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
55A compatibility table by model and feature is maintained on the web
56site, http://ibm-acpi.sf.net/. I appreciate any success or failure
57reports, especially if they add to or correct the compatibility table.
58Please include the following information in your report:
59
60	- ThinkPad model name
61	- a copy of your ACPI tables, using the "acpidump" utility
62	- a copy of the output of dmidecode, with serial numbers
63	  and UUIDs masked off
64	- which driver features work and which don't
65	- the observed behavior of non-working features
66
67Any other comments or patches are also more than welcome.
68
69
70Installation
71------------
72
73If you are compiling this driver as included in the Linux kernel
74sources, look for the CONFIG_THINKPAD_ACPI Kconfig option.
75It is located on the menu path: "Device Drivers" -> "X86 Platform
76Specific Device Drivers" -> "ThinkPad ACPI Laptop Extras".
77
78
79Features
80--------
81
82The driver exports two different interfaces to userspace, which can be
83used to access the features it provides.  One is a legacy procfs-based
84interface, which will be removed at some time in the future.  The other
85is a new sysfs-based interface which is not complete yet.
86
87The procfs interface creates the /proc/acpi/ibm directory.  There is a
88file under that directory for each feature it supports.  The procfs
89interface is mostly frozen, and will change very little if at all: it
90will not be extended to add any new functionality in the driver, instead
91all new functionality will be implemented on the sysfs interface.
92
93The sysfs interface tries to blend in the generic Linux sysfs subsystems
94and classes as much as possible.  Since some of these subsystems are not
95yet ready or stabilized, it is expected that this interface will change,
96and any and all userspace programs must deal with it.
97
98
99Notes about the sysfs interface
100^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
101
102Unlike what was done with the procfs interface, correctness when talking
103to the sysfs interfaces will be enforced, as will correctness in the
104thinkpad-acpi's implementation of sysfs interfaces.
105
106Also, any bugs in the thinkpad-acpi sysfs driver code or in the
107thinkpad-acpi's implementation of the sysfs interfaces will be fixed for
108maximum correctness, even if that means changing an interface in
109non-compatible ways.  As these interfaces mature both in the kernel and
110in thinkpad-acpi, such changes should become quite rare.
111
112Applications interfacing to the thinkpad-acpi sysfs interfaces must
113follow all sysfs guidelines and correctly process all errors (the sysfs
114interface makes extensive use of errors).  File descriptors and open /
115close operations to the sysfs inodes must also be properly implemented.
116
117The version of thinkpad-acpi's sysfs interface is exported by the driver
118as a driver attribute (see below).
119
120Sysfs driver attributes are on the driver's sysfs attribute space,
121for 2.6.23+ this is /sys/bus/platform/drivers/thinkpad_acpi/ and
122/sys/bus/platform/drivers/thinkpad_hwmon/
123
124Sysfs device attributes are on the thinkpad_acpi device sysfs attribute
125space, for 2.6.23+ this is /sys/devices/platform/thinkpad_acpi/.
126
127Sysfs device attributes for the sensors and fan are on the
128thinkpad_hwmon device's sysfs attribute space, but you should locate it
129looking for a hwmon device with the name attribute of "thinkpad", or
130better yet, through libsensors. For 4.14+ sysfs attributes were moved to the
131hwmon device (/sys/bus/platform/devices/thinkpad_hwmon/hwmon/hwmon? or
132/sys/class/hwmon/hwmon?).
133
134Driver version
135--------------
136
137procfs: /proc/acpi/ibm/driver
138
139sysfs driver attribute: version
140
141The driver name and version. No commands can be written to this file.
142
143
144Sysfs interface version
145-----------------------
146
147sysfs driver attribute: interface_version
148
149Version of the thinkpad-acpi sysfs interface, as an unsigned long
150(output in hex format: 0xAAAABBCC), where:
151
152	AAAA
153	  - major revision
154	BB
155	  - minor revision
156	CC
157	  - bugfix revision
158
159The sysfs interface version changelog for the driver can be found at the
160end of this document.  Changes to the sysfs interface done by the kernel
161subsystems are not documented here, nor are they tracked by this
162attribute.
163
164Changes to the thinkpad-acpi sysfs interface are only considered
165non-experimental when they are submitted to Linux mainline, at which
166point the changes in this interface are documented and interface_version
167may be updated.  If you are using any thinkpad-acpi features not yet
168sent to mainline for merging, you do so on your own risk: these features
169may disappear, or be implemented in a different and incompatible way by
170the time they are merged in Linux mainline.
171
172Changes that are backwards-compatible by nature (e.g. the addition of
173attributes that do not change the way the other attributes work) do not
174always warrant an update of interface_version.  Therefore, one must
175expect that an attribute might not be there, and deal with it properly
176(an attribute not being there *is* a valid way to make it clear that a
177feature is not available in sysfs).
178
179
180Hot keys
181--------
182
183procfs: /proc/acpi/ibm/hotkey
184
185sysfs device attribute: hotkey_*
186
187In a ThinkPad, the ACPI HKEY handler is responsible for communicating
188some important events and also keyboard hot key presses to the operating
189system.  Enabling the hotkey functionality of thinkpad-acpi signals the
190firmware that such a driver is present, and modifies how the ThinkPad
191firmware will behave in many situations.
192
193The driver enables the HKEY ("hot key") event reporting automatically
194when loaded, and disables it when it is removed.
195
196The driver will report HKEY events in the following format::
197
198	ibm/hotkey HKEY 00000080 0000xxxx
199
200Some of these events refer to hot key presses, but not all of them.
201
202The driver will generate events over the input layer for hot keys and
203radio switches, and over the ACPI netlink layer for other events.  The
204input layer support accepts the standard IOCTLs to remap the keycodes
205assigned to each hot key.
206
207The hot key bit mask allows some control over which hot keys generate
208events.  If a key is "masked" (bit set to 0 in the mask), the firmware
209will handle it.  If it is "unmasked", it signals the firmware that
210thinkpad-acpi would prefer to handle it, if the firmware would be so
211kind to allow it (and it often doesn't!).
212
213Not all bits in the mask can be modified.  Not all bits that can be
214modified do anything.  Not all hot keys can be individually controlled
215by the mask.  Some models do not support the mask at all.  The behaviour
216of the mask is, therefore, highly dependent on the ThinkPad model.
217
218The driver will filter out any unmasked hotkeys, so even if the firmware
219doesn't allow disabling an specific hotkey, the driver will not report
220events for unmasked hotkeys.
221
222Note that unmasking some keys prevents their default behavior.  For
223example, if Fn+F5 is unmasked, that key will no longer enable/disable
224Bluetooth by itself in firmware.
225
226Note also that not all Fn key combinations are supported through ACPI
227depending on the ThinkPad model and firmware version.  On those
228ThinkPads, it is still possible to support some extra hotkeys by
229polling the "CMOS NVRAM" at least 10 times per second.  The driver
230attempts to enables this functionality automatically when required.
231
232procfs notes
233^^^^^^^^^^^^
234
235The following commands can be written to the /proc/acpi/ibm/hotkey file::
236
237	echo 0xffffffff > /proc/acpi/ibm/hotkey -- enable all hot keys
238	echo 0 > /proc/acpi/ibm/hotkey -- disable all possible hot keys
239	... any other 8-hex-digit mask ...
