root/drivers/gpu/drm/drm_dp_mst_topology.c

DEFINITIONS

1. drm_dp_mst_req_type_str
2. drm_dp_mst_nak_reason_str
3. drm_dp_msg_header_crc4
4. drm_dp_msg_data_crc4
5. drm_dp_calc_sb_hdr_size
6. drm_dp_encode_sideband_msg_hdr
7. drm_dp_decode_sideband_msg_hdr
8. drm_dp_encode_sideband_req
9. drm_dp_crc_sideband_chunk_req
10. drm_dp_encode_sideband_reply
11. drm_dp_sideband_msg_build
12. drm_dp_sideband_parse_link_address
13. drm_dp_sideband_parse_remote_dpcd_read
14. drm_dp_sideband_parse_remote_dpcd_write
15. drm_dp_sideband_parse_remote_i2c_read_ack
16. drm_dp_sideband_parse_enum_path_resources_ack
17. drm_dp_sideband_parse_allocate_payload_ack
18. drm_dp_sideband_parse_query_payload_ack
19. drm_dp_sideband_parse_power_updown_phy_ack
20. drm_dp_sideband_parse_reply
21. drm_dp_sideband_parse_connection_status_notify
22. drm_dp_sideband_parse_resource_status_notify
23. drm_dp_sideband_parse_req
24. build_dpcd_write
25. build_link_address
26. build_enum_path_resources
27. build_allocate_payload
28. build_power_updown_phy
29. drm_dp_mst_assign_payload_id
30. drm_dp_mst_put_payload_id
31. check_txmsg_state
32. drm_dp_mst_wait_tx_reply
33. drm_dp_add_mst_branch_device
34. drm_dp_free_mst_branch_device
35. drm_dp_mst_get_mstb_malloc
36. drm_dp_mst_put_mstb_malloc
37. drm_dp_free_mst_port
38. drm_dp_mst_get_port_malloc
39. drm_dp_mst_put_port_malloc
40. drm_dp_destroy_mst_branch_device
41. drm_dp_mst_topology_try_get_mstb
42. drm_dp_mst_topology_get_mstb
43. drm_dp_mst_topology_put_mstb
44. drm_dp_port_teardown_pdt
45. drm_dp_destroy_port
46. drm_dp_mst_topology_try_get_port
47. drm_dp_mst_topology_get_port
48. drm_dp_mst_topology_put_port
49. drm_dp_mst_topology_get_mstb_validated_locked
50. drm_dp_mst_topology_get_mstb_validated
51. drm_dp_mst_topology_get_port_validated_locked
52. drm_dp_mst_topology_get_port_validated
53. drm_dp_get_port
54. drm_dp_calculate_rad
55. drm_dp_port_setup_pdt
56. drm_dp_mst_dpcd_read
57. drm_dp_mst_dpcd_write
58. drm_dp_check_mstb_guid
59. build_mst_prop_path
60. drm_dp_mst_connector_late_register
61. drm_dp_mst_connector_early_unregister
62. drm_dp_add_port
63. drm_dp_update_port
64. drm_dp_get_mst_branch_device
65. get_mst_branch_device_by_guid_helper
66. drm_dp_get_mst_branch_device_by_guid
67. drm_dp_check_and_send_link_address
68. drm_dp_mst_link_probe_work
69. drm_dp_validate_guid
70. build_dpcd_read
71. drm_dp_send_sideband_msg
72. set_hdr_from_dst_qlock
73. process_single_tx_qlock
74. process_single_down_tx_qlock
75. process_single_up_tx_qlock
76. drm_dp_queue_down_tx
77. drm_dp_send_link_address
78. drm_dp_send_enum_path_resources
79. drm_dp_get_last_connected_port_to_mstb
80. drm_dp_get_last_connected_port_and_mstb
81. drm_dp_payload_send_msg
82. drm_dp_send_power_updown_phy
83. drm_dp_create_payload_step1
84. drm_dp_create_payload_step2
85. drm_dp_destroy_payload_step1
86. drm_dp_destroy_payload_step2
87. drm_dp_update_payload_part1
88. drm_dp_update_payload_part2
89. drm_dp_send_dpcd_read
90. drm_dp_send_dpcd_write
91. drm_dp_encode_up_ack_reply
92. drm_dp_send_up_ack_reply
93. drm_dp_get_vc_payload_bw
94. drm_dp_mst_topology_mgr_set_mst
95. drm_dp_mst_topology_mgr_suspend
96. drm_dp_mst_topology_mgr_resume
97. drm_dp_get_one_sb_msg
98. drm_dp_mst_handle_down_rep
99. drm_dp_mst_handle_up_req
100. drm_dp_mst_hpd_irq
101. drm_dp_mst_detect_port
102. drm_dp_mst_port_has_audio
103. drm_dp_mst_get_edid
104. drm_dp_find_vcpi_slots
105. drm_dp_init_vcpi
106. drm_dp_atomic_find_vcpi_slots
107. drm_dp_atomic_release_vcpi_slots
108. drm_dp_mst_allocate_vcpi
109. drm_dp_mst_get_vcpi_slots
110. drm_dp_mst_reset_vcpi_slots
111. drm_dp_mst_deallocate_vcpi
112. drm_dp_dpcd_write_payload
113. drm_dp_check_act_status
114. drm_dp_calc_pbn_mode
115. test_calc_pbn_mode
116. drm_dp_mst_kick_tx
117. drm_dp_mst_dump_mstb
118. dump_dp_payload_table
119. fetch_monitor_name
120. drm_dp_mst_dump_topology
121. drm_dp_tx_work
122. drm_dp_destroy_connector_work
123. drm_dp_mst_duplicate_state
124. drm_dp_mst_destroy_state
125. drm_dp_mst_atomic_check_topology_state
126. drm_dp_mst_atomic_check
127. drm_atomic_get_mst_topology_state
128. drm_dp_mst_topology_mgr_init
129. drm_dp_mst_topology_mgr_destroy
130. remote_i2c_read_ok
131. drm_dp_mst_i2c_xfer
132. drm_dp_mst_i2c_functionality
133. drm_dp_mst_register_i2c_bus
134. drm_dp_mst_unregister_i2c_bus

   1 /*
   2  * Copyright © 2014 Red Hat
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and its
   5  * documentation for any purpose is hereby granted without fee, provided that
   6  * the above copyright notice appear in all copies and that both that copyright
   7  * notice and this permission notice appear in supporting documentation, and
   8  * that the name of the copyright holders not be used in advertising or
   9  * publicity pertaining to distribution of the software without specific,
  10  * written prior permission.  The copyright holders make no representations
  11  * about the suitability of this software for any purpose.  It is provided "as
  12  * is" without express or implied warranty.
  13  *
  14  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  16  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  20  * OF THIS SOFTWARE.
  21  */
  22 
  23 #include <linux/delay.h>
  24 #include <linux/errno.h>
  25 #include <linux/i2c.h>
  26 #include <linux/init.h>
  27 #include <linux/kernel.h>
  28 #include <linux/sched.h>
  29 #include <linux/seq_file.h>
  30 
  31 #include <drm/drm_atomic.h>
  32 #include <drm/drm_atomic_helper.h>
  33 #include <drm/drm_dp_mst_helper.h>
  34 #include <drm/drm_drv.h>
  35 #include <drm/drm_fixed.h>
  36 #include <drm/drm_print.h>
  37 #include <drm/drm_probe_helper.h>
  38 
  39 #include "drm_crtc_helper_internal.h"
  40 
  41 /**
  42  * DOC: dp mst helper
  43  *
  44  * These functions contain parts of the DisplayPort 1.2a MultiStream Transport
  45  * protocol. The helpers contain a topology manager and bandwidth manager.
  46  * The helpers encapsulate the sending and received of sideband msgs.
  47  */
  48 static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
  49                                   char *buf);
  50 static int test_calc_pbn_mode(void);
  51 
  52 static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port);
  53 
  54 static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
  55                                      int id,
  56                                      struct drm_dp_payload *payload);
  57 
  58 static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
  59                                  struct drm_dp_mst_port *port,
  60                                  int offset, int size, u8 *bytes);
  61 static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
  62                                   struct drm_dp_mst_port *port,
  63                                   int offset, int size, u8 *bytes);
  64 
  65 static void drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
  66                                      struct drm_dp_mst_branch *mstb);
  67 static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
  68                                            struct drm_dp_mst_branch *mstb,
  69                                            struct drm_dp_mst_port *port);
  70 static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
  71                                  u8 *guid);
  72 
  73 static int drm_dp_mst_register_i2c_bus(struct drm_dp_aux *aux);
  74 static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_aux *aux);
  75 static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr);
  76 
  77 #define DP_STR(x) [DP_ ## x] = #x
  78 
  79 static const char *drm_dp_mst_req_type_str(u8 req_type)
  80 {
  81         static const char * const req_type_str[] = {
  82                 DP_STR(GET_MSG_TRANSACTION_VERSION),
  83                 DP_STR(LINK_ADDRESS),
  84                 DP_STR(CONNECTION_STATUS_NOTIFY),
  85                 DP_STR(ENUM_PATH_RESOURCES),
  86                 DP_STR(ALLOCATE_PAYLOAD),
  87                 DP_STR(QUERY_PAYLOAD),
  88                 DP_STR(RESOURCE_STATUS_NOTIFY),
  89                 DP_STR(CLEAR_PAYLOAD_ID_TABLE),
  90                 DP_STR(REMOTE_DPCD_READ),
  91                 DP_STR(REMOTE_DPCD_WRITE),
  92                 DP_STR(REMOTE_I2C_READ),
  93                 DP_STR(REMOTE_I2C_WRITE),
  94                 DP_STR(POWER_UP_PHY),
  95                 DP_STR(POWER_DOWN_PHY),
  96                 DP_STR(SINK_EVENT_NOTIFY),
  97                 DP_STR(QUERY_STREAM_ENC_STATUS),
  98         };
  99 
 100         if (req_type >= ARRAY_SIZE(req_type_str) ||
 101             !req_type_str[req_type])
 102                 return "unknown";
 103 
 104         return req_type_str[req_type];
 105 }
 106 
 107 #undef DP_STR
 108 #define DP_STR(x) [DP_NAK_ ## x] = #x
 109 
 110 static const char *drm_dp_mst_nak_reason_str(u8 nak_reason)
 111 {
 112         static const char * const nak_reason_str[] = {
 113                 DP_STR(WRITE_FAILURE),
 114                 DP_STR(INVALID_READ),
 115                 DP_STR(CRC_FAILURE),
 116                 DP_STR(BAD_PARAM),
 117                 DP_STR(DEFER),
 118                 DP_STR(LINK_FAILURE),
 119                 DP_STR(NO_RESOURCES),
 120                 DP_STR(DPCD_FAIL),
 121                 DP_STR(I2C_NAK),
 122                 DP_STR(ALLOCATE_FAIL),
 123         };
 124 
 125         if (nak_reason >= ARRAY_SIZE(nak_reason_str) ||
 126             !nak_reason_str[nak_reason])
 127                 return "unknown";
 128 
 129         return nak_reason_str[nak_reason];
 130 }
 131 
 132 #undef DP_STR
 133 
 134 /* sideband msg handling */
 135 static u8 drm_dp_msg_header_crc4(const uint8_t *data, size_t num_nibbles)
 136 {
 137         u8 bitmask = 0x80;
 138         u8 bitshift = 7;
 139         u8 array_index = 0;
 140         int number_of_bits = num_nibbles * 4;
 141         u8 remainder = 0;
 142 
 143         while (number_of_bits != 0) {
 144                 number_of_bits--;
 145                 remainder <<= 1;
 146                 remainder |= (data[array_index] & bitmask) >> bitshift;
 147                 bitmask >>= 1;
 148                 bitshift--;
 149                 if (bitmask == 0) {
 150                         bitmask = 0x80;
 151                         bitshift = 7;
 152                         array_index++;
 153                 }
 154                 if ((remainder & 0x10) == 0x10)
 155                         remainder ^= 0x13;
 156         }
 157 
 158         number_of_bits = 4;
 159         while (number_of_bits != 0) {
 160                 number_of_bits--;
 161                 remainder <<= 1;
 162                 if ((remainder & 0x10) != 0)
 163                         remainder ^= 0x13;
 164         }
 165 
 166         return remainder;
 167 }
 168 
 169 static u8 drm_dp_msg_data_crc4(const uint8_t *data, u8 number_of_bytes)
 170 {
 171         u8 bitmask = 0x80;
 172         u8 bitshift = 7;
 173         u8 array_index = 0;
 174         int number_of_bits = number_of_bytes * 8;
 175         u16 remainder = 0;
 176 
 177         while (number_of_bits != 0) {
 178                 number_of_bits--;
 179                 remainder <<= 1;
 180                 remainder |= (data[array_index] & bitmask) >> bitshift;
 181                 bitmask >>= 1;
 182                 bitshift--;
 183                 if (bitmask == 0) {
 184                         bitmask = 0x80;
 185                         bitshift = 7;
 186                         array_index++;
 187                 }
 188                 if ((remainder & 0x100) == 0x100)
 189                         remainder ^= 0xd5;
 190         }
 191 
 192         number_of_bits = 8;
 193         while (number_of_bits != 0) {
 194                 number_of_bits--;
 195                 remainder <<= 1;
 196                 if ((remainder & 0x100) != 0)
 197                         remainder ^= 0xd5;
 198         }
 199 
 200         return remainder & 0xff;
 201 }
 202 static inline u8 drm_dp_calc_sb_hdr_size(struct drm_dp_sideband_msg_hdr *hdr)
 203 {
 204         u8 size = 3;
 205         size += (hdr->lct / 2);
 206         return size;
 207 }
 208 
 209 static void drm_dp_encode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr,
 210                                            u8 *buf, int *len)
 211 {
 212         int idx = 0;
 213         int i;
 214         u8 crc4;
 215         buf[idx++] = ((hdr->lct & 0xf) << 4) | (hdr->lcr & 0xf);
 216         for (i = 0; i < (hdr->lct / 2); i++)
 217                 buf[idx++] = hdr->rad[i];
 218         buf[idx++] = (hdr->broadcast << 7) | (hdr->path_msg << 6) |
 219                 (hdr->msg_len & 0x3f);
 220         buf[idx++] = (hdr->somt << 7) | (hdr->eomt << 6) | (hdr->seqno << 4);
 221 
 222         crc4 = drm_dp_msg_header_crc4(buf, (idx * 2) - 1);
 223         buf[idx - 1] |= (crc4 & 0xf);
 224 
 225         *len = idx;
 226 }
 227 
 228 static bool drm_dp_decode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr,
 229                                            u8 *buf, int buflen, u8 *hdrlen)
 230 {
 231         u8 crc4;
 232         u8 len;
 233         int i;
 234         u8 idx;
 235         if (buf[0] == 0)
 236                 return false;
 237         len = 3;
 238         len += ((buf[0] & 0xf0) >> 4) / 2;
 239         if (len > buflen)
 240                 return false;
 241         crc4 = drm_dp_msg_header_crc4(buf, (len * 2) - 1);
 242 
 243         if ((crc4 & 0xf) != (buf[len - 1] & 0xf)) {
 244                 DRM_DEBUG_KMS("crc4 mismatch 0x%x 0x%x\n", crc4, buf[len - 1]);
 245                 return false;
 246         }
 247 
 248         hdr->lct = (buf[0] & 0xf0) >> 4;
 249         hdr->lcr = (buf[0] & 0xf);
 250         idx = 1;
 251         for (i = 0; i < (hdr->lct / 2); i++)
 252                 hdr->rad[i] = buf[idx++];
 253         hdr->broadcast = (buf[idx] >> 7) & 0x1;
 254         hdr->path_msg = (buf[idx] >> 6) & 0x1;
 255         hdr->msg_len = buf[idx] & 0x3f;
 256         idx++;
 257         hdr->somt = (buf[idx] >> 7) & 0x1;
 258         hdr->eomt = (buf[idx] >> 6) & 0x1;
 259         hdr->seqno = (buf[idx] >> 4) & 0x1;
 260         idx++;
 261         *hdrlen = idx;
 262         return true;
 263 }
 264 
 265 static void drm_dp_encode_sideband_req(struct drm_dp_sideband_msg_req_body *req,
 266                                        struct drm_dp_sideband_msg_tx *raw)
 267 {
 268         int idx = 0;
 269         int i;
 270         u8 *buf = raw->msg;
 271         buf[idx++] = req->req_type & 0x7f;
 272 
 273         switch (req->req_type) {
 274         case DP_ENUM_PATH_RESOURCES:
 275                 buf[idx] = (req->u.port_num.port_number & 0xf) << 4;
 276                 idx++;
 277                 break;
 278         case DP_ALLOCATE_PAYLOAD:
 279                 buf[idx] = (req->u.allocate_payload.port_number & 0xf) << 4 |
 280                         (req->u.allocate_payload.number_sdp_streams & 0xf);
 281                 idx++;
 282                 buf[idx] = (req->u.allocate_payload.vcpi & 0x7f);
 283                 idx++;
 284                 buf[idx] = (req->u.allocate_payload.pbn >> 8);
 285                 idx++;
 286                 buf[idx] = (req->u.allocate_payload.pbn & 0xff);
 287                 idx++;
 288                 for (i = 0; i < req->u.allocate_payload.number_sdp_streams / 2; i++) {
 289                         buf[idx] = ((req->u.allocate_payload.sdp_stream_sink[i * 2] & 0xf) << 4) |
 290                                 (req->u.allocate_payload.sdp_stream_sink[i * 2 + 1] & 0xf);
 291                         idx++;
 292                 }
 293                 if (req->u.allocate_payload.number_sdp_streams & 1) {
 294                         i = req->u.allocate_payload.number_sdp_streams - 1;
 295                         buf[idx] = (req->u.allocate_payload.sdp_stream_sink[i] & 0xf) << 4;
 296                         idx++;
 297                 }
 298                 break;
 299         case DP_QUERY_PAYLOAD:
 300                 buf[idx] = (req->u.query_payload.port_number & 0xf) << 4;
 301                 idx++;
 302                 buf[idx] = (req->u.query_payload.vcpi & 0x7f);
 303                 idx++;
 304                 break;
 305         case DP_REMOTE_DPCD_READ:
 306                 buf[idx] = (req->u.dpcd_read.port_number & 0xf) << 4;
 307                 buf[idx] |= ((req->u.dpcd_read.dpcd_address & 0xf0000) >> 16) & 0xf;
 308                 idx++;
 309                 buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff00) >> 8;
 310                 idx++;
 311                 buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff);
 312                 idx++;
 313                 buf[idx] = (req->u.dpcd_read.num_bytes);
 314                 idx++;
 315                 break;
 316 
 317         case DP_REMOTE_DPCD_WRITE:
 318                 buf[idx] = (req->u.dpcd_write.port_number & 0xf) << 4;
 319                 buf[idx] |= ((req->u.dpcd_write.dpcd_address & 0xf0000) >> 16) & 0xf;
 320                 idx++;
 321                 buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff00) >> 8;
 322                 idx++;
 323                 buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff);
 324                 idx++;
 325                 buf[idx] = (req->u.dpcd_write.num_bytes);
 326                 idx++;
 327                 memcpy(&buf[idx], req->u.dpcd_write.bytes, req->u.dpcd_write.num_bytes);
 328                 idx += req->u.dpcd_write.num_bytes;
 329                 break;
 330         case DP_REMOTE_I2C_READ:
 331                 buf[idx] = (req->u.i2c_read.port_number & 0xf) << 4;
 332                 buf[idx] |= (req->u.i2c_read.num_transactions & 0x3);
 333                 idx++;
 334                 for (i = 0; i < (req->u.i2c_read.num_transactions & 0x3); i++) {
 335                         buf[idx] = req->u.i2c_read.transactions[i].i2c_dev_id & 0x7f;
 336                         idx++;
 337                         buf[idx] = req->u.i2c_read.transactions[i].num_bytes;
 338                         idx++;
 339                         memcpy(&buf[idx], req->u.i2c_read.transactions[i].bytes, req->u.i2c_read.transactions[i].num_bytes);
 340                         idx += req->u.i2c_read.transactions[i].num_bytes;
 341 
 342                         buf[idx] = (req->u.i2c_read.transactions[i].no_stop_bit & 0x1) << 4;
 343                         buf[idx] |= (req->u.i2c_read.transactions[i].i2c_transaction_delay & 0xf);
 344                         idx++;
 345                 }
 346                 buf[idx] = (req->u.i2c_read.read_i2c_device_id) & 0x7f;
 347                 idx++;
 348                 buf[idx] = (req->u.i2c_read.num_bytes_read);
 349                 idx++;
 350                 break;
 351 
 352         case DP_REMOTE_I2C_WRITE:
 353                 buf[idx] = (req->u.i2c_write.port_number & 0xf) << 4;
 354                 idx++;
 355                 buf[idx] = (req->u.i2c_write.write_i2c_device_id) & 0x7f;
 356                 idx++;
 357                 buf[idx] = (req->u.i2c_write.num_bytes);
 358                 idx++;
 359                 memcpy(&buf[idx], req->u.i2c_write.bytes, req->u.i2c_write.num_bytes);
 360                 idx += req->u.i2c_write.num_bytes;
 361                 break;
 362 
 363         case DP_POWER_DOWN_PHY:
 364         case DP_POWER_UP_PHY:
 365                 buf[idx] = (req->u.port_num.port_number & 0xf) << 4;
 366                 idx++;
 367                 break;
 368         }
 369         raw->cur_len = idx;
 370 }
 371 
 372 static void drm_dp_crc_sideband_chunk_req(u8 *msg, u8 len)
 373 {
 374         u8 crc4;
 375         crc4 = drm_dp_msg_data_crc4(msg, len);
 376         msg[len] = crc4;
 377 }
 378 
 379 static void drm_dp_encode_sideband_reply(struct drm_dp_sideband_msg_reply_body *rep,
 380                                          struct drm_dp_sideband_msg_tx *raw)
 381 {
 382         int idx = 0;
 383         u8 *buf = raw->msg;
 384 
 385         buf[idx++] = (rep->reply_type & 0x1) << 7 | (rep->req_type & 0x7f);
 386 
 387         raw->cur_len = idx;
 388 }
 389 
 390 /* this adds a chunk of msg to the builder to get the final msg */
