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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-08-07 13:17:46 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-08-07 13:17:46 +0000
commit7f3a4257159dea8e7ef66d1a539dc6df708b8ed3 (patch)
treebcc69b5f4609f348fac49e2f59e210b29eaea783 /Documentation/wmi/devices
parentAdding upstream version 6.9.12. (diff)
downloadlinux-7f3a4257159dea8e7ef66d1a539dc6df708b8ed3.tar.xz
linux-7f3a4257159dea8e7ef66d1a539dc6df708b8ed3.zip
Adding upstream version 6.10.3.upstream/6.10.3
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+===================================================
+MSI WMI Platform Features driver (msi-wmi-platform)
+===================================================
+
+Introduction
+============
+
+Many MSI notebooks support various features like reading fan sensors. This features are controlled
+by the embedded controller, with the ACPI firmware exposing a standard ACPI WMI interface on top
+of the embedded controller interface.
+
+WMI interface description
+=========================
+
+The WMI interface description can be decoded from the embedded binary MOF (bmof)
+data using the `bmfdec <https://github.com/pali/bmfdec>`_ utility:
+
+::
+
+ [WMI, Locale("MS\0x409"),
+ Description("This class contains the definition of the package used in other classes"),
+ guid("{ABBC0F60-8EA1-11d1-00A0-C90629100000}")]
+ class Package {
+ [WmiDataId(1), read, write, Description("16 bytes of data")] uint8 Bytes[16];
+ };
+
+ [WMI, Locale("MS\0x409"),
+ Description("This class contains the definition of the package used in other classes"),
+ guid("{ABBC0F63-8EA1-11d1-00A0-C90629100000}")]
+ class Package_32 {
+ [WmiDataId(1), read, write, Description("32 bytes of data")] uint8 Bytes[32];
+ };
+
+ [WMI, Dynamic, Provider("WmiProv"), Locale("MS\0x409"),
+ Description("Class used to operate methods on a package"),
+ guid("{ABBC0F6E-8EA1-11d1-00A0-C90629100000}")]
+ class MSI_ACPI {
+ [key, read] string InstanceName;
+ [read] boolean Active;
+
+ [WmiMethodId(1), Implemented, read, write, Description("Return the contents of a package")]
+ void GetPackage([out, id(0)] Package Data);
+
+ [WmiMethodId(2), Implemented, read, write, Description("Set the contents of a package")]
+ void SetPackage([in, id(0)] Package Data);
+
+ [WmiMethodId(3), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_EC([out, id(0)] Package_32 Data);
+
+ [WmiMethodId(4), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_EC([in, id(0)] Package_32 Data);
+
+ [WmiMethodId(5), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_BIOS([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(6), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_BIOS([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(7), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_SMBUS([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(8), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_SMBUS([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(9), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_MasterBattery([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(10), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_MasterBattery([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(11), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_SlaveBattery([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(12), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_SlaveBattery([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(13), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_Temperature([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(14), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_Temperature([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(15), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_Thermal([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(16), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_Thermal([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(17), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_Fan([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(18), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_Fan([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(19), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_Device([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(20), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_Device([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(21), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_Power([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(22), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_Power([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(23), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_Debug([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(24), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_Debug([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(25), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_AP([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(26), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_AP([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(27), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_Data([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(28), Implemented, read, write, Description("Set the contents of a package")]
+ void Set_Data([in, out, id(0)] Package_32 Data);
+
+ [WmiMethodId(29), Implemented, read, write, Description("Return the contents of a package")]
+ void Get_WMI([out, id(0)] Package_32 Data);
+ };
+
+Due to a peculiarity in how Windows handles the ``CreateByteField()`` ACPI operator (errors only
+happen when a invalid byte field is ultimately accessed), all methods require a 32 byte input
+buffer, even if the Binay MOF says otherwise.
+
+The input buffer contains a single byte to select the subfeature to be accessed and 31 bytes of
+input data, the meaning of which depends on the subfeature being accessed.
+
+The output buffer contains a singe byte which signals success or failure (``0x00`` on failure)
+and 31 bytes of output data, the meaning if which depends on the subfeature being accessed.
+
+WMI method Get_EC()
+-------------------
+
+Returns embedded controller information, the selected subfeature does not matter. The output
+data contains a flag byte and a 28 byte controller firmware version string.
+
+The first 4 bits of the flag byte contain the minor version of the embedded controller interface,
+with the next 2 bits containing the major version of the embedded controller interface.
+
+The 7th bit signals if the embedded controller page chaged (exact meaning is unknown), and the
+last bit signals if the platform is a Tigerlake platform.
+
+The MSI software seems to only use this interface when the last bit is set.
+
+WMI method Get_Fan()
+--------------------
+
+Fan speed sensors can be accessed by selecting subfeature ``0x00``. The output data contains
+up to four 16-bit fan speed readings in big-endian format. Most machines do not support all
+four fan speed sensors, so the remaining reading are hardcoded to ``0x0000``.
+
+The fan RPM readings can be calculated with the following formula:
+
+ RPM = 480000 / <fan speed reading>
+
+If the fan speed reading is zero, then the fan RPM is zero too.
+
+WMI method Get_WMI()
+--------------------
+
+Returns the version of the ACPI WMI interface, the selected subfeature does not matter.
+The output data contains two bytes, the first one contains the major version and the last one
+contains the minor revision of the ACPI WMI interface.
+
+The MSI software seems to only use this interface when the major version is greater than two.
+
+Reverse-Engineering the MSI WMI Platform interface
+==================================================
+
+.. warning:: Randomly poking the embedded controller interface can potentially cause damage
+ to the machine and other unwanted side effects, please be careful.
+
+The underlying embedded controller interface is used by the ``msi-ec`` driver, and it seems
+that many methods just copy a part of the embedded controller memory into the output buffer.
+
+This means that the remaining WMI methods can be reverse-engineered by looking which part of
+the embedded controller memory is accessed by the ACPI AML code. The driver also supports a
+debugfs interface for directly executing WMI methods. Additionally, any safety checks regarding
+unsupported hardware can be disabled by loading the module with ``force=true``.
+
+More information about the MSI embedded controller interface can be found at the
+`msi-ec project <https://github.com/BeardOverflow/msi-ec>`_.
+
+Special thanks go to github user `glpnk` for showing how to decode the fan speed readings.