linux/drivers/media/media-entity.c
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   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#include <media/media-device.h>
  27
  28/**
  29 * media_entity_init - Initialize a media entity
  30 *
  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.
  34 *
  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.
  40 *
  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
  43 * created.
  44 *
  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.
  48 *
  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.
  51 */
  52int
  53media_entity_init(struct media_entity *entity, u16 num_pads,
  54                  struct media_pad *pads, u16 extra_links)
  55{
  56        struct media_link *links;
  57        unsigned int max_links = num_pads + extra_links;
  58        unsigned int i;
  59
  60        links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
  61        if (links == NULL)
  62                return -ENOMEM;
  63
  64        entity->group_id = 0;
  65        entity->max_links = max_links;
  66        entity->num_links = 0;
  67        entity->num_backlinks = 0;
  68        entity->num_pads = num_pads;
  69        entity->pads = pads;
  70        entity->links = links;
  71
  72        for (i = 0; i < num_pads; i++) {
  73                pads[i].entity = entity;
  74                pads[i].index = i;
  75        }
  76
  77        return 0;
  78}
  79EXPORT_SYMBOL_GPL(media_entity_init);
  80
  81void
  82media_entity_cleanup(struct media_entity *entity)
  83{
  84        kfree(entity->links);
  85}
  86EXPORT_SYMBOL_GPL(media_entity_cleanup);
  87
  88/* -----------------------------------------------------------------------------
  89 * Graph traversal
  90 */
  91
  92static struct media_entity *
  93media_entity_other(struct media_entity *entity, struct media_link *link)
  94{
  95        if (link->source->entity == entity)
  96                return link->sink->entity;
  97        else
  98                return link->source->entity;
  99}
 100
 101/* push an entity to traversal stack */
 102static void stack_push(struct media_entity_graph *graph,
 103                       struct media_entity *entity)
 104{
 105        if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
 106                WARN_ON(1);
 107                return;
 108        }
 109        graph->top++;
 110        graph->stack[graph->top].link = 0;
 111        graph->stack[graph->top].entity = entity;
 112}
 113
 114static struct media_entity *stack_pop(struct media_entity_graph *graph)
 115{
 116        struct media_entity *entity;
 117
 118        entity = graph->stack[graph->top].entity;
 119        graph->top--;
 120
 121        return entity;
 122}
 123
 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)
 127
 128/**
 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
 132 *
 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
 136 * safely be freed.
 137 */
 138void media_entity_graph_walk_start(struct media_entity_graph *graph,
 139                                   struct media_entity *entity)
 140{
 141        graph->top = 0;
 142        graph->stack[graph->top].entity = NULL;
 143        stack_push(graph, entity);
 144}
 145EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
 146
 147/**
 148 * media_entity_graph_walk_next - Get the next entity in the graph
 149 * @graph: Media graph structure
 150 *
 151 * Perform a depth-first traversal of the given media entities graph.
 152 *
 153 * The graph structure must have been previously initialized with a call to
 154 * media_entity_graph_walk_start().
 155 *
 156 * Return the next entity in the graph or NULL if the whole graph have been
 157 * traversed.
 158 */
 159struct media_entity *
 160media_entity_graph_walk_next(struct media_entity_graph *graph)
 161{
 162        if (stack_top(graph) == NULL)
 163                return NULL;
 164
 165        /*
 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
 168         * found.
 169         */
 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;
 174
 175                /* The link is not enabled so we do not follow. */
 176                if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
 177                        link_top(graph)++;
 178                        continue;
 179                }
 180
 181                /* Get the entity in the other end of the link . */
 182                next = media_entity_other(entity, link);
 183
 184                /* Was it the entity we came here from? */
 185                if (next == stack_peek(graph)) {
 186                        link_top(graph)++;
 187                        continue;
 188                }
 189
 190                /* Push the new entity to stack and start over. */
 191                link_top(graph)++;
 192                stack_push(graph, next);
 193        }
 194
 195        return stack_pop(graph);
 196}
 197EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
 198
 199/* -----------------------------------------------------------------------------
 200 * Pipeline management
 201 */
 202
 203/**
 204 * media_entity_pipeline_start - Mark a pipeline as streaming
 205 * @entity: Starting entity
 206 * @pipe: Media pipeline to be assigned to all entities in the pipeline.
 207 *
 208 * Mark all entities connected to a given entity through enabled links, either
 209 * directly or indirectly, as streaming. The given pipeline object is assigned to
 210 * every entity in the pipeline and stored in the media_entity pipe field.
 211 *
 212 * Calls to this function can be nested, in which case the same number of
 213 * media_entity_pipeline_stop() calls will be required to stop streaming. The
 214 * pipeline pointer must be identical for all nested calls to
 215 * media_entity_pipeline_start().
 216 */
 217__must_check int media_entity_pipeline_start(struct media_entity *entity,
 218                                             struct media_pipeline *pipe)
 219{
 220        struct media_device *mdev = entity->parent;
 221        struct media_entity_graph graph;
 222        struct media_entity *entity_err = entity;
 223        int ret;
 224
 225        mutex_lock(&mdev->graph_mutex);
 226
 227        media_entity_graph_walk_start(&graph, entity);
 228
 229        while ((entity = media_entity_graph_walk_next(&graph))) {
 230                unsigned int i;
 231
 232                entity->stream_count++;
 233                WARN_ON(entity->pipe && entity->pipe != pipe);
 234                entity->pipe = pipe;
 235
 236                /* Already streaming --- no need to check. */
 237                if (entity->stream_count > 1)
 238                        continue;
 239
 240                if (!entity->ops || !entity->ops->link_validate)
 241                        continue;
 242
 243                for (i = 0; i < entity->num_links; i++) {
 244                        struct media_link *link = &entity->links[i];
 245
 246                        /* Is this pad part of an enabled link? */
 247                        if (!(link->flags & MEDIA_LNK_FL_ENABLED))
 248                                continue;
 249
 250                        /* Are we the sink or not? */
 251                        if (link->sink->entity != entity)
 252                                continue;
 253
 254                        ret = entity->ops->link_validate(link);
 255                        if (ret < 0 && ret != -ENOIOCTLCMD)
 256                                goto error;
 257                }
 258        }
 259
 260        mutex_unlock(&mdev->graph_mutex);
 261
 262        return 0;
 263
 264error:
 265        /*
 266         * Link validation on graph failed. We revert what we did and
 267         * return the error.
 268         */
 269        media_entity_graph_walk_start(&graph, entity_err);
 270
 271        while ((entity_err = media_entity_graph_walk_next(&graph))) {
 272                entity_err->stream_count--;
 273                if (entity_err->stream_count == 0)
 274                        entity_err->pipe = NULL;
 275
 276                /*
 277                 * We haven't increased stream_count further than this
 278                 * so we quit here.
 279                 */
 280                if (entity_err == entity)
 281                        break;
 282        }
 283
 284        mutex_unlock(&mdev->graph_mutex);
 285
 286        return ret;
 287}
 288EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
 289
 290/**
 291 * media_entity_pipeline_stop - Mark a pipeline as not streaming
 292 * @entity: Starting entity
 293 *
 294 * Mark all entities connected to a given entity through enabled links, either
 295 * directly or indirectly, as not streaming. The media_entity pipe field is
 296 * reset to NULL.
 297 *
 298 * If multiple calls to media_entity_pipeline_start() have been made, the same
 299 * number of calls to this function are required to mark the pipeline as not
 300 * streaming.
 301 */
 302void media_entity_pipeline_stop(struct media_entity *entity)
 303{
 304        struct media_device *mdev = entity->parent;
 305        struct media_entity_graph graph;
 306
 307        mutex_lock(&mdev->graph_mutex);
 308
 309        media_entity_graph_walk_start(&graph, entity);
 310
 311        while ((entity = media_entity_graph_walk_next(&graph))) {
 312                entity->stream_count--;
 313                if (entity->stream_count == 0)
 314                        entity->pipe = NULL;
 315        }
 316
 317        mutex_unlock(&mdev->graph_mutex);
 318}
 319EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
 320
 321/* -----------------------------------------------------------------------------
 322 * Module use count
 323 */
 324
 325/*
 326 * media_entity_get - Get a reference to the parent module
 327 * @entity: The entity
 328 *
 329 * Get a reference to the parent media device module.
 330 *
 331 * The function will return immediately if @entity is NULL.
 332 *
 333 * Return a pointer to the entity on success or NULL on failure.
 334 */
 335struct media_entity *media_entity_get(struct media_entity *entity)
 336{
 337        if (entity == NULL)
 338                return NULL;
 339
 340        if (entity->parent->dev &&
 341            !try_module_get(entity->parent->dev->driver->owner))
 342                return NULL;
 343
 344        return entity;
 345}
 346EXPORT_SYMBOL_GPL(media_entity_get);
 347
 348/*
 349 * media_entity_put - Release the reference to the parent module
 350 * @entity: The entity
 351 *
 352 * Release the reference count acquired by media_entity_get().
