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>

diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
index d58ff8467953a2da610891c921d750842f8c1806..aa15b9ee2e7000595d04df9f2faeae760cb27703 100644 (file)
--- a/Documentation/networking/can.txt
+++ b/Documentation/networking/can.txt
@@ -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
       4.2.4 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)
 
     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;
 
     (..)

-    mytxmsg.nframes = 4;
+    mytxmsg.msg_head.nframes = 4;

     (..)
 
     write(s, &mytxmsg, sizeof(mytxmsg));
     (..)
 
     write(s, &mytxmsg, sizeof(mytxmsg));


@@ -852,6 +853,28 @@ solution for a couple of reasons:
 
     write(s, &msg, sizeof(msg));
 
 
     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)
 
   4.3 connected transport protocols (SOCK_SEQPACKET)
   4.4 unconnected transport protocols (SOCK_DGRAM)