Add support for privacy-screen consumers to register a notifier to be notified of external (e.g. done by the hw itself on a hotkey press) state changes.
Signed-off-by: Hans de Goede hdegoede@redhat.com --- drivers/gpu/drm/drm_privacy_screen.c | 67 +++++++++++++++++++++++ include/drm/drm_privacy_screen_consumer.h | 5 ++ include/drm/drm_privacy_screen_driver.h | 4 ++ 3 files changed, 76 insertions(+)
diff --git a/drivers/gpu/drm/drm_privacy_screen.c b/drivers/gpu/drm/drm_privacy_screen.c index 6296fd46156c..7e78b4068e8f 100644 --- a/drivers/gpu/drm/drm_privacy_screen.c +++ b/drivers/gpu/drm/drm_privacy_screen.c @@ -254,6 +254,49 @@ void drm_privacy_screen_get_state(struct drm_privacy_screen *priv, } EXPORT_SYMBOL(drm_privacy_screen_get_state);
+/** + * drm_privacy_screen_register_notifier - register a notifier + * @priv: Privacy screen to register the notifier with + * @nb: Notifier-block for the notifier to register + * + * Register a notifier with the privacy-screen to be notified of changes made + * to the privacy-screen state from outside of the privacy-screen class. + * E.g. the state may be changed by the hardware itself in response to a + * hotkey press. + * + * The notifier is called with no locks held. The new hw_state and sw_state + * can be retrieved using the drm_privacy_screen_get_state() function. + * A pointer to the drm_privacy_screen's struct is passed as the void *data + * argument of the notifier_block's notifier_call. + * + * The notifier will NOT be called when changes are made through + * drm_privacy_screen_set_sw_state(). It is only called for external changes. + * + * Return: 0 on success, negative error code on failure. + */ +int drm_privacy_screen_register_notifier(struct drm_privacy_screen *priv, + struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&priv->notifier_head, nb); +} +EXPORT_SYMBOL(drm_privacy_screen_register_notifier); + +/** + * drm_privacy_screen_unregister_notifier - unregister a notifier + * @priv: Privacy screen to register the notifier with + * @nb: Notifier-block for the notifier to register + * + * Unregister a notifier registered with drm_privacy_screen_register_notifier(). + * + * Return: 0 on success, negative error code on failure. + */ +int drm_privacy_screen_unregister_notifier(struct drm_privacy_screen *priv, + struct notifier_block *nb) +{ + return blocking_notifier_chain_unregister(&priv->notifier_head, nb); +} +EXPORT_SYMBOL(drm_privacy_screen_unregister_notifier); + /*** drm_privacy_screen_driver.h functions ***/
static ssize_t sw_state_show(struct device *dev, @@ -352,6 +395,7 @@ struct drm_privacy_screen *drm_privacy_screen_register( return ERR_PTR(-ENOMEM);
mutex_init(&priv->lock); + BLOCKING_INIT_NOTIFIER_HEAD(&priv->notifier_head);
priv->dev.class = &drm_privacy_screen_class; priv->dev.parent = parent; @@ -399,6 +443,29 @@ void drm_privacy_screen_unregister(struct drm_privacy_screen *priv) } EXPORT_SYMBOL(drm_privacy_screen_unregister);
+/** + * drm_privacy_screen_call_notifier_chain - notify consumers of state change + * @priv: Privacy screen to register the notifier with + * + * A privacy-screen provider driver can call this functions upon external + * changes to the privacy-screen state. E.g. the state may be changed by the + * hardware itself in response to a hotkey press. + * This function must be called without holding the privacy-screen lock. + * the driver must update sw_state and hw_state to reflect the new state before + * calling this function. + * The expected behavior from the driver upon receiving an external state + * change event is: 1. Take the lock; 2. Update sw_state and hw_state; + * 3. Release the lock. 4. Call drm_privacy_screen_call_notifier_chain(). + */ +void drm_privacy_screen_call_notifier_chain(struct drm_privacy_screen *priv) +{ + if (WARN_ON(mutex_is_locked(&priv->lock))) + return; + + blocking_notifier_call_chain(&priv->notifier_head, 0, priv); +} +EXPORT_SYMBOL(drm_privacy_screen_call_notifier_chain); + static int __init drm_privacy_screen_init(void) { int ret; diff --git a/include/drm/drm_privacy_screen_consumer.h b/include/drm/drm_privacy_screen_consumer.h index 169ba72bd60d..1f33dc1457ff 100644 --- a/include/drm/drm_privacy_screen_consumer.h +++ b/include/drm/drm_privacy_screen_consumer.h @@ -24,4 +24,9 @@ void drm_privacy_screen_get_state(struct drm_privacy_screen *priv, enum drm_privacy_screen_status *sw_state_ret, enum drm_privacy_screen_status *hw_state_ret);
+int drm_privacy_screen_register_notifier(struct drm_privacy_screen *priv, + struct notifier_block *nb); +int drm_privacy_screen_unregister_notifier(struct drm_privacy_screen *priv, + struct notifier_block *nb); + #endif diff --git a/include/drm/drm_privacy_screen_driver.h b/include/drm/drm_privacy_screen_driver.h index 5187ae52eb03..24591b607675 100644 --- a/include/drm/drm_privacy_screen_driver.h +++ b/include/drm/drm_privacy_screen_driver.h @@ -54,6 +54,8 @@ struct drm_privacy_screen { struct mutex lock; /** @list: privacy-screen devices list list-entry. */ struct list_head list; + /** @notifier_head: privacy-screen notifier head. */ + struct blocking_notifier_head notifier_head; /** * @ops: &struct drm_privacy_screen_ops for this privacy-screen. * This is NULL if the driver has unregistered the privacy-screen. @@ -77,4 +79,6 @@ struct drm_privacy_screen *drm_privacy_screen_register( struct device *parent, const struct drm_privacy_screen_ops *ops); void drm_privacy_screen_unregister(struct drm_privacy_screen *priv);
+void drm_privacy_screen_call_notifier_chain(struct drm_privacy_screen *priv); + #endif