[media] media: Links setup

Create the following ioctl and implement it at the media device level to
setup links.

- MEDIA_IOC_SETUP_LINK: Modify the properties of a given link

The only property that can currently be modified is the ENABLED link
flag to enable/disable a link. Links marked with the IMMUTABLE link flag
can not be enabled or disabled.

Enabling or disabling a link has effects on entities' use count. Those
changes are automatically propagated through the graph.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Stanimir Varbanov <svarbanov@mm-sol.com>
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 200 insertions, 0 deletions

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 648a9d892ac1..16b70b4412f7 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -172,6 +172,44 @@ static long media_device_enum_links(struct media_device *mdev,
         return 0;
 }
 
+static long media_device_setup_link(struct media_device *mdev,
+                                    struct media_link_desc __user *_ulink)
+{
+        struct media_link *link = NULL;
+        struct media_link_desc ulink;
+        struct media_entity *source;
+        struct media_entity *sink;
+        int ret;
+
+        if (copy_from_user(&ulink, _ulink, sizeof(ulink)))
+                return -EFAULT;
+
+        /* Find the source and sink entities and link.
+         */
+        source = find_entity(mdev, ulink.source.entity);
+        sink = find_entity(mdev, ulink.sink.entity);
+
+        if (source == NULL || sink == NULL)
+                return -EINVAL;
+
+        if (ulink.source.index >= source->num_pads ||
+            ulink.sink.index >= sink->num_pads)
+                return -EINVAL;
+
+        link = media_entity_find_link(&source->pads[ulink.source.index],
+                                      &sink->pads[ulink.sink.index]);
+        if (link == NULL)
+                return -EINVAL;
+
+        /* Setup the link on both entities. */
+        ret = __media_entity_setup_link(link, ulink.flags);
+
+        if (copy_to_user(_ulink, &ulink, sizeof(ulink)))
+                return -EFAULT;
+
+        return ret;
+}
+
 static long media_device_ioctl(struct file *filp, unsigned int cmd,
                                unsigned long arg)
 {
@@ -197,6 +235,13 @@ static long media_device_ioctl(struct file *filp, unsigned int cmd,
                 mutex_unlock(&dev->graph_mutex);
                 break;
 
+        case MEDIA_IOC_SETUP_LINK:
+                mutex_lock(&dev->graph_mutex);
+                ret = media_device_setup_link(dev,
+                                (struct media_link_desc __user *)arg);
+                mutex_unlock(&dev->graph_mutex);
+                break;
+
         default:
                 ret = -ENOIOCTLCMD;
         }
diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index 3e7e2d569cec..6795c920d460 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -306,3 +306,158 @@ media_entity_create_link(struct media_entity *source, u16 source_pad,
         return 0;
 }
 EXPORT_SYMBOL_GPL(media_entity_create_link);
+
+static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
+{
+        const u32 mask = MEDIA_LNK_FL_ENABLED;
+        int ret;
+
+        /* Notify both entities. */
+        ret = media_entity_call(link->source->entity, link_setup,
+                                link->source, link->sink, flags);
+        if (ret < 0 && ret != -ENOIOCTLCMD)
+                return ret;
+
+        ret = media_entity_call(link->sink->entity, link_setup,
+                                link->sink, link->source, flags);
+        if (ret < 0 && ret != -ENOIOCTLCMD) {
+                media_entity_call(link->source->entity, link_setup,
+                                  link->source, link->sink, link->flags);
+                return ret;
+        }
+
+        link->flags = (link->flags & ~mask) | (flags & mask);
+        link->reverse->flags = link->flags;
+
+        return 0;
+}
+
+/**
+ * __media_entity_setup_link - Configure a media link
+ * @link: The link being configured
+ * @flags: Link configuration flags
+ *
+ * The bulk of link setup is handled by the two entities connected through the
+ * link. This function notifies both entities of the link configuration change.
+ *
+ * If the link is immutable or if the current and new configuration are
+ * identical, return immediately.
+ *
+ * The user is expected to hold link->source->parent->mutex. If not,
+ * media_entity_setup_link() should be used instead.
+ */
+int __media_entity_setup_link(struct media_link *link, u32 flags)
+{
+        struct media_device *mdev;
+        struct media_entity *source, *sink;
+        int ret = -EBUSY;
+
+        if (link == NULL)
+                return -EINVAL;
+
+        if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
+                return link->flags == flags ? 0 : -EINVAL;
+
+        if (link->flags == flags)
+                return 0;
+
+        source = link->source->entity;
+        sink = link->sink->entity;
+
+        mdev = source->parent;
+
+        if ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify) {
+                ret = mdev->link_notify(link->source, link->sink,
+                                        MEDIA_LNK_FL_ENABLED);
+                if (ret < 0)
+                        return ret;
+        }
+
+        ret = __media_entity_setup_link_notify(link, flags);
+        if (ret < 0)
+                goto err;
+
+        if (!(flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify)
+                mdev->link_notify(link->source, link->sink, 0);
+
+        return 0;
+
+err:
+        if ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify)
+                mdev->link_notify(link->source, link->sink, 0);
+
+        return ret;
+}
+
+int media_entity_setup_link(struct media_link *link, u32 flags)
+{
+        int ret;
+
+        mutex_lock(&link->source->entity->parent->graph_mutex);
+        ret = __media_entity_setup_link(link, flags);
+        mutex_unlock(&link->source->entity->parent->graph_mutex);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(media_entity_setup_link);
+
+/**
+ * media_entity_find_link - Find a link between two pads
+ * @source: Source pad
+ * @sink: Sink pad
+ *
+ * Return a pointer to the link between the two entities. If no such link
+ * exists, return NULL.
+ */
+struct media_link *
+media_entity_find_link(struct media_pad *source, struct media_pad *sink)
+{
+        struct media_link *link;
+        unsigned int i;
+
+        for (i = 0; i < source->entity->num_links; ++i) {
+                link = &source->entity->links[i];
+
+                if (link->source->entity == source->entity &&
+                    link->source->index == source->index &&
+                    link->sink->entity == sink->entity &&
+                    link->sink->index == sink->index)
+                        return link;
+        }
+
+        return NULL;
+}
+EXPORT_SYMBOL_GPL(media_entity_find_link);
+
+/**
+ * media_entity_remote_source - Find the source pad at the remote end of a link
+ * @pad: Sink pad at the local end of the link
+ *
+ * Search for a remote source pad connected to the given sink pad by iterating
+ * over all links originating or terminating at that pad until an enabled link
+ * is found.
+ *
+ * Return a pointer to the pad at the remote end of the first found enabled
+ * link, or NULL if no enabled link has been found.
+ */
+struct media_pad *media_entity_remote_source(struct media_pad *pad)
+{
+        unsigned int i;
+
+        for (i = 0; i < pad->entity->num_links; i++) {
+                struct media_link *link = &pad->entity->links[i];
+
+                if (!(link->flags & MEDIA_LNK_FL_ENABLED))
+                        continue;
+
+                if (link->source == pad)
+                        return link->sink;
+
+                if (link->sink == pad)
+                        return link->source;
+        }
+
+        return NULL;
+
+}
+EXPORT_SYMBOL_GPL(media_entity_remote_source);