[PATCH 05/11] platform/x86: asus-wmi: Add support for multiple kbd RGB handlers

[Antheas Kapenekakis <lkml@antheas.dev>]

Some devices, such as the Z13 have multiple AURA devices connected
to them by USB. In addition, they might have a WMI interface for
RGB. In Windows, Armoury Crate exposes a unified brightness slider
for all of them, with 3 brightness levels.

Therefore, to be synergistic in Linux, and support existing tooling
such as UPower, allow adding listeners to the RGB device of the WMI
interface. If WMI does not exist, lazy initialize the interface.

Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
---
 drivers/platform/x86/asus-wmi.c            | 100 ++++++++++++++++++---
 include/linux/platform_data/x86/asus-wmi.h |  16 ++++
 2 files changed, 104 insertions(+), 12 deletions(-)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 38ef778e8c19b..21e034be71b2f 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -254,6 +254,8 @@ struct asus_wmi {
 	int tpd_led_wk;
 	struct led_classdev kbd_led;
 	int kbd_led_wk;
+	bool kbd_led_avail;
+	bool kbd_led_registered;
 	struct led_classdev lightbar_led;
 	int lightbar_led_wk;
 	struct led_classdev micmute_led;
@@ -1487,6 +1489,46 @@ static void asus_wmi_battery_exit(struct asus_wmi *asus)
 
 /* LEDs ***********************************************************************/
 
+LIST_HEAD(asus_brt_listeners);
+DEFINE_MUTEX(asus_brt_lock);
+struct asus_wmi *asus_brt_ref;
+
+int asus_brt_register_listener(struct asus_brt_listener *bdev)
+{
+	int ret;
+
+	mutex_lock(&asus_brt_lock);
+	list_add_tail(&bdev->list, &asus_brt_listeners);
+	if (asus_brt_ref) {
+		if (asus_brt_ref->kbd_led_registered && asus_brt_ref->kbd_led_wk >= 0)
+			bdev->notify(bdev, asus_brt_ref->kbd_led_wk);
+		else {
+			asus_brt_ref->kbd_led_registered = true;
+			ret = led_classdev_register(
+				&asus_brt_ref->platform_device->dev,
+				&asus_brt_ref->kbd_led);
+		}
+	}
+	mutex_unlock(&asus_brt_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(asus_brt_register_listener);
+
+void asus_brt_unregister_listener(struct asus_brt_listener *bdev)
+{
+	mutex_lock(&asus_brt_lock);
+	list_del(&bdev->list);
+
+	if (asus_brt_ref && asus_brt_ref->kbd_led_registered &&
+	    list_empty(&asus_brt_listeners) && !asus_brt_ref->kbd_led_avail) {
+		led_classdev_unregister(&asus_brt_ref->kbd_led);
+		asus_brt_ref->kbd_led_registered = false;
+	}
+	mutex_unlock(&asus_brt_lock);
+}
+EXPORT_SYMBOL_GPL(asus_brt_unregister_listener);
+
 /*
  * These functions actually update the LED's, and are called from a
  * workqueue. By doing this as separate work rather than when the LED
@@ -1566,6 +1608,7 @@ static int kbd_led_read(struct asus_wmi *asus, int *level, int *env)
 
 static void do_kbd_led_set(struct led_classdev *led_cdev, int value)
 {
+	struct asus_brt_listener *listener;
 	struct asus_wmi *asus;
 	int max_level;
 
@@ -1573,7 +1616,12 @@ static void do_kbd_led_set(struct led_classdev *led_cdev, int value)
 	max_level = asus->kbd_led.max_brightness;
 
 	asus->kbd_led_wk = clamp_val(value, 0, max_level);
-	kbd_led_update(asus);
+
+	if (asus->kbd_led_avail)
+		kbd_led_update(asus);
+
+	list_for_each_entry(listener, &asus_brt_listeners, list)
+		listener->notify(listener, asus->kbd_led_wk);
 }
 
 static void kbd_led_set(struct led_classdev *led_cdev,
@@ -1583,15 +1631,21 @@ static void kbd_led_set(struct led_classdev *led_cdev,
 	if (led_cdev->flags & LED_UNREGISTERING)
 		return;
 
