[PATCH v11] platform/x86: hp-wmi: Add multicolor LED support for HP keyboard backlight

["Коненко Андрей Викторович" <admin@aquinas.su>]

Add support for the HP keyboard RGB backlight found on HP OMEN and
HP Victus laptops. These keyboards expose per-zone RGB control through
WMI commands.

Register multicolor LED class devices for each keyboard zone (up to 4
zones, depending on the keyboard type). Each zone exposes individual
red, green, and blue channels via the multicolor LED subsystem.

Also hardware-initiated brightness changes (e.g. via the keyboard
backlight hotkey, mostly fn+f4) are reported.

The color data is stored in a 128-byte color table managed by the
firmware, with RGB values starting at offset 25, packed sequentially
per zone.

Signed-off-by: Konenko Andrey Viktorovich <admin@aquinas.su>

---
Changes since v10:
 - adapted for current linux-next (20260914)
 - Added Named Constants:
	HP_BACKLIGHT_EVENT_ON — replaces magic number for backlight enable event
	HP_BACKLIGHT_EVENT_OFF — replaces magic number for backlight disable event
	HP_KBD_RGB_COLORS — replaces universally used literal 3 as RGB color/channel count
 - Refactored hp_kbd_brightness_set_by_hwd Function - Eliminated reliance on magic numbers in event handling logic (bugfix)
 - Event Filtering (critical bugfix):
	Added event type filtering in hp_wmi_notify() before calling hp_kbd_brightness_set_by_hwd()
	This prevents EC flooding and keyboard malfunction on some devices

Changes since v9:
 - Fixed corrupted long lines
 - Fixed changelog

Changes since v8:
 - No changes (It was mistake to resend email without any fix)

Changes since v7:
 - The LED class device names changed to be consistent with the documentation.

Changes since v6:
 - The LED class device names have been made more consistent with the 
documentation, in accordance with patch https://lore.kernel.org/linux-leds/
20260504145434.12746-1-johannes.goede@oss.qualcomm.com/
underscores have been replaced with dashes where indicated.

Changes since v5:
 - LED class device names changed from a number to using a descriptive name 
for each zone.

v4: https://lore.kernel.org/all/20260303084022.7223-3-edip@medip.dev/

Changes since v4:
 - Fix circular dependencies

Changes since v3:
 - Merge the changes into a single commit

Changes since v1:
 - Fix mentioned style errors
 - Add Kconfig dependencies

---
 drivers/platform/x86/hp/Kconfig  |   2 +
 drivers/platform/x86/hp/hp-wmi.c | 298 ++++++++++++++++++++++++++++++-
 2 files changed, 299 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/hp/Kconfig b/drivers/platform/x86/hp/Kconfig
index dd51491b9bcd..2a1841cbec76 100644
--- a/drivers/platform/x86/hp/Kconfig
+++ b/drivers/platform/x86/hp/Kconfig
@@ -45,6 +45,8 @@ config HP_WMI
 	select INPUT_SPARSEKMAP
 	select ACPI_PLATFORM_PROFILE
 	select HWMON
+	select LEDS_CLASS
+	select LEDS_CLASS_MULTICOLOR
 	help
 	  Say Y here if you want to support WMI-based hotkeys on HP laptops and
 	  to read data from WMI such as docking or ambient light sensor state.
diff --git a/drivers/platform/x86/hp/hp-wmi.c b/drivers/platform/x86/hp/hp-wmi.c
index 615b4cf6fc45..cf57b6b00b01 100644
--- a/drivers/platform/x86/hp/hp-wmi.c
+++ b/drivers/platform/x86/hp/hp-wmi.c
@@ -28,6 +28,8 @@
 #include <linux/kstrtox.h>
 #include <linux/limits.h>
 #include <linux/minmax.h>
+#include <linux/led-class-multicolor.h>
+#include <linux/leds.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
@@ -61,6 +63,10 @@ enum hp_ec_offsets {
 #define HP_FAN_SPEED_AUTOMATIC	 0x00
 #define HP_POWER_LIMIT_DEFAULT	 0x00
 #define HP_POWER_LIMIT_NO_CHANGE 0xFF
+#define HP_COLOR_TABLE_PADDING  25
+#define HP_BACKLIGHT_EVENT_ON   0x2
+#define HP_BACKLIGHT_EVENT_OFF  0x0
+#define HP_KBD_RGB_COLORS       3
 #define HPWMI_MUX_MODE_UMA		BIT(0)
 #define HPWMI_MUX_MODE_HYBRID		BIT(1)
 #define HPWMI_MUX_MODE_DISCRETE		BIT(2)
@@ -106,6 +112,14 @@ enum hp_thermal_profile {
 	HP_THERMAL_PROFILE_QUIET			= 0x03,
 };
 
