Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

11 files changed, 3134 insertions, 0 deletions

diff --git a/Documentation/admin-guide/laptops/alienware-wmi.rst b/Documentation/admin-guide/laptops/alienware-wmi.rst
new file mode 100644
index 000000000..e532c60db
--- /dev/null
+++ b/Documentation/admin-guide/laptops/alienware-wmi.rst
@@ -0,0 +1,127 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+====================
+Alienware WMI Driver
+====================
+
+Kurt Borja <kuurtb@gmail.com>
+
+This is a driver for the "WMAX" WMI device, which is found in most Dell gaming
+laptops and controls various special features.
+
+Before the launch of M-Series laptops (~2018), the "WMAX" device controlled
+basic RGB lighting, deep sleep mode, HDMI mode and amplifier status.
+
+Later, this device was completely repurpused. Now it mostly deals with thermal
+profiles, sensor monitoring and overclocking. This interface is named "AWCC" and
+is known to be used by the AWCC OEM application to control these features.
+
+The alienware-wmi driver controls both interfaces.
+
+AWCC Interface
+==============
+
+WMI device documentation: Documentation/wmi/devices/alienware-wmi.rst
+
+Supported devices
+-----------------
+
+- Alienware M-Series laptops
+- Alienware X-Series laptops
+- Alienware Aurora Desktops
+- Dell G-Series laptops
+
+If you believe your device supports the AWCC interface and you don't have any of
+the features described in this document, try the following alienware-wmi module
+parameters:
+
+- ``force_platform_profile=1``: Forces probing for platform profile support
+- ``force_hwmon=1``: Forces probing for HWMON support
+
+If the module loads successfully with these parameters, consider submitting a
+patch adding your model to the ``awcc_dmi_table`` located in
+``drivers/platform/x86/dell/alienware-wmi-wmax.c`` or contacting the maintainer
+for further guidance.
+
+Status
+------
+
+The following features are currently supported:
+
+- :ref:`Platform Profile <platform-profile>`:
+
+  - Thermal profile control
+
+  - G-Mode toggling
+
+- :ref:`HWMON <hwmon>`:
+
+  - Sensor monitoring
+
+  - Manual fan control
+
+.. _platform-profile:
+
+Platform Profile
+----------------
+
+The AWCC interface exposes various firmware defined thermal profiles. These are
+exposed to user-space through the Platform Profile class interface. Refer to
+:ref:`sysfs-class-platform-profile <abi_file_testing_sysfs_class_platform_profile>`
+for more information.
+
+The name of the platform-profile class device exported by this driver is
+"alienware-wmi" and it's path can be found with:
+
+::
+
+ grep -l "alienware-wmi" /sys/class/platform-profile/platform-profile-*/name | sed 's|/[^/]*$||'
+
+If the device supports G-Mode, it is also toggled when selecting the
+``performance`` profile.
+
+.. note::
+   You may set the ``force_gmode`` module parameter to always try to toggle this
+   feature, without checking if your model supports it.
+
+.. _hwmon:
+
+HWMON
+-----
+
+The AWCC interface also supports sensor monitoring and manual fan control. Both
+of these features are exposed to user-space through the HWMON interface.
+
+The name of the hwmon class device exported by this driver is "alienware_wmi"
+and it's path can be found with:
+
+::
+
+ grep -l "alienware_wmi" /sys/class/hwmon/hwmon*/name | sed 's|/[^/]*$||'
+
+Sensor monitoring is done through the standard HWMON interface. Refer to
+:ref:`sysfs-class-hwmon <abi_file_testing_sysfs_class_hwmon>` for more
+information.
+
+Manual fan control on the other hand, is not exposed directly by the AWCC
+interface. Instead it let's us control a fan `boost` value. This `boost` value
+has the following approximate behavior over the fan pwm:
+
+::
+
+ pwm = pwm_base + (fan_boost / 255) * (pwm_max - pwm_base)
+
+Due to the above behavior, the fan `boost` control is exposed to user-space
+through the following, custom hwmon sysfs attribute:
+
+=============================== ======= =======================================
+Name				Perm	Description
+=============================== ======= =======================================
+fan[1-4]_boost			RW	Fan boost value.
+
+					Integer value between 0 and 255
+=============================== ======= =======================================
+
+.. note::
+   In some devices, manual fan control only works reliably if the ``custom``
+   platform profile is selected.
diff --git a/Documentation/admin-guide/laptops/asus-laptop.rst b/Documentation/admin-guide/laptops/asus-laptop.rst
new file mode 100644
index 000000000..95176321a
--- /dev/null
+++ b/Documentation/admin-guide/laptops/asus-laptop.rst
@@ -0,0 +1,271 @@
+==================
+Asus Laptop Extras
+==================
+
+Version 0.1
+
+August 6, 2009
+
+Corentin Chary <corentincj@iksaif.net>
+http://acpi4asus.sf.net/
+
+ This driver provides support for extra features of ACPI-compatible ASUS laptops.
+ It may also support some MEDION, JVC or VICTOR laptops (such as MEDION 9675 or
+ VICTOR XP7210 for example). It makes all the extra buttons generate input
+ events (like keyboards).
+
+ On some models adds support for changing the display brightness and output,
+ switching the LCD backlight on and off, and most importantly, allows you to
+ blink those fancy LEDs intended for reporting mail and wireless status.
+
+This driver supersedes the old asus_acpi driver.
+
+Requirements
+------------
+
+  Kernel 2.6.X sources, configured for your computer, with ACPI support.
+  You also need CONFIG_INPUT and CONFIG_ACPI.
+
+Status
+------
+
+ The features currently supported are the following (see below for
+ detailed description):
+
+ - Fn key combinations
+ - Bluetooth enable and disable
+ - Wlan enable and disable
+ - GPS enable and disable
+ - Video output switching
+ - Ambient Light Sensor on and off
+ - LED control
+ - LED Display control
+ - LCD brightness control
+ - LCD on and off
+
+ A compatibility table by model and feature is maintained on the web
+ site, http://acpi4asus.sf.net/.
+
+Usage
+-----
+
+  Try "modprobe asus-laptop". Check your dmesg (simply type dmesg). You should
+  see some lines like this :
+
+      Asus Laptop Extras version 0.42
+        - L2D model detected.
+
+  If it is not the output you have on your laptop, send it (and the laptop's
+  DSDT) to me.
+
+  That's all, now, all the events generated by the hotkeys of your laptop
+  should be reported via netlink events. You can check with
+  "acpi_genl monitor" (part of the acpica project).
+
+  Hotkeys are also reported as input keys (like keyboards) you can check
+  which key are supported using "xev" under X11.
+
+  You can get information on the version of your DSDT table by reading the
+  /sys/devices/platform/asus-laptop/infos entry. If you have a question or a
+  bug report to do, please include the output of this entry.
+
+LEDs
+----
+
+  You can modify LEDs be echoing values to `/sys/class/leds/asus/*/brightness`::
+
+    echo 1 >  /sys/class/leds/asus::mail/brightness
+
+  will switch the mail LED on.
+
+  You can also know if they are on/off by reading their content and use
+  kernel triggers like disk-activity or heartbeat.
+
+Backlight
+---------
+
+  You can control lcd backlight power and brightness with
+  /sys/class/backlight/asus-laptop/. Brightness Values are between 0 and 15.
+
+Wireless devices
+----------------
+
+  You can turn the internal Bluetooth adapter on/off with the bluetooth entry
+  (only on models with Bluetooth). This usually controls the associated LED.
+  Same for Wlan adapter.
+
+Display switching
+-----------------
+
+  Note: the display switching code is currently considered EXPERIMENTAL.
+
+  Switching works for the following models:
+
+    - L3800C
+    - A2500H
+    - L5800C
+    - M5200N
+    - W1000N (albeit with some glitches)
+    - M6700R
+    - A6JC
+    - F3J
+
+  Switching doesn't work for the following:
+
+    - M3700N
+    - L2X00D (locks the laptop under certain conditions)
+
+  To switch the displays, echo values from 0 to 15 to
+  /sys/devices/platform/asus-laptop/display. The significance of those values
+  is as follows:
+
+  +-------+-----+-----+-----+-----+-----+
+  | Bin   | Val | DVI | TV  | CRT | LCD |
+  +-------+-----+-----+-----+-----+-----+
+  | 0000  |   0 |     |     |     |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 0001  |   1 |     |     |     |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 0010  |   2 |     |     |  X  |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 0011  |   3 |     |     |  X  |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 0100  |   4 |     |  X  |     |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 0101  |   5 |     |  X  |     | X   |
+  +-------+-----+-----+-----+-----+-----+
+  | 0110  |   6 |     |  X  |  X  |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 0111  |   7 |     |  X  |  X  |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 1000  |   8 |  X  |     |     |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 1001  |   9 |  X  |     |     |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 1010  |  10 |  X  |     |  X  |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 1011  |  11 |  X  |     |  X  |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 1100  |  12 |  X  |  X  |     |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 1101  |  13 |  X  |  X  |     |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 1110  |  14 |  X  |  X  |  X  |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 1111  |  15 |  X  |  X  |  X  |  X  |
+  +-------+-----+-----+-----+-----+-----+
+
+  In most cases, the appropriate displays must be plugged in for the above
+  combinations to work. TV-Out may need to be initialized at boot time.
+
+  Debugging:
+
+  1) Check whether the Fn+F8 key:
+
+     a) does not lock the laptop (try a boot with noapic / nolapic if it does)
+     b) generates events (0x6n, where n is the value corresponding to the
+        configuration above)
+     c) actually works
+
+     Record the disp value at every configuration.
+  2) Echo values from 0 to 15 to /sys/devices/platform/asus-laptop/display.
+     Record its value, note any change. If nothing changes, try a broader range,
+     up to 65535.
+  3) Send ANY output (both positive and negative reports are needed, unless your
+     machine is already listed above) to the acpi4asus-user mailing list.
+
+  Note: on some machines (e.g. L3C), after the module has been loaded, only 0x6n
+  events are generated and no actual switching occurs. In such a case, a line
+  like::
+
+    echo $((10#$arg-60)) > /sys/devices/platform/asus-laptop/display
+
+  will usually do the trick ($arg is the 0000006n-like event passed to acpid).
+
+  Note: there is currently no reliable way to read display status on xxN
+  (Centrino) models.
+
+LED display
+-----------
+
+  Some models like the W1N have a LED display that can be used to display
+  several items of information.
+
+  LED display works for the following models:
+
+    - W1000N
+    - W1J
+
+  To control the LED display, use the following::
+
+    echo 0x0T000DDD > /sys/devices/platform/asus-laptop/
+
+  where T control the 3 letters display, and DDD the 3 digits display,
+  according to the tables below::
+
+         DDD (digits)
+         000 to 999 = display digits
+         AAA        = ---
+         BBB to FFF = turn-off
+
+         T  (type)
+         0 = off
+         1 = dvd
+         2 = vcd
+         3 = mp3
+         4 = cd
+         5 = tv
+         6 = cpu
+         7 = vol
+
+  For example "echo 0x01000001 >/sys/devices/platform/asus-laptop/ledd"
+  would display "DVD001".
+
+Driver options
+--------------
+
+ Options can be passed to the asus-laptop driver using the standard
+ module argument syntax (<param>=<value> when passing the option to the
+ module or asus-laptop.<param>=<value> on the kernel boot line when
+ asus-laptop is statically linked into the kernel).
+
+	     wapf: WAPF defines the behavior of the Fn+Fx wlan key
+		   The significance of values is yet to be found, but
+		   most of the time:
+
+		   - 0x0 should do nothing
+		   - 0x1 should allow to control the device with Fn+Fx key.
+		   - 0x4 should send an ACPI event (0x88) while pressing the Fn+Fx key
+		   - 0x5 like 0x1 or 0x4
+
+ The default value is 0x1.
+
+Unsupported models
+------------------
+
+ These models will never be supported by this module, as they use a completely
+ different mechanism to handle LEDs and extra stuff (meaning we have no clue
+ how it works):
+
+ - ASUS A1300 (A1B), A1370D
+ - ASUS L7300G
+ - ASUS L8400
+
+Patches, Errors, Questions
+--------------------------
+
+ 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:
+
+ - Asus model name
+ - a copy of your ACPI tables, using the "acpidump" utility
+ - a copy of /sys/devices/platform/asus-laptop/infos
+ - 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.
+
+ acpi4asus-user@lists.sourceforge.net
+
+ http://sourceforge.net/projects/acpi4asus
diff --git a/Documentation/admin-guide/laptops/disk-shock-protection.rst b/Documentation/admin-guide/laptops/disk-shock-protection.rst
new file mode 100644
index 000000000..22c7ec3e8
--- /dev/null
+++ b/Documentation/admin-guide/laptops/disk-shock-protection.rst
@@ -0,0 +1,151 @@
+==========================
+Hard disk shock protection
+==========================
+
+Author: Elias Oltmanns <eo@nebensachen.de>
+
+Last modified: 2008-10-03
+
+
+.. 0. Contents
+
+   1. Intro
+   2. The interface
+   3. References
+   4. CREDITS
+
+
+1. Intro
+--------
+
+ATA/ATAPI-7 specifies the IDLE IMMEDIATE command with unload feature.
+Issuing this command should cause the drive to switch to idle mode and
+unload disk heads. This feature is being used in modern laptops in
+conjunction with accelerometers and appropriate software to implement
+a shock protection facility. The idea is to stop all I/O operations on
+the internal hard drive and park its heads on the ramp when critical
+situations are anticipated. The desire to have such a feature
+available on GNU/Linux systems has been the original motivation to
+implement a generic disk head parking interface in the Linux kernel.
+Please note, however, that other components have to be set up on your
+system in order to get disk shock protection working (see
+section 3. References below for pointers to more information about
+that).
+
+
+2. The interface
+----------------
+
+For each ATA device, the kernel exports the file
+`block/*/device/unload_heads` in sysfs (here assumed to be mounted under
+/sys). Access to `/sys/block/*/device/unload_heads` is denied with
+-EOPNOTSUPP if the device does not support the unload feature.