 391 static bool drm_dp_sideband_msg_build(struct drm_dp_sideband_msg_rx *msg,
 392                                       u8 *replybuf, u8 replybuflen, bool hdr)
 393 {
 394         int ret;
 395         u8 crc4;
 396 
 397         if (hdr) {
 398                 u8 hdrlen;
 399                 struct drm_dp_sideband_msg_hdr recv_hdr;
 400                 ret = drm_dp_decode_sideband_msg_hdr(&recv_hdr, replybuf, replybuflen, &hdrlen);
 401                 if (ret == false) {
 402                         print_hex_dump(KERN_DEBUG, "failed hdr", DUMP_PREFIX_NONE, 16, 1, replybuf, replybuflen, false);
 403                         return false;
 404                 }
 405 
 406                 /*
 407                  * ignore out-of-order messages or messages that are part of a
 408                  * failed transaction
 409                  */
 410                 if (!recv_hdr.somt && !msg->have_somt)
 411                         return false;
 412 
 413                 /* get length contained in this portion */
 414                 msg->curchunk_len = recv_hdr.msg_len;
 415                 msg->curchunk_hdrlen = hdrlen;
 416 
 417                 /* we have already gotten an somt - don't bother parsing */
 418                 if (recv_hdr.somt && msg->have_somt)
 419                         return false;
 420 
 421                 if (recv_hdr.somt) {
 422                         memcpy(&msg->initial_hdr, &recv_hdr, sizeof(struct drm_dp_sideband_msg_hdr));
 423                         msg->have_somt = true;
 424                 }
 425                 if (recv_hdr.eomt)
 426                         msg->have_eomt = true;
 427 
 428                 /* copy the bytes for the remainder of this header chunk */
 429                 msg->curchunk_idx = min(msg->curchunk_len, (u8)(replybuflen - hdrlen));
 430                 memcpy(&msg->chunk[0], replybuf + hdrlen, msg->curchunk_idx);
 431         } else {
 432                 memcpy(&msg->chunk[msg->curchunk_idx], replybuf, replybuflen);
 433                 msg->curchunk_idx += replybuflen;
 434         }
 435 
 436         if (msg->curchunk_idx >= msg->curchunk_len) {
 437                 /* do CRC */
 438                 crc4 = drm_dp_msg_data_crc4(msg->chunk, msg->curchunk_len - 1);
 439                 /* copy chunk into bigger msg */
 440                 memcpy(&msg->msg[msg->curlen], msg->chunk, msg->curchunk_len - 1);
 441                 msg->curlen += msg->curchunk_len - 1;
 442         }
 443         return true;
 444 }
 445 
 446 static bool drm_dp_sideband_parse_link_address(struct drm_dp_sideband_msg_rx *raw,
 447                                                struct drm_dp_sideband_msg_reply_body *repmsg)
 448 {
 449         int idx = 1;
 450         int i;
 451         memcpy(repmsg->u.link_addr.guid, &raw->msg[idx], 16);
 452         idx += 16;
 453         repmsg->u.link_addr.nports = raw->msg[idx] & 0xf;
 454         idx++;
 455         if (idx > raw->curlen)
 456                 goto fail_len;
 457         for (i = 0; i < repmsg->u.link_addr.nports; i++) {
 458                 if (raw->msg[idx] & 0x80)
 459                         repmsg->u.link_addr.ports[i].input_port = 1;
 460 
 461                 repmsg->u.link_addr.ports[i].peer_device_type = (raw->msg[idx] >> 4) & 0x7;
 462                 repmsg->u.link_addr.ports[i].port_number = (raw->msg[idx] & 0xf);
 463 
 464                 idx++;
 465                 if (idx > raw->curlen)
 466                         goto fail_len;
 467                 repmsg->u.link_addr.ports[i].mcs = (raw->msg[idx] >> 7) & 0x1;
 468                 repmsg->u.link_addr.ports[i].ddps = (raw->msg[idx] >> 6) & 0x1;
 469                 if (repmsg->u.link_addr.ports[i].input_port == 0)
 470                         repmsg->u.link_addr.ports[i].legacy_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
 471                 idx++;
 472                 if (idx > raw->curlen)
 473                         goto fail_len;
 474                 if (repmsg->u.link_addr.ports[i].input_port == 0) {
 475                         repmsg->u.link_addr.ports[i].dpcd_revision = (raw->msg[idx]);
 476                         idx++;
 477                         if (idx > raw->curlen)
 478                                 goto fail_len;
 479                         memcpy(repmsg->u.link_addr.ports[i].peer_guid, &raw->msg[idx], 16);
 480                         idx += 16;
 481                         if (idx > raw->curlen)
 482                                 goto fail_len;
 483                         repmsg->u.link_addr.ports[i].num_sdp_streams = (raw->msg[idx] >> 4) & 0xf;
 484                         repmsg->u.link_addr.ports[i].num_sdp_stream_sinks = (raw->msg[idx] & 0xf);
 485                         idx++;
 486 
 487                 }
 488                 if (idx > raw->curlen)
 489                         goto fail_len;
 490         }
 491 
 492         return true;
 493 fail_len:
 494         DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
 495         return false;
 496 }
 497 
 498 static bool drm_dp_sideband_parse_remote_dpcd_read(struct drm_dp_sideband_msg_rx *raw,
 499                                                    struct drm_dp_sideband_msg_reply_body *repmsg)
 500 {
 501         int idx = 1;
 502         repmsg->u.remote_dpcd_read_ack.port_number = raw->msg[idx] & 0xf;
 503         idx++;
 504         if (idx > raw->curlen)
 505                 goto fail_len;
 506         repmsg->u.remote_dpcd_read_ack.num_bytes = raw->msg[idx];
 507         idx++;
 508         if (idx > raw->curlen)
 509                 goto fail_len;
 510 
 511         memcpy(repmsg->u.remote_dpcd_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_dpcd_read_ack.num_bytes);
 512         return true;
 513 fail_len:
 514         DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
 515         return false;
 516 }
 517 
 518 static bool drm_dp_sideband_parse_remote_dpcd_write(struct drm_dp_sideband_msg_rx *raw,
 519                                                       struct drm_dp_sideband_msg_reply_body *repmsg)
 520 {
 521         int idx = 1;
 522         repmsg->u.remote_dpcd_write_ack.port_number = raw->msg[idx] & 0xf;
 523         idx++;
 524         if (idx > raw->curlen)
 525                 goto fail_len;
 526         return true;
 527 fail_len:
 528         DRM_DEBUG_KMS("parse length fail %d %d\n", idx, raw->curlen);
 529         return false;
 530 }
 531 
 532 static bool drm_dp_sideband_parse_remote_i2c_read_ack(struct drm_dp_sideband_msg_rx *raw,
 533                                                       struct drm_dp_sideband_msg_reply_body *repmsg)
 534 {
 535         int idx = 1;
 536 
 537         repmsg->u.remote_i2c_read_ack.port_number = (raw->msg[idx] & 0xf);
 538         idx++;
 539         if (idx > raw->curlen)
 540                 goto fail_len;
 541         repmsg->u.remote_i2c_read_ack.num_bytes = raw->msg[idx];
 542         idx++;
 543         /* TODO check */
 544         memcpy(repmsg->u.remote_i2c_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_i2c_read_ack.num_bytes);
 545         return true;
 546 fail_len:
 547         DRM_DEBUG_KMS("remote i2c reply parse length fail %d %d\n", idx, raw->curlen);
 548         return false;
 549 }
 550 
 551 static bool drm_dp_sideband_parse_enum_path_resources_ack(struct drm_dp_sideband_msg_rx *raw,
 552                                                           struct drm_dp_sideband_msg_reply_body *repmsg)
 553 {
 554         int idx = 1;
 555         repmsg->u.path_resources.port_number = (raw->msg[idx] >> 4) & 0xf;
 556         idx++;
 557         if (idx > raw->curlen)
 558                 goto fail_len;
 559         repmsg->u.path_resources.full_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
 560         idx += 2;
 561         if (idx > raw->curlen)
 562                 goto fail_len;
 563         repmsg->u.path_resources.avail_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
 564         idx += 2;
 565         if (idx > raw->curlen)
 566                 goto fail_len;
 567         return true;
 568 fail_len:
 569         DRM_DEBUG_KMS("enum resource parse length fail %d %d\n", idx, raw->curlen);
 570         return false;
 571 }
 572 
 573 static bool drm_dp_sideband_parse_allocate_payload_ack(struct drm_dp_sideband_msg_rx *raw,
 574                                                           struct drm_dp_sideband_msg_reply_body *repmsg)
 575 {
 576         int idx = 1;
 577         repmsg->u.allocate_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
 578         idx++;
 579         if (idx > raw->curlen)
 580                 goto fail_len;
 581         repmsg->u.allocate_payload.vcpi = raw->msg[idx];
 582         idx++;
 583         if (idx > raw->curlen)
 584                 goto fail_len;
 585         repmsg->u.allocate_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
 586         idx += 2;
 587         if (idx > raw->curlen)
 588                 goto fail_len;
 589         return true;
 590 fail_len:
 591         DRM_DEBUG_KMS("allocate payload parse length fail %d %d\n", idx, raw->curlen);
 592         return false;
 593 }
 594 
 595 static bool drm_dp_sideband_parse_query_payload_ack(struct drm_dp_sideband_msg_rx *raw,
 596                                                     struct drm_dp_sideband_msg_reply_body *repmsg)
 597 {
 598         int idx = 1;
 599         repmsg->u.query_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
 600         idx++;
 601         if (idx > raw->curlen)
 602                 goto fail_len;
 603         repmsg->u.query_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
 604         idx += 2;
 605         if (idx > raw->curlen)
 606                 goto fail_len;
 607         return true;
 608 fail_len:
 609         DRM_DEBUG_KMS("query payload parse length fail %d %d\n", idx, raw->curlen);
 610         return false;
 611 }
 612 
 613 static bool drm_dp_sideband_parse_power_updown_phy_ack(struct drm_dp_sideband_msg_rx *raw,
 614                                                        struct drm_dp_sideband_msg_reply_body *repmsg)
 615 {
 616         int idx = 1;
 617 
 618         repmsg->u.port_number.port_number = (raw->msg[idx] >> 4) & 0xf;
 619         idx++;
 620         if (idx > raw->curlen) {
 621                 DRM_DEBUG_KMS("power up/down phy parse length fail %d %d\n",
 622                               idx, raw->curlen);
 623                 return false;
 624         }
 625         return true;
 626 }
 627 
 628 static bool drm_dp_sideband_parse_reply(struct drm_dp_sideband_msg_rx *raw,
 629                                         struct drm_dp_sideband_msg_reply_body *msg)
 630 {
 631         memset(msg, 0, sizeof(*msg));
 632         msg->reply_type = (raw->msg[0] & 0x80) >> 7;
 633         msg->req_type = (raw->msg[0] & 0x7f);
 634 
 635         if (msg->reply_type == DP_SIDEBAND_REPLY_NAK) {
 636                 memcpy(msg->u.nak.guid, &raw->msg[1], 16);
 637                 msg->u.nak.reason = raw->msg[17];
 638                 msg->u.nak.nak_data = raw->msg[18];
 639                 return false;
 640         }
 641 
 642         switch (msg->req_type) {
 643         case DP_LINK_ADDRESS:
 644                 return drm_dp_sideband_parse_link_address(raw, msg);
 645         case DP_QUERY_PAYLOAD:
 646                 return drm_dp_sideband_parse_query_payload_ack(raw, msg);
 647         case DP_REMOTE_DPCD_READ:
 648                 return drm_dp_sideband_parse_remote_dpcd_read(raw, msg);
 649         case DP_REMOTE_DPCD_WRITE:
 650                 return drm_dp_sideband_parse_remote_dpcd_write(raw, msg);
 651         case DP_REMOTE_I2C_READ:
 652                 return drm_dp_sideband_parse_remote_i2c_read_ack(raw, msg);
 653         case DP_ENUM_PATH_RESOURCES:
 654                 return drm_dp_sideband_parse_enum_path_resources_ack(raw, msg);
 655         case DP_ALLOCATE_PAYLOAD:
 656                 return drm_dp_sideband_parse_allocate_payload_ack(raw, msg);
 657         case DP_POWER_DOWN_PHY:
 658         case DP_POWER_UP_PHY:
 659                 return drm_dp_sideband_parse_power_updown_phy_ack(raw, msg);
 660         default:
 661                 DRM_ERROR("Got unknown reply 0x%02x (%s)\n", msg->req_type,
 662                           drm_dp_mst_req_type_str(msg->req_type));
 663                 return false;
 664         }
 665 }
 666 
 667 static bool drm_dp_sideband_parse_connection_status_notify(struct drm_dp_sideband_msg_rx *raw,
 668                                                            struct drm_dp_sideband_msg_req_body *msg)
 669 {
 670         int idx = 1;
 671 
 672         msg->u.conn_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
 673         idx++;
 674         if (idx > raw->curlen)
 675                 goto fail_len;
 676 
 677         memcpy(msg->u.conn_stat.guid, &raw->msg[idx], 16);
 678         idx += 16;
 679         if (idx > raw->curlen)
 680                 goto fail_len;
 681 
 682         msg->u.conn_stat.legacy_device_plug_status = (raw->msg[idx] >> 6) & 0x1;
 683         msg->u.conn_stat.displayport_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
 684         msg->u.conn_stat.message_capability_status = (raw->msg[idx] >> 4) & 0x1;
 685         msg->u.conn_stat.input_port = (raw->msg[idx] >> 3) & 0x1;
 686         msg->u.conn_stat.peer_device_type = (raw->msg[idx] & 0x7);
 687         idx++;
 688         return true;
 689 fail_len:
 690         DRM_DEBUG_KMS("connection status reply parse length fail %d %d\n", idx, raw->curlen);
 691         return false;
 692 }
 693 
 694 static bool drm_dp_sideband_parse_resource_status_notify(struct drm_dp_sideband_msg_rx *raw,
 695                                                            struct drm_dp_sideband_msg_req_body *msg)
 696 {
 697         int idx = 1;
 698 
 699         msg->u.resource_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
 700         idx++;
 701         if (idx > raw->curlen)
 702                 goto fail_len;
 703 
 704         memcpy(msg->u.resource_stat.guid, &raw->msg[idx], 16);
 705         idx += 16;
 706         if (idx > raw->curlen)
 707                 goto fail_len;
 708 
 709         msg->u.resource_stat.available_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
 710         idx++;
 711         return true;
 712 fail_len:
 713         DRM_DEBUG_KMS("resource status reply parse length fail %d %d\n", idx, raw->curlen);
 714         return false;
 715 }
 716 
 717 static bool drm_dp_sideband_parse_req(struct drm_dp_sideband_msg_rx *raw,
 718                                       struct drm_dp_sideband_msg_req_body *msg)
 719 {
 720         memset(msg, 0, sizeof(*msg));
 721         msg->req_type = (raw->msg[0] & 0x7f);
 722 
 723         switch (msg->req_type) {
 724         case DP_CONNECTION_STATUS_NOTIFY:
 725                 return drm_dp_sideband_parse_connection_status_notify(raw, msg);
 726         case DP_RESOURCE_STATUS_NOTIFY:
 727                 return drm_dp_sideband_parse_resource_status_notify(raw, msg);
 728         default:
 729                 DRM_ERROR("Got unknown request 0x%02x (%s)\n", msg->req_type,
 730                           drm_dp_mst_req_type_str(msg->req_type));
 731                 return false;
 732         }
 733 }
 734 
 735 static int build_dpcd_write(struct drm_dp_sideband_msg_tx *msg, u8 port_num, u32 offset, u8 num_bytes, u8 *bytes)
 736 {
 737         struct drm_dp_sideband_msg_req_body req;
 738 
 739         req.req_type = DP_REMOTE_DPCD_WRITE;
 740         req.u.dpcd_write.port_number = port_num;
 741         req.u.dpcd_write.dpcd_address = offset;
 742         req.u.dpcd_write.num_bytes = num_bytes;
 743         req.u.dpcd_write.bytes = bytes;
 744         drm_dp_encode_sideband_req(&req, msg);
 745 
 746         return 0;
 747 }
 748 
 749 static int build_link_address(struct drm_dp_sideband_msg_tx *msg)
 750 {
 751         struct drm_dp_sideband_msg_req_body req;
 752 
 753         req.req_type = DP_LINK_ADDRESS;
 754         drm_dp_encode_sideband_req(&req, msg);
 755         return 0;
 756 }
 757 
 758 static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg, int port_num)
 759 {
 760         struct drm_dp_sideband_msg_req_body req;
 761 
 762         req.req_type = DP_ENUM_PATH_RESOURCES;
 763         req.u.port_num.port_number = port_num;
 764         drm_dp_encode_sideband_req(&req, msg);
 765         msg->path_msg = true;
 766         return 0;
 767 }
 768 
 769 static int build_allocate_payload(struct drm_dp_sideband_msg_tx *msg, int port_num,
 770                                   u8 vcpi, uint16_t pbn,
 771                                   u8 number_sdp_streams,
 772                                   u8 *sdp_stream_sink)
 773 {
 774         struct drm_dp_sideband_msg_req_body req;
 775         memset(&req, 0, sizeof(req));
 776         req.req_type = DP_ALLOCATE_PAYLOAD;
 777         req.u.allocate_payload.port_number = port_num;
 778         req.u.allocate_payload.vcpi = vcpi;
 779         req.u.allocate_payload.pbn = pbn;
 780         req.u.allocate_payload.number_sdp_streams = number_sdp_streams;
 781         memcpy(req.u.allocate_payload.sdp_stream_sink, sdp_stream_sink,
 782                    number_sdp_streams);
 783         drm_dp_encode_sideband_req(&req, msg);
 784         msg->path_msg = true;
 785         return 0;
 786 }
 787 
 788 static int build_power_updown_phy(struct drm_dp_sideband_msg_tx *msg,
 789                                   int port_num, bool power_up)
 790 {
 791         struct drm_dp_sideband_msg_req_body req;
 792 
 793         if (power_up)
 794                 req.req_type = DP_POWER_UP_PHY;
 795         else
 796                 req.req_type = DP_POWER_DOWN_PHY;
 797 
 798         req.u.port_num.port_number = port_num;
 799         drm_dp_encode_sideband_req(&req, msg);
 800         msg->path_msg = true;
 801         return 0;
 802 }
 803 
 804 static int drm_dp_mst_assign_payload_id(struct drm_dp_mst_topology_mgr *mgr,
 805                                         struct drm_dp_vcpi *vcpi)
 806 {
 807         int ret, vcpi_ret;
 808 
 809         mutex_lock(&mgr->payload_lock);
 810         ret = find_first_zero_bit(&mgr->payload_mask, mgr->max_payloads + 1);
 811         if (ret > mgr->max_payloads) {
 812                 ret = -EINVAL;
 813                 DRM_DEBUG_KMS("out of payload ids %d\n", ret);
 814                 goto out_unlock;
 815         }
 816 
 817         vcpi_ret = find_first_zero_bit(&mgr->vcpi_mask, mgr->max_payloads + 1);
 818         if (vcpi_ret > mgr->max_payloads) {
 819                 ret = -EINVAL;
 820                 DRM_DEBUG_KMS("out of vcpi ids %d\n", ret);
 821                 goto out_unlock;
 822         }
 823 
 824         set_bit(ret, &mgr->payload_mask);
 825         set_bit(vcpi_ret, &mgr->vcpi_mask);
 826         vcpi->vcpi = vcpi_ret + 1;
 827         mgr->proposed_vcpis[ret - 1] = vcpi;
 828 out_unlock:
 829         mutex_unlock(&mgr->payload_lock);
 830         return ret;
 831 }
 832 
 833 static void drm_dp_mst_put_payload_id(struct drm_dp_mst_topology_mgr *mgr,
 834                                       int vcpi)
 835 {
 836         int i;
 837         if (vcpi == 0)
 838                 return;
 839 
 840         mutex_lock(&mgr->payload_lock);
 841         DRM_DEBUG_KMS("putting payload %d\n", vcpi);
 842         clear_bit(vcpi - 1, &mgr->vcpi_mask);
 843 
 844         for (i = 0; i < mgr->max_payloads; i++) {
 845                 if (mgr->proposed_vcpis[i])
 846                         if (mgr->proposed_vcpis[i]->vcpi == vcpi) {
 847                                 mgr->proposed_vcpis[i] = NULL;
 848                                 clear_bit(i + 1, &mgr->payload_mask);
 849                         }
 850         }
 851         mutex_unlock(&mgr->payload_lock);
 852 }
 853 
 854 static bool check_txmsg_state(struct drm_dp_mst_topology_mgr *mgr,
 855                               struct drm_dp_sideband_msg_tx *txmsg)
 856 {
 857         unsigned int state;
 858 
 859         /*
 860          * All updates to txmsg->state are protected by mgr->qlock, and the two
 861          * cases we check here are terminal states. For those the barriers
 862          * provided by the wake_up/wait_event pair are enough.
