Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * linux/can/gw.h
3 *
4 * Definitions for CAN frame Gateway/Router/Bridge
5 *
6 * Author: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
7 * Copyright (c) 2011 Volkswagen Group Electronic Research
8 * All rights reserved.
9 *
10 */
11
12#ifndef CAN_GW_H
13#define CAN_GW_H
14
15#include <linux/types.h>
16#include <linux/can.h>
17
18struct rtcanmsg {
19 __u8 can_family;
20 __u8 gwtype;
21 __u16 flags;
22};
23
24/* CAN gateway types */
25enum {
26 CGW_TYPE_UNSPEC,
27 CGW_TYPE_CAN_CAN, /* CAN->CAN routing */
28 __CGW_TYPE_MAX
29};
30
31#define CGW_TYPE_MAX (__CGW_TYPE_MAX - 1)
32
33/* CAN rtnetlink attribute definitions */
34enum {
35 CGW_UNSPEC,
36 CGW_MOD_AND, /* CAN frame modification binary AND */
37 CGW_MOD_OR, /* CAN frame modification binary OR */
38 CGW_MOD_XOR, /* CAN frame modification binary XOR */
39 CGW_MOD_SET, /* CAN frame modification set alternate values */
40 CGW_CS_XOR, /* set data[] XOR checksum into data[index] */
41 CGW_CS_CRC8, /* set data[] CRC8 checksum into data[index] */
42 CGW_HANDLED, /* number of handled CAN frames */
43 CGW_DROPPED, /* number of dropped CAN frames */
44 CGW_SRC_IF, /* ifindex of source network interface */
45 CGW_DST_IF, /* ifindex of destination network interface */
46 CGW_FILTER, /* specify struct can_filter on source CAN device */
47 CGW_DELETED, /* number of deleted CAN frames (see max_hops param) */
48 CGW_LIM_HOPS, /* limit the number of hops of this specific rule */
49 __CGW_MAX
50};
51
52#define CGW_MAX (__CGW_MAX - 1)
53
54#define CGW_FLAGS_CAN_ECHO 0x01
55#define CGW_FLAGS_CAN_SRC_TSTAMP 0x02
56#define CGW_FLAGS_CAN_IIF_TX_OK 0x04
57
58#define CGW_MOD_FUNCS 4 /* AND OR XOR SET */
59
60/* CAN frame elements that are affected by curr. 3 CAN frame modifications */
61#define CGW_MOD_ID 0x01
62#define CGW_MOD_DLC 0x02
63#define CGW_MOD_DATA 0x04
64
65#define CGW_FRAME_MODS 3 /* ID DLC DATA */
66
67#define MAX_MODFUNCTIONS (CGW_MOD_FUNCS * CGW_FRAME_MODS)
68
69struct cgw_frame_mod {
70 struct can_frame cf;
71 __u8 modtype;
72} __attribute__((packed));
73
74#define CGW_MODATTR_LEN sizeof(struct cgw_frame_mod)
75
76struct cgw_csum_xor {
77 __s8 from_idx;
78 __s8 to_idx;
79 __s8 result_idx;
80 __u8 init_xor_val;
81} __attribute__((packed));
82
83struct cgw_csum_crc8 {
84 __s8 from_idx;
85 __s8 to_idx;
86 __s8 result_idx;
87 __u8 init_crc_val;
88 __u8 final_xor_val;
89 __u8 crctab[256];
90 __u8 profile;
91 __u8 profile_data[20];
92} __attribute__((packed));
93
94/* length of checksum operation parameters. idx = index in CAN frame data[] */
95#define CGW_CS_XOR_LEN sizeof(struct cgw_csum_xor)
96#define CGW_CS_CRC8_LEN sizeof(struct cgw_csum_crc8)
97
98/* CRC8 profiles (compute CRC for additional data elements - see below) */
99enum {
100 CGW_CRC8PRF_UNSPEC,
101 CGW_CRC8PRF_1U8, /* compute one additional u8 value */
102 CGW_CRC8PRF_16U8, /* u8 value table indexed by data[1] & 0xF */
103 CGW_CRC8PRF_SFFID_XOR, /* (can_id & 0xFF) ^ (can_id >> 8 & 0xFF) */
104 __CGW_CRC8PRF_MAX
105};
106
107#define CGW_CRC8PRF_MAX (__CGW_CRC8PRF_MAX - 1)
108
109/*
110 * CAN rtnetlink attribute contents in detail
111 *
112 * CGW_XXX_IF (length 4 bytes):
113 * Sets an interface index for source/destination network interfaces.
114 * For the CAN->CAN gwtype the indices of _two_ CAN interfaces are mandatory.
115 *
116 * CGW_FILTER (length 8 bytes):
117 * Sets a CAN receive filter for the gateway job specified by the
118 * struct can_filter described in include/linux/can.h
119 *
120 * CGW_MOD_(AND|OR|XOR|SET) (length 17 bytes):
121 * Specifies a modification that's done to a received CAN frame before it is
122 * send out to the destination interface.
123 *
124 * <struct can_frame> data used as operator
125 * <u8> affected CAN frame elements
126 *
127 * CGW_LIM_HOPS (length 1 byte):
128 * Limit the number of hops of this specific rule. Usually the received CAN
129 * frame can be processed as much as 'max_hops' times (which is given at module
130 * load time of the can-gw module). This value is used to reduce the number of
131 * possible hops for this gateway rule to a value smaller then max_hops.
132 *
133 * CGW_CS_XOR (length 4 bytes):
134 * Set a simple XOR checksum starting with an initial value into
135 * data[result-idx] using data[start-idx] .. data[end-idx]
136 *
137 * The XOR checksum is calculated like this:
138 *
139 * xor = init_xor_val
140 *
141 * for (i = from_idx .. to_idx)
142 * xor ^= can_frame.data[i]
143 *
144 * can_frame.data[ result_idx ] = xor
145 *
146 * CGW_CS_CRC8 (length 282 bytes):
147 * Set a CRC8 value into data[result-idx] using a given 256 byte CRC8 table,
148 * a given initial value and a defined input data[start-idx] .. data[end-idx].
149 * Finally the result value is XOR'ed with the final_xor_val.
150 *
151 * The CRC8 checksum is calculated like this:
152 *
153 * crc = init_crc_val
154 *
155 * for (i = from_idx .. to_idx)
156 * crc = crctab[ crc ^ can_frame.data[i] ]
157 *
158 * can_frame.data[ result_idx ] = crc ^ final_xor_val
159 *
160 * The calculated CRC may contain additional source data elements that can be
161 * defined in the handling of 'checksum profiles' e.g. shown in AUTOSAR specs
162 * like http://www.autosar.org/download/R4.0/AUTOSAR_SWS_E2ELibrary.pdf
163 * E.g. the profile_data[] may contain additional u8 values (called DATA_IDs)
164 * that are used depending on counter values inside the CAN frame data[].
165 * So far only three profiles have been implemented for illustration.
166 *
167 * Remark: In general the attribute data is a linear buffer.
168 * Beware of sending unpacked or aligned structs!
169 */
170
171#endif