Elantech Touchpad Driver

드라이버 계보와 하드웨어 세대

Elantech 터치패드 드라이버 문서는 2007~2008년 Arjan Opmeer가 저작했습니다. 하드웨어 버전 1의 추가 정보는 Steve Havelka가 제공했고, EeePC용 버전 2 지원은 Xandros의 Woody가 만든 패치를 eeeuser.com의 StewieGriffin이 전달한 것을 기반으로 합니다.

문서는 소개, 추가 sysfs 조절값, 버전 판별, 하드웨어 v1~v4의 레지스터와 패킷 형식, 그리고 v3/v4 트랙포인트 형식을 차례로 다룹니다.

일부 v3와 v4 장치는 별도 6바이트 형식의 트랙포인트를 포함합니다. 드라이버는 모든 세대를 지원하며 Xorg Synaptics 터치패드 드라이버와 그래픽 구성 도구에 호환되도록 설계됐습니다.

트랙포인트가 있는 장치에서는 마우스 버튼이 터치패드 또는 트랙포인트 중 하나와 연결됩니다. Xorg에서 터치패드를 비활성화하는 원문 설정 `TouchPadOff=0`은 터치패드에 연결된 버튼도 함께 비활성화합니다.

내부 레지스터는 `/sys/bus/serio/drivers/psmouse/serio?` 아래 읽기·쓰기 가능한 sysfs 항목으로 노출됩니다. v1 레지스터만 어느 정도 이해됐고 v2는 같은 레지스터를 쓰는 듯하지만 비트 의미가 같은지는 알 수 없습니다.

일부 레지스터는 상대 모드에서만 효과가 있습니다. Linux 드라이버는 하드웨어를 항상 절대 모드로 두므로 아래 정보 중 일부를 즉시 활용할 수 없습니다. 공개 Elantech 문서가 없기 때문에 완전성을 위해 관찰된 정보를 수록합니다.

Elantech Touchpad Driver
========================

        Copyright (C) 2007-2008 Arjan Opmeer <[email protected]>

        Extra information for hardware version 1 found and
        provided by Steve Havelka

        Version 2 (EeePC) hardware support based on patches
        received from Woody at Xandros and forwarded to me
        by user StewieGriffin at the eeeuser.com forum

.. Contents

 1. Introduction
 2. Extra knobs
 3. Differentiating hardware versions
 4. Hardware version 1
    4.1 Registers
    4.2 Native relative mode 4 byte packet format
    4.3 Native absolute mode 4 byte packet format
 5. Hardware version 2
    5.1 Registers
    5.2 Native absolute mode 6 byte packet format
        5.2.1 Parity checking and packet re-synchronization
        5.2.2 One/Three finger touch
        5.2.3 Two finger touch
 6. Hardware version 3
    6.1 Registers
    6.2 Native absolute mode 6 byte packet format
        6.2.1 One/Three finger touch
        6.2.2 Two finger touch
 7. Hardware version 4
    7.1 Registers
    7.2 Native absolute mode 6 byte packet format
        7.2.1 Status packet
        7.2.2 Head packet
        7.2.3 Motion packet
 8. Trackpoint (for Hardware version 3 and 4)
    8.1 Registers
    8.2 Native relative mode 6 byte packet format
        8.2.1 Status Packet



Introduction
~~~~~~~~~~~~

Currently the Linux Elantech touchpad driver is aware of four different
hardware versions unimaginatively called version 1,version 2, version 3
and version 4. Version 1 is found in "older" laptops and uses 4 bytes per
packet. Version 2 seems to be introduced with the EeePC and uses 6 bytes
per packet, and provides additional features such as position of two fingers,
and width of the touch.  Hardware version 3 uses 6 bytes per packet (and
for 2 fingers the concatenation of two 6 bytes packets) and allows tracking
of up to 3 fingers. Hardware version 4 uses 6 bytes per packet, and can
combine a status packet with multiple head or motion packets. Hardware version
4 allows tracking up to 5 fingers.

Some Hardware version 3 and version 4 also have a trackpoint which uses a
separate packet format. It is also 6 bytes per packet.

The driver tries to support both hardware versions and should be compatible
with the Xorg Synaptics touchpad driver and its graphical configuration
utilities.

Note that a mouse button is also associated with either the touchpad or the
trackpoint when a trackpoint is available.  Disabling the Touchpad in xorg
(TouchPadOff=0) will also disable the buttons associated with the touchpad.

Additionally the operation of the touchpad can be altered by adjusting the
contents of some of its internal registers. These registers are represented
by the driver as sysfs entries under /sys/bus/serio/drivers/psmouse/serio?
that can be read from and written to.

Currently only the registers for hardware version 1 are somewhat understood.
Hardware version 2 seems to use some of the same registers but it is not
known whether the bits in the registers represent the same thing or might
have changed their meaning.

On top of that, some register settings have effect only when the touchpad is
in relative mode and not in absolute mode. As the Linux Elantech touchpad
driver always puts the hardware into absolute mode not all information
mentioned below can be used immediately. But because there is no freely
available Elantech documentation the information is provided here anyway for
completeness sake.

추가 sysfs 조절값과 버전 판별

드라이버는 `/sys/bus/serio/drivers/psmouse/serio?` 아래에 `debug`, `paritycheck`, `crc_enabled` 세 조절값을 제공합니다.

패킷 디버깅은 처리 전 모든 패킷을 syslog에 기록하므로 매우 많은 데이터를 만들 수 있습니다. `crc_enabled`는 공식 이름이지만 실제 cyclic redundancy check는 아닙니다. 활성 상태에 따라 v3/v4에서 기본 무결성 검사를 하고 손상으로 보이는 패킷을 거부합니다.

하드웨어 버전은 `param[0].param[1].param[2]` 형식의 버전 번호로 판별합니다. Dell 제공 드라이버의 이름과 알려진 패킷 길이는 다음과 같습니다.

EF113만 압력과 폭을 보고하지 않고 데이터 일관성 검사도 다르며, 나머지 6바이트 버전은 거의 차이가 없는 것으로 보입니다.

Extra knobs
~~~~~~~~~~~

Currently the Linux Elantech touchpad driver provides three extra knobs under
/sys/bus/serio/drivers/psmouse/serio? for the user.

* debug

   Turn different levels of debugging ON or OFF.

   By echoing "0" to this file all debugging will be turned OFF.

   Currently a value of "1" will turn on some basic debugging and a value of
   "2" will turn on packet debugging. For hardware version 1 the default is
   OFF. For version 2 the default is "1".

   Turning packet debugging on will make the driver dump every packet
   received to the syslog before processing it. Be warned that this can
   generate quite a lot of data!

* paritycheck

   Turns parity checking ON or OFF.

   By echoing "0" to this file parity checking will be turned OFF. Any
   non-zero value will turn it ON. For hardware version 1 the default is ON.
   For version 2 the default it is OFF.

   Hardware version 1 provides basic data integrity verification by
   calculating a parity bit for the last 3 bytes of each packet. The driver
   can check these bits and reject any packet that appears corrupted. Using
   this knob you can bypass that check.

   Hardware version 2 does not provide the same parity bits. Only some basic
   data consistency checking can be done. For now checking is disabled by
   default. Currently even turning it on will do nothing.

* crc_enabled

   Sets crc_enabled to 0/1. The name "crc_enabled" is the official name of
   this integrity check, even though it is not an actual cyclic redundancy
   check.

   Depending on the state of crc_enabled, certain basic data integrity
   verification is done by the driver on hardware version 3 and 4. The
   driver will reject any packet that appears corrupted. Using this knob,
   The state of crc_enabled can be altered with this knob.

   Reading the crc_enabled value will show the active value. Echoing
   "0" or "1" to this file will set the state to "0" or "1".

