fsi: Add regmap and refactor sbefifo

Merge series from Eddie James <eajames@linux.ibm.com>:

The SBEFIFO hardware can now be attached over a new I2C endpoint interface
called the I2C Responder (I2CR). In order to use the existing SBEFIFO
driver, add a regmap driver for the FSI bus and an endpoint driver for the
I2CR. Then, refactor the SBEFIFO and OCC drivers to clean up and use the
new regmap driver or the I2CR interface.

This branch just has the regmap change so it can be shared with the FSI
code.

1 files changed, 529 insertions, 119 deletions

diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index afd1bd7ff7b6..b8bcbc734eaf 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -59,10 +59,12 @@ static inline const char *link_type_name(struct media_link *link)
 	}
 }
 
-__must_check int __media_entity_enum_init(struct media_entity_enum *ent_enum,
-					  int idx_max)
+__must_check int media_entity_enum_init(struct media_entity_enum *ent_enum,
+					struct media_device *mdev)
 {
-	idx_max = ALIGN(idx_max, BITS_PER_LONG);
+	int idx_max;
+
+	idx_max = ALIGN(mdev->entity_internal_idx_max + 1, BITS_PER_LONG);
 	ent_enum->bmap = bitmap_zalloc(idx_max, GFP_KERNEL);
 	if (!ent_enum->bmap)
 		return -ENOMEM;
@@ -71,7 +73,7 @@ __must_check int __media_entity_enum_init(struct media_entity_enum *ent_enum,
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(__media_entity_enum_init);
+EXPORT_SYMBOL_GPL(media_entity_enum_init);
 
 void media_entity_enum_cleanup(struct media_entity_enum *ent_enum)
 {
@@ -193,7 +195,8 @@ 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;
+	struct media_pad *iter;
+	unsigned int i = 0;
 
 	if (num_pads >= MEDIA_ENTITY_MAX_PADS)
 		return -E2BIG;
@@ -204,12 +207,12 @@ int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
 	if (mdev)
 		mutex_lock(&mdev->graph_mutex);
 
-	for (i = 0; i < num_pads; i++) {
-		pads[i].entity = entity;
-		pads[i].index = i;
+	media_entity_for_each_pad(entity, iter) {
+		iter->entity = entity;
+		iter->index = i++;
 		if (mdev)
 			media_gobj_create(mdev, MEDIA_GRAPH_PAD,
-					&entity->pads[i].graph_obj);
+					  &iter->graph_obj);
 	}
 
 	if (mdev)
@@ -223,6 +226,33 @@ EXPORT_SYMBOL_GPL(media_entity_pads_init);
  * Graph traversal
  */
 
