linux/Documentation/laptops/thinkpad-acpi.txt
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   1                     ThinkPad ACPI Extras Driver
   2
   3                            Version 0.24
   4                        December 11th,  2009
   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        hotkey_report_mode:
 333                Returns the state of the procfs ACPI event report mode
 334                filter for hot keys.  If it is set to 1 (the default),
 335                all hot key presses are reported both through the input
 336                layer and also as ACPI events through procfs (but not
 337                through netlink).  If it is set to 2, hot key presses
 338                are reported only through the input layer.
 339
 340                This attribute is read-only in kernels 2.6.23 or later,
 341                and read-write on earlier kernels.
 342
 343                May return -EPERM (write access locked out by module
 344                parameter) or -EACCES (read-only).
 345
 346        wakeup_reason:
 347                Set to 1 if the system is waking up because the user
 348                requested a bay ejection.  Set to 2 if the system is
 349                waking up because the user requested the system to
 350                undock.  Set to zero for normal wake-ups or wake-ups
 351                due to unknown reasons.
 352
 353                This attribute has poll()/select() support.
 354
 355        wakeup_hotunplug_complete:
 356                Set to 1 if the system was waken up because of an
 357                undock or bay ejection request, and that request
 358                was successfully completed.  At this point, it might
 359                be useful to send the system back to sleep, at the
 360                user's choice.  Refer to HKEY events 0x4003 and
 361                0x3003, below.
 362
 363                This attribute has poll()/select() support.
 364
 365input layer notes:
 366
 367A Hot key is mapped to a single input layer EV_KEY event, possibly
 368followed by an EV_MSC MSC_SCAN event that shall contain that key's scan
 369code.  An EV_SYN event will always be generated to mark the end of the
 370event block.
 371
 372Do not use the EV_MSC MSC_SCAN events to process keys.  They are to be
 373used as a helper to remap keys, only.  They are particularly useful when
 374remapping KEY_UNKNOWN keys.
 375
 376The events are available in an input device, with the following id:
 377
 378        Bus:            BUS_HOST
 379        vendor:         0x1014 (PCI_VENDOR_ID_IBM)  or
 380                        0x17aa (PCI_VENDOR_ID_LENOVO)
 381        product:        0x5054 ("TP")
 382        version:        0x4101
 383
 384The version will have its LSB incremented if the keymap changes in a
 385backwards-compatible way.  The MSB shall always be 0x41 for this input
 386device.  If the MSB is not 0x41, do not use the device as described in
 387this section, as it is either something else (e.g. another input device
 388exported by a thinkpad driver, such as HDAPS) or its functionality has
 389been changed in a non-backwards compatible way.
 390
 391Adding other event types for other functionalities shall be considered a
 392backwards-compatible change for this input device.
 393
 394Thinkpad-acpi Hot Key event map (version 0x4101):
 395
 396ACPI    Scan
 397event   code    Key             Notes
 398
 3990x1001  0x00    FN+F1           -
 400
 4010x1002  0x01    FN+F2           IBM: battery (rare)
 402                                Lenovo: Screen lock
 403
 4040x1003  0x02    FN+F3           Many IBM models always report
 405                                this hot key, even with hot keys
 406                                disabled or with Fn+F3 masked
 407                                off
 408                                IBM: screen lock, often turns
 409                                off the ThinkLight as side-effect
 410                                Lenovo: battery
 411
 4120x1004  0x03    FN+F4           Sleep button (ACPI sleep button
 413                                semantics, i.e. sleep-to-RAM).
 414                                It always generates some kind
 415                                of event, either the hot key
 416                                event or an ACPI sleep button
 417                                event. The firmware may
 418                                refuse to generate further FN+F4
 419                                key presses until a S3 or S4 ACPI
 420                                sleep cycle is performed or some
 421                                time passes.
 422
 4230x1005  0x04    FN+F5           Radio.  Enables/disables
 424                                the internal Bluetooth hardware
 425                                and W-WAN card if left in control
 426                                of the firmware.  Does not affect
 427                                the WLAN card.
 428                                Should be used to turn on/off all
 429                                radios (Bluetooth+W-WAN+WLAN),
 430                                really.
 431
 4320x1006  0x05    FN+F6           -
 433
 4340x1007  0x06    FN+F7           Video output cycle.
 435                                Do you feel lucky today?
 436
 4370x1008  0x07    FN+F8           IBM: toggle screen expand
 438                                Lenovo: configure UltraNav,
 439                                or toggle screen expand
 440
 4410x1009  0x08    FN+F9           -
 442        ..      ..              ..
 4430x100B  0x0A    FN+F11          -
 444
 4450x100C  0x0B    FN+F12          Sleep to disk.  You are always
 446                                supposed to handle it yourself,
 447                                either through the ACPI event,
 448                                or through a hotkey event.
 449                                The firmware may refuse to
 450                                generate further FN+F12 key
 451                                press events until a S3 or S4
 452                                ACPI sleep cycle is performed,
 453                                or some time passes.
 454
 4550x100D  0x0C    FN+BACKSPACE    -
 4560x100E  0x0D    FN+INSERT       -
 4570x100F  0x0E    FN+DELETE       -
 458
 4590x1010  0x0F    FN+HOME         Brightness up.  This key is
 460                                always handled by the firmware
 461                                in IBM ThinkPads, even when
 462                                unmasked.  Just leave it alone.
 463                                For Lenovo ThinkPads with a new
 464                                BIOS, it has to be handled either
 465                                by the ACPI OSI, or by userspace.
 466                                The driver does the right thing,
 467                                never mess with this.
 4680x1011  0x10    FN+END          Brightness down.  See brightness
 469                                up for details.
 470
 4710x1012  0x11    FN+PGUP         ThinkLight toggle.  This key is
 472                                always handled by the firmware,
 473                                even when unmasked.
 474
 4750x1013  0x12    FN+PGDOWN       -
 476
 4770x1014  0x13    FN+SPACE        Zoom key
 478
 4790x1015  0x14    VOLUME UP       Internal mixer volume up. This
 480                                key is always handled by the
 481                                firmware, even when unmasked.
 482                                NOTE: Lenovo seems to be changing
 483                                this.
 4840x1016  0x15    VOLUME DOWN     Internal mixer volume up. This
 485                                key is always handled by the
 486                                firmware, even when unmasked.
 487                                NOTE: Lenovo seems to be changing
 488                                this.
 4890x1017  0x16    MUTE            Mute internal mixer. This
 490                                key is always handled by the
 491                                firmware, even when unmasked.
 492
 4930x1018  0x17    THINKPAD        ThinkPad/Access IBM/Lenovo key
 494
 4950x1019  0x18    unknown
 496..      ..      ..
 4970x1020  0x1F    unknown
 498
 499The ThinkPad firmware does not allow one to differentiate when most hot
 500keys are pressed or released (either that, or we don't know how to, yet).
 501For these keys, the driver generates a set of events for a key press and
 502immediately issues the same set of events for a key release.  It is
 503unknown by the driver if the ThinkPad firmware triggered these events on
 504hot key press or release, but the firmware will do it for either one, not
 505both.
 506
 507If a key is mapped to KEY_RESERVED, it generates no input events at all.
 508If a key is mapped to KEY_UNKNOWN, it generates an input event that
 509includes an scan code.  If a key is mapped to anything else, it will
 510generate input device EV_KEY events.
 511
 512In addition to the EV_KEY events, thinkpad-acpi may also issue EV_SW
 513events for switches:
 514
 515SW_RFKILL_ALL   T60 and later hardware rfkill rocker switch
 516SW_TABLET_MODE  Tablet ThinkPads HKEY events 0x5009 and 0x500A
 517
 518Non hotkey ACPI HKEY event map:
 519-------------------------------
 520
 521Events that are not propagated by the driver, except for legacy
 522compatibility purposes when hotkey_report_mode is set to 1:
 523
 5240x5001          Lid closed
 5250x5002          Lid opened
 5260x5009          Tablet swivel: switched to tablet mode
 5270x500A          Tablet swivel: switched to normal mode
 5280x7000          Radio Switch may have changed state
 529
 530Events that are never propagated by the driver:
 531
 5320x2304          System is waking up from suspend to undock
 5330x2305          System is waking up from suspend to eject bay
 5340x2404          System is waking up from hibernation to undock
 5350x2405          System is waking up from hibernation to eject bay
 5360x5010          Brightness level changed/control event
 5370x6000          KEYBOARD: Numlock key pressed
 5380x6005          KEYBOARD: Fn key pressed (TO BE VERIFIED)
 539
 540Events that are propagated by the driver to userspace:
 541
 5420x2313          ALARM: System is waking up from suspend because
 543                the battery is nearly empty
 5440x2413          ALARM: System is waking up from hibernation because
 545                the battery is nearly empty
 5460x3003          Bay ejection (see 0x2x05) complete, can sleep again
 5470x3006          Bay hotplug request (hint to power up SATA link when
 548                the optical drive tray is ejected)
 5490x4003          Undocked (see 0x2x04), can sleep again
 5500x4010          Docked into hotplug port replicator (non-ACPI dock)
 5510x4011          Undocked from hotplug port replicator (non-ACPI dock)
 5520x500B          Tablet pen inserted into its storage bay
 5530x500C          Tablet pen removed from its storage bay
 5540x6011          ALARM: battery is too hot
 5550x6012          ALARM: battery is extremely hot
 5560x6021          ALARM: a sensor is too hot
 5570x6022          ALARM: a sensor is extremely hot
 5580x6030          System thermal table changed
 5590x6040          Nvidia Optimus/AC adapter related (TO BE VERIFIED)
 560
 561Battery nearly empty alarms are a last resort attempt to get the
 562operating system to hibernate or shutdown cleanly (0x2313), or shutdown
 563cleanly (0x2413) before power is lost.  They must be acted upon, as the
 564wake up caused by the firmware will have negated most safety nets...
 565
 566When any of the "too hot" alarms happen, according to Lenovo the user
 567should suspend or hibernate the laptop (and in the case of battery
 568alarms, unplug the AC adapter) to let it cool down.  These alarms do
 569signal that something is wrong, they should never happen on normal
 570operating conditions.
 571
 572The "extremely hot" alarms are emergencies.  According to Lenovo, the
 573operating system is to force either an immediate suspend or hibernate
 574cycle, or a system shutdown.  Obviously, something is very wrong if this
 575happens.
 576
 577Compatibility notes:
 578
 579ibm-acpi and thinkpad-acpi 0.15 (mainline kernels before 2.6.23) never
 580supported the input layer, and sent events over the procfs ACPI event
 581interface.
 582
 583To avoid sending duplicate events over the input layer and the ACPI
 584event interface, thinkpad-acpi 0.16 implements a module parameter
 585(hotkey_report_mode), and also a sysfs device attribute with the same
 586name.
 587
 588Make no mistake here: userspace is expected to switch to using the input
 589layer interface of thinkpad-acpi, together with the ACPI netlink event
 590interface in kernels 2.6.23 and later, or with the ACPI procfs event
 591interface in kernels 2.6.22 and earlier.
 592
 593If no hotkey_report_mode module parameter is specified (or it is set to
 594zero), the driver defaults to mode 1 (see below), and on kernels 2.6.22
 595and earlier, also allows one to change the hotkey_report_mode through
 596sysfs.  In kernels 2.6.23 and later, where the netlink ACPI event
 597interface is available, hotkey_report_mode cannot be changed through
 598sysfs (it is read-only).
 599
 600If the hotkey_report_mode module parameter is set to 1 or 2, it cannot
 601be changed later through sysfs (any writes will return -EPERM to signal
 602that hotkey_report_mode was locked.  On 2.6.23 and later, where
 603hotkey_report_mode cannot be changed at all, writes will return -EACCES).
 604
 605hotkey_report_mode set to 1 makes the driver export through the procfs
 606ACPI event interface all hot key presses (which are *also* sent to the
 607input layer).  This is a legacy compatibility behaviour, and it is also
 608the default mode of operation for the driver.
 609
 610hotkey_report_mode set to 2 makes the driver filter out the hot key
 611presses from the procfs ACPI event interface, so these events will only
 612be sent through the input layer.  Userspace that has been updated to use
 613the thinkpad-acpi input layer interface should set hotkey_report_mode to
 6142.
 615
 616Hot key press events are never sent to the ACPI netlink event interface.
 617Really up-to-date userspace under kernel 2.6.23 and later is to use the
 618netlink interface and the input layer interface, and don't bother at all
 619with hotkey_report_mode.
 620
 621
 622Brightness hotkey notes:
 623
 624Don't mess with the brightness hotkeys in a Thinkpad.  If you want
 625notifications for OSD, use the sysfs backlight class event support.
 626
 627The driver will issue KEY_BRIGHTNESS_UP and KEY_BRIGHTNESS_DOWN events
 628automatically for the cases were userspace has to do something to
 629implement brightness changes.  When you override these events, you will
 630either fail to handle properly the ThinkPads that require explicit
 631action to change backlight brightness, or the ThinkPads that require
 632that no action be taken to work properly.
 633
 634
 635Bluetooth
 636---------
 637
 638procfs: /proc/acpi/ibm/bluetooth
 639sysfs device attribute: bluetooth_enable (deprecated)
 640sysfs rfkill class: switch "tpacpi_bluetooth_sw"
 641
 642This feature shows the presence and current state of a ThinkPad
 643Bluetooth device in the internal ThinkPad CDC slot.
 644
 645If the ThinkPad supports it, the Bluetooth state is stored in NVRAM,
 646so it is kept across reboots and power-off.
 647
 648Procfs notes:
 649
 650If Bluetooth is installed, the following commands can be used:
 651
 652        echo enable > /proc/acpi/ibm/bluetooth
 653        echo disable > /proc/acpi/ibm/bluetooth
 654
 655Sysfs notes:
 656
 657        If the Bluetooth CDC card is installed, it can be enabled /
 658        disabled through the "bluetooth_enable" thinkpad-acpi device
 659        attribute, and its current status can also be queried.
 660
 661        enable:
 662                0: disables Bluetooth / Bluetooth is disabled
 663                1: enables Bluetooth / Bluetooth is enabled.
 664
 665        Note: this interface has been superseded by the generic rfkill
 666        class.  It has been deprecated, and it will be removed in year
 667        2010.
 668
 669        rfkill controller switch "tpacpi_bluetooth_sw": refer to
 670        Documentation/rfkill.txt for details.
 671
 672
 673Video output control -- /proc/acpi/ibm/video
 674--------------------------------------------
 675
 676This feature allows control over the devices used for video output -
 677LCD, CRT or DVI (if available). The following commands are available:
 678
 679        echo lcd_enable > /proc/acpi/ibm/video
 680        echo lcd_disable > /proc/acpi/ibm/video
 681        echo crt_enable > /proc/acpi/ibm/video
 682        echo crt_disable > /proc/acpi/ibm/video
 683        echo dvi_enable > /proc/acpi/ibm/video
 684        echo dvi_disable > /proc/acpi/ibm/video
 685        echo auto_enable > /proc/acpi/ibm/video
 686        echo auto_disable > /proc/acpi/ibm/video
 687        echo expand_toggle > /proc/acpi/ibm/video
 688        echo video_switch > /proc/acpi/ibm/video
 689
 690NOTE: Access to this feature is restricted to processes owning the
 691CAP_SYS_ADMIN capability for safety reasons, as it can interact badly
 692enough with some versions of X.org to crash it.
 693
 694Each video output device can be enabled or disabled individually.
 695Reading /proc/acpi/ibm/video shows the status of each device.
 696
 697Automatic video switching can be enabled or disabled.  When automatic
 698video switching is enabled, certain events (e.g. opening the lid,
 699docking or undocking) cause the video output device to change
 700automatically. While this can be useful, it also causes flickering
 701and, on the X40, video corruption. By disabling automatic switching,
 702the flickering or video corruption can be avoided.
 703
 704The video_switch command cycles through the available video outputs
 705(it simulates the behavior of Fn-F7).
 706
 707Video expansion can be toggled through this feature. This controls
 708whether the display is expanded to fill the entire LCD screen when a
 709mode with less than full resolution is used. Note that the current
 710video expansion status cannot be determined through this feature.
 711
 712Note that on many models (particularly those using Radeon graphics
 713chips) the X driver configures the video card in a way which prevents
 714Fn-F7 from working. This also disables the video output switching
 715features of this driver, as it uses the same ACPI methods as
 716Fn-F7. Video switching on the console should still work.
 717
 718UPDATE: refer to https://bugs.freedesktop.org/show_bug.cgi?id=2000
 719
 720
 721ThinkLight control
 722------------------
 723
 724procfs: /proc/acpi/ibm/light
 725sysfs attributes: as per LED class, for the "tpacpi::thinklight" LED
 726
 727procfs notes:
 728
 729The ThinkLight status can be read and set through the procfs interface.  A
 730few models which do not make the status available will show the ThinkLight
 731status as "unknown". The available commands are:
 732
 733        echo on  > /proc/acpi/ibm/light
 734        echo off > /proc/acpi/ibm/light
 735
 736sysfs notes:
 737
 738The ThinkLight sysfs interface is documented by the LED class
 739documentation, in Documentation/leds/leds-class.txt.  The ThinkLight LED name
 740is "tpacpi::thinklight".
 741
 742Due to limitations in the sysfs LED class, if the status of the ThinkLight
 743cannot be read or if it is unknown, thinkpad-acpi will report it as "off".
 744It is impossible to know if the status returned through sysfs is valid.
 745
 746
 747CMOS/UCMS control
 748-----------------
 749
 750procfs: /proc/acpi/ibm/cmos
 751sysfs device attribute: cmos_command
 752
 753This feature is mostly used internally by the ACPI firmware to keep the legacy
 754CMOS NVRAM bits in sync with the current machine state, and to record this
 755state so that the ThinkPad will retain such settings across reboots.
 756
 757Some of these commands actually perform actions in some ThinkPad models, but
 758this is expected to disappear more and more in newer models.  As an example, in
 759a T43 and in a X40, commands 12 and 13 still control the ThinkLight state for
 760real, but commands 0 to 2 don't control the mixer anymore (they have been
 761phased out) and just update the NVRAM.
