/* * Media entity * * Copyright (C) 2010 Nokia Corporation * * Contacts: Laurent Pinchart * Sakari Ailus * * 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 #include #include /** * 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 stack_peek(en) ((en)->stack[(en)->top - 1].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; 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); /* Was it the entity we came here from? */ if (next == stack_peek(graph)) { 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); /* ----------------------------------------------------------------------------- * 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);