Richtek RT4831 four channel WLED and Display Bias Voltage

modulename: rt4831.ko

configname: CONFIG_MFD_RT4831

Linux Kernel Configuration
└─>Device Drivers
└─>Multifunction device drivers
└─>Richtek RT4831 four channel WLED and Display Bias Voltage
In linux kernel since version 5.2 (release Date: 2019-07-07)  
This enables support for the Richtek RT4831 that includes 4 channel
WLED driving and Display Bias Voltage. It's commonly used to provide
power to the LCD display and LCD backlight.

source code: