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canfd: add new data structures and constants

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- add new struct canfd_frame
- check identical element offsets in struct can_frame and struct canfd_frame
- new ETH_P_CANFD definition to tag CAN FD skbs correctly
- add CAN_MTU and CANFD_MTU definitions for easy frame and mode detection
- add CAN[FD]_MAX_[DLC|DLEN] helper constants to remove hard coded values
- update existing struct can_frame with helper constants and comments

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Oliver Hartkopp
2012-06-13 20:04:33 +02:00
committed by Marc Kleine-Budde
parent 5b92da0443
commit 7c9416365c
3 changed files with 63 additions and 6 deletions
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59
include/linux/can.h
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@@ -46,18 +46,67 @@ typedef __u32 canid_t;
*/
typedef __u32 can_err_mask_t;
/* CAN payload length and DLC definitions according to ISO 11898-1 */
#define CAN_MAX_DLC 8
#define CAN_MAX_DLEN 8
/* CAN FD payload length and DLC definitions according to ISO 11898-7 */
#define CANFD_MAX_DLC 15
#define CANFD_MAX_DLEN 64
/**
* struct can_frame - basic CAN frame structure
* @can_id: the CAN ID of the frame and CAN_*_FLAG flags, see above.
* @can_dlc: the data length field of the CAN frame
* @data: the CAN frame payload.
* @can_id: CAN ID of the frame and CAN_*_FLAG flags, see canid_t definition
* @can_dlc: frame payload length in byte (0 .. 8) aka data length code
* N.B. the DLC field from ISO 11898-1 Chapter 8.4.2.3 has a 1:1
* mapping of the 'data length code' to the real payload length
* @data: CAN frame payload (up to 8 byte)
*/
struct can_frame {
canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
__u8 can_dlc; /* data length code: 0 .. 8 */
__u8 data[8] __attribute__((aligned(8)));
__u8 can_dlc; /* frame payload length in byte (0 .. CAN_MAX_DLEN) */
__u8 data[CAN_MAX_DLEN] __attribute__((aligned(8)));
};
/*
* defined bits for canfd_frame.flags
*
* As the default for CAN FD should be to support the high data rate in the
* payload section of the frame (HDR) and to support up to 64 byte in the
* data section (EDL) the bits are only set in the non-default case.
* Btw. as long as there's no real implementation for CAN FD network driver
* these bits are only preliminary.
*
* RX: NOHDR/NOEDL - info about received CAN FD frame
* ESI - bit from originating CAN controller
* TX: NOHDR/NOEDL - control per-frame settings if supported by CAN controller
* ESI - bit is set by local CAN controller
*/
#define CANFD_NOHDR 0x01 /* frame without high data rate */
#define CANFD_NOEDL 0x02 /* frame without extended data length */
#define CANFD_ESI 0x04 /* error state indicator */
/**
* struct canfd_frame - CAN flexible data rate frame structure
* @can_id: CAN ID of the frame and CAN_*_FLAG flags, see canid_t definition
* @len: frame payload length in byte (0 .. CANFD_MAX_DLEN)
* @flags: additional flags for CAN FD
* @__res0: reserved / padding
* @__res1: reserved / padding
* @data: CAN FD frame payload (up to CANFD_MAX_DLEN byte)
*/
struct canfd_frame {
canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
__u8 len; /* frame payload length in byte */
__u8 flags; /* additional flags for CAN FD */
__u8 __res0; /* reserved / padding */
__u8 __res1; /* reserved / padding */
__u8 data[CANFD_MAX_DLEN] __attribute__((aligned(8)));
};
#define CAN_MTU (sizeof(struct can_frame))
#define CANFD_MTU (sizeof(struct canfd_frame))
/* particular protocols of the protocol family PF_CAN */
#define CAN_RAW 1 /* RAW sockets */
#define CAN_BCM 2 /* Broadcast Manager */