GPIO Support

modulename: ext-gpio.ko

and/or

gpiolib.ko

configname: CONFIG_GPIOLIB

Linux Kernel Configuration
└─>Device Drivers
└─>GPIO Support
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
This enables GPIO support through the generic GPIO library.
You only need to enable this, if you also want to enable
one or more of the GPIO expansion card drivers below.

If unsure, say N.

source code:
/arch/blackfin/mach-bf538/ext-gpio.c