net: of_mdio: parse "max-speed" property to set PHY supported features

The "max-speed" property is defined per the ePAPR specification to
express the maximum speed a PHY supports. Use that property, if present
to set the phydev->supported features which properly restricts the PHY
within the range of defined speeds.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/of/of_mdio.c

@@ -22,12 +22,30 @@
 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
 MODULE_LICENSE("GPL");
 
+static void of_set_phy_supported(struct phy_device *phydev, u32 max_speed)
+{
+	phydev->supported |= PHY_DEFAULT_FEATURES;
+
+	switch (max_speed) {
+	default:
+		return;
+
+	case SPEED_1000:
+		phydev->supported |= PHY_1000BT_FEATURES;
+	case SPEED_100:
+		phydev->supported |= PHY_100BT_FEATURES;
+	case SPEED_10:
+		phydev->supported |= PHY_10BT_FEATURES;
+	}
+}
+
 static int of_mdiobus_register_phy(struct mii_bus *mdio, struct device_node *child,
 				   u32 addr)
 {
 	struct phy_device *phy;
 	bool is_c45;
 	int rc, prev_irq;
+	u32 max_speed = 0;
 
 	is_c45 = of_device_is_compatible(child,
 					 "ethernet-phy-ieee802.3-c45");
@@ -58,8 +76,13 @@ static int of_mdiobus_register_phy(struct mii_bus *mdio, struct device_node *chi
 		return 1;
 	}
 
+	/* Set phydev->supported based on the "max-speed" property
+	 * if present */
+	if (!of_property_read_u32(child, "max-speed", &max_speed))
+		of_set_phy_supported(phy, max_speed);
+
 	dev_dbg(&mdio->dev, "registered phy %s at address %i\n",
-		 child->name, addr);
+		child->name, addr);
 
 	return 0;
 }