Differentiating hardware versions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To detect the hardware version, read the version number as param[0].param[1].param[2]::

 4 bytes version: (after the arrow is the name given in the Dell-provided driver)
 02.00.22 => EF013
 02.06.00 => EF019

In the wild, there appear to be more versions, such as 00.01.64, 01.00.21,
02.00.00, 02.00.04, 02.00.06::

 6 bytes:
 02.00.30 => EF113
 02.08.00 => EF023
 02.08.XX => EF123
 02.0B.00 => EF215
 04.01.XX => Scroll_EF051
 04.02.XX => EF051

In the wild, there appear to be more versions, such as 04.03.01, 04.04.11. There
appears to be almost no difference, except for EF113, which does not report
pressure/width and has different data consistency checks.

Probably all the versions with param[0] <= 01 can be considered as
4 bytes/firmware 1. The versions < 02.08.00, with the exception of 02.00.30, as
4 bytes/firmware 2. Everything >= 02.08.00 can be considered as 6 bytes.

하드웨어 버전 1 레지스터와 4바이트 패킷

v1 레지스터는 sysfs 파일에 16진 값을 써서 변경합니다. 예를 들어 `echo -n 0x16 > reg_10`처럼 설정합니다.

Parity가 켜진 일반 패킷에서 `ds3..ds0`는 스크롤 양과 방향이며 양수는 아래 또는 왼쪽, 음수는 위 또는 오른쪽입니다. Corner tap이면 `ds0`=오른쪽 위, `ds1`=오른쪽 아래, `ds2`=왼쪽 아래, `ds3`=왼쪽 위입니다. `n1..n0` 손가락 수는 firmware 2.x만 보고하고, 1.x는 1/2/3손가락 탭을 L/M/R 버튼에 직접 매핑하는 것으로 보입니다. `h`는 수평 스크롤, `w`는 넓은 손가락 접촉 추정 비트입니다.

v1 절대 모드의 EF013과 EF019는 펌웨어 버그로 보이는 특수 동작이 있습니다. 한 손가락이 닿으면 처음 두 위치 보고를 버려야 하며 손가락 수가 바뀔 때 카운트를 재설정합니다.

