[PATCH v4 07/11] platform/x86: asus-wmi: add keyboard brightness event handler

[Antheas Kapenekakis <lkml@antheas.dev>]

Currenlty, the keyboard brightness control of Asus WMI keyboards is
handled in the kernel, which leads to the shortcut going from
brightness 0, to 1, to 2, and 3.

However, for HID keyboards it is exposed as a key and handled by the
user's desktop environment. For the toggle button, this means that
brightness control becomes on/off. In addition, in the absence of a
DE, the keyboard brightness does not work.

Therefore, expose an event handler for the keyboard brightness control
which can then be used by hid-asus.

Reviewed-by: Luke D. Jones <luke@ljones.dev>
Tested-by: Luke D. Jones <luke@ljones.dev>
Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
---
 drivers/platform/x86/asus-wmi.c            | 39 ++++++++++++++++++++++
 include/linux/platform_data/x86/asus-wmi.h | 11 ++++++
 2 files changed, 50 insertions(+)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index ff1d7ccb3982f..27468d67dba09 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -1536,6 +1536,45 @@ void asus_hid_unregister_listener(struct asus_hid_listener *bdev)
 }
 EXPORT_SYMBOL_GPL(asus_hid_unregister_listener);
 
+static void do_kbd_led_set(struct led_classdev *led_cdev, int value);
+
+int asus_hid_event(enum asus_hid_event event)
+{
+	unsigned long flags;
+	int brightness;
+
+	spin_lock_irqsave(&asus_ref.lock, flags);
+	if (!asus_ref.asus || !asus_ref.asus->kbd_led_registered) {
+		spin_unlock_irqrestore(&asus_ref.lock, flags);
+		return -EBUSY;
+	}
+	brightness = asus_ref.asus->kbd_led_wk;
+
+	switch (event) {
+	case ASUS_EV_BRTUP:
+		brightness += 1;
+		break;
+	case ASUS_EV_BRTDOWN:
+		brightness -= 1;
+		break;
+	case ASUS_EV_BRTTOGGLE:
+		if (brightness >= 3)
+			brightness = 0;
+		else
+			brightness += 1;
+		break;
+	}
+
+	do_kbd_led_set(&asus_ref.asus->kbd_led, brightness);
+	led_classdev_notify_brightness_hw_changed(&asus_ref.asus->kbd_led,
+						  asus_ref.asus->kbd_led_wk);
+
+	spin_unlock_irqrestore(&asus_ref.lock, flags);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(asus_hid_event);
+
 /*
  * These functions actually update the LED's, and are called from a
  * workqueue. By doing this as separate work rather than when the LED
diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index c513b5a732323..9adbe8abef090 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -162,11 +162,18 @@ struct asus_hid_listener {
 	void (*brightness_set)(struct asus_hid_listener *listener, int brightness);
 };
 
+enum asus_hid_event {
+	ASUS_EV_BRTUP,
+	ASUS_EV_BRTDOWN,
+	ASUS_EV_BRTTOGGLE,
+};
+
 #if IS_REACHABLE(CONFIG_ASUS_WMI)
 int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1, u32 *retval);
 
 int asus_hid_register_listener(struct asus_hid_listener *cdev);
 void asus_hid_unregister_listener(struct asus_hid_listener *cdev);
+int asus_hid_event(enum asus_hid_event event);
 #else
 static inline int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1,
 					   u32 *retval)
@@ -181,6 +188,10 @@ static inline int asus_hid_register_listener(struct asus_hid_listener *bdev)
 static inline void asus_hid_unregister_listener(struct asus_hid_listener *bdev)
 {
 }
+static inline int asus_hid_event(enum asus_hid_event event)
+{
+	return -ENODEV;
+}
 #endif
 
 #endif	/* __PLATFORM_DATA_X86_ASUS_WMI_H */
-- 
2.49.0