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Based on kernel version 3.13. Page generated on 2014-01-20 22:03 EST.

1			     ThinkPad ACPI Extras Driver
2	
3	                            Version 0.25
4	                        October 16th,  2013
5	
6	               Borislav Deianov <borislav@users.sf.net>
7	             Henrique de Moraes Holschuh <hmh@hmh.eng.br>
8	                      http://ibm-acpi.sf.net/
9	
10	
11	This is a Linux driver for the IBM and Lenovo ThinkPad laptops. It
12	supports various features of these laptops which are accessible
13	through the ACPI and ACPI EC framework, but not otherwise fully
14	supported by the generic Linux ACPI drivers.
15	
16	This driver used to be named ibm-acpi until kernel 2.6.21 and release
17	0.13-20070314.  It used to be in the drivers/acpi tree, but it was
18	moved to the drivers/misc tree and renamed to thinkpad-acpi for kernel
19	2.6.22, and release 0.14.  It was moved to drivers/platform/x86 for
20	kernel 2.6.29 and release 0.22.
21	
22	The driver is named "thinkpad-acpi".  In some places, like module
23	names and log messages, "thinkpad_acpi" is used because of userspace
24	issues.
25	
26	"tpacpi" is used as a shorthand where "thinkpad-acpi" would be too
27	long due to length limitations on some Linux kernel versions.
28	
29	Status
30	------
31	
32	The features currently supported are the following (see below for
33	detailed description):
34	
35		- Fn key combinations
36		- Bluetooth enable and disable
37		- video output switching, expansion control
38		- ThinkLight on and off
39		- CMOS/UCMS control
40		- LED control
41		- ACPI sounds
42		- temperature sensors
43		- Experimental: embedded controller register dump
44		- LCD brightness control
45		- Volume control
46		- Fan control and monitoring: fan speed, fan enable/disable
47		- WAN enable and disable
48		- UWB enable and disable
49	
50	A compatibility table by model and feature is maintained on the web
51	site, http://ibm-acpi.sf.net/. I appreciate any success or failure
52	reports, especially if they add to or correct the compatibility table.
53	Please include the following information in your report:
54	
55		- ThinkPad model name
56		- a copy of your ACPI tables, using the "acpidump" utility
57		- a copy of the output of dmidecode, with serial numbers
58		  and UUIDs masked off
59		- which driver features work and which don't
60		- the observed behavior of non-working features
61	
62	Any other comments or patches are also more than welcome.
63	
64	
65	Installation
66	------------
67	
68	If you are compiling this driver as included in the Linux kernel
69	sources, look for the CONFIG_THINKPAD_ACPI Kconfig option.
70	It is located on the menu path: "Device Drivers" -> "X86 Platform
71	Specific Device Drivers" -> "ThinkPad ACPI Laptop Extras".
72	
73	
74	Features
75	--------
76	
77	The driver exports two different interfaces to userspace, which can be
78	used to access the features it provides.  One is a legacy procfs-based
79	interface, which will be removed at some time in the future.  The other
80	is a new sysfs-based interface which is not complete yet.
81	
82	The procfs interface creates the /proc/acpi/ibm directory.  There is a
83	file under that directory for each feature it supports.  The procfs
84	interface is mostly frozen, and will change very little if at all: it
85	will not be extended to add any new functionality in the driver, instead
86	all new functionality will be implemented on the sysfs interface.
87	
88	The sysfs interface tries to blend in the generic Linux sysfs subsystems
89	and classes as much as possible.  Since some of these subsystems are not
90	yet ready or stabilized, it is expected that this interface will change,
91	and any and all userspace programs must deal with it.
92	
93	
94	Notes about the sysfs interface:
95	
96	Unlike what was done with the procfs interface, correctness when talking
97	to the sysfs interfaces will be enforced, as will correctness in the
98	thinkpad-acpi's implementation of sysfs interfaces.
99	
100	Also, any bugs in the thinkpad-acpi sysfs driver code or in the
101	thinkpad-acpi's implementation of the sysfs interfaces will be fixed for
102	maximum correctness, even if that means changing an interface in
103	non-compatible ways.  As these interfaces mature both in the kernel and
104	in thinkpad-acpi, such changes should become quite rare.
105	
106	Applications interfacing to the thinkpad-acpi sysfs interfaces must
107	follow all sysfs guidelines and correctly process all errors (the sysfs
108	interface makes extensive use of errors).  File descriptors and open /
109	close operations to the sysfs inodes must also be properly implemented.
110	
111	The version of thinkpad-acpi's sysfs interface is exported by the driver
112	as a driver attribute (see below).
113	
114	Sysfs driver attributes are on the driver's sysfs attribute space,
115	for 2.6.23+ this is /sys/bus/platform/drivers/thinkpad_acpi/ and
116	/sys/bus/platform/drivers/thinkpad_hwmon/
117	
118	Sysfs device attributes are on the thinkpad_acpi device sysfs attribute
119	space, for 2.6.23+ this is /sys/devices/platform/thinkpad_acpi/.
120	
121	Sysfs device attributes for the sensors and fan are on the
122	thinkpad_hwmon device's sysfs attribute space, but you should locate it
123	looking for a hwmon device with the name attribute of "thinkpad", or
124	better yet, through libsensors.
125	
126	
127	Driver version
128	--------------
129	
130	procfs: /proc/acpi/ibm/driver
131	sysfs driver attribute: version
132	
133	The driver name and version. No commands can be written to this file.
134	
135	
136	Sysfs interface version
137	-----------------------
138	
139	sysfs driver attribute: interface_version
140	
141	Version of the thinkpad-acpi sysfs interface, as an unsigned long
142	(output in hex format: 0xAAAABBCC), where:
143		AAAA - major revision
144		BB - minor revision
145		CC - bugfix revision
146	
147	The sysfs interface version changelog for the driver can be found at the
148	end of this document.  Changes to the sysfs interface done by the kernel
149	subsystems are not documented here, nor are they tracked by this
150	attribute.
151	
152	Changes to the thinkpad-acpi sysfs interface are only considered
153	non-experimental when they are submitted to Linux mainline, at which
154	point the changes in this interface are documented and interface_version
155	may be updated.  If you are using any thinkpad-acpi features not yet
156	sent to mainline for merging, you do so on your own risk: these features
157	may disappear, or be implemented in a different and incompatible way by
158	the time they are merged in Linux mainline.
159	
160	Changes that are backwards-compatible by nature (e.g. the addition of
161	attributes that do not change the way the other attributes work) do not
162	always warrant an update of interface_version.  Therefore, one must
163	expect that an attribute might not be there, and deal with it properly
164	(an attribute not being there *is* a valid way to make it clear that a
165	feature is not available in sysfs).
166	
167	
168	Hot keys
169	--------
170	
171	procfs: /proc/acpi/ibm/hotkey
172	sysfs device attribute: hotkey_*
173	
174	In a ThinkPad, the ACPI HKEY handler is responsible for communicating
175	some important events and also keyboard hot key presses to the operating
176	system.  Enabling the hotkey functionality of thinkpad-acpi signals the
177	firmware that such a driver is present, and modifies how the ThinkPad
178	firmware will behave in many situations.
179	
180	The driver enables the HKEY ("hot key") event reporting automatically
181	when loaded, and disables it when it is removed.
182	
183	The driver will report HKEY events in the following format:
184	
185		ibm/hotkey HKEY 00000080 0000xxxx
186	
187	Some of these events refer to hot key presses, but not all of them.
188	
189	The driver will generate events over the input layer for hot keys and
190	radio switches, and over the ACPI netlink layer for other events.  The
191	input layer support accepts the standard IOCTLs to remap the keycodes
192	assigned to each hot key.