+Otherwise, writing an integer value to this file will take the heads
+of the respective drive off the platter and block all I/O operations
+for the specified number of milliseconds. When the timeout expires and
+no further disk head park request has been issued in the meantime,
+normal operation will be resumed. The maximal value accepted for a
+timeout is 30000 milliseconds. Exceeding this limit will return
+-EOVERFLOW, but heads will be parked anyway and the timeout will be
+set to 30 seconds. However, you can always change a timeout to any
+value between 0 and 30000 by issuing a subsequent head park request
+before the timeout of the previous one has expired. In particular, the
+total timeout can exceed 30 seconds and, more importantly, you can
+cancel a previously set timeout and resume normal operation
+immediately by specifying a timeout of 0. Values below -2 are rejected
+with -EINVAL (see below for the special meaning of -1 and -2). If the
+timeout specified for a recent head park request has not yet expired,
+reading from `/sys/block/*/device/unload_heads` will report the number
+of milliseconds remaining until normal operation will be resumed;
+otherwise, reading the unload_heads attribute will return 0.
+
+For example, do the following in order to park the heads of drive
+/dev/sda and stop all I/O operations for five seconds::
+
+	# echo 5000 > /sys/block/sda/device/unload_heads
+
+A simple::
+
+	# cat /sys/block/sda/device/unload_heads
+
+will show you how many milliseconds are left before normal operation
+will be resumed.
+
+A word of caution: The fact that the interface operates on a basis of
+milliseconds may raise expectations that cannot be satisfied in
+reality. In fact, the ATA specs clearly state that the time for an
+unload operation to complete is vendor specific. The hint in ATA-7
+that this will typically be within 500 milliseconds apparently has
+been dropped in ATA-8.
+
+There is a technical detail of this implementation that may cause some
+confusion and should be discussed here. When a head park request has
+been issued to a device successfully, all I/O operations on the
+controller port this device is attached to will be deferred. That is
+to say, any other device that may be connected to the same port will
+be affected too. The only exception is that a subsequent head unload
+request to that other device will be executed immediately. Further
+operations on that port will be deferred until the timeout specified
+for either device on the port has expired. As far as PATA (old style
+IDE) configurations are concerned, there can only be two devices
+attached to any single port. In SATA world we have port multipliers
+which means that a user-issued head parking request to one device may
+actually result in stopping I/O to a whole bunch of devices. However,
+since this feature is supposed to be used on laptops and does not seem
+to be very useful in any other environment, there will be mostly one
+device per port. Even if the CD/DVD writer happens to be connected to
+the same port as the hard drive, it generally *should* recover just
+fine from the occasional buffer under-run incurred by a head park
+request to the HD. Actually, when you are using an ide driver rather
+than its libata counterpart (i.e. your disk is called /dev/hda
+instead of /dev/sda), then parking the heads of one drive (drive X)
+will generally not affect the mode of operation of another drive
+(drive Y) on the same port as described above. It is only when a port
+reset is required to recover from an exception on drive Y that further
+I/O operations on that drive (and the reset itself) will be delayed
+until drive X is no longer in the parked state.
+
+Finally, there are some hard drives that only comply with an earlier
+version of the ATA standard than ATA-7, but do support the unload
+feature nonetheless. Unfortunately, there is no safe way Linux can
+detect these devices, so you won't be able to write to the
+unload_heads attribute. If you know that your device really does
+support the unload feature (for instance, because the vendor of your
+laptop or the hard drive itself told you so), then you can tell the
+kernel to enable the usage of this feature for that drive by writing
+the special value -1 to the unload_heads attribute::
+
+	# echo -1 > /sys/block/sda/device/unload_heads
+
+will enable the feature for /dev/sda, and giving -2 instead of -1 will
+disable it again.
+
+
+3. References
+-------------
+
+There are several laptops from different vendors featuring shock
+protection capabilities. As manufacturers have refused to support open
+source development of the required software components so far, Linux
+support for shock protection varies considerably between different
+hardware implementations. Ideally, this section should contain a list
+of pointers at different projects aiming at an implementation of shock
+protection on different systems. Unfortunately, I only know of a
+single project which, although still considered experimental, is fit
+for use. Please feel free to add projects that have been the victims
+of my ignorance.
+
+- https://www.thinkwiki.org/wiki/HDAPS
+
+  See this page for information about Linux support of the hard disk
+  active protection system as implemented in IBM/Lenovo Thinkpads.
+
+
+4. CREDITS
+----------
+
+This implementation of disk head parking has been inspired by a patch
+originally published by Jon Escombe <lists@dresco.co.uk>. My efforts
+to develop an implementation of this feature that is fit to be merged
+into mainline have been aided by various kernel developers, in
+particular by Tejun Heo and Bartlomiej Zolnierkiewicz.
diff --git a/Documentation/admin-guide/laptops/index.rst b/Documentation/admin-guide/laptops/index.rst
new file mode 100644
index 000000000..c0b911d05
--- /dev/null
+++ b/Documentation/admin-guide/laptops/index.rst
@@ -0,0 +1,19 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============
+Laptop Drivers
+==============
+
+.. toctree::
+   :maxdepth: 1
+
+   alienware-wmi
+   asus-laptop
+   disk-shock-protection
+   lg-laptop
+   samsung-galaxybook
+   sony-laptop
+   sonypi
+   thinkpad-acpi
+   toshiba_haps
+   uniwill-laptop
diff --git a/Documentation/admin-guide/laptops/lg-laptop.rst b/Documentation/admin-guide/laptops/lg-laptop.rst
new file mode 100644
index 000000000..c4dd534f9
--- /dev/null
+++ b/Documentation/admin-guide/laptops/lg-laptop.rst
@@ -0,0 +1,82 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+
+LG Gram laptop extra features
+=============================
+
+By Matan Ziv-Av <matan@svgalib.org>
+
+
+Hotkeys
+-------
+
+The following FN keys are ignored by the kernel without this driver:
+
+- FN-F1 (LG control panel)   - Generates F15
+- FN-F5 (Touchpad toggle)    - Generates F21
+- FN-F6 (Airplane mode)      - Generates RFKILL
+- FN-F9 (Reader mode)        - Generates F14
+
+The rest of the FN keys work without a need for a special driver.
+
+
+Reader mode
+-----------
+
+Writing 0/1 to /sys/devices/platform/lg-laptop/reader_mode disables/enables
+reader mode. In this mode the screen colors change (blue color reduced),
+and the reader mode indicator LED (on F9 key) turns on.
+
+
+FN Lock
+-------
+
+Writing 0/1 to /sys/devices/platform/lg-laptop/fn_lock disables/enables
+FN lock.
+
+
+Battery care limit
+------------------
+
+Writing 80/100 to /sys/class/power_supply/CMB0/charge_control_end_threshold
+sets the maximum capacity to charge the battery. Limiting the charge
+reduces battery capacity loss over time.
+
+This value is reset to 100 when the kernel boots.
+
+
+Fan mode
+--------
+
+Writing 0/1/2 to /sys/devices/platform/lg-laptop/fan_mode sets fan mode to
+Optimal/Silent/Performance respectively.
+
+
+USB charge
+----------
+
+Writing 0/1 to /sys/devices/platform/lg-laptop/usb_charge disables/enables
+charging another device from the USB port while the device is turned off.
+
+This value is reset to 0 when the kernel boots.
+
+
+LEDs
+~~~~
+
+The are two LED devices supported by the driver:
+
+Keyboard backlight
+------------------
+
+A led device named kbd_led controls the keyboard backlight. There are three
+lighting level: off (0), low (127) and high (255).
+
+The keyboard backlight is also controlled by the key combination FN-F8
+which cycles through those levels.
+
+
+Touchpad indicator LED
+----------------------
+
+On the F5 key. Controlled by led device names tpad_led.
diff --git a/Documentation/admin-guide/laptops/samsung-galaxybook.rst b/Documentation/admin-guide/laptops/samsung-galaxybook.rst
new file mode 100644
index 000000000..752b8f1a4
--- /dev/null
+++ b/Documentation/admin-guide/laptops/samsung-galaxybook.rst
@@ -0,0 +1,174 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+==========================
+Samsung Galaxy Book Driver
+==========================
+
+Joshua Grisham <josh@joshuagrisham.com>
+
+This is a Linux x86 platform driver for Samsung Galaxy Book series notebook
+devices which utilizes Samsung's ``SCAI`` ACPI device in order to control
+extra features and receive various notifications.
+
+Supported devices
+=================
+
+Any device with one of the supported ACPI device IDs should be supported. This
+covers most of the "Samsung Galaxy Book" series notebooks that are currently
+available as of this writing, and could include other Samsung notebook devices
+as well.
+
+Status
+======
+
+The following features are currently supported:
+
+- :ref:`Keyboard backlight <keyboard-backlight>` control
+- :ref:`Performance mode <performance-mode>` control implemented using the
+  platform profile interface
+- :ref:`Battery charge control end threshold
+  <battery-charge-control-end-threshold>` (stop charging battery at given
+  percentage value) implemented as a battery hook
+- :ref:`Firmware Attributes <firmware-attributes>` to allow control of various
+  device settings
+- :ref:`Handling of Fn hotkeys <keyboard-hotkey-actions>` for various actions
+- :ref:`Handling of ACPI notifications and hotkeys
+  <acpi-notifications-and-hotkey-actions>`
+
+Because different models of these devices can vary in their features, there is
+logic built within the driver which attempts to test each implemented feature
+for a valid response before enabling its support (registering additional devices
+or extensions, adding sysfs attributes, etc). Therefore, it can be important to
+note that not all features may be supported for your particular device.
+
+The following features might be possible to implement but will require
+additional investigation and are therefore not supported at this time:
+
+- "Dolby Atmos" mode for the speakers
+- "Outdoor Mode" for increasing screen brightness on models with ``SAM0427``
+- "Silent Mode" on models with ``SAM0427``
+
+.. _keyboard-backlight:
+
+Keyboard backlight
+==================
+
+A new LED class named ``samsung-galaxybook::kbd_backlight`` is created which
+will then expose the device using the standard sysfs-based LED interface at
+``/sys/class/leds/samsung-galaxybook::kbd_backlight``. Brightness can be
+controlled by writing the desired value to the ``brightness`` sysfs attribute or
+with any other desired userspace utility.
+
+.. note::
+  Most of these devices have an ambient light sensor which also turns
+  off the keyboard backlight under well-lit conditions. This behavior does not
+  seem possible to control at this time, but can be good to be aware of.
+
+.. _performance-mode:
+
+Performance mode
+================
+
+This driver implements the
+Documentation/userspace-api/sysfs-platform_profile.rst interface for working
+with the "performance mode" function of the Samsung ACPI device.
+
+Mapping of each Samsung "performance mode" to its respective platform profile is
+performed dynamically by the driver, as not all models support all of the same
+performance modes. Your device might have one or more of the following mappings:
+
+- "Silent" maps to ``low-power``
+- "Quiet" maps to ``quiet``
+- "Optimized" maps to ``balanced``
+- "High performance" maps to ``performance``
+
+The result of the mapping can be printed in the kernel log when the module is
+loaded. Supported profiles can also be retrieved from
+``/sys/firmware/acpi/platform_profile_choices``, while
+``/sys/firmware/acpi/platform_profile`` can be used to read or write the
+currently selected profile.
+
+The ``balanced`` platform profile will be set during module load if no profile
+has been previously set.
+
+.. _battery-charge-control-end-threshold:
+
+Battery charge control end threshold
+====================================
+
+This platform driver will add the ability to set the battery's charge control
+end threshold, but does not have the ability to set a start threshold.
+
+This feature is typically called "Battery Saver" by the various Samsung
+applications in Windows, but in Linux we have implemented the standardized
+"charge control threshold" sysfs interface on the battery device to allow for
+controlling this functionality from the userspace.
+
+The sysfs attribute
+``/sys/class/power_supply/BAT1/charge_control_end_threshold`` can be used to
+read or set the desired charge end threshold.
+
+If you wish to maintain interoperability with the Samsung Settings application
+in Windows, then you should set the value to 100 to represent "off", or enable
+the feature using only one of the following values: 50, 60, 70, 80, or 90.
+Otherwise, the driver will accept any value between 1 and 100 as the percentage
+that you wish the battery to stop charging at.
+
+.. note::
+  Some devices have been observed as automatically "turning off" the charge
+  control end threshold if an input value of less than 30 is given.
+
+.. _firmware-attributes:
+
+Firmware Attributes
+===================
+
+The following enumeration-typed firmware attributes are set up by this driver
+and should be accessible under
+``/sys/class/firmware-attributes/samsung-galaxybook/attributes/`` if your device
+supports them:
+
+- ``power_on_lid_open`` (device should power on when the lid is opened)
+- ``usb_charging``  (USB ports can deliver power to connected devices even when
+  the device is powered off or in a low sleep state)
+- ``block_recording`` (blocks access to camera and microphone)
+
+All of these attributes are simple boolean-like enumeration values which use 0
+to represent "off" and 1 to represent "on". Use the ``current_value`` attribute
+to get or change the setting on the device.
+
+Note that when ``block_recording`` is updated, the input device "Samsung Galaxy
+Book Lens Cover" will receive a ``SW_CAMERA_LENS_COVER`` switch event which
+reflects the current state.
+
+.. _keyboard-hotkey-actions:
+
+Keyboard hotkey actions (i8042 filter)
+======================================
+
+The i8042 filter will swallow the keyboard events for the Fn+F9 hotkey (Multi-
+level keyboard backlight toggle) and Fn+F10 hotkey (Block recording toggle)
+and instead execute their actions within the driver itself.
+
+Fn+F9 will cycle through the brightness levels of the keyboard backlight. A
+notification will be sent using ``led_classdev_notify_brightness_hw_changed``
+so that the userspace can be aware of the change. This mimics the behavior of
+other existing devices where the brightness level is cycled internally by the
+embedded controller and then reported via a notification.
