CONFIG_MDIO_I2C (not configurable)

modulename: mdio-i2c.ko

configname: CONFIG_MDIO_I2C

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>MDIO bus device drivers
└─>MDIO_I2C
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Support I2C based PHYs. This provides a MDIO bus bridged
to I2C to allow PHYs connected in I2C mode to be accessed
using the existing infrastructure.

This is library mode.

source code: