1===========================
2ThinkPad ACPI Extras Driver
3===========================
4
5Version 0.25
6
7October 16th,  2013
8
9- Borislav Deianov <borislav@users.sf.net>
10- Henrique de Moraes Holschuh <hmh@hmh.eng.br>
11
12http://ibm-acpi.sf.net/
13
14This is a Linux driver for the IBM and Lenovo ThinkPad laptops. It
15supports various features of these laptops which are accessible
16through the ACPI and ACPI EC framework, but not otherwise fully
17supported by the generic Linux ACPI drivers.
18
19This driver used to be named ibm-acpi until kernel 2.6.21 and release
200.13-20070314.  It used to be in the drivers/acpi tree, but it was
21moved to the drivers/misc tree and renamed to thinkpad-acpi for kernel
222.6.22, and release 0.14.  It was moved to drivers/platform/x86 for
23kernel 2.6.29 and release 0.22.
24
25The driver is named "thinkpad-acpi".  In some places, like module
26names and log messages, "thinkpad_acpi" is used because of userspace
27issues.
28
29"tpacpi" is used as a shorthand where "thinkpad-acpi" would be too
30long due to length limitations on some Linux kernel versions.
31
32Status
33------
34
35The features currently supported are the following (see below for
36detailed description):
37
38	- Fn key combinations
39	- Bluetooth enable and disable
40	- video output switching, expansion control
41	- ThinkLight on and off
42	- CMOS/UCMS control
43	- LED control
44	- ACPI sounds
45	- temperature sensors
46	- Experimental: embedded controller register dump
47	- LCD brightness control
48	- Volume control
49	- Fan control and monitoring: fan speed, fan enable/disable
50	- WAN enable and disable
51	- UWB enable and disable
52	- LCD Shadow (PrivacyGuard) enable and disable
53	- Lap mode sensor
54	- Setting keyboard language
55	- WWAN Antenna type
56
57A compatibility table by model and feature is maintained on the web
58site, http://ibm-acpi.sf.net/. I appreciate any success or failure
59reports, especially if they add to or correct the compatibility table.
60Please include the following information in your report:
61
62	- ThinkPad model name
63	- a copy of your ACPI tables, using the "acpidump" utility
64	- a copy of the output of dmidecode, with serial numbers
65	  and UUIDs masked off
66	- which driver features work and which don't
67	- the observed behavior of non-working features
68
69Any other comments or patches are also more than welcome.
70
71
72Installation
73------------
74
75If you are compiling this driver as included in the Linux kernel
76sources, look for the CONFIG_THINKPAD_ACPI Kconfig option.
77It is located on the menu path: "Device Drivers" -> "X86 Platform
78Specific Device Drivers" -> "ThinkPad ACPI Laptop Extras".
79
80
81Features
82--------
83
84The driver exports two different interfaces to userspace, which can be
85used to access the features it provides.  One is a legacy procfs-based
86interface, which will be removed at some time in the future.  The other
87is a new sysfs-based interface which is not complete yet.
88
89The procfs interface creates the /proc/acpi/ibm directory.  There is a
90file under that directory for each feature it supports.  The procfs
91interface is mostly frozen, and will change very little if at all: it
92will not be extended to add any new functionality in the driver, instead
93all new functionality will be implemented on the sysfs interface.
94
95The sysfs interface tries to blend in the generic Linux sysfs subsystems
96and classes as much as possible.  Since some of these subsystems are not
97yet ready or stabilized, it is expected that this interface will change,
98and any and all userspace programs must deal with it.
99
100
101Notes about the sysfs interface
102^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
103
104Unlike what was done with the procfs interface, correctness when talking
105to the sysfs interfaces will be enforced, as will correctness in the
106thinkpad-acpi's implementation of sysfs interfaces.
107
108Also, any bugs in the thinkpad-acpi sysfs driver code or in the
109thinkpad-acpi's implementation of the sysfs interfaces will be fixed for
110maximum correctness, even if that means changing an interface in
111non-compatible ways.  As these interfaces mature both in the kernel and
112in thinkpad-acpi, such changes should become quite rare.
113
114Applications interfacing to the thinkpad-acpi sysfs interfaces must
115follow all sysfs guidelines and correctly process all errors (the sysfs
116interface makes extensive use of errors).  File descriptors and open /
117close operations to the sysfs inodes must also be properly implemented.
118
119The version of thinkpad-acpi's sysfs interface is exported by the driver
120as a driver attribute (see below).
121
122Sysfs driver attributes are on the driver's sysfs attribute space,
123for 2.6.23+ this is /sys/bus/platform/drivers/thinkpad_acpi/ and
124/sys/bus/platform/drivers/thinkpad_hwmon/
125
126Sysfs device attributes are on the thinkpad_acpi device sysfs attribute
127space, for 2.6.23+ this is /sys/devices/platform/thinkpad_acpi/.
128
129Sysfs device attributes for the sensors and fan are on the
130thinkpad_hwmon device's sysfs attribute space, but you should locate it
131looking for a hwmon device with the name attribute of "thinkpad", or
132better yet, through libsensors. For 4.14+ sysfs attributes were moved to the
133hwmon device (/sys/bus/platform/devices/thinkpad_hwmon/hwmon/hwmon? or
134/sys/class/hwmon/hwmon?).
135
136Driver version
137--------------
138
139procfs: /proc/acpi/ibm/driver
140
141sysfs driver attribute: version
142
143The driver name and version. No commands can be written to this file.
144
145
146Sysfs interface version
147-----------------------
148
149sysfs driver attribute: interface_version
150
151Version of the thinkpad-acpi sysfs interface, as an unsigned long
152(output in hex format: 0xAAAABBCC), where:
153
154	AAAA
155	  - major revision
156	BB
157	  - minor revision
158	CC
159	  - bugfix revision
160
161The sysfs interface version changelog for the driver can be found at the
162end of this document.  Changes to the sysfs interface done by the kernel
163subsystems are not documented here, nor are they tracked by this
164attribute.
165
166Changes to the thinkpad-acpi sysfs interface are only considered
167non-experimental when they are submitted to Linux mainline, at which
168point the changes in this interface are documented and interface_version
169may be updated.  If you are using any thinkpad-acpi features not yet
170sent to mainline for merging, you do so on your own risk: these features
171may disappear, or be implemented in a different and incompatible way by
172the time they are merged in Linux mainline.
173
174Changes that are backwards-compatible by nature (e.g. the addition of
175attributes that do not change the way the other attributes work) do not
176always warrant an update of interface_version.  Therefore, one must
177expect that an attribute might not be there, and deal with it properly
178(an attribute not being there *is* a valid way to make it clear that a
179feature is not available in sysfs).
180
181
182Hot keys
183--------
184
185procfs: /proc/acpi/ibm/hotkey
186
187sysfs device attribute: hotkey_*
188
189In a ThinkPad, the ACPI HKEY handler is responsible for communicating
190some important events and also keyboard hot key presses to the operating
191system.  Enabling the hotkey functionality of thinkpad-acpi signals the
192firmware that such a driver is present, and modifies how the ThinkPad
193firmware will behave in many situations.
194
195The driver enables the HKEY ("hot key") event reporting automatically
196when loaded, and disables it when it is removed.
197
198The driver will report HKEY events in the following format::
199
200	ibm/hotkey HKEY 00000080 0000xxxx
201
202Some of these events refer to hot key presses, but not all of them.
203
204The driver will generate events over the input layer for hot keys and
205radio switches, and over the ACPI netlink layer for other events.  The
206input layer support accepts the standard IOCTLs to remap the keycodes
207assigned to each hot key.
208
209The hot key bit mask allows some control over which hot keys generate
210events.  If a key is "masked" (bit set to 0 in the mask), the firmware
211will handle it.  If it is "unmasked", it signals the firmware that
212thinkpad-acpi would prefer to handle it, if the firmware would be so
213kind to allow it (and it often doesn't!).
214
215Not all bits in the mask can be modified.  Not all bits that can be
216modified do anything.  Not all hot keys can be individually controlled
217by the mask.  Some models do not support the mask at all.  The behaviour
218of the mask is, therefore, highly dependent on the ThinkPad model.
219
220The driver will filter out any unmasked hotkeys, so even if the firmware
221doesn't allow disabling an specific hotkey, the driver will not report
222events for unmasked hotkeys.
223
224Note that unmasking some keys prevents their default behavior.  For
225example, if Fn+F5 is unmasked, that key will no longer enable/disable
226Bluetooth by itself in firmware.
227
228Note also that not all Fn key combinations are supported through ACPI
229depending on the ThinkPad model and firmware version.  On those
230ThinkPads, it is still possible to support some extra hotkeys by
231polling the "CMOS NVRAM" at least 10 times per second.  The driver
232attempts to enables this functionality automatically when required.
233
234procfs notes
235^^^^^^^^^^^^
236
237The following commands can be written to the /proc/acpi/ibm/hotkey file::
238
239	echo 0xffffffff > /proc/acpi/ibm/hotkey -- enable all hot keys
240	echo 0 > /proc/acpi/ibm/hotkey -- disable all possible hot keys
241	... any other 8-hex-digit mask ...
242	echo reset > /proc/acpi/ibm/hotkey -- restore the recommended mask
243
244The following commands have been deprecated and will cause the kernel
245to log a warning::
246
247	echo enable > /proc/acpi/ibm/hotkey -- does nothing
248	echo disable > /proc/acpi/ibm/hotkey -- returns an error
249
250The procfs interface does not support NVRAM polling control.  So as to
251maintain maximum bug-to-bug compatibility, it does not report any masks,
252nor does it allow one to manipulate the hot key mask when the firmware
253does not support masks at all, even if NVRAM polling is in use.
254
255sysfs notes
256^^^^^^^^^^^
257
258	hotkey_bios_enabled:
259		DEPRECATED, WILL BE REMOVED SOON.
260
261		Returns 0.
262
263	hotkey_bios_mask:
264		DEPRECATED, DON'T USE, WILL BE REMOVED IN THE FUTURE.
265
266		Returns the hot keys mask when thinkpad-acpi was loaded.
267		Upon module unload, the hot keys mask will be restored
268		to this value.   This is always 0x80c, because those are
269		the hotkeys that were supported by ancient firmware
270		without mask support.
271
272	hotkey_enable:
273		DEPRECATED, WILL BE REMOVED SOON.
274
275		0: returns -EPERM
276		1: does nothing
277
278	hotkey_mask:
279		bit mask to enable reporting (and depending on
280		the firmware, ACPI event generation) for each hot key
281		(see above).  Returns the current status of the hot keys
282		mask, and allows one to modify it.
283
284	hotkey_all_mask:
285		bit mask that should enable event reporting for all
286		supported hot keys, when echoed to hotkey_mask above.
287		Unless you know which events need to be handled
288		passively (because the firmware *will* handle them
289		anyway), do *not* use hotkey_all_mask.  Use
290		hotkey_recommended_mask, instead. You have been warned.
291
292	hotkey_recommended_mask:
293		bit mask that should enable event reporting for all
294		supported hot keys, except those which are always
295		handled by the firmware anyway.  Echo it to
296		hotkey_mask above, to use.  This is the default mask
297		used by the driver.
298
299	hotkey_source_mask:
300		bit mask that selects which hot keys will the driver
301		poll the NVRAM for.  This is auto-detected by the driver
302		based on the capabilities reported by the ACPI firmware,
303		but it can be overridden at runtime.
304
305		Hot keys whose bits are set in hotkey_source_mask are
306		polled for in NVRAM, and reported as hotkey events if
307		enabled in hotkey_mask.  Only a few hot keys are
308		available through CMOS NVRAM polling.
309
310		Warning: when in NVRAM mode, the volume up/down/mute
311		keys are synthesized according to changes in the mixer,
312		which uses a single volume up or volume down hotkey
313		press to unmute, as per the ThinkPad volume mixer user
314		interface.  When in ACPI event mode, volume up/down/mute
315		events are reported by the firmware and can behave
316		differently (and that behaviour changes with firmware
317		version -- not just with firmware models -- as well as
318		OSI(Linux) state).
319
320	hotkey_poll_freq:
321		frequency in Hz for hot key polling. It must be between
322		0 and 25 Hz.  Polling is only carried out when strictly
323		needed.
324
325		Setting hotkey_poll_freq to zero disables polling, and
326		will cause hot key presses that require NVRAM polling
327		to never be reported.
328
329		Setting hotkey_poll_freq too low may cause repeated
330		pressings of the same hot key to be misreported as a
331		single key press, or to not even be detected at all.
332		The recommended polling frequency is 10Hz.
333
334	hotkey_radio_sw:
335		If the ThinkPad has a hardware radio switch, this
336		attribute will read 0 if the switch is in the "radios
337		disabled" position, and 1 if the switch is in the
338		"radios enabled" position.
339
340		This attribute has poll()/select() support.
341
342	hotkey_tablet_mode:
343		If the ThinkPad has tablet capabilities, this attribute
344		will read 0 if the ThinkPad is in normal mode, and
345		1 if the ThinkPad is in tablet mode.
346
347		This attribute has poll()/select() support.
348
349	wakeup_reason:
350		Set to 1 if the system is waking up because the user
351		requested a bay ejection.  Set to 2 if the system is
352		waking up because the user requested the system to
353		undock.  Set to zero for normal wake-ups or wake-ups
354		due to unknown reasons.
355
356		This attribute has poll()/select() support.
357
358	wakeup_hotunplug_complete:
359		Set to 1 if the system was waken up because of an
360		undock or bay ejection request, and that request
361		was successfully completed.  At this point, it might
362		be useful to send the system back to sleep, at the
363		user's choice.  Refer to HKEY events 0x4003 and
364		0x3003, below.
365
366		This attribute has poll()/select() support.
367
368input layer notes
369^^^^^^^^^^^^^^^^^
370
371A Hot key is mapped to a single input layer EV_KEY event, possibly
372followed by an EV_MSC MSC_SCAN event that shall contain that key's scan
373code.  An EV_SYN event will always be generated to mark the end of the
374event block.
375
376Do not use the EV_MSC MSC_SCAN events to process keys.  They are to be
377used as a helper to remap keys, only.  They are particularly useful when
378remapping KEY_UNKNOWN keys.
379
380The events are available in an input device, with the following id:
381
382	==============  ==============================
383	Bus		BUS_HOST
384	vendor		0x1014 (PCI_VENDOR_ID_IBM)  or
385			0x17aa (PCI_VENDOR_ID_LENOVO)
386	product		0x5054 ("TP")
387	version		0x4101
388	==============  ==============================
389
390The version will have its LSB incremented if the keymap changes in a
391backwards-compatible way.  The MSB shall always be 0x41 for this input
392device.  If the MSB is not 0x41, do not use the device as described in
393this section, as it is either something else (e.g. another input device
394exported by a thinkpad driver, such as HDAPS) or its functionality has
395been changed in a non-backwards compatible way.
396
397Adding other event types for other functionalities shall be considered a
398backwards-compatible change for this input device.
399
400Thinkpad-acpi Hot Key event map (version 0x4101):
401
402=======	=======	==============	==============================================
403ACPI	Scan
404event	code	Key		Notes
405=======	=======	==============	==============================================
4060x1001	0x00	FN+F1		-
407
4080x1002	0x01	FN+F2		IBM: battery (rare)
409				Lenovo: Screen lock
410
4110x1003	0x02	FN+F3		Many IBM models always report
412				this hot key, even with hot keys
413				disabled or with Fn+F3 masked
414				off
415				IBM: screen lock, often turns
416				off the ThinkLight as side-effect
417				Lenovo: battery
418
4190x1004	0x03	FN+F4		Sleep button (ACPI sleep button
420				semantics, i.e. sleep-to-RAM).
421				It always generates some kind
422				of event, either the hot key
423				event or an ACPI sleep button
424				event. The firmware may
425				refuse to generate further FN+F4
426				key presses until a S3 or S4 ACPI
427				sleep cycle is performed or some
428				time passes.
429
4300x1005	0x04	FN+F5		Radio.  Enables/disables
431				the internal Bluetooth hardware
432				and W-WAN card if left in control
433				of the firmware.  Does not affect
434				the WLAN card.
435				Should be used to turn on/off all
436				radios (Bluetooth+W-WAN+WLAN),
437				really.
438
4390x1006	0x05	FN+F6		-
440
4410x1007	0x06	FN+F7		Video output cycle.
442				Do you feel lucky today?
443
4440x1008	0x07	FN+F8		IBM: toggle screen expand
445				Lenovo: configure UltraNav,
446				or toggle screen expand
447
4480x1009	0x08	FN+F9		-
449
450...	...	...		...
451
4520x100B	0x0A	FN+F11		-
453
4540x100C	0x0B	FN+F12		Sleep to disk.  You are always
455				supposed to handle it yourself,
456				either through the ACPI event,
457				or through a hotkey event.
458				The firmware may refuse to
459				generate further FN+F12 key
460				press events until a S3 or S4
461				ACPI sleep cycle is performed,
462				or some time passes.
463
4640x100D	0x0C	FN+BACKSPACE	-
4650x100E	0x0D	FN+INSERT	-
4660x100F	0x0E	FN+DELETE	-
467
4680x1010	0x0F	FN+HOME		Brightness up.  This key is
469				always handled by the firmware
470				in IBM ThinkPads, even when
471				unmasked.  Just leave it alone.
472				For Lenovo ThinkPads with a new
473				BIOS, it has to be handled either
474				by the ACPI OSI, or by userspace.
475				The driver does the right thing,
476				never mess with this.
4770x1011	0x10	FN+END		Brightness down.  See brightness
478				up for details.
479
4800x1012	0x11	FN+PGUP		ThinkLight toggle.  This key is
481				always handled by the firmware,
482				even when unmasked.
483
4840x1013	0x12	FN+PGDOWN	-
485
4860x1014	0x13	FN+SPACE	Zoom key
487
4880x1015	0x14	VOLUME UP	Internal mixer volume up. This
489				key is always handled by the
490				firmware, even when unmasked.
491				NOTE: Lenovo seems to be changing
492				this.
4930x1016	0x15	VOLUME DOWN	Internal mixer volume up. This
494				key is always handled by the
495				firmware, even when unmasked.
496				NOTE: Lenovo seems to be changing
497				this.
4980x1017	0x16	MUTE		Mute internal mixer. This
499				key is always handled by the
500				firmware, even when unmasked.
501
5020x1018	0x17	THINKPAD	ThinkPad/Access IBM/Lenovo key
503
5040x1019	0x18	unknown
505
506...	...	...
507
5080x1020	0x1F	unknown
509=======	=======	==============	==============================================
510
511The ThinkPad firmware does not allow one to differentiate when most hot
512keys are pressed or released (either that, or we don't know how to, yet).
513For these keys, the driver generates a set of events for a key press and
514immediately issues the same set of events for a key release.  It is
515unknown by the driver if the ThinkPad firmware triggered these events on
516hot key press or release, but the firmware will do it for either one, not
517both.
518
519If a key is mapped to KEY_RESERVED, it generates no input events at all.
520If a key is mapped to KEY_UNKNOWN, it generates an input event that
521includes an scan code.  If a key is mapped to anything else, it will
522generate input device EV_KEY events.
523
524In addition to the EV_KEY events, thinkpad-acpi may also issue EV_SW
525events for switches:
526
527==============	==============================================
528SW_RFKILL_ALL	T60 and later hardware rfkill rocker switch
529SW_TABLET_MODE	Tablet ThinkPads HKEY events 0x5009 and 0x500A
530==============	==============================================
531
532Non hotkey ACPI HKEY event map
533------------------------------
534
535Events that are never propagated by the driver:
536
537======		==================================================
5380x2304		System is waking up from suspend to undock
5390x2305		System is waking up from suspend to eject bay
5400x2404		System is waking up from hibernation to undock
5410x2405		System is waking up from hibernation to eject bay
5420x5001		Lid closed
5430x5002		Lid opened
5440x5009		Tablet swivel: switched to tablet mode
5450x500A		Tablet swivel: switched to normal mode
5460x5010		Brightness level changed/control event
5470x6000		KEYBOARD: Numlock key pressed
5480x6005		KEYBOARD: Fn key pressed (TO BE VERIFIED)
5490x7000		Radio Switch may have changed state
550======		==================================================
551
552
553Events that are propagated by the driver to userspace:
554
555======		=====================================================
5560x2313		ALARM: System is waking up from suspend because
557		the battery is nearly empty
5580x2413		ALARM: System is waking up from hibernation because
559		the battery is nearly empty
5600x3003		Bay ejection (see 0x2x05) complete, can sleep again
5610x3006		Bay hotplug request (hint to power up SATA link when
562		the optical drive tray is ejected)
5630x4003		Undocked (see 0x2x04), can sleep again
5640x4010		Docked into hotplug port replicator (non-ACPI dock)
5650x4011		Undocked from hotplug port replicator (non-ACPI dock)
5660x500B		Tablet pen inserted into its storage bay
5670x500C		Tablet pen removed from its storage bay
5680x6011		ALARM: battery is too hot
5690x6012		ALARM: battery is extremely hot
5700x6021		ALARM: a sensor is too hot
5710x6022		ALARM: a sensor is extremely hot
5720x6030		System thermal table changed
5730x6032		Thermal Control command set completion  (DYTC, Windows)
5740x6040		Nvidia Optimus/AC adapter related (TO BE VERIFIED)
5750x60C0		X1 Yoga 2016, Tablet mode status changed
5760x60F0		Thermal Transformation changed (GMTS, Windows)
577======		=====================================================
578
579Battery nearly empty alarms are a last resort attempt to get the
580operating system to hibernate or shutdown cleanly (0x2313), or shutdown
581cleanly (0x2413) before power is lost.  They must be acted upon, as the
582wake up caused by the firmware will have negated most safety nets...
583
584When any of the "too hot" alarms happen, according to Lenovo the user
585should suspend or hibernate the laptop (and in the case of battery
586alarms, unplug the AC adapter) to let it cool down.  These alarms do
587signal that something is wrong, they should never happen on normal
588operating conditions.
589
590The "extremely hot" alarms are emergencies.  According to Lenovo, the
591operating system is to force either an immediate suspend or hibernate
592cycle, or a system shutdown.  Obviously, something is very wrong if this
593happens.
594
595
596Brightness hotkey notes
597^^^^^^^^^^^^^^^^^^^^^^^
598
599Don't mess with the brightness hotkeys in a Thinkpad.  If you want
600notifications for OSD, use the sysfs backlight class event support.
601
602The driver will issue KEY_BRIGHTNESS_UP and KEY_BRIGHTNESS_DOWN events
603automatically for the cases were userspace has to do something to
604implement brightness changes.  When you override these events, you will
605either fail to handle properly the ThinkPads that require explicit
606action to change backlight brightness, or the ThinkPads that require
607that no action be taken to work properly.
608
609
610Bluetooth
611---------
612
613procfs: /proc/acpi/ibm/bluetooth
614
615sysfs device attribute: bluetooth_enable (deprecated)
616
617sysfs rfkill class: switch "tpacpi_bluetooth_sw"
618
619This feature shows the presence and current state of a ThinkPad
620Bluetooth device in the internal ThinkPad CDC slot.
621
622If the ThinkPad supports it, the Bluetooth state is stored in NVRAM,
623so it is kept across reboots and power-off.
624
625Procfs notes
626^^^^^^^^^^^^
627
628If Bluetooth is installed, the following commands can be used::
629
630	echo enable > /proc/acpi/ibm/bluetooth
631	echo disable > /proc/acpi/ibm/bluetooth
632
633Sysfs notes
634^^^^^^^^^^^
635
636	If the Bluetooth CDC card is installed, it can be enabled /
637	disabled through the "bluetooth_enable" thinkpad-acpi device
638	attribute, and its current status can also be queried.
639
640	enable:
641
642		- 0: disables Bluetooth / Bluetooth is disabled
643		- 1: enables Bluetooth / Bluetooth is enabled.
644
645	Note: this interface has been superseded by the	generic rfkill
646	class.  It has been deprecated, and it will be removed in year
647	2010.
648
649	rfkill controller switch "tpacpi_bluetooth_sw": refer to
650	Documentation/driver-api/rfkill.rst for details.
651
652
653Video output control -- /proc/acpi/ibm/video
654--------------------------------------------
655
656This feature allows control over the devices used for video output -
657LCD, CRT or DVI (if available). The following commands are available::
658
659	echo lcd_enable > /proc/acpi/ibm/video
660	echo lcd_disable > /proc/acpi/ibm/video
661	echo crt_enable > /proc/acpi/ibm/video
662	echo crt_disable > /proc/acpi/ibm/video
663	echo dvi_enable > /proc/acpi/ibm/video
664	echo dvi_disable > /proc/acpi/ibm/video
665	echo auto_enable > /proc/acpi/ibm/video
666	echo auto_disable > /proc/acpi/ibm/video
667	echo expand_toggle > /proc/acpi/ibm/video
668	echo video_switch > /proc/acpi/ibm/video
669
670NOTE:
671  Access to this feature is restricted to processes owning the
672  CAP_SYS_ADMIN capability for safety reasons, as it can interact badly
673  enough with some versions of X.org to crash it.
674
675Each video output device can be enabled or disabled individually.
676Reading /proc/acpi/ibm/video shows the status of each device.
677
678Automatic video switching can be enabled or disabled.  When automatic
679video switching is enabled, certain events (e.g. opening the lid,
680docking or undocking) cause the video output device to change
681automatically. While this can be useful, it also causes flickering
682and, on the X40, video corruption. By disabling automatic switching,
683the flickering or video corruption can be avoided.
684
685The video_switch command cycles through the available video outputs
686(it simulates the behavior of Fn-F7).
687
688Video expansion can be toggled through this feature. This controls
689whether the display is expanded to fill the entire LCD screen when a
690mode with less than full resolution is used. Note that the current
691video expansion status cannot be determined through this feature.
692
693Note that on many models (particularly those using Radeon graphics
694chips) the X driver configures the video card in a way which prevents
695Fn-F7 from working. This also disables the video output switching
696features of this driver, as it uses the same ACPI methods as
697Fn-F7. Video switching on the console should still work.
698
699UPDATE: refer to https://bugs.freedesktop.org/show_bug.cgi?id=2000
700
701
702ThinkLight control
703------------------
704
705procfs: /proc/acpi/ibm/light
706
707sysfs attributes: as per LED class, for the "tpacpi::thinklight" LED
708
709procfs notes
710^^^^^^^^^^^^
711
712The ThinkLight status can be read and set through the procfs interface.  A
713few models which do not make the status available will show the ThinkLight
714status as "unknown". The available commands are::
715
716	echo on  > /proc/acpi/ibm/light
717	echo off > /proc/acpi/ibm/light
718
719sysfs notes
720^^^^^^^^^^^
721
722The ThinkLight sysfs interface is documented by the LED class
723documentation, in Documentation/leds/leds-class.rst.  The ThinkLight LED name
724is "tpacpi::thinklight".
725
726Due to limitations in the sysfs LED class, if the status of the ThinkLight
727cannot be read or if it is unknown, thinkpad-acpi will report it as "off".
728It is impossible to know if the status returned through sysfs is valid.
729
730
731CMOS/UCMS control
732-----------------
733
734procfs: /proc/acpi/ibm/cmos
735
736sysfs device attribute: cmos_command
737
738This feature is mostly used internally by the ACPI firmware to keep the legacy
739CMOS NVRAM bits in sync with the current machine state, and to record this
740state so that the ThinkPad will retain such settings across reboots.
741
742Some of these commands actually perform actions in some ThinkPad models, but
743this is expected to disappear more and more in newer models.  As an example, in
744a T43 and in a X40, commands 12 and 13 still control the ThinkLight state for
745real, but commands 0 to 2 don't control the mixer anymore (they have been
746phased out) and just update the NVRAM.
747
748The range of valid cmos command numbers is 0 to 21, but not all have an
749effect and the behavior varies from model to model.  Here is the behavior
750on the X40 (tpb is the ThinkPad Buttons utility):
751
752	- 0 - Related to "Volume down" key press
753	- 1 - Related to "Volume up" key press
754	- 2 - Related to "Mute on" key press
755	- 3 - Related to "Access IBM" key press
756	- 4 - Related to "LCD brightness up" key press
757	- 5 - Related to "LCD brightness down" key press
758	- 11 - Related to "toggle screen expansion" key press/function
759	- 12 - Related to "ThinkLight on"
760	- 13 - Related to "ThinkLight off"
761	- 14 - Related to "ThinkLight" key press (toggle ThinkLight)
762
763The cmos command interface is prone to firmware split-brain problems, as
764in newer ThinkPads it is just a compatibility layer.  Do not use it, it is
765exported just as a debug tool.
766
767
768LED control
769-----------
770
771procfs: /proc/acpi/ibm/led
772sysfs attributes: as per LED class, see below for names
773
774Some of the LED indicators can be controlled through this feature.  On
775some older ThinkPad models, it is possible to query the status of the
776LED indicators as well.  Newer ThinkPads cannot query the real status
777of the LED indicators.
778
779Because misuse of the LEDs could induce an unaware user to perform
780dangerous actions (like undocking or ejecting a bay device while the
781buses are still active), or mask an important alarm (such as a nearly
782empty battery, or a broken battery), access to most LEDs is
783restricted.
784
785Unrestricted access to all LEDs requires that thinkpad-acpi be
786compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
787Distributions must never enable this option.  Individual users that
788are aware of the consequences are welcome to enabling it.
789
790Audio mute and microphone mute LEDs are supported, but currently not
791visible to userspace. They are used by the snd-hda-intel audio driver.
792
793procfs notes
794^^^^^^^^^^^^
795
796The available commands are::
797
798	echo '<LED number> on' >/proc/acpi/ibm/led
799	echo '<LED number> off' >/proc/acpi/ibm/led
800	echo '<LED number> blink' >/proc/acpi/ibm/led
801
802The <LED number> range is 0 to 15. The set of LEDs that can be
803controlled varies from model to model. Here is the common ThinkPad
804mapping:
805
806	- 0 - power
807	- 1 - battery (orange)
808	- 2 - battery (green)
809	- 3 - UltraBase/dock
810	- 4 - UltraBay
811	- 5 - UltraBase battery slot
812	- 6 - (unknown)
813	- 7 - standby
814	- 8 - dock status 1
815	- 9 - dock status 2
816	- 10, 11 - (unknown)
817	- 12 - thinkvantage
818	- 13, 14, 15 - (unknown)
819
820All of the above can be turned on and off and can be made to blink.
821
822sysfs notes
823^^^^^^^^^^^
824
825The ThinkPad LED sysfs interface is described in detail by the LED class
826documentation, in Documentation/leds/leds-class.rst.
827
828The LEDs are named (in LED ID order, from 0 to 12):
829"tpacpi::power", "tpacpi:orange:batt", "tpacpi:green:batt",
830"tpacpi::dock_active", "tpacpi::bay_active", "tpacpi::dock_batt",
831"tpacpi::unknown_led", "tpacpi::standby", "tpacpi::dock_status1",
832"tpacpi::dock_status2", "tpacpi::unknown_led2", "tpacpi::unknown_led3",
833"tpacpi::thinkvantage".
834
835Due to limitations in the sysfs LED class, if the status of the LED
836indicators cannot be read due to an error, thinkpad-acpi will report it as
837a brightness of zero (same as LED off).
838
839If the thinkpad firmware doesn't support reading the current status,
840trying to read the current LED brightness will just return whatever
841brightness was last written to that attribute.
842
843These LEDs can blink using hardware acceleration.  To request that a
844ThinkPad indicator LED should blink in hardware accelerated mode, use the
845"timer" trigger, and leave the delay_on and delay_off parameters set to
846zero (to request hardware acceleration autodetection).
847
848LEDs that are known not to exist in a given ThinkPad model are not
849made available through the sysfs interface.  If you have a dock and you
850notice there are LEDs listed for your ThinkPad that do not exist (and
851are not in the dock), or if you notice that there are missing LEDs,
852a report to ibm-acpi-devel@lists.sourceforge.net is appreciated.
853
854
855ACPI sounds -- /proc/acpi/ibm/beep
856----------------------------------
857
858The BEEP method is used internally by the ACPI firmware to provide
859audible alerts in various situations. This feature allows the same
860sounds to be triggered manually.
861
862The commands are non-negative integer numbers::
863
864	echo <number> >/proc/acpi/ibm/beep
865
866The valid <number> range is 0 to 17. Not all numbers trigger sounds
867and the sounds vary from model to model. Here is the behavior on the
868X40:
869
870	- 0 - stop a sound in progress (but use 17 to stop 16)
871	- 2 - two beeps, pause, third beep ("low battery")
872	- 3 - single beep
873	- 4 - high, followed by low-pitched beep ("unable")
874	- 5 - single beep
875	- 6 - very high, followed by high-pitched beep ("AC/DC")
876	- 7 - high-pitched beep
877	- 9 - three short beeps
878	- 10 - very long beep
879	- 12 - low-pitched beep
880	- 15 - three high-pitched beeps repeating constantly, stop with 0
881	- 16 - one medium-pitched beep repeating constantly, stop with 17
882	- 17 - stop 16
883
884
885Temperature sensors
886-------------------
887
888procfs: /proc/acpi/ibm/thermal
889
890sysfs device attributes: (hwmon "thinkpad") temp*_input
891
892Most ThinkPads include six or more separate temperature sensors but only
893expose the CPU temperature through the standard ACPI methods.  This
894feature shows readings from up to eight different sensors on older
895ThinkPads, and up to sixteen different sensors on newer ThinkPads.
896
897For example, on the X40, a typical output may be:
898
899temperatures:
900	42 42 45 41 36 -128 33 -128
901
902On the T43/p, a typical output may be:
903
904temperatures:
905	48 48 36 52 38 -128 31 -128 48 52 48 -128 -128 -128 -128 -128
906
907The mapping of thermal sensors to physical locations varies depending on
908system-board model (and thus, on ThinkPad model).
909
910https://thinkwiki.org/wiki/Thermal_Sensors is a public wiki page that
911tries to track down these locations for various models.
912
913Most (newer?) models seem to follow this pattern:
914
915- 1:  CPU
916- 2:  (depends on model)
917- 3:  (depends on model)
918- 4:  GPU
919- 5:  Main battery: main sensor
920- 6:  Bay battery: main sensor
921- 7:  Main battery: secondary sensor
922- 8:  Bay battery: secondary sensor
923- 9-15: (depends on model)
924
925For the R51 (source: Thomas Gruber):
926
927- 2:  Mini-PCI
928- 3:  Internal HDD
929
930For the T43, T43/p (source: Shmidoax/Thinkwiki.org)
931https://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_T43.2C_T43p
932
933- 2:  System board, left side (near PCMCIA slot), reported as HDAPS temp
934- 3:  PCMCIA slot
935- 9:  MCH (northbridge) to DRAM Bus
936- 10: Clock-generator, mini-pci card and ICH (southbridge), under Mini-PCI
937      card, under touchpad
938- 11: Power regulator, underside of system board, below F2 key
939
940The A31 has a very atypical layout for the thermal sensors
941(source: Milos Popovic, https://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_A31)
942
943- 1:  CPU
944- 2:  Main Battery: main sensor
945- 3:  Power Converter
946- 4:  Bay Battery: main sensor
947- 5:  MCH (northbridge)
948- 6:  PCMCIA/ambient
949- 7:  Main Battery: secondary sensor
950- 8:  Bay Battery: secondary sensor
951
952
953Procfs notes
954^^^^^^^^^^^^
955
956	Readings from sensors that are not available return -128.
957	No commands can be written to this file.
958
959Sysfs notes
960^^^^^^^^^^^
961
962	Sensors that are not available return the ENXIO error.  This
963	status may change at runtime, as there are hotplug thermal
964	sensors, like those inside the batteries and docks.
965
966	thinkpad-acpi thermal sensors are reported through the hwmon
967	subsystem, and follow all of the hwmon guidelines at
968	Documentation/hwmon.
969
970EXPERIMENTAL: Embedded controller register dump
971-----------------------------------------------
972
973This feature is not included in the thinkpad driver anymore.
974Instead the EC can be accessed through /sys/kernel/debug/ec with
975a userspace tool which can be found here:
976ftp://ftp.suse.com/pub/people/trenn/sources/ec
977
978Use it to determine the register holding the fan
979speed on some models. To do that, do the following:
980
981	- make sure the battery is fully charged
982	- make sure the fan is running
983	- use above mentioned tool to read out the EC
984
985Often fan and temperature values vary between
986readings. Since temperatures don't change vary fast, you can take
987several quick dumps to eliminate them.
988
989You can use a similar method to figure out the meaning of other
990embedded controller registers - e.g. make sure nothing else changes
991except the charging or discharging battery to determine which
992registers contain the current battery capacity, etc. If you experiment
993with this, do send me your results (including some complete dumps with
994a description of the conditions when they were taken.)
995
996
997LCD brightness control
998----------------------
999
1000procfs: /proc/acpi/ibm/brightness
1001
1002sysfs backlight device "thinkpad_screen"
1003
1004This feature allows software control of the LCD brightness on ThinkPad
1005models which don't have a hardware brightness slider.
1006
1007It has some limitations: the LCD backlight cannot be actually turned
1008on or off by this interface, it just controls the backlight brightness
1009level.
1010
1011On IBM (and some of the earlier Lenovo) ThinkPads, the backlight control
1012has eight brightness levels, ranging from 0 to 7.  Some of the levels
1013may not be distinct.  Later Lenovo models that implement the ACPI
1014display backlight brightness control methods have 16 levels, ranging
1015from 0 to 15.
1016
1017For IBM ThinkPads, there are two interfaces to the firmware for direct
1018brightness control, EC and UCMS (or CMOS).  To select which one should be
1019used, use the brightness_mode module parameter: brightness_mode=1 selects
1020EC mode, brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
1021mode with NVRAM backing (so that brightness changes are remembered across
1022shutdown/reboot).
1023
1024The driver tries to select which interface to use from a table of
1025defaults for each ThinkPad model.  If it makes a wrong choice, please
1026report this as a bug, so that we can fix it.
1027
1028Lenovo ThinkPads only support brightness_mode=2 (UCMS).
1029
1030When display backlight brightness controls are available through the
1031standard ACPI interface, it is best to use it instead of this direct
1032ThinkPad-specific interface.  The driver will disable its native
1033backlight brightness control interface if it detects that the standard
1034ACPI interface is available in the ThinkPad.
1035
1036If you want to use the thinkpad-acpi backlight brightness control
1037instead of the generic ACPI video backlight brightness control for some
1038reason, you should use the acpi_backlight=vendor kernel parameter.
1039
1040The brightness_enable module parameter can be used to control whether
1041the LCD brightness control feature will be enabled when available.
1042brightness_enable=0 forces it to be disabled.  brightness_enable=1
1043forces it to be enabled when available, even if the standard ACPI
1044interface is also available.
1045
1046Procfs notes
1047^^^^^^^^^^^^
1048
1049The available commands are::
1050
1051	echo up   >/proc/acpi/ibm/brightness
1052	echo down >/proc/acpi/ibm/brightness
1053	echo 'level <level>' >/proc/acpi/ibm/brightness
1054
1055Sysfs notes
1056^^^^^^^^^^^
1057
1058The interface is implemented through the backlight sysfs class, which is
1059poorly documented at this time.