+
+Fn+F10 will toggle the value of the "block recording" setting, which blocks
+or allows usage of the built-in camera and microphone (and generates the same
+Lens Cover switch event mentioned above).
+
+.. _acpi-notifications-and-hotkey-actions:
+
+ACPI notifications and hotkey actions
+=====================================
+
+ACPI notifications will generate ACPI netlink events under the device class
+``samsung-galaxybook`` and bus ID matching the Samsung ACPI device ID found on
+your device. The events can be received using userspace tools such as
+``acpi_listen`` and ``acpid``.
+
+The Fn+F11 Performance mode hotkey will be handled by the driver; each keypress
+will cycle to the next available platform profile.
diff --git a/Documentation/admin-guide/laptops/sony-laptop.rst b/Documentation/admin-guide/laptops/sony-laptop.rst
new file mode 100644
index 000000000..9edcc7f66
--- /dev/null
+++ b/Documentation/admin-guide/laptops/sony-laptop.rst
@@ -0,0 +1,174 @@
+=========================================
+Sony Notebook Control Driver (SNC) Readme
+=========================================
+
+	- Copyright (C) 2004- 2005 Stelian Pop <stelian@popies.net>
+	- Copyright (C) 2007 Mattia Dongili <malattia@linux.it>
+
+This mini-driver drives the SNC and SPIC device present in the ACPI BIOS of the
+Sony Vaio laptops. This driver mixes both devices functions under the same
+(hopefully consistent) interface. This also means that the sonypi driver is
+obsoleted by sony-laptop now.
+
+Fn keys (hotkeys):
+------------------
+
+Some models report hotkeys through the SNC or SPIC devices, such events are
+reported both through the ACPI subsystem as acpi events and through the INPUT
+subsystem. See the logs of /proc/bus/input/devices to find out what those
+events are and which input devices are created by the driver.
+Additionally, loading the driver with the debug option will report all events
+in the kernel log.
+
+The "scancodes" passed to the input system (that can be remapped with udev)
+are indexes to the table "sony_laptop_input_keycode_map" in the sony-laptop.c
+module.  For example the "FN/E" key combination (EJECTCD on some models)
+generates the scancode 20 (0x14).
+
+Backlight control:
+------------------
+If your laptop model supports it, you will find sysfs files in the
+/sys/class/backlight/sony/
+directory. You will be able to query and set the current screen
+brightness:
+
+	======================	=========================================
+	brightness		get/set screen brightness (an integer
+				between 0 and 7)
+	actual_brightness	reading from this file will query the HW
+				to get real brightness value
+	max_brightness		the maximum brightness value
+	======================	=========================================
+
+
+Platform specific:
+------------------
+Loading the sony-laptop module will create a
+/sys/devices/platform/sony-laptop/
+directory populated with some files.
+
+You then read/write integer values from/to those files by using
+standard UNIX tools.
+
+The files are:
+
+	======================	==========================================
+	brightness_default	screen brightness which will be set
+				when the laptop will be rebooted
+	cdpower			power on/off the internal CD drive
+	audiopower		power on/off the internal sound card
+	lanpower		power on/off the internal ethernet card
+				(only in debug mode)
+	bluetoothpower		power on/off the internal bluetooth device
+	fanspeed		get/set the fan speed
+	======================	==========================================
+
+Note that some files may be missing if they are not supported
+by your particular laptop model.
+
+Example usage::
+
+	# echo "1" > /sys/devices/platform/sony-laptop/brightness_default
+
+sets the lowest screen brightness for the next and later reboots
+
+::
+
+	# echo "8" > /sys/devices/platform/sony-laptop/brightness_default
+
+sets the highest screen brightness for the next and later reboots
+
+::
+
+	# cat /sys/devices/platform/sony-laptop/brightness_default
+
+retrieves the value
+
+::
+
+	# echo "0" > /sys/devices/platform/sony-laptop/audiopower
+
+powers off the sound card
+
+::
+
+	# echo "1" > /sys/devices/platform/sony-laptop/audiopower
+
+powers on the sound card.
+
+
+RFkill control:
+---------------
+More recent Vaio models expose a consistent set of ACPI methods to
+control radio frequency emitting devices. If you are a lucky owner of
+such a laptop you will find the necessary rfkill devices under
+/sys/class/rfkill. Check those starting with sony-* in::
+
+	# grep . /sys/class/rfkill/*/{state,name}
+
+
+Development:
+------------
+
+If you want to help with the development of this driver (and
+you are not afraid of any side effects doing strange things with
+your ACPI BIOS could have on your laptop), load the driver and
+pass the option 'debug=1'.
+
+REPEAT:
+	**DON'T DO THIS IF YOU DON'T LIKE RISKY BUSINESS.**
+
+In your kernel logs you will find the list of all ACPI methods
+the SNC device has on your laptop.
+
+* For new models you will see a long list of meaningless method names,
+  reading the DSDT table source should reveal that:
+
+(1) the SNC device uses an internal capability lookup table
+(2) SN00 is used to find values in the lookup table
+(3) SN06 and SN07 are used to call into the real methods based on
+    offsets you can obtain iterating the table using SN00
+(4) SN02 used to enable events.
+
+Some values in the capability lookup table are more or less known, see
+the code for all sony_call_snc_handle calls, others are more obscure.
+
+* For old models you can see the GCDP/GCDP methods used to pwer on/off
+  the CD drive, but there are others and they are usually different from
+  model to model.
+
+**I HAVE NO IDEA WHAT THOSE METHODS DO.**
+
+The sony-laptop driver creates, for some of those methods (the most
+current ones found on several Vaio models), an entry under
+/sys/devices/platform/sony-laptop, just like the 'cdpower' one.
+You can create other entries corresponding to your own laptop methods by
+further editing the source (see the 'sony_nc_values' table, and add a new
+entry to this table with your get/set method names using the
+SNC_HANDLE_NAMES macro).
+
+Your mission, should you accept it, is to try finding out what
+those entries are for, by reading/writing random values from/to those
+files and find out what is the impact on your laptop.
+
+Should you find anything interesting, please report it back to me,
+I will not disavow all knowledge of your actions :)
+
+See also http://www.linux.it/~malattia/wiki/index.php/Sony_drivers for other
+useful info.
+
+Bugs/Limitations:
+-----------------
+
+* This driver is not based on official documentation from Sony
+  (because there is none), so there is no guarantee this driver
+  will work at all, or do the right thing. Although this hasn't
+  happened to me, this driver could do very bad things to your
+  laptop, including permanent damage.
+
+* The sony-laptop and sonypi drivers do not interact at all. In the
+  future, sonypi will be removed and replaced by sony-laptop.
+
+* spicctrl, which is the userspace tool used to communicate with the
+  sonypi driver (through /dev/sonypi) is deprecated as well since all
+  its features are now available under the sysfs tree via sony-laptop.
diff --git a/Documentation/admin-guide/laptops/sonypi.rst b/Documentation/admin-guide/laptops/sonypi.rst
new file mode 100644
index 000000000..fb8f4a30d
--- /dev/null
+++ b/Documentation/admin-guide/laptops/sonypi.rst
@@ -0,0 +1,158 @@
+==================================================
+Sony Programmable I/O Control Device Driver Readme
+==================================================
+
+	- Copyright (C) 2001-2004 Stelian Pop <stelian@popies.net>
+	- Copyright (C) 2001-2002 Alcôve <www.alcove.com>
+	- Copyright (C) 2001 Michael Ashley <m.ashley@unsw.edu.au>
+	- Copyright (C) 2001 Junichi Morita <jun1m@mars.dti.ne.jp>
+	- Copyright (C) 2000 Takaya Kinjo <t-kinjo@tc4.so-net.ne.jp>
+	- Copyright (C) 2000 Andrew Tridgell <tridge@samba.org>
+
+This driver enables access to the Sony Programmable I/O Control Device which
+can be found in many Sony Vaio laptops. Some newer Sony laptops (seems to be
+limited to new FX series laptops, at least the FX501 and the FX702) lack a
+sonypi device and are not supported at all by this driver.
+
+It will give access (through a user space utility) to some events those laptops
+generate, like:
+
+	- jogdial events (the small wheel on the side of Vaios)
+	- capture button events (only on Vaio Picturebook series)
+	- Fn keys
+	- bluetooth button (only on C1VR model)
+	- programmable keys, back, help, zoom, thumbphrase buttons, etc.
+	  (when available)
+
+Those events (see linux/sonypi.h) can be polled using the character device node
+/dev/sonypi (major 10, minor auto allocated or specified as an option).
+A simple daemon which translates the jogdial movements into mouse wheel events
+can be downloaded at: <http://popies.net/sonypi/>
+
+Another option to intercept the events is to get them directly through the
+input layer.
+
+This driver supports also some ioctl commands for setting the LCD screen
+brightness and querying the batteries charge information (some more
+commands may be added in the future).
+
+This driver can also be used to set the camera controls on Picturebook series
+(brightness, contrast etc), and is used by the video4linux driver for the
+Motion Eye camera.
+
+Please note that this driver was created by reverse engineering the Windows
+driver and the ACPI BIOS, because Sony doesn't agree to release any programming
+specs for its laptops. If someone convinces them to do so, drop me a note.
+
+Driver options:
+---------------
+
+Several options can be passed to the sonypi driver using the standard
+module argument syntax (<param>=<value> when passing the option to the
+module or sonypi.<param>=<value> on the kernel boot line when sonypi is
+statically linked into the kernel). Those options are:
+
+	=============== =======================================================
+	minor:		minor number of the misc device /dev/sonypi,
+			default is -1 (automatic allocation, see /proc/misc
+			or kernel logs)
+
+	camera:		if you have a PictureBook series Vaio (with the
+			integrated MotionEye camera), set this parameter to 1
+			in order to let the driver access to the camera
+
+	fnkeyinit:	on some Vaios (C1VE, C1VR etc), the Fn key events don't
+			get enabled unless you set this parameter to 1.
+			Do not use this option unless it's actually necessary,
+			some Vaio models don't deal well with this option.
+			This option is available only if the kernel is
+			compiled without ACPI support (since it conflicts
+			with it and it shouldn't be required anyway if
+			ACPI is already enabled).
+
+	verbose:	set to 1 to print unknown events received from the
+			sonypi device.
+			set to 2 to print all events received from the
+			sonypi device.
+
+	compat:		uses some compatibility code for enabling the sonypi
+			events. If the driver worked for you in the past
+			(prior to version 1.5) and does not work anymore,
+			add this option and report to the author.
+
+	mask:		event mask telling the driver what events will be
+			reported to the user. This parameter is required for
+			some Vaio models where the hardware reuses values
+			used in other Vaio models (like the FX series who does
+			not have a jogdial but reuses the jogdial events for
+			programmable keys events). The default event mask is
+			set to 0xffffffff, meaning that all possible events
+			will be tried. You can use the following bits to
+			construct your own event mask (from
+			include/linux/sonypi.h)::
+
+				SONYPI_JOGGER_MASK		0x0001
+				SONYPI_CAPTURE_MASK		0x0002
+				SONYPI_FNKEY_MASK		0x0004
+				SONYPI_BLUETOOTH_MASK		0x0008
+				SONYPI_PKEY_MASK		0x0010
+				SONYPI_BACK_MASK		0x0020
+				SONYPI_HELP_MASK		0x0040
+				SONYPI_LID_MASK			0x0080
+				SONYPI_ZOOM_MASK		0x0100
+				SONYPI_THUMBPHRASE_MASK		0x0200
+				SONYPI_MEYE_MASK		0x0400
+				SONYPI_MEMORYSTICK_MASK		0x0800
+				SONYPI_BATTERY_MASK		0x1000
+				SONYPI_WIRELESS_MASK		0x2000
+
+	useinput:	if set (which is the default) two input devices are
+			created, one which interprets the jogdial events as
+			mouse events, the other one which acts like a
+			keyboard reporting the pressing of the special keys.
+	=============== =======================================================
+
+Module use:
+-----------
+
+In order to automatically load the sonypi module on use, you can put those
+lines a configuration file in /etc/modprobe.d/::
+
+	alias char-major-10-250 sonypi
+	options sonypi minor=250
+
+This supposes the use of minor 250 for the sonypi device::
+
+	# mknod /dev/sonypi c 10 250
+
+Bugs:
+-----
+
+	- several users reported that this driver disables the BIOS-managed
+	  Fn-keys which put the laptop in sleeping state, or switch the
+	  external monitor on/off. There is no workaround yet, since this
+	  driver disables all APM management for those keys, by enabling the
+	  ACPI management (and the ACPI core stuff is not complete yet). If
+	  you have one of those laptops with working Fn keys and want to
+	  continue to use them, don't use this driver.
+
+	- some users reported that the laptop speed is lower (dhrystone
+	  tested) when using the driver with the fnkeyinit parameter. I cannot
+	  reproduce it on my laptop and not all users have this problem.
+	  This happens because the fnkeyinit parameter enables the ACPI
+	  mode (but without additional ACPI control, like processor
+	  speed handling etc). Use ACPI instead of APM if it works on your
+	  laptop.
+
+	- sonypi lacks the ability to distinguish between certain key
+	  events on some models.
+
+	- some models with the nvidia card (geforce go 6200 tc) uses a
+	  different way to adjust the backlighting of the screen. There
+	  is a userspace utility to adjust the brightness on those models,
+	  which can be downloaded from
+	  https://www.acc.umu.se/~erikw/program/smartdimmer-0.1.tar.bz2
+
+	- since all development was done by reverse engineering, there is
+	  *absolutely no guarantee* that this driver will not crash your
+	  laptop. Permanently.
diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
new file mode 100644
index 000000000..db4588af0
--- /dev/null
+++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
@@ -0,0 +1,1773 @@
+===========================
+ThinkPad ACPI Extras Driver
+===========================
+
+Version 0.25
+
+October 16th,  2013
+
+- Borislav Deianov <borislav@users.sf.net>
+- Henrique de Moraes Holschuh <hmh@hmh.eng.br>
+
+http://ibm-acpi.sf.net/
+
+This is a Linux driver for the IBM and Lenovo ThinkPad laptops. It
+supports various features of these laptops which are accessible
+through the ACPI and ACPI EC framework, but not otherwise fully
+supported by the generic Linux ACPI drivers.
+
+This driver used to be named ibm-acpi until kernel 2.6.21 and release
+0.13-20070314.  It used to be in the drivers/acpi tree, but it was
+moved to the drivers/misc tree and renamed to thinkpad-acpi for kernel
+2.6.22, and release 0.14.  It was moved to drivers/platform/x86 for
+kernel 2.6.29 and release 0.22.
+
+The driver is named "thinkpad-acpi".  In some places, like module
+names and log messages, "thinkpad_acpi" is used because of userspace
+issues.
+
+"tpacpi" is used as a shorthand where "thinkpad-acpi" would be too
+long due to length limitations on some Linux kernel versions.
+
+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
+	- CMOS/UCMS control
+	- LED control
+	- ACPI sounds
+	- temperature sensors
+	- Experimental: embedded controller register dump
+	- LCD brightness control
+	- Volume control
+	- Fan control and monitoring: fan speed, fan enable/disable
+	- WAN enable and disable
+	- UWB enable and disable
+	- LCD Shadow (PrivacyGuard) enable and disable
+	- Lap mode sensor
+	- Setting keyboard language
+	- WWAN Antenna type
+	- Auxmac
+	- Hardware damage detection capability
+
+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 ACPI tables, using the "acpidump" utility
+	- a copy of the output of dmidecode, with serial numbers
+	  and UUIDs masked off
+	- 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, look for the CONFIG_THINKPAD_ACPI Kconfig option.
+It is located on the menu path: "Device Drivers" -> "X86 Platform
+Specific Device Drivers" -> "ThinkPad ACPI Laptop Extras".
+
+
+Features
+--------
+
+The driver exports two different interfaces to userspace, which can be
+used to access the features it provides.  One is a legacy procfs-based
+interface, which will be removed at some time in the future.  The other
+is a new sysfs-based interface which is not complete yet.
+
+The procfs interface creates the /proc/acpi/ibm directory.  There is a
+file under that directory for each feature it supports.  The procfs
+interface is mostly frozen, and will change very little if at all: it
+will not be extended to add any new functionality in the driver, instead
+all new functionality will be implemented on the sysfs interface.
+
+The sysfs interface tries to blend in the generic Linux sysfs subsystems
+and classes as much as possible.  Since some of these subsystems are not
+yet ready or stabilized, it is expected that this interface will change,
+and any and all userspace programs must deal with it.
+
+
+Notes about the sysfs interface
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Unlike what was done with the procfs interface, correctness when talking
+to the sysfs interfaces will be enforced, as will correctness in the
+thinkpad-acpi's implementation of sysfs interfaces.
+
+Also, any bugs in the thinkpad-acpi sysfs driver code or in the
+thinkpad-acpi's implementation of the sysfs interfaces will be fixed for
+maximum correctness, even if that means changing an interface in
+non-compatible ways.  As these interfaces mature both in the kernel and
+in thinkpad-acpi, such changes should become quite rare.
+
+Applications interfacing to the thinkpad-acpi sysfs interfaces must
+follow all sysfs guidelines and correctly process all errors (the sysfs
+interface makes extensive use of errors).  File descriptors and open /
+close operations to the sysfs inodes must also be properly implemented.
+
+The version of thinkpad-acpi's sysfs interface is exported by the driver
+as a driver attribute (see below).
+
+Sysfs driver attributes are on the driver's sysfs attribute space,
+for 2.6.23+ this is /sys/bus/platform/drivers/thinkpad_acpi/ and
+/sys/bus/platform/drivers/thinkpad_hwmon/
+
+Sysfs device attributes are on the thinkpad_acpi device sysfs attribute
+space, for 2.6.23+ this is /sys/devices/platform/thinkpad_acpi/.
+
+Sysfs device attributes for the sensors and fan are on the
+thinkpad_hwmon device's sysfs attribute space, but you should locate it
+looking for a hwmon device with the name attribute of "thinkpad", or
+better yet, through libsensors. For 4.14+ sysfs attributes were moved to the
+hwmon device (/sys/bus/platform/devices/thinkpad_hwmon/hwmon/hwmon? or
+/sys/class/hwmon/hwmon?).
+
+Driver version
+--------------
+
+procfs: /proc/acpi/ibm/driver
+
+sysfs driver attribute: version
+
+The driver name and version. No commands can be written to this file.
+
+
+Sysfs interface version
+-----------------------
+
+sysfs driver attribute: interface_version
+
+Version of the thinkpad-acpi sysfs interface, as an unsigned long
+(output in hex format: 0xAAAABBCC), where:
+
+	AAAA
+	  - major revision
+	BB
+	  - minor revision
+	CC
+	  - bugfix revision
+
+The sysfs interface version changelog for the driver can be found at the
+end of this document.  Changes to the sysfs interface done by the kernel
+subsystems are not documented here, nor are they tracked by this
+attribute.
+
+Changes to the thinkpad-acpi sysfs interface are only considered
+non-experimental when they are submitted to Linux mainline, at which
+point the changes in this interface are documented and interface_version
+may be updated.  If you are using any thinkpad-acpi features not yet
+sent to mainline for merging, you do so on your own risk: these features
+may disappear, or be implemented in a different and incompatible way by
+the time they are merged in Linux mainline.
+
+Changes that are backwards-compatible by nature (e.g. the addition of
+attributes that do not change the way the other attributes work) do not
+always warrant an update of interface_version.  Therefore, one must
+expect that an attribute might not be there, and deal with it properly
+(an attribute not being there *is* a valid way to make it clear that a
+feature is not available in sysfs).
+
+
+Hot keys
+--------
+
+procfs: /proc/acpi/ibm/hotkey
+
+sysfs device attribute: hotkey_*
+
+In a ThinkPad, the ACPI HKEY handler is responsible for communicating
+some important events and also keyboard hot key presses to the operating
+system.  Enabling the hotkey functionality of thinkpad-acpi signals the
+firmware that such a driver is present, and modifies how the ThinkPad
+firmware will behave in many situations.
+
+The driver enables the HKEY ("hot key") event reporting automatically
+when loaded, and disables it when it is removed.
+
+The driver will report HKEY events in the following format::
+
+	ibm/hotkey HKEY 00000080 0000xxxx
+
+Some of these events refer to hot key presses, but not all of them.
+
+The driver will generate events over the input layer for hot keys and
+radio switches, and over the ACPI netlink layer for other events.  The
+input layer support accepts the standard IOCTLs to remap the keycodes
+assigned to each hot key.
+
+The hot key bit mask allows some control over which hot keys generate
+events.  If a key is "masked" (bit set to 0 in the mask), the firmware
+will handle it.  If it is "unmasked", it signals the firmware that
+thinkpad-acpi would prefer to handle it, if the firmware would be so
+kind to allow it (and it often doesn't!).
+
+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.  Some models do not support the mask at all.  The behaviour
+of the mask is, therefore, highly dependent on the ThinkPad model.
+
+The driver will filter out any unmasked hotkeys, so even if the firmware
+doesn't allow disabling an specific hotkey, the driver will not report
+events for unmasked hotkeys.
+
+Note that unmasking some keys prevents their default behavior.  For
+example, if Fn+F5 is unmasked, that key will no longer enable/disable
+Bluetooth by itself in firmware.
+
+Note also that not all Fn key combinations are supported through ACPI
+depending on the ThinkPad model and firmware version.  On those
+ThinkPads, it is still possible to support some extra hotkeys by
+polling the "CMOS NVRAM" at least 10 times per second.  The driver
+attempts to enables this functionality automatically when required.
+
+procfs notes
+^^^^^^^^^^^^
+
+The following commands can be written to the /proc/acpi/ibm/hotkey file::
+
+	echo 0xffffffff > /proc/acpi/ibm/hotkey -- enable all hot keys
+	echo 0 > /proc/acpi/ibm/hotkey -- disable all possible hot keys
+	... any other 8-hex-digit mask ...
+	echo reset > /proc/acpi/ibm/hotkey -- restore the recommended mask
+
+The following commands have been deprecated and will cause the kernel
+to log a warning::
+
+	echo enable > /proc/acpi/ibm/hotkey -- does nothing
+	echo disable > /proc/acpi/ibm/hotkey -- returns an error
+
+The procfs interface does not support NVRAM polling control.  So as to
+maintain maximum bug-to-bug compatibility, it does not report any masks,
+nor does it allow one to manipulate the hot key mask when the firmware
+does not support masks at all, even if NVRAM polling is in use.
+
+sysfs notes
+^^^^^^^^^^^
+
+	hotkey_bios_enabled:
+		DEPRECATED, WILL BE REMOVED SOON.
+
+		Returns 0.
+
+	hotkey_bios_mask:
+		DEPRECATED, DON'T USE, WILL BE REMOVED IN THE FUTURE.
+
+		Returns the hot keys mask when thinkpad-acpi was loaded.
+		Upon module unload, the hot keys mask will be restored
+		to this value.   This is always 0x80c, because those are
+		the hotkeys that were supported by ancient firmware
+		without mask support.
+
+	hotkey_enable:
+		DEPRECATED, WILL BE REMOVED SOON.
+
+		0: returns -EPERM
+		1: does nothing
+
+	hotkey_mask:
+		bit mask to enable reporting (and depending on
+		the firmware, ACPI event generation) for each hot key
+		(see above).  Returns the current status of the hot keys
+		mask, and allows one to modify it.
+
+	hotkey_all_mask:
+		bit mask that should enable event reporting for all
+		supported hot keys, when echoed to hotkey_mask above.
+		Unless you know which events need to be handled
+		passively (because the firmware *will* handle them
+		anyway), do *not* use hotkey_all_mask.  Use
+		hotkey_recommended_mask, instead. You have been warned.
+
+	hotkey_recommended_mask:
+		bit mask that should enable event reporting for all
+		supported hot keys, except those which are always
+		handled by the firmware anyway.  Echo it to
+		hotkey_mask above, to use.  This is the default mask
+		used by the driver.
+
+	hotkey_source_mask:
+		bit mask that selects which hot keys will the driver
+		poll the NVRAM for.  This is auto-detected by the driver
+		based on the capabilities reported by the ACPI firmware,
+		but it can be overridden at runtime.
+
+		Hot keys whose bits are set in hotkey_source_mask are
+		polled for in NVRAM, and reported as hotkey events if
+		enabled in hotkey_mask.  Only a few hot keys are
+		available through CMOS NVRAM polling.
+
+		Warning: when in NVRAM mode, the volume up/down/mute
+		keys are synthesized according to changes in the mixer,
+		which uses a single volume up or volume down hotkey
+		press to unmute, as per the ThinkPad volume mixer user
+		interface.  When in ACPI event mode, volume up/down/mute
+		events are reported by the firmware and can behave
+		differently (and that behaviour changes with firmware
+		version -- not just with firmware models -- as well as
+		OSI(Linux) state).
+
+	hotkey_poll_freq:
+		frequency in Hz for hot key polling. It must be between
+		0 and 25 Hz.  Polling is only carried out when strictly
+		needed.
+
+		Setting hotkey_poll_freq to zero disables polling, and
+		will cause hot key presses that require NVRAM polling
+		to never be reported.
+
+		Setting hotkey_poll_freq too low may cause repeated
+		pressings of the same hot key to be misreported as a
+		single key press, or to not even be detected at all.
+		The recommended polling frequency is 10Hz.
+
+	hotkey_radio_sw:
+		If the ThinkPad has a hardware radio switch, this
+		attribute will read 0 if the switch is in the "radios
+		disabled" position, and 1 if the switch is in the
+		"radios enabled" position.
+
+		This attribute has poll()/select() support.
+
+	hotkey_tablet_mode:
+		If the ThinkPad has tablet capabilities, this attribute
+		will read 0 if the ThinkPad is in normal mode, and
+		1 if the ThinkPad is in tablet mode.
+
+		This attribute has poll()/select() support.
+
+	wakeup_reason:
+		Set to 1 if the system is waking up because the user
+		requested a bay ejection.  Set to 2 if the system is
+		waking up because the user requested the system to
+		undock.  Set to zero for normal wake-ups or wake-ups
+		due to unknown reasons.
+
+		This attribute has poll()/select() support.
+
+	wakeup_hotunplug_complete:
+		Set to 1 if the system was waken up because of an
+		undock or bay ejection request, and that request
+		was successfully completed.  At this point, it might
+		be useful to send the system back to sleep, at the
+		user's choice.  Refer to HKEY events 0x4003 and
+		0x3003, below.
+
+		This attribute has poll()/select() support.
+
+input layer notes
+^^^^^^^^^^^^^^^^^
+
+A Hot key is mapped to a single input layer EV_KEY event, possibly
+followed by an EV_MSC MSC_SCAN event that shall contain that key's scan
+code.  An EV_SYN event will always be generated to mark the end of the
+event block.
+
+Do not use the EV_MSC MSC_SCAN events to process keys.  They are to be
+used as a helper to remap keys, only.  They are particularly useful when
+remapping KEY_UNKNOWN keys.
+
+The events are available in an input device, with the following id:
+
+	==============  ==============================
+	Bus		BUS_HOST
+	vendor		0x1014 (PCI_VENDOR_ID_IBM)  or
+			0x17aa (PCI_VENDOR_ID_LENOVO)
+	product		0x5054 ("TP")
+	version		0x4101
+	==============  ==============================
+
+The version will have its LSB incremented if the keymap changes in a
+backwards-compatible way.  The MSB shall always be 0x41 for this input
+device.  If the MSB is not 0x41, do not use the device as described in
+this section, as it is either something else (e.g. another input device
+exported by a thinkpad driver, such as HDAPS) or its functionality has
+been changed in a non-backwards compatible way.
+
+Adding other event types for other functionalities shall be considered a
+backwards-compatible change for this input device.
+
+Thinkpad-acpi Hot Key event map (version 0x4101):
+
+=======	=======	==============	==============================================
+ACPI	Scan
+event	code	Key		Notes
+=======	=======	==============	==============================================
+0x1001	0x00	FN+F1		-
+
+0x1002	0x01	FN+F2		IBM: battery (rare)
+				Lenovo: Screen lock
+
+0x1003	0x02	FN+F3		Many IBM models always report
+				this hot key, even with hot keys
+				disabled or with Fn+F3 masked
+				off
+				IBM: screen lock, often turns
+				off the ThinkLight as side-effect
+				Lenovo: battery
+
+0x1004	0x03	FN+F4		Sleep button (ACPI sleep button
+				semantics, i.e. sleep-to-RAM).
+				It always generates some kind
+				of event, either the hot key
+				event or an ACPI sleep button
+				event. The firmware may
+				refuse to generate further FN+F4
+				key presses until a S3 or S4 ACPI
+				sleep cycle is performed or some
+				time passes.
+
+0x1005	0x04	FN+F5		Radio.  Enables/disables
+				the internal Bluetooth hardware
+				and W-WAN card if left in control
+				of the firmware.  Does not affect
+				the WLAN card.
+				Should be used to turn on/off all
+				radios (Bluetooth+W-WAN+WLAN),
+				really.
+
+0x1006	0x05	FN+F6		-
+
+0x1007	0x06	FN+F7		Video output cycle.
+				Do you feel lucky today?
+
+0x1008	0x07	FN+F8		IBM: toggle screen expand
+				Lenovo: configure UltraNav,
+				or toggle screen expand.
+				On 2024 platforms replaced by
+				0x131f (see below) and on newer
+				platforms (2025 +) keycode is
+				replaced by 0x1401 (see below).
+
+0x1009	0x08	FN+F9		-
+
+...	...	...		...
+
+0x100B	0x0A	FN+F11		-
+
+0x100C	0x0B	FN+F12		Sleep to disk.  You are always
+				supposed to handle it yourself,
+				either through the ACPI event,
+				or through a hotkey event.
+				The firmware may refuse to
+				generate further FN+F12 key
+				press events until a S3 or S4
+				ACPI sleep cycle is performed,
+				or some time passes.
+
+0x100D	0x0C	FN+BACKSPACE	-
+0x100E	0x0D	FN+INSERT	-
+0x100F	0x0E	FN+DELETE	-
+
+0x1010	0x0F	FN+HOME		Brightness up.  This key is
+				always handled by the firmware
+				in IBM ThinkPads, even when
+				unmasked.  Just leave it alone.
+				For Lenovo ThinkPads with a new
+				BIOS, it has to be handled either
+				by the ACPI OSI, or by userspace.
+				The driver does the right thing,
+				never mess with this.
+0x1011	0x10	FN+END		Brightness down.  See brightness
+				up for details.
+
+0x1012	0x11	FN+PGUP		ThinkLight toggle.  This key is
+				always handled by the firmware,
+				even when unmasked.
+
+0x1013	0x12	FN+PGDOWN	-
+
+0x1014	0x13	FN+SPACE	Zoom key
+
+0x1015	0x14	VOLUME UP	Internal mixer volume up. This
+				key is always handled by the
+				firmware, even when unmasked.
+				NOTE: Lenovo seems to be changing
+				this.
+0x1016	0x15	VOLUME DOWN	Internal mixer volume up. This
+				key is always handled by the
+				firmware, even when unmasked.
+				NOTE: Lenovo seems to be changing
+				this.
+0x1017	0x16	MUTE		Mute internal mixer. This
+				key is always handled by the
+				firmware, even when unmasked.
+
+0x1018	0x17	THINKPAD	ThinkPad/Access IBM/Lenovo key
+
+0x1019	0x18	unknown
+
+0x131f	...	FN+F8		Platform Mode change (2024 systems).
+				Implemented in driver.
+
+0x1401	...	FN+F8		Platform Mode change (2025 + systems).
+				Implemented in driver.
+...	...	...
+
+0x1020	0x1F	unknown
+=======	=======	==============	==============================================
+
+The ThinkPad firmware does not allow one to differentiate when most hot
+keys are pressed or released (either that, or we don't know how to, yet).
+For these keys, the driver generates a set of events for a key press and
+immediately issues the same set of events for a key release.  It is
+unknown by the driver if the ThinkPad firmware triggered these events on
+hot key press or release, but the firmware will do it for either one, not
+both.
+
+If a key is mapped to KEY_RESERVED, it generates no input events at all.
+If a key is mapped to KEY_UNKNOWN, it generates an input event that
+includes an scan code.  If a key is mapped to anything else, it will
+generate input device EV_KEY events.
+
+In addition to the EV_KEY events, thinkpad-acpi may also issue EV_SW
+events for switches:
+
+==============	==============================================
+SW_RFKILL_ALL	T60 and later hardware rfkill rocker switch
+SW_TABLET_MODE	Tablet ThinkPads HKEY events 0x5009 and 0x500A
+==============	==============================================
+
+Non hotkey ACPI HKEY event map
+------------------------------
+
+Events that are never propagated by the driver:
+
+======		==================================================
+0x2304		System is waking up from suspend to undock
+0x2305		System is waking up from suspend to eject bay
+0x2404		System is waking up from hibernation to undock
+0x2405		System is waking up from hibernation to eject bay
+0x5001		Lid closed
+0x5002		Lid opened
+0x5009		Tablet swivel: switched to tablet mode
+0x500A		Tablet swivel: switched to normal mode
+0x5010		Brightness level changed/control event
+0x6000		KEYBOARD: Numlock key pressed
+0x6005		KEYBOARD: Fn key pressed (TO BE VERIFIED)
+0x7000		Radio Switch may have changed state
+======		==================================================
+
+
+Events that are propagated by the driver to userspace:
+
+======		=====================================================
+0x2313		ALARM: System is waking up from suspend because
+		the battery is nearly empty
+0x2413		ALARM: System is waking up from hibernation because
+		the battery is nearly empty
+0x3003		Bay ejection (see 0x2x05) complete, can sleep again
+0x3006		Bay hotplug request (hint to power up SATA link when
+		the optical drive tray is ejected)
+0x4003		Undocked (see 0x2x04), can sleep again
+0x4010		Docked into hotplug port replicator (non-ACPI dock)
+0x4011		Undocked from hotplug port replicator (non-ACPI dock)
+0x500B		Tablet pen inserted into its storage bay
+0x500C		Tablet pen removed from its storage bay
+0x6011		ALARM: battery is too hot
+0x6012		ALARM: battery is extremely hot
+0x6021		ALARM: a sensor is too hot
+0x6022		ALARM: a sensor is extremely hot
+0x6030		System thermal table changed
+0x6032		Thermal Control command set completion  (DYTC, Windows)
+0x6040		Nvidia Optimus/AC adapter related (TO BE VERIFIED)
+0x60C0		X1 Yoga 2016, Tablet mode status changed
+0x60F0		Thermal Transformation changed (GMTS, Windows)
+======		=====================================================
+
+Battery nearly empty alarms are a last resort attempt to get the
+operating system to hibernate or shutdown cleanly (0x2313), or shutdown
+cleanly (0x2413) before power is lost.  They must be acted upon, as the
+wake up caused by the firmware will have negated most safety nets...
+
+When any of the "too hot" alarms happen, according to Lenovo the user
+should suspend or hibernate the laptop (and in the case of battery
+alarms, unplug the AC adapter) to let it cool down.  These alarms do
+signal that something is wrong, they should never happen on normal
+operating conditions.
+
+The "extremely hot" alarms are emergencies.  According to Lenovo, the
+operating system is to force either an immediate suspend or hibernate
+cycle, or a system shutdown.  Obviously, something is very wrong if this
+happens.
+
+
+Brightness hotkey notes
+^^^^^^^^^^^^^^^^^^^^^^^
+
+Don't mess with the brightness hotkeys in a Thinkpad.  If you want
+notifications for OSD, use the sysfs backlight class event support.
+
+The driver will issue KEY_BRIGHTNESS_UP and KEY_BRIGHTNESS_DOWN events
+automatically for the cases were userspace has to do something to
+implement brightness changes.  When you override these events, you will
+either fail to handle properly the ThinkPads that require explicit
+action to change backlight brightness, or the ThinkPads that require
+that no action be taken to work properly.
+
+
+Bluetooth
+---------
+
+procfs: /proc/acpi/ibm/bluetooth
+
+sysfs device attribute: bluetooth_enable (deprecated)
+
+sysfs rfkill class: switch "tpacpi_bluetooth_sw"
+
+This feature shows the presence and current state of a ThinkPad
+Bluetooth device in the internal ThinkPad CDC slot.
+
+If the ThinkPad supports it, the Bluetooth state is stored in NVRAM,
+so it is kept across reboots and power-off.
+
+Procfs notes
+^^^^^^^^^^^^
+
+If Bluetooth is installed, the following commands can be used::
+
+	echo enable > /proc/acpi/ibm/bluetooth
+	echo disable > /proc/acpi/ibm/bluetooth
+
+Sysfs notes
+^^^^^^^^^^^
+
+	If the Bluetooth CDC card is installed, it can be enabled /
+	disabled through the "bluetooth_enable" thinkpad-acpi device
+	attribute, and its current status can also be queried.
+
+	enable:
+
+		- 0: disables Bluetooth / Bluetooth is disabled
+		- 1: enables Bluetooth / Bluetooth is enabled.
+
+	Note: this interface has been superseded by the	generic rfkill
+	class.  It has been deprecated, and it will be removed in year
+	2010.
+
+	rfkill controller switch "tpacpi_bluetooth_sw": refer to
+	Documentation/driver-api/rfkill.rst for details.
+
+
+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
+
+NOTE:
+  Access to this feature is restricted to processes owning the
+  CAP_SYS_ADMIN capability for safety reasons, as it can interact badly
+  enough with some versions of X.org to crash it.
+
+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 simulates 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.
+
+UPDATE: refer to https://bugs.freedesktop.org/show_bug.cgi?id=2000
+
+
+ThinkLight control
+------------------
+
+procfs: /proc/acpi/ibm/light
+
+sysfs attributes: as per LED class, for the "tpacpi::thinklight" LED
+
+procfs notes
+^^^^^^^^^^^^
+
+The ThinkLight status can be read and set through the procfs interface.  A
+few models which do not make the status available will show the ThinkLight
+status as "unknown". The available commands are::
+
+	echo on  > /proc/acpi/ibm/light
+	echo off > /proc/acpi/ibm/light
+
+sysfs notes
+^^^^^^^^^^^
+
+The ThinkLight sysfs interface is documented by the LED class
+documentation, in Documentation/leds/leds-class.rst.  The ThinkLight LED name
+is "tpacpi::thinklight".
+
+Due to limitations in the sysfs LED class, if the status of the ThinkLight
+cannot be read or if it is unknown, thinkpad-acpi will report it as "off".
+It is impossible to know if the status returned through sysfs is valid.
+
+
+CMOS/UCMS control
+-----------------
+
+procfs: /proc/acpi/ibm/cmos
+
+sysfs device attribute: cmos_command
+
+This feature is mostly used internally by the ACPI firmware to keep the legacy
+CMOS NVRAM bits in sync with the current machine state, and to record this
+state so that the ThinkPad will retain such settings across reboots.
+
+Some of these commands actually perform actions in some ThinkPad models, but
+this is expected to disappear more and more in newer models.  As an example, in
+a T43 and in a X40, commands 12 and 13 still control the ThinkLight state for
+real, but commands 0 to 2 don't control the mixer anymore (they have been
+phased out) and just update the NVRAM.
+
+The range of valid cmos command numbers is 0 to 21, but not all have an
+effect and the behavior varies from model to model.  Here is the behavior
+on the X40 (tpb is the ThinkPad Buttons utility):
+
+	- 0 - Related to "Volume down" key press
+	- 1 - Related to "Volume up" key press
+	- 2 - Related to "Mute on" key press
+	- 3 - Related to "Access IBM" key press
+	- 4 - Related to "LCD brightness up" key press
+	- 5 - Related to "LCD brightness down" key press
+	- 11 - Related to "toggle screen expansion" key press/function
+	- 12 - Related to "ThinkLight on"
+	- 13 - Related to "ThinkLight off"
+	- 14 - Related to "ThinkLight" key press (toggle ThinkLight)
+
+The cmos command interface is prone to firmware split-brain problems, as
+in newer ThinkPads it is just a compatibility layer.  Do not use it, it is
+exported just as a debug tool.
+
+
+LED control
+-----------
+
+procfs: /proc/acpi/ibm/led
+sysfs attributes: as per LED class, see below for names
+
+Some of the LED indicators can be controlled through this feature.  On
+some older ThinkPad models, it is possible to query the status of the
+LED indicators as well.  Newer ThinkPads cannot query the real status
+of the LED indicators.
+
+Because misuse of the LEDs could induce an unaware user to perform
+dangerous actions (like undocking or ejecting a bay device while the
+buses are still active), or mask an important alarm (such as a nearly
+empty battery, or a broken battery), access to most LEDs is
+restricted.
+
+Unrestricted access to all LEDs requires that thinkpad-acpi be
+compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
+Distributions must never enable this option.  Individual users that
+are aware of the consequences are welcome to enabling it.
+
+Audio mute and microphone mute LEDs are supported, but currently not
+visible to userspace. They are used by the snd-hda-intel audio driver.
