configuring gpio pins within a driver module

[hjoe]

I found the CAN device driver sources in  

sun7i_can.c - CAN bus controller driver for sun7i

 

to configure the gpio pins for the special case of acting as TX and RX for CAN, the following function calls are used:

sw_gpio_setcfg(GPIOA(16), 3); 

I try to use this code to implement the can4linux module an a BananaPi M2-Berry using Armbian stretch but are not able to find any prototype of such a function sw_gpio_setcfg(); nor the definitions of the gpio ports like GPIOA.

What ist the correct way of accessing the gpio ports from within the kernel?

Thanks for helping.