1 files changed, 1035 insertions, 0 deletions

diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
new file mode 100644
index 000000000..3498551e6
--- /dev/null
+++ b/drivers/media/media-entity.c
@@ -0,0 +1,1035 @@
+/*
+ * Media entity
+ *
+ * Copyright (C) 2010 Nokia Corporation
+ *
+ * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+ *	     Sakari Ailus <sakari.ailus@iki.fi>
+ *
+ * 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.
+ */
+
+#include <linux/bitmap.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <media/media-entity.h>
+#include <media/media-device.h>
+
+static inline const char *gobj_type(enum media_gobj_type type)
+{
+	switch (type) {
+	case MEDIA_GRAPH_ENTITY:
+		return "entity";
+	case MEDIA_GRAPH_PAD:
+		return "pad";
+	case MEDIA_GRAPH_LINK:
+		return "link";
+	case MEDIA_GRAPH_INTF_DEVNODE:
+		return "intf-devnode";
+	default:
+		return "unknown";
+	}
+}
+
+static inline const char *intf_type(struct media_interface *intf)
+{
+	switch (intf->type) {
+	case MEDIA_INTF_T_DVB_FE:
+		return "dvb-frontend";
+	case MEDIA_INTF_T_DVB_DEMUX:
+		return "dvb-demux";
+	case MEDIA_INTF_T_DVB_DVR:
+		return "dvb-dvr";
+	case MEDIA_INTF_T_DVB_CA:
+		return  "dvb-ca";
+	case MEDIA_INTF_T_DVB_NET:
+		return "dvb-net";
+	case MEDIA_INTF_T_V4L_VIDEO:
+		return "v4l-video";
+	case MEDIA_INTF_T_V4L_VBI:
+		return "v4l-vbi";
+	case MEDIA_INTF_T_V4L_RADIO:
+		return "v4l-radio";
+	case MEDIA_INTF_T_V4L_SUBDEV:
+		return "v4l-subdev";
+	case MEDIA_INTF_T_V4L_SWRADIO:
+		return "v4l-swradio";
+	case MEDIA_INTF_T_V4L_TOUCH:
+		return "v4l-touch";
+	default:
+		return "unknown-intf";
+	}
+};
+
+__must_check int __media_entity_enum_init(struct media_entity_enum *ent_enum,
+					  int idx_max)
+{
+	idx_max = ALIGN(idx_max, BITS_PER_LONG);
+	ent_enum->bmap = kcalloc(idx_max / BITS_PER_LONG, sizeof(long),
+				 GFP_KERNEL);
+	if (!ent_enum->bmap)
+		return -ENOMEM;
+
+	bitmap_zero(ent_enum->bmap, idx_max);
+	ent_enum->idx_max = idx_max;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__media_entity_enum_init);
+
+void media_entity_enum_cleanup(struct media_entity_enum *ent_enum)
+{
+	kfree(ent_enum->bmap);
+}
+EXPORT_SYMBOL_GPL(media_entity_enum_cleanup);
+
+/**
+ *  dev_dbg_obj - Prints in debug mode a change on some object
+ *
+ * @event_name:	Name of the event to report. Could be __func__
+ * @gobj:	Pointer to the object
+ *
+ * Enabled only if DEBUG or CONFIG_DYNAMIC_DEBUG. Otherwise, it
+ * won't produce any code.
+ */
+static void dev_dbg_obj(const char *event_name,  struct media_gobj *gobj)
+{
+#if defined(DEBUG) || defined (CONFIG_DYNAMIC_DEBUG)
+	switch (media_type(gobj)) {
+	case MEDIA_GRAPH_ENTITY:
+		dev_dbg(gobj->mdev->dev,
+			"%s id %u: entity '%s'\n",
+			event_name, media_id(gobj),
+			gobj_to_entity(gobj)->name);
+		break;
+	case MEDIA_GRAPH_LINK:
+	{
+		struct media_link *link = gobj_to_link(gobj);
+
+		dev_dbg(gobj->mdev->dev,
+			"%s id %u: %s link id %u ==> id %u\n",
+			event_name, media_id(gobj),
+			media_type(link->gobj0) == MEDIA_GRAPH_PAD ?
+				"data" : "interface",
+			media_id(link->gobj0),
+			media_id(link->gobj1));
+		break;
+	}
+	case MEDIA_GRAPH_PAD:
+	{
+		struct media_pad *pad = gobj_to_pad(gobj);
+
+		dev_dbg(gobj->mdev->dev,
+			"%s id %u: %s%spad '%s':%d\n",
+			event_name, media_id(gobj),
+			pad->flags & MEDIA_PAD_FL_SINK   ? "sink " : "",
+			pad->flags & MEDIA_PAD_FL_SOURCE ? "source " : "",
+			pad->entity->name, pad->index);
+		break;
+	}
+	case MEDIA_GRAPH_INTF_DEVNODE:
+	{
+		struct media_interface *intf = gobj_to_intf(gobj);
+		struct media_intf_devnode *devnode = intf_to_devnode(intf);
+
+		dev_dbg(gobj->mdev->dev,
+			"%s id %u: intf_devnode %s - major: %d, minor: %d\n",
+			event_name, media_id(gobj),
+			intf_type(intf),
+			devnode->major, devnode->minor);
+		break;
+	}
+	}
+#endif
+}
+
+void media_gobj_create(struct media_device *mdev,
+			   enum media_gobj_type type,
+			   struct media_gobj *gobj)
+{
+	BUG_ON(!mdev);
+
+	gobj->mdev = mdev;
+
+	/* Create a per-type unique object ID */
+	gobj->id = media_gobj_gen_id(type, ++mdev->id);
+
+	switch (type) {
+	case MEDIA_GRAPH_ENTITY:
+		list_add_tail(&gobj->list, &mdev->entities);
+		break;
+	case MEDIA_GRAPH_PAD:
+		list_add_tail(&gobj->list, &mdev->pads);
+		break;
+	case MEDIA_GRAPH_LINK:
+		list_add_tail(&gobj->list, &mdev->links);
+		break;
+	case MEDIA_GRAPH_INTF_DEVNODE:
+		list_add_tail(&gobj->list, &mdev->interfaces);
+		break;
+	}
+
+	mdev->topology_version++;
+
+	dev_dbg_obj(__func__, gobj);
+}
+
+void media_gobj_destroy(struct media_gobj *gobj)
+{
+	/* Do nothing if the object is not linked. */
+	if (gobj->mdev == NULL)
+		return;
+
+	dev_dbg_obj(__func__, gobj);
+
+	gobj->mdev->topology_version++;
+
+	/* Remove the object from mdev list */
+	list_del(&gobj->list);
+
+	gobj->mdev = NULL;
+}
+
+/*
+ * TODO: Get rid of this.
+ */
+#define MEDIA_ENTITY_MAX_PADS		512
+
+int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
+			   struct media_pad *pads)
+{
+	struct media_device *mdev = entity->graph_obj.mdev;
+	unsigned int i;
+
+	if (num_pads >= MEDIA_ENTITY_MAX_PADS)
+		return -E2BIG;
+
+	entity->num_pads = num_pads;
+	entity->pads = pads;
+
+	if (mdev)
+		mutex_lock(&mdev->graph_mutex);
+
+	for (i = 0; i < num_pads; i++) {
+		pads[i].entity = entity;
+		pads[i].index = i;
+		if (mdev)
+			media_gobj_create(mdev, MEDIA_GRAPH_PAD,
+					&entity->pads[i].graph_obj);
+	}
+
+	if (mdev)
+		mutex_unlock(&mdev->graph_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(media_entity_pads_init);
+
+/* -----------------------------------------------------------------------------
+ * Graph traversal
+ */
+
+static struct media_entity *
+media_entity_other(struct media_entity *entity, struct media_link *link)
+{
+	if (link->source->entity == entity)
+		return link->sink->entity;
+	else
+		return link->source->entity;
+}
+
+/* push an entity to traversal stack */
+static void stack_push(struct media_graph *graph,
+		       struct media_entity *entity)
+{
+	if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
+		WARN_ON(1);
+		return;
+	}
+	graph->top++;
+	graph->stack[graph->top].link = entity->links.next;
+	graph->stack[graph->top].entity = entity;
+}
+
+static struct media_entity *stack_pop(struct media_graph *graph)
+{
+	struct media_entity *entity;
+
+	entity = graph->stack[graph->top].entity;
+	graph->top--;
+
+	return entity;
+}
+
+#define link_top(en)	((en)->stack[(en)->top].link)
+#define stack_top(en)	((en)->stack[(en)->top].entity)
+
+/**
+ * media_graph_walk_init - Allocate resources for graph walk
+ * @graph: Media graph structure that will be used to walk the graph
+ * @mdev: Media device
+ *
+ * Reserve resources for graph walk in media device's current
+ * state. The memory must be released using
+ * media_graph_walk_free().