Hardware version 1
~~~~~~~~~~~~~~~~~~

Registers
---------

By echoing a hexadecimal value to a register it contents can be altered.

For example::

   echo -n 0x16 > reg_10

* reg_10::

   bit   7   6   5   4   3   2   1   0
         B   C   T   D   L   A   S   E

         E: 1 = enable smart edges unconditionally
         S: 1 = enable smart edges only when dragging
         A: 1 = absolute mode (needs 4 byte packets, see reg_11)
         L: 1 = enable drag lock (see reg_22)
         D: 1 = disable dynamic resolution
         T: 1 = disable tapping
         C: 1 = enable corner tap
         B: 1 = swap left and right button

* reg_11::

   bit   7   6   5   4   3   2   1   0
         1   0   0   H   V   1   F   P

         P: 1 = enable parity checking for relative mode
         F: 1 = enable native 4 byte packet mode
         V: 1 = enable vertical scroll area
         H: 1 = enable horizontal scroll area

* reg_20::

         single finger width?

* reg_21::

         scroll area width (small: 0x40 ... wide: 0xff)

* reg_22::

         drag lock time out (short: 0x14 ... long: 0xfe;
                             0xff = tap again to release)

* reg_23::

         tap make timeout?

* reg_24::

         tap release timeout?

* reg_25::

         smart edge cursor speed (0x02 = slow, 0x03 = medium, 0x04 = fast)

* reg_26::

         smart edge activation area width?


Native relative mode 4 byte packet format
-----------------------------------------

byte 0::

   bit   7   6   5   4   3   2   1   0
         c   c  p2  p1   1   M   R   L

         L, R, M = 1 when Left, Right, Middle mouse button pressed
            some models have M as byte 3 odd parity bit
         when parity checking is enabled (reg_11, P = 1):
            p1..p2 = byte 1 and 2 odd parity bit
         c = 1 when corner tap detected

byte 1::

   bit   7   6   5   4   3   2   1   0
        dx7 dx6 dx5 dx4 dx3 dx2 dx1 dx0

         dx7..dx0 = x movement;   positive = right, negative = left
         byte 1 = 0xf0 when corner tap detected

byte 2::

   bit   7   6   5   4   3   2   1   0
        dy7 dy6 dy5 dy4 dy3 dy2 dy1 dy0

         dy7..dy0 = y movement;   positive = up,    negative = down

byte 3::

   parity checking enabled (reg_11, P = 1):

      bit   7   6   5   4   3   2   1   0
            w   h  n1  n0  ds3 ds2 ds1 ds0

            normally:
               ds3..ds0 = scroll wheel amount and direction
                          positive = down or left
                          negative = up or right
            when corner tap detected:
               ds0 = 1 when top right corner tapped
               ds1 = 1 when bottom right corner tapped
               ds2 = 1 when bottom left corner tapped
               ds3 = 1 when top left corner tapped
            n1..n0 = number of fingers on touchpad
               only models with firmware 2.x report this, models with
               firmware 1.x seem to map one, two and three finger taps
               directly to L, M and R mouse buttons
            h = 1 when horizontal scroll action
            w = 1 when wide finger touch?

   otherwise (reg_11, P = 0):

      bit   7   6   5   4   3   2   1   0
           ds7 ds6 ds5 ds4 ds3 ds2 ds1 ds0

            ds7..ds0 = vertical scroll amount and direction
                       negative = up
                       positive = down


Native absolute mode 4 byte packet format
-----------------------------------------

EF013 and EF019 have a special behaviour (due to a bug in the firmware?), and
when 1 finger is touching, the first 2 position reports must be discarded.
This counting is reset whenever a different number of fingers is reported.

byte 0::

   firmware version 1.x:

      bit   7   6   5   4   3   2   1   0
            D   U  p1  p2   1  p3   R   L

            L, R = 1 when Left, Right mouse button pressed
            p1..p3 = byte 1..3 odd parity bit
            D, U = 1 when rocker switch pressed Up, Down

   firmware version 2.x:

      bit   7   6   5   4   3   2   1   0
           n1  n0  p2  p1   1  p3   R   L

            L, R = 1 when Left, Right mouse button pressed
            p1..p3 = byte 1..3 odd parity bit
            n1..n0 = number of fingers on touchpad

byte 1::

   firmware version 1.x:

      bit   7   6   5   4   3   2   1   0
            f   0  th  tw  x9  x8  y9  y8

            tw = 1 when two finger touch
            th = 1 when three finger touch
            f  = 1 when finger touch

   firmware version 2.x:

      bit   7   6   5   4   3   2   1   0
            .   .   .   .  x9  x8  y9  y8

byte 2::

   bit   7   6   5   4   3   2   1   0
        x7  x6  x5  x4  x3  x2  x1  x0

         x9..x0 = absolute x value (horizontal)

byte 3::

   bit   7   6   5   4   3   2   1   0
        y7  y6  y5  y4  y3  y2  y1  y0

         y9..y0 = absolute y value (vertical)

하드웨어 버전 2 레지스터와 6바이트 패킷

v2 레지스터도 16진 값을 sysfs에 써서 변경합니다. 예제는 `echo -n 0x56 > reg_10`입니다.

v2에는 parity 비트가 없지만 일관성 검사는 가능합니다. EF113은 여섯 바이트를 `SA1,A1,B1,SB1,C1,D1`로 두고 접촉 상태에 따라 byte 1·2·4·5의 마스크와 상수를 검사합니다.

if ((((SA1 & 0x3C) != 0x3C) && ((SA1 & 0xC0) != 0x80)) ||
    (((SA1 & 0x0C) != 0x0C) && ((SA1 & 0xC0) == 0x80)) ||
    (((SA1 & 0xC0) != 0x80) && (( A1 & 0xF0) != 0x00)) ||
    (((SB1 & 0x3E) != 0x38) && ((SA1 & 0xC0) != 0x80)) ||
    (((SB1 & 0x0E) != 0x08) && ((SA1 & 0xC0) == 0x80)) ||
    (((SA1 & 0xC0) != 0x80) && (( C1 & 0xF0) != 0x00)))
        /* 오류 감지 */

EF113 이외 장치는 `(packet[0] & 0x0C) == 0x04`와 `(packet[3] & 0x0f) == 0x02` 두 상수 조건을 검사합니다. 오류가 감지되면 `packet[0]`을 버리고 전체 패킷 경계를 한 바이트 이동해 재동기화합니다.

`n4`는 3손가락 모드에서 3개보다 많을 때 설정됩니다. EF123의 `vf`는 손가락이 버튼 위면 0, 아니면 1인 것으로 보입니다. `w3..w0` 폭과 `p7..p0` 압력은 EF113에는 없습니다. EF113의 `b2.R.L`은 0 없음, 1 왼쪽, 2 오른쪽, 3 가운데(좌+우), 4 Forward, 5 Back, 6·7 다른 버튼을 나타냅니다.

두 손가락 패킷의 좌표 두 쌍은 실제 두 손가락 좌표가 아니라 경계 사각형의 왼쪽 아래와 오른쪽 위입니다. 실제 손가락은 그 사각형의 반대 대각선에 있을 수도 있습니다.

Hardware version 2
~~~~~~~~~~~~~~~~~~


