looks like gpio needs to be created
/sys/kernel/debug# cat gpio
gpiochip0: GPIOs 0-31, parent: platform/18040000.gpio, 18040000.gpio:
gpio-1 ( |gl-ar750s:green:powe) out lo
gpio-2 ( |reset ) in hi
gpio-8 ( |mode ) in hi
gpio-19 ( |gl-ar750s:green:wlan) out hi
gpio-20 ( |gl-ar750s:green:wlan) out hi

and then script created in rc.common. to enable it. I can understand. itś figuring it out without doing something bad since I´ve never done this

below is output for gli firmware
gpiochip0: GPIOs 0-31, parent: platform/ath79-gpio, ath79-gpio:
gpio-1 ( |gl-ar750s:white:powe) out lo
gpio-2 ( |reset ) in hi
gpio-5 ( |sda ) in hi
gpio-7 ( |gl-ar750s:white:usbp) out hi
gpio-8 ( |right ) in lo
gpio-19 ( |gl-ar750s:white:wlan) out lo
gpio-20 ( |gl-ar750s:white:wlan) out hi
gpio-21 ( |scl ) in hi