psm(4) sync with FreeBSD

[Antonio Huete Jimenez <ahuete.devel@xxxxxxxxx>]

Hi,

I've done a full sync of the psm(4) driver with FreeBSD, you can check
the changes here:

http://gitweb.dragonflybsd.org/~tuxillo/dragonfly.git/shortlog/refs/heads/psm

Any review, comments, opinions are welcome.

The reason for doing this is that my mouse was not working in one of
the two machines I got connected to a KVM switch (mouse/keyboard/vga).
FreeBSD already solved this issue so I thought it was worth bringing
it. The port also includes a number of changes; you can check a small
list of them below:

- Support for A4 Tech RFSW-35 mouse wheel.
- Ignore strange return values in test_aux_port()  from some laptops
(Compaq, Toshiba, Acer).
- Support synaptics touchpad w/ many features such as supporting
integrated wheel, up/down buttons or tapping.
- Synaptic tunables hw.psm.tap_enabled and hw.psm.synaptics_support to
control activation and/or features like gestures.
- Fix many issues with buggy KVM switches which got the mouse confused
on sync packets.
- ALPS glide point ID.
- Let some PS/2 mice to get directly to Explorer mode (i.e. A4Tech X-7xx)

Additionally I've built an USB Image for easier testing.

http://island.quantumachine.net/pub/temp/dfly_testpsm.bz2

* Testing instructions:
1. Write the .img file to a USB stick, if you are in Windows you can
use flashnul (http://shounen.ru/soft/flashnul/)
2. Boot your PC/Laptop with the USB stick
3. Login as root and execute 'rcenable moused'. You should be able to
use the mouse normally.
4. If you have a synaptics touchpad, put in
'hw.psm.synaptics_support=1' and ' hw.psm.tap_enabled=1", reboot and
check whether tapping works on the console.

-------------
I've done some testing by myself with satisfactory results:

- VMWare VM DFBSD i386 - OK
- VMWare VM DFBSD x86_64 - Ok
- Acer Aspire One - DFBSD i386 (Synaptics touchpad detected, tapping
works on console)
- Dell Latitude D620 - DFBSD i386 - Ok (tapping doesn't work on
console, not synaptics)
- AMD Athlon X2 - DFBSD i386 connected to a buggy KVM switch - Ok

Cheers,
Antonio Huete