+ *
+ * Returns error on failure, zero on success.
+ */
+__must_check int media_graph_walk_init(
+	struct media_graph *graph, struct media_device *mdev)
+{
+	return media_entity_enum_init(&graph->ent_enum, mdev);
+}
+EXPORT_SYMBOL_GPL(media_graph_walk_init);
+
+/**
+ * media_graph_walk_cleanup - Release resources related to graph walking
+ * @graph: Media graph structure that was used to walk the graph
+ */
+void media_graph_walk_cleanup(struct media_graph *graph)
+{
+	media_entity_enum_cleanup(&graph->ent_enum);
+}
+EXPORT_SYMBOL_GPL(media_graph_walk_cleanup);
+
+void media_graph_walk_start(struct media_graph *graph,
+			    struct media_entity *entity)
+{
+	media_entity_enum_zero(&graph->ent_enum);
+	media_entity_enum_set(&graph->ent_enum, entity);
+
+	graph->top = 0;
+	graph->stack[graph->top].entity = NULL;
+	stack_push(graph, entity);
+	dev_dbg(entity->graph_obj.mdev->dev,
+		"begin graph walk at '%s'\n", entity->name);
+}
+EXPORT_SYMBOL_GPL(media_graph_walk_start);
+
+static void media_graph_walk_iter(struct media_graph *graph)
+{
+	struct media_entity *entity = stack_top(graph);
+	struct media_link *link;
+	struct media_entity *next;
+
+	link = list_entry(link_top(graph), typeof(*link), list);
+
+	/* The link is not enabled so we do not follow. */
+	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
+		link_top(graph) = link_top(graph)->next;
+		dev_dbg(entity->graph_obj.mdev->dev,
+			"walk: skipping disabled link '%s':%u -> '%s':%u\n",
+			link->source->entity->name, link->source->index,
+			link->sink->entity->name, link->sink->index);
+		return;
+	}
+
+	/* Get the entity in the other end of the link . */
+	next = media_entity_other(entity, link);
+
+	/* Has the entity already been visited? */
+	if (media_entity_enum_test_and_set(&graph->ent_enum, next)) {
+		link_top(graph) = link_top(graph)->next;
+		dev_dbg(entity->graph_obj.mdev->dev,
+			"walk: skipping entity '%s' (already seen)\n",
+			next->name);
+		return;
+	}
+
+	/* Push the new entity to stack and start over. */
+	link_top(graph) = link_top(graph)->next;
+	stack_push(graph, next);
+	dev_dbg(entity->graph_obj.mdev->dev, "walk: pushing '%s' on stack\n",
+		next->name);
+}
+
+struct media_entity *media_graph_walk_next(struct media_graph *graph)
+{
+	struct media_entity *entity;
+
+	if (stack_top(graph) == NULL)
+		return NULL;
+
+	/*
+	 * Depth first search. Push entity to stack and continue from
+	 * top of the stack until no more entities on the level can be
+	 * found.