Registers
---------

By echoing a hexadecimal value to a register it contents can be altered.

For example::

   echo -n 0x56 > reg_10

* reg_10::

   bit   7   6   5   4   3   2   1   0
         0   1   0   1   0   1   D   0

         D: 1 = enable drag and drop

* reg_11::

   bit   7   6   5   4   3   2   1   0
         1   0   0   0   S   0   1   0

         S: 1 = enable vertical scroll

* reg_21::

         unknown (0x00)

* reg_22::

         drag and drop release time out (short: 0x70 ... long 0x7e;
                                   0x7f = never i.e. tap again to release)


Native absolute mode 6 byte packet format
-----------------------------------------

Parity checking and packet re-synchronization
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

There is no parity checking, however some consistency checks can be performed.

For instance for EF113::

        SA1= packet[0];
        A1 = packet[1];
        B1 = packet[2];
        SB1= packet[3];
        C1 = packet[4];
        D1 = packet[5];
        if( (((SA1 & 0x3C) != 0x3C) && ((SA1 & 0xC0) != 0x80)) || // check Byte 1
            (((SA1 & 0x0C) != 0x0C) && ((SA1 & 0xC0) == 0x80)) || // check Byte 1 (one finger pressed)
            (((SA1 & 0xC0) != 0x80) && (( A1 & 0xF0) != 0x00)) || // check Byte 2
            (((SB1 & 0x3E) != 0x38) && ((SA1 & 0xC0) != 0x80)) || // check Byte 4
            (((SB1 & 0x0E) != 0x08) && ((SA1 & 0xC0) == 0x80)) || // check Byte 4 (one finger pressed)
            (((SA1 & 0xC0) != 0x80) && (( C1 & 0xF0) != 0x00))  ) // check Byte 5
                // error detected

For all the other ones, there are just a few constant bits::

        if( ((packet[0] & 0x0C) != 0x04) ||
            ((packet[3] & 0x0f) != 0x02) )
                // error detected


In case an error is detected, all the packets are shifted by one (and packet[0] is discarded).

One/Three finger touch
^^^^^^^^^^^^^^^^^^^^^^

byte 0::

   bit   7   6   5   4   3   2   1   0
         n1  n0  w3  w2   .   .   R   L

         L, R = 1 when Left, Right mouse button pressed
         n1..n0 = number of fingers on touchpad

byte 1::

   bit   7   6   5   4   3   2   1   0
         p7  p6  p5  p4 x11 x10 x9  x8

byte 2::

   bit   7   6   5   4   3   2   1   0
         x7  x6  x5  x4  x3  x2  x1  x0

         x11..x0 = absolute x value (horizontal)

byte 3::

   bit   7   6   5   4   3   2   1   0
         n4  vf  w1  w0   .   .   .  b2

         n4 = set if more than 3 fingers (only in 3 fingers mode)
         vf = a kind of flag ? (only on EF123, 0 when finger is over one
              of the buttons, 1 otherwise)
         w3..w0 = width of the finger touch (not EF113)
         b2 (on EF113 only, 0 otherwise), b2.R.L indicates one button pressed:
                0 = none
                1 = Left
                2 = Right
                3 = Middle (Left and Right)
                4 = Forward
                5 = Back
                6 = Another one
                7 = Another one

byte 4::

   bit   7   6   5   4   3   2   1   0
        p3  p1  p2  p0  y11 y10 y9  y8

         p7..p0 = pressure (not EF113)

byte 5::

   bit   7   6   5   4   3   2   1   0
        y7  y6  y5  y4  y3  y2  y1  y0

         y11..y0 = absolute y value (vertical)


