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
  18 struct rtcanmsg {
  19         __u8  can_family;
  20         __u8  gwtype;
  21         __u16 flags;
  22 };
  23
  24 /* CAN gateway types */
  25 enum {
  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 */
  34 enum {
  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
  66 struct 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
  73 struct cgw_csum_xor {
  74         __s8 from_idx;
  75         __s8 to_idx;
  76         __s8 result_idx;
  77         __u8 init_xor_val;
  78 } __attribute__((packed));
  79
  80 struct 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) */
  96 enum {
  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