 863          */
 864         state = READ_ONCE(txmsg->state);
 865         return (state == DRM_DP_SIDEBAND_TX_RX ||
 866                 state == DRM_DP_SIDEBAND_TX_TIMEOUT);
 867 }
 868 
 869 static int drm_dp_mst_wait_tx_reply(struct drm_dp_mst_branch *mstb,
 870                                     struct drm_dp_sideband_msg_tx *txmsg)
 871 {
 872         struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
 873         int ret;
 874 
 875         ret = wait_event_timeout(mgr->tx_waitq,
 876                                  check_txmsg_state(mgr, txmsg),
 877                                  (4 * HZ));
 878         mutex_lock(&mstb->mgr->qlock);
 879         if (ret > 0) {
 880                 if (txmsg->state == DRM_DP_SIDEBAND_TX_TIMEOUT) {
 881                         ret = -EIO;
 882                         goto out;
 883                 }
 884         } else {
 885                 DRM_DEBUG_KMS("timedout msg send %p %d %d\n", txmsg, txmsg->state, txmsg->seqno);
 886 
 887                 /* dump some state */
 888                 ret = -EIO;
 889 
 890                 /* remove from q */
 891                 if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED ||
 892                     txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND) {
 893                         list_del(&txmsg->next);
 894                 }
 895 
 896                 if (txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND ||
 897                     txmsg->state == DRM_DP_SIDEBAND_TX_SENT) {
 898                         mstb->tx_slots[txmsg->seqno] = NULL;
 899                 }
 900         }
 901 out:
 902         mutex_unlock(&mgr->qlock);
 903 
 904         return ret;
 905 }
 906 
 907 static struct drm_dp_mst_branch *drm_dp_add_mst_branch_device(u8 lct, u8 *rad)
 908 {
 909         struct drm_dp_mst_branch *mstb;
 910 
 911         mstb = kzalloc(sizeof(*mstb), GFP_KERNEL);
 912         if (!mstb)
 913                 return NULL;
 914 
 915         mstb->lct = lct;
 916         if (lct > 1)
 917                 memcpy(mstb->rad, rad, lct / 2);
 918         INIT_LIST_HEAD(&mstb->ports);
 919         kref_init(&mstb->topology_kref);
 920         kref_init(&mstb->malloc_kref);
 921         return mstb;
 922 }
 923 
 924 static void drm_dp_free_mst_branch_device(struct kref *kref)
 925 {
 926         struct drm_dp_mst_branch *mstb =
 927                 container_of(kref, struct drm_dp_mst_branch, malloc_kref);
 928 
 929         if (mstb->port_parent)
 930                 drm_dp_mst_put_port_malloc(mstb->port_parent);
 931 
 932         kfree(mstb);
 933 }
 934 
 935 /**
 936  * DOC: Branch device and port refcounting
 937  *
 938  * Topology refcount overview
 939  * ~~~~~~~~~~~~~~~~~~~~~~~~~~
 940  *
 941  * The refcounting schemes for &struct drm_dp_mst_branch and &struct
 942  * drm_dp_mst_port are somewhat unusual. Both ports and branch devices have
 943  * two different kinds of refcounts: topology refcounts, and malloc refcounts.
 944  *
 945  * Topology refcounts are not exposed to drivers, and are handled internally
 946  * by the DP MST helpers. The helpers use them in order to prevent the
 947  * in-memory topology state from being changed in the middle of critical
 948  * operations like changing the internal state of payload allocations. This
 949  * means each branch and port will be considered to be connected to the rest
 950  * of the topology until its topology refcount reaches zero. Additionally,
 951  * for ports this means that their associated &struct drm_connector will stay
 952  * registered with userspace until the port's refcount reaches 0.
 953  *
 954  * Malloc refcount overview
 955  * ~~~~~~~~~~~~~~~~~~~~~~~~
 956  *
 957  * Malloc references are used to keep a &struct drm_dp_mst_port or &struct
 958  * drm_dp_mst_branch allocated even after all of its topology references have
 959  * been dropped, so that the driver or MST helpers can safely access each
 960  * branch's last known state before it was disconnected from the topology.
 961  * When the malloc refcount of a port or branch reaches 0, the memory
 962  * allocation containing the &struct drm_dp_mst_branch or &struct
 963  * drm_dp_mst_port respectively will be freed.
 964  *
 965  * For &struct drm_dp_mst_branch, malloc refcounts are not currently exposed
 966  * to drivers. As of writing this documentation, there are no drivers that
 967  * have a usecase for accessing &struct drm_dp_mst_branch outside of the MST
 968  * helpers. Exposing this API to drivers in a race-free manner would take more
 969  * tweaking of the refcounting scheme, however patches are welcome provided
 970  * there is a legitimate driver usecase for this.
 971  *
 972  * Refcount relationships in a topology
 973  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 974  *
 975  * Let's take a look at why the relationship between topology and malloc
 976  * refcounts is designed the way it is.
 977  *
 978  * .. kernel-figure:: dp-mst/topology-figure-1.dot
 979  *
 980  *    An example of topology and malloc refs in a DP MST topology with two
 981  *    active payloads. Topology refcount increments are indicated by solid
 982  *    lines, and malloc refcount increments are indicated by dashed lines.
 983  *    Each starts from the branch which incremented the refcount, and ends at
 984  *    the branch to which the refcount belongs to, i.e. the arrow points the
 985  *    same way as the C pointers used to reference a structure.
 986  *
 987  * As you can see in the above figure, every branch increments the topology
 988  * refcount of its children, and increments the malloc refcount of its
 989  * parent. Additionally, every payload increments the malloc refcount of its
 990  * assigned port by 1.
 991  *
 992  * So, what would happen if MSTB #3 from the above figure was unplugged from
 993  * the system, but the driver hadn't yet removed payload #2 from port #3? The
 994  * topology would start to look like the figure below.
 995  *
 996  * .. kernel-figure:: dp-mst/topology-figure-2.dot
 997  *
 998  *    Ports and branch devices which have been released from memory are
 999  *    colored grey, and references which have been removed are colored red.
1000  *
1001  * Whenever a port or branch device's topology refcount reaches zero, it will
1002  * decrement the topology refcounts of all its children, the malloc refcount
1003  * of its parent, and finally its own malloc refcount. For MSTB #4 and port
1004  * #4, this means they both have been disconnected from the topology and freed
1005  * from memory. But, because payload #2 is still holding a reference to port
1006  * #3, port #3 is removed from the topology but its &struct drm_dp_mst_port
1007  * is still accessible from memory. This also means port #3 has not yet
1008  * decremented the malloc refcount of MSTB #3, so its &struct
1009  * drm_dp_mst_branch will also stay allocated in memory until port #3's
1010  * malloc refcount reaches 0.
1011  *
1012  * This relationship is necessary because in order to release payload #2, we
1013  * need to be able to figure out the last relative of port #3 that's still
1014  * connected to the topology. In this case, we would travel up the topology as
1015  * shown below.
1016  *
1017  * .. kernel-figure:: dp-mst/topology-figure-3.dot
1018  *
1019  * And finally, remove payload #2 by communicating with port #2 through
1020  * sideband transactions.
1021  */
1022 
1023 /**
1024  * drm_dp_mst_get_mstb_malloc() - Increment the malloc refcount of a branch
1025  * device
1026  * @mstb: The &struct drm_dp_mst_branch to increment the malloc refcount of
1027  *
1028  * Increments &drm_dp_mst_branch.malloc_kref. When
1029  * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
1030  * will be released and @mstb may no longer be used.
1031  *
1032  * See also: drm_dp_mst_put_mstb_malloc()
1033  */
1034 static void
1035 drm_dp_mst_get_mstb_malloc(struct drm_dp_mst_branch *mstb)
1036 {
1037         kref_get(&mstb->malloc_kref);
1038         DRM_DEBUG("mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref));
1039 }
1040 
1041 /**
1042  * drm_dp_mst_put_mstb_malloc() - Decrement the malloc refcount of a branch
1043  * device
1044  * @mstb: The &struct drm_dp_mst_branch to decrement the malloc refcount of
1045  *
1046  * Decrements &drm_dp_mst_branch.malloc_kref. When
1047  * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
1048  * will be released and @mstb may no longer be used.
1049  *
1050  * See also: drm_dp_mst_get_mstb_malloc()
1051  */
1052 static void
1053 drm_dp_mst_put_mstb_malloc(struct drm_dp_mst_branch *mstb)
1054 {
1055         DRM_DEBUG("mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref) - 1);
1056         kref_put(&mstb->malloc_kref, drm_dp_free_mst_branch_device);
1057 }
1058 
1059 static void drm_dp_free_mst_port(struct kref *kref)
1060 {
1061         struct drm_dp_mst_port *port =
1062                 container_of(kref, struct drm_dp_mst_port, malloc_kref);
1063 
1064         drm_dp_mst_put_mstb_malloc(port->parent);
1065         kfree(port);
1066 }
1067 
1068 /**
1069  * drm_dp_mst_get_port_malloc() - Increment the malloc refcount of an MST port
1070  * @port: The &struct drm_dp_mst_port to increment the malloc refcount of
1071  *
1072  * Increments &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
1073  * reaches 0, the memory allocation for @port will be released and @port may
1074  * no longer be used.
1075  *
1076  * Because @port could potentially be freed at any time by the DP MST helpers
1077  * if &drm_dp_mst_port.malloc_kref reaches 0, including during a call to this
1078  * function, drivers that which to make use of &struct drm_dp_mst_port should
1079  * ensure that they grab at least one main malloc reference to their MST ports
1080  * in &drm_dp_mst_topology_cbs.add_connector. This callback is called before
1081  * there is any chance for &drm_dp_mst_port.malloc_kref to reach 0.
1082  *
1083  * See also: drm_dp_mst_put_port_malloc()
1084  */
1085 void
1086 drm_dp_mst_get_port_malloc(struct drm_dp_mst_port *port)
1087 {
1088         kref_get(&port->malloc_kref);
1089         DRM_DEBUG("port %p (%d)\n", port, kref_read(&port->malloc_kref));
1090 }
1091 EXPORT_SYMBOL(drm_dp_mst_get_port_malloc);
1092 
1093 /**
1094  * drm_dp_mst_put_port_malloc() - Decrement the malloc refcount of an MST port
1095  * @port: The &struct drm_dp_mst_port to decrement the malloc refcount of
1096  *
1097  * Decrements &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
1098  * reaches 0, the memory allocation for @port will be released and @port may
1099  * no longer be used.
1100  *
1101  * See also: drm_dp_mst_get_port_malloc()
1102  */
1103 void
1104 drm_dp_mst_put_port_malloc(struct drm_dp_mst_port *port)
1105 {
1106         DRM_DEBUG("port %p (%d)\n", port, kref_read(&port->malloc_kref) - 1);
1107         kref_put(&port->malloc_kref, drm_dp_free_mst_port);
1108 }
1109 EXPORT_SYMBOL(drm_dp_mst_put_port_malloc);
1110 
1111 static void drm_dp_destroy_mst_branch_device(struct kref *kref)
1112 {
1113         struct drm_dp_mst_branch *mstb =
1114                 container_of(kref, struct drm_dp_mst_branch, topology_kref);
1115         struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
1116         struct drm_dp_mst_port *port, *tmp;
1117         bool wake_tx = false;
1118 
1119         mutex_lock(&mgr->lock);
1120         list_for_each_entry_safe(port, tmp, &mstb->ports, next) {
1121                 list_del(&port->next);
1122                 drm_dp_mst_topology_put_port(port);
1123         }
1124         mutex_unlock(&mgr->lock);
1125 
1126         /* drop any tx slots msg */
1127         mutex_lock(&mstb->mgr->qlock);
1128         if (mstb->tx_slots[0]) {
1129                 mstb->tx_slots[0]->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
1130                 mstb->tx_slots[0] = NULL;
1131                 wake_tx = true;
1132         }
1133         if (mstb->tx_slots[1]) {
1134                 mstb->tx_slots[1]->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
1135                 mstb->tx_slots[1] = NULL;
1136                 wake_tx = true;
1137         }
1138         mutex_unlock(&mstb->mgr->qlock);
1139 
1140         if (wake_tx)
1141                 wake_up_all(&mstb->mgr->tx_waitq);
1142 
1143         drm_dp_mst_put_mstb_malloc(mstb);
1144 }
1145 
1146 /**
1147  * drm_dp_mst_topology_try_get_mstb() - Increment the topology refcount of a
1148  * branch device unless it's zero
1149  * @mstb: &struct drm_dp_mst_branch to increment the topology refcount of
1150  *
1151  * Attempts to grab a topology reference to @mstb, if it hasn't yet been
1152  * removed from the topology (e.g. &drm_dp_mst_branch.topology_kref has
1153  * reached 0). Holding a topology reference implies that a malloc reference
1154  * will be held to @mstb as long as the user holds the topology reference.
1155  *
1156  * Care should be taken to ensure that the user has at least one malloc
1157  * reference to @mstb. If you already have a topology reference to @mstb, you
1158  * should use drm_dp_mst_topology_get_mstb() instead.
1159  *
1160  * See also:
1161  * drm_dp_mst_topology_get_mstb()
1162  * drm_dp_mst_topology_put_mstb()
1163  *
1164  * Returns:
1165  * * 1: A topology reference was grabbed successfully
1166  * * 0: @port is no longer in the topology, no reference was grabbed
1167  */
1168 static int __must_check
1169 drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb)
1170 {
1171         int ret = kref_get_unless_zero(&mstb->topology_kref);
1172 
1173         if (ret)
1174                 DRM_DEBUG("mstb %p (%d)\n", mstb,
1175                           kref_read(&mstb->topology_kref));
1176 
1177         return ret;
1178 }
1179 
1180 /**
1181  * drm_dp_mst_topology_get_mstb() - Increment the topology refcount of a
1182  * branch device
1183  * @mstb: The &struct drm_dp_mst_branch to increment the topology refcount of
1184  *
1185  * Increments &drm_dp_mst_branch.topology_refcount without checking whether or
1186  * not it's already reached 0. This is only valid to use in scenarios where
1187  * you are already guaranteed to have at least one active topology reference
1188  * to @mstb. Otherwise, drm_dp_mst_topology_try_get_mstb() must be used.
1189  *
1190  * See also:
1191  * drm_dp_mst_topology_try_get_mstb()
1192  * drm_dp_mst_topology_put_mstb()
1193  */
1194 static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb)
1195 {
1196         WARN_ON(kref_read(&mstb->topology_kref) == 0);
1197         kref_get(&mstb->topology_kref);
1198         DRM_DEBUG("mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref));
1199 }
1200 
1201 /**
1202  * drm_dp_mst_topology_put_mstb() - release a topology reference to a branch
1203  * device
1204  * @mstb: The &struct drm_dp_mst_branch to release the topology reference from
1205  *
1206  * Releases a topology reference from @mstb by decrementing
1207  * &drm_dp_mst_branch.topology_kref.
1208  *
1209  * See also:
1210  * drm_dp_mst_topology_try_get_mstb()
1211  * drm_dp_mst_topology_get_mstb()
1212  */
1213 static void
1214 drm_dp_mst_topology_put_mstb(struct drm_dp_mst_branch *mstb)
1215 {
1216         DRM_DEBUG("mstb %p (%d)\n",
1217                   mstb, kref_read(&mstb->topology_kref) - 1);
1218         kref_put(&mstb->topology_kref, drm_dp_destroy_mst_branch_device);
1219 }
1220 
1221 static void drm_dp_port_teardown_pdt(struct drm_dp_mst_port *port, int old_pdt)
1222 {
1223         struct drm_dp_mst_branch *mstb;
1224 
1225         switch (old_pdt) {
1226         case DP_PEER_DEVICE_DP_LEGACY_CONV:
1227         case DP_PEER_DEVICE_SST_SINK:
1228                 /* remove i2c over sideband */
1229                 drm_dp_mst_unregister_i2c_bus(&port->aux);
1230                 break;
1231         case DP_PEER_DEVICE_MST_BRANCHING:
1232                 mstb = port->mstb;
1233                 port->mstb = NULL;
1234                 drm_dp_mst_topology_put_mstb(mstb);
1235                 break;
1236         }
1237 }
1238 
1239 static void drm_dp_destroy_port(struct kref *kref)
1240 {
1241         struct drm_dp_mst_port *port =
1242                 container_of(kref, struct drm_dp_mst_port, topology_kref);
1243         struct drm_dp_mst_topology_mgr *mgr = port->mgr;
1244 
1245         if (!port->input) {
1246                 kfree(port->cached_edid);
1247 
1248                 /*
1249                  * The only time we don't have a connector
1250                  * on an output port is if the connector init
1251                  * fails.
1252                  */
1253                 if (port->connector) {
1254                         /* we can't destroy the connector here, as
1255                          * we might be holding the mode_config.mutex
1256                          * from an EDID retrieval */
1257 
1258                         mutex_lock(&mgr->destroy_connector_lock);
1259                         list_add(&port->next, &mgr->destroy_connector_list);
1260                         mutex_unlock(&mgr->destroy_connector_lock);
1261                         schedule_work(&mgr->destroy_connector_work);
1262                         return;
1263                 }
1264                 /* no need to clean up vcpi
1265                  * as if we have no connector we never setup a vcpi */
1266                 drm_dp_port_teardown_pdt(port, port->pdt);
1267                 port->pdt = DP_PEER_DEVICE_NONE;
1268         }
1269         drm_dp_mst_put_port_malloc(port);
1270 }
1271 
1272 /**
1273  * drm_dp_mst_topology_try_get_port() - Increment the topology refcount of a
1274  * port unless it's zero
1275  * @port: &struct drm_dp_mst_port to increment the topology refcount of
1276  *
1277  * Attempts to grab a topology reference to @port, if it hasn't yet been
1278  * removed from the topology (e.g. &drm_dp_mst_port.topology_kref has reached
1279  * 0). Holding a topology reference implies that a malloc reference will be
1280  * held to @port as long as the user holds the topology reference.
1281  *
1282  * Care should be taken to ensure that the user has at least one malloc
1283  * reference to @port. If you already have a topology reference to @port, you
1284  * should use drm_dp_mst_topology_get_port() instead.
1285  *
1286  * See also:
1287  * drm_dp_mst_topology_get_port()
1288  * drm_dp_mst_topology_put_port()
1289  *
1290  * Returns:
1291  * * 1: A topology reference was grabbed successfully
1292  * * 0: @port is no longer in the topology, no reference was grabbed
1293  */
1294 static int __must_check
1295 drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port)
1296 {
1297         int ret = kref_get_unless_zero(&port->topology_kref);
1298 
1299         if (ret)
1300                 DRM_DEBUG("port %p (%d)\n", port,
1301                           kref_read(&port->topology_kref));
1302 
1303         return ret;
1304 }
1305 
1306 /**
1307  * drm_dp_mst_topology_get_port() - Increment the topology refcount of a port
1308  * @port: The &struct drm_dp_mst_port to increment the topology refcount of
1309  *
1310  * Increments &drm_dp_mst_port.topology_refcount without checking whether or
1311  * not it's already reached 0. This is only valid to use in scenarios where
1312  * you are already guaranteed to have at least one active topology reference
1313  * to @port. Otherwise, drm_dp_mst_topology_try_get_port() must be used.
1314  *
1315  * See also:
1316  * drm_dp_mst_topology_try_get_port()
1317  * drm_dp_mst_topology_put_port()
1318  */
1319 static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port)
1320 {
1321         WARN_ON(kref_read(&port->topology_kref) == 0);
1322         kref_get(&port->topology_kref);
1323         DRM_DEBUG("port %p (%d)\n", port, kref_read(&port->topology_kref));
1324 }
1325 
1326 /**
1327  * drm_dp_mst_topology_put_port() - release a topology reference to a port
1328  * @port: The &struct drm_dp_mst_port to release the topology reference from
1329  *
1330  * Releases a topology reference from @port by decrementing
1331  * &drm_dp_mst_port.topology_kref.
