linux/Documentation/laptops/thinkpad-acpi.txt
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   1                     ThinkPad ACPI Extras Driver
   2
   3                            Version 0.25
   4                        October 16th,  2013
   5
   6               Borislav Deianov <borislav@users.sf.net>
   7             Henrique de Moraes Holschuh <hmh@hmh.eng.br>
   8                      http://ibm-acpi.sf.net/
   9
  10
  11This is a Linux driver for the IBM and Lenovo ThinkPad laptops. It
  12supports various features of these laptops which are accessible
  13through the ACPI and ACPI EC framework, but not otherwise fully
  14supported by the generic Linux ACPI drivers.
  15
  16This driver used to be named ibm-acpi until kernel 2.6.21 and release
  170.13-20070314.  It used to be in the drivers/acpi tree, but it was
  18moved to the drivers/misc tree and renamed to thinkpad-acpi for kernel
  192.6.22, and release 0.14.  It was moved to drivers/platform/x86 for
  20kernel 2.6.29 and release 0.22.
  21
  22The driver is named "thinkpad-acpi".  In some places, like module
  23names and log messages, "thinkpad_acpi" is used because of userspace
  24issues.
  25
  26"tpacpi" is used as a shorthand where "thinkpad-acpi" would be too
  27long due to length limitations on some Linux kernel versions.
  28
  29Status
  30------
  31
  32The features currently supported are the following (see below for
  33detailed description):
  34
  35        - Fn key combinations
  36        - Bluetooth enable and disable
  37        - video output switching, expansion control
  38        - ThinkLight on and off
  39        - CMOS/UCMS control
  40        - LED control
  41        - ACPI sounds
  42        - temperature sensors
  43        - Experimental: embedded controller register dump
  44        - LCD brightness control
  45        - Volume control
  46        - Fan control and monitoring: fan speed, fan enable/disable
  47        - WAN enable and disable
  48        - UWB enable and disable
  49
  50A compatibility table by model and feature is maintained on the web
  51site, http://ibm-acpi.sf.net/. I appreciate any success or failure
  52reports, especially if they add to or correct the compatibility table.
  53Please include the following information in your report:
  54
  55        - ThinkPad model name
  56        - a copy of your ACPI tables, using the "acpidump" utility
  57        - a copy of the output of dmidecode, with serial numbers
  58          and UUIDs masked off
  59        - which driver features work and which don't
  60        - the observed behavior of non-working features
  61
  62Any other comments or patches are also more than welcome.
  63
  64
  65Installation
  66------------
  67
  68If you are compiling this driver as included in the Linux kernel
  69sources, look for the CONFIG_THINKPAD_ACPI Kconfig option.
  70It is located on the menu path: "Device Drivers" -> "X86 Platform
  71Specific Device Drivers" -> "ThinkPad ACPI Laptop Extras".
  72
  73
  74Features
  75--------
  76
  77The driver exports two different interfaces to userspace, which can be
  78used to access the features it provides.  One is a legacy procfs-based
  79interface, which will be removed at some time in the future.  The other
  80is a new sysfs-based interface which is not complete yet.
  81
  82The procfs interface creates the /proc/acpi/ibm directory.  There is a
  83file under that directory for each feature it supports.  The procfs
  84interface is mostly frozen, and will change very little if at all: it
  85will not be extended to add any new functionality in the driver, instead
  86all new functionality will be implemented on the sysfs interface.
  87
  88The sysfs interface tries to blend in the generic Linux sysfs subsystems
  89and classes as much as possible.  Since some of these subsystems are not
  90yet ready or stabilized, it is expected that this interface will change,
  91and any and all userspace programs must deal with it.
  92
  93
  94Notes about the sysfs interface:
  95
  96Unlike what was done with the procfs interface, correctness when talking
  97to the sysfs interfaces will be enforced, as will correctness in the
  98thinkpad-acpi's implementation of sysfs interfaces.
  99
 100Also, any bugs in the thinkpad-acpi sysfs driver code or in the
 101thinkpad-acpi's implementation of the sysfs interfaces will be fixed for
 102maximum correctness, even if that means changing an interface in
 103non-compatible ways.  As these interfaces mature both in the kernel and
 104in thinkpad-acpi, such changes should become quite rare.
 105
 106Applications interfacing to the thinkpad-acpi sysfs interfaces must
 107follow all sysfs guidelines and correctly process all errors (the sysfs
 108interface makes extensive use of errors).  File descriptors and open /
 109close operations to the sysfs inodes must also be properly implemented.
 110
 111The version of thinkpad-acpi's sysfs interface is exported by the driver
 112as a driver attribute (see below).
 113
 114Sysfs driver attributes are on the driver's sysfs attribute space,
 115for 2.6.23+ this is /sys/bus/platform/drivers/thinkpad_acpi/ and
 116/sys/bus/platform/drivers/thinkpad_hwmon/
 117
 118Sysfs device attributes are on the thinkpad_acpi device sysfs attribute
 119space, for 2.6.23+ this is /sys/devices/platform/thinkpad_acpi/.
 120
 121Sysfs device attributes for the sensors and fan are on the
 122thinkpad_hwmon device's sysfs attribute space, but you should locate it
 123looking for a hwmon device with the name attribute of "thinkpad", or
 124better yet, through libsensors.
 125
 126
 127Driver version
 128--------------
 129
 130procfs: /proc/acpi/ibm/driver
 131sysfs driver attribute: version
 132
 133The driver name and version. No commands can be written to this file.
 134
 135
 136Sysfs interface version
 137-----------------------
 138
 139sysfs driver attribute: interface_version
 140
 141Version of the thinkpad-acpi sysfs interface, as an unsigned long
 142(output in hex format: 0xAAAABBCC), where:
 143        AAAA - major revision
 144        BB - minor revision
 145        CC - bugfix revision
 146
 147The sysfs interface version changelog for the driver can be found at the
 148end of this document.  Changes to the sysfs interface done by the kernel
 149subsystems are not documented here, nor are they tracked by this
 150attribute.
 151
 152Changes to the thinkpad-acpi sysfs interface are only considered
 153non-experimental when they are submitted to Linux mainline, at which
 154point the changes in this interface are documented and interface_version
 155may be updated.  If you are using any thinkpad-acpi features not yet
 156sent to mainline for merging, you do so on your own risk: these features
 157may disappear, or be implemented in a different and incompatible way by
 158the time they are merged in Linux mainline.
 159
 160Changes that are backwards-compatible by nature (e.g. the addition of
 161attributes that do not change the way the other attributes work) do not
 162always warrant an update of interface_version.  Therefore, one must
 163expect that an attribute might not be there, and deal with it properly
 164(an attribute not being there *is* a valid way to make it clear that a
 165feature is not available in sysfs).
 166
 167
 168Hot keys
 169--------
 170
 171procfs: /proc/acpi/ibm/hotkey
 172sysfs device attribute: hotkey_*
 173
 174In a ThinkPad, the ACPI HKEY handler is responsible for communicating
 175some important events and also keyboard hot key presses to the operating
 176system.  Enabling the hotkey functionality of thinkpad-acpi signals the
 177firmware that such a driver is present, and modifies how the ThinkPad
 178firmware will behave in many situations.
 179
 180The driver enables the HKEY ("hot key") event reporting automatically
 181when loaded, and disables it when it is removed.
 182
 183The driver will report HKEY events in the following format:
 184
 185        ibm/hotkey HKEY 00000080 0000xxxx
 186
 187Some of these events refer to hot key presses, but not all of them.
