/*
   * 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.
   *
   * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  #include <linux/bitmap.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <media/media-entity.h>
  #include <media/media-device.h>
  
  /**
   * media_entity_init - Initialize a media entity
   *
   * @num_pads: Total number of sink and source pads.
   * @extra_links: Initial estimate of the number of extra links.
   * @pads: Array of 'num_pads' pads.
   *
   * The total number of pads is an intrinsic property of entities known by the
   * entity driver, while the total number of links depends on hardware design
   * and is an extrinsic property unknown to the entity driver. However, in most
   * use cases the entity driver can guess the number of links which can safely
   * be assumed to be equal to or larger than the number of pads.
   *
   * For those reasons the links array can be preallocated based on the entity
   * driver guess and will be reallocated later if extra links need to be
   * created.
   *
   * This function allocates a links array with enough space to hold at least
   * 'num_pads' + 'extra_links' elements. The media_entity::max_links field will
   * be set to the number of allocated elements.
   *
   * The pads array is managed by the entity driver and passed to
   * media_entity_init() where its pointer will be stored in the entity structure.
   */
  int
  media_entity_init(struct media_entity *entity, u16 num_pads,
  		  struct media_pad *pads, u16 extra_links)
  {
  	struct media_link *links;
  	unsigned int max_links = num_pads + extra_links;
  	unsigned int i;
  
  	links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
  	if (links == NULL)
  		return -ENOMEM;
  
  	entity->group_id = 0;
  	entity->max_links = max_links;
  	entity->num_links = 0;
  	entity->num_backlinks = 0;
  	entity->num_pads = num_pads;
  	entity->pads = pads;
  	entity->links = links;
  
  	for (i = 0; i < num_pads; i++) {
  		pads[i].entity = entity;
  		pads[i].index = i;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(media_entity_init);
  
  void
  media_entity_cleanup(struct media_entity *entity)
  {
  	kfree(entity->links);
  }
  EXPORT_SYMBOL_GPL(media_entity_cleanup);
  
  /* -----------------------------------------------------------------------------
   * 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_entity_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 = 0;
  	graph->stack[graph->top].entity = entity;
  }
  
  static struct media_entity *stack_pop(struct media_entity_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_entity_graph_walk_start - Start walking the media graph at a given entity
   * @graph: Media graph structure that will be used to walk the graph
   * @entity: Starting entity
   *
   * This function initializes the graph traversal structure to walk the entities
   * graph starting at the given entity. The traversal structure must not be
   * modified by the caller during graph traversal. When done the structure can
   * safely be freed.
   */
  void media_entity_graph_walk_start(struct media_entity_graph *graph,
  				   struct media_entity *entity)
  {
  	graph->top = 0;
  	graph->stack[graph->top].entity = NULL;
  	bitmap_zero(graph->entities, MEDIA_ENTITY_ENUM_MAX_ID);
  
  	if (WARN_ON(entity->id >= MEDIA_ENTITY_ENUM_MAX_ID))
  		return;
  
  	__set_bit(entity->id, graph->entities);
  	stack_push(graph, entity);
  }
  EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
  
  /**
   * media_entity_graph_walk_next - Get the next entity in the graph
   * @graph: Media graph structure
   *
   * Perform a depth-first traversal of the given media entities graph.
   *
   * The graph structure must have been previously initialized with a call to
   * media_entity_graph_walk_start().
   *
   * Return the next entity in the graph or NULL if the whole graph have been
   * traversed.
   */
  struct media_entity *
  media_entity_graph_walk_next(struct media_entity_graph *graph)
  {
  	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)->num_links) {
  		struct media_entity *entity = stack_top(graph);
  		struct media_link *link = &entity->links[link_top(graph)];
  		struct media_entity *next;
  
  		/* The link is not enabled so we do not follow. */
  		if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
  			link_top(graph)++;
  			continue;
  		}
  
  		/* Get the entity in the other end of the link . */
  		next = media_entity_other(entity, link);
  		if (WARN_ON(next->id >= MEDIA_ENTITY_ENUM_MAX_ID))
  			return NULL;
  
