[RFC PATCH 0/3] platform: lenovo: architecture independent home for the Lenovo WMI drivers

[David Cemin <dcemin@nvidia.com>]

Lenovo now ships ACPI based arm64 laptops whose firmware exposes the
same ACPI-WMI interfaces as the x86 IdeaPad and Legion machines: the Fn
key event GUID consumed by ideapad-laptop, the hotkey utility GUID used
for the microphone mute LED, and the GameZone, Other Mode and capability
data GUIDs behind the thermal operation modes. Since 884d53763d30
("platform/wmi: Remove dependency on CONFIG_X86") the ACPI-WMI core
builds on arm64, but the Lenovo WMI drivers still live under
drivers/platform/x86, which is gated by X86_PLATFORM_DEVICES, so none of
that code can be used where the firmware is.

This series:
  1. moves the architecture independent Lenovo WMI drivers into a new
     drivers/platform/lenovo directory, following drivers/platform/surface
     which exists for the same reason (Surface ships x86 and arm64);
     ideapad-laptop, thinkpad_acpi, think-lmi and the Yoga tablet drivers
     stay under x86 because they need i8042, port I/O or x86 only devices;
  2. adds a small WMI hotkeys driver for the Fn key event GUID on machines
     where ideapad-laptop cannot bind;
  3. makes ideapad-laptop's own WMI event driver decline the GUIDs when
     the IdeaPad VPC device is absent, since it can never report events
     there.

Patch 2 was tested on a Lenovo Yoga 9 2-in-1 16 (arm64): microphone
mute, airplane mode, the Smart Key, the Smart Connect key and the Fn+Q
operation mode key all report input events. The same key set is dead on
a Lenovo Yoga Pro 9 (arm64) today and uses the same GUID.
Patches 1 and 3 are compile tested on x86_64 and arm64 (defconfig plus
all LENOVO_WMI options as modules).

Two questions I would like the maintainers' view on before this goes
further:

  a. Is a vendor directory (drivers/platform/lenovo, like surface) the
     right home, or should the architecture independent Lenovo WMI
     drivers move under drivers/platform/wmi next to the core instead?
  b. Should the Fn key event handling stay a separate small driver, or
     be factored out of ideapad-laptop so x86 and arm64 share one path?
     ideapad-laptop handles the event only when its VPC platform driver
     is bound, and the arm64 machines expose none of the VPC interface
     it is built on (no _CFG, VPCR/VPCW, DYTC or HALS/SALS), so making
     it the single driver means gating most of its probe. Two smaller
     options: lift ideapad-laptop's own Fn key wmi_driver and keymap
     into this file and let ideapad-laptop register for the events it
     still wants (Fn lock LED, DYTC cycle), or the hid-asus/asus-wmi
     shape where a companion WMI module exports the event to a
     subsystem driver. The keymap in patch 2 duplicates entries of
     ideapad-laptop's table on purpose until that is decided.

Patch 2 declines to bind when the IdeaPad VPC device (VPC2004) is
present, so machines handled by ideapad-laptop keep it; patch 3 is the
mirror on the ideapad-laptop side. The new MAINTAINERS entry uses
platform-driver-x86, the list that already covers drivers/platform/arm64,
the ACPI-WMI core and the other Lenovo WMI drivers.


David Cemin (3):
  platform: lenovo: move the architecture independent WMI drivers out of
    x86
  platform: lenovo: add WMI hotkeys driver
  platform/x86: ideapad-laptop: do not bind the WMI event devices
    without the VPC

 MAINTAINERS                                   |   9 +-
 drivers/platform/Kconfig                      |   2 +
 drivers/platform/Makefile                     |   1 +
 drivers/platform/lenovo/Kconfig               | 101 ++++++++++++
 drivers/platform/lenovo/Makefile              |  23 +++
 .../platform/{x86 => }/lenovo/wmi-camera.c    |   0
 .../platform/{x86 => }/lenovo/wmi-capdata.c   |   0
 .../platform/{x86 => }/lenovo/wmi-capdata.h   |   0
 .../platform/{x86 => }/lenovo/wmi-events.c    |   0
 .../platform/{x86 => }/lenovo/wmi-events.h    |   0
 .../platform/{x86 => }/lenovo/wmi-gamezone.c  |   0
 .../platform/{x86 => }/lenovo/wmi-helpers.c   |   0
 .../platform/{x86 => }/lenovo/wmi-helpers.h   |   0
 .../{x86 => }/lenovo/wmi-hotkey-utilities.c   |   0
 drivers/platform/lenovo/wmi-hotkeys.c         | 151 ++++++++++++++++++
 drivers/platform/{x86 => }/lenovo/wmi-other.c |   0
 drivers/platform/x86/lenovo/Kconfig           |  67 --------
 drivers/platform/x86/lenovo/Makefile          |   7 -
 drivers/platform/x86/lenovo/ideapad-laptop.c  |   8 +
 19 files changed, 294 insertions(+), 75 deletions(-)
 create mode 100644 drivers/platform/lenovo/Kconfig
 create mode 100644 drivers/platform/lenovo/Makefile
 rename drivers/platform/{x86 => }/lenovo/wmi-camera.c (100%)
 rename drivers/platform/{x86 => }/lenovo/wmi-capdata.c (100%)
 rename drivers/platform/{x86 => }/lenovo/wmi-capdata.h (100%)
 rename drivers/platform/{x86 => }/lenovo/wmi-events.c (100%)
 rename drivers/platform/{x86 => }/lenovo/wmi-events.h (100%)
 rename drivers/platform/{x86 => }/lenovo/wmi-gamezone.c (100%)
 rename drivers/platform/{x86 => }/lenovo/wmi-helpers.c (100%)
 rename drivers/platform/{x86 => }/lenovo/wmi-helpers.h (100%)
 rename drivers/platform/{x86 => }/lenovo/wmi-hotkey-utilities.c (100%)
 create mode 100644 drivers/platform/lenovo/wmi-hotkeys.c
 rename drivers/platform/{x86 => }/lenovo/wmi-other.c (100%)


base-commit: 2800868f63227c8237d70c41e70d441c919620d6
-- 
2.56.1