Add event handling backend to V4L2. The backend handles event subscription
and delivery to file handles. Event subscriptions are based on file handle.
Events may be delivered to all subscribed file handles on a device
independent of where they originate from.
Signed-off-by: Sakari Ailus <sakari.ai...@maxwell.research.nokia.com>
---
drivers/media/video/Makefile | 3 +-
drivers/media/video/v4l2-dev.c | 21 +++-
drivers/media/video/v4l2-event.c | 254 ++++++++++++++++++++++++++++++++++++++
drivers/media/video/v4l2-fh.c | 4 +
include/media/v4l2-event.h | 65 ++++++++++
include/media/v4l2-fh.h | 3 +
6 files changed, 346 insertions(+), 4 deletions(-)
create mode 100644 drivers/media/video/v4l2-event.c
create mode 100644 include/media/v4l2-event.h
diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index 1947146..dd6a853 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -10,7 +10,8 @@ stkwebcam-objs := stk-webcam.o stk-sensor.o
omap2cam-objs := omap24xxcam.o omap24xxcam-dma.o
-videodev-objs := v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o
+videodev-objs := v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
+ v4l2-event.o
# V4L2 core modules
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 15b2ac8..6d25297 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -613,22 +613,36 @@ static int __init videodev_init(void)
dev_t dev = MKDEV(VIDEO_MAJOR, 0);
int ret;
+ ret = v4l2_event_init();
+ if (ret < 0) {
+ printk(KERN_WARNING "videodev: unable to initialise events\n");
+ return ret;
+ }
+
printk(KERN_INFO "Linux video capture interface: v2.00\n");
ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
if (ret < 0) {
printk(KERN_WARNING "videodev: unable to get major %d\n",
VIDEO_MAJOR);
- return ret;
+ goto out_register_chrdev_region;
}
ret = class_register(&video_class);
if (ret < 0) {
- unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
printk(KERN_WARNING "video_dev: class_register failed\n");
- return -EIO;
+ ret = -EIO;
+ goto out_class_register;
}
return 0;
+
+out_class_register:
+ unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
+
+out_register_chrdev_region:
+ v4l2_event_exit();
+
+ return ret;
}
static void __exit videodev_exit(void)
@@ -637,6 +651,7 @@ static void __exit videodev_exit(void)
class_unregister(&video_class);
unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
+ v4l2_event_exit();
}
module_init(videodev_init)
diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
new file mode 100644
index 0000000..9fc0c81
--- /dev/null
+++ b/drivers/media/video/v4l2-event.c
@@ -0,0 +1,254 @@
+/*
+ * drivers/media/video/v4l2-event.c
+ *
+ * V4L2 events.
+ *
+ * Copyright (C) 2009 Nokia Corporation.
+ *
+ * Contact: Sakari Ailus <sakari.ai...@maxwell.research.nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <media/v4l2-dev.h>
+#include <media/v4l2-event.h>
+
+#include <linux/sched.h>
+
+static struct kmem_cache *event_kmem;
+
+int v4l2_event_init(void)
+{
+ event_kmem = kmem_cache_create("event_kmem",
+ sizeof(struct _v4l2_event), 0,
+ SLAB_HWCACHE_ALIGN,
+ NULL);
+
+ if (!event_kmem)
+ return -ENOMEM;
+
+ return 0;
+}
+
+void v4l2_event_exit(void)
+{
+ kmem_cache_destroy(event_kmem);
+}
+
+void v4l2_event_init_fh(struct v4l2_fh *fh)
+{
+ struct v4l2_events *events = &fh->events;
+
+ init_waitqueue_head(&events->wait);
+ spin_lock_init(&events->lock);
+
+ INIT_LIST_HEAD(&events->available);
+ INIT_LIST_HEAD(&events->subscribed);
+}
+EXPORT_SYMBOL_GPL(v4l2_event_init_fh);
+
+void v4l2_event_exit_fh(struct v4l2_fh *fh)
+{
+ struct v4l2_events *events = &fh->events;
+
+ while (!list_empty(&events->available)) {
+ struct _v4l2_event *ev;
+
+ ev = list_entry(events->available.next,
+ struct _v4l2_event, list);
+
+ list_del(&ev->list);
+
+ kmem_cache_free(event_kmem, ev);
+ }
+
+ while (!list_empty(&events->subscribed)) {
+ struct v4l2_subscribed_event *sub;
+
+ sub = list_entry(events->subscribed.next,
+ struct v4l2_subscribed_event, list);
+
+ list_del(&sub->list);
+
+ kfree(sub);
+ }
+}
+EXPORT_SYMBOL_GPL(v4l2_event_exit_fh);
+
+int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
+{
+ struct v4l2_events *events = &fh->events;
+ struct _v4l2_event *ev;
+ unsigned long flags;
+
+ spin_lock_irqsave(&events->lock, flags);
+
+ if (list_empty(&events->available)) {
+ spin_unlock_irqrestore(&events->lock, flags);
+ return -ENOENT;
+ }
+
+ ev = list_first_entry(&events->available, struct _v4l2_event, list);
+ list_del(&ev->list);
+
+ ev->event.count = !list_empty(&events->available);
+
+ spin_unlock_irqrestore(&events->lock, flags);
+
+ memcpy(event, &ev->event, sizeof(ev->event));
+
+ kmem_cache_free(event_kmem, ev);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
+
+static struct v4l2_subscribed_event *__v4l2_event_subscribed(
+ struct v4l2_fh *fh, u32 type)
+{
+ struct v4l2_events *events = &fh->events;
+ struct v4l2_subscribed_event *ev;
+
+ list_for_each_entry(ev, &events->subscribed, list) {
+ if (ev->type == type)
+ return ev;
+ }
+
+ return NULL;
+}
+
+struct v4l2_subscribed_event *v4l2_event_subscribed(
+ struct v4l2_fh *fh, u32 type)
+{
+ struct v4l2_events *events = &fh->events;
+ struct v4l2_subscribed_event *ev;
+ unsigned long flags;
+
+ spin_lock_irqsave(&events->lock, flags);
+
+ ev = __v4l2_event_subscribed(fh, type);
+
+ spin_unlock_irqrestore(&events->lock, flags);
+
+ return ev;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_subscribed);
+
+void v4l2_event_queue(struct video_device *vdev, struct v4l2_event *ev)
+{
+ struct v4l2_fh *fh;
+ unsigned long flags;
+
+ spin_lock_irqsave(&vdev->fh_lock, flags);
+
+ list_for_each_entry(fh, &vdev->fh, list) {
+ struct _v4l2_event *_ev;
+
+ if (!v4l2_event_subscribed(fh, ev->type))
+ continue;
+
+ _ev = kmem_cache_alloc(event_kmem, GFP_ATOMIC);
+ if (!_ev)
+ continue;
+
+ _ev->event = *ev;
+
+ spin_lock(&fh->events.lock);
+ list_add_tail(&_ev->list, &fh->events.available);
+ spin_unlock(&fh->events.lock);
+
+ wake_up_all(&fh->events.wait);
+ }
+
+ spin_unlock_irqrestore(&vdev->fh_lock, flags);
+}
+EXPORT_SYMBOL_GPL(v4l2_event_queue);
+
+int v4l2_event_pending(struct v4l2_fh *fh)
+{
+ struct v4l2_events *events = &fh->events;
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&events->lock, flags);
+ ret = !list_empty(&events->available);
+ spin_unlock_irqrestore(&events->lock, flags);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_pending);
+
+int v4l2_event_subscribe(struct v4l2_fh *fh,
+ struct v4l2_event_subscription *sub)
+{
+ struct v4l2_events *events = &fh->events;
+ struct v4l2_subscribed_event *ev;
+ unsigned long flags;
+ int ret = 0;
+
+ /* Allow subscribing to valid events only. */
+ if (sub->type < V4L2_EVENT_PRIVATE_START)
+ switch (sub->type) {
+ case V4L2_EVENT_ALL:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ ev = kmalloc(sizeof(*ev), GFP_KERNEL);
+ if (!ev)
