drivers/media/mc/mc-entity.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Media entity
   4  *
   5  * Copyright (C) 2010 Nokia Corporation
   6  *
   7  * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
   8  *           Sakari Ailus <sakari.ailus@iki.fi>
   9  */
  10
  11 #include <linux/bitmap.h>
  12 #include <linux/property.h>
  13 #include <linux/slab.h>
  14 #include <media/media-entity.h>
  15 #include <media/media-device.h>
  16
  17 static inline const char *gobj_type(enum media_gobj_type type)
  18 {
  19         switch (type) {
  20         case MEDIA_GRAPH_ENTITY:
  21                 return "entity";
  22         case MEDIA_GRAPH_PAD:
  23                 return "pad";
  24         case MEDIA_GRAPH_LINK:
  25                 return "link";
  26         case MEDIA_GRAPH_INTF_DEVNODE:
  27                 return "intf-devnode";
  28         default:
  29                 return "unknown";
  30         }
  31 }
  32
  33 static inline const char *intf_type(struct media_interface *intf)
  34 {
  35         switch (intf->type) {
  36         case MEDIA_INTF_T_DVB_FE:
  37                 return "dvb-frontend";
  38         case MEDIA_INTF_T_DVB_DEMUX:
  39                 return "dvb-demux";
  40         case MEDIA_INTF_T_DVB_DVR:
  41                 return "dvb-dvr";
  42         case MEDIA_INTF_T_DVB_CA:
  43                 return  "dvb-ca";
  44         case MEDIA_INTF_T_DVB_NET:
  45                 return "dvb-net";
  46         case MEDIA_INTF_T_V4L_VIDEO:
  47                 return "v4l-video";
  48         case MEDIA_INTF_T_V4L_VBI:
  49                 return "v4l-vbi";
  50         case MEDIA_INTF_T_V4L_RADIO:
  51                 return "v4l-radio";
  52         case MEDIA_INTF_T_V4L_SUBDEV:
  53                 return "v4l-subdev";
  54         case MEDIA_INTF_T_V4L_SWRADIO:
  55                 return "v4l-swradio";
  56         case MEDIA_INTF_T_V4L_TOUCH:
  57                 return "v4l-touch";
  58         default:
  59                 return "unknown-intf";
  60         }
  61 };
  62
  63 __must_check int __media_entity_enum_init(struct media_entity_enum *ent_enum,
  64                                           int idx_max)
  65 {
  66         idx_max = ALIGN(idx_max, BITS_PER_LONG);
  67         ent_enum->bmap = kcalloc(idx_max / BITS_PER_LONG, sizeof(long),
  68                                  GFP_KERNEL);
  69         if (!ent_enum->bmap)
  70                 return -ENOMEM;
  71
  72         bitmap_zero(ent_enum->bmap, idx_max);
  73         ent_enum->idx_max = idx_max;
  74
  75         return 0;
  76 }
  77 EXPORT_SYMBOL_GPL(__media_entity_enum_init);
  78
  79 void media_entity_enum_cleanup(struct media_entity_enum *ent_enum)
  80 {
  81         kfree(ent_enum->bmap);
  82 }
  83 EXPORT_SYMBOL_GPL(media_entity_enum_cleanup);
  84
  85 /**
  86  *  dev_dbg_obj - Prints in debug mode a change on some object
  87  *
  88  * @event_name: Name of the event to report. Could be __func__
  89  * @gobj:       Pointer to the object
  90  *
  91  * Enabled only if DEBUG or CONFIG_DYNAMIC_DEBUG. Otherwise, it
  92  * won't produce any code.
  93  */
  94 static void dev_dbg_obj(const char *event_name,  struct media_gobj *gobj)
  95 {
  96 #if defined(DEBUG) || defined (CONFIG_DYNAMIC_DEBUG)
  97         switch (media_type(gobj)) {
  98         case MEDIA_GRAPH_ENTITY:
  99                 dev_dbg(gobj->mdev->dev,
 100                         "%s id %u: entity '%s'\n",
 101                         event_name, media_id(gobj),
 102                         gobj_to_entity(gobj)->name);
 103                 break;
 104         case MEDIA_GRAPH_LINK:
 105         {
 106                 struct media_link *link = gobj_to_link(gobj);
 107
 108                 dev_dbg(gobj->mdev->dev,
 109                         "%s id %u: %s link id %u ==> id %u\n",
 110                         event_name, media_id(gobj),
 111                         media_type(link->gobj0) == MEDIA_GRAPH_PAD ?
 112                                 "data" : "interface",
 113                         media_id(link->gobj0),
 114                         media_id(link->gobj1));
 115                 break;
 116         }
 117         case MEDIA_GRAPH_PAD:
 118         {
 119                 struct media_pad *pad = gobj_to_pad(gobj);
 120
 121                 dev_dbg(gobj->mdev->dev,
 122                         "%s id %u: %s%spad '%s':%d\n",
 123                         event_name, media_id(gobj),
 124                         pad->flags & MEDIA_PAD_FL_SINK   ? "sink " : "",
 125                         pad->flags & MEDIA_PAD_FL_SOURCE ? "source " : "",
 126                         pad->entity->name, pad->index);
 127                 break;
 128         }
 129         case MEDIA_GRAPH_INTF_DEVNODE:
 130         {
 131                 struct media_interface *intf = gobj_to_intf(gobj);
 132                 struct media_intf_devnode *devnode = intf_to_devnode(intf);
 133
 134                 dev_dbg(gobj->mdev->dev,
 135                         "%s id %u: intf_devnode %s - major: %d, minor: %d\n",
 136                         event_name, media_id(gobj),
 137                         intf_type(intf),
 138                         devnode->major, devnode->minor);
 139                 break;
 140         }
 141         }
 142 #endif
 143 }
 144
 145 void media_gobj_create(struct media_device *mdev,
 146                            enum media_gobj_type type,
 147                            struct media_gobj *gobj)
 148 {
 149         BUG_ON(!mdev);
 150
 151         gobj->mdev = mdev;
 152
 153         /* Create a per-type unique object ID */
 154         gobj->id = media_gobj_gen_id(type, ++mdev->id);
 155
 156         switch (type) {
 157         case MEDIA_GRAPH_ENTITY:
 158                 list_add_tail(&gobj->list, &mdev->entities);
 159                 break;
 160         case MEDIA_GRAPH_PAD:
 161                 list_add_tail(&gobj->list, &mdev->pads);
 162                 break;
 163         case MEDIA_GRAPH_LINK:
 164                 list_add_tail(&gobj->list, &mdev->links);
 165                 break;
 166         case MEDIA_GRAPH_INTF_DEVNODE:
 167                 list_add_tail(&gobj->list, &mdev->interfaces);
 168                 break;
 169         }
 170
 171         mdev->topology_version++;
 172
 173         dev_dbg_obj(__func__, gobj);
 174 }
 175
 176 void media_gobj_destroy(struct media_gobj *gobj)
 177 {
 178         /* Do nothing if the object is not linked. */
 179         if (gobj->mdev == NULL)
 180                 return;
 181
 182         dev_dbg_obj(__func__, gobj);
 183
 184         gobj->mdev->topology_version++;
 185
 186         /* Remove the object from mdev list */
 187         list_del(&gobj->list);
 188
 189         gobj->mdev = NULL;
 190 }
 191
 192 /*
 193  * TODO: Get rid of this.
 194  */
 195 #define MEDIA_ENTITY_MAX_PADS           512
 196
 197 int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
 198                            struct media_pad *pads)
 199 {
 200         struct media_device *mdev = entity->graph_obj.mdev;
 201         unsigned int i;
 202
 203         if (num_pads >= MEDIA_ENTITY_MAX_PADS)
 204                 return -E2BIG;
 205
 206         entity->num_pads = num_pads;
 207         entity->pads = pads;
 208
 209         if (mdev)
 210                 mutex_lock(&mdev->graph_mutex);
 211
 212         for (i = 0; i < num_pads; i++) {
 213                 pads[i].entity = entity;
 214                 pads[i].index = i;
 215                 if (mdev)
 216                         media_gobj_create(mdev, MEDIA_GRAPH_PAD,
 217                                         &entity->pads[i].graph_obj);
 218         }
 219
 220         if (mdev)
 221                 mutex_unlock(&mdev->graph_mutex);
 222
 223         return 0;
 224 }
 225 EXPORT_SYMBOL_GPL(media_entity_pads_init);
 226
 227 /* -----------------------------------------------------------------------------
 228  * Graph traversal
 229  */
 230
 231 static struct media_entity *
 232 media_entity_other(struct media_entity *entity, struct media_link *link)
 233 {
 234         if (link->source->entity == entity)
 235                 return link->sink->entity;
 236         else
 237                 return link->source->entity;
 238 }
 239
 240 /* push an entity to traversal stack */
 241 static void stack_push(struct media_graph *graph,
 242                        struct media_entity *entity)
 243 {
 244         if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
 245                 WARN_ON(1);
 246                 return;
 247         }
 248         graph->top++;
 249         graph->stack[graph->top].link = entity->links.next;
 250         graph->stack[graph->top].entity = entity;
 251 }
 252
 253 static struct media_entity *stack_pop(struct media_graph *graph)
 254 {
 255         struct media_entity *entity;
 256
 257         entity = graph->stack[graph->top].entity;
 258         graph->top--;
 259
 260         return entity;
 261 }
 262
 263 #define link_top(en)    ((en)->stack[(en)->top].link)
 264 #define stack_top(en)   ((en)->stack[(en)->top].entity)
 265
 266 /**
 267  * media_graph_walk_init - Allocate resources for graph walk
 268  * @graph: Media graph structure that will be used to walk the graph
 269  * @mdev: Media device
 270  *
 271  * Reserve resources for graph walk in media device's current
 272  * state. The memory must be released using
 273  * media_graph_walk_free().
 274  *
 275  * Returns error on failure, zero on success.
 276  */
 277 __must_check int media_graph_walk_init(
 278         struct media_graph *graph, struct media_device *mdev)
 279 {
 280         return media_entity_enum_init(&graph->ent_enum, mdev);
 281 }
 282 EXPORT_SYMBOL_GPL(media_graph_walk_init);
 283
 284 /**
 285  * media_graph_walk_cleanup - Release resources related to graph walking
 286  * @graph: Media graph structure that was used to walk the graph
 287  */
 288 void media_graph_walk_cleanup(struct media_graph *graph)
 289 {
 290         media_entity_enum_cleanup(&graph->ent_enum);
 291 }
 292 EXPORT_SYMBOL_GPL(media_graph_walk_cleanup);
 293
 294 void media_graph_walk_start(struct media_graph *graph,
 295                             struct media_entity *entity)
 296 {
 297         media_entity_enum_zero(&graph->ent_enum);
 298         media_entity_enum_set(&graph->ent_enum, entity);
 299
 300         graph->top = 0;
 301         graph->stack[graph->top].entity = NULL;
 302         stack_push(graph, entity);
 303         dev_dbg(entity->graph_obj.mdev->dev,
 304                 "begin graph walk at '%s'\n", entity->name);
 305 }
 306 EXPORT_SYMBOL_GPL(media_graph_walk_start);
 307
 308 static void media_graph_walk_iter(struct media_graph *graph)
 309 {
 310         struct media_entity *entity = stack_top(graph);
 311         struct media_link *link;
 312         struct media_entity *next;
 313
 314         link = list_entry(link_top(graph), typeof(*link), list);
 315
 316         /* The link is not enabled so we do not follow. */
 317         if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
 318                 link_top(graph) = link_top(graph)->next;
 319                 dev_dbg(entity->graph_obj.mdev->dev,
 320                         "walk: skipping disabled link '%s':%u -> '%s':%u\n",
 321                         link->source->entity->name, link->source->index,
 322                         link->sink->entity->name, link->sink->index);
 323                 return;
 324         }
 325
 326         /* Get the entity at the other end of the link. */
 327         next = media_entity_other(entity, link);
 328
 329         /* Has the entity already been visited? */
 330         if (media_entity_enum_test_and_set(&graph->ent_enum, next)) {
 331                 link_top(graph) = link_top(graph)->next;
 332                 dev_dbg(entity->graph_obj.mdev->dev,
 333                         "walk: skipping entity '%s' (already seen)\n",
 334                         next->name);
 335                 return;
 336         }
 337
 338         /* Push the new entity to stack and start over. */
 339         link_top(graph) = link_top(graph)->next;
 340         stack_push(graph, next);
 341         dev_dbg(entity->graph_obj.mdev->dev, "walk: pushing '%s' on stack\n",
 342                 next->name);
 343         lockdep_assert_held(&entity->graph_obj.mdev->graph_mutex);
 344 }
 345
 346 struct media_entity *media_graph_walk_next(struct media_graph *graph)
 347 {
 348         struct media_entity *entity;
 349
 350         if (stack_top(graph) == NULL)
 351                 return NULL;
 352
 353         /*
 354          * Depth first search. Push entity to stack and continue from
 355          * top of the stack until no more entities on the level can be
 356          * found.
 357          */
 358         while (link_top(graph) != &stack_top(graph)->links)
 359                 media_graph_walk_iter(graph);
 360
 361         entity = stack_pop(graph);
 362         dev_dbg(entity->graph_obj.mdev->dev,
 363                 "walk: returning entity '%s'\n", entity->name);
 364
 365         return entity;
 366 }
 367 EXPORT_SYMBOL_GPL(media_graph_walk_next);
 368
 369 int media_entity_get_fwnode_pad(struct media_entity *entity,
 370                                 struct fwnode_handle *fwnode,
 371                                 unsigned long direction_flags)
 372 {
 373         struct fwnode_endpoint endpoint;
 374         unsigned int i;
 375         int ret;
 376
 377         if (!entity->ops || !entity->ops->get_fwnode_pad) {
 378                 for (i = 0; i < entity->num_pads; i++) {
 379                         if (entity->pads[i].flags & direction_flags)
 380                                 return i;
 381                 }
 382
 383                 return -ENXIO;
 384         }
 385
 386         ret = fwnode_graph_parse_endpoint(fwnode, &endpoint);
 387         if (ret)
 388                 return ret;
 389
 390         ret = entity->ops->get_fwnode_pad(entity, &endpoint);
 391         if (ret < 0)
 392                 return ret;
 393
 394         if (ret >= entity->num_pads)
 395                 return -ENXIO;
 396
 397         if (!(entity->pads[ret].flags & direction_flags))
 398                 return -ENXIO;
 399
 400         return ret;
 401 }
 402 EXPORT_SYMBOL_GPL(media_entity_get_fwnode_pad);
 403
 404 /* -----------------------------------------------------------------------------
 405  * Pipeline management
 406  */
 407
 408 __must_check int __media_pipeline_start(struct media_entity *entity,
 409                                         struct media_pipeline *pipe)
 410 {
 411         struct media_device *mdev = entity->graph_obj.mdev;
 412         struct media_graph *graph = &pipe->graph;
 413         struct media_entity *entity_err = entity;
 414         struct media_link *link;
 415         int ret;
 416
 417         if (!pipe->streaming_count++) {
 418                 ret = media_graph_walk_init(&pipe->graph, mdev);
 419                 if (ret)
 420                         goto error_graph_walk_start;
 421         }
 422
 423         media_graph_walk_start(&pipe->graph, entity);
 424
 425         while ((entity = media_graph_walk_next(graph))) {
 426                 DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
 427                 DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
 428
 429                 entity->stream_count++;
 430
 431                 if (entity->pipe && entity->pipe != pipe) {
 432                         pr_err("Pipe active for %s. Can't start for %s\n",
 433                                 entity->name,
 434                                 entity_err->name);
 435                         ret = -EBUSY;
 436                         goto error;
 437                 }
 438
 439                 entity->pipe = pipe;
 440
 441                 /* Already streaming --- no need to check. */
 442                 if (entity->stream_count > 1)
 443                         continue;
 444
 445                 if (!entity->ops || !entity->ops->link_validate)
 446                         continue;
 447
 448                 bitmap_zero(active, entity->num_pads);
 449                 bitmap_fill(has_no_links, entity->num_pads);
 450
 451                 list_for_each_entry(link, &entity->links, list) {
 452                         struct media_pad *pad = link->sink->entity == entity
 453                                                 ? link->sink : link->source;
 454
 455                         /* Mark that a pad is connected by a link. */
 456                         bitmap_clear(has_no_links, pad->index, 1);
 457
 458                         /*
 459                          * Pads that either do not need to connect or
 460                          * are connected through an enabled link are
 461                          * fine.
 462                          */
 463                         if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
 464                             link->flags & MEDIA_LNK_FL_ENABLED)
 465                                 bitmap_set(active, pad->index, 1);
 466
 467                         /*
 468                          * Link validation will only take place for
 469                          * sink ends of the link that are enabled.
 470                          */
 471                         if (link->sink != pad ||
 472                             !(link->flags & MEDIA_LNK_FL_ENABLED))
 473                                 continue;
 474
 475                         ret = entity->ops->link_validate(link);
 476                         if (ret < 0 && ret != -ENOIOCTLCMD) {
 477                                 dev_dbg(entity->graph_obj.mdev->dev,
 478                                         "link validation failed for '%s':%u -> '%s':%u, error %d\n",
 479                                         link->source->entity->name,
 480                                         link->source->index,
 481                                         entity->name, link->sink->index, ret);
 482                                 goto error;
 483                         }
 484                 }
 485
 486                 /* Either no links or validated links are fine. */
 487                 bitmap_or(active, active, has_no_links, entity->num_pads);
 488
 489                 if (!bitmap_full(active, entity->num_pads)) {
 490                         ret = -ENOLINK;
 491                         dev_dbg(entity->graph_obj.mdev->dev,
 492                                 "'%s':%u must be connected by an enabled link\n",
 493                                 entity->name,
 494                                 (unsigned)find_first_zero_bit(
 495                                         active, entity->num_pads));
 496                         goto error;
 497                 }
 498         }
 499
 500         return 0;
 501
 502 error:
 503         /*
 504          * Link validation on graph failed. We revert what we did and
 505          * return the error.
 506          */
 507         media_graph_walk_start(graph, entity_err);
 508
 509         while ((entity_err = media_graph_walk_next(graph))) {
 510                 /* Sanity check for negative stream_count */
 511                 if (!WARN_ON_ONCE(entity_err->stream_count <= 0)) {
 512                         entity_err->stream_count--;
 513                         if (entity_err->stream_count == 0)
 514                                 entity_err->pipe = NULL;
 515                 }
 516
 517                 /*
 518                  * We haven't increased stream_count further than this
 519                  * so we quit here.
 520                  */
 521                 if (entity_err == entity)
 522                         break;
 523         }
 524
 525 error_graph_walk_start:
 526         if (!--pipe->streaming_count)
 527                 media_graph_walk_cleanup(graph);
 528
 529         return ret;
 530 }
 531 EXPORT_SYMBOL_GPL(__media_pipeline_start);
 532
 533 __must_check int media_pipeline_start(struct media_entity *entity,
 534                                       struct media_pipeline *pipe)
 535 {
 536         struct media_device *mdev = entity->graph_obj.mdev;
 537         int ret;
 538
 539         mutex_lock(&mdev->graph_mutex);
 540         ret = __media_pipeline_start(entity, pipe);
 541         mutex_unlock(&mdev->graph_mutex);
 542         return ret;
 543 }
 544 EXPORT_SYMBOL_GPL(media_pipeline_start);
 545
 546 void __media_pipeline_stop(struct media_entity *entity)
 547 {
 548         struct media_graph *graph = &entity->pipe->graph;
 549         struct media_pipeline *pipe = entity->pipe;
 550
 551         /*
 552          * If the following check fails, the driver has performed an
 553          * unbalanced call to media_pipeline_stop()
 554          */
 555         if (WARN_ON(!pipe))
 556                 return;
 557
 558         media_graph_walk_start(graph, entity);
 559
 560         while ((entity = media_graph_walk_next(graph))) {
 561                 /* Sanity check for negative stream_count */
 562                 if (!WARN_ON_ONCE(entity->stream_count <= 0)) {
 563                         entity->stream_count--;
 564                         if (entity->stream_count == 0)
 565                                 entity->pipe = NULL;
 566                 }
 567         }
 568
 569         if (!--pipe->streaming_count)
 570                 media_graph_walk_cleanup(graph);
 571
 572 }
 573 EXPORT_SYMBOL_GPL(__media_pipeline_stop);
 574
 575 void media_pipeline_stop(struct media_entity *entity)
 576 {
 577         struct media_device *mdev = entity->graph_obj.mdev;
 578
 579         mutex_lock(&mdev->graph_mutex);
 580         __media_pipeline_stop(entity);
 581         mutex_unlock(&mdev->graph_mutex);
 582 }
 583 EXPORT_SYMBOL_GPL(media_pipeline_stop);
 584
 585 /* -----------------------------------------------------------------------------
 586  * Links management
 587  */
 588
 589 static struct media_link *media_add_link(struct list_head *head)
 590 {
 591         struct media_link *link;
 592
 593         link = kzalloc(sizeof(*link), GFP_KERNEL);
 594         if (link == NULL)
 595                 return NULL;
 596
 597         list_add_tail(&link->list, head);
 598
 599         return link;
 600 }
 601
 602 static void __media_entity_remove_link(struct media_entity *entity,
 603                                        struct media_link *link)
 604 {
 605         struct media_link *rlink, *tmp;
 606         struct media_entity *remote;
 607
 608         if (link->source->entity == entity)
 609                 remote = link->sink->entity;
 610         else
 611                 remote = link->source->entity;
 612
 613         list_for_each_entry_safe(rlink, tmp, &remote->links, list) {
 614                 if (rlink != link->reverse)
 615                         continue;
 616
 617                 if (link->source->entity == entity)
 618                         remote->num_backlinks--;
 619
 620                 /* Remove the remote link */
 621                 list_del(&rlink->list);
 622                 media_gobj_destroy(&rlink->graph_obj);
 623                 kfree(rlink);
 624
 625                 if (--remote->num_links == 0)
 626                         break;
 627         }
 628         list_del(&link->list);
 629         media_gobj_destroy(&link->graph_obj);
 630         kfree(link);
 631 }
 632
 633 int media_get_pad_index(struct media_entity *entity, bool is_sink,
 634                         enum media_pad_signal_type sig_type)
 635 {
 636         int i;
 637         bool pad_is_sink;
 638
 639         if (!entity)
 640                 return -EINVAL;
 641
 642         for (i = 0; i < entity->num_pads; i++) {
 643                 if (entity->pads[i].flags & MEDIA_PAD_FL_SINK)
 644                         pad_is_sink = true;
 645                 else if (entity->pads[i].flags & MEDIA_PAD_FL_SOURCE)
 646                         pad_is_sink = false;
 647                 else
 648                         continue;       /* This is an error! */
 649
 650                 if (pad_is_sink != is_sink)
 651                         continue;
 652                 if (entity->pads[i].sig_type == sig_type)
 653                         return i;
 654         }
 655         return -EINVAL;
 656 }
 657 EXPORT_SYMBOL_GPL(media_get_pad_index);
 658
 659 int
 660 media_create_pad_link(struct media_entity *source, u16 source_pad,
 661                          struct media_entity *sink, u16 sink_pad, u32 flags)
 662 {
 663         struct media_link *link;
 664         struct media_link *backlink;
 665
 666         if (WARN_ON(!source || !sink) ||
 667             WARN_ON(source_pad >= source->num_pads) ||
 668             WARN_ON(sink_pad >= sink->num_pads))
 669                 return -EINVAL;
 670         if (WARN_ON(!(source->pads[source_pad].flags & MEDIA_PAD_FL_SOURCE)))
 671                 return -EINVAL;
 672         if (WARN_ON(!(sink->pads[sink_pad].flags & MEDIA_PAD_FL_SINK)))
 673                 return -EINVAL;
 674
 675         link = media_add_link(&source->links);
 676         if (link == NULL)
 677                 return -ENOMEM;
 678
 679         link->source = &source->pads[source_pad];
 680         link->sink = &sink->pads[sink_pad];
 681         link->flags = flags & ~MEDIA_LNK_FL_INTERFACE_LINK;
 682
 683         /* Initialize graph object embedded at the new link */
 684         media_gobj_create(source->graph_obj.mdev, MEDIA_GRAPH_LINK,
 685                         &link->graph_obj);
 686
 687         /* Create the backlink. Backlinks are used to help graph traversal and
 688          * are not reported to userspace.
 689          */
 690         backlink = media_add_link(&sink->links);
 691         if (backlink == NULL) {
 692                 __media_entity_remove_link(source, link);
 693                 return -ENOMEM;
 694         }
 695
 696         backlink->source = &source->pads[source_pad];
 697         backlink->sink = &sink->pads[sink_pad];
 698         backlink->flags = flags;
 699         backlink->is_backlink = true;
 700
 701         /* Initialize graph object embedded at the new link */
 702         media_gobj_create(sink->graph_obj.mdev, MEDIA_GRAPH_LINK,
 703                         &backlink->graph_obj);
 704
 705         link->reverse = backlink;
 706         backlink->reverse = link;
 707
 708         sink->num_backlinks++;
 709         sink->num_links++;
 710         source->num_links++;
 711
 712         return 0;
 713 }
 714 EXPORT_SYMBOL_GPL(media_create_pad_link);
 715
 716 int media_create_pad_links(const struct media_device *mdev,
 717                            const u32 source_function,
 718                            struct media_entity *source,
 719                            const u16 source_pad,
 720                            const u32 sink_function,
 721                            struct media_entity *sink,
 722                            const u16 sink_pad,
 723                            u32 flags,
 724                            const bool allow_both_undefined)
 725 {
 726         struct media_entity *entity;
 727         unsigned function;
 728         int ret;
 729
 730         /* Trivial case: 1:1 relation */
 731         if (source && sink)
 732                 return media_create_pad_link(source, source_pad,
 733                                              sink, sink_pad, flags);
 734
 735         /* Worse case scenario: n:n relation */
 736         if (!source && !sink) {
 737                 if (!allow_both_undefined)
 738                         return 0;
 739                 media_device_for_each_entity(source, mdev) {
 740                         if (source->function != source_function)
 741                                 continue;
 742                         media_device_for_each_entity(sink, mdev) {
 743                                 if (sink->function != sink_function)
 744                                         continue;
 745                                 ret = media_create_pad_link(source, source_pad,
 746                                                             sink, sink_pad,
 747                                                             flags);
 748                                 if (ret)
 749                                         return ret;
 750                                 flags &= ~(MEDIA_LNK_FL_ENABLED |
 751                                            MEDIA_LNK_FL_IMMUTABLE);
 752                         }
 753                 }
 754                 return 0;
 755         }
 756
 757         /* Handle 1:n and n:1 cases */
 758         if (source)
 759                 function = sink_function;
 760         else
 761                 function = source_function;
 762
 763         media_device_for_each_entity(entity, mdev) {
 764                 if (entity->function != function)
 765                         continue;
 766
 767                 if (source)
 768                         ret = media_create_pad_link(source, source_pad,
 769                                                     entity, sink_pad, flags);
 770                 else
 771                         ret = media_create_pad_link(entity, source_pad,
 772                                                     sink, sink_pad, flags);
 773                 if (ret)
 774                         return ret;
 775                 flags &= ~(MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE);
 776         }
 777         return 0;
 778 }
 779 EXPORT_SYMBOL_GPL(media_create_pad_links);
 780
 781 void __media_entity_remove_links(struct media_entity *entity)
 782 {
 783         struct media_link *link, *tmp;
 784
 785         list_for_each_entry_safe(link, tmp, &entity->links, list)
 786                 __media_entity_remove_link(entity, link);
 787
 788         entity->num_links = 0;
 789         entity->num_backlinks = 0;
 790 }
 791 EXPORT_SYMBOL_GPL(__media_entity_remove_links);
 792
 793 void media_entity_remove_links(struct media_entity *entity)
 794 {
 795         struct media_device *mdev = entity->graph_obj.mdev;
 796
 797         /* Do nothing if the entity is not registered. */
 798         if (mdev == NULL)
 799                 return;
 800
 801         mutex_lock(&mdev->graph_mutex);
 802         __media_entity_remove_links(entity);
 803         mutex_unlock(&mdev->graph_mutex);
 804 }
 805 EXPORT_SYMBOL_GPL(media_entity_remove_links);
 806
 807 static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
 808 {
 809         int ret;
 810
 811         /* Notify both entities. */
 812         ret = media_entity_call(link->source->entity, link_setup,
 813                                 link->source, link->sink, flags);
 814         if (ret < 0 && ret != -ENOIOCTLCMD)
 815                 return ret;
 816
 817         ret = media_entity_call(link->sink->entity, link_setup,
 818                                 link->sink, link->source, flags);
 819         if (ret < 0 && ret != -ENOIOCTLCMD) {
 820                 media_entity_call(link->source->entity, link_setup,
 821                                   link->source, link->sink, link->flags);
 822                 return ret;
 823         }
 824
 825         link->flags = flags;
 826         link->reverse->flags = link->flags;
 827
 828         return 0;
 829 }
 830
 831 int __media_entity_setup_link(struct media_link *link, u32 flags)
 832 {
 833         const u32 mask = MEDIA_LNK_FL_ENABLED;
 834         struct media_device *mdev;
 835         struct media_entity *source, *sink;
 836         int ret = -EBUSY;
 837
 838         if (link == NULL)
 839                 return -EINVAL;
 840
 841         /* The non-modifiable link flags must not be modified. */
 842         if ((link->flags & ~mask) != (flags & ~mask))
 843                 return -EINVAL;
 844
 845         if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
 846                 return link->flags == flags ? 0 : -EINVAL;
 847
 848         if (link->flags == flags)
 849                 return 0;
 850
 851         source = link->source->entity;
 852         sink = link->sink->entity;
 853
 854         if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
 855             (source->stream_count || sink->stream_count))
 856                 return -EBUSY;
 857
 858         mdev = source->graph_obj.mdev;
 859
 860         if (mdev->ops && mdev->ops->link_notify) {
 861                 ret = mdev->ops->link_notify(link, flags,
 862                                              MEDIA_DEV_NOTIFY_PRE_LINK_CH);
 863                 if (ret < 0)
 864                         return ret;
 865         }
 866
 867         ret = __media_entity_setup_link_notify(link, flags);
 868
 869         if (mdev->ops && mdev->ops->link_notify)
 870                 mdev->ops->link_notify(link, flags,
 871                                        MEDIA_DEV_NOTIFY_POST_LINK_CH);
 872
 873         return ret;
 874 }
 875 EXPORT_SYMBOL_GPL(__media_entity_setup_link);
 876
 877 int media_entity_setup_link(struct media_link *link, u32 flags)
 878 {
 879         int ret;
 880
 881         mutex_lock(&link->graph_obj.mdev->graph_mutex);
 882         ret = __media_entity_setup_link(link, flags);
 883         mutex_unlock(&link->graph_obj.mdev->graph_mutex);
 884
 885         return ret;
 886 }
 887 EXPORT_SYMBOL_GPL(media_entity_setup_link);
 888
 889 struct media_link *
 890 media_entity_find_link(struct media_pad *source, struct media_pad *sink)
 891 {
 892         struct media_link *link;
 893
 894         list_for_each_entry(link, &source->entity->links, list) {
 895                 if (link->source->entity == source->entity &&
 896                     link->source->index == source->index &&
 897                     link->sink->entity == sink->entity &&
 898                     link->sink->index == sink->index)
 899                         return link;
 900         }
 901
 902         return NULL;
 903 }
 904 EXPORT_SYMBOL_GPL(media_entity_find_link);
 905
 906 struct media_pad *media_entity_remote_pad(const struct media_pad *pad)
 907 {
 908         struct media_link *link;
 909
 910         list_for_each_entry(link, &pad->entity->links, list) {
 911                 if (!(link->flags & MEDIA_LNK_FL_ENABLED))
 912                         continue;
 913
 914                 if (link->source == pad)
 915                         return link->sink;
 916
 917                 if (link->sink == pad)
 918                         return link->source;
 919         }
 920
 921         return NULL;
 922
 923 }
 924 EXPORT_SYMBOL_GPL(media_entity_remote_pad);
 925
 926 static void media_interface_init(struct media_device *mdev,
 927                                  struct media_interface *intf,
 928                                  u32 gobj_type,
 929                                  u32 intf_type, u32 flags)
 930 {
 931         intf->type = intf_type;
 932         intf->flags = flags;
 933         INIT_LIST_HEAD(&intf->links);
 934
 935         media_gobj_create(mdev, gobj_type, &intf->graph_obj);
 936 }
 937
 938 /* Functions related to the media interface via device nodes */
 939
 940 struct media_intf_devnode *media_devnode_create(struct media_device *mdev,
 941                                                 u32 type, u32 flags,
 942                                                 u32 major, u32 minor)
 943 {
 944         struct media_intf_devnode *devnode;
 945
 946         devnode = kzalloc(sizeof(*devnode), GFP_KERNEL);
 947         if (!devnode)
 948                 return NULL;
 949
 950         devnode->major = major;
 951         devnode->minor = minor;
 952
 953         media_interface_init(mdev, &devnode->intf, MEDIA_GRAPH_INTF_DEVNODE,
 954                              type, flags);
 955
 956         return devnode;
 957 }
 958 EXPORT_SYMBOL_GPL(media_devnode_create);
 959
 960 void media_devnode_remove(struct media_intf_devnode *devnode)
 961 {
 962         media_remove_intf_links(&devnode->intf);
 963         media_gobj_destroy(&devnode->intf.graph_obj);
 964         kfree(devnode);
 965 }
 966 EXPORT_SYMBOL_GPL(media_devnode_remove);
 967
 968 struct media_link *media_create_intf_link(struct media_entity *entity,
 969                                             struct media_interface *intf,
 970                                             u32 flags)
 971 {
 972         struct media_link *link;
 973
 974         link = media_add_link(&intf->links);
 975         if (link == NULL)
 976                 return NULL;
 977
 978         link->intf = intf;
 979         link->entity = entity;
 980         link->flags = flags | MEDIA_LNK_FL_INTERFACE_LINK;
 981
 982         /* Initialize graph object embedded at the new link */
 983         media_gobj_create(intf->graph_obj.mdev, MEDIA_GRAPH_LINK,
 984                         &link->graph_obj);
 985
 986         return link;
 987 }
 988 EXPORT_SYMBOL_GPL(media_create_intf_link);
 989
 990 void __media_remove_intf_link(struct media_link *link)
 991 {
 992         list_del(&link->list);
 993         media_gobj_destroy(&link->graph_obj);
 994         kfree(link);
 995 }
 996 EXPORT_SYMBOL_GPL(__media_remove_intf_link);
 997
 998 void media_remove_intf_link(struct media_link *link)
 999 {
1000         struct media_device *mdev = link->graph_obj.mdev;
1001
1002         /* Do nothing if the intf is not registered. */
1003         if (mdev == NULL)
1004                 return;
1005
1006         mutex_lock(&mdev->graph_mutex);
1007         __media_remove_intf_link(link);
1008         mutex_unlock(&mdev->graph_mutex);
1009 }
1010 EXPORT_SYMBOL_GPL(media_remove_intf_link);
1011
1012 void __media_remove_intf_links(struct media_interface *intf)
1013 {
1014         struct media_link *link, *tmp;
1015
1016         list_for_each_entry_safe(link, tmp, &intf->links, list)
1017                 __media_remove_intf_link(link);
1018
1019 }
1020 EXPORT_SYMBOL_GPL(__media_remove_intf_links);
1021
1022 void media_remove_intf_links(struct media_interface *intf)
1023 {
1024         struct media_device *mdev = intf->graph_obj.mdev;
1025
1026         /* Do nothing if the intf is not registered. */
1027         if (mdev == NULL)
1028                 return;
1029
1030         mutex_lock(&mdev->graph_mutex);
1031         __media_remove_intf_links(intf);
1032         mutex_unlock(&mdev->graph_mutex);
1033 }
1034 EXPORT_SYMBOL_GPL(media_remove_intf_links);