Mouse reset
-----------

  1: Set UART to 'break line' state (set bit 6 in the LCR).
  2: Clear the RTS and DTR (bits 0-1) in the MCR, wait a while.
  3: Set the RTS and DTR bits again.


Serial mice detection (identification bytes before optional PnP data)
---------------------------------------------------------------------

  In Microsoft mode mouse sends 'M' after dropping and raising RTS.
  In Logitech mode mouse sends 'M3' after dropping and raising RTS.
  In Microsoft wheel mode mouse sends 'MZ@',0,0,0 after
	dropping and raising RTS.
  In Mouse Systems mode mouse sends nothing.


===========================================================================
Serial Mouse Systems mode: 1200 bps, 8 data bits, 1 stop bit, no parity

	      1st byte		2nd byte	  3rd byte
	 +---------------+ +---------------+ +---------------+
	 |1|0|0|0|0|L|M|R| |X|X|X|X|X|X|X|X| |Y|Y|Y|Y|Y|Y|Y|Y|
	 +---------------+ +---------------+ +---------------+
		    | | |     Xa movement	Ya movement
		    | | |
		    | | |       4th byte 	 5th byte
  Left Button ------+ | |  +---------------+ +---------------+
Middle Button --------+ |  |X|X|X|X|X|X|X|X| |Y|Y|Y|Y|Y|Y|Y|Y|
 Right Button ----------+  +---------------+ +---------------+
(0 if pressed)		      Xb movement	Yb movement
			

Xa/Ya - movement of the mouse since last packet.
Xb/Yb - movement of the mouse since Xa/Ya.
Movement values are 8-bit signed twos complement integers.
Positive movement value indicates motion to the right/upward.


===========================================================================
Serial Microsoft mode: 1200 bps, 7 data bits, 1 stop bit, no parity

	      1st byte		2nd byte	  3rd byte
	 +---------------+ +---------------+ +---------------+
	 |0|1|L|R|Y|Y|X|X| |0|0|X|X|X|X|X|X| |0|0|Y|Y|Y|Y|Y|Y|
	 +---------------+ +---------------+ +---------------+
	      | | \ / \ /	\----+----/	  \----+----/
	      | |  |   |	     |		       |
	      | |  +---|-------------|---------+       |
	      | |      +-----+	     |	       |       |
	      | |	    / \ /----+----\   / \ /----+----\
	      | |	   +---------------+ +---------------+
 Left Button -+ |	   | | | | | | | | | | | | | | | | | |
Right Button ---+	   +---------------+ +---------------+
(1 if pressed)		       X movement	 Y movement


Movement values are 8-bit signed twos complement integers.
Positive movement value indicates motion to the right/downward.


===========================================================================
Serial Logitech mode: 1200 bps, 7 data bits, 1 stop bit, no parity

	      1st byte		2nd byte	  3rd byte
	 +---------------+ +---------------+ +---------------+
	 |0|1|L|R|Y|Y|X|X| |0|0|X|X|X|X|X|X| |0|0|Y|Y|Y|Y|Y|Y|
	 +---------------+ +---------------+ +---------------+
	      | | \ / \ /	\----+----/	  \----+----/
	      | |  |   |	     |		       |
	      | |  +---|-------------|---------+       |
	      | |      +-----+	     |	       |       |
	      | |	    / \ /----+----\   / \ /----+----\
	      | |	   +---------------+ +---------------+
 Left Button -+ |	   | | | | | | | | | | | | | | | | | |
Right Button ---+	   +---------------+ +---------------+
(1 if pressed)		       X movement	 Y movement


The extra byte (only when middle button is pressed)
---------------------------------------------------

	     4th byte
	+---------------+
	|0|0|M|0|0|0|0|0|
	+---------------+
	     |
	Middle Button (1 if pressed)


First three bytes are equal to Mouse mode packet.
Movement values are 8-bit signed twos complement integers.
Positive movement value indicates motion to the right/downward.


===========================================================================
Serial Microsoft wheel mode: 1200 bps, 7 data bits, 1 stop bit, no parity

	      1st byte		2nd byte	  3rd byte	    4th byte
	 +---------------+ +---------------+ +---------------+ +---------------+
	 |0|1|L|R|Y|Y|X|X| |0|0|X|X|X|X|X|X| |0|0|Y|Y|Y|Y|Y|Y| |0|0|0|M|w|w|w|w|
	 +---------------+ +---------------+ +---------------+ +---------------+
	      | | \ / \ /	\----+----/	  \----+----/	      | \--+--/
	      | |  |   |	     |		       |	      |	   |
	      | |  +---|-------------|---------+       |      Middle -+	   |
	      | |      +-----+	     |	       |       |      Button	   |
	      | |	    / \ /----+----\   / \ /----+----\		   |
	      | |	   +---------------+ +---------------+	  Wheel ---+
 Left Button -+ |	   | | | | | | | | | | | | | | | | | |	 Movement
Right Button ---+	   +---------------+ +---------------+
(1 if pressed)		       X movement	 Y movement


First three bytes are equal to Mouse mode packet.
Movement values are 8-bit signed twos complement integers.
Positive movement value indicates motion to the right/downward.


===========================================================================
PS/2 standard mode protocol:

	      1st byte		2nd byte	  3rd byte
	 +---------------+ +---------------+ +---------------+
	 |?|?|Y|X|1|M|R|L| |X|X|X|X|X|X|X|X| |Y|Y|Y|Y|Y|Y|Y|Y|
	 +---------------+ +---------------+ +---------------+
	      | |   | | |   \------+------/   \------+------/
	      | |   | | |	   |		     |
	      +-|---|-|-|----------|-----------+     |
		+---|-|-|--+	   |	       |     |
		    | | |  | /-----+-------\   | /---+---------\
Middle Button ------+ | | +-----------------+ +-----------------+
 Right Button --------+ | | | | | | | | | | | | | | | | | | | |	|
  Left Button ----------+ +-----------------+ +-----------------+
(1 if pressed)		       X movement	   Y movement


Two most significant bits in first byte indicate overflow (more than 9 bits
  of movement) in each direction. Usually ignored.
Movement values are 9-bit signed twos complement integers.
Positive movement value indicates motion to the right/upward.


===========================================================================
PS/2 wheel mode protocol:

	      1st byte		2nd byte	  3rd byte	    4th byte
	 +---------------+ +---------------+ +---------------+ +---------------+
	 |?|?|Y|X|1|M|R|L| |X|X|X|X|X|X|X|X| |Y|Y|Y|Y|Y|Y|Y|Y| |w|w|w|w|W|W|W|W|
	 +---------------+ +---------------+ +---------------+ +---------------+
	      | |   | | |   \------+------/   \------+------/	\-------+-----/
	      | |   | | |	   |		     |			|
	      +-|---|-|-|----------|-----------+     |			|
		+---|-|-|--+	   |	       |     |			|
		    | | |  | /-----+-------\   | /---+---------\	|
Middle Button ------+ | | +-----------------+ +-----------------+	|
 Right Button --------+ | | | | | | | | | | | | | | | | | | | |	|	|
  Left Button ----------+ +-----------------+ +-----------------+     Wheel
(1 if pressed)		       X movement	   Y movement	     Movement


First three bytes are equal to PS/2 standard mode packet.
Two most significant bits in first byte indicate overflow (more than 9 bits
  of movement) in each direction. Usually ignored.
Movement values are 9-bit signed twos complement integers.
Positive movement value indicates motion to the right/upward.
Wheel movemement is a 8-bit signed twos complement integer and usually
  limited by -8..+7 range (4-bit value).
Positive wheel movemenet value indicates rotation downward.