Understanding of how to multiplex pins on Beaglebone black

I want to know how to pin multiplex pins in initial phase of boot i.e is in spl(MLO). What I am trying to do is change the default pin configuration to gpio one, so that I can see high or low on the pin.

On P8 header I tried to change the mode 0 from default ‘TIMER4’ to gpio2[2] i.e mode 7. So I did this

static struct module_pin_mux gpio2_2_pin_mux[] = {
{OFFSET(gpmc_wen), (MODE(7) | PULLUDEN)},
and called this function

in board/ti/am335x/mux.c

I didn’t saw any voltage on 7th pin of P8 header?

What is the correct way to do this?
Attached the two file I am referring for this. The .c file contain some small changes at line 358 that I tried with.

mux_am43xx.h (3.53 KB)

mux.c (15.2 KB)