can: kvaser_usb: advertise timestamping capabilities and add ioctl support

Currently, userland has no method to query which timestamping features
are supported by the kvaser_usb driver (aside maybe of getting RX
messages and observe whether or not hardware timestamps stay at zero).

The canonical way for a network driver to advertise what kind of
timestamping it supports is to implement
ethtool_ops::get_ts_info(). Here, we use the CAN specific
can_ethtool_op_get_ts_info_hwts() function to achieve this.

In addition, the driver currently does not support the hardware
timestamps ioctls. According to [1], SIOCSHWTSTAMP is "must" and
SIOCGHWTSTAMP is "should". This patch fills up that gap by
implementing net_device_ops::ndo_eth_ioctl() using the CAN specific
function can_eth_ioctl_hwts().

[1] kernel doc Timestamping, section 3.1: "Hardware Timestamping
Implementation: Device Drivers"
Link: https://docs.kernel.org/networking/timestamping.html#hardware-timestamping-implementation-device-drivers

CC: Jimmy Assarsson <[e-mail]>
Signed-off-by: Vincent Mailhol <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/usb/kvaser_usb/kvaser_usb.h

···
 #define KVASER_USB_QUIRK_HAS_SILENT_MODE	BIT(0)
 #define KVASER_USB_QUIRK_HAS_TXRX_ERRORS	BIT(1)
 #define KVASER_USB_QUIRK_IGNORE_CLK_FREQ	BIT(2)
+#define KVASER_USB_QUIRK_HAS_HARDWARE_TIMESTAMP	BIT(3)
 
 /* Device capabilities */
 #define KVASER_USB_CAP_BERR_CAP			0x01

drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c

···
 
 #include <linux/completion.h>
 #include <linux/device.h>
+#include <linux/ethtool.h>
 #include <linux/gfp.h>
 #include <linux/if.h>
 #include <linux/kernel.h>
···
 #define USB_HYBRID_PRO_CANLIN_PRODUCT_ID	278
 
 static const struct kvaser_usb_driver_info kvaser_usb_driver_info_hydra = {
-	.quirks = 0,
+	.quirks = KVASER_USB_QUIRK_HAS_HARDWARE_TIMESTAMP,
 	.ops = &kvaser_usb_hydra_dev_ops,
 };
 
···
 	.ndo_change_mtu = can_change_mtu,
 };
 
+static const struct net_device_ops kvaser_usb_netdev_ops_hwts = {
+	.ndo_open = kvaser_usb_open,
+	.ndo_stop = kvaser_usb_close,
+	.ndo_eth_ioctl = can_eth_ioctl_hwts,
+	.ndo_start_xmit = kvaser_usb_start_xmit,
+	.ndo_change_mtu = can_change_mtu,
+};
+
+static const struct ethtool_ops kvaser_usb_ethtool_ops = {
+	.get_ts_info = ethtool_op_get_ts_info,
+};
+
+static const struct ethtool_ops kvaser_usb_ethtool_ops_hwts = {
+	.get_ts_info = can_ethtool_op_get_ts_info_hwts,
+};
+
 static void kvaser_usb_remove_interfaces(struct kvaser_usb *dev)
 {
 	int i;
···
 	netdev->flags |= IFF_ECHO;
 
 	netdev->netdev_ops = &kvaser_usb_netdev_ops;
-
+	if (driver_info->quirks & KVASER_USB_QUIRK_HAS_HARDWARE_TIMESTAMP) {
+		netdev->netdev_ops = &kvaser_usb_netdev_ops_hwts;
+		netdev->ethtool_ops = &kvaser_usb_ethtool_ops_hwts;
+	} else {
+		netdev->netdev_ops = &kvaser_usb_netdev_ops;
+		netdev->ethtool_ops = &kvaser_usb_ethtool_ops;
+	}
 	SET_NETDEV_DEV(netdev, &dev->intf->dev);
 	netdev->dev_id = channel;