include/uapi/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  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of Volkswagen nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * Alternatively, provided that this notice is retained in full, this
  23  * software may be distributed under the terms of the GNU General
  24  * Public License ("GPL") version 2, in which case the provisions of the
  25  * GPL apply INSTEAD OF those given above.
  26  *
  27  * The provided data structures and external interfaces from this code
  28  * are not restricted to be used by modules with a GPL compatible license.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  31  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  32  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  33  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  34  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  35  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  36  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  40  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
  41  * DAMAGE.
  42  */
  43
  44 #ifndef _UAPI_CAN_GW_H
  45 #define _UAPI_CAN_GW_H
  46
  47 #include <linux/types.h>
  48 #include <linux/can.h>
  49
  50 struct rtcanmsg {
  51         __u8  can_family;
  52         __u8  gwtype;
  53         __u16 flags;
  54 };
  55
  56 /* CAN gateway types */
  57 enum {
  58         CGW_TYPE_UNSPEC,
  59         CGW_TYPE_CAN_CAN,       /* CAN->CAN routing */
  60         __CGW_TYPE_MAX
  61 };
  62
  63 #define CGW_TYPE_MAX (__CGW_TYPE_MAX - 1)
  64
  65 /* CAN rtnetlink attribute definitions */
  66 enum {
  67         CGW_UNSPEC,
  68         CGW_MOD_AND,    /* CAN frame modification binary AND */
  69         CGW_MOD_OR,     /* CAN frame modification binary OR */
  70         CGW_MOD_XOR,    /* CAN frame modification binary XOR */
  71         CGW_MOD_SET,    /* CAN frame modification set alternate values */
  72         CGW_CS_XOR,     /* set data[] XOR checksum into data[index] */
  73         CGW_CS_CRC8,    /* set data[] CRC8 checksum into data[index] */
  74         CGW_HANDLED,    /* number of handled CAN frames */
  75         CGW_DROPPED,    /* number of dropped CAN frames */
  76         CGW_SRC_IF,     /* ifindex of source network interface */
  77         CGW_DST_IF,     /* ifindex of destination network interface */
  78         CGW_FILTER,     /* specify struct can_filter on source CAN device */
  79         CGW_DELETED,    /* number of deleted CAN frames (see max_hops param) */
  80         CGW_LIM_HOPS,   /* limit the number of hops of this specific rule */
  81         __CGW_MAX
  82 };
  83
  84 #define CGW_MAX (__CGW_MAX - 1)
  85
  86 #define CGW_FLAGS_CAN_ECHO 0x01
  87 #define CGW_FLAGS_CAN_SRC_TSTAMP 0x02
  88 #define CGW_FLAGS_CAN_IIF_TX_OK 0x04
  89
  90 #define CGW_MOD_FUNCS 4 /* AND OR XOR SET */
  91
  92 /* CAN frame elements that are affected by curr. 3 CAN frame modifications */
  93 #define CGW_MOD_ID      0x01
  94 #define CGW_MOD_DLC     0x02
  95 #define CGW_MOD_DATA    0x04
  96
  97 #define CGW_FRAME_MODS 3 /* ID DLC DATA */
  98
  99 #define MAX_MODFUNCTIONS (CGW_MOD_FUNCS * CGW_FRAME_MODS)
 100
 101 struct cgw_frame_mod {
 102         struct can_frame cf;
 103         __u8 modtype;
 104 } __attribute__((packed));
 105
 106 #define CGW_MODATTR_LEN sizeof(struct cgw_frame_mod)
 107
 108 struct cgw_csum_xor {
 109         __s8 from_idx;
 110         __s8 to_idx;
 111         __s8 result_idx;
 112         __u8 init_xor_val;
 113 } __attribute__((packed));
 114
 115 struct cgw_csum_crc8 {
 116         __s8 from_idx;