+
+procfs notes
+^^^^^^^^^^^^
+
+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> range is 0 to 15. The set of LEDs that can be
+controlled varies from model to model. Here is the common ThinkPad
+mapping:
+
+	- 0 - power
+	- 1 - battery (orange)
+	- 2 - battery (green)
+	- 3 - UltraBase/dock
+	- 4 - UltraBay
+	- 5 - UltraBase battery slot
+	- 6 - (unknown)
+	- 7 - standby
+	- 8 - dock status 1
+	- 9 - dock status 2
+	- 10, 11 - (unknown)
+	- 12 - thinkvantage
+	- 13, 14, 15 - (unknown)
+
+All of the above can be turned on and off and can be made to blink.
+
+sysfs notes
+^^^^^^^^^^^
+
+The ThinkPad LED sysfs interface is described in detail by the LED class
+documentation, in Documentation/leds/leds-class.rst.
+
+The LEDs are named (in LED ID order, from 0 to 12):
+"tpacpi::power", "tpacpi:orange:batt", "tpacpi:green:batt",
+"tpacpi::dock_active", "tpacpi::bay_active", "tpacpi::dock_batt",
+"tpacpi::unknown_led", "tpacpi::standby", "tpacpi::dock_status1",
+"tpacpi::dock_status2", "tpacpi::unknown_led2", "tpacpi::unknown_led3",
+"tpacpi::thinkvantage".
+
+Due to limitations in the sysfs LED class, if the status of the LED
+indicators cannot be read due to an error, thinkpad-acpi will report it as
+a brightness of zero (same as LED off).
+
+If the thinkpad firmware doesn't support reading the current status,
+trying to read the current LED brightness will just return whatever
+brightness was last written to that attribute.
+
+These LEDs can blink using hardware acceleration.  To request that a
+ThinkPad indicator LED should blink in hardware accelerated mode, use the
+"timer" trigger, and leave the delay_on and delay_off parameters set to
+zero (to request hardware acceleration autodetection).
+
+LEDs that are known not to exist in a given ThinkPad model are not
+made available through the sysfs interface.  If you have a dock and you
+notice there are LEDs listed for your ThinkPad that do not exist (and
+are not in the dock), or if you notice that there are missing LEDs,
+a report to ibm-acpi-devel@lists.sourceforge.net is appreciated.
+
+
+ACPI sounds -- /proc/acpi/ibm/beep
+----------------------------------
+
+The BEEP method is used internally by the ACPI firmware to provide
+audible alerts in various situations. This feature allows the same
+sounds to be triggered manually.
+
+The commands are non-negative integer numbers::
+
+	echo <number> >/proc/acpi/ibm/beep
+
+The valid <number> range is 0 to 17. Not all numbers trigger sounds
+and the sounds vary from model to model. Here is the behavior on the
+X40:
+
+	- 0 - stop a sound in progress (but use 17 to stop 16)
+	- 2 - two beeps, pause, third beep ("low battery")
+	- 3 - single beep
+	- 4 - high, followed by low-pitched beep ("unable")
+	- 5 - single beep
+	- 6 - very high, followed by high-pitched beep ("AC/DC")
+	- 7 - high-pitched beep
+	- 9 - three short beeps
+	- 10 - very long beep
+	- 12 - low-pitched beep
+	- 15 - three high-pitched beeps repeating constantly, stop with 0
+	- 16 - one medium-pitched beep repeating constantly, stop with 17
+	- 17 - stop 16
+
+
+Temperature sensors
+-------------------
+
+procfs: /proc/acpi/ibm/thermal
+
+sysfs device attributes: (hwmon "thinkpad") temp*_input
+
+Most ThinkPads include six or more separate temperature sensors but only
+expose the CPU temperature through the standard ACPI methods.  This
+feature shows readings from up to eight different sensors on older
+ThinkPads, and up to sixteen different sensors on newer ThinkPads.
+
+For example, on the X40, a typical output may be:
+
+temperatures:
+	42 42 45 41 36 -128 33 -128
+
+On the T43/p, a typical output may be:
+
+temperatures:
+	48 48 36 52 38 -128 31 -128 48 52 48 -128 -128 -128 -128 -128
+
+The mapping of thermal sensors to physical locations varies depending on
+system-board model (and thus, on ThinkPad model).
+
+https://thinkwiki.org/wiki/Thermal_Sensors is a public wiki page that
+tries to track down these locations for various models.
+
+Most (newer?) models seem to follow this pattern:
+
+- 1:  CPU
+- 2:  (depends on model)
+- 3:  (depends on model)
+- 4:  GPU
+- 5:  Main battery: main sensor
+- 6:  Bay battery: main sensor
+- 7:  Main battery: secondary sensor
+- 8:  Bay battery: secondary sensor
+- 9-15: (depends on model)
+
+For the R51 (source: Thomas Gruber):
+
+- 2:  Mini-PCI
+- 3:  Internal HDD
+
+For the T43, T43/p (source: Shmidoax/Thinkwiki.org)
+https://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_T43.2C_T43p
+
+- 2:  System board, left side (near PCMCIA slot), reported as HDAPS temp
+- 3:  PCMCIA slot
+- 9:  MCH (northbridge) to DRAM Bus
+- 10: Clock-generator, mini-pci card and ICH (southbridge), under Mini-PCI
+      card, under touchpad
+- 11: Power regulator, underside of system board, below F2 key
+
+The A31 has a very atypical layout for the thermal sensors
+(source: Milos Popovic, https://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_A31)
+
+- 1:  CPU
+- 2:  Main Battery: main sensor
+- 3:  Power Converter
+- 4:  Bay Battery: main sensor
+- 5:  MCH (northbridge)
+- 6:  PCMCIA/ambient
+- 7:  Main Battery: secondary sensor
+- 8:  Bay Battery: secondary sensor
+
+
+Procfs notes
+^^^^^^^^^^^^
+
+	Readings from sensors that are not available return -128.
+	No commands can be written to this file.
+
+Sysfs notes
+^^^^^^^^^^^
+
+	Sensors that are not available return the ENXIO error.  This
+	status may change at runtime, as there are hotplug thermal
+	sensors, like those inside the batteries and docks.
+
+	thinkpad-acpi thermal sensors are reported through the hwmon
+	subsystem, and follow all of the hwmon guidelines at
+	Documentation/hwmon.
+
+EXPERIMENTAL: Embedded controller register dump
+-----------------------------------------------
+
+This feature is not included in the thinkpad driver anymore.
+Instead the EC can be accessed through /sys/kernel/debug/ec with
+a userspace tool which can be found here:
+ftp://ftp.suse.com/pub/people/trenn/sources/ec
+
+Use it to determine the register holding the fan
+speed on some models. To do that, do the following:
+
+	- make sure the battery is fully charged
+	- make sure the fan is running
+	- use above mentioned tool to read out the EC
+
+Often fan and temperature values vary between
+readings. Since temperatures don't change vary fast, you can take
+several quick dumps to eliminate them.
+
+You can use a similar method to figure out the meaning of other
+embedded controller registers - e.g. make sure nothing else changes
+except the charging or discharging battery to determine which
+registers contain the current battery capacity, etc. If you experiment
+with this, do send me your results (including some complete dumps with
+a description of the conditions when they were taken.)
+
+
+LCD brightness control
+----------------------
+
+procfs: /proc/acpi/ibm/brightness
+
+sysfs backlight device "thinkpad_screen"
+
+This feature allows software control of the LCD brightness on ThinkPad
+models which don't have a hardware brightness slider.
+
+It has some limitations: the LCD backlight cannot be actually turned
+on or off by this interface, it just controls the backlight brightness
+level.
+
+On IBM (and some of the earlier Lenovo) ThinkPads, the backlight control
+has eight brightness levels, ranging from 0 to 7.  Some of the levels
+may not be distinct.  Later Lenovo models that implement the ACPI
+display backlight brightness control methods have 16 levels, ranging
+from 0 to 15.
+
+For IBM ThinkPads, there are two interfaces to the firmware for direct
+brightness control, EC and UCMS (or CMOS).  To select which one should be
+used, use the brightness_mode module parameter: brightness_mode=1 selects
+EC mode, brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
+mode with NVRAM backing (so that brightness changes are remembered across
+shutdown/reboot).
+
+The driver tries to select which interface to use from a table of
+defaults for each ThinkPad model.  If it makes a wrong choice, please
+report this as a bug, so that we can fix it.
+
+Lenovo ThinkPads only support brightness_mode=2 (UCMS).
+
+When display backlight brightness controls are available through the
+standard ACPI interface, it is best to use it instead of this direct
+ThinkPad-specific interface.  The driver will disable its native
+backlight brightness control interface if it detects that the standard
+ACPI interface is available in the ThinkPad.
+
+If you want to use the thinkpad-acpi backlight brightness control
+instead of the generic ACPI video backlight brightness control for some
+reason, you should use the acpi_backlight=vendor kernel parameter.
+
+The brightness_enable module parameter can be used to control whether
+the LCD brightness control feature will be enabled when available.
+brightness_enable=0 forces it to be disabled.  brightness_enable=1
+forces it to be enabled when available, even if the standard ACPI
+interface is also available.
+
+Procfs notes
+^^^^^^^^^^^^
+
+The available commands are::
+
+	echo up   >/proc/acpi/ibm/brightness
+	echo down >/proc/acpi/ibm/brightness
+	echo 'level <level>' >/proc/acpi/ibm/brightness
+
+Sysfs notes
+^^^^^^^^^^^
+
+The interface is implemented through the backlight sysfs class, which is
+poorly documented at this time.
+
+Locate the thinkpad_screen device under /sys/class/backlight, and inside
+it there will be the following attributes:
+
+	max_brightness:
+		Reads the maximum brightness the hardware can be set to.
+		The minimum is always zero.
+
+	actual_brightness:
+		Reads what brightness the screen is set to at this instant.
+
+	brightness:
+		Writes request the driver to change brightness to the
+		given value.  Reads will tell you what brightness the
+		driver is trying to set the display to when "power" is set
+		to zero and the display has not been dimmed by a kernel
+		power management event.
+
+	power:
+		power management mode, where 0 is "display on", and 1 to 3
+		will dim the display backlight to brightness level 0
+		because thinkpad-acpi cannot really turn the backlight
+		off.  Kernel power management events can temporarily
+		increase the current power management level, i.e. they can
+		dim the display.
+
+
+WARNING:
+
+    Whatever you do, do NOT ever call thinkpad-acpi backlight-level change
+    interface and the ACPI-based backlight level change interface
+    (available on newer BIOSes, and driven by the Linux ACPI video driver)
+    at the same time.  The two will interact in bad ways, do funny things,
+    and maybe reduce the life of the backlight lamps by needlessly kicking
+    its level up and down at every change.
+
+
+Volume control (Console Audio control)
+--------------------------------------
+
+procfs: /proc/acpi/ibm/volume
+
+ALSA: "ThinkPad Console Audio Control", default ID: "ThinkPadEC"
+
+NOTE: by default, the volume control interface operates in read-only
+mode, as it is supposed to be used for on-screen-display purposes.
+The read/write mode can be enabled through the use of the
+"volume_control=1" module parameter.
+
+NOTE: distros are urged to not enable volume_control by default, this
+should be done by the local admin only.  The ThinkPad UI is for the
+console audio control to be done through the volume keys only, and for
+the desktop environment to just provide on-screen-display feedback.
+Software volume control should be done only in the main AC97/HDA
+mixer.
+
+
+About the ThinkPad Console Audio control
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+ThinkPads have a built-in amplifier and muting circuit that drives the
+console headphone and speakers.  This circuit is after the main AC97
+or HDA mixer in the audio path, and under exclusive control of the
+firmware.
+
+ThinkPads have three special hotkeys to interact with the console
+audio control: volume up, volume down and mute.
+
+It is worth noting that the normal way the mute function works (on
+ThinkPads that do not have a "mute LED") is:
+
+1. Press mute to mute.  It will *always* mute, you can press it as
+   many times as you want, and the sound will remain mute.
+
+2. Press either volume key to unmute the ThinkPad (it will _not_
+   change the volume, it will just unmute).
+
+This is a very superior design when compared to the cheap software-only
+mute-toggle solution found on normal consumer laptops:  you can be
+absolutely sure the ThinkPad will not make noise if you press the mute
+button, no matter the previous state.
+
+The IBM ThinkPads, and the earlier Lenovo ThinkPads have variable-gain
+amplifiers driving the speakers and headphone output, and the firmware
+also handles volume control for the headphone and speakers on these
+ThinkPads without any help from the operating system (this volume
+control stage exists after the main AC97 or HDA mixer in the audio
+path).
+
+The newer Lenovo models only have firmware mute control, and depend on
+the main HDA mixer to do volume control (which is done by the operating
+system).  In this case, the volume keys are filtered out for unmute
+key press (there are some firmware bugs in this area) and delivered as
+normal key presses to the operating system (thinkpad-acpi is not
+involved).
+
+
+The ThinkPad-ACPI volume control
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The preferred way to interact with the Console Audio control is the
+ALSA interface.
+
+The legacy procfs interface allows one to read the current state,
+and if volume control is enabled, accepts the following commands::
+
+	echo up   >/proc/acpi/ibm/volume
+	echo down >/proc/acpi/ibm/volume
+	echo mute >/proc/acpi/ibm/volume
+	echo unmute >/proc/acpi/ibm/volume
+	echo 'level <level>' >/proc/acpi/ibm/volume
+
+The <level> number range is 0 to 14 although not all of them may be
+distinct. To unmute the volume after the mute command, use either the
+up or down command (the level command will not unmute the volume), or
+the unmute command.
+
+You can use the volume_capabilities parameter to tell the driver
+whether your thinkpad has volume control or mute-only control:
+volume_capabilities=1 for mixers with mute and volume control,
+volume_capabilities=2 for mixers with only mute control.
+
+If the driver misdetects the capabilities for your ThinkPad model,
+please report this to ibm-acpi-devel@lists.sourceforge.net, so that we
+can update the driver.
+
+There are two strategies for volume control.  To select which one
+should be used, use the volume_mode module parameter: volume_mode=1
+selects EC mode, and volume_mode=3 selects EC mode with NVRAM backing
+(so that volume/mute changes are remembered across shutdown/reboot).
