can: kvaser_pciefd: advertise timestamping capabilities and add ioctl support

Currently, userland has no method to query which timestamping features
are supported by the kvaser_pciefd 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/kvaser_pciefd.c

···
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/device.h>
+#include <linux/ethtool.h>
 #include <linux/pci.h>
 #include <linux/can/dev.h>
 #include <linux/timer.h>
···
 static const struct net_device_ops kvaser_pciefd_netdev_ops = {
 	.ndo_open = kvaser_pciefd_open,
 	.ndo_stop = kvaser_pciefd_stop,
+	.ndo_eth_ioctl = can_eth_ioctl_hwts,
 	.ndo_start_xmit = kvaser_pciefd_start_xmit,
 	.ndo_change_mtu = can_change_mtu,
+};
+
+static const struct ethtool_ops kvaser_pciefd_ethtool_ops = {
+	.get_ts_info = can_ethtool_op_get_ts_info_hwts,
 };
 
 static int kvaser_pciefd_setup_can_ctrls(struct kvaser_pciefd *pcie)
···
 
 		can = netdev_priv(netdev);
 		netdev->netdev_ops = &kvaser_pciefd_netdev_ops;
+		netdev->ethtool_ops = &kvaser_pciefd_ethtool_ops;
 		can->reg_base = pcie->reg_base + KVASER_PCIEFD_KCAN0_BASE +
 				i * KVASER_PCIEFD_KCAN_BASE_OFFSET;