can: bittiming: mark function arguments and local variables as const

This patch marks the arguments of some functions as well as some local
variables as constant.

Link: https://lore.kernel.org/all/20220124215642.3474154-7-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/dev/bittiming.c

@@ -24,7 +24,7 @@
  */
 static int
 can_update_sample_point(const struct can_bittiming_const *btc,
-			unsigned int sample_point_nominal, unsigned int tseg,
+			const unsigned int sample_point_nominal, const unsigned int tseg,
 			unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
 			unsigned int *sample_point_error_ptr)
 {
@@ -63,7 +63,7 @@ can_update_sample_point(const struct can_bittiming_const *btc,
 	return best_sample_point;
 }
 
-int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
+int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 		       const struct can_bittiming_const *btc)
 {
 	struct can_priv *priv = netdev_priv(dev);
@@ -208,10 +208,10 @@ void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
  * prescaler value brp. You can find more information in the header
  * file linux/can/netlink.h.
  */
-static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt,
+static int can_fixup_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 			       const struct can_bittiming_const *btc)
 {
-	struct can_priv *priv = netdev_priv(dev);
+	const struct can_priv *priv = netdev_priv(dev);
 	unsigned int tseg1, alltseg;
 	u64 brp64;
 
@@ -244,7 +244,7 @@ static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt,
 
 /* Checks the validity of predefined bitrate settings */
 static int
-can_validate_bitrate(struct net_device *dev, struct can_bittiming *bt,
+can_validate_bitrate(const struct net_device *dev, const struct can_bittiming *bt,
 		     const u32 *bitrate_const,
 		     const unsigned int bitrate_const_cnt)
 {
@@ -258,7 +258,7 @@ can_validate_bitrate(struct net_device *dev, struct can_bittiming *bt,
 	return -EINVAL;
 }
 
-int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,
+int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 		      const struct can_bittiming_const *btc,
 		      const u32 *bitrate_const,
 		      const unsigned int bitrate_const_cnt)

include/linux/can/bittiming.h

@@ -113,7 +113,7 @@ struct can_tdc_const {
 };
 
 #ifdef CONFIG_CAN_CALC_BITTIMING
-int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
+int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 		       const struct can_bittiming_const *btc);
 
 void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
@@ -121,7 +121,7 @@ void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 		   u32 *ctrlmode, u32 ctrlmode_supported);
 #else /* !CONFIG_CAN_CALC_BITTIMING */
 static inline int
-can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
+can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 		   const struct can_bittiming_const *btc)
 {
 	netdev_err(dev, "bit-timing calculation not available\n");
@@ -136,7 +136,7 @@ can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 }
 #endif /* CONFIG_CAN_CALC_BITTIMING */
 
-int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,
+int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 		      const struct can_bittiming_const *btc,
 		      const u32 *bitrate_const,
 		      const unsigned int bitrate_const_cnt);