1 /*
2 * Copyright (c) 2011, 2012, Atheros Communications Inc.
3 * Copyright (c) 2014, I2SE GmbH
4 *
5 * Permission to use, copy, modify, and/or distribute this software
6 * for any purpose with or without fee is hereby granted, provided
7 * that the above copyright notice and this permission notice appear
8 * in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
11 * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
12 * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
13 * THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
14 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
15 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
16 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
17 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 /* Atheros ethernet framing. Every Ethernet frame is surrounded
21 * by an atheros frame while transmitted over a serial channel;
22 */
23
24 #include <linux/init.h>
25 #include <linux/kernel.h>
26 #include <linux/module.h>
27
28 #include "qca_7k_common.h"
29
30 u16
31 qcafrm_create_header(u8 *buf, u16 length)
32 {
33 __le16 len;
34
35 if (!buf)
36 return 0;
37
38 len = cpu_to_le16(length);
39
40 buf[0] = 0xAA;
41 buf[1] = 0xAA;
42 buf[2] = 0xAA;
43 buf[3] = 0xAA;
44 buf[4] = len & 0xff;
45 buf[5] = (len >> 8) & 0xff;
46 buf[6] = 0;
47 buf[7] = 0;
48
49 return QCAFRM_HEADER_LEN;
50 }
51 EXPORT_SYMBOL_GPL(qcafrm_create_header);
52
53 u16
54 qcafrm_create_footer(u8 *buf)
55 {
56 if (!buf)
57 return 0;
58
59 buf[0] = 0x55;
60 buf[1] = 0x55;
61 return QCAFRM_FOOTER_LEN;
62 }
63 EXPORT_SYMBOL_GPL(qcafrm_create_footer);
64
65 /* Gather received bytes and try to extract a full ethernet frame by
66 * following a simple state machine.
67 *
68 * Return: QCAFRM_GATHER No ethernet frame fully received yet.
69 * QCAFRM_NOHEAD Header expected but not found.
70 * QCAFRM_INVLEN Atheros frame length is invalid
71 * QCAFRM_NOTAIL Footer expected but not found.
72 * > 0 Number of byte in the fully received
73 * Ethernet frame
74 */
75
76 s32
77 qcafrm_fsm_decode(struct qcafrm_handle *handle, u8 *buf, u16 buf_len, u8 recv_byte)
78 {
79 s32 ret = QCAFRM_GATHER;
80 u16 len;
81
82 switch (handle->state) {
83 case QCAFRM_HW_LEN0:
84 case QCAFRM_HW_LEN1:
85 /* by default, just go to next state */
86 handle->state--;
87
88 if (recv_byte != 0x00) {
89 /* first two bytes of length must be 0 */
90 handle->state = handle->init;
91 }
92 break;
93 case QCAFRM_HW_LEN2:
94 case QCAFRM_HW_LEN3:
95 handle->state--;
96 break;
97 /* 4 bytes header pattern */
98 case QCAFRM_WAIT_AA1:
99 case QCAFRM_WAIT_AA2:
100 case QCAFRM_WAIT_AA3:
101 case QCAFRM_WAIT_AA4:
102 if (recv_byte != 0xAA) {
103 ret = QCAFRM_NOHEAD;
104 handle->state = handle->init;
105 } else {
106 handle->state--;
107 }
108 break;
109 /* 2 bytes length. */
110 /* Borrow offset field to hold length for now. */
111 case QCAFRM_WAIT_LEN_BYTE0:
112 handle->offset = recv_byte;
113 handle->state = QCAFRM_WAIT_LEN_BYTE1;
114 break;
115 case QCAFRM_WAIT_LEN_BYTE1:
116 handle->offset = handle->offset | (recv_byte << 8);
117 handle->state = QCAFRM_WAIT_RSVD_BYTE1;
118 break;
119 case QCAFRM_WAIT_RSVD_BYTE1:
120 handle->state = QCAFRM_WAIT_RSVD_BYTE2;
121 break;
122 case QCAFRM_WAIT_RSVD_BYTE2:
123 len = handle->offset;
124 if (len > buf_len || len < QCAFRM_MIN_LEN) {
125 ret = QCAFRM_INVLEN;
126 handle->state = handle->init;
127 } else {
128 handle->state = (enum qcafrm_state)(len + 1);
129 /* Remaining number of bytes. */
130 handle->offset = 0;
131 }
132 break;
133 default:
134 /* Receiving Ethernet frame itself. */
135 buf[handle->offset] = recv_byte;
136 handle->offset++;
137 handle->state--;
138 break;
139 case QCAFRM_WAIT_551:
140 if (recv_byte != 0x55) {
141 ret = QCAFRM_NOTAIL;
142 handle->state = handle->init;
143 } else {
144 handle->state = QCAFRM_WAIT_552;
145 }
146 break;
147 case QCAFRM_WAIT_552:
148 if (recv_byte != 0x55) {
149 ret = QCAFRM_NOTAIL;
150 handle->state = handle->init;
151 } else {
152 ret = handle->offset;
153 /* Frame is fully received. */
154 handle->state = handle->init;
155 }
156 break;
157 }
158
159 return ret;
160 }
161 EXPORT_SYMBOL_GPL(qcafrm_fsm_decode);
162
163 MODULE_DESCRIPTION("Qualcomm Atheros QCA7000 common");
164 MODULE_AUTHOR("Qualcomm Atheros Communications");
165 MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
166 MODULE_LICENSE("Dual BSD/GPL");