+/*
+ * This function checks the interdependency inside the entity between @pad0
+ * and @pad1. If two pads are interdependent they are part of the same pipeline
+ * and enabling one of the pads means that the other pad will become "locked"
+ * and doesn't allow configuration changes.
+ *
+ * This function uses the &media_entity_operations.has_pad_interdep() operation
+ * to check the dependency inside the entity between @pad0 and @pad1. If the
+ * has_pad_interdep operation is not implemented, all pads of the entity are
+ * considered to be interdependent.
+ */
+static bool media_entity_has_pad_interdep(struct media_entity *entity,
+					  unsigned int pad0, unsigned int pad1)
+{
+	if (pad0 >= entity->num_pads || pad1 >= entity->num_pads)
+		return false;
+
+	if (entity->pads[pad0].flags & entity->pads[pad1].flags &
+	    (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_SOURCE))
+		return false;
+
+	if (!entity->ops || !entity->ops->has_pad_interdep)
+		return true;
+
+	return entity->ops->has_pad_interdep(entity, pad0, pad1);
+}
+
 static struct media_entity *
 media_entity_other(struct media_entity *entity, struct media_link *link)
 {
@@ -367,139 +397,435 @@ struct media_entity *media_graph_walk_next(struct media_graph *graph)
 }
 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)
+/* -----------------------------------------------------------------------------
+ * Pipeline management
+ */
+
+/*
+ * The pipeline traversal stack stores pads that are reached during graph
+ * traversal, with a list of links to be visited to continue the traversal.
+ * When a new pad is reached, an entry is pushed on the top of the stack and
+ * points to the incoming pad and the first link of the entity.
+ *
+ * To find further pads in the pipeline, the traversal algorithm follows
+ * internal pad dependencies in the entity, and then links in the graph. It
+ * does so by iterating over all links of the entity, and following enabled
+ * links that originate from a pad that is internally connected to the incoming
+ * pad, as reported by the media_entity_has_pad_interdep() function.
+ */
+
+/**
+ * struct media_pipeline_walk_entry - Entry in the pipeline traversal stack
+ *
+ * @pad: The media pad being visited
+ * @links: Links left to be visited
+ */
+struct media_pipeline_walk_entry {
+	struct media_pad *pad;
+	struct list_head *links;
+};
+
+/**
+ * struct media_pipeline_walk - State used by the media pipeline traversal
+ *				algorithm
+ *
+ * @mdev: The media device
+ * @stack: Depth-first search stack
+ * @stack.size: Number of allocated entries in @stack.entries
+ * @stack.top: Index of the top stack entry (-1 if the stack is empty)
+ * @stack.entries: Stack entries
+ */
+struct media_pipeline_walk {
+	struct media_device *mdev;
+
+	struct {
+		unsigned int size;
+		int top;
+		struct media_pipeline_walk_entry *entries;
+	} stack;
+};
+
+#define MEDIA_PIPELINE_STACK_GROW_STEP		16
+
+static struct media_pipeline_walk_entry *
+media_pipeline_walk_top(struct media_pipeline_walk *walk)
 {
-	struct fwnode_endpoint endpoint;
-	unsigned int i;
+	return &walk->stack.entries[walk->stack.top];
+}
+
+static bool media_pipeline_walk_empty(struct media_pipeline_walk *walk)
+{
+	return walk->stack.top == -1;
+}
+
+/* Increase the stack size by MEDIA_PIPELINE_STACK_GROW_STEP elements. */
+static int media_pipeline_walk_resize(struct media_pipeline_walk *walk)
+{
+	struct media_pipeline_walk_entry *entries;
+	unsigned int new_size;
+
+	/* Safety check, to avoid stack overflows in case of bugs. */
+	if (walk->stack.size >= 256)
+		return -E2BIG;
+
+	new_size = walk->stack.size + MEDIA_PIPELINE_STACK_GROW_STEP;
+
+	entries = krealloc(walk->stack.entries,
+			   new_size * sizeof(*walk->stack.entries),
+			   GFP_KERNEL);
+	if (!entries)
+		return -ENOMEM;
+
+	walk->stack.entries = entries;
+	walk->stack.size = new_size;
+
+	return 0;
+}
+
+/* Push a new entry on the stack. */
+static int media_pipeline_walk_push(struct media_pipeline_walk *walk,
+				    struct media_pad *pad)
+{
+	struct media_pipeline_walk_entry *entry;
 	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;
+	if (walk->stack.top + 1 >= walk->stack.size) {
+		ret = media_pipeline_walk_resize(walk);
+		if (ret)
+			return ret;
+	}
+
+	walk->stack.top++;
+	entry = media_pipeline_walk_top(walk);
+	entry->pad = pad;
+	entry->links = pad->entity->links.next;
+
+	dev_dbg(walk->mdev->dev,
+		"media pipeline: pushed entry %u: '%s':%u\n",
+		walk->stack.top, pad->entity->name, pad->index);
+
+	return 0;
+}
+
+/*
+ * Move the top entry link cursor to the next link. If all links of the entry
+ * have been visited, pop the entry itself.
+ */
+static void media_pipeline_walk_pop(struct media_pipeline_walk *walk)
+{
+	struct media_pipeline_walk_entry *entry;
+
+	if (WARN_ON(walk->stack.top < 0))
+		return;
+
+	entry = media_pipeline_walk_top(walk);
+
+	if (entry->links->next == &entry->pad->entity->links) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: entry %u has no more links, popping\n",
+			walk->stack.top);
+
+		walk->stack.top--;
+		return;
+	}
+
+	entry->links = entry->links->next;
+
+	dev_dbg(walk->mdev->dev,
+		"media pipeline: moved entry %u to next link\n",
+		walk->stack.top);
+}
+
+/* Free all memory allocated while walking the pipeline. */
+static void media_pipeline_walk_destroy(struct media_pipeline_walk *walk)
+{
+	kfree(walk->stack.entries);
+}
+
+/* Add a pad to the pipeline and push it to the stack. */
+static int media_pipeline_add_pad(struct media_pipeline *pipe,
+				  struct media_pipeline_walk *walk,
+				  struct media_pad *pad)
+{
+	struct media_pipeline_pad *ppad;
+
+	list_for_each_entry(ppad, &pipe->pads, list) {
+		if (ppad->pad == pad) {
+			dev_dbg(pad->graph_obj.mdev->dev,
+				"media pipeline: already contains pad '%s':%u\n",
+				pad->entity->name, pad->index);
+			return 0;
 		}
+	}
 
