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 by an atheros
21 *   frame while transmitted over a serial channel.
22 */
23
24#ifndef _QCA_FRAMING_H
25#define _QCA_FRAMING_H
26
27#include <linux/if_ether.h>
28#include <linux/if_vlan.h>
29#include <linux/types.h>
30
31/* Frame is currently being received */
32#define QCAFRM_GATHER 0
33
34/*  No header byte while expecting it */
35#define QCAFRM_NOHEAD (QCAFRM_ERR_BASE - 1)
36
37/* No tailer byte while expecting it */
38#define QCAFRM_NOTAIL (QCAFRM_ERR_BASE - 2)
39
40/* Frame length is invalid */
41#define QCAFRM_INVLEN (QCAFRM_ERR_BASE - 3)
42
43/* Frame length is invalid */
44#define QCAFRM_INVFRAME (QCAFRM_ERR_BASE - 4)
45
46/* Min/Max Ethernet MTU */
47#define QCAFRM_ETHMINMTU 46
48#define QCAFRM_ETHMAXMTU 1500
49
50/* Min/Max frame lengths */
51#define QCAFRM_ETHMINLEN (QCAFRM_ETHMINMTU + ETH_HLEN)
52#define QCAFRM_ETHMAXLEN (QCAFRM_ETHMAXMTU + VLAN_ETH_HLEN)
53
54/* QCA7K header len */
55#define QCAFRM_HEADER_LEN 8
56
57/* QCA7K footer len */
58#define QCAFRM_FOOTER_LEN 2
59
60/* QCA7K Framing. */
61#define QCAFRM_ERR_BASE -1000
62
63enum qcafrm_state {
64	QCAFRM_HW_LEN0 = 0x8000,
65	QCAFRM_HW_LEN1 = QCAFRM_HW_LEN0 - 1,
66	QCAFRM_HW_LEN2 = QCAFRM_HW_LEN1 - 1,
67	QCAFRM_HW_LEN3 = QCAFRM_HW_LEN2 - 1,
68
69	/*  Waiting first 0xAA of header */
70	QCAFRM_WAIT_AA1 = QCAFRM_HW_LEN3 - 1,
71
72	/*  Waiting second 0xAA of header */
73	QCAFRM_WAIT_AA2 = QCAFRM_WAIT_AA1 - 1,
74
75	/*  Waiting third 0xAA of header */
76	QCAFRM_WAIT_AA3 = QCAFRM_WAIT_AA2 - 1,
77
78	/*  Waiting fourth 0xAA of header */
79	QCAFRM_WAIT_AA4 = QCAFRM_WAIT_AA3 - 1,
80
81	/*  Waiting Byte 0-1 of length (litte endian) */
82	QCAFRM_WAIT_LEN_BYTE0 = QCAFRM_WAIT_AA4 - 1,
83	QCAFRM_WAIT_LEN_BYTE1 = QCAFRM_WAIT_AA4 - 2,
84
85	/* Reserved bytes */
86	QCAFRM_WAIT_RSVD_BYTE1 = QCAFRM_WAIT_AA4 - 3,
87	QCAFRM_WAIT_RSVD_BYTE2 = QCAFRM_WAIT_AA4 - 4,
88
89	/*  The frame length is used as the state until
90	 *  the end of the Ethernet frame
91	 *  Waiting for first 0x55 of footer
92	 */
93	QCAFRM_WAIT_551 = 1,
94
95	/*  Waiting for second 0x55 of footer */
96	QCAFRM_WAIT_552 = QCAFRM_WAIT_551 - 1
97};
98
99/*   Structure to maintain the frame decoding during reception. */
100
101struct qcafrm_handle {
102	/*  Current decoding state */
103	enum qcafrm_state state;
104
105	/* Offset in buffer (borrowed for length too) */
106	s16 offset;
107
108	/* Frame length as kept by this module */
109	u16 len;
110};
111
112u16 qcafrm_create_header(u8 *buf, u16 len);
113
114u16 qcafrm_create_footer(u8 *buf);
115
116static inline void qcafrm_fsm_init(struct qcafrm_handle *handle)
117{
118	handle->state = QCAFRM_HW_LEN0;
119}
120
121/*   Gather received bytes and try to extract a full Ethernet frame
122 *   by following a simple state machine.
123 *
124 * Return:   QCAFRM_GATHER       No Ethernet frame fully received yet.
125 *           QCAFRM_NOHEAD       Header expected but not found.
126 *           QCAFRM_INVLEN       QCA7K frame length is invalid
127 *           QCAFRM_NOTAIL       Footer expected but not found.
128 *           > 0                 Number of byte in the fully received
129 *                               Ethernet frame
130 */
131
132s32 qcafrm_fsm_decode(struct qcafrm_handle *handle, u8 *buf, u16 buf_len, u8 recv_byte);
133
134#endif /* _QCA_FRAMING_H */
135