240	echo reset > /proc/acpi/ibm/hotkey -- restore the recommended mask
241
242The following commands have been deprecated and will cause the kernel
243to log a warning::
244
245	echo enable > /proc/acpi/ibm/hotkey -- does nothing
246	echo disable > /proc/acpi/ibm/hotkey -- returns an error
247
248The procfs interface does not support NVRAM polling control.  So as to
249maintain maximum bug-to-bug compatibility, it does not report any masks,
250nor does it allow one to manipulate the hot key mask when the firmware
251does not support masks at all, even if NVRAM polling is in use.
252
253sysfs notes
254^^^^^^^^^^^
255
256	hotkey_bios_enabled:
257		DEPRECATED, WILL BE REMOVED SOON.
258
259		Returns 0.
260
261	hotkey_bios_mask:
262		DEPRECATED, DON'T USE, WILL BE REMOVED IN THE FUTURE.
263
264		Returns the hot keys mask when thinkpad-acpi was loaded.
265		Upon module unload, the hot keys mask will be restored
266		to this value.   This is always 0x80c, because those are
267		the hotkeys that were supported by ancient firmware
268		without mask support.
269
270	hotkey_enable:
271		DEPRECATED, WILL BE REMOVED SOON.
272
273		0: returns -EPERM
274		1: does nothing
275
276	hotkey_mask:
277		bit mask to enable reporting (and depending on
278		the firmware, ACPI event generation) for each hot key
279		(see above).  Returns the current status of the hot keys
280		mask, and allows one to modify it.
281
282	hotkey_all_mask:
283		bit mask that should enable event reporting for all
284		supported hot keys, when echoed to hotkey_mask above.
285		Unless you know which events need to be handled
286		passively (because the firmware *will* handle them
287		anyway), do *not* use hotkey_all_mask.  Use
288		hotkey_recommended_mask, instead. You have been warned.
289
290	hotkey_recommended_mask:
291		bit mask that should enable event reporting for all
292		supported hot keys, except those which are always
293		handled by the firmware anyway.  Echo it to
294		hotkey_mask above, to use.  This is the default mask
295		used by the driver.
296
297	hotkey_source_mask:
298		bit mask that selects which hot keys will the driver
299		poll the NVRAM for.  This is auto-detected by the driver
300		based on the capabilities reported by the ACPI firmware,
301		but it can be overridden at runtime.
302
303		Hot keys whose bits are set in hotkey_source_mask are
304		polled for in NVRAM, and reported as hotkey events if
305		enabled in hotkey_mask.  Only a few hot keys are
306		available through CMOS NVRAM polling.
307
308		Warning: when in NVRAM mode, the volume up/down/mute
309		keys are synthesized according to changes in the mixer,
310		which uses a single volume up or volume down hotkey
311		press to unmute, as per the ThinkPad volume mixer user
312		interface.  When in ACPI event mode, volume up/down/mute
313		events are reported by the firmware and can behave
314		differently (and that behaviour changes with firmware
315		version -- not just with firmware models -- as well as
316		OSI(Linux) state).
317
318	hotkey_poll_freq:
319		frequency in Hz for hot key polling. It must be between
320		0 and 25 Hz.  Polling is only carried out when strictly
321		needed.
322
323		Setting hotkey_poll_freq to zero disables polling, and
324		will cause hot key presses that require NVRAM polling
325		to never be reported.
326
327		Setting hotkey_poll_freq too low may cause repeated
328		pressings of the same hot key to be misreported as a
329		single key press, or to not even be detected at all.
330		The recommended polling frequency is 10Hz.
331
332	hotkey_radio_sw:
333		If the ThinkPad has a hardware radio switch, this
334		attribute will read 0 if the switch is in the "radios
335		disabled" position, and 1 if the switch is in the
336		"radios enabled" position.
337
338		This attribute has poll()/select() support.
339
340	hotkey_tablet_mode:
341		If the ThinkPad has tablet capabilities, this attribute
342		will read 0 if the ThinkPad is in normal mode, and
343		1 if the ThinkPad is in tablet mode.
344
345		This attribute has poll()/select() support.
346
347	wakeup_reason:
348		Set to 1 if the system is waking up because the user
349		requested a bay ejection.  Set to 2 if the system is
350		waking up because the user requested the system to
351		undock.  Set to zero for normal wake-ups or wake-ups
352		due to unknown reasons.
353
354		This attribute has poll()/select() support.
355
356	wakeup_hotunplug_complete:
357		Set to 1 if the system was waken up because of an
358		undock or bay ejection request, and that request
359		was successfully completed.  At this point, it might
360		be useful to send the system back to sleep, at the
361		user's choice.  Refer to HKEY events 0x4003 and
362		0x3003, below.
363
364		This attribute has poll()/select() support.
365
366input layer notes
367^^^^^^^^^^^^^^^^^
368
369A Hot key is mapped to a single input layer EV_KEY event, possibly
370followed by an EV_MSC MSC_SCAN event that shall contain that key's scan
371code.  An EV_SYN event will always be generated to mark the end of the
372event block.
373
374Do not use the EV_MSC MSC_SCAN events to process keys.  They are to be
375used as a helper to remap keys, only.  They are particularly useful when
376remapping KEY_UNKNOWN keys.
377
378The events are available in an input device, with the following id:
379
380	==============  ==============================
381	Bus		BUS_HOST
382	vendor		0x1014 (PCI_VENDOR_ID_IBM)  or
383			0x17aa (PCI_VENDOR_ID_LENOVO)
384	product		0x5054 ("TP")
385	version		0x4101
386	==============  ==============================
387
388The version will have its LSB incremented if the keymap changes in a
389backwards-compatible way.  The MSB shall always be 0x41 for this input
390device.  If the MSB is not 0x41, do not use the device as described in
391this section, as it is either something else (e.g. another input device
392exported by a thinkpad driver, such as HDAPS) or its functionality has
393been changed in a non-backwards compatible way.
394
395Adding other event types for other functionalities shall be considered a
396backwards-compatible change for this input device.
397
398Thinkpad-acpi Hot Key event map (version 0x4101):
399
400=======	=======	==============	==============================================
401ACPI	Scan
402event	code	Key		Notes
403=======	=======	==============	==============================================
4040x1001	0x00	FN+F1		-
405
4060x1002	0x01	FN+F2		IBM: battery (rare)
407				Lenovo: Screen lock
408
4090x1003	0x02	FN+F3		Many IBM models always report
410				this hot key, even with hot keys
411				disabled or with Fn+F3 masked
412				off
413				IBM: screen lock, often turns
414				off the ThinkLight as side-effect
415				Lenovo: battery
416
4170x1004	0x03	FN+F4		Sleep button (ACPI sleep button
418				semantics, i.e. sleep-to-RAM).
419				It always generates some kind
420				of event, either the hot key
421				event or an ACPI sleep button
422				event. The firmware may
423				refuse to generate further FN+F4
424				key presses until a S3 or S4 ACPI
425				sleep cycle is performed or some
426				time passes.
427
4280x1005	0x04	FN+F5		Radio.  Enables/disables
429				the internal Bluetooth hardware
430				and W-WAN card if left in control
431				of the firmware.  Does not affect
432				the WLAN card.
433				Should be used to turn on/off all
434				radios (Bluetooth+W-WAN+WLAN),
435				really.
436
4370x1006	0x05	FN+F6		-
438
4390x1007	0x06	FN+F7		Video output cycle.
440				Do you feel lucky today?
441
4420x1008	0x07	FN+F8		IBM: toggle screen expand
443				Lenovo: configure UltraNav,
444				or toggle screen expand
445
4460x1009	0x08	FN+F9		-
447
448...	...	...		...
