root/drivers/base/component.c

DEFINITIONS

1. component_devices_show
2. component_debug_init
3. component_master_debugfs_add
4. component_master_debugfs_del
5. component_master_debugfs_add
6. component_master_debugfs_del
7. __master_find
8. find_component
9. find_components
10. remove_component
11. try_to_bring_up_master
12. try_to_bring_up_masters
13. take_down_master
14. component_match_release
15. devm_component_match_release
16. component_match_realloc
17. __component_match_add
18. component_match_add_release
19. component_match_add_typed
20. free_master
21. component_master_add_with_match
22. component_master_del
23. component_unbind
24. component_unbind_all
25. component_bind
26. component_bind_all
27. __component_add
28. component_add_typed
29. component_add
30. component_del

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Componentized device handling.
   4  *
   5  * This is work in progress.  We gather up the component devices into a list,
   6  * and bind them when instructed.  At the moment, we're specific to the DRM
   7  * subsystem, and only handles one master device, but this doesn't have to be
   8  * the case.
   9  */
  10 #include <linux/component.h>
  11 #include <linux/device.h>
  12 #include <linux/kref.h>
  13 #include <linux/list.h>
  14 #include <linux/module.h>
  15 #include <linux/mutex.h>
  16 #include <linux/slab.h>
  17 #include <linux/debugfs.h>
  18 
  19 /**
  20  * DOC: overview
  21  *
  22  * The component helper allows drivers to collect a pile of sub-devices,
  23  * including their bound drivers, into an aggregate driver. Various subsystems
  24  * already provide functions to get hold of such components, e.g.
  25  * of_clk_get_by_name(). The component helper can be used when such a
  26  * subsystem-specific way to find a device is not available: The component
  27  * helper fills the niche of aggregate drivers for specific hardware, where
  28  * further standardization into a subsystem would not be practical. The common
  29  * example is when a logical device (e.g. a DRM display driver) is spread around
  30  * the SoC on various components (scanout engines, blending blocks, transcoders
  31  * for various outputs and so on).
  32  *
  33  * The component helper also doesn't solve runtime dependencies, e.g. for system
  34  * suspend and resume operations. See also :ref:`device links<device_link>`.
  35  *
  36  * Components are registered using component_add() and unregistered with
  37  * component_del(), usually from the driver's probe and disconnect functions.
  38  *
  39  * Aggregate drivers first assemble a component match list of what they need
  40  * using component_match_add(). This is then registered as an aggregate driver
  41  * using component_master_add_with_match(), and unregistered using
  42  * component_master_del().
  43  */
  44 
  45 struct component;
  46 
  47 struct component_match_array {
  48         void *data;
  49         int (*compare)(struct device *, void *);
  50         int (*compare_typed)(struct device *, int, void *);
  51         void (*release)(struct device *, void *);
  52         struct component *component;
  53         bool duplicate;
  54 };
  55 
  56 struct component_match {
  57         size_t alloc;
  58         size_t num;
  59         struct component_match_array *compare;
  60 };
  61 
  62 struct master {
  63         struct list_head node;
  64         bool bound;
  65 
  66         const struct component_master_ops *ops;
  67         struct device *dev;
  68         struct component_match *match;
  69         struct dentry *dentry;
  70 };
  71 
  72 struct component {
  73         struct list_head node;
  74         struct master *master;
  75         bool bound;
  76 
  77         const struct component_ops *ops;
  78         int subcomponent;
  79         struct device *dev;
  80 };
  81 
  82 static DEFINE_MUTEX(component_mutex);
  83 static LIST_HEAD(component_list);
  84 static LIST_HEAD(masters);
  85 
  86 #ifdef CONFIG_DEBUG_FS
  87 
  88 static struct dentry *component_debugfs_dir;
  89 
  90 static int component_devices_show(struct seq_file *s, void *data)
  91 {
  92         struct master *m = s->private;
  93         struct component_match *match = m->match;
  94         size_t i;
  95 
  96         mutex_lock(&component_mutex);
  97         seq_printf(s, "%-40s %20s\n", "master name", "status");
  98         seq_puts(s, "-------------------------------------------------------------\n");
  99         seq_printf(s, "%-40s %20s\n\n",