+
+The driver will operate in volume_mode=3 by default. If that does not
+work well on your ThinkPad model, please report this to
+ibm-acpi-devel@lists.sourceforge.net.
+
+The driver supports the standard ALSA module parameters.  If the ALSA
+mixer is disabled, the driver will disable all volume functionality.
+
+
+Fan control and monitoring: fan speed, fan enable/disable
+---------------------------------------------------------
+
+procfs: /proc/acpi/ibm/fan
+
+sysfs device attributes: (hwmon "thinkpad") fan1_input, pwm1, pwm1_enable, fan2_input
+
+sysfs hwmon driver attributes: fan_watchdog
+
+NOTE NOTE NOTE:
+   fan control operations are disabled by default for
+   safety reasons.  To enable them, the module parameter "fan_control=1"
+   must be given to thinkpad-acpi.
+
+This feature attempts to show the current fan speed, control mode and
+other fan data that might be available.  The speed is read directly
+from the hardware registers of the embedded controller.  This is known
+to work on later R, T, X and Z series ThinkPads but may show a bogus
+value on other models.
+
+Some Lenovo ThinkPads support a secondary fan.  This fan cannot be
+controlled separately, it shares the main fan control.
+
+Fan levels
+^^^^^^^^^^
+
+Most ThinkPad fans work in "levels" at the firmware interface.  Level 0
+stops the fan.  The higher the level, the higher the fan speed, although
+adjacent levels often map to the same fan speed.  7 is the highest
+level, where the fan reaches the maximum recommended speed.
+
+Level "auto" means the EC changes the fan level according to some
+internal algorithm, usually based on readings from the thermal sensors.
+
+There is also a "full-speed" level, also known as "disengaged" level.
+In this level, the EC disables the speed-locked closed-loop fan control,
+and drives the fan as fast as it can go, which might exceed hardware
+limits, so use this level with caution.
+
+The fan usually ramps up or down slowly from one speed to another, and
+it is normal for the EC to take several seconds to react to fan
+commands.  The full-speed level may take up to two minutes to ramp up to
+maximum speed, and in some ThinkPads, the tachometer readings go stale
+while the EC is transitioning to the full-speed level.
+
+WARNING WARNING WARNING: do not leave the fan disabled unless you are
+monitoring all of the temperature sensor readings and you are ready to
+enable it if necessary to avoid overheating.
+
+An enabled fan in level "auto" may stop spinning if the EC decides the
+ThinkPad is cool enough and doesn't need the extra airflow.  This is
+normal, and the EC will spin the fan up if the various thermal readings
+rise too much.
+
+On the X40, this seems to depend on the CPU and HDD temperatures.
+Specifically, the fan is turned on when either the CPU temperature
+climbs to 56 degrees or the HDD temperature climbs to 46 degrees.  The
+fan is turned off when the CPU temperature drops to 49 degrees and the
+HDD temperature drops to 41 degrees.  These thresholds cannot
+currently be controlled.
+
+The ThinkPad's ACPI DSDT code will reprogram the fan on its own when
+certain conditions are met.  It will override any fan programming done
+through thinkpad-acpi.
+
+The thinkpad-acpi kernel driver can be programmed to revert the fan
+level to a safe setting if userspace does not issue one of the procfs
+fan commands: "enable", "disable", "level" or "watchdog", or if there
+are no writes to pwm1_enable (or to pwm1 *if and only if* pwm1_enable is
+set to 1, manual mode) within a configurable amount of time of up to
+120 seconds.  This functionality is called fan safety watchdog.
+
+Note that the watchdog timer stops after it enables the fan.  It will be
+rearmed again automatically (using the same interval) when one of the
+above mentioned fan commands is received.  The fan watchdog is,
+therefore, not suitable to protect against fan mode changes made through
+means other than the "enable", "disable", and "level" procfs fan
+commands, or the hwmon fan control sysfs interface.
+
+Procfs notes
+^^^^^^^^^^^^
+
+The fan may be enabled or disabled with the following commands::
+
+	echo enable  >/proc/acpi/ibm/fan
+	echo disable >/proc/acpi/ibm/fan
+
+Placing a fan on level 0 is the same as disabling it.  Enabling a fan
+will try to place it in a safe level if it is too slow or disabled.
+
+The fan level can be controlled with the command::
+
+	echo 'level <level>' > /proc/acpi/ibm/fan
+
+Where <level> is an integer from 0 to 7, or one of the words "auto" or
+"full-speed" (without the quotes).  Not all ThinkPads support the "auto"
+and "full-speed" levels.  The driver accepts "disengaged" as an alias for
+"full-speed", and reports it as "disengaged" for backwards
+compatibility.
+
+On the X31 and X40 (and ONLY on those models), the fan speed can be
+controlled to a certain degree.  Once the fan is running, it can be
+forced to run faster or slower with the following command::
+
+	echo 'speed <speed>' > /proc/acpi/ibm/fan
+
+The sustainable range of fan speeds on the X40 appears to be from about
+3700 to about 7350. Values outside this range either do not have any
+effect or the fan speed eventually settles somewhere in that range.  The
+fan cannot be stopped or started with this command.  This functionality
+is incomplete, and not available through the sysfs interface.
+
+To program the safety watchdog, use the "watchdog" command::
+
+	echo 'watchdog <interval in seconds>' > /proc/acpi/ibm/fan
+
+If you want to disable the watchdog, use 0 as the interval.
+
+Sysfs notes
+^^^^^^^^^^^
+
+The sysfs interface follows the hwmon subsystem guidelines for the most
+part, and the exception is the fan safety watchdog.
+
+Writes to any of the sysfs attributes may return the EINVAL error if
+that operation is not supported in a given ThinkPad or if the parameter
+is out-of-bounds, and EPERM if it is forbidden.  They may also return
+EINTR (interrupted system call), and EIO (I/O error while trying to talk
+to the firmware).
+
+Features not yet implemented by the driver return ENOSYS.
+
+hwmon device attribute pwm1_enable:
+	- 0: PWM offline (fan is set to full-speed mode)
+	- 1: Manual PWM control (use pwm1 to set fan level)
+	- 2: Hardware PWM control (EC "auto" mode)
+	- 3: reserved (Software PWM control, not implemented yet)
+
+	Modes 0 and 2 are not supported by all ThinkPads, and the
+	driver is not always able to detect this.  If it does know a
+	mode is unsupported, it will return -EINVAL.
+
+hwmon device attribute pwm1:
+	Fan level, scaled from the firmware values of 0-7 to the hwmon
+	scale of 0-255.  0 means fan stopped, 255 means highest normal
+	speed (level 7).
+
+	This attribute only commands the fan if pmw1_enable is set to 1
+	(manual PWM control).
+
+hwmon device attribute fan1_input:
+	Fan tachometer reading, in RPM.  May go stale on certain
+	ThinkPads while the EC transitions the PWM to offline mode,
+	which can take up to two minutes.  May return rubbish on older
+	ThinkPads.
+
+hwmon device attribute fan2_input:
+	Fan tachometer reading, in RPM, for the secondary fan.
+	Available only on some ThinkPads.  If the secondary fan is
+	not installed, will always read 0.
+
+hwmon driver attribute fan_watchdog:
+	Fan safety watchdog timer interval, in seconds.  Minimum is
+	1 second, maximum is 120 seconds.  0 disables the watchdog.
+
+To stop the fan: set pwm1 to zero, and pwm1_enable to 1.
+
+To start the fan in a safe mode: set pwm1_enable to 2.  If that fails
+with EINVAL, try to set pwm1_enable to 1 and pwm1 to at least 128 (255
+would be the safest choice, though).
+
+
+WAN
+---
+
+procfs: /proc/acpi/ibm/wan
+
+sysfs device attribute: wwan_enable (deprecated)
+
+sysfs rfkill class: switch "tpacpi_wwan_sw"
+
+This feature shows the presence and current state of the built-in
+Wireless WAN device.
+
+If the ThinkPad supports it, the WWAN state is stored in NVRAM,
+so it is kept across reboots and power-off.
+
+It was tested on a Lenovo ThinkPad X60. It should probably work on other
+ThinkPad models which come with this module installed.
+
+Procfs notes
+^^^^^^^^^^^^
+
+If the W-WAN card is installed, the following commands can be used::
+
+	echo enable > /proc/acpi/ibm/wan
+	echo disable > /proc/acpi/ibm/wan
+
+Sysfs notes
+^^^^^^^^^^^
+
+	If the W-WAN card is installed, it can be enabled /
+	disabled through the "wwan_enable" thinkpad-acpi device
+	attribute, and its current status can also be queried.
+
+	enable:
+		- 0: disables WWAN card / WWAN card is disabled
+		- 1: enables WWAN card / WWAN card is enabled.
+
+	Note: this interface has been superseded by the	generic rfkill
+	class.  It has been deprecated, and it will be removed in year
+	2010.
+
+	rfkill controller switch "tpacpi_wwan_sw": refer to
+	Documentation/driver-api/rfkill.rst for details.
+
+
+LCD Shadow control
+------------------
+
+procfs: /proc/acpi/ibm/lcdshadow
+
+Some newer T480s and T490s ThinkPads provide a feature called
+PrivacyGuard. By turning this feature on, the usable vertical and
+horizontal viewing angles of the LCD can be limited (as if some privacy
+screen was applied manually in front of the display).
+
+procfs notes
+^^^^^^^^^^^^
+
+The available commands are::
+
+	echo '0' >/proc/acpi/ibm/lcdshadow
+	echo '1' >/proc/acpi/ibm/lcdshadow
+
+The first command ensures the best viewing angle and the latter one turns
+on the feature, restricting the viewing angles.
+
+
+DYTC Lapmode sensor
+-------------------
+
+sysfs: dytc_lapmode
+
+Newer thinkpads and mobile workstations have the ability to determine if
+the device is in deskmode or lapmode. This feature is used by user space
+to decide if WWAN transmission can be increased to maximum power and is
+also useful for understanding the different thermal modes available as
+they differ between desk and lap mode.
+
+The property is read-only. If the platform doesn't have support the sysfs
+class is not created.
+
+EXPERIMENTAL: UWB
+-----------------
+
+This feature is considered EXPERIMENTAL because it has not been extensively
+tested and validated in various ThinkPad models yet.  The feature may not
+work as expected. USE WITH CAUTION! To use this feature, you need to supply
+the experimental=1 parameter when loading the module.
+
+sysfs rfkill class: switch "tpacpi_uwb_sw"
+
+This feature exports an rfkill controller for the UWB device, if one is
+present and enabled in the BIOS.
+
+Sysfs notes
+^^^^^^^^^^^
+
+	rfkill controller switch "tpacpi_uwb_sw": refer to
+	Documentation/driver-api/rfkill.rst for details.
+
+
+Setting keyboard language
+-------------------------
+
+sysfs: keyboard_lang
+
+This feature is used to set keyboard language to ECFW using ASL interface.
+Fewer thinkpads models like T580 , T590 , T15 Gen 1 etc.. has "=", "(',
+")" numeric keys, which are not displaying correctly, when keyboard language
+is other than "english". This is because the default keyboard language in ECFW
+is set as "english". Hence using this sysfs, user can set the correct keyboard
+language to ECFW and then these key's will work correctly.
+
+Example of command to set keyboard language is mentioned below::
+
+        echo jp > /sys/devices/platform/thinkpad_acpi/keyboard_lang
+
+Text corresponding to keyboard layout to be set in sysfs are: be(Belgian),
+cz(Czech), da(Danish), de(German), en(English), es(Spain), et(Estonian),
+fr(French), fr-ch(French(Switzerland)), hu(Hungarian), it(Italy), jp (Japan),
+nl(Dutch), nn(Norway), pl(Polish), pt(portuguese), sl(Slovenian), sv(Sweden),
+tr(Turkey)
+
+WWAN Antenna type
+-----------------
+
+sysfs: wwan_antenna_type
+
+On some newer Thinkpads we need to set SAR value based on the antenna
+type. This interface will be used by userspace to get the antenna type
+and set the corresponding SAR value, as is required for FCC certification.
+
+The available commands are::
+
+        cat /sys/devices/platform/thinkpad_acpi/wwan_antenna_type
+
+Currently 2 antenna types are supported as mentioned below:
+- type a
+- type b
+
+The property is read-only. If the platform doesn't have support the sysfs
+class is not created.
+
+doubletap_enable
+----------------
+
+sysfs: doubletap_enable
+
+Controls whether TrackPoint doubletap events are filtered out. Doubletap is a
+feature where quickly tapping the TrackPoint twice triggers a special function key event.
+
+The available commands are::
+
+                cat /sys/devices/platform/thinkpad_acpi/doubletap_enable
+                echo 1 | sudo tee /sys/devices/platform/thinkpad_acpi/doubletap_enable
+                echo 0 | sudo tee /sys/devices/platform/thinkpad_acpi/doubletap_enable
+
+Values:
+
+	* 1 - doubletap events are processed (default)
+	* 0 - doubletap events are filtered out (ignored)
+
+	This setting can also be toggled via the Fn+doubletap hotkey.
+
+USB-C Security
+--------------
+
+sysfs: usb_c_security
+
+Reports the current state of the USB-C Security (Restricted Mode) feature
+on supported ThinkPad systems. When enabled, USB-C data connections are
+disabled while power delivery is preserved.
+
+The available command is::
+
+        cat /sys/devices/platform/thinkpad_acpi/usb_c_security
+
+Values:
+
+	* ``enabled``  - USB-C data connections are currently blocked
+	* ``disabled`` - USB-C data connections are currently allowed
+
+The attribute is read-only. The USB-C Security state can only be toggled
+via the Fn+U followed by Fn+S hotkey chord.
+
+The sysfs attribute is not created on platforms that do not support this
+feature.
+
+Auxmac
+------
+
+sysfs: auxmac
+
+Some newer Thinkpads have a feature called MAC Address Pass-through. This
+feature is implemented by the system firmware to provide a system unique MAC,
+that can override a dock or USB ethernet dongle MAC, when connected to a
+network. This property enables user-space to easily determine the MAC address
+if the feature is enabled.
+
+The values of this auxiliary MAC are:
+
+        cat /sys/devices/platform/thinkpad_acpi/auxmac
+
+If the feature is disabled, the value will be 'disabled'.
+
+This property is read-only.
+
+Adaptive keyboard
+-----------------
+
+sysfs device attribute: adaptive_kbd_mode
+
+This sysfs attribute controls the keyboard "face" that will be shown on the
+Lenovo X1 Carbon 2nd gen (2014)'s adaptive keyboard. The value can be read
+and set.
+
+- 0 = Home mode
+- 1 = Web-browser mode
+- 2 = Web-conference mode
+- 3 = Function mode
+- 4 = Layflat mode
+
+For more details about which buttons will appear depending on the mode, please
+review the laptop's user guide:
+https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles_pdf/x1carbon_2_ug_en.pdf
+
+Battery charge control
+----------------------
+
+sysfs attributes:
+/sys/class/power_supply/BAT*/charge_control_{start,end}_threshold
+
+These two attributes are created for those batteries that are supported by the
+driver. They enable the user to control the battery charge thresholds of the
+given battery. Both values may be read and set. `charge_control_start_threshold`
+accepts an integer between 0 and 99 (inclusive); this value represents a battery
+percentage level, below which charging will begin. `charge_control_end_threshold`
+accepts an integer between 1 and 100 (inclusive); this value represents a battery
+percentage level, above which charging will stop.
+
+The exact semantics of the attributes may be found in
+Documentation/ABI/testing/sysfs-class-power.
+
+Hardware damage detection capability
+------------------------------------
+
+sysfs attributes: hwdd_status, hwdd_detail
+
+Thinkpads are adding the ability to detect and report hardware damage.
+Add new sysfs interface to identify the damaged device status.
+Initial support is available for the USB-C replaceable connector.
+
+The command to check device damaged status is::
+
+        cat /sys/devices/platform/thinkpad_acpi/hwdd_status
+
+This value displays status of device damaged.
+
+- 0 = Not Damaged
+- 1 = Damaged
+
+The command to check location of damaged device is::
+
+        cat /sys/devices/platform/thinkpad_acpi/hwdd_detail
+
+This value displays location of damaged device having 1 line per damaged "item".
+For example:
+
+if no damage is detected:
+
+- No damage detected
+
+if damage detected:
+
+- TYPE-C: Base, Right side, Center port
+
+The property is read-only. If feature is not supported then sysfs
+attribute is not created.
+
+Multiple Commands, 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 thinkpad-acpi module,
+for example::
+
+	modprobe thinkpad_acpi hotkey=enable,0xffff video=auto_disable
+
+
+Enabling debugging output
+-------------------------
+
+The module takes a debug parameter which can be used to selectively
+enable various classes of debugging output, for example::
+
+	 modprobe thinkpad_acpi debug=0xffff
+
+will enable all debugging output classes.  It takes a bitmask, so
+to enable more than one output class, just add their values.
+
+	=============		======================================
+	Debug bitmask		Description
+	=============		======================================
+	0x8000			Disclose PID of userspace programs
+				accessing some functions of the driver
+	0x0001			Initialization and probing
+	0x0002			Removal
+	0x0004			RF Transmitter control (RFKILL)
+				(bluetooth, WWAN, UWB...)
+	0x0008			HKEY event interface, hotkeys
+	0x0010			Fan control
+	0x0020			Backlight brightness
+	0x0040			Audio mixer/volume control
+	=============		======================================
+
+There is also a kernel build option to enable more debugging
+information, which may be necessary to debug driver problems.
+
+The level of debugging information output by the driver can be changed
+at runtime through sysfs, using the driver attribute debug_level.  The
+attribute takes the same bitmask as the debug module parameter above.
+
+
+Force loading of module
+-----------------------
+
+If thinkpad-acpi refuses to detect your ThinkPad, you can try to specify
+the module parameter force_load=1.  Regardless of whether this works or
+not, please contact ibm-acpi-devel@lists.sourceforge.net with a report.
+
+
+Sysfs interface changelog
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+=========	===============================================================
+0x000100:	Initial sysfs support, as a single platform driver and
+		device.
+0x000200:	Hot key support for 32 hot keys, and radio slider switch
+		support.
+0x010000:	Hot keys are now handled by default over the input
+		layer, the radio switch generates input event EV_RADIO,
+		and the driver enables hot key handling by default in
+		the firmware.
+
+0x020000:	ABI fix: added a separate hwmon platform device and
+		driver, which must be located by name (thinkpad)
+		and the hwmon class for libsensors4 (lm-sensors 3)
+		compatibility.  Moved all hwmon attributes to this
+		new platform device.
+
+0x020100:	Marker for thinkpad-acpi with hot key NVRAM polling
+		support.  If you must, use it to know you should not
+		start a userspace NVRAM poller (allows to detect when
+		NVRAM is compiled out by the user because it is
+		unneeded/undesired in the first place).
+0x020101:	Marker for thinkpad-acpi with hot key NVRAM polling
+		and proper hotkey_mask semantics (version 8 of the
+		NVRAM polling patch).  Some development snapshots of
+		0.18 had an earlier version that did strange things
+		to hotkey_mask.
+
+0x020200:	Add poll()/select() support to the following attributes:
+		hotkey_radio_sw, wakeup_hotunplug_complete, wakeup_reason
+
+0x020300:	hotkey enable/disable support removed, attributes
+		hotkey_bios_enabled and hotkey_enable deprecated and
+		marked for removal.
+
+0x020400:	Marker for 16 LEDs support.  Also, LEDs that are known
+		to not exist in a given model are not registered with
+		the LED sysfs class anymore.
+
+0x020500:	Updated hotkey driver, hotkey_mask is always available
+		and it is always able to disable hot keys.  Very old
+		thinkpads are properly supported.  hotkey_bios_mask
+		is deprecated and marked for removal.
+
+0x020600:	Marker for backlight change event support.
+
+0x020700:	Support for mute-only mixers.
+		Volume control in read-only mode by default.
+		Marker for ALSA mixer support.
+
+0x030000:	Thermal and fan sysfs attributes were moved to the hwmon
+		device instead of being attached to the backing platform
+		device.
+=========	===============================================================
diff --git a/Documentation/admin-guide/laptops/toshiba_haps.rst b/Documentation/admin-guide/laptops/toshiba_haps.rst
new file mode 100644
index 000000000..0226225b8
--- /dev/null
+++ b/Documentation/admin-guide/laptops/toshiba_haps.rst
@@ -0,0 +1,87 @@
+====================================
+Toshiba HDD Active Protection Sensor
+====================================
+
+Kernel driver: toshiba_haps
+
+Author: Azael Avalos <coproscefalo@gmail.com>
+
+
+.. 0. Contents
+
+   1. Description
+   2. Interface
+   3. Accelerometer axes
+   4. Supported devices
+   5. Usage
+
+
+1. Description
+--------------
+
+This driver provides support for the accelerometer found in various Toshiba
+laptops, being called "Toshiba HDD Protection - Shock Sensor" officially,
+and detects laptops automatically with this device.
+On Windows, Toshiba provided software monitors this device and provides
+automatic HDD protection (head unload) on sudden moves or harsh vibrations,
+however, this driver only provides a notification via a sysfs file to let
+userspace tools or daemons act accordingly, as well as providing a sysfs
+file to set the desired protection level or sensor sensibility.
+
+
+2. Interface
+------------
+
+This device comes with 3 methods:
+
+====	=====================================================================
+_STA    Checks existence of the device, returning Zero if the device does not
+	exists or is not supported.
+PTLV    Sets the desired protection level.
+RSSS    Shuts down the HDD protection interface for a few seconds,
+	then restores normal operation.
+====	=====================================================================
+
+Note:
+  The presence of Solid State Drives (SSD) can cause this driver to fail loading,
+  given the fact that such drives have no movable parts, and thus, not requiring
+  any "protection" as well as failing during the evaluation of the _STA method
+  found under this device.
+
+
+3. Accelerometer axes
+---------------------
+
+This device does not report any axes, however, to query the sensor position
+a couple HCI (Hardware Configuration Interface) calls (0x6D and 0xA6) are
+provided to query such information, handled by the kernel module toshiba_acpi
+since kernel version 3.15.
+
+
+4. Supported devices
+--------------------
+
+This driver binds itself to the ACPI device TOS620A, and any Toshiba laptop
+with this device is supported, given the fact that they have the presence of
+conventional HDD and not only SSD, or a combination of both HDD and SSD.
+
+
+5. Usage
+--------
+
+The sysfs files under /sys/devices/LNXSYSTM:00/LNXSYBUS:00/TOS620A:00/ are:
+
+================   ============================================================
+protection_level   The protection_level is readable and writeable, and
+		   provides a way to let userspace query the current protection
+		   level, as well as set the desired protection level, the
+		   available protection levels are::
+
+		     ============   =======   ==========   ========
+		     0 - Disabled   1 - Low   2 - Medium   3 - High
+		     ============   =======   ==========   ========
+
+reset_protection   The reset_protection entry is writeable only, being "1"
+		   the only parameter it accepts, it is used to trigger
+		   a reset of the protection interface.
+================   ============================================================
diff --git a/Documentation/admin-guide/laptops/uniwill-laptop.rst b/Documentation/admin-guide/laptops/uniwill-laptop.rst
new file mode 100644
index 000000000..be50b45b8
--- /dev/null
+++ b/Documentation/admin-guide/laptops/uniwill-laptop.rst
@@ -0,0 +1,118 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+Uniwill laptop extra features
+=============================
+
+On laptops manufactured by Uniwill (either directly or as ODM), the ``uniwill-laptop`` driver
+handles various platform-specific features.
+
+Module Loading
+--------------
+
+The ``uniwill-laptop`` driver relies on a DMI table to automatically load on supported devices.
+When using the ``force`` module parameter, this DMI check will be omitted, allowing the driver
+to be loaded on unsupported devices for testing purposes.
+
+Hotkeys
+-------
+
+Usually the FN keys work without a special driver. However as soon as the ``uniwill-laptop`` driver
+is loaded, the FN keys need to be handled manually. This is done automatically by the driver itself.
+
+Keyboard settings
+-----------------
+
+The ``uniwill-laptop`` driver allows the user to enable/disable:
+
+ - the FN lock and super key of the integrated keyboard
+ - the touchpad toggle functionality of the integrated touchpad
+
+See Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details.
+
+Hwmon interface
+---------------
+
+The ``uniwill-laptop`` driver supports reading of the CPU and GPU temperature and supports up to
+two fans. Userspace applications can access sensor readings over the hwmon sysfs interface.
+
+Platform profile
+----------------
+
+Support for changing the platform performance mode is currently not implemented.
+
+Battery Charging Control
+------------------------
+
+.. warning:: Some devices do not properly implement the charging threshold interface. Forcing
+             the driver to enable access to said interface on such devices might damage the
+             battery [1]_. Because of this the driver will not enable said feature even when
+             using the ``force`` module parameter. The charging profile interface will be
+             available instead.
+
+The ``uniwill-laptop`` driver supports controlling the battery charge limit. This either happens
+over the standard ``charge_control_end_threshold`` or ``charge_types`` power supply sysfs attribute,
+depending on the device. When using the ``charge_control_end_threshold`` sysfs attribute, all values
+between 1 and 100 percent are supported. When using the ``charge_types`` sysfs attribute, the driver
+supports switching between the ``Standard``, ``Trickle`` and ``Long Life`` profiles.
+
+Keep in mind that when using the ``charge_types`` sysfs attribute, the EC firmware will hide the
+true charging status of the battery from the operating system, potentially misleading users into
+thinking that the charging profile does not work. Checking the ``current_now`` sysfs attribute
+tells you the true charging status of the battery even when using the ``charge_types`` sysfs
+attribute (0 means that the battery is currently not charging).
+
+Additionally the driver signals the presence of battery charging issues through the standard
+``health`` power supply sysfs attribute.
+
+It also lets you set whether a USB-C power source should prioritise charging the battery or
+delivering immediate power to the cpu. See Documentation/ABI/testing/sysfs-driver-uniwill-laptop for
+details.
+
+Lightbar
+--------
+
+The ``uniwill-laptop`` driver exposes the lightbar found on some models as a standard multicolor
+LED class device. The default name of this LED class device is ``uniwill:multicolor:status``.
+
+See Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details on how to control the various
+animation modes of the lightbar.
+
+Keyboard Backlight
+------------------
+
+The ``uniwill-laptop`` driver supports controlling the keyboard backlight using the standard
+LED class interface. The default name of this LED class device is ``uniwill:white:kbd_backlight``
+when the keyboard backlight supports only a single color, or ``uniwill:multicolor:kbd_backlight``
+when the keyboard backlight supports RGB colors. The maximum intensity for each color channel
+in RGB mode is 50.
+
+Keep in mind that due to hardware design choices, the driver does not support the RGB value
+``0x000000`` (black), instead it will fall back to ``0x010101`` (faint white). In order to
+disable the keyboard backlight, the standard LED brightness setting has to be used instead.
+
+Configurable TGP
+----------------
+
+The ``uniwill-laptop`` driver allows to set the configurable TGP for devices with NVIDIA GPUs that
+allow it.
+
+See Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details.
+
+AC Auto Boot
+------------
+
+The ``uniwill-laptop`` driver allows the user to configure if the system should automatically
+boot when being connected to a power source, see
+Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details.
+
+USB Powershare
+--------------
+
+The ``uniwill-laptop`` driver allows the user to configure if the system should continue to
+provide power via the USB ports when hibernating or powered off, see
+Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details.
+
+References
+==========
+
+.. [1] https://www.reddit.com/r/XMG_gg/comments/ld9yyf/battery_limit_hidden_function_discovered_on/