449
4500x100B	0x0A	FN+F11		-
451
4520x100C	0x0B	FN+F12		Sleep to disk.  You are always
453				supposed to handle it yourself,
454				either through the ACPI event,
455				or through a hotkey event.
456				The firmware may refuse to
457				generate further FN+F12 key
458				press events until a S3 or S4
459				ACPI sleep cycle is performed,
460				or some time passes.
461
4620x100D	0x0C	FN+BACKSPACE	-
4630x100E	0x0D	FN+INSERT	-
4640x100F	0x0E	FN+DELETE	-
465
4660x1010	0x0F	FN+HOME		Brightness up.  This key is
467				always handled by the firmware
468				in IBM ThinkPads, even when
469				unmasked.  Just leave it alone.
470				For Lenovo ThinkPads with a new
471				BIOS, it has to be handled either
472				by the ACPI OSI, or by userspace.
473				The driver does the right thing,
474				never mess with this.
4750x1011	0x10	FN+END		Brightness down.  See brightness
476				up for details.
477
4780x1012	0x11	FN+PGUP		ThinkLight toggle.  This key is
479				always handled by the firmware,
480				even when unmasked.
481
4820x1013	0x12	FN+PGDOWN	-
483
4840x1014	0x13	FN+SPACE	Zoom key
485
4860x1015	0x14	VOLUME UP	Internal mixer volume up. This
487				key is always handled by the
488				firmware, even when unmasked.
489				NOTE: Lenovo seems to be changing
490				this.
4910x1016	0x15	VOLUME DOWN	Internal mixer volume up. This
492				key is always handled by the
493				firmware, even when unmasked.
494				NOTE: Lenovo seems to be changing
495				this.
4960x1017	0x16	MUTE		Mute internal mixer. This
497				key is always handled by the
498				firmware, even when unmasked.
499
5000x1018	0x17	THINKPAD	ThinkPad/Access IBM/Lenovo key
501
5020x1019	0x18	unknown
503
504...	...	...
505
5060x1020	0x1F	unknown
507=======	=======	==============	==============================================
508
509The ThinkPad firmware does not allow one to differentiate when most hot
510keys are pressed or released (either that, or we don't know how to, yet).
511For these keys, the driver generates a set of events for a key press and
512immediately issues the same set of events for a key release.  It is
513unknown by the driver if the ThinkPad firmware triggered these events on
514hot key press or release, but the firmware will do it for either one, not
515both.
516
517If a key is mapped to KEY_RESERVED, it generates no input events at all.
518If a key is mapped to KEY_UNKNOWN, it generates an input event that
519includes an scan code.  If a key is mapped to anything else, it will
520generate input device EV_KEY events.
521
522In addition to the EV_KEY events, thinkpad-acpi may also issue EV_SW
523events for switches:
524
525==============	==============================================
526SW_RFKILL_ALL	T60 and later hardware rfkill rocker switch
527SW_TABLET_MODE	Tablet ThinkPads HKEY events 0x5009 and 0x500A
528==============	==============================================
529
530Non hotkey ACPI HKEY event map
531------------------------------
532
533Events that are never propagated by the driver:
534
535======		==================================================
5360x2304		System is waking up from suspend to undock
5370x2305		System is waking up from suspend to eject bay
5380x2404		System is waking up from hibernation to undock
5390x2405		System is waking up from hibernation to eject bay
5400x5001		Lid closed
5410x5002		Lid opened
5420x5009		Tablet swivel: switched to tablet mode
5430x500A		Tablet swivel: switched to normal mode
5440x5010		Brightness level changed/control event
5450x6000		KEYBOARD: Numlock key pressed
5460x6005		KEYBOARD: Fn key pressed (TO BE VERIFIED)
5470x7000		Radio Switch may have changed state
548======		==================================================
549
550
551Events that are propagated by the driver to userspace:
552
553======		=====================================================
5540x2313		ALARM: System is waking up from suspend because
555		the battery is nearly empty
5560x2413		ALARM: System is waking up from hibernation because
557		the battery is nearly empty
5580x3003		Bay ejection (see 0x2x05) complete, can sleep again
5590x3006		Bay hotplug request (hint to power up SATA link when
560		the optical drive tray is ejected)
5610x4003		Undocked (see 0x2x04), can sleep again
5620x4010		Docked into hotplug port replicator (non-ACPI dock)
5630x4011		Undocked from hotplug port replicator (non-ACPI dock)
5640x500B		Tablet pen inserted into its storage bay
5650x500C		Tablet pen removed from its storage bay
5660x6011		ALARM: battery is too hot
5670x6012		ALARM: battery is extremely hot
5680x6021		ALARM: a sensor is too hot
5690x6022		ALARM: a sensor is extremely hot
5700x6030		System thermal table changed
5710x6032		Thermal Control command set completion  (DYTC, Windows)
5720x6040		Nvidia Optimus/AC adapter related (TO BE VERIFIED)
5730x60C0		X1 Yoga 2016, Tablet mode status changed
5740x60F0		Thermal Transformation changed (GMTS, Windows)
575======		=====================================================
576
577Battery nearly empty alarms are a last resort attempt to get the
578operating system to hibernate or shutdown cleanly (0x2313), or shutdown
579cleanly (0x2413) before power is lost.  They must be acted upon, as the
580wake up caused by the firmware will have negated most safety nets...
581
582When any of the "too hot" alarms happen, according to Lenovo the user
583should suspend or hibernate the laptop (and in the case of battery
584alarms, unplug the AC adapter) to let it cool down.  These alarms do
585signal that something is wrong, they should never happen on normal
586operating conditions.
587
588The "extremely hot" alarms are emergencies.  According to Lenovo, the
589operating system is to force either an immediate suspend or hibernate
590cycle, or a system shutdown.  Obviously, something is very wrong if this
591happens.
592
593
594Brightness hotkey notes
595^^^^^^^^^^^^^^^^^^^^^^^
596
597Don't mess with the brightness hotkeys in a Thinkpad.  If you want
598notifications for OSD, use the sysfs backlight class event support.
599
600The driver will issue KEY_BRIGHTNESS_UP and KEY_BRIGHTNESS_DOWN events
601automatically for the cases were userspace has to do something to
602implement brightness changes.  When you override these events, you will
603either fail to handle properly the ThinkPads that require explicit
604action to change backlight brightness, or the ThinkPads that require
605that no action be taken to work properly.
606
607
608Bluetooth
609---------
610
611procfs: /proc/acpi/ibm/bluetooth
612
613sysfs device attribute: bluetooth_enable (deprecated)
614
615sysfs rfkill class: switch "tpacpi_bluetooth_sw"
616
617This feature shows the presence and current state of a ThinkPad
618Bluetooth device in the internal ThinkPad CDC slot.
619
620If the ThinkPad supports it, the Bluetooth state is stored in NVRAM,
621so it is kept across reboots and power-off.
622
623Procfs notes
624^^^^^^^^^^^^
625
626If Bluetooth is installed, the following commands can be used::
627
628	echo enable > /proc/acpi/ibm/bluetooth
629	echo disable > /proc/acpi/ibm/bluetooth
630
631Sysfs notes
632^^^^^^^^^^^
633
634	If the Bluetooth CDC card is installed, it can be enabled /
635	disabled through the "bluetooth_enable" thinkpad-acpi device
636	attribute, and its current status can also be queried.
637
638	enable:
639
640		- 0: disables Bluetooth / Bluetooth is disabled
641		- 1: enables Bluetooth / Bluetooth is enabled.
