[PATCH] kprobes: function-return probes

[linux.git] / Documentation / ibm-acpi.txt

		    IBM ThinkPad ACPI Extras Driver

                            Version 0.8
                          8 November 2004

               Borislav Deianov <[email protected]>
		      http://ibm-acpi.sf.net/


This is a Linux ACPI driver for the IBM ThinkPad laptops. It aims to
support various features of these laptops which are accessible through
the ACPI framework but not otherwise supported by the generic Linux
ACPI drivers.


Status
------

The features currently supported are the following (see below for
detailed description):

	- Fn key combinations
	- Bluetooth enable and disable
	- video output switching, expansion control	
	- ThinkLight on and off
	- limited docking and undocking
	- UltraBay eject
	- Experimental: CMOS control
	- Experimental: LED control
	- Experimental: ACPI sounds

A compatibility table by model and feature is maintained on the web
site, http://ibm-acpi.sf.net/. I appreciate any success or failure
reports, especially if they add to or correct the compatibility table.
Please include the following information in your report:

	- ThinkPad model name
	- a copy of your DSDT, from /proc/acpi/dsdt
	- which driver features work and which don't
	- the observed behavior of non-working features

Any other comments or patches are also more than welcome.


Installation
------------

If you are compiling this driver as included in the Linux kernel
sources, simply enable the CONFIG_ACPI_IBM option (Power Management /
ACPI / IBM ThinkPad Laptop Extras). The rest of this section describes
how to install this driver when downloaded from the web site.

First, you need to get a kernel with ACPI support up and running.
Please refer to http://acpi.sourceforge.net/ for help with this
step. How successful you will be depends a lot on you ThinkPad model,
the kernel you are using and any additional patches applied. The
kernel provided with your distribution may not be good enough. I
needed to compile a 2.6.7 kernel with the 20040715 ACPI patch to get
ACPI working reliably on my ThinkPad X40. Old ThinkPad models may not
be supported at all.

Assuming you have the basic ACPI support working (e.g. you can see the
/proc/acpi directory), follow the following steps to install this
driver:

	- unpack the archive:

		tar xzvf ibm-acpi-x.y.tar.gz; cd ibm-acpi-x.y

	- compile the driver:

		make

	- install the module in your kernel modules directory:

		make install

	- load the module:

		modprobe ibm_acpi

After loading the module, check the "dmesg" output for any error messages.


Features
--------

The driver creates the /proc/acpi/ibm directory. There is a file under
that directory for each feature described below. Note that while the
driver is still in the alpha stage, the exact proc file format and
commands supported by the various features is guaranteed to change
frequently.

Driver Version -- /proc/acpi/ibm/driver
--------------------------------------

The driver name and version. No commands can be written to this file.

Hot Keys -- /proc/acpi/ibm/hotkey
---------------------------------

Without this driver, only the Fn-F4 key (sleep button) generates an
ACPI event. With the driver loaded, the hotkey feature enabled and the
mask set (see below), the various hot keys generate ACPI events in the
following format:

	ibm/hotkey HKEY 00000080 0000xxxx

The last four digits vary depending on the key combination pressed.
All labeled Fn-Fx key combinations generate distinct events. In
addition, the lid microswitch and some docking station buttons may
also generate such events.

The following commands can be written to this file:

	echo enable > /proc/acpi/ibm/hotkey -- enable the hot keys feature
	echo disable > /proc/acpi/ibm/hotkey -- disable the hot keys feature
	echo 0xffff > /proc/acpi/ibm/hotkey -- enable all possible hot keys
	echo 0x0000 > /proc/acpi/ibm/hotkey -- disable all possible hot keys
	... any other 4-hex-digit mask ...
	echo reset > /proc/acpi/ibm/hotkey -- restore the original mask

The bit mask allows some control over which hot keys generate ACPI
events. Not all bits in the mask can be modified. Not all bits that
can be modified do anything. Not all hot keys can be individually
controlled by the mask. Most recent ThinkPad models honor the
following bits (assuming the hot keys feature has been enabled):

	key	bit	behavior when set	behavior when unset

	Fn-F3			always generates ACPI event
	Fn-F4			always generates ACPI event
	Fn-F5	0010	generate ACPI event	enable/disable Bluetooth
	Fn-F7	0040	generate ACPI event	switch LCD and external display
	Fn-F8	0080	generate ACPI event	expand screen or none
	Fn-F9	0100	generate ACPI event	none
	Fn-F12			always generates ACPI event

Some models do not support all of the above. For example, the T30 does
not support Fn-F5 and Fn-F9. Other models do not support the mask at
all. On those models, hot keys cannot be controlled individually.

Note that enabling ACPI events for some keys prevents their default
behavior. For example, if events for Fn-F5 are enabled, that key will
no longer enable/disable Bluetooth by itself. This can still be done
from an acpid handler for the ibm/hotkey event.

Note also that not all Fn key combinations are supported through
ACPI. For example, on the X40, the brightness, volume and "Access IBM"
buttons do not generate ACPI events even with this driver. They *can*
be used through the "ThinkPad Buttons" utility, see
http://www.nongnu.org/tpb/

Bluetooth -- /proc/acpi/ibm/bluetooth
-------------------------------------

This feature shows the presence and current state of a Bluetooth
device. If Bluetooth is installed, the following commands can be used:

	echo enable > /proc/acpi/ibm/bluetooth
	echo disable > /proc/acpi/ibm/bluetooth

Video output control -- /proc/acpi/ibm/video
--------------------------------------------

This feature allows control over the devices used for video output -
LCD, CRT or DVI (if available). The following commands are available:

	echo lcd_enable > /proc/acpi/ibm/video
	echo lcd_disable > /proc/acpi/ibm/video
	echo crt_enable > /proc/acpi/ibm/video
	echo crt_disable > /proc/acpi/ibm/video
	echo dvi_enable > /proc/acpi/ibm/video
	echo dvi_disable > /proc/acpi/ibm/video
	echo auto_enable > /proc/acpi/ibm/video
	echo auto_disable > /proc/acpi/ibm/video
	echo expand_toggle > /proc/acpi/ibm/video
	echo video_switch > /proc/acpi/ibm/video

Each video output device can be enabled or disabled individually.
Reading /proc/acpi/ibm/video shows the status of each device.

Automatic video switching can be enabled or disabled.  When automatic
video switching is enabled, certain events (e.g. opening the lid,
docking or undocking) cause the video output device to change
automatically. While this can be useful, it also causes flickering
and, on the X40, video corruption. By disabling automatic switching,
the flickering or video corruption can be avoided.

The video_switch command cycles through the available video outputs
(it sumulates the behavior of Fn-F7).

Video expansion can be toggled through this feature. This controls
whether the display is expanded to fill the entire LCD screen when a
mode with less than full resolution is used. Note that the current
video expansion status cannot be determined through this feature.

Note that on many models (particularly those using Radeon graphics
chips) the X driver configures the video card in a way which prevents
Fn-F7 from working. This also disables the video output switching
features of this driver, as it uses the same ACPI methods as
Fn-F7. Video switching on the console should still work.

ThinkLight control -- /proc/acpi/ibm/light
------------------------------------------

The current status of the ThinkLight can be found in this file. A few
models which do not make the status available will show it as
"unknown". The available commands are:

	echo on  > /proc/acpi/ibm/light
	echo off > /proc/acpi/ibm/light

Docking / Undocking -- /proc/acpi/ibm/dock
------------------------------------------

Docking and undocking (e.g. with the X4 UltraBase) requires some
actions to be taken by the operating system to safely make or break
the electrical connections with the dock.

The docking feature of this driver generates the following ACPI events:

	ibm/dock GDCK 00000003 00000001 -- eject request
	ibm/dock GDCK 00000003 00000002 -- undocked
	ibm/dock GDCK 00000000 00000003 -- docked

NOTE: These events will only be generated if the laptop was docked
when originally booted. This is due to the current lack of support for
hot plugging of devices in the Linux ACPI framework. If the laptop was
booted while not in the dock, the following message is shown in the
logs: "ibm_acpi: dock device not present". No dock-related events are
generated but the dock and undock commands described below still
work. They can be executed manually or triggered by Fn key
combinations (see the example acpid configuration files included in
the driver tarball package available on the web site).

When the eject request button on the dock is pressed, the first event
above is generated. The handler for this event should issue the
following command:

	echo undock > /proc/acpi/ibm/dock

After the LED on the dock goes off, it is safe to eject the laptop.
Note: if you pressed this key by mistake, go ahead and eject the
laptop, then dock it back in. Otherwise, the dock may not function as
expected.

When the laptop is docked, the third event above is generated. The
handler for this event should issue the following command to fully
enable the dock:

	echo dock > /proc/acpi/ibm/dock

The contents of the /proc/acpi/ibm/dock file shows the current status
of the dock, as provided by the ACPI framework.

The docking support in this driver does not take care of enabling or
disabling any other devices you may have attached to the dock. For
example, a CD drive plugged into the UltraBase needs to be disabled or
enabled separately. See the provided example acpid configuration files
for how this can be accomplished.

There is no support yet for PCI devices that may be attached to a
docking station, e.g. in the ThinkPad Dock II. The driver currently
does not recognize, enable or disable such devices. This means that
the only docking stations currently supported are the X-series
UltraBase docks and "dumb" port replicators like the Mini Dock (the
latter don't need any ACPI support, actually).

UltraBay Eject -- /proc/acpi/ibm/bay
------------------------------------

Inserting or ejecting an UltraBay device requires some actions to be
taken by the operating system to safely make or break the electrical
connections with the device.

This feature generates the following ACPI events:

	ibm/bay MSTR 00000003 00000000 -- eject request
	ibm/bay MSTR 00000001 00000000 -- eject lever inserted

NOTE: These events will only be generated if the UltraBay was present
when the laptop was originally booted (on the X series, the UltraBay
is in the dock, so it may not be present if the laptop was undocked).
This is due to the current lack of support for hot plugging of devices
in the Linux ACPI framework. If the laptop was booted without the
UltraBay, the following message is shown in the logs: "ibm_acpi: bay
device not present". No bay-related events are generated but the eject
command described below still works. It can be executed manually or
triggered by a hot key combination.

Sliding the eject lever generates the first event shown above. The
handler for this event should take whatever actions are necessary to
shut down the device in the UltraBay (e.g. call idectl), then issue
the following command:

	echo eject > /proc/acpi/ibm/bay

After the LED on the UltraBay goes off, it is safe to pull out the
device.

When the eject lever is inserted, the second event above is
generated. The handler for this event should take whatever actions are
necessary to enable the UltraBay device (e.g. call idectl).

The contents of the /proc/acpi/ibm/bay file shows the current status
of the UltraBay, as provided by the ACPI framework.

Experimental Features
---------------------

The following features are marked experimental because using them
involves guessing the correct values of some parameters. Guessing
incorrectly may have undesirable effects like crashing your
ThinkPad. USE THESE WITH CAUTION! To activate them, you'll need to
supply the experimental=1 parameter when loading the module.

Experimental: CMOS control - /proc/acpi/ibm/cmos
------------------------------------------------

This feature is used internally by the ACPI firmware to control the
ThinkLight on most newer ThinkPad models. It appears that it can also
control LCD brightness, sounds volume and more, but only on some
models.

The commands are non-negative integer numbers:

	echo 0 >/proc/acpi/ibm/cmos
	echo 1 >/proc/acpi/ibm/cmos
	echo 2 >/proc/acpi/ibm/cmos
	...

The range of numbers which are used internally by various models is 0
to 21, but it's possible that numbers outside this range have
interesting behavior. Here is the behavior on the X40 (tpb is the
ThinkPad Buttons utility):

	0 - no effect but tpb reports "Volume down"
	1 - no effect but tpb reports "Volume up"
	2 - no effect but tpb reports "Mute on"
	3 - simulate pressing the "Access IBM" button
	4 - LCD brightness up
	5 - LCD brightness down
	11 - toggle screen expansion
	12 - ThinkLight on
	13 - ThinkLight off
	14 - no effect but tpb reports ThinkLight status change

If you try this feature, please send me a report similar to the
above. On models which allow control of LCD brightness or sound
volume, I'd like to provide this functionality in an user-friendly
way, but first I need a way to identify the models which this is
possible.

