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

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (c) 2020, NVIDIA CORPORATION.  All rights reserved.
0004  */
0005
0006 #include <linux/acpi.h>
0007 #include <linux/backlight.h>
0008 #include <linux/mod_devicetable.h>
0009 #include <linux/module.h>
0010 #include <linux/types.h>
0011 #include <linux/wmi.h>
0012
0013 /**
0014  * enum wmi_brightness_method - WMI method IDs
0015  * @WMI_BRIGHTNESS_METHOD_LEVEL:  Get/Set EC brightness level status
0016  * @WMI_BRIGHTNESS_METHOD_SOURCE: Get/Set EC Brightness Source
0017  */
0018 enum wmi_brightness_method {
0019     WMI_BRIGHTNESS_METHOD_LEVEL = 1,
0020     WMI_BRIGHTNESS_METHOD_SOURCE = 2,
0021     WMI_BRIGHTNESS_METHOD_MAX
0022 };
0023
0024 /**
0025  * enum wmi_brightness_mode - Operation mode for WMI-wrapped method
0026  * @WMI_BRIGHTNESS_MODE_GET:            Get the current brightness level/source.
0027  * @WMI_BRIGHTNESS_MODE_SET:            Set the brightness level.
0028  * @WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL:  Get the maximum brightness level. This
0029  *                                      is only valid when the WMI method is
0030  *                                      %WMI_BRIGHTNESS_METHOD_LEVEL.
0031  */
0032 enum wmi_brightness_mode {
0033     WMI_BRIGHTNESS_MODE_GET = 0,
0034     WMI_BRIGHTNESS_MODE_SET = 1,
0035     WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL = 2,
0036     WMI_BRIGHTNESS_MODE_MAX
0037 };
0038
0039 /**
0040  * enum wmi_brightness_source - Backlight brightness control source selection
0041  * @WMI_BRIGHTNESS_SOURCE_GPU: Backlight brightness is controlled by the GPU.
0042  * @WMI_BRIGHTNESS_SOURCE_EC:  Backlight brightness is controlled by the
0043  *                             system's Embedded Controller (EC).
0044  * @WMI_BRIGHTNESS_SOURCE_AUX: Backlight brightness is controlled over the
0045  *                             DisplayPort AUX channel.
0046  */
0047 enum wmi_brightness_source {
0048     WMI_BRIGHTNESS_SOURCE_GPU = 1,
0049     WMI_BRIGHTNESS_SOURCE_EC = 2,
0050     WMI_BRIGHTNESS_SOURCE_AUX = 3,
0051     WMI_BRIGHTNESS_SOURCE_MAX
0052 };
0053
0054 /**
0055  * struct wmi_brightness_args - arguments for the WMI-wrapped ACPI method
0056  * @mode:    Pass in an &enum wmi_brightness_mode value to select between
0057  *           getting or setting a value.
0058  * @val:     In parameter for value to set when using %WMI_BRIGHTNESS_MODE_SET
0059  *           mode. Not used in conjunction with %WMI_BRIGHTNESS_MODE_GET or
0060  *           %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL mode.
0061  * @ret:     Out parameter returning retrieved value when operating in
0062  *           %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL
0063  *           mode. Not used in %WMI_BRIGHTNESS_MODE_SET mode.
0064  * @ignored: Padding; not used. The ACPI method expects a 24 byte params struct.
0065  *
0066  * This is the parameters structure for the WmiBrightnessNotify ACPI method as
0067  * wrapped by WMI. The value passed in to @val or returned by @ret will be a
0068  * brightness value when the WMI method ID is %WMI_BRIGHTNESS_METHOD_LEVEL, or
0069  * an &enum wmi_brightness_source value with %WMI_BRIGHTNESS_METHOD_SOURCE.
0070  */
0071 struct wmi_brightness_args {
0072     u32 mode;
0073     u32 val;
0074     u32 ret;
0075     u32 ignored[3];
0076 };
0077
0078 /**
0079  * wmi_brightness_notify() - helper function for calling WMI-wrapped ACPI method
0080  * @w:    Pointer to the struct wmi_device identified by %WMI_BRIGHTNESS_GUID
0081  * @id:   The WMI method ID to call (e.g. %WMI_BRIGHTNESS_METHOD_LEVEL or
0082  *        %WMI_BRIGHTNESS_METHOD_SOURCE)
0083  * @mode: The operation to perform on the method (e.g. %WMI_BRIGHTNESS_MODE_SET
0084  *        or %WMI_BRIGHTNESS_MODE_GET)
0085  * @val:  Pointer to a value passed in by the caller when @mode is
0086  *        %WMI_BRIGHTNESS_MODE_SET, or a value passed out to caller when @mode
0087  *        is %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL.
0088  *
0089  * Returns 0 on success, or a negative error number on failure.
0090  */
0091 static int wmi_brightness_notify(struct wmi_device *w, enum wmi_brightness_method id, enum wmi_brightness_mode mode, u32 *val)
0092 {
0093     struct wmi_brightness_args args = {
0094         .mode = mode,
0095         .val = 0,
0096         .ret = 0,
0097     };
0098     struct acpi_buffer buf = { (acpi_size)sizeof(args), &args };
0099     acpi_status status;
0100
0101     if (id < WMI_BRIGHTNESS_METHOD_LEVEL ||
0102         id >= WMI_BRIGHTNESS_METHOD_MAX ||
0103         mode < WMI_BRIGHTNESS_MODE_GET || mode >= WMI_BRIGHTNESS_MODE_MAX)
0104         return -EINVAL;
0105
0106     if (mode == WMI_BRIGHTNESS_MODE_SET)
0107         args.val = *val;
0108
0109     status = wmidev_evaluate_method(w, 0, id, &buf, &buf);
0110     if (ACPI_FAILURE(status)) {
0111         dev_err(&w->dev, "EC backlight control failed: %s\n",
0112             acpi_format_exception(status));
0113         return -EIO;
0114     }
0115
0116     if (mode != WMI_BRIGHTNESS_MODE_SET)
0117         *val = args.ret;
0118
0119     return 0;
0120 }
0121
0122 static int nvidia_wmi_ec_backlight_update_status(struct backlight_device *bd)
0123 {
0124     struct wmi_device *wdev = bl_get_data(bd);
0125
0126     return wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
0127                                  WMI_BRIGHTNESS_MODE_SET,
0128                          &bd->props.brightness);
0129 }
0130
0131 static int nvidia_wmi_ec_backlight_get_brightness(struct backlight_device *bd)
0132 {
0133     struct wmi_device *wdev = bl_get_data(bd);
0134     u32 level;
0135     int ret;
0136
0137     ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
0138                                 WMI_BRIGHTNESS_MODE_GET, &level);
0139     if (ret < 0)
0140         return ret;
0141
0142     return level;
0143 }
0144
0145 static const struct backlight_ops nvidia_wmi_ec_backlight_ops = {
0146     .update_status = nvidia_wmi_ec_backlight_update_status,
0147     .get_brightness = nvidia_wmi_ec_backlight_get_brightness,
0148 };
0149
0150 static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ctx)
0151 {
0152     struct backlight_properties props = {};
0153     struct backlight_device *bdev;
0154     u32 source;
0155     int ret;
0156
0157     ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_SOURCE,
0158                                WMI_BRIGHTNESS_MODE_GET, &source);
0159     if (ret)
0160         return ret;
0161
0162     /*
0163      * This driver is only to be used when brightness control is handled
0164      * by the EC; otherwise, the GPU driver(s) should control brightness.
0165      */
0166     if (source != WMI_BRIGHTNESS_SOURCE_EC)
0167         return -ENODEV;
0168
0169     /*
0170      * Identify this backlight device as a firmware device so that it can
0171      * be prioritized over any exposed GPU-driven raw device(s).
0172      */
0173     props.type = BACKLIGHT_FIRMWARE;
0174
0175     ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
0176                                WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL,
0177                                &props.max_brightness);
0178     if (ret)
0179         return ret;
0180
0181     ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
0182                                WMI_BRIGHTNESS_MODE_GET, &props.brightness);
0183     if (ret)
0184         return ret;
0185
0186     bdev = devm_backlight_device_register(&wdev->dev,
0187                                           "nvidia_wmi_ec_backlight",
0188                           &wdev->dev, wdev,
0189                           &nvidia_wmi_ec_backlight_ops,
0190                           &props);
0191     return PTR_ERR_OR_ZERO(bdev);
0192 }
0193
0194 #define WMI_BRIGHTNESS_GUID "603E9613-EF25-4338-A3D0-C46177516DB7"
0195
0196 static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = {
0197     { .guid_string = WMI_BRIGHTNESS_GUID },
0198     { }
0199 };
0200 MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table);
0201
0202 static struct wmi_driver nvidia_wmi_ec_backlight_driver = {
0203     .driver = {
0204         .name = "nvidia-wmi-ec-backlight",
0205     },
0206     .probe = nvidia_wmi_ec_backlight_probe,
0207     .id_table = nvidia_wmi_ec_backlight_id_table,
0208 };
0209 module_wmi_driver(nvidia_wmi_ec_backlight_driver);
0210
0211 MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
0212 MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver");
0213 MODULE_LICENSE("GPL");