-		return -ENXIO;
+	ppad = kzalloc(sizeof(*ppad), GFP_KERNEL);
+	if (!ppad)
+		return -ENOMEM;
+
+	ppad->pipe = pipe;
+	ppad->pad = pad;
+
+	list_add_tail(&ppad->list, &pipe->pads);
+
+	dev_dbg(pad->graph_obj.mdev->dev,
+		"media pipeline: added pad '%s':%u\n",
+		pad->entity->name, pad->index);
+
+	return media_pipeline_walk_push(walk, pad);
+}
+
+/* Explore the next link of the entity at the top of the stack. */
+static int media_pipeline_explore_next_link(struct media_pipeline *pipe,
+					    struct media_pipeline_walk *walk)
+{
+	struct media_pipeline_walk_entry *entry = media_pipeline_walk_top(walk);
+	struct media_pad *pad;
+	struct media_link *link;
+	struct media_pad *local;
+	struct media_pad *remote;
+	int ret;
+
+	pad = entry->pad;
+	link = list_entry(entry->links, typeof(*link), list);
+	media_pipeline_walk_pop(walk);
+
+	dev_dbg(walk->mdev->dev,
+		"media pipeline: exploring link '%s':%u -> '%s':%u\n",
+		link->source->entity->name, link->source->index,
+		link->sink->entity->name, link->sink->index);
+
+	/* Skip links that are not enabled. */
+	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: skipping link (disabled)\n");
+		return 0;
 	}
 
-	ret = fwnode_graph_parse_endpoint(fwnode, &endpoint);
+	/* Get the local pad and remote pad. */
+	if (link->source->entity == pad->entity) {
+		local = link->source;
+		remote = link->sink;
+	} else {
+		local = link->sink;
+		remote = link->source;
+	}
+
+	/*
+	 * Skip links that originate from a different pad than the incoming pad
+	 * that is not connected internally in the entity to the incoming pad.
+	 */
+	if (pad != local &&
+	    !media_entity_has_pad_interdep(pad->entity, pad->index, local->index)) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: skipping link (no route)\n");
+		return 0;
+	}
+
+	/*
+	 * Add the local and remote pads of the link to the pipeline and push
+	 * them to the stack, if they're not already present.
+	 */
+	ret = media_pipeline_add_pad(pipe, walk, local);
 	if (ret)
 		return ret;
 
-	ret = entity->ops->get_fwnode_pad(entity, &endpoint);
-	if (ret < 0)
+	ret = media_pipeline_add_pad(pipe, walk, remote);
+	if (ret)
 		return ret;
 
-	if (ret >= entity->num_pads)
-		return -ENXIO;
+	return 0;
+}
 
-	if (!(entity->pads[ret].flags & direction_flags))
-		return -ENXIO;
+static void media_pipeline_cleanup(struct media_pipeline *pipe)
+{
+	while (!list_empty(&pipe->pads)) {
+		struct media_pipeline_pad *ppad;
 
-	return ret;
+		ppad = list_first_entry(&pipe->pads, typeof(*ppad), list);
+		list_del(&ppad->list);
+		kfree(ppad);
+	}
 }
-EXPORT_SYMBOL_GPL(media_entity_get_fwnode_pad);
 