 100                    dev_name(m->dev), m->bound ? "bound" : "not bound");
 101 
 102         seq_printf(s, "%-40s %20s\n", "device name", "status");
 103         seq_puts(s, "-------------------------------------------------------------\n");
 104         for (i = 0; i < match->num; i++) {
 105                 struct component *component = match->compare[i].component;
 106 
 107                 seq_printf(s, "%-40s %20s\n",
 108                            component ? dev_name(component->dev) : "(unknown)",
 109                            component ? (component->bound ? "bound" : "not bound") : "not registered");
 110         }
 111         mutex_unlock(&component_mutex);
 112 
 113         return 0;
 114 }
 115 
 116 DEFINE_SHOW_ATTRIBUTE(component_devices);
 117 
 118 static int __init component_debug_init(void)
 119 {
 120         component_debugfs_dir = debugfs_create_dir("device_component", NULL);
 121 
 122         return 0;
 123 }
 124 
 125 core_initcall(component_debug_init);
 126 
 127 static void component_master_debugfs_add(struct master *m)
 128 {
 129         m->dentry = debugfs_create_file(dev_name(m->dev), 0444,
 130                                         component_debugfs_dir,
 131                                         m, &component_devices_fops);
 132 }
 133 
 134 static void component_master_debugfs_del(struct master *m)
 135 {
 136         debugfs_remove(m->dentry);
 137         m->dentry = NULL;
 138 }
 139 
 140 #else
 141 
 142 static void component_master_debugfs_add(struct master *m)
 143 { }
 144 
 145 static void component_master_debugfs_del(struct master *m)
 146 { }
 147 
 148 #endif
 149 
 150 static struct master *__master_find(struct device *dev,
 151         const struct component_master_ops *ops)
 152 {
 153         struct master *m;
 154 
 155         list_for_each_entry(m, &masters, node)
 156                 if (m->dev == dev && (!ops || m->ops == ops))
 157                         return m;
 158 
 159         return NULL;
 160 }
 161 
 162 static struct component *find_component(struct master *master,
 163         struct component_match_array *mc)
 164 {
 165         struct component *c;
 166 
 167         list_for_each_entry(c, &component_list, node) {
 168                 if (c->master && c->master != master)
 169                         continue;
 170 
 171                 if (mc->compare && mc->compare(c->dev, mc->data))
 172                         return c;
 173 
 174                 if (mc->compare_typed &&
 175                     mc->compare_typed(c->dev, c->subcomponent, mc->data))
 176                         return c;
 177         }
 178 
 179         return NULL;
 180 }
 181 
 182 static int find_components(struct master *master)
 183 {
 184         struct component_match *match = master->match;
 185         size_t i;
 186         int ret = 0;
 187 
 188         /*
 189          * Scan the array of match functions and attach
 190          * any components which are found to this master.
 191          */
 192         for (i = 0; i < match->num; i++) {
 193                 struct component_match_array *mc = &match->compare[i];
 194                 struct component *c;
 195 
 196                 dev_dbg(master->dev, "Looking for component %zu\n", i);
 197 
 198                 if (match->compare[i].component)
 199                         continue;
 200 
 201                 c = find_component(master, mc);
 202                 if (!c) {
 203                         ret = -ENXIO;
 204                         break;
 205                 }
 206 
 207                 dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master);
 208 
 209                 /* Attach this component to the master */
 210                 match->compare[i].duplicate = !!c->master;
 211                 match->compare[i].component = c;
 212                 c->master = master;
 213         }
 214         return ret;
 215 }
 216 
 217 /* Detach component from associated master */
 218 static void remove_component(struct master *master, struct component *c)
 219 {
 220         size_t i;
 221 
 222         /* Detach the component from this master. */
 223         for (i = 0; i < master->match->num; i++)
 224                 if (master->match->compare[i].component == c)
 225                         master->match->compare[i].component = NULL;
 226 }
 227 
 228 /*
 229  * Try to bring up a master.  If component is NULL, we're interested in
 230  * this master, otherwise it's a component which must be present to try
 231  * and bring up the master.
 232  *
 233  * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
 234  */
 235 static int try_to_bring_up_master(struct master *master,
 236         struct component *component)
 237 {
 238         int ret;
 239 
 240         dev_dbg(master->dev, "trying to bring up master\n");
 241 
 242         if (find_components(master)) {
 243                 dev_dbg(master->dev, "master has incomplete components\n");
 244                 return 0;
 245         }
 246 
 247         if (component && component->master != master) {
 248                 dev_dbg(master->dev, "master is not for this component (%s)\n",
 249                         dev_name(component->dev));
 250                 return 0;
 251         }
 252 
 253         if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
 254                 return -ENOMEM;
 255 
 256         /* Found all components */
 257         ret = master->ops->bind(master->dev);
 258         if (ret < 0) {
 259                 devres_release_group(master->dev, NULL);
 260                 if (ret != -EPROBE_DEFER)
 261                         dev_info(master->dev, "master bind failed: %d\n", ret);
 262                 return ret;
 263         }
 264 
 265         master->bound = true;
 266         return 1;
 267 }
 268 
 269 static int try_to_bring_up_masters(struct component *component)
 270 {
 271         struct master *m;
 272         int ret = 0;
 273 
 274         list_for_each_entry(m, &masters, node) {
 275                 if (!m->bound) {
 276                         ret = try_to_bring_up_master(m, component);
 277                         if (ret != 0)
 278                                 break;
 279                 }
 280         }
 281 
 282         return ret;
 283 }
 284 
 285 static void take_down_master(struct master *master)
 286 {
 287         if (master->bound) {
 288                 master->ops->unbind(master->dev);
 289                 devres_release_group(master->dev, NULL);
 290                 master->bound = false;
 291         }
 292 }
 293 
 294 static void component_match_release(struct device *master,
 295         struct component_match *match)
 296 {
 297         unsigned int i;
 298 
 299         for (i = 0; i < match->num; i++) {
 300                 struct component_match_array *mc = &match->compare[i];
 301 
 302                 if (mc->release)
 303                         mc->release(master, mc->data);
 304         }
 305 
 306         kfree(match->compare);
 307 }
 308 
 309 static void devm_component_match_release(struct device *dev, void *res)
 310 {
 311         component_match_release(dev, res);
 312 }
 313 
 314 static int component_match_realloc(struct device *dev,
 315         struct component_match *match, size_t num)
 316 {
 317         struct component_match_array *new;
 318 
 319         if (match->alloc == num)
 320                 return 0;
 321 
 322         new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);
 323         if (!new)
 324                 return -ENOMEM;
 325 
 326         if (match->compare) {
 327                 memcpy(new, match->compare, sizeof(*new) *
 328                                             min(match->num, num));
 329                 kfree(match->compare);
 330         }
 331         match->compare = new;
 332         match->alloc = num;
 333 
 334         return 0;
 335 }
 336 
 337 static void __component_match_add(struct device *master,
 338         struct component_match **matchptr,
 339         void (*release)(struct device *, void *),
 340         int (*compare)(struct device *, void *),
 341         int (*compare_typed)(struct device *, int, void *),
 342         void *compare_data)
 343 {
 344         struct component_match *match = *matchptr;
 345 
 346         if (IS_ERR(match))
 347                 return;
 348 
 349         if (!match) {
 350                 match = devres_alloc(devm_component_match_release,
 351                                      sizeof(*match), GFP_KERNEL);
 352                 if (!match) {
 353                         *matchptr = ERR_PTR(-ENOMEM);
 354                         return;
 355                 }
 356 
 357                 devres_add(master, match);
 358 
 359                 *matchptr = match;
 360         }
 361 
 362         if (match->num == match->alloc) {
 363                 size_t new_size = match->alloc + 16;
 364                 int ret;
 365 
 366                 ret = component_match_realloc(master, match, new_size);
 367                 if (ret) {
 368                         *matchptr = ERR_PTR(ret);
 369                         return;
 370                 }
 371         }
 372 
 373         match->compare[match->num].compare = compare;
 374         match->compare[match->num].compare_typed = compare_typed;
 375         match->compare[match->num].release = release;
 376         match->compare[match->num].data = compare_data;
 377         match->compare[match->num].component = NULL;
 378         match->num++;
 379 }
 380 
 381 /**
 382  * component_match_add_release - add a component match entry with release callback
 383  * @master: device with the aggregate driver
 384  * @matchptr: pointer to the list of component matches
 385  * @release: release function for @compare_data
 386  * @compare: compare function to match against all components
 387  * @compare_data: opaque pointer passed to the @compare function
 388  *
 389  * Adds a new component match to the list stored in @matchptr, which the @master
 390  * aggregate driver needs to function. The list of component matches pointed to
 391  * by @matchptr must be initialized to NULL before adding the first match. This
 392  * only matches against components added with component_add().
 393  *
 394  * The allocated match list in @matchptr is automatically released using devm
 395  * actions, where upon @release will be called to free any references held by
 396  * @compare_data, e.g. when @compare_data is a &device_node that must be
 397  * released with of_node_put().
 398  *
 399  * See also component_match_add() and component_match_add_typed().
 400  */
 401 void component_match_add_release(struct device *master,
 402         struct component_match **matchptr,
 403         void (*release)(struct device *, void *),
 404         int (*compare)(struct device *, void *), void *compare_data)
 405 {
 406         __component_match_add(master, matchptr, release, compare, NULL,
 407                               compare_data);
 408 }
 409 EXPORT_SYMBOL(component_match_add_release);
 410 
 411 /**
 412  * component_match_add_typed - add a component match entry for a typed component
 413  * @master: device with the aggregate driver
 414  * @matchptr: pointer to the list of component matches
 415  * @compare_typed: compare function to match against all typed components
 416  * @compare_data: opaque pointer passed to the @compare function
 417  *
 418  * Adds a new component match to the list stored in @matchptr, which the @master
 419  * aggregate driver needs to function. The list of component matches pointed to
 420  * by @matchptr must be initialized to NULL before adding the first match. This
 421  * only matches against components added with component_add_typed().
 422  *
 423  * The allocated match list in @matchptr is automatically released using devm
 424  * actions.
 425  *
 426  * See also component_match_add_release() and component_match_add_typed().
 427  */
 428 void component_match_add_typed(struct device *master,
 429         struct component_match **matchptr,
 430         int (*compare_typed)(struct device *, int, void *), void *compare_data)
 431 {
 432         __component_match_add(master, matchptr, NULL, NULL, compare_typed,
 433                               compare_data);
 434 }
 435 EXPORT_SYMBOL(component_match_add_typed);
 436 
 437 static void free_master(struct master *master)
 438 {
 439         struct component_match *match = master->match;
 440         int i;
 441 
 442         component_master_debugfs_del(master);
 443         list_del(&master->node);
 444 
 445         if (match) {
 446                 for (i = 0; i < match->num; i++) {
 447                         struct component *c = match->compare[i].component;
 448                         if (c)
 449                                 c->master = NULL;
 450                 }
 451         }
 452 
 453         kfree(master);
 454 }
 455 
 456 /**
 457  * component_master_add_with_match - register an aggregate driver
 458  * @dev: device with the aggregate driver
 459  * @ops: callbacks for the aggregate driver
 460  * @match: component match list for the aggregate driver
 461  *
 462  * Registers a new aggregate driver consisting of the components added to @match
 463  * by calling one of the component_match_add() functions. Once all components in
 464  * @match are available, it will be assembled by calling
 465  * &component_master_ops.bind from @ops. Must be unregistered by calling
 466  * component_master_del().
 467  */
 468 int component_master_add_with_match(struct device *dev,
 469         const struct component_master_ops *ops,
 470         struct component_match *match)
 471 {
 472         struct master *master;
 473         int ret;
 474 
 475         /* Reallocate the match array for its true size */
 476         ret = component_match_realloc(dev, match, match->num);
 477         if (ret)
 478                 return ret;
 479 
 480         master = kzalloc(sizeof(*master), GFP_KERNEL);
 481         if (!master)
 482                 return -ENOMEM;
 483 
 484         master->dev = dev;
 485         master->ops = ops;
 486         master->match = match;
 487 
 488         component_master_debugfs_add(master);
 489         /* Add to the list of available masters. */
 490         mutex_lock(&component_mutex);
 491         list_add(&master->node, &masters);
 492 
 493         ret = try_to_bring_up_master(master, NULL);
 494 
 495         if (ret < 0)
 496                 free_master(master);
 497 
 498         mutex_unlock(&component_mutex);
 499 
 500         return ret < 0 ? ret : 0;
 501 }
 502 EXPORT_SYMBOL_GPL(component_master_add_with_match);
 503 
 504 /**
 505  * component_master_del - unregister an aggregate driver
 506  * @dev: device with the aggregate driver
 507  * @ops: callbacks for the aggregate driver
 508  *
 509  * Unregisters an aggregate driver registered with
 510  * component_master_add_with_match(). If necessary the aggregate driver is first
 511  * disassembled by calling &component_master_ops.unbind from @ops.
 512  */
 513 void component_master_del(struct device *dev,
 514         const struct component_master_ops *ops)
 515 {
 516         struct master *master;
 517 
 518         mutex_lock(&component_mutex);
 519         master = __master_find(dev, ops);
 520         if (master) {
 521                 take_down_master(master);
 522                 free_master(master);
 523         }
 524         mutex_unlock(&component_mutex);
 525 }
 526 EXPORT_SYMBOL_GPL(component_master_del);
 527 
 528 static void component_unbind(struct component *component,
 529         struct master *master, void *data)
 530 {
 531         WARN_ON(!component->bound);
 532 
 533         component->ops->unbind(component->dev, master->dev, data);
 534         component->bound = false;
 535 
 536         /* Release all resources claimed in the binding of this component */
 537         devres_release_group(component->dev, component);
 538 }
 539 
 540 /**
 541  * component_unbind_all - unbind all components of an aggregate driver
 542  * @master_dev: device with the aggregate driver
 543  * @data: opaque pointer, passed to all components
 544  *
 545  * Unbinds all components of the aggregate @dev by passing @data to their
 546  * &component_ops.unbind functions. Should be called from
 547  * &component_master_ops.unbind.
 548  */
 549 void component_unbind_all(struct device *master_dev, void *data)
 550 {
 551         struct master *master;
 552         struct component *c;
 553         size_t i;
 554 
 555         WARN_ON(!mutex_is_locked(&component_mutex));
 556 
 557         master = __master_find(master_dev, NULL);
 558         if (!master)
 559                 return;
 560 
 561         /* Unbind components in reverse order */
 562         for (i = master->match->num; i--; )
 563                 if (!master->match->compare[i].duplicate) {
 564                         c = master->match->compare[i].component;
 565                         component_unbind(c, master, data);
 566                 }
 567 }
 568 EXPORT_SYMBOL_GPL(component_unbind_all);
 569 
 570 static int component_bind(struct component *component, struct master *master,
 571         void *data)
 572 {
 573         int ret;
 574 
 575         /*
 576          * Each component initialises inside its own devres group.
 577          * This allows us to roll-back a failed component without
 578          * affecting anything else.
 579          */
 580         if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
 581                 return -ENOMEM;
 582 
 583         /*
 584          * Also open a group for the device itself: this allows us
 585          * to release the resources claimed against the sub-device
 586          * at the appropriate moment.
 587          */
 588         if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
 589                 devres_release_group(master->dev, NULL);
 590                 return -ENOMEM;
 591         }
 592 
 593         dev_dbg(master->dev, "binding %s (ops %ps)\n",
 594                 dev_name(component->dev), component->ops);
 595 
 596         ret = component->ops->bind(component->dev, master->dev, data);
 597         if (!ret) {
 598                 component->bound = true;
 599 
 600                 /*
 601                  * Close the component device's group so that resources
 602                  * allocated in the binding are encapsulated for removal
 603                  * at unbind.  Remove the group on the DRM device as we
 604                  * can clean those resources up independently.
 605                  */
 606                 devres_close_group(component->dev, NULL);
 607                 devres_remove_group(master->dev, NULL);
 608 
 609                 dev_info(master->dev, "bound %s (ops %ps)\n",
 610                          dev_name(component->dev), component->ops);
 611         } else {
 612                 devres_release_group(component->dev, NULL);
 613                 devres_release_group(master->dev, NULL);
 614 
 615                 if (ret != -EPROBE_DEFER)
 616                         dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
 617                                 dev_name(component->dev), component->ops, ret);
 618         }
 619 
 620         return ret;
 621 }
 622 
 623 /**
 624  * component_bind_all - bind all components of an aggregate driver
 625  * @master_dev: device with the aggregate driver
 626  * @data: opaque pointer, passed to all components
 627  *
 628  * Binds all components of the aggregate @dev by passing @data to their
 629  * &component_ops.bind functions. Should be called from
 630  * &component_master_ops.bind.
 631  */
 632 int component_bind_all(struct device *master_dev, void *data)
 633 {
 634         struct master *master;
 635         struct component *c;
 636         size_t i;
 637         int ret = 0;
 638 
 639         WARN_ON(!mutex_is_locked(&component_mutex));
 640 
 641         master = __master_find(master_dev, NULL);
 642         if (!master)
 643                 return -EINVAL;
 644 
 645         /* Bind components in match order */
 646         for (i = 0; i < master->match->num; i++)
 647                 if (!master->match->compare[i].duplicate) {
 648                         c = master->match->compare[i].component;
 649                         ret = component_bind(c, master, data);
 650                         if (ret)
 651                                 break;
 652                 }
 653 
 654         if (ret != 0) {
 655                 for (; i > 0; i--)
 656                         if (!master->match->compare[i - 1].duplicate) {
 657                                 c = master->match->compare[i - 1].component;
 658                                 component_unbind(c, master, data);
 659                         }
 660         }
 661 
 662         return ret;
 663 }
 664 EXPORT_SYMBOL_GPL(component_bind_all);
 665 
 666 static int __component_add(struct device *dev, const struct component_ops *ops,
 667         int subcomponent)
 668 {
 669         struct component *component;
 670         int ret;
 671 
 672         component = kzalloc(sizeof(*component), GFP_KERNEL);
 673         if (!component)
 674                 return -ENOMEM;
 675 
 676         component->ops = ops;
 677         component->dev = dev;
 678         component->subcomponent = subcomponent;
 679 
 680         dev_dbg(dev, "adding component (ops %ps)\n", ops);
 681 
 682         mutex_lock(&component_mutex);
 683         list_add_tail(&component->node, &component_list);
 684 
 685         ret = try_to_bring_up_masters(component);
 686         if (ret < 0) {
 687                 if (component->master)
 688                         remove_component(component->master, component);
 689                 list_del(&component->node);
 690 
 691                 kfree(component);
 692         }
 693         mutex_unlock(&component_mutex);
 694 
 695         return ret < 0 ? ret : 0;
 696 }
 697 
 698 /**
 699  * component_add_typed - register a component
 700  * @dev: component device
 701  * @ops: component callbacks
 702  * @subcomponent: nonzero identifier for subcomponents
 703  *
 704  * Register a new component for @dev. Functions in @ops will be call when the
 705  * aggregate driver is ready to bind the overall driver by calling
 706  * component_bind_all(). See also &struct component_ops.
 707  *
 708  * @subcomponent must be nonzero and is used to differentiate between multiple
 709  * components registerd on the same device @dev. These components are match
 710  * using component_match_add_typed().
 711  *
 712  * The component needs to be unregistered at driver unload/disconnect by
 713  * calling component_del().
 714  *
 715  * See also component_add().
 716  */
 717 int component_add_typed(struct device *dev, const struct component_ops *ops,
 718         int subcomponent)
 719 {
 720         if (WARN_ON(subcomponent == 0))
 721                 return -EINVAL;
 722 
 723         return __component_add(dev, ops, subcomponent);
 724 }
 725 EXPORT_SYMBOL_GPL(component_add_typed);
 726 
 727 /**
 728  * component_add - register a component
 729  * @dev: component device
 730  * @ops: component callbacks
 731  *
 732  * Register a new component for @dev. Functions in @ops will be called when the
 733  * aggregate driver is ready to bind the overall driver by calling
 734  * component_bind_all(). See also &struct component_ops.
 735  *
 736  * The component needs to be unregistered at driver unload/disconnect by
 737  * calling component_del().
 738  *
 739  * See also component_add_typed() for a variant that allows multipled different
 740  * components on the same device.
 741  */
 742 int component_add(struct device *dev, const struct component_ops *ops)
 743 {
 744         return __component_add(dev, ops, 0);
 745 }
 746 EXPORT_SYMBOL_GPL(component_add);
 747 
 748 /**
 749  * component_del - unregister a component
 750  * @dev: component device
 751  * @ops: component callbacks
 752  *
 753  * Unregister a component added with component_add(). If the component is bound
 754  * into an aggregate driver, this will force the entire aggregate driver, including
 755  * all its components, to be unbound.
 756  */
 757 void component_del(struct device *dev, const struct component_ops *ops)
 758 {
 759         struct component *c, *component = NULL;
 760 
 761         mutex_lock(&component_mutex);
 762         list_for_each_entry(c, &component_list, node)
 763                 if (c->dev == dev && c->ops == ops) {
 764                         list_del(&c->node);
 765                         component = c;
 766                         break;
 767                 }
 768 
 769         if (component && component->master) {
 770                 take_down_master(component->master);
 771                 remove_component(component->master, component);
 772         }
 773 
 774         mutex_unlock(&component_mutex);
 775 
 776         WARN_ON(!component);
 777         kfree(component);
 778 }
 779 EXPORT_SYMBOL_GPL(component_del);
 780 
 781 MODULE_LICENSE("GPL v2");