On Sun, Apr 30, 2023 at 12:55:24AM +0200, Armin Wolf wrote: > diff --git a/Documentation/wmi/devices/dell-wmi-ddv.rst b/Documentation/wmi/devices/dell-wmi-ddv.rst > new file mode 100644 > index 000000000000..3fc6ee3e9f9b > --- /dev/null > +++ b/Documentation/wmi/devices/dell-wmi-ddv.rst > @@ -0,0 +1,294 @@ > +.. SPDX-License-Identifier: GPL-2.0-or-later > + > +============================================ > +Dell DDV WMI interface driver (dell-wmi-ddv) > +============================================ > + > +Introduction > +============ > + > +Many Dell notebooks made after ~2020 support a WMI-based interface for > +retrieving various system data like battery temperature, ePPID, diagostic data > +and fan/thermal sensor data. > + > +This interface is likely used by the `Dell Data Vault` software on Windows, > +so it was called `DDV`. Currently the ``dell-wmi-ddv`` driver supports > +version 2 and 3 of the interface, with support for new interface versions > +easily added. > + > +.. warning:: The interface is regarded as internal by Dell, so no vendor > + documentation is available. All knowledge was thus obtained by > + trial-and-error, please keep that in mind. > + > +Dell ePPID (electronic Piece Part Identification) > +================================================= > + > +The Dell ePPID is used to uniquely identify components in Dell machines, > +including batteries. It has a form similar to `CC-PPPPPP-MMMMM-YMD-SSSS-FFF` > +and contains the following information: > + > +* Country code of origin (CC). > +* Part number with the first character being a filling number (PPPPPP). > +* Manufacture Identification (MMMMM). > +* Manufacturing Year/Month/Date (YMD) in base 36, with Y being the last digit > + of the year. > +* Manufacture Sequence Number (SSSS). > +* Optional Firmware Version/Revision (FFF). > + > +The `eppidtool <https://pypi.org/project/eppidtool>`_ python utility can be used > +to decode and display this information. > + > +All information regarding the Dell ePPID was gathered using Dell support > +documentation and `this website <https://telcontar.net/KBK/Dell/date_codes>`_. > + > +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, Dynamic, Provider("WmiProv"), Locale("MS\\0x409"), Description("WMI Function"), guid("{8A42EA14-4F2A-FD45-6422-0087F7A7E608}")] > + class DDVWmiMethodFunction { > + [key, read] string InstanceName; > + [read] boolean Active; > + > + [WmiMethodId(1), Implemented, read, write, Description("Return Battery Design Capacity.")] void BatteryDesignCapacity([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(2), Implemented, read, write, Description("Return Battery Full Charge Capacity.")] void BatteryFullChargeCapacity([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(3), Implemented, read, write, Description("Return Battery Manufacture Name.")] void BatteryManufactureName([in] uint32 arg2, [out] string argr); > + [WmiMethodId(4), Implemented, read, write, Description("Return Battery Manufacture Date.")] void BatteryManufactureDate([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(5), Implemented, read, write, Description("Return Battery Serial Number.")] void BatterySerialNumber([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(6), Implemented, read, write, Description("Return Battery Chemistry Value.")] void BatteryChemistryValue([in] uint32 arg2, [out] string argr); > + [WmiMethodId(7), Implemented, read, write, Description("Return Battery Temperature.")] void BatteryTemperature([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(8), Implemented, read, write, Description("Return Battery Current.")] void BatteryCurrent([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(9), Implemented, read, write, Description("Return Battery Voltage.")] void BatteryVoltage([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(10), Implemented, read, write, Description("Return Battery Manufacture Access(MA code).")] void BatteryManufactureAceess([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(11), Implemented, read, write, Description("Return Battery Relative State-Of-Charge.")] void BatteryRelativeStateOfCharge([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(12), Implemented, read, write, Description("Return Battery Cycle Count")] void BatteryCycleCount([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(13), Implemented, read, write, Description("Return Battery ePPID")] void BatteryePPID([in] uint32 arg2, [out] string argr); > + [WmiMethodId(14), Implemented, read, write, Description("Return Battery Raw Analytics Start")] void