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/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  */
  52 int
  53 media_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 }
  79 EXPORT_SYMBOL_GPL(media_entity_init);
  80
  81 void
  82 media_entity_cleanup(struct media_entity *entity)
  83 {
  84         kfree(entity->links);
  85 }
  86 EXPORT_SYMBOL_GPL(media_entity_cleanup);
  87
  88 /* -----------------------------------------------------------------------------
  89  * Graph traversal
  90  */
  91
  92 static struct media_entity *
  93 media_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 */
 102 static 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
 114 static 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  */
 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         stack_push(graph, entity);
 144 }
 145 EXPORT_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  */
 159 struct media_entity *
 160 media_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 }
 197 EXPORT_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
 264 error:
 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 }
 288 EXPORT_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  */
 302 void 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 }
 319 EXPORT_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  */
 335 struct 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 }
 346 EXPORT_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  */
 356 void 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 }
 364 EXPORT_SYMBOL_GPL(media_entity_put);
 365
 366 /* -----------------------------------------------------------------------------
 367  * Links management
 368  */
 369
 370 static 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
 391 int
 392 media_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 }
 430 EXPORT_SYMBOL_GPL(media_entity_create_link);
 431
 432 static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
 433 {
 434         int ret;
 435
 436         /* Notify both entities. */
 437         ret = media_entity_call(link->source->entity, link_setup,
 438                                 link->source, link->sink, flags);
 439         if (ret < 0 && ret != -ENOIOCTLCMD)
 440                 return ret;
 441
 442         ret = media_entity_call(link->sink->entity, link_setup,
 443                                 link->sink, link->source, flags);
 444         if (ret < 0 && ret != -ENOIOCTLCMD) {
 445                 media_entity_call(link->source->entity, link_setup,
 446                                   link->source, link->sink, link->flags);
 447                 return ret;
 448         }
 449
 450         link->flags = flags;
 451         link->reverse->flags = link->flags;
 452
 453         return 0;
 454 }
 455
 456 /**
 457  * __media_entity_setup_link - Configure a media link
 458  * @link: The link being configured
 459  * @flags: Link configuration flags
 460  *
 461  * The bulk of link setup is handled by the two entities connected through the
 462  * link. This function notifies both entities of the link configuration change.
 463  *
 464  * If the link is immutable or if the current and new configuration are
 465  * identical, return immediately.
 466  *
 467  * The user is expected to hold link->source->parent->mutex. If not,
 468  * media_entity_setup_link() should be used instead.
 469  */
 470 int __media_entity_setup_link(struct media_link *link, u32 flags)
 471 {
 472         const u32 mask = MEDIA_LNK_FL_ENABLED;
 473         struct media_device *mdev;
 474         struct media_entity *source, *sink;
 475         int ret = -EBUSY;
 476
 477         if (link == NULL)
 478                 return -EINVAL;
 479
 480         /* The non-modifiable link flags must not be modified. */
 481         if ((link->flags & ~mask) != (flags & ~mask))
 482                 return -EINVAL;
 483
 484         if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
 485                 return link->flags == flags ? 0 : -EINVAL;
 486
 487         if (link->flags == flags)
 488                 return 0;
 489
 490         source = link->source->entity;
 491         sink = link->sink->entity;
 492
 493         if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
 494             (source->stream_count || sink->stream_count))
 495                 return -EBUSY;
 496
 497         mdev = source->parent;
 498
 499         if ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify) {
 500                 ret = mdev->link_notify(link->source, link->sink,
 501                                         MEDIA_LNK_FL_ENABLED);
 502                 if (ret < 0)
 503                         return ret;
 504         }
 505
 506         ret = __media_entity_setup_link_notify(link, flags);
 507         if (ret < 0)
 508                 goto err;
 509
 510         if (!(flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify)
 511                 mdev->link_notify(link->source, link->sink, 0);
 512
 513         return 0;
 514
 515 err:
 516         if ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify)
 517                 mdev->link_notify(link->source, link->sink, 0);
 518
 519         return ret;
 520 }
 521
 522 int media_entity_setup_link(struct media_link *link, u32 flags)
 523 {
 524         int ret;
 525
 526         mutex_lock(&link->source->entity->parent->graph_mutex);
 527         ret = __media_entity_setup_link(link, flags);
 528         mutex_unlock(&link->source->entity->parent->graph_mutex);
 529
 530         return ret;
 531 }
 532 EXPORT_SYMBOL_GPL(media_entity_setup_link);
 533
 534 /**
 535  * media_entity_find_link - Find a link between two pads
 536  * @source: Source pad
 537  * @sink: Sink pad
 538  *
 539  * Return a pointer to the link between the two entities. If no such link
 540  * exists, return NULL.
 541  */
 542 struct media_link *
 543 media_entity_find_link(struct media_pad *source, struct media_pad *sink)
 544 {
 545         struct media_link *link;
 546         unsigned int i;
 547
 548         for (i = 0; i < source->entity->num_links; ++i) {
 549                 link = &source->entity->links[i];
 550
 551                 if (link->source->entity == source->entity &&
 552                     link->source->index == source->index &&
 553                     link->sink->entity == sink->entity &&
 554                     link->sink->index == sink->index)
 555                         return link;
 556         }
 557
 558         return NULL;
 559 }
 560 EXPORT_SYMBOL_GPL(media_entity_find_link);
 561
 562 /**
 563  * media_entity_remote_source - Find the source pad at the remote end of a link
 564  * @pad: Sink pad at the local end of the link
 565  *
 566  * Search for a remote source pad connected to the given sink pad by iterating
 567  * over all links originating or terminating at that pad until an enabled link
 568  * is found.
 569  *
 570  * Return a pointer to the pad at the remote end of the first found enabled
 571  * link, or NULL if no enabled link has been found.
 572  */
 573 struct media_pad *media_entity_remote_source(struct media_pad *pad)
 574 {
 575         unsigned int i;
 576
 577         for (i = 0; i < pad->entity->num_links; i++) {
 578                 struct media_link *link = &pad->entity->links[i];
 579
 580                 if (!(link->flags & MEDIA_LNK_FL_ENABLED))
 581                         continue;
 582
 583                 if (link->source == pad)
 584                         return link->sink;
 585
 586                 if (link->sink == pad)
 587                         return link->source;
 588         }
 589
 590         return NULL;
 591
 592 }
 593 EXPORT_SYMBOL_GPL(media_entity_remote_source);