+	 */
+	while (link_top(graph) != &stack_top(graph)->links)
+		media_graph_walk_iter(graph);
+
+	entity = stack_pop(graph);
+	dev_dbg(entity->graph_obj.mdev->dev,
+		"walk: returning entity '%s'\n", entity->name);
+
+	return entity;
+}
+EXPORT_SYMBOL_GPL(media_graph_walk_next);
+
+int media_entity_get_fwnode_pad(struct media_entity *entity,
+				struct fwnode_handle *fwnode,
+				unsigned long direction_flags)
+{
+	struct fwnode_endpoint endpoint;
+	unsigned int i;
+	int ret;
+
+	if (!entity->ops || !entity->ops->get_fwnode_pad) {
+		for (i = 0; i < entity->num_pads; i++) {
+			if (entity->pads[i].flags & direction_flags)
+				return i;
+		}
+
+		return -ENXIO;
+	}
+
+	ret = fwnode_graph_parse_endpoint(fwnode, &endpoint);
+	if (ret)
+		return ret;
+
+	ret = entity->ops->get_fwnode_pad(&endpoint);
+	if (ret < 0)
+		return ret;
+
+	if (ret >= entity->num_pads)
+		return -ENXIO;
+
+	if (!(entity->pads[ret].flags & direction_flags))
+		return -ENXIO;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(media_entity_get_fwnode_pad);
+
+/* -----------------------------------------------------------------------------
+ * Pipeline management
+ */
+
+__must_check int __media_pipeline_start(struct media_entity *entity,
+					struct media_pipeline *pipe)
+{
+	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_graph *graph = &pipe->graph;
+	struct media_entity *entity_err = entity;
+	struct media_link *link;
+	int ret;
+
+	if (!pipe->streaming_count++) {
+		ret = media_graph_walk_init(&pipe->graph, mdev);
+		if (ret)
+			goto error_graph_walk_start;
+	}
+
+	media_graph_walk_start(&pipe->graph, entity);
+
+	while ((entity = media_graph_walk_next(graph))) {
+		DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
+		DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
+
+		entity->stream_count++;
+
+		if (WARN_ON(entity->pipe && entity->pipe != pipe)) {
+			ret = -EBUSY;
+			goto error;
+		}
+
+		entity->pipe = pipe;
+
+		/* Already streaming --- no need to check. */
+		if (entity->stream_count > 1)
+			continue;
+
+		if (!entity->ops || !entity->ops->link_validate)
+			continue;
+
+		bitmap_zero(active, entity->num_pads);
+		bitmap_fill(has_no_links, entity->num_pads);
+
+		list_for_each_entry(link, &entity->links, list) {
+			struct media_pad *pad = link->sink->entity == entity
+						? link->sink : link->source;
+
+			/* Mark that a pad is connected by a link. */
+			bitmap_clear(has_no_links, pad->index, 1);
+
+			/*
+			 * Pads that either do not need to connect or
+			 * are connected through an enabled link are
+			 * fine.
+			 */
+			if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
+			    link->flags & MEDIA_LNK_FL_ENABLED)
+				bitmap_set(active, pad->index, 1);
+
+			/*
+			 * Link validation will only take place for
+			 * sink ends of the link that are enabled.
+			 */
+			if (link->sink != pad ||
+			    !(link->flags & MEDIA_LNK_FL_ENABLED))
+				continue;
+
+			ret = entity->ops->link_validate(link);
+			if (ret < 0 && ret != -ENOIOCTLCMD) {
+				dev_dbg(entity->graph_obj.mdev->dev,
+					"link validation failed for '%s':%u -> '%s':%u, error %d\n",
+					link->source->entity->name,
+					link->source->index,
+					entity->name, link->sink->index, ret);
+				goto error;
+			}
+		}
+
+		/* Either no links or validated links are fine. */
+		bitmap_or(active, active, has_no_links, entity->num_pads);
+
+		if (!bitmap_full(active, entity->num_pads)) {
+			ret = -ENOLINK;
+			dev_dbg(entity->graph_obj.mdev->dev,
+				"'%s':%u must be connected by an enabled link\n",
+				entity->name,
+				(unsigned)find_first_zero_bit(
+					active, entity->num_pads));
+			goto error;
+		}
+	}
+
+	return 0;
+
+error:
+	/*
+	 * Link validation on graph failed. We revert what we did and
+	 * return the error.
+	 */
+	media_graph_walk_start(graph, entity_err);
+
+	while ((entity_err = media_graph_walk_next(graph))) {
+		/* Sanity check for negative stream_count */
+		if (!WARN_ON_ONCE(entity_err->stream_count <= 0)) {
+			entity_err->stream_count--;
+			if (entity_err->stream_count == 0)
+				entity_err->pipe = NULL;
+		}
+
+		/*
+		 * We haven't increased stream_count further than this
+		 * so we quit here.
