[Intel-gfx] [PATCH 2/2] platform/chrome: Add driver for ChromeOS privacy-screen
Rajat Jain
rajatja at google.com
Fri Dec 10 20:11:44 UTC 2021
This adds the ACPI driver for the ChromeOS privacy screen that is
present on some chromeos devices.
Note that I found that ACPI drivers are bound to their devices AFTER
the drm probe. So on chromebooks with privacy-screen, this causes a
probe deferral for i915 driver, which results in a delay of about 250ms
in my experiments. However, per my personal experience, it did not
result in any user perceived delay of splash screen
(https://hansdegoede.livejournal.com/25948.html)
In future if this probe deferral turns out to be an issue, we can
consider turning this ACPI driver into something that is probed earlier
than the drm drivers.
Signed-off-by: Rajat Jain <rajatja at google.com>
---
This patch is rebased on top of linux-next/master
drivers/platform/chrome/Kconfig | 10 ++
drivers/platform/chrome/Makefile | 1 +
drivers/platform/chrome/chromeos_priv_scrn.c | 133 +++++++++++++++++++
3 files changed, 144 insertions(+)
create mode 100644 drivers/platform/chrome/chromeos_priv_scrn.c
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index ccc23d8686e8..3f874bbd3d03 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -243,6 +243,16 @@ config CROS_USBPD_NOTIFY
To compile this driver as a module, choose M here: the
module will be called cros_usbpd_notify.
+config CHROMEOS_PRIVACY_SCREEN
+ bool "ChromeOS Privacy Screen support"
+ depends on ACPI
+ depends on DRM
+ default n
+ select DRM_PRIVACY_SCREEN
+ help
+ This driver provides the support needed for the in-built electronic
+ privacy screen that is present on some ChromeOS devices.
+
source "drivers/platform/chrome/wilco_ec/Kconfig"
endif # CHROMEOS_PLATFORMS
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index f901d2e43166..cfa0bb4e9e34 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -4,6 +4,7 @@
CFLAGS_cros_ec_trace.o:= -I$(src)
obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
+obj-$(CONFIG_CHROMEOS_PRIVACY_SCREEN) += chromeos_priv_scrn.o
obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
obj-$(CONFIG_CHROMEOS_TBMC) += chromeos_tbmc.o
obj-$(CONFIG_CROS_EC) += cros_ec.o
diff --git a/drivers/platform/chrome/chromeos_priv_scrn.c b/drivers/platform/chrome/chromeos_priv_scrn.c
new file mode 100644
index 000000000000..00536154acd6
--- /dev/null
+++ b/drivers/platform/chrome/chromeos_priv_scrn.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * chromeos_priv_scrn.c - ChromeOS Privacy Screen support
+ *
+ * Copyright (C) 2022 The Chromium OS Authors
+ *
+ */
+
+#include <linux/acpi.h>
+#include <drm/drm_privacy_screen_driver.h>
+
+/*
+ * The DSM (Define 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_priv_scrn_dsm_guid =
+ GUID_INIT(0xc7033113, 0x8720, 0x4ceb,
+ 0x90, 0x90, 0x9d, 0x52, 0xb3, 0xe5, 0x2d, 0x73);
+
+static void
+chromeos_priv_scrn_get_hw_state(struct drm_privacy_screen *drm_priv_scrn)
+{
+ union acpi_object *obj;
+ acpi_handle handle;
+ struct device *priv_scrn = drm_priv_scrn->dev.parent;
+
+ if (!priv_scrn)
+ return;
+
+ handle = acpi_device_handle(to_acpi_device(priv_scrn));
+ obj = acpi_evaluate_dsm(handle, &chromeos_priv_scrn_dsm_guid,
+ PRIV_SCRN_DSM_REVID,
+ PRIV_SCRN_DSM_FN_GET_STATUS, NULL);
+ if (!obj) {
+ dev_err(priv_scrn, "_DSM failed to get privacy-screen state\n");
+ return;
+ }
+
+ if (obj->type != ACPI_TYPE_INTEGER)
+ dev_err(priv_scrn, "Bad _DSM to get privacy-screen state\n");
+ else if (obj->integer.value == 1)
+ drm_priv_scrn->hw_state = drm_priv_scrn->sw_state =
+ PRIVACY_SCREEN_ENABLED;
+ else
+ drm_priv_scrn->hw_state = drm_priv_scrn->sw_state =
+ PRIVACY_SCREEN_DISABLED;
+
+ ACPI_FREE(obj);
+}
+
+static int
+chromeos_priv_scrn_set_sw_state(struct drm_privacy_screen *drm_priv_scrn,
+ enum drm_privacy_screen_status state)
+{
+ union acpi_object *obj = NULL;
+ acpi_handle handle;
+ struct device *priv_scrn = drm_priv_scrn->dev.parent;
+
+ if (!priv_scrn)
+ return -ENODEV;
+
+ handle = acpi_device_handle(to_acpi_device(priv_scrn));
+
+ if (state == PRIVACY_SCREEN_DISABLED) {
+ obj = acpi_evaluate_dsm(handle, &chromeos_priv_scrn_dsm_guid,
+ PRIV_SCRN_DSM_REVID,
+ PRIV_SCRN_DSM_FN_DISABLE, NULL);
+ } else if (state == PRIVACY_SCREEN_ENABLED) {
+ obj = acpi_evaluate_dsm(handle, &chromeos_priv_scrn_dsm_guid,
+ PRIV_SCRN_DSM_REVID,
+ PRIV_SCRN_DSM_FN_ENABLE, NULL);
+ } else {
+ dev_err(priv_scrn, "Bad attempt to set privacy-screen status\n");
+ return -EINVAL;
+ }
+
+ if (!obj) {
+ dev_err(priv_scrn, "_DSM failed to set privacy-screen state\n");
+ return -EIO;
+ }
+
+ drm_priv_scrn->hw_state = drm_priv_scrn->sw_state = state;
+ ACPI_FREE(obj);
+ return 0;
+}
+
+static const struct drm_privacy_screen_ops chromeos_priv_scrn_ops = {
+ .get_hw_state = chromeos_priv_scrn_get_hw_state,
+ .set_sw_state = chromeos_priv_scrn_set_sw_state,
+};
+
+static int chromeos_priv_scrn_add(struct acpi_device *adev)
+{
+ struct drm_privacy_screen *drm_priv_scrn =
+ drm_privacy_screen_register(&adev->dev, &chromeos_priv_scrn_ops);
+
+ if (IS_ERR(drm_priv_scrn)) {
+ dev_err(&adev->dev, "Error registering privacy-screen\n");
+ return PTR_ERR(drm_priv_scrn);
+ }
+
+ dev_info(&adev->dev, " registered privacy-screen '%s'\n",
+ dev_name(&drm_priv_scrn->dev));
+
+ return 0;
+}
+
+static const struct acpi_device_id chromeos_priv_scrn_device_ids[] = {
+ {"GOOG0010", 0}, /* Google's electronic privacy screen for eDP-1 */
+ {}
+};
+MODULE_DEVICE_TABLE(acpi, chromeos_priv_scrn_device_ids);
+
+static struct acpi_driver chromeos_priv_scrn_driver = {
+ .name = "chromeos_priv_scrn_drvr",
+ .class = "ChromeOS",
+ .ids = chromeos_priv_scrn_device_ids,
+ .ops = {
+ .add = chromeos_priv_scrn_add,
+ },
+ .owner = THIS_MODULE,
+};
+
+module_acpi_driver(chromeos_priv_scrn_driver);
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("ChromeOS ACPI Privacy Screen driver");
+MODULE_AUTHOR("Rajat Jain <rajatja at google.com>");
--
2.34.1.173.g76aa8bc2d0-goog
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