media-entity.c

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/*
 * Media entity
 *
 * Copyright (C) 2010 Nokia Corporation
 *
 * Contacts: Laurent Pinchart <[email protected]>
 *       Sakari Ailus <[email protected]>
 *
 * 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>
#include <media/media-device.h>

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)

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);

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);

/* -----------------------------------------------------------------------------
 * Pipeline management
 */

__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))) {
        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;

        for (i = 0; i < entity->num_links; i++) {
            struct media_link *link = &entity->links[i];

            /* Is this pad part of an enabled link? */
            if (!(link->flags & MEDIA_LNK_FL_ENABLED))
                continue;

            /* Are we the sink or not? */
            if (link->sink->entity != entity)
                continue;

            ret = entity->ops->link_validate(link);
            if (ret < 0 && ret != -ENOIOCTLCMD)
                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);

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);

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;
}

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 ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify) {
        ret = mdev->link_notify(link->source, link->sink,
                    MEDIA_LNK_FL_ENABLED);
        if (ret < 0)
            return ret;
    }

    ret = __media_entity_setup_link_notify(link, flags);
    if (ret < 0)
        goto err;

    if (!(flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify)
        mdev->link_notify(link->source, link->sink, 0);

    return 0;

err:
    if ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify)
        mdev->link_notify(link->source, link->sink, 0);

    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);

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);

struct media_pad *media_entity_remote_source(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_source);