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+Elantech Touchpad Driver
+========================
+
+        Copyright (C) 2007-2008 Arjan Opmeer <arjan@opmeer.net>
+
+        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. Hardware version 1
+    3.1 Registers
+    3.2 Native relative mode 4 byte packet format
+    3.3 Native absolute mode 4 byte packet format
+ 4. Hardware version 2
+    4.1 Registers
+    4.2 Native absolute mode 6 byte packet format
+        4.2.1 One finger touch
+        4.2.2 Two finger touch
+
+
+
+1. Introduction
+   ~~~~~~~~~~~~
+
+Currently the Linux Elantech touchpad driver is aware of two different
+hardware versions unimaginatively called version 1 and version 2. 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.
+
+The driver tries to support both hardware versions and should be compatible
+with the Xorg Synaptics touchpad driver and its graphical configuration
+utilities.
+
+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.
+
+
+/////////////////////////////////////////////////////////////////////////////
+
+
+2. Extra knobs
+   ~~~~~~~~~~~
+
+Currently the Linux Elantech touchpad driver provides two 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.
+
+   It is not known yet whether hardware version 2 provides the same parity
+   bits. Hence checking is disabled by default. Currently even turning it on
+   will do nothing.
+
+
+/////////////////////////////////////////////////////////////////////////////
+
+
+3. Hardware version 1
+   ==================
+
+3.1 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?
+
+
+3.2 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
+
+
+3.3 Native absolute mode 4 byte packet format
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+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)
+
+
+/////////////////////////////////////////////////////////////////////////////
+
+
+4. Hardware version 2
+   ==================
+
+
+4.1 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)
+
+
+4.2 Native absolute mode 6 byte packet format
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+4.2.1 One finger touch
+      ~~~~~~~~~~~~~~~~
+
+byte 0:
+
+   bit   7   6   5   4   3   2   1   0
+        n1  n0   .   .   .   .   R   L
+
+         L, R = 1 when Left, Right mouse button pressed
+         n1..n0 = numbers of fingers on touchpad
+
+byte 1:
+
+   bit   7   6   5   4   3   2   1   0
+        x15 x14 x13 x12 x11 x10 x9  x8
+
+byte 2:
+
+   bit   7   6   5   4   3   2   1   0
+        x7  x6  x5  x4  x4  x2  x1  x0
+
+         x15..x0 = absolute x value (horizontal)
+
+byte 3:
+
+   bit   7   6   5   4   3   2   1   0
+         .   .   .   .   .   .   .   .
+
+byte 4:
+
+   bit   7   6   5   4   3   2   1   0
+        y15 y14 y13 y12 y11 y10 y8  y8
+
+byte 5:
+
+   bit   7   6   5   4   3   2   1   0
+        y7  y6  y5  y4  y3  y2  y1  y0
+
+         y15..y0 = absolute y value (vertical)
+
+
+4.2.2 Two finger touch
+      ~~~~~~~~~~~~~~~~
+
+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 = numbers 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 = first 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 = first 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 = second 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 = second finger absolute y value