4 * Copyright (C) 2010 Nokia Corporation
6 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
7 * Sakari Ailus <sakari.ailus@iki.fi>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 #include <linux/module.h>
24 #include <linux/slab.h>
25 #include <media/media-entity.h>
26 #include <media/media-device.h>
29 * media_entity_init - Initialize a media entity
31 * @num_pads: Total number of sink and source pads.
32 * @extra_links: Initial estimate of the number of extra links.
33 * @pads: Array of 'num_pads' pads.
35 * The total number of pads is an intrinsic property of entities known by the
36 * entity driver, while the total number of links depends on hardware design
37 * and is an extrinsic property unknown to the entity driver. However, in most
38 * use cases the entity driver can guess the number of links which can safely
39 * be assumed to be equal to or larger than the number of pads.
41 * For those reasons the links array can be preallocated based on the entity
42 * driver guess and will be reallocated later if extra links need to be
45 * This function allocates a links array with enough space to hold at least
46 * 'num_pads' + 'extra_links' elements. The media_entity::max_links field will
47 * be set to the number of allocated elements.
49 * The pads array is managed by the entity driver and passed to
50 * media_entity_init() where its pointer will be stored in the entity structure.
53 media_entity_init(struct media_entity *entity, u16 num_pads,
54 struct media_pad *pads, u16 extra_links)
56 struct media_link *links;
57 unsigned int max_links = num_pads + extra_links;
60 links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
65 entity->max_links = max_links;
66 entity->num_links = 0;
67 entity->num_backlinks = 0;
68 entity->num_pads = num_pads;
70 entity->links = links;
72 for (i = 0; i < num_pads; i++) {
73 pads[i].entity = entity;
79 EXPORT_SYMBOL_GPL(media_entity_init);
82 media_entity_cleanup(struct media_entity *entity)
86 EXPORT_SYMBOL_GPL(media_entity_cleanup);
88 /* -----------------------------------------------------------------------------
92 static struct media_entity *
93 media_entity_other(struct media_entity *entity, struct media_link *link)
95 if (link->source->entity == entity)
96 return link->sink->entity;
98 return link->source->entity;
101 /* push an entity to traversal stack */
102 static void stack_push(struct media_entity_graph *graph,
103 struct media_entity *entity)
105 if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
110 graph->stack[graph->top].link = 0;
111 graph->stack[graph->top].entity = entity;
114 static struct media_entity *stack_pop(struct media_entity_graph *graph)
116 struct media_entity *entity;
118 entity = graph->stack[graph->top].entity;
124 #define stack_peek(en) ((en)->stack[(en)->top - 1].entity)
125 #define link_top(en) ((en)->stack[(en)->top].link)
126 #define stack_top(en) ((en)->stack[(en)->top].entity)
129 * media_entity_graph_walk_start - Start walking the media graph at a given entity
130 * @graph: Media graph structure that will be used to walk the graph
131 * @entity: Starting entity
133 * This function initializes the graph traversal structure to walk the entities
134 * graph starting at the given entity. The traversal structure must not be
135 * modified by the caller during graph traversal. When done the structure can
138 void media_entity_graph_walk_start(struct media_entity_graph *graph,
139 struct media_entity *entity)
142 graph->stack[graph->top].entity = NULL;
143 stack_push(graph, entity);
145 EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
148 * media_entity_graph_walk_next - Get the next entity in the graph
149 * @graph: Media graph structure
151 * Perform a depth-first traversal of the given media entities graph.
153 * The graph structure must have been previously initialized with a call to
154 * media_entity_graph_walk_start().
156 * Return the next entity in the graph or NULL if the whole graph have been
159 struct media_entity *
160 media_entity_graph_walk_next(struct media_entity_graph *graph)
162 if (stack_top(graph) == NULL)
166 * Depth first search. Push entity to stack and continue from
167 * top of the stack until no more entities on the level can be
170 while (link_top(graph) < stack_top(graph)->num_links) {
171 struct media_entity *entity = stack_top(graph);
172 struct media_link *link = &entity->links[link_top(graph)];
173 struct media_entity *next;
175 /* The link is not enabled so we do not follow. */
176 if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
181 /* Get the entity in the other end of the link . */
182 next = media_entity_other(entity, link);
184 /* Was it the entity we came here from? */
185 if (next == stack_peek(graph)) {
190 /* Push the new entity to stack and start over. */
192 stack_push(graph, next);
195 return stack_pop(graph);
197 EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
199 /* -----------------------------------------------------------------------------
204 * media_entity_get - Get a reference to the parent module
205 * @entity: The entity
207 * Get a reference to the parent media device module.
209 * The function will return immediately if @entity is NULL.
211 * Return a pointer to the entity on success or NULL on failure.
213 struct media_entity *media_entity_get(struct media_entity *entity)
218 if (entity->parent->dev &&
219 !try_module_get(entity->parent->dev->driver->owner))
224 EXPORT_SYMBOL_GPL(media_entity_get);
227 * media_entity_put - Release the reference to the parent module
228 * @entity: The entity
230 * Release the reference count acquired by media_entity_get().
232 * The function will return immediately if @entity is NULL.
234 void media_entity_put(struct media_entity *entity)
239 if (entity->parent->dev)
240 module_put(entity->parent->dev->driver->owner);
242 EXPORT_SYMBOL_GPL(media_entity_put);
244 /* -----------------------------------------------------------------------------
248 static struct media_link *media_entity_add_link(struct media_entity *entity)
250 if (entity->num_links >= entity->max_links) {
251 struct media_link *links = entity->links;
252 unsigned int max_links = entity->max_links + 2;
255 links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
259 for (i = 0; i < entity->num_links; i++)
260 links[i].reverse->reverse = &links[i];
262 entity->max_links = max_links;
263 entity->links = links;
266 return &entity->links[entity->num_links++];
270 media_entity_create_link(struct media_entity *source, u16 source_pad,
271 struct media_entity *sink, u16 sink_pad, u32 flags)
273 struct media_link *link;
274 struct media_link *backlink;
276 BUG_ON(source == NULL || sink == NULL);
277 BUG_ON(source_pad >= source->num_pads);
278 BUG_ON(sink_pad >= sink->num_pads);
280 link = media_entity_add_link(source);
284 link->source = &source->pads[source_pad];
285 link->sink = &sink->pads[sink_pad];
288 /* Create the backlink. Backlinks are used to help graph traversal and
289 * are not reported to userspace.
291 backlink = media_entity_add_link(sink);
292 if (backlink == NULL) {
297 backlink->source = &source->pads[source_pad];
298 backlink->sink = &sink->pads[sink_pad];
299 backlink->flags = flags;
301 link->reverse = backlink;
302 backlink->reverse = link;
304 sink->num_backlinks++;
308 EXPORT_SYMBOL_GPL(media_entity_create_link);