CONFIG_CLKSRC_MMIO (not configurable)

modulename: mmio.ko

configname: CONFIG_CLKSRC_MMIO

Linux Kernel Configuration
└─>Device Drivers
└─>Clock Source drivers
└─>CLKSRC_MMIO
In linux kernel since version 3 (release Date: 2011-07-21)  
source code:
drivers/clocksource/mmio.c