Firmware for RaspberryPi that turns it into a GPIO controller?

Question

Raspberry Pi

Is there a firmware that turns the RaspberryPi into a GPIO IN/OUT controller?

Answer 1

There, classic Linux also allows you to control GPIO. Or are you looking for something special?
At the lowest level, something like this . But there are normal higher level interfaces

Answer 2

WiringPi won't work?