[Intel-gfx] [PATCH 8/9] platform/x86: thinkpad_acpi: Register a privacy-screen device

[Hans de Goede]

Register a privacy-screen device on laptops with a privacy-screen,
this exports the PrivacyGuard features to user-space using a
standardized vendor-agnostic sysfs interface. Note the sysfs interface
is read-only.

Registering a privacy-screen device with the new privacy-screen class
code will also allow the GPU driver to get a handle to it and export
the privacy-screen setting as a property on the DRM connector object
for the LCD panel. This DRM connector property is news standardized
interface which all user-space code should use to query and control
the privacy-screen.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 drivers/platform/x86/Kconfig         |  1 +
 drivers/platform/x86/thinkpad_acpi.c | 76 +++++++++++++++++++---------
 2 files changed, 52 insertions(+), 25 deletions(-)

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 318e083f38b3..db427ab86292 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -617,6 +617,7 @@ config THINKPAD_ACPI
 	depends on RFKILL || RFKILL = n
 	depends on ACPI_VIDEO || ACPI_VIDEO = n
 	depends on BACKLIGHT_CLASS_DEVICE
+	select DRM_PRIVACY_SCREEN
 	select HWMON
 	select NVRAM
 	select NEW_LEDS
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 782e74d3167f..7e7edac26f83 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -72,6 +72,7 @@
 #include <linux/uaccess.h>
 #include <acpi/battery.h>
 #include <acpi/video.h>
+#include <drm/drm_privacy_screen_driver.h>
 
 /* ThinkPad CMOS commands */
 #define TP_CMOS_VOLUME_DOWN	0
@@ -9699,30 +9700,40 @@ static struct ibm_struct battery_driver_data = {
  * LCD Shadow subdriver, for the Lenovo PrivacyGuard feature
  */
 
+static struct drm_privacy_screen *lcdshadow_dev;
 static acpi_handle lcdshadow_get_handle;
 static acpi_handle lcdshadow_set_handle;
-static int lcdshadow_state;
 
-static int lcdshadow_on_off(bool state)
+int lcdshadow_set_sw_state(struct drm_privacy_screen *priv,
+			   enum drm_privacy_screen_status state)
 {
 	int output;
 
+	if (WARN_ON(!mutex_is_locked(&priv->lock)))
+		return -EIO;
+
 	if (!acpi_evalf(lcdshadow_set_handle, &output, NULL, "dd", (int)state))
 		return -EIO;
 
-	lcdshadow_state = state;
+	priv->hw_state = priv->sw_state = state;
 	return 0;
 }
 
-static int lcdshadow_set(bool on)
+void lcdshadow_get_hw_state(struct drm_privacy_screen *priv)
 {
-	if (lcdshadow_state < 0)
-		return lcdshadow_state;
-	if (lcdshadow_state == on)
-		return 0;
-	return lcdshadow_on_off(on);
+	int output;
+
+	if (!acpi_evalf(lcdshadow_get_handle, &output, NULL, "dd", 0))
+		return;
+
+	priv->hw_state = priv->sw_state = output & 0x1;
 }
 
+const struct drm_privacy_screen_ops lcdshadow_ops = {
+	.set_sw_state = lcdshadow_set_sw_state,
+	.get_hw_state = lcdshadow_get_hw_state,
+};
+
 static int tpacpi_lcdshadow_init(struct ibm_init_struct *iibm)
 {
 	acpi_status status1, status2;
@@ -9730,36 +9741,44 @@ static int tpacpi_lcdshadow_init(struct ibm_init_struct *iibm)
 
 	status1 = acpi_get_handle(hkey_handle, "GSSS", &lcdshadow_get_handle);
 	status2 = acpi_get_handle(hkey_handle, "SSSS", &lcdshadow_set_handle);
-	if (ACPI_FAILURE(status1) || ACPI_FAILURE(status2)) {
-		lcdshadow_state = -ENODEV;
+	if (ACPI_FAILURE(status1) || ACPI_FAILURE(status2))
 		return 0;
-	}
 
-	if (!acpi_evalf(lcdshadow_get_handle, &output, NULL, "dd", 0)) {
-		lcdshadow_state = -EIO;
+	if (!acpi_evalf(lcdshadow_get_handle, &output, NULL, "dd", 0))
 		return -EIO;
-	}
-	if (!(output & 0x10000)) {
-		lcdshadow_state = -ENODEV;
+
+	if (!(output & 0x10000))
 		return 0;
-	}
-	lcdshadow_state = output & 0x1;
+
+	lcdshadow_dev = drm_privacy_screen_register(&tpacpi_pdev->dev,
+						    &lcdshadow_ops);
+	if (IS_ERR(lcdshadow_dev))
+		return PTR_ERR(lcdshadow_dev);
 
 	return 0;
 }
 
+static void lcdshadow_exit(void)
+{
+	drm_privacy_screen_unregister(lcdshadow_dev);
+}
+
 static void lcdshadow_resume(void)
 {
-	if (lcdshadow_state >= 0)
-		lcdshadow_on_off(lcdshadow_state);
+	if (!lcdshadow_dev)
+		return;
+
+	mutex_lock(&lcdshadow_dev->lock);
+	lcdshadow_set_sw_state(lcdshadow_dev, lcdshadow_dev->sw_state);
+	mutex_unlock(&lcdshadow_dev->lock);
 }
 
 static int lcdshadow_read(struct seq_file *m)
 {
-	if (lcdshadow_state < 0) {
+	if (!lcdshadow_dev) {
 		seq_puts(m, "status:\t\tnot supported\n");
 	} else {
-		seq_printf(m, "status:\t\t%d\n", lcdshadow_state);
+		seq_printf(m, "status:\t\t%d\n", lcdshadow_dev->hw_state);
 		seq_puts(m, "commands:\t0, 1\n");
 	}
 
@@ -9771,7 +9790,7 @@ static int lcdshadow_write(char *buf)
 	char *cmd;
 	int res, state = -EINVAL;
 
-	if (lcdshadow_state < 0)
+	if (!lcdshadow_dev)
 		return -ENODEV;
 
 	while ((cmd = strsep(&buf, ","))) {
@@ -9783,11 +9802,18 @@ static int lcdshadow_write(char *buf)
 	if (state >= 2 || state < 0)
 		return -EINVAL;
 
-	return lcdshadow_set(state);
+	mutex_lock(&lcdshadow_dev->lock);
+	res = lcdshadow_set_sw_state(lcdshadow_dev, state);
+	mutex_unlock(&lcdshadow_dev->lock);
+
+	drm_privacy_screen_call_notifier_chain(lcdshadow_dev);
+
+	return res;
 }
 
 static struct ibm_struct lcdshadow_driver_data = {
 	.name = "lcdshadow",
+	.exit = lcdshadow_exit,
 	.resume = lcdshadow_resume,
 	.read = lcdshadow_read,
 	.write = lcdshadow_write,
-- 
2.26.2