1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4 * ChromeOS Privacy Screen support
5 *
6 * Copyright (C) 2022 Google LLC
7 *
8 * This is the Chromeos privacy screen provider, present on certain chromebooks,
9 * represented by a GOOG0010 device in the ACPI. This ACPI device, if present,
10 * will cause the i915 drm driver to probe defer until this driver registers
11 * the privacy-screen.
12 */
13
14 #include <linux/acpi.h>
15 #include <drm/drm_privacy_screen_driver.h>
16
17 /*
18 * The DSM (Device Specific Method) constants below are the agreed API with
19 * the firmware team, on how to control privacy screen using ACPI methods.
20 */
21 #define PRIV_SCRN_DSM_REVID 1 /* DSM version */
22 #define PRIV_SCRN_DSM_FN_GET_STATUS 1 /* Get privacy screen status */
23 #define PRIV_SCRN_DSM_FN_ENABLE 2 /* Enable privacy screen */
24 #define PRIV_SCRN_DSM_FN_DISABLE 3 /* Disable privacy screen */
25
26 static const guid_t chromeos_privacy_screen_dsm_guid =
27 GUID_INIT(0xc7033113, 0x8720, 0x4ceb,
28 0x90, 0x90, 0x9d, 0x52, 0xb3, 0xe5, 0x2d, 0x73);
29
30 static void
chromeos_privacy_screen_get_hw_state(struct drm_privacy_screen * drm_privacy_screen)31 chromeos_privacy_screen_get_hw_state(struct drm_privacy_screen
32 *drm_privacy_screen)
33 {
34 union acpi_object *obj;
35 acpi_handle handle;
36 struct device *privacy_screen =
37 drm_privacy_screen_get_drvdata(drm_privacy_screen);
38
39 handle = acpi_device_handle(to_acpi_device(privacy_screen));
40 obj = acpi_evaluate_dsm(handle, &chromeos_privacy_screen_dsm_guid,
41 PRIV_SCRN_DSM_REVID,
42 PRIV_SCRN_DSM_FN_GET_STATUS, NULL);
43 if (!obj) {
44 dev_err(privacy_screen,
45 "_DSM failed to get privacy-screen state\n");
46 return;
47 }
48
49 if (obj->type != ACPI_TYPE_INTEGER)
50 dev_err(privacy_screen,
51 "Bad _DSM to get privacy-screen state\n");
52 else if (obj->integer.value == 1)
53 drm_privacy_screen->hw_state = drm_privacy_screen->sw_state =
54 PRIVACY_SCREEN_ENABLED;
55 else
56 drm_privacy_screen->hw_state = drm_privacy_screen->sw_state =
57 PRIVACY_SCREEN_DISABLED;
58
59 ACPI_FREE(obj);
60 }
61
62 static int
chromeos_privacy_screen_set_sw_state(struct drm_privacy_screen * drm_privacy_screen,enum drm_privacy_screen_status state)63 chromeos_privacy_screen_set_sw_state(struct drm_privacy_screen
64 *drm_privacy_screen,
65 enum drm_privacy_screen_status state)
66 {
67 union acpi_object *obj = NULL;
68 acpi_handle handle;
69 struct device *privacy_screen =
70 drm_privacy_screen_get_drvdata(drm_privacy_screen);
71
72 handle = acpi_device_handle(to_acpi_device(privacy_screen));
73
74 if (state == PRIVACY_SCREEN_DISABLED) {
75 obj = acpi_evaluate_dsm(handle,
76 &chromeos_privacy_screen_dsm_guid,
77 PRIV_SCRN_DSM_REVID,
78 PRIV_SCRN_DSM_FN_DISABLE, NULL);
79 } else if (state == PRIVACY_SCREEN_ENABLED) {
80 obj = acpi_evaluate_dsm(handle,
81 &chromeos_privacy_screen_dsm_guid,
82 PRIV_SCRN_DSM_REVID,
83 PRIV_SCRN_DSM_FN_ENABLE, NULL);
84 } else {
85 dev_err(privacy_screen,
86 "Bad attempt to set privacy-screen status to %u\n",
87 state);
88 return -EINVAL;
89 }
90
91 if (!obj) {
92 dev_err(privacy_screen,
93 "_DSM failed to set privacy-screen state\n");
94 return -EIO;
95 }
96
97 drm_privacy_screen->hw_state = drm_privacy_screen->sw_state = state;
98 ACPI_FREE(obj);
99 return 0;
100 }
101
102 static const struct drm_privacy_screen_ops chromeos_privacy_screen_ops = {
103 .get_hw_state = chromeos_privacy_screen_get_hw_state,
104 .set_sw_state = chromeos_privacy_screen_set_sw_state,
105 };
106
chromeos_privacy_screen_add(struct acpi_device * adev)107 static int chromeos_privacy_screen_add(struct acpi_device *adev)
108 {
109 struct drm_privacy_screen *drm_privacy_screen =
110 drm_privacy_screen_register(&adev->dev,
111 &chromeos_privacy_screen_ops,
112 &adev->dev);
113
114 if (IS_ERR(drm_privacy_screen)) {
115 dev_err(&adev->dev, "Error registering privacy-screen\n");
116 return PTR_ERR(drm_privacy_screen);
117 }
118
119 adev->driver_data = drm_privacy_screen;
120 dev_info(&adev->dev, "registered privacy-screen '%s'\n",
121 dev_name(&drm_privacy_screen->dev));
122
123 return 0;
124 }
125
chromeos_privacy_screen_remove(struct acpi_device * adev)126 static int chromeos_privacy_screen_remove(struct acpi_device *adev)
127 {
128 struct drm_privacy_screen *drm_privacy_screen = acpi_driver_data(adev);
129
130 drm_privacy_screen_unregister(drm_privacy_screen);
131 return 0;
132 }
133
134 static const struct acpi_device_id chromeos_privacy_screen_device_ids[] = {
135 {"GOOG0010", 0}, /* Google's electronic privacy screen for eDP-1 */
136 {}
137 };
138 MODULE_DEVICE_TABLE(acpi, chromeos_privacy_screen_device_ids);
139
140 static struct acpi_driver chromeos_privacy_screen_driver = {
141 .name = "chromeos_privacy_screen_driver",
142 .class = "ChromeOS",
143 .ids = chromeos_privacy_screen_device_ids,
144 .ops = {
145 .add = chromeos_privacy_screen_add,
146 .remove = chromeos_privacy_screen_remove,
147 },
148 };
149
150 module_acpi_driver(chromeos_privacy_screen_driver);
151 MODULE_LICENSE("GPL v2");
152 MODULE_DESCRIPTION("ChromeOS ACPI Privacy Screen driver");
153 MODULE_AUTHOR("Rajat Jain <rajatja@google.com>");
154