Bitbanged MDIO buses

modulename: mdio-bitbang.ko

configname: CONFIG_MDIO_BITBANG

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>MDIO bus device drivers
└─>Bitbanged MDIO buses
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
This module implements the MDIO bus protocol in software,
for use by low level drivers that export the ability to
drive the relevant pins.

If in doubt, say N.

source code: