canfd: add support for CAN FD in CAN_RAW sockets

- introduce a new sockopt CAN_RAW_FD_FRAMES to allow CAN FD frames
- handle CAN frames and CAN FD frames simultaneously when enabled

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

include/linux/can/raw.h

@@ -23,7 +23,8 @@ enum {
 	CAN_RAW_FILTER = 1,	/* set 0 .. n can_filter(s)          */
 	CAN_RAW_ERR_FILTER,	/* set filter for error frames       */
 	CAN_RAW_LOOPBACK,	/* local loopback (default:on)       */
-	CAN_RAW_RECV_OWN_MSGS	/* receive my own msgs (default:off) */
+	CAN_RAW_RECV_OWN_MSGS,	/* receive my own msgs (default:off) */
+	CAN_RAW_FD_FRAMES,	/* allow CAN FD frames (default:off) */
 };
 
 #endif