 353 *
 354 * The function will return immediately if @entity is NULL.
 355 */
 356void media_entity_put(struct media_entity *entity)
 357{
 358        if (entity == NULL)
 359                return;
 360
 361        if (entity->parent->dev)
 362                module_put(entity->parent->dev->driver->owner);
 363}
 364EXPORT_SYMBOL_GPL(media_entity_put);
 365
 366/* -----------------------------------------------------------------------------
 367 * Links management
 368 */
 369
 370static struct media_link *media_entity_add_link(struct media_entity *entity)
 371{
 372        if (entity->num_links >= entity->max_links) {
 373                struct media_link *links = entity->links;
 374                unsigned int max_links = entity->max_links + 2;
 375                unsigned int i;
 376
 377                links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
 378                if (links == NULL)
 379                        return NULL;
 380
 381                for (i = 0; i < entity->num_links; i++)
 382                        links[i].reverse->reverse = &links[i];
 383
 384                entity->max_links = max_links;
 385                entity->links = links;
 386        }
 387
 388        return &entity->links[entity->num_links++];
 389}
 390
 391int
 392media_entity_create_link(struct media_entity *source, u16 source_pad,
 393                         struct media_entity *sink, u16 sink_pad, u32 flags)
 394{
 395        struct media_link *link;
 396        struct media_link *backlink;
 397
 398        BUG_ON(source == NULL || sink == NULL);
 399        BUG_ON(source_pad >= source->num_pads);
 400        BUG_ON(sink_pad >= sink->num_pads);
 401
 402        link = media_entity_add_link(source);
 403        if (link == NULL)
 404                return -ENOMEM;
 405
 406        link->source = &source->pads[source_pad];
 407        link->sink = &sink->pads[sink_pad];
 408        link->flags = flags;
 409
 410        /* Create the backlink. Backlinks are used to help graph traversal and
 411         * are not reported to userspace.
 412         */
 413        backlink = media_entity_add_link(sink);
 414        if (backlink == NULL) {
 415                source->num_links--;
 416                return -ENOMEM;
 417        }
 418
 419        backlink->source = &source->pads[source_pad];
 420        backlink->sink = &sink->pads[sink_pad];
 421        backlink->flags = flags;
 422
 423        link->reverse = backlink;
 424        backlink->reverse = link;
 425
 426        sink->num_backlinks++;
 427
 428        return 0;
 429}
 430EXPORT_SYMBOL_GPL(media_entity_create_link);
 431
 432void __media_entity_remove_links(struct media_entity *entity)
 433{
 434        unsigned int i;
 435
 436        for (i = 0; i < entity->num_links; i++) {
 437                struct media_link *link = &entity->links[i];
 438                struct media_entity *remote;
 439                unsigned int r = 0;
 440
 441                if (link->source->entity == entity)
 442                        remote = link->sink->entity;
 443                else
 444                        remote = link->source->entity;
 445
 446                while (r < remote->num_links) {
 447                        struct media_link *rlink = &remote->links[r];
 448
 449                        if (rlink != link->reverse) {
 450                                r++;
 451                                continue;
 452                        }
 453
 454                        if (link->source->entity == entity)
 455                                remote->num_backlinks--;
 456
 457                        if (--remote->num_links == 0)
 458                                break;
 459
 460                        /* Insert last entry in place of the dropped link. */
 461                        *rlink = remote->links[remote->num_links];
 462                }
 463        }
 464
 465        entity->num_links = 0;
 466        entity->num_backlinks = 0;
 467}
 468EXPORT_SYMBOL_GPL(__media_entity_remove_links);
 469
 470void media_entity_remove_links(struct media_entity *entity)
 471{
 472        /* Do nothing if the entity is not registered. */
 473        if (entity->parent == NULL)
 474                return;
 475
 476        mutex_lock(&entity->parent->graph_mutex);
 477        __media_entity_remove_links(entity);
 478        mutex_unlock(&entity->parent->graph_mutex);
 479}
 480EXPORT_SYMBOL_GPL(media_entity_remove_links);
 481
 482static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
 483{
 484        int ret;
 485
 486        /* Notify both entities. */
 487        ret = media_entity_call(link->source->entity, link_setup,
 488                                link->source, link->sink, flags);
 489        if (ret < 0 && ret != -ENOIOCTLCMD)
 490                return ret;
 491
 492        ret = media_entity_call(link->sink->entity, link_setup,
 493                                link->sink, link->source, flags);
 494        if (ret < 0 && ret != -ENOIOCTLCMD) {
 495                media_entity_call(link->source->entity, link_setup,
 496                                  link->source, link->sink, link->flags);
 497                return ret;
 498        }
 499
 500        link->flags = flags;
 501        link->reverse->flags = link->flags;
 502
 503        return 0;
 504}
 505
 506/**
 507 * __media_entity_setup_link - Configure a media link
 508 * @link: The link being configured
 509 * @flags: Link configuration flags
 510 *
 511 * The bulk of link setup is handled by the two entities connected through the
 512 * link. This function notifies both entities of the link configuration change.