642
643	Note: this interface has been superseded by the	generic rfkill
644	class.  It has been deprecated, and it will be removed in year
645	2010.
646
647	rfkill controller switch "tpacpi_bluetooth_sw": refer to
648	Documentation/driver-api/rfkill.rst for details.
649
650
651Video output control -- /proc/acpi/ibm/video
652--------------------------------------------
653
654This feature allows control over the devices used for video output -
655LCD, CRT or DVI (if available). The following commands are available::
656
657	echo lcd_enable > /proc/acpi/ibm/video
658	echo lcd_disable > /proc/acpi/ibm/video
659	echo crt_enable > /proc/acpi/ibm/video
660	echo crt_disable > /proc/acpi/ibm/video
661	echo dvi_enable > /proc/acpi/ibm/video
662	echo dvi_disable > /proc/acpi/ibm/video
663	echo auto_enable > /proc/acpi/ibm/video
664	echo auto_disable > /proc/acpi/ibm/video
665	echo expand_toggle > /proc/acpi/ibm/video
666	echo video_switch > /proc/acpi/ibm/video
667
668NOTE:
669  Access to this feature is restricted to processes owning the
670  CAP_SYS_ADMIN capability for safety reasons, as it can interact badly
671  enough with some versions of X.org to crash it.
672
673Each video output device can be enabled or disabled individually.
674Reading /proc/acpi/ibm/video shows the status of each device.
675
676Automatic video switching can be enabled or disabled.  When automatic
677video switching is enabled, certain events (e.g. opening the lid,
678docking or undocking) cause the video output device to change
679automatically. While this can be useful, it also causes flickering
680and, on the X40, video corruption. By disabling automatic switching,
681the flickering or video corruption can be avoided.
682
683The video_switch command cycles through the available video outputs
684(it simulates the behavior of Fn-F7).
685
686Video expansion can be toggled through this feature. This controls
687whether the display is expanded to fill the entire LCD screen when a
688mode with less than full resolution is used. Note that the current
689video expansion status cannot be determined through this feature.
690
691Note that on many models (particularly those using Radeon graphics
692chips) the X driver configures the video card in a way which prevents
693Fn-F7 from working. This also disables the video output switching
694features of this driver, as it uses the same ACPI methods as
695Fn-F7. Video switching on the console should still work.
696
697UPDATE: refer to https://bugs.freedesktop.org/show_bug.cgi?id=2000
698
699
700ThinkLight control
701------------------
702
703procfs: /proc/acpi/ibm/light
704
705sysfs attributes: as per LED class, for the "tpacpi::thinklight" LED
706
707procfs notes
708^^^^^^^^^^^^
709
710The ThinkLight status can be read and set through the procfs interface.  A
711few models which do not make the status available will show the ThinkLight
712status as "unknown". The available commands are::
713
714	echo on  > /proc/acpi/ibm/light
715	echo off > /proc/acpi/ibm/light
716
717sysfs notes
718^^^^^^^^^^^
719
720The ThinkLight sysfs interface is documented by the LED class
721documentation, in Documentation/leds/leds-class.rst.  The ThinkLight LED name
722is "tpacpi::thinklight".
723
724Due to limitations in the sysfs LED class, if the status of the ThinkLight
725cannot be read or if it is unknown, thinkpad-acpi will report it as "off".
726It is impossible to know if the status returned through sysfs is valid.
727
728
729CMOS/UCMS control
730-----------------
731
732procfs: /proc/acpi/ibm/cmos
733
734sysfs device attribute: cmos_command
735
736This feature is mostly used internally by the ACPI firmware to keep the legacy
737CMOS NVRAM bits in sync with the current machine state, and to record this
738state so that the ThinkPad will retain such settings across reboots.
739
740Some of these commands actually perform actions in some ThinkPad models, but
741this is expected to disappear more and more in newer models.  As an example, in
742a T43 and in a X40, commands 12 and 13 still control the ThinkLight state for
743real, but commands 0 to 2 don't control the mixer anymore (they have been
744phased out) and just update the NVRAM.
745
746The range of valid cmos command numbers is 0 to 21, but not all have an
747effect and the behavior varies from model to model.  Here is the behavior
748on the X40 (tpb is the ThinkPad Buttons utility):
749
750	- 0 - Related to "Volume down" key press
751	- 1 - Related to "Volume up" key press
752	- 2 - Related to "Mute on" key press
753	- 3 - Related to "Access IBM" key press
754	- 4 - Related to "LCD brightness up" key press
755	- 5 - Related to "LCD brightness down" key press
756	- 11 - Related to "toggle screen expansion" key press/function
757	- 12 - Related to "ThinkLight on"
758	- 13 - Related to "ThinkLight off"
759	- 14 - Related to "ThinkLight" key press (toggle ThinkLight)
760
761The cmos command interface is prone to firmware split-brain problems, as
762in newer ThinkPads it is just a compatibility layer.  Do not use it, it is
763exported just as a debug tool.
764
765
766LED control
767-----------
768
769procfs: /proc/acpi/ibm/led
770sysfs attributes: as per LED class, see below for names
771
772Some of the LED indicators can be controlled through this feature.  On
773some older ThinkPad models, it is possible to query the status of the
774LED indicators as well.  Newer ThinkPads cannot query the real status
775of the LED indicators.
776
777Because misuse of the LEDs could induce an unaware user to perform
778dangerous actions (like undocking or ejecting a bay device while the
779buses are still active), or mask an important alarm (such as a nearly
780empty battery, or a broken battery), access to most LEDs is
781restricted.
782
783Unrestricted access to all LEDs requires that thinkpad-acpi be
784compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
785Distributions must never enable this option.  Individual users that
786are aware of the consequences are welcome to enabling it.
787
788Audio mute and microphone mute LEDs are supported, but currently not
789visible to userspace. They are used by the snd-hda-intel audio driver.
790
791procfs notes
792^^^^^^^^^^^^
793
794The available commands are::
795
796	echo '<LED number> on' >/proc/acpi/ibm/led
797	echo '<LED number> off' >/proc/acpi/ibm/led
798	echo '<LED number> blink' >/proc/acpi/ibm/led
799
800The <LED number> range is 0 to 15. The set of LEDs that can be
801controlled varies from model to model. Here is the common ThinkPad
802mapping:
803
804	- 0 - power
805	- 1 - battery (orange)
806	- 2 - battery (green)
807	- 3 - UltraBase/dock
808	- 4 - UltraBay
809	- 5 - UltraBase battery slot
810	- 6 - (unknown)
811	- 7 - standby
812	- 8 - dock status 1
813	- 9 - dock status 2
814	- 10, 11 - (unknown)
815	- 12 - thinkvantage
816	- 13, 14, 15 - (unknown)
817
818All of the above can be turned on and off and can be made to blink.
819
820sysfs notes
821^^^^^^^^^^^
822
823The ThinkPad LED sysfs interface is described in detail by the LED class
824documentation, in Documentation/leds/leds-class.rst.
825
826The LEDs are named (in LED ID order, from 0 to 12):
827"tpacpi::power", "tpacpi:orange:batt", "tpacpi:green:batt",
828"tpacpi::dock_active", "tpacpi::bay_active", "tpacpi::dock_batt",
829"tpacpi::unknown_led", "tpacpi::standby", "tpacpi::dock_status1",
830"tpacpi::dock_status2", "tpacpi::unknown_led2", "tpacpi::unknown_led3",
831"tpacpi::thinkvantage".
832
833Due to limitations in the sysfs LED class, if the status of the LED
834indicators cannot be read due to an error, thinkpad-acpi will report it as
835a brightness of zero (same as LED off).
