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