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// 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 int 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);
return 0;
}
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>");
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