1 files changed, 82 insertions, 0 deletions

diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index c6cf75909389..d6c73f79c131 100644
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -27,12 +27,14 @@
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/list.h>
+#include <linux/mutex.h>
 
 struct backlight_device;
 struct dentry;
 struct device_node;
 struct drm_connector;
 struct drm_device;
+struct drm_panel_follower;
 struct drm_panel;
 struct display_timing;
 
@@ -144,6 +146,45 @@ struct drm_panel_funcs {
 	void (*debugfs_init)(struct drm_panel *panel, struct dentry *root);
 };
 
+struct drm_panel_follower_funcs {
+	/**
+	 * @panel_prepared:
+	 *
+	 * Called after the panel has been powered on.
+	 */
+	int (*panel_prepared)(struct drm_panel_follower *follower);
+
+	/**
+	 * @panel_unpreparing:
+	 *
+	 * Called before the panel is powered off.
+	 */
+	int (*panel_unpreparing)(struct drm_panel_follower *follower);
+};
+
+struct drm_panel_follower {
+	/**
+	 * @funcs:
+	 *
+	 * Dependent device callbacks; should be initted by the caller.
+	 */
+	const struct drm_panel_follower_funcs *funcs;
+
+	/**
+	 * @list
+	 *
+	 * Used for linking into panel's list; set by drm_panel_add_follower().
+	 */
+	struct list_head list;
+
+	/**
+	 * @panel
+	 *
+	 * The panel we're dependent on; set by drm_panel_add_follower().
+	 */
+	struct drm_panel *panel;
+};
+
 /**
  * struct drm_panel - DRM panel object
  */
@@ -190,6 +231,20 @@ struct drm_panel {
 	struct list_head list;
 
 	/**
+	 * @followers:
+	 *
+	 * A list of struct drm_panel_follower dependent on this panel.
+	 */
+	struct list_head followers;
+
+	/**
+	 * @followers_lock:
+	 *
+	 * Lock for followers list.
+	 */
+	struct mutex follower_lock;
+
+	/**
 	 * @prepare_prev_first:
 	 *
 	 * The previous controller should be prepared first, before the prepare
@@ -246,6 +301,33 @@ static inline int of_drm_get_panel_orientation(const struct device_node *np,
 }
 #endif
 
+#if defined(CONFIG_DRM_PANEL)
+bool drm_is_panel_follower(struct device *dev);
+int drm_panel_add_follower(struct device *follower_dev,
+			   struct drm_panel_follower *follower);
+void drm_panel_remove_follower(struct drm_panel_follower *follower);
+int devm_drm_panel_add_follower(struct device *follower_dev,
+				struct drm_panel_follower *follower);
+#else
+static inline bool drm_is_panel_follower(struct device *dev)
+{
+	return false;
+}
+
+static inline int drm_panel_add_follower(struct device *follower_dev,
+					 struct drm_panel_follower *follower)
+{
+	return -ENODEV;
+}
+
+static inline void drm_panel_remove_follower(struct drm_panel_follower *follower) { }
+static inline int devm_drm_panel_add_follower(struct device *follower_dev,
+					      struct drm_panel_follower *follower)
+{
+	return -ENODEV;
+}
+#endif
+
 #if IS_ENABLED(CONFIG_DRM_PANEL) && (IS_BUILTIN(CONFIG_BACKLIGHT_CLASS_DEVICE) || \
 	(IS_MODULE(CONFIG_DRM) && IS_MODULE(CONFIG_BACKLIGHT_CLASS_DEVICE)))
 int drm_panel_of_backlight(struct drm_panel *panel);