CONFIG_OF (not configurable)

modulename: of.ko

and/or

of_regulator.ko

and/or

prom.ko

and/or

devicetree.ko

and/or

devtree.ko

configname: CONFIG_OF

Linux Kernel Configuration
└─>Device Drivers
└─>OF
In linux kernel since version 2.6.23 (release Date: 2007-10-09)  
source code:
drivers/pci/of.c