+		 */
+		if (entity_err == entity)
+			break;
+	}
+
+error_graph_walk_start:
+	if (!--pipe->streaming_count)
+		media_graph_walk_cleanup(graph);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__media_pipeline_start);
+
+__must_check int media_pipeline_start(struct media_entity *entity,
+				      struct media_pipeline *pipe)
+{
+	struct media_device *mdev = entity->graph_obj.mdev;
+	int ret;
+
+	mutex_lock(&mdev->graph_mutex);
+	ret = __media_pipeline_start(entity, pipe);
+	mutex_unlock(&mdev->graph_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(media_pipeline_start);
+
+void __media_pipeline_stop(struct media_entity *entity)
+{
+	struct media_graph *graph = &entity->pipe->graph;
+	struct media_pipeline *pipe = entity->pipe;
+
+	/*
+	 * If the following check fails, the driver has performed an
+	 * unbalanced call to media_pipeline_stop()
+	 */
+	if (WARN_ON(!pipe))
+		return;
+
+	media_graph_walk_start(graph, entity);
+
+	while ((entity = media_graph_walk_next(graph))) {
+		/* Sanity check for negative stream_count */
+		if (!WARN_ON_ONCE(entity->stream_count <= 0)) {
+			entity->stream_count--;
+			if (entity->stream_count == 0)
+				entity->pipe = NULL;
+		}
+	}
+
+	if (!--pipe->streaming_count)
+		media_graph_walk_cleanup(graph);
+
+}
+EXPORT_SYMBOL_GPL(__media_pipeline_stop);
+
+void media_pipeline_stop(struct media_entity *entity)
+{
+	struct media_device *mdev = entity->graph_obj.mdev;
+
+	mutex_lock(&mdev->graph_mutex);
+	__media_pipeline_stop(entity);
+	mutex_unlock(&mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(media_pipeline_stop);
+
+/* -----------------------------------------------------------------------------
+ * Module use count
+ */
+
+struct media_entity *media_entity_get(struct media_entity *entity)
+{
+	if (entity == NULL)
+		return NULL;
+
+	if (entity->graph_obj.mdev->dev &&
+	    !try_module_get(entity->graph_obj.mdev->dev->driver->owner))
+		return NULL;
+
+	return entity;
+}
+EXPORT_SYMBOL_GPL(media_entity_get);
+
+void media_entity_put(struct media_entity *entity)
+{
+	if (entity == NULL)
+		return;
+
+	if (entity->graph_obj.mdev->dev)
+		module_put(entity->graph_obj.mdev->dev->driver->owner);
+}
+EXPORT_SYMBOL_GPL(media_entity_put);
+
+/* -----------------------------------------------------------------------------
+ * Links management
+ */
+
+static struct media_link *media_add_link(struct list_head *head)
+{
+	struct media_link *link;
+
+	link = kzalloc(sizeof(*link), GFP_KERNEL);
+	if (link == NULL)
+		return NULL;
+
+	list_add_tail(&link->list, head);
+
+	return link;
+}
+
+static void __media_entity_remove_link(struct media_entity *entity,
+				       struct media_link *link)
+{
+	struct media_link *rlink, *tmp;
+	struct media_entity *remote;
+
+	if (link->source->entity == entity)
+		remote = link->sink->entity;
+	else
+		remote = link->source->entity;
+
+	list_for_each_entry_safe(rlink, tmp, &remote->links, list) {
+		if (rlink != link->reverse)
+			continue;
+
+		if (link->source->entity == entity)
+			remote->num_backlinks--;
+
+		/* Remove the remote link */
+		list_del(&rlink->list);
+		media_gobj_destroy(&rlink->graph_obj);
+		kfree(rlink);
+
+		if (--remote->num_links == 0)
+			break;
+	}
+	list_del(&link->list);
+	media_gobj_destroy(&link->graph_obj);
+	kfree(link);
+}
+
+int
+media_create_pad_link(struct media_entity *source, u16 source_pad,
+			 struct media_entity *sink, u16 sink_pad, u32 flags)
+{
+	struct media_link *link;
+	struct media_link *backlink;
+
+	BUG_ON(source == NULL || sink == NULL);
+	BUG_ON(source_pad >= source->num_pads);
+	BUG_ON(sink_pad >= sink->num_pads);
+
+	link = media_add_link(&source->links);
+	if (link == NULL)
+		return -ENOMEM;
+
+	link->source = &source->pads[source_pad];
+	link->sink = &sink->pads[sink_pad];
+	link->flags = flags & ~MEDIA_LNK_FL_INTERFACE_LINK;
+
+	/* Initialize graph object embedded at the new link */
+	media_gobj_create(source->graph_obj.mdev, MEDIA_GRAPH_LINK,
+			&link->graph_obj);
+
+	/* Create the backlink. Backlinks are used to help graph traversal and
+	 * are not reported to userspace.
