platform/x86: nvidia-wmi-ec-backlight: Add force module parameter

On some Lenovo Legion models, the backlight might be driven by either
one of nvidia_wmi_ec_backlight or amdgpu_bl0 at different times.

When the Nvidia WMI EC backlight interface reports the backlight is
controlled by the EC, the current backlight handling only registers
nvidia_wmi_ec_backlight (and registers no other backlight interfaces).

This hides (never registers) the amdgpu_bl0 interface, where as prior
to 6.1.4 users would have both nvidia_wmi_ec_backlight and amdgpu_bl0
and could work around things in userspace.

Add a force module parameter which can be used with acpi_backlight=native
to restore the old behavior as a workound (for now) by passing:

"acpi_backlight=native nvidia-wmi-ec-backlight.force=1"

Fixes: 8d0ca287fd8c ("platform/x86: nvidia-wmi-ec-backlight: Use acpi_video_get_backlight_type()")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217026
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Daniel Dadap <ddadap@nvidia.com>
Link: https://lore.kernel.org/r/20230217144208.5721-1-hdegoede@redhat.com

platform/x86: nvidia-wmi-ec-backlight: Use acpi_video_get_backlight_type()

Add an acpi_video_get_backlight_type() == acpi_backlight_nvidia_wmi_ec
check. This will make nvidia-wmi-ec-backlight properly honor the user
selecting a different backlight driver through the acpi_backlight=...
kernel commandline option.

Since the auto-detect code check for nvidia-wmi-ec-backlight in
drivers/acpi/video_detect.c already checks that the WMI advertised
brightness-source is the embedded controller, this new check makes it
unnecessary for nvidia_wmi_ec_backlight_probe() to check this itself.

Suggested-by: Daniel Dadap <ddadap@nvidia.com>
Reviewed-by: Daniel Dadap <ddadap@nvidia.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: nvidia-wmi-ec-backlight: Move fw interface definitions to a header (v2)

Move the WMI interface definitions to a header, so that the definitions
can be shared with drivers/acpi/video_detect.c .

Changes in v2:
- Add missing Nvidia copyright header
- Move WMI_BRIGHTNESS_GUID to nvidia-wmi-ec-backlight.h as well

Suggested-by: Daniel Dadap <ddadap@nvidia.com>
Reviewed-by: Daniel Dadap <ddadap@nvidia.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: Rename wmaa-backlight-wmi to nvidia-wmi-ec-backlight

Rename the wmaa-backlight-wmi driver and associated KConfig option to
remove the remaining references to the "WMAA" ACPI handle which was
used in the previous name. The driver has already been updated to
remove internal references to "WMAA". As part of the renaming, the
components in the name have been rearranged to reflect the standard
vendor_wmi_feature pattern.

Signed-off-by: Daniel Dadap <ddadap@nvidia.com>
Link: https://lore.kernel.org/r/20210927202359.13684-2-ddadap@nvidia.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>