1/*
2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
3 *
4 *   This program is free software; you can redistribute it and/or
5 *   modify it under the terms of the GNU General Public License
6 *   as published by the Free Software Foundation, version 2.
7 *
8 *   This program is distributed in the hope that it will be useful, but
9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 *   NON INFRINGEMENT.  See the GNU General Public License for
12 *   more details.
13 */
14
15/**
16 * @file drv_xgbe_intf.h
17 * Interface to the hypervisor XGBE driver.
18 */
19
20#ifndef __DRV_XGBE_INTF_H__
21#define __DRV_XGBE_INTF_H__
22
23/**
24 * An object for forwarding VAs and PAs to the hypervisor.
25 * @ingroup types
26 *
27 * This allows the supervisor to specify a number of areas of memory to
28 * store packet buffers.
29 */
30typedef struct
31{
32  /** The physical address of the memory. */
33  HV_PhysAddr pa;
34  /** Page table entry for the memory.  This is only used to derive the
35   *  memory's caching mode; the PA bits are ignored. */
36  HV_PTE pte;
37  /** The virtual address of the memory. */
38  HV_VirtAddr va;
39  /** Size (in bytes) of the memory area. */
40  int size;
41
42}
43netio_ipp_address_t;
44
45/** The various pread/pwrite offsets into the hypervisor-level driver.
46 * @ingroup types
47 */
48typedef enum
49{
50  /** Inform the Linux driver of the address of the NetIO arena memory.
51   *  This offset is actually only used to convey information from netio
52   *  to the Linux driver; it never makes it from there to the hypervisor.
53   *  Write-only; takes a uint32_t specifying the VA address. */
54  NETIO_FIXED_ADDR               = 0x5000000000000000ULL,
55
56  /** Inform the Linux driver of the size of the NetIO arena memory.
57   *  This offset is actually only used to convey information from netio
58   *  to the Linux driver; it never makes it from there to the hypervisor.
59   *  Write-only; takes a uint32_t specifying the VA size. */
60  NETIO_FIXED_SIZE               = 0x5100000000000000ULL,
61
62  /** Register current tile with IPP.  Write then read: write, takes a
63   *  netio_input_config_t, read returns a pointer to a netio_queue_impl_t. */
64  NETIO_IPP_INPUT_REGISTER_OFF   = 0x6000000000000000ULL,
65
66  /** Unregister current tile from IPP.  Write-only, takes a dummy argument. */
67  NETIO_IPP_INPUT_UNREGISTER_OFF = 0x6100000000000000ULL,
68
69  /** Start packets flowing.  Write-only, takes a dummy argument. */
70  NETIO_IPP_INPUT_INIT_OFF       = 0x6200000000000000ULL,
71
72  /** Stop packets flowing.  Write-only, takes a dummy argument. */
73  NETIO_IPP_INPUT_UNINIT_OFF     = 0x6300000000000000ULL,
74
75  /** Configure group (typically we group on VLAN).  Write-only: takes an
76   *  array of netio_group_t's, low 24 bits of the offset is the base group
77   *  number times the size of a netio_group_t. */
78  NETIO_IPP_INPUT_GROUP_CFG_OFF  = 0x6400000000000000ULL,
79
80  /** Configure bucket.  Write-only: takes an array of netio_bucket_t's, low
81   *  24 bits of the offset is the base bucket number times the size of a
82   *  netio_bucket_t. */
83  NETIO_IPP_INPUT_BUCKET_CFG_OFF = 0x6500000000000000ULL,
84
85  /** Get/set a parameter.  Read or write: read or write data is the parameter
86   *  value, low 32 bits of the offset is a __netio_getset_offset_t. */
87  NETIO_IPP_PARAM_OFF            = 0x6600000000000000ULL,
88
89  /** Get fast I/O index.  Read-only; returns a 4-byte base index value. */
90  NETIO_IPP_GET_FASTIO_OFF       = 0x6700000000000000ULL,
91
92  /** Configure hijack IP address.  Packets with this IPv4 dest address
93   *  go to bucket NETIO_NUM_BUCKETS - 1.  Write-only: takes an IP address
94   *  in some standard form.  FIXME: Define the form! */
95  NETIO_IPP_INPUT_HIJACK_CFG_OFF  = 0x6800000000000000ULL,
96
97  /**
98   * Offsets beyond this point are reserved for the supervisor (although that
99   * enforcement must be done by the supervisor driver itself).
