CONFIG_OF_GPIO (not configurable)

modulename: gpiolib-of.ko

configname: CONFIG_OF_GPIO

Linux Kernel Configuration
└─>Device Drivers
└─>GPIO Support
└─>Device Tree and Open Firmware support
└─>OF_GPIO
In linux kernel since version 2.6.26 (release Date: 2008-07-13)  
source code:
drivers/gpio/gpiolib-of.c

is selected by
CONFIG_MDIO_BUS_MUX_GPIO