193	
194	The hot key bit mask allows some control over which hot keys generate
195	events.  If a key is "masked" (bit set to 0 in the mask), the firmware
196	will handle it.  If it is "unmasked", it signals the firmware that
197	thinkpad-acpi would prefer to handle it, if the firmware would be so
198	kind to allow it (and it often doesn't!).
199	
200	Not all bits in the mask can be modified.  Not all bits that can be
201	modified do anything.  Not all hot keys can be individually controlled
202	by the mask.  Some models do not support the mask at all.  The behaviour
203	of the mask is, therefore, highly dependent on the ThinkPad model.
204	
205	The driver will filter out any unmasked hotkeys, so even if the firmware
206	doesn't allow disabling an specific hotkey, the driver will not report
207	events for unmasked hotkeys.
208	
209	Note that unmasking some keys prevents their default behavior.  For
210	example, if Fn+F5 is unmasked, that key will no longer enable/disable
211	Bluetooth by itself in firmware.
212	
213	Note also that not all Fn key combinations are supported through ACPI
214	depending on the ThinkPad model and firmware version.  On those
215	ThinkPads, it is still possible to support some extra hotkeys by
216	polling the "CMOS NVRAM" at least 10 times per second.  The driver
217	attempts to enables this functionality automatically when required.
218	
219	procfs notes:
220	
221	The following commands can be written to the /proc/acpi/ibm/hotkey file:
222	
223		echo 0xffffffff > /proc/acpi/ibm/hotkey -- enable all hot keys
224		echo 0 > /proc/acpi/ibm/hotkey -- disable all possible hot keys
225		... any other 8-hex-digit mask ...
226		echo reset > /proc/acpi/ibm/hotkey -- restore the recommended mask
227	
228	The following commands have been deprecated and will cause the kernel
229	to log a warning:
230	
231		echo enable > /proc/acpi/ibm/hotkey -- does nothing
232		echo disable > /proc/acpi/ibm/hotkey -- returns an error
233	
234	The procfs interface does not support NVRAM polling control.  So as to
235	maintain maximum bug-to-bug compatibility, it does not report any masks,
236	nor does it allow one to manipulate the hot key mask when the firmware
237	does not support masks at all, even if NVRAM polling is in use.
238	
239	sysfs notes:
240	
241		hotkey_bios_enabled:
242			DEPRECATED, WILL BE REMOVED SOON.
243	
244			Returns 0.
245	
246		hotkey_bios_mask:
247			DEPRECATED, DON'T USE, WILL BE REMOVED IN THE FUTURE.
248	
249			Returns the hot keys mask when thinkpad-acpi was loaded.
250			Upon module unload, the hot keys mask will be restored
251			to this value.   This is always 0x80c, because those are
252			the hotkeys that were supported by ancient firmware
253			without mask support.
254	
255		hotkey_enable:
256			DEPRECATED, WILL BE REMOVED SOON.
257	
258			0: returns -EPERM
259			1: does nothing
260	
261		hotkey_mask:
262			bit mask to enable reporting (and depending on
263			the firmware, ACPI event generation) for each hot key
264			(see above).  Returns the current status of the hot keys
265			mask, and allows one to modify it.
266	
267		hotkey_all_mask:
268			bit mask that should enable event reporting for all
269			supported hot keys, when echoed to hotkey_mask above.
270			Unless you know which events need to be handled
271			passively (because the firmware *will* handle them
272			anyway), do *not* use hotkey_all_mask.  Use
273			hotkey_recommended_mask, instead. You have been warned.
274	
275		hotkey_recommended_mask:
276			bit mask that should enable event reporting for all
277			supported hot keys, except those which are always
278			handled by the firmware anyway.  Echo it to
279			hotkey_mask above, to use.  This is the default mask
280			used by the driver.
281	
282		hotkey_source_mask:
283			bit mask that selects which hot keys will the driver
284			poll the NVRAM for.  This is auto-detected by the driver
285			based on the capabilities reported by the ACPI firmware,
286			but it can be overridden at runtime.
287	
288			Hot keys whose bits are set in hotkey_source_mask are
289			polled for in NVRAM, and reported as hotkey events if
290			enabled in hotkey_mask.  Only a few hot keys are
291			available through CMOS NVRAM polling.
292	
293			Warning: when in NVRAM mode, the volume up/down/mute
294			keys are synthesized according to changes in the mixer,
295			which uses a single volume up or volume down hotkey
296			press to unmute, as per the ThinkPad volume mixer user
297			interface.  When in ACPI event mode, volume up/down/mute
298			events are reported by the firmware and can behave
299			differently (and that behaviour changes with firmware
300			version -- not just with firmware models -- as well as
301			OSI(Linux) state).
302	
303		hotkey_poll_freq:
304			frequency in Hz for hot key polling. It must be between
305			0 and 25 Hz.  Polling is only carried out when strictly
306			needed.
307	
308			Setting hotkey_poll_freq to zero disables polling, and
309			will cause hot key presses that require NVRAM polling
310			to never be reported.
311	
312			Setting hotkey_poll_freq too low may cause repeated
313			pressings of the same hot key to be misreported as a
314			single key press, or to not even be detected at all.
315			The recommended polling frequency is 10Hz.
316	
317		hotkey_radio_sw:
318			If the ThinkPad has a hardware radio switch, this
319			attribute will read 0 if the switch is in the "radios
320			disabled" position, and 1 if the switch is in the
321			"radios enabled" position.
322	
323			This attribute has poll()/select() support.
324	
325		hotkey_tablet_mode:
326			If the ThinkPad has tablet capabilities, this attribute
327			will read 0 if the ThinkPad is in normal mode, and
328			1 if the ThinkPad is in tablet mode.
329	
330			This attribute has poll()/select() support.
331	
332		wakeup_reason:
333			Set to 1 if the system is waking up because the user
334			requested a bay ejection.  Set to 2 if the system is
335			waking up because the user requested the system to
336			undock.  Set to zero for normal wake-ups or wake-ups
337			due to unknown reasons.
338	
339			This attribute has poll()/select() support.
340	
341		wakeup_hotunplug_complete:
342			Set to 1 if the system was waken up because of an
343			undock or bay ejection request, and that request
344			was successfully completed.  At this point, it might
345			be useful to send the system back to sleep, at the
346			user's choice.  Refer to HKEY events 0x4003 and
347			0x3003, below.
348	
349			This attribute has poll()/select() support.
350	
351	input layer notes:
352	
353	A Hot key is mapped to a single input layer EV_KEY event, possibly
354	followed by an EV_MSC MSC_SCAN event that shall contain that key's scan
355	code.  An EV_SYN event will always be generated to mark the end of the
356	event block.
357	
358	Do not use the EV_MSC MSC_SCAN events to process keys.  They are to be
359	used as a helper to remap keys, only.  They are particularly useful when
360	remapping KEY_UNKNOWN keys.
361	
362	The events are available in an input device, with the following id:
363	
364		Bus:		BUS_HOST
365		vendor:		0x1014 (PCI_VENDOR_ID_IBM)  or
366				0x17aa (PCI_VENDOR_ID_LENOVO)
367		product:	0x5054 ("TP")
368		version:	0x4101
369	
370	The version will have its LSB incremented if the keymap changes in a
371	backwards-compatible way.  The MSB shall always be 0x41 for this input
372	device.  If the MSB is not 0x41, do not use the device as described in
373	this section, as it is either something else (e.g. another input device
374	exported by a thinkpad driver, such as HDAPS) or its functionality has
375	been changed in a non-backwards compatible way.
