An example driver for accessing GPIO pins as inputs and outputs without using the device tree.
This example can be compiled and run on a Raspberry Pi. I don't think it will work on other plattforms (other ARM based boards or x86).
- checking the GPIO number on pinout.xyz
- GPIO pins are organized in gpiochips
- list all gpiochips:
pi@raspberrypi:~ $ gpiodetect gpiochip0 [pinctrl-bcm2835] (54 lines) gpiochip1 [raspberrypi-exp-gpio] (8 lines) - find gpiochips in sysfs
ls /sys/class/gpio/ export gpiochip0 gpiochip504 unexport - Offsets are numbers before gpiochip
- Find out which is the right one
cat /sys/class/gpiochip0/label pinctrl-bcm2835 - So, we have to use Offset 0