platform/x86: Add driver for ACPI WMAA EC-based backlight control (ad62cd93) · Commits · jan.koester / Linux

MAINTAINERS

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		@@ -20246,6 +20246,12 @@ L: linux-wireless@vger.kernel.org
		S: Odd fixes
		F: drivers/net/wireless/wl3501*

		WMAA BACKLIGHT DRIVER
		M: Daniel Dadap <ddadap@nvidia.com>
		L: platform-driver-x86@vger.kernel.org
		S: Supported
		F: drivers/platform/x86/wmaa-backlight-wmi.c

		WOLFSON MICROELECTRONICS DRIVERS
		L: patches@opensource.cirrus.com
		S: Supported

drivers/platform/x86/Kconfig

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		@@ -91,6 +91,22 @@ config PEAQ_WMI
		help
		Say Y here if you want to support WMI-based hotkeys on PEAQ 2-in-1s.

		config WMAA_BACKLIGHT_WMI
		tristate "ACPI WMAA Backlight Driver"
		depends on ACPI_WMI
		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 Embedded Controller
		(EC).

		Say Y or M here if you want to control the backlight on a notebook
		system with an EC-driven backlight using the ACPI WMAA method.

		If you choose to compile this driver as a module the module will be
		called wmaa-backlight-wmi.

		config XIAOMI_WMI
		tristate "Xiaomi WMI key driver"
		depends on ACPI_WMI

drivers/platform/x86/Makefile

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		@@ -12,6 +12,7 @@ obj-$(CONFIG_WMI_BMOF) += wmi-bmof.o
		obj-$(CONFIG_HUAWEI_WMI) += huawei-wmi.o
		obj-$(CONFIG_MXM_WMI) += mxm-wmi.o
		obj-$(CONFIG_PEAQ_WMI) += peaq-wmi.o
		obj-$(CONFIG_WMAA_BACKLIGHT_WMI) += wmaa-backlight-wmi.o
		obj-$(CONFIG_XIAOMI_WMI) += xiaomi-wmi.o
		obj-$(CONFIG_GIGABYTE_WMI) += gigabyte-wmi.o

drivers/platform/x86/wmaa-backlight-wmi.c

0 → 100644

+205 −0

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		// SPDX-License-Identifier: GPL-2.0-only
		/*
		* Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
		*/

		#include <linux/acpi.h>
		#include <linux/backlight.h>
		#include <linux/mod_devicetable.h>
		#include <linux/module.h>
		#include <linux/types.h>
		#include <linux/wmi.h>

		/**
		* enum wmaa_method - WMI method IDs for ACPI WMAA
		* @WMAA_METHOD_LEVEL: Get or set the brightness level,
		* or get the maximum brightness level.
		* @WMAA_METHOD_SOURCE: Get the source for backlight control.
		*/
		enum wmaa_method {
		WMAA_METHOD_LEVEL = 1,
		WMAA_METHOD_SOURCE = 2,
		WMAA_METHOD_MAX
		};

		/**
		* enum wmaa_mode - Operation mode for ACPI WMAA method
		* @WMAA_MODE_GET: Get the current brightness level or source.
		* @WMAA_MODE_SET: Set the brightness level.
		* @WMAA_MODE_GET_MAX_LEVEL: Get the maximum brightness level. This is only
		* valid when the WMI method is %WMAA_METHOD_LEVEL.
		*/
		enum wmaa_mode {
		WMAA_MODE_GET = 0,
		WMAA_MODE_SET = 1,
		WMAA_MODE_GET_MAX_LEVEL = 2,
		WMAA_MODE_MAX
		};

		/**
		* enum wmaa_source - Backlight brightness control source identification
		* @WMAA_SOURCE_GPU: Backlight brightness is controlled by the GPU.
		* @WMAA_SOURCE_EC: Backlight brightness is controlled by the system's
		* Embedded Controller (EC).
		* @WMAA_SOURCE_AUX: Backlight brightness is controlled over the DisplayPort
		* AUX channel.
		*/
		enum wmaa_source {
		WMAA_SOURCE_GPU = 1,
		WMAA_SOURCE_EC = 2,
		WMAA_SOURCE_AUX = 3,
		WMAA_SOURCE_MAX
		};

		/**
		* struct wmaa_args - arguments for the ACPI WMAA method
		* @mode: Pass in an &enum wmaa_mode value to select between getting or
		* setting a value.
		* @val: In parameter for value to set when operating in %WMAA_MODE_SET
		* mode. Not used in %WMAA_MODE_GET or %WMAA_MODE_GET_MAX_LEVEL mode.
		* @ret: Out parameter returning retrieved value when operating in
		* %WMAA_MODE_GET or %WMAA_MODE_GET_MAX_LEVEL mode. Not used in
		* %WMAA_MODE_SET mode.
		* @ignored: Padding; not used. The ACPI method expects a 24 byte params struct.
		*
		* This is the parameters structure for the ACPI WMAA method as wrapped by WMI.
		* The value passed in to @val or returned by @ret will be a brightness value
		* when the WMI method ID is %WMAA_METHOD_LEVEL, or an &enum wmaa_source value
		* when the WMI method ID is %WMAA_METHOD_SOURCE.
		*/
		struct wmaa_args {
		u32 mode;
		u32 val;
		u32 ret;
		u32 ignored[3];
		};

		/**
		* wmi_call_wmaa() - helper function for calling ACPI WMAA via its WMI wrapper
		* @w: Pointer to the struct wmi_device identified by %WMAA_WMI_GUID
		* @id: The method ID for the ACPI WMAA method (e.g. %WMAA_METHOD_LEVEL or
		* %WMAA_METHOD_SOURCE)
		* @mode: The operation to perform on the ACPI WMAA method (e.g. %WMAA_MODE_SET
		* or %WMAA_MODE_GET)
		* @val: Pointer to a value passed in by the caller when @mode is
		* %WMAA_MODE_SET, or a value passed out to the caller when @mode is
		* %WMAA_MODE_GET or %WMAA_MODE_GET_MAX_LEVEL.
		*
		* Returns 0 on success, or a negative error number on failure.
		*/
		static int wmi_call_wmaa(struct wmi_device w, enum wmaa_method id, enum wmaa_mode mode, u32 val)
		{
		struct wmaa_args args = {
		.mode = mode,
		.val = 0,
		.ret = 0,
		};
		struct acpi_buffer buf = { (acpi_size)sizeof(args), &args };
		acpi_status status;

		if (id < WMAA_METHOD_LEVEL \|\| id >= WMAA_METHOD_MAX \|\|
		mode < WMAA_MODE_GET \|\| mode >= WMAA_MODE_MAX)
		return -EINVAL;

		if (mode == WMAA_MODE_SET)
		args.val = *val;

		status = wmidev_evaluate_method(w, 0, id, &buf, &buf);
		if (ACPI_FAILURE(status)) {
		dev_err(&w->dev, "ACPI WMAA failed: %s\n",
		acpi_format_exception(status));
		return -EIO;
		}

		if (mode != WMAA_MODE_SET)
		*val = args.ret;

		return 0;
		}

		static int wmaa_backlight_update_status(struct backlight_device *bd)
		{
		struct wmi_device *wdev = bl_get_data(bd);

		return wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_SET,
		&bd->props.brightness);
		}

		static int wmaa_backlight_get_brightness(struct backlight_device *bd)
		{
		struct wmi_device *wdev = bl_get_data(bd);
		u32 level;
		int ret;

		ret = wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_GET, &level);
		if (ret < 0)
		return ret;

		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_backlight_wmi_probe(struct wmi_device wdev, const void ctx)
		{
		struct backlight_properties props = {};
		struct backlight_device *bdev;
		u32 source;
		int ret;

		ret = wmi_call_wmaa(wdev, WMAA_METHOD_SOURCE, WMAA_MODE_GET, &source);
		if (ret)
		return ret;

		/*
		* This driver is only to be used when brightness control is handled
		* by the EC; otherwise, the GPU driver(s) should control brightness.
		*/
		if (source != WMAA_SOURCE_EC)
		return -ENODEV;

		/*
		* Identify this backlight device as a firmware device so that it can
		* be prioritized over any exposed GPU-driven raw device(s).
		*/
		props.type = BACKLIGHT_FIRMWARE;

		ret = wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_GET_MAX_LEVEL,
		&props.max_brightness);
		if (ret)
		return ret;

		ret = wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_GET,
		&props.brightness);
		if (ret)
		return ret;

		bdev = devm_backlight_device_register(&wdev->dev, "wmaa_backlight",
		&wdev->dev, wdev,
		&wmaa_backlight_ops, &props);
		return PTR_ERR_OR_ZERO(bdev);
		}

		#define WMAA_WMI_GUID "603E9613-EF25-4338-A3D0-C46177516DB7"

		static const struct wmi_device_id wmaa_backlight_wmi_id_table[] = {
		{ .guid_string = WMAA_WMI_GUID },
		{ }
		};
		MODULE_DEVICE_TABLE(wmi, wmaa_backlight_wmi_id_table);

		static struct wmi_driver wmaa_backlight_wmi_driver = {
		.driver = {
		.name = "wmaa-backlight",
		},
		.probe = wmaa_backlight_wmi_probe,
		.id_table = wmaa_backlight_wmi_id_table,
		};
		module_wmi_driver(wmaa_backlight_wmi_driver);

		MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
		MODULE_DESCRIPTION("WMAA Backlight WMI driver");
		MODULE_LICENSE("GPL");