can: peak_usb: add adapter BEC callback definition

Add the definition of a new callback that enable any PEAK-System CAN USB
adapter to grant read access to its Bus Error Counters value. This ability is
not supported by all the PEAK-System adapters, thus, for those, the callback
pointer will be initiaized to NULL, which is correct regarding the linux-can
device driver specs.
Signed-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/peak_usb/pcan_usb_core.c

@@ -750,6 +750,7 @@ static int peak_usb_create_dev(const struct peak_usb_adapter *peak_usb_adapter,
 	dev->can.bittiming_const = &peak_usb_adapter->bittiming_const;
 	dev->can.do_set_bittiming = peak_usb_set_bittiming;
 	dev->can.do_set_mode = peak_usb_set_mode;
+	dev->can.do_get_berr_counter = peak_usb_adapter->do_get_berr_counter;
 	dev->can.ctrlmode_supported = peak_usb_adapter->ctrlmode_supported;
 
 	netdev->netdev_ops = &peak_usb_netdev_ops;

drivers/net/can/usb/peak_usb/pcan_usb_core.h

@@ -67,6 +67,8 @@ struct peak_usb_adapter {
 	int (*dev_stop)(struct peak_usb_device *dev);
 	int (*dev_restart_async)(struct peak_usb_device *dev, struct urb *urb,
 					u8 *buf);
+	int (*do_get_berr_counter)(const struct net_device *netdev,
+				   struct can_berr_counter *bec);
 	u8 ep_msg_in;
 	u8 ep_msg_out[PCAN_USB_MAX_CHANNEL];
 	u8 ts_used_bits;