 188
 189The driver will generate events over the input layer for hot keys and
 190radio switches, and over the ACPI netlink layer for other events.  The
 191input layer support accepts the standard IOCTLs to remap the keycodes
 192assigned to each hot key.
 193
 194The hot key bit mask allows some control over which hot keys generate
 195events.  If a key is "masked" (bit set to 0 in the mask), the firmware
 196will handle it.  If it is "unmasked", it signals the firmware that
 197thinkpad-acpi would prefer to handle it, if the firmware would be so
 198kind to allow it (and it often doesn't!).
 199
 200Not all bits in the mask can be modified.  Not all bits that can be
 201modified do anything.  Not all hot keys can be individually controlled
 202by the mask.  Some models do not support the mask at all.  The behaviour
 203of the mask is, therefore, highly dependent on the ThinkPad model.
 204
 205The driver will filter out any unmasked hotkeys, so even if the firmware
 206doesn't allow disabling an specific hotkey, the driver will not report
 207events for unmasked hotkeys.
 208
 209Note that unmasking some keys prevents their default behavior.  For
 210example, if Fn+F5 is unmasked, that key will no longer enable/disable
 211Bluetooth by itself in firmware.
 212
 213Note also that not all Fn key combinations are supported through ACPI
 214depending on the ThinkPad model and firmware version.  On those
 215ThinkPads, it is still possible to support some extra hotkeys by
 216polling the "CMOS NVRAM" at least 10 times per second.  The driver
 217attempts to enables this functionality automatically when required.
 218
 219procfs notes:
 220
 221The following commands can be written to the /proc/acpi/ibm/hotkey file:
 222
 223        echo 0xffffffff > /proc/acpi/ibm/hotkey -- enable all hot keys
 224        echo 0 > /proc/acpi/ibm/hotkey -- disable all possible hot keys
 225        ... any other 8-hex-digit mask ...
 226        echo reset > /proc/acpi/ibm/hotkey -- restore the recommended mask
 227
 228The following commands have been deprecated and will cause the kernel
 229to log a warning:
 230
 231        echo enable > /proc/acpi/ibm/hotkey -- does nothing
 232        echo disable > /proc/acpi/ibm/hotkey -- returns an error
 233
 234The procfs interface does not support NVRAM polling control.  So as to
 235maintain maximum bug-to-bug compatibility, it does not report any masks,
 236nor does it allow one to manipulate the hot key mask when the firmware
 237does not support masks at all, even if NVRAM polling is in use.
 238
 239sysfs notes:
 240
 241        hotkey_bios_enabled:
 242                DEPRECATED, WILL BE REMOVED SOON.
 243
 244                Returns 0.
 245
 246        hotkey_bios_mask:
 247                DEPRECATED, DON'T USE, WILL BE REMOVED IN THE FUTURE.
 248
 249                Returns the hot keys mask when thinkpad-acpi was loaded.
 250                Upon module unload, the hot keys mask will be restored
 251                to this value.   This is always 0x80c, because those are
 252                the hotkeys that were supported by ancient firmware
 253                without mask support.
 254
 255        hotkey_enable:
 256                DEPRECATED, WILL BE REMOVED SOON.
 257
 258                0: returns -EPERM
 259                1: does nothing
 260
 261        hotkey_mask:
 262                bit mask to enable reporting (and depending on
 263                the firmware, ACPI event generation) for each hot key
 264                (see above).  Returns the current status of the hot keys
 265                mask, and allows one to modify it.
 266
 267        hotkey_all_mask:
 268                bit mask that should enable event reporting for all
 269                supported hot keys, when echoed to hotkey_mask above.
 270                Unless you know which events need to be handled
 271                passively (because the firmware *will* handle them
 272                anyway), do *not* use hotkey_all_mask.  Use
 273                hotkey_recommended_mask, instead. You have been warned.
 274
 275        hotkey_recommended_mask:
 276                bit mask that should enable event reporting for all
 277                supported hot keys, except those which are always
 278                handled by the firmware anyway.  Echo it to
 279                hotkey_mask above, to use.  This is the default mask
 280                used by the driver.
 281
 282        hotkey_source_mask:
 283                bit mask that selects which hot keys will the driver
 284                poll the NVRAM for.  This is auto-detected by the driver
 285                based on the capabilities reported by the ACPI firmware,
 286                but it can be overridden at runtime.
 287
 288                Hot keys whose bits are set in hotkey_source_mask are
 289                polled for in NVRAM, and reported as hotkey events if
 290                enabled in hotkey_mask.  Only a few hot keys are
 291                available through CMOS NVRAM polling.
 292
 293                Warning: when in NVRAM mode, the volume up/down/mute
 294                keys are synthesized according to changes in the mixer,
 295                which uses a single volume up or volume down hotkey
 296                press to unmute, as per the ThinkPad volume mixer user
 297                interface.  When in ACPI event mode, volume up/down/mute
 298                events are reported by the firmware and can behave
 299                differently (and that behaviour changes with firmware
 300                version -- not just with firmware models -- as well as
 301                OSI(Linux) state).
 302
 303        hotkey_poll_freq:
 304                frequency in Hz for hot key polling. It must be between
 305                0 and 25 Hz.  Polling is only carried out when strictly
 306                needed.
 307
 308                Setting hotkey_poll_freq to zero disables polling, and
 309                will cause hot key presses that require NVRAM polling
 310                to never be reported.
 311
 312                Setting hotkey_poll_freq too low may cause repeated
 313                pressings of the same hot key to be misreported as a
 314                single key press, or to not even be detected at all.
 315                The recommended polling frequency is 10Hz.
 316
 317        hotkey_radio_sw:
 318                If the ThinkPad has a hardware radio switch, this
 319                attribute will read 0 if the switch is in the "radios
 320                disabled" position, and 1 if the switch is in the
 321                "radios enabled" position.
 322
 323                This attribute has poll()/select() support.
 324
 325        hotkey_tablet_mode:
 326                If the ThinkPad has tablet capabilities, this attribute
 327                will read 0 if the ThinkPad is in normal mode, and
 328                1 if the ThinkPad is in tablet mode.
 329
 330                This attribute has poll()/select() support.
 331
 332        wakeup_reason:
 333                Set to 1 if the system is waking up because the user
 334                requested a bay ejection.  Set to 2 if the system is
 335                waking up because the user requested the system to
 336                undock.  Set to zero for normal wake-ups or wake-ups
 337                due to unknown reasons.
 338
 339                This attribute has poll()/select() support.
 340
 341        wakeup_hotunplug_complete:
 342                Set to 1 if the system was waken up because of an
 343                undock or bay ejection request, and that request
 344                was successfully completed.  At this point, it might
 345                be useful to send the system back to sleep, at the
 346                user's choice.  Refer to HKEY events 0x4003 and
 347                0x3003, below.
 348
 349                This attribute has poll()/select() support.
 350
 351input layer notes:
 352
 353A Hot key is mapped to a single input layer EV_KEY event, possibly
 354followed by an EV_MSC MSC_SCAN event that shall contain that key's scan
 355code.  An EV_SYN event will always be generated to mark the end of the
 356event block.
 357
 358Do not use the EV_MSC MSC_SCAN events to process keys.  They are to be
 359used as a helper to remap keys, only.  They are particularly useful when
 360remapping KEY_UNKNOWN keys.
