include/media/v4l2-event.h

   1 /*
   2  * v4l2-event.h
   3  *
   4  * V4L2 events.
   5  *
   6  * Copyright (C) 2009--2010 Nokia Corporation.
   7  *
   8  * Contact: Sakari Ailus <sakari.ailus@iki.fi>
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * version 2 as published by the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope that it will be useful, but
  15  * WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * General Public License for more details.
  18  */
  19
  20 #ifndef V4L2_EVENT_H
  21 #define V4L2_EVENT_H
  22
  23 #include <linux/types.h>
  24 #include <linux/videodev2.h>
  25 #include <linux/wait.h>
  26
  27 struct v4l2_fh;
  28 struct v4l2_subdev;
  29 struct v4l2_subscribed_event;
  30 struct video_device;
  31
  32 /**
  33  * struct v4l2_kevent - Internal kernel event struct.
  34  * @list:       List node for the v4l2_fh->available list.
  35  * @sev:        Pointer to parent v4l2_subscribed_event.
  36  * @event:      The event itself.
  37  * @ts:         The timestamp of the event.
  38  */
  39 struct v4l2_kevent {
  40         struct list_head        list;
  41         struct v4l2_subscribed_event *sev;
  42         struct v4l2_event       event;
  43         u64                     ts;
  44 };
  45
  46 /**
  47  * struct v4l2_subscribed_event_ops - Subscribed event operations.
  48  *
  49  * @add:        Optional callback, called when a new listener is added
  50  * @del:        Optional callback, called when a listener stops listening
  51  * @replace:    Optional callback that can replace event 'old' with event 'new'.
  52  * @merge:      Optional callback that can merge event 'old' into event 'new'.
  53  */
  54 struct v4l2_subscribed_event_ops {
  55         int  (*add)(struct v4l2_subscribed_event *sev, unsigned int elems);
  56         void (*del)(struct v4l2_subscribed_event *sev);
  57         void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
  58         void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
  59 };
  60
  61 /**
  62  * struct v4l2_subscribed_event - Internal struct representing a subscribed
  63  *              event.
  64  *
  65  * @list:       List node for the v4l2_fh->subscribed list.
  66  * @type:       Event type.
  67  * @id: Associated object ID (e.g. control ID). 0 if there isn't any.
  68  * @flags:      Copy of v4l2_event_subscription->flags.
  69  * @fh: Filehandle that subscribed to this event.
  70  * @node:       List node that hooks into the object's event list
  71  *              (if there is one).
  72  * @ops:        v4l2_subscribed_event_ops
  73  * @elems:      The number of elements in the events array.
  74  * @first:      The index of the events containing the oldest available event.
  75  * @in_use:     The number of queued events.
  76  * @events:     An array of @elems events.
  77  */
  78 struct v4l2_subscribed_event {
  79         struct list_head        list;
  80         u32                     type;
  81         u32                     id;
  82         u32                     flags;
  83         struct v4l2_fh          *fh;
  84         struct list_head        node;
  85         const struct v4l2_subscribed_event_ops *ops;
  86         unsigned int            elems;
  87         unsigned int            first;
  88         unsigned int            in_use;
  89         struct v4l2_kevent      events[];
  90 };
  91
  92 /**
  93  * v4l2_event_dequeue - Dequeue events from video device.
  94  *
  95  * @fh: pointer to struct v4l2_fh
  96  * @event: pointer to struct v4l2_event
  97  * @nonblocking: if not zero, waits for an event to arrive
  98  */
  99 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
 100                        int nonblocking);
 101
 102 /**
 103  * v4l2_event_queue - Queue events to video device.
 104  *
 105  * @vdev: pointer to &struct video_device
 106  * @ev: pointer to &struct v4l2_event
 107  *
 108  * The event will be queued for all &struct v4l2_fh file handlers.
 109  *
 110  * .. note::
 111  *    The driver's only responsibility is to fill in the type and the data
 112  *    fields.The other fields will be filled in by  V4L2.
 113  */
 114 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
 115
 116 /**
 117  * v4l2_event_queue_fh - Queue events to video device.
 118  *
 119  * @fh: pointer to &struct v4l2_fh
 120  * @ev: pointer to &struct v4l2_event
 121  *
 122  *
 123  * The event will be queued only for the specified &struct v4l2_fh file handler.
 124  *
 125  * .. note::
 126  *    The driver's only responsibility is to fill in the type and the data
 127  *    fields.The other fields will be filled in by  V4L2.
 128  */
 129 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
 130
 131 /**
 132  * v4l2_event_pending - Check if an event is available
 133  *
 134  * @fh: pointer to &struct v4l2_fh
 135  *
 136  * Returns the number of pending events.
 137  */
 138 int v4l2_event_pending(struct v4l2_fh *fh);
 139
 140 /**
 141  * v4l2_event_subscribe - Subscribes to an event
 142  *
 143  * @fh: pointer to &struct v4l2_fh
 144  * @sub: pointer to &struct v4l2_event_subscription
 145  * @elems: size of the events queue
 146  * @ops: pointer to &v4l2_subscribed_event_ops
 147  *
 148  * .. note::
 149  *
 150  *    if @elems is zero, the framework will fill in a default value,
 151  *    with is currently 1 element.
 152  */
 153 int v4l2_event_subscribe(struct v4l2_fh *fh,
 154                          const struct v4l2_event_subscription *sub,
 155                          unsigned int elems,
 156                          const struct v4l2_subscribed_event_ops *ops);
 157 /**
 158  * v4l2_event_unsubscribe - Unsubscribes to an event
 159  *
 160  * @fh: pointer to &struct v4l2_fh
 161  * @sub: pointer to &struct v4l2_event_subscription
 162  */
 163 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 164                            const struct v4l2_event_subscription *sub);
 165 /**
 166  * v4l2_event_unsubscribe_all - Unsubscribes to all events
 167  *
 168  * @fh: pointer to &struct v4l2_fh
 169  */
 170 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
 171
 172 /**
 173  * v4l2_event_subdev_unsubscribe - Subdev variant of v4l2_event_unsubscribe()
 174  *
 175  * @sd: pointer to &struct v4l2_subdev
 176  * @fh: pointer to &struct v4l2_fh
 177  * @sub: pointer to &struct v4l2_event_subscription
 178  *
 179  * .. note::
 180  *
 181  *      This function should be used for the &struct v4l2_subdev_core_ops
 182  *      %unsubscribe_event field.
 183  */
 184 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd,
 185                                   struct v4l2_fh *fh,
 186                                   struct v4l2_event_subscription *sub);
 187 /**
 188  * v4l2_src_change_event_subscribe - helper function that calls
 189  *      v4l2_event_subscribe() if the event is %V4L2_EVENT_SOURCE_CHANGE.
 190  *
 191  * @fh: pointer to struct v4l2_fh
 192  * @sub: pointer to &struct v4l2_event_subscription
 193  */
 194 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
 195                                     const struct v4l2_event_subscription *sub);
 196 /**
 197  * v4l2_src_change_event_subdev_subscribe - Variant of v4l2_event_subscribe(),
 198  *      meant to subscribe only events of the type %V4L2_EVENT_SOURCE_CHANGE.
 199  *
 200  * @sd: pointer to &struct v4l2_subdev
 201  * @fh: pointer to &struct v4l2_fh
 202  * @sub: pointer to &struct v4l2_event_subscription
 203  */
 204 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
 205                                            struct v4l2_fh *fh,
 206                                            struct v4l2_event_subscription *sub);
 207 #endif /* V4L2_EVENT_H */