net: dsa: microchip: Support optional 125MHz SYNCLKO output

The KSZ9477 series chips have a SYNCLKO pin which by default outputs a
25MHz clock, but some board setups require a 125MHz clock instead. Added
a microchip,synclko-125 device tree property to allow indicating a
125MHz clock output is required.

Signed-off-by: Robert Hancock <hancock@sedsystems.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/ksz.txt

@@ -16,6 +16,8 @@ Required properties:
 Optional properties:
 
 - reset-gpios		: Should be a gpio specifier for a reset line
+- microchip,synclko-125 : Set if the output SYNCLKO frequency should be set to
+			  125MHz instead of 25MHz.
 
 See Documentation/devicetree/bindings/net/dsa/dsa.txt for a list of additional
 required and optional properties.

drivers/net/dsa/microchip/ksz9477.c

@@ -258,6 +258,10 @@ static int ksz9477_reset_switch(struct ksz_device *dev)
 	data16 |= (BROADCAST_STORM_VALUE * BROADCAST_STORM_PROT_RATE) / 100;
 	ksz_write16(dev, REG_SW_MAC_CTRL_2, data16);
 
+	if (dev->synclko_125)
+		ksz_write8(dev, REG_SW_GLOBAL_OUTPUT_CTRL__1,
+			   SW_ENABLE_REFCLKO | SW_REFCLKO_IS_125MHZ);
+
 	return 0;
 }
 

drivers/net/dsa/microchip/ksz_common.c

@@ -460,6 +460,8 @@ int ksz_switch_register(struct ksz_device *dev,
 		ret = of_get_phy_mode(dev->dev->of_node);
 		if (ret >= 0)
 			dev->interface = ret;
+		dev->synclko_125 = of_property_read_bool(dev->dev->of_node,
+							 "microchip,synclko-125");
 	}
 
 	ret = dsa_register_switch(dev->ds);

drivers/net/dsa/microchip/ksz_priv.h

@@ -78,6 +78,7 @@ struct ksz_device {
 	phy_interface_t interface;
 	u32 regs_size;
 	bool phy_errata_9477;
+	bool synclko_125;
 
 	struct vlan_table *vlan_cache;