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
 15static bool force;
 16module_param(force, bool, 0444);
 17MODULE_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 */
 32static 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
 63static 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
 72static 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
 86static 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
 91static 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
126static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = {
127	{ .guid_string = WMI_BRIGHTNESS_GUID },
128	{ }
129};
130MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table);
131
132static 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};
139module_wmi_driver(nvidia_wmi_ec_backlight_driver);
140
141MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
142MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver");
143MODULE_LICENSE("GPL");