2024 0322 Linux keyboard LED control

#!/bin/sh
set -e

usage() {
	cat <<ENDUSAGE
$0: Send commands to Ploopy Trackball Nano via caps/scroll/num lock LED signals
Usage: $0 [scroll|dpi|reset|status|help]
ENDUSAGE
}

inputdev=/dev/input/by-id/usb-PloopyCo_Trackball_Nano-event-kbd
evntname="$(basename "$(readlink -f $inputdev)")"
# e.g. "event22"
sysclassdev=/sys/class/input/$evntname/device
sysinputname="$(echo $sysclassdev/*::capslock | sed 's|.*/\(input[0-9]*\).*|\1|')"
# e.g. "input1251"
caps=/sys/class/leds/$sysinputname::capslock/brightness
scroll=/sys/class/leds/$sysinputname::scrolllock/brightness
num=/sys/class/leds/$sysinputname::numlock/brightness

# We have to wait a very small amount of time or the LED changes don't seem to register
lkbmwait() {
	busybox sleep 0.002s
}

toggle_scroll() {
	echo 1 > "$num"
	lkbmwait
	echo 0 > "$num"
	lkbmwait
}
cycle_dpi() {
	echo 1 > "$caps"
	lkbmwait
	echo 0 > "$caps"
	lkbmwait
}
enter_reset() {
	echo 0 > "$caps"
	lkbmwait
	echo 1 > "$caps"
	lkbmwait
	echo 1 > "$num"
	lkbmwait
	echo 0 > "$num"
	lkbmwait
}
read_status() {
	c="$(cat "$caps")"
	s="$(cat "$scroll")"
	n="$(cat "$num")"
	echo "Input device path:          $inputdev"
	echo "Event device name:          $evntname"
	echo "/sys/class even device:     $sysclassdev"
	echo "/sys/class input device:    $sysinputname"
	echo "Capslock:      $c"
	echo "Scroll lock:   $s"
	echo "Numlock:       $n"
}

case "$1" in
	scroll) toggle_scroll;;
	dpi) cycle_dpi;;
	reset) enter_reset;;
	status) read_status;;
	*) usage;;
esac

#!/bin/sh
set -eu

usage() {
	cat <<ENDUSAGE
$0: Change capslock/compose/kana/numlock/scrolllock LEDs of attached keyboards.
Usage: $0 [KEYBOARD] [-A CAPSLOCK] [-o COMPOSE] [-k KANA] [-n NUMLOCK] [-s SCROLLLOCK] [-p PLOOPYMODE] [-t]

Arguments
KEYBOARD          A keyboard identifier.
                  This can be the shortest substring that identifies a board
		  based on files in /dev/input/by-id.
-A CAPSLOCK       Set the capslock LED
-o COMPOSE        Set the compose LED
-k KANA           Set the kana LED
-n NUMLOCK        Set the numlock LED
-s SCROLLLOCK     Set the scrolllock LED
-p PLOOPYMODE     Send an LKBM (LED Key BitMask) command to a Ploopy Nano
-l                List possible keyboard input devices;
                  any fragment of the filename can be used as a KEYBOARD argument
-t                Read the status of all LEDs of a board
                  (after any of the other changes are sent, if applicable)

Setting LEDs:
Setting any of the five LEDs accepts a 0 or 1 for off or on;
any other value toggles the current setting.

Ploopy LKBM commands:
These are commands defined in the lkbm Ploopy Nano firwmare.
<https://github.com/qmk/qmk_firmware/tree/master/keyboards/ploopyco/trackball_nano/keymaps/lkbm>
Available commands:
  scroll     Toggle between using the device as a regular trackball
             or using it as a 2D scrollball.
  dpi        Toggle between three DPI settings that control mouse speed.
  reset      Enter reset/bootloader mode that allows flashing firmware.
             (This doesn't seem to be working at the moment for some reason.)
ENDUSAGE
}

# A path in /dev/input/by-id that refers to the keyboard input event device.
# Because it is a keyboard, it should end in -event-kbd.
# It will be a symlink to a file in /dev/input/ called event.*
inputdev=
# The name (not full path) of the event.* file in /dev/input/
evntname=
# A path to /sys/class/input/$evntname/device.
# This will be a symlink to a folder like /sys/class/input/input.*
sysclassdev=
# The name (not full path) of the input.* file in /sys/class/input/
sysinputname=
# Once we have this, we can use paths like the following to set the capslock LED:
# /sys/class/leds/"$sysinputname"::capslock/brightness
ledcapslock=
ledcompose=
ledkana=
lednumlock=
ledscrolllock=

