/*
* socketcan/can/gw.h
*
- * Definitions for CAN frame Gateway/Router/Bridge
+ * Definitions for CAN frame Gateway/Router/Bridge
*
* $Id$
*
* Author: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
- * Copyright (c) 2002-2010 Volkswagen Group Electronic Research
+ * Copyright (c) 2011 Volkswagen Group Electronic Research
* All rights reserved.
*
* Send feedback to <socketcan-users@lists.berlios.de>
#ifndef CAN_GW_H
#define CAN_GW_H
+#include <linux/types.h>
#include <socketcan/can.h>
struct rtcanmsg {
__s8 to_idx;
__s8 result_idx;
__u8 init_xor_val;
-} __attribute__ ((packed));
+} __attribute__((packed));
struct cgw_csum_crc8 {
__s8 from_idx;
__u8 init_crc_val;
__u8 final_xor_val;
__u8 crctab[256];
-} __attribute__ ((packed));
+ __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
*
* 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 261 bytes):
+ * 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!
*/