platform/x86: xiaomi-wmi: Drop unnecessary NULL checks

The WMI driver core already makes sure that:

- a valid WMI device is passed to each callback
- the notify() callback runs after the probe() callback succeeds

Remove the unnecessary NULL checks.

Compile-tested only.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20240402143059.8456-3-W_Armin@gmx.de
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: xiaomi-wmi: Fix race condition when reporting key events

Multiple WMI events can be received concurrently, so multiple instances
of xiaomi_wmi_notify() can be active at the same time. Since the input
device is shared between those handlers, the key input sequence can be
disturbed.

Fix this by protecting the key input sequence with a mutex.

Compile-tested only.

Fixes: edb73f4f0247 ("platform/x86: wmi: add Xiaomi WMI key driver")
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20240402143059.8456-2-W_Armin@gmx.de
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: wmi: Mark simple WMI drivers as legacy-free

The inspur_platform_profile driver and the xiaomi-wmi driver both
meet the requirements for modern WMI drivers, as they both do not
use the legacy GUID-based interface and can be safely instantiated
multiple times.

Mark them both as legacy-free using the no_singleton flag.

Compile-tested only.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20240402143059.8456-1-W_Armin@gmx.de
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: wmi: Make two functions static

Fix sparse warnings:

drivers/platform/x86/xiaomi-wmi.c:26:5: warning: symbol 'xiaomi_wmi_probe' was not declared. Should it be static?
drivers/platform/x86/xiaomi-wmi.c:51:6: warning: symbol 'xiaomi_wmi_notify' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

platform/x86: wmi: add Xiaomi WMI key driver

Some function keys on the built in keyboard on Xiaomi's notebooks does
not produce any key events when pressed in combination with the function
key. Some of these keys do report that they are being pressed via WMI
events.

This driver reports key events for Fn+F7 and double tap on Fn.

Other WMI events that are reported by the hardware but not utilized by
this driver are Caps Lock(which already work) and Fn lock/unlock.

Signed-off-by: Mattias Jacobsson <2pi@mok.nu>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>