The Sentelic touchpad in an ASUS ZenBook UX21E is reported as

"psmouse serio4: sentelic: Finger Sensing Pad, hw: 14.3.1, sw: 1.0.0-K, buttons: 4"

and does not offer any kind of scrolling support with unpatched Linux kernel
version 3.2-rc6.

This patch adds absolute positioning support for it which enables edge
scrolling as well as multitouch support which enables two-finger scrolling.

To use the patched driver copy the files from src/ to drivers/input/mouse/
or apply the patch in patches/.  The patch applies cleanly to 3.2-rc6.
There's also an unrelated patch under patches/ to add support for the USB
Ethernet adapter delivered with the ZenBook.

TODO:

* Middle-click support
* Cursor movement is a bit jumpy
* Horizontal two-finger scrolling does not work (at least in Gnome 3) for
  some reason and also messes up vertical scrolling
* Figure out more values for the registers