100   */
101  NETIO_IPP_USER_MAX_OFF         = 0x6FFFFFFFFFFFFFFFULL,
102
103  /** Register I/O memory.  Write-only, takes a netio_ipp_address_t. */
104  NETIO_IPP_IOMEM_REGISTER_OFF   = 0x7000000000000000ULL,
105
106  /** Unregister I/O memory.  Write-only, takes a netio_ipp_address_t. */
107  NETIO_IPP_IOMEM_UNREGISTER_OFF = 0x7100000000000000ULL,
108
109  /* Offsets greater than 0x7FFFFFFF can't be used directly from Linux
110   * userspace code due to limitations in the pread/pwrite syscalls. */
111
112  /** Drain LIPP buffers. */
113  NETIO_IPP_DRAIN_OFF              = 0xFA00000000000000ULL,
114
115  /** Supply a netio_ipp_address_t to be used as shared memory for the
116   *  LEPP command queue. */
117  NETIO_EPP_SHM_OFF              = 0xFB00000000000000ULL,
118
119  /* 0xFC... is currently unused. */
120
121  /** Stop IPP/EPP tiles.  Write-only, takes a dummy argument.  */
122  NETIO_IPP_STOP_SHIM_OFF        = 0xFD00000000000000ULL,
123
124  /** Start IPP/EPP tiles.  Write-only, takes a dummy argument.  */
125  NETIO_IPP_START_SHIM_OFF       = 0xFE00000000000000ULL,
126
127  /** Supply packet arena.  Write-only, takes an array of
128    * netio_ipp_address_t values. */
129  NETIO_IPP_ADDRESS_OFF          = 0xFF00000000000000ULL,
130} netio_hv_offset_t;
131
132/** Extract the base offset from an offset */
133#define NETIO_BASE_OFFSET(off)    ((off) & 0xFF00000000000000ULL)
134/** Extract the local offset from an offset */
135#define NETIO_LOCAL_OFFSET(off)   ((off) & 0x00FFFFFFFFFFFFFFULL)
136
137
138/**
139 * Get/set offset.
140 */
141typedef union
142{
143  struct
144  {
145    uint64_t addr:48;        /**< Class-specific address */
146    unsigned int class:8;    /**< Class (e.g., NETIO_PARAM) */
147    unsigned int opcode:8;   /**< High 8 bits of NETIO_IPP_PARAM_OFF */
148  }
149  bits;                      /**< Bitfields */
150  uint64_t word;             /**< Aggregated value to use as the offset */
151}
152__netio_getset_offset_t;
153
154/**
155 * Fast I/O index offsets (must be contiguous).
