can: allow to change the device mtu for CAN FD capable devices

The configuration for CAN FD depends on CAN_CTRLMODE_FD enabled in the driver
specific ctrlmode_supported capabilities.

The configuration can be done either with the 'fd { on | off }' option in the
'ip' tool from iproute2 or by setting the CAN netdevice MTU to CAN_MTU (16) or
to CANFD_MTU (72).

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

2 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 8adaee96f292..3ce5e526525f 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -113,6 +113,7 @@ struct can_priv *safe_candev_priv(struct net_device *dev);
 
 int open_candev(struct net_device *dev);
 void close_candev(struct net_device *dev);
+int can_change_mtu(struct net_device *dev, int new_mtu);
 
 int register_candev(struct net_device *dev);
 void unregister_candev(struct net_device *dev);
diff --git a/include/uapi/linux/can/netlink.h b/include/uapi/linux/can/netlink.h
index b41933d6bdcd..7e2e1863db16 100644
--- a/include/uapi/linux/can/netlink.h
+++ b/include/uapi/linux/can/netlink.h
@@ -96,6 +96,7 @@ struct can_ctrlmode {
 #define CAN_CTRLMODE_3_SAMPLES          0x04    /* Triple sampling mode */
 #define CAN_CTRLMODE_ONE_SHOT           0x08    /* One-Shot mode */
 #define CAN_CTRLMODE_BERR_REPORTING     0x10    /* Bus-error reporting */
+#define CAN_CTRLMODE_FD                 0x20    /* CAN FD mode */
 
 /*
  * CAN device statistics