836
837If the thinkpad firmware doesn't support reading the current status,
838trying to read the current LED brightness will just return whatever
839brightness was last written to that attribute.
840
841These LEDs can blink using hardware acceleration.  To request that a
842ThinkPad indicator LED should blink in hardware accelerated mode, use the
843"timer" trigger, and leave the delay_on and delay_off parameters set to
844zero (to request hardware acceleration autodetection).
845
846LEDs that are known not to exist in a given ThinkPad model are not
847made available through the sysfs interface.  If you have a dock and you
848notice there are LEDs listed for your ThinkPad that do not exist (and
849are not in the dock), or if you notice that there are missing LEDs,
850a report to ibm-acpi-devel@lists.sourceforge.net is appreciated.
851
852
853ACPI sounds -- /proc/acpi/ibm/beep
854----------------------------------
855
856The BEEP method is used internally by the ACPI firmware to provide
857audible alerts in various situations. This feature allows the same
858sounds to be triggered manually.
859
860The commands are non-negative integer numbers::
861
862	echo <number> >/proc/acpi/ibm/beep
863
864The valid <number> range is 0 to 17. Not all numbers trigger sounds
865and the sounds vary from model to model. Here is the behavior on the
866X40:
867
868	- 0 - stop a sound in progress (but use 17 to stop 16)
869	- 2 - two beeps, pause, third beep ("low battery")
870	- 3 - single beep
871	- 4 - high, followed by low-pitched beep ("unable")
872	- 5 - single beep
873	- 6 - very high, followed by high-pitched beep ("AC/DC")
874	- 7 - high-pitched beep
875	- 9 - three short beeps
876	- 10 - very long beep
877	- 12 - low-pitched beep
878	- 15 - three high-pitched beeps repeating constantly, stop with 0
879	- 16 - one medium-pitched beep repeating constantly, stop with 17
880	- 17 - stop 16
881
882
883Temperature sensors
884-------------------
885
886procfs: /proc/acpi/ibm/thermal
887
888sysfs device attributes: (hwmon "thinkpad") temp*_input
889
890Most ThinkPads include six or more separate temperature sensors but only
891expose the CPU temperature through the standard ACPI methods.  This
892feature shows readings from up to eight different sensors on older
893ThinkPads, and up to sixteen different sensors on newer ThinkPads.
894
895For example, on the X40, a typical output may be:
896
897temperatures:
898	42 42 45 41 36 -128 33 -128
899
900On the T43/p, a typical output may be:
901
902temperatures:
903	48 48 36 52 38 -128 31 -128 48 52 48 -128 -128 -128 -128 -128
904
905The mapping of thermal sensors to physical locations varies depending on
906system-board model (and thus, on ThinkPad model).
907
908https://thinkwiki.org/wiki/Thermal_Sensors is a public wiki page that
909tries to track down these locations for various models.
910
911Most (newer?) models seem to follow this pattern:
912
913- 1:  CPU
914- 2:  (depends on model)
915- 3:  (depends on model)
916- 4:  GPU
917- 5:  Main battery: main sensor
918- 6:  Bay battery: main sensor
919- 7:  Main battery: secondary sensor
920- 8:  Bay battery: secondary sensor
921- 9-15: (depends on model)
922
923For the R51 (source: Thomas Gruber):
924
925- 2:  Mini-PCI
926- 3:  Internal HDD
927
928For the T43, T43/p (source: Shmidoax/Thinkwiki.org)
929https://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_T43.2C_T43p
930
931- 2:  System board, left side (near PCMCIA slot), reported as HDAPS temp
932- 3:  PCMCIA slot
933- 9:  MCH (northbridge) to DRAM Bus
934- 10: Clock-generator, mini-pci card and ICH (southbridge), under Mini-PCI
935      card, under touchpad
936- 11: Power regulator, underside of system board, below F2 key
937
938The A31 has a very atypical layout for the thermal sensors
939(source: Milos Popovic, https://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_A31)
940
941- 1:  CPU
942- 2:  Main Battery: main sensor
943- 3:  Power Converter
944- 4:  Bay Battery: main sensor
945- 5:  MCH (northbridge)
946- 6:  PCMCIA/ambient
947- 7:  Main Battery: secondary sensor
948- 8:  Bay Battery: secondary sensor
949
950
951Procfs notes
952^^^^^^^^^^^^
953
954	Readings from sensors that are not available return -128.
955	No commands can be written to this file.
956
957Sysfs notes
958^^^^^^^^^^^
959
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
979	- make sure the battery is fully charged
980	- make sure the fan is running
981	- use above mentioned tool to read out the EC
982
983Often fan and temperature values vary between
984readings. Since temperatures don't change vary fast, you can take
985several quick dumps to eliminate them.
986
987You can use a similar method to figure out the meaning of other
988embedded controller registers - e.g. make sure nothing else changes
989except the charging or discharging battery to determine which
990registers contain the current battery capacity, etc. If you experiment
991with this, do send me your results (including some complete dumps with
992a description of the conditions when they were taken.)
993
994
995LCD brightness control
996----------------------
997
998procfs: /proc/acpi/ibm/brightness
999
1000sysfs backlight device "thinkpad_screen"
1001
1002This feature allows software control of the LCD brightness on ThinkPad
1003models which don't have a hardware brightness slider.
1004
1005It has some limitations: the LCD backlight cannot be actually turned
1006on or off by this interface, it just controls the backlight brightness
1007level.
1008
1009On IBM (and some of the earlier Lenovo) ThinkPads, the backlight control
1010has eight brightness levels, ranging from 0 to 7.  Some of the levels
1011may not be distinct.  Later Lenovo models that implement the ACPI
1012display backlight brightness control methods have 16 levels, ranging
1013from 0 to 15.
1014
1015For IBM ThinkPads, there are two interfaces to the firmware for direct
1016brightness control, EC and UCMS (or CMOS).  To select which one should be
1017used, use the brightness_mode module parameter: brightness_mode=1 selects
1018EC mode, brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
1019mode with NVRAM backing (so that brightness changes are remembered across
1020shutdown/reboot).
1021
1022The driver tries to select which interface to use from a table of
1023defaults for each ThinkPad model.  If it makes a wrong choice, please
1024report this as a bug, so that we can fix it.
1025
1026Lenovo ThinkPads only support brightness_mode=2 (UCMS).
1027
1028When display backlight brightness controls are available through the
1029standard ACPI interface, it is best to use it instead of this direct
1030ThinkPad-specific interface.  The driver will disable its native
1031backlight brightness control interface if it detects that the standard
1032ACPI interface is available in the ThinkPad.
1033
1034If you want to use the thinkpad-acpi backlight brightness control
1035instead of the generic ACPI video backlight brightness control for some
1036reason, you should use the acpi_backlight=vendor kernel parameter.
1037
1038The brightness_enable module parameter can be used to control whether
1039the LCD brightness control feature will be enabled when available.
1040brightness_enable=0 forces it to be disabled.  brightness_enable=1
1041forces it to be enabled when available, even if the standard ACPI
1042interface is also available.
1043
1044Procfs notes
1045^^^^^^^^^^^^
1046
1047The available commands are::
1048
1049	echo up   >/proc/acpi/ibm/brightness
1050	echo down >/proc/acpi/ibm/brightness
1051	echo 'level <level>' >/proc/acpi/ibm/brightness
1052
1053Sysfs notes
1054^^^^^^^^^^^
1055
1056The interface is implemented through the backlight sysfs class, which is
1057poorly documented at this time.
