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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: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Oliver Hartkopp 2017-04-11 15:43:43 +02:00 committed by Marc Kleine-Budde
parent 7e97d274db
commit 0254688422
1 changed files with 9 additions and 0 deletions
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9
include/uapi/linux/can.h
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@ -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