platform/x86: wmi: Add device specific documentation

Add a place for device-specific documentation of WMI drivers.
The first entry is documentation for the wmi-bmof driver, with
additional documentation being expected to follow.

Signed-off-by: Armin Wolf <[e-mail]>
Tested-by: Randy Dunlap <[e-mail]>
Acked-by: Randy Dunlap <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Hans de Goede <[e-mail]>

Documentation/ABI/stable/sysfs-platform-wmi-bmof

···
+What:		/sys/bus/wmi/devices/05901221-D566-11D1-B2F0-00A0C9062910[-X]/bmof
+Date:		Jun 2017
+KernelVersion:	4.13
+Description:
+		Binary MOF metadata used to decribe the details of available ACPI WMI interfaces.
+
+		See Documentation/wmi/devices/wmi-bmof.rst for details.

Documentation/wmi/devices/index.rst

···
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+=============================
+Driver-specific Documentation
+=============================
+
+This section provides information about various devices supported by
+the Linux kernel, their protocols and driver details.
+
+.. toctree::
+   :maxdepth: 1
+   :numbered:
+   :glob:
+
+   *
+
+.. only:: subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`

Documentation/wmi/devices/wmi-bmof.rst

···
+.. SPDX-License-Identifier: GPL-2.0-only
+
+==============================
+WMI embedded Binary MOF driver
+==============================
+
+Introduction
+============
+
+Many machines embed WMI Binary MOF (Managed Object Format) metadata used to
+describe the details of their ACPI WMI interfaces. The data can be decoded
+with tools like `bmfdec <https://github.com/pali/bmfdec>`_ to obtain a
+human readable WMI interface description, which is useful for developing
+new WMI drivers.
+
+The Binary MOF data can be retrieved from the ``bmof`` sysfs attribute of the
+associated WMI device. Please note that multiple WMI devices containing Binary
+MOF data can exist on a given system.
+
+WMI interface
+=============
+
+The Binary MOF WMI device is identified by the WMI GUID ``05901221-D566-11D1-B2F0-00A0C9062910``.
+The Binary MOF can be obtained by doing a WMI data block query. The result is
+then returned as an ACPI buffer with a variable size.

Documentation/wmi/index.rst

···
    :maxdepth: 1
 
    acpi-interface
+   devices/index
 
 .. only::  subproject and html
 

MAINTAINERS

···
 S:	Odd fixes
 F:	drivers/net/wireless/legacy/wl3501*
 
+WMI BINARY MOF DRIVER
+L:	[e-mail]
+S:	Orphan
+F:	Documentation/ABI/stable/sysfs-platform-wmi-bmof
+F:	Documentation/wmi/devices/wmi-bmof.rst
+F:	drivers/platform/x86/wmi-bmof.c
+
 WOLFSON MICROELECTRONICS DRIVERS
 L:	[e-mail]
 S:	Supported

drivers/platform/x86/Kconfig

···
 	default ACPI_WMI
 	help
 	  Say Y here if you want to be able to read a firmware-embedded
-	  WMI Binary MOF data. Using this requires userspace tools and may be
-	  rather tedious.
+	  WMI Binary MOF (Managed Object Format) data. Using this requires
+	  userspace tools and may be rather tedious.
 
 	  To compile this driver as a module, choose M here: the module will
 	  be called wmi-bmof.