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
qcafrm_create_header(u8 * buf,u16 length)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
qcafrm_create_footer(u8 * buf)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
qcafrm_fsm_decode(struct qcafrm_handle * handle,u8 * buf,u16 buf_len,u8 recv_byte)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");
167