1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
6 #include <linux/acpi.h>
7 #include <linux/backlight.h>
8 #include <linux/mod_devicetable.h>
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/wmi.h>
14 * enum wmi_brightness_method - WMI method IDs
15 * @WMI_BRIGHTNESS_METHOD_LEVEL: Get/Set EC brightness level status
16 * @WMI_BRIGHTNESS_METHOD_SOURCE: Get/Set EC Brightness Source
18 enum wmi_brightness_method {
19 WMI_BRIGHTNESS_METHOD_LEVEL = 1,
20 WMI_BRIGHTNESS_METHOD_SOURCE = 2,
21 WMI_BRIGHTNESS_METHOD_MAX
25 * enum wmi_brightness_mode - Operation mode for WMI-wrapped method
26 * @WMI_BRIGHTNESS_MODE_GET: Get the current brightness level/source.
27 * @WMI_BRIGHTNESS_MODE_SET: Set the brightness level.
28 * @WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL: Get the maximum brightness level. This
29 * is only valid when the WMI method is
30 * %WMI_BRIGHTNESS_METHOD_LEVEL.
32 enum wmi_brightness_mode {
33 WMI_BRIGHTNESS_MODE_GET = 0,
34 WMI_BRIGHTNESS_MODE_SET = 1,
35 WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL = 2,
36 WMI_BRIGHTNESS_MODE_MAX
40 * enum wmi_brightness_source - Backlight brightness control source selection
41 * @WMI_BRIGHTNESS_SOURCE_GPU: Backlight brightness is controlled by the GPU.
42 * @WMI_BRIGHTNESS_SOURCE_EC: Backlight brightness is controlled by the
43 * system's Embedded Controller (EC).
44 * @WMI_BRIGHTNESS_SOURCE_AUX: Backlight brightness is controlled over the
45 * DisplayPort AUX channel.
47 enum wmi_brightness_source {
48 WMI_BRIGHTNESS_SOURCE_GPU = 1,
49 WMI_BRIGHTNESS_SOURCE_EC = 2,
50 WMI_BRIGHTNESS_SOURCE_AUX = 3,
51 WMI_BRIGHTNESS_SOURCE_MAX
55 * struct wmi_brightness_args - arguments for the WMI-wrapped ACPI method
56 * @mode: Pass in an &enum wmi_brightness_mode value to select between
57 * getting or setting a value.
58 * @val: In parameter for value to set when using %WMI_BRIGHTNESS_MODE_SET
59 * mode. Not used in conjunction with %WMI_BRIGHTNESS_MODE_GET or
60 * %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL mode.
61 * @ret: Out parameter returning retrieved value when operating in
62 * %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL
63 * mode. Not used in %WMI_BRIGHTNESS_MODE_SET mode.
64 * @ignored: Padding; not used. The ACPI method expects a 24 byte params struct.
66 * This is the parameters structure for the WmiBrightnessNotify ACPI method as
67 * wrapped by WMI. The value passed in to @val or returned by @ret will be a
68 * brightness value when the WMI method ID is %WMI_BRIGHTNESS_METHOD_LEVEL, or
69 * an &enum wmi_brightness_source value with %WMI_BRIGHTNESS_METHOD_SOURCE.
71 struct wmi_brightness_args {
79 * wmi_brightness_notify() - helper function for calling WMI-wrapped ACPI method
80 * @w: Pointer to the struct wmi_device identified by %WMI_BRIGHTNESS_GUID
81 * @id: The WMI method ID to call (e.g. %WMI_BRIGHTNESS_METHOD_LEVEL or
82 * %WMI_BRIGHTNESS_METHOD_SOURCE)
83 * @mode: The operation to perform on the method (e.g. %WMI_BRIGHTNESS_MODE_SET
84 * or %WMI_BRIGHTNESS_MODE_GET)
85 * @val: Pointer to a value passed in by the caller when @mode is
86 * %WMI_BRIGHTNESS_MODE_SET, or a value passed out to caller when @mode
87 * is %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL.
89 * Returns 0 on success, or a negative error number on failure.
91 static int wmi_brightness_notify(struct wmi_device *w, enum wmi_brightness_method id, enum wmi_brightness_mode mode, u32 *val)
93 struct wmi_brightness_args args = {
98 struct acpi_buffer buf = { (acpi_size)sizeof(args), &args };
101 if (id < WMI_BRIGHTNESS_METHOD_LEVEL ||
102 id >= WMI_BRIGHTNESS_METHOD_MAX ||
103 mode < WMI_BRIGHTNESS_MODE_GET || mode >= WMI_BRIGHTNESS_MODE_MAX)
106 if (mode == WMI_BRIGHTNESS_MODE_SET)
109 status = wmidev_evaluate_method(w, 0, id, &buf, &buf);
110 if (ACPI_FAILURE(status)) {
111 dev_err(&w->dev, "EC backlight control failed: %s\n",
112 acpi_format_exception(status));
116 if (mode != WMI_BRIGHTNESS_MODE_SET)
122 static int nvidia_wmi_ec_backlight_update_status(struct backlight_device *bd)
124 struct wmi_device *wdev = bl_get_data(bd);
126 return wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
127 WMI_BRIGHTNESS_MODE_SET,
128 &bd->props.brightness);
131 static int nvidia_wmi_ec_backlight_get_brightness(struct backlight_device *bd)
133 struct wmi_device *wdev = bl_get_data(bd);
137 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
138 WMI_BRIGHTNESS_MODE_GET, &level);
145 static const struct backlight_ops nvidia_wmi_ec_backlight_ops = {
146 .update_status = nvidia_wmi_ec_backlight_update_status,
147 .get_brightness = nvidia_wmi_ec_backlight_get_brightness,
150 static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ctx)
152 struct backlight_properties props = {};
153 struct backlight_device *bdev;
157 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_SOURCE,
158 WMI_BRIGHTNESS_MODE_GET, &source);
163 * This driver is only to be used when brightness control is handled
164 * by the EC; otherwise, the GPU driver(s) should control brightness.
166 if (source != WMI_BRIGHTNESS_SOURCE_EC)
170 * Identify this backlight device as a firmware device so that it can
171 * be prioritized over any exposed GPU-driven raw device(s).
173 props.type = BACKLIGHT_FIRMWARE;
175 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
176 WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL,
177 &props.max_brightness);
181 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
182 WMI_BRIGHTNESS_MODE_GET, &props.brightness);
186 bdev = devm_backlight_device_register(&wdev->dev,
187 "nvidia_wmi_ec_backlight",
189 &nvidia_wmi_ec_backlight_ops,
191 return PTR_ERR_OR_ZERO(bdev);
194 #define WMI_BRIGHTNESS_GUID "603E9613-EF25-4338-A3D0-C46177516DB7"
196 static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = {
197 { .guid_string = WMI_BRIGHTNESS_GUID },
200 MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table);
202 static struct wmi_driver nvidia_wmi_ec_backlight_driver = {
204 .name = "nvidia-wmi-ec-backlight",
206 .probe = nvidia_wmi_ec_backlight_probe,
207 .id_table = nvidia_wmi_ec_backlight_id_table,
209 module_wmi_driver(nvidia_wmi_ec_backlight_driver);
211 MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
212 MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver");
213 MODULE_LICENSE("GPL");