 762
 763The range of valid cmos command numbers is 0 to 21, but not all have an
 764effect and the behavior varies from model to model.  Here is the behavior
 765on the X40 (tpb is the ThinkPad Buttons utility):
 766
 767        0 - Related to "Volume down" key press
 768        1 - Related to "Volume up" key press
 769        2 - Related to "Mute on" key press
 770        3 - Related to "Access IBM" key press
 771        4 - Related to "LCD brightness up" key press
 772        5 - Related to "LCD brightness down" key press
 773        11 - Related to "toggle screen expansion" key press/function
 774        12 - Related to "ThinkLight on"
 775        13 - Related to "ThinkLight off"
 776        14 - Related to "ThinkLight" key press (toggle ThinkLight)
 777
 778The cmos command interface is prone to firmware split-brain problems, as
 779in newer ThinkPads it is just a compatibility layer.  Do not use it, it is
 780exported just as a debug tool.
 781
 782
 783LED control
 784-----------
 785
 786procfs: /proc/acpi/ibm/led
 787sysfs attributes: as per LED class, see below for names
 788
 789Some of the LED indicators can be controlled through this feature.  On
 790some older ThinkPad models, it is possible to query the status of the
 791LED indicators as well.  Newer ThinkPads cannot query the real status
 792of the LED indicators.
 793
 794Because misuse of the LEDs could induce an unaware user to perform
 795dangerous actions (like undocking or ejecting a bay device while the
 796buses are still active), or mask an important alarm (such as a nearly
 797empty battery, or a broken battery), access to most LEDs is
 798restricted.
 799
 800Unrestricted access to all LEDs requires that thinkpad-acpi be
 801compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
 802Distributions must never enable this option.  Individual users that
 803are aware of the consequences are welcome to enabling it.
 804
 805procfs notes:
 806
 807The available commands are:
 808
 809        echo '<LED number> on' >/proc/acpi/ibm/led
 810        echo '<LED number> off' >/proc/acpi/ibm/led
 811        echo '<LED number> blink' >/proc/acpi/ibm/led
 812
 813The <LED number> range is 0 to 15. The set of LEDs that can be
 814controlled varies from model to model. Here is the common ThinkPad
 815mapping:
 816
 817        0 - power
 818        1 - battery (orange)
 819        2 - battery (green)
 820        3 - UltraBase/dock
 821        4 - UltraBay
 822        5 - UltraBase battery slot
 823        6 - (unknown)
 824        7 - standby
 825        8 - dock status 1
 826        9 - dock status 2
 827        10, 11 - (unknown)
 828        12 - thinkvantage
 829        13, 14, 15 - (unknown)
 830
 831All of the above can be turned on and off and can be made to blink.
 832
 833sysfs notes:
 834
 835The ThinkPad LED sysfs interface is described in detail by the LED class
 836documentation, in Documentation/leds/leds-class.txt.
 837
 838The LEDs are named (in LED ID order, from 0 to 12):
 839"tpacpi::power", "tpacpi:orange:batt", "tpacpi:green:batt",
 840"tpacpi::dock_active", "tpacpi::bay_active", "tpacpi::dock_batt",
 841"tpacpi::unknown_led", "tpacpi::standby", "tpacpi::dock_status1",
 842"tpacpi::dock_status2", "tpacpi::unknown_led2", "tpacpi::unknown_led3",
 843"tpacpi::thinkvantage".
 844
 845Due to limitations in the sysfs LED class, if the status of the LED
 846indicators cannot be read due to an error, thinkpad-acpi will report it as
 847a brightness of zero (same as LED off).
 848
 849If the thinkpad firmware doesn't support reading the current status,
 850trying to read the current LED brightness will just return whatever
 851brightness was last written to that attribute.
 852
 853These LEDs can blink using hardware acceleration.  To request that a
 854ThinkPad indicator LED should blink in hardware accelerated mode, use the
 855"timer" trigger, and leave the delay_on and delay_off parameters set to
 856zero (to request hardware acceleration autodetection).
 857
 858LEDs that are known not to exist in a given ThinkPad model are not
 859made available through the sysfs interface.  If you have a dock and you
 860notice there are LEDs listed for your ThinkPad that do not exist (and
 861are not in the dock), or if you notice that there are missing LEDs,
 862a report to ibm-acpi-devel@lists.sourceforge.net is appreciated.
 863
 864
 865ACPI sounds -- /proc/acpi/ibm/beep
 866----------------------------------
 867
 868The BEEP method is used internally by the ACPI firmware to provide
 869audible alerts in various situations. This feature allows the same
 870sounds to be triggered manually.
 871
 872The commands are non-negative integer numbers:
 873
 874        echo <number> >/proc/acpi/ibm/beep
 875
 876The valid <number> range is 0 to 17. Not all numbers trigger sounds
 877and the sounds vary from model to model. Here is the behavior on the
 878X40:
 879
 880        0 - stop a sound in progress (but use 17 to stop 16)
 881        2 - two beeps, pause, third beep ("low battery")
 882        3 - single beep
 883        4 - high, followed by low-pitched beep ("unable")
 884        5 - single beep
 885        6 - very high, followed by high-pitched beep ("AC/DC")
 886        7 - high-pitched beep
 887        9 - three short beeps
 888        10 - very long beep
 889        12 - low-pitched beep
 890        15 - three high-pitched beeps repeating constantly, stop with 0
 891        16 - one medium-pitched beep repeating constantly, stop with 17
 892        17 - stop 16
 893
 894
 895Temperature sensors
 896-------------------
 897
 898procfs: /proc/acpi/ibm/thermal
 899sysfs device attributes: (hwmon "thinkpad") temp*_input
 900
 901Most ThinkPads include six or more separate temperature sensors but only
 902expose the CPU temperature through the standard ACPI methods.  This
 903feature shows readings from up to eight different sensors on older
 904ThinkPads, and up to sixteen different sensors on newer ThinkPads.
 905
 906For example, on the X40, a typical output may be:
 907temperatures:   42 42 45 41 36 -128 33 -128
 908
 909On the T43/p, a typical output may be:
 910temperatures:   48 48 36 52 38 -128 31 -128 48 52 48 -128 -128 -128 -128 -128
 911
 912The mapping of thermal sensors to physical locations varies depending on
 913system-board model (and thus, on ThinkPad model).
