163 lines
4.6 KiB
C
163 lines
4.6 KiB
C
/*
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* linux/can/gw.h
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*
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* Definitions for CAN frame Gateway/Router/Bridge
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*
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* Author: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
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* Copyright (c) 2011 Volkswagen Group Electronic Research
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* All rights reserved.
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*
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*/
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#ifndef CAN_GW_H
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#define CAN_GW_H
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#include <linux/types.h>
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#include <linux/can.h>
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struct rtcanmsg {
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__u8 can_family;
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__u8 gwtype;
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__u16 flags;
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};
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/* CAN gateway types */
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enum {
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CGW_TYPE_UNSPEC,
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CGW_TYPE_CAN_CAN, /* CAN->CAN routing */
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__CGW_TYPE_MAX
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};
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#define CGW_TYPE_MAX (__CGW_TYPE_MAX - 1)
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/* CAN rtnetlink attribute definitions */
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enum {
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CGW_UNSPEC,
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CGW_MOD_AND, /* CAN frame modification binary AND */
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CGW_MOD_OR, /* CAN frame modification binary OR */
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CGW_MOD_XOR, /* CAN frame modification binary XOR */
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CGW_MOD_SET, /* CAN frame modification set alternate values */
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CGW_CS_XOR, /* set data[] XOR checksum into data[index] */
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CGW_CS_CRC8, /* set data[] CRC8 checksum into data[index] */
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CGW_HANDLED, /* number of handled CAN frames */
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CGW_DROPPED, /* number of dropped CAN frames */
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CGW_SRC_IF, /* ifindex of source network interface */
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CGW_DST_IF, /* ifindex of destination network interface */
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CGW_FILTER, /* specify struct can_filter on source CAN device */
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__CGW_MAX
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};
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#define CGW_MAX (__CGW_MAX - 1)
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#define CGW_FLAGS_CAN_ECHO 0x01
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#define CGW_FLAGS_CAN_SRC_TSTAMP 0x02
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#define CGW_MOD_FUNCS 4 /* AND OR XOR SET */
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/* CAN frame elements that are affected by curr. 3 CAN frame modifications */
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#define CGW_MOD_ID 0x01
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#define CGW_MOD_DLC 0x02
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#define CGW_MOD_DATA 0x04
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#define CGW_FRAME_MODS 3 /* ID DLC DATA */
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#define MAX_MODFUNCTIONS (CGW_MOD_FUNCS * CGW_FRAME_MODS)
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struct cgw_frame_mod {
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struct can_frame cf;
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__u8 modtype;
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} __attribute__((packed));
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#define CGW_MODATTR_LEN sizeof(struct cgw_frame_mod)
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struct cgw_csum_xor {
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__s8 from_idx;
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__s8 to_idx;
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__s8 result_idx;
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__u8 init_xor_val;
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} __attribute__((packed));
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struct cgw_csum_crc8 {
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__s8 from_idx;
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__s8 to_idx;
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__s8 result_idx;
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__u8 init_crc_val;
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__u8 final_xor_val;
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__u8 crctab[256];
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__u8 profile;
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__u8 profile_data[20];
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} __attribute__((packed));
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/* length of checksum operation parameters. idx = index in CAN frame data[] */
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#define CGW_CS_XOR_LEN sizeof(struct cgw_csum_xor)
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#define CGW_CS_CRC8_LEN sizeof(struct cgw_csum_crc8)
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/* CRC8 profiles (compute CRC for additional data elements - see below) */
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enum {
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CGW_CRC8PRF_UNSPEC,
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CGW_CRC8PRF_1U8, /* compute one additional u8 value */
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CGW_CRC8PRF_16U8, /* u8 value table indexed by data[1] & 0xF */
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CGW_CRC8PRF_SFFID_XOR, /* (can_id & 0xFF) ^ (can_id >> 8 & 0xFF) */
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__CGW_CRC8PRF_MAX
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};
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#define CGW_CRC8PRF_MAX (__CGW_CRC8PRF_MAX - 1)
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/*
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* CAN rtnetlink attribute contents in detail
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*
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* CGW_XXX_IF (length 4 bytes):
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* Sets an interface index for source/destination network interfaces.
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* For the CAN->CAN gwtype the indices of _two_ CAN interfaces are mandatory.
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*
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* CGW_FILTER (length 8 bytes):
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* Sets a CAN receive filter for the gateway job specified by the
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* struct can_filter described in include/linux/can.h
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*
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* CGW_MOD_XXX (length 17 bytes):
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* Specifies a modification that's done to a received CAN frame before it is
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* send out to the destination interface.
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*
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* <struct can_frame> data used as operator
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* <u8> affected CAN frame elements
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*
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* CGW_CS_XOR (length 4 bytes):
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* Set a simple XOR checksum starting with an initial value into
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* data[result-idx] using data[start-idx] .. data[end-idx]
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*
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* The XOR checksum is calculated like this:
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*
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* xor = init_xor_val
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*
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* for (i = from_idx .. to_idx)
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* xor ^= can_frame.data[i]
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*
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* can_frame.data[ result_idx ] = xor
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*
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* CGW_CS_CRC8 (length 282 bytes):
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* Set a CRC8 value into data[result-idx] using a given 256 byte CRC8 table,
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* a given initial value and a defined input data[start-idx] .. data[end-idx].
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* Finally the result value is XOR'ed with the final_xor_val.
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*
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* The CRC8 checksum is calculated like this:
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*
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* crc = init_crc_val
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*
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* for (i = from_idx .. to_idx)
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* crc = crctab[ crc ^ can_frame.data[i] ]
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*
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* can_frame.data[ result_idx ] = crc ^ final_xor_val
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*
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* The calculated CRC may contain additional source data elements that can be
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* defined in the handling of 'checksum profiles' e.g. shown in AUTOSAR specs
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* like http://www.autosar.org/download/R4.0/AUTOSAR_SWS_E2ELibrary.pdf
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* E.g. the profile_data[] may contain additional u8 values (called DATA_IDs)
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* that are used depending on counter values inside the CAN frame data[].
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* So far only three profiles have been implemented for illustration.
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*
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* Remark: In general the attribute data is a linear buffer.
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* Beware of sending unpacked or aligned structs!
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*/
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#endif
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