can: raw: add CAN XL support

Enable CAN_RAW sockets to read and write CAN XL frames analogue to the
CAN FD extension (new CAN_RAW_XL_FRAMES sockopt).

A CAN XL network interface is capable to handle Classical CAN, CAN FD and
CAN XL frames. When CAN_RAW_XL_FRAMES is enabled, the CAN_RAW socket checks
whether the addressed CAN network interface is capable to handle the
provided CAN frame.

In opposite to the fixed number of bytes for
- CAN frames (CAN_MTU = sizeof(struct can_frame))
- CAN FD frames (CANFD_MTU = sizeof(struct can_frame))
the number of bytes when reading/writing CAN XL frames depends on the
number of data bytes. For efficiency reasons the length of the struct
canxl_frame is truncated to the needed size for read/write operations.
This leads to a calculated size of CANXL_HDR_SIZE + canxl_frame::len which
is enforced on write() operations and guaranteed on read() operations.

NB: Valid length values are 1 .. 2048 (CANXL_MIN_DLEN .. CANXL_MAX_DLEN).

Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20220912170725.120748-8-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/uapi/linux/can/raw.h b/include/uapi/linux/can/raw.h
index 3386aa81fdf2..ff12f525c37c 100644
--- a/include/uapi/linux/can/raw.h
+++ b/include/uapi/linux/can/raw.h
@@ -62,6 +62,7 @@ enum {
 	CAN_RAW_RECV_OWN_MSGS,	/* receive my own msgs (default:off) */
 	CAN_RAW_FD_FRAMES,	/* allow CAN FD frames (default:off) */
 	CAN_RAW_JOIN_FILTERS,	/* all filters must match to trigger */
+	CAN_RAW_XL_FRAMES,	/* allow CAN XL frames (default:off) */
 };
 
 #endif /* !_UAPI_CAN_RAW_H */