net: dsa: microchip: Add property to disable reference clock

Add a new microchip,synclko-disable property which can be specified
to disable the reference clock output from the device if not required
by the board design.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/microchip/ksz9477.c

@@ -222,9 +222,12 @@ static int ksz9477_reset_switch(struct ksz_device *dev)
 			   (BROADCAST_STORM_VALUE *
 			   BROADCAST_STORM_PROT_RATE) / 100);
 
-	if (dev->synclko_125)
-		ksz_write8(dev, REG_SW_GLOBAL_OUTPUT_CTRL__1,
-			   SW_ENABLE_REFCLKO | SW_REFCLKO_IS_125MHZ);
+	data8 = SW_ENABLE_REFCLKO;
+	if (dev->synclko_disable)
+		data8 = 0;
+	else if (dev->synclko_125)
+		data8 = SW_ENABLE_REFCLKO | SW_REFCLKO_IS_125MHZ;
+	ksz_write8(dev, REG_SW_GLOBAL_OUTPUT_CTRL__1, data8);
 
 	return 0;
 }

drivers/net/dsa/microchip/ksz_common.c

@@ -434,6 +434,12 @@ int ksz_switch_register(struct ksz_device *dev,
 			}
 		dev->synclko_125 = of_property_read_bool(dev->dev->of_node,
 							 "microchip,synclko-125");
+		dev->synclko_disable = of_property_read_bool(dev->dev->of_node,
+							     "microchip,synclko-disable");
+		if (dev->synclko_125 && dev->synclko_disable) {
+			dev_err(dev->dev, "inconsistent synclko settings\n");
+			return -EINVAL;
+		}
 	}
 
 	ret = dsa_register_switch(dev->ds);

drivers/net/dsa/microchip/ksz_common.h

@@ -75,6 +75,7 @@ struct ksz_device {
 	u32 regs_size;
 	bool phy_errata_9477;
 	bool synclko_125;
+	bool synclko_disable;
 
 	struct vlan_table *vlan_cache;