156 */
157typedef enum
158{
159  NETIO_FASTIO_ALLOCATE         = 0, /**< Get empty packet buffer */
160  NETIO_FASTIO_FREE_BUFFER      = 1, /**< Give buffer back to IPP */
161  NETIO_FASTIO_RETURN_CREDITS   = 2, /**< Give credits to IPP */
162  NETIO_FASTIO_SEND_PKT_NOCK    = 3, /**< Send a packet, no checksum */
163  NETIO_FASTIO_SEND_PKT_CK      = 4, /**< Send a packet, with checksum */
164  NETIO_FASTIO_SEND_PKT_VEC     = 5, /**< Send a vector of packets */
165  NETIO_FASTIO_SENDV_PKT        = 6, /**< Sendv one packet */
166  NETIO_FASTIO_NUM_INDEX        = 7, /**< Total number of fast I/O indices */
167} netio_fastio_index_t;
168
169/** 3-word return type for Fast I/O call. */
170typedef struct
171{
172  int err;            /**< Error code. */
173  uint32_t val0;      /**< Value.  Meaning depends upon the specific call. */
174  uint32_t val1;      /**< Value.  Meaning depends upon the specific call. */
175} netio_fastio_rv3_t;
176
177/** 0-argument fast I/O call */
178int __netio_fastio0(uint32_t fastio_index);
179/** 1-argument fast I/O call */
180int __netio_fastio1(uint32_t fastio_index, uint32_t arg0);
181/** 3-argument fast I/O call, 2-word return value */
182netio_fastio_rv3_t __netio_fastio3_rv3(uint32_t fastio_index, uint32_t arg0,
183                                       uint32_t arg1, uint32_t arg2);
184/** 4-argument fast I/O call */
185int __netio_fastio4(uint32_t fastio_index, uint32_t arg0, uint32_t arg1,
186                    uint32_t arg2, uint32_t arg3);
187/** 6-argument fast I/O call */
188int __netio_fastio6(uint32_t fastio_index, uint32_t arg0, uint32_t arg1,
189                    uint32_t arg2, uint32_t arg3, uint32_t arg4, uint32_t arg5);
190/** 9-argument fast I/O call */
191int __netio_fastio9(uint32_t fastio_index, uint32_t arg0, uint32_t arg1,
192                    uint32_t arg2, uint32_t arg3, uint32_t arg4, uint32_t arg5,
193                    uint32_t arg6, uint32_t arg7, uint32_t arg8);
194
195/** Allocate an empty packet.
196 * @param fastio_index Fast I/O index.
197 * @param size Size of the packet to allocate.
198 */
199#define __netio_fastio_allocate(fastio_index, size) \
200  __netio_fastio1((fastio_index) + NETIO_FASTIO_ALLOCATE, size)
201
202/** Free a buffer.
203 * @param fastio_index Fast I/O index.
204 * @param handle Handle for the packet to free.
205 */
206#define __netio_fastio_free_buffer(fastio_index, handle) \
207  __netio_fastio1((fastio_index) + NETIO_FASTIO_FREE_BUFFER, handle)
208
209/** Increment our receive credits.
210 * @param fastio_index Fast I/O index.
211 * @param credits Number of credits to add.
212 */
213#define __netio_fastio_return_credits(fastio_index, credits) \
214  __netio_fastio1((fastio_index) + NETIO_FASTIO_RETURN_CREDITS, credits)
215
216/** Send packet, no checksum.
217 * @param fastio_index Fast I/O index.
218 * @param ackflag Nonzero if we want an ack.
219 * @param size Size of the packet.
220 * @param va Virtual address of start of packet.
221 * @param handle Packet handle.
222 */
223#define __netio_fastio_send_pkt_nock(fastio_index, ackflag, size, va, handle) \
224  __netio_fastio4((fastio_index) + NETIO_FASTIO_SEND_PKT_NOCK, ackflag, \
225                  size, va, handle)
226
227/** Send packet, calculate checksum.
228 * @param fastio_index Fast I/O index.
229 * @param ackflag Nonzero if we want an ack.
230 * @param size Size of the packet.
231 * @param va Virtual address of start of packet.
232 * @param handle Packet handle.
233 * @param csum0 Shim checksum header.
234 * @param csum1 Checksum seed.
235 */
236#define __netio_fastio_send_pkt_ck(fastio_index, ackflag, size, va, handle, \
237                                   csum0, csum1) \
238  __netio_fastio6((fastio_index) + NETIO_FASTIO_SEND_PKT_CK, ackflag, \
239                  size, va, handle, csum0, csum1)
240
241
242/** Format for the "csum0" argument to the __netio_fastio_send routines
243 * and LEPP.  Note that this is currently exactly identical to the
244 * ShimProtocolOffloadHeader.