 914
 915http://thinkwiki.org/wiki/Thermal_Sensors is a public wiki page that
 916tries to track down these locations for various models.
 917
 918Most (newer?) models seem to follow this pattern:
 919
 9201:  CPU
 9212:  (depends on model)
 9223:  (depends on model)
 9234:  GPU
 9245:  Main battery: main sensor
 9256:  Bay battery: main sensor
 9267:  Main battery: secondary sensor
 9278:  Bay battery: secondary sensor
 9289-15: (depends on model)
 929
 930For the R51 (source: Thomas Gruber):
 9312:  Mini-PCI
 9323:  Internal HDD
 933
 934For the T43, T43/p (source: Shmidoax/Thinkwiki.org)
 935http://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_T43.2C_T43p
 9362:  System board, left side (near PCMCIA slot), reported as HDAPS temp
 9373:  PCMCIA slot
 9389:  MCH (northbridge) to DRAM Bus
 93910: Clock-generator, mini-pci card and ICH (southbridge), under Mini-PCI
 940    card, under touchpad
 94111: Power regulator, underside of system board, below F2 key
 942
 943The A31 has a very atypical layout for the thermal sensors
 944(source: Milos Popovic, http://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_A31)
 9451:  CPU
 9462:  Main Battery: main sensor
 9473:  Power Converter
 9484:  Bay Battery: main sensor
 9495:  MCH (northbridge)
 9506:  PCMCIA/ambient
 9517:  Main Battery: secondary sensor
 9528:  Bay Battery: secondary sensor
 953
 954
 955Procfs notes:
 956        Readings from sensors that are not available return -128.
 957        No commands can be written to this file.
 958
 959Sysfs notes:
 960        Sensors that are not available return the ENXIO error.  This
 961        status may change at runtime, as there are hotplug thermal
 962        sensors, like those inside the batteries and docks.
 963
 964        thinkpad-acpi thermal sensors are reported through the hwmon
 965        subsystem, and follow all of the hwmon guidelines at
 966        Documentation/hwmon.
 967
 968EXPERIMENTAL: Embedded controller register dump
 969-----------------------------------------------
 970
 971This feature is not included in the thinkpad driver anymore.
 972Instead the EC can be accessed through /sys/kernel/debug/ec with
 973a userspace tool which can be found here:
 974ftp://ftp.suse.com/pub/people/trenn/sources/ec
 975
 976Use it to determine the register holding the fan
 977speed on some models. To do that, do the following:
 978        - make sure the battery is fully charged
 979        - make sure the fan is running
 980        - use above mentioned tool to read out the EC
 981
 982Often fan and temperature values vary between
 983readings. Since temperatures don't change vary fast, you can take
 984several quick dumps to eliminate them.
 985
 986You can use a similar method to figure out the meaning of other
 987embedded controller registers - e.g. make sure nothing else changes
 988except the charging or discharging battery to determine which
 989registers contain the current battery capacity, etc. If you experiment
 990with this, do send me your results (including some complete dumps with
 991a description of the conditions when they were taken.)
 992
 993
 994LCD brightness control
 995----------------------
 996
 997procfs: /proc/acpi/ibm/brightness
 998sysfs backlight device "thinkpad_screen"
 999
1000This feature allows software control of the LCD brightness on ThinkPad
1001models which don't have a hardware brightness slider.
1002
1003It has some limitations: the LCD backlight cannot be actually turned
1004on or off by this interface, it just controls the backlight brightness
1005level.
1006
1007On IBM (and some of the earlier Lenovo) ThinkPads, the backlight control
1008has eight brightness levels, ranging from 0 to 7.  Some of the levels
1009may not be distinct.  Later Lenovo models that implement the ACPI
1010display backlight brightness control methods have 16 levels, ranging
1011from 0 to 15.
1012
1013For IBM ThinkPads, there are two interfaces to the firmware for direct
1014brightness control, EC and UCMS (or CMOS).  To select which one should be
1015used, use the brightness_mode module parameter: brightness_mode=1 selects
1016EC mode, brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
1017mode with NVRAM backing (so that brightness changes are remembered across
1018shutdown/reboot).
1019
1020The driver tries to select which interface to use from a table of
1021defaults for each ThinkPad model.  If it makes a wrong choice, please
1022report this as a bug, so that we can fix it.
1023
1024Lenovo ThinkPads only support brightness_mode=2 (UCMS).
1025
1026When display backlight brightness controls are available through the
1027standard ACPI interface, it is best to use it instead of this direct
1028ThinkPad-specific interface.  The driver will disable its native
1029backlight brightness control interface if it detects that the standard
1030ACPI interface is available in the ThinkPad.
1031
1032If you want to use the thinkpad-acpi backlight brightness control
1033instead of the generic ACPI video backlight brightness control for some
1034reason, you should use the acpi_backlight=vendor kernel parameter.
1035
1036The brightness_enable module parameter can be used to control whether
1037the LCD brightness control feature will be enabled when available.
1038brightness_enable=0 forces it to be disabled.  brightness_enable=1
1039forces it to be enabled when available, even if the standard ACPI
1040interface is also available.
1041
1042Procfs notes:
1043
1044        The available commands are:
1045
1046        echo up   >/proc/acpi/ibm/brightness
1047        echo down >/proc/acpi/ibm/brightness
1048        echo 'level <level>' >/proc/acpi/ibm/brightness
1049
1050Sysfs notes:
1051
1052The interface is implemented through the backlight sysfs class, which is
1053poorly documented at this time.
1054
1055Locate the thinkpad_screen device under /sys/class/backlight, and inside
1056it there will be the following attributes:
1057
1058        max_brightness:
1059                Reads the maximum brightness the hardware can be set to.
1060                The minimum is always zero.
1061
1062        actual_brightness:
1063                Reads what brightness the screen is set to at this instant.
1064
1065        brightness:
1066                Writes request the driver to change brightness to the
1067                given value.  Reads will tell you what brightness the
1068                driver is trying to set the display to when "power" is set
1069                to zero and the display has not been dimmed by a kernel
1070                power management event.
