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");
140