What:		/sys/bus/mdio_bus/devices/.../phy_id
Date:		November 2012
KernelVersion:	3.8
Contact:	netdev@vger.kernel.org
Description:
		This attribute contains the 32-bit PHY Identifier as reported
		by the device during bus enumeration, encoded in hexadecimal.
		This ID is used to match the device with the appropriate
		driver.