376	
377	Adding other event types for other functionalities shall be considered a
378	backwards-compatible change for this input device.
379	
380	Thinkpad-acpi Hot Key event map (version 0x4101):
381	
382	ACPI	Scan
383	event	code	Key		Notes
384	
385	0x1001	0x00	FN+F1		-
386	
387	0x1002	0x01	FN+F2		IBM: battery (rare)
388					Lenovo: Screen lock
389	
390	0x1003	0x02	FN+F3		Many IBM models always report
391					this hot key, even with hot keys
392					disabled or with Fn+F3 masked
393					off
394					IBM: screen lock, often turns
395					off the ThinkLight as side-effect
396					Lenovo: battery
397	
398	0x1004	0x03	FN+F4		Sleep button (ACPI sleep button
399					semantics, i.e. sleep-to-RAM).
400					It always generates some kind
401					of event, either the hot key
402					event or an ACPI sleep button
403					event. The firmware may
404					refuse to generate further FN+F4
405					key presses until a S3 or S4 ACPI
406					sleep cycle is performed or some
407					time passes.
408	
409	0x1005	0x04	FN+F5		Radio.  Enables/disables
410					the internal Bluetooth hardware
411					and W-WAN card if left in control
412					of the firmware.  Does not affect
413					the WLAN card.
414					Should be used to turn on/off all
415					radios (Bluetooth+W-WAN+WLAN),
416					really.
417	
418	0x1006	0x05	FN+F6		-
419	
420	0x1007	0x06	FN+F7		Video output cycle.
421					Do you feel lucky today?
422	
423	0x1008	0x07	FN+F8		IBM: toggle screen expand
424					Lenovo: configure UltraNav,
425					or toggle screen expand
426	
427	0x1009	0x08	FN+F9		-
428		..	..		..
429	0x100B	0x0A	FN+F11		-
430	
431	0x100C	0x0B	FN+F12		Sleep to disk.  You are always
432					supposed to handle it yourself,
433					either through the ACPI event,
434					or through a hotkey event.
435					The firmware may refuse to
436					generate further FN+F12 key
437					press events until a S3 or S4
438					ACPI sleep cycle is performed,
439					or some time passes.
440	
441	0x100D	0x0C	FN+BACKSPACE	-
442	0x100E	0x0D	FN+INSERT	-
443	0x100F	0x0E	FN+DELETE	-
444	
445	0x1010	0x0F	FN+HOME		Brightness up.  This key is
446					always handled by the firmware
447					in IBM ThinkPads, even when
448					unmasked.  Just leave it alone.
449					For Lenovo ThinkPads with a new
450					BIOS, it has to be handled either
451					by the ACPI OSI, or by userspace.
452					The driver does the right thing,
453					never mess with this.
454	0x1011	0x10	FN+END		Brightness down.  See brightness
455					up for details.
456	
457	0x1012	0x11	FN+PGUP		ThinkLight toggle.  This key is
458					always handled by the firmware,
459					even when unmasked.
460	
461	0x1013	0x12	FN+PGDOWN	-
462	
463	0x1014	0x13	FN+SPACE	Zoom key
464	
465	0x1015	0x14	VOLUME UP	Internal mixer volume up. This
466					key is always handled by the
467					firmware, even when unmasked.
468					NOTE: Lenovo seems to be changing
469					this.
470	0x1016	0x15	VOLUME DOWN	Internal mixer volume up. This
471					key is always handled by the
472					firmware, even when unmasked.
473					NOTE: Lenovo seems to be changing
474					this.
475	0x1017	0x16	MUTE		Mute internal mixer. This
476					key is always handled by the
477					firmware, even when unmasked.
478	
479	0x1018	0x17	THINKPAD	ThinkPad/Access IBM/Lenovo key
480	
481	0x1019	0x18	unknown
482	..	..	..
483	0x1020	0x1F	unknown
484	
485	The ThinkPad firmware does not allow one to differentiate when most hot
486	keys are pressed or released (either that, or we don't know how to, yet).
487	For these keys, the driver generates a set of events for a key press and
488	immediately issues the same set of events for a key release.  It is
489	unknown by the driver if the ThinkPad firmware triggered these events on
490	hot key press or release, but the firmware will do it for either one, not
491	both.
492	
493	If a key is mapped to KEY_RESERVED, it generates no input events at all.
494	If a key is mapped to KEY_UNKNOWN, it generates an input event that
495	includes an scan code.  If a key is mapped to anything else, it will
496	generate input device EV_KEY events.
497	
498	In addition to the EV_KEY events, thinkpad-acpi may also issue EV_SW
499	events for switches:
500	
501	SW_RFKILL_ALL	T60 and later hardware rfkill rocker switch
502	SW_TABLET_MODE	Tablet ThinkPads HKEY events 0x5009 and 0x500A
503	
504	Non hotkey ACPI HKEY event map:
505	-------------------------------
506	
507	Events that are never propagated by the driver:
508	
509	0x2304		System is waking up from suspend to undock
510	0x2305		System is waking up from suspend to eject bay
511	0x2404		System is waking up from hibernation to undock
512	0x2405		System is waking up from hibernation to eject bay
513	0x5001		Lid closed
514	0x5002		Lid opened
515	0x5009		Tablet swivel: switched to tablet mode
516	0x500A		Tablet swivel: switched to normal mode
517	0x5010		Brightness level changed/control event
518	0x6000		KEYBOARD: Numlock key pressed
519	0x6005		KEYBOARD: Fn key pressed (TO BE VERIFIED)
520	0x7000		Radio Switch may have changed state
521	
522	
523	Events that are propagated by the driver to userspace:
524	
525	0x2313		ALARM: System is waking up from suspend because
526			the battery is nearly empty
527	0x2413		ALARM: System is waking up from hibernation because
528			the battery is nearly empty
529	0x3003		Bay ejection (see 0x2x05) complete, can sleep again
530	0x3006		Bay hotplug request (hint to power up SATA link when
531			the optical drive tray is ejected)
532	0x4003		Undocked (see 0x2x04), can sleep again
533	0x4010		Docked into hotplug port replicator (non-ACPI dock)
534	0x4011		Undocked from hotplug port replicator (non-ACPI dock)
535	0x500B		Tablet pen inserted into its storage bay
536	0x500C		Tablet pen removed from its storage bay
537	0x6011		ALARM: battery is too hot
538	0x6012		ALARM: battery is extremely hot
539	0x6021		ALARM: a sensor is too hot
540	0x6022		ALARM: a sensor is extremely hot
541	0x6030		System thermal table changed
542	0x6040		Nvidia Optimus/AC adapter related (TO BE VERIFIED)
543	
544	Battery nearly empty alarms are a last resort attempt to get the
545	operating system to hibernate or shutdown cleanly (0x2313), or shutdown
546	cleanly (0x2413) before power is lost.  They must be acted upon, as the
547	wake up caused by the firmware will have negated most safety nets...
548	
549	When any of the "too hot" alarms happen, according to Lenovo the user
550	should suspend or hibernate the laptop (and in the case of battery
551	alarms, unplug the AC adapter) to let it cool down.  These alarms do
552	signal that something is wrong, they should never happen on normal
553	operating conditions.
554	
555	The "extremely hot" alarms are emergencies.  According to Lenovo, the
556	operating system is to force either an immediate suspend or hibernate
557	cycle, or a system shutdown.  Obviously, something is very wrong if this
558	happens.
