[PATCH 1/7] media: v4l2-core: add v4l2_debugfs_root()

[Hans Verkuil <hverkuil-cisco@xxxxxxxxx>]

This new function returns the dentry of the top-level debugfs "v4l2"
directory. If it does not exist yet, then it is created first.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
---
 drivers/media/v4l2-core/v4l2-dev.c | 14 ++++++++++++++
 include/media/v4l2-dev.h           | 15 +++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index be2ba7ca5de2..4bbf279a0c8b 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -93,6 +93,8 @@ static struct attribute *video_device_attrs[] = {
 };
 ATTRIBUTE_GROUPS(video_device);
 
+static struct dentry *v4l2_debugfs_root_dir;
+
 /*
  *	Active devices
  */
@@ -1104,6 +1106,16 @@ void video_unregister_device(struct video_device *vdev)
 }
 EXPORT_SYMBOL(video_unregister_device);
 
+#ifdef CONFIG_DEBUG_FS
+struct dentry *v4l2_debugfs_root(void)
+{
+	if (!v4l2_debugfs_root_dir)
+		v4l2_debugfs_root_dir = debugfs_create_dir("v4l2", NULL);
+	return v4l2_debugfs_root_dir;
+}
+EXPORT_SYMBOL_GPL(v4l2_debugfs_root);
+#endif
+
 #if defined(CONFIG_MEDIA_CONTROLLER)
 
 __must_check int video_device_pipeline_start(struct video_device *vdev,
@@ -1208,6 +1220,8 @@ static void __exit videodev_exit(void)
 
 	class_unregister(&video_class);
 	unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
+	debugfs_remove_recursive(v4l2_debugfs_root_dir);
+	v4l2_debugfs_root_dir = NULL;
 }
 
 subsys_initcall(videodev_init);
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index d82dfdbf6e58..1b6222fab24e 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -62,6 +62,7 @@ struct v4l2_ioctl_callbacks;
 struct video_device;
 struct v4l2_device;
 struct v4l2_ctrl_handler;
+struct dentry;
 
 /**
  * enum v4l2_video_device_flags - Flags used by &struct video_device
@@ -539,6 +540,20 @@ static inline int video_is_registered(struct video_device *vdev)
 	return test_bit(V4L2_FL_REGISTERED, &vdev->flags);
 }
 
+/**
+ * v4l2_debugfs_root - returns the dentry of the top-level "v4l2" debugfs dir
+ *
+ * If this directory does not yet exist, then it will be created.
+ */
+#ifdef CONFIG_DEBUG_FS
+struct dentry *v4l2_debugfs_root(void);
+#else
+static inline struct dentry *v4l2_debugfs_root(void)
+{
+	return NULL;
+}
+#endif
+
 #if defined(CONFIG_MEDIA_CONTROLLER)
 
 /**
-- 
2.43.0