@@ -1,3 +1,137 @@
+V4L2 File handlers
+------------------
+
+struct v4l2_fh provides a way to easily keep file handle specific data
+that is used by the V4L2 framework. New drivers must use struct v4l2_fh
+since it is also used to implement priority handling (VIDIOC_G/S_PRIORITY).
+
+The users of v4l2_fh (in the V4L2 framework, not the driver) know
+whether a driver uses v4l2_fh as its file->private_data pointer by
+testing the V4L2_FL_USES_V4L2_FH bit in video_device->flags. This bit is
+set whenever v4l2_fh_init() is called.
+
+struct v4l2_fh is allocated as a part of the driver's own file handle
+structure and file->private_data is set to it in the driver's open
+function by the driver.
+
+In many cases the struct v4l2_fh will be embedded in a larger structure.
+In that case you should call v4l2_fh_init+v4l2_fh_add in open() and
+v4l2_fh_del+v4l2_fh_exit in release().
+
+Drivers can extract their own file handle structure by using the container_of
+macro. Example:
+
+.. code-block:: none
+
+ struct my_fh {
+ int blah;
+ struct v4l2_fh fh;
+ };
+
+ ...
+
+ int my_open(struct file *file)
+ {
+ struct my_fh *my_fh;
+ struct video_device *vfd;
+ int ret;
+
+ ...
+
+ my_fh = kzalloc(sizeof(*my_fh), GFP_KERNEL);
+
+ ...
+
+ v4l2_fh_init(&my_fh->fh, vfd);
+
+ ...
+
+ file->private_data = &my_fh->fh;
+ v4l2_fh_add(&my_fh->fh);
+ return 0;
+ }
+
+ int my_release(struct file *file)
+ {
+ struct v4l2_fh *fh = file->private_data;
+ struct my_fh *my_fh = container_of(fh, struct my_fh, fh);
+
+ ...
+ v4l2_fh_del(&my_fh->fh);
+ v4l2_fh_exit(&my_fh->fh);
+ kfree(my_fh);
+ return 0;
+ }
+
+Below is a short description of the v4l2_fh functions used:
+
+.. code-block:: none
+
+ void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
+
+ Initialise the file handle. This *MUST* be performed in the driver's
+ v4l2_file_operations->open() handler.
+
+.. code-block:: none
+
+ void v4l2_fh_add(struct v4l2_fh *fh)
+
+ Add a v4l2_fh to video_device file handle list. Must be called once the
+ file handle is completely initialized.
+
+.. code-block:: none
+
+ void v4l2_fh_del(struct v4l2_fh *fh)
+
+ Unassociate the file handle from video_device(). The file handle
+ exit function may now be called.
+
+.. code-block:: none
+
+ void v4l2_fh_exit(struct v4l2_fh *fh)
+
+ Uninitialise the file handle. After uninitialisation the v4l2_fh
+ memory can be freed.
+
+
+If struct v4l2_fh is not embedded, then you can use these helper functions:
+
+.. code-block:: none
+
+ int v4l2_fh_open(struct file *filp)
+
+ This allocates a struct v4l2_fh, initializes it and adds it to the struct
+ video_device associated with the file struct.
+
+.. code-block:: none
+
+ int v4l2_fh_release(struct file *filp)
+
+ This deletes it from the struct video_device associated with the file
+ struct, uninitialised the v4l2_fh and frees it.
+
+These two functions can be plugged into the v4l2_file_operation's open() and
+release() ops.
+
+
+Several drivers need to do something when the first file handle is opened and
+when the last file handle closes. Two helper functions were added to check
+whether the v4l2_fh struct is the only open filehandle of the associated
+device node:
+
+.. code-block:: none
+
+ int v4l2_fh_is_singular(struct v4l2_fh *fh)
+
+ Returns 1 if the file handle is the only open file handle, else 0.
+
+.. code-block:: none
+
+ int v4l2_fh_is_singular_file(struct file *filp)
+
+ Same, but it calls v4l2_fh_is_singular with filp->private_data.
+
+
V4L2 File Handler kAPI
^^^^^^^^^^^^^^^^^^^^^^
.. kernel-doc:: include/media/v4l2-fh.h
@@ -80,139 +80,6 @@ The V4L2 framework also optionally integrates with the media framework. If a
driver sets the struct v4l2_device mdev field, sub-devices and video nodes
will automatically appear in the media framework as entities.
