summaryrefslogtreecommitdiffstats
path: root/drivers/platform/chrome/chromeos_privacy_screen.c
blob: bb74ddf9af4ac5f813a0bcd0c97839c060071f18 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
// SPDX-License-Identifier: GPL-2.0

/*
 *  ChromeOS Privacy Screen support
 *
 * Copyright (C) 2022 Google LLC
 *
 * This is the Chromeos privacy screen provider, present on certain chromebooks,
 * represented by a GOOG0010 device in the ACPI. This ACPI device, if present,
 * will cause the i915 drm driver to probe defer until this driver registers
 * the privacy-screen.
 */

#include <linux/acpi.h>
#include <drm/drm_privacy_screen_driver.h>

/*
 * The DSM (Device Specific Method) constants below are the agreed API with
 * the firmware team, on how to control privacy screen using ACPI methods.
 */
#define PRIV_SCRN_DSM_REVID		1	/* DSM version */
#define PRIV_SCRN_DSM_FN_GET_STATUS	1	/* Get privacy screen status */
#define PRIV_SCRN_DSM_FN_ENABLE		2	/* Enable privacy screen */
#define PRIV_SCRN_DSM_FN_DISABLE	3	/* Disable privacy screen */

static const guid_t chromeos_privacy_screen_dsm_guid =
		    GUID_INIT(0xc7033113, 0x8720, 0x4ceb,
			      0x90, 0x90, 0x9d, 0x52, 0xb3, 0xe5, 0x2d, 0x73);

static void
chromeos_privacy_screen_get_hw_state(struct drm_privacy_screen
				     *drm_privacy_screen)
{
	union acpi_object *obj;
	acpi_handle handle;
	struct device *privacy_screen =
		drm_privacy_screen_get_drvdata(drm_privacy_screen);

	handle = acpi_device_handle(to_acpi_device(privacy_screen));
	obj = acpi_evaluate_dsm(handle, &chromeos_privacy_screen_dsm_guid,
				PRIV_SCRN_DSM_REVID,
				PRIV_SCRN_DSM_FN_GET_STATUS, NULL);
	if (!obj) {
		dev_err(privacy_screen,
			"_DSM failed to get privacy-screen state\n");
		return;
	}

	if (obj->type != ACPI_TYPE_INTEGER)
		dev_err(privacy_screen,
			"Bad _DSM to get privacy-screen state\n");
	else if (obj->integer.value == 1)
		drm_privacy_screen->hw_state = drm_privacy_screen->sw_state =
			PRIVACY_SCREEN_ENABLED;
	else
		drm_privacy_screen->hw_state = drm_privacy_screen->sw_state =
			PRIVACY_SCREEN_DISABLED;

	ACPI_FREE(obj);
}

static int
chromeos_privacy_screen_set_sw_state(struct drm_privacy_screen
				     *drm_privacy_screen,
				     enum drm_privacy_screen_status state)
{
	union acpi_object *obj = NULL;
	acpi_handle handle;
	struct device *privacy_screen =
		drm_privacy_screen_get_drvdata(drm_privacy_screen);

	handle = acpi_device_handle(to_acpi_device(privacy_screen));

	if (state == PRIVACY_SCREEN_DISABLED) {
		obj = acpi_evaluate_dsm(handle,
					&chromeos_privacy_screen_dsm_guid,
					PRIV_SCRN_DSM_REVID,
					PRIV_SCRN_DSM_FN_DISABLE, NULL);
	} else if (state == PRIVACY_SCREEN_ENABLED) {
		obj = acpi_evaluate_dsm(handle,
					&chromeos_privacy_screen_dsm_guid,
					PRIV_SCRN_DSM_REVID,
					PRIV_SCRN_DSM_FN_ENABLE, NULL);
	} else {
		dev_err(privacy_screen,
			"Bad attempt to set privacy-screen status to %u\n",
			state);
		return -EINVAL;
	}

	if (!obj) {
		dev_err(privacy_screen,
			"_DSM failed to set privacy-screen state\n");
		return -EIO;
	}

	drm_privacy_screen->hw_state = drm_privacy_screen->sw_state = state;
	ACPI_FREE(obj);
	return 0;
}

static const struct drm_privacy_screen_ops chromeos_privacy_screen_ops = {
	.get_hw_state = chromeos_privacy_screen_get_hw_state,
	.set_sw_state = chromeos_privacy_screen_set_sw_state,
};

static int chromeos_privacy_screen_add(struct acpi_device *adev)
{
	struct drm_privacy_screen *drm_privacy_screen =
		drm_privacy_screen_register(&adev->dev,
					    &chromeos_privacy_screen_ops,
					    &adev->dev);

	if (IS_ERR(drm_privacy_screen)) {
		dev_err(&adev->dev, "Error registering privacy-screen\n");
		return PTR_ERR(drm_privacy_screen);
	}

	adev->driver_data = drm_privacy_screen;
	dev_info(&adev->dev, "registered privacy-screen '%s'\n",
		 dev_name(&drm_privacy_screen->dev));

	return 0;
}

static void chromeos_privacy_screen_remove(struct acpi_device *adev)
{
	struct drm_privacy_screen *drm_privacy_screen =	acpi_driver_data(adev);

	drm_privacy_screen_unregister(drm_privacy_screen);
}

static const struct acpi_device_id chromeos_privacy_screen_device_ids[] = {
	{"GOOG0010", 0}, /* Google's electronic privacy screen for eDP-1 */
	{}
};
MODULE_DEVICE_TABLE(acpi, chromeos_privacy_screen_device_ids);

static struct acpi_driver chromeos_privacy_screen_driver = {
	.name = "chromeos_privacy_screen_driver",
	.class = "ChromeOS",
	.ids = chromeos_privacy_screen_device_ids,
	.ops = {
		.add = chromeos_privacy_screen_add,
		.remove = chromeos_privacy_screen_remove,
	},
};

module_acpi_driver(chromeos_privacy_screen_driver);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ChromeOS ACPI Privacy Screen driver");
MODULE_AUTHOR("Rajat Jain <rajatja@google.com>");