Two finger touch
^^^^^^^^^^^^^^^^

Note that the two pairs of coordinates are not exactly the coordinates of the
two fingers, but only the pair of the lower-left and upper-right coordinates.
So the actual fingers might be situated on the other diagonal of the square
defined by these two points.

byte 0::

   bit   7   6   5   4   3   2   1   0
        n1  n0  ay8 ax8  .   .   R   L

         L, R = 1 when Left, Right mouse button pressed
         n1..n0 = number of fingers on touchpad

byte 1::

   bit   7   6   5   4   3   2   1   0
        ax7 ax6 ax5 ax4 ax3 ax2 ax1 ax0

         ax8..ax0 = lower-left finger absolute x value

byte 2::

   bit   7   6   5   4   3   2   1   0
        ay7 ay6 ay5 ay4 ay3 ay2 ay1 ay0

         ay8..ay0 = lower-left finger absolute y value

byte 3::

   bit   7   6   5   4   3   2   1   0
         .   .  by8 bx8  .   .   .   .

byte 4::

   bit   7   6   5   4   3   2   1   0
        bx7 bx6 bx5 bx4 bx3 bx2 bx1 bx0

         bx8..bx0 = upper-right finger absolute x value

byte 5::

   bit   7   6   5   4   3   2   1   0
        by7 by8 by5 by4 by3 by2 by1 by0

         by8..by0 = upper-right finger absolute y value

하드웨어 버전 3과 debounce 패킷

한 손가락과 세 손가락은 같은 6바이트 형식을 사용하지만, 세 손가락에서는 세 손가락 중심 위치만 보고합니다. 두 손가락은 6바이트 패킷 두 개를 이어 총 12바이트를 보냅니다.

전원이 불안정하거나 전기적 문제가 있거나 손가락 수가 바뀌면 펌웨어가 debounce 상태를 알리는 패킷을 보낼 수 있습니다. 서명은 `c4 ff ff 02 ff ff`이며 드라이버는 이 패킷을 무시합니다.

