sdswap

#!/bin/bash

getdevice() {
	#based on https://unix.stackexchange.com/questions/136781/how-to-get-device-filename-from-lsusb-output-or-by-device-path
	local idV=${1%:*}
	local idP=${1#*:}
	for path in $(dirname $(find -L /sys/bus/usb/devices/ -maxdepth 2 -name 'idVendor')); do
		if grep -q "$idV" "$path/idVendor" && grep -q "$idP" "$path/idProduct"; then
			echo "$path"
		fi
	done
}

run_root() {
	if [ "$(id -u)" != "0" ]; then
		sudo "$@"
	else
		"$@"
	fi
}

get_blockdev() {
	# This can match twice so add `-m 1` to grep to only match once
	local SYSFS_BLOCK_RELATIVE
	SYSFS_BLOCK_RELATIVE=$(realpath --relative-base="$1" /sys/block/* | grep -vm 1 "^/") || return $?
	basename "$SYSFS_BLOCK_RELATIVE" 2>/dev/null
}

print_help() {
	cat << EOF
To switch the SD card to USB run:
$0 1
To switch the SD card to SBC run:
$0 0
To print the block dev run:
$0 p

If you have multiple devices run either of the above.
Then run with the last param the same as above:
$0 \$(Your USB number) 0

NOTE:
When printing the block device the script waits until the device exists

Examples:
# $0 0
Uisng device /sys/bus/usb/devices/3-4

# $0 0
Uisng device /sys/bus/usb/devices/3-4
Already off.

# $0 p
/dev/sda

# $0 0
Multiple devices found! Pass a usb number as param 1...
Usb num: 3-4
Usb num: 3-1

# $0 3-1 0
Uisng device /sys/bus/usb/devices/3-1
EOF
	exit 1
}

get_devices() {
	local DEVICES
	DEVICES=$(getdevice 0bda:0316)
	if echo "$DEVICES" | grep -q " "; then
		if [ $# -eq 2 ]; then
			for dev in $DEVICES; do
				if echo "$dev" | grep -q "$1"; then
					export DEVICE="$dev"
				fi
			done
			if [ -z "$DEVICE" ]; then
				echo "Device not found. Pass a usb number as param 1..."
				for dev in $DEVICES; do
					echo "Usb num:" "$(basename "$dev")"
				done
				exit 1
			fi
		else
			echo "Multiple devices found! Pass a usb number as param 1..."
			for dev in $DEVICES; do
				echo "Usb num:" "$(basename "$dev")"
			done
			exit 1
		fi
	else
			export DEVICE=$DEVICES
	fi

	if [ -z "$DEVICES" ]; then
		echo "No devices found ;("
		exit 1
	fi
}

setup_pwrctl() {
	echo 0 | run_root tee "$1"/power/autosuspend_delay_ms &>/dev/null
	echo auto | run_root tee "$1"/power/control &>/dev/null
}

turn_off() {
	echo "$1" | run_root tee /sys/bus/usb/drivers/usb/unbind &>/dev/null || echo "Already off."
}

turn_on() {
	echo "$1" | run_root tee /sys/bus/usb/drivers/usb/bind &>/dev/null || echo "Already on"
}

print_info() {
	echo "Uisng device" "$1"

	local DEVNAME
	DEVNAME=$(get_blockdev "$1")
	if [[ ${DEVNAME} ]]; then
		echo "With devpath of /dev/""$DEVNAME"
	fi
}

print_dev() {
	local DEVNAME
	while true; do
		DEVNAME=$(get_blockdev "$1") && break
	done
	echo /dev/"$DEVNAME"
	exit 0
}

main() {
	local OPERATION
	local USB_NUM

	OPERATION=$(eval echo "\${$#}")

	case "$OPERATION" in
		0|1|p)
			get_devices "$@";;
		*)
			print_help;;
	esac

	if [ "$OPERATION" == 'p' ]; then
		print_dev "$DEVICE"
	fi

	print_info "$DEVICE"
	USB_NUM=$(basename "$DEVICE")

	setup_pwrctl "$DEVICE"

	if [ "$OPERATION" == '1' ]; then
		turn_on "$USB_NUM"
	elif [ "$OPERATION" == '0' ]; then
		turn_off "$USB_NUM"
	fi
}

main "$@"