LXR linux/include/linux/can/gw.h

   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_MAX
  48};
  49
  50#define CGW_MAX (__CGW_MAX - 1)
  51
  52#define CGW_FLAGS_CAN_ECHO 0x01
  53#define CGW_FLAGS_CAN_SRC_TSTAMP 0x02
  54
  55#define CGW_MOD_FUNCS 4 /* AND OR XOR SET */
  56
  57/* CAN frame elements that are affected by curr. 3 CAN frame modifications */
  58#define CGW_MOD_ID      0x01
  59#define CGW_MOD_DLC     0x02
  60#define CGW_MOD_DATA    0x04
  61
  62#define CGW_FRAME_MODS 3 /* ID DLC DATA */
  63
  64#define MAX_MODFUNCTIONS (CGW_MOD_FUNCS * CGW_FRAME_MODS)
  65
  66struct cgw_frame_mod {
  67        struct can_frame cf;
  68        __u8 modtype;
  69} __attribute__((packed));
  70
  71#define CGW_MODATTR_LEN sizeof(struct cgw_frame_mod)
  72
  73struct cgw_csum_xor {
  74        __s8 from_idx;
  75        __s8 to_idx;
  76        __s8 result_idx;
  77        __u8 init_xor_val;
  78} __attribute__((packed));
  79
  80struct cgw_csum_crc8 {
  81        __s8 from_idx;
  82        __s8 to_idx;
  83        __s8 result_idx;
  84        __u8 init_crc_val;
  85        __u8 final_xor_val;
  86        __u8 crctab[256];
  87        __u8 profile;
  88        __u8 profile_data[20];
  89} __attribute__((packed));
  90
  91/* length of checksum operation parameters. idx = index in CAN frame data[] */
  92#define CGW_CS_XOR_LEN  sizeof(struct cgw_csum_xor)
  93#define CGW_CS_CRC8_LEN  sizeof(struct cgw_csum_crc8)
  94
  95/* CRC8 profiles (compute CRC for additional data elements - see below) */
  96enum {
  97        CGW_CRC8PRF_UNSPEC,
  98        CGW_CRC8PRF_1U8,        /* compute one additional u8 value */
  99        CGW_CRC8PRF_16U8,       /* u8 value table indexed by data[1] & 0xF */
 100        CGW_CRC8PRF_SFFID_XOR,  /* (can_id & 0xFF) ^ (can_id >> 8 & 0xFF) */
 101        __CGW_CRC8PRF_MAX
 102};
 103
 104#define CGW_CRC8PRF_MAX (__CGW_CRC8PRF_MAX - 1)
 105
 106/*
 107 * CAN rtnetlink attribute contents in detail
 108 *
 109 * CGW_XXX_IF (length 4 bytes):
 110 * Sets an interface index for source/destination network interfaces.
 111 * For the CAN->CAN gwtype the indices of _two_ CAN interfaces are mandatory.
 112 *
 113 * CGW_FILTER (length 8 bytes):
 114 * Sets a CAN receive filter for the gateway job specified by the
 115 * struct can_filter described in include/linux/can.h
 116 *
 117 * CGW_MOD_XXX (length 17 bytes):
 118 * Specifies a modification that's done to a received CAN frame before it is
 119 * send out to the destination interface.
 120 *
 121 * <struct can_frame> data used as operator
 122 * <u8> affected CAN frame elements
 123 *
 124 * CGW_CS_XOR (length 4 bytes):
 125 * Set a simple XOR checksum starting with an initial value into
 126 * data[result-idx] using data[start-idx] .. data[end-idx]
 127 *
 128 * The XOR checksum is calculated like this:
 129 *
 130 * xor = init_xor_val
 131 *
 132 * for (i = from_idx .. to_idx)
 133 *      xor ^= can_frame.data[i]
 134 *
 135 * can_frame.data[ result_idx ] = xor
 136 *
 137 * CGW_CS_CRC8 (length 282 bytes):
 138 * Set a CRC8 value into data[result-idx] using a given 256 byte CRC8 table,
 139 * a given initial value and a defined input data[start-idx] .. data[end-idx].
 140 * Finally the result value is XOR'ed with the final_xor_val.
 141 *
 142 * The CRC8 checksum is calculated like this:
 143 *
 144 * crc = init_crc_val
 145 *
 146 * for (i = from_idx .. to_idx)
 147 *      crc = crctab[ crc ^ can_frame.data[i] ]
 148 *
 149 * can_frame.data[ result_idx ] = crc ^ final_xor_val
 150 *
 151 * The calculated CRC may contain additional source data elements that can be
 152 * defined in the handling of 'checksum profiles' e.g. shown in AUTOSAR specs
 153 * like http://www.autosar.org/download/R4.0/AUTOSAR_SWS_E2ELibrary.pdf
 154 * E.g. the profile_data[] may contain additional u8 values (called DATA_IDs)
 155 * that are used depending on counter values inside the CAN frame data[].
 156 * So far only three profiles have been implemented for illustration.
 157 *
 158 * Remark: In general the attribute data is a linear buffer.
 159 *         Beware of sending unpacked or aligned structs!
 160 */
 161
 162#endif
 163