#!/bin/sh

RESET_PIN=90
BOOT0_PIN=67

SYSFSPATH=/sys/class/gpio

die() {
	echo "$*" 1>&2
	exit 1
}

usage() {
	echo "Usage: $0 [--reset|--dfu|--disable|--flash <firmware>]"
	echo "  --reset            - resets the Cortex M0"
	echo "  --dfu              - enables DFU loader"
	echo "  --disable          - keep Cortex M0 in reset"
	echo "  --flash <firmware> - flash the given firmware"

	exit 1
}

gpiosetup() {
	for PIN in $RESET_PIN $BOOT0_PIN 
	do
		if [ ! -d ${SYSFSPATH}/gpio${PIN} ] ; then
			echo $PIN > ${SYSFSPATH}/export
			echo out > ${SYSFSPATH}/gpio${PIN}/direction
		fi
	done
}

reset_stm32() {
	echo 0 >  ${SYSFSPATH}/gpio${RESET_PIN}/value
	echo 0 >  ${SYSFSPATH}/gpio${BOOT0_PIN}/value
	sleep 0.1
	echo 1 >  ${SYSFSPATH}/gpio${RESET_PIN}/value
}

enable_dfu() {
	gpiosetup
	echo 0 >  ${SYSFSPATH}/gpio${RESET_PIN}/value
	echo 1 >  ${SYSFSPATH}/gpio${BOOT0_PIN}/value
	sleep 0.1
	echo 1 >  ${SYSFSPATH}/gpio${RESET_PIN}/value
}

case "$1" in
--reset) echo "reseting Cortex M0"
	gpiosetup
	reset_stm32
    ;;
--dfu) echo "enabling DFU loader"
	gpiosetup
	enable_dfu
    ;;
--disable) echo "disabling Cortex M0"
	gpiosetup
	echo 0 >  ${SYSFSPATH}/gpio${RESET_PIN}/value
    ;;
--flash) 
	[ $# -eq 2 ] || usage
	command -v dfu-util >/dev/null 2>&1 || die "dfu-util needed but not found"
	[ -f "$2" ] || die "flash file does not exist"
	echo "flashing Cortex M0"
	gpiosetup
	enable_dfu
	echo waiting for DFU loader
	if [ command -v lsusb >/dev/null 2>&1 ]; then
		while ! lsusb -d 0483:df11 > /dev/null
		do
			sleep .1
			echo -n .
		done
		echo -e "\nfound"
	else
		sleep 5
	fi
	dfu-util -d 0483:df11 -a 0 -s 0x08000000 -D $2
	reset_stm32
    ;;
--*) usage
    ;;
*) usage 
    ;;
esac

exit 0