Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 359 insertions, 0 deletions

diff --git a/Documentation/hwmon/dell-smm-hwmon.rst b/Documentation/hwmon/dell-smm-hwmon.rst
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+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+.. include:: <isonum.txt>
+
+Kernel driver dell-smm-hwmon
+============================
+
+:Copyright: |copy| 2002-2005 Massimo Dal Zotto <dz@debian.org>
+:Copyright: |copy| 2019 Giovanni Mascellani <gio@debian.org>
+
+Description
+-----------
+
+On many Dell laptops the System Management Mode (SMM) BIOS can be
+queried for the status of fans and temperature sensors.  Userspace
+utilities like ``sensors`` can be used to return the readings. The
+userspace suite `i8kutils`__ can also be used to read the sensors and
+automatically adjust fan speed (please notice that it currently uses
+the deprecated ``/proc/i8k`` interface).
+
+ __ https://github.com/vitorafsr/i8kutils
+
+``sysfs`` interface
+-------------------
+
+Temperature sensors and fans can be queried and set via the standard
+``hwmon`` interface on ``sysfs``, under the directory
+``/sys/class/hwmon/hwmonX`` for some value of ``X`` (search for the
+``X`` such that ``/sys/class/hwmon/hwmonX/name`` has content
+``dell_smm``). A number of other attributes can be read or written:
+
+=============================== ======= =======================================
+Name				Perm	Description
+=============================== ======= =======================================
+fan[1-3]_input                  RO      Fan speed in RPM.
+fan[1-3]_label                  RO      Fan label.
+fan[1-3]_min                    RO      Minimal Fan speed in RPM
+fan[1-3]_max                    RO      Maximal Fan speed in RPM
+fan[1-3]_target                 RO      Expected Fan speed in RPM
+pwm[1-3]                        RW      Control the fan PWM duty-cycle.
+pwm1_enable                     WO      Enable or disable automatic BIOS fan
+                                        control (not supported on all laptops,
+                                        see below for details).
+temp[1-10]_input                RO      Temperature reading in milli-degrees
+                                        Celsius.
+temp[1-10]_label                RO      Temperature sensor label.
+=============================== ======= =======================================
+
+Due to the nature of the SMM interface, each pwmX attribute controls
+fan number X.
+
+Disabling automatic BIOS fan control
+------------------------------------
+
+On some laptops the BIOS automatically sets fan speed every few
+seconds. Therefore the fan speed set by mean of this driver is quickly
+overwritten.
+
+There is experimental support for disabling automatic BIOS fan
+control, at least on laptops where the corresponding SMM command is
+known, by writing the value ``1`` in the attribute ``pwm1_enable``
+(writing ``2`` enables automatic BIOS control again). Even if you have
+more than one fan, all of them are set to either enabled or disabled
+automatic fan control at the same time and, notwithstanding the name,
+``pwm1_enable`` sets automatic control for all fans.
+
+If ``pwm1_enable`` is not available, then it means that SMM codes for
+enabling and disabling automatic BIOS fan control are not whitelisted
+for your hardware. It is possible that codes that work for other
+laptops actually work for yours as well, or that you have to discover
+new codes.
+
+Check the list ``i8k_whitelist_fan_control`` in file
+``drivers/hwmon/dell-smm-hwmon.c`` in the kernel tree: as a first
+attempt you can try to add your machine and use an already-known code
+pair. If, after recompiling the kernel, you see that ``pwm1_enable``
+is present and works (i.e., you can manually control the fan speed),
+then please submit your finding as a kernel patch, so that other users
+can benefit from it. Please see
+:ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
+for information on submitting patches.
+
+If no known code works on your machine, you need to resort to do some
+probing, because unfortunately Dell does not publish datasheets for
+its SMM. You can experiment with the code in `this repository`__ to
+probe the BIOS on your machine and discover the appropriate codes.
+
+ __ https://github.com/clopez/dellfan/
+
+Again, when you find new codes, we'd be happy to have your patches!
+
+``thermal`` interface
+---------------------------
+
+The driver also exports the fans as thermal cooling devices with
+``type`` set to ``dell-smm-fan[1-3]``. This allows for easy fan control
+using one of the thermal governors.