+enum hp_keyboard_type {
+	HP_KEYBOARD_TYPE_NOBACKLIGHT		= 0x0,
+	HP_KEYBOARD_TYPE_FOURZONE_WITH_NUMPAD	= 0x1,
+	HP_KEYBOARD_TYPE_FOURZONE_WITHOUT_NUMPAD	= 0x2,
+	HP_KEYBOARD_TYPE_RGB_PER_KEY		= 0x3,
+	HP_KEYBOARD_TYPE_SINGLEZONE_WITH_NUMPAD	= 0x4,
+	HP_KEYBOARD_TYPE_SINGLEZONE_WITHOUT_NUMPAD	= 0x5,
+};
 
 struct thermal_profile_params {
 	u8 performance;
@@ -433,16 +447,27 @@ enum hp_wmi_gm_commandtype {
 	HPWMI_GET_GPU_THERMAL_MODES_QUERY	= 0x21,
 	HPWMI_SET_GPU_THERMAL_MODES_QUERY	= 0x22,
 	HPWMI_SET_POWER_LIMITS_QUERY		= 0x29,
+	HPWMI_GET_KEYBOARD_TYPE_QUERY		= 0x2b,
 	HPWMI_VICTUS_S_FAN_SPEED_GET_QUERY	= 0x2D,
 	HPWMI_VICTUS_S_FAN_SPEED_SET_QUERY	= 0x2E,
 	HPWMI_VICTUS_S_GET_FAN_TABLE_QUERY	= 0x2F,
 };
 
+enum hp_wmi_backlight_commandtype {
+	HPWMI_BACKLIGHT_COLOR_GET_QUERY		= 0x02,
+	HPWMI_BACKLIGHT_COLOR_SET_QUERY		= 0x03,
+	HPWMI_BACKLIGHT_BRIGHTNESS_GET_QUERY	= 0x04,
+	HPWMI_BACKLIGHT_BRIGHTNESS_SET_QUERY	= 0x05,
+	HPWMI_BACKLIGHT_SET_OFF_QUERY		= 0x64,
+	HPWMI_BACKLIGHT_SET_ON_QUERY		= 0xE4,
+};
+
 enum hp_wmi_command {
 	HPWMI_READ	= 0x01,
 	HPWMI_WRITE	= 0x02,
 	HPWMI_ODM	= 0x03,
 	HPWMI_GM	= 0x20008,
+	HPWMI_BACKLIGHT	= 0x20009,
 };
 
 enum hp_wmi_hardware_mask {
@@ -450,6 +475,24 @@ enum hp_wmi_hardware_mask {
 	HPWMI_TABLET_MASK	= 0x04,
 };
 
+struct hp_kbd_led_priv {
+	int zone;               /* Zone index (0-3) */
+	enum led_brightness last_brightness;  /* Brightness before turning off */
+};
+
+struct hp_mc_leds {
+	struct led_classdev_mc devices[4];
+	struct hp_kbd_led_priv priv[4];
+};
+
+/* zone naming for 4-zone keyboards (HP Omen) */
+static const char *const hp_zone_names_4[] = {
+	[0] = "zoned_backlight-right",
+	[1] = "zoned_backlight-center",
+	[2] = "zoned_backlight-left",
+	[3] = "zoned_backlight-wasd",
+};
+
 struct bios_return {
 	u32 sigpass;
 	u32 return_code;
@@ -530,6 +573,7 @@ static DEFINE_MUTEX(active_platform_profile_lock);
 static struct input_dev *hp_wmi_input_dev;
 static struct input_dev *camera_shutter_input_dev;
 static struct platform_device *hp_wmi_platform_dev;
+static struct hp_mc_leds hp_multicolor_leds;
 static struct device *platform_profile_device;
 static struct notifier_block platform_power_source_nb;
 static enum platform_profile_option active_platform_profile;
@@ -1338,6 +1382,8 @@ static struct attribute *hp_wmi_attrs[] = {
 };
 ATTRIBUTE_GROUPS(hp_wmi);
 
