// SPDX-License-Identifier: GPL-2.0-only
/*
 * v4l2-fh.c
 *
 * V4L2 file handles.
 *
 * Copyright (C) 2009--2010 Nokia Corporation.
 *
 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
 */

#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <media/v4l2-dev.h>
#include <media/v4l2-fh.h>
#include <media/v4l2-event.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-mc.h>

void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
{
        fh->vdev = vdev;
        /* Inherit from video_device. May be overridden by the driver. */
        fh->ctrl_handler = vdev->ctrl_handler;
        INIT_LIST_HEAD(&fh->list);
        set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
        /*
         * determine_valid_ioctls() does not know if struct v4l2_fh
         * is used by this driver, but here we do. So enable the
         * prio ioctls here.
         */
        set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
        set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
        fh->prio = V4L2_PRIORITY_UNSET;
        init_waitqueue_head(&fh->wait);
        INIT_LIST_HEAD(&fh->available);
        INIT_LIST_HEAD(&fh->subscribed);
        fh->sequence = -1;
        mutex_init(&fh->subscribe_lock);
}
EXPORT_SYMBOL_GPL(v4l2_fh_init);

void v4l2_fh_add(struct v4l2_fh *fh, struct file *filp)
{
        unsigned long flags;

        filp->private_data = fh;

        v4l2_prio_open(fh->vdev->prio, &fh->prio);
        spin_lock_irqsave(&fh->vdev->fh_lock, flags);
        list_add(&fh->list, &fh->vdev->fh_list);
        spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
}
EXPORT_SYMBOL_GPL(v4l2_fh_add);

int v4l2_fh_open(struct file *filp)
{
        struct video_device *vdev = video_devdata(filp);
        struct v4l2_fh *fh = kzalloc_obj(*fh);

        if (fh == NULL)
                return -ENOMEM;
        v4l2_fh_init(fh, vdev);
        v4l2_fh_add(fh, filp);
        return 0;
}
EXPORT_SYMBOL_GPL(v4l2_fh_open);

void v4l2_fh_del(struct v4l2_fh *fh, struct file *filp)
{
        unsigned long flags;

        spin_lock_irqsave(&fh->vdev->fh_lock, flags);
        list_del_init(&fh->list);
        spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
        v4l2_prio_close(fh->vdev->prio, fh->prio);

        filp->private_data = NULL;
}
EXPORT_SYMBOL_GPL(v4l2_fh_del);

void v4l2_fh_exit(struct v4l2_fh *fh)
{
        if (fh->vdev == NULL)
                return;
        v4l_disable_media_source(fh->vdev);
        v4l2_event_unsubscribe_all(fh);
        mutex_destroy(&fh->subscribe_lock);
        fh->vdev = NULL;
}
EXPORT_SYMBOL_GPL(v4l2_fh_exit);

int v4l2_fh_release(struct file *filp)
{
        struct v4l2_fh *fh = file_to_v4l2_fh(filp);

        if (fh) {
                v4l2_fh_del(fh, filp);
                v4l2_fh_exit(fh);
                kfree(fh);
        }
        return 0;
}
EXPORT_SYMBOL_GPL(v4l2_fh_release);

int v4l2_fh_is_singular(struct v4l2_fh *fh)
{
        unsigned long flags;
        int is_singular;

        if (fh == NULL || fh->vdev == NULL)
                return 0;
        spin_lock_irqsave(&fh->vdev->fh_lock, flags);
        is_singular = list_is_singular(&fh->list);
        spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
        return is_singular;
}
EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);