#!/bin/sh

BASE_PATH=/sys/class
GPIO_PATH="$BASE_PATH"/gpio
PWM_PATH="$BASE_PATH"/pwm/pwmchip0

# GPIO pins
CPU_FAN=12
HDD_FAN=13

# Values
LOW=0
HIGH=1

export_pin() {
    if [ ! -e $GPIO_PATH/gpio"$1" ]; then
        echo "$1" >$GPIO_PATH/export
    fi
}

unexport_pin() {
    if [ -e $GPIO_PATH/gpio"$1" ]; then
        echo "$1" >$GPIO_PATH/unexport
    fi
}

set_gpio() {
    export_pin "$1"
    echo "out" >$GPIO_PATH/gpio"$1"/direction
    echo "$2" >$GPIO_PATH/gpio"$1"/value
    if [ "$3" = "clean" ]; then
        unexport_pin "$1"
    fi
}

enable_pwm_channel() {
    echo "$1" >$PWM_PATH/export
    echo 40000 >$PWM_PATH/pwm"$1"/period
    echo 30000 >$PWM_PATH/pwm"$1"/duty_cycle
    echo 1 >$PWM_PATH/pwm"$1"/enable
}

set_pwm() {
    if [ "$1" = "clean" ]; then
        echo 1 >$PWM_PATH/unexport
    else
        enable_pwm_channel 1
    fi
}

turn_on() {
    set_gpio $CPU_FAN $HIGH
    set_gpio $HDD_FAN $HIGH
    set_pwm
}

turn_off() {
    set_gpio $CPU_FAN $LOW clean
    set_gpio $HDD_FAN $LOW clean
    set_pwm clean
}

trap turn_off INT

if [ "$1" = "on" ]; then
    turn_on
else
    turn_off
fi

exit 0