+
+Module parameters
+-----------------
+
+* force:bool
+                   Force loading without checking for supported
+                   models. (default: 0)
+
+* ignore_dmi:bool
+                   Continue probing hardware even if DMI data does not
+                   match. (default: 0)
+
+* restricted:bool
+                   Allow fan control only to processes with the
+                   ``CAP_SYS_ADMIN`` capability set or processes run
+                   as root when using the legacy ``/proc/i8k``
+                   interface. In this case normal users will be able
+                   to read temperature and fan status but not to
+                   control the fan.  If your notebook is shared with
+                   other users and you don't trust them you may want
+                   to use this option. (default: 1, only available
+                   with ``CONFIG_I8K``)
+
+* power_status:bool
+                   Report AC status in ``/proc/i8k``. (default: 0,
+                   only available with ``CONFIG_I8K``)
+
+* fan_mult:uint
+                   Factor to multiply fan speed with. (default:
+                   autodetect)
+
+* fan_max:uint
+                   Maximum configurable fan speed. (default:
+                   autodetect)
+
+Legacy ``/proc`` interface
+--------------------------
+
+.. warning:: This interface is obsolete and deprecated and should not
+             used in new applications. This interface is only
+             available when kernel is compiled with option
+             ``CONFIG_I8K``.
+
+The information provided by the kernel driver can be accessed by
+simply reading the ``/proc/i8k`` file. For example::
+
+    $ cat /proc/i8k
+    1.0 A17 2J59L02 52 2 1 8040 6420 1 2
+
+The fields read from ``/proc/i8k`` are::
+
+    1.0 A17 2J59L02 52 2 1 8040 6420 1 2
+    |   |   |       |  | | |    |    | |
+    |   |   |       |  | | |    |    | +------- 10. buttons status
+    |   |   |       |  | | |    |    +--------- 9.  AC status
+    |   |   |       |  | | |    +-------------- 8.  fan0 RPM
+    |   |   |       |  | | +------------------- 7.  fan1 RPM
+    |   |   |       |  | +--------------------- 6.  fan0 status
+    |   |   |       |  +----------------------- 5.  fan1 status
+    |   |   |       +-------------------------- 4.  temp0 reading (Celsius)
+    |   |   +---------------------------------- 3.  Dell service tag (later known as 'serial number')
+    |   +-------------------------------------- 2.  BIOS version
+    +------------------------------------------ 1.  /proc/i8k format version
+
+A negative value, for example -22, indicates that the BIOS doesn't
+return the corresponding information. This is normal on some
+models/BIOSes.
+
+For performance reasons the ``/proc/i8k`` doesn't report by default
+the AC status since this SMM call takes a long time to execute and is
+not really needed.  If you want to see the ac status in ``/proc/i8k``
+you must explictitly enable this option by passing the
+``power_status=1`` parameter to insmod. If AC status is not
+available -1 is printed instead.
+
+The driver provides also an ioctl interface which can be used to
+obtain the same information and to control the fan status. The ioctl
+interface can be accessed from C programs or from shell using the
+i8kctl utility. See the source file of ``i8kutils`` for more
+information on how to use the ioctl interface.
+
+SMM Interface
+-------------
+
+.. warning:: The SMM interface was reverse-engineered by trial-and-error
+             since Dell did not provide any Documentation,
+             please keep that in mind.
+
+The driver uses the SMM interface to send commands to the system BIOS.
+This interface is normally used by Dell's 32-bit diagnostic program or
+on newer notebook models by the buildin BIOS diagnostics.
+The SMM is triggered by writing to the special ioports ``0xb2`` and ``0x84``,
+and may cause short hangs when the BIOS code is taking too long to
+execute.
+
+The SMM handler inside the system BIOS looks at the contents of the
+``eax``, ``ebx``, ``ecx``, ``edx``, ``esi`` and ``edi`` registers.
+Each register has a special purpose:
+
+=============== ==================================
+Register        Purpose
+=============== ==================================
+eax             Holds the command code before SMM,
+                holds the first result after SMM.
+ebx             Holds the arguments.
+ecx             Unknown, set to 0.
+edx             Holds the second result after SMM.
+esi             Unknown, set to 0.
+edi             Unknown, set to 0.
