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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