245 */
246typedef union
247{
248  struct
249  {
250    unsigned int start_byte:7;       /**< The first byte to be checksummed */
251    unsigned int count:14;           /**< Number of bytes to be checksummed. */
252    unsigned int destination_byte:7; /**< The byte to write the checksum to. */
253    unsigned int reserved:4;         /**< Reserved. */
254  } bits;                            /**< Decomposed method of access. */
255  unsigned int word;                 /**< To send out the IDN. */
256} __netio_checksum_header_t;
257
258
259/** Sendv packet with 1 or 2 segments.
260 * @param fastio_index Fast I/O index.
261 * @param flags Ack/csum/notify flags in low 3 bits; number of segments minus
262 *        1 in next 2 bits; expected checksum in high 16 bits.
263 * @param confno Confirmation number to request, if notify flag set.
264 * @param csum0 Checksum descriptor; if zero, no checksum.
265 * @param va_F Virtual address of first segment.
266 * @param va_L Virtual address of last segment, if 2 segments.
267 * @param len_F_L Length of first segment in low 16 bits; length of last
268 *        segment, if 2 segments, in high 16 bits.
269 */
270#define __netio_fastio_sendv_pkt_1_2(fastio_index, flags, confno, csum0, \
271                                     va_F, va_L, len_F_L) \
272  __netio_fastio6((fastio_index) + NETIO_FASTIO_SENDV_PKT, flags, confno, \
273                  csum0, va_F, va_L, len_F_L)
274
275/** Send packet on PCIe interface.
276 * @param fastio_index Fast I/O index.
277 * @param flags Ack/csum/notify flags in low 3 bits.
278 * @param confno Confirmation number to request, if notify flag set.
279 * @param csum0 Checksum descriptor; Hard wired 0, not needed for PCIe.
280 * @param va_F Virtual address of the packet buffer.
281 * @param va_L Virtual address of last segment, if 2 segments. Hard wired 0.
282 * @param len_F_L Length of the packet buffer in low 16 bits.
283 */
284#define __netio_fastio_send_pcie_pkt(fastio_index, flags, confno, csum0, \
285                                     va_F, va_L, len_F_L) \
286  __netio_fastio6((fastio_index) + PCIE_FASTIO_SENDV_PKT, flags, confno, \
287                  csum0, va_F, va_L, len_F_L)
288
289/** Sendv packet with 3 or 4 segments.
290 * @param fastio_index Fast I/O index.
291 * @param flags Ack/csum/notify flags in low 3 bits; number of segments minus
292 *        1 in next 2 bits; expected checksum in high 16 bits.
293 * @param confno Confirmation number to request, if notify flag set.
294 * @param csum0 Checksum descriptor; if zero, no checksum.
295 * @param va_F Virtual address of first segment.
296 * @param va_L Virtual address of last segment (third segment if 3 segments,
297 *        fourth segment if 4 segments).
298 * @param len_F_L Length of first segment in low 16 bits; length of last
299 *        segment in high 16 bits.
300 * @param va_M0 Virtual address of "middle 0" segment; this segment is sent
301 *        second when there are three segments, and third if there are four.
302 * @param va_M1 Virtual address of "middle 1" segment; this segment is sent
303 *        second when there are four segments.
304 * @param len_M0_M1 Length of middle 0 segment in low 16 bits; length of middle
305 *        1 segment, if 4 segments, in high 16 bits.
306 */
307#define __netio_fastio_sendv_pkt_3_4(fastio_index, flags, confno, csum0, va_F, \
308                                     va_L, len_F_L, va_M0, va_M1, len_M0_M1) \
309  __netio_fastio9((fastio_index) + NETIO_FASTIO_SENDV_PKT, flags, confno, \
310                  csum0, va_F, va_L, len_F_L, va_M0, va_M1, len_M0_M1)
311
312/** Send vector of packets.
313 * @param fastio_index Fast I/O index.
