systemd/hwdb/70-touchpad.hwdb

# This file is part of systemd.
#
# The lookup keys are composed in:
#   70-touchpad.rules
#
# Note: The format of the "touchpad:" prefix match key is a
# contract between the rules file and the hardware data, it might
# change in later revisions to support more or better matches, it
# is not necessarily expected to be a stable ABI.
#
# Match string format:
# touchpad:pnpid:<pnpid>:
#
# To add local entries, create a new file
#   /etc/udev/hwdb.d/71-touchpad-local.hwdb
# and add your rules there. To load the new rules execute (as root):
#   udevadm hwdb --update
#   udevadm trigger /dev/input/eventXX
# where /dev/input/eventXX is the touchpad in question. If in
# doubt, simply use /dev/input/event* to reload all input rules.
#
# If your changes are generally applicable, open a bug report on
#   http://bugs.freedesktop.org/enter_bug.cgi?product=systemd
# and include your new rules, a description of the device, and the
# output of
#   udevadm info /dev/input/eventXX
# (or /dev/input/event*).
#
# Allowed properties are:
#    TOUCHPAD_HAS_TRACKPOINT_BUTTONS=1
#
# If the TOUCHPAD_HAS_TRACKPOINT_BUTTONS property is set, this
# device has # the trackpoint buttons wired up to the touchpad as
# BTN_0, BTN_1 and BTN_2. This affects the Lenovo X1 Carbon 3rd
# and the *50 series (T450, T550, etc.)

# Lenovo X1 Carbon 3rd
touchpad:pnpid:*LEN0048*:
# Lenovo W541
touchpad:pnpid:*LEN004a*:
# Lenovo T450s
touchpad:pnpid:*LEN200f*:
 TOUCHPAD_HAS_TRACKPOINT_BUTTONS=1