+static void hp_kbd_brightness_set_by_hwd(u32 event_data);
+
 static void hp_wmi_notify(union acpi_object *obj, void *context)
 {
 	u32 event_id, event_data;
@@ -1438,6 +1484,16 @@ static void hp_wmi_notify(union acpi_object *obj, void *context)
 	case HPWMI_PROXIMITY_SENSOR:
 		break;
 	case HPWMI_BACKLIT_KB_BRIGHTNESS:
+		/*
+		 * Only handle actual backlight events (0x0 and 0x2).
+		 * Other event_data values (like keyboard scan codes, e.g. 0x20 for 'd')
+		 * are keyboard events and should be handled via sparse_keymap,
+		 * not treated as brightness control commands.
+		 */
+		if (event_data != HP_BACKLIGHT_EVENT_ON &&
+		    event_data != HP_BACKLIGHT_EVENT_OFF)
+			break;
+		hp_kbd_brightness_set_by_hwd(event_data);
 		break;
 	case HPWMI_PEAKSHIFT_PERIOD:
 		break;
@@ -1700,6 +1756,244 @@ static int __init hp_wmi_rfkill2_setup(struct platform_device *device)
 	return err;
 }
 
+static struct hp_kbd_led_priv *hp_led_get_priv(struct led_classdev *led_cdev)
+{
+	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(led_cdev);
+	int zone = mc_cdev - hp_multicolor_leds.devices;
+
+	return &hp_multicolor_leds.priv[zone];
+}
+
+static int hp_kbd_backlight_set_rgb_color(int zone, int red, int green, int blue)
+{
+	u8 color_table[128];
+	int ret;
+
+	/*
+	 * Get the current color table and then change only the relevant parts.
+	 */
+	ret = hp_wmi_perform_query(HPWMI_BACKLIGHT_COLOR_GET_QUERY,
+				  HPWMI_BACKLIGHT, color_table,
+				  zero_if_sup(color_table),
+				  sizeof(color_table));
+	if (ret)
+		return ret;
+
+	/*
+	 * RGB color data starts at offset 25 +3 per zone (r g b)
+	 * e.g. if zone 1 starts in 25 zone 2 starts in 28
+	 */
+	color_table[HP_COLOR_TABLE_PADDING + zone * HP_KBD_RGB_COLORS]     = red;
+	color_table[HP_COLOR_TABLE_PADDING + zone * HP_KBD_RGB_COLORS + 1] = green;
+	color_table[HP_COLOR_TABLE_PADDING + zone * HP_KBD_RGB_COLORS + 2] = blue;
+
+	ret = hp_wmi_perform_query(HPWMI_BACKLIGHT_COLOR_SET_QUERY, HPWMI_BACKLIGHT,
+				  color_table, sizeof(color_table), sizeof(color_table));
+	if (ret < 0)
+		return ret;
+	if (ret)
+		return -EINVAL;
+
+	return 0;
+}
+
+static bool hp_kbd_backlight_is_on(void)
+{
+	u8 data;
+	int ret;
+
+	ret = hp_wmi_perform_query(HPWMI_BACKLIGHT_BRIGHTNESS_GET_QUERY, HPWMI_BACKLIGHT, &data,
+				sizeof(data), sizeof(data));
+	if (ret)
+		return false;
+
+	return data == HPWMI_BACKLIGHT_SET_ON_QUERY;
+}
+
+static int hp_kbd_set_brightness(struct led_classdev *led_cdev,
+					enum led_brightness brightness)
+{
+	struct hp_kbd_led_priv *priv = hp_led_get_priv(led_cdev);
+	struct led_classdev_mc *mc_cdev;
+	struct led_classdev_mc *device;
+	int red, green, blue;
+	int ret;
+
+	if (!hp_kbd_backlight_is_on()) {
