diff options
Diffstat (limited to 'include/media/v4l2-fh.h')
| -rw-r--r-- | include/media/v4l2-fh.h | 178 |
1 files changed, 129 insertions, 49 deletions
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h index a62ee18cb7b7..aad4b3689d7e 100644 --- a/include/media/v4l2-fh.h +++ b/include/media/v4l2-fh.h @@ -1,36 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ /* * v4l2-fh.h * * V4L2 file handle. Store per file handle data for the V4L2 - * framework. Using file handles is optional for the drivers. + * framework. Using file handles is mandatory for the drivers. * * Copyright (C) 2009--2010 Nokia Corporation. * * Contact: Sakari Ailus <sakari.ailus@iki.fi> - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License - * version 2 as published by the Free Software Foundation. - * - * This program is distributed in the hope that it will be useful, but - * WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA - * 02110-1301 USA */ #ifndef V4L2_FH_H #define V4L2_FH_H +#include <linux/fs.h> +#include <linux/kconfig.h> #include <linux/list.h> +#include <linux/videodev2.h> 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 + * @subscribe_lock: serialise changes to the subscribed list; guarantee that + * the add and del event callbacks are orderly called + * @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; @@ -39,59 +47,131 @@ struct v4l2_fh { /* Events */ wait_queue_head_t wait; - struct list_head subscribed; /* Subscribed events */ - struct list_head available; /* Dequeueable event */ + struct mutex subscribe_lock; + struct list_head subscribed; + struct list_head available; unsigned int navailable; u32 sequence; + + struct v4l2_m2m_ctx *m2m_ctx; }; -/* - * Initialise the file handle. Parts of the V4L2 framework using the +/** + * file_to_v4l2_fh - Return the v4l2_fh associated with a struct file + * + * @filp: pointer to &struct file + * + * This function should be used by drivers to retrieve the &struct v4l2_fh + * instance pointer stored in the file private_data instead of accessing the + * private_data field directly. + */ +static inline struct v4l2_fh *file_to_v4l2_fh(struct file *filp) +{ + return filp->private_data; +} + +/** + * 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 + * @filp: pointer to &struct file associated with @fh + * + * The function sets filp->private_data to point to @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. +void v4l2_fh_add(struct v4l2_fh *fh, struct file *filp); + +/** + * 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. + * + * On error filp->private_data will be %NULL, otherwise it will point to + * the &struct v4l2_fh. */ 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 + * @filp: pointer to &struct file associated with @fh + * + * The function resets filp->private_data to NULL. + * + * .. 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. +void v4l2_fh_del(struct v4l2_fh *fh, struct file *filp); + +/** + * 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) { |