include/media/v4l2-event.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * v4l2-event.h
   4  *
   5  * V4L2 events.
   6  *
   7  * Copyright (C) 2009--2010 Nokia Corporation.
   8  *
   9  * Contact: Sakari Ailus <sakari.ailus@iki.fi>
  10  */
  11
  12 #ifndef V4L2_EVENT_H
  13 #define V4L2_EVENT_H
  14
  15 #include <linux/types.h>
  16 #include <linux/videodev2.h>
  17 #include <linux/wait.h>
  18
  19 struct v4l2_fh;
  20 struct v4l2_subdev;
  21 struct v4l2_subscribed_event;
  22 struct video_device;
  23
  24 /**
  25  * struct v4l2_kevent - Internal kernel event struct.
  26  * @list:       List node for the v4l2_fh->available list.
  27  * @sev:        Pointer to parent v4l2_subscribed_event.
  28  * @event:      The event itself.
  29  * @ts:         The timestamp of the event.
  30  */
  31 struct v4l2_kevent {
  32         struct list_head        list;
  33         struct v4l2_subscribed_event *sev;
  34         struct v4l2_event       event;
  35         u64                     ts;
  36 };
  37
  38 /**
  39  * struct v4l2_subscribed_event_ops - Subscribed event operations.
  40  *
  41  * @add:        Optional callback, called when a new listener is added
  42  * @del:        Optional callback, called when a listener stops listening
  43  * @replace:    Optional callback that can replace event 'old' with event 'new'.
  44  * @merge:      Optional callback that can merge event 'old' into event 'new'.
  45  */
  46 struct v4l2_subscribed_event_ops {
  47         int  (*add)(struct v4l2_subscribed_event *sev, unsigned int elems);
  48         void (*del)(struct v4l2_subscribed_event *sev);
  49         void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
  50         void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
  51 };
  52
  53 /**
  54  * struct v4l2_subscribed_event - Internal struct representing a subscribed
  55  *              event.
  56  *
  57  * @list:       List node for the v4l2_fh->subscribed list.
  58  * @type:       Event type.
  59  * @id: Associated object ID (e.g. control ID). 0 if there isn't any.
  60  * @flags:      Copy of v4l2_event_subscription->flags.
  61  * @fh: Filehandle that subscribed to this event.
  62  * @node:       List node that hooks into the object's event list
  63  *              (if there is one).
  64  * @ops:        v4l2_subscribed_event_ops
  65  * @elems:      The number of elements in the events array.
  66  * @first:      The index of the events containing the oldest available event.
  67  * @in_use:     The number of queued events.
  68  * @events:     An array of @elems events.
  69  */
  70 struct v4l2_subscribed_event {
  71         struct list_head        list;
  72         u32                     type;
  73         u32                     id;
  74         u32                     flags;
  75         struct v4l2_fh          *fh;
  76         struct list_head        node;
  77         const struct v4l2_subscribed_event_ops *ops;
  78         unsigned int            elems;
  79         unsigned int            first;
  80         unsigned int            in_use;
  81         struct v4l2_kevent      events[];
  82 };
  83
  84 /**
  85  * v4l2_event_dequeue - Dequeue events from video device.
  86  *
  87  * @fh: pointer to struct v4l2_fh
  88  * @event: pointer to struct v4l2_event
  89  * @nonblocking: if not zero, waits for an event to arrive
  90  */
  91 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
  92                        int nonblocking);
  93
  94 /**
  95  * v4l2_event_queue - Queue events to video device.
  96  *
  97  * @vdev: pointer to &struct video_device
  98  * @ev: pointer to &struct v4l2_event
  99  *
 100  * The event will be queued for all &struct v4l2_fh file handlers.
 101  *
 102  * .. note::
 103  *    The driver's only responsibility is to fill in the type and the data
 104  *    fields.The other fields will be filled in by  V4L2.
 105  */
 106 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
 107
 108 /**
 109  * v4l2_event_queue_fh - Queue events to video device.
 110  *
 111  * @fh: pointer to &struct v4l2_fh
 112  * @ev: pointer to &struct v4l2_event
 113  *
 114  *
 115  * The event will be queued only for the specified &struct v4l2_fh file handler.
 116  *
 117  * .. note::
 118  *    The driver's only responsibility is to fill in the type and the data
 119  *    fields.The other fields will be filled in by  V4L2.
 120  */
 121 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
 122
 123 /**
 124  * v4l2_event_pending - Check if an event is available
 125  *
 126  * @fh: pointer to &struct v4l2_fh
 127  *
 128  * Returns the number of pending events.
 129  */
 130 int v4l2_event_pending(struct v4l2_fh *fh);
 131
 132 /**
 133  * v4l2_event_subscribe - Subscribes to an event
 134  *
 135  * @fh: pointer to &struct v4l2_fh
 136  * @sub: pointer to &struct v4l2_event_subscription
 137  * @elems: size of the events queue
 138  * @ops: pointer to &v4l2_subscribed_event_ops
 139  *
 140  * .. note::
 141  *
 142  *    if @elems is zero, the framework will fill in a default value,
 143  *    with is currently 1 element.
 144  */
 145 int v4l2_event_subscribe(struct v4l2_fh *fh,
 146                          const struct v4l2_event_subscription *sub,
 147                          unsigned int elems,
 148                          const struct v4l2_subscribed_event_ops *ops);
 149 /**
 150  * v4l2_event_unsubscribe - Unsubscribes to an event
 151  *
 152  * @fh: pointer to &struct v4l2_fh
 153  * @sub: pointer to &struct v4l2_event_subscription
 154  */
 155 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 156                            const struct v4l2_event_subscription *sub);
 157 /**
 158  * v4l2_event_unsubscribe_all - Unsubscribes to all events
 159  *
 160  * @fh: pointer to &struct v4l2_fh
 161  */
 162 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
 163
 164 /**
 165  * v4l2_event_subdev_unsubscribe - Subdev variant of v4l2_event_unsubscribe()
 166  *
 167  * @sd: pointer to &struct v4l2_subdev
 168  * @fh: pointer to &struct v4l2_fh
 169  * @sub: pointer to &struct v4l2_event_subscription
 170  *
 171  * .. note::
 172  *
 173  *      This function should be used for the &struct v4l2_subdev_core_ops
 174  *      %unsubscribe_event field.
 175  */
 176 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd,
 177                                   struct v4l2_fh *fh,
 178                                   struct v4l2_event_subscription *sub);
 179 /**
 180  * v4l2_src_change_event_subscribe - helper function that calls
 181  *      v4l2_event_subscribe() if the event is %V4L2_EVENT_SOURCE_CHANGE.
 182  *
 183  * @fh: pointer to struct v4l2_fh
 184  * @sub: pointer to &struct v4l2_event_subscription
 185  */
 186 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
 187                                     const struct v4l2_event_subscription *sub);
 188 /**
 189  * v4l2_src_change_event_subdev_subscribe - Variant of v4l2_event_subscribe(),
 190  *      meant to subscribe only events of the type %V4L2_EVENT_SOURCE_CHANGE.
 191  *
 192  * @sd: pointer to &struct v4l2_subdev
 193  * @fh: pointer to &struct v4l2_fh
 194  * @sub: pointer to &struct v4l2_event_subscription
 195  */
 196 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
 197                                            struct v4l2_fh *fh,
 198                                            struct v4l2_event_subscription *sub);
 199 #endif /* V4L2_EVENT_H */