[PATCH] can: introduce CANFD_USE flag for mixed content in struct canfd_frame
From: Oliver Hartkopp <socketcan@hartkopp.net>
Date: 2016-08-12 08:34:19
Subsystem:
can network layer, the rest · Maintainers:
Oliver Hartkopp, Marc Kleine-Budde, Linus Torvalds
The struct can_frame and struct canfd_frame intentionaly 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_USE 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_USE flag is disregarded by Linux. Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> --- include/uapi/linux/can.h | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/include/uapi/linux/can.h b/include/uapi/linux/can.h
index 9692cda..698ffc5 100644
--- a/include/uapi/linux/can.h
+++ b/include/uapi/linux/can.h@@ -124,9 +124,18 @@ 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 intentionaly 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_USE 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_USE 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_USE 0x04 /* mark CAN FD for dual use of struct canfd_frame */ /** * struct canfd_frame - CAN flexible data rate frame structure
--
2.8.1