# led output register
led=0x90470000
red=13
blue=12

# select register, sets gpio or pwm mode
select=0x90470058
mode_gpio=0
mode_pwm=1

# pwm
pwm_ctrl=0x90458000

# pwm 5 is mapped to red (gpio 13)
red_pwm_hi=0x90458030
red_pwm_lo=0x90458034

# pwm 4 is mapped to blue (gpio 12)
blue_pwm_hi=0x90458028
blue_pwm_lo=0x9045802c

setreg()
{
	devmem $1 32 $2 > /dev/null
}

getreg()
{
	devmem $1
}

hex()
{
	printf "0x%08x" $1
}

select()
{
	pin=$1
	val=$2

	shift=$((2 * $pin))

	g=$(getreg $select)
	v=$(( ($g & ~(3 << $shift)) | ($val << $shift) ))
	h=$(hex $v)
	setreg $select $h
}

getreg $pwm_ctrl
setreg $pwm_ctrl 0x800000ff
getreg $pwm_ctrl

select $red $mode_pwm
select $blue $mode_pwm

# max
max=0x800003ff		# ~952Hz
val=0x3ff

while true; do
	echo -n 'Enter duty cycle 0-100 -> '
	read duty
	min=$(($val * $duty / 100))

	echo $duty
	setreg $blue_pwm_lo $(hex $(($min)))
	setreg $blue_pwm_hi $max
	setreg $red_pwm_lo $val
	setreg $red_pwm_hi $max
done
	
#select $red $mode_gpio
#select $blue $mode_gpio