 361
 362The events are available in an input device, with the following id:
 363
 364        Bus:            BUS_HOST
 365        vendor:         0x1014 (PCI_VENDOR_ID_IBM)  or
 366                        0x17aa (PCI_VENDOR_ID_LENOVO)
 367        product:        0x5054 ("TP")
 368        version:        0x4101
 369
 370The version will have its LSB incremented if the keymap changes in a
 371backwards-compatible way.  The MSB shall always be 0x41 for this input
 372device.  If the MSB is not 0x41, do not use the device as described in
 373this section, as it is either something else (e.g. another input device
 374exported by a thinkpad driver, such as HDAPS) or its functionality has
 375been changed in a non-backwards compatible way.
 376
 377Adding other event types for other functionalities shall be considered a
 378backwards-compatible change for this input device.
 379
 380Thinkpad-acpi Hot Key event map (version 0x4101):
 381
 382ACPI    Scan
 383event   code    Key             Notes
 384
 3850x1001  0x00    FN+F1           -
 386
 3870x1002  0x01    FN+F2           IBM: battery (rare)
 388                                Lenovo: Screen lock
 389
 3900x1003  0x02    FN+F3           Many IBM models always report
 391                                this hot key, even with hot keys
 392                                disabled or with Fn+F3 masked
 393                                off
 394                                IBM: screen lock, often turns
 395                                off the ThinkLight as side-effect
 396                                Lenovo: battery
 397
 3980x1004  0x03    FN+F4           Sleep button (ACPI sleep button
 399                                semantics, i.e. sleep-to-RAM).
 400                                It always generates some kind
 401                                of event, either the hot key
 402                                event or an ACPI sleep button
 403                                event. The firmware may
 404                                refuse to generate further FN+F4
 405                                key presses until a S3 or S4 ACPI
 406                                sleep cycle is performed or some
 407                                time passes.
 408
 4090x1005  0x04    FN+F5           Radio.  Enables/disables
 410                                the internal Bluetooth hardware
 411                                and W-WAN card if left in control
 412                                of the firmware.  Does not affect
 413                                the WLAN card.
 414                                Should be used to turn on/off all
 415                                radios (Bluetooth+W-WAN+WLAN),
 416                                really.
 417
 4180x1006  0x05    FN+F6           -
 419
 4200x1007  0x06    FN+F7           Video output cycle.
 421                                Do you feel lucky today?
 422
 4230x1008  0x07    FN+F8           IBM: toggle screen expand
 424                                Lenovo: configure UltraNav,
 425                                or toggle screen expand
 426
 4270x1009  0x08    FN+F9           -
 428        ..      ..              ..
 4290x100B  0x0A    FN+F11          -
 430
 4310x100C  0x0B    FN+F12          Sleep to disk.  You are always
 432                                supposed to handle it yourself,
 433                                either through the ACPI event,
 434                                or through a hotkey event.
 435                                The firmware may refuse to
 436                                generate further FN+F12 key
 437                                press events until a S3 or S4
 438                                ACPI sleep cycle is performed,
 439                                or some time passes.
 440
 4410x100D  0x0C    FN+BACKSPACE    -
 4420x100E  0x0D    FN+INSERT       -
 4430x100F  0x0E    FN+DELETE       -
 444
 4450x1010  0x0F    FN+HOME         Brightness up.  This key is
 446                                always handled by the firmware
 447                                in IBM ThinkPads, even when
 448                                unmasked.  Just leave it alone.
 449                                For Lenovo ThinkPads with a new
 450                                BIOS, it has to be handled either
 451                                by the ACPI OSI, or by userspace.
 452                                The driver does the right thing,
 453                                never mess with this.
 4540x1011  0x10    FN+END          Brightness down.  See brightness
 455                                up for details.
 456
 4570x1012  0x11    FN+PGUP         ThinkLight toggle.  This key is
 458                                always handled by the firmware,
 459                                even when unmasked.
 460
 4610x1013  0x12    FN+PGDOWN       -
 462
 4630x1014  0x13    FN+SPACE        Zoom key
 464
 4650x1015  0x14    VOLUME UP       Internal mixer volume up. This
 466                                key is always handled by the
 467                                firmware, even when unmasked.
 468                                NOTE: Lenovo seems to be changing
 469                                this.
 4700x1016  0x15    VOLUME DOWN     Internal mixer volume up. This
 471                                key is always handled by the
 472                                firmware, even when unmasked.
 473                                NOTE: Lenovo seems to be changing
 474                                this.
 4750x1017  0x16    MUTE            Mute internal mixer. This
 476                                key is always handled by the
 477                                firmware, even when unmasked.
 478
 4790x1018  0x17    THINKPAD        ThinkPad/Access IBM/Lenovo key
 480
 4810x1019  0x18    unknown
 482..      ..      ..
 4830x1020  0x1F    unknown
 484
 485The ThinkPad firmware does not allow one to differentiate when most hot
 486keys are pressed or released (either that, or we don't know how to, yet).
 487For these keys, the driver generates a set of events for a key press and
 488immediately issues the same set of events for a key release.  It is
 489unknown by the driver if the ThinkPad firmware triggered these events on
 490hot key press or release, but the firmware will do it for either one, not
 491both.
 492
 493If a key is mapped to KEY_RESERVED, it generates no input events at all.
 494If a key is mapped to KEY_UNKNOWN, it generates an input event that
 495includes an scan code.  If a key is mapped to anything else, it will
 496generate input device EV_KEY events.
 497
 498In addition to the EV_KEY events, thinkpad-acpi may also issue EV_SW
 499events for switches:
 500
 501SW_RFKILL_ALL   T60 and later hardware rfkill rocker switch
 502SW_TABLET_MODE  Tablet ThinkPads HKEY events 0x5009 and 0x500A
 503
 504Non hotkey ACPI HKEY event map:
 505-------------------------------
 506
 507Events that are never propagated by the driver:
 508
 5090x2304          System is waking up from suspend to undock
 5100x2305          System is waking up from suspend to eject bay
 5110x2404          System is waking up from hibernation to undock
 5120x2405          System is waking up from hibernation to eject bay
 5130x5001          Lid closed
 5140x5002          Lid opened
 5150x5009          Tablet swivel: switched to tablet mode
 5160x500A          Tablet swivel: switched to normal mode
 5170x5010          Brightness level changed/control event
 5180x6000          KEYBOARD: Numlock key pressed
 5190x6005          KEYBOARD: Fn key pressed (TO BE VERIFIED)
 5200x7000          Radio Switch may have changed state
 521
 522
 523Events that are propagated by the driver to userspace:
 524
 5250x2313          ALARM: System is waking up from suspend because
 526                the battery is nearly empty
 5270x2413          ALARM: System is waking up from hibernation because
 528                the battery is nearly empty
 5290x3003          Bay ejection (see 0x2x05) complete, can sleep again
 5300x3006          Bay hotplug request (hint to power up SATA link when
 531                the optical drive tray is ejected)
 5320x4003          Undocked (see 0x2x04), can sleep again
 5330x4010          Docked into hotplug port replicator (non-ACPI dock)
 5340x4011          Undocked from hotplug port replicator (non-ACPI dock)
 5350x500B          Tablet pen inserted into its storage bay
 5360x500C          Tablet pen removed from its storage bay
 5370x6011          ALARM: battery is too hot
 5380x6012          ALARM: battery is extremely hot
 5390x6021          ALARM: a sensor is too hot
 5400x6022          ALARM: a sensor is extremely hot
 5410x6030          System thermal table changed
 5420x6040          Nvidia Optimus/AC adapter related (TO BE VERIFIED)
 543
 544Battery nearly empty alarms are a last resort attempt to get the
 545operating system to hibernate or shutdown cleanly (0x2313), or shutdown
 546cleanly (0x2413) before power is lost.  They must be acted upon, as the
 547wake up caused by the firmware will have negated most safety nets...