1060
1061Locate the thinkpad_screen device under /sys/class/backlight, and inside
1062it there will be the following attributes:
1063
1064	max_brightness:
1065		Reads the maximum brightness the hardware can be set to.
1066		The minimum is always zero.
1067
1068	actual_brightness:
1069		Reads what brightness the screen is set to at this instant.
1070
1071	brightness:
1072		Writes request the driver to change brightness to the
1073		given value.  Reads will tell you what brightness the
1074		driver is trying to set the display to when "power" is set
1075		to zero and the display has not been dimmed by a kernel
1076		power management event.
1077
1078	power:
1079		power management mode, where 0 is "display on", and 1 to 3
1080		will dim the display backlight to brightness level 0
1081		because thinkpad-acpi cannot really turn the backlight
1082		off.  Kernel power management events can temporarily
1083		increase the current power management level, i.e. they can
1084		dim the display.
1085
1086
1087WARNING:
1088
1089    Whatever you do, do NOT ever call thinkpad-acpi backlight-level change
1090    interface and the ACPI-based backlight level change interface
1091    (available on newer BIOSes, and driven by the Linux ACPI video driver)
1092    at the same time.  The two will interact in bad ways, do funny things,
1093    and maybe reduce the life of the backlight lamps by needlessly kicking
1094    its level up and down at every change.
1095
1096
1097Volume control (Console Audio control)
1098--------------------------------------
1099
1100procfs: /proc/acpi/ibm/volume
1101
1102ALSA: "ThinkPad Console Audio Control", default ID: "ThinkPadEC"
1103
1104NOTE: by default, the volume control interface operates in read-only
1105mode, as it is supposed to be used for on-screen-display purposes.
1106The read/write mode can be enabled through the use of the
1107"volume_control=1" module parameter.
1108
1109NOTE: distros are urged to not enable volume_control by default, this
1110should be done by the local admin only.  The ThinkPad UI is for the
1111console audio control to be done through the volume keys only, and for
1112the desktop environment to just provide on-screen-display feedback.
1113Software volume control should be done only in the main AC97/HDA
1114mixer.
1115
1116
1117About the ThinkPad Console Audio control
1118^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1119
1120ThinkPads have a built-in amplifier and muting circuit that drives the
1121console headphone and speakers.  This circuit is after the main AC97
1122or HDA mixer in the audio path, and under exclusive control of the
1123firmware.
1124
1125ThinkPads have three special hotkeys to interact with the console
1126audio control: volume up, volume down and mute.
1127
1128It is worth noting that the normal way the mute function works (on
1129ThinkPads that do not have a "mute LED") is:
1130
11311. Press mute to mute.  It will *always* mute, you can press it as
1132   many times as you want, and the sound will remain mute.
1133
11342. Press either volume key to unmute the ThinkPad (it will _not_
1135   change the volume, it will just unmute).
1136
1137This is a very superior design when compared to the cheap software-only
1138mute-toggle solution found on normal consumer laptops:  you can be
1139absolutely sure the ThinkPad will not make noise if you press the mute
1140button, no matter the previous state.
1141
1142The IBM ThinkPads, and the earlier Lenovo ThinkPads have variable-gain
1143amplifiers driving the speakers and headphone output, and the firmware
1144also handles volume control for the headphone and speakers on these
1145ThinkPads without any help from the operating system (this volume
1146control stage exists after the main AC97 or HDA mixer in the audio
1147path).
1148
1149The newer Lenovo models only have firmware mute control, and depend on
1150the main HDA mixer to do volume control (which is done by the operating
1151system).  In this case, the volume keys are filtered out for unmute
1152key press (there are some firmware bugs in this area) and delivered as
1153normal key presses to the operating system (thinkpad-acpi is not
1154involved).
1155
1156
1157The ThinkPad-ACPI volume control
1158^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1159
1160The preferred way to interact with the Console Audio control is the
1161ALSA interface.
1162
1163The legacy procfs interface allows one to read the current state,
1164and if volume control is enabled, accepts the following commands::
1165
1166	echo up   >/proc/acpi/ibm/volume
1167	echo down >/proc/acpi/ibm/volume
1168	echo mute >/proc/acpi/ibm/volume
1169	echo unmute >/proc/acpi/ibm/volume
1170	echo 'level <level>' >/proc/acpi/ibm/volume
1171
1172The <level> number range is 0 to 14 although not all of them may be
1173distinct. To unmute the volume after the mute command, use either the
1174up or down command (the level command will not unmute the volume), or
1175the unmute command.
1176
1177You can use the volume_capabilities parameter to tell the driver
1178whether your thinkpad has volume control or mute-only control:
1179volume_capabilities=1 for mixers with mute and volume control,
1180volume_capabilities=2 for mixers with only mute control.
1181
1182If the driver misdetects the capabilities for your ThinkPad model,
1183please report this to ibm-acpi-devel@lists.sourceforge.net, so that we
1184can update the driver.
1185
1186There are two strategies for volume control.  To select which one
1187should be used, use the volume_mode module parameter: volume_mode=1
1188selects EC mode, and volume_mode=3 selects EC mode with NVRAM backing
1189(so that volume/mute changes are remembered across shutdown/reboot).
1190
1191The driver will operate in volume_mode=3 by default. If that does not
1192work well on your ThinkPad model, please report this to
1193ibm-acpi-devel@lists.sourceforge.net.
1194
1195The driver supports the standard ALSA module parameters.  If the ALSA
1196mixer is disabled, the driver will disable all volume functionality.
1197
1198
1199Fan control and monitoring: fan speed, fan enable/disable
1200---------------------------------------------------------
1201
1202procfs: /proc/acpi/ibm/fan
1203
1204sysfs device attributes: (hwmon "thinkpad") fan1_input, pwm1, pwm1_enable, fan2_input
1205
1206sysfs hwmon driver attributes: fan_watchdog
1207
1208NOTE NOTE NOTE:
1209   fan control operations are disabled by default for
1210   safety reasons.  To enable them, the module parameter "fan_control=1"
1211   must be given to thinkpad-acpi.
1212
1213This feature attempts to show the current fan speed, control mode and
1214other fan data that might be available.  The speed is read directly
1215from the hardware registers of the embedded controller.  This is known
1216to work on later R, T, X and Z series ThinkPads but may show a bogus
1217value on other models.
1218
1219Some Lenovo ThinkPads support a secondary fan.  This fan cannot be
1220controlled separately, it shares the main fan control.
1221
1222Fan levels
1223^^^^^^^^^^
1224
1225Most ThinkPad fans work in "levels" at the firmware interface.  Level 0
1226stops the fan.  The higher the level, the higher the fan speed, although
1227adjacent levels often map to the same fan speed.  7 is the highest
1228level, where the fan reaches the maximum recommended speed.
1229
1230Level "auto" means the EC changes the fan level according to some
1231internal algorithm, usually based on readings from the thermal sensors.
1232
1233There is also a "full-speed" level, also known as "disengaged" level.
1234In this level, the EC disables the speed-locked closed-loop fan control,
1235and drives the fan as fast as it can go, which might exceed hardware
1236limits, so use this level with caution.
1237
1238The fan usually ramps up or down slowly from one speed to another, and
1239it is normal for the EC to take several seconds to react to fan
1240commands.  The full-speed level may take up to two minutes to ramp up to
1241maximum speed, and in some ThinkPads, the tachometer readings go stale
1242while the EC is transitioning to the full-speed level.
1243
1244WARNING WARNING WARNING: do not leave the fan disabled unless you are
1245monitoring all of the temperature sensor readings and you are ready to
1246enable it if necessary to avoid overheating.
1247
1248An enabled fan in level "auto" may stop spinning if the EC decides the
1249ThinkPad is cool enough and doesn't need the extra airflow.  This is
1250normal, and the EC will spin the fan up if the various thermal readings
1251rise too much.
1252
1253On the X40, this seems to depend on the CPU and HDD temperatures.
1254Specifically, the fan is turned on when either the CPU temperature
1255climbs to 56 degrees or the HDD temperature climbs to 46 degrees.  The
1256fan is turned off when the CPU temperature drops to 49 degrees and the
1257HDD temperature drops to 41 degrees.  These thresholds cannot
1258currently be controlled.