1332  *
1333  * See also:
1334  * drm_dp_mst_topology_try_get_port()
1335  * drm_dp_mst_topology_get_port()
1336  */
1337 static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port)
1338 {
1339         DRM_DEBUG("port %p (%d)\n",
1340                   port, kref_read(&port->topology_kref) - 1);
1341         kref_put(&port->topology_kref, drm_dp_destroy_port);
1342 }
1343 
1344 static struct drm_dp_mst_branch *
1345 drm_dp_mst_topology_get_mstb_validated_locked(struct drm_dp_mst_branch *mstb,
1346                                               struct drm_dp_mst_branch *to_find)
1347 {
1348         struct drm_dp_mst_port *port;
1349         struct drm_dp_mst_branch *rmstb;
1350 
1351         if (to_find == mstb)
1352                 return mstb;
1353 
1354         list_for_each_entry(port, &mstb->ports, next) {
1355                 if (port->mstb) {
1356                         rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
1357                             port->mstb, to_find);
1358                         if (rmstb)
1359                                 return rmstb;
1360                 }
1361         }
1362         return NULL;
1363 }
1364 
1365 static struct drm_dp_mst_branch *
1366 drm_dp_mst_topology_get_mstb_validated(struct drm_dp_mst_topology_mgr *mgr,
1367                                        struct drm_dp_mst_branch *mstb)
1368 {
1369         struct drm_dp_mst_branch *rmstb = NULL;
1370 
1371         mutex_lock(&mgr->lock);
1372         if (mgr->mst_primary) {
1373                 rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
1374                     mgr->mst_primary, mstb);
1375 
1376                 if (rmstb && !drm_dp_mst_topology_try_get_mstb(rmstb))
1377                         rmstb = NULL;
1378         }
1379         mutex_unlock(&mgr->lock);
1380         return rmstb;
1381 }
1382 
1383 static struct drm_dp_mst_port *
1384 drm_dp_mst_topology_get_port_validated_locked(struct drm_dp_mst_branch *mstb,
1385                                               struct drm_dp_mst_port *to_find)
1386 {
1387         struct drm_dp_mst_port *port, *mport;
1388 
1389         list_for_each_entry(port, &mstb->ports, next) {
1390                 if (port == to_find)
1391                         return port;
1392 
1393                 if (port->mstb) {
1394                         mport = drm_dp_mst_topology_get_port_validated_locked(
1395                             port->mstb, to_find);
1396                         if (mport)
1397                                 return mport;
1398                 }
1399         }
1400         return NULL;
1401 }
1402 
1403 static struct drm_dp_mst_port *
1404 drm_dp_mst_topology_get_port_validated(struct drm_dp_mst_topology_mgr *mgr,
1405                                        struct drm_dp_mst_port *port)
1406 {
1407         struct drm_dp_mst_port *rport = NULL;
1408 
1409         mutex_lock(&mgr->lock);
1410         if (mgr->mst_primary) {
1411                 rport = drm_dp_mst_topology_get_port_validated_locked(
1412                     mgr->mst_primary, port);
1413 
1414                 if (rport && !drm_dp_mst_topology_try_get_port(rport))
1415                         rport = NULL;
1416         }
1417         mutex_unlock(&mgr->lock);
1418         return rport;
1419 }
1420 
1421 static struct drm_dp_mst_port *drm_dp_get_port(struct drm_dp_mst_branch *mstb, u8 port_num)
1422 {
1423         struct drm_dp_mst_port *port;
1424         int ret;
1425 
1426         list_for_each_entry(port, &mstb->ports, next) {
1427                 if (port->port_num == port_num) {
1428                         ret = drm_dp_mst_topology_try_get_port(port);
1429                         return ret ? port : NULL;
1430                 }
1431         }
1432 
1433         return NULL;
1434 }
1435 
1436 /*
1437  * calculate a new RAD for this MST branch device
1438  * if parent has an LCT of 2 then it has 1 nibble of RAD,
1439  * if parent has an LCT of 3 then it has 2 nibbles of RAD,
1440  */
1441 static u8 drm_dp_calculate_rad(struct drm_dp_mst_port *port,
1442                                  u8 *rad)
1443 {
1444         int parent_lct = port->parent->lct;
1445         int shift = 4;
1446         int idx = (parent_lct - 1) / 2;
1447         if (parent_lct > 1) {
1448                 memcpy(rad, port->parent->rad, idx + 1);
1449                 shift = (parent_lct % 2) ? 4 : 0;
1450         } else
1451                 rad[0] = 0;
1452 
1453         rad[idx] |= port->port_num << shift;
1454         return parent_lct + 1;
1455 }
1456 
1457 /*
1458  * return sends link address for new mstb
1459  */
1460 static bool drm_dp_port_setup_pdt(struct drm_dp_mst_port *port)
1461 {
1462         int ret;
1463         u8 rad[6], lct;
1464         bool send_link = false;
1465         switch (port->pdt) {
1466         case DP_PEER_DEVICE_DP_LEGACY_CONV:
1467         case DP_PEER_DEVICE_SST_SINK:
1468                 /* add i2c over sideband */
1469                 ret = drm_dp_mst_register_i2c_bus(&port->aux);
1470                 break;
1471         case DP_PEER_DEVICE_MST_BRANCHING:
1472                 lct = drm_dp_calculate_rad(port, rad);
1473 
1474                 port->mstb = drm_dp_add_mst_branch_device(lct, rad);
1475                 if (port->mstb) {
1476                         port->mstb->mgr = port->mgr;
1477                         port->mstb->port_parent = port;
1478                         /*
1479                          * Make sure this port's memory allocation stays
1480                          * around until its child MSTB releases it
1481                          */
1482                         drm_dp_mst_get_port_malloc(port);
1483 
1484                         send_link = true;
1485                 }
1486                 break;
1487         }
1488         return send_link;
1489 }
1490 
1491 /**
1492  * drm_dp_mst_dpcd_read() - read a series of bytes from the DPCD via sideband
1493  * @aux: Fake sideband AUX CH
1494  * @offset: address of the (first) register to read
1495  * @buffer: buffer to store the register values
1496  * @size: number of bytes in @buffer
1497  *
1498  * Performs the same functionality for remote devices via
1499  * sideband messaging as drm_dp_dpcd_read() does for local
1500  * devices via actual AUX CH.
1501  *
1502  * Return: Number of bytes read, or negative error code on failure.
1503  */
1504 ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux,
1505                              unsigned int offset, void *buffer, size_t size)
1506 {
1507         struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
1508                                                     aux);
1509 
1510         return drm_dp_send_dpcd_read(port->mgr, port,
1511                                      offset, size, buffer);
1512 }
1513 
1514 /**
1515  * drm_dp_mst_dpcd_write() - write a series of bytes to the DPCD via sideband
1516  * @aux: Fake sideband AUX CH
1517  * @offset: address of the (first) register to write
1518  * @buffer: buffer containing the values to write
1519  * @size: number of bytes in @buffer
1520  *
1521  * Performs the same functionality for remote devices via
1522  * sideband messaging as drm_dp_dpcd_write() does for local
1523  * devices via actual AUX CH.
1524  *
1525  * Return: 0 on success, negative error code on failure.
1526  */
1527 ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux,
1528                               unsigned int offset, void *buffer, size_t size)
1529 {
1530         struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
1531                                                     aux);
1532 
1533         return drm_dp_send_dpcd_write(port->mgr, port,
1534                                       offset, size, buffer);
1535 }
1536 
1537 static void drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, u8 *guid)
1538 {
1539         int ret;
1540 
1541         memcpy(mstb->guid, guid, 16);
1542 
1543         if (!drm_dp_validate_guid(mstb->mgr, mstb->guid)) {
1544                 if (mstb->port_parent) {
1545                         ret = drm_dp_send_dpcd_write(
1546                                         mstb->mgr,
1547                                         mstb->port_parent,
1548                                         DP_GUID,
1549                                         16,
1550                                         mstb->guid);
1551                 } else {
1552 
1553                         ret = drm_dp_dpcd_write(
1554                                         mstb->mgr->aux,
1555                                         DP_GUID,
1556                                         mstb->guid,
1557                                         16);
1558                 }
1559         }
1560 }
1561 
1562 static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
1563                                 int pnum,
1564                                 char *proppath,
1565                                 size_t proppath_size)
1566 {
1567         int i;
1568         char temp[8];
1569         snprintf(proppath, proppath_size, "mst:%d", mstb->mgr->conn_base_id);
1570         for (i = 0; i < (mstb->lct - 1); i++) {
1571                 int shift = (i % 2) ? 0 : 4;
1572                 int port_num = (mstb->rad[i / 2] >> shift) & 0xf;
1573                 snprintf(temp, sizeof(temp), "-%d", port_num);
1574                 strlcat(proppath, temp, proppath_size);
1575         }
1576         snprintf(temp, sizeof(temp), "-%d", pnum);
1577         strlcat(proppath, temp, proppath_size);
1578 }
1579 
1580 /**
1581  * drm_dp_mst_connector_late_register() - Late MST connector registration
1582  * @connector: The MST connector
1583  * @port: The MST port for this connector
1584  *
1585  * Helper to register the remote aux device for this MST port. Drivers should
1586  * call this from their mst connector's late_register hook to enable MST aux
1587  * devices.
1588  *
1589  * Return: 0 on success, negative error code on failure.
1590  */
1591 int drm_dp_mst_connector_late_register(struct drm_connector *connector,
1592                                        struct drm_dp_mst_port *port)
1593 {
1594         DRM_DEBUG_KMS("registering %s remote bus for %s\n",
1595                       port->aux.name, connector->kdev->kobj.name);
1596 
1597         port->aux.dev = connector->kdev;
1598         return drm_dp_aux_register_devnode(&port->aux);
1599 }
1600 EXPORT_SYMBOL(drm_dp_mst_connector_late_register);
1601 
1602 /**
1603  * drm_dp_mst_connector_early_unregister() - Early MST connector unregistration
1604  * @connector: The MST connector
1605  * @port: The MST port for this connector
1606  *
1607  * Helper to unregister the remote aux device for this MST port, registered by
1608  * drm_dp_mst_connector_late_register(). Drivers should call this from their mst
1609  * connector's early_unregister hook.
1610  */
1611 void drm_dp_mst_connector_early_unregister(struct drm_connector *connector,
1612                                            struct drm_dp_mst_port *port)
1613 {
1614         DRM_DEBUG_KMS("unregistering %s remote bus for %s\n",
1615                       port->aux.name, connector->kdev->kobj.name);
1616         drm_dp_aux_unregister_devnode(&port->aux);
1617 }
1618 EXPORT_SYMBOL(drm_dp_mst_connector_early_unregister);
1619 
1620 static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
1621                             struct drm_device *dev,
1622                             struct drm_dp_link_addr_reply_port *port_msg)
1623 {
1624         struct drm_dp_mst_port *port;
1625         bool ret;
1626         bool created = false;
1627         int old_pdt = 0;
1628         int old_ddps = 0;
1629 
1630         port = drm_dp_get_port(mstb, port_msg->port_number);
1631         if (!port) {
1632                 port = kzalloc(sizeof(*port), GFP_KERNEL);
1633                 if (!port)
1634                         return;
1635                 kref_init(&port->topology_kref);
1636                 kref_init(&port->malloc_kref);
1637                 port->parent = mstb;
1638                 port->port_num = port_msg->port_number;
1639                 port->mgr = mstb->mgr;
1640                 port->aux.name = "DPMST";
1641                 port->aux.dev = dev->dev;
1642                 port->aux.is_remote = true;
1643 
1644                 /*
1645                  * Make sure the memory allocation for our parent branch stays
1646                  * around until our own memory allocation is released
1647                  */
1648                 drm_dp_mst_get_mstb_malloc(mstb);
1649 
1650                 created = true;
1651         } else {
1652                 old_pdt = port->pdt;
1653                 old_ddps = port->ddps;
1654         }
1655 
1656         port->pdt = port_msg->peer_device_type;
1657         port->input = port_msg->input_port;
1658         port->mcs = port_msg->mcs;
1659         port->ddps = port_msg->ddps;
1660         port->ldps = port_msg->legacy_device_plug_status;
1661         port->dpcd_rev = port_msg->dpcd_revision;
1662         port->num_sdp_streams = port_msg->num_sdp_streams;
1663         port->num_sdp_stream_sinks = port_msg->num_sdp_stream_sinks;
1664 
1665         /* manage mstb port lists with mgr lock - take a reference
1666            for this list */
1667         if (created) {
1668                 mutex_lock(&mstb->mgr->lock);
1669                 drm_dp_mst_topology_get_port(port);
1670                 list_add(&port->next, &mstb->ports);
1671                 mutex_unlock(&mstb->mgr->lock);
1672         }
1673 
1674         if (old_ddps != port->ddps) {
1675                 if (port->ddps) {
1676                         if (!port->input) {
1677                                 drm_dp_send_enum_path_resources(mstb->mgr,
1678                                                                 mstb, port);
1679                         }
1680                 } else {
1681                         port->available_pbn = 0;
1682                 }
1683         }
1684 
1685         if (old_pdt != port->pdt && !port->input) {
1686                 drm_dp_port_teardown_pdt(port, old_pdt);
1687 
1688                 ret = drm_dp_port_setup_pdt(port);
1689                 if (ret == true)
1690                         drm_dp_send_link_address(mstb->mgr, port->mstb);
1691         }
1692 
1693         if (created && !port->input) {
1694                 char proppath[255];
1695 
1696                 build_mst_prop_path(mstb, port->port_num, proppath,
1697                                     sizeof(proppath));
1698                 port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr,
1699                                                                    port,
1700                                                                    proppath);
1701                 if (!port->connector) {
1702                         /* remove it from the port list */
1703                         mutex_lock(&mstb->mgr->lock);
1704                         list_del(&port->next);
1705                         mutex_unlock(&mstb->mgr->lock);
1706                         /* drop port list reference */
1707                         drm_dp_mst_topology_put_port(port);
1708                         goto out;
1709                 }
1710                 if ((port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV ||
1711                      port->pdt == DP_PEER_DEVICE_SST_SINK) &&
1712                     port->port_num >= DP_MST_LOGICAL_PORT_0) {
1713                         port->cached_edid = drm_get_edid(port->connector,
1714                                                          &port->aux.ddc);
1715                         drm_connector_set_tile_property(port->connector);
1716                 }
1717                 (*mstb->mgr->cbs->register_connector)(port->connector);
1718         }
1719 
1720 out:
1721         /* put reference to this port */
1722         drm_dp_mst_topology_put_port(port);
1723 }
1724 
1725 static void drm_dp_update_port(struct drm_dp_mst_branch *mstb,
1726                                struct drm_dp_connection_status_notify *conn_stat)
1727 {
1728         struct drm_dp_mst_port *port;
1729         int old_pdt;
1730         int old_ddps;
1731         bool dowork = false;
1732         port = drm_dp_get_port(mstb, conn_stat->port_number);
1733         if (!port)
1734                 return;
1735 
1736         old_ddps = port->ddps;
1737         old_pdt = port->pdt;
1738         port->pdt = conn_stat->peer_device_type;
1739         port->mcs = conn_stat->message_capability_status;
1740         port->ldps = conn_stat->legacy_device_plug_status;
1741         port->ddps = conn_stat->displayport_device_plug_status;
1742 
1743         if (old_ddps != port->ddps) {
1744                 if (port->ddps) {
1745                         dowork = true;
1746                 } else {
1747                         port->available_pbn = 0;
1748                 }
1749         }
1750         if (old_pdt != port->pdt && !port->input) {
1751                 drm_dp_port_teardown_pdt(port, old_pdt);
1752 
1753                 if (drm_dp_port_setup_pdt(port))
1754                         dowork = true;
1755         }
1756 
1757         drm_dp_mst_topology_put_port(port);
1758         if (dowork)
1759                 queue_work(system_long_wq, &mstb->mgr->work);
1760 
1761 }
1762 
1763 static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_topology_mgr *mgr,
1764                                                                u8 lct, u8 *rad)
1765 {
1766         struct drm_dp_mst_branch *mstb;
1767         struct drm_dp_mst_port *port;
1768         int i, ret;
1769         /* find the port by iterating down */
1770 
1771         mutex_lock(&mgr->lock);
1772         mstb = mgr->mst_primary;
1773 
1774         if (!mstb)
1775                 goto out;
1776 
1777         for (i = 0; i < lct - 1; i++) {
1778                 int shift = (i % 2) ? 0 : 4;
1779                 int port_num = (rad[i / 2] >> shift) & 0xf;
1780 
1781                 list_for_each_entry(port, &mstb->ports, next) {
1782                         if (port->port_num == port_num) {
1783                                 mstb = port->mstb;
1784                                 if (!mstb) {
1785                                         DRM_ERROR("failed to lookup MSTB with lct %d, rad %02x\n", lct, rad[0]);
1786                                         goto out;
1787                                 }
1788 
1789                                 break;
1790                         }
1791                 }
1792         }
1793         ret = drm_dp_mst_topology_try_get_mstb(mstb);
1794         if (!ret)
1795                 mstb = NULL;
1796 out:
1797         mutex_unlock(&mgr->lock);
1798         return mstb;
1799 }
1800 
1801 static struct drm_dp_mst_branch *get_mst_branch_device_by_guid_helper(
1802         struct drm_dp_mst_branch *mstb,
1803         uint8_t *guid)
1804 {
1805         struct drm_dp_mst_branch *found_mstb;
1806         struct drm_dp_mst_port *port;
1807 
1808         if (memcmp(mstb->guid, guid, 16) == 0)
1809                 return mstb;
1810 
1811 
1812         list_for_each_entry(port, &mstb->ports, next) {
1813                 if (!port->mstb)
1814                         continue;
1815 
1816                 found_mstb = get_mst_branch_device_by_guid_helper(port->mstb, guid);
1817 
1818                 if (found_mstb)
1819                         return found_mstb;
1820         }
1821 
1822         return NULL;
1823 }
1824 
1825 static struct drm_dp_mst_branch *
1826 drm_dp_get_mst_branch_device_by_guid(struct drm_dp_mst_topology_mgr *mgr,
1827                                      uint8_t *guid)
1828 {
1829         struct drm_dp_mst_branch *mstb;
1830         int ret;
1831 
1832         /* find the port by iterating down */
1833         mutex_lock(&mgr->lock);
1834 
1835         mstb = get_mst_branch_device_by_guid_helper(mgr->mst_primary, guid);
1836         if (mstb) {
1837                 ret = drm_dp_mst_topology_try_get_mstb(mstb);
1838                 if (!ret)
1839                         mstb = NULL;
1840         }
1841 
1842         mutex_unlock(&mgr->lock);
1843         return mstb;
1844 }
1845 
1846 static void drm_dp_check_and_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
1847                                                struct drm_dp_mst_branch *mstb)
1848 {
1849         struct drm_dp_mst_port *port;
1850         struct drm_dp_mst_branch *mstb_child;
1851         if (!mstb->link_address_sent)
1852                 drm_dp_send_link_address(mgr, mstb);
1853 
1854         list_for_each_entry(port, &mstb->ports, next) {
1855                 if (port->input)
1856                         continue;
1857 
1858                 if (!port->ddps)
1859                         continue;
1860 
1861                 if (!port->available_pbn)
1862                         drm_dp_send_enum_path_resources(mgr, mstb, port);
1863 
1864                 if (port->mstb) {
1865                         mstb_child = drm_dp_mst_topology_get_mstb_validated(
1866                             mgr, port->mstb);
1867                         if (mstb_child) {
1868                                 drm_dp_check_and_send_link_address(mgr, mstb_child);
1869                                 drm_dp_mst_topology_put_mstb(mstb_child);
1870                         }
1871                 }
1872         }
1873 }
1874 
1875 static void drm_dp_mst_link_probe_work(struct work_struct *work)
1876 {
1877         struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, work);
1878         struct drm_dp_mst_branch *mstb;
1879         int ret;
1880 
1881         mutex_lock(&mgr->lock);
1882         mstb = mgr->mst_primary;
1883         if (mstb) {
1884                 ret = drm_dp_mst_topology_try_get_mstb(mstb);
1885                 if (!ret)
1886                         mstb = NULL;
1887         }
1888         mutex_unlock(&mgr->lock);
1889         if (mstb) {
1890                 drm_dp_check_and_send_link_address(mgr, mstb);
1891                 drm_dp_mst_topology_put_mstb(mstb);
1892         }
1893 }
1894 
1895 static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
1896                                  u8 *guid)
1897 {
1898         u64 salt;
1899 
1900         if (memchr_inv(guid, 0, 16))
1901                 return true;
1902 
1903         salt = get_jiffies_64();
1904 
1905         memcpy(&guid[0], &salt, sizeof(u64));
1906         memcpy(&guid[8], &salt, sizeof(u64));
1907 
1908         return false;
1909 }
1910 
1911 static int build_dpcd_read(struct drm_dp_sideband_msg_tx *msg, u8 port_num, u32 offset, u8 num_bytes)
1912 {
1913         struct drm_dp_sideband_msg_req_body req;
1914 
1915         req.req_type = DP_REMOTE_DPCD_READ;
1916         req.u.dpcd_read.port_number = port_num;
1917         req.u.dpcd_read.dpcd_address = offset;
1918         req.u.dpcd_read.num_bytes = num_bytes;
1919         drm_dp_encode_sideband_req(&req, msg);
1920 
1921         return 0;
1922 }
1923 
1924 static int drm_dp_send_sideband_msg(struct drm_dp_mst_topology_mgr *mgr,
1925                                     bool up, u8 *msg, int len)
1926 {
1927         int ret;
1928         int regbase = up ? DP_SIDEBAND_MSG_UP_REP_BASE : DP_SIDEBAND_MSG_DOWN_REQ_BASE;
1929         int tosend, total, offset;
1930         int retries = 0;
1931 
1932 retry:
1933         total = len;
1934         offset = 0;
1935         do {
1936                 tosend = min3(mgr->max_dpcd_transaction_bytes, 16, total);
1937 
1938                 ret = drm_dp_dpcd_write(mgr->aux, regbase + offset,
1939                                         &msg[offset],
1940                                         tosend);
