On Tue, 2009-12-22 at 18:43 +0200, Sakari Ailus wrote:
> 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);
Hi Sakari,
Disabling and restoring local interrupts to check if any events are
pending seems excessive.
Since you added an atomic_t with the number of events available in patch
5/7, why don't you just check that atomic_t here?
Regards,
Andy
> +
> +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;
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