  		/* Has the entity already been visited? */
  		if (__test_and_set_bit(next->id, graph->entities)) {
  			link_top(graph)++;
  			continue;
  		}
  
  		/* Push the new entity to stack and start over. */
  		link_top(graph)++;
  		stack_push(graph, next);
  	}
  
  	return stack_pop(graph);
  }
  EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
  
  /* -----------------------------------------------------------------------------
   * Pipeline management
   */
  
  /**
   * media_entity_pipeline_start - Mark a pipeline as streaming
   * @entity: Starting entity
   * @pipe: Media pipeline to be assigned to all entities in the pipeline.
   *
   * Mark all entities connected to a given entity through enabled links, either
   * directly or indirectly, as streaming. The given pipeline object is assigned to
   * every entity in the pipeline and stored in the media_entity pipe field.
   *
   * Calls to this function can be nested, in which case the same number of
   * media_entity_pipeline_stop() calls will be required to stop streaming. The
   * pipeline pointer must be identical for all nested calls to
   * media_entity_pipeline_start().
   */
  __must_check int media_entity_pipeline_start(struct media_entity *entity,
  					     struct media_pipeline *pipe)
  {
  	struct media_device *mdev = entity->parent;
  	struct media_entity_graph graph;
  	struct media_entity *entity_err = entity;
  	int ret;
  
  	mutex_lock(&mdev->graph_mutex);
  
  	media_entity_graph_walk_start(&graph, entity);
  
  	while ((entity = media_entity_graph_walk_next(&graph))) {
  		DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
  		DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
  		unsigned int i;
  
  		entity->stream_count++;
  		WARN_ON(entity->pipe && entity->pipe != pipe);
  		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);
  
  		for (i = 0; i < entity->num_links; i++) {
  			struct media_link *link = &entity->links[i];
  			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->parent->dev,
  					"link validation failed for \"%s\":%u -> \"%s\":%u, error %d
  ",
  					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 = -EPIPE;
  			dev_dbg(entity->parent->dev,
  				"\"%s\":%u must be connected by an enabled link
  ",
  				entity->name,
  				(unsigned)find_first_zero_bit(
  					active, entity->num_pads));
  			goto error;
  		}
  	}
  
  	mutex_unlock(&mdev->graph_mutex);
  
  	return 0;
  
  error:
  	/*
  	 * Link validation on graph failed. We revert what we did and
  	 * return the error.
  	 */
  	media_entity_graph_walk_start(&graph, entity_err);
  
  	while ((entity_err = media_entity_graph_walk_next(&graph))) {
  		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;
  	}
  
  	mutex_unlock(&mdev->graph_mutex);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
  
  /**
   * media_entity_pipeline_stop - Mark a pipeline as not streaming
   * @entity: Starting entity
   *
   * Mark all entities connected to a given entity through enabled links, either
   * directly or indirectly, as not streaming. The media_entity pipe field is
   * reset to NULL.
   *
   * If multiple calls to media_entity_pipeline_start() have been made, the same
   * number of calls to this function are required to mark the pipeline as not
   * streaming.
   */
  void media_entity_pipeline_stop(struct media_entity *entity)
  {
  	struct media_device *mdev = entity->parent;
  	struct media_entity_graph graph;
  
  	mutex_lock(&mdev->graph_mutex);
  
  	media_entity_graph_walk_start(&graph, entity);
  
  	while ((entity = media_entity_graph_walk_next(&graph))) {
  		entity->stream_count--;
  		if (entity->stream_count == 0)
  			entity->pipe = NULL;
  	}
  
  	mutex_unlock(&mdev->graph_mutex);
  }
  EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
  
  /* -----------------------------------------------------------------------------
   * Module use count
   */
  