+ return -ENOMEM;
+
+ spin_lock_irqsave(&events->lock, flags);
+
+ if (__v4l2_event_subscribed(fh, sub->type) != NULL) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ INIT_LIST_HEAD(&ev->list);
+ ev->type = sub->type;
+
+ list_add(&ev->list, &events->subscribed);
+
+out:
+ spin_unlock_irqrestore(&events->lock, flags);
+
+ if (ret)
+ kfree(ev);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
+
+int v4l2_event_unsubscribe(struct v4l2_fh *fh,
+ struct v4l2_event_subscription *sub)
+{
+ struct v4l2_events *events = &fh->events;
+ struct v4l2_subscribed_event *ev;
+ unsigned long flags;
+
+ spin_lock_irqsave(&events->lock, flags);
+
+ ev = __v4l2_event_subscribed(fh, sub->type);
+
+ if (ev != NULL)
+ list_del(&ev->list);
+
+ spin_unlock_irqrestore(&events->lock, flags);
+
+ return ev == NULL;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
diff --git a/drivers/media/video/v4l2-fh.c b/drivers/media/video/v4l2-fh.c
index 406e4ac..2b25ec9 100644
--- a/drivers/media/video/v4l2-fh.c
+++ b/drivers/media/video/v4l2-fh.c
@@ -32,6 +32,8 @@ int v4l2_fh_add(struct video_device *vdev, struct v4l2_fh *fh)
{
unsigned long flags;
+ v4l2_event_init_fh(fh);
+
spin_lock_irqsave(&vdev->fh_lock, flags);
list_add(&fh->list, &vdev->fh);
spin_unlock_irqrestore(&vdev->fh_lock, flags);
@@ -44,6 +46,8 @@ void v4l2_fh_del(struct video_device *vdev, struct v4l2_fh
*fh)
{
unsigned long flags;
+ v4l2_event_exit_fh(fh);
+
spin_lock_irqsave(&vdev->fh_lock, flags);
list_del(&fh->list);
spin_unlock_irqrestore(&vdev->fh_lock, flags);
diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
new file mode 100644
index 0000000..b11de92
--- /dev/null
+++ b/include/media/v4l2-event.h
@@ -0,0 +1,65 @@
+/*
+ * include/media/v4l2-event.h
+ *
+ * V4L2 events.
+ *
+ * Copyright (C) 2009 Nokia Corporation.
+ *
+ * Contact: Sakari Ailus <sakari.ai...@maxwell.research.nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#ifndef V4L2_EVENT_H
+#define V4L2_EVENT_H
+
+#include <linux/types.h>
+#include <linux/videodev2.h>
+
+struct v4l2_fh;
+struct video_device;
+
+struct _v4l2_event {
+ struct list_head list;
+ struct v4l2_event event;
+};
+
+struct v4l2_events {
+ spinlock_t lock; /* Protect everything here. */
+ struct list_head available;
+ wait_queue_head_t wait;
+ struct list_head subscribed; /* Subscribed events. */
+};
+
+struct v4l2_subscribed_event {
+ struct list_head list;
+ u32 type;
+};
+
+int v4l2_event_init(void);
+void v4l2_event_exit(void);
+void v4l2_event_init_fh(struct v4l2_fh *fh);
+void v4l2_event_exit_fh(struct v4l2_fh *fh);
+int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event);
+struct v4l2_subscribed_event *v4l2_event_subscribed(
+ struct v4l2_fh *fh, u32 type);
+void v4l2_event_queue(struct video_device *vdev, struct v4l2_event *ev);
+int v4l2_event_pending(struct v4l2_fh *fh);
+int v4l2_event_subscribe(struct v4l2_fh *fh,
+ struct v4l2_event_subscription *sub);
+int v4l2_event_unsubscribe(struct v4l2_fh *fh,
+ struct v4l2_event_subscription *sub);
+
+#endif /* V4L2_EVENT_H */
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h
index 1efa916..c15bd13 100644
--- a/include/media/v4l2-fh.h
+++ b/include/media/v4l2-fh.h
@@ -28,8 +28,11 @@
#include <linux/types.h>
#include <linux/list.h>
+#include <media/v4l2-event.h>
+
struct v4l2_fh {
struct list_head list;
+ struct v4l2_events events; /* events, pending and subscribed */
};
struct video_device;
--
1.5.6.5
