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/platform_data/x86/nvidia-wmi-ec-backlight.h>
  11 #include <linux/types.h>
  12 #include <linux/wmi.h>
  13 #include <acpi/video.h>
  14
  15 /**
  16  * wmi_brightness_notify() - helper function for calling WMI-wrapped ACPI method
  17  * @w:    Pointer to the struct wmi_device identified by %WMI_BRIGHTNESS_GUID
  18  * @id:   The WMI method ID to call (e.g. %WMI_BRIGHTNESS_METHOD_LEVEL or
  19  *        %WMI_BRIGHTNESS_METHOD_SOURCE)
  20  * @mode: The operation to perform on the method (e.g. %WMI_BRIGHTNESS_MODE_SET
  21  *        or %WMI_BRIGHTNESS_MODE_GET)
  22  * @val:  Pointer to a value passed in by the caller when @mode is
  23  *        %WMI_BRIGHTNESS_MODE_SET, or a value passed out to caller when @mode
  24  *        is %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL.
  25  *
  26  * Returns 0 on success, or a negative error number on failure.
  27  */
  28 static int wmi_brightness_notify(struct wmi_device *w, enum wmi_brightness_method id, enum wmi_brightness_mode mode, u32 *val)
  29 {
  30         struct wmi_brightness_args args = {
  31                 .mode = mode,
  32                 .val = 0,
  33                 .ret = 0,
  34         };
  35         struct acpi_buffer buf = { (acpi_size)sizeof(args), &args };
  36         acpi_status status;
  37
  38         if (id < WMI_BRIGHTNESS_METHOD_LEVEL ||
  39             id >= WMI_BRIGHTNESS_METHOD_MAX ||
  40             mode < WMI_BRIGHTNESS_MODE_GET || mode >= WMI_BRIGHTNESS_MODE_MAX)
  41                 return -EINVAL;
  42
  43         if (mode == WMI_BRIGHTNESS_MODE_SET)
  44                 args.val = *val;
  45
  46         status = wmidev_evaluate_method(w, 0, id, &buf, &buf);
  47         if (ACPI_FAILURE(status)) {
  48                 dev_err(&w->dev, "EC backlight control failed: %s\n",
  49                         acpi_format_exception(status));
  50                 return -EIO;
  51         }
  52
  53         if (mode != WMI_BRIGHTNESS_MODE_SET)
  54                 *val = args.ret;
  55
  56         return 0;
  57 }
  58
  59 static int nvidia_wmi_ec_backlight_update_status(struct backlight_device *bd)
  60 {
  61         struct wmi_device *wdev = bl_get_data(bd);
  62
  63         return wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
  64                                      WMI_BRIGHTNESS_MODE_SET,
  65                                      &bd->props.brightness);
  66 }
  67
  68 static int nvidia_wmi_ec_backlight_get_brightness(struct backlight_device *bd)
  69 {
  70         struct wmi_device *wdev = bl_get_data(bd);
  71         u32 level;
  72         int ret;
  73
  74         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
  75                                     WMI_BRIGHTNESS_MODE_GET, &level);
  76         if (ret < 0)
  77                 return ret;
  78
  79         return level;
  80 }
  81
  82 static const struct backlight_ops nvidia_wmi_ec_backlight_ops = {
  83         .update_status = nvidia_wmi_ec_backlight_update_status,
  84         .get_brightness = nvidia_wmi_ec_backlight_get_brightness,
  85 };
  86
  87 static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ctx)
  88 {
  89         struct backlight_properties props = {};
  90         struct backlight_device *bdev;
  91         int ret;
  92
  93         /* drivers/acpi/video_detect.c also checks that SOURCE == EC */
  94         if (acpi_video_get_backlight_type() != acpi_backlight_nvidia_wmi_ec)
  95                 return -ENODEV;
  96
  97         /*
  98          * Identify this backlight device as a firmware device so that it can
  99          * be prioritized over any exposed GPU-driven raw device(s).
 100          */
 101         props.type = BACKLIGHT_FIRMWARE;
 102
 103         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
 104                                    WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL,
 105                                    &props.max_brightness);
 106         if (ret)
 107                 return ret;
 108
 109         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
 110                                    WMI_BRIGHTNESS_MODE_GET, &props.brightness);
 111         if (ret)
 112                 return ret;
 113
 114         bdev = devm_backlight_device_register(&wdev->dev,
 115                                               "nvidia_wmi_ec_backlight",
 116                                               &wdev->dev, wdev,
 117                                               &nvidia_wmi_ec_backlight_ops,
 118                                               &props);
 119         return PTR_ERR_OR_ZERO(bdev);
 120 }
 121
 122 static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = {
 123         { .guid_string = WMI_BRIGHTNESS_GUID },
 124         { }
 125 };
 126 MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table);
 127
 128 static struct wmi_driver nvidia_wmi_ec_backlight_driver = {
 129         .driver = {
 130                 .name = "nvidia-wmi-ec-backlight",
 131         },
 132         .probe = nvidia_wmi_ec_backlight_probe,
 133         .id_table = nvidia_wmi_ec_backlight_id_table,
 134 };
 135 module_wmi_driver(nvidia_wmi_ec_backlight_driver);
 136
 137 MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
 138 MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver");
 139 MODULE_LICENSE("GPL");