drivers/base/component.c

   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 struct component;
  20
  21 struct component_match_array {
  22         void *data;
  23         int (*compare)(struct device *, void *);
  24         void (*release)(struct device *, void *);
  25         struct component *component;
  26         bool duplicate;
  27 };
  28
  29 struct component_match {
  30         size_t alloc;
  31         size_t num;
  32         struct component_match_array *compare;
  33 };
  34
  35 struct master {
  36         struct list_head node;
  37         bool bound;
  38
  39         const struct component_master_ops *ops;
  40         struct device *dev;
  41         struct component_match *match;
  42         struct dentry *dentry;
  43 };
  44
  45 struct component {
  46         struct list_head node;
  47         struct master *master;
  48         bool bound;
  49
  50         const struct component_ops *ops;
  51         struct device *dev;
  52 };
  53
  54 static DEFINE_MUTEX(component_mutex);
  55 static LIST_HEAD(component_list);
  56 static LIST_HEAD(masters);
  57
  58 #ifdef CONFIG_DEBUG_FS
  59
  60 static struct dentry *component_debugfs_dir;
  61
  62 static int component_devices_show(struct seq_file *s, void *data)
  63 {
  64         struct master *m = s->private;
  65         struct component_match *match = m->match;
  66         size_t i;
  67
  68         mutex_lock(&component_mutex);
  69         seq_printf(s, "%-40s %20s\n", "master name", "status");
  70         seq_puts(s, "-------------------------------------------------------------\n");
  71         seq_printf(s, "%-40s %20s\n\n",
  72                    dev_name(m->dev), m->bound ? "bound" : "not bound");
  73
  74         seq_printf(s, "%-40s %20s\n", "device name", "status");
  75         seq_puts(s, "-------------------------------------------------------------\n");
  76         for (i = 0; i < match->num; i++) {
  77                 struct device *d = (struct device *)match->compare[i].data;
  78
  79                 seq_printf(s, "%-40s %20s\n", dev_name(d),
  80                            match->compare[i].component ?
  81                            "registered" : "not registered");
  82         }
  83         mutex_unlock(&component_mutex);
  84
  85         return 0;
  86 }
  87
  88 static int component_devices_open(struct inode *inode, struct file *file)
  89 {
  90         return single_open(file, component_devices_show, inode->i_private);
  91 }
  92
  93 static const struct file_operations component_devices_fops = {
  94         .open = component_devices_open,
  95         .read = seq_read,
  96         .llseek = seq_lseek,
  97         .release = single_release,
  98 };
  99
 100 static int __init component_debug_init(void)
 101 {
 102         component_debugfs_dir = debugfs_create_dir("device_component", NULL);
 103
 104         return 0;
 105 }
 106
 107 core_initcall(component_debug_init);
 108
 109 static void component_master_debugfs_add(struct master *m)
 110 {
 111         m->dentry = debugfs_create_file(dev_name(m->dev), 0444,
 112                                         component_debugfs_dir,
 113                                         m, &component_devices_fops);
 114 }
 115
 116 static void component_master_debugfs_del(struct master *m)
 117 {
 118         debugfs_remove(m->dentry);
 119         m->dentry = NULL;
 120 }
 121
 122 #else
 123
 124 static void component_master_debugfs_add(struct master *m)
 125 { }
 126
 127 static void component_master_debugfs_del(struct master *m)
 128 { }
 129
 130 #endif
 131
 132 static struct master *__master_find(struct device *dev,
 133         const struct component_master_ops *ops)
 134 {
 135         struct master *m;
 136
 137         list_for_each_entry(m, &masters, node)
 138                 if (m->dev == dev && (!ops || m->ops == ops))
 139                         return m;
 140
 141         return NULL;
 142 }
 143
 144 static struct component *find_component(struct master *master,
 145         int (*compare)(struct device *, void *), void *compare_data)
 146 {
 147         struct component *c;
 148
 149         list_for_each_entry(c, &component_list, node) {
 150                 if (c->master && c->master != master)
 151                         continue;
 152
 153                 if (compare(c->dev, compare_data))
 154                         return c;
 155         }
 156
 157         return NULL;
 158 }
 159
 160 static int find_components(struct master *master)
 161 {
 162         struct component_match *match = master->match;
 163         size_t i;
 164         int ret = 0;
 165
 166         /*
 167          * Scan the array of match functions and attach
 168          * any components which are found to this master.
 169          */
 170         for (i = 0; i < match->num; i++) {
 171                 struct component_match_array *mc = &match->compare[i];
 172                 struct component *c;
 173
 174                 dev_dbg(master->dev, "Looking for component %zu\n", i);
 175
 176                 if (match->compare[i].component)
 177                         continue;
 178
 179                 c = find_component(master, mc->compare, mc->data);
 180                 if (!c) {
 181                         ret = -ENXIO;
 182                         break;
 183                 }
 184
 185                 dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master);
 186
 187                 /* Attach this component to the master */
 188                 match->compare[i].duplicate = !!c->master;
 189                 match->compare[i].component = c;
 190                 c->master = master;
 191         }
 192         return ret;
 193 }
 194
 195 /* Detach component from associated master */
 196 static void remove_component(struct master *master, struct component *c)
 197 {
 198         size_t i;
 199
 200         /* Detach the component from this master. */
 201         for (i = 0; i < master->match->num; i++)
 202                 if (master->match->compare[i].component == c)
 203                         master->match->compare[i].component = NULL;
 204 }
 205
 206 /*
 207  * Try to bring up a master.  If component is NULL, we're interested in
 208  * this master, otherwise it's a component which must be present to try
 209  * and bring up the master.