314 * @param seqno Number of packets transmitted so far on this interface;
315 *        used to decide which packets should be acknowledged.
316 * @param nentries Number of entries in vector.
317 * @param va Virtual address of start of vector entry array.
318 * @return 3-word netio_fastio_rv3_t structure.  The structure's err member
319 *         is an error code, or zero if no error.  The val0 member is the
320 *         updated value of seqno; it has been incremented by 1 for each
321 *         packet sent.  That increment may be less than nentries if an
322 *         error occurred, or if some of the entries in the vector contain
323 *         handles equal to NETIO_PKT_HANDLE_NONE.  The val1 member is the
324 *         updated value of nentries; it has been decremented by 1 for each
325 *         vector entry processed.  Again, that decrement may be less than
326 *         nentries (leaving the returned value positive) if an error
327 *         occurred.
328 */
329#define __netio_fastio_send_pkt_vec(fastio_index, seqno, nentries, va) \
330  __netio_fastio3_rv3((fastio_index) + NETIO_FASTIO_SEND_PKT_VEC, seqno, \
331                      nentries, va)
332
333
334/** An egress DMA command for LEPP. */
335typedef struct
336{
337  /** Is this a TSO transfer?
338   *
339   * NOTE: This field is always 0, to distinguish it from
340   * lepp_tso_cmd_t.  It must come first!
341   */
342  uint8_t tso               : 1;
343
344  /** Unused padding bits. */
345  uint8_t _unused           : 3;
346
347  /** Should this packet be sent directly from caches instead of DRAM,
348   * using hash-for-home to locate the packet data?
349   */
350  uint8_t hash_for_home     : 1;
351
352  /** Should we compute a checksum? */
353  uint8_t compute_checksum  : 1;
354
355  /** Is this the final buffer for this packet?
356   *
357   * A single packet can be split over several input buffers (a "gather"
358   * operation).  This flag indicates that this is the last buffer
359   * in a packet.
360   */
361  uint8_t end_of_packet     : 1;
362
363  /** Should LEPP advance 'comp_busy' when this DMA is fully finished? */
364  uint8_t send_completion   : 1;
365
366  /** High bits of Client Physical Address of the start of the buffer
367   *  to be egressed.
368   *
369   *  NOTE: Only 6 bits are actually needed here, as CPAs are
370   *  currently 38 bits.  So two bits could be scavenged from this.
371   */
372  uint8_t cpa_hi;
373
374  /** The number of bytes to be egressed. */
375  uint16_t length;
376
377  /** Low 32 bits of Client Physical Address of the start of the buffer
378   *  to be egressed.
379   */
380  uint32_t cpa_lo;
381
382  /** Checksum information (only used if 'compute_checksum'). */
383  __netio_checksum_header_t checksum_data;
384
385} lepp_cmd_t;
386
387
388/** A chunk of physical memory for a TSO egress. */
389typedef struct
390{
391  /** The low bits of the CPA. */
392  uint32_t cpa_lo;
393  /** The high bits of the CPA. */
394  uint16_t cpa_hi		: 15;
395  /** Should this packet be sent directly from caches instead of DRAM,
396   *  using hash-for-home to locate the packet data?
397   */
398  uint16_t hash_for_home	: 1;
399  /** The length in bytes. */
400  uint16_t length;
401} lepp_frag_t;
402
403
404/** An LEPP command that handles TSO. */
405typedef struct
406{
407  /** Is this a TSO transfer?
408   *
409   *  NOTE: This field is always 1, to distinguish it from
410   *  lepp_cmd_t.  It must come first!
411   */
412  uint8_t tso             : 1;
413
414  /** Unused padding bits. */
415  uint8_t _unused         : 7;
416
417  /** Size of the header[] array in bytes.  It must be in the range
418   *  [40, 127], which are the smallest header for a TCP packet over
419   *  Ethernet and the maximum possible prepend size supported by
420   *  hardware, respectively.  Note that the array storage must be
421   *  padded out to a multiple of four bytes so that the following
422   *  LEPP command is aligned properly.