  /*
   * media_entity_get - Get a reference to the parent module
   * @entity: The entity
   *
   * Get a reference to the parent media device module.
   *
   * The function will return immediately if @entity is NULL.
   *
   * Return a pointer to the entity on success or NULL on failure.
   */
  struct media_entity *media_entity_get(struct media_entity *entity)
  {
  	if (entity == NULL)
  		return NULL;
  
  	if (entity->parent->dev &&
  	    !try_module_get(entity->parent->dev->driver->owner))
  		return NULL;
  
  	return entity;
  }
  EXPORT_SYMBOL_GPL(media_entity_get);
  
  /*
   * media_entity_put - Release the reference to the parent module
   * @entity: The entity
   *
   * Release the reference count acquired by media_entity_get().
   *
   * The function will return immediately if @entity is NULL.
   */
  void media_entity_put(struct media_entity *entity)
  {
  	if (entity == NULL)
  		return;
  
  	if (entity->parent->dev)
  		module_put(entity->parent->dev->driver->owner);
  }
  EXPORT_SYMBOL_GPL(media_entity_put);
  
  /* -----------------------------------------------------------------------------
   * Links management
   */
  
  static struct media_link *media_entity_add_link(struct media_entity *entity)
  {
  	if (entity->num_links >= entity->max_links) {
  		struct media_link *links = entity->links;
  		unsigned int max_links = entity->max_links + 2;
  		unsigned int i;
  
  		links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
  		if (links == NULL)
  			return NULL;
  
  		for (i = 0; i < entity->num_links; i++)
  			links[i].reverse->reverse = &links[i];
  
  		entity->max_links = max_links;
  		entity->links = links;
  	}
  
  	return &entity->links[entity->num_links++];
  }
  
  int
  media_entity_create_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_entity_add_link(source);
  	if (link == NULL)
  		return -ENOMEM;
  
  	link->source = &source->pads[source_pad];
  	link->sink = &sink->pads[sink_pad];
  	link->flags = flags;
  
  	/* Create the backlink. Backlinks are used to help graph traversal and
  	 * are not reported to userspace.
  	 */
  	backlink = media_entity_add_link(sink);
  	if (backlink == NULL) {
  		source->num_links--;
  		return -ENOMEM;
  	}
  
  	backlink->source = &source->pads[source_pad];
  	backlink->sink = &sink->pads[sink_pad];
  	backlink->flags = flags;
  
  	link->reverse = backlink;
  	backlink->reverse = link;
  
  	sink->num_backlinks++;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(media_entity_create_link);
  
  void __media_entity_remove_links(struct media_entity *entity)
  {
  	unsigned int i;
  
  	for (i = 0; i < entity->num_links; i++) {
  		struct media_link *link = &entity->links[i];
  		struct media_entity *remote;
  		unsigned int r = 0;
  
  		if (link->source->entity == entity)
  			remote = link->sink->entity;
  		else
  			remote = link->source->entity;
  
  		while (r < remote->num_links) {
  			struct media_link *rlink = &remote->links[r];
  
  			if (rlink != link->reverse) {
  				r++;
  				continue;
  			}
  
  			if (link->source->entity == entity)
  				remote->num_backlinks--;
  
  			if (--remote->num_links == 0)
  				break;
  
  			/* Insert last entry in place of the dropped link. */
  			*rlink = remote->links[remote->num_links];
  		}
  	}
  
  	entity->num_links = 0;
  	entity->num_backlinks = 0;
  }
  EXPORT_SYMBOL_GPL(__media_entity_remove_links);
  
  void media_entity_remove_links(struct media_entity *entity)
  {
  	/* Do nothing if the entity is not registered. */
  	if (entity->parent == NULL)
  		return;
  
  	mutex_lock(&entity->parent->graph_mutex);
  	__media_entity_remove_links(entity);
  	mutex_unlock(&entity->parent->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;
  }
  
  /**
   * __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)
  {
  	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->parent;
  
  	if (mdev->link_notify) {
  		ret = mdev->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->link_notify)
  		mdev->link_notify(link, flags, MEDIA_DEV_NOTIFY_POST_LINK_CH);
  
  	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_pad - Find the pad at the remote end of a link
   * @pad: Pad at the local end of the link
   *
   * Search for a remote pad connected to the given 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_pad(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_pad);