 548
 549When any of the "too hot" alarms happen, according to Lenovo the user
 550should suspend or hibernate the laptop (and in the case of battery
 551alarms, unplug the AC adapter) to let it cool down.  These alarms do
 552signal that something is wrong, they should never happen on normal
 553operating conditions.
 554
 555The "extremely hot" alarms are emergencies.  According to Lenovo, the
 556operating system is to force either an immediate suspend or hibernate
 557cycle, or a system shutdown.  Obviously, something is very wrong if this
 558happens.
 559
 560
 561Brightness hotkey notes:
 562
 563Don't mess with the brightness hotkeys in a Thinkpad.  If you want
 564notifications for OSD, use the sysfs backlight class event support.
 565
 566The driver will issue KEY_BRIGHTNESS_UP and KEY_BRIGHTNESS_DOWN events
 567automatically for the cases were userspace has to do something to
 568implement brightness changes.  When you override these events, you will
 569either fail to handle properly the ThinkPads that require explicit
 570action to change backlight brightness, or the ThinkPads that require
 571that no action be taken to work properly.
 572
 573
 574Bluetooth
 575---------
 576
 577procfs: /proc/acpi/ibm/bluetooth
 578sysfs device attribute: bluetooth_enable (deprecated)
 579sysfs rfkill class: switch "tpacpi_bluetooth_sw"
 580
 581This feature shows the presence and current state of a ThinkPad
 582Bluetooth device in the internal ThinkPad CDC slot.
 583
 584If the ThinkPad supports it, the Bluetooth state is stored in NVRAM,
 585so it is kept across reboots and power-off.
 586
 587Procfs notes:
 588
 589If Bluetooth is installed, the following commands can be used:
 590
 591        echo enable > /proc/acpi/ibm/bluetooth
 592        echo disable > /proc/acpi/ibm/bluetooth
 593
 594Sysfs notes:
 595
 596        If the Bluetooth CDC card is installed, it can be enabled /
 597        disabled through the "bluetooth_enable" thinkpad-acpi device
 598        attribute, and its current status can also be queried.
 599
 600        enable:
 601                0: disables Bluetooth / Bluetooth is disabled
 602                1: enables Bluetooth / Bluetooth is enabled.
 603
 604        Note: this interface has been superseded by the generic rfkill
 605        class.  It has been deprecated, and it will be removed in year
 606        2010.
 607
 608        rfkill controller switch "tpacpi_bluetooth_sw": refer to
 609        Documentation/rfkill.txt for details.
 610
 611
 612Video output control -- /proc/acpi/ibm/video
 613--------------------------------------------
 614
 615This feature allows control over the devices used for video output -
 616LCD, CRT or DVI (if available). The following commands are available:
 617
 618        echo lcd_enable > /proc/acpi/ibm/video
 619        echo lcd_disable > /proc/acpi/ibm/video
 620        echo crt_enable > /proc/acpi/ibm/video
 621        echo crt_disable > /proc/acpi/ibm/video
 622        echo dvi_enable > /proc/acpi/ibm/video
 623        echo dvi_disable > /proc/acpi/ibm/video
 624        echo auto_enable > /proc/acpi/ibm/video
 625        echo auto_disable > /proc/acpi/ibm/video
 626        echo expand_toggle > /proc/acpi/ibm/video
 627        echo video_switch > /proc/acpi/ibm/video
 628
 629NOTE: Access to this feature is restricted to processes owning the
 630CAP_SYS_ADMIN capability for safety reasons, as it can interact badly
 631enough with some versions of X.org to crash it.
 632
 633Each video output device can be enabled or disabled individually.
 634Reading /proc/acpi/ibm/video shows the status of each device.
 635
 636Automatic video switching can be enabled or disabled.  When automatic
 637video switching is enabled, certain events (e.g. opening the lid,
 638docking or undocking) cause the video output device to change
 639automatically. While this can be useful, it also causes flickering
 640and, on the X40, video corruption. By disabling automatic switching,
 641the flickering or video corruption can be avoided.
 642
 643The video_switch command cycles through the available video outputs
 644(it simulates the behavior of Fn-F7).
 645
 646Video expansion can be toggled through this feature. This controls
 647whether the display is expanded to fill the entire LCD screen when a
 648mode with less than full resolution is used. Note that the current
 649video expansion status cannot be determined through this feature.
 650
 651Note that on many models (particularly those using Radeon graphics
 652chips) the X driver configures the video card in a way which prevents
 653Fn-F7 from working. This also disables the video output switching
 654features of this driver, as it uses the same ACPI methods as
 655Fn-F7. Video switching on the console should still work.
 656
 657UPDATE: refer to https://bugs.freedesktop.org/show_bug.cgi?id=2000
 658
 659
 660ThinkLight control
 661------------------
 662
 663procfs: /proc/acpi/ibm/light
 664sysfs attributes: as per LED class, for the "tpacpi::thinklight" LED
 665
 666procfs notes:
 667
 668The ThinkLight status can be read and set through the procfs interface.  A
 669few models which do not make the status available will show the ThinkLight
 670status as "unknown". The available commands are:
 671
 672        echo on  > /proc/acpi/ibm/light
 673        echo off > /proc/acpi/ibm/light
 674
 675sysfs notes:
 676
 677The ThinkLight sysfs interface is documented by the LED class
 678documentation, in Documentation/leds/leds-class.txt.  The ThinkLight LED name
 679is "tpacpi::thinklight".
 680
 681Due to limitations in the sysfs LED class, if the status of the ThinkLight
 682cannot be read or if it is unknown, thinkpad-acpi will report it as "off".
 683It is impossible to know if the status returned through sysfs is valid.
 684
 685
 686CMOS/UCMS control
 687-----------------
 688
 689procfs: /proc/acpi/ibm/cmos
 690sysfs device attribute: cmos_command
 691
 692This feature is mostly used internally by the ACPI firmware to keep the legacy
 693CMOS NVRAM bits in sync with the current machine state, and to record this
 694state so that the ThinkPad will retain such settings across reboots.
 695
 696Some of these commands actually perform actions in some ThinkPad models, but
 697this is expected to disappear more and more in newer models.  As an example, in
 698a T43 and in a X40, commands 12 and 13 still control the ThinkLight state for
 699real, but commands 0 to 2 don't control the mixer anymore (they have been
 700phased out) and just update the NVRAM.
 701
 702The range of valid cmos command numbers is 0 to 21, but not all have an
 703effect and the behavior varies from model to model.  Here is the behavior
 704on the X40 (tpb is the ThinkPad Buttons utility):
 705
 706        0 - Related to "Volume down" key press
 707        1 - Related to "Volume up" key press
 708        2 - Related to "Mute on" key press
 709        3 - Related to "Access IBM" key press
 710        4 - Related to "LCD brightness up" key press
 711        5 - Related to "LCD brightness down" key press
 712        11 - Related to "toggle screen expansion" key press/function
 713        12 - Related to "ThinkLight on"
 714        13 - Related to "ThinkLight off"
 715        14 - Related to "ThinkLight" key press (toggle ThinkLight)
 716
 717The cmos command interface is prone to firmware split-brain problems, as
 718in newer ThinkPads it is just a compatibility layer.  Do not use it, it is
 719exported just as a debug tool.