1941                 if (ret != tosend) {
1942                         if (ret == -EIO && retries < 5) {
1943                                 retries++;
1944                                 goto retry;
1945                         }
1946                         DRM_DEBUG_KMS("failed to dpcd write %d %d\n", tosend, ret);
1947 
1948                         return -EIO;
1949                 }
1950                 offset += tosend;
1951                 total -= tosend;
1952         } while (total > 0);
1953         return 0;
1954 }
1955 
1956 static int set_hdr_from_dst_qlock(struct drm_dp_sideband_msg_hdr *hdr,
1957                                   struct drm_dp_sideband_msg_tx *txmsg)
1958 {
1959         struct drm_dp_mst_branch *mstb = txmsg->dst;
1960         u8 req_type;
1961 
1962         /* both msg slots are full */
1963         if (txmsg->seqno == -1) {
1964                 if (mstb->tx_slots[0] && mstb->tx_slots[1]) {
1965                         DRM_DEBUG_KMS("%s: failed to find slot\n", __func__);
1966                         return -EAGAIN;
1967                 }
1968                 if (mstb->tx_slots[0] == NULL && mstb->tx_slots[1] == NULL) {
1969                         txmsg->seqno = mstb->last_seqno;
1970                         mstb->last_seqno ^= 1;
1971                 } else if (mstb->tx_slots[0] == NULL)
1972                         txmsg->seqno = 0;
1973                 else
1974                         txmsg->seqno = 1;
1975                 mstb->tx_slots[txmsg->seqno] = txmsg;
1976         }
1977 
1978         req_type = txmsg->msg[0] & 0x7f;
1979         if (req_type == DP_CONNECTION_STATUS_NOTIFY ||
1980                 req_type == DP_RESOURCE_STATUS_NOTIFY)
1981                 hdr->broadcast = 1;
1982         else
1983                 hdr->broadcast = 0;
1984         hdr->path_msg = txmsg->path_msg;
1985         hdr->lct = mstb->lct;
1986         hdr->lcr = mstb->lct - 1;
1987         if (mstb->lct > 1)
1988                 memcpy(hdr->rad, mstb->rad, mstb->lct / 2);
1989         hdr->seqno = txmsg->seqno;
1990         return 0;
1991 }
1992 /*
1993  * process a single block of the next message in the sideband queue
1994  */
1995 static int process_single_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
1996                                    struct drm_dp_sideband_msg_tx *txmsg,
1997                                    bool up)
1998 {
1999         u8 chunk[48];
2000         struct drm_dp_sideband_msg_hdr hdr;
2001         int len, space, idx, tosend;
2002         int ret;
2003 
2004         memset(&hdr, 0, sizeof(struct drm_dp_sideband_msg_hdr));
2005 
2006         if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED) {
2007                 txmsg->seqno = -1;
2008                 txmsg->state = DRM_DP_SIDEBAND_TX_START_SEND;
2009         }
2010 
2011         /* make hdr from dst mst - for replies use seqno
2012            otherwise assign one */
2013         ret = set_hdr_from_dst_qlock(&hdr, txmsg);
2014         if (ret < 0)
2015                 return ret;
2016 
2017         /* amount left to send in this message */
2018         len = txmsg->cur_len - txmsg->cur_offset;
2019 
2020         /* 48 - sideband msg size - 1 byte for data CRC, x header bytes */
2021         space = 48 - 1 - drm_dp_calc_sb_hdr_size(&hdr);
2022 
2023         tosend = min(len, space);
2024         if (len == txmsg->cur_len)
2025                 hdr.somt = 1;
2026         if (space >= len)
2027                 hdr.eomt = 1;
2028 
2029 
2030         hdr.msg_len = tosend + 1;
2031         drm_dp_encode_sideband_msg_hdr(&hdr, chunk, &idx);
2032         memcpy(&chunk[idx], &txmsg->msg[txmsg->cur_offset], tosend);
2033         /* add crc at end */
2034         drm_dp_crc_sideband_chunk_req(&chunk[idx], tosend);
2035         idx += tosend + 1;
2036 
2037         ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx);
2038         if (ret) {
2039                 DRM_DEBUG_KMS("sideband msg failed to send\n");
2040                 return ret;
2041         }
2042 
2043         txmsg->cur_offset += tosend;
2044         if (txmsg->cur_offset == txmsg->cur_len) {
2045                 txmsg->state = DRM_DP_SIDEBAND_TX_SENT;
2046                 return 1;
2047         }
2048         return 0;
2049 }
2050 
2051 static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
2052 {
2053         struct drm_dp_sideband_msg_tx *txmsg;
2054         int ret;
2055 
2056         WARN_ON(!mutex_is_locked(&mgr->qlock));
2057 
2058         /* construct a chunk from the first msg in the tx_msg queue */
2059         if (list_empty(&mgr->tx_msg_downq))
2060                 return;
2061 
2062         txmsg = list_first_entry(&mgr->tx_msg_downq, struct drm_dp_sideband_msg_tx, next);
2063         ret = process_single_tx_qlock(mgr, txmsg, false);
2064         if (ret == 1) {
2065                 /* txmsg is sent it should be in the slots now */
2066                 list_del(&txmsg->next);
2067         } else if (ret) {
2068                 DRM_DEBUG_KMS("failed to send msg in q %d\n", ret);
2069                 list_del(&txmsg->next);
2070                 if (txmsg->seqno != -1)
2071                         txmsg->dst->tx_slots[txmsg->seqno] = NULL;
2072                 txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
2073                 wake_up_all(&mgr->tx_waitq);
2074         }
2075 }
2076 
2077 /* called holding qlock */
2078 static void process_single_up_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
2079                                        struct drm_dp_sideband_msg_tx *txmsg)
2080 {
2081         int ret;
2082 
2083         /* construct a chunk from the first msg in the tx_msg queue */
2084         ret = process_single_tx_qlock(mgr, txmsg, true);
2085 
2086         if (ret != 1)
2087                 DRM_DEBUG_KMS("failed to send msg in q %d\n", ret);
2088 
2089         if (txmsg->seqno != -1) {
2090                 WARN_ON((unsigned int)txmsg->seqno >
2091                         ARRAY_SIZE(txmsg->dst->tx_slots));
2092                 txmsg->dst->tx_slots[txmsg->seqno] = NULL;
2093         }
2094 }
2095 
2096 static void drm_dp_queue_down_tx(struct drm_dp_mst_topology_mgr *mgr,
2097                                  struct drm_dp_sideband_msg_tx *txmsg)
2098 {
2099         mutex_lock(&mgr->qlock);
2100         list_add_tail(&txmsg->next, &mgr->tx_msg_downq);
2101         if (list_is_singular(&mgr->tx_msg_downq))
2102                 process_single_down_tx_qlock(mgr);
2103         mutex_unlock(&mgr->qlock);
2104 }
2105 
2106 static void drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
2107                                      struct drm_dp_mst_branch *mstb)
2108 {
2109         int len;
2110         struct drm_dp_sideband_msg_tx *txmsg;
2111         int ret;
2112 
2113         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2114         if (!txmsg)
2115                 return;
2116 
2117         txmsg->dst = mstb;
2118         len = build_link_address(txmsg);
2119 
2120         mstb->link_address_sent = true;
2121         drm_dp_queue_down_tx(mgr, txmsg);
2122 
2123         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2124         if (ret > 0) {
2125                 int i;
2126 
2127                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
2128                         DRM_DEBUG_KMS("link address nak received\n");
2129                 } else {
2130                         DRM_DEBUG_KMS("link address reply: %d\n", txmsg->reply.u.link_addr.nports);
2131                         for (i = 0; i < txmsg->reply.u.link_addr.nports; i++) {
2132                                 DRM_DEBUG_KMS("port %d: input %d, pdt: %d, pn: %d, dpcd_rev: %02x, mcs: %d, ddps: %d, ldps %d, sdp %d/%d\n", i,
2133                                        txmsg->reply.u.link_addr.ports[i].input_port,
2134                                        txmsg->reply.u.link_addr.ports[i].peer_device_type,
2135                                        txmsg->reply.u.link_addr.ports[i].port_number,
2136                                        txmsg->reply.u.link_addr.ports[i].dpcd_revision,
2137                                        txmsg->reply.u.link_addr.ports[i].mcs,
2138                                        txmsg->reply.u.link_addr.ports[i].ddps,
2139                                        txmsg->reply.u.link_addr.ports[i].legacy_device_plug_status,
2140                                        txmsg->reply.u.link_addr.ports[i].num_sdp_streams,
2141                                        txmsg->reply.u.link_addr.ports[i].num_sdp_stream_sinks);
2142                         }
2143 
2144                         drm_dp_check_mstb_guid(mstb, txmsg->reply.u.link_addr.guid);
2145 
2146                         for (i = 0; i < txmsg->reply.u.link_addr.nports; i++) {
2147                                 drm_dp_add_port(mstb, mgr->dev, &txmsg->reply.u.link_addr.ports[i]);
2148                         }
2149                         drm_kms_helper_hotplug_event(mgr->dev);
2150                 }
2151         } else {
2152                 mstb->link_address_sent = false;
2153                 DRM_DEBUG_KMS("link address failed %d\n", ret);
2154         }
2155 
2156         kfree(txmsg);
2157 }
2158 
2159 static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
2160                                            struct drm_dp_mst_branch *mstb,
2161                                            struct drm_dp_mst_port *port)
2162 {
2163         int len;
2164         struct drm_dp_sideband_msg_tx *txmsg;
2165         int ret;
2166 
2167         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2168         if (!txmsg)
2169                 return -ENOMEM;
2170 
2171         txmsg->dst = mstb;
2172         len = build_enum_path_resources(txmsg, port->port_num);
2173 
2174         drm_dp_queue_down_tx(mgr, txmsg);
2175 
2176         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2177         if (ret > 0) {
2178                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
2179                         DRM_DEBUG_KMS("enum path resources nak received\n");
2180                 } else {
2181                         if (port->port_num != txmsg->reply.u.path_resources.port_number)
2182                                 DRM_ERROR("got incorrect port in response\n");
2183                         DRM_DEBUG_KMS("enum path resources %d: %d %d\n", txmsg->reply.u.path_resources.port_number, txmsg->reply.u.path_resources.full_payload_bw_number,
2184                                txmsg->reply.u.path_resources.avail_payload_bw_number);
2185                         port->available_pbn = txmsg->reply.u.path_resources.avail_payload_bw_number;
2186                 }
2187         }
2188 
2189         kfree(txmsg);
2190         return 0;
2191 }
2192 
2193 static struct drm_dp_mst_port *drm_dp_get_last_connected_port_to_mstb(struct drm_dp_mst_branch *mstb)
2194 {
2195         if (!mstb->port_parent)
2196                 return NULL;
2197 
2198         if (mstb->port_parent->mstb != mstb)
2199                 return mstb->port_parent;
2200 
2201         return drm_dp_get_last_connected_port_to_mstb(mstb->port_parent->parent);
2202 }
2203 
2204 /*
2205  * Searches upwards in the topology starting from mstb to try to find the
2206  * closest available parent of mstb that's still connected to the rest of the
2207  * topology. This can be used in order to perform operations like releasing
2208  * payloads, where the branch device which owned the payload may no longer be
2209  * around and thus would require that the payload on the last living relative
2210  * be freed instead.
2211  */
2212 static struct drm_dp_mst_branch *
2213 drm_dp_get_last_connected_port_and_mstb(struct drm_dp_mst_topology_mgr *mgr,
2214                                         struct drm_dp_mst_branch *mstb,
2215                                         int *port_num)
2216 {
2217         struct drm_dp_mst_branch *rmstb = NULL;
2218         struct drm_dp_mst_port *found_port;
2219 
2220         mutex_lock(&mgr->lock);
2221         if (!mgr->mst_primary)
2222                 goto out;
2223 
2224         do {
2225                 found_port = drm_dp_get_last_connected_port_to_mstb(mstb);
2226                 if (!found_port)
2227                         break;
2228 
2229                 if (drm_dp_mst_topology_try_get_mstb(found_port->parent)) {
2230                         rmstb = found_port->parent;
2231                         *port_num = found_port->port_num;
2232                 } else {
2233                         /* Search again, starting from this parent */
2234                         mstb = found_port->parent;
2235                 }
2236         } while (!rmstb);
2237 out:
2238         mutex_unlock(&mgr->lock);
2239         return rmstb;
2240 }
2241 
2242 static int drm_dp_payload_send_msg(struct drm_dp_mst_topology_mgr *mgr,
2243                                    struct drm_dp_mst_port *port,
2244                                    int id,
2245                                    int pbn)
2246 {
2247         struct drm_dp_sideband_msg_tx *txmsg;
2248         struct drm_dp_mst_branch *mstb;
2249         int len, ret, port_num;
2250         u8 sinks[DRM_DP_MAX_SDP_STREAMS];
2251         int i;
2252 
2253         port_num = port->port_num;
2254         mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
2255         if (!mstb) {
2256                 mstb = drm_dp_get_last_connected_port_and_mstb(mgr,
2257                                                                port->parent,
2258                                                                &port_num);
2259 
2260                 if (!mstb)
2261                         return -EINVAL;
2262         }
2263 
2264         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2265         if (!txmsg) {
2266                 ret = -ENOMEM;
2267                 goto fail_put;
2268         }
2269 
2270         for (i = 0; i < port->num_sdp_streams; i++)
2271                 sinks[i] = i;
2272 
2273         txmsg->dst = mstb;
2274         len = build_allocate_payload(txmsg, port_num,
2275                                      id,
2276                                      pbn, port->num_sdp_streams, sinks);
2277 
2278         drm_dp_queue_down_tx(mgr, txmsg);
2279 
2280         /*
2281          * FIXME: there is a small chance that between getting the last
2282          * connected mstb and sending the payload message, the last connected
2283          * mstb could also be removed from the topology. In the future, this
2284          * needs to be fixed by restarting the
2285          * drm_dp_get_last_connected_port_and_mstb() search in the event of a
2286          * timeout if the topology is still connected to the system.
2287          */
2288         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2289         if (ret > 0) {
2290                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
2291                         ret = -EINVAL;
2292                 else
2293                         ret = 0;
2294         }
2295         kfree(txmsg);
2296 fail_put:
2297         drm_dp_mst_topology_put_mstb(mstb);
2298         return ret;
2299 }
2300 
2301 int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
2302                                  struct drm_dp_mst_port *port, bool power_up)
2303 {
2304         struct drm_dp_sideband_msg_tx *txmsg;
2305         int len, ret;
2306 
2307         port = drm_dp_mst_topology_get_port_validated(mgr, port);
2308         if (!port)
2309                 return -EINVAL;
2310 
2311         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2312         if (!txmsg) {
2313                 drm_dp_mst_topology_put_port(port);
2314                 return -ENOMEM;
2315         }
2316 
2317         txmsg->dst = port->parent;
2318         len = build_power_updown_phy(txmsg, port->port_num, power_up);
2319         drm_dp_queue_down_tx(mgr, txmsg);
2320 
2321         ret = drm_dp_mst_wait_tx_reply(port->parent, txmsg);
2322         if (ret > 0) {
2323                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
2324                         ret = -EINVAL;
2325                 else
2326                         ret = 0;
2327         }
2328         kfree(txmsg);
2329         drm_dp_mst_topology_put_port(port);
2330 
2331         return ret;
2332 }
2333 EXPORT_SYMBOL(drm_dp_send_power_updown_phy);
2334 
2335 static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
2336                                        int id,
2337                                        struct drm_dp_payload *payload)
2338 {
2339         int ret;
2340 
2341         ret = drm_dp_dpcd_write_payload(mgr, id, payload);
2342         if (ret < 0) {
2343                 payload->payload_state = 0;
2344                 return ret;
2345         }
2346         payload->payload_state = DP_PAYLOAD_LOCAL;
2347         return 0;
2348 }
2349 
2350 static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
2351                                        struct drm_dp_mst_port *port,
2352                                        int id,
2353                                        struct drm_dp_payload *payload)
2354 {
2355         int ret;
2356         ret = drm_dp_payload_send_msg(mgr, port, id, port->vcpi.pbn);
2357         if (ret < 0)
2358                 return ret;
2359         payload->payload_state = DP_PAYLOAD_REMOTE;
2360         return ret;
2361 }
2362 
2363 static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
2364                                         struct drm_dp_mst_port *port,
2365                                         int id,
2366                                         struct drm_dp_payload *payload)
2367 {
2368         DRM_DEBUG_KMS("\n");
2369         /* it's okay for these to fail */
2370         if (port) {
2371                 drm_dp_payload_send_msg(mgr, port, id, 0);
2372         }
2373 
2374         drm_dp_dpcd_write_payload(mgr, id, payload);
2375         payload->payload_state = DP_PAYLOAD_DELETE_LOCAL;
2376         return 0;
2377 }
2378 
2379 static int drm_dp_destroy_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
2380                                         int id,
2381                                         struct drm_dp_payload *payload)
2382 {
2383         payload->payload_state = 0;
2384         return 0;
2385 }
2386 
2387 /**
2388  * drm_dp_update_payload_part1() - Execute payload update part 1
2389  * @mgr: manager to use.
2390  *
2391  * This iterates over all proposed virtual channels, and tries to
2392  * allocate space in the link for them. For 0->slots transitions,
2393  * this step just writes the VCPI to the MST device. For slots->0
2394  * transitions, this writes the updated VCPIs and removes the
2395  * remote VC payloads.
2396  *
2397  * after calling this the driver should generate ACT and payload
2398  * packets.
2399  */
2400 int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr)
2401 {
2402         struct drm_dp_payload req_payload;
2403         struct drm_dp_mst_port *port;
2404         int i, j;
2405         int cur_slots = 1;
2406 
2407         mutex_lock(&mgr->payload_lock);
2408         for (i = 0; i < mgr->max_payloads; i++) {
2409                 struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i];
2410                 struct drm_dp_payload *payload = &mgr->payloads[i];
2411                 bool put_port = false;
2412 
2413                 /* solve the current payloads - compare to the hw ones
2414                    - update the hw view */
2415                 req_payload.start_slot = cur_slots;
2416                 if (vcpi) {
2417                         port = container_of(vcpi, struct drm_dp_mst_port,
2418                                             vcpi);
2419 
2420                         /* Validated ports don't matter if we're releasing
2421                          * VCPI
2422                          */
2423                         if (vcpi->num_slots) {
2424                                 port = drm_dp_mst_topology_get_port_validated(
2425                                     mgr, port);
2426                                 if (!port) {
2427                                         mutex_unlock(&mgr->payload_lock);
2428                                         return -EINVAL;
2429                                 }
2430                                 put_port = true;
2431                         }
2432 
2433                         req_payload.num_slots = vcpi->num_slots;
2434                         req_payload.vcpi = vcpi->vcpi;
2435                 } else {
2436                         port = NULL;
2437                         req_payload.num_slots = 0;
2438                 }
2439 
2440                 payload->start_slot = req_payload.start_slot;
2441                 /* work out what is required to happen with this payload */
2442                 if (payload->num_slots != req_payload.num_slots) {
2443 
2444                         /* need to push an update for this payload */
2445                         if (req_payload.num_slots) {
2446                                 drm_dp_create_payload_step1(mgr, vcpi->vcpi,
2447                                                             &req_payload);
2448                                 payload->num_slots = req_payload.num_slots;
2449                                 payload->vcpi = req_payload.vcpi;
2450 
2451                         } else if (payload->num_slots) {
2452                                 payload->num_slots = 0;
2453                                 drm_dp_destroy_payload_step1(mgr, port,
2454                                                              payload->vcpi,
2455                                                              payload);
2456                                 req_payload.payload_state =
2457                                         payload->payload_state;
2458                                 payload->start_slot = 0;
2459                         }
2460                         payload->payload_state = req_payload.payload_state;
2461                 }
2462                 cur_slots += req_payload.num_slots;
2463 
2464                 if (put_port)
2465                         drm_dp_mst_topology_put_port(port);
2466         }
2467 
2468         for (i = 0; i < mgr->max_payloads; /* do nothing */) {
2469                 if (mgr->payloads[i].payload_state != DP_PAYLOAD_DELETE_LOCAL) {
2470                         i++;
2471                         continue;
2472                 }
2473 
2474                 DRM_DEBUG_KMS("removing payload %d\n", i);
2475                 for (j = i; j < mgr->max_payloads - 1; j++) {
2476                         mgr->payloads[j] = mgr->payloads[j + 1];
2477                         mgr->proposed_vcpis[j] = mgr->proposed_vcpis[j + 1];
2478 
2479                         if (mgr->proposed_vcpis[j] &&
2480                             mgr->proposed_vcpis[j]->num_slots) {
2481                                 set_bit(j + 1, &mgr->payload_mask);
2482                         } else {
2483                                 clear_bit(j + 1, &mgr->payload_mask);
2484                         }
2485                 }
2486 
2487                 memset(&mgr->payloads[mgr->max_payloads - 1], 0,
2488                        sizeof(struct drm_dp_payload));
2489                 mgr->proposed_vcpis[mgr->max_payloads - 1] = NULL;
2490                 clear_bit(mgr->max_payloads, &mgr->payload_mask);
2491         }
2492         mutex_unlock(&mgr->payload_lock);
2493 
2494         return 0;
2495 }
2496 EXPORT_SYMBOL(drm_dp_update_payload_part1);
2497 
2498 /**
2499  * drm_dp_update_payload_part2() - Execute payload update part 2
2500  * @mgr: manager to use.