 513 *
 514 * If the link is immutable or if the current and new configuration are
 515 * identical, return immediately.
 516 *
 517 * The user is expected to hold link->source->parent->mutex. If not,
 518 * media_entity_setup_link() should be used instead.
 519 */
 520int __media_entity_setup_link(struct media_link *link, u32 flags)
 521{
 522        const u32 mask = MEDIA_LNK_FL_ENABLED;
 523        struct media_device *mdev;
 524        struct media_entity *source, *sink;
 525        int ret = -EBUSY;
 526
 527        if (link == NULL)
 528                return -EINVAL;
 529
 530        /* The non-modifiable link flags must not be modified. */
 531        if ((link->flags & ~mask) != (flags & ~mask))
 532                return -EINVAL;
 533
 534        if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
 535                return link->flags == flags ? 0 : -EINVAL;
 536
 537        if (link->flags == flags)
 538                return 0;
 539
 540        source = link->source->entity;
 541        sink = link->sink->entity;
 542
 543        if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
 544            (source->stream_count || sink->stream_count))
 545                return -EBUSY;
 546
 547        mdev = source->parent;
 548
 549        if (mdev->link_notify) {
 550                ret = mdev->link_notify(link, flags,
 551                                        MEDIA_DEV_NOTIFY_PRE_LINK_CH);
 552                if (ret < 0)
 553                        return ret;
 554        }
 555
 556        ret = __media_entity_setup_link_notify(link, flags);
 557
 558        if (mdev->link_notify)
 559                mdev->link_notify(link, flags, MEDIA_DEV_NOTIFY_POST_LINK_CH);
 560
 561        return ret;
 562}
 563
 564int media_entity_setup_link(struct media_link *link, u32 flags)
 565{
 566        int ret;
 567
 568        mutex_lock(&link->source->entity->parent->graph_mutex);
 569        ret = __media_entity_setup_link(link, flags);
 570        mutex_unlock(&link->source->entity->parent->graph_mutex);
 571
 572        return ret;
 573}
 574EXPORT_SYMBOL_GPL(media_entity_setup_link);
 575
 576/**
 577 * media_entity_find_link - Find a link between two pads
 578 * @source: Source pad
 579 * @sink: Sink pad
 580 *
 581 * Return a pointer to the link between the two entities. If no such link
 582 * exists, return NULL.
 583 */
 584struct media_link *
 585media_entity_find_link(struct media_pad *source, struct media_pad *sink)
 586{
 587        struct media_link *link;
 588        unsigned int i;
 589
 590        for (i = 0; i < source->entity->num_links; ++i) {
 591                link = &source->entity->links[i];
 592
 593                if (link->source->entity == source->entity &&
 594                    link->source->index == source->index &&
 595                    link->sink->entity == sink->entity &&
 596                    link->sink->index == sink->index)
 597                        return link;
 598        }
 599
 600        return NULL;
 601}
 602EXPORT_SYMBOL_GPL(media_entity_find_link);
 603
 604/**
 605 * media_entity_remote_pad - Find the pad at the remote end of a link
 606 * @pad: Pad at the local end of the link
 607 *
 608 * Search for a remote pad connected to the given pad by iterating over all
 609 * links originating or terminating at that pad until an enabled link is found.
 610 *
 611 * Return a pointer to the pad at the remote end of the first found enabled
 612 * link, or NULL if no enabled link has been found.
 613 */
 614struct media_pad *media_entity_remote_pad(struct media_pad *pad)
 615{
 616        unsigned int i;
 617
 618        for (i = 0; i < pad->entity->num_links; i++) {
 619                struct media_link *link = &pad->entity->links[i];
 620
 621                if (!(link->flags & MEDIA_LNK_FL_ENABLED))
 622                        continue;
 623
 624                if (link->source == pad)
 625                        return link->sink;
 626
 627                if (link->sink == pad)
 628                        return link->source;
 629        }
 630
 631        return NULL;
 632
 633}
 634EXPORT_SYMBOL_GPL(media_entity_remote_pad);
 635
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