 720
 721
 722LED control
 723-----------
 724
 725procfs: /proc/acpi/ibm/led
 726sysfs attributes: as per LED class, see below for names
 727
 728Some of the LED indicators can be controlled through this feature.  On
 729some older ThinkPad models, it is possible to query the status of the
 730LED indicators as well.  Newer ThinkPads cannot query the real status
 731of the LED indicators.
 732
 733Because misuse of the LEDs could induce an unaware user to perform
 734dangerous actions (like undocking or ejecting a bay device while the
 735buses are still active), or mask an important alarm (such as a nearly
 736empty battery, or a broken battery), access to most LEDs is
 737restricted.
 738
 739Unrestricted access to all LEDs requires that thinkpad-acpi be
 740compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
 741Distributions must never enable this option.  Individual users that
 742are aware of the consequences are welcome to enabling it.
 743
 744Audio mute and microphone mute LEDs are supported, but currently not
 745visible to userspace. They are used by the snd-hda-intel audio driver.
 746
 747procfs notes:
 748
 749The available commands are:
 750
 751        echo '<LED number> on' >/proc/acpi/ibm/led
 752        echo '<LED number> off' >/proc/acpi/ibm/led
 753        echo '<LED number> blink' >/proc/acpi/ibm/led
 754
 755The <LED number> range is 0 to 15. The set of LEDs that can be
 756controlled varies from model to model. Here is the common ThinkPad
 757mapping:
 758
 759        0 - power
 760        1 - battery (orange)
 761        2 - battery (green)
 762        3 - UltraBase/dock
 763        4 - UltraBay
 764        5 - UltraBase battery slot
 765        6 - (unknown)
 766        7 - standby
 767        8 - dock status 1
 768        9 - dock status 2
 769        10, 11 - (unknown)
 770        12 - thinkvantage
 771        13, 14, 15 - (unknown)
 772
 773All of the above can be turned on and off and can be made to blink.
 774
 775sysfs notes:
 776
 777The ThinkPad LED sysfs interface is described in detail by the LED class
 778documentation, in Documentation/leds/leds-class.txt.
 779
 780The LEDs are named (in LED ID order, from 0 to 12):
 781"tpacpi::power", "tpacpi:orange:batt", "tpacpi:green:batt",
 782"tpacpi::dock_active", "tpacpi::bay_active", "tpacpi::dock_batt",
 783"tpacpi::unknown_led", "tpacpi::standby", "tpacpi::dock_status1",
 784"tpacpi::dock_status2", "tpacpi::unknown_led2", "tpacpi::unknown_led3",
 785"tpacpi::thinkvantage".
 786
 787Due to limitations in the sysfs LED class, if the status of the LED
 788indicators cannot be read due to an error, thinkpad-acpi will report it as
 789a brightness of zero (same as LED off).
 790
 791If the thinkpad firmware doesn't support reading the current status,
 792trying to read the current LED brightness will just return whatever
 793brightness was last written to that attribute.
 794
 795These LEDs can blink using hardware acceleration.  To request that a
 796ThinkPad indicator LED should blink in hardware accelerated mode, use the
 797"timer" trigger, and leave the delay_on and delay_off parameters set to
 798zero (to request hardware acceleration autodetection).
 799
 800LEDs that are known not to exist in a given ThinkPad model are not
 801made available through the sysfs interface.  If you have a dock and you
 802notice there are LEDs listed for your ThinkPad that do not exist (and
 803are not in the dock), or if you notice that there are missing LEDs,
 804a report to ibm-acpi-devel@lists.sourceforge.net is appreciated.
 805
 806
 807ACPI sounds -- /proc/acpi/ibm/beep
 808----------------------------------
 809
 810The BEEP method is used internally by the ACPI firmware to provide
 811audible alerts in various situations. This feature allows the same
 812sounds to be triggered manually.
 813
 814The commands are non-negative integer numbers:
 815
 816        echo <number> >/proc/acpi/ibm/beep
 817
 818The valid <number> range is 0 to 17. Not all numbers trigger sounds
 819and the sounds vary from model to model. Here is the behavior on the
 820X40:
 821
 822        0 - stop a sound in progress (but use 17 to stop 16)
 823        2 - two beeps, pause, third beep ("low battery")
 824        3 - single beep
 825        4 - high, followed by low-pitched beep ("unable")
 826        5 - single beep
 827        6 - very high, followed by high-pitched beep ("AC/DC")
 828        7 - high-pitched beep
 829        9 - three short beeps
 830        10 - very long beep
 831        12 - low-pitched beep
 832        15 - three high-pitched beeps repeating constantly, stop with 0
 833        16 - one medium-pitched beep repeating constantly, stop with 17
 834        17 - stop 16
 835
 836
 837Temperature sensors
 838-------------------
 839
 840procfs: /proc/acpi/ibm/thermal
 841sysfs device attributes: (hwmon "thinkpad") temp*_input
 842
 843Most ThinkPads include six or more separate temperature sensors but only
 844expose the CPU temperature through the standard ACPI methods.  This
 845feature shows readings from up to eight different sensors on older
 846ThinkPads, and up to sixteen different sensors on newer ThinkPads.
 847
 848For example, on the X40, a typical output may be:
 849temperatures:   42 42 45 41 36 -128 33 -128
 850
 851On the T43/p, a typical output may be:
 852temperatures:   48 48 36 52 38 -128 31 -128 48 52 48 -128 -128 -128 -128 -128
 853
 854The mapping of thermal sensors to physical locations varies depending on
 855system-board model (and thus, on ThinkPad model).
 856
 857http://thinkwiki.org/wiki/Thermal_Sensors is a public wiki page that
 858tries to track down these locations for various models.
 859
 860Most (newer?) models seem to follow this pattern:
 861
 8621:  CPU
 8632:  (depends on model)
 8643:  (depends on model)
 8654:  GPU
 8665:  Main battery: main sensor
 8676:  Bay battery: main sensor
 8687:  Main battery: secondary sensor
 8698:  Bay battery: secondary sensor
 8709-15: (depends on model)
 871
 872For the R51 (source: Thomas Gruber):
 8732:  Mini-PCI
 8743:  Internal HDD
 875
 876For the T43, T43/p (source: Shmidoax/Thinkwiki.org)
 877http://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_T43.2C_T43p
 8782:  System board, left side (near PCMCIA slot), reported as HDAPS temp
 8793:  PCMCIA slot
 8809:  MCH (northbridge) to DRAM Bus
 88110: Clock-generator, mini-pci card and ICH (southbridge), under Mini-PCI
 882    card, under touchpad
 88311: Power regulator, underside of system board, below F2 key
 884
 885The A31 has a very atypical layout for the thermal sensors
 886(source: Milos Popovic, http://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_A31)
 8871:  CPU
 8882:  Main Battery: main sensor
 8893:  Power Converter
 8904:  Bay Battery: main sensor
 8915:  MCH (northbridge)
 8926:  PCMCIA/ambient
 8937:  Main Battery: secondary sensor
 8948:  Bay Battery: secondary sensor
 895
 896
 897Procfs notes:
 898        Readings from sensors that are not available return -128.
 899        No commands can be written to this file.
 900
 901Sysfs notes:
 902        Sensors that are not available return the ENXIO error.  This
 903        status may change at runtime, as there are hotplug thermal
 904        sensors, like those inside the batteries and docks.
 905
 906        thinkpad-acpi thermal sensors are reported through the hwmon
 907        subsystem, and follow all of the hwmon guidelines at
 908        Documentation/hwmon.
 909
 910EXPERIMENTAL: Embedded controller register dump
 911-----------------------------------------------
 912
 913This feature is not included in the thinkpad driver anymore.
