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 / MCP23S18 /
MCP23008 / MCP23017 / MCP23018 I/O expanders.
This provides a GPIO interface supporting inputs and outputs and a
corresponding interrupt-controller.

source code: