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 */
wmi_brightness_notify(struct wmi_device * w,enum wmi_brightness_method id,enum wmi_brightness_mode mode,u32 * val)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
nvidia_wmi_ec_backlight_update_status(struct backlight_device * bd)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
nvidia_wmi_ec_backlight_get_brightness(struct backlight_device * bd)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
nvidia_wmi_ec_backlight_probe(struct wmi_device * wdev,const void * ctx)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