Experimental: LED control - /proc/acpi/ibm/LED
----------------------------------------------

Some of the LED indicators can be controlled through this feature. The
available commands are:

	echo <led number> on >/proc/acpi/ibm/led
	echo <led number> off >/proc/acpi/ibm/led
	echo <led number> blink >/proc/acpi/ibm/led

The <led number> parameter is a non-negative integer. The range of LED
numbers used internally by various models is 0 to 7 but it's possible
that numbers outside this range are also valid. Here is the mapping on
the X40:

	0 - power
	1 - battery (orange)
	2 - battery (green)
	3 - UltraBase
	4 - UltraBay
	7 - standby

All of the above can be turned on and off and can be made to blink.

If you try this feature, please send me a report similar to the
above. I'd like to provide this functionality in an user-friendly way,
but first I need to identify the which numbers correspond to which
LEDs on various models.

Experimental: ACPI sounds - /proc/acpi/ibm/beep
-----------------------------------------------

The BEEP method is used internally by the ACPI firmware to provide
audible alerts in various situtation. This feature allows the same
sounds to be triggered manually.

The commands are non-negative integer numbers:

	echo 0 >/proc/acpi/ibm/beep
	echo 1 >/proc/acpi/ibm/beep
	echo 2 >/proc/acpi/ibm/beep
	...

The range of numbers which are used internally by various models is 0
to 17, but it's possible that numbers outside this range are also
valid. Here is the behavior on the X40:

	2 - two beeps, pause, third beep
	3 - single beep
	4 - "unable"	
	5 - single beep
	6 - "AC/DC"
	7 - high-pitched beep
	9 - three short beeps
	10 - very long beep
	12 - low-pitched beep

(I've only been able to identify a couple of them).

If you try this feature, please send me a report similar to the
above. I'd like to provide this functionality in an user-friendly way,
but first I need to identify the which numbers correspond to which
sounds on various models.


Multiple Command, Module Parameters
-----------------------------------

Multiple commands can be written to the proc files in one shot by
separating them with commas, for example:

	echo enable,0xffff > /proc/acpi/ibm/hotkey
	echo lcd_disable,crt_enable > /proc/acpi/ibm/video

Commands can also be specified when loading the ibm_acpi module, for
example:

	modprobe ibm_acpi hotkey=enable,0xffff video=auto_disable


Example Configuration
---------------------

The ACPI support in the kernel is intended to be used in conjunction
with a user-space daemon, acpid. The configuration files for this
daemon control what actions are taken in response to various ACPI
events. An example set of configuration files are included in the
config/ directory of the tarball package available on the web
site. Note that these are provided for illustration purposes only and
may need to be adapted to your particular setup.

The following utility scripts are used by the example action
scripts (included with ibm-acpi for completeness):

	/usr/local/sbin/idectl -- from the hdparm source distribution,
		see http://www.ibiblio.org/pub/Linux/system/hardware
	/usr/local/sbin/laptop_mode -- from the Linux kernel source
		distribution, see Documentation/laptop-mode.txt
	/sbin/service -- comes with Redhat/Fedora distributions

Toan T Nguyen <[email protected]> has written a SuSE powersave
script for the X20, included in config/usr/sbin/ibm_hotkeys_X20

Henrik Brix Andersen <[email protected]> has written a Gentoo ACPI event
handler script for the X31. You can get the latest version from
http://dev.gentoo.org/~brix/files/x31.sh

David Schweikert <[email protected]> has written an alternative blank.sh
script which works on Debian systems, included in
configs/etc/acpi/actions/blank-debian.sh


TODO
----

I'd like to implement the following features but haven't yet found the
time and/or I don't yet know how to implement them:

- UltraBay floppy drive support