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  */
  38 struct v4l2_kevent {
  39         struct list_head        list;
  40         struct v4l2_subscribed_event *sev;
  41         struct v4l2_event       event;
  42 };
  43
  44 /**
  45  * struct v4l2_subscribed_event_ops - Subscribed event operations.
  46  *
  47  * @add:        Optional callback, called when a new listener is added
  48  * @del:        Optional callback, called when a listener stops listening
  49  * @replace:    Optional callback that can replace event 'old' with event 'new'.
  50  * @merge:      Optional callback that can merge event 'old' into event 'new'.
  51  */
  52 struct v4l2_subscribed_event_ops {
  53         int  (*add)(struct v4l2_subscribed_event *sev, unsigned int elems);
  54         void (*del)(struct v4l2_subscribed_event *sev);
  55         void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
  56         void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
  57 };
  58
  59 /**
  60  * struct v4l2_subscribed_event - Internal struct representing a subscribed
  61  *              event.
  62  *
  63  * @list:       List node for the v4l2_fh->subscribed list.
  64  * @type:       Event type.
  65  * @id: Associated object ID (e.g. control ID). 0 if there isn't any.
  66  * @flags:      Copy of v4l2_event_subscription->flags.
  67  * @fh: Filehandle that subscribed to this event.
  68  * @node:       List node that hooks into the object's event list
  69  *              (if there is one).
  70  * @ops:        v4l2_subscribed_event_ops
  71  * @elems:      The number of elements in the events array.
  72  * @first:      The index of the events containing the oldest available event.
  73  * @in_use:     The number of queued events.
  74  * @events:     An array of @elems events.
  75  */
  76 struct v4l2_subscribed_event {
  77         struct list_head        list;
  78         u32                     type;
  79         u32                     id;
  80         u32                     flags;
  81         struct v4l2_fh          *fh;
  82         struct list_head        node;
  83         const struct v4l2_subscribed_event_ops *ops;
  84         unsigned int            elems;
  85         unsigned int            first;
  86         unsigned int            in_use;
  87         struct v4l2_kevent      events[];
  88 };
  89
  90 /**
  91  * v4l2_event_dequeue - Dequeue events from video device.
  92  *
  93  * @fh: pointer to struct v4l2_fh
  94  * @event: pointer to struct v4l2_event
  95  * @nonblocking: if not zero, waits for an event to arrive
  96  */
  97 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
  98                        int nonblocking);
  99
 100 /**
 101  * v4l2_event_queue - Queue events to video device.
 102  *
 103  * @vdev: pointer to &struct video_device
 104  * @ev: pointer to &struct v4l2_event
 105  *
 106  * The event will be queued for all &struct v4l2_fh file handlers.
 107  *
 108  * .. note::
 109  *    The driver's only responsibility is to fill in the type and the data
 110  *    fields.The other fields will be filled in by  V4L2.
 111  */
 112 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
 113
 114 /**
 115  * v4l2_event_queue_fh - Queue events to video device.
 116  *
 117  * @fh: pointer to &struct v4l2_fh
 118  * @ev: pointer to &struct v4l2_event
 119  *
 120  *
 121  * The event will be queued only for the specified &struct v4l2_fh file handler.
 122  *
 123  * .. note::
 124  *    The driver's only responsibility is to fill in the type and the data
 125  *    fields.The other fields will be filled in by  V4L2.
 126  */
 127 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
 128
 129 /**
 130  * v4l2_event_pending - Check if an event is available
 131  *
 132  * @fh: pointer to &struct v4l2_fh
 133  *
 134  * Returns the number of pending events.
 135  */
 136 int v4l2_event_pending(struct v4l2_fh *fh);
 137
 138 /**
 139  * v4l2_event_subscribe - Subscribes to an event
 140  *
 141  * @fh: pointer to &struct v4l2_fh
 142  * @sub: pointer to &struct v4l2_event_subscription
 143  * @elems: size of the events queue
 144  * @ops: pointer to &v4l2_subscribed_event_ops
 145  *
 146  * .. note::
 147  *
 148  *    if @elems is zero, the framework will fill in a default value,
 149  *    with is currently 1 element.
 150  */
 151 int v4l2_event_subscribe(struct v4l2_fh *fh,
 152                          const struct v4l2_event_subscription *sub,
 153                          unsigned int elems,
 154                          const struct v4l2_subscribed_event_ops *ops);
 155 /**
 156  * v4l2_event_unsubscribe - Unsubscribes to an event
 157  *
 158  * @fh: pointer to &struct v4l2_fh
 159  * @sub: pointer to &struct v4l2_event_subscription
 160  */
 161 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 162                            const struct v4l2_event_subscription *sub);
 163 /**
 164  * v4l2_event_unsubscribe_all - Unsubscribes to all events
 165  *
 166  * @fh: pointer to &struct v4l2_fh
 167  */
 168 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
 169
 170 /**
 171  * v4l2_event_subdev_unsubscribe - Subdev variant of v4l2_event_unsubscribe()
 172  *
 173  * @sd: pointer to &struct v4l2_subdev
 174  * @fh: pointer to &struct v4l2_fh
 175  * @sub: pointer to &struct v4l2_event_subscription
 176  *
 177  * .. note::
 178  *
 179  *      This function should be used for the &struct v4l2_subdev_core_ops
 180  *      %unsubscribe_event field.
 181  */
 182 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd,
 183                                   struct v4l2_fh *fh,
 184                                   struct v4l2_event_subscription *sub);
 185 /**
 186  * v4l2_src_change_event_subscribe - helper function that calls
 187  *      v4l2_event_subscribe() if the event is %V4L2_EVENT_SOURCE_CHANGE.
 188  *
 189  * @fh: pointer to struct v4l2_fh
 190  * @sub: pointer to &struct v4l2_event_subscription
 191  */
 192 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
 193                                     const struct v4l2_event_subscription *sub);
 194 /**
 195  * v4l2_src_change_event_subdev_subscribe - Variant of v4l2_event_subscribe(),
 196  *      meant to subscribe only events of the type %V4L2_EVENT_SOURCE_CHANGE.
 197  *
 198  * @sd: pointer to &struct v4l2_subdev
 199  * @fh: pointer to &struct v4l2_fh
 200  * @sub: pointer to &struct v4l2_event_subscription
 201  */
 202 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
 203                                            struct v4l2_fh *fh,
 204                                            struct v4l2_event_subscription *sub);
 205 #endif /* V4L2_EVENT_H */