-/* -----------------------------------------------------------------------------
- * Pipeline management
- */
+static int media_pipeline_populate(struct media_pipeline *pipe,
+				   struct media_pad *pad)
+{
+	struct media_pipeline_walk walk = { };
+	struct media_pipeline_pad *ppad;
+	int ret;
+
+	/*
+	 * Populate the media pipeline by walking the media graph, starting
+	 * from @pad.
+	 */
+	INIT_LIST_HEAD(&pipe->pads);
+	pipe->mdev = pad->graph_obj.mdev;
+
+	walk.mdev = pipe->mdev;
+	walk.stack.top = -1;
+	ret = media_pipeline_add_pad(pipe, &walk, pad);
+	if (ret)
+		goto done;
+
+	/*
+	 * Use a depth-first search algorithm: as long as the stack is not
+	 * empty, explore the next link of the top entry. The
+	 * media_pipeline_explore_next_link() function will either move to the
+	 * next link, pop the entry if fully visited, or add new entries on
+	 * top.
+	 */
+	while (!media_pipeline_walk_empty(&walk)) {
+		ret = media_pipeline_explore_next_link(pipe, &walk);
+		if (ret)
+			goto done;
+	}
+
+	dev_dbg(pad->graph_obj.mdev->dev,
+		"media pipeline populated, found pads:\n");
+
+	list_for_each_entry(ppad, &pipe->pads, list)
+		dev_dbg(pad->graph_obj.mdev->dev, "- '%s':%u\n",
+			ppad->pad->entity->name, ppad->pad->index);
+
+	WARN_ON(walk.stack.top != -1);
 
-__must_check int __media_pipeline_start(struct media_entity *entity,
+	ret = 0;
+
+done:
+	media_pipeline_walk_destroy(&walk);
+
+	if (ret)
+		media_pipeline_cleanup(pipe);
+
+	return ret;
+}
+
+__must_check int __media_pipeline_start(struct media_pad *pad,
 					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;
+	struct media_device *mdev = pad->entity->graph_obj.mdev;
+	struct media_pipeline_pad *err_ppad;
+	struct media_pipeline_pad *ppad;
 	int ret;
 
-	if (pipe->streaming_count) {
-		pipe->streaming_count++;
+	lockdep_assert_held(&mdev->graph_mutex);
+
+	/*
+	 * If the entity is already part of a pipeline, that pipeline must
+	 * be the same as the pipe given to media_pipeline_start().
+	 */
+	if (WARN_ON(pad->pipe && pad->pipe != pipe))
+		return -EINVAL;
+
+	/*
+	 * If the pipeline has already been started, it is guaranteed to be
+	 * valid, so just increase the start count.
+	 */
+	if (pipe->start_count) {
+		pipe->start_count++;
 		return 0;
 	}
 
-	ret = media_graph_walk_init(&pipe->graph, mdev);
+	/*
+	 * Populate the pipeline. This populates the media_pipeline pads list
+	 * with media_pipeline_pad instances for each pad found during graph
+	 * walk.
+	 */
+	ret = media_pipeline_populate(pipe, pad);
 	if (ret)
 		return ret;
 
-	media_graph_walk_start(&pipe->graph, entity);
+	/*
+	 * Now that all the pads in the pipeline have been gathered, perform
+	 * the validation steps.
+	 */
+
+	list_for_each_entry(ppad, &pipe->pads, list) {
+		struct media_pad *pad = ppad->pad;
+		struct media_entity *entity = pad->entity;
+		bool has_enabled_link = false;
+		bool has_link = false;
+		struct media_link *link;
 
-	while ((entity = media_graph_walk_next(graph))) {
-		DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
-		DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
+		dev_dbg(mdev->dev, "Validating pad '%s':%u\n", pad->entity->name,
+			pad->index);
 
-		if (entity->pipe && entity->pipe != pipe) {
-			pr_err("Pipe active for %s. Can't start for %s\n",
-				entity->name,
-				entity_err->name);
+		/*
+		 * 1. Ensure that the pad doesn't already belong to a different
+		 * pipeline.
+		 */
+		if (pad->pipe) {
+			dev_dbg(mdev->dev, "Failed to start pipeline: pad '%s':%u busy\n",
+				pad->entity->name, pad->index);
 			ret = -EBUSY;
 			goto error;
 		}
 