559	
560	
561	Brightness hotkey notes:
562	
563	Don't mess with the brightness hotkeys in a Thinkpad.  If you want
564	notifications for OSD, use the sysfs backlight class event support.
565	
566	The driver will issue KEY_BRIGHTNESS_UP and KEY_BRIGHTNESS_DOWN events
567	automatically for the cases were userspace has to do something to
568	implement brightness changes.  When you override these events, you will
569	either fail to handle properly the ThinkPads that require explicit
570	action to change backlight brightness, or the ThinkPads that require
571	that no action be taken to work properly.
572	
573	
574	Bluetooth
575	---------
576	
577	procfs: /proc/acpi/ibm/bluetooth
578	sysfs device attribute: bluetooth_enable (deprecated)
579	sysfs rfkill class: switch "tpacpi_bluetooth_sw"
580	
581	This feature shows the presence and current state of a ThinkPad
582	Bluetooth device in the internal ThinkPad CDC slot.
583	
584	If the ThinkPad supports it, the Bluetooth state is stored in NVRAM,
585	so it is kept across reboots and power-off.
586	
587	Procfs notes:
588	
589	If Bluetooth is installed, the following commands can be used:
590	
591		echo enable > /proc/acpi/ibm/bluetooth
592		echo disable > /proc/acpi/ibm/bluetooth
593	
594	Sysfs notes:
595	
596		If the Bluetooth CDC card is installed, it can be enabled /
597		disabled through the "bluetooth_enable" thinkpad-acpi device
598		attribute, and its current status can also be queried.
599	
600		enable:
601			0: disables Bluetooth / Bluetooth is disabled
602			1: enables Bluetooth / Bluetooth is enabled.
603	
604		Note: this interface has been superseded by the	generic rfkill
605		class.  It has been deprecated, and it will be removed in year
606		2010.
607	
608		rfkill controller switch "tpacpi_bluetooth_sw": refer to
609		Documentation/rfkill.txt for details.
610	
611	
612	Video output control -- /proc/acpi/ibm/video
613	--------------------------------------------
614	
615	This feature allows control over the devices used for video output -
616	LCD, CRT or DVI (if available). The following commands are available:
617	
618		echo lcd_enable > /proc/acpi/ibm/video
619		echo lcd_disable > /proc/acpi/ibm/video
620		echo crt_enable > /proc/acpi/ibm/video
621		echo crt_disable > /proc/acpi/ibm/video
622		echo dvi_enable > /proc/acpi/ibm/video
623		echo dvi_disable > /proc/acpi/ibm/video
624		echo auto_enable > /proc/acpi/ibm/video
625		echo auto_disable > /proc/acpi/ibm/video
626		echo expand_toggle > /proc/acpi/ibm/video
627		echo video_switch > /proc/acpi/ibm/video
628	
629	NOTE: Access to this feature is restricted to processes owning the
630	CAP_SYS_ADMIN capability for safety reasons, as it can interact badly
631	enough with some versions of X.org to crash it.
632	
633	Each video output device can be enabled or disabled individually.
634	Reading /proc/acpi/ibm/video shows the status of each device.
635	
636	Automatic video switching can be enabled or disabled.  When automatic
637	video switching is enabled, certain events (e.g. opening the lid,
638	docking or undocking) cause the video output device to change
639	automatically. While this can be useful, it also causes flickering
640	and, on the X40, video corruption. By disabling automatic switching,
641	the flickering or video corruption can be avoided.
642	
643	The video_switch command cycles through the available video outputs
644	(it simulates the behavior of Fn-F7).
645	
646	Video expansion can be toggled through this feature. This controls
647	whether the display is expanded to fill the entire LCD screen when a
648	mode with less than full resolution is used. Note that the current
649	video expansion status cannot be determined through this feature.
650	
651	Note that on many models (particularly those using Radeon graphics
652	chips) the X driver configures the video card in a way which prevents
653	Fn-F7 from working. This also disables the video output switching
654	features of this driver, as it uses the same ACPI methods as
655	Fn-F7. Video switching on the console should still work.
656	
657	UPDATE: refer to https://bugs.freedesktop.org/show_bug.cgi?id=2000
658	
659	
660	ThinkLight control
661	------------------
662	
663	procfs: /proc/acpi/ibm/light
664	sysfs attributes: as per LED class, for the "tpacpi::thinklight" LED
665	
666	procfs notes:
667	
668	The ThinkLight status can be read and set through the procfs interface.  A
669	few models which do not make the status available will show the ThinkLight
670	status as "unknown". The available commands are:
671	
672		echo on  > /proc/acpi/ibm/light
673		echo off > /proc/acpi/ibm/light
674	
675	sysfs notes:
676	
677	The ThinkLight sysfs interface is documented by the LED class
678	documentation, in Documentation/leds/leds-class.txt.  The ThinkLight LED name
679	is "tpacpi::thinklight".
680	
681	Due to limitations in the sysfs LED class, if the status of the ThinkLight
682	cannot be read or if it is unknown, thinkpad-acpi will report it as "off".
683	It is impossible to know if the status returned through sysfs is valid.
684	
685	
686	CMOS/UCMS control
687	-----------------
688	
689	procfs: /proc/acpi/ibm/cmos
690	sysfs device attribute: cmos_command
691	
692	This feature is mostly used internally by the ACPI firmware to keep the legacy
693	CMOS NVRAM bits in sync with the current machine state, and to record this
694	state so that the ThinkPad will retain such settings across reboots.
695	
696	Some of these commands actually perform actions in some ThinkPad models, but
697	this is expected to disappear more and more in newer models.  As an example, in
698	a T43 and in a X40, commands 12 and 13 still control the ThinkLight state for
699	real, but commands 0 to 2 don't control the mixer anymore (they have been
700	phased out) and just update the NVRAM.
701	
702	The range of valid cmos command numbers is 0 to 21, but not all have an
703	effect and the behavior varies from model to model.  Here is the behavior
704	on the X40 (tpb is the ThinkPad Buttons utility):
705	
706		0 - Related to "Volume down" key press
707		1 - Related to "Volume up" key press
708		2 - Related to "Mute on" key press
709		3 - Related to "Access IBM" key press
710		4 - Related to "LCD brightness up" key press
711		5 - Related to "LCD brightness down" key press
712		11 - Related to "toggle screen expansion" key press/function
713		12 - Related to "ThinkLight on"
714		13 - Related to "ThinkLight off"
715		14 - Related to "ThinkLight" key press (toggle ThinkLight)
716	
717	The cmos command interface is prone to firmware split-brain problems, as
718	in newer ThinkPads it is just a compatibility layer.  Do not use it, it is
719	exported just as a debug tool.
720	
721	
722	LED control
723	-----------
724	
725	procfs: /proc/acpi/ibm/led
726	sysfs attributes: as per LED class, see below for names
727	
728	Some of the LED indicators can be controlled through this feature.  On
729	some older ThinkPad models, it is possible to query the status of the
730	LED indicators as well.  Newer ThinkPads cannot query the real status
731	of the LED indicators.
732	
733	Because misuse of the LEDs could induce an unaware user to perform
734	dangerous actions (like undocking or ejecting a bay device while the
735	buses are still active), or mask an important alarm (such as a nearly
736	empty battery, or a broken battery), access to most LEDs is
737	restricted.
738	
739	Unrestricted access to all LEDs requires that thinkpad-acpi be
740	compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
741	Distributions must never enable this option.  Individual users that
742	are aware of the consequences are welcome to enabling it.
