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
30u16
31qcafrm_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}
51EXPORT_SYMBOL_GPL(qcafrm_create_header);
52
53u16
54qcafrm_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}
63EXPORT_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
76s32
77qcafrm_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}
161EXPORT_SYMBOL_GPL(qcafrm_fsm_decode);
162
163MODULE_DESCRIPTION("Qualcomm Atheros QCA7000 common");
164MODULE_AUTHOR("Qualcomm Atheros Communications");
165MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
166MODULE_LICENSE("Dual BSD/GPL");
167