libphy: add phy_find_first function

Many drivers do this in them manually. Now they can use this function.

Signed-off-by: Jiri Pirko <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/phy/phy_device.c

···
 EXPORT_SYMBOL(phy_device_register);
 
 /**
+ * phy_find_first - finds the first PHY device on the bus
+ * @bus: the target MII bus
+ */
+struct phy_device *phy_find_first(struct mii_bus *bus)
+{
+	int addr;
+
+	for (addr = 0; addr < PHY_MAX_ADDR; addr++) {
+		if (bus->phy_map[addr])
+			return bus->phy_map[addr];
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(phy_find_first);
+
+/**
  * phy_prepare_link - prepares the PHY layer to monitor link status
  * @phydev: target phy_device struct
  * @handler: callback function for link status change notifications

include/linux/phy.h

···
 		u32 flags, phy_interface_t interface);
 struct phy_device * phy_attach(struct net_device *dev,
 		const char *bus_id, u32 flags, phy_interface_t interface);
+struct phy_device *phy_find_first(struct mii_bus *bus);
 int phy_connect_direct(struct net_device *dev, struct phy_device *phydev,
 		void (*handler)(struct net_device *), u32 flags,
 		phy_interface_t interface);