+	mutex_lock(&asus_brt_lock);
 	do_kbd_led_set(led_cdev, value);
+	mutex_unlock(&asus_brt_lock);
 }
 
 static void kbd_led_set_by_kbd(struct asus_wmi *asus, enum led_brightness value)
 {
-	struct led_classdev *led_cdev = &asus->kbd_led;
+	struct led_classdev *led_cdev;
+
+	mutex_lock(&asus_brt_lock);
+	led_cdev = &asus->kbd_led;
 
 	do_kbd_led_set(led_cdev, value);
 	led_classdev_notify_brightness_hw_changed(led_cdev, asus->kbd_led_wk);
+	mutex_unlock(&asus_brt_lock);
 }
 
 static enum led_brightness kbd_led_get(struct led_classdev *led_cdev)
@@ -1601,6 +1655,9 @@ static enum led_brightness kbd_led_get(struct led_classdev *led_cdev)
 
 	asus = container_of(led_cdev, struct asus_wmi, kbd_led);
 
+	if (!asus->kbd_led_avail)
+		return asus->kbd_led_wk;
+
 	retval = kbd_led_read(asus, &value, NULL);
 	if (retval < 0)
 		return retval;
@@ -1716,7 +1773,12 @@ static int camera_led_set(struct led_classdev *led_cdev,
 
 static void asus_wmi_led_exit(struct asus_wmi *asus)
 {
-	led_classdev_unregister(&asus->kbd_led);
+	mutex_lock(&asus_brt_lock);
+	asus_brt_ref = NULL;
+	if (asus->kbd_led_registered)
+		led_classdev_unregister(&asus->kbd_led);
+	mutex_unlock(&asus_brt_lock);
+
 	led_classdev_unregister(&asus->tpd_led);
 	led_classdev_unregister(&asus->wlan_led);
 	led_classdev_unregister(&asus->lightbar_led);
@@ -1730,6 +1792,7 @@ static void asus_wmi_led_exit(struct asus_wmi *asus)
 static int asus_wmi_led_init(struct asus_wmi *asus)
 {
 	int rv = 0, num_rgb_groups = 0, led_val;
+	bool has_listeners;
 
 	if (asus->kbd_rgb_dev)
 		kbd_rgb_mode_groups[num_rgb_groups++] = &kbd_rgb_mode_group;
@@ -1754,24 +1817,37 @@ static int asus_wmi_led_init(struct asus_wmi *asus)
 			goto error;
 	}
 
-	if (!kbd_led_read(asus, &led_val, NULL) && !dmi_check_system(asus_use_hid_led_dmi_ids)) {
-		pr_info("using asus-wmi for asus::kbd_backlight\n");
+	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;
+	asus->kbd_led_avail = !kbd_led_read(asus, &led_val, NULL);
+
+	if (asus->kbd_led_avail)
 		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;
+	else
+		asus->kbd_led_wk = -1;
+
+	if (asus->kbd_led_avail && num_rgb_groups != 0)
+		asus->kbd_led.groups = kbd_rgb_mode_groups;
 
-		if (num_rgb_groups != 0)
-			asus->kbd_led.groups = kbd_rgb_mode_groups;
+	mutex_lock(&asus_brt_lock);
+	has_listeners = !list_empty(&asus_brt_listeners);
+	mutex_unlock(&asus_brt_lock);
 
+	if (asus->kbd_led_avail || has_listeners) {
 		rv = led_classdev_register(&asus->platform_device->dev,
 					   &asus->kbd_led);
 		if (rv)
 			goto error;
+		asus->kbd_led_registered = true;
 	}
 
+	mutex_lock(&asus_brt_lock);
+	asus_brt_ref = asus;
+	mutex_unlock(&asus_brt_lock);
+
 	if (asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_WIRELESS_LED)
 			&& (asus->driver->quirks->wapf > 0)) {
 		INIT_WORK(&asus->wlan_led_work, wlan_led_update);
diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index 783e2a336861b..42e963b70acdb 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -157,14 +157,30 @@
 #define ASUS_WMI_DSTS_MAX_BRIGTH_MASK	0x0000FF00
 #define ASUS_WMI_DSTS_LIGHTBAR_MASK	0x0000000F
 
+struct asus_brt_listener {
+	struct list_head list;
+	void (*notify)(struct asus_brt_listener *listener, int brightness);
+};
+
 #if IS_REACHABLE(CONFIG_ASUS_WMI)
 int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1, u32 *retval);
+
+int asus_brt_register_listener(struct asus_brt_listener *cdev);
+void asus_brt_unregister_listener(struct asus_brt_listener *cdev);
 #else
 static inline int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1,
 					   u32 *retval)
 {
 	return -ENODEV;
 }
+
+static inline int asus_brt_register_listener(struct asus_brt_listener *bdev)
+{
+	return -ENODEV;
+}
+static inline void asus_brt_unregister_listener(struct asus_brt_listener *bdev)
+{
+}
 #endif
 
 /* To be used by both hid-asus and asus-wmi to determine which controls kbd_brightness */
-- 
2.48.1