423   */
424  uint8_t header_size;
425
426  /** Byte offset of the IP header in header[]. */
427  uint8_t ip_offset;
428
429  /** Byte offset of the TCP header in header[]. */
430  uint8_t tcp_offset;
431
432  /** The number of bytes to use for the payload of each packet,
433   *  except of course the last one, which may not have enough bytes.
434   *  This means that each Ethernet packet except the last will have a
435   *  size of header_size + payload_size.
436   */
437  uint16_t payload_size;
438
439  /** The length of the 'frags' array that follows this struct. */
440  uint16_t num_frags;
441
442  /** The actual frags. */
443  lepp_frag_t frags[0 /* Variable-sized; num_frags entries. */];
444
445  /*
446   * The packet header template logically follows frags[],
447   * but you can't declare that in C.
448   *
449   * uint32_t header[header_size_in_words_rounded_up];
450   */
451
452} lepp_tso_cmd_t;
453
454
455/** An LEPP completion ring entry. */
456typedef void* lepp_comp_t;
457
458
459/** Maximum number of frags for one TSO command.  This is adapted from
460 *  linux's "MAX_SKB_FRAGS", and presumably over-estimates by one, for
461 *  our page size of exactly 65536.  We add one for a "body" fragment.
462 */
463#define LEPP_MAX_FRAGS (65536 / HV_DEFAULT_PAGE_SIZE_SMALL + 2 + 1)
464
465/** Total number of bytes needed for an lepp_tso_cmd_t. */
466#define LEPP_TSO_CMD_SIZE(num_frags, header_size) \
467  (sizeof(lepp_tso_cmd_t) + \
468   (num_frags) * sizeof(lepp_frag_t) + \
469   (((header_size) + 3) & -4))
470
471/** The size of the lepp "cmd" queue. */
472#define LEPP_CMD_QUEUE_BYTES \
473 (((CHIP_L2_CACHE_SIZE() - 2 * CHIP_L2_LINE_SIZE()) / \
474  (sizeof(lepp_cmd_t) + sizeof(lepp_comp_t))) * sizeof(lepp_cmd_t))
475
476/** The largest possible command that can go in lepp_queue_t::cmds[]. */
477#define LEPP_MAX_CMD_SIZE LEPP_TSO_CMD_SIZE(LEPP_MAX_FRAGS, 128)
478
479/** The largest possible value of lepp_queue_t::cmd_{head, tail} (inclusive).
480 */
481#define LEPP_CMD_LIMIT \
482  (LEPP_CMD_QUEUE_BYTES - LEPP_MAX_CMD_SIZE)
483
484/** The maximum number of completions in an LEPP queue. */
485#define LEPP_COMP_QUEUE_SIZE \
486  ((LEPP_CMD_LIMIT + sizeof(lepp_cmd_t) - 1) / sizeof(lepp_cmd_t))
487
488/** Increment an index modulo the queue size. */
489#define LEPP_QINC(var) \
490  (var = __insn_mnz(var - (LEPP_COMP_QUEUE_SIZE - 1), var + 1))
491
492/** A queue used to convey egress commands from the client to LEPP. */
493typedef struct
494{
495  /** Index of first completion not yet processed by user code.
496   *  If this is equal to comp_busy, there are no such completions.
497   *
498   *  NOTE: This is only read/written by the user.
499   */
500  unsigned int comp_head;
501
502  /** Index of first completion record not yet completed.
503   *  If this is equal to comp_tail, there are no such completions.
504   *  This index gets advanced (modulo LEPP_QUEUE_SIZE) whenever
505   *  a command with the 'completion' bit set is finished.
506   *
507   *  NOTE: This is only written by LEPP, only read by the user.
508   */
509  volatile unsigned int comp_busy;
510
511  /** Index of the first empty slot in the completion ring.
