[PATCH v2 5/5] can: bcm: add documentation for CAN FD support

[Oliver Hartkopp <socketcan@hartkopp.net>]

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 Documentation/networking/can.txt | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
index d58ff84..3ec4375 100644
--- a/Documentation/networking/can.txt
+++ b/Documentation/networking/can.txt
@@ -852,6 +852,28 @@ solution for a couple of reasons:
 
     write(s, &msg, sizeof(msg));
 
+  4.2.6 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)
 
-- 
2.8.1