Toggle Panasonic Toughpad FZ-G1 touchscreen on Linux

I've been using the Panasonic Toughpad FZ-G1 tablet for a while for satellite receptions while on the go, as it's very rugged and, especially, waterproof.

This tablet is fitted with two input systems: a Wacom digitizer with its stylus, that also works when submerged, and a normal multipoint touchscreen made by eGalax. The latter is problematic while using the tablet under harsh weather conditions, as it is prone to "going crazy" as soon as the screen gets even slightly wet.

The solution could be to permanently disable the multipoint touchscreen and only rely on the Wacom stylus, but this is not as convenient for many things. It's better to be able to toggle the touchscreen on and off via the function keys, so it can be disabled when it's raining and turned on in dry weather.

Keep in mind these commands will work on any computer with a touchscreen, but you will need to adjust the VID/PID accordingly.

Touchscreens can be enabled by writing the USB ID to the /sys/bus/hid/drivers/hid-multitouch/bind pseudofile, and disabled by naturally writing the USB ID to the /sys/bus/hid/drivers/hid-multitouch/unbind pseudofile, for example:

# echo "0003:0EEF:C08F.0002" > /sys/bus/hid/drivers/hid-multitouch/bind

The problem is that the full USB ID is needed, it is not enough to just write the VID:PID, and this changes on reboot depending on which peripherals get initialised first.

The quickest (and dirtiest) solution is to have a cronjob run on reboot as follows, that will write the full ID to a file, that can then be used by the other scripts.

In crontab:

@reboot cat /proc/bus/input/devices | grep -Po \([0-9]{4}:0EEF:C08F\.[0-9]{4}\) | head -n 1 > /opt/ts_devid

Enable script:

#!/bin/bash
echo `cat /opt/ts_devid` > /sys/bus/hid/drivers/hid-multitouch/bind

Disable script:

#!/bin/bash
echo `cat /opt/ts_devid` > /sys/bus/hid/drivers/hid-multitouch/unbind

These scripts need to be executed with root permissions, so if you want to run them from a keybind (e.g. via Gnome) you'll need to add an appropriate entry in /etc/sudoers to let them run without a password.