[deliverable/linux.git] / drivers / media / media-entity.c

/*
 * 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/module.h>
#include <linux/slab.h>
#include <media/media-entity.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 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);
Commit	Line	Data
53e269c1 LP	1	/*
	2	* Media entity
	3	*
	4	* Copyright (C) 2010 Nokia Corporation
	5	*
	6	* Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
	7	* Sakari Ailus <sakari.ailus@iki.fi>
	8	*
	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.
	12	*
	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.
	17	*
	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
	21	*/
	22
	23	#include <linux/module.h>
	24	#include <linux/slab.h>
	25	#include <media/media-entity.h>
	26
	27	/**
	28	* media_entity_init - Initialize a media entity
	29	*
	30	* @num_pads: Total number of sink and source pads.
	31	* @extra_links: Initial estimate of the number of extra links.
	32	* @pads: Array of 'num_pads' pads.
	33	*
	34	* The total number of pads is an intrinsic property of entities known by the
	35	* entity driver, while the total number of links depends on hardware design
	36	* and is an extrinsic property unknown to the entity driver. However, in most
	37	* use cases the entity driver can guess the number of links which can safely
	38	* be assumed to be equal to or larger than the number of pads.
	39	*
	40	* For those reasons the links array can be preallocated based on the entity
	41	* driver guess and will be reallocated later if extra links need to be
	42	* created.
	43	*
	44	* This function allocates a links array with enough space to hold at least
	45	* 'num_pads' + 'extra_links' elements. The media_entity::max_links field will
	46	* be set to the number of allocated elements.
	47	*
	48	* The pads array is managed by the entity driver and passed to
	49	* media_entity_init() where its pointer will be stored in the entity structure.
	50	*/
	51	int
	52	media_entity_init(struct media_entity *entity, u16 num_pads,
	53	struct media_pad *pads, u16 extra_links)
	54	{
	55	struct media_link *links;
	56	unsigned int max_links = num_pads + extra_links;
	57	unsigned int i;
	58
	59	links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
	60	if (links == NULL)
	61	return -ENOMEM;
	62
	63	entity->group_id = 0;
	64	entity->max_links = max_links;
65	entity->num_links = 0;
66	entity->num_backlinks = 0;
67	entity->num_pads = num_pads;
68	entity->pads = pads;
69	entity->links = links;
70
71	for (i = 0; i < num_pads; i++) {
72	pads[i].entity = entity;
73	pads[i].index = i;
74	}
75
76	return 0;
77	}
78	EXPORT_SYMBOL_GPL(media_entity_init);
79
80	void
81	media_entity_cleanup(struct media_entity *entity)
82	{
83	kfree(entity->links);
84	}
85	EXPORT_SYMBOL_GPL(media_entity_cleanup);
86
a5ccc48a SA	87	/* -----------------------------------------------------------------------------
	88	* Graph traversal
	89	*/
	90
	91	static struct media_entity *
	92	media_entity_other(struct media_entity entity, struct media_link link)
	93	{
	94	if (link->source->entity == entity)
	95	return link->sink->entity;
	96	else
	97	return link->source->entity;
	98	}
	99
	100	/* push an entity to traversal stack */
	101	static void stack_push(struct media_entity_graph *graph,
	102	struct media_entity *entity)
	103	{
	104	if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
	105	WARN_ON(1);
	106	return;
	107	}
	108	graph->top++;
	109	graph->stack[graph->top].link = 0;
	110	graph->stack[graph->top].entity = entity;
	111	}
	112
	113	static struct media_entity stack_pop(struct media_entity_graph graph)
	114	{
	115	struct media_entity *entity;
	116
	117	entity = graph->stack[graph->top].entity;
	118	graph->top--;
	119
	120	return entity;
	121	}
	122
	123	#define stack_peek(en) ((en)->stack[(en)->top - 1].entity)
	124	#define link_top(en) ((en)->stack[(en)->top].link)
	125	#define stack_top(en) ((en)->stack[(en)->top].entity)
	126
	127	/**
	128	* media_entity_graph_walk_start - Start walking the media graph at a given entity
	129	* @graph: Media graph structure that will be used to walk the graph
	130	* @entity: Starting entity
	131	*
	132	* This function initializes the graph traversal structure to walk the entities
	133	* graph starting at the given entity. The traversal structure must not be
	134	* modified by the caller during graph traversal. When done the structure can
	135	* safely be freed.
