Documentation/input/elantech.txt

   1 Elantech Touchpad Driver
   2 ========================
   3
   4         Copyright (C) 2007-2008 Arjan Opmeer <arjan@opmeer.net>
   5
   6         Extra information for hardware version 1 found and
   7         provided by Steve Havelka
   8
   9         Version 2 (EeePC) hardware support based on patches
  10         received from Woody at Xandros and forwarded to me
  11         by user StewieGriffin at the eeeuser.com forum
  12
  13
  14 Contents
  15 ~~~~~~~~
  16
  17  1. Introduction
  18  2. Extra knobs
  19  3. Hardware version 1
  20     3.1 Registers
  21     3.2 Native relative mode 4 byte packet format
  22     3.3 Native absolute mode 4 byte packet format
  23  4. Hardware version 2
  24     4.1 Registers
  25     4.2 Native absolute mode 6 byte packet format
  26         4.2.1 One finger touch
  27         4.2.2 Two finger touch
  28
  29
  30
  31 1. Introduction
  32    ~~~~~~~~~~~~
  33
  34 Currently the Linux Elantech touchpad driver is aware of two different
  35 hardware versions unimaginatively called version 1 and version 2. Version 1
  36 is found in "older" laptops and uses 4 bytes per packet. Version 2 seems to
  37 be introduced with the EeePC and uses 6 bytes per packet.
  38
  39 The driver tries to support both hardware versions and should be compatible
  40 with the Xorg Synaptics touchpad driver and its graphical configuration
  41 utilities.
  42
  43 Additionally the operation of the touchpad can be altered by adjusting the
  44 contents of some of its internal registers. These registers are represented
  45 by the driver as sysfs entries under /sys/bus/serio/drivers/psmouse/serio?
  46 that can be read from and written to.
  47
  48 Currently only the registers for hardware version 1 are somewhat understood.
  49 Hardware version 2 seems to use some of the same registers but it is not
  50 known whether the bits in the registers represent the same thing or might
  51 have changed their meaning.
  52
  53 On top of that, some register settings have effect only when the touchpad is
  54 in relative mode and not in absolute mode. As the Linux Elantech touchpad
  55 driver always puts the hardware into absolute mode not all information
  56 mentioned below can be used immediately. But because there is no freely
  57 available Elantech documentation the information is provided here anyway for
  58 completeness sake.
  59
  60
  61 /////////////////////////////////////////////////////////////////////////////
  62
  63
  64 2. Extra knobs
  65    ~~~~~~~~~~~
  66
  67 Currently the Linux Elantech touchpad driver provides two extra knobs under
  68 /sys/bus/serio/drivers/psmouse/serio? for the user.
  69
  70 * debug
  71
  72    Turn different levels of debugging ON or OFF.
  73
  74    By echoing "0" to this file all debugging will be turned OFF.
  75
  76    Currently a value of "1" will turn on some basic debugging and a value of
  77    "2" will turn on packet debugging. For hardware version 1 the default is
  78    OFF. For version 2 the default is "1".
  79
  80    Turning packet debugging on will make the driver dump every packet
  81    received to the syslog before processing it. Be warned that this can
  82    generate quite a lot of data!
  83
  84 * paritycheck
  85
  86    Turns parity checking ON or OFF.
  87
  88    By echoing "0" to this file parity checking will be turned OFF. Any
  89    non-zero value will turn it ON. For hardware version 1 the default is ON.
  90    For version 2 the default it is OFF.
  91
  92    Hardware version 1 provides basic data integrity verification by
  93    calculating a parity bit for the last 3 bytes of each packet. The driver
  94    can check these bits and reject any packet that appears corrupted. Using
  95    this knob you can bypass that check.
  96
  97    It is not known yet whether hardware version 2 provides the same parity
  98    bits. Hence checking is disabled by default. Currently even turning it on
  99    will do nothing.
 100
 101
 102 /////////////////////////////////////////////////////////////////////////////
 103
 104
 105 3. Hardware version 1
 106    ==================
 107
 108 3.1 Registers
 109     ~~~~~~~~~
 110
 111 By echoing a hexadecimal value to a register it contents can be altered.
 112
 113 For example:
 114
 115    echo -n 0x16 > reg_10
 116
 117 * reg_10
 118
 119    bit   7   6   5   4   3   2   1   0
 120          B   C   T   D   L   A   S   E
 121
 122          E: 1 = enable smart edges unconditionally
 123          S: 1 = enable smart edges only when dragging
 124          A: 1 = absolute mode (needs 4 byte packets, see reg_11)
 125          L: 1 = enable drag lock (see reg_22)
 126          D: 1 = disable dynamic resolution
 127          T: 1 = disable tapping
 128          C: 1 = enable corner tap
 129          B: 1 = swap left and right button
 130
 131 * reg_11
 132
 133    bit   7   6   5   4   3   2   1   0
 134          1   0   0   H   V   1   F   P
 135
 136          P: 1 = enable parity checking for relative mode
 137          F: 1 = enable native 4 byte packet mode
 138          V: 1 = enable vertical scroll area
 139          H: 1 = enable horizontal scroll area
 140
 141 * reg_20
 142
 143          single finger width?