2501  *
2502  * This iterates over all proposed virtual channels, and tries to
2503  * allocate space in the link for them. For 0->slots transitions,
2504  * this step writes the remote VC payload commands. For slots->0
2505  * this just resets some internal state.
2506  */
2507 int drm_dp_update_payload_part2(struct drm_dp_mst_topology_mgr *mgr)
2508 {
2509         struct drm_dp_mst_port *port;
2510         int i;
2511         int ret = 0;
2512         mutex_lock(&mgr->payload_lock);
2513         for (i = 0; i < mgr->max_payloads; i++) {
2514 
2515                 if (!mgr->proposed_vcpis[i])
2516                         continue;
2517 
2518                 port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
2519 
2520                 DRM_DEBUG_KMS("payload %d %d\n", i, mgr->payloads[i].payload_state);
2521                 if (mgr->payloads[i].payload_state == DP_PAYLOAD_LOCAL) {
2522                         ret = drm_dp_create_payload_step2(mgr, port, mgr->proposed_vcpis[i]->vcpi, &mgr->payloads[i]);
2523                 } else if (mgr->payloads[i].payload_state == DP_PAYLOAD_DELETE_LOCAL) {
2524                         ret = drm_dp_destroy_payload_step2(mgr, mgr->proposed_vcpis[i]->vcpi, &mgr->payloads[i]);
2525                 }
2526                 if (ret) {
2527                         mutex_unlock(&mgr->payload_lock);
2528                         return ret;
2529                 }
2530         }
2531         mutex_unlock(&mgr->payload_lock);
2532         return 0;
2533 }
2534 EXPORT_SYMBOL(drm_dp_update_payload_part2);
2535 
2536 static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
2537                                  struct drm_dp_mst_port *port,
2538                                  int offset, int size, u8 *bytes)
2539 {
2540         int len;
2541         int ret = 0;
2542         struct drm_dp_sideband_msg_tx *txmsg;
2543         struct drm_dp_mst_branch *mstb;
2544 
2545         mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
2546         if (!mstb)
2547                 return -EINVAL;
2548 
2549         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2550         if (!txmsg) {
2551                 ret = -ENOMEM;
2552                 goto fail_put;
2553         }
2554 
2555         len = build_dpcd_read(txmsg, port->port_num, offset, size);
2556         txmsg->dst = port->parent;
2557 
2558         drm_dp_queue_down_tx(mgr, txmsg);
2559 
2560         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2561         if (ret < 0)
2562                 goto fail_free;
2563 
2564         /* DPCD read should never be NACKed */
2565         if (txmsg->reply.reply_type == 1) {
2566                 DRM_ERROR("mstb %p port %d: DPCD read on addr 0x%x for %d bytes NAKed\n",
2567                           mstb, port->port_num, offset, size);
2568                 ret = -EIO;
2569                 goto fail_free;
2570         }
2571 
2572         if (txmsg->reply.u.remote_dpcd_read_ack.num_bytes != size) {
2573                 ret = -EPROTO;
2574                 goto fail_free;
2575         }
2576 
2577         ret = min_t(size_t, txmsg->reply.u.remote_dpcd_read_ack.num_bytes,
2578                     size);
2579         memcpy(bytes, txmsg->reply.u.remote_dpcd_read_ack.bytes, ret);
2580 
2581 fail_free:
2582         kfree(txmsg);
2583 fail_put:
2584         drm_dp_mst_topology_put_mstb(mstb);
2585 
2586         return ret;
2587 }
2588 
2589 static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
2590                                   struct drm_dp_mst_port *port,
2591                                   int offset, int size, u8 *bytes)
2592 {
2593         int len;
2594         int ret;
2595         struct drm_dp_sideband_msg_tx *txmsg;
2596         struct drm_dp_mst_branch *mstb;
2597 
2598         mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
2599         if (!mstb)
2600                 return -EINVAL;
2601 
2602         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2603         if (!txmsg) {
2604                 ret = -ENOMEM;
2605                 goto fail_put;
2606         }
2607 
2608         len = build_dpcd_write(txmsg, port->port_num, offset, size, bytes);
2609         txmsg->dst = mstb;
2610 
2611         drm_dp_queue_down_tx(mgr, txmsg);
2612 
2613         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2614         if (ret > 0) {
2615                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
2616                         ret = -EIO;
2617                 else
2618                         ret = 0;
2619         }
2620         kfree(txmsg);
2621 fail_put:
2622         drm_dp_mst_topology_put_mstb(mstb);
2623         return ret;
2624 }
2625 
2626 static int drm_dp_encode_up_ack_reply(struct drm_dp_sideband_msg_tx *msg, u8 req_type)
2627 {
2628         struct drm_dp_sideband_msg_reply_body reply;
2629 
2630         reply.reply_type = DP_SIDEBAND_REPLY_ACK;
2631         reply.req_type = req_type;
2632         drm_dp_encode_sideband_reply(&reply, msg);
2633         return 0;
2634 }
2635 
2636 static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
2637                                     struct drm_dp_mst_branch *mstb,
2638                                     int req_type, int seqno, bool broadcast)
2639 {
2640         struct drm_dp_sideband_msg_tx *txmsg;
2641 
2642         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2643         if (!txmsg)
2644                 return -ENOMEM;
2645 
2646         txmsg->dst = mstb;
2647         txmsg->seqno = seqno;
2648         drm_dp_encode_up_ack_reply(txmsg, req_type);
2649 
2650         mutex_lock(&mgr->qlock);
2651 
2652         process_single_up_tx_qlock(mgr, txmsg);
2653 
2654         mutex_unlock(&mgr->qlock);
2655 
2656         kfree(txmsg);
2657         return 0;
2658 }
2659 
2660 static bool drm_dp_get_vc_payload_bw(int dp_link_bw,
2661                                      int dp_link_count,
2662                                      int *out)
2663 {
2664         switch (dp_link_bw) {
2665         default:
2666                 DRM_DEBUG_KMS("invalid link bandwidth in DPCD: %x (link count: %d)\n",
2667                               dp_link_bw, dp_link_count);
2668                 return false;
2669 
2670         case DP_LINK_BW_1_62:
2671                 *out = 3 * dp_link_count;
2672                 break;
2673         case DP_LINK_BW_2_7:
2674                 *out = 5 * dp_link_count;
2675                 break;
2676         case DP_LINK_BW_5_4:
2677                 *out = 10 * dp_link_count;
2678                 break;
2679         case DP_LINK_BW_8_1:
2680                 *out = 15 * dp_link_count;
2681                 break;
2682         }
2683         return true;
2684 }
2685 
2686 /**
2687  * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
2688  * @mgr: manager to set state for
2689  * @mst_state: true to enable MST on this connector - false to disable.
2690  *
2691  * This is called by the driver when it detects an MST capable device plugged
2692  * into a DP MST capable port, or when a DP MST capable device is unplugged.
2693  */
2694 int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state)
2695 {
2696         int ret = 0;
2697         struct drm_dp_mst_branch *mstb = NULL;
2698 
2699         mutex_lock(&mgr->payload_lock);
2700         mutex_lock(&mgr->lock);
2701         if (mst_state == mgr->mst_state)
2702                 goto out_unlock;
2703 
2704         mgr->mst_state = mst_state;
2705         /* set the device into MST mode */
2706         if (mst_state) {
2707                 WARN_ON(mgr->mst_primary);
2708 
2709                 /* get dpcd info */
2710                 ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, DP_RECEIVER_CAP_SIZE);
2711                 if (ret != DP_RECEIVER_CAP_SIZE) {
2712                         DRM_DEBUG_KMS("failed to read DPCD\n");
2713                         goto out_unlock;
2714                 }
2715 
2716                 if (!drm_dp_get_vc_payload_bw(mgr->dpcd[1],
2717                                               mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK,
2718                                               &mgr->pbn_div)) {
2719                         ret = -EINVAL;
2720                         goto out_unlock;
2721                 }
2722 
2723                 /* add initial branch device at LCT 1 */
2724                 mstb = drm_dp_add_mst_branch_device(1, NULL);
2725                 if (mstb == NULL) {
2726                         ret = -ENOMEM;
2727                         goto out_unlock;
2728                 }
2729                 mstb->mgr = mgr;
2730 
2731                 /* give this the main reference */
2732                 mgr->mst_primary = mstb;
2733                 drm_dp_mst_topology_get_mstb(mgr->mst_primary);
2734 
2735                 ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
2736                                                          DP_MST_EN | DP_UP_REQ_EN | DP_UPSTREAM_IS_SRC);
2737                 if (ret < 0) {
2738                         goto out_unlock;
2739                 }
2740 
2741                 {
2742                         struct drm_dp_payload reset_pay;
2743                         reset_pay.start_slot = 0;
2744                         reset_pay.num_slots = 0x3f;
2745                         drm_dp_dpcd_write_payload(mgr, 0, &reset_pay);
2746                 }
2747 
2748                 queue_work(system_long_wq, &mgr->work);
2749 
2750                 ret = 0;
2751         } else {
2752                 /* disable MST on the device */
2753                 mstb = mgr->mst_primary;
2754                 mgr->mst_primary = NULL;
2755                 /* this can fail if the device is gone */
2756                 drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
2757                 ret = 0;
2758                 memset(mgr->payloads, 0,
2759                        mgr->max_payloads * sizeof(mgr->payloads[0]));
2760                 memset(mgr->proposed_vcpis, 0,
2761                        mgr->max_payloads * sizeof(mgr->proposed_vcpis[0]));
2762                 mgr->payload_mask = 0;
2763                 set_bit(0, &mgr->payload_mask);
2764                 mgr->vcpi_mask = 0;
2765         }
2766 
2767 out_unlock:
2768         mutex_unlock(&mgr->lock);
2769         mutex_unlock(&mgr->payload_lock);
2770         if (mstb)
2771                 drm_dp_mst_topology_put_mstb(mstb);
2772         return ret;
2773 
2774 }
2775 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_set_mst);
2776 
2777 /**
2778  * drm_dp_mst_topology_mgr_suspend() - suspend the MST manager
2779  * @mgr: manager to suspend
2780  *
2781  * This function tells the MST device that we can't handle UP messages
2782  * anymore. This should stop it from sending any since we are suspended.
2783  */
2784 void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr)
2785 {
2786         mutex_lock(&mgr->lock);
2787         drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
2788                            DP_MST_EN | DP_UPSTREAM_IS_SRC);
2789         mutex_unlock(&mgr->lock);
2790         flush_work(&mgr->work);
2791         flush_work(&mgr->destroy_connector_work);
2792 }
2793 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_suspend);
2794 
2795 /**
2796  * drm_dp_mst_topology_mgr_resume() - resume the MST manager
2797  * @mgr: manager to resume
2798  *
2799  * This will fetch DPCD and see if the device is still there,
2800  * if it is, it will rewrite the MSTM control bits, and return.
2801  *
2802  * if the device fails this returns -1, and the driver should do
2803  * a full MST reprobe, in case we were undocked.
2804  */
2805 int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr)
2806 {
2807         int ret = 0;
2808 
2809         mutex_lock(&mgr->lock);
2810 
2811         if (mgr->mst_primary) {
2812                 int sret;
2813                 u8 guid[16];
2814 
2815                 sret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, DP_RECEIVER_CAP_SIZE);
2816                 if (sret != DP_RECEIVER_CAP_SIZE) {
2817                         DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n");
2818                         ret = -1;
2819                         goto out_unlock;
2820                 }
2821 
2822                 ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
2823                                          DP_MST_EN | DP_UP_REQ_EN | DP_UPSTREAM_IS_SRC);
2824                 if (ret < 0) {
2825                         DRM_DEBUG_KMS("mst write failed - undocked during suspend?\n");
2826                         ret = -1;
2827                         goto out_unlock;
2828                 }
2829 
2830                 /* Some hubs forget their guids after they resume */
2831                 sret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16);
2832                 if (sret != 16) {
2833                         DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n");
2834                         ret = -1;
2835                         goto out_unlock;
2836                 }
2837                 drm_dp_check_mstb_guid(mgr->mst_primary, guid);
2838 
2839                 ret = 0;
2840         } else
2841                 ret = -1;
2842 
2843 out_unlock:
2844         mutex_unlock(&mgr->lock);
2845         return ret;
2846 }
2847 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume);
2848 
2849 static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
2850 {
2851         int len;
2852         u8 replyblock[32];
2853         int replylen, origlen, curreply;
2854         int ret;
2855         struct drm_dp_sideband_msg_rx *msg;
2856         int basereg = up ? DP_SIDEBAND_MSG_UP_REQ_BASE : DP_SIDEBAND_MSG_DOWN_REP_BASE;
2857         msg = up ? &mgr->up_req_recv : &mgr->down_rep_recv;
2858 
2859         len = min(mgr->max_dpcd_transaction_bytes, 16);
2860         ret = drm_dp_dpcd_read(mgr->aux, basereg,
2861                                replyblock, len);
2862         if (ret != len) {
2863                 DRM_DEBUG_KMS("failed to read DPCD down rep %d %d\n", len, ret);
2864                 return false;
2865         }
2866         ret = drm_dp_sideband_msg_build(msg, replyblock, len, true);
2867         if (!ret) {
2868                 DRM_DEBUG_KMS("sideband msg build failed %d\n", replyblock[0]);
2869                 return false;
2870         }
2871         replylen = msg->curchunk_len + msg->curchunk_hdrlen;
2872 
2873         origlen = replylen;
2874         replylen -= len;
2875         curreply = len;
2876         while (replylen > 0) {
2877                 len = min3(replylen, mgr->max_dpcd_transaction_bytes, 16);
2878                 ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply,
2879                                     replyblock, len);
2880                 if (ret != len) {
2881                         DRM_DEBUG_KMS("failed to read a chunk (len %d, ret %d)\n",
2882                                       len, ret);
2883                         return false;
2884                 }
2885 
2886                 ret = drm_dp_sideband_msg_build(msg, replyblock, len, false);
2887                 if (!ret) {
2888                         DRM_DEBUG_KMS("failed to build sideband msg\n");
2889                         return false;
2890                 }
2891 
2892                 curreply += len;
2893                 replylen -= len;
2894         }
2895         return true;
2896 }
2897 
2898 static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
2899 {
2900         int ret = 0;
2901 
2902         if (!drm_dp_get_one_sb_msg(mgr, false)) {
2903                 memset(&mgr->down_rep_recv, 0,
2904                        sizeof(struct drm_dp_sideband_msg_rx));
2905                 return 0;
2906         }
2907 
2908         if (mgr->down_rep_recv.have_eomt) {
2909                 struct drm_dp_sideband_msg_tx *txmsg;
2910                 struct drm_dp_mst_branch *mstb;
2911                 int slot = -1;
2912                 mstb = drm_dp_get_mst_branch_device(mgr,
2913                                                     mgr->down_rep_recv.initial_hdr.lct,
2914                                                     mgr->down_rep_recv.initial_hdr.rad);
2915 
2916                 if (!mstb) {
2917                         DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->down_rep_recv.initial_hdr.lct);
2918                         memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
2919                         return 0;
2920                 }
2921 
2922                 /* find the message */
2923                 slot = mgr->down_rep_recv.initial_hdr.seqno;
2924                 mutex_lock(&mgr->qlock);
2925                 txmsg = mstb->tx_slots[slot];
2926                 /* remove from slots */
2927                 mutex_unlock(&mgr->qlock);
2928 
2929                 if (!txmsg) {
2930                         DRM_DEBUG_KMS("Got MST reply with no msg %p %d %d %02x %02x\n",
2931                                mstb,
2932                                mgr->down_rep_recv.initial_hdr.seqno,
2933                                mgr->down_rep_recv.initial_hdr.lct,
2934                                       mgr->down_rep_recv.initial_hdr.rad[0],
2935                                       mgr->down_rep_recv.msg[0]);
2936                         drm_dp_mst_topology_put_mstb(mstb);
2937                         memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
2938                         return 0;
2939                 }
2940 
2941                 drm_dp_sideband_parse_reply(&mgr->down_rep_recv, &txmsg->reply);
2942 
2943                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
2944                         DRM_DEBUG_KMS("Got NAK reply: req 0x%02x (%s), reason 0x%02x (%s), nak data 0x%02x\n",
2945                                       txmsg->reply.req_type,
2946                                       drm_dp_mst_req_type_str(txmsg->reply.req_type),
2947                                       txmsg->reply.u.nak.reason,
2948                                       drm_dp_mst_nak_reason_str(txmsg->reply.u.nak.reason),
2949                                       txmsg->reply.u.nak.nak_data);
2950 
2951                 memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
2952                 drm_dp_mst_topology_put_mstb(mstb);
2953 
2954                 mutex_lock(&mgr->qlock);
2955                 txmsg->state = DRM_DP_SIDEBAND_TX_RX;
2956                 mstb->tx_slots[slot] = NULL;
2957                 mutex_unlock(&mgr->qlock);
2958 
2959                 wake_up_all(&mgr->tx_waitq);
2960         }
2961         return ret;
2962 }
2963 
2964 static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
2965 {
2966         int ret = 0;
2967 
2968         if (!drm_dp_get_one_sb_msg(mgr, true)) {
2969                 memset(&mgr->up_req_recv, 0,
2970                        sizeof(struct drm_dp_sideband_msg_rx));
2971                 return 0;
2972         }
2973 
2974         if (mgr->up_req_recv.have_eomt) {
2975                 struct drm_dp_sideband_msg_req_body msg;
2976                 struct drm_dp_mst_branch *mstb = NULL;
2977                 bool seqno;
2978 
2979                 if (!mgr->up_req_recv.initial_hdr.broadcast) {
2980                         mstb = drm_dp_get_mst_branch_device(mgr,
2981                                                             mgr->up_req_recv.initial_hdr.lct,
2982                                                             mgr->up_req_recv.initial_hdr.rad);
2983                         if (!mstb) {
2984                                 DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->up_req_recv.initial_hdr.lct);
2985                                 memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
2986                                 return 0;
2987                         }
2988                 }
2989 
2990                 seqno = mgr->up_req_recv.initial_hdr.seqno;
2991                 drm_dp_sideband_parse_req(&mgr->up_req_recv, &msg);
2992 
2993                 if (msg.req_type == DP_CONNECTION_STATUS_NOTIFY) {
2994                         drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, msg.req_type, seqno, false);
2995 
2996                         if (!mstb)
2997                                 mstb = drm_dp_get_mst_branch_device_by_guid(mgr, msg.u.conn_stat.guid);
2998 
2999                         if (!mstb) {
3000                                 DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->up_req_recv.initial_hdr.lct);
3001                                 memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
3002                                 return 0;
3003                         }
3004 
3005                         drm_dp_update_port(mstb, &msg.u.conn_stat);
3006 
3007                         DRM_DEBUG_KMS("Got CSN: pn: %d ldps:%d ddps: %d mcs: %d ip: %d pdt: %d\n", msg.u.conn_stat.port_number, msg.u.conn_stat.legacy_device_plug_status, msg.u.conn_stat.displayport_device_plug_status, msg.u.conn_stat.message_capability_status, msg.u.conn_stat.input_port, msg.u.conn_stat.peer_device_type);
3008                         drm_kms_helper_hotplug_event(mgr->dev);
3009 
3010                 } else if (msg.req_type == DP_RESOURCE_STATUS_NOTIFY) {
3011                         drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, msg.req_type, seqno, false);
3012                         if (!mstb)
3013                                 mstb = drm_dp_get_mst_branch_device_by_guid(mgr, msg.u.resource_stat.guid);
3014 
3015                         if (!mstb) {
3016                                 DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->up_req_recv.initial_hdr.lct);
3017                                 memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
3018                                 return 0;
3019                         }
3020 
3021                         DRM_DEBUG_KMS("Got RSN: pn: %d avail_pbn %d\n", msg.u.resource_stat.port_number, msg.u.resource_stat.available_pbn);
3022                 }
3023 
3024                 if (mstb)
3025                         drm_dp_mst_topology_put_mstb(mstb);
3026 
3027                 memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
3028         }
3029         return ret;
3030 }
3031 
3032 /**
3033  * drm_dp_mst_hpd_irq() - MST hotplug IRQ notify
3034  * @mgr: manager to notify irq for.
3035  * @esi: 4 bytes from SINK_COUNT_ESI
3036  * @handled: whether the hpd interrupt was consumed or not
3037  *
3038  * This should be called from the driver when it detects a short IRQ,
3039  * along with the value of the DEVICE_SERVICE_IRQ_VECTOR_ESI0. The
3040  * topology manager will process the sideband messages received as a result
3041  * of this.