 914Instead the EC can be accessed through /sys/kernel/debug/ec with
 915a userspace tool which can be found here:
 916ftp://ftp.suse.com/pub/people/trenn/sources/ec
 917
 918Use it to determine the register holding the fan
 919speed on some models. To do that, do the following:
 920        - make sure the battery is fully charged
 921        - make sure the fan is running
 922        - use above mentioned tool to read out the EC
 923
 924Often fan and temperature values vary between
 925readings. Since temperatures don't change vary fast, you can take
 926several quick dumps to eliminate them.
 927
 928You can use a similar method to figure out the meaning of other
 929embedded controller registers - e.g. make sure nothing else changes
 930except the charging or discharging battery to determine which
 931registers contain the current battery capacity, etc. If you experiment
 932with this, do send me your results (including some complete dumps with
 933a description of the conditions when they were taken.)
 934
 935
 936LCD brightness control
 937----------------------
 938
 939procfs: /proc/acpi/ibm/brightness
 940sysfs backlight device "thinkpad_screen"
 941
 942This feature allows software control of the LCD brightness on ThinkPad
 943models which don't have a hardware brightness slider.
 944
 945It has some limitations: the LCD backlight cannot be actually turned
 946on or off by this interface, it just controls the backlight brightness
 947level.
 948
 949On IBM (and some of the earlier Lenovo) ThinkPads, the backlight control
 950has eight brightness levels, ranging from 0 to 7.  Some of the levels
 951may not be distinct.  Later Lenovo models that implement the ACPI
 952display backlight brightness control methods have 16 levels, ranging
 953from 0 to 15.
 954
 955For IBM ThinkPads, there are two interfaces to the firmware for direct
 956brightness control, EC and UCMS (or CMOS).  To select which one should be
 957used, use the brightness_mode module parameter: brightness_mode=1 selects
 958EC mode, brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
 959mode with NVRAM backing (so that brightness changes are remembered across
 960shutdown/reboot).
 961
 962The driver tries to select which interface to use from a table of
 963defaults for each ThinkPad model.  If it makes a wrong choice, please
 964report this as a bug, so that we can fix it.
 965
 966Lenovo ThinkPads only support brightness_mode=2 (UCMS).
 967
 968When display backlight brightness controls are available through the
 969standard ACPI interface, it is best to use it instead of this direct
 970ThinkPad-specific interface.  The driver will disable its native
 971backlight brightness control interface if it detects that the standard
 972ACPI interface is available in the ThinkPad.
 973
 974If you want to use the thinkpad-acpi backlight brightness control
 975instead of the generic ACPI video backlight brightness control for some
 976reason, you should use the acpi_backlight=vendor kernel parameter.
 977
 978The brightness_enable module parameter can be used to control whether
 979the LCD brightness control feature will be enabled when available.
 980brightness_enable=0 forces it to be disabled.  brightness_enable=1
 981forces it to be enabled when available, even if the standard ACPI
 982interface is also available.
 983
 984Procfs notes:
 985
 986        The available commands are:
 987
 988        echo up   >/proc/acpi/ibm/brightness
 989        echo down >/proc/acpi/ibm/brightness
 990        echo 'level <level>' >/proc/acpi/ibm/brightness
 991
 992Sysfs notes:
 993
 994The interface is implemented through the backlight sysfs class, which is
 995poorly documented at this time.
 996
 997Locate the thinkpad_screen device under /sys/class/backlight, and inside
 998it there will be the following attributes:
 999
1000        max_brightness:
1001                Reads the maximum brightness the hardware can be set to.
1002                The minimum is always zero.
1003
1004        actual_brightness:
1005                Reads what brightness the screen is set to at this instant.
1006
1007        brightness:
1008                Writes request the driver to change brightness to the
1009                given value.  Reads will tell you what brightness the
1010                driver is trying to set the display to when "power" is set
1011                to zero and the display has not been dimmed by a kernel
1012                power management event.
1013
1014        power:
1015                power management mode, where 0 is "display on", and 1 to 3
1016                will dim the display backlight to brightness level 0
1017                because thinkpad-acpi cannot really turn the backlight
1018                off.  Kernel power management events can temporarily
1019                increase the current power management level, i.e. they can
1020                dim the display.
1021
1022
1023WARNING:
1024
1025    Whatever you do, do NOT ever call thinkpad-acpi backlight-level change
1026    interface and the ACPI-based backlight level change interface
1027    (available on newer BIOSes, and driven by the Linux ACPI video driver)
1028    at the same time.  The two will interact in bad ways, do funny things,
1029    and maybe reduce the life of the backlight lamps by needlessly kicking
1030    its level up and down at every change.
1031
1032
1033Volume control (Console Audio control)
1034--------------------------------------
1035
1036procfs: /proc/acpi/ibm/volume
1037ALSA: "ThinkPad Console Audio Control", default ID: "ThinkPadEC"
1038
1039NOTE: by default, the volume control interface operates in read-only
1040mode, as it is supposed to be used for on-screen-display purposes.
1041The read/write mode can be enabled through the use of the
1042"volume_control=1" module parameter.
1043
1044NOTE: distros are urged to not enable volume_control by default, this
1045should be done by the local admin only.  The ThinkPad UI is for the
1046console audio control to be done through the volume keys only, and for
1047the desktop environment to just provide on-screen-display feedback.
1048Software volume control should be done only in the main AC97/HDA
1049mixer.
1050
1051
1052About the ThinkPad Console Audio control:
1053
1054ThinkPads have a built-in amplifier and muting circuit that drives the
1055console headphone and speakers.  This circuit is after the main AC97
1056or HDA mixer in the audio path, and under exclusive control of the
1057firmware.
1058
1059ThinkPads have three special hotkeys to interact with the console
1060audio control: volume up, volume down and mute.
1061
1062It is worth noting that the normal way the mute function works (on
1063ThinkPads that do not have a "mute LED") is:
1064
10651. Press mute to mute.  It will *always* mute, you can press it as
1066   many times as you want, and the sound will remain mute.
1067
10682. Press either volume key to unmute the ThinkPad (it will _not_
1069   change the volume, it will just unmute).
1070
1071This is a very superior design when compared to the cheap software-only
1072mute-toggle solution found on normal consumer laptops:  you can be
1073absolutely sure the ThinkPad will not make noise if you press the mute
1074button, no matter the previous state.
1075
1076The IBM ThinkPads, and the earlier Lenovo ThinkPads have variable-gain
1077amplifiers driving the speakers and headphone output, and the firmware
1078also handles volume control for the headphone and speakers on these
1079ThinkPads without any help from the operating system (this volume
1080control stage exists after the main AC97 or HDA mixer in the audio
1081path).
1082
1083The newer Lenovo models only have firmware mute control, and depend on
1084the main HDA mixer to do volume control (which is done by the operating
1085system).  In this case, the volume keys are filtered out for unmute
1086key press (there are some firmware bugs in this area) and delivered as
1087normal key presses to the operating system (thinkpad-acpi is not
1088involved).
1089
1090
1091The ThinkPad-ACPI volume control:
1092
1093The preferred way to interact with the Console Audio control is the
1094ALSA interface.
1095
1096The legacy procfs interface allows one to read the current state,
1097and if volume control is enabled, accepts the following commands:
1098
1099        echo up   >/proc/acpi/ibm/volume
1100        echo down >/proc/acpi/ibm/volume
1101        echo mute >/proc/acpi/ibm/volume
1102        echo unmute >/proc/acpi/ibm/volume
1103        echo 'level <level>' >/proc/acpi/ibm/volume
1104
1105The <level> number range is 0 to 14 although not all of them may be
1106distinct. To unmute the volume after the mute command, use either the
1107up or down command (the level command will not unmute the volume), or
1108the unmute command.
