Commit 02546884 authored by Oliver Hartkopp's avatar Oliver Hartkopp Committed by Marc Kleine-Budde
Browse files

can: uapi: introduce CANFD_FDF flag for mixed content in struct canfd_frame 

The struct can_frame and struct canfd_frame intentionally share the
same layout to be able to write CAN frame content into a CAN FD frame
structure. When this is done the former differentiation via CAN_MTU /
CANFD_MTU is lost. CANFD_FDF allows programmers to mark CAN FD frames
in the case of using struct canfd_frame for mixed CAN/CAN FD
content (dual use).

N.B. the Kernel APIs do NOT provide mixed CAN / CAN FD content inside
of struct canfd_frame therefore the CANFD_FDF flag is disregarded by
Linux.

Link: https://lore.kernel.org/r/20170411134343.3089-1-socketcan@hartkopp.net


Signed-off-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 7e97d274

include/uapi/linux/can.h

+9 −0
Original line number Diff line number Diff line
@@ -135,9 +135,18 @@ struct can_frame { 
 * controller only the CANFD_BRS bit is relevant for real CAN controllers when

 * building a CAN FD frame for transmission. Setting the CANFD_ESI bit can make

 * sense for virtual CAN interfaces to test applications with echoed frames.

 *

 * The struct can_frame and struct canfd_frame intentionally share the same

 * layout to be able to write CAN frame content into a CAN FD frame structure.

 * When this is done the former differentiation via CAN_MTU / CANFD_MTU gets

 * lost. CANFD_FDF allows programmers to mark CAN FD frames in the case of

 * using struct canfd_frame for mixed CAN / CAN FD content (dual use).

 * N.B. the Kernel APIs do NOT provide mixed CAN / CAN FD content inside of

 * struct canfd_frame therefore the CANFD_FDF flag is disregarded by Linux.

 */

#define CANFD_BRS 0x01 /* bit rate switch (second bitrate for payload data) */

#define CANFD_ESI 0x02 /* error state indicator of the transmitting node */

#define CANFD_FDF 0x04 /* mark CAN FD for dual use of struct canfd_frame */



/**

 * struct canfd_frame - CAN flexible data rate frame structure