Input: add driver for SOC button array

This patch adds support for the GPIO buttons on some Intel Bay Trail
tablets originally running Windows 8. The ACPI description of these
buttons follows "Windows ACPI Design Guide for SoC Platforms".

Signed-off-by: Lejun Zhu <lejun.zhu@linux.intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Input: appletouch - implement sensor data smoothing

Use smoothed version of sensor array data to calculate movement and add
weight to prior values when calculating average. This gives more granular
and more predictable movement.

Signed-off-by: Clinton Sprain <clintonsprain@gmail.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Input: appletouch - fix jumps when additional fingers are detected

Addresses issues related to when a second finger enters or leaves the
field, causing the cursor to jump or the page to scroll unexpectedly; now,
we discard any movement change that happens at the exact moment we detect a
change in the number of fingers touching the trackpad. This doesn't
completely resolve the issue but does greatly mitigate it.

Signed-off-by: Clinton Sprain <clintonsprain@gmail.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>