linux/drivers/media/media-entity.c

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[media] media: Entities, pads and links As video hardware pipelines become increasingly complex and configurable, the current hardware description through v4l2 subdevices reaches its limits. In addition to enumerating and configuring subdevices, video camera drivers need a way to discover and modify at runtime how those subdevices are connected. This is done through new elements called entities, pads and links. An entity is a basic media hardware building block. It can correspond to a large variety of logical blocks such as physical hardware devices (CMOS sensor for instance), logical hardware devices (a building block in a System-on-Chip image processing pipeline), DMA channels or physical connectors. A pad is a connection endpoint through which an entity can interact with other entities. Data (not restricted to video) produced by an entity flows from the entity's output to one or more entity inputs. Pads should not be confused with physical pins at chip boundaries. A link is a point-to-point oriented connection between two pads, either on the same entity or on different entities. Data flows from a source pad to a sink pad. Links are stored in the source entity. To make backwards graph walk faster, a copy of all links is also stored in the sink entity. The copy is known as a backlink and is only used to help graph traversal. The entity API is made of three functions: - media_entity_init() initializes an entity. The caller must provide an array of pads as well as an estimated number of links. The links array is allocated dynamically and will be reallocated if it grows beyond the initial estimate. - media_entity_cleanup() frees resources allocated for an entity. It must be called during the cleanup phase after unregistering the entity and before freeing it. - media_entity_create_link() creates a link between two entities. An entry in the link array of each entity is allocated and stores pointers to source and sink pads. When a media device is unregistered, all its entities are unregistered automatically. The code is based on Hans Verkuil <hverkuil@xs4all.nl> initial work. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2009-12-09 11:40:00 +00:00
/*
* 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] media: Entities, pads and links As video hardware pipelines become increasingly complex and configurable, the current hardware description through v4l2 subdevices reaches its limits. In addition to enumerating and configuring subdevices, video camera drivers need a way to discover and modify at runtime how those subdevices are connected. This is done through new elements called entities, pads and links. An entity is a basic media hardware building block. It can correspond to a large variety of logical blocks such as physical hardware devices (CMOS sensor for instance), logical hardware devices (a building block in a System-on-Chip image processing pipeline), DMA channels or physical connectors. A pad is a connection endpoint through which an entity can interact with other entities. Data (not restricted to video) produced by an entity flows from the entity's output to one or more entity inputs. Pads should not be confused with physical pins at chip boundaries. A link is a point-to-point oriented connection between two pads, either on the same entity or on different entities. Data flows from a source pad to a sink pad. Links are stored in the source entity. To make backwards graph walk faster, a copy of all links is also stored in the sink entity. The copy is known as a backlink and is only used to help graph traversal. The entity API is made of three functions: - media_entity_init() initializes an entity. The caller must provide an array of pads as well as an estimated number of links. The links array is allocated dynamically and will be reallocated if it grows beyond the initial estimate. - media_entity_cleanup() frees resources allocated for an entity. It must be called during the cleanup phase after unregistering the entity and before freeing it. - media_entity_create_link() creates a link between two entities. An entry in the link array of each entity is allocated and stores pointers to source and sink pads. When a media device is unregistered, all its entities are unregistered automatically. The code is based on Hans Verkuil <hverkuil@xs4all.nl> initial work. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2009-12-09 11:40:00 +00:00
/**
* 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
*/
[media] media: Entities, pads and links As video hardware pipelines become increasingly complex and configurable, the current hardware description through v4l2 subdevices reaches its limits. In addition to enumerating and configuring subdevices, video camera drivers need a way to discover and modify at runtime how those subdevices are connected. This is done through new elements called entities, pads and links. An entity is a basic media hardware building block. It can correspond to a large variety of logical blocks such as physical hardware devices (CMOS sensor for instance), logical hardware devices (a building block in a System-on-Chip image processing pipeline), DMA channels or physical connectors. A pad is a connection endpoint through which an entity can interact with other entities. Data (not restricted to video) produced by an entity flows from the entity's output to one or more entity inputs. Pads should not be confused with physical pins at chip boundaries. A link is a point-to-point oriented connection between two pads, either on the same entity or on different entities. Data flows from a source pad to a sink pad. Links are stored in the source entity. To make backwards graph walk faster, a copy of all links is also stored in the sink entity. The copy is known as a backlink and is only used to help graph traversal. The entity API is made of three functions: - media_entity_init() initializes an entity. The caller must provide an array of pads as well as an estimated number of links. The links array is allocated dynamically and will be reallocated if it grows beyond the initial estimate. - media_entity_cleanup() frees resources allocated for an entity. It must be called during the cleanup phase after unregistering the entity and before freeing it. - media_entity_create_link() creates a link between two entities. An entry in the link array of each entity is allocated and stores pointers to source and sink pads. When a media device is unregistered, all its entities are unregistered automatically. The code is based on Hans Verkuil <hverkuil@xs4all.nl> initial work. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2009-12-09 11:40:00 +00:00
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);