drivers/media/media-entity.c

   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/bitmap.h>
  24 #include <linux/module.h>
  25 #include <linux/slab.h>
  26 #include <media/media-entity.h>
  27 #include <media/media-device.h>
  28
  29 /**
  30  * media_entity_init - Initialize a media entity
  31  *
  32  * @num_pads: Total number of sink and source pads.
  33  * @extra_links: Initial estimate of the number of extra links.
  34  * @pads: Array of 'num_pads' pads.
  35  *
  36  * The total number of pads is an intrinsic property of entities known by the
  37  * entity driver, while the total number of links depends on hardware design
  38  * and is an extrinsic property unknown to the entity driver. However, in most
  39  * use cases the entity driver can guess the number of links which can safely
  40  * be assumed to be equal to or larger than the number of pads.
  41  *
  42  * For those reasons the links array can be preallocated based on the entity
  43  * driver guess and will be reallocated later if extra links need to be
  44  * created.
  45  *
  46  * This function allocates a links array with enough space to hold at least
  47  * 'num_pads' + 'extra_links' elements. The media_entity::max_links field will
  48  * be set to the number of allocated elements.
  49  *
  50  * The pads array is managed by the entity driver and passed to
  51  * media_entity_init() where its pointer will be stored in the entity structure.
  52  */
  53 int
  54 media_entity_init(struct media_entity *entity, u16 num_pads,
  55                   struct media_pad *pads, u16 extra_links)
  56 {
  57         struct media_link *links;
  58         unsigned int max_links = num_pads + extra_links;
  59         unsigned int i;
  60
  61         links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
  62         if (links == NULL)
  63                 return -ENOMEM;
  64
  65         entity->group_id = 0;
  66         entity->max_links = max_links;
  67         entity->num_links = 0;
  68         entity->num_backlinks = 0;
  69         entity->num_pads = num_pads;
  70         entity->pads = pads;
  71         entity->links = links;
  72
  73         for (i = 0; i < num_pads; i++) {
  74                 pads[i].entity = entity;
  75                 pads[i].index = i;
  76         }
  77
  78         return 0;
  79 }
  80 EXPORT_SYMBOL_GPL(media_entity_init);
  81
  82 void
  83 media_entity_cleanup(struct media_entity *entity)
  84 {
  85         kfree(entity->links);
  86 }
  87 EXPORT_SYMBOL_GPL(media_entity_cleanup);
  88
  89 /* -----------------------------------------------------------------------------
  90  * Graph traversal
  91  */
  92
  93 static struct media_entity *
  94 media_entity_other(struct media_entity *entity, struct media_link *link)
  95 {
  96         if (link->source->entity == entity)
  97                 return link->sink->entity;
  98         else
  99                 return link->source->entity;
 100 }
 101
 102 /* push an entity to traversal stack */
 103 static void stack_push(struct media_entity_graph *graph,
 104                        struct media_entity *entity)
 105 {
 106         if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
 107                 WARN_ON(1);
 108                 return;
 109         }
 110         graph->top++;
 111         graph->stack[graph->top].link = 0;
 112         graph->stack[graph->top].entity = entity;
 113 }
 114
 115 static struct media_entity *stack_pop(struct media_entity_graph *graph)
 116 {
 117         struct media_entity *entity;
 118
 119         entity = graph->stack[graph->top].entity;
 120         graph->top--;
 121
 122         return entity;
 123 }
 124
 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  */
 138 void 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         bitmap_zero(graph->entities, MEDIA_ENTITY_ENUM_MAX_ID);
 144
 145         if (WARN_ON(entity->id >= MEDIA_ENTITY_ENUM_MAX_ID))
 146                 return;
 147
 148         __set_bit(entity->id, graph->entities);
 149         stack_push(graph, entity);
 150 }
 151 EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
 152
 153 /**
 154  * media_entity_graph_walk_next - Get the next entity in the graph
 155  * @graph: Media graph structure
 156  *
 157  * Perform a depth-first traversal of the given media entities graph.
 158  *
 159  * The graph structure must have been previously initialized with a call to
 160  * media_entity_graph_walk_start().
 161  *
 162  * Return the next entity in the graph or NULL if the whole graph have been
 163  * traversed.
