A number of upcoming notebook computer designs drive the internal display panel's backlight PWM through the Embedded Controller (EC). This EC-based backlight control can be plumbed through to an ACPI "WMAA" method interface, which in turn can be wrapped by WMI with the GUID handle 603E9613-EF25-4338-A3D0-C46177516DB7. Add a new driver, aliased to the WMAA WMI GUID, to expose a sysfs backlight class driver to control backlight levels on systems with EC-driven backlights. Signed-off-by: Aaron Plattner <aplattner@xxxxxxxxxx> Signed-off-by: Daniel Dadap <ddadap@xxxxxxxxxx> --- MAINTAINERS | 6 + drivers/platform/x86/Kconfig | 11 ++ drivers/platform/x86/Makefile | 2 + drivers/platform/x86/wmaa-backlight-wmi.c | 153 ++++++++++++++++++++++ 4 files changed, 172 insertions(+) create mode 100644 drivers/platform/x86/wmaa-backlight-wmi.c diff --git a/MAINTAINERS b/MAINTAINERS index eeff55560759..e5ce6544a3c8 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -18249,6 +18249,12 @@ L: linux-wireless@xxxxxxxxxxxxxxx S: Odd fixes F: drivers/net/wireless/wl3501* +WMAA BACKLIGHT DRIVER +M: Daniel Dadap <ddadap@xxxxxxxxxx> +L: platform-driver-x86@xxxxxxxxxxxxxxx +S: Supported +F: drivers/platform/x86/wmaa-backlight-wmi.c + WOLFSON MICROELECTRONICS DRIVERS L: patches@xxxxxxxxxxxxxxxxxxxxx T: git https://github.com/CirrusLogic/linux-drivers.git diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig index 0ad7ad8cf8e1..db342e480aa9 100644 --- a/drivers/platform/x86/Kconfig +++ b/drivers/platform/x86/Kconfig @@ -1368,6 +1368,17 @@ config INTEL_TELEMETRY directly via debugfs files. Various tools may use this interface for SoC state monitoring. +config WMAA_BACKLIGHT_WMI + tristate "ACPI WMAA Backlight Driver" + depends on ACPI_WMI + depends on ACPI + depends on BACKLIGHT_CLASS_DEVICE + help + This driver provides a sysfs backlight interface for notebook + systems which expose the WMAA ACPI method and an associated WMI + wrapper to drive LCD backlight levels through the system's + Embedded Controller. + endif # X86_PLATFORM_DEVICES config PMC_ATOM diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile index 53408d965874..fb6e16d62031 100644 --- a/drivers/platform/x86/Makefile +++ b/drivers/platform/x86/Makefile @@ -146,3 +146,5 @@ obj-$(CONFIG_INTEL_TELEMETRY) += intel_telemetry_core.o \ intel_telemetry_pltdrv.o \ intel_telemetry_debugfs.o obj-$(CONFIG_PMC_ATOM) += pmc_atom.o + +obj-$(CONFIG_WMAA_BACKLIGHT_WMI) += wmaa-backlight-wmi.o diff --git a/drivers/platform/x86/wmaa-backlight-wmi.c b/drivers/platform/x86/wmaa-backlight-wmi.c new file mode 100644 index 000000000000..890e9371f91a --- /dev/null +++ b/drivers/platform/x86/wmaa-backlight-wmi.c @@ -0,0 +1,153 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * WMAA Backlight WMI driver + * + * Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + */ + +#include <linux/module.h> +#include <linux/acpi.h> +#include <linux/backlight.h> + +MODULE_AUTHOR("Aaron Plattner <aplattner@xxxxxxxxxx>"); +MODULE_AUTHOR("Daniel Dadap <ddadap@xxxxxxxxxx>"); +MODULE_DESCRIPTION("WMAA Backlight WMI driver"); +MODULE_LICENSE("GPL v2"); + +#define WMAA_WMI_GUID "603E9613-EF25-4338-A3D0-C46177516DB7" + +MODULE_ALIAS("wmi:"WMAA_WMI_GUID); + +static struct backlight_device *backlight; + +enum wmaa_method { + WMAA_BRIGHTNESS_LEVEL = 1, + WMAA_BRIGHTNESS_SOURCE = 2, +}; + +enum wmaa_get_or_set { + WMAA_GET = 0, + WMAA_SET = 1, + WMAA_GET_MAX = 2, // for WMAA_BRIGHTNESS_LEVEL only +}; + +enum wmaa_source { + WMAA_SOURCE_CLEAR = 0, + WMAA_SOURCE_GPU = 1, + WMAA_SOURCE_EC = 2, + WMAA_SOURCE_AUX = 3, + WMAA_SOURCE_COUNT +}; + +struct wmaa_args { + u32 set; + u32 val; + u32 ret; + u32 ignored[3]; +}; + +static int wmi_call_wmaa(enum wmaa_method method, enum wmaa_get_or_set set, + u32 *val) +{ + struct wmaa_args args = { + .set = set, + .val = 0, + .ret = 0, + }; + struct acpi_buffer buf = { (acpi_size)sizeof(args), &args }; + acpi_status status; + + if (set == WMAA_SET) + args.val = *val; + + status = wmi_evaluate_method(WMAA_WMI_GUID, 0, method, &buf, &buf); + if (ACPI_FAILURE(status)) + return status; + if (set != WMAA_SET) + *val = args.ret; + return status; +} + +static int wmaa_get_brightness(u32 *level) +{ + return wmi_call_wmaa(WMAA_BRIGHTNESS_LEVEL, WMAA_GET, level); +} + +static int wmaa_set_brightness(u32 level) +{ + return wmi_call_wmaa(WMAA_BRIGHTNESS_LEVEL, WMAA_SET, &level); +} + +static int wmaa_backlight_update_status(struct backlight_device *bd) +{ + return wmaa_set_brightness(bd->props.brightness); +} + +static int wmaa_backlight_get_brightness(struct backlight_device *bd) +{ + u32 level; + int ret = wmaa_get_brightness(&level); + + WARN_ON(ret != 0); + return level; +} + +static const struct backlight_ops wmaa_backlight_ops = { + .update_status = wmaa_backlight_update_status, + .get_brightness = wmaa_backlight_get_brightness, +}; + +static int wmaa_get_max_brightness(u32 *level) +{ + return wmi_call_wmaa(WMAA_BRIGHTNESS_LEVEL, WMAA_GET_MAX, level); +} + +static int wmaa_get_brightness_source(u32 *source) +{ + return wmi_call_wmaa(WMAA_BRIGHTNESS_SOURCE, WMAA_GET, source); +} + +static int __init wmaa_backlight_wmi_init(void) +{ + struct backlight_properties props; + u32 source; + + if (!wmi_has_guid(WMAA_WMI_GUID)) + return -ENODEV; + + if (wmaa_get_brightness_source(&source)) + return -EINVAL; + if (source != WMAA_SOURCE_EC) + return -ENODEV; + + // Register a backlight handler + props.type = BACKLIGHT_PLATFORM; + if (wmaa_get_max_brightness(&props.max_brightness) || + wmaa_get_brightness(&props.brightness)) + return -EINVAL; + + backlight = backlight_device_register("wmaa_backlight", NULL, NULL, + &wmaa_backlight_ops, &props); + if (IS_ERR(backlight)) + return PTR_ERR(backlight); + + return 0; +} + +static void __exit wmaa_backlight_wmi_exit(void) +{ + backlight_device_unregister(backlight); +} + +module_init(wmaa_backlight_wmi_init); +module_exit(wmaa_backlight_wmi_exit); -- 2.18.4