+		u8 data = HPWMI_BACKLIGHT_SET_ON_QUERY;
+
+		ret = hp_wmi_perform_query(HPWMI_BACKLIGHT_BRIGHTNESS_SET_QUERY,
+					   HPWMI_BACKLIGHT, &data,
+					   sizeof(data), sizeof(data));
+		if (ret)
+			return ret;
+
+		/*
+		 * Turning the backlight on via WMI turns all zones,
+		 * so we need to restore the other zones' off state.
+		 */
+		for (int i = 0; i < ARRAY_SIZE(hp_multicolor_leds.devices); i++) {
+			if (i == priv->zone)
+				continue;
+
+			device = &hp_multicolor_leds.devices[i];
+			if (!device->led_cdev.name)
+				continue;
+			hp_kbd_backlight_set_rgb_color(i,
+				device->subled_info[0].brightness,
+				device->subled_info[1].brightness,
+				device->subled_info[2].brightness);
+		}
+	}
+
+	led_cdev->brightness = brightness;
+
+	mc_cdev = lcdev_to_mccdev(led_cdev);
+	led_mc_calc_color_components(mc_cdev, brightness);
+
+	red = mc_cdev->subled_info[0].brightness;
+	green = mc_cdev->subled_info[1].brightness;
+	blue = mc_cdev->subled_info[2].brightness;
+
+	return hp_kbd_backlight_set_rgb_color(priv->zone, red, green, blue);
+}
+
+static void hp_kbd_brightness_set_by_hwd(u32 event_data)
+{
+	struct device *dev = &hp_wmi_platform_dev->dev;
+	struct led_classdev *led_cdev;
+	struct hp_kbd_led_priv *priv;
+	u8 brightness;
+
+	for (int zone = 0; zone < ARRAY_SIZE(hp_multicolor_leds.devices); zone++) {
+		if (!hp_multicolor_leds.devices[zone].led_cdev.name)
+			continue;
+
+		led_cdev = &hp_multicolor_leds.devices[zone].led_cdev;
+		if (!led_cdev->dev)
+			continue;
+
+		priv = hp_led_get_priv(led_cdev);
+
+		switch (event_data) {
+		case HP_BACKLIGHT_EVENT_ON:
+			brightness = priv->last_brightness ? : LED_FULL;
+			break;
+		case HP_BACKLIGHT_EVENT_OFF:
+			priv->last_brightness = led_cdev->brightness;
+			brightness = LED_OFF;
+			break;
+		default:
+			dev_warn(dev, "Unknown keyboard backlight event - 0x%x\n",
+				 event_data);
+			return;
+		}
+
+		led_cdev->brightness = brightness;
+		led_classdev_notify_brightness_hw_changed(led_cdev, brightness);
+	}
+}
+
+static int __init hp_mc_leds_register(int num_zones)
+{
+	u8 color_table[128];
+	int ret;
+
+	ret = hp_wmi_perform_query(HPWMI_BACKLIGHT_COLOR_GET_QUERY, HPWMI_BACKLIGHT,
+				  color_table, zero_if_sup(color_table),
+				  sizeof(color_table));
+	if (ret)
+		return ret;
+
+	for (int zone = 0; zone < num_zones; zone++) {
+		struct led_classdev_mc *multicolor_led_dev;
+		struct led_classdev *led_cdev;
+		struct mc_subled *mc_subled_info;
+		struct hp_kbd_led_priv *priv;
+		struct device *dev;
+
+		dev = &hp_wmi_platform_dev->dev;
+		multicolor_led_dev = &hp_multicolor_leds.devices[zone];
+		led_cdev = &multicolor_led_dev->led_cdev;
+		priv = &hp_multicolor_leds.priv[zone];