1109
1110You can use the volume_capabilities parameter to tell the driver
1111whether your thinkpad has volume control or mute-only control:
1112volume_capabilities=1 for mixers with mute and volume control,
1113volume_capabilities=2 for mixers with only mute control.
1114
1115If the driver misdetects the capabilities for your ThinkPad model,
1116please report this to ibm-acpi-devel@lists.sourceforge.net, so that we
1117can update the driver.
1118
1119There are two strategies for volume control.  To select which one
1120should be used, use the volume_mode module parameter: volume_mode=1
1121selects EC mode, and volume_mode=3 selects EC mode with NVRAM backing
1122(so that volume/mute changes are remembered across shutdown/reboot).
1123
1124The driver will operate in volume_mode=3 by default. If that does not
1125work well on your ThinkPad model, please report this to
1126ibm-acpi-devel@lists.sourceforge.net.
1127
1128The driver supports the standard ALSA module parameters.  If the ALSA
1129mixer is disabled, the driver will disable all volume functionality.
1130
1131
1132Fan control and monitoring: fan speed, fan enable/disable
1133---------------------------------------------------------
1134
1135procfs: /proc/acpi/ibm/fan
1136sysfs device attributes: (hwmon "thinkpad") fan1_input, pwm1,
1137                          pwm1_enable, fan2_input
1138sysfs hwmon driver attributes: fan_watchdog
1139
1140NOTE NOTE NOTE: fan control operations are disabled by default for
1141safety reasons.  To enable them, the module parameter "fan_control=1"
1142must be given to thinkpad-acpi.
1143
1144This feature attempts to show the current fan speed, control mode and
1145other fan data that might be available.  The speed is read directly
1146from the hardware registers of the embedded controller.  This is known
1147to work on later R, T, X and Z series ThinkPads but may show a bogus
1148value on other models.
1149
1150Some Lenovo ThinkPads support a secondary fan.  This fan cannot be
1151controlled separately, it shares the main fan control.
1152
1153Fan levels:
1154
1155Most ThinkPad fans work in "levels" at the firmware interface.  Level 0
1156stops the fan.  The higher the level, the higher the fan speed, although
1157adjacent levels often map to the same fan speed.  7 is the highest
1158level, where the fan reaches the maximum recommended speed.
1159
1160Level "auto" means the EC changes the fan level according to some
1161internal algorithm, usually based on readings from the thermal sensors.
1162
1163There is also a "full-speed" level, also known as "disengaged" level.
1164In this level, the EC disables the speed-locked closed-loop fan control,
1165and drives the fan as fast as it can go, which might exceed hardware
1166limits, so use this level with caution.
1167
1168The fan usually ramps up or down slowly from one speed to another, and
1169it is normal for the EC to take several seconds to react to fan
1170commands.  The full-speed level may take up to two minutes to ramp up to
1171maximum speed, and in some ThinkPads, the tachometer readings go stale
1172while the EC is transitioning to the full-speed level.
1173
1174WARNING WARNING WARNING: do not leave the fan disabled unless you are
1175monitoring all of the temperature sensor readings and you are ready to
1176enable it if necessary to avoid overheating.
1177
1178An enabled fan in level "auto" may stop spinning if the EC decides the
1179ThinkPad is cool enough and doesn't need the extra airflow.  This is
1180normal, and the EC will spin the fan up if the various thermal readings
1181rise too much.
1182
1183On the X40, this seems to depend on the CPU and HDD temperatures.
1184Specifically, the fan is turned on when either the CPU temperature
1185climbs to 56 degrees or the HDD temperature climbs to 46 degrees.  The
1186fan is turned off when the CPU temperature drops to 49 degrees and the
1187HDD temperature drops to 41 degrees.  These thresholds cannot
1188currently be controlled.
1189
1190The ThinkPad's ACPI DSDT code will reprogram the fan on its own when
1191certain conditions are met.  It will override any fan programming done
1192through thinkpad-acpi.
1193
1194The thinkpad-acpi kernel driver can be programmed to revert the fan
1195level to a safe setting if userspace does not issue one of the procfs
1196fan commands: "enable", "disable", "level" or "watchdog", or if there
1197are no writes to pwm1_enable (or to pwm1 *if and only if* pwm1_enable is
1198set to 1, manual mode) within a configurable amount of time of up to
1199120 seconds.  This functionality is called fan safety watchdog.
1200
1201Note that the watchdog timer stops after it enables the fan.  It will be
1202rearmed again automatically (using the same interval) when one of the
1203above mentioned fan commands is received.  The fan watchdog is,
1204therefore, not suitable to protect against fan mode changes made through
1205means other than the "enable", "disable", and "level" procfs fan
1206commands, or the hwmon fan control sysfs interface.
1207
1208Procfs notes:
1209
1210The fan may be enabled or disabled with the following commands:
1211
1212        echo enable  >/proc/acpi/ibm/fan
1213        echo disable >/proc/acpi/ibm/fan
1214
1215Placing a fan on level 0 is the same as disabling it.  Enabling a fan
1216will try to place it in a safe level if it is too slow or disabled.
1217
1218The fan level can be controlled with the command:
1219
1220        echo 'level <level>' > /proc/acpi/ibm/fan
1221
1222Where <level> is an integer from 0 to 7, or one of the words "auto" or
1223"full-speed" (without the quotes).  Not all ThinkPads support the "auto"
1224and "full-speed" levels.  The driver accepts "disengaged" as an alias for
1225"full-speed", and reports it as "disengaged" for backwards
1226compatibility.
1227
1228On the X31 and X40 (and ONLY on those models), the fan speed can be
1229controlled to a certain degree.  Once the fan is running, it can be
1230forced to run faster or slower with the following command:
1231
1232        echo 'speed <speed>' > /proc/acpi/ibm/fan
1233
1234The sustainable range of fan speeds on the X40 appears to be from about
12353700 to about 7350. Values outside this range either do not have any
1236effect or the fan speed eventually settles somewhere in that range.  The
1237fan cannot be stopped or started with this command.  This functionality
1238is incomplete, and not available through the sysfs interface.
1239
1240To program the safety watchdog, use the "watchdog" command.
1241
1242        echo 'watchdog <interval in seconds>' > /proc/acpi/ibm/fan
1243
1244If you want to disable the watchdog, use 0 as the interval.
1245
1246Sysfs notes:
1247
1248The sysfs interface follows the hwmon subsystem guidelines for the most
1249part, and the exception is the fan safety watchdog.
1250
1251Writes to any of the sysfs attributes may return the EINVAL error if
1252that operation is not supported in a given ThinkPad or if the parameter
1253is out-of-bounds, and EPERM if it is forbidden.  They may also return
1254EINTR (interrupted system call), and EIO (I/O error while trying to talk
1255to the firmware).
1256
1257Features not yet implemented by the driver return ENOSYS.
1258
1259hwmon device attribute pwm1_enable:
1260        0: PWM offline (fan is set to full-speed mode)
1261        1: Manual PWM control (use pwm1 to set fan level)
1262        2: Hardware PWM control (EC "auto" mode)
1263        3: reserved (Software PWM control, not implemented yet)
1264
1265        Modes 0 and 2 are not supported by all ThinkPads, and the
1266        driver is not always able to detect this.  If it does know a
1267        mode is unsupported, it will return -EINVAL.
