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 */
 28static 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
 59static 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
 68static 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
 82static 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
 87static 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
122static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = {
123	{ .guid_string = WMI_BRIGHTNESS_GUID },
124	{ }
125};
126MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table);
127
128static 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};
135module_wmi_driver(nvidia_wmi_ec_backlight_driver);
136
137MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
138MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver");
139MODULE_LICENSE("GPL");