+
+		if (num_zones == 1)
+			led_cdev->name = devm_kasprintf(dev, GFP_KERNEL,
+				"hp::kbd_backlight");
+		else if (num_zones == 4 && zone < ARRAY_SIZE(hp_zone_names_4))
+			led_cdev->name = devm_kasprintf(dev, GFP_KERNEL,
+				"hp::kbd_%s",
+				hp_zone_names_4[zone]);
+		else if (num_zones > 1)
+			led_cdev->name = devm_kasprintf(dev, GFP_KERNEL,
+				"hp::kbd_zoned_backlight-%d",
+				zone);
+
+		if (!led_cdev->name)
+			return -ENOMEM;
+		led_cdev->brightness = hp_kbd_backlight_is_on() ?
+				       LED_FULL : LED_OFF;
+		led_cdev->max_brightness = LED_FULL;
+		led_cdev->brightness_set_blocking = hp_kbd_set_brightness;
+		led_cdev->flags = LED_CORE_SUSPENDRESUME |
+				  LED_RETAIN_AT_SHUTDOWN |
+				  LED_BRIGHT_HW_CHANGED;
+
+		mc_subled_info = devm_kzalloc(dev, sizeof(*mc_subled_info) * HP_KBD_RGB_COLORS,
+					      GFP_KERNEL);
+		if (!mc_subled_info)
+			return -ENOMEM;
+
+		mc_subled_info[0].color_index = LED_COLOR_ID_RED;
+		mc_subled_info[1].color_index = LED_COLOR_ID_GREEN;
+		mc_subled_info[2].color_index = LED_COLOR_ID_BLUE;
+
+		for (int i = 0; i < HP_KBD_RGB_COLORS; i++) {
+			int off = HP_COLOR_TABLE_PADDING + zone * HP_KBD_RGB_COLORS + i;
+
+			mc_subled_info[i].channel = zone * HP_KBD_RGB_COLORS + i;
+			mc_subled_info[i].intensity = color_table[off];
+			mc_subled_info[i].brightness = LED_FULL;
+		}
+
+		multicolor_led_dev->subled_info = mc_subled_info;
+		multicolor_led_dev->num_colors = HP_KBD_RGB_COLORS;
+
+		ret = devm_led_classdev_multicolor_register(dev, multicolor_led_dev);
+		if (ret) {
+			dev_err(dev, "Failed to register multicolor RGB backlight\n");
+			return ret;
+		}
+
+		/* Initialize private data */
+		priv->zone = zone;
+		priv->last_brightness = LED_FULL;
+	}
+	return 0;
+}
+
+static int __init hp_kbd_rgb_setup(void)
+{
+	u8 keyboard_type;
+	int ret;
+
+	ret = hp_wmi_perform_query(HPWMI_GET_KEYBOARD_TYPE_QUERY, HPWMI_GM, &keyboard_type,
+				sizeof(keyboard_type), sizeof(keyboard_type));
+	if (ret)
+		return ret;
+
+	switch (keyboard_type) {
+	case HP_KEYBOARD_TYPE_FOURZONE_WITH_NUMPAD:
+	case HP_KEYBOARD_TYPE_FOURZONE_WITHOUT_NUMPAD:
+		return hp_mc_leds_register(4);
+	case HP_KEYBOARD_TYPE_SINGLEZONE_WITH_NUMPAD:
+	case HP_KEYBOARD_TYPE_SINGLEZONE_WITHOUT_NUMPAD:
+		return hp_mc_leds_register(1);
+	default:
+		return 0;
+	}
+}
+
 static int platform_profile_omen_get_ec(enum platform_profile_option *profile)
 {
 	int tp;
@@ -2541,7 +2835,9 @@ static int __init hp_wmi_bios_setup(struct platform_device *device)
 		return err;
 
 	thermal_profile_setup(device);
-
+	err = hp_kbd_rgb_setup();
+	if (err)
+		dev_err(&device->dev, "Failed to initialize keyboard RGB\n");
 	return 0;
 }
 
-- 
2.55.0