1// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
2/*
3 * Copyright (c) 2011, 2012, Atheros Communications Inc.
4 * Copyright (c) 2014, I2SE GmbH
5 */
6
7/* Atheros ethernet framing. Every Ethernet frame is surrounded
8 * by an atheros frame while transmitted over a serial channel;
9 */
10
11#include <linux/init.h>
12#include <linux/kernel.h>
13#include <linux/module.h>
14
15#include "qca_7k_common.h"
16
17u16
18qcafrm_create_header(u8 *buf, u16 length)
19{
20 __le16 len;
21
22 if (!buf)
23 return 0;
24
25 len = cpu_to_le16(length);
26
27 buf[0] = 0xAA;
28 buf[1] = 0xAA;
29 buf[2] = 0xAA;
30 buf[3] = 0xAA;
31 buf[4] = len & 0xff;
32 buf[5] = (len >> 8) & 0xff;
33 buf[6] = 0;
34 buf[7] = 0;
35
36 return QCAFRM_HEADER_LEN;
37}
38EXPORT_SYMBOL_GPL(qcafrm_create_header);
39
40u16
41qcafrm_create_footer(u8 *buf)
42{
43 if (!buf)
44 return 0;
45
46 buf[0] = 0x55;
47 buf[1] = 0x55;
48 return QCAFRM_FOOTER_LEN;
49}
50EXPORT_SYMBOL_GPL(qcafrm_create_footer);
51
52/* Gather received bytes and try to extract a full ethernet frame by
53 * following a simple state machine.
54 *
55 * Return: QCAFRM_GATHER No ethernet frame fully received yet.
56 * QCAFRM_NOHEAD Header expected but not found.
57 * QCAFRM_INVLEN Atheros frame length is invalid
58 * QCAFRM_NOTAIL Footer expected but not found.
59 * > 0 Number of byte in the fully received
60 * Ethernet frame
61 */
62
63s32
64qcafrm_fsm_decode(struct qcafrm_handle *handle, u8 *buf, u16 buf_len, u8 recv_byte)
65{
66 s32 ret = QCAFRM_GATHER;
67 u16 len;
68
69 switch (handle->state) {
70 case QCAFRM_HW_LEN0:
71 case QCAFRM_HW_LEN1:
72 /* by default, just go to next state */
73 handle->state--;
74
75 if (recv_byte != 0x00) {
76 /* first two bytes of length must be 0 */
77 handle->state = handle->init;
78 }
79 break;
80 case QCAFRM_HW_LEN2:
81 case QCAFRM_HW_LEN3:
82 handle->state--;
83 break;
84 /* 4 bytes header pattern */
85 case QCAFRM_WAIT_AA1:
86 case QCAFRM_WAIT_AA2:
87 case QCAFRM_WAIT_AA3:
88 case QCAFRM_WAIT_AA4:
89 if (recv_byte != 0xAA) {
90 ret = QCAFRM_NOHEAD;
91 handle->state = handle->init;
92 } else {
93 handle->state--;
94 }
95 break;
96 /* 2 bytes length. */
97 /* Borrow offset field to hold length for now. */
98 case QCAFRM_WAIT_LEN_BYTE0:
99 handle->offset = recv_byte;
100 handle->state = QCAFRM_WAIT_LEN_BYTE1;
101 break;
102 case QCAFRM_WAIT_LEN_BYTE1:
103 handle->offset = handle->offset | (recv_byte << 8);
104 handle->state = QCAFRM_WAIT_RSVD_BYTE1;
105 break;
106 case QCAFRM_WAIT_RSVD_BYTE1:
107 handle->state = QCAFRM_WAIT_RSVD_BYTE2;
108 break;
109 case QCAFRM_WAIT_RSVD_BYTE2:
110 len = handle->offset;
111 if (len > buf_len || len < QCAFRM_MIN_LEN) {
112 ret = QCAFRM_INVLEN;
113 handle->state = handle->init;
114 } else {
115 handle->state = (enum qcafrm_state)(len + 1);
116 /* Remaining number of bytes. */
117 handle->offset = 0;
118 }
119 break;
120 default:
121 /* Receiving Ethernet frame itself. */
122 buf[handle->offset] = recv_byte;
123 handle->offset++;
124 handle->state--;
125 break;
126 case QCAFRM_WAIT_551:
127 if (recv_byte != 0x55) {
128 ret = QCAFRM_NOTAIL;
129 handle->state = handle->init;
130 } else {
131 handle->state = QCAFRM_WAIT_552;
132 }
133 break;
134 case QCAFRM_WAIT_552:
135 if (recv_byte != 0x55) {
136 ret = QCAFRM_NOTAIL;
137 handle->state = handle->init;
138 } else {
139 ret = handle->offset;
140 /* Frame is fully received. */
141 handle->state = handle->init;
142 }
143 break;
144 }
145
146 return ret;
147}
148EXPORT_SYMBOL_GPL(qcafrm_fsm_decode);
149
150MODULE_DESCRIPTION("Qualcomm Atheros QCA7000 common");
151MODULE_AUTHOR("Qualcomm Atheros Communications");
152MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net>");
153MODULE_LICENSE("Dual BSD/GPL");
154

source code of linux/drivers/net/ethernet/qualcomm/qca_7k_common.c