#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2023 JELOS (https://github.com/JustEnoughLinuxOS)

for mod in usb_f_ecm ; do
	modprobe -q ${mod}
done

mkdir -p /storage/.cache/usbgadget

if [ ! -f /storage/.cache/usbgadget/ip_address.conf ] ; then
	echo "10.1.1.2" > /storage/.cache/usbgadget/ip_address.conf
fi

if [ ! -f /storage/.cache/usbgadget/udhcpd.conf ] ; then
	echo -e "interface usb0\nstart 10.1.1.1\nend 10.1.1.1\nopt subnet 255.255.255.0\nopt lease 86400\nmax_leases 1\nlease_file /dev/null\nremaining no" >> /storage/.cache/usbgadget/udhcpd.conf
fi

VENDOR=JELOS
MACHINE=$(cat /etc/hostname)
UDC_NAME=$(ls -1 /sys/class/udc |head -n1)
IP=$(cat /storage/.cache/usbgadget/ip_address.conf)

usb_disable() {
	echo "" > /sys/kernel/config/usb_gadget/gadget/UDC
	echo "USB_MODE=disabled" > /storage/.cache/usbgadget/usbgadget.conf
}

usb_start() {
	if [ -r /storage/.cache/usbgadget/usbgadget.conf ] ; then
		. /storage/.cache/usbgadget/usbgadget.conf
	fi
	
	if [ "$1" ] ; then
		USB_MODE=$1
	fi

	cd /sys/kernel/config/usb_gadget
	mkdir gadget \
		gadget/strings/0x409 \
		gadget/configs/c.1 \
		gadget/configs/c.1/strings/0x409 \
		gadget/functions/ecm.usb0
        
	echo $VENDOR > gadget/strings/0x409/manufacturer
	echo $MACHINE > gadget/strings/0x409/product

	if [ "${USB_MODE}" = cdc ] ; then
		echo cdc > gadget/configs/c.1/strings/0x409/configuration
		echo 0x1d6b > gadget/idVendor	
		echo 0x104 > gadget/idProduct
		ln -s gadget/functions/ecm.usb0 gadget/configs/c.1
		echo "${UDC_NAME}" > /sys/kernel/config/usb_gadget/gadget/UDC
		ifconfig usb0 $IP up
		/usr/sbin/udhcpd -S /storage/.cache/usbgadget/udhcpd.conf
	fi

	echo "USB_MODE=$(cat gadget/configs/c.1/strings/0x409/configuration)" > /storage/.cache/usbgadget/usbgadget.conf
}

usb_stop() {
	(
		cd /sys/kernel/config/usb_gadget

		usb_disable

		rm -f gadget/configs/c.1/ecm.usb0 \

		rmdir gadget/configs/c.1/strings/0x409 \
			gadget/configs/c.1 \
			gadget/functions/ecm.usb0 \
			gadget/strings/0x409 \
			gadget

		killall udhcpd
	) >/dev/null 2>&1
}

case "$1" in
	start)
		usb_start $2
		;;
	stop)
		usb_stop
		;;
	restart)
		usb_stop
		usb_start $2
		;;
	*)
		echo "Usage: usbgadget [start|stop|restart]"
		;;
esac