-struct v4l2_fh
---------------
-
-struct v4l2_fh provides a way to easily keep file handle specific data
-that is used by the V4L2 framework. New drivers must use struct v4l2_fh
-since it is also used to implement priority handling (VIDIOC_G/S_PRIORITY).
-
-The users of v4l2_fh (in the V4L2 framework, not the driver) know
-whether a driver uses v4l2_fh as its file->private_data pointer by
-testing the V4L2_FL_USES_V4L2_FH bit in video_device->flags. This bit is
-set whenever v4l2_fh_init() is called.
-
-struct v4l2_fh is allocated as a part of the driver's own file handle
-structure and file->private_data is set to it in the driver's open
-function by the driver.
-
-In many cases the struct v4l2_fh will be embedded in a larger structure.
-In that case you should call v4l2_fh_init+v4l2_fh_add in open() and
-v4l2_fh_del+v4l2_fh_exit in release().
-
-Drivers can extract their own file handle structure by using the container_of
-macro. Example:
-
-.. code-block:: none
-
- struct my_fh {
- int blah;
- struct v4l2_fh fh;
- };
-
- ...
-
- int my_open(struct file *file)
- {
- struct my_fh *my_fh;
- struct video_device *vfd;
- int ret;
-
- ...
-
- my_fh = kzalloc(sizeof(*my_fh), GFP_KERNEL);
-
- ...
-
- v4l2_fh_init(&my_fh->fh, vfd);
-
- ...
-
- file->private_data = &my_fh->fh;
- v4l2_fh_add(&my_fh->fh);
- return 0;
- }
-
- int my_release(struct file *file)
- {
- struct v4l2_fh *fh = file->private_data;
- struct my_fh *my_fh = container_of(fh, struct my_fh, fh);
-
- ...
- v4l2_fh_del(&my_fh->fh);
- v4l2_fh_exit(&my_fh->fh);
- kfree(my_fh);
- return 0;
- }
-
-Below is a short description of the v4l2_fh functions used:
-
-.. code-block:: none
-
- void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
-
- Initialise the file handle. This *MUST* be performed in the driver's
- v4l2_file_operations->open() handler.
-
-.. code-block:: none
-
- void v4l2_fh_add(struct v4l2_fh *fh)
-
- Add a v4l2_fh to video_device file handle list. Must be called once the
- file handle is completely initialized.
-
-.. code-block:: none
-
- void v4l2_fh_del(struct v4l2_fh *fh)
-
- Unassociate the file handle from video_device(). The file handle
- exit function may now be called.
-
-.. code-block:: none
-
- void v4l2_fh_exit(struct v4l2_fh *fh)
-
- Uninitialise the file handle. After uninitialisation the v4l2_fh
- memory can be freed.
-
-
-If struct v4l2_fh is not embedded, then you can use these helper functions:
-
-.. code-block:: none
-
- int v4l2_fh_open(struct file *filp)
-
- This allocates a struct v4l2_fh, initializes it and adds it to the struct
- video_device associated with the file struct.
-
-.. code-block:: none
-
- int v4l2_fh_release(struct file *filp)
-
- This deletes it from the struct video_device associated with the file
- struct, uninitialised the v4l2_fh and frees it.
-
-These two functions can be plugged into the v4l2_file_operation's open() and
-release() ops.
-
-
-Several drivers need to do something when the first file handle is opened and
-when the last file handle closes. Two helper functions were added to check
-whether the v4l2_fh struct is the only open filehandle of the associated
-device node:
-
-.. code-block:: none
-
- int v4l2_fh_is_singular(struct v4l2_fh *fh)
-
- Returns 1 if the file handle is the only open file handle, else 0.
-
-.. code-block:: none
-
- int v4l2_fh_is_singular_file(struct file *filp)
-
- Same, but it calls v4l2_fh_is_singular with filp->private_data.
-
V4L2 clocks
-----------
Move the v4l2_fh specific content from v4l2-framework.rst to v4l2-fh.rst. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> --- Documentation/media/kapi/v4l2-fh.rst | 134 ++++++++++++++++++++++++++++ Documentation/media/kapi/v4l2-framework.rst | 133 --------------------------- 2 files changed, 134 insertions(+), 133 deletions(-)