-		/* Already streaming --- no need to check. */
-		if (entity->pipe)
-			continue;
-
-		entity->pipe = pipe;
-
-		if (!entity->ops || !entity->ops->link_validate)
-			continue;
-
-		bitmap_zero(active, entity->num_pads);
-		bitmap_fill(has_no_links, entity->num_pads);
-
+		/*
+		 * 2. Validate all active links whose sink is the current pad.
+		 * Validation of the source pads is performed in the context of
+		 * the connected sink pad to avoid duplicating checks.
+		 */
 		for_each_media_entity_data_link(entity, link) {
-			struct media_pad *pad = link->sink->entity == entity
-						? link->sink : link->source;
+			/* Skip links unrelated to the current pad. */
+			if (link->sink != pad && link->source != pad)
+				continue;
 
-			/* Mark that a pad is connected by a link. */
-			bitmap_clear(has_no_links, pad->index, 1);
+			/* Record if the pad has links and enabled links. */
+			if (link->flags & MEDIA_LNK_FL_ENABLED)
+				has_enabled_link = true;
+			has_link = true;
 
 			/*
-			 * Pads that either do not need to connect or
-			 * are connected through an enabled link are
-			 * fine.
+			 * Validate the link if it's enabled and has the
+			 * current pad as its sink.
 			 */
-			if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
-			    link->flags & MEDIA_LNK_FL_ENABLED)
-				bitmap_set(active, pad->index, 1);
+			if (!(link->flags & MEDIA_LNK_FL_ENABLED))
+				continue;
 
-			/*
-			 * 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))
+			if (link->sink != pad)
+				continue;
+
+			if (!entity->ops || !entity->ops->link_validate)
 				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",
+			if (ret) {
+				dev_dbg(mdev->dev,
+					"Link '%s':%u -> '%s':%u failed validation: %d\n",
 					link->source->entity->name,
 					link->source->index,
-					entity->name, link->sink->index, ret);
+					link->sink->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);
+			dev_dbg(mdev->dev,
+				"Link '%s':%u -> '%s':%u is valid\n",
+				link->source->entity->name,
+				link->source->index,
+				link->sink->entity->name,
+				link->sink->index);
+		}
 
-		if (!bitmap_full(active, entity->num_pads)) {
+		/*
+		 * 3. If the pad has the MEDIA_PAD_FL_MUST_CONNECT flag set,
+		 * ensure that it has either no link or an enabled link.
+		 */
+		if ((pad->flags & MEDIA_PAD_FL_MUST_CONNECT) && has_link &&
+		    !has_enabled_link) {
+			dev_dbg(mdev->dev,
+				"Pad '%s':%u must be connected by an enabled link\n",
+				pad->entity->name, pad->index);
 			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;
 		}
+
+		/* Validation passed, store the pipe pointer in the pad. */
+		pad->pipe = pipe;
 	}
 
-	pipe->streaming_count++;
+	pipe->start_count++;
 
 	return 0;
 
@@ -508,42 +834,37 @@ 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))) {
-		entity_err->pipe = NULL;
-
-		/*
-		 * We haven't started entities further than this so we quit
-		 * here.
-		 */
-		if (entity_err == entity)
+	list_for_each_entry(err_ppad, &pipe->pads, list) {
+		if (err_ppad == ppad)
 			break;
+
+		err_ppad->pad->pipe = NULL;
 	}
 
-	media_graph_walk_cleanup(graph);
+	media_pipeline_cleanup(pipe);
 
 	return ret;
 }
 EXPORT_SYMBOL_GPL(__media_pipeline_start);
 
-__must_check int media_pipeline_start(struct media_entity *entity,
+__must_check int media_pipeline_start(struct media_pad *pad,
 				      struct media_pipeline *pipe)
 {
-	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_device *mdev = pad->entity->graph_obj.mdev;
 	int ret;
 
 	mutex_lock(&mdev->graph_mutex);
-	ret = __media_pipeline_start(entity, pipe);
+	ret = __media_pipeline_start(pad, pipe);
 	mutex_unlock(&mdev->graph_mutex);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(media_pipeline_start);
 