 164  */
 165 struct media_entity *
 166 media_entity_graph_walk_next(struct media_entity_graph *graph)
 167 {
 168         if (stack_top(graph) == NULL)
 169                 return NULL;
 170
 171         /*
 172          * Depth first search. Push entity to stack and continue from
 173          * top of the stack until no more entities on the level can be
 174          * found.
 175          */
 176         while (link_top(graph) < stack_top(graph)->num_links) {
 177                 struct media_entity *entity = stack_top(graph);
 178                 struct media_link *link = &entity->links[link_top(graph)];
 179                 struct media_entity *next;
 180
 181                 /* The link is not enabled so we do not follow. */
 182                 if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
 183                         link_top(graph)++;
 184                         continue;
 185                 }
 186
 187                 /* Get the entity in the other end of the link . */
 188                 next = media_entity_other(entity, link);
 189                 if (WARN_ON(next->id >= MEDIA_ENTITY_ENUM_MAX_ID))
 190                         return NULL;
 191
 192                 /* Has the entity already been visited? */
 193                 if (__test_and_set_bit(next->id, graph->entities)) {
 194                         link_top(graph)++;
 195                         continue;
 196                 }
 197
 198                 /* Push the new entity to stack and start over. */
 199                 link_top(graph)++;
 200                 stack_push(graph, next);
 201         }
 202
 203         return stack_pop(graph);
 204 }
 205 EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
 206
 207 /* -----------------------------------------------------------------------------
 208  * Pipeline management
 209  */
 210
 211 /**
 212  * media_entity_pipeline_start - Mark a pipeline as streaming
 213  * @entity: Starting entity
 214  * @pipe: Media pipeline to be assigned to all entities in the pipeline.
 215  *
 216  * Mark all entities connected to a given entity through enabled links, either
 217  * directly or indirectly, as streaming. The given pipeline object is assigned to
 218  * every entity in the pipeline and stored in the media_entity pipe field.
 219  *
 220  * Calls to this function can be nested, in which case the same number of
 221  * media_entity_pipeline_stop() calls will be required to stop streaming. The
 222  * pipeline pointer must be identical for all nested calls to
 223  * media_entity_pipeline_start().
 224  */
 225 __must_check int media_entity_pipeline_start(struct media_entity *entity,
 226                                              struct media_pipeline *pipe)
 227 {
 228         struct media_device *mdev = entity->parent;
 229         struct media_entity_graph graph;
 230         struct media_entity *entity_err = entity;
 231         int ret;
 232
 233         mutex_lock(&mdev->graph_mutex);
 234
 235         media_entity_graph_walk_start(&graph, entity);
 236
 237         while ((entity = media_entity_graph_walk_next(&graph))) {
 238                 DECLARE_BITMAP(active, entity->num_pads);
 239                 DECLARE_BITMAP(has_no_links, entity->num_pads);
 240                 unsigned int i;
 241
 242                 entity->stream_count++;
 243                 WARN_ON(entity->pipe && entity->pipe != pipe);
 244                 entity->pipe = pipe;
 245
 246                 /* Already streaming --- no need to check. */
 247                 if (entity->stream_count > 1)
 248                         continue;
 249
 250                 if (!entity->ops || !entity->ops->link_validate)
 251                         continue;
 252
 253                 bitmap_zero(active, entity->num_pads);
 254                 bitmap_fill(has_no_links, entity->num_pads);
 255
 256                 for (i = 0; i < entity->num_links; i++) {
 257                         struct media_link *link = &entity->links[i];
 258                         struct media_pad *pad = link->sink->entity == entity
 259                                                 ? link->sink : link->source;
 260
 261                         /* Mark that a pad is connected by a link. */
 262                         bitmap_clear(has_no_links, pad->index, 1);
 263
 264                         /*
 265                          * Pads that either do not need to connect or
 266                          * are connected through an enabled link are
 267                          * fine.
 268                          */
 269                         if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
 270                             link->flags & MEDIA_LNK_FL_ENABLED)
 271                                 bitmap_set(active, pad->index, 1);
 272
 273                         /*
 274                          * Link validation will only take place for
 275                          * sink ends of the link that are enabled.