 144
 145 * reg_21
 146
 147          scroll area width (small: 0x40 ... wide: 0xff)
 148
 149 * reg_22
 150
 151          drag lock time out (short: 0x14 ... long: 0xfe;
 152                              0xff = tap again to release)
 153
 154 * reg_23
 155
 156          tap make timeout?
 157
 158 * reg_24
 159
 160          tap release timeout?
 161
 162 * reg_25
 163
 164          smart edge cursor speed (0x02 = slow, 0x03 = medium, 0x04 = fast)
 165
 166 * reg_26
 167
 168          smart edge activation area width?
 169
 170
 171 3.2 Native relative mode 4 byte packet format
 172     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 173
 174 byte 0:
 175    bit   7   6   5   4   3   2   1   0
 176          c   c  p2  p1   1   M   R   L
 177
 178          L, R, M = 1 when Left, Right, Middle mouse button pressed
 179             some models have M as byte 3 odd parity bit
 180          when parity checking is enabled (reg_11, P = 1):
 181             p1..p2 = byte 1 and 2 odd parity bit
 182          c = 1 when corner tap detected
 183
 184 byte 1:
 185    bit   7   6   5   4   3   2   1   0
 186         dx7 dx6 dx5 dx4 dx3 dx2 dx1 dx0
 187
 188          dx7..dx0 = x movement;   positive = right, negative = left
 189          byte 1 = 0xf0 when corner tap detected
 190
 191 byte 2:
 192    bit   7   6   5   4   3   2   1   0
 193         dy7 dy6 dy5 dy4 dy3 dy2 dy1 dy0
 194
 195          dy7..dy0 = y movement;   positive = up,    negative = down
 196
 197 byte 3:
 198    parity checking enabled (reg_11, P = 1):
 199
 200       bit   7   6   5   4   3   2   1   0
 201             w   h  n1  n0  ds3 ds2 ds1 ds0
 202
 203             normally:
 204                ds3..ds0 = scroll wheel amount and direction
 205                           positive = down or left
 206                           negative = up or right
 207             when corner tap detected:
 208                ds0 = 1 when top right corner tapped
 209                ds1 = 1 when bottom right corner tapped
 210                ds2 = 1 when bottom left corner tapped
 211                ds3 = 1 when top left corner tapped
 212             n1..n0 = number of fingers on touchpad
 213                only models with firmware 2.x report this, models with
 214                firmware 1.x seem to map one, two and three finger taps
 215                directly to L, M and R mouse buttons
 216             h = 1 when horizontal scroll action
 217             w = 1 when wide finger touch?
 218
 219    otherwise (reg_11, P = 0):
 220
 221       bit   7   6   5   4   3   2   1   0
 222            ds7 ds6 ds5 ds4 ds3 ds2 ds1 ds0
 223
 224             ds7..ds0 = vertical scroll amount and direction
 225                        negative = up
 226                        positive = down
 227
 228
 229 3.3 Native absolute mode 4 byte packet format
 230     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 231
 232 byte 0:
 233    firmware version 1.x:
 234
 235       bit   7   6   5   4   3   2   1   0
 236             D   U  p1  p2   1  p3   R   L
 237
 238             L, R = 1 when Left, Right mouse button pressed
 239             p1..p3 = byte 1..3 odd parity bit
 240             D, U = 1 when rocker switch pressed Up, Down
 241
 242    firmware version 2.x:
 243
 244       bit   7   6   5   4   3   2   1   0
 245            n1  n0  p2  p1   1  p3   R   L
 246
 247             L, R = 1 when Left, Right mouse button pressed
 248             p1..p3 = byte 1..3 odd parity bit
 249             n1..n0 = number of fingers on touchpad
 250
 251 byte 1:
 252    firmware version 1.x:
 253
 254       bit   7   6   5   4   3   2   1   0
 255             f   0  th  tw  x9  x8  y9  y8
 256
 257             tw = 1 when two finger touch
 258             th = 1 when three finger touch
 259             f  = 1 when finger touch
 260
 261    firmware version 2.x:
 262
 263       bit   7   6   5   4   3   2   1   0
 264             .   .   .   .  x9  x8  y9  y8
 265
 266 byte 2:
 267    bit   7   6   5   4   3   2   1   0
 268         x7  x6  x5  x4  x3  x2  x1  x0
 269
 270          x9..x0 = absolute x value (horizontal)
 271
 272 byte 3:
 273    bit   7   6   5   4   3   2   1   0
 274         y7  y6  y5  y4  y3  y2  y1  y0
 275
 276          y9..y0 = absolute y value (vertical)
 277
 278
 279 /////////////////////////////////////////////////////////////////////////////
