Commit 4ada120e authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab

[media] v4l2-fh.h: add documentation for it

This header file was undocumented. Add documentation for it.
Signed-off-by: 's avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent d2316856
......@@ -8,6 +8,7 @@ Video2Linux devices
v4l2-dev
v4l2-controls
v4l2-device
v4l2-fh
v4l2-dv-timings
v4l2-event
v4l2-flash-led-class
......
V4L2 File Handler kAPI
^^^^^^^^^^^^^^^^^^^^^^
.. kernel-doc:: include/media/v4l2-fh.h
......@@ -33,6 +33,21 @@
struct video_device;
struct v4l2_ctrl_handler;
/**
* struct v4l2_fh - Describes a V4L2 file handler
*
* @list: list of file handlers
* @vdev: pointer to &struct video_device
* @ctrl_handler: pointer to &struct v4l2_ctrl_handler
* @prio: priority of the file handler, as defined by &enum v4l2_priority
*
* @wait: event' s wait queue
* @subscribed: list of subscribed events
* @available: list of events waiting to be dequeued
* @navailable: number of available events at @available list
* @sequence: event sequence number
* @m2m_ctx: pointer to &struct v4l2_m2m_ctx
*/
struct v4l2_fh {
struct list_head list;
struct video_device *vdev;
......@@ -41,8 +56,8 @@ struct v4l2_fh {
/* Events */
wait_queue_head_t wait;
struct list_head subscribed; /* Subscribed events */
struct list_head available; /* Dequeueable event */
struct list_head subscribed;
struct list_head available;
unsigned int navailable;
u32 sequence;
......@@ -51,53 +66,102 @@ struct v4l2_fh {
#endif
};
/*
* Initialise the file handle. Parts of the V4L2 framework using the
/**
* v4l2_fh_init - Initialise the file handle.
*
* @fh: pointer to &struct v4l2_fh
* @vdev: pointer to &struct video_device
*
* Parts of the V4L2 framework using the
* file handles should be initialised in this function. Must be called
* from driver's v4l2_file_operations->open() handler if the driver
* uses v4l2_fh.
* from driver's v4l2_file_operations->open\(\) handler if the driver
* uses &struct v4l2_fh.
*/
void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
/*
* Add the fh to the list of file handles on a video_device. The file
* handle must be initialised first.
/**
* v4l2_fh_add - Add the fh to the list of file handles on a video_device.
*
* @fh: pointer to &struct v4l2_fh
*
* .. note::
* The @fh file handle must be initialised first.
*/
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.
/**
* v4l2_fh_open - Ancillary routine that can be used as the open\(\) op
* of v4l2_file_operations.
*
* @filp: pointer to struct file
*
* It allocates a v4l2_fh and inits and adds it to the &struct 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.
/**
* v4l2_fh_del - Remove file handle from the list of file handles.
*
* @fh: pointer to &struct v4l2_fh
*
* On error filp->private_data will be %NULL, otherwise it will point to
* the &struct v4l2_fh.
*
* .. note::
* Must be called in v4l2_file_operations->release\(\) handler if the driver
* uses &struct v4l2_fh.
*/
void v4l2_fh_del(struct v4l2_fh *fh);
/*
* Release resources related to a file handle. Parts of the V4L2
* framework using the v4l2_fh must release their resources here, too.
* Must be called in v4l2_file_operations->release() handler if the
* driver uses v4l2_fh.
/**
* v4l2_fh_exit - Release resources related to a file handle.
*
* @fh: pointer to &struct v4l2_fh
*
* Parts of the V4L2 framework using the v4l2_fh must release their
* resources here, too.
*
* .. note::
* Must be called in v4l2_file_operations->release\(\) handler if the
* driver uses &struct v4l2_fh.
*/
void v4l2_fh_exit(struct v4l2_fh *fh);
/*
* Can be used as the release() op of v4l2_file_operations.
/**
* v4l2_fh_release - Ancillary routine that can be used as the release\(\) op
* of v4l2_file_operations.
*
* @filp: pointer to struct file
*
* 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.
* v4l2_fh struct) is %NULL.
*
* This function always returns 0.
*/
int v4l2_fh_release(struct file *filp);
/*
* Returns 1 if this filehandle is the only filehandle opened for the
* associated video_device. If fh is NULL, then it returns 0.
/**
* v4l2_fh_is_singular - Returns 1 if this filehandle is the only filehandle
* opened for the associated video_device.
*
* @fh: pointer to &struct v4l2_fh
*
* If @fh is NULL, then it returns 0.
*/
int v4l2_fh_is_singular(struct v4l2_fh *fh);
/*
* Helper function with struct file as argument. If filp->private_data is
* NULL, then it will return 0.
/**
* v4l2_fh_is_singular_file - Returns 1 if this filehandle is the only
* filehandle opened for the associated video_device.
*
* @filp: pointer to struct file
*
* This is a helper function variant of v4l2_fh_is_singular() with uses
* struct file as argument.
*
* If filp->private_data is %NULL, then it will return 0.
*/
static inline int v4l2_fh_is_singular_file(struct file *filp)
{
......
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