BatteryeRawAnalyticsStart([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(15), Implemented, read, write, Description("Return Battery Raw Analytics")] void BatteryeRawAnalytics([in] uint32 arg2, [out] uint32 RawSize, [out, WmiSizeIs("RawSize") : ToInstance] uint8 RawData[]); > + [WmiMethodId(16), Implemented, read, write, Description("Return Battery Design Voltage.")] void BatteryDesignVoltage([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(17), Implemented, read, write, Description("Return Battery Raw Analytics A Block")] void BatteryeRawAnalyticsABlock([in] uint32 arg2, [out] uint32 RawSize, [out, WmiSizeIs("RawSize") : ToInstance] uint8 RawData[]); > + [WmiMethodId(18), Implemented, read, write, Description("Return Version.")] void ReturnVersion([in] uint32 arg2, [out] uint32 argr); > + [WmiMethodId(32), Implemented, read, write, Description("Return Fan Sensor Information")] void FanSensorInformation([in] uint32 arg2, [out] uint32 RawSize, [out, WmiSizeIs("RawSize") : ToInstance] uint8 RawData[]); > + [WmiMethodId(34), Implemented, read, write, Description("Return Thermal Sensor Information")] void ThermalSensorInformation([in] uint32 arg2, [out] uint32 RawSize, [out, WmiSizeIs("RawSize") : ToInstance] uint8 RawData[]); > + }; > + > +Each WMI method takes an ACPI buffer containing a 32-bit index as input argument, > +with the first 8 bit being used to specify the battery when using battery-related > +WMI methods. Other WMI methods may ignore this argument or interpret it > +differently. The WMI method output format varies: > + > +* if the function has only a single output, then an ACPI object > + of the corresponding type is returned > +* if the function has multiple outputs, when an ACPI package > + containing the outputs in the same order is returned > + > +The format of the output should be thoroughly checked, since many methods can > +return malformed data in case of an error. > + > +The data format of many battery-related methods seems to be based on the > +`Smart Battery Data Specification`, so unknown battery-related methods are > +likely to follow this standard in some way. > + > +WMI method GetBatteryDesignCapacity() > +------------------------------------- > + > +Returns the design capacity of the battery in mAh as an u16. > + > +WMI method BatteryFullCharge() > +------------------------------ > + > +Returns the full charge capacity of the battery in mAh as an u16. > + > +WMI method BatteryManufactureName() > +----------------------------------- > + > +Returns the manufacture name of the battery as an ASCII string. > + > +WMI method BatteryManufactureDate() > +----------------------------------- > + > +Returns the manufacture date of the battery as an u16. > +The date is encoded in the following manner: > + > +- bits 0 to 4 contain the manufacture day. > +- bits 5 to 8 contain the manufacture month. > +- bits 9 to 15 contain the manufacture year biased by 1980. > + > +.. note:: > + The data format needs to be verified on more machines. > + > +WMI method BatterySerialNumber() > +-------------------------------- > + > +Returns the serial number of the battery as an u16. > + > +WMI method BatteryChemistryValue() > +---------------------------------- > + > +Returns the chemistry of the battery as an ASCII string. > +Known values are: > + > +- "Li-I" for Li-Ion > + > +WMI method BatteryTemperature() > +------------------------------- > + > +Returns the temperature of the battery in tenth degree kelvin as an u16. > + > +WMI method BatteryCurrent() > +--------------------------- > + > +Returns the current flow of the battery in mA as an s16. > +Negative values indicate discharging. > + > +WMI method BatteryVoltage() > +--------------------------- > + > +Returns the voltage flow of the battery in mV as an u16. > + > +WMI method BatteryManufactureAccess() > +------------------------------------- > + > +Returns a manufacture-defined value as an u16. > + > +WMI method BatteryRelativeStateOfCharge() > +----------------------------------------- > + > +Returns the capacity of the battery in percent as an u16. > + > +WMI method BatteryCycleCount() > +------------------------------ > + > +Returns the cycle count of the battery as an u16. > + > +WMI method BatteryePPID() > +------------------------- > + > +Returns the ePPID of the battery as an ASCII string. > + > +WMI method BatteryeRawAnalyticsStart() > +-------------------------------------- > + > +Performs an analysis of the battery and returns a status code: > + > +- ``0x0``: Success > +- ``0x1``: Interface not supported > +- ``0xfffffffe``: Error/Timeout > + > +.. note:: > + The meaning of this method is