ADC Ladder Buttons

modulename: adc-keys.ko

configname: CONFIG_KEYBOARD_ADC

Linux Kernel Configuration
└─>Device Drivers
└─>Input device support
└─>Keyboards
└─>ADC Ladder Buttons
In linux kernel since version 4.1 (release Date: 2015-06-21)  
This driver implements support for buttons connected
to an ADC using a resistor ladder.

Say Y here if your device has such buttons connected to an ADC. Your
board-specific setup logic must also provide a configuration data
for mapping voltages to buttons.

To compile this driver as a module, choose M here: the
module will be called adc_keys.

source code: