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                 unsigned int i;
 239
 240                 entity->stream_count++;
 241                 WARN_ON(entity->pipe && entity->pipe != pipe);
 242                 entity->pipe = pipe;
 243
 244                 /* Already streaming --- no need to check. */
 245                 if (entity->stream_count > 1)
 246                         continue;
 247
 248                 if (!entity->ops || !entity->ops->link_validate)
 249                         continue;
 250
 251                 for (i = 0; i < entity->num_links; i++) {
 252                         struct media_link *link = &entity->links[i];
 253
 254                         /* Is this pad part of an enabled link? */
 255                         if (!(link->flags & MEDIA_LNK_FL_ENABLED))
 256                                 continue;
 257
 258                         /* Are we the sink or not? */
 259                         if (link->sink->entity != entity)
 260                                 continue;
 261
 262                         ret = entity->ops->link_validate(link);
 263                         if (ret < 0 && ret != -ENOIOCTLCMD)
 264                                 goto error;
 265                 }
 266         }
 267
 268         mutex_unlock(&mdev->graph_mutex);
 269
 270         return 0;
 271
 272 error:
 273         /*
 274          * Link validation on graph failed. We revert what we did and
 275          * return the error.
 276          */
 277         media_entity_graph_walk_start(&graph, entity_err);
 278
 279         while ((entity_err = media_entity_graph_walk_next(&graph))) {
 280                 entity_err->stream_count--;
 281                 if (entity_err->stream_count == 0)
 282                         entity_err->pipe = NULL;
 283
 284                 /*
 285                  * We haven't increased stream_count further than this
 286                  * so we quit here.
 287                  */
 288                 if (entity_err == entity)
 289                         break;
 290         }
 291
 292         mutex_unlock(&mdev->graph_mutex);
 293
 294         return ret;
 295 }
 296 EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
 297
 298 /**
 299  * media_entity_pipeline_stop - Mark a pipeline as not streaming
 300  * @entity: Starting entity
 301  *
 302  * Mark all entities connected to a given entity through enabled links, either
 303  * directly or indirectly, as not streaming. The media_entity pipe field is
 304  * reset to NULL.
 305  *
 306  * If multiple calls to media_entity_pipeline_start() have been made, the same
 307  * number of calls to this function are required to mark the pipeline as not
 308  * streaming.
 309  */
 310 void media_entity_pipeline_stop(struct media_entity *entity)
 311 {
 312         struct media_device *mdev = entity->parent;
 313         struct media_entity_graph graph;
 314
 315         mutex_lock(&mdev->graph_mutex);
 316
 317         media_entity_graph_walk_start(&graph, entity);
 318
 319         while ((entity = media_entity_graph_walk_next(&graph))) {
 320                 entity->stream_count--;
 321                 if (entity->stream_count == 0)
 322                         entity->pipe = NULL;
 323         }
 324
 325         mutex_unlock(&mdev->graph_mutex);
 326 }
 327 EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
 328
 329 /* -----------------------------------------------------------------------------
 330  * Module use count
 331  */
 332
 333 /*
 334  * media_entity_get - Get a reference to the parent module
 335  * @entity: The entity
 336  *
 337  * Get a reference to the parent media device module.
 338  *
 339  * The function will return immediately if @entity is NULL.
 340  *
 341  * Return a pointer to the entity on success or NULL on failure.
 342  */
 343 struct media_entity *media_entity_get(struct media_entity *entity)
 344 {
 345         if (entity == NULL)
 346                 return NULL;
 347
 348         if (entity->parent->dev &&
 349             !try_module_get(entity->parent->dev->driver->owner))
 350                 return NULL;
 351
 352         return entity;
 353 }
 354 EXPORT_SYMBOL_GPL(media_entity_get);
 355
 356 /*
 357  * media_entity_put - Release the reference to the parent module
 358  * @entity: The entity
 359  *
 360  * Release the reference count acquired by media_entity_get().
 361  *
 362  * The function will return immediately if @entity is NULL.
 363  */
 364 void media_entity_put(struct media_entity *entity)
 365 {
 366         if (entity == NULL)
 367                 return;
 368
 369         if (entity->parent->dev)
 370                 module_put(entity->parent->dev->driver->owner);
 371 }
 372 EXPORT_SYMBOL_GPL(media_entity_put);
 373
 374 /* -----------------------------------------------------------------------------
 375  * Links management
 376  */
 377
 378 static struct media_link *media_entity_add_link(struct media_entity *entity)
 379 {
 380         if (entity->num_links >= entity->max_links) {
 381                 struct media_link *links = entity->links;
 382                 unsigned int max_links = entity->max_links + 2;
 383                 unsigned int i;
 384
 385                 links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
 386                 if (links == NULL)
 387                         return NULL;
 388
 389                 for (i = 0; i < entity->num_links; i++)
 390                         links[i].reverse->reverse = &links[i];
 391
 392                 entity->max_links = max_links;
 393                 entity->links = links;
 394         }
 395
 396         return &entity->links[entity->num_links++];
 397 }
 398
 399 int
 400 media_entity_create_link(struct media_entity *source, u16 source_pad,
 401                          struct media_entity *sink, u16 sink_pad, u32 flags)
 402 {
 403         struct media_link *link;
 404         struct media_link *backlink;
 405
 406         BUG_ON(source == NULL || sink == NULL);
 407         BUG_ON(source_pad >= source->num_pads);
 408         BUG_ON(sink_pad >= sink->num_pads);
 409
 410         link = media_entity_add_link(source);
 411         if (link == NULL)
 412                 return -ENOMEM;
 413
 414         link->source = &source->pads[source_pad];
 415         link->sink = &sink->pads[sink_pad];
 416         link->flags = flags;
 417
 418         /* Create the backlink. Backlinks are used to help graph traversal and
 419          * are not reported to userspace.
 420          */
 421         backlink = media_entity_add_link(sink);
 422         if (backlink == NULL) {
 423                 source->num_links--;
 424                 return -ENOMEM;
 425         }
 426
 427         backlink->source = &source->pads[source_pad];
 428         backlink->sink = &sink->pads[sink_pad];
 429         backlink->flags = flags;
 430
 431         link->reverse = backlink;
 432         backlink->reverse = link;
 433
 434         sink->num_backlinks++;
 435
 436         return 0;
 437 }
 438 EXPORT_SYMBOL_GPL(media_entity_create_link);
 439
 440 void __media_entity_remove_links(struct media_entity *entity)
 441 {
 442         unsigned int i;
 443
 444         for (i = 0; i < entity->num_links; i++) {
 445                 struct media_link *link = &entity->links[i];
 446                 struct media_entity *remote;
 447                 unsigned int r = 0;
 448
 449                 if (link->source->entity == entity)
 450                         remote = link->sink->entity;
 451                 else
 452                         remote = link->source->entity;
 453
 454                 while (r < remote->num_links) {
 455                         struct media_link *rlink = &remote->links[r];
 456
 457                         if (rlink != link->reverse) {
 458                                 r++;
 459                                 continue;
 460                         }
 461
 462                         if (link->source->entity == entity)
 463                                 remote->num_backlinks--;
 464
 465                         if (--remote->num_links == 0)
 466                                 break;
 467
 468                         /* Insert last entry in place of the dropped link. */
 469                         *rlink = remote->links[remote->num_links];
 470                 }
 471         }
 472
 473         entity->num_links = 0;
 474         entity->num_backlinks = 0;
 475 }
 476 EXPORT_SYMBOL_GPL(__media_entity_remove_links);
 477
 478 void media_entity_remove_links(struct media_entity *entity)
 479 {
 480         /* Do nothing if the entity is not registered. */
 481         if (entity->parent == NULL)
 482                 return;
 483
 484         mutex_lock(&entity->parent->graph_mutex);
 485         __media_entity_remove_links(entity);
 486         mutex_unlock(&entity->parent->graph_mutex);
 487 }
 488 EXPORT_SYMBOL_GPL(media_entity_remove_links);
 489
 490 static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
 491 {
 492         int ret;
 493
 494         /* Notify both entities. */
 495         ret = media_entity_call(link->source->entity, link_setup,
 496                                 link->source, link->sink, flags);
 497         if (ret < 0 && ret != -ENOIOCTLCMD)
 498                 return ret;
 499
 500         ret = media_entity_call(link->sink->entity, link_setup,
 501                                 link->sink, link->source, flags);
 502         if (ret < 0 && ret != -ENOIOCTLCMD) {
 503                 media_entity_call(link->source->entity, link_setup,
 504                                   link->source, link->sink, link->flags);
 505                 return ret;
 506         }
 507
 508         link->flags = flags;
 509         link->reverse->flags = link->flags;
 510
 511         return 0;
 512 }
 513
 514 /**
 515  * __media_entity_setup_link - Configure a media link
 516  * @link: The link being configured
 517  * @flags: Link configuration flags
 518  *
 519  * The bulk of link setup is handled by the two entities connected through the
 520  * link. This function notifies both entities of the link configuration change.
 521  *
 522  * If the link is immutable or if the current and new configuration are
 523  * identical, return immediately.
 524  *
 525  * The user is expected to hold link->source->parent->mutex. If not,
 526  * media_entity_setup_link() should be used instead.
 527  */
 528 int __media_entity_setup_link(struct media_link *link, u32 flags)
 529 {
 530         const u32 mask = MEDIA_LNK_FL_ENABLED;
 531         struct media_device *mdev;
 532         struct media_entity *source, *sink;
 533         int ret = -EBUSY;
 534
 535         if (link == NULL)
 536                 return -EINVAL;
 537
 538         /* The non-modifiable link flags must not be modified. */
 539         if ((link->flags & ~mask) != (flags & ~mask))
 540                 return -EINVAL;
 541
 542         if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
 543                 return link->flags == flags ? 0 : -EINVAL;
 544
 545         if (link->flags == flags)
 546                 return 0;
 547
 548         source = link->source->entity;
 549         sink = link->sink->entity;
 550
 551         if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
 552             (source->stream_count || sink->stream_count))
 553                 return -EBUSY;
 554
 555         mdev = source->parent;
 556
 557         if (mdev->link_notify) {
 558                 ret = mdev->link_notify(link, flags,
 559                                         MEDIA_DEV_NOTIFY_PRE_LINK_CH);
 560                 if (ret < 0)
 561                         return ret;
 562         }
 563
 564         ret = __media_entity_setup_link_notify(link, flags);
 565
 566         if (mdev->link_notify)
 567                 mdev->link_notify(link, flags, MEDIA_DEV_NOTIFY_POST_LINK_CH);
 568
 569         return ret;
 570 }
 571
 572 int media_entity_setup_link(struct media_link *link, u32 flags)
 573 {
 574         int ret;
 575
 576         mutex_lock(&link->source->entity->parent->graph_mutex);
 577         ret = __media_entity_setup_link(link, flags);
 578         mutex_unlock(&link->source->entity->parent->graph_mutex);
 579
 580         return ret;
 581 }
 582 EXPORT_SYMBOL_GPL(media_entity_setup_link);
 583
 584 /**
 585  * media_entity_find_link - Find a link between two pads
 586  * @source: Source pad
 587  * @sink: Sink pad
 588  *
 589  * Return a pointer to the link between the two entities. If no such link
 590  * exists, return NULL.
 591  */
 592 struct media_link *
 593 media_entity_find_link(struct media_pad *source, struct media_pad *sink)
 594 {
 595         struct media_link *link;
 596         unsigned int i;
 597
 598         for (i = 0; i < source->entity->num_links; ++i) {
 599                 link = &source->entity->links[i];
 600
 601                 if (link->source->entity == source->entity &&
 602                     link->source->index == source->index &&
 603                     link->sink->entity == sink->entity &&
 604                     link->sink->index == sink->index)
 605                         return link;
 606         }
 607
 608         return NULL;
 609 }
 610 EXPORT_SYMBOL_GPL(media_entity_find_link);
 611
 612 /**
 613  * media_entity_remote_pad - Find the pad at the remote end of a link
 614  * @pad: Pad at the local end of the link
 615  *
 616  * Search for a remote pad connected to the given pad by iterating over all
 617  * links originating or terminating at that pad until an enabled link is found.
 618  *
 619  * Return a pointer to the pad at the remote end of the first found enabled
 620  * link, or NULL if no enabled link has been found.
 621  */
 622 struct media_pad *media_entity_remote_pad(struct media_pad *pad)
 623 {
 624         unsigned int i;
 625
 626         for (i = 0; i < pad->entity->num_links; i++) {
 627                 struct media_link *link = &pad->entity->links[i];
 628
 629                 if (!(link->flags & MEDIA_LNK_FL_ENABLED))
 630                         continue;
 631
 632                 if (link->source == pad)
 633                         return link->sink;
 634
 635                 if (link->sink == pad)
 636                         return link->source;
 637         }
 638
 639         return NULL;
 640
 641 }
 642 EXPORT_SYMBOL_GPL(media_entity_remote_pad);