# Populate the global variables above
findkbd() {
	if test -e "$1" && test "${1#/}"; then
		# If it exists and is an absolute path, let the user pass whatever
		inputdev="$1"
	else
		# The links should be in /dev/input/by-id and end in -event-kbd
		# We can find any substring of the file so that
		# the user can just pass a product name in most cases.
		foundmulti=
		for f in /dev/input/by-id/*"$1"*; do
			# Ignore files that end in -ifXX-event-kbd like:
			# /dev/input/by-id/usb-ZSA_Technology_Labs_Voyager-if01-event-kbd
			# but find files that otherwise end in -event-kbd like:
			# /dev/input/by-id/usb-ZSA_Technology_Labs_Voyager-event-kbd
			case "$f" in
				*-if[0-9][0-9]-event-kbd)
					continue;;
				*-event-kbd)
					if test "$inputdev"; then
						echo "Found multiple devices that match string: $1"
						ls -1 /dev/input/by-id/*"$1"* | grep 'event-kbd$' | grep -v 'if[0-9][0-9]-event-kbd$'
						exit 1
					fi
					inputdev="$f"
					;;
			esac
		done
	fi
	if test -z "$inputdev"; then
		echo "Could not find a keyboard that matches string: $1"
		exit 1
	fi
	evntname="$(basename "$(readlink -f $inputdev)")"
	# e.g. "event22"
	sysclassdev=/sys/class/input/$evntname/device
	sysinputname="$(echo $sysclassdev/*::capslock | sed 's|.*/\(input[0-9]*\).*|\1|')"
	# e.g. "input1251"
	ledcapslock=/sys/class/leds/$sysinputname::capslock/brightness
	ledcompose=/sys/class/leds/$sysinputname::compose/brightness
	ledkana=/sys/class/leds/$sysinputname::kana/brightness
	ledscrolllock=/sys/class/leds/$sysinputname::scrolllock/brightness
	lednumlock=/sys/class/leds/$sysinputname::numlock/brightness
}

# We have to wait a very small amount of time or the LED changes don't seem to register
lkbmwait() {
	busybox sleep 0.02s
}

# Toggle between using the trackball as normal and using it as a 2D scrollball
lkbm_toggle_scroll() {
	echo 1 > "$lednumlock"
	lkbmwait
	echo 0 > "$lednumlock"
	lkbmwait
}

# Cycle between slow/mid/fast DPI settings for the tracball
lkbm_cycle_dpi() {
	echo 1 > "$ledcapslock"
	lkbmwait
	echo 0 > "$ledcapslock"
	lkbmwait
}

# Enter the bootloader where new firmware can be sent (not working?)
lkbm_enter_reset() {
	echo 0 > "$ledcapslock"
	lkbmwait
	echo 1 > "$ledcapslock"
	lkbmwait
	echo 1 > "$lednumlock"
	lkbmwait
	echo 0 > "$lednumlock"
	lkbmwait
}

# Read the status of the keyboard LEDs
read_status() {
	A="$(cat "$ledcapslock")"
	o="$(cat "$ledcompose")"
	k="$(cat "$ledkana")"
	s="$(cat "$ledscrolllock")"
	n="$(cat "$lednumlock")"
	echo "Input device path:          $inputdev"
	echo "Event device name:          $evntname"
	echo "/sys/class event device:    $sysclassdev"
	echo "/sys/class input device:    $sysinputname"
	echo "Capslock:      $A"
	echo "Compose:       $o"
	echo "Kana:          $k"
	echo "Scroll lock:   $s"
	echo "Numlock:       $n"
}

# List all input devices by their ID;
# the user can use any unique fragment of the filename as the KEYBOARD argument.
list_keyboard_input_devices() {
	ls -1 /dev/input/by-id/*-event-kbd | grep -v 'if[0-9][0-9]-event-kbd$'
}

# Set an LED
setled() {
	ledpath="$1"
	value="$2"
	if ! test -e "$ledpath"; then
		echo "LED brightness file does not exist at $ledpath"
		exit 1
	fi
	case "$value" in
		0|1) echo "$value" > "$ledpath";;
		*)
			if test "$(tr -d '\n' <"$ledpath")" -eq 0; then
				echo 1 >"$ledpath"
			else
				echo 0 >"$ledpath"
			fi;;
	esac
}

kbd=
setcapslock=
setcompose=
setkana=
setnumlock=
setscrolllock=
readstatus=
ploopycmd=
while test $# -gt 0; do
	case "$1" in
		-h|--help) usage; exit;;
		-A) setcapslock="$2"; shift 2;;
		-o) setcompose="$2"; shift 2;;
		-k) setkana="$2"; shift 2;;
		-n) setnumlock="$2"; shift 2;;
		-s) setscrolllock="$2"; shift 2;;
		-l) list_keyboard_input_devices; exit;;
		-t) readstatus=1; shift;;
		-p)
			# If a keyboard was not passed in Ploopy LKBM mode, guess
			if test -z "$kbd"; then
				kbd="PloopyCo_Trackball_Nano"
			fi
			ploopycmd="$2"
			shift 2;;
		-*) usage; echo ""; echo "Invalid option: $1"; exit 1;;
		*)
			if test -z "$kbd"; then
				kbd="$1"
			else
				usage; echo ""; echo "Invalid argument: $1"; exit 1;
			fi
			shift;;
	esac
done

if test -z "$kbd"; then
	usage
	echo ""
	echo "No keyboard argument passed"
	exit 1
fi
findkbd "$kbd"

if test "$ploopycmd"; then
	case "$ploopycmd" in
		scroll) lkbm_toggle_scroll;;
		dpi) lkbm_cycle_dpi;;
		reset) lkbm_enter_reset;;
		*) usage;;
	esac
else
	test "$setcapslock" && setled "$ledcapslock" "$setcapslock"
	test "$setcompose" && setled "$ledcompose" "$setcompose"
	test "$setkana" && setled "$ledkana" "$setkana"
	test "$setnumlock" && setled "$lednumlock" "$setnumlock"
	test "$setscrolllock" && setled "$ledscrolllock" "$setscrolllock"
fi

test "$readstatus" && read_status