can: kvaser_usb: Add helper functions to convert device timestamp into ktime

Add helper function kvaser_usb_ticks_to_ktime() that converts from
device ticks to ktime.
And kvaser_usb_timestamp{48,64}_to_ktime() that converts from device
48-bit or 64-bit timestamp, to ktime.
Signed-off-by: Jimmy Assarsson <extja@kvaser.com>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/20240701154936.92633-2-extja@kvaser.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

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

@@ -22,6 +22,8 @@
  */
 
 #include <linux/completion.h>
+#include <linux/ktime.h>
+#include <linux/math64.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <linux/usb.h>
@@ -216,4 +218,26 @@ int kvaser_usb_can_rx_over_error(struct net_device *netdev);
 
 extern const struct can_bittiming_const kvaser_usb_flexc_bittiming_const;
 
+static inline ktime_t kvaser_usb_ticks_to_ktime(const struct kvaser_usb_dev_cfg *cfg,
+						u64 ticks)
+{
+	return ns_to_ktime(div_u64(ticks * 1000, cfg->timestamp_freq));
+}
+
+static inline ktime_t kvaser_usb_timestamp48_to_ktime(const struct kvaser_usb_dev_cfg *cfg,
+						      const __le16 *timestamp)
+{
+	u64 ticks = le16_to_cpu(timestamp[0]) |
+		    (u64)(le16_to_cpu(timestamp[1])) << 16 |
+		    (u64)(le16_to_cpu(timestamp[2])) << 32;
+
+	return kvaser_usb_ticks_to_ktime(cfg, ticks);
+}
+
+static inline ktime_t kvaser_usb_timestamp64_to_ktime(const struct kvaser_usb_dev_cfg *cfg,
+						      __le64 timestamp)
+{
+	return kvaser_usb_ticks_to_ktime(cfg, le64_to_cpu(timestamp));
+}
+
 #endif /* KVASER_USB_H */

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

@@ -526,19 +526,17 @@ static ktime_t
 kvaser_usb_hydra_ktime_from_rx_cmd(const struct kvaser_usb_dev_cfg *cfg,
 				   const struct kvaser_cmd *cmd)
 {
-	u64 ticks;
+	ktime_t hwtstamp = 0;
 
 	if (cmd->header.cmd_no == CMD_EXTENDED) {
 		struct kvaser_cmd_ext *cmd_ext = (struct kvaser_cmd_ext *)cmd;
 
-		ticks = le64_to_cpu(cmd_ext->rx_can.timestamp);
+		hwtstamp = kvaser_usb_timestamp64_to_ktime(cfg, cmd_ext->rx_can.timestamp);
 	} else {
-		ticks = le16_to_cpu(cmd->rx_can.timestamp[0]);
-		ticks += (u64)(le16_to_cpu(cmd->rx_can.timestamp[1])) << 16;
-		ticks += (u64)(le16_to_cpu(cmd->rx_can.timestamp[2])) << 32;
+		hwtstamp = kvaser_usb_timestamp48_to_ktime(cfg, cmd->rx_can.timestamp);
 	}
 
-	return ns_to_ktime(div_u64(ticks * 1000, cfg->timestamp_freq));
+	return hwtstamp;
 }
 
 static int kvaser_usb_hydra_send_simple_cmd(struct kvaser_usb *dev,