Disable wakeup from suspend for select USB devices

I noticed that my cat sometimes pulls my computer out of suspend by walking across the keyboard during the night. 🐾 So I decided to disable waking up the system via the keyboard, and this is the result. Now my computer should sleep well, too, instead of wasting power all night. 😸

How it works

The script checks the sysfs entries for your USB devices, which can be found in /sys/bus/usb/devices/. The files within the device directory contain (among other thing) information that identifies the device, like its type or manufacturer. The script compares these against a configured list, and on a match it writes disabled to the power/wakeup file for the device. This should work on any Linux system. 🐧

Installation

Just copy the script to a suitable location and copy the systemd unit to the system units directory, then enable it:

sudo cp disable-usb-wakeup.py /etc/
sudo cp disable-usb-wakeup.service /etc/systemd/system/
systemctl enable disable-usb-wakeup.service

You can use another location for the script, just adjust the ExecStart line in the service unit accordingly. You should not use a script file owned by a regular (non-root) user, because then it could be used for privilege escalation: That user could edit the file to have the systemd unit do just about anything.

The unit is configured to start before sleep.target. The reason why I don't use multi-user.target is that re-plugging a device resets its wakeup setting, and I want the unit to work regardless of whether the device has been unplugged at any point after boot.

For other init systems you'll have to use their means to run the script at the right time.

Configuration

The default configuration contained in the script disables wakeup for all USB keyboards. If that doesn't suit your needs, you can create a JSON configuration file, for example like this if don't want your computer to wake up on any USB mouse, and also not for the device with vendor ID 1234 and product ID abcd:

{
    "disable_wakeup": [
        {"product": "usb mouse"},
        {"idVendor": "1234", "idProduct": "abcd"}
    ]
}

The properties of each item in the disable_wakeup list are compared against the properties of each USB device, and wakeup set to disabled for each match. The properties for each device are read from the per-device sysfs files named like the properties, devices that lack any of the used properties are ignored.

Once you have your configuration file change the ExecStart line in the systemd unit to use it, for example:

ExecStart=/etc/disable-usb-wakeup.py -q -c /path/to/config.json