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 163