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Diffstat (limited to '')
| -rw-r--r-- | include/media/v4l2-fh.h | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h new file mode 100644 index 000000000..b5b3e00c8 --- /dev/null +++ b/include/media/v4l2-fh.h @@ -0,0 +1,161 @@ +/* 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. + * + * Copyright (C) 2009--2010 Nokia Corporation. + * + * Contact: Sakari Ailus <sakari.ailus@iki.fi> + */ + +#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; + struct v4l2_ctrl_handler *ctrl_handler; + enum v4l2_priority prio; + + /* Events */ + wait_queue_head_t wait; + struct mutex subscribe_lock; + struct list_head subscribed; + struct list_head available; + unsigned int navailable; + u32 sequence; + + struct v4l2_m2m_ctx *m2m_ctx; +}; + +/** + * 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 &struct v4l2_fh. + */ +void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev); + +/** + * 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); + +/** + * 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); + +/** + * 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); + +/** + * 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); + +/** + * 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. + */ +int v4l2_fh_release(struct file *filp); + +/** + * 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); + +/** + * 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) +{ + return v4l2_fh_is_singular(filp->private_data); +} + +#endif /* V4L2_EVENT_H */ |