-void __media_pipeline_stop(struct media_entity *entity)
+void __media_pipeline_stop(struct media_pad *pad)
 {
-	struct media_graph *graph = &entity->pipe->graph;
-	struct media_pipeline *pipe = entity->pipe;
+	struct media_pipeline *pipe = pad->pipe;
+	struct media_pipeline_pad *ppad;
 
 	/*
 	 * If the following check fails, the driver has performed an
@@ -552,29 +873,65 @@ void __media_pipeline_stop(struct media_entity *entity)
 	if (WARN_ON(!pipe))
 		return;
 
-	if (--pipe->streaming_count)
+	if (--pipe->start_count)
 		return;
 
-	media_graph_walk_start(graph, entity);
-
-	while ((entity = media_graph_walk_next(graph)))
-		entity->pipe = NULL;
+	list_for_each_entry(ppad, &pipe->pads, list)
+		ppad->pad->pipe = NULL;
 
-	media_graph_walk_cleanup(graph);
+	media_pipeline_cleanup(pipe);
 
+	if (pipe->allocated)
+		kfree(pipe);
 }
 EXPORT_SYMBOL_GPL(__media_pipeline_stop);
 
-void media_pipeline_stop(struct media_entity *entity)
+void media_pipeline_stop(struct media_pad *pad)
 {
-	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_device *mdev = pad->entity->graph_obj.mdev;
 
 	mutex_lock(&mdev->graph_mutex);
-	__media_pipeline_stop(entity);
+	__media_pipeline_stop(pad);
 	mutex_unlock(&mdev->graph_mutex);
 }
 EXPORT_SYMBOL_GPL(media_pipeline_stop);
 
+__must_check int media_pipeline_alloc_start(struct media_pad *pad)
+{
+	struct media_device *mdev = pad->entity->graph_obj.mdev;
+	struct media_pipeline *new_pipe = NULL;
+	struct media_pipeline *pipe;
+	int ret;
+
+	mutex_lock(&mdev->graph_mutex);
+
+	/*
+	 * Is the entity already part of a pipeline? If not, we need to allocate
+	 * a pipe.
+	 */
+	pipe = media_pad_pipeline(pad);
+	if (!pipe) {
+		new_pipe = kzalloc(sizeof(*new_pipe), GFP_KERNEL);
+		if (!new_pipe) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		pipe = new_pipe;
+		pipe->allocated = true;
+	}
+
+	ret = __media_pipeline_start(pad, pipe);
+	if (ret)
+		kfree(new_pipe);
+
+out:
+	mutex_unlock(&mdev->graph_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(media_pipeline_alloc_start);
+
 /* -----------------------------------------------------------------------------
  * Links management
  */
@@ -829,7 +1186,7 @@ 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;
+	struct media_pad *source, *sink;
 	int ret = -EBUSY;
 
 	if (link == NULL)
@@ -845,12 +1202,11 @@ int __media_entity_setup_link(struct media_link *link, u32 flags)
 	if (link->flags == flags)
 		return 0;
 
-	source = link->source->entity;
-	sink = link->sink->entity;
+	source = link->source;
+	sink = link->sink;
 
 	if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
-	    (media_entity_is_streaming(source) ||
-	     media_entity_is_streaming(sink)))
+	    (media_pad_is_streaming(source) || media_pad_is_streaming(sink)))
 		return -EBUSY;
 
 	mdev = source->graph_obj.mdev;
@@ -991,6 +1347,60 @@ struct media_pad *media_pad_remote_pad_unique(const struct media_pad *pad)
 }
 EXPORT_SYMBOL_GPL(media_pad_remote_pad_unique);
 
+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(entity, &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);
+
+struct media_pipeline *media_entity_pipeline(struct media_entity *entity)
+{
+	struct media_pad *pad;
+
+	media_entity_for_each_pad(entity, pad) {
+		if (pad->pipe)
+			return pad->pipe;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(media_entity_pipeline);
+
+struct media_pipeline *media_pad_pipeline(struct media_pad *pad)
+{
+	return pad->pipe;
+}
+EXPORT_SYMBOL_GPL(media_pad_pipeline);
+
 static void media_interface_init(struct media_device *mdev,
 				 struct media_interface *intf,
 				 u32 gobj_type,