1071
1072        power:
1073                power management mode, where 0 is "display on", and 1 to 3
1074                will dim the display backlight to brightness level 0
1075                because thinkpad-acpi cannot really turn the backlight
1076                off.  Kernel power management events can temporarily
1077                increase the current power management level, i.e. they can
1078                dim the display.
1079
1080
1081WARNING:
1082
1083    Whatever you do, do NOT ever call thinkpad-acpi backlight-level change
1084    interface and the ACPI-based backlight level change interface
1085    (available on newer BIOSes, and driven by the Linux ACPI video driver)
1086    at the same time.  The two will interact in bad ways, do funny things,
1087    and maybe reduce the life of the backlight lamps by needlessly kicking
1088    its level up and down at every change.
1089
1090
1091Volume control (Console Audio control)
1092--------------------------------------
1093
1094procfs: /proc/acpi/ibm/volume
1095ALSA: "ThinkPad Console Audio Control", default ID: "ThinkPadEC"
1096
1097NOTE: by default, the volume control interface operates in read-only
1098mode, as it is supposed to be used for on-screen-display purposes.
1099The read/write mode can be enabled through the use of the
1100"volume_control=1" module parameter.
1101
1102NOTE: distros are urged to not enable volume_control by default, this
1103should be done by the local admin only.  The ThinkPad UI is for the
1104console audio control to be done through the volume keys only, and for
1105the desktop environment to just provide on-screen-display feedback.
1106Software volume control should be done only in the main AC97/HDA
1107mixer.
1108
1109
1110About the ThinkPad Console Audio control:
1111
1112ThinkPads have a built-in amplifier and muting circuit that drives the
1113console headphone and speakers.  This circuit is after the main AC97
1114or HDA mixer in the audio path, and under exclusive control of the
1115firmware.
1116
1117ThinkPads have three special hotkeys to interact with the console
1118audio control: volume up, volume down and mute.
1119
1120It is worth noting that the normal way the mute function works (on
1121ThinkPads that do not have a "mute LED") is:
1122
11231. Press mute to mute.  It will *always* mute, you can press it as
1124   many times as you want, and the sound will remain mute.
1125
11262. Press either volume key to unmute the ThinkPad (it will _not_
1127   change the volume, it will just unmute).
1128
1129This is a very superior design when compared to the cheap software-only
1130mute-toggle solution found on normal consumer laptops:  you can be
1131absolutely sure the ThinkPad will not make noise if you press the mute
1132button, no matter the previous state.
1133
1134The IBM ThinkPads, and the earlier Lenovo ThinkPads have variable-gain
1135amplifiers driving the speakers and headphone output, and the firmware
1136also handles volume control for the headphone and speakers on these
1137ThinkPads without any help from the operating system (this volume
1138control stage exists after the main AC97 or HDA mixer in the audio
1139path).
1140
1141The newer Lenovo models only have firmware mute control, and depend on
1142the main HDA mixer to do volume control (which is done by the operating
1143system).  In this case, the volume keys are filtered out for unmute
1144key press (there are some firmware bugs in this area) and delivered as
1145normal key presses to the operating system (thinkpad-acpi is not
1146involved).
1147
1148
1149The ThinkPad-ACPI volume control:
1150
1151The preferred way to interact with the Console Audio control is the
1152ALSA interface.
1153
1154The legacy procfs interface allows one to read the current state,
1155and if volume control is enabled, accepts the following commands:
1156
1157        echo up   >/proc/acpi/ibm/volume
1158        echo down >/proc/acpi/ibm/volume
1159        echo mute >/proc/acpi/ibm/volume
1160        echo unmute >/proc/acpi/ibm/volume
1161        echo 'level <level>' >/proc/acpi/ibm/volume
1162
1163The <level> number range is 0 to 14 although not all of them may be
1164distinct. To unmute the volume after the mute command, use either the
1165up or down command (the level command will not unmute the volume), or
1166the unmute command.
1167
1168You can use the volume_capabilities parameter to tell the driver
1169whether your thinkpad has volume control or mute-only control:
1170volume_capabilities=1 for mixers with mute and volume control,
1171volume_capabilities=2 for mixers with only mute control.
1172
1173If the driver misdetects the capabilities for your ThinkPad model,
1174please report this to ibm-acpi-devel@lists.sourceforge.net, so that we
1175can update the driver.
1176
1177There are two strategies for volume control.  To select which one
1178should be used, use the volume_mode module parameter: volume_mode=1
1179selects EC mode, and volume_mode=3 selects EC mode with NVRAM backing
1180(so that volume/mute changes are remembered across shutdown/reboot).
1181
1182The driver will operate in volume_mode=3 by default. If that does not
1183work well on your ThinkPad model, please report this to
1184ibm-acpi-devel@lists.sourceforge.net.
1185
1186The driver supports the standard ALSA module parameters.  If the ALSA
1187mixer is disabled, the driver will disable all volume functionality.
1188
1189
1190Fan control and monitoring: fan speed, fan enable/disable
1191---------------------------------------------------------
1192
1193procfs: /proc/acpi/ibm/fan
1194sysfs device attributes: (hwmon "thinkpad") fan1_input, pwm1,
1195                          pwm1_enable, fan2_input
1196sysfs hwmon driver attributes: fan_watchdog
1197
1198NOTE NOTE NOTE: fan control operations are disabled by default for
1199safety reasons.  To enable them, the module parameter "fan_control=1"
1200must be given to thinkpad-acpi.
1201
1202This feature attempts to show the current fan speed, control mode and
1203other fan data that might be available.  The speed is read directly
1204from the hardware registers of the embedded controller.  This is known
1205to work on later R, T, X and Z series ThinkPads but may show a bogus
1206value on other models.
1207
1208Some Lenovo ThinkPads support a secondary fan.  This fan cannot be
1209controlled separately, it shares the main fan control.
1210
1211Fan levels:
1212
1213Most ThinkPad fans work in "levels" at the firmware interface.  Level 0
1214stops the fan.  The higher the level, the higher the fan speed, although
1215adjacent levels often map to the same fan speed.  7 is the highest
1216level, where the fan reaches the maximum recommended speed.
1217
1218Level "auto" means the EC changes the fan level according to some
1219internal algorithm, usually based on readings from the thermal sensors.
1220
1221There is also a "full-speed" level, also known as "disengaged" level.
