On Thu, 9 Jul 2026, Yo-Jung Leo Lin (AMD) wrote: > The Halo Box features an RGB LED light bar that can be controlled > through WMI methods to display any color combination. > > The driver exposes the LED through the LED multicolor subsystem, > allowing userspace to control RGB values via sysfs: > /sys/class/leds/amd_halo:multicolor:status/multi_intensity > /sys/class/leds/amd_halo:multicolor:status/brightness > > Hardware interface: > - Three separate RGB channels (Red, Green, Blue) > - All 3 channels are configured at once with a single WMI method call > - Value range: 0-100 (matching hardware range directly) > > Co-developed-by: Mario Limonciello (AMD) > Signed-off-by: Mario Limonciello (AMD) > Reviewed-by: Shyam Sundar S K > Reviewed-by: Armin Wolf > Signed-off-by: Yo-Jung Leo Lin (AMD) > --- > To: Hans de Goede > To: Ilpo Järvinen > To: Mario Limonciello (AMD) > To: Yo-Jung Leo Lin (AMD) > Cc: linux-kernel@vger.kernel.org > Cc: platform-driver-x86@vger.kernel.org > > v7 -> v8 > - Move local variables to the beginnign of function. (Ilpo) > - Add trailing commas to enum declaratiion. (Ilpo) > - Fix more white spaces > - Remove redundant comments > - Link to v7: https://lore.kernel.org/r/20260611-halo-leds-v2-plus-v7-1-8aad73fccb6b@amd.com > > v6 -> v7 > - Introduce a amd_halo_wmi_get_rgb() to get WMI values of colors, and > read them on probe. > - Remove hard-coded RGB values. > - Link to v6: https://lore.kernel.org/r/20260529-halo-leds-v2-plus-v6-1-b7bf7b904a16@amd.com > > v5 -> v6 > - Add missing includes and sort/group them accordingly > - In __amd_halo_wmi_call, remove some unnecessary intermedaite variable assignments > - In __amd_halo_wmi_call, move declaration of pointer managed by scope-based cleanup > helpers closer to where it is used > - Add trailing comma to designated initializers > - Link to v5: https://lore.kernel.org/r/20260523-halo-leds-v2-plus-v5-1-497dc9719a18@amd.com > --- > MAINTAINERS | 7 + > drivers/platform/x86/amd/Kconfig | 11 ++ > drivers/platform/x86/amd/Makefile | 1 + > drivers/platform/x86/amd/amd_halo_led.c | 315 ++++++++++++++++++++++++++++++++ > 4 files changed, 334 insertions(+) > > diff --git a/MAINTAINERS b/MAINTAINERS > index 15011f5752a99..3b774bc8889c5 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -1138,6 +1138,13 @@ F: drivers/char/hw_random/geode-rng.c > F: drivers/crypto/geode* > F: drivers/video/fbdev/geode/ > > +AMD HALO BOX RGB LED DRIVER > +M: Mario Limonciello (AMD) > +R: Yo-Jung Leo Lin (AMD) > +L: platform-driver-x86@vger.kernel.org > +S: Supported > +F: drivers/platform/x86/amd/amd_halo_led.c > + > AMD HSMP DRIVER > M: Naveen Krishna Chatradhi > R: Carlos Bilbao > diff --git a/drivers/platform/x86/amd/Kconfig b/drivers/platform/x86/amd/Kconfig > index b813f92653686..a1a74ef6c8593 100644 > --- a/drivers/platform/x86/amd/Kconfig > +++ b/drivers/platform/x86/amd/Kconfig > @@ -34,6 +34,17 @@ config AMD_WBRF > This mechanism will only be activated on platforms that advertise a > need for it. > > +config AMD_HALO_LED > + tristate "AMD Halo Box RGB LED Driver" > + depends on ACPI_WMI && LEDS_CLASS_MULTICOLOR > + help > + This driver provides RGB LED control for AMD Halo Box devices > + through the LED multicolor subsystem. The Halo Box light bar can > + be controlled via sysfs to display any RGB color combination. > + > + To compile this driver as a module, choose M here: the module > + will be called amd_halo_led. > + > config AMD_ISP_PLATFORM > tristate "AMD ISP4 platform driver" > depends on I2C && X86_64 && ACPI > diff --git a/drivers/platform/x86/amd/Makefile b/drivers/platform/x86/amd/Makefile > index f6ff0c837f345..2f467dbbfc8a3 100644 > --- a/drivers/platform/x86/amd/Makefile > +++ b/drivers/platform/x86/amd/Makefile > @@ -10,5 +10,6 @@ obj-$(CONFIG_AMD_PMC) += pmc/ > obj-$(CONFIG_AMD_HSMP) += hsmp/ > obj-$(CONFIG_AMD_PMF) += pmf/ > obj-$(CONFIG_AMD_WBRF) += wbrf.o > +obj-$(CONFIG_AMD_HALO_LED) += amd_halo_led.o > obj-$(CONFIG_AMD_ISP_PLATFORM) += amd_isp4.o > obj-$(CONFIG_AMD_HFI) += hfi/ > diff --git a/drivers/platform/x86/amd/amd_halo_led.c b/drivers/platform/x86/amd/amd_halo_led.c > new file mode 100644 > index 0000000000000..b21d956c7d96c > --- /dev/null > +++ b/drivers/platform/x86/amd/amd_halo_led.c > @@ -0,0 +1,315 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * AMD Halo Box RGB LED Driver > + * > + * Copyright (C) 2026 Advanced Micro Devices, Inc. > + * > + * This driver provides RGB LED control for AMD Halo Box devices through > + * the LED multicolor subsystem. The Halo Box light bar can be controlled > + * via sysfs to display any RGB color combination. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > + > +#define AMD_HALO_GUID "081E747B-E028-4232-AF24-EAAEAB2B1E86" > + > +/* WMI method IDs from MOF */ > +enum { > + AMD_HALO_WMI_TURN_OFF = 0x04, > + AMD_HALO_WMI_RGB = 0x07, > +}; > + > +/* Arg0 of the AMD_HALO_WMI_RGB Method */ > +enum { > + AMD_HALO_RGB_CMD_GET = 0x0, > + AMD_HALO_RGB_CMD_SET = 0x1, > +}; > + > +/* Status codes from spec */ > +#define AMD_HALO_STATUS_SUCCESS 0x0000 > +#define AMD_HALO_STATUS_INVALID_PARAM 0xFFFD > + > +/* Brightness uses 0-100 range */ > +#define AMD_HALO_MAX_HW_BRIGHTNESS 100 > + > +/** > + * struct amd_halo_led_data - Driver private data > + * @wdev: WMI device pointer > + * @led_mc: LED multicolor class device > + * @subled_info: RGB channel information > + * @lock: Mutex to protect WMI calls > + */ > +struct amd_halo_led_data { > + struct wmi_device *wdev; > + struct led_classdev_mc led_mc; > + struct mc_subled subled_info[3]; > + struct mutex lock; Please put the comment back to explain what this lock protects. -- i. > +}; > + > +struct amd_halo_wmi_args { > + __le32 arg0; > + __le32 arg1; > +}; > + > +struct amd_halo_wmi_args_rgb { > + __le32 cmd; > + __le32 red; > + __le32 green; > + __le32 blue; > +}; > + > +struct amd_halo_wmi_output_rgb { > + __le16 status; > + u8 red; > + u8 green; > + u8 blue; > +} __packed; > + > +static inline int wmi_status_to_err(u16 status) > +{ > + switch (status) { > + case AMD_HALO_STATUS_SUCCESS: > + return 0; > + case AMD_HALO_STATUS_INVALID_PARAM: > + return -EINVAL; > + default: > + return -EIO; > + } > +} > + > +static int __amd_halo_wmi_call(struct wmi_device *wdev, > + u32 method_id, void *data, size_t length) > +{ > + struct wmi_buffer input = { > + .length = length, > + .data = data, > + }; > + struct wmi_buffer output = { }; > + int ret; > + > + /* Return buffer per spec: Bytes[0:1] = Status (little-endian) */ > + ret = wmidev_invoke_method(wdev, 0, method_id, > + &input, &output, sizeof(__le16)); > + if (ret) > + return ret; > + > + __le16 *result_status __free(kfree) = output.data; > + > + return wmi_status_to_err(le16_to_cpu(*result_status)); > +} > + > +/** > + * amd_halo_wmi_turn_off - Turn off all LED channels > + * @wdev: WMI device pointer > + * > + * Return: 0 on success, negative error code on failure > + */ > +static int amd_halo_wmi_turn_off(struct wmi_device *wdev) > +{ > + struct amd_halo_wmi_args args = { }; > + > + return __amd_halo_wmi_call(wdev, AMD_HALO_WMI_TURN_OFF, &args, sizeof(args)); > +} > + > +/** > + * amd_halo_wmi_set_rgb - Set all RGB channels atomically > + * @wdev: WMI device pointer > + * @r: brightness for red channel (0 - 100) > + * @g: brightness for green channel (0 - 100) > + * @b: brightness for blue channel (0 - 100) > + * > + * Return: 0 on success, negative error code on failure > + */ > +static int amd_halo_wmi_set_rgb(struct wmi_device *wdev, u32 r, u32 g, u32 b) > +{ > + struct amd_halo_wmi_args_rgb args = { > + .cmd = cpu_to_le32(AMD_HALO_RGB_CMD_SET), > + .red = cpu_to_le32(r), > + .green = cpu_to_le32(g), > + .blue = cpu_to_le32(b), > + }; > + > + if (r > AMD_HALO_MAX_HW_BRIGHTNESS || > + g > AMD_HALO_MAX_HW_BRIGHTNESS || > + b > AMD_HALO_MAX_HW_BRIGHTNESS) { > + return -EINVAL; > + } > + > + return __amd_halo_wmi_call(wdev, AMD_HALO_WMI_RGB, &args, sizeof(args)); > +} > + > +/** > + * amd_halo_wmi_get_rgb - Get RGB values > + * @wdev: WMI device pointer > + * @r: output buffer for red value > + * @g: output buffer for green value > + * @b: output buffer for blue value > + * > + * Return: 0 on success, negative error code on failure > + */ > +static int amd_halo_wmi_get_rgb(struct wmi_device *wdev, u8 *r, u8 *g, u8 *b) > +{ > + struct amd_halo_wmi_args_rgb args = { > + .cmd = cpu_to_le32(AMD_HALO_RGB_CMD_GET), > + }; > + struct wmi_buffer input = { > + .length = sizeof(args), > + .data = &args, > + }; > + struct wmi_buffer output = { }; > + int ret; > + > + ret = wmidev_invoke_method(wdev, 0, AMD_HALO_WMI_RGB, > + &input, &output, sizeof(struct amd_halo_wmi_output_rgb)); > + if (ret) > + return ret; > + > + struct amd_halo_wmi_output_rgb *data __free(kfree) = output.data; > + > + ret = wmi_status_to_err(le16_to_cpu(data->status)); > + if (ret) > + return ret; > + > + if (data->red > AMD_HALO_MAX_HW_BRIGHTNESS || > + data->green > AMD_HALO_MAX_HW_BRIGHTNESS || > + data->blue > AMD_HALO_MAX_HW_BRIGHTNESS) { > + return -EPROTO; > + } > + > + *r = data->red; > + *g = data->green; > + *b = data->blue; > + > + return 0; > +} > + > +/** > + * amd_halo_brightness_set - Set LED brightness > + * @cdev: LED class device > + * @brightness: Brightness value > + * > + * Return: 0 on success, negative error code on failure > + */ > +static int amd_halo_brightness_set(struct led_classdev *cdev, > + enum led_brightness brightness) > +{ > + struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev); > + struct amd_halo_led_data *data = container_of(mc_cdev, > + struct amd_halo_led_data, > + led_mc); > + u32 red_hw, green_hw, blue_hw; > + int ret; > + > + guard(mutex)(&data->lock); > + > + led_mc_calc_color_components(mc_cdev, brightness); > + > + if (brightness == 0) > + return amd_halo_wmi_turn_off(data->wdev); > + > + red_hw = mc_cdev->subled_info[0].brightness; > + green_hw = mc_cdev->subled_info[1].brightness; > + blue_hw = mc_cdev->subled_info[2].brightness; > + > + ret = amd_halo_wmi_set_rgb(data->wdev, red_hw, green_hw, blue_hw); > + if (ret) > + goto out; > + > + return 0; > + > +out: > + /* > + * Consider the light bar non-functional if AMD_HALO_WMI_RGB failed. > + * Attempt to turn the LED off completely as clean-up. > + */ > + if (amd_halo_wmi_turn_off(data->wdev)) > + dev_warn_ratelimited(&data->wdev->dev, "Failed to turn LED off on cleanup\n"); > + > + return ret; > +} > + > +static int amd_halo_probe(struct wmi_device *wdev, const void *context) > +{ > + struct led_init_data led_init_data = { > + .devicename = "amd_halo", > + .default_label = "multicolor:" LED_FUNCTION_STATUS, > + .devname_mandatory = true, > + }; > + struct amd_halo_led_data *data; > + u8 r, g, b; > + int ret; > + > + data = devm_kzalloc(&wdev->dev, sizeof(*data), GFP_KERNEL); > + if (!data) > + return -ENOMEM; > + > + ret = devm_mutex_init(&wdev->dev, &data->lock); > + if (ret) > + return ret; > + > + data->wdev = wdev; > + dev_set_drvdata(&wdev->dev, data); > + > + data->subled_info[0].color_index = LED_COLOR_ID_RED; > + data->subled_info[1].color_index = LED_COLOR_ID_GREEN; > + data->subled_info[2].color_index = LED_COLOR_ID_BLUE; > + > + data->led_mc.led_cdev.brightness = AMD_HALO_MAX_HW_BRIGHTNESS; > + data->led_mc.led_cdev.max_brightness = AMD_HALO_MAX_HW_BRIGHTNESS; > + data->led_mc.led_cdev.brightness_set_blocking = amd_halo_brightness_set; > + data->led_mc.led_cdev.flags = LED_CORE_SUSPENDRESUME | LED_RETAIN_AT_SHUTDOWN; > + data->led_mc.num_colors = ARRAY_SIZE(data->subled_info); > + data->led_mc.subled_info = data->subled_info; > + > + ret = amd_halo_wmi_get_rgb(wdev, &r, &g, &b); > + if (ret) > + return ret; > + > + data->subled_info[0].intensity = r; > + data->subled_info[1].intensity = g; > + data->subled_info[2].intensity = b; > + > + ret = devm_led_classdev_multicolor_register_ext(&wdev->dev, &data->led_mc, > + &led_init_data); > + if (ret) > + return dev_err_probe(&wdev->dev, ret, > + "Failed to register multicolor LED\n"); > + return 0; > +} > + > +static const struct wmi_device_id amd_halo_id_table[] = { > + { .guid_string = AMD_HALO_GUID }, > + { } > +}; > +MODULE_DEVICE_TABLE(wmi, amd_halo_id_table); > + > +static struct wmi_driver amd_halo_driver = { > + .driver = { > + .name = "amd_halo_led", > + }, > + .id_table = amd_halo_id_table, > + .probe = amd_halo_probe, > + .no_singleton = true, > +}; > + > +module_wmi_driver(amd_halo_driver); > + > +MODULE_AUTHOR("Mario Limonciello (AMD) "); > +MODULE_AUTHOR("Yo-Jung Leo Lin (AMD) "); > +MODULE_DESCRIPTION("AMD Halo Box RGB LED Control Driver"); > +MODULE_LICENSE("GPL"); > > --- > base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482 > change-id: 20260429-halo-leds-v2-plus-722c8083afe8 > > Best regards, >