Microchip MCP23xxx I/O expander

modulename: pinctrl-mcp23s08.ko

configname: CONFIG_PINCTRL_MCP23S08

Linux Kernel Configuration
└─>Device Drivers
└─>Pin controllers
└─>Microchip MCP23xxx I/O expander
In linux kernel since version 4.2 (release Date: 2015-08-30)  
SPI/I2C driver for Microchip MCP23S08/MCP23S17/MCP23008/MCP23017
I/O expanders.
This provides a GPIO interface supporting inputs and outputs.
The I2C versions of the chips can be used as interrupt-controller.

source code: