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 static bool force;
  16 module_param(force, bool, 0444);
  17 MODULE_PARM_DESC(force, "Force loading (disable acpi_backlight=xxx checks");
  18
  19 /**
  20  * wmi_brightness_notify() - helper function for calling WMI-wrapped ACPI method
  21  * @w:    Pointer to the struct wmi_device identified by %WMI_BRIGHTNESS_GUID
  22  * @id:   The WMI method ID to call (e.g. %WMI_BRIGHTNESS_METHOD_LEVEL or
  23  *        %WMI_BRIGHTNESS_METHOD_SOURCE)
  24  * @mode: The operation to perform on the method (e.g. %WMI_BRIGHTNESS_MODE_SET
  25  *        or %WMI_BRIGHTNESS_MODE_GET)
  26  * @val:  Pointer to a value passed in by the caller when @mode is
  27  *        %WMI_BRIGHTNESS_MODE_SET, or a value passed out to caller when @mode
  28  *        is %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL.
  29  *
  30  * Returns 0 on success, or a negative error number on failure.
  31  */
  32 static int wmi_brightness_notify(struct wmi_device *w, enum wmi_brightness_method id, enum wmi_brightness_mode mode, u32 *val)
  33 {
  34         struct wmi_brightness_args args = {
  35                 .mode = mode,
  36                 .val = 0,
  37                 .ret = 0,
  38         };
  39         struct acpi_buffer buf = { (acpi_size)sizeof(args), &args };
  40         acpi_status status;
  41
  42         if (id < WMI_BRIGHTNESS_METHOD_LEVEL ||
  43             id >= WMI_BRIGHTNESS_METHOD_MAX ||
  44             mode < WMI_BRIGHTNESS_MODE_GET || mode >= WMI_BRIGHTNESS_MODE_MAX)
  45                 return -EINVAL;
  46
  47         if (mode == WMI_BRIGHTNESS_MODE_SET)
  48                 args.val = *val;
  49
  50         status = wmidev_evaluate_method(w, 0, id, &buf, &buf);
  51         if (ACPI_FAILURE(status)) {
  52                 dev_err(&w->dev, "EC backlight control failed: %s\n",
  53                         acpi_format_exception(status));
  54                 return -EIO;
  55         }
  56
  57         if (mode != WMI_BRIGHTNESS_MODE_SET)
  58                 *val = args.ret;
  59
  60         return 0;
  61 }
  62
  63 static int nvidia_wmi_ec_backlight_update_status(struct backlight_device *bd)
  64 {
  65         struct wmi_device *wdev = bl_get_data(bd);
  66
  67         return wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
  68                                      WMI_BRIGHTNESS_MODE_SET,
  69                                      &bd->props.brightness);
  70 }
  71
  72 static int nvidia_wmi_ec_backlight_get_brightness(struct backlight_device *bd)
  73 {
  74         struct wmi_device *wdev = bl_get_data(bd);
  75         u32 level;
  76         int ret;
  77
  78         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
  79                                     WMI_BRIGHTNESS_MODE_GET, &level);
  80         if (ret < 0)
  81                 return ret;
  82
  83         return level;
  84 }
  85
  86 static const struct backlight_ops nvidia_wmi_ec_backlight_ops = {
  87         .update_status = nvidia_wmi_ec_backlight_update_status,
  88         .get_brightness = nvidia_wmi_ec_backlight_get_brightness,
  89 };
  90
  91 static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ctx)
  92 {
  93         struct backlight_properties props = {};
  94         struct backlight_device *bdev;
  95         int ret;
  96
  97         /* drivers/acpi/video_detect.c also checks that SOURCE == EC */
  98         if (!force && acpi_video_get_backlight_type() != acpi_backlight_nvidia_wmi_ec)
  99                 return -ENODEV;
 100
 101         /*
 102          * Identify this backlight device as a firmware device so that it can
 103          * be prioritized over any exposed GPU-driven raw device(s).
 104          */
 105         props.type = BACKLIGHT_FIRMWARE;
 106
 107         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
 108                                    WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL,
 109                                    &props.max_brightness);
 110         if (ret)
 111                 return ret;
 112
 113         ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
 114                                    WMI_BRIGHTNESS_MODE_GET, &props.brightness);
 115         if (ret)
 116                 return ret;
 117
 118         bdev = devm_backlight_device_register(&wdev->dev,
 119                                               "nvidia_wmi_ec_backlight",
 120                                               &wdev->dev, wdev,
 121                                               &nvidia_wmi_ec_backlight_ops,
 122                                               &props);
 123         return PTR_ERR_OR_ZERO(bdev);
 124 }
 125
 126 static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = {
 127         { .guid_string = WMI_BRIGHTNESS_GUID },
 128         { }
 129 };
 130 MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table);
 131
 132 static struct wmi_driver nvidia_wmi_ec_backlight_driver = {
 133         .driver = {
 134                 .name = "nvidia-wmi-ec-backlight",
 135         },
 136         .probe = nvidia_wmi_ec_backlight_probe,
 137         .id_table = nvidia_wmi_ec_backlight_id_table,
 138 };
 139 module_wmi_driver(nvidia_wmi_ec_backlight_driver);
 140
 141 MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
 142 MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver");
 143 MODULE_LICENSE("GPL");