1058
1059Locate the thinkpad_screen device under /sys/class/backlight, and inside
1060it there will be the following attributes:
1061
1062	max_brightness:
1063		Reads the maximum brightness the hardware can be set to.
1064		The minimum is always zero.
1065
1066	actual_brightness:
1067		Reads what brightness the screen is set to at this instant.
1068
1069	brightness:
1070		Writes request the driver to change brightness to the
1071		given value.  Reads will tell you what brightness the
1072		driver is trying to set the display to when "power" is set
1073		to zero and the display has not been dimmed by a kernel
1074		power management event.
1075
1076	power:
1077		power management mode, where 0 is "display on", and 1 to 3
1078		will dim the display backlight to brightness level 0
1079		because thinkpad-acpi cannot really turn the backlight
1080		off.  Kernel power management events can temporarily
1081		increase the current power management level, i.e. they can
1082		dim the display.
1083
1084
1085WARNING:
1086
1087    Whatever you do, do NOT ever call thinkpad-acpi backlight-level change
1088    interface and the ACPI-based backlight level change interface
1089    (available on newer BIOSes, and driven by the Linux ACPI video driver)
1090    at the same time.  The two will interact in bad ways, do funny things,
1091    and maybe reduce the life of the backlight lamps by needlessly kicking
1092    its level up and down at every change.
1093
1094
1095Volume control (Console Audio control)
1096--------------------------------------
1097
1098procfs: /proc/acpi/ibm/volume
1099
1100ALSA: "ThinkPad Console Audio Control", default ID: "ThinkPadEC"
1101
1102NOTE: by default, the volume control interface operates in read-only
1103mode, as it is supposed to be used for on-screen-display purposes.
1104The read/write mode can be enabled through the use of the
1105"volume_control=1" module parameter.
1106
1107NOTE: distros are urged to not enable volume_control by default, this
1108should be done by the local admin only.  The ThinkPad UI is for the
1109console audio control to be done through the volume keys only, and for
1110the desktop environment to just provide on-screen-display feedback.
1111Software volume control should be done only in the main AC97/HDA
1112mixer.
1113
1114
1115About the ThinkPad Console Audio control
1116^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1117
1118ThinkPads have a built-in amplifier and muting circuit that drives the
1119console headphone and speakers.  This circuit is after the main AC97
1120or HDA mixer in the audio path, and under exclusive control of the
1121firmware.
1122
1123ThinkPads have three special hotkeys to interact with the console
1124audio control: volume up, volume down and mute.
1125
1126It is worth noting that the normal way the mute function works (on
1127ThinkPads that do not have a "mute LED") is:
1128
11291. Press mute to mute.  It will *always* mute, you can press it as
1130   many times as you want, and the sound will remain mute.
1131
11322. Press either volume key to unmute the ThinkPad (it will _not_
1133   change the volume, it will just unmute).
1134
1135This is a very superior design when compared to the cheap software-only
1136mute-toggle solution found on normal consumer laptops:  you can be
1137absolutely sure the ThinkPad will not make noise if you press the mute
1138button, no matter the previous state.
1139
1140The IBM ThinkPads, and the earlier Lenovo ThinkPads have variable-gain
1141amplifiers driving the speakers and headphone output, and the firmware
1142also handles volume control for the headphone and speakers on these
1143ThinkPads without any help from the operating system (this volume
1144control stage exists after the main AC97 or HDA mixer in the audio
1145path).
1146
1147The newer Lenovo models only have firmware mute control, and depend on
1148the main HDA mixer to do volume control (which is done by the operating
1149system).  In this case, the volume keys are filtered out for unmute
1150key press (there are some firmware bugs in this area) and delivered as
1151normal key presses to the operating system (thinkpad-acpi is not
1152involved).
1153
1154
1155The ThinkPad-ACPI volume control
1156^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1157
1158The preferred way to interact with the Console Audio control is the
1159ALSA interface.
1160
1161The legacy procfs interface allows one to read the current state,
1162and if volume control is enabled, accepts the following commands::
1163
1164	echo up   >/proc/acpi/ibm/volume
1165	echo down >/proc/acpi/ibm/volume
1166	echo mute >/proc/acpi/ibm/volume
1167	echo unmute >/proc/acpi/ibm/volume
1168	echo 'level <level>' >/proc/acpi/ibm/volume
1169
1170The <level> number range is 0 to 14 although not all of them may be
1171distinct. To unmute the volume after the mute command, use either the
1172up or down command (the level command will not unmute the volume), or
1173the unmute command.
1174
1175You can use the volume_capabilities parameter to tell the driver
1176whether your thinkpad has volume control or mute-only control:
1177volume_capabilities=1 for mixers with mute and volume control,
1178volume_capabilities=2 for mixers with only mute control.
1179
1180If the driver misdetects the capabilities for your ThinkPad model,
1181please report this to ibm-acpi-devel@lists.sourceforge.net, so that we
1182can update the driver.
1183
1184There are two strategies for volume control.  To select which one
1185should be used, use the volume_mode module parameter: volume_mode=1
1186selects EC mode, and volume_mode=3 selects EC mode with NVRAM backing
1187(so that volume/mute changes are remembered across shutdown/reboot).
1188
1189The driver will operate in volume_mode=3 by default. If that does not
1190work well on your ThinkPad model, please report this to
1191ibm-acpi-devel@lists.sourceforge.net.
1192
1193The driver supports the standard ALSA module parameters.  If the ALSA
1194mixer is disabled, the driver will disable all volume functionality.
1195
1196
1197Fan control and monitoring: fan speed, fan enable/disable
1198---------------------------------------------------------
1199
1200procfs: /proc/acpi/ibm/fan
1201
1202sysfs device attributes: (hwmon "thinkpad") fan1_input, pwm1, pwm1_enable, fan2_input
1203
1204sysfs hwmon driver attributes: fan_watchdog
1205
1206NOTE NOTE NOTE:
1207   fan control operations are disabled by default for
1208   safety reasons.  To enable them, the module parameter "fan_control=1"
1209   must be given to thinkpad-acpi.
1210
1211This feature attempts to show the current fan speed, control mode and
1212other fan data that might be available.  The speed is read directly
1213from the hardware registers of the embedded controller.  This is known
1214to work on later R, T, X and Z series ThinkPads but may show a bogus
1215value on other models.
1216
1217Some Lenovo ThinkPads support a secondary fan.  This fan cannot be
1218controlled separately, it shares the main fan control.
1219
1220Fan levels
1221^^^^^^^^^^
1222
1223Most ThinkPad fans work in "levels" at the firmware interface.  Level 0
1224stops the fan.  The higher the level, the higher the fan speed, although
1225adjacent levels often map to the same fan speed.  7 is the highest
1226level, where the fan reaches the maximum recommended speed.
1227
1228Level "auto" means the EC changes the fan level according to some
1229internal algorithm, usually based on readings from the thermal sensors.
1230
1231There is also a "full-speed" level, also known as "disengaged" level.
1232In this level, the EC disables the speed-locked closed-loop fan control,
1233and drives the fan as fast as it can go, which might exceed hardware
1234limits, so use this level with caution.
1235
1236The fan usually ramps up or down slowly from one speed to another, and
1237it is normal for the EC to take several seconds to react to fan
1238commands.  The full-speed level may take up to two minutes to ramp up to
1239maximum speed, and in some ThinkPads, the tachometer readings go stale
1240while the EC is transitioning to the full-speed level.
