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can: bcm: add documentation for CAN FD support 

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Oliver Hartkopp 2016-06-17 15:35:28 +02:00 committed by Marc Kleine-Budde
parent 6f3b911d5f
commit 9be05c7f37
1 changed files with 24 additions and 1 deletions
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25
Documentation/networking/can.txt
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@ -31,6 +31,7 @@ This file contains
4.2.4 Broadcast Manager message sequence transmission
4.2.5 Broadcast Manager receive filter timers
4.2.6 Broadcast Manager multiplex message receive filter
4.2.7 Broadcast Manager CAN FD support
4.3 connected transport protocols (SOCK_SEQPACKET)
4.4 unconnected transport protocols (SOCK_DGRAM)
@ -799,7 +800,7 @@ solution for a couple of reasons:
} mytxmsg;
(..)
mytxmsg.nframes = 4;
mytxmsg.msg_head.nframes = 4;
(..)
write(s, &mytxmsg, sizeof(mytxmsg));
@ -852,6 +853,28 @@ solution for a couple of reasons:
write(s, &msg, sizeof(msg));
4.2.7 Broadcast Manager CAN FD support
The programming API of the CAN_BCM depends on struct can_frame which is
given as array directly behind the bcm_msg_head structure. To follow this
schema for the CAN FD frames a new flag 'CAN_FD_FRAME' in the bcm_msg_head
flags indicates that the concatenated CAN frame structures behind the
bcm_msg_head are defined as struct canfd_frame.
struct {
struct bcm_msg_head msg_head;
struct canfd_frame frame[5];
} msg;
msg.msg_head.opcode = RX_SETUP;
msg.msg_head.can_id = 0x42;
msg.msg_head.flags = CAN_FD_FRAME;
msg.msg_head.nframes = 5;
(..)
When using CAN FD frames for multiplex filtering the MUX mask is still
expected in the first 64 bit of the struct canfd_frame data section.
4.3 connected transport protocols (SOCK_SEQPACKET)
4.4 unconnected transport protocols (SOCK_DGRAM)