+	 */
+	backlink = media_add_link(&sink->links);
+	if (backlink == NULL) {
+		__media_entity_remove_link(source, link);
+		return -ENOMEM;
+	}
+
+	backlink->source = &source->pads[source_pad];
+	backlink->sink = &sink->pads[sink_pad];
+	backlink->flags = flags;
+	backlink->is_backlink = true;
+
+	/* Initialize graph object embedded at the new link */
+	media_gobj_create(sink->graph_obj.mdev, MEDIA_GRAPH_LINK,
+			&backlink->graph_obj);
+
+	link->reverse = backlink;
+	backlink->reverse = link;
+
+	sink->num_backlinks++;
+	sink->num_links++;
+	source->num_links++;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(media_create_pad_link);
+
+int media_create_pad_links(const struct media_device *mdev,
+			   const u32 source_function,
+			   struct media_entity *source,
+			   const u16 source_pad,
+			   const u32 sink_function,
+			   struct media_entity *sink,
+			   const u16 sink_pad,
+			   u32 flags,
+			   const bool allow_both_undefined)
+{
+	struct media_entity *entity;
+	unsigned function;
+	int ret;
+
+	/* Trivial case: 1:1 relation */
+	if (source && sink)
+		return media_create_pad_link(source, source_pad,
+					     sink, sink_pad, flags);
+
+	/* Worse case scenario: n:n relation */
+	if (!source && !sink) {
+		if (!allow_both_undefined)
+			return 0;
+		media_device_for_each_entity(source, mdev) {
+			if (source->function != source_function)
+				continue;
+			media_device_for_each_entity(sink, mdev) {
+				if (sink->function != sink_function)
+					continue;
+				ret = media_create_pad_link(source, source_pad,
+							    sink, sink_pad,
+							    flags);
+				if (ret)
+					return ret;
+				flags &= ~(MEDIA_LNK_FL_ENABLED |
+					   MEDIA_LNK_FL_IMMUTABLE);
+			}
+		}
+		return 0;
+	}
+
+	/* Handle 1:n and n:1 cases */
+	if (source)
+		function = sink_function;
+	else
+		function = source_function;
+
+	media_device_for_each_entity(entity, mdev) {
+		if (entity->function != function)
+			continue;
+
+		if (source)
+			ret = media_create_pad_link(source, source_pad,
+						    entity, sink_pad, flags);
+		else
+			ret = media_create_pad_link(entity, source_pad,
+						    sink, sink_pad, flags);
+		if (ret)
+			return ret;
+		flags &= ~(MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE);
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(media_create_pad_links);
+
+void __media_entity_remove_links(struct media_entity *entity)
+{
+	struct media_link *link, *tmp;
+
+	list_for_each_entry_safe(link, tmp, &entity->links, list)
+		__media_entity_remove_link(entity, link);
+
+	entity->num_links = 0;
+	entity->num_backlinks = 0;
+}
+EXPORT_SYMBOL_GPL(__media_entity_remove_links);
+
+void media_entity_remove_links(struct media_entity *entity)
+{
+	struct media_device *mdev = entity->graph_obj.mdev;
+
+	/* Do nothing if the entity is not registered. */
+	if (mdev == NULL)
+		return;
+
+	mutex_lock(&mdev->graph_mutex);
+	__media_entity_remove_links(entity);
+	mutex_unlock(&mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(media_entity_remove_links);
+
+static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
+{
+	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 = flags;
+	link->reverse->flags = link->flags;
+
+	return 0;
+}
+
+int __media_entity_setup_link(struct media_link *link, u32 flags)
+{
+	const u32 mask = MEDIA_LNK_FL_ENABLED;
+	struct media_device *mdev;
+	struct media_entity *source, *sink;
+	int ret = -EBUSY;
+
+	if (link == NULL)
+		return -EINVAL;
+
+	/* The non-modifiable link flags must not be modified. */
+	if ((link->flags & ~mask) != (flags & ~mask))
+		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;
+
+	if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
+	    (source->stream_count || sink->stream_count))
+		return -EBUSY;
+
+	mdev = source->graph_obj.mdev;
+
+	if (mdev->ops && mdev->ops->link_notify) {
+		ret = mdev->ops->link_notify(link, flags,