1222In this level, the EC disables the speed-locked closed-loop fan control,
1223and drives the fan as fast as it can go, which might exceed hardware
1224limits, so use this level with caution.
1225
1226The fan usually ramps up or down slowly from one speed to another, and
1227it is normal for the EC to take several seconds to react to fan
1228commands.  The full-speed level may take up to two minutes to ramp up to
1229maximum speed, and in some ThinkPads, the tachometer readings go stale
1230while the EC is transitioning to the full-speed level.
1231
1232WARNING WARNING WARNING: do not leave the fan disabled unless you are
1233monitoring all of the temperature sensor readings and you are ready to
1234enable it if necessary to avoid overheating.
1235
1236An enabled fan in level "auto" may stop spinning if the EC decides the
1237ThinkPad is cool enough and doesn't need the extra airflow.  This is
1238normal, and the EC will spin the fan up if the various thermal readings
1239rise too much.
1240
1241On the X40, this seems to depend on the CPU and HDD temperatures.
1242Specifically, the fan is turned on when either the CPU temperature
1243climbs to 56 degrees or the HDD temperature climbs to 46 degrees.  The
1244fan is turned off when the CPU temperature drops to 49 degrees and the
1245HDD temperature drops to 41 degrees.  These thresholds cannot
1246currently be controlled.
1247
1248The ThinkPad's ACPI DSDT code will reprogram the fan on its own when
1249certain conditions are met.  It will override any fan programming done
1250through thinkpad-acpi.
1251
1252The thinkpad-acpi kernel driver can be programmed to revert the fan
1253level to a safe setting if userspace does not issue one of the procfs
1254fan commands: "enable", "disable", "level" or "watchdog", or if there
1255are no writes to pwm1_enable (or to pwm1 *if and only if* pwm1_enable is
1256set to 1, manual mode) within a configurable amount of time of up to
1257120 seconds.  This functionality is called fan safety watchdog.
1258
1259Note that the watchdog timer stops after it enables the fan.  It will be
1260rearmed again automatically (using the same interval) when one of the
1261above mentioned fan commands is received.  The fan watchdog is,
1262therefore, not suitable to protect against fan mode changes made through
1263means other than the "enable", "disable", and "level" procfs fan
1264commands, or the hwmon fan control sysfs interface.
1265
1266Procfs notes:
1267
1268The fan may be enabled or disabled with the following commands:
1269
1270        echo enable  >/proc/acpi/ibm/fan
1271        echo disable >/proc/acpi/ibm/fan
1272
1273Placing a fan on level 0 is the same as disabling it.  Enabling a fan
1274will try to place it in a safe level if it is too slow or disabled.
1275
1276The fan level can be controlled with the command:
1277
1278        echo 'level <level>' > /proc/acpi/ibm/fan
1279
1280Where <level> is an integer from 0 to 7, or one of the words "auto" or
1281"full-speed" (without the quotes).  Not all ThinkPads support the "auto"
1282and "full-speed" levels.  The driver accepts "disengaged" as an alias for
1283"full-speed", and reports it as "disengaged" for backwards
1284compatibility.
1285
1286On the X31 and X40 (and ONLY on those models), the fan speed can be
1287controlled to a certain degree.  Once the fan is running, it can be
1288forced to run faster or slower with the following command:
1289
1290        echo 'speed <speed>' > /proc/acpi/ibm/fan
1291
1292The sustainable range of fan speeds on the X40 appears to be from about
12933700 to about 7350. Values outside this range either do not have any
1294effect or the fan speed eventually settles somewhere in that range.  The
1295fan cannot be stopped or started with this command.  This functionality
1296is incomplete, and not available through the sysfs interface.
1297
1298To program the safety watchdog, use the "watchdog" command.
1299
1300        echo 'watchdog <interval in seconds>' > /proc/acpi/ibm/fan
1301
1302If you want to disable the watchdog, use 0 as the interval.
1303
1304Sysfs notes:
1305
1306The sysfs interface follows the hwmon subsystem guidelines for the most
1307part, and the exception is the fan safety watchdog.
1308
1309Writes to any of the sysfs attributes may return the EINVAL error if
1310that operation is not supported in a given ThinkPad or if the parameter
1311is out-of-bounds, and EPERM if it is forbidden.  They may also return
1312EINTR (interrupted system call), and EIO (I/O error while trying to talk
1313to the firmware).
1314
1315Features not yet implemented by the driver return ENOSYS.
1316
1317hwmon device attribute pwm1_enable:
1318        0: PWM offline (fan is set to full-speed mode)
1319        1: Manual PWM control (use pwm1 to set fan level)
1320        2: Hardware PWM control (EC "auto" mode)
1321        3: reserved (Software PWM control, not implemented yet)
1322
1323        Modes 0 and 2 are not supported by all ThinkPads, and the
1324        driver is not always able to detect this.  If it does know a
1325        mode is unsupported, it will return -EINVAL.
1326
1327hwmon device attribute pwm1:
1328        Fan level, scaled from the firmware values of 0-7 to the hwmon
1329        scale of 0-255.  0 means fan stopped, 255 means highest normal
1330        speed (level 7).
1331
1332        This attribute only commands the fan if pmw1_enable is set to 1
1333        (manual PWM control).
1334
1335hwmon device attribute fan1_input:
1336        Fan tachometer reading, in RPM.  May go stale on certain
1337        ThinkPads while the EC transitions the PWM to offline mode,
1338        which can take up to two minutes.  May return rubbish on older
1339        ThinkPads.
1340
1341hwmon device attribute fan2_input:
1342        Fan tachometer reading, in RPM, for the secondary fan.
1343        Available only on some ThinkPads.  If the secondary fan is
1344        not installed, will always read 0.
1345
1346hwmon driver attribute fan_watchdog:
1347        Fan safety watchdog timer interval, in seconds.  Minimum is
1348        1 second, maximum is 120 seconds.  0 disables the watchdog.
1349
1350To stop the fan: set pwm1 to zero, and pwm1_enable to 1.
1351
1352To start the fan in a safe mode: set pwm1_enable to 2.  If that fails
1353with EINVAL, try to set pwm1_enable to 1 and pwm1 to at least 128 (255
1354would be the safest choice, though).