3042  */
3043 int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled)
3044 {
3045         int ret = 0;
3046         int sc;
3047         *handled = false;
3048         sc = esi[0] & 0x3f;
3049 
3050         if (sc != mgr->sink_count) {
3051                 mgr->sink_count = sc;
3052                 *handled = true;
3053         }
3054 
3055         if (esi[1] & DP_DOWN_REP_MSG_RDY) {
3056                 ret = drm_dp_mst_handle_down_rep(mgr);
3057                 *handled = true;
3058         }
3059 
3060         if (esi[1] & DP_UP_REQ_MSG_RDY) {
3061                 ret |= drm_dp_mst_handle_up_req(mgr);
3062                 *handled = true;
3063         }
3064 
3065         drm_dp_mst_kick_tx(mgr);
3066         return ret;
3067 }
3068 EXPORT_SYMBOL(drm_dp_mst_hpd_irq);
3069 
3070 /**
3071  * drm_dp_mst_detect_port() - get connection status for an MST port
3072  * @connector: DRM connector for this port
3073  * @mgr: manager for this port
3074  * @port: unverified pointer to a port
3075  *
3076  * This returns the current connection state for a port. It validates the
3077  * port pointer still exists so the caller doesn't require a reference
3078  */
3079 enum drm_connector_status drm_dp_mst_detect_port(struct drm_connector *connector,
3080                                                  struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
3081 {
3082         enum drm_connector_status status = connector_status_disconnected;
3083 
3084         /* we need to search for the port in the mgr in case it's gone */
3085         port = drm_dp_mst_topology_get_port_validated(mgr, port);
3086         if (!port)
3087                 return connector_status_disconnected;
3088 
3089         if (!port->ddps)
3090                 goto out;
3091 
3092         switch (port->pdt) {
3093         case DP_PEER_DEVICE_NONE:
3094         case DP_PEER_DEVICE_MST_BRANCHING:
3095                 break;
3096 
3097         case DP_PEER_DEVICE_SST_SINK:
3098                 status = connector_status_connected;
3099                 /* for logical ports - cache the EDID */
3100                 if (port->port_num >= 8 && !port->cached_edid) {
3101                         port->cached_edid = drm_get_edid(connector, &port->aux.ddc);
3102                 }
3103                 break;
3104         case DP_PEER_DEVICE_DP_LEGACY_CONV:
3105                 if (port->ldps)
3106                         status = connector_status_connected;
3107                 break;
3108         }
3109 out:
3110         drm_dp_mst_topology_put_port(port);
3111         return status;
3112 }
3113 EXPORT_SYMBOL(drm_dp_mst_detect_port);
3114 
3115 /**
3116  * drm_dp_mst_port_has_audio() - Check whether port has audio capability or not
3117  * @mgr: manager for this port
3118  * @port: unverified pointer to a port.
3119  *
3120  * This returns whether the port supports audio or not.
3121  */
3122 bool drm_dp_mst_port_has_audio(struct drm_dp_mst_topology_mgr *mgr,
3123                                         struct drm_dp_mst_port *port)
3124 {
3125         bool ret = false;
3126 
3127         port = drm_dp_mst_topology_get_port_validated(mgr, port);
3128         if (!port)
3129                 return ret;
3130         ret = port->has_audio;
3131         drm_dp_mst_topology_put_port(port);
3132         return ret;
3133 }
3134 EXPORT_SYMBOL(drm_dp_mst_port_has_audio);
3135 
3136 /**
3137  * drm_dp_mst_get_edid() - get EDID for an MST port
3138  * @connector: toplevel connector to get EDID for
3139  * @mgr: manager for this port
3140  * @port: unverified pointer to a port.
3141  *
3142  * This returns an EDID for the port connected to a connector,
3143  * It validates the pointer still exists so the caller doesn't require a
3144  * reference.
3145  */
3146 struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
3147 {
3148         struct edid *edid = NULL;
3149 
3150         /* we need to search for the port in the mgr in case it's gone */
3151         port = drm_dp_mst_topology_get_port_validated(mgr, port);
3152         if (!port)
3153                 return NULL;
3154 
3155         if (port->cached_edid)
3156                 edid = drm_edid_duplicate(port->cached_edid);
3157         else {
3158                 edid = drm_get_edid(connector, &port->aux.ddc);
3159         }
3160         port->has_audio = drm_detect_monitor_audio(edid);
3161         drm_dp_mst_topology_put_port(port);
3162         return edid;
3163 }
3164 EXPORT_SYMBOL(drm_dp_mst_get_edid);
3165 
3166 /**
3167  * drm_dp_find_vcpi_slots() - Find VCPI slots for this PBN value
3168  * @mgr: manager to use
3169  * @pbn: payload bandwidth to convert into slots.
3170  *
3171  * Calculate the number of VCPI slots that will be required for the given PBN
3172  * value. This function is deprecated, and should not be used in atomic
3173  * drivers.
3174  *
3175  * RETURNS:
3176  * The total slots required for this port, or error.
3177  */
3178 int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
3179                            int pbn)
3180 {
3181         int num_slots;
3182 
3183         num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
3184 
3185         /* max. time slots - one slot for MTP header */
3186         if (num_slots > 63)
3187                 return -ENOSPC;
3188         return num_slots;
3189 }
3190 EXPORT_SYMBOL(drm_dp_find_vcpi_slots);
3191 
3192 static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
3193                             struct drm_dp_vcpi *vcpi, int pbn, int slots)
3194 {
3195         int ret;
3196 
3197         /* max. time slots - one slot for MTP header */
3198         if (slots > 63)
3199                 return -ENOSPC;
3200 
3201         vcpi->pbn = pbn;
3202         vcpi->aligned_pbn = slots * mgr->pbn_div;
3203         vcpi->num_slots = slots;
3204 
3205         ret = drm_dp_mst_assign_payload_id(mgr, vcpi);
3206         if (ret < 0)
3207                 return ret;
3208         return 0;
3209 }
3210 
3211 /**
3212  * drm_dp_atomic_find_vcpi_slots() - Find and add VCPI slots to the state
3213  * @state: global atomic state
3214  * @mgr: MST topology manager for the port
3215  * @port: port to find vcpi slots for
3216  * @pbn: bandwidth required for the mode in PBN
3217  *
3218  * Allocates VCPI slots to @port, replacing any previous VCPI allocations it
3219  * may have had. Any atomic drivers which support MST must call this function
3220  * in their &drm_encoder_helper_funcs.atomic_check() callback to change the
3221  * current VCPI allocation for the new state, but only when
3222  * &drm_crtc_state.mode_changed or &drm_crtc_state.connectors_changed is set
3223  * to ensure compatibility with userspace applications that still use the
3224  * legacy modesetting UAPI.
3225  *
3226  * Allocations set by this function are not checked against the bandwidth
3227  * restraints of @mgr until the driver calls drm_dp_mst_atomic_check().
3228  *
3229  * Additionally, it is OK to call this function multiple times on the same
3230  * @port as needed. It is not OK however, to call this function and
3231  * drm_dp_atomic_release_vcpi_slots() in the same atomic check phase.
3232  *
3233  * See also:
3234  * drm_dp_atomic_release_vcpi_slots()
3235  * drm_dp_mst_atomic_check()
3236  *
3237  * Returns:
3238  * Total slots in the atomic state assigned for this port, or a negative error
3239  * code if the port no longer exists
3240  */
3241 int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
3242                                   struct drm_dp_mst_topology_mgr *mgr,
3243                                   struct drm_dp_mst_port *port, int pbn)
3244 {
3245         struct drm_dp_mst_topology_state *topology_state;
3246         struct drm_dp_vcpi_allocation *pos, *vcpi = NULL;
3247         int prev_slots, req_slots, ret;
3248 
3249         topology_state = drm_atomic_get_mst_topology_state(state, mgr);
3250         if (IS_ERR(topology_state))
3251                 return PTR_ERR(topology_state);
3252 
3253         /* Find the current allocation for this port, if any */
3254         list_for_each_entry(pos, &topology_state->vcpis, next) {
3255                 if (pos->port == port) {
3256                         vcpi = pos;
3257                         prev_slots = vcpi->vcpi;
3258 
3259                         /*
3260                          * This should never happen, unless the driver tries
3261                          * releasing and allocating the same VCPI allocation,
3262                          * which is an error
3263                          */
3264                         if (WARN_ON(!prev_slots)) {
3265                                 DRM_ERROR("cannot allocate and release VCPI on [MST PORT:%p] in the same state\n",
3266                                           port);
3267                                 return -EINVAL;
3268                         }
3269 
3270                         break;
3271                 }
3272         }
3273         if (!vcpi)
3274                 prev_slots = 0;
3275 
3276         req_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
3277 
3278         DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] VCPI %d -> %d\n",
3279                          port->connector->base.id, port->connector->name,
3280                          port, prev_slots, req_slots);
3281 
3282         /* Add the new allocation to the state */
3283         if (!vcpi) {
3284                 vcpi = kzalloc(sizeof(*vcpi), GFP_KERNEL);
3285                 if (!vcpi)
3286                         return -ENOMEM;
3287 
3288                 drm_dp_mst_get_port_malloc(port);
3289                 vcpi->port = port;
3290                 list_add(&vcpi->next, &topology_state->vcpis);
3291         }
3292         vcpi->vcpi = req_slots;
3293 
3294         ret = req_slots;
3295         return ret;
3296 }
3297 EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);
3298 
3299 /**
3300  * drm_dp_atomic_release_vcpi_slots() - Release allocated vcpi slots
3301  * @state: global atomic state
3302  * @mgr: MST topology manager for the port
3303  * @port: The port to release the VCPI slots from
3304  *
3305  * Releases any VCPI slots that have been allocated to a port in the atomic
3306  * state. Any atomic drivers which support MST must call this function in
3307  * their &drm_connector_helper_funcs.atomic_check() callback when the
3308  * connector will no longer have VCPI allocated (e.g. because its CRTC was
3309  * removed) when it had VCPI allocated in the previous atomic state.
3310  *
3311  * It is OK to call this even if @port has been removed from the system.
3312  * Additionally, it is OK to call this function multiple times on the same
3313  * @port as needed. It is not OK however, to call this function and
3314  * drm_dp_atomic_find_vcpi_slots() on the same @port in a single atomic check
3315  * phase.
3316  *
3317  * See also:
3318  * drm_dp_atomic_find_vcpi_slots()
3319  * drm_dp_mst_atomic_check()
3320  *
3321  * Returns:
3322  * 0 if all slots for this port were added back to
3323  * &drm_dp_mst_topology_state.avail_slots or negative error code
3324  */
3325 int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
3326                                      struct drm_dp_mst_topology_mgr *mgr,
3327                                      struct drm_dp_mst_port *port)
3328 {
3329         struct drm_dp_mst_topology_state *topology_state;
3330         struct drm_dp_vcpi_allocation *pos;
3331         bool found = false;
3332 
3333         topology_state = drm_atomic_get_mst_topology_state(state, mgr);
3334         if (IS_ERR(topology_state))
3335                 return PTR_ERR(topology_state);
3336 
3337         list_for_each_entry(pos, &topology_state->vcpis, next) {
3338                 if (pos->port == port) {
3339                         found = true;
3340                         break;
3341                 }
3342         }
3343         if (WARN_ON(!found)) {
3344                 DRM_ERROR("no VCPI for [MST PORT:%p] found in mst state %p\n",
3345                           port, &topology_state->base);
3346                 return -EINVAL;
3347         }
3348 
3349         DRM_DEBUG_ATOMIC("[MST PORT:%p] VCPI %d -> 0\n", port, pos->vcpi);
3350         if (pos->vcpi) {
3351                 drm_dp_mst_put_port_malloc(port);
3352                 pos->vcpi = 0;
3353         }
3354 
3355         return 0;
3356 }
3357 EXPORT_SYMBOL(drm_dp_atomic_release_vcpi_slots);
3358 
3359 /**
3360  * drm_dp_mst_allocate_vcpi() - Allocate a virtual channel
3361  * @mgr: manager for this port
3362  * @port: port to allocate a virtual channel for.
3363  * @pbn: payload bandwidth number to request
3364  * @slots: returned number of slots for this PBN.
3365  */
3366 bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
3367                               struct drm_dp_mst_port *port, int pbn, int slots)
3368 {
3369         int ret;
3370 
3371         port = drm_dp_mst_topology_get_port_validated(mgr, port);
3372         if (!port)
3373                 return false;
3374 
3375         if (slots < 0)
3376                 return false;
3377 
3378         if (port->vcpi.vcpi > 0) {
3379                 DRM_DEBUG_KMS("payload: vcpi %d already allocated for pbn %d - requested pbn %d\n",
3380                               port->vcpi.vcpi, port->vcpi.pbn, pbn);
3381                 if (pbn == port->vcpi.pbn) {
3382                         drm_dp_mst_topology_put_port(port);
3383                         return true;
3384                 }
3385         }
3386 
3387         ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn, slots);
3388         if (ret) {
3389                 DRM_DEBUG_KMS("failed to init vcpi slots=%d max=63 ret=%d\n",
3390                               DIV_ROUND_UP(pbn, mgr->pbn_div), ret);
3391                 goto out;
3392         }
3393         DRM_DEBUG_KMS("initing vcpi for pbn=%d slots=%d\n",
3394                       pbn, port->vcpi.num_slots);
3395 
3396         /* Keep port allocated until its payload has been removed */
3397         drm_dp_mst_get_port_malloc(port);
3398         drm_dp_mst_topology_put_port(port);
3399         return true;
3400 out:
3401         return false;
3402 }
3403 EXPORT_SYMBOL(drm_dp_mst_allocate_vcpi);
3404 
3405 int drm_dp_mst_get_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
3406 {
3407         int slots = 0;
3408         port = drm_dp_mst_topology_get_port_validated(mgr, port);
3409         if (!port)
3410                 return slots;
3411 
3412         slots = port->vcpi.num_slots;
3413         drm_dp_mst_topology_put_port(port);
3414         return slots;
3415 }
3416 EXPORT_SYMBOL(drm_dp_mst_get_vcpi_slots);
3417 
3418 /**
3419  * drm_dp_mst_reset_vcpi_slots() - Reset number of slots to 0 for VCPI
3420  * @mgr: manager for this port
3421  * @port: unverified pointer to a port.
3422  *
3423  * This just resets the number of slots for the ports VCPI for later programming.
3424  */
3425 void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
3426 {
3427         /*
3428          * A port with VCPI will remain allocated until its VCPI is
3429          * released, no verified ref needed
3430          */
3431 
3432         port->vcpi.num_slots = 0;
3433 }
3434 EXPORT_SYMBOL(drm_dp_mst_reset_vcpi_slots);
3435 
3436 /**
3437  * drm_dp_mst_deallocate_vcpi() - deallocate a VCPI
3438  * @mgr: manager for this port
3439  * @port: port to deallocate vcpi for
3440  *
3441  * This can be called unconditionally, regardless of whether
3442  * drm_dp_mst_allocate_vcpi() succeeded or not.
3443  */
3444 void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
3445                                 struct drm_dp_mst_port *port)
3446 {
3447         if (!port->vcpi.vcpi)
3448                 return;
3449 
3450         drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
3451         port->vcpi.num_slots = 0;
3452         port->vcpi.pbn = 0;
3453         port->vcpi.aligned_pbn = 0;
3454         port->vcpi.vcpi = 0;
3455         drm_dp_mst_put_port_malloc(port);
3456 }
3457 EXPORT_SYMBOL(drm_dp_mst_deallocate_vcpi);
3458 
3459 static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
3460                                      int id, struct drm_dp_payload *payload)
3461 {
3462         u8 payload_alloc[3], status;
3463         int ret;
3464         int retries = 0;
3465 
3466         drm_dp_dpcd_writeb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
3467                            DP_PAYLOAD_TABLE_UPDATED);
3468 
3469         payload_alloc[0] = id;
3470         payload_alloc[1] = payload->start_slot;
3471         payload_alloc[2] = payload->num_slots;
3472 
3473         ret = drm_dp_dpcd_write(mgr->aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
3474         if (ret != 3) {
3475                 DRM_DEBUG_KMS("failed to write payload allocation %d\n", ret);
3476                 goto fail;
3477         }
3478 
3479 retry:
3480         ret = drm_dp_dpcd_readb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
3481         if (ret < 0) {
3482                 DRM_DEBUG_KMS("failed to read payload table status %d\n", ret);
3483                 goto fail;
3484         }
3485 
3486         if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
3487                 retries++;
3488                 if (retries < 20) {
3489                         usleep_range(10000, 20000);
3490                         goto retry;
3491                 }
3492                 DRM_DEBUG_KMS("status not set after read payload table status %d\n", status);
3493                 ret = -EINVAL;
3494                 goto fail;
3495         }
3496         ret = 0;
3497 fail:
3498         return ret;
3499 }
3500 
3501 
3502 /**
3503  * drm_dp_check_act_status() - Check ACT handled status.
3504  * @mgr: manager to use
3505  *
3506  * Check the payload status bits in the DPCD for ACT handled completion.
3507  */
3508 int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr)
3509 {
3510         u8 status;
3511         int ret;
3512         int count = 0;
3513 
3514         do {
3515                 ret = drm_dp_dpcd_readb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
3516 
3517                 if (ret < 0) {
3518                         DRM_DEBUG_KMS("failed to read payload table status %d\n", ret);
3519                         goto fail;
3520                 }
3521 
3522                 if (status & DP_PAYLOAD_ACT_HANDLED)
3523                         break;
3524                 count++;
3525                 udelay(100);
3526 
3527         } while (count < 30);
3528 
3529         if (!(status & DP_PAYLOAD_ACT_HANDLED)) {
3530                 DRM_DEBUG_KMS("failed to get ACT bit %d after %d retries\n", status, count);
3531                 ret = -EINVAL;
3532                 goto fail;
3533         }
3534         return 0;
3535 fail:
3536         return ret;
3537 }
3538 EXPORT_SYMBOL(drm_dp_check_act_status);
3539 
3540 /**
3541  * drm_dp_calc_pbn_mode() - Calculate the PBN for a mode.
3542  * @clock: dot clock for the mode
3543  * @bpp: bpp for the mode.
3544  *
3545  * This uses the formula in the spec to calculate the PBN value for a mode.
3546  */
3547 int drm_dp_calc_pbn_mode(int clock, int bpp)
3548 {
3549         u64 kbps;
3550         s64 peak_kbps;
3551         u32 numerator;
3552         u32 denominator;
3553 
3554         kbps = clock * bpp;
3555 
3556         /*
3557          * margin 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006
3558          * The unit of 54/64Mbytes/sec is an arbitrary unit chosen based on
3559          * common multiplier to render an integer PBN for all link rate/lane
3560          * counts combinations
3561          * calculate
3562          * peak_kbps *= (1006/1000)
3563          * peak_kbps *= (64/54)
3564          * peak_kbps *= 8    convert to bytes
3565          */
3566 
3567         numerator = 64 * 1006;
3568         denominator = 54 * 8 * 1000 * 1000;
3569 
3570         kbps *= numerator;
3571         peak_kbps = drm_fixp_from_fraction(kbps, denominator);
3572 
3573         return drm_fixp2int_ceil(peak_kbps);
3574 }
3575 EXPORT_SYMBOL(drm_dp_calc_pbn_mode);
3576 
3577 static int test_calc_pbn_mode(void)
3578 {
3579         int ret;
3580         ret = drm_dp_calc_pbn_mode(154000, 30);
3581         if (ret != 689) {
3582                 DRM_ERROR("PBN calculation test failed - clock %d, bpp %d, expected PBN %d, actual PBN %d.\n",
3583                                 154000, 30, 689, ret);
3584                 return -EINVAL;
3585         }
3586         ret = drm_dp_calc_pbn_mode(234000, 30);
3587         if (ret != 1047) {
3588                 DRM_ERROR("PBN calculation test failed - clock %d, bpp %d, expected PBN %d, actual PBN %d.\n",
3589                                 234000, 30, 1047, ret);
3590                 return -EINVAL;
3591         }
3592         ret = drm_dp_calc_pbn_mode(297000, 24);
3593         if (ret != 1063) {
3594                 DRM_ERROR("PBN calculation test failed - clock %d, bpp %d, expected PBN %d, actual PBN %d.\n",
3595                                 297000, 24, 1063, ret);
3596                 return -EINVAL;
3597         }
3598         return 0;
3599 }
3600 
3601 /* we want to kick the TX after we've ack the up/down IRQs. */
3602 static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr)
3603 {
3604         queue_work(system_long_wq, &mgr->tx_work);
3605 }
3606 
3607 static void drm_dp_mst_dump_mstb(struct seq_file *m,
3608                                  struct drm_dp_mst_branch *mstb)
3609 {
3610         struct drm_dp_mst_port *port;
3611         int tabs = mstb->lct;
3612         char prefix[10];
3613         int i;
3614 
3615         for (i = 0; i < tabs; i++)
3616                 prefix[i] = '\t';
3617         prefix[i] = '\0';
3618 
3619         seq_printf(m, "%smst: %p, %d\n", prefix, mstb, mstb->num_ports);
3620         list_for_each_entry(port, &mstb->ports, next) {
3621                 seq_printf(m, "%sport: %d: input: %d: pdt: %d, ddps: %d ldps: %d, sdp: %d/%d, %p, conn: %p\n", prefix, port->port_num, port->input, port->pdt, port->ddps, port->ldps, port->num_sdp_streams, port->num_sdp_stream_sinks, port, port->connector);
3622                 if (port->mstb)
3623                         drm_dp_mst_dump_mstb(m, port->mstb);
3624         }
3625 }
3626 
3627 #define DP_PAYLOAD_TABLE_SIZE           64
3628 
3629 static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
3630                                   char *buf)
3631 {
3632         int i;
3633 
3634         for (i = 0; i < DP_PAYLOAD_TABLE_SIZE; i += 16) {
3635                 if (drm_dp_dpcd_read(mgr->aux,
3636                                      DP_PAYLOAD_TABLE_UPDATE_STATUS + i,
3637                                      &buf[i], 16) != 16)
3638                         return false;
3639         }
3640         return true;
3641 }
3642 
3643 static void fetch_monitor_name(struct drm_dp_mst_topology_mgr *mgr,
3644                                struct drm_dp_mst_port *port, char *name,
3645                                int namelen)
3646 {
3647         struct edid *mst_edid;
3648 
3649         mst_edid = drm_dp_mst_get_edid(port->connector, mgr, port);
3650         drm_edid_get_monitor_name(mst_edid, name, namelen);
3651 }
3652 
3653 /**
3654  * drm_dp_mst_dump_topology(): dump topology to seq file.