1259
1260The ThinkPad's ACPI DSDT code will reprogram the fan on its own when
1261certain conditions are met.  It will override any fan programming done
1262through thinkpad-acpi.
1263
1264The thinkpad-acpi kernel driver can be programmed to revert the fan
1265level to a safe setting if userspace does not issue one of the procfs
1266fan commands: "enable", "disable", "level" or "watchdog", or if there
1267are no writes to pwm1_enable (or to pwm1 *if and only if* pwm1_enable is
1268set to 1, manual mode) within a configurable amount of time of up to
1269120 seconds.  This functionality is called fan safety watchdog.
1270
1271Note that the watchdog timer stops after it enables the fan.  It will be
1272rearmed again automatically (using the same interval) when one of the
1273above mentioned fan commands is received.  The fan watchdog is,
1274therefore, not suitable to protect against fan mode changes made through
1275means other than the "enable", "disable", and "level" procfs fan
1276commands, or the hwmon fan control sysfs interface.
1277
1278Procfs notes
1279^^^^^^^^^^^^
1280
1281The fan may be enabled or disabled with the following commands::
1282
1283	echo enable  >/proc/acpi/ibm/fan
1284	echo disable >/proc/acpi/ibm/fan
1285
1286Placing a fan on level 0 is the same as disabling it.  Enabling a fan
1287will try to place it in a safe level if it is too slow or disabled.
1288
1289The fan level can be controlled with the command::
1290
1291	echo 'level <level>' > /proc/acpi/ibm/fan
1292
1293Where <level> is an integer from 0 to 7, or one of the words "auto" or
1294"full-speed" (without the quotes).  Not all ThinkPads support the "auto"
1295and "full-speed" levels.  The driver accepts "disengaged" as an alias for
1296"full-speed", and reports it as "disengaged" for backwards
1297compatibility.
1298
1299On the X31 and X40 (and ONLY on those models), the fan speed can be
1300controlled to a certain degree.  Once the fan is running, it can be
1301forced to run faster or slower with the following command::
1302
1303	echo 'speed <speed>' > /proc/acpi/ibm/fan
1304
1305The sustainable range of fan speeds on the X40 appears to be from about
13063700 to about 7350. Values outside this range either do not have any
1307effect or the fan speed eventually settles somewhere in that range.  The
1308fan cannot be stopped or started with this command.  This functionality
1309is incomplete, and not available through the sysfs interface.
1310
1311To program the safety watchdog, use the "watchdog" command::
1312
1313	echo 'watchdog <interval in seconds>' > /proc/acpi/ibm/fan
1314
1315If you want to disable the watchdog, use 0 as the interval.
1316
1317Sysfs notes
1318^^^^^^^^^^^
1319
1320The sysfs interface follows the hwmon subsystem guidelines for the most
1321part, and the exception is the fan safety watchdog.
1322
1323Writes to any of the sysfs attributes may return the EINVAL error if
1324that operation is not supported in a given ThinkPad or if the parameter
1325is out-of-bounds, and EPERM if it is forbidden.  They may also return
1326EINTR (interrupted system call), and EIO (I/O error while trying to talk
1327to the firmware).
1328
1329Features not yet implemented by the driver return ENOSYS.
1330
1331hwmon device attribute pwm1_enable:
1332	- 0: PWM offline (fan is set to full-speed mode)
1333	- 1: Manual PWM control (use pwm1 to set fan level)
1334	- 2: Hardware PWM control (EC "auto" mode)
1335	- 3: reserved (Software PWM control, not implemented yet)
1336
1337	Modes 0 and 2 are not supported by all ThinkPads, and the
1338	driver is not always able to detect this.  If it does know a
1339	mode is unsupported, it will return -EINVAL.
1340
1341hwmon device attribute pwm1:
1342	Fan level, scaled from the firmware values of 0-7 to the hwmon
1343	scale of 0-255.  0 means fan stopped, 255 means highest normal
1344	speed (level 7).
1345
1346	This attribute only commands the fan if pmw1_enable is set to 1
1347	(manual PWM control).
1348
1349hwmon device attribute fan1_input:
1350	Fan tachometer reading, in RPM.  May go stale on certain
1351	ThinkPads while the EC transitions the PWM to offline mode,
1352	which can take up to two minutes.  May return rubbish on older
1353	ThinkPads.
1354
1355hwmon device attribute fan2_input:
1356	Fan tachometer reading, in RPM, for the secondary fan.
1357	Available only on some ThinkPads.  If the secondary fan is
1358	not installed, will always read 0.
1359
1360hwmon driver attribute fan_watchdog:
1361	Fan safety watchdog timer interval, in seconds.  Minimum is
1362	1 second, maximum is 120 seconds.  0 disables the watchdog.
1363
1364To stop the fan: set pwm1 to zero, and pwm1_enable to 1.
1365
1366To start the fan in a safe mode: set pwm1_enable to 2.  If that fails
1367with EINVAL, try to set pwm1_enable to 1 and pwm1 to at least 128 (255
1368would be the safest choice, though).
1369
1370
1371WAN
1372---
1373
1374procfs: /proc/acpi/ibm/wan
1375
1376sysfs device attribute: wwan_enable (deprecated)
1377
1378sysfs rfkill class: switch "tpacpi_wwan_sw"
1379
1380This feature shows the presence and current state of the built-in
1381Wireless WAN device.
1382
1383If the ThinkPad supports it, the WWAN state is stored in NVRAM,
1384so it is kept across reboots and power-off.
1385
1386It was tested on a Lenovo ThinkPad X60. It should probably work on other
1387ThinkPad models which come with this module installed.
1388
1389Procfs notes
1390^^^^^^^^^^^^
1391
1392If the W-WAN card is installed, the following commands can be used::
1393
1394	echo enable > /proc/acpi/ibm/wan
1395	echo disable > /proc/acpi/ibm/wan
1396
1397Sysfs notes
1398^^^^^^^^^^^
1399
1400	If the W-WAN card is installed, it can be enabled /
1401	disabled through the "wwan_enable" thinkpad-acpi device
1402	attribute, and its current status can also be queried.
1403
1404	enable:
1405		- 0: disables WWAN card / WWAN card is disabled
1406		- 1: enables WWAN card / WWAN card is enabled.
1407
1408	Note: this interface has been superseded by the	generic rfkill
1409	class.  It has been deprecated, and it will be removed in year
1410	2010.
1411
1412	rfkill controller switch "tpacpi_wwan_sw": refer to
1413	Documentation/driver-api/rfkill.rst for details.
1414
1415
1416LCD Shadow control
1417------------------
1418
1419procfs: /proc/acpi/ibm/lcdshadow
1420
1421Some newer T480s and T490s ThinkPads provide a feature called
1422PrivacyGuard. By turning this feature on, the usable vertical and
1423horizontal viewing angles of the LCD can be limited (as if some privacy
1424screen was applied manually in front of the display).
1425
1426procfs notes
1427^^^^^^^^^^^^
1428
1429The available commands are::
1430
1431	echo '0' >/proc/acpi/ibm/lcdshadow
1432	echo '1' >/proc/acpi/ibm/lcdshadow
1433
1434The first command ensures the best viewing angle and the latter one turns
1435on the feature, restricting the viewing angles.
1436
1437
1438DYTC Lapmode sensor
1439-------------------
1440
1441sysfs: dytc_lapmode
1442
1443Newer thinkpads and mobile workstations have the ability to determine if
1444the device is in deskmode or lapmode. This feature is used by user space
1445to decide if WWAN transmission can be increased to maximum power and is
1446also useful for understanding the different thermal modes available as
1447they differ between desk and lap mode.
1448
1449The property is read-only. If the platform doesn't have support the sysfs
1450class is not created.
1451
1452EXPERIMENTAL: UWB
1453-----------------
1454
1455This feature is considered EXPERIMENTAL because it has not been extensively
1456tested and validated in various ThinkPad models yet.  The feature may not
1457work as expected. USE WITH CAUTION! To use this feature, you need to supply
1458the experimental=1 parameter when loading the module.
