CONFIG_REBOOT_MODE (not configurable)

modulename: reboot-mode.ko

configname: CONFIG_REBOOT_MODE

Linux Kernel Configuration
└─>Device Drivers
└─>Board level reset or power off
└─>REBOOT_MODE
In linux kernel since version 4.1 (release Date: 2015-06-21)  
source code:
drivers/power/reset/reboot-mode.c