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/*

 * linux/can/gw.h

 *

 * Definitions for CAN frame Gateway/Router/Bridge

 *

 * Author: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>

 * Copyright (c) 2011 Volkswagen Group Electronic Research

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. Neither the name of Volkswagen nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * Alternatively, provided that this notice is retained in full, this

 * software may be distributed under the terms of the GNU General

 * Public License ("GPL") version 2, in which case the provisions of the

 * GPL apply INSTEAD OF those given above.

 *

 * The provided data structures and external interfaces from this code

 * are not restricted to be used by modules with a GPL compatible license.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH

 * DAMAGE.

 */

#ifndef CAN_GW_H

#define CAN_GW_H

#include <linux/types.h>

#include <linux/can.h>

struct rtcanmsg {

        __u8  can_family;

        __u8  gwtype;

        __u16 flags;

};

/* CAN gateway types */

enum {

        CGW_TYPE_UNSPEC,

        CGW_TYPE_CAN_CAN,       /* CAN->CAN routing */

        __CGW_TYPE_MAX

};

#define CGW_TYPE_MAX (__CGW_TYPE_MAX - 1)

/* CAN rtnetlink attribute definitions */

enum {

        CGW_UNSPEC,

        CGW_MOD_AND,    /* CAN frame modification binary AND */

        CGW_MOD_OR,     /* CAN frame modification binary OR */

        CGW_MOD_XOR,    /* CAN frame modification binary XOR */

        CGW_MOD_SET,    /* CAN frame modification set alternate values */

        CGW_CS_XOR,     /* set data[] XOR checksum into data[index] */

        CGW_CS_CRC8,    /* set data[] CRC8 checksum into data[index] */

        CGW_HANDLED,    /* number of handled CAN frames */

        CGW_DROPPED,    /* number of dropped CAN frames */

        CGW_SRC_IF,     /* ifindex of source network interface */

        CGW_DST_IF,     /* ifindex of destination network interface */

        CGW_FILTER,     /* specify struct can_filter on source CAN device */

        CGW_DELETED,    /* number of deleted CAN frames (see max_hops param) */

        CGW_LIM_HOPS,   /* limit the number of hops of this specific rule */

        __CGW_MAX

};

#define CGW_MAX (__CGW_MAX - 1)

#define CGW_FLAGS_CAN_ECHO 0x01

#define CGW_FLAGS_CAN_SRC_TSTAMP 0x02

#define CGW_FLAGS_CAN_IIF_TX_OK 0x04

#define CGW_MOD_FUNCS 4 /* AND OR XOR SET */

/* CAN frame elements that are affected by curr. 3 CAN frame modifications */

#define CGW_MOD_ID      0x01

#define CGW_MOD_DLC     0x02

#define CGW_MOD_DATA    0x04

#define CGW_FRAME_MODS 3 /* ID DLC DATA */

#define MAX_MODFUNCTIONS (CGW_MOD_FUNCS * CGW_FRAME_MODS)

struct cgw_frame_mod {

        struct can_frame cf;

        __u8 modtype;

} __attribute__((packed));

#define CGW_MODATTR_LEN sizeof(struct cgw_frame_mod)

struct cgw_csum_xor {

        __s8 from_idx;

        __s8 to_idx;

        __s8 result_idx;

        __u8 init_xor_val;

} __attribute__((packed));

struct cgw_csum_crc8 {

        __s8 from_idx;

        __s8 to_idx;

        __s8 result_idx;

        __u8 init_crc_val;

        __u8 final_xor_val;

        __u8 crctab[256];

        __u8 profile;

        __u8 profile_data[20];

} __attribute__((packed));

/* length of checksum operation parameters. idx = index in CAN frame data[] */

#define CGW_CS_XOR_LEN  sizeof(struct cgw_csum_xor)

#define CGW_CS_CRC8_LEN  sizeof(struct cgw_csum_crc8)

/* CRC8 profiles (compute CRC for additional data elements - see below) */

enum {

        CGW_CRC8PRF_UNSPEC,

        CGW_CRC8PRF_1U8,        /* compute one additional u8 value */

        CGW_CRC8PRF_16U8,       /* u8 value table indexed by data[1] & 0xF */

        CGW_CRC8PRF_SFFID_XOR,  /* (can_id & 0xFF) ^ (can_id >> 8 & 0xFF) */

        __CGW_CRC8PRF_MAX

};

#define CGW_CRC8PRF_MAX (__CGW_CRC8PRF_MAX - 1)

/*

 * CAN rtnetlink attribute contents in detail

 *

 * CGW_XXX_IF (length 4 bytes):

 * Sets an interface index for source/destination network interfaces.

 * For the CAN->CAN gwtype the indices of _two_ CAN interfaces are mandatory.

 *

 * CGW_FILTER (length 8 bytes):

 * Sets a CAN receive filter for the gateway job specified by the

 * struct can_filter described in include/linux/can.h

 *

 * CGW_MOD_(AND|OR|XOR|SET) (length 17 bytes):

 * Specifies a modification that's done to a received CAN frame before it is

 * send out to the destination interface.

 *

 * <struct can_frame> data used as operator

 * <u8> affected CAN frame elements

 *

 * CGW_LIM_HOPS (length 1 byte):

 * Limit the number of hops of this specific rule. Usually the received CAN

 * frame can be processed as much as 'max_hops' times (which is given at module

 * load time of the can-gw module). This value is used to reduce the number of

 * possible hops for this gateway rule to a value smaller then max_hops.

 *

 * CGW_CS_XOR (length 4 bytes):

 * Set a simple XOR checksum starting with an initial value into

 * data[result-idx] using data[start-idx] .. data[end-idx]

 *

 * The XOR checksum is calculated like this:

 *

 * xor = init_xor_val

 *

 * for (i = from_idx .. to_idx)

 *      xor ^= can_frame.data[i]

 *

 * can_frame.data[ result_idx ] = xor

 *

 * CGW_CS_CRC8 (length 282 bytes):

 * Set a CRC8 value into data[result-idx] using a given 256 byte CRC8 table,

 * a given initial value and a defined input data[start-idx] .. data[end-idx].

 * Finally the result value is XOR'ed with the final_xor_val.

 *

 * The CRC8 checksum is calculated like this:

 *

 * crc = init_crc_val

 *

 * for (i = from_idx .. to_idx)

 *      crc = crctab[ crc ^ can_frame.data[i] ]

 *

 * can_frame.data[ result_idx ] = crc ^ final_xor_val

 *

 * The calculated CRC may contain additional source data elements that can be

 * defined in the handling of 'checksum profiles' e.g. shown in AUTOSAR specs

 * like http://www.autosar.org/download/R4.0/AUTOSAR_SWS_E2ELibrary.pdf

 * E.g. the profile_data[] may contain additional u8 values (called DATA_IDs)

 * that are used depending on counter values inside the CAN frame data[].

 * So far only three profiles have been implemented for illustration.

 *

 * Remark: In general the attribute data is a linear buffer.

 *         Beware of sending unpacked or aligned structs!

 */

#endif