platform/x86: asus-wmi: Call led hw_changed API on kbd brightness change

Make asus-wmi notify on hotkey kbd brightness changes, listen for
brightness events and update the brightness directly in the driver.
Create new do_kbd_led_set function for in-driver update, and leave
kbd_led_set for original led_classdev call path.

Update the brightness by led_classdev_notify_brightness_hw_changed.
This will allow userspace to monitor (poll) for brightness changes
on the LED without reporting via input keymapping.

Signed-off-by: Chris Chiu <chiu@endlessm.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/asus-wmi.c

@@ -470,6 +470,7 @@ static void kbd_led_update(struct work_struct *work)
 		ctrl_param = 0x80 | (asus->kbd_led_wk & 0x7F);
 
 	asus_wmi_set_devstate(ASUS_WMI_DEVID_KBD_BACKLIGHT, ctrl_param, NULL);
+	led_classdev_notify_brightness_hw_changed(&asus->kbd_led, asus->kbd_led_wk);
 }
 
 static int kbd_led_read(struct asus_wmi *asus, int *level, int *env)
@@ -500,22 +501,29 @@ static int kbd_led_read(struct asus_wmi *asus, int *level, int *env)
 	return retval;
 }
 
-static void kbd_led_set(struct led_classdev *led_cdev,
-			enum led_brightness value)
+static void do_kbd_led_set(struct led_classdev *led_cdev, int value)
 {
 	struct asus_wmi *asus;
+	int max_level;
 
 	asus = container_of(led_cdev, struct asus_wmi, kbd_led);
+	max_level = asus->kbd_led.max_brightness;
 
-	if (value > asus->kbd_led.max_brightness)
-		value = asus->kbd_led.max_brightness;
+	if (value > max_level)
+		value = max_level;
 	else if (value < 0)
 		value = 0;
 
 	asus->kbd_led_wk = value;
 	queue_work(asus->led_workqueue, &asus->kbd_led_work);
 }
 
+static void kbd_led_set(struct led_classdev *led_cdev,
+			enum led_brightness value)
+{
+	do_kbd_led_set(led_cdev, value);
+}
+
 static enum led_brightness kbd_led_get(struct led_classdev *led_cdev)
 {
 	struct asus_wmi *asus;
@@ -666,6 +674,7 @@ static int asus_wmi_led_init(struct asus_wmi *asus)
 
 		asus->kbd_led_wk = led_val;
 		asus->kbd_led.name = "asus::kbd_backlight";
+		asus->kbd_led.flags = LED_BRIGHT_HW_CHANGED;
 		asus->kbd_led.brightness_set = kbd_led_set;
 		asus->kbd_led.brightness_get = kbd_led_get;
 		asus->kbd_led.max_brightness = 3;
@@ -1758,6 +1767,15 @@ static void asus_wmi_notify(u32 value, void *context)
 		}
 	}
 
+	if (code == NOTIFY_KBD_BRTUP) {
+		do_kbd_led_set(&asus->kbd_led, asus->kbd_led_wk + 1);
+		goto exit;
+	}
+	if (code == NOTIFY_KBD_BRTDWN) {
+		do_kbd_led_set(&asus->kbd_led, asus->kbd_led_wk - 1);
+		goto exit;
+	}
+
 	if (is_display_toggle(code) &&
 	    asus->driver->quirks->no_display_toggle)
 		goto exit;