743	
744	Audio mute and microphone mute LEDs are supported, but currently not
745	visible to userspace. They are used by the snd-hda-intel audio driver.
746	
747	procfs notes:
748	
749	The available commands are:
750	
751		echo '<LED number> on' >/proc/acpi/ibm/led
752		echo '<LED number> off' >/proc/acpi/ibm/led
753		echo '<LED number> blink' >/proc/acpi/ibm/led
754	
755	The <LED number> range is 0 to 15. The set of LEDs that can be
756	controlled varies from model to model. Here is the common ThinkPad
757	mapping:
758	
759		0 - power
760		1 - battery (orange)
761		2 - battery (green)
762		3 - UltraBase/dock
763		4 - UltraBay
764		5 - UltraBase battery slot
765		6 - (unknown)
766		7 - standby
767		8 - dock status 1
768		9 - dock status 2
769		10, 11 - (unknown)
770		12 - thinkvantage
771		13, 14, 15 - (unknown)
772	
773	All of the above can be turned on and off and can be made to blink.
774	
775	sysfs notes:
776	
777	The ThinkPad LED sysfs interface is described in detail by the LED class
778	documentation, in Documentation/leds/leds-class.txt.
779	
780	The LEDs are named (in LED ID order, from 0 to 12):
781	"tpacpi::power", "tpacpi:orange:batt", "tpacpi:green:batt",
782	"tpacpi::dock_active", "tpacpi::bay_active", "tpacpi::dock_batt",
783	"tpacpi::unknown_led", "tpacpi::standby", "tpacpi::dock_status1",
784	"tpacpi::dock_status2", "tpacpi::unknown_led2", "tpacpi::unknown_led3",
785	"tpacpi::thinkvantage".
786	
787	Due to limitations in the sysfs LED class, if the status of the LED
788	indicators cannot be read due to an error, thinkpad-acpi will report it as
789	a brightness of zero (same as LED off).
790	
791	If the thinkpad firmware doesn't support reading the current status,
792	trying to read the current LED brightness will just return whatever
793	brightness was last written to that attribute.
794	
795	These LEDs can blink using hardware acceleration.  To request that a
796	ThinkPad indicator LED should blink in hardware accelerated mode, use the
797	"timer" trigger, and leave the delay_on and delay_off parameters set to
798	zero (to request hardware acceleration autodetection).
799	
800	LEDs that are known not to exist in a given ThinkPad model are not
801	made available through the sysfs interface.  If you have a dock and you
802	notice there are LEDs listed for your ThinkPad that do not exist (and
803	are not in the dock), or if you notice that there are missing LEDs,
804	a report to ibm-acpi-devel@lists.sourceforge.net is appreciated.
805	
806	
807	ACPI sounds -- /proc/acpi/ibm/beep
808	----------------------------------
809	
810	The BEEP method is used internally by the ACPI firmware to provide
811	audible alerts in various situations. This feature allows the same
812	sounds to be triggered manually.
813	
814	The commands are non-negative integer numbers:
815	
816		echo <number> >/proc/acpi/ibm/beep
817	
818	The valid <number> range is 0 to 17. Not all numbers trigger sounds
819	and the sounds vary from model to model. Here is the behavior on the
820	X40:
821	
822		0 - stop a sound in progress (but use 17 to stop 16)
823		2 - two beeps, pause, third beep ("low battery")
824		3 - single beep
825		4 - high, followed by low-pitched beep ("unable")
826		5 - single beep
827		6 - very high, followed by high-pitched beep ("AC/DC")
828		7 - high-pitched beep
829		9 - three short beeps
830		10 - very long beep
831		12 - low-pitched beep
832		15 - three high-pitched beeps repeating constantly, stop with 0
833		16 - one medium-pitched beep repeating constantly, stop with 17
834		17 - stop 16
835	
836	
837	Temperature sensors
838	-------------------
839	
840	procfs: /proc/acpi/ibm/thermal
841	sysfs device attributes: (hwmon "thinkpad") temp*_input
842	
843	Most ThinkPads include six or more separate temperature sensors but only
844	expose the CPU temperature through the standard ACPI methods.  This
845	feature shows readings from up to eight different sensors on older
846	ThinkPads, and up to sixteen different sensors on newer ThinkPads.
847	
848	For example, on the X40, a typical output may be:
849	temperatures:   42 42 45 41 36 -128 33 -128
850	
851	On the T43/p, a typical output may be:
852	temperatures:   48 48 36 52 38 -128 31 -128 48 52 48 -128 -128 -128 -128 -128
853	
854	The mapping of thermal sensors to physical locations varies depending on
855	system-board model (and thus, on ThinkPad model).
856	
857	http://thinkwiki.org/wiki/Thermal_Sensors is a public wiki page that
858	tries to track down these locations for various models.
859	
860	Most (newer?) models seem to follow this pattern:
861	
862	1:  CPU
863	2:  (depends on model)
864	3:  (depends on model)
865	4:  GPU
866	5:  Main battery: main sensor
867	6:  Bay battery: main sensor
868	7:  Main battery: secondary sensor
869	8:  Bay battery: secondary sensor
870	9-15: (depends on model)
871	
872	For the R51 (source: Thomas Gruber):
873	2:  Mini-PCI
874	3:  Internal HDD
875	
876	For the T43, T43/p (source: Shmidoax/Thinkwiki.org)
877	http://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_T43.2C_T43p
878	2:  System board, left side (near PCMCIA slot), reported as HDAPS temp
879	3:  PCMCIA slot
880	9:  MCH (northbridge) to DRAM Bus
881	10: Clock-generator, mini-pci card and ICH (southbridge), under Mini-PCI
882	    card, under touchpad
883	11: Power regulator, underside of system board, below F2 key
884	
885	The A31 has a very atypical layout for the thermal sensors
886	(source: Milos Popovic, http://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_A31)
887	1:  CPU
888	2:  Main Battery: main sensor
889	3:  Power Converter
890	4:  Bay Battery: main sensor
891	5:  MCH (northbridge)
892	6:  PCMCIA/ambient
893	7:  Main Battery: secondary sensor
894	8:  Bay Battery: secondary sensor
895	
896	
897	Procfs notes:
898		Readings from sensors that are not available return -128.
899		No commands can be written to this file.
900	
901	Sysfs notes:
902		Sensors that are not available return the ENXIO error.  This
903		status may change at runtime, as there are hotplug thermal
904		sensors, like those inside the batteries and docks.
905	
906		thinkpad-acpi thermal sensors are reported through the hwmon
907		subsystem, and follow all of the hwmon guidelines at
908		Documentation/hwmon.
909	
910	EXPERIMENTAL: Embedded controller register dump
911	-----------------------------------------------
912	
913	This feature is not included in the thinkpad driver anymore.
914	Instead the EC can be accessed through /sys/kernel/debug/ec with
915	a userspace tool which can be found here:
916	ftp://ftp.suse.com/pub/people/trenn/sources/ec
917	
918	Use it to determine the register holding the fan
919	speed on some models. To do that, do the following:
920		- make sure the battery is fully charged
921		- make sure the fan is running
922		- use above mentioned tool to read out the EC
923	
924	Often fan and temperature values vary between
925	readings. Since temperatures don't change vary fast, you can take
926	several quick dumps to eliminate them.
927	
928	You can use a similar method to figure out the meaning of other
929	embedded controller registers - e.g. make sure nothing else changes
930	except the charging or discharging battery to determine which
931	registers contain the current battery capacity, etc. If you experiment
932	with this, do send me your results (including some complete dumps with
933	a description of the conditions when they were taken.)