 117         __s8 to_idx;
 118         __s8 result_idx;
 119         __u8 init_crc_val;
 120         __u8 final_xor_val;
 121         __u8 crctab[256];
 122         __u8 profile;
 123         __u8 profile_data[20];
 124 } __attribute__((packed));
 125
 126 /* length of checksum operation parameters. idx = index in CAN frame data[] */
 127 #define CGW_CS_XOR_LEN  sizeof(struct cgw_csum_xor)
 128 #define CGW_CS_CRC8_LEN  sizeof(struct cgw_csum_crc8)
 129
 130 /* CRC8 profiles (compute CRC for additional data elements - see below) */
 131 enum {
 132         CGW_CRC8PRF_UNSPEC,
 133         CGW_CRC8PRF_1U8,        /* compute one additional u8 value */
 134         CGW_CRC8PRF_16U8,       /* u8 value table indexed by data[1] & 0xF */
 135         CGW_CRC8PRF_SFFID_XOR,  /* (can_id & 0xFF) ^ (can_id >> 8 & 0xFF) */
 136         __CGW_CRC8PRF_MAX
 137 };
 138
 139 #define CGW_CRC8PRF_MAX (__CGW_CRC8PRF_MAX - 1)
 140
 141 /*
 142  * CAN rtnetlink attribute contents in detail
 143  *
 144  * CGW_XXX_IF (length 4 bytes):
 145  * Sets an interface index for source/destination network interfaces.
 146  * For the CAN->CAN gwtype the indices of _two_ CAN interfaces are mandatory.
 147  *
 148  * CGW_FILTER (length 8 bytes):
 149  * Sets a CAN receive filter for the gateway job specified by the
 150  * struct can_filter described in include/linux/can.h
 151  *
 152  * CGW_MOD_(AND|OR|XOR|SET) (length 17 bytes):
 153  * Specifies a modification that's done to a received CAN frame before it is
 154  * send out to the destination interface.
 155  *
 156  * <struct can_frame> data used as operator
 157  * <u8> affected CAN frame elements
 158  *
 159  * CGW_LIM_HOPS (length 1 byte):
 160  * Limit the number of hops of this specific rule. Usually the received CAN
 161  * frame can be processed as much as 'max_hops' times (which is given at module
 162  * load time of the can-gw module). This value is used to reduce the number of
 163  * possible hops for this gateway rule to a value smaller then max_hops.
 164  *
 165  * CGW_CS_XOR (length 4 bytes):
 166  * Set a simple XOR checksum starting with an initial value into
 167  * data[result-idx] using data[start-idx] .. data[end-idx]
 168  *
 169  * The XOR checksum is calculated like this:
 170  *
 171  * xor = init_xor_val
 172  *
 173  * for (i = from_idx .. to_idx)
 174  *      xor ^= can_frame.data[i]
 175  *
 176  * can_frame.data[ result_idx ] = xor
 177  *
 178  * CGW_CS_CRC8 (length 282 bytes):
 179  * Set a CRC8 value into data[result-idx] using a given 256 byte CRC8 table,
 180  * a given initial value and a defined input data[start-idx] .. data[end-idx].
 181  * Finally the result value is XOR'ed with the final_xor_val.
 182  *
 183  * The CRC8 checksum is calculated like this:
 184  *
 185  * crc = init_crc_val
 186  *
 187  * for (i = from_idx .. to_idx)
 188  *      crc = crctab[ crc ^ can_frame.data[i] ]
 189  *
 190  * can_frame.data[ result_idx ] = crc ^ final_xor_val
 191  *
 192  * The calculated CRC may contain additional source data elements that can be
 193  * defined in the handling of 'checksum profiles' e.g. shown in AUTOSAR specs
 194  * like http://www.autosar.org/download/R4.0/AUTOSAR_SWS_E2ELibrary.pdf
 195  * E.g. the profile_data[] may contain additional u8 values (called DATA_IDs)
 196  * that are used depending on counter values inside the CAN frame data[].
 197  * So far only three profiles have been implemented for illustration.
 198  *
 199  * Remark: In general the attribute data is a linear buffer.
 200  *         Beware of sending unpacked or aligned structs!
 201  */
 202
 203 #endif /* !_UAPI_CAN_GW_H */