[seL4] Camkes and GPIO

Hello all, I am trying to implement a simple demo on sel4 using camkes. I need to add some external hardware like sensors to my demo. For this purpose I need GPIO programming. Could you please point me to some example GPIO components? Should I add hardware component? or just use <platsupport.GPIO.h> to write signal on pins on source files? Thank you for your time and consideration, Parveneh.