934	
935	
936	LCD brightness control
937	----------------------
938	
939	procfs: /proc/acpi/ibm/brightness
940	sysfs backlight device "thinkpad_screen"
941	
942	This feature allows software control of the LCD brightness on ThinkPad
943	models which don't have a hardware brightness slider.
944	
945	It has some limitations: the LCD backlight cannot be actually turned
946	on or off by this interface, it just controls the backlight brightness
947	level.
948	
949	On IBM (and some of the earlier Lenovo) ThinkPads, the backlight control
950	has eight brightness levels, ranging from 0 to 7.  Some of the levels
951	may not be distinct.  Later Lenovo models that implement the ACPI
952	display backlight brightness control methods have 16 levels, ranging
953	from 0 to 15.
954	
955	For IBM ThinkPads, there are two interfaces to the firmware for direct
956	brightness control, EC and UCMS (or CMOS).  To select which one should be
957	used, use the brightness_mode module parameter: brightness_mode=1 selects
958	EC mode, brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
959	mode with NVRAM backing (so that brightness changes are remembered across
960	shutdown/reboot).
961	
962	The driver tries to select which interface to use from a table of
963	defaults for each ThinkPad model.  If it makes a wrong choice, please
964	report this as a bug, so that we can fix it.
965	
966	Lenovo ThinkPads only support brightness_mode=2 (UCMS).
967	
968	When display backlight brightness controls are available through the
969	standard ACPI interface, it is best to use it instead of this direct
970	ThinkPad-specific interface.  The driver will disable its native
971	backlight brightness control interface if it detects that the standard
972	ACPI interface is available in the ThinkPad.
973	
974	If you want to use the thinkpad-acpi backlight brightness control
975	instead of the generic ACPI video backlight brightness control for some
976	reason, you should use the acpi_backlight=vendor kernel parameter.
977	
978	The brightness_enable module parameter can be used to control whether
979	the LCD brightness control feature will be enabled when available.
980	brightness_enable=0 forces it to be disabled.  brightness_enable=1
981	forces it to be enabled when available, even if the standard ACPI
982	interface is also available.
983	
984	Procfs notes:
985	
986		The available commands are:
987	
988		echo up   >/proc/acpi/ibm/brightness
989		echo down >/proc/acpi/ibm/brightness
990		echo 'level <level>' >/proc/acpi/ibm/brightness
991	
992	Sysfs notes:
993	
994	The interface is implemented through the backlight sysfs class, which is
995	poorly documented at this time.
996	
997	Locate the thinkpad_screen device under /sys/class/backlight, and inside
998	it there will be the following attributes:
999	
1000		max_brightness:
1001			Reads the maximum brightness the hardware can be set to.
1002			The minimum is always zero.
1003	
1004		actual_brightness:
1005			Reads what brightness the screen is set to at this instant.
1006	
1007		brightness:
1008			Writes request the driver to change brightness to the
1009			given value.  Reads will tell you what brightness the
1010			driver is trying to set the display to when "power" is set
1011			to zero and the display has not been dimmed by a kernel
1012			power management event.
1013	
1014		power:
1015			power management mode, where 0 is "display on", and 1 to 3
1016			will dim the display backlight to brightness level 0
1017			because thinkpad-acpi cannot really turn the backlight
1018			off.  Kernel power management events can temporarily
1019			increase the current power management level, i.e. they can
1020			dim the display.
1021	
1022	
1023	WARNING:
1024	
1025	    Whatever you do, do NOT ever call thinkpad-acpi backlight-level change
1026	    interface and the ACPI-based backlight level change interface
1027	    (available on newer BIOSes, and driven by the Linux ACPI video driver)
1028	    at the same time.  The two will interact in bad ways, do funny things,
1029	    and maybe reduce the life of the backlight lamps by needlessly kicking
1030	    its level up and down at every change.
1031	
1032	
1033	Volume control (Console Audio control)
1034	--------------------------------------
1035	
1036	procfs: /proc/acpi/ibm/volume
1037	ALSA: "ThinkPad Console Audio Control", default ID: "ThinkPadEC"
1038	
1039	NOTE: by default, the volume control interface operates in read-only
1040	mode, as it is supposed to be used for on-screen-display purposes.
1041	The read/write mode can be enabled through the use of the
1042	"volume_control=1" module parameter.
1043	
1044	NOTE: distros are urged to not enable volume_control by default, this
1045	should be done by the local admin only.  The ThinkPad UI is for the
1046	console audio control to be done through the volume keys only, and for
1047	the desktop environment to just provide on-screen-display feedback.
1048	Software volume control should be done only in the main AC97/HDA
1049	mixer.
1050	
1051	
1052	About the ThinkPad Console Audio control:
1053	
1054	ThinkPads have a built-in amplifier and muting circuit that drives the
1055	console headphone and speakers.  This circuit is after the main AC97
1056	or HDA mixer in the audio path, and under exclusive control of the
1057	firmware.
1058	
1059	ThinkPads have three special hotkeys to interact with the console
1060	audio control: volume up, volume down and mute.
1061	
1062	It is worth noting that the normal way the mute function works (on
1063	ThinkPads that do not have a "mute LED") is:
1064	
1065	1. Press mute to mute.  It will *always* mute, you can press it as
1066	   many times as you want, and the sound will remain mute.
1067	
1068	2. Press either volume key to unmute the ThinkPad (it will _not_
1069	   change the volume, it will just unmute).
1070	
1071	This is a very superior design when compared to the cheap software-only
1072	mute-toggle solution found on normal consumer laptops:  you can be
1073	absolutely sure the ThinkPad will not make noise if you press the mute
1074	button, no matter the previous state.
1075	
1076	The IBM ThinkPads, and the earlier Lenovo ThinkPads have variable-gain
1077	amplifiers driving the speakers and headphone output, and the firmware
1078	also handles volume control for the headphone and speakers on these
1079	ThinkPads without any help from the operating system (this volume
1080	control stage exists after the main AC97 or HDA mixer in the audio
1081	path).
1082	
1083	The newer Lenovo models only have firmware mute control, and depend on
1084	the main HDA mixer to do volume control (which is done by the operating
1085	system).  In this case, the volume keys are filtered out for unmute
1086	key press (there are some firmware bugs in this area) and delivered as
1087	normal key presses to the operating system (thinkpad-acpi is not
1088	involved).
1089	
1090	
1091	The ThinkPad-ACPI volume control:
1092	
1093	The preferred way to interact with the Console Audio control is the
1094	ALSA interface.
1095	
1096	The legacy procfs interface allows one to read the current state,
1097	and if volume control is enabled, accepts the following commands:
1098	
1099		echo up   >/proc/acpi/ibm/volume
1100		echo down >/proc/acpi/ibm/volume
1101		echo mute >/proc/acpi/ibm/volume
1102		echo unmute >/proc/acpi/ibm/volume
1103		echo 'level <level>' >/proc/acpi/ibm/volume
1104	
1105	The <level> number range is 0 to 14 although not all of them may be
1106	distinct. To unmute the volume after the mute command, use either the
1107	up or down command (the level command will not unmute the volume), or
1108	the unmute command.
1109	
1110	You can use the volume_capabilities parameter to tell the driver
1111	whether your thinkpad has volume control or mute-only control:
1112	volume_capabilities=1 for mixers with mute and volume control,
1113	volume_capabilities=2 for mixers with only mute control.
1114	
1115	If the driver misdetects the capabilities for your ThinkPad model,
1116	please report this to ibm-acpi-devel@lists.sourceforge.net, so that we
1117	can update the driver.