1241
1242WARNING WARNING WARNING: do not leave the fan disabled unless you are
1243monitoring all of the temperature sensor readings and you are ready to
1244enable it if necessary to avoid overheating.
1245
1246An enabled fan in level "auto" may stop spinning if the EC decides the
1247ThinkPad is cool enough and doesn't need the extra airflow.  This is
1248normal, and the EC will spin the fan up if the various thermal readings
1249rise too much.
1250
1251On the X40, this seems to depend on the CPU and HDD temperatures.
1252Specifically, the fan is turned on when either the CPU temperature
1253climbs to 56 degrees or the HDD temperature climbs to 46 degrees.  The
1254fan is turned off when the CPU temperature drops to 49 degrees and the
1255HDD temperature drops to 41 degrees.  These thresholds cannot
1256currently be controlled.
1257
1258The ThinkPad's ACPI DSDT code will reprogram the fan on its own when
1259certain conditions are met.  It will override any fan programming done
1260through thinkpad-acpi.
1261
1262The thinkpad-acpi kernel driver can be programmed to revert the fan
1263level to a safe setting if userspace does not issue one of the procfs
1264fan commands: "enable", "disable", "level" or "watchdog", or if there
1265are no writes to pwm1_enable (or to pwm1 *if and only if* pwm1_enable is
1266set to 1, manual mode) within a configurable amount of time of up to
1267120 seconds.  This functionality is called fan safety watchdog.
1268
1269Note that the watchdog timer stops after it enables the fan.  It will be
1270rearmed again automatically (using the same interval) when one of the
1271above mentioned fan commands is received.  The fan watchdog is,
1272therefore, not suitable to protect against fan mode changes made through
1273means other than the "enable", "disable", and "level" procfs fan
1274commands, or the hwmon fan control sysfs interface.
1275
1276Procfs notes
1277^^^^^^^^^^^^
1278
1279The fan may be enabled or disabled with the following commands::
1280
1281	echo enable  >/proc/acpi/ibm/fan
1282	echo disable >/proc/acpi/ibm/fan
1283
1284Placing a fan on level 0 is the same as disabling it.  Enabling a fan
1285will try to place it in a safe level if it is too slow or disabled.
1286
1287The fan level can be controlled with the command::
1288
1289	echo 'level <level>' > /proc/acpi/ibm/fan
1290
1291Where <level> is an integer from 0 to 7, or one of the words "auto" or
1292"full-speed" (without the quotes).  Not all ThinkPads support the "auto"
1293and "full-speed" levels.  The driver accepts "disengaged" as an alias for
1294"full-speed", and reports it as "disengaged" for backwards
1295compatibility.
1296
1297On the X31 and X40 (and ONLY on those models), the fan speed can be
1298controlled to a certain degree.  Once the fan is running, it can be
1299forced to run faster or slower with the following command::
1300
1301	echo 'speed <speed>' > /proc/acpi/ibm/fan
1302
1303The sustainable range of fan speeds on the X40 appears to be from about
13043700 to about 7350. Values outside this range either do not have any
1305effect or the fan speed eventually settles somewhere in that range.  The
1306fan cannot be stopped or started with this command.  This functionality
1307is incomplete, and not available through the sysfs interface.
1308
1309To program the safety watchdog, use the "watchdog" command::
1310
1311	echo 'watchdog <interval in seconds>' > /proc/acpi/ibm/fan
1312
1313If you want to disable the watchdog, use 0 as the interval.
1314
1315Sysfs notes
1316^^^^^^^^^^^
1317
1318The sysfs interface follows the hwmon subsystem guidelines for the most
1319part, and the exception is the fan safety watchdog.
1320
1321Writes to any of the sysfs attributes may return the EINVAL error if
1322that operation is not supported in a given ThinkPad or if the parameter
1323is out-of-bounds, and EPERM if it is forbidden.  They may also return
1324EINTR (interrupted system call), and EIO (I/O error while trying to talk
1325to the firmware).
1326
1327Features not yet implemented by the driver return ENOSYS.
1328
1329hwmon device attribute pwm1_enable:
1330	- 0: PWM offline (fan is set to full-speed mode)
1331	- 1: Manual PWM control (use pwm1 to set fan level)
1332	- 2: Hardware PWM control (EC "auto" mode)
1333	- 3: reserved (Software PWM control, not implemented yet)
1334
1335	Modes 0 and 2 are not supported by all ThinkPads, and the
1336	driver is not always able to detect this.  If it does know a
1337	mode is unsupported, it will return -EINVAL.
1338
1339hwmon device attribute pwm1:
1340	Fan level, scaled from the firmware values of 0-7 to the hwmon
1341	scale of 0-255.  0 means fan stopped, 255 means highest normal
1342	speed (level 7).
1343
1344	This attribute only commands the fan if pmw1_enable is set to 1
1345	(manual PWM control).
1346
1347hwmon device attribute fan1_input:
1348	Fan tachometer reading, in RPM.  May go stale on certain
1349	ThinkPads while the EC transitions the PWM to offline mode,
1350	which can take up to two minutes.  May return rubbish on older
1351	ThinkPads.
1352
1353hwmon device attribute fan2_input:
1354	Fan tachometer reading, in RPM, for the secondary fan.
1355	Available only on some ThinkPads.  If the secondary fan is
1356	not installed, will always read 0.
1357
1358hwmon driver attribute fan_watchdog:
1359	Fan safety watchdog timer interval, in seconds.  Minimum is
1360	1 second, maximum is 120 seconds.  0 disables the watchdog.
1361
1362To stop the fan: set pwm1 to zero, and pwm1_enable to 1.
1363
1364To start the fan in a safe mode: set pwm1_enable to 2.  If that fails
1365with EINVAL, try to set pwm1_enable to 1 and pwm1 to at least 128 (255
1366would be the safest choice, though).
1367
1368
1369WAN
1370---
1371
1372procfs: /proc/acpi/ibm/wan
1373
1374sysfs device attribute: wwan_enable (deprecated)
1375
1376sysfs rfkill class: switch "tpacpi_wwan_sw"
1377
1378This feature shows the presence and current state of the built-in
1379Wireless WAN device.
1380
1381If the ThinkPad supports it, the WWAN state is stored in NVRAM,
1382so it is kept across reboots and power-off.
1383
1384It was tested on a Lenovo ThinkPad X60. It should probably work on other
1385ThinkPad models which come with this module installed.
1386
1387Procfs notes
1388^^^^^^^^^^^^
1389
1390If the W-WAN card is installed, the following commands can be used::
1391
1392	echo enable > /proc/acpi/ibm/wan
1393	echo disable > /proc/acpi/ibm/wan
1394
1395Sysfs notes
1396^^^^^^^^^^^
1397
1398	If the W-WAN card is installed, it can be enabled /
1399	disabled through the "wwan_enable" thinkpad-acpi device
1400	attribute, and its current status can also be queried.
1401
1402	enable:
1403		- 0: disables WWAN card / WWAN card is disabled
1404		- 1: enables WWAN card / WWAN card is enabled.
1405
1406	Note: this interface has been superseded by the	generic rfkill
1407	class.  It has been deprecated, and it will be removed in year
1408	2010.
1409
1410	rfkill controller switch "tpacpi_wwan_sw": refer to
1411	Documentation/driver-api/rfkill.rst for details.
1412
1413
1414LCD Shadow control
1415------------------
1416
1417procfs: /proc/acpi/ibm/lcdshadow
1418
1419Some newer T480s and T490s ThinkPads provide a feature called
1420PrivacyGuard. By turning this feature on, the usable vertical and
1421horizontal viewing angles of the LCD can be limited (as if some privacy
1422screen was applied manually in front of the display).
