net: dsa: mv88e6xxx: change serdes lane parameter type from u8 type to int

Returning 0 is no more an error case with MV88E6393 family
which has serdes lane numbers 0, 9 or 10.
So with this change .serdes_get_lane will return lane number
or -errno (-ENODEV or -EOPNOTSUPP).

Signed-off-by: Pavana Sharma <pavana.sharma@digi.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Marek BehĂșn <kabel@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 903d619..cd0c8d1 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -485,12 +485,12 @@ static int mv88e6xxx_serdes_pcs_get_state(struct dsa_switch *ds, int port,
 					  struct phylink_link_state *state)
 {
 	struct mv88e6xxx_chip *chip = ds->priv;
-	u8 lane;
+	int lane;
 	int err;
 
 	mv88e6xxx_reg_lock(chip);
 	lane = mv88e6xxx_serdes_get_lane(chip, port);
-	if (lane && chip->info->ops->serdes_pcs_get_state)
+	if (lane >= 0 && chip->info->ops->serdes_pcs_get_state)
 		err = chip->info->ops->serdes_pcs_get_state(chip, port, lane,
 							    state);
 	else
@@ -506,11 +506,11 @@ static int mv88e6xxx_serdes_pcs_config(struct mv88e6xxx_chip *chip, int port,
 				       const unsigned long *advertise)
 {
 	const struct mv88e6xxx_ops *ops = chip->info->ops;
-	u8 lane;
+	int lane;
 
 	if (ops->serdes_pcs_config) {
 		lane = mv88e6xxx_serdes_get_lane(chip, port);
-		if (lane)
+		if (lane >= 0)
 			return ops->serdes_pcs_config(chip, port, lane, mode,
 						      interface, advertise);
 	}
@@ -523,14 +523,14 @@ static void mv88e6xxx_serdes_pcs_an_restart(struct dsa_switch *ds, int port)
 	struct mv88e6xxx_chip *chip = ds->priv;
 	const struct mv88e6xxx_ops *ops;
 	int err = 0;
-	u8 lane;
+	int lane;
 
 	ops = chip->info->ops;
 
 	if (ops->serdes_pcs_an_restart) {
 		mv88e6xxx_reg_lock(chip);
 		lane = mv88e6xxx_serdes_get_lane(chip, port);
-		if (lane)
+		if (lane >= 0)
 			err = ops->serdes_pcs_an_restart(chip, port, lane);
 		mv88e6xxx_reg_unlock(chip);
 
@@ -544,11 +544,11 @@ static int mv88e6xxx_serdes_pcs_link_up(struct mv88e6xxx_chip *chip, int port,
 					int speed, int duplex)
 {
 	const struct mv88e6xxx_ops *ops = chip->info->ops;
-	u8 lane;
+	int lane;
 
 	if (!phylink_autoneg_inband(mode) && ops->serdes_pcs_link_up) {
 		lane = mv88e6xxx_serdes_get_lane(chip, port);
-		if (lane)
+		if (lane >= 0)
 			return ops->serdes_pcs_link_up(chip, port, lane,
 						       speed, duplex);
 	}
@@ -2460,11 +2460,11 @@ static irqreturn_t mv88e6xxx_serdes_irq_thread_fn(int irq, void *dev_id)
 	struct mv88e6xxx_chip *chip = mvp->chip;
 	irqreturn_t ret = IRQ_NONE;
 	int port = mvp->port;
-	u8 lane;
+	int lane;
 
 	mv88e6xxx_reg_lock(chip);
 	lane = mv88e6xxx_serdes_get_lane(chip, port);
-	if (lane)
+	if (lane >= 0)
 		ret = mv88e6xxx_serdes_irq_status(chip, port, lane);
 	mv88e6xxx_reg_unlock(chip);
 
@@ -2472,7 +2472,7 @@ static irqreturn_t mv88e6xxx_serdes_irq_thread_fn(int irq, void *dev_id)
 }
 
 static int mv88e6xxx_serdes_irq_request(struct mv88e6xxx_chip *chip, int port,
-					u8 lane)
+					int lane)
 {
 	struct mv88e6xxx_port *dev_id = &chip->ports[port];
 	unsigned int irq;
@@ -2501,7 +2501,7 @@ static int mv88e6xxx_serdes_irq_request(struct mv88e6xxx_chip *chip, int port,
 }
 
 static int mv88e6xxx_serdes_irq_free(struct mv88e6xxx_chip *chip, int port,
-				     u8 lane)
+				     int lane)
 {
 	struct mv88e6xxx_port *dev_id = &chip->ports[port];
 	unsigned int irq = dev_id->serdes_irq;
@@ -2526,11 +2526,11 @@ static int mv88e6xxx_serdes_irq_free(struct mv88e6xxx_chip *chip, int port,
 static int mv88e6xxx_serdes_power(struct mv88e6xxx_chip *chip, int port,
 				  bool on)
 {
-	u8 lane;
+	int lane;
 	int err;
 
 	lane = mv88e6xxx_serdes_get_lane(chip, port);
-	if (!lane)
+	if (lane < 0)
 		return 0;
 
 	if (on) {