drivers/platform/x86/nvidia-wmi-ec-backlight.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2020, NVIDIA CORPORATION.  All rights reserved.
   4  */
   5
   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>
  12
  13 /**
  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
  17  */
  18 enum wmi_brightness_method {
  19         WMI_BRIGHTNESS_METHOD_LEVEL = 1,
  20         WMI_BRIGHTNESS_METHOD_SOURCE = 2,
  21         WMI_BRIGHTNESS_METHOD_MAX
  22 };
  23
  24 /**
  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.
  31  */
  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
  37 };
  38
  39 /**
  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.
  46  */
  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
  52 };
  53
  54 /**
  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.
  65  *
  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.
  70  */
  71 struct wmi_brightness_args {
  72         u32 mode;
  73         u32 val;
  74         u32 ret;
  75         u32 ignored[3];
  76 };
  77
  78 /**
  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.
  88  *
  89  * Returns 0 on success, or a negative error number on failure.
  90  */
  91 static int wmi_brightness_notify(struct wmi_device *w, enum wmi_brightness_method id, enum wmi_brightness_mode mode, u32 *val)
  92 {
  93         struct wmi_brightness_args args = {
  94                 .mode = mode,
  95                 .val = 0,
  96                 .ret = 0,
  97         };
  98         struct acpi_buffer buf = { (acpi_size)sizeof(args), &args };
  99         acpi_status status;
 100
 101         if (id < WMI_BRIGHTNESS_METHOD_LEVEL ||
 102             id >= WMI_BRIGHTNESS_METHOD_MAX ||
 103             mode < WMI_BRIGHTNESS_MODE_GET || mode >= WMI_BRIGHTNESS_MODE_MAX)
 104                 return -EINVAL;
 105
 106         if (mode == WMI_BRIGHTNESS_MODE_SET)
 107                 args.val = *val;
 108
 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));
 113                 return -EIO;
 114         }
 115
 116         if (mode != WMI_BRIGHTNESS_MODE_SET)
 117                 *val = args.ret;
 118
 119         return 0;
 120 }
 121
 122 static int nvidia_wmi_ec_backlight_update_status(struct backlight_device *bd)
 123 {
 124         struct wmi_device *wdev = bl_get_data(bd);
 125
 126         return wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
 127                                      WMI_BRIGHTNESS_MODE_SET,
 128                                      &bd->props.brightness);
 129 }
 130
 131 static int nvidia_wmi_ec_backlight_get_brightness(struct backlight_device *bd)
 132 {
 133         struct wmi_device *wdev = bl_get_data(bd);
 134         u32 level;
 135         int ret;
 136
 137         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
 138                                     WMI_BRIGHTNESS_MODE_GET, &level);
 139         if (ret < 0)
 140                 return ret;
 141
 142         return level;
 143 }
 144
 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,
 148 };
 149
 150 static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ctx)
 151 {
 152         struct backlight_properties props = {};
 153         struct backlight_device *bdev;
 154         u32 source;
 155         int ret;
 156
 157         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_SOURCE,
 158                                    WMI_BRIGHTNESS_MODE_GET, &source);
 159         if (ret)
 160                 return ret;
 161
 162         /*
 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.
 165          */
 166         if (source != WMI_BRIGHTNESS_SOURCE_EC)
 167                 return -ENODEV;
 168
 169         /*
 170          * Identify this backlight device as a firmware device so that it can
 171          * be prioritized over any exposed GPU-driven raw device(s).
 172          */
 173         props.type = BACKLIGHT_FIRMWARE;
 174
 175         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
 176                                    WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL,
 177                                    &props.max_brightness);
 178         if (ret)
 179                 return ret;
 180
 181         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
 182                                    WMI_BRIGHTNESS_MODE_GET, &props.brightness);
 183         if (ret)
 184                 return ret;
 185
 186         bdev = devm_backlight_device_register(&wdev->dev,
 187                                               "nvidia_wmi_ec_backlight",
 188                                               &wdev->dev, wdev,
 189                                               &nvidia_wmi_ec_backlight_ops,
 190                                               &props);
 191         return PTR_ERR_OR_ZERO(bdev);
 192 }
 193
 194 #define WMI_BRIGHTNESS_GUID "603E9613-EF25-4338-A3D0-C46177516DB7"
 195
 196 static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = {
 197         { .guid_string = WMI_BRIGHTNESS_GUID },
 198         { }
 199 };
 200 MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table);
 201
 202 static struct wmi_driver nvidia_wmi_ec_backlight_driver = {
 203         .driver = {
 204                 .name = "nvidia-wmi-ec-backlight",
 205         },
 206         .probe = nvidia_wmi_ec_backlight_probe,
 207         .id_table = nvidia_wmi_ec_backlight_id_table,
 208 };
 209 module_wmi_driver(nvidia_wmi_ec_backlight_driver);
 210
 211 MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
 212 MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver");
 213 MODULE_LICENSE("GPL");