1459
1460sysfs rfkill class: switch "tpacpi_uwb_sw"
1461
1462This feature exports an rfkill controller for the UWB device, if one is
1463present and enabled in the BIOS.
1464
1465Sysfs notes
1466^^^^^^^^^^^
1467
1468	rfkill controller switch "tpacpi_uwb_sw": refer to
1469	Documentation/driver-api/rfkill.rst for details.
1470
1471
1472Setting keyboard language
1473-------------------------
1474
1475sysfs: keyboard_lang
1476
1477This feature is used to set keyboard language to ECFW using ASL interface.
1478Fewer thinkpads models like T580 , T590 , T15 Gen 1 etc.. has "=", "(',
1479")" numeric keys, which are not displaying correctly, when keyboard language
1480is other than "english". This is because the default keyboard language in ECFW
1481is set as "english". Hence using this sysfs, user can set the correct keyboard
1482language to ECFW and then these key's will work correctly.
1483
1484Example of command to set keyboard language is mentioned below::
1485
1486        echo jp > /sys/devices/platform/thinkpad_acpi/keyboard_lang
1487
1488Text corresponding to keyboard layout to be set in sysfs are: be(Belgian),
1489cz(Czech), da(Danish), de(German), en(English), es(Spain), et(Estonian),
1490fr(French), fr-ch(French(Switzerland)), hu(Hungarian), it(Italy), jp (Japan),
1491nl(Dutch), nn(Norway), pl(Polish), pt(portugese), sl(Slovenian), sv(Sweden),
1492tr(Turkey)
1493
1494WWAN Antenna type
1495-----------------
1496
1497sysfs: wwan_antenna_type
1498
1499On some newer Thinkpads we need to set SAR value based on the antenna
1500type. This interface will be used by userspace to get the antenna type
1501and set the corresponding SAR value, as is required for FCC certification.
1502
1503The available commands are::
1504
1505        cat /sys/devices/platform/thinkpad_acpi/wwan_antenna_type
1506
1507Currently 2 antenna types are supported as mentioned below:
1508- type a
1509- type b
1510
1511The property is read-only. If the platform doesn't have support the sysfs
1512class is not created.
1513
1514Adaptive keyboard
1515-----------------
1516
1517sysfs device attribute: adaptive_kbd_mode
1518
1519This sysfs attribute controls the keyboard "face" that will be shown on the
1520Lenovo X1 Carbon 2nd gen (2014)'s adaptive keyboard. The value can be read
1521and set.
1522
1523- 0 = Home mode
1524- 1 = Web-browser mode
1525- 2 = Web-conference mode
1526- 3 = Function mode
1527- 4 = Layflat mode
1528
1529For more details about which buttons will appear depending on the mode, please
1530review the laptop's user guide:
1531https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles_pdf/x1carbon_2_ug_en.pdf
1532
1533Battery charge control
1534----------------------
1535
1536sysfs attributes:
1537/sys/class/power_supply/BAT*/charge_control_{start,end}_threshold
1538
1539These two attributes are created for those batteries that are supported by the
1540driver. They enable the user to control the battery charge thresholds of the
1541given battery. Both values may be read and set. `charge_control_start_threshold`
1542accepts an integer between 0 and 99 (inclusive); this value represents a battery
1543percentage level, below which charging will begin. `charge_control_end_threshold`
1544accepts an integer between 1 and 100 (inclusive); this value represents a battery
1545percentage level, above which charging will stop.
1546
1547The exact semantics of the attributes may be found in
1548Documentation/ABI/testing/sysfs-class-power.
1549
1550Multiple Commands, Module Parameters
1551------------------------------------
1552
1553Multiple commands can be written to the proc files in one shot by
1554separating them with commas, for example::
1555
1556	echo enable,0xffff > /proc/acpi/ibm/hotkey
1557	echo lcd_disable,crt_enable > /proc/acpi/ibm/video
1558
1559Commands can also be specified when loading the thinkpad-acpi module,
1560for example::
1561
1562	modprobe thinkpad_acpi hotkey=enable,0xffff video=auto_disable
1563
1564
1565Enabling debugging output
1566-------------------------
1567
1568The module takes a debug parameter which can be used to selectively
1569enable various classes of debugging output, for example::
1570
1571	 modprobe thinkpad_acpi debug=0xffff
1572
1573will enable all debugging output classes.  It takes a bitmask, so
1574to enable more than one output class, just add their values.
1575
1576	=============		======================================
1577	Debug bitmask		Description
1578	=============		======================================
1579	0x8000			Disclose PID of userspace programs
1580				accessing some functions of the driver
1581	0x0001			Initialization and probing
1582	0x0002			Removal
1583	0x0004			RF Transmitter control (RFKILL)
1584				(bluetooth, WWAN, UWB...)
1585	0x0008			HKEY event interface, hotkeys
1586	0x0010			Fan control
1587	0x0020			Backlight brightness
1588	0x0040			Audio mixer/volume control
1589	=============		======================================
1590
1591There is also a kernel build option to enable more debugging
1592information, which may be necessary to debug driver problems.
1593
1594The level of debugging information output by the driver can be changed
1595at runtime through sysfs, using the driver attribute debug_level.  The
1596attribute takes the same bitmask as the debug module parameter above.
1597
1598
1599Force loading of module
1600-----------------------
1601
1602If thinkpad-acpi refuses to detect your ThinkPad, you can try to specify
1603the module parameter force_load=1.  Regardless of whether this works or
1604not, please contact ibm-acpi-devel@lists.sourceforge.net with a report.
1605
1606
1607Sysfs interface changelog
1608^^^^^^^^^^^^^^^^^^^^^^^^^
1609
1610=========	===============================================================
16110x000100:	Initial sysfs support, as a single platform driver and
1612		device.
16130x000200:	Hot key support for 32 hot keys, and radio slider switch
1614		support.
16150x010000:	Hot keys are now handled by default over the input
1616		layer, the radio switch generates input event EV_RADIO,
1617		and the driver enables hot key handling by default in
1618		the firmware.
1619
16200x020000:	ABI fix: added a separate hwmon platform device and
1621		driver, which must be located by name (thinkpad)
1622		and the hwmon class for libsensors4 (lm-sensors 3)
1623		compatibility.  Moved all hwmon attributes to this
1624		new platform device.
1625
16260x020100:	Marker for thinkpad-acpi with hot key NVRAM polling
1627		support.  If you must, use it to know you should not
1628		start a userspace NVRAM poller (allows to detect when
1629		NVRAM is compiled out by the user because it is
1630		unneeded/undesired in the first place).
16310x020101:	Marker for thinkpad-acpi with hot key NVRAM polling
1632		and proper hotkey_mask semantics (version 8 of the
1633		NVRAM polling patch).  Some development snapshots of
1634		0.18 had an earlier version that did strange things
1635		to hotkey_mask.
1636
16370x020200:	Add poll()/select() support to the following attributes:
1638		hotkey_radio_sw, wakeup_hotunplug_complete, wakeup_reason
1639
16400x020300:	hotkey enable/disable support removed, attributes
1641		hotkey_bios_enabled and hotkey_enable deprecated and
1642		marked for removal.
1643
16440x020400:	Marker for 16 LEDs support.  Also, LEDs that are known
1645		to not exist in a given model are not registered with
1646		the LED sysfs class anymore.
1647
16480x020500:	Updated hotkey driver, hotkey_mask is always available
1649		and it is always able to disable hot keys.  Very old
1650		thinkpads are properly supported.  hotkey_bios_mask
1651		is deprecated and marked for removal.
1652
16530x020600:	Marker for backlight change event support.
1654
16550x020700:	Support for mute-only mixers.
1656		Volume control in read-only mode by default.
1657		Marker for ALSA mixer support.
1658
16590x030000:	Thermal and fan sysfs attributes were moved to the hwmon
1660		device instead of being attached to the backing platform
1661		device.
1662=========	===============================================================
1663