 276                          */
 277                         if (link->sink != pad ||
 278                             !(link->flags & MEDIA_LNK_FL_ENABLED))
 279                                 continue;
 280
 281                         ret = entity->ops->link_validate(link);
 282                         if (ret < 0 && ret != -ENOIOCTLCMD)
 283                                 goto error;
 284                 }
 285
 286                 /* Either no links or validated links are fine. */
 287                 bitmap_or(active, active, has_no_links, entity->num_pads);
 288
 289                 if (!bitmap_full(active, entity->num_pads)) {
 290                         ret = -EPIPE;
 291                         goto error;
 292                 }
 293         }
 294
 295         mutex_unlock(&mdev->graph_mutex);
 296
 297         return 0;
 298
 299 error:
 300         /*
 301          * Link validation on graph failed. We revert what we did and
 302          * return the error.
 303          */
 304         media_entity_graph_walk_start(&graph, entity_err);
 305
 306         while ((entity_err = media_entity_graph_walk_next(&graph))) {
 307                 entity_err->stream_count--;
 308                 if (entity_err->stream_count == 0)
 309                         entity_err->pipe = NULL;
 310
 311                 /*
 312                  * We haven't increased stream_count further than this
 313                  * so we quit here.
 314                  */
 315                 if (entity_err == entity)
 316                         break;
 317         }
 318
 319         mutex_unlock(&mdev->graph_mutex);
 320
 321         return ret;
 322 }
 323 EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
 324
 325 /**
 326  * media_entity_pipeline_stop - Mark a pipeline as not streaming
 327  * @entity: Starting entity
 328  *
 329  * Mark all entities connected to a given entity through enabled links, either
 330  * directly or indirectly, as not streaming. The media_entity pipe field is
 331  * reset to NULL.
 332  *
 333  * If multiple calls to media_entity_pipeline_start() have been made, the same
 334  * number of calls to this function are required to mark the pipeline as not
 335  * streaming.
 336  */
 337 void media_entity_pipeline_stop(struct media_entity *entity)
 338 {
 339         struct media_device *mdev = entity->parent;
 340         struct media_entity_graph graph;
 341
 342         mutex_lock(&mdev->graph_mutex);
 343
 344         media_entity_graph_walk_start(&graph, entity);
 345
 346         while ((entity = media_entity_graph_walk_next(&graph))) {
 347                 entity->stream_count--;
 348                 if (entity->stream_count == 0)
 349                         entity->pipe = NULL;
 350         }
 351
 352         mutex_unlock(&mdev->graph_mutex);
 353 }
 354 EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
 355
 356 /* -----------------------------------------------------------------------------
 357  * Module use count
 358  */
 359
 360 /*
 361  * media_entity_get - Get a reference to the parent module
 362  * @entity: The entity
 363  *
 364  * Get a reference to the parent media device module.
 365  *
 366  * The function will return immediately if @entity is NULL.
 367  *
 368  * Return a pointer to the entity on success or NULL on failure.
 369  */
 370 struct media_entity *media_entity_get(struct media_entity *entity)
 371 {
 372         if (entity == NULL)
 373                 return NULL;
 374
 375         if (entity->parent->dev &&
 376             !try_module_get(entity->parent->dev->driver->owner))
 377                 return NULL;
 378
 379         return entity;
 380 }
 381 EXPORT_SYMBOL_GPL(media_entity_get);
 382
 383 /*
 384  * media_entity_put - Release the reference to the parent module
 385  * @entity: The entity
 386  *
 387  * Release the reference count acquired by media_entity_get().
 388  *
 389  * The function will return immediately if @entity is NULL.