	136	*/
	137	void media_entity_graph_walk_start(struct media_entity_graph *graph,
	138	struct media_entity *entity)
	139	{
	140	graph->top = 0;
	141	graph->stack[graph->top].entity = NULL;
	142	stack_push(graph, entity);
	143	}
	144	EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
	145
	146	/**
	147	* media_entity_graph_walk_next - Get the next entity in the graph
	148	* @graph: Media graph structure
	149	*
	150	* Perform a depth-first traversal of the given media entities graph.
151	*
152	* The graph structure must have been previously initialized with a call to
153	* media_entity_graph_walk_start().
154	*
155	* Return the next entity in the graph or NULL if the whole graph have been
156	* traversed.
157	*/
158	struct media_entity *
159	media_entity_graph_walk_next(struct media_entity_graph *graph)
160	{
161	if (stack_top(graph) == NULL)
162	return NULL;
163
164	/*
165	* Depth first search. Push entity to stack and continue from
166	* top of the stack until no more entities on the level can be
167	* found.
168	*/
169	while (link_top(graph) < stack_top(graph)->num_links) {
170	struct media_entity *entity = stack_top(graph);
171	struct media_link *link = &entity->links[link_top(graph)];
172	struct media_entity *next;
173
174	/* The link is not enabled so we do not follow. */
175	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
176	link_top(graph)++;
177	continue;
178	}
179
180	/* Get the entity in the other end of the link . */
181	next = media_entity_other(entity, link);
182
183	/* Was it the entity we came here from? */
184	if (next == stack_peek(graph)) {
185	link_top(graph)++;
186	continue;
187	}
188
189	/* Push the new entity to stack and start over. */
190	link_top(graph)++;
191	stack_push(graph, next);
192	}
193
194	return stack_pop(graph);
195	}
196	EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
197
198	/* -----------------------------------------------------------------------------
199	* Links management
200	*/
201
53e269c1 LP	202	static struct media_link media_entity_add_link(struct media_entity entity)
	203	{
	204	if (entity->num_links >= entity->max_links) {
	205	struct media_link *links = entity->links;
	206	unsigned int max_links = entity->max_links + 2;
	207	unsigned int i;
	208
	209	links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
	210	if (links == NULL)
	211	return NULL;
	212
	213	for (i = 0; i < entity->num_links; i++)
	214	links[i].reverse->reverse = &links[i];
	215
	216	entity->max_links = max_links;
	217	entity->links = links;
	218	}
	219
	220	return &entity->links[entity->num_links++];
	221	}
	222
	223	int
	224	media_entity_create_link(struct media_entity *source, u16 source_pad,
	225	struct media_entity *sink, u16 sink_pad, u32 flags)
	226	{
	227	struct media_link *link;
	228	struct media_link *backlink;
	229
	230	BUG_ON(source == NULL \|\| sink == NULL);
	231	BUG_ON(source_pad >= source->num_pads);
	232	BUG_ON(sink_pad >= sink->num_pads);
	233
	234	link = media_entity_add_link(source);
	235	if (link == NULL)
	236	return -ENOMEM;
	237
	238	link->source = &source->pads[source_pad];
	239	link->sink = &sink->pads[sink_pad];
	240	link->flags = flags;
	241
	242	/* Create the backlink. Backlinks are used to help graph traversal and
	243	* are not reported to userspace.
	244	*/
	245	backlink = media_entity_add_link(sink);
	246	if (backlink == NULL) {
	247	source->num_links--;
	248	return -ENOMEM;
	249	}
	250
	251	backlink->source = &source->pads[source_pad];
	252	backlink->sink = &sink->pads[sink_pad];
	253	backlink->flags = flags;
	254
	255	link->reverse = backlink;
	256	backlink->reverse = link;
	257
	258	sink->num_backlinks++;
	259
	260	return 0;
	261	}
	262	EXPORT_SYMBOL_GPL(media_entity_create_link);