Hardware version 3
~~~~~~~~~~~~~~~~~~

Registers
---------

* reg_10::

   bit   7   6   5   4   3   2   1   0
         0   0   0   0   R   F   T   A

         A: 1 = enable absolute tracking
         T: 1 = enable two finger mode auto correct
         F: 1 = disable ABS Position Filter
         R: 1 = enable real hardware resolution

Native absolute mode 6 byte packet format
-----------------------------------------

1 and 3 finger touch shares the same 6-byte packet format, except that
3 finger touch only reports the position of the center of all three fingers.

Firmware would send 12 bytes of data for 2 finger touch.

Note on debounce:
In case the box has unstable power supply or other electricity issues, or
when number of finger changes, F/W would send "debounce packet" to inform
driver that the hardware is in debounce status.
The debounce packet has the following signature::

    byte 0: 0xc4
    byte 1: 0xff
    byte 2: 0xff
    byte 3: 0x02
    byte 4: 0xff
    byte 5: 0xff

When we encounter this kind of packet, we just ignore it.

One/Three finger touch
^^^^^^^^^^^^^^^^^^^^^^

byte 0::

   bit   7   6   5   4   3   2   1   0
        n1  n0  w3  w2   0   1   R   L

        L, R = 1 when Left, Right mouse button pressed
        n1..n0 = number of fingers on touchpad

byte 1::

   bit   7   6   5   4   3   2   1   0
        p7  p6  p5  p4 x11 x10  x9  x8

byte 2::

   bit   7   6   5   4   3   2   1   0
        x7  x6  x5  x4  x3  x2  x1  x0

        x11..x0 = absolute x value (horizontal)

byte 3::

   bit   7   6   5   4   3   2   1   0
         0   0  w1  w0   0   0   1   0

         w3..w0 = width of the finger touch

byte 4::

   bit   7   6   5   4   3   2   1   0
        p3  p1  p2  p0  y11 y10 y9  y8

        p7..p0 = pressure

byte 5::

   bit   7   6   5   4   3   2   1   0
        y7  y6  y5  y4  y3  y2  y1  y0

        y11..y0 = absolute y value (vertical)

Two finger touch
^^^^^^^^^^^^^^^^

The packet format is exactly the same for two finger touch, except the hardware
sends two 6 byte packets. The first packet contains data for the first finger,
the second packet has data for the second finger. So for two finger touch a
total of 12 bytes are sent.

하드웨어 버전 4의 진정한 멀티터치

v4는 최대 5손가락을 개별 추적하는 진정한 멀티터치 터치패드입니다. PS/2 대역폭 한계 때문에 status, head, motion 패킷을 조합하는 복잡한 형식을 사용합니다.

손가락 수나 ID가 바뀌면 하드웨어가 어떤 손가락이 있는지 나타내는 status 패킷을 보낸 뒤 head 또는 motion 패킷을 보냅니다. Head는 손가락 ID, 절대 X/Y, 폭과 압력을 포함하고, motion은 두 손가락의 위치 변화량을 담습니다.

예를 들어 status가 두 손가락을 알리면 head 패킷 두 개가 뒤따릅니다. 상태가 바뀌지 않으면 다음 status까지 motion 패킷으로 변화량만 보냅니다. 예외적으로 한 손가락 상태 뒤에는 계속 head 패킷을 보냅니다.

Motion의 `w`는 변화량이 +127보다 크거나 -128보다 작아 overflow했음을 나타냅니다. 이때 펌웨어는 `delta x / 5`, `delta y / 5`를 보냅니다. 바이트 0~2는 한 손가락, 바이트 3~5는 다른 손가락에 해당합니다.

Hardware version 4
~~~~~~~~~~~~~~~~~~

Registers
---------

* reg_07::

   bit   7   6   5   4   3   2   1   0
         0   0   0   0   0   0   0   A

         A: 1 = enable absolute tracking

Native absolute mode 6 byte packet format
-----------------------------------------

v4 hardware is a true multitouch touchpad, capable of tracking up to 5 fingers.
Unfortunately, due to PS/2's limited bandwidth, its packet format is rather
complex.

Whenever the numbers or identities of the fingers changes, the hardware sends a
status packet to indicate how many and which fingers is on touchpad, followed by
head packets or motion packets. A head packet contains data of finger id, finger
position (absolute x, y values), width, and pressure. A motion packet contains
two fingers' position delta.

For example, when status packet tells there are 2 fingers on touchpad, then we
can expect two following head packets. If the finger status doesn't change,
the following packets would be motion packets, only sending delta of finger
position, until we receive a status packet.

One exception is one finger touch. when a status packet tells us there is only
one finger, the hardware would just send head packets afterwards.

Status packet
^^^^^^^^^^^^^

byte 0::

   bit   7   6   5   4   3   2   1   0
         .   .   .   .   0   1   R   L

         L, R = 1 when Left, Right mouse button pressed

byte 1::

   bit   7   6   5   4   3   2   1   0
         .   .   . ft4 ft3 ft2 ft1 ft0

         ft4 ft3 ft2 ft1 ft0 ftn = 1 when finger n is on touchpad

byte 2::

   not used

byte 3::

   bit   7   6   5   4   3   2   1   0
         .   .   .   1   0   0   0   0

         constant bits

byte 4::

   bit   7   6   5   4   3   2   1   0
         p   .   .   .   .   .   .   .