512   *  Entries from this up to but not including comp_head (in ring order)
513   *  can be filled in with completion data.
514   *
515   *  NOTE: This is only read/written by the user.
516   */
517  unsigned int comp_tail;
518
519  /** Byte index of first command enqueued for LEPP but not yet processed.
520   *
521   *  This is always divisible by sizeof(void*) and always <= LEPP_CMD_LIMIT.
522   *
523   *  NOTE: LEPP advances this counter as soon as it no longer needs
524   *  the cmds[] storage for this entry, but the transfer is not actually
525   *  complete (i.e. the buffer pointed to by the command is no longer
526   *  needed) until comp_busy advances.
527   *
528   *  If this is equal to cmd_tail, the ring is empty.
529   *
530   *  NOTE: This is only written by LEPP, only read by the user.
531   */
532  volatile unsigned int cmd_head;
533
534  /** Byte index of first empty slot in the command ring.  This field can
535   *  be incremented up to but not equal to cmd_head (because that would
536   *  mean the ring is empty).
537   *
538   *  This is always divisible by sizeof(void*) and always <= LEPP_CMD_LIMIT.
539   *
540   *  NOTE: This is read/written by the user, only read by LEPP.
541   */
542  volatile unsigned int cmd_tail;
543
544  /** A ring of variable-sized egress DMA commands.
545   *
546   *  NOTE: Only written by the user, only read by LEPP.
547   */
548  char cmds[LEPP_CMD_QUEUE_BYTES]
549    __attribute__((aligned(CHIP_L2_LINE_SIZE())));
550
551  /** A ring of user completion data.
552   *  NOTE: Only read/written by the user.
553   */
554  lepp_comp_t comps[LEPP_COMP_QUEUE_SIZE]
555    __attribute__((aligned(CHIP_L2_LINE_SIZE())));
556} lepp_queue_t;
557
558
559/** An internal helper function for determining the number of entries
560 *  available in a ring buffer, given that there is one sentinel.
561 */
562static inline unsigned int
563_lepp_num_free_slots(unsigned int head, unsigned int tail)
564{
565  /*
566   * One entry is reserved for use as a sentinel, to distinguish
567   * "empty" from "full".  So we compute
568   * (head - tail - 1) % LEPP_QUEUE_SIZE, but without using a slow % operation.
569   */
570  return (head - tail - 1) + ((head <= tail) ? LEPP_COMP_QUEUE_SIZE : 0);
571}
572
573
574/** Returns how many new comp entries can be enqueued. */
575static inline unsigned int
576lepp_num_free_comp_slots(const lepp_queue_t* q)
577{
578  return _lepp_num_free_slots(q->comp_head, q->comp_tail);
579}
580
581static inline int
582lepp_qsub(int v1, int v2)
583{
584  int delta = v1 - v2;
585  return delta + ((delta >> 31) & LEPP_COMP_QUEUE_SIZE);
586}
587
588
589/** FIXME: Check this from linux, via a new "pwrite()" call. */
590#define LIPP_VERSION 1
591
592
593/** We use exactly two bytes of alignment padding. */
594#define LIPP_PACKET_PADDING 2
595
596/** The minimum size of a "small" buffer (including the padding). */
597#define LIPP_SMALL_PACKET_SIZE 128
598
599/*
600 * NOTE: The following two values should total to less than around
601 * 13582, to keep the total size used for "lipp_state_t" below 64K.
602 */
603
604/** The maximum number of "small" buffers.
605 *  This is enough for 53 network cpus with 128 credits.  Note that
606 *  if these are exhausted, we will fall back to using large buffers.
607 */
608#define LIPP_SMALL_BUFFERS 6785
609
610/** The maximum number of "large" buffers.
611 *  This is enough for 53 network cpus with 128 credits.
612 */
613#define LIPP_LARGE_BUFFERS 6785
614
615#endif /* __DRV_XGBE_INTF_H__ */
616