 390  */
 391 void media_entity_put(struct media_entity *entity)
 392 {
 393         if (entity == NULL)
 394                 return;
 395
 396         if (entity->parent->dev)
 397                 module_put(entity->parent->dev->driver->owner);
 398 }
 399 EXPORT_SYMBOL_GPL(media_entity_put);
 400
 401 /* -----------------------------------------------------------------------------
 402  * Links management
 403  */
 404
 405 static struct media_link *media_entity_add_link(struct media_entity *entity)
 406 {
 407         if (entity->num_links >= entity->max_links) {
 408                 struct media_link *links = entity->links;
 409                 unsigned int max_links = entity->max_links + 2;
 410                 unsigned int i;
 411
 412                 links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
 413                 if (links == NULL)
 414                         return NULL;
 415
 416                 for (i = 0; i < entity->num_links; i++)
 417                         links[i].reverse->reverse = &links[i];
 418
 419                 entity->max_links = max_links;
 420                 entity->links = links;
 421         }
 422
 423         return &entity->links[entity->num_links++];
 424 }
 425
 426 int
 427 media_entity_create_link(struct media_entity *source, u16 source_pad,
 428                          struct media_entity *sink, u16 sink_pad, u32 flags)
 429 {
 430         struct media_link *link;
 431         struct media_link *backlink;
 432
 433         BUG_ON(source == NULL || sink == NULL);
 434         BUG_ON(source_pad >= source->num_pads);
 435         BUG_ON(sink_pad >= sink->num_pads);
 436
 437         link = media_entity_add_link(source);
 438         if (link == NULL)
 439                 return -ENOMEM;
 440
 441         link->source = &source->pads[source_pad];
 442         link->sink = &sink->pads[sink_pad];
 443         link->flags = flags;
 444
 445         /* Create the backlink. Backlinks are used to help graph traversal and
 446          * are not reported to userspace.
 447          */
 448         backlink = media_entity_add_link(sink);
 449         if (backlink == NULL) {
 450                 source->num_links--;
 451                 return -ENOMEM;
 452         }
 453
 454         backlink->source = &source->pads[source_pad];
 455         backlink->sink = &sink->pads[sink_pad];
 456         backlink->flags = flags;
 457
 458         link->reverse = backlink;
 459         backlink->reverse = link;
 460
 461         sink->num_backlinks++;
 462
 463         return 0;
 464 }
 465 EXPORT_SYMBOL_GPL(media_entity_create_link);
 466
 467 void __media_entity_remove_links(struct media_entity *entity)
 468 {
 469         unsigned int i;
 470
 471         for (i = 0; i < entity->num_links; i++) {
 472                 struct media_link *link = &entity->links[i];
 473                 struct media_entity *remote;
 474                 unsigned int r = 0;
 475
 476                 if (link->source->entity == entity)
 477                         remote = link->sink->entity;
 478                 else
 479                         remote = link->source->entity;
 480
 481                 while (r < remote->num_links) {
 482                         struct media_link *rlink = &remote->links[r];
 483
 484                         if (rlink != link->reverse) {
 485                                 r++;
 486                                 continue;
 487                         }
 488
 489                         if (link->source->entity == entity)
 490                                 remote->num_backlinks--;
 491
 492                         if (--remote->num_links == 0)
 493                                 break;
 494
 495                         /* Insert last entry in place of the dropped link. */
 496                         *rlink = remote->links[remote->num_links];
 497                 }
 498         }
 499
 500         entity->num_links = 0;
 501         entity->num_backlinks = 0;
 502 }
 503 EXPORT_SYMBOL_GPL(__media_entity_remove_links);
 504
 505 void media_entity_remove_links(struct media_entity *entity)
 506 {
 507         /* Do nothing if the entity is not registered. */
 508         if (entity->parent == NULL)
 509                 return;
 510
 511         mutex_lock(&entity->parent->graph_mutex);
 512         __media_entity_remove_links(entity);
 513         mutex_unlock(&entity->parent->graph_mutex);
 514 }
 515 EXPORT_SYMBOL_GPL(media_entity_remove_links);
 516
 517 static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
 518 {
 519         int ret;
 520
 521         /* Notify both entities. */
 522         ret = media_entity_call(link->source->entity, link_setup,
 523                                 link->source, link->sink, flags);
 524         if (ret < 0 && ret != -ENOIOCTLCMD)
 525                 return ret;
 526
 527         ret = media_entity_call(link->sink->entity, link_setup,
 528                                 link->sink, link->source, flags);
 529         if (ret < 0 && ret != -ENOIOCTLCMD) {
 530                 media_entity_call(link->source->entity, link_setup,
 531                                   link->source, link->sink, link->flags);
 532                 return ret;
 533         }
 534
 535         link->flags = flags;
 536         link->reverse->flags = link->flags;
 537
 538         return 0;
 539 }
 540
 541 /**
 542  * __media_entity_setup_link - Configure a media link
 543  * @link: The link being configured
 544  * @flags: Link configuration flags
 545  *
 546  * The bulk of link setup is handled by the two entities connected through the
 547  * link. This function notifies both entities of the link configuration change.