still largely unknown. > + > +WMI method BatteryeRawAnalytics() > +--------------------------------- > + > +Returns a buffer usually containg 12 blocks of analytics data. > +Those blocks contain: > +- block number starting with 0 (u8) > +- 31 bytes of unknown data > + > +.. note:: > + The meaning of this method is still largely unknown. > + > +WMI method BatteryDesignVoltage() > +--------------------------------- > + > +Returns the design voltage of the battery in mV as an u16. > + > +WMI method BatteryeRawAnalyticsABlock() > +--------------------------------------- > + > +Returns a single block of analytics data, with the second byte > +of the index being used for selecting the block number. > + > +*Supported since WMI interface version 3!* > + > +.. note:: > + The meaning of this method is still largely unknown. > + > +WMI method ReturnVersion() > +-------------------------- > + > +Returns the WMI interface version as an u32. > + > +WMI method FanSensorInformation() > +--------------------------------- > + > +Returns a buffer containg fan sensor entries, terminated > +with a single ``0xff``. > +Those entries contain: > + > +- fan type (u8) > +- fan speed in RPM (little endian u16) > + > +WMI method ThermalSensorInformation() > +------------------------------------- > + > +Returns a buffer containing thermal sensor entries, terminated > +with a single ``0xff``. > +Those entries contain: > + > +- thermal type (u8) > +- current temperature (s8) > +- min. temperature (s8) > +- max. temperature (s8) > +- unknown field (u8) > + > +.. note:: > + Find out what the meaning of the last byte is. Is the note above TODO? If so, mark as such, keeping the note:: directive. > + > +ACPI battery matching algorithm > +=============================== > + > +The algorithm used to match ACPI batteries to indices is based on information > +which was found inside the logging messages of the OEM software. > + > +Basically for each new ACPI battery, the serial numbers of the batteries behind > +indices 1 till 3 are compared with the serial number of the ACPI battery. > +Since the serial number of the ACPI battery can either be encoded as a normal > +integer or as a hexadecimal value, both cases need to be checked. The first > +index with a matching serial number is then selected. > + > +A serial number of 0 indicates that the corresponding index is not associated > +with an actual battery, or that the associated battery is not present. > + > +Some machines like the Dell Inspiron 3505 only support a single battery and thus > +ignore the battery index. Because of this the driver depends on the ACPI battery > +hook mechanism to discover batteries. > + > +.. note:: > + The ACPI battery matching algorithm currently used inside the driver is > + outdated and does not match the algorithm described above. The reasons for > + this are differences in the handling of the ToHexString() ACPI opcode between > + Linux and Windows, which distorts the serial number of ACPI batteries on many > + machines. Until this issue is resolved, the driver cannot use the above > + algorithm. > + > +Reverse-Engineering the DDV WMI interface > +========================================= > + > +1. Find a supported Dell notebook, usually made after ~2020. > +2. Dump the ACPI tables and search for the WMI device (usually called "ADDV"). > +3. Decode the corresponding bmof data and look at the ASL code. > +4. Try to deduce the meaning of a certain WMI method by comparing the control > + flow with other ACPI methods (_BIX or _BIF for battery related methods > + for example). > +5. Use the built-in UEFI diagostics to view sensor types/values for fan/thermal > + related methods (sometimes overwriting static ACPI data fields can be used > + to test different sensor type values, since on some machines this data is > + not reinitialized upon a warm reset). > + > +Alternatively: > + > +1. Load the ``dell-wmi-ddv`` driver, use the ``force`` module param > + if necessary. > +2. Use the debugfs interface to access the raw fan/thermal sensor buffer data. > +3. Compare the data with the built-in UEFI diagnostics. > + > +In case the DDV WMI interface version available on your Dell notebook is not > +supported or you are seeing unknown fan/thermal sensors, please submit a > +bugreport on `bugzilla <https://bugzilla.kernel.org>`_ so they can be added > +to the ``dell-wmi-ddv`` driver. Also don't forget to read Documentation/admin-guide/reporting-issues.rst. Regardless, the formatting LGTM, thanks! -- An old man doll... just what I always wanted! - Clara
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