         p = 1 for palm

byte 5::

   not used

Head packet
^^^^^^^^^^^

byte 0::

   bit   7   6   5   4   3   2   1   0
        w3  w2  w1  w0   0   1   R   L

        L, R = 1 when Left, Right mouse button pressed
        w3..w0 = finger width (spans how many trace lines)

byte 1::

   bit   7   6   5   4   3   2   1   0
        p7  p6  p5  p4 x11 x10  x9  x8

byte 2::

   bit   7   6   5   4   3   2   1   0
        x7  x6  x5  x4  x3  x2  x1  x0

        x11..x0 = absolute x value (horizontal)

byte 3::

   bit   7   6   5   4   3   2   1   0
       id2 id1 id0   1   0   0   0   1

       id2..id0 = finger id

byte 4::

   bit   7   6   5   4   3   2   1   0
        p3  p1  p2  p0  y11 y10 y9  y8

        p7..p0 = pressure

byte 5::

   bit   7   6   5   4   3   2   1   0
        y7  y6  y5  y4  y3  y2  y1  y0

        y11..y0 = absolute y value (vertical)

Motion packet
^^^^^^^^^^^^^

byte 0::

   bit   7   6   5   4   3   2   1   0
       id2 id1 id0   w   0   1   R   L

       L, R = 1 when Left, Right mouse button pressed
       id2..id0 = finger id
       w = 1 when delta overflows (> 127 or < -128), in this case
       firmware sends us (delta x / 5) and (delta y  / 5)

byte 1::

   bit   7   6   5   4   3   2   1   0
        x7  x6  x5  x4  x3  x2  x1  x0

        x7..x0 = delta x (two's complement)

byte 2::

   bit   7   6   5   4   3   2   1   0
        y7  y6  y5  y4  y3  y2  y1  y0

        y7..y0 = delta y (two's complement)

byte 3::

   bit   7   6   5   4   3   2   1   0
       id2 id1 id0   1   0   0   1   0

       id2..id0 = finger id

byte 4::

   bit   7   6   5   4   3   2   1   0
        x7  x6  x5  x4  x3  x2  x1  x0

        x7..x0 = delta x (two's complement)

byte 5::

   bit   7   6   5   4   3   2   1   0
        y7  y6  y5  y4  y3  y2  y1  y0

        y7..y0 = delta y (two's complement)

        byte 0 ~ 2 for one finger
        byte 3 ~ 5 for another

v3·v4 트랙포인트 상대 패킷

일부 하드웨어 v3와 v4의 트랙포인트에는 확인된 전용 레지스터가 없습니다. 상대 모드에서 6바이트 status 패킷을 사용합니다.

X와 Y는 9비트에 걸친 2의 보수입니다. `sx`·`sy`가 최상위 상대 부호 비트이고 `x7..x0`, `y7..y0`가 하위 비트입니다. `~sx`와 `~sy`는 각각 부호 비트의 반전값입니다.

트랙포인트 Y 부호는 Linux input 드라이버가 상대 이동에 기대하는 방향과 반대이므로 드라이버가 방향을 반전해 전달해야 합니다.

Trackpoint (for Hardware version 3 and 4)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Registers
---------

No special registers have been identified.

Native relative mode 6 byte packet format
-----------------------------------------

Status Packet
^^^^^^^^^^^^^

byte 0::

   bit   7   6   5   4   3   2   1   0
         0   0  sx  sy   0   M   R   L

byte 1::

   bit   7   6   5   4   3   2   1   0
       ~sx   0   0   0   0   0   0   0

byte 2::

   bit   7   6   5   4   3   2   1   0
       ~sy   0   0   0   0   0   0   0

byte 3::

   bit   7   6   5   4   3   2   1   0
         0   0 ~sy ~sx   0   1   1   0

byte 4::

   bit   7   6   5   4   3   2   1   0
        x7  x6  x5  x4  x3  x2  x1  x0

byte 5::

   bit   7   6   5   4   3   2   1   0
        y7  y6  y5  y4  y3  y2  y1  y0


         x and y are written in two's complement spread
             over 9 bits with sx/sy the relative top bit and
             x7..x0 and y7..y0 the lower bits.
         ~sx is the inverse of sx, ~sy is the inverse of sy.
         The sign of y is opposite to what the input driver
             expects for a relative movement