+=============== ==================================
+
+The SMM handler can signal a failure by either:
+
+- setting the lower sixteen bits of ``eax`` to ``0xffff``
+- not modifying ``eax`` at all
+- setting the carry flag
+
+SMM command codes
+-----------------
+
+=============== ======================= ================================================
+Command Code    Command Name            Description
+=============== ======================= ================================================
+``0x0025``      Get Fn key status       Returns the Fn key pressed after SMM:
+
+                                        - 9th bit in ``eax`` indicates Volume up
+                                        - 10th bit in ``eax`` indicates Volume down
+                                        - both bits indicate Volume mute
+
+``0xa069``      Get power status        Returns current power status after SMM:
+
+                                        - 1st bit in ``eax`` indicates Battery connected
+                                        - 3th bit in ``eax`` indicates AC connected
+
+``0x00a3``      Get fan state           Returns current fan state after SMM:
+
+                                        - 1st byte in ``eax`` holds the current
+                                          fan state (0 - 2 or 3)
+
+``0x01a3``      Set fan state           Sets the fan speed:
+
+                                        - 1st byte in ``ebx`` holds the fan number
+                                        - 2nd byte in ``ebx`` holds the desired
+                                          fan state (0 - 2 or 3)
+
+``0x02a3``      Get fan speed           Returns the current fan speed in RPM:
+
+                                        - 1st byte in ``ebx`` holds the fan number
+                                        - 1st word in ``eax`` holds the current
+                                          fan speed in RPM (after SMM)
+
+``0x03a3``      Get fan type            Returns the fan type:
+
+                                        - 1st byte in ``ebx`` holds the fan number
+                                        - 1st byte in ``eax`` holds the
+                                          fan type (after SMM):
+
+                                          - 5th bit indicates docking fan
+                                          - 1 indicates Processor fan
+                                          - 2 indicates Motherboard fan
+                                          - 3 indicates Video fan
+                                          - 4 indicates Power supply fan
+                                          - 5 indicates Chipset fan
+                                          - 6 indicates other fan type
+
+``0x04a3``      Get nominal fan speed   Returns the nominal RPM in each fan state:
+
+                                        - 1st byte in ``ebx`` holds the fan number
+                                        - 2nd byte in ``ebx`` holds the fan state
+                                          in question (0 - 2 or 3)
+                                        - 1st word in ``eax`` holds the nominal
+                                          fan speed in RPM (after SMM)
+
+``0x05a3``      Get fan speed tolerance Returns the speed tolerance for each fan state:
+
+                                        - 1st byte in ``ebx`` holds the fan number
+                                        - 2nd byte in ``ebx`` holds the fan state
+                                          in question (0 - 2 or 3)
+                                        - 1st byte in ``eax`` returns the speed
+                                          tolerance
+
+``0x10a3``      Get sensor temperature  Returns the measured temperature:
+
+                                        - 1st byte in ``ebx`` holds the sensor number
+                                        - 1st byte in ``eax`` holds the measured
+                                          temperature (after SMM)
+
+``0x11a3``      Get sensor type         Returns the sensor type:
+
+                                        - 1st byte in ``ebx`` holds the sensor number
+                                        - 1st byte in ``eax`` holds the
+                                          temperature type (after SMM):
+
+                                          - 1 indicates CPU sensor
+                                          - 2 indicates GPU sensor
+                                          - 3 indicates SODIMM sensor
+                                          - 4 indicates other sensor type
+                                          - 5 indicates Ambient sensor
+                                          - 6 indicates other sensor type
+
+``0xfea3``      Get SMM signature       Returns Dell signature if interface
+                                        is supported (after SMM):
+
+                                        - ``eax`` holds 1145651527
+                                          (0x44494147 or "DIAG")
+                                        - ``edx`` holds 1145392204
+                                          (0x44454c4c or "DELL")
+
+``0xffa3``      Get SMM signature       Same as ``0xfea3``, check both.
+=============== ======================= ================================================
+
+There are additional commands for enabling (``0x31a3`` or ``0x35a3``) and
+disabling (``0x30a3`` or ``0x34a3``) automatic fan speed control.
+The commands are however causing severe sideeffects on many machines, so
+they are not used by default.
+
+On several machines (Inspiron 3505, Precision 490, Vostro 1720, ...), the
+fans supports a 4th "magic" state, which signals the BIOS that automatic
+fan control should be enabled for a specific fan.
+However there are also some machines who do support a 4th regular fan state too,
+but in case of the "magic" state, the nominal RPM reported for this state is a
+placeholder value, which however is not always detectable.
+
+Firmware Bugs
+-------------
+
+The SMM calls can behave erratic on some machines:
+
+======================================================= =================
+Firmware Bug                                            Affected Machines
+======================================================= =================
+Reading of fan states return spurious errors.           Precision 490
+
+Reading of fan types causes erratic fan behaviour.      Studio XPS 8000
+
+                                                        Studio XPS 8100
+
+                                                        Inspiron 580
+
+                                                        Inspiron 3505
+
+Fan-related SMM calls take too long (about 500ms).      Inspiron 7720
+
+                                                        Vostro 3360
+
+                                                        XPS 13 9333
+
+                                                        XPS 15 L502X
+======================================================= =================
+
+In case you experience similar issues on your Dell machine, please
+submit a bugreport on bugzilla to we can apply workarounds.
+
+Limitations
+-----------
+
+The SMM calls can take too long to execute on some machines, causing
+short hangs and/or audio glitches.
+Also the fan state needs to be restored after suspend, as well as
+the automatic mode settings.
+When reading a temperature sensor, values above 127 degrees indicate
+a BIOS read error or a deactivated sensor.