CONFIG_OF_MDIO (not configurable)

modulename: of_mdio.ko

configname: CONFIG_OF_MDIO

Linux Kernel Configuration
└─>Device Drivers
└─>Device Tree and Open Firmware support
└─>OF_MDIO
In linux kernel since version 2.6.31 (release Date: 2009-09-09)  
OpenFirmware MDIO bus (Ethernet PHY) accessors

source code: