Lenovo *40 series touchpad support
The Lenovo *40 series emulates trackstick buttons on the top part of the touchpads.
The Lenovo *40 series introduced a new type of touchpad. Previously, all laptops had a separate set of physical buttons for the trackstick. This series removed these buttons, relying on a software emulation of the top section of the touchpad. This is visually marked on the trackpad itself, and clicks can be triggered by pressing the touchpad down with a finger in the respective area:
This page only covers the top software buttons, the bottom button behavior is covered in Clickpad software buttons.
Clickpads with a top button area are marked with the INPUT_PROP_TOPBUTTONPAD property.
The firmware on the first generation of touchpads providing top software buttons is buggy and announces wrong ranges. Kernel patches are required; these fixes are available in kernels 3.14.1, 3.15 and later but each touchpad needs a separate fix.
The October 2014 refresh of these laptops do not have this firmware bug anymore and should work without per-device patches, though this kernel commit is required.
For a complete list of supported touchpads check the kernel source (search for “topbuttonpad_pnp_ids”).