3655  * @m: seq_file to dump output to
3656  * @mgr: manager to dump current topology for.
3657  *
3658  * helper to dump MST topology to a seq file for debugfs.
3659  */
3660 void drm_dp_mst_dump_topology(struct seq_file *m,
3661                               struct drm_dp_mst_topology_mgr *mgr)
3662 {
3663         int i;
3664         struct drm_dp_mst_port *port;
3665 
3666         mutex_lock(&mgr->lock);
3667         if (mgr->mst_primary)
3668                 drm_dp_mst_dump_mstb(m, mgr->mst_primary);
3669 
3670         /* dump VCPIs */
3671         mutex_unlock(&mgr->lock);
3672 
3673         mutex_lock(&mgr->payload_lock);
3674         seq_printf(m, "vcpi: %lx %lx %d\n", mgr->payload_mask, mgr->vcpi_mask,
3675                 mgr->max_payloads);
3676 
3677         for (i = 0; i < mgr->max_payloads; i++) {
3678                 if (mgr->proposed_vcpis[i]) {
3679                         char name[14];
3680 
3681                         port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
3682                         fetch_monitor_name(mgr, port, name, sizeof(name));
3683                         seq_printf(m, "vcpi %d: %d %d %d sink name: %s\n", i,
3684                                    port->port_num, port->vcpi.vcpi,
3685                                    port->vcpi.num_slots,
3686                                    (*name != 0) ? name :  "Unknown");
3687                 } else
3688                         seq_printf(m, "vcpi %d:unused\n", i);
3689         }
3690         for (i = 0; i < mgr->max_payloads; i++) {
3691                 seq_printf(m, "payload %d: %d, %d, %d\n",
3692                            i,
3693                            mgr->payloads[i].payload_state,
3694                            mgr->payloads[i].start_slot,
3695                            mgr->payloads[i].num_slots);
3696 
3697 
3698         }
3699         mutex_unlock(&mgr->payload_lock);
3700 
3701         mutex_lock(&mgr->lock);
3702         if (mgr->mst_primary) {
3703                 u8 buf[DP_PAYLOAD_TABLE_SIZE];
3704                 int ret;
3705 
3706                 ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf, DP_RECEIVER_CAP_SIZE);
3707                 seq_printf(m, "dpcd: %*ph\n", DP_RECEIVER_CAP_SIZE, buf);
3708                 ret = drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2);
3709                 seq_printf(m, "faux/mst: %*ph\n", 2, buf);
3710                 ret = drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1);
3711                 seq_printf(m, "mst ctrl: %*ph\n", 1, buf);
3712 
3713                 /* dump the standard OUI branch header */
3714                 ret = drm_dp_dpcd_read(mgr->aux, DP_BRANCH_OUI, buf, DP_BRANCH_OUI_HEADER_SIZE);
3715                 seq_printf(m, "branch oui: %*phN devid: ", 3, buf);
3716                 for (i = 0x3; i < 0x8 && buf[i]; i++)
3717                         seq_printf(m, "%c", buf[i]);
3718                 seq_printf(m, " revision: hw: %x.%x sw: %x.%x\n",
3719                            buf[0x9] >> 4, buf[0x9] & 0xf, buf[0xa], buf[0xb]);
3720                 if (dump_dp_payload_table(mgr, buf))
3721                         seq_printf(m, "payload table: %*ph\n", DP_PAYLOAD_TABLE_SIZE, buf);
3722         }
3723 
3724         mutex_unlock(&mgr->lock);
3725 
3726 }
3727 EXPORT_SYMBOL(drm_dp_mst_dump_topology);
3728 
3729 static void drm_dp_tx_work(struct work_struct *work)
3730 {
3731         struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, tx_work);
3732 
3733         mutex_lock(&mgr->qlock);
3734         if (!list_empty(&mgr->tx_msg_downq))
3735                 process_single_down_tx_qlock(mgr);
3736         mutex_unlock(&mgr->qlock);
3737 }
3738 
3739 static void drm_dp_destroy_connector_work(struct work_struct *work)
3740 {
3741         struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, destroy_connector_work);
3742         struct drm_dp_mst_port *port;
3743         bool send_hotplug = false;
3744         /*
3745          * Not a regular list traverse as we have to drop the destroy
3746          * connector lock before destroying the connector, to avoid AB->BA
3747          * ordering between this lock and the config mutex.
3748          */
3749         for (;;) {
3750                 mutex_lock(&mgr->destroy_connector_lock);
3751                 port = list_first_entry_or_null(&mgr->destroy_connector_list, struct drm_dp_mst_port, next);
3752                 if (!port) {
3753                         mutex_unlock(&mgr->destroy_connector_lock);
3754                         break;
3755                 }
3756                 list_del(&port->next);
3757                 mutex_unlock(&mgr->destroy_connector_lock);
3758 
3759                 INIT_LIST_HEAD(&port->next);
3760 
3761                 mgr->cbs->destroy_connector(mgr, port->connector);
3762 
3763                 drm_dp_port_teardown_pdt(port, port->pdt);
3764                 port->pdt = DP_PEER_DEVICE_NONE;
3765 
3766                 drm_dp_mst_put_port_malloc(port);
3767                 send_hotplug = true;
3768         }
3769         if (send_hotplug)
3770                 drm_kms_helper_hotplug_event(mgr->dev);
3771 }
3772 
3773 static struct drm_private_state *
3774 drm_dp_mst_duplicate_state(struct drm_private_obj *obj)
3775 {
3776         struct drm_dp_mst_topology_state *state, *old_state =
3777                 to_dp_mst_topology_state(obj->state);
3778         struct drm_dp_vcpi_allocation *pos, *vcpi;
3779 
3780         state = kmemdup(old_state, sizeof(*state), GFP_KERNEL);
3781         if (!state)
3782                 return NULL;
3783 
3784         __drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);
3785 
3786         INIT_LIST_HEAD(&state->vcpis);
3787 
3788         list_for_each_entry(pos, &old_state->vcpis, next) {
3789                 /* Prune leftover freed VCPI allocations */
3790                 if (!pos->vcpi)
3791                         continue;
3792 
3793                 vcpi = kmemdup(pos, sizeof(*vcpi), GFP_KERNEL);
3794                 if (!vcpi)
3795                         goto fail;
3796 
3797                 drm_dp_mst_get_port_malloc(vcpi->port);
3798                 list_add(&vcpi->next, &state->vcpis);
3799         }
3800 
3801         return &state->base;
3802 
3803 fail:
3804         list_for_each_entry_safe(pos, vcpi, &state->vcpis, next) {
3805                 drm_dp_mst_put_port_malloc(pos->port);
3806                 kfree(pos);
3807         }
3808         kfree(state);
3809 
3810         return NULL;
3811 }
3812 
3813 static void drm_dp_mst_destroy_state(struct drm_private_obj *obj,
3814                                      struct drm_private_state *state)
3815 {
3816         struct drm_dp_mst_topology_state *mst_state =
3817                 to_dp_mst_topology_state(state);
3818         struct drm_dp_vcpi_allocation *pos, *tmp;
3819 
3820         list_for_each_entry_safe(pos, tmp, &mst_state->vcpis, next) {
3821                 /* We only keep references to ports with non-zero VCPIs */
3822                 if (pos->vcpi)
3823                         drm_dp_mst_put_port_malloc(pos->port);
3824                 kfree(pos);
3825         }
3826 
3827         kfree(mst_state);
3828 }
3829 
3830 static inline int
3831 drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr,
3832                                        struct drm_dp_mst_topology_state *mst_state)
3833 {
3834         struct drm_dp_vcpi_allocation *vcpi;
3835         int avail_slots = 63, payload_count = 0;
3836 
3837         list_for_each_entry(vcpi, &mst_state->vcpis, next) {
3838                 /* Releasing VCPI is always OK-even if the port is gone */
3839                 if (!vcpi->vcpi) {
3840                         DRM_DEBUG_ATOMIC("[MST PORT:%p] releases all VCPI slots\n",
3841                                          vcpi->port);
3842                         continue;
3843                 }
3844 
3845                 DRM_DEBUG_ATOMIC("[MST PORT:%p] requires %d vcpi slots\n",
3846                                  vcpi->port, vcpi->vcpi);
3847 
3848                 avail_slots -= vcpi->vcpi;
3849                 if (avail_slots < 0) {
3850                         DRM_DEBUG_ATOMIC("[MST PORT:%p] not enough VCPI slots in mst state %p (avail=%d)\n",
3851                                          vcpi->port, mst_state,
3852                                          avail_slots + vcpi->vcpi);
3853                         return -ENOSPC;
3854                 }
3855 
3856                 if (++payload_count > mgr->max_payloads) {
3857                         DRM_DEBUG_ATOMIC("[MST MGR:%p] state %p has too many payloads (max=%d)\n",
3858                                          mgr, mst_state, mgr->max_payloads);
3859                         return -EINVAL;
3860                 }
3861         }
3862         DRM_DEBUG_ATOMIC("[MST MGR:%p] mst state %p VCPI avail=%d used=%d\n",
3863                          mgr, mst_state, avail_slots,
3864                          63 - avail_slots);
3865 
3866         return 0;
3867 }
3868 
3869 /**
3870  * drm_dp_mst_atomic_check - Check that the new state of an MST topology in an
3871  * atomic update is valid
3872  * @state: Pointer to the new &struct drm_dp_mst_topology_state
3873  *
3874  * Checks the given topology state for an atomic update to ensure that it's
3875  * valid. This includes checking whether there's enough bandwidth to support
3876  * the new VCPI allocations in the atomic update.
3877  *
3878  * Any atomic drivers supporting DP MST must make sure to call this after
3879  * checking the rest of their state in their
3880  * &drm_mode_config_funcs.atomic_check() callback.
3881  *
3882  * See also:
3883  * drm_dp_atomic_find_vcpi_slots()
3884  * drm_dp_atomic_release_vcpi_slots()
3885  *
3886  * Returns:
3887  *
3888  * 0 if the new state is valid, negative error code otherwise.
3889  */
3890 int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
3891 {
3892         struct drm_dp_mst_topology_mgr *mgr;
3893         struct drm_dp_mst_topology_state *mst_state;
3894         int i, ret = 0;
3895 
3896         for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {
3897                 ret = drm_dp_mst_atomic_check_topology_state(mgr, mst_state);
3898                 if (ret)
3899                         break;
3900         }
3901 
3902         return ret;
3903 }
3904 EXPORT_SYMBOL(drm_dp_mst_atomic_check);
3905 
3906 const struct drm_private_state_funcs drm_dp_mst_topology_state_funcs = {
3907         .atomic_duplicate_state = drm_dp_mst_duplicate_state,
3908         .atomic_destroy_state = drm_dp_mst_destroy_state,
3909 };
3910 EXPORT_SYMBOL(drm_dp_mst_topology_state_funcs);
3911 
3912 /**
3913  * drm_atomic_get_mst_topology_state: get MST topology state
3914  *
3915  * @state: global atomic state
3916  * @mgr: MST topology manager, also the private object in this case
3917  *
3918  * This function wraps drm_atomic_get_priv_obj_state() passing in the MST atomic
3919  * state vtable so that the private object state returned is that of a MST
3920  * topology object. Also, drm_atomic_get_private_obj_state() expects the caller
3921  * to care of the locking, so warn if don't hold the connection_mutex.
3922  *
3923  * RETURNS:
3924  *
3925  * The MST topology state or error pointer.
3926  */
3927 struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
3928                                                                     struct drm_dp_mst_topology_mgr *mgr)
3929 {
3930         struct drm_device *dev = mgr->dev;
3931 
3932         WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
3933         return to_dp_mst_topology_state(drm_atomic_get_private_obj_state(state, &mgr->base));
3934 }
3935 EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
3936 
3937 /**
3938  * drm_dp_mst_topology_mgr_init - initialise a topology manager
3939  * @mgr: manager struct to initialise
3940  * @dev: device providing this structure - for i2c addition.
3941  * @aux: DP helper aux channel to talk to this device
3942  * @max_dpcd_transaction_bytes: hw specific DPCD transaction limit
3943  * @max_payloads: maximum number of payloads this GPU can source
3944  * @conn_base_id: the connector object ID the MST device is connected to.
3945  *
3946  * Return 0 for success, or negative error code on failure
3947  */
3948 int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
3949                                  struct drm_device *dev, struct drm_dp_aux *aux,
3950                                  int max_dpcd_transaction_bytes,
3951                                  int max_payloads, int conn_base_id)
3952 {
3953         struct drm_dp_mst_topology_state *mst_state;
3954 
3955         mutex_init(&mgr->lock);
3956         mutex_init(&mgr->qlock);
3957         mutex_init(&mgr->payload_lock);
3958         mutex_init(&mgr->destroy_connector_lock);
3959         INIT_LIST_HEAD(&mgr->tx_msg_downq);
3960         INIT_LIST_HEAD(&mgr->destroy_connector_list);
3961         INIT_WORK(&mgr->work, drm_dp_mst_link_probe_work);
3962         INIT_WORK(&mgr->tx_work, drm_dp_tx_work);
3963         INIT_WORK(&mgr->destroy_connector_work, drm_dp_destroy_connector_work);
3964         init_waitqueue_head(&mgr->tx_waitq);
3965         mgr->dev = dev;
3966         mgr->aux = aux;
3967         mgr->max_dpcd_transaction_bytes = max_dpcd_transaction_bytes;
3968         mgr->max_payloads = max_payloads;
3969         mgr->conn_base_id = conn_base_id;
3970         if (max_payloads + 1 > sizeof(mgr->payload_mask) * 8 ||
3971             max_payloads + 1 > sizeof(mgr->vcpi_mask) * 8)
3972                 return -EINVAL;
3973         mgr->payloads = kcalloc(max_payloads, sizeof(struct drm_dp_payload), GFP_KERNEL);
3974         if (!mgr->payloads)
3975                 return -ENOMEM;
3976         mgr->proposed_vcpis = kcalloc(max_payloads, sizeof(struct drm_dp_vcpi *), GFP_KERNEL);
3977         if (!mgr->proposed_vcpis)
3978                 return -ENOMEM;
3979         set_bit(0, &mgr->payload_mask);
3980         if (test_calc_pbn_mode() < 0)
3981                 DRM_ERROR("MST PBN self-test failed\n");
3982 
3983         mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
3984         if (mst_state == NULL)
3985                 return -ENOMEM;
3986 
3987         mst_state->mgr = mgr;
3988         INIT_LIST_HEAD(&mst_state->vcpis);
3989 
3990         drm_atomic_private_obj_init(dev, &mgr->base,
3991                                     &mst_state->base,
3992                                     &drm_dp_mst_topology_state_funcs);
3993 
3994         return 0;
3995 }
3996 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_init);
3997 
3998 /**
3999  * drm_dp_mst_topology_mgr_destroy() - destroy topology manager.
4000  * @mgr: manager to destroy
4001  */
4002 void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
4003 {
4004         drm_dp_mst_topology_mgr_set_mst(mgr, false);
4005         flush_work(&mgr->work);
4006         flush_work(&mgr->destroy_connector_work);
4007         mutex_lock(&mgr->payload_lock);
4008         kfree(mgr->payloads);
4009         mgr->payloads = NULL;
4010         kfree(mgr->proposed_vcpis);
4011         mgr->proposed_vcpis = NULL;
4012         mutex_unlock(&mgr->payload_lock);
4013         mgr->dev = NULL;
4014         mgr->aux = NULL;
4015         drm_atomic_private_obj_fini(&mgr->base);
4016         mgr->funcs = NULL;
4017 }
4018 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_destroy);
4019 
4020 static bool remote_i2c_read_ok(const struct i2c_msg msgs[], int num)
4021 {
4022         int i;
4023 
4024         if (num - 1 > DP_REMOTE_I2C_READ_MAX_TRANSACTIONS)
4025                 return false;
4026 
4027         for (i = 0; i < num - 1; i++) {
4028                 if (msgs[i].flags & I2C_M_RD ||
4029                     msgs[i].len > 0xff)
4030                         return false;
4031         }
4032 
4033         return msgs[num - 1].flags & I2C_M_RD &&
4034                 msgs[num - 1].len <= 0xff;
4035 }
4036 
4037 /* I2C device */
4038 static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
4039                                int num)
4040 {
4041         struct drm_dp_aux *aux = adapter->algo_data;
4042         struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port, aux);
4043         struct drm_dp_mst_branch *mstb;
4044         struct drm_dp_mst_topology_mgr *mgr = port->mgr;
4045         unsigned int i;
4046         struct drm_dp_sideband_msg_req_body msg;
4047         struct drm_dp_sideband_msg_tx *txmsg = NULL;
4048         int ret;
4049 
4050         mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
4051         if (!mstb)
4052                 return -EREMOTEIO;
4053 
4054         if (!remote_i2c_read_ok(msgs, num)) {
4055                 DRM_DEBUG_KMS("Unsupported I2C transaction for MST device\n");
4056                 ret = -EIO;
4057                 goto out;
4058         }
4059 
4060         memset(&msg, 0, sizeof(msg));
4061         msg.req_type = DP_REMOTE_I2C_READ;
4062         msg.u.i2c_read.num_transactions = num - 1;
4063         msg.u.i2c_read.port_number = port->port_num;
4064         for (i = 0; i < num - 1; i++) {
4065                 msg.u.i2c_read.transactions[i].i2c_dev_id = msgs[i].addr;
4066                 msg.u.i2c_read.transactions[i].num_bytes = msgs[i].len;
4067                 msg.u.i2c_read.transactions[i].bytes = msgs[i].buf;
4068                 msg.u.i2c_read.transactions[i].no_stop_bit = !(msgs[i].flags & I2C_M_STOP);
4069         }
4070         msg.u.i2c_read.read_i2c_device_id = msgs[num - 1].addr;
4071         msg.u.i2c_read.num_bytes_read = msgs[num - 1].len;
4072 
4073         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
4074         if (!txmsg) {
4075                 ret = -ENOMEM;
4076                 goto out;
4077         }
4078 
4079         txmsg->dst = mstb;
4080         drm_dp_encode_sideband_req(&msg, txmsg);
4081 
4082         drm_dp_queue_down_tx(mgr, txmsg);
4083 
4084         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
4085         if (ret > 0) {
4086 
4087                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
4088                         ret = -EREMOTEIO;
4089                         goto out;
4090                 }
4091                 if (txmsg->reply.u.remote_i2c_read_ack.num_bytes != msgs[num - 1].len) {
4092                         ret = -EIO;
4093                         goto out;
4094                 }
4095                 memcpy(msgs[num - 1].buf, txmsg->reply.u.remote_i2c_read_ack.bytes, msgs[num - 1].len);
4096                 ret = num;
4097         }
4098 out:
4099         kfree(txmsg);
4100         drm_dp_mst_topology_put_mstb(mstb);
4101         return ret;
4102 }
4103 
4104 static u32 drm_dp_mst_i2c_functionality(struct i2c_adapter *adapter)
4105 {
4106         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
4107                I2C_FUNC_SMBUS_READ_BLOCK_DATA |
4108                I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
4109                I2C_FUNC_10BIT_ADDR;
4110 }
4111 
4112 static const struct i2c_algorithm drm_dp_mst_i2c_algo = {
4113         .functionality = drm_dp_mst_i2c_functionality,
4114         .master_xfer = drm_dp_mst_i2c_xfer,
4115 };
4116 
4117 /**
4118  * drm_dp_mst_register_i2c_bus() - register an I2C adapter for I2C-over-AUX
4119  * @aux: DisplayPort AUX channel
4120  *
4121  * Returns 0 on success or a negative error code on failure.
4122  */
4123 static int drm_dp_mst_register_i2c_bus(struct drm_dp_aux *aux)
4124 {
4125         aux->ddc.algo = &drm_dp_mst_i2c_algo;
4126         aux->ddc.algo_data = aux;
4127         aux->ddc.retries = 3;
4128 
4129         aux->ddc.class = I2C_CLASS_DDC;
4130         aux->ddc.owner = THIS_MODULE;
4131         aux->ddc.dev.parent = aux->dev;
4132         aux->ddc.dev.of_node = aux->dev->of_node;
4133 
4134         strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
4135                 sizeof(aux->ddc.name));
4136 
4137         return i2c_add_adapter(&aux->ddc);
4138 }
4139 
4140 /**
4141  * drm_dp_mst_unregister_i2c_bus() - unregister an I2C-over-AUX adapter
4142  * @aux: DisplayPort AUX channel
4143  */
4144 static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_aux *aux)
4145 {
4146         i2c_del_adapter(&aux->ddc);
4147 }