LXR linux/drivers/media/v4l2-core/v4l2-fh.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * v4l2-fh.c
   4 *
   5 * V4L2 file handles.
   6 *
   7 * Copyright (C) 2009--2010 Nokia Corporation.
   8 *
   9 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
  10 */
  11
  12#include <linux/bitops.h>
  13#include <linux/slab.h>
  14#include <linux/export.h>
  15#include <media/v4l2-dev.h>
  16#include <media/v4l2-fh.h>
  17#include <media/v4l2-event.h>
  18#include <media/v4l2-ioctl.h>
  19#include <media/v4l2-mc.h>
  20
  21void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
  22{
  23        fh->vdev = vdev;
  24        /* Inherit from video_device. May be overridden by the driver. */
  25        fh->ctrl_handler = vdev->ctrl_handler;
  26        INIT_LIST_HEAD(&fh->list);
  27        set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
  28        /*
  29         * determine_valid_ioctls() does not know if struct v4l2_fh
  30         * is used by this driver, but here we do. So enable the
  31         * prio ioctls here.
  32         */
  33        set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
  34        set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
  35        fh->prio = V4L2_PRIORITY_UNSET;
  36        init_waitqueue_head(&fh->wait);
  37        INIT_LIST_HEAD(&fh->available);
  38        INIT_LIST_HEAD(&fh->subscribed);
  39        fh->sequence = -1;
  40        mutex_init(&fh->subscribe_lock);
  41}
  42EXPORT_SYMBOL_GPL(v4l2_fh_init);
  43
  44void v4l2_fh_add(struct v4l2_fh *fh)
  45{
  46        unsigned long flags;
  47
  48        v4l2_prio_open(fh->vdev->prio, &fh->prio);
  49        spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  50        list_add(&fh->list, &fh->vdev->fh_list);
  51        spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  52}
  53EXPORT_SYMBOL_GPL(v4l2_fh_add);
  54
  55int v4l2_fh_open(struct file *filp)
  56{
  57        struct video_device *vdev = video_devdata(filp);
  58        struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
  59
  60        filp->private_data = fh;
  61        if (fh == NULL)
  62                return -ENOMEM;
  63        v4l2_fh_init(fh, vdev);
  64        v4l2_fh_add(fh);
  65        return 0;
  66}
  67EXPORT_SYMBOL_GPL(v4l2_fh_open);
  68
  69void v4l2_fh_del(struct v4l2_fh *fh)
  70{
  71        unsigned long flags;
  72
  73        spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  74        list_del_init(&fh->list);
  75        spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  76        v4l2_prio_close(fh->vdev->prio, fh->prio);
  77}
  78EXPORT_SYMBOL_GPL(v4l2_fh_del);
  79
  80void v4l2_fh_exit(struct v4l2_fh *fh)
  81{
  82        if (fh->vdev == NULL)
  83                return;
  84        v4l_disable_media_source(fh->vdev);
  85        v4l2_event_unsubscribe_all(fh);
  86        mutex_destroy(&fh->subscribe_lock);
  87        fh->vdev = NULL;
  88}
  89EXPORT_SYMBOL_GPL(v4l2_fh_exit);
  90
  91int v4l2_fh_release(struct file *filp)
  92{
  93        struct v4l2_fh *fh = filp->private_data;
  94
  95        if (fh) {
  96                v4l2_fh_del(fh);
  97                v4l2_fh_exit(fh);
  98                kfree(fh);
  99                filp->private_data = NULL;
 100        }
 101        return 0;
 102}
 103EXPORT_SYMBOL_GPL(v4l2_fh_release);
 104
 105int v4l2_fh_is_singular(struct v4l2_fh *fh)
 106{
 107        unsigned long flags;
 108        int is_singular;
 109
 110        if (fh == NULL || fh->vdev == NULL)
 111                return 0;
 112        spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 113        is_singular = list_is_singular(&fh->list);
 114        spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 115        return is_singular;
 116}
 117EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);
 118