1118	
1119	There are two strategies for volume control.  To select which one
1120	should be used, use the volume_mode module parameter: volume_mode=1
1121	selects EC mode, and volume_mode=3 selects EC mode with NVRAM backing
1122	(so that volume/mute changes are remembered across shutdown/reboot).
1123	
1124	The driver will operate in volume_mode=3 by default. If that does not
1125	work well on your ThinkPad model, please report this to
1126	ibm-acpi-devel@lists.sourceforge.net.
1127	
1128	The driver supports the standard ALSA module parameters.  If the ALSA
1129	mixer is disabled, the driver will disable all volume functionality.
1130	
1131	
1132	Fan control and monitoring: fan speed, fan enable/disable
1133	---------------------------------------------------------
1134	
1135	procfs: /proc/acpi/ibm/fan
1136	sysfs device attributes: (hwmon "thinkpad") fan1_input, pwm1,
1137				  pwm1_enable, fan2_input
1138	sysfs hwmon driver attributes: fan_watchdog
1139	
1140	NOTE NOTE NOTE: fan control operations are disabled by default for
1141	safety reasons.  To enable them, the module parameter "fan_control=1"
1142	must be given to thinkpad-acpi.
1143	
1144	This feature attempts to show the current fan speed, control mode and
1145	other fan data that might be available.  The speed is read directly
1146	from the hardware registers of the embedded controller.  This is known
1147	to work on later R, T, X and Z series ThinkPads but may show a bogus
1148	value on other models.
1149	
1150	Some Lenovo ThinkPads support a secondary fan.  This fan cannot be
1151	controlled separately, it shares the main fan control.
1152	
1153	Fan levels:
1154	
1155	Most ThinkPad fans work in "levels" at the firmware interface.  Level 0
1156	stops the fan.  The higher the level, the higher the fan speed, although
1157	adjacent levels often map to the same fan speed.  7 is the highest
1158	level, where the fan reaches the maximum recommended speed.
1159	
1160	Level "auto" means the EC changes the fan level according to some
1161	internal algorithm, usually based on readings from the thermal sensors.
1162	
1163	There is also a "full-speed" level, also known as "disengaged" level.
1164	In this level, the EC disables the speed-locked closed-loop fan control,
1165	and drives the fan as fast as it can go, which might exceed hardware
1166	limits, so use this level with caution.
1167	
1168	The fan usually ramps up or down slowly from one speed to another, and
1169	it is normal for the EC to take several seconds to react to fan
1170	commands.  The full-speed level may take up to two minutes to ramp up to
1171	maximum speed, and in some ThinkPads, the tachometer readings go stale
1172	while the EC is transitioning to the full-speed level.
1173	
1174	WARNING WARNING WARNING: do not leave the fan disabled unless you are
1175	monitoring all of the temperature sensor readings and you are ready to
1176	enable it if necessary to avoid overheating.
1177	
1178	An enabled fan in level "auto" may stop spinning if the EC decides the
1179	ThinkPad is cool enough and doesn't need the extra airflow.  This is
1180	normal, and the EC will spin the fan up if the various thermal readings
1181	rise too much.
1182	
1183	On the X40, this seems to depend on the CPU and HDD temperatures.
1184	Specifically, the fan is turned on when either the CPU temperature
1185	climbs to 56 degrees or the HDD temperature climbs to 46 degrees.  The
1186	fan is turned off when the CPU temperature drops to 49 degrees and the
1187	HDD temperature drops to 41 degrees.  These thresholds cannot
1188	currently be controlled.
1189	
1190	The ThinkPad's ACPI DSDT code will reprogram the fan on its own when
1191	certain conditions are met.  It will override any fan programming done
1192	through thinkpad-acpi.
1193	
1194	The thinkpad-acpi kernel driver can be programmed to revert the fan
1195	level to a safe setting if userspace does not issue one of the procfs
1196	fan commands: "enable", "disable", "level" or "watchdog", or if there
1197	are no writes to pwm1_enable (or to pwm1 *if and only if* pwm1_enable is
1198	set to 1, manual mode) within a configurable amount of time of up to
1199	120 seconds.  This functionality is called fan safety watchdog.
1200	
1201	Note that the watchdog timer stops after it enables the fan.  It will be
1202	rearmed again automatically (using the same interval) when one of the
1203	above mentioned fan commands is received.  The fan watchdog is,
1204	therefore, not suitable to protect against fan mode changes made through
1205	means other than the "enable", "disable", and "level" procfs fan
1206	commands, or the hwmon fan control sysfs interface.
1207	
1208	Procfs notes:
1209	
1210	The fan may be enabled or disabled with the following commands:
1211	
1212		echo enable  >/proc/acpi/ibm/fan
1213		echo disable >/proc/acpi/ibm/fan
1214	
1215	Placing a fan on level 0 is the same as disabling it.  Enabling a fan
1216	will try to place it in a safe level if it is too slow or disabled.
1217	
1218	The fan level can be controlled with the command:
1219	
1220		echo 'level <level>' > /proc/acpi/ibm/fan
1221	
1222	Where <level> is an integer from 0 to 7, or one of the words "auto" or
1223	"full-speed" (without the quotes).  Not all ThinkPads support the "auto"
1224	and "full-speed" levels.  The driver accepts "disengaged" as an alias for
1225	"full-speed", and reports it as "disengaged" for backwards
1226	compatibility.
1227	
1228	On the X31 and X40 (and ONLY on those models), the fan speed can be
1229	controlled to a certain degree.  Once the fan is running, it can be
1230	forced to run faster or slower with the following command:
1231	
1232		echo 'speed <speed>' > /proc/acpi/ibm/fan
1233	
1234	The sustainable range of fan speeds on the X40 appears to be from about
1235	3700 to about 7350. Values outside this range either do not have any
1236	effect or the fan speed eventually settles somewhere in that range.  The
1237	fan cannot be stopped or started with this command.  This functionality
1238	is incomplete, and not available through the sysfs interface.
1239	
1240	To program the safety watchdog, use the "watchdog" command.
1241	
1242		echo 'watchdog <interval in seconds>' > /proc/acpi/ibm/fan
1243	
1244	If you want to disable the watchdog, use 0 as the interval.
1245	
1246	Sysfs notes:
1247	
1248	The sysfs interface follows the hwmon subsystem guidelines for the most
1249	part, and the exception is the fan safety watchdog.
1250	
1251	Writes to any of the sysfs attributes may return the EINVAL error if
1252	that operation is not supported in a given ThinkPad or if the parameter
1253	is out-of-bounds, and EPERM if it is forbidden.  They may also return
1254	EINTR (interrupted system call), and EIO (I/O error while trying to talk
1255	to the firmware).
1256	
1257	Features not yet implemented by the driver return ENOSYS.
1258	
1259	hwmon device attribute pwm1_enable:
1260		0: PWM offline (fan is set to full-speed mode)
1261		1: Manual PWM control (use pwm1 to set fan level)
1262		2: Hardware PWM control (EC "auto" mode)
1263		3: reserved (Software PWM control, not implemented yet)
1264	
1265		Modes 0 and 2 are not supported by all ThinkPads, and the
1266		driver is not always able to detect this.  If it does know a
1267		mode is unsupported, it will return -EINVAL.
1268	
1269	hwmon device attribute pwm1:
1270		Fan level, scaled from the firmware values of 0-7 to the hwmon
1271		scale of 0-255.  0 means fan stopped, 255 means highest normal
1272		speed (level 7).
