Driver documentation for yealink usb-p1k phones

0. Status
~~~~~~~~~
The p1k is a relatively cheap usb 1.1 phone with:
  - keyboard		full support, yealink.ko / input event API
  - LCD			full support, yealink.ko / sysfs API
  - LED			full support, yealink.ko / sysfs API
  - dialtone		full support, yealink.ko / sysfs API
  - ringtone		full support, yealink.ko / sysfs API
  - audio playback   	full support, snd_usb_audio.ko / alsa API
  - audio record     	full support, snd_usb_audio.ko / alsa API

For vendor documentation see http://www.yealink.com


1. Compilation (stand alone version)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Currently only kernel 2.6.x.y versions are supported.
In order to build the yealink.ko module do

  make

If you encounter problems please check if in the MAKE_OPTS variable in
the Makefile is pointing to the location where your kernel sources
are located, default /usr/src/linux.


1.1 Troubleshooting
~~~~~~~~~~~~~~~~~~~
Q: Module yealink compiled and installed without any problem but phone
   is not initialized and does not react to any actions.
A: If you see something like:
   hiddev0: USB HID v1.00 Device [Yealink Network Technology Ltd. VOIP USB Phone
   in dmesg, it means that the hid driver has grabbed the device first. Try to
   load module yealink before any other usb hid driver. Please see the
   instructions provided by your distribution on module configuration.

Q: Phone is working now (displays version and accepts keypad input) but I can't
   find the sysfs files.
A: The sysfs files are located on the particular usb endpoint. On most
   distributions you can do: "find /sys/ -name get_icons" for a hint.


2. keyboard features
~~~~~~~~~~~~~~~~~~~~
The current mapping in the kernel is provided by the map_p1k_to_key
function:

   Physical USB-P1K button layout	input events


              up			     up
        IN           OUT		left,	right
             down			    down

      pickup   C    hangup		enter, backspace, escape
        1      2      3			1, 2, 3
        4      5      6			4, 5, 6,
        7      8      9			7, 8, 9,
        *      0      #			*, 0, #,

  The "up" and "down" keys, are symbolised by arrows on the button.
  The "pickup" and "hangup" keys are symbolised by a green and red phone
  on the button.


3. LCD features
~~~~~~~~~~~~~~~
The LCD is divided and organised as a 3 line display:

    |[]   [][]   [][]   [][]   in   |[][]
    |[] M [][] D [][] : [][]   out  |[][]
                              store

    NEW REP         SU MO TU WE TH FR SA

    [] [] [] [] [] [] [] [] [] [] [] []
    [] [] [] [] [] [] [] [] [] [] [] []


Line 1	Format (see below)	: 18.e8.M8.88...188
	Icon names		:   M  D  :  IN OUT STORE
Line 2  Format			: .........
	Icon name		: NEW REP SU MO TU WE TH FR SA
Line 3  Format			: 888888888888


Format description:
  From a userspace perspective the world is separated into "digits" and "icons".
  A digit can have a character set, an icon can only be ON or OFF.

  Format specifier
    '8' :  Generic 7 segment digit with individual addressable segments

    Reduced capability 7 segment digit, when segments are hard wired together.
    '1' : 2 segments digit only able to produce a 1.
    'e' : Most significant day of the month digit,
          able to produce at least 1 2 3.
    'M' : Most significant minute digit,
          able to produce at least 0 1 2 3 4 5.

    Icons or pictograms:
    '.' : For example like AM, PM, SU, a 'dot' .. or other single segment
	  elements.


4. Driver usage
~~~~~~~~~~~~~~~
For userland the following interfaces are available using the sysfs interface:
  /sys/.../
           line1	Read/Write, lcd line1
           line2	Read/Write, lcd line2
           line3	Read/Write, lcd line3

	   get_icons    Read, returns a set of available icons.
	   hide_icon    Write, hide the element by writing the icon name.
	   show_icon    Write, display the element by writing the icon name.

	   map_seg7	Read/Write, the 7 segments char set, common for all
	   		yealink phones. (see map_to_7segment.h)

	   ringtone	Write, upload binary representation of a ringtone,
	   		see yealink.c. status EXPERIMENTAL due to potential
			races between async. and sync usb calls.


4.1 lineX
~~~~~~~~~
Reading /sys/../lineX will return the format string with its current value:

  Example:
  cat ./line3
  888888888888
  Linux Rocks!

Writing to /sys/../lineX will set the corresponding LCD line.
 - Excess characters are ignored.
 - If less characters are written than allowed, the remaining digits are
   unchanged.
 - The tab '\t'and '\n' char does not overwrite the original content.
 - Writing a space to an icon will always hide its content.

  Example:
  date +"%m.%e.%k:%M"  | sed 's/^0/ /' > ./line1

  Will update the LCD with the current date & time.


4.2 get_icons
~~~~~~~~~~~~~
Reading will return all available icon names and its current settings:

  cat ./get_icons
  on M
  on D
  on :
     IN
     OUT
     STORE
     NEW
     REP
     SU
     MO
     TU
     WE
     TH
     FR
     SA
     LED
     DIALTONE
     RINGTONE


4.3 show/hide icons
~~~~~~~~~~~~~~~~~~~
Writing to these files will update the state of the icon.
Only one icon at a time can be updated.

If an icon is also on a ./lineX the corresponding value is
updated with the first letter of the icon.

  Example - light up the store icon:
  echo -n "STORE" > ./show_icon

  cat ./line1
  18.e8.M8.88...188
               S

  Example - sound the ringtone for 10 seconds:
  echo -n RINGTONE > /sys/..../show_icon
  sleep 10
  echo -n RINGTONE > /sys/..../hide_icon


5. Sound features
~~~~~~~~~~~~~~~~~
Sound is supported by the ALSA driver: snd_usb_audio

One 16-bit channel with sample and playback rates of 8000 Hz is the practical
limit of the device.

  Example - recording test:
  arecord -v -d 10 -r 8000 -f S16_LE -t wav  foobar.wav

  Example - playback test:
  aplay foobar.wav


6. Credits & Acknowledgments
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  - Olivier Vandorpe, for starting the usbb2k-api project doing much of
	the reverse engineering.
  - Martin Diehl, for pointing out how to handle USB memory allocation.
  - Dmitry Torokhov, for the numerous code reviews and suggestions.