vcan: add CAN FD support

- move the length calculation from dlc to real length (using canfd_frame)
- allow to switch the driver between CAN and CAN FD (change of MTU)

Signed-off-by: Oliver Hartkopp <[e-mail]>
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/vcan.c

···
 
 static void vcan_rx(struct sk_buff *skb, struct net_device *dev)
 {
-	struct can_frame *cf = (struct can_frame *)skb->data;
+	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 	struct net_device_stats *stats = &dev->stats;
 
 	stats->rx_packets++;
-	stats->rx_bytes += cf->can_dlc;
+	stats->rx_bytes += cfd->len;
 
-	skb->protocol  = htons(ETH_P_CAN);
 	skb->pkt_type  = PACKET_BROADCAST;
 	skb->dev       = dev;
 	skb->ip_summed = CHECKSUM_UNNECESSARY;
···
 
 static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
 {
-	struct can_frame *cf = (struct can_frame *)skb->data;
+	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 	struct net_device_stats *stats = &dev->stats;
 	int loop;
 
···
 		return NETDEV_TX_OK;
 
 	stats->tx_packets++;
-	stats->tx_bytes += cf->can_dlc;
+	stats->tx_bytes += cfd->len;
 
 	/* set flag whether this packet has to be looped back */
 	loop = skb->pkt_type == PACKET_LOOPBACK;
···
 			 * CAN core already did the echo for us
 			 */
 			stats->rx_packets++;
-			stats->rx_bytes += cf->can_dlc;
+			stats->rx_bytes += cfd->len;
 		}
 		kfree_skb(skb);
 		return NETDEV_TX_OK;
···
 	return NETDEV_TX_OK;
 }
 
+static int vcan_change_mtu(struct net_device *dev, int new_mtu)
+{
+	/* Do not allow changing the MTU while running */
+	if (dev->flags & IFF_UP)
+		return -EBUSY;
+
+	if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
+		return -EINVAL;
+
+	dev->mtu = new_mtu;
+	return 0;
+}
+
 static const struct net_device_ops vcan_netdev_ops = {
 	.ndo_start_xmit = vcan_tx,
+	.ndo_change_mtu = vcan_change_mtu,
 };
 
 static void vcan_setup(struct net_device *dev)
 {
 	dev->type		= ARPHRD_CAN;
-	dev->mtu		= sizeof(struct can_frame);
+	dev->mtu		= CAN_MTU;
 	dev->hard_header_len	= 0;
 	dev->addr_len		= 0;
 	dev->tx_queue_len	= 0;