Avionic Design N-bit GPIO expander

modulename: gpio-adnp.ko

configname: CONFIG_GPIO_ADNP

Linux Kernel Configuration
└─>Device Drivers
└─>GPIO Support
└─>I2C GPIO expanders
└─>Avionic Design N-bit GPIO expander
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This option enables support for N GPIOs found on Avionic Design
I2C GPIO expanders. The register space will be extended by powers
of two, so the controller will need to accommodate for that. For
example: if a controller provides 48 pins, 6 registers will be
enough to represent all pins, but the driver will assume a
register layout for 64 pins (8 registers).

source code: