[media] v4l2-fh: add v4l2_fh_open and v4l2_fh_release helper functions

Add two new functions: v4l2_fh_open allocates and initializes a struct v4l2_fh
based on a struct file pointer and v4l2_fh_release releases and frees a struct
v4l2_fh.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h
index 5fc5ba9..5657881 100644
--- a/include/media/v4l2-fh.h
+++ b/include/media/v4l2-fh.h
@@ -51,8 +51,16 @@ int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
  */
 void v4l2_fh_add(struct v4l2_fh *fh);
 /*
+ * Can be used as the open() op of v4l2_file_operations.
+ * It allocates a v4l2_fh and inits and adds it to the video_device associated
+ * with the file pointer.
+ */
+int v4l2_fh_open(struct file *filp);
+/*
  * Remove file handle from the list of file handles. Must be called in
  * v4l2_file_operations->release() handler if the driver uses v4l2_fh.
+ * On error filp->private_data will be NULL, otherwise it will point to
+ * the v4l2_fh struct.
  */
 void v4l2_fh_del(struct v4l2_fh *fh);
 /*
@@ -62,5 +70,12 @@ void v4l2_fh_del(struct v4l2_fh *fh);
  * driver uses v4l2_fh.
  */
 void v4l2_fh_exit(struct v4l2_fh *fh);
+/*
+ * Can be used as the release() op of v4l2_file_operations.
+ * It deletes and exits the v4l2_fh associated with the file pointer and
+ * frees it. It will do nothing if filp->private_data (the pointer to the
+ * v4l2_fh struct) is NULL. This function always returns 0.
+ */
+int v4l2_fh_release(struct file *filp);
 
 #endif /* V4L2_EVENT_H */