- 根目录:
- 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>
#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 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);
/* -----------------------------------------------------------------------------
* 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().
*/
void media_entity_pipeline_start(struct media_entity *entity,
struct media_pipeline *pipe)
{
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++;
WARN_ON(entity->pipe && entity->pipe != pipe);
entity->pipe = pipe;
}
mutex_unlock(&mdev->graph_mutex);
}
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);
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 ((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);
/**
* 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_source - Find the source pad at the remote end of a link
* @pad: Sink pad at the local end of the link
*
* Search for a remote source pad connected to the given sink 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_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);