 548  *
 549  * If the link is immutable or if the current and new configuration are
 550  * identical, return immediately.
 551  *
 552  * The user is expected to hold link->source->parent->mutex. If not,
 553  * media_entity_setup_link() should be used instead.
 554  */
 555 int __media_entity_setup_link(struct media_link *link, u32 flags)
 556 {
 557         const u32 mask = MEDIA_LNK_FL_ENABLED;
 558         struct media_device *mdev;
 559         struct media_entity *source, *sink;
 560         int ret = -EBUSY;
 561
 562         if (link == NULL)
 563                 return -EINVAL;
 564
 565         /* The non-modifiable link flags must not be modified. */
 566         if ((link->flags & ~mask) != (flags & ~mask))
 567                 return -EINVAL;
 568
 569         if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
 570                 return link->flags == flags ? 0 : -EINVAL;
 571
 572         if (link->flags == flags)
 573                 return 0;
 574
 575         source = link->source->entity;
 576         sink = link->sink->entity;
 577
 578         if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
 579             (source->stream_count || sink->stream_count))
 580                 return -EBUSY;
 581
 582         mdev = source->parent;
 583
 584         if (mdev->link_notify) {
 585                 ret = mdev->link_notify(link, flags,
 586                                         MEDIA_DEV_NOTIFY_PRE_LINK_CH);
 587                 if (ret < 0)
 588                         return ret;
 589         }
 590
 591         ret = __media_entity_setup_link_notify(link, flags);
 592
 593         if (mdev->link_notify)
 594                 mdev->link_notify(link, flags, MEDIA_DEV_NOTIFY_POST_LINK_CH);
 595
 596         return ret;
 597 }
 598
 599 int media_entity_setup_link(struct media_link *link, u32 flags)
 600 {
 601         int ret;
 602
 603         mutex_lock(&link->source->entity->parent->graph_mutex);
 604         ret = __media_entity_setup_link(link, flags);
 605         mutex_unlock(&link->source->entity->parent->graph_mutex);
 606
 607         return ret;
 608 }
 609 EXPORT_SYMBOL_GPL(media_entity_setup_link);
 610
 611 /**
 612  * media_entity_find_link - Find a link between two pads
 613  * @source: Source pad
 614  * @sink: Sink pad
 615  *
 616  * Return a pointer to the link between the two entities. If no such link
 617  * exists, return NULL.
 618  */
 619 struct media_link *
 620 media_entity_find_link(struct media_pad *source, struct media_pad *sink)
 621 {
 622         struct media_link *link;
 623         unsigned int i;
 624
 625         for (i = 0; i < source->entity->num_links; ++i) {
 626                 link = &source->entity->links[i];
 627
 628                 if (link->source->entity == source->entity &&
 629                     link->source->index == source->index &&
 630                     link->sink->entity == sink->entity &&
 631                     link->sink->index == sink->index)
 632                         return link;
 633         }
 634
 635         return NULL;
 636 }
 637 EXPORT_SYMBOL_GPL(media_entity_find_link);
 638
 639 /**
 640  * media_entity_remote_pad - Find the pad at the remote end of a link
 641  * @pad: Pad at the local end of the link
 642  *
 643  * Search for a remote pad connected to the given pad by iterating over all
 644  * links originating or terminating at that pad until an enabled link is found.
 645  *
 646  * Return a pointer to the pad at the remote end of the first found enabled
 647  * link, or NULL if no enabled link has been found.
 648  */
 649 struct media_pad *media_entity_remote_pad(struct media_pad *pad)
 650 {
 651         unsigned int i;
 652
 653         for (i = 0; i < pad->entity->num_links; i++) {
 654                 struct media_link *link = &pad->entity->links[i];
 655
 656                 if (!(link->flags & MEDIA_LNK_FL_ENABLED))
 657                         continue;
 658
 659                 if (link->source == pad)
 660                         return link->sink;
 661
 662                 if (link->sink == pad)
 663                         return link->source;
 664         }
 665
 666         return NULL;
 667
 668 }
 669 EXPORT_SYMBOL_GPL(media_entity_remote_pad);