1273	
1274		This attribute only commands the fan if pmw1_enable is set to 1
1275		(manual PWM control).
1276	
1277	hwmon device attribute fan1_input:
1278		Fan tachometer reading, in RPM.  May go stale on certain
1279		ThinkPads while the EC transitions the PWM to offline mode,
1280		which can take up to two minutes.  May return rubbish on older
1281		ThinkPads.
1282	
1283	hwmon device attribute fan2_input:
1284		Fan tachometer reading, in RPM, for the secondary fan.
1285		Available only on some ThinkPads.  If the secondary fan is
1286		not installed, will always read 0.
1287	
1288	hwmon driver attribute fan_watchdog:
1289		Fan safety watchdog timer interval, in seconds.  Minimum is
1290		1 second, maximum is 120 seconds.  0 disables the watchdog.
1291	
1292	To stop the fan: set pwm1 to zero, and pwm1_enable to 1.
1293	
1294	To start the fan in a safe mode: set pwm1_enable to 2.  If that fails
1295	with EINVAL, try to set pwm1_enable to 1 and pwm1 to at least 128 (255
1296	would be the safest choice, though).
1297	
1298	
1299	WAN
1300	---
1301	
1302	procfs: /proc/acpi/ibm/wan
1303	sysfs device attribute: wwan_enable (deprecated)
1304	sysfs rfkill class: switch "tpacpi_wwan_sw"
1305	
1306	This feature shows the presence and current state of the built-in
1307	Wireless WAN device.
1308	
1309	If the ThinkPad supports it, the WWAN state is stored in NVRAM,
1310	so it is kept across reboots and power-off.
1311	
1312	It was tested on a Lenovo ThinkPad X60. It should probably work on other
1313	ThinkPad models which come with this module installed.
1314	
1315	Procfs notes:
1316	
1317	If the W-WAN card is installed, the following commands can be used:
1318	
1319		echo enable > /proc/acpi/ibm/wan
1320		echo disable > /proc/acpi/ibm/wan
1321	
1322	Sysfs notes:
1323	
1324		If the W-WAN card is installed, it can be enabled /
1325		disabled through the "wwan_enable" thinkpad-acpi device
1326		attribute, and its current status can also be queried.
1327	
1328		enable:
1329			0: disables WWAN card / WWAN card is disabled
1330			1: enables WWAN card / WWAN card is enabled.
1331	
1332		Note: this interface has been superseded by the	generic rfkill
1333		class.  It has been deprecated, and it will be removed in year
1334		2010.
1335	
1336		rfkill controller switch "tpacpi_wwan_sw": refer to
1337		Documentation/rfkill.txt for details.
1338	
1339	
1340	EXPERIMENTAL: UWB
1341	-----------------
1342	
1343	This feature is considered EXPERIMENTAL because it has not been extensively
1344	tested and validated in various ThinkPad models yet.  The feature may not
1345	work as expected. USE WITH CAUTION! To use this feature, you need to supply
1346	the experimental=1 parameter when loading the module.
1347	
1348	sysfs rfkill class: switch "tpacpi_uwb_sw"
1349	
1350	This feature exports an rfkill controller for the UWB device, if one is
1351	present and enabled in the BIOS.
1352	
1353	Sysfs notes:
1354	
1355		rfkill controller switch "tpacpi_uwb_sw": refer to
1356		Documentation/rfkill.txt for details.
1357	
1358	
1359	Multiple Commands, Module Parameters
1360	------------------------------------
1361	
1362	Multiple commands can be written to the proc files in one shot by
1363	separating them with commas, for example:
1364	
1365		echo enable,0xffff > /proc/acpi/ibm/hotkey
1366		echo lcd_disable,crt_enable > /proc/acpi/ibm/video
1367	
1368	Commands can also be specified when loading the thinkpad-acpi module,
1369	for example:
1370	
1371		modprobe thinkpad_acpi hotkey=enable,0xffff video=auto_disable
1372	
1373	
1374	Enabling debugging output
1375	-------------------------
1376	
1377	The module takes a debug parameter which can be used to selectively
1378	enable various classes of debugging output, for example:
1379	
1380		 modprobe thinkpad_acpi debug=0xffff
1381	
1382	will enable all debugging output classes.  It takes a bitmask, so
1383	to enable more than one output class, just add their values.
1384	
1385		Debug bitmask		Description
1386		0x8000			Disclose PID of userspace programs
1387					accessing some functions of the driver
1388		0x0001			Initialization and probing
1389		0x0002			Removal
1390		0x0004			RF Transmitter control (RFKILL)
1391					(bluetooth, WWAN, UWB...)
1392		0x0008			HKEY event interface, hotkeys
1393		0x0010			Fan control
1394		0x0020			Backlight brightness
1395		0x0040			Audio mixer/volume control
1396	
1397	There is also a kernel build option to enable more debugging
1398	information, which may be necessary to debug driver problems.
1399	
1400	The level of debugging information output by the driver can be changed
1401	at runtime through sysfs, using the driver attribute debug_level.  The
1402	attribute takes the same bitmask as the debug module parameter above.
1403	
1404	
1405	Force loading of module
1406	-----------------------
1407	
1408	If thinkpad-acpi refuses to detect your ThinkPad, you can try to specify
1409	the module parameter force_load=1.  Regardless of whether this works or
1410	not, please contact ibm-acpi-devel@lists.sourceforge.net with a report.
1411	
1412	
1413	Sysfs interface changelog:
1414	
1415	0x000100:	Initial sysfs support, as a single platform driver and
1416			device.
1417	0x000200:	Hot key support for 32 hot keys, and radio slider switch
1418			support.
1419	0x010000:	Hot keys are now handled by default over the input
1420			layer, the radio switch generates input event EV_RADIO,
1421			and the driver enables hot key handling by default in
1422			the firmware.
1423	
1424	0x020000:	ABI fix: added a separate hwmon platform device and
1425			driver, which must be located by name (thinkpad)
1426			and the hwmon class for libsensors4 (lm-sensors 3)
1427			compatibility.  Moved all hwmon attributes to this
1428			new platform device.
1429	
1430	0x020100:	Marker for thinkpad-acpi with hot key NVRAM polling
1431			support.  If you must, use it to know you should not
1432			start a userspace NVRAM poller (allows to detect when
1433			NVRAM is compiled out by the user because it is
1434			unneeded/undesired in the first place).
1435	0x020101:	Marker for thinkpad-acpi with hot key NVRAM polling
1436			and proper hotkey_mask semantics (version 8 of the
1437			NVRAM polling patch).  Some development snapshots of
1438			0.18 had an earlier version that did strange things
1439			to hotkey_mask.
1440	
1441	0x020200:	Add poll()/select() support to the following attributes:
1442			hotkey_radio_sw, wakeup_hotunplug_complete, wakeup_reason
1443	
1444	0x020300:	hotkey enable/disable support removed, attributes
1445			hotkey_bios_enabled and hotkey_enable deprecated and
1446			marked for removal.
1447	
1448	0x020400:	Marker for 16 LEDs support.  Also, LEDs that are known
1449			to not exist in a given model are not registered with
1450			the LED sysfs class anymore.
1451	
1452	0x020500:	Updated hotkey driver, hotkey_mask is always available
1453			and it is always able to disable hot keys.  Very old
1454			thinkpads are properly supported.  hotkey_bios_mask
1455			is deprecated and marked for removal.
1456	
1457	0x020600:	Marker for backlight change event support.
1458	
1459	0x020700:	Support for mute-only mixers.
1460			Volume control in read-only mode by default.
1461			Marker for ALSA mixer support.
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