1423
1424procfs notes
1425^^^^^^^^^^^^
1426
1427The available commands are::
1428
1429	echo '0' >/proc/acpi/ibm/lcdshadow
1430	echo '1' >/proc/acpi/ibm/lcdshadow
1431
1432The first command ensures the best viewing angle and the latter one turns
1433on the feature, restricting the viewing angles.
1434
1435
1436DYTC Lapmode sensor
1437-------------------
1438
1439sysfs: dytc_lapmode
1440
1441Newer thinkpads and mobile workstations have the ability to determine if
1442the device is in deskmode or lapmode. This feature is used by user space
1443to decide if WWAN transmission can be increased to maximum power and is
1444also useful for understanding the different thermal modes available as
1445they differ between desk and lap mode.
1446
1447The property is read-only. If the platform doesn't have support the sysfs
1448class is not created.
1449
1450EXPERIMENTAL: UWB
1451-----------------
1452
1453This feature is considered EXPERIMENTAL because it has not been extensively
1454tested and validated in various ThinkPad models yet.  The feature may not
1455work as expected. USE WITH CAUTION! To use this feature, you need to supply
1456the experimental=1 parameter when loading the module.
1457
1458sysfs rfkill class: switch "tpacpi_uwb_sw"
1459
1460This feature exports an rfkill controller for the UWB device, if one is
1461present and enabled in the BIOS.
1462
1463Sysfs notes
1464^^^^^^^^^^^
1465
1466	rfkill controller switch "tpacpi_uwb_sw": refer to
1467	Documentation/driver-api/rfkill.rst for details.
1468
1469Adaptive keyboard
1470-----------------
1471
1472sysfs device attribute: adaptive_kbd_mode
1473
1474This sysfs attribute controls the keyboard "face" that will be shown on the
1475Lenovo X1 Carbon 2nd gen (2014)'s adaptive keyboard. The value can be read
1476and set.
1477
1478- 1 = Home mode
1479- 2 = Web-browser mode
1480- 3 = Web-conference mode
1481- 4 = Function mode
1482- 5 = Layflat mode
1483
1484For more details about which buttons will appear depending on the mode, please
1485review the laptop's user guide:
1486http://www.lenovo.com/shop/americas/content/user_guides/x1carbon_2_ug_en.pdf
1487
1488Battery charge control
1489----------------------
1490
1491sysfs attributes:
1492/sys/class/power_supply/BAT*/charge_control_{start,end}_threshold
1493
1494These two attributes are created for those batteries that are supported by the
1495driver. They enable the user to control the battery charge thresholds of the
1496given battery. Both values may be read and set. `charge_control_start_threshold`
1497accepts an integer between 0 and 99 (inclusive); this value represents a battery
1498percentage level, below which charging will begin. `charge_control_end_threshold`
1499accepts an integer between 1 and 100 (inclusive); this value represents a battery
1500percentage level, above which charging will stop.
1501
1502The exact semantics of the attributes may be found in
1503Documentation/ABI/testing/sysfs-class-power.
1504
1505Multiple Commands, Module Parameters
1506------------------------------------
1507
1508Multiple commands can be written to the proc files in one shot by
1509separating them with commas, for example::
1510
1511	echo enable,0xffff > /proc/acpi/ibm/hotkey
1512	echo lcd_disable,crt_enable > /proc/acpi/ibm/video
1513
1514Commands can also be specified when loading the thinkpad-acpi module,
1515for example::
1516
1517	modprobe thinkpad_acpi hotkey=enable,0xffff video=auto_disable
1518
1519
1520Enabling debugging output
1521-------------------------
1522
1523The module takes a debug parameter which can be used to selectively
1524enable various classes of debugging output, for example::
1525
1526	 modprobe thinkpad_acpi debug=0xffff
1527
1528will enable all debugging output classes.  It takes a bitmask, so
1529to enable more than one output class, just add their values.
1530
1531	=============		======================================
1532	Debug bitmask		Description
1533	=============		======================================
1534	0x8000			Disclose PID of userspace programs
1535				accessing some functions of the driver
1536	0x0001			Initialization and probing
1537	0x0002			Removal
1538	0x0004			RF Transmitter control (RFKILL)
1539				(bluetooth, WWAN, UWB...)
1540	0x0008			HKEY event interface, hotkeys
1541	0x0010			Fan control
1542	0x0020			Backlight brightness
1543	0x0040			Audio mixer/volume control
1544	=============		======================================
1545
1546There is also a kernel build option to enable more debugging
1547information, which may be necessary to debug driver problems.
1548
1549The level of debugging information output by the driver can be changed
1550at runtime through sysfs, using the driver attribute debug_level.  The
1551attribute takes the same bitmask as the debug module parameter above.
1552
1553
1554Force loading of module
1555-----------------------
1556
1557If thinkpad-acpi refuses to detect your ThinkPad, you can try to specify
1558the module parameter force_load=1.  Regardless of whether this works or
1559not, please contact ibm-acpi-devel@lists.sourceforge.net with a report.
1560
1561
1562Sysfs interface changelog
1563^^^^^^^^^^^^^^^^^^^^^^^^^
1564
1565=========	===============================================================
15660x000100:	Initial sysfs support, as a single platform driver and
1567		device.
15680x000200:	Hot key support for 32 hot keys, and radio slider switch
1569		support.
15700x010000:	Hot keys are now handled by default over the input
1571		layer, the radio switch generates input event EV_RADIO,
1572		and the driver enables hot key handling by default in
1573		the firmware.
1574
15750x020000:	ABI fix: added a separate hwmon platform device and
1576		driver, which must be located by name (thinkpad)
1577		and the hwmon class for libsensors4 (lm-sensors 3)
1578		compatibility.  Moved all hwmon attributes to this
1579		new platform device.
1580
15810x020100:	Marker for thinkpad-acpi with hot key NVRAM polling
1582		support.  If you must, use it to know you should not
1583		start a userspace NVRAM poller (allows to detect when
1584		NVRAM is compiled out by the user because it is
1585		unneeded/undesired in the first place).
15860x020101:	Marker for thinkpad-acpi with hot key NVRAM polling
1587		and proper hotkey_mask semantics (version 8 of the
1588		NVRAM polling patch).  Some development snapshots of
1589		0.18 had an earlier version that did strange things
1590		to hotkey_mask.
1591
15920x020200:	Add poll()/select() support to the following attributes:
1593		hotkey_radio_sw, wakeup_hotunplug_complete, wakeup_reason
1594
15950x020300:	hotkey enable/disable support removed, attributes
1596		hotkey_bios_enabled and hotkey_enable deprecated and
1597		marked for removal.
1598
15990x020400:	Marker for 16 LEDs support.  Also, LEDs that are known
1600		to not exist in a given model are not registered with
1601		the LED sysfs class anymore.
1602
16030x020500:	Updated hotkey driver, hotkey_mask is always available
1604		and it is always able to disable hot keys.  Very old
1605		thinkpads are properly supported.  hotkey_bios_mask
1606		is deprecated and marked for removal.
1607
16080x020600:	Marker for backlight change event support.
1609
16100x020700:	Support for mute-only mixers.
1611		Volume control in read-only mode by default.
1612		Marker for ALSA mixer support.
1613
16140x030000:	Thermal and fan sysfs attributes were moved to the hwmon
1615		device instead of being attached to the backing platform
1616		device.
1617=========	===============================================================
1618