1268
1269hwmon device attribute pwm1:
1270        Fan level, scaled from the firmware values of 0-7 to the hwmon
1271        scale of 0-255.  0 means fan stopped, 255 means highest normal
1272        speed (level 7).
1273
1274        This attribute only commands the fan if pmw1_enable is set to 1
1275        (manual PWM control).
1276
1277hwmon device attribute fan1_input:
1278        Fan tachometer reading, in RPM.  May go stale on certain
1279        ThinkPads while the EC transitions the PWM to offline mode,
1280        which can take up to two minutes.  May return rubbish on older
1281        ThinkPads.
1282
1283hwmon device attribute fan2_input:
1284        Fan tachometer reading, in RPM, for the secondary fan.
1285        Available only on some ThinkPads.  If the secondary fan is
1286        not installed, will always read 0.
1287
1288hwmon driver attribute fan_watchdog:
1289        Fan safety watchdog timer interval, in seconds.  Minimum is
1290        1 second, maximum is 120 seconds.  0 disables the watchdog.
1291
1292To stop the fan: set pwm1 to zero, and pwm1_enable to 1.
1293
1294To start the fan in a safe mode: set pwm1_enable to 2.  If that fails
1295with EINVAL, try to set pwm1_enable to 1 and pwm1 to at least 128 (255
1296would be the safest choice, though).
1297
1298
1299WAN
1300---
1301
1302procfs: /proc/acpi/ibm/wan
1303sysfs device attribute: wwan_enable (deprecated)
1304sysfs rfkill class: switch "tpacpi_wwan_sw"
1305
1306This feature shows the presence and current state of the built-in
1307Wireless WAN device.
1308
1309If the ThinkPad supports it, the WWAN state is stored in NVRAM,
1310so it is kept across reboots and power-off.
1311
1312It was tested on a Lenovo ThinkPad X60. It should probably work on other
1313ThinkPad models which come with this module installed.
1314
1315Procfs notes:
1316
1317If the W-WAN card is installed, the following commands can be used:
1318
1319        echo enable > /proc/acpi/ibm/wan
1320        echo disable > /proc/acpi/ibm/wan
1321
1322Sysfs notes:
1323
1324        If the W-WAN card is installed, it can be enabled /
1325        disabled through the "wwan_enable" thinkpad-acpi device
1326        attribute, and its current status can also be queried.
1327
1328        enable:
1329                0: disables WWAN card / WWAN card is disabled
1330                1: enables WWAN card / WWAN card is enabled.
1331
1332        Note: this interface has been superseded by the generic rfkill
1333        class.  It has been deprecated, and it will be removed in year
1334        2010.
1335
1336        rfkill controller switch "tpacpi_wwan_sw": refer to
1337        Documentation/rfkill.txt for details.
1338
1339
1340EXPERIMENTAL: UWB
1341-----------------
1342
1343This feature is considered EXPERIMENTAL because it has not been extensively
1344tested and validated in various ThinkPad models yet.  The feature may not
1345work as expected. USE WITH CAUTION! To use this feature, you need to supply
1346the experimental=1 parameter when loading the module.
1347
1348sysfs rfkill class: switch "tpacpi_uwb_sw"
1349
1350This feature exports an rfkill controller for the UWB device, if one is
1351present and enabled in the BIOS.
1352
1353Sysfs notes:
1354
1355        rfkill controller switch "tpacpi_uwb_sw": refer to
1356        Documentation/rfkill.txt for details.
1357
1358
1359Multiple Commands, Module Parameters
1360------------------------------------
1361
1362Multiple commands can be written to the proc files in one shot by
1363separating them with commas, for example:
1364
1365        echo enable,0xffff > /proc/acpi/ibm/hotkey
1366        echo lcd_disable,crt_enable > /proc/acpi/ibm/video
1367
1368Commands can also be specified when loading the thinkpad-acpi module,
1369for example:
1370
1371        modprobe thinkpad_acpi hotkey=enable,0xffff video=auto_disable
1372
1373
1374Enabling debugging output
1375-------------------------
1376
1377The module takes a debug parameter which can be used to selectively
1378enable various classes of debugging output, for example:
1379
1380         modprobe thinkpad_acpi debug=0xffff
1381
1382will enable all debugging output classes.  It takes a bitmask, so
1383to enable more than one output class, just add their values.
1384
1385        Debug bitmask           Description
1386        0x8000                  Disclose PID of userspace programs
1387                                accessing some functions of the driver
1388        0x0001                  Initialization and probing
1389        0x0002                  Removal
1390        0x0004                  RF Transmitter control (RFKILL)
1391                                (bluetooth, WWAN, UWB...)
1392        0x0008                  HKEY event interface, hotkeys
1393        0x0010                  Fan control
1394        0x0020                  Backlight brightness
1395        0x0040                  Audio mixer/volume control
1396
1397There is also a kernel build option to enable more debugging
1398information, which may be necessary to debug driver problems.
1399
1400The level of debugging information output by the driver can be changed
1401at runtime through sysfs, using the driver attribute debug_level.  The
1402attribute takes the same bitmask as the debug module parameter above.
1403
1404
1405Force loading of module
1406-----------------------
1407
1408If thinkpad-acpi refuses to detect your ThinkPad, you can try to specify
1409the module parameter force_load=1.  Regardless of whether this works or
1410not, please contact ibm-acpi-devel@lists.sourceforge.net with a report.
1411
1412
1413Sysfs interface changelog:
1414
14150x000100:       Initial sysfs support, as a single platform driver and
1416                device.
14170x000200:       Hot key support for 32 hot keys, and radio slider switch
1418                support.
14190x010000:       Hot keys are now handled by default over the input
1420                layer, the radio switch generates input event EV_RADIO,
1421                and the driver enables hot key handling by default in
1422                the firmware.
1423
14240x020000:       ABI fix: added a separate hwmon platform device and
1425                driver, which must be located by name (thinkpad)
1426                and the hwmon class for libsensors4 (lm-sensors 3)
1427                compatibility.  Moved all hwmon attributes to this
1428                new platform device.
1429
14300x020100:       Marker for thinkpad-acpi with hot key NVRAM polling
1431                support.  If you must, use it to know you should not
1432                start a userspace NVRAM poller (allows to detect when
1433                NVRAM is compiled out by the user because it is
1434                unneeded/undesired in the first place).
14350x020101:       Marker for thinkpad-acpi with hot key NVRAM polling
1436                and proper hotkey_mask semantics (version 8 of the
1437                NVRAM polling patch).  Some development snapshots of
1438                0.18 had an earlier version that did strange things
1439                to hotkey_mask.
1440
14410x020200:       Add poll()/select() support to the following attributes:
1442                hotkey_radio_sw, wakeup_hotunplug_complete, wakeup_reason
1443
14440x020300:       hotkey enable/disable support removed, attributes
1445                hotkey_bios_enabled and hotkey_enable deprecated and
1446                marked for removal.
1447
14480x020400:       Marker for 16 LEDs support.  Also, LEDs that are known
1449                to not exist in a given model are not registered with
1450                the LED sysfs class anymore.
1451
14520x020500:       Updated hotkey driver, hotkey_mask is always available
1453                and it is always able to disable hot keys.  Very old
1454                thinkpads are properly supported.  hotkey_bios_mask
1455                is deprecated and marked for removal.
1456
14570x020600:       Marker for backlight change event support.
1458
14590x020700:       Support for mute-only mixers.
1460                Volume control in read-only mode by default.
1461                Marker for ALSA mixer support.
1462
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