 280
 281
 282 4. Hardware version 2
 283    ==================
 284
 285
 286 4.1 Registers
 287     ~~~~~~~~~
 288
 289 By echoing a hexadecimal value to a register it contents can be altered.
 290
 291 For example:
 292
 293    echo -n 0x56 > reg_10
 294
 295 * reg_10
 296
 297    bit   7   6   5   4   3   2   1   0
 298          0   1   0   1   0   1   D   0
 299
 300          D: 1 = enable drag and drop
 301
 302 * reg_11
 303
 304    bit   7   6   5   4   3   2   1   0
 305          1   0   0   0   S   0   1   0
 306
 307          S: 1 = enable vertical scroll
 308
 309 * reg_21
 310
 311          unknown (0x00)
 312
 313 * reg_22
 314
 315          drag and drop release time out (short: 0x70 ... long 0x7e;
 316                                    0x7f = never i.e. tap again to release)
 317
 318
 319 4.2 Native absolute mode 6 byte packet format
 320     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 321
 322 4.2.1 One finger touch
 323       ~~~~~~~~~~~~~~~~
 324
 325 byte 0:
 326
 327    bit   7   6   5   4   3   2   1   0
 328         n1  n0   .   .   .   .   R   L
 329
 330          L, R = 1 when Left, Right mouse button pressed
 331          n1..n0 = numbers of fingers on touchpad
 332
 333 byte 1:
 334
 335    bit   7   6   5   4   3   2   1   0
 336         x15 x14 x13 x12 x11 x10 x9  x8
 337
 338 byte 2:
 339
 340    bit   7   6   5   4   3   2   1   0
 341         x7  x6  x5  x4  x4  x2  x1  x0
 342
 343          x15..x0 = absolute x value (horizontal)
 344
 345 byte 3:
 346
 347    bit   7   6   5   4   3   2   1   0
 348          .   .   .   .   .   .   .   .
 349
 350 byte 4:
 351
 352    bit   7   6   5   4   3   2   1   0
 353         y15 y14 y13 y12 y11 y10 y8  y8
 354
 355 byte 5:
 356
 357    bit   7   6   5   4   3   2   1   0
 358         y7  y6  y5  y4  y3  y2  y1  y0
 359
 360          y15..y0 = absolute y value (vertical)
 361
 362
 363 4.2.2 Two finger touch
 364       ~~~~~~~~~~~~~~~~
 365
 366 byte 0:
 367
 368    bit   7   6   5   4   3   2   1   0
 369         n1  n0  ay8 ax8  .   .   R   L
 370
 371          L, R = 1 when Left, Right mouse button pressed
 372          n1..n0 = numbers of fingers on touchpad
 373
 374 byte 1:
 375
 376    bit   7   6   5   4   3   2   1   0
 377         ax7 ax6 ax5 ax4 ax3 ax2 ax1 ax0
 378
 379          ax8..ax0 = first finger absolute x value
 380
 381 byte 2:
 382
 383    bit   7   6   5   4   3   2   1   0
 384         ay7 ay6 ay5 ay4 ay3 ay2 ay1 ay0
 385
 386          ay8..ay0 = first finger absolute y value
 387
 388 byte 3:
 389
 390    bit   7   6   5   4   3   2   1   0
 391          .   .  by8 bx8  .   .   .   .
 392
 393 byte 4:
 394
 395    bit   7   6   5   4   3   2   1   0
 396         bx7 bx6 bx5 bx4 bx3 bx2 bx1 bx0
 397
 398          bx8..bx0 = second finger absolute x value
 399
 400 byte 5:
 401
 402    bit   7   6   5   4   3   2   1   0
 403         by7 by8 by5 by4 by3 by2 by1 by0
 404
 405          by8..by0 = second finger absolute y value