1355
1356
1357WAN
1358---
1359
1360procfs: /proc/acpi/ibm/wan
1361sysfs device attribute: wwan_enable (deprecated)
1362sysfs rfkill class: switch "tpacpi_wwan_sw"
1363
1364This feature shows the presence and current state of the built-in
1365Wireless WAN device.
1366
1367If the ThinkPad supports it, the WWAN state is stored in NVRAM,
1368so it is kept across reboots and power-off.
1369
1370It was tested on a Lenovo ThinkPad X60. It should probably work on other
1371ThinkPad models which come with this module installed.
1372
1373Procfs notes:
1374
1375If the W-WAN card is installed, the following commands can be used:
1376
1377        echo enable > /proc/acpi/ibm/wan
1378        echo disable > /proc/acpi/ibm/wan
1379
1380Sysfs notes:
1381
1382        If the W-WAN card is installed, it can be enabled /
1383        disabled through the "wwan_enable" thinkpad-acpi device
1384        attribute, and its current status can also be queried.
1385
1386        enable:
1387                0: disables WWAN card / WWAN card is disabled
1388                1: enables WWAN card / WWAN card is enabled.
1389
1390        Note: this interface has been superseded by the generic rfkill
1391        class.  It has been deprecated, and it will be removed in year
1392        2010.
1393
1394        rfkill controller switch "tpacpi_wwan_sw": refer to
1395        Documentation/rfkill.txt for details.
1396
1397
1398EXPERIMENTAL: UWB
1399-----------------
1400
1401This feature is marked EXPERIMENTAL because it has not been extensively
1402tested and validated in various ThinkPad models yet.  The feature may not
1403work as expected. USE WITH CAUTION! To use this feature, you need to supply
1404the experimental=1 parameter when loading the module.
1405
1406sysfs rfkill class: switch "tpacpi_uwb_sw"
1407
1408This feature exports an rfkill controller for the UWB device, if one is
1409present and enabled in the BIOS.
1410
1411Sysfs notes:
1412
1413        rfkill controller switch "tpacpi_uwb_sw": refer to
1414        Documentation/rfkill.txt for details.
1415
1416
1417Multiple Commands, Module Parameters
1418------------------------------------
1419
1420Multiple commands can be written to the proc files in one shot by
1421separating them with commas, for example:
1422
1423        echo enable,0xffff > /proc/acpi/ibm/hotkey
1424        echo lcd_disable,crt_enable > /proc/acpi/ibm/video
1425
1426Commands can also be specified when loading the thinkpad-acpi module,
1427for example:
1428
1429        modprobe thinkpad_acpi hotkey=enable,0xffff video=auto_disable
1430
1431
1432Enabling debugging output
1433-------------------------
1434
1435The module takes a debug parameter which can be used to selectively
1436enable various classes of debugging output, for example:
1437
1438         modprobe thinkpad_acpi debug=0xffff
1439
1440will enable all debugging output classes.  It takes a bitmask, so
1441to enable more than one output class, just add their values.
1442
1443        Debug bitmask           Description
1444        0x8000                  Disclose PID of userspace programs
1445                                accessing some functions of the driver
1446        0x0001                  Initialization and probing
1447        0x0002                  Removal
1448        0x0004                  RF Transmitter control (RFKILL)
1449                                (bluetooth, WWAN, UWB...)
1450        0x0008                  HKEY event interface, hotkeys
1451        0x0010                  Fan control
1452        0x0020                  Backlight brightness
1453        0x0040                  Audio mixer/volume control
1454
1455There is also a kernel build option to enable more debugging
1456information, which may be necessary to debug driver problems.
1457
1458The level of debugging information output by the driver can be changed
1459at runtime through sysfs, using the driver attribute debug_level.  The
1460attribute takes the same bitmask as the debug module parameter above.
1461
1462
1463Force loading of module
1464-----------------------
1465
1466If thinkpad-acpi refuses to detect your ThinkPad, you can try to specify
1467the module parameter force_load=1.  Regardless of whether this works or
1468not, please contact ibm-acpi-devel@lists.sourceforge.net with a report.
1469
1470
1471Sysfs interface changelog:
1472
14730x000100:       Initial sysfs support, as a single platform driver and
1474                device.
14750x000200:       Hot key support for 32 hot keys, and radio slider switch
1476                support.
14770x010000:       Hot keys are now handled by default over the input
1478                layer, the radio switch generates input event EV_RADIO,
1479                and the driver enables hot key handling by default in
1480                the firmware.
1481
14820x020000:       ABI fix: added a separate hwmon platform device and
1483                driver, which must be located by name (thinkpad)
1484                and the hwmon class for libsensors4 (lm-sensors 3)
1485                compatibility.  Moved all hwmon attributes to this
1486                new platform device.
1487
14880x020100:       Marker for thinkpad-acpi with hot key NVRAM polling
1489                support.  If you must, use it to know you should not
1490                start a userspace NVRAM poller (allows to detect when
1491                NVRAM is compiled out by the user because it is
1492                unneeded/undesired in the first place).
14930x020101:       Marker for thinkpad-acpi with hot key NVRAM polling
1494                and proper hotkey_mask semantics (version 8 of the
1495                NVRAM polling patch).  Some development snapshots of
1496                0.18 had an earlier version that did strange things
1497                to hotkey_mask.
1498
14990x020200:       Add poll()/select() support to the following attributes:
1500                hotkey_radio_sw, wakeup_hotunplug_complete, wakeup_reason
1501
15020x020300:       hotkey enable/disable support removed, attributes
1503                hotkey_bios_enabled and hotkey_enable deprecated and
1504                marked for removal.
1505
15060x020400:       Marker for 16 LEDs support.  Also, LEDs that are known
1507                to not exist in a given model are not registered with
1508                the LED sysfs class anymore.
1509
15100x020500:       Updated hotkey driver, hotkey_mask is always available
1511                and it is always able to disable hot keys.  Very old
1512                thinkpads are properly supported.  hotkey_bios_mask
1513                is deprecated and marked for removal.
1514
15150x020600:       Marker for backlight change event support.
1516
15170x020700:       Support for mute-only mixers.
1518                Volume control in read-only mode by default.
1519                Marker for ALSA mixer support.
1520
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