+					     MEDIA_DEV_NOTIFY_PRE_LINK_CH);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = __media_entity_setup_link_notify(link, flags);
+
+	if (mdev->ops && mdev->ops->link_notify)
+		mdev->ops->link_notify(link, flags,
+				       MEDIA_DEV_NOTIFY_POST_LINK_CH);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__media_entity_setup_link);
+
+int media_entity_setup_link(struct media_link *link, u32 flags)
+{
+	int ret;
+
+	mutex_lock(&link->graph_obj.mdev->graph_mutex);
+	ret = __media_entity_setup_link(link, flags);
+	mutex_unlock(&link->graph_obj.mdev->graph_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(media_entity_setup_link);
+
+struct media_link *
+media_entity_find_link(struct media_pad *source, struct media_pad *sink)
+{
+	struct media_link *link;
+
+	list_for_each_entry(link, &source->entity->links, list) {
+		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);
+
+struct media_pad *media_entity_remote_pad(const struct media_pad *pad)
+{
+	struct media_link *link;
+
+	list_for_each_entry(link, &pad->entity->links, list) {
+		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_pad);
+
+static void media_interface_init(struct media_device *mdev,
+				 struct media_interface *intf,
+				 u32 gobj_type,
+				 u32 intf_type, u32 flags)
+{
+	intf->type = intf_type;
+	intf->flags = flags;
+	INIT_LIST_HEAD(&intf->links);
+
+	media_gobj_create(mdev, gobj_type, &intf->graph_obj);
+}
+
+/* Functions related to the media interface via device nodes */
+
+struct media_intf_devnode *media_devnode_create(struct media_device *mdev,
+						u32 type, u32 flags,
+						u32 major, u32 minor)
+{
+	struct media_intf_devnode *devnode;
+
+	devnode = kzalloc(sizeof(*devnode), GFP_KERNEL);
+	if (!devnode)
+		return NULL;
+
+	devnode->major = major;
+	devnode->minor = minor;
+
+	media_interface_init(mdev, &devnode->intf, MEDIA_GRAPH_INTF_DEVNODE,
+			     type, flags);
+
+	return devnode;
+}
+EXPORT_SYMBOL_GPL(media_devnode_create);
+
+void media_devnode_remove(struct media_intf_devnode *devnode)
+{
+	media_remove_intf_links(&devnode->intf);
+	media_gobj_destroy(&devnode->intf.graph_obj);
+	kfree(devnode);
+}
+EXPORT_SYMBOL_GPL(media_devnode_remove);
+
+struct media_link *media_create_intf_link(struct media_entity *entity,
+					    struct media_interface *intf,
+					    u32 flags)
+{
+	struct media_link *link;
+
+	link = media_add_link(&intf->links);
+	if (link == NULL)
+		return NULL;
+
+	link->intf = intf;
+	link->entity = entity;
+	link->flags = flags | MEDIA_LNK_FL_INTERFACE_LINK;
+
+	/* Initialize graph object embedded at the new link */
+	media_gobj_create(intf->graph_obj.mdev, MEDIA_GRAPH_LINK,
+			&link->graph_obj);
+
+	return link;
+}
+EXPORT_SYMBOL_GPL(media_create_intf_link);
+
+void __media_remove_intf_link(struct media_link *link)
+{
+	list_del(&link->list);
+	media_gobj_destroy(&link->graph_obj);
+	kfree(link);
+}
+EXPORT_SYMBOL_GPL(__media_remove_intf_link);
+
+void media_remove_intf_link(struct media_link *link)
+{
+	struct media_device *mdev = link->graph_obj.mdev;
+
+	/* Do nothing if the intf is not registered. */
+	if (mdev == NULL)
+		return;
+
+	mutex_lock(&mdev->graph_mutex);
+	__media_remove_intf_link(link);
+	mutex_unlock(&mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(media_remove_intf_link);
+
+void __media_remove_intf_links(struct media_interface *intf)
+{
+	struct media_link *link, *tmp;
+
+	list_for_each_entry_safe(link, tmp, &intf->links, list)
+		__media_remove_intf_link(link);
+
+}
+EXPORT_SYMBOL_GPL(__media_remove_intf_links);
+
+void media_remove_intf_links(struct media_interface *intf)
+{
+	struct media_device *mdev = intf->graph_obj.mdev;
+
+	/* Do nothing if the intf is not registered. */
+	if (mdev == NULL)
+		return;
+
+	mutex_lock(&mdev->graph_mutex);
+	__media_remove_intf_links(intf);
+	mutex_unlock(&mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(media_remove_intf_links);