 210  *
 211  * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
 212  */
 213 static int try_to_bring_up_master(struct master *master,
 214         struct component *component)
 215 {
 216         int ret;
 217
 218         dev_dbg(master->dev, "trying to bring up master\n");
 219
 220         if (find_components(master)) {
 221                 dev_dbg(master->dev, "master has incomplete components\n");
 222                 return 0;
 223         }
 224
 225         if (component && component->master != master) {
 226                 dev_dbg(master->dev, "master is not for this component (%s)\n",
 227                         dev_name(component->dev));
 228                 return 0;
 229         }
 230
 231         if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
 232                 return -ENOMEM;
 233
 234         /* Found all components */
 235         ret = master->ops->bind(master->dev);
 236         if (ret < 0) {
 237                 devres_release_group(master->dev, NULL);
 238                 dev_info(master->dev, "master bind failed: %d\n", ret);
 239                 return ret;
 240         }
 241
 242         master->bound = true;
 243         return 1;
 244 }
 245
 246 static int try_to_bring_up_masters(struct component *component)
 247 {
 248         struct master *m;
 249         int ret = 0;
 250
 251         list_for_each_entry(m, &masters, node) {
 252                 if (!m->bound) {
 253                         ret = try_to_bring_up_master(m, component);
 254                         if (ret != 0)
 255                                 break;
 256                 }
 257         }
 258
 259         return ret;
 260 }
 261
 262 static void take_down_master(struct master *master)
 263 {
 264         if (master->bound) {
 265                 master->ops->unbind(master->dev);
 266                 devres_release_group(master->dev, NULL);
 267                 master->bound = false;
 268         }
 269 }
 270
 271 static void component_match_release(struct device *master,
 272         struct component_match *match)
 273 {
 274         unsigned int i;
 275
 276         for (i = 0; i < match->num; i++) {
 277                 struct component_match_array *mc = &match->compare[i];
 278
 279                 if (mc->release)
 280                         mc->release(master, mc->data);
 281         }
 282
 283         kfree(match->compare);
 284 }
 285
 286 static void devm_component_match_release(struct device *dev, void *res)
 287 {
 288         component_match_release(dev, res);
 289 }
 290
 291 static int component_match_realloc(struct device *dev,
 292         struct component_match *match, size_t num)
 293 {
 294         struct component_match_array *new;
 295
 296         if (match->alloc == num)
 297                 return 0;
 298
 299         new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);
 300         if (!new)
 301                 return -ENOMEM;
 302
 303         if (match->compare) {
 304                 memcpy(new, match->compare, sizeof(*new) *
 305                                             min(match->num, num));
 306                 kfree(match->compare);
 307         }
 308         match->compare = new;
 309         match->alloc = num;
 310
 311         return 0;
 312 }
 313
 314 /*
 315  * Add a component to be matched, with a release function.
 316  *
 317  * The match array is first created or extended if necessary.
 318  */
 319 void component_match_add_release(struct device *master,
 320         struct component_match **matchptr,
 321         void (*release)(struct device *, void *),
 322         int (*compare)(struct device *, void *), void *compare_data)
 323 {
 324         struct component_match *match = *matchptr;
 325
 326         if (IS_ERR(match))
 327                 return;
 328
 329         if (!match) {
 330                 match = devres_alloc(devm_component_match_release,
 331                                      sizeof(*match), GFP_KERNEL);
 332                 if (!match) {
 333                         *matchptr = ERR_PTR(-ENOMEM);
 334                         return;
 335                 }
 336
 337                 devres_add(master, match);
 338
 339                 *matchptr = match;
 340         }
 341
 342         if (match->num == match->alloc) {
 343                 size_t new_size = match->alloc + 16;
 344                 int ret;
 345
 346                 ret = component_match_realloc(master, match, new_size);
 347                 if (ret) {
 348                         *matchptr = ERR_PTR(ret);
 349                         return;
 350                 }
 351         }
 352
 353         match->compare[match->num].compare = compare;
 354         match->compare[match->num].release = release;
 355         match->compare[match->num].data = compare_data;
 356         match->compare[match->num].component = NULL;
 357         match->num++;
 358 }
 359 EXPORT_SYMBOL(component_match_add_release);
 360
 361 static void free_master(struct master *master)
 362 {
 363         struct component_match *match = master->match;
 364         int i;
 365
 366         component_master_debugfs_del(master);
 367         list_del(&master->node);
 368
 369         if (match) {
 370                 for (i = 0; i < match->num; i++) {
 371                         struct component *c = match->compare[i].component;
 372                         if (c)
 373                                 c->master = NULL;
 374                 }
 375         }
 376
 377         kfree(master);
 378 }
 379
 380 int component_master_add_with_match(struct device *dev,
 381         const struct component_master_ops *ops,
 382         struct component_match *match)
 383 {
 384         struct master *master;
 385         int ret;
 386
 387         /* Reallocate the match array for its true size */
 388         ret = component_match_realloc(dev, match, match->num);
 389         if (ret)
 390                 return ret;
 391
 392         master = kzalloc(sizeof(*master), GFP_KERNEL);
 393         if (!master)
 394                 return -ENOMEM;
 395
 396         master->dev = dev;
 397         master->ops = ops;
 398         master->match = match;
 399
 400         component_master_debugfs_add(master);
 401         /* Add to the list of available masters. */
 402         mutex_lock(&component_mutex);
 403         list_add(&master->node, &masters);
 404
 405         ret = try_to_bring_up_master(master, NULL);
 406
 407         if (ret < 0)
 408                 free_master(master);
 409
 410         mutex_unlock(&component_mutex);
 411
 412         return ret < 0 ? ret : 0;
 413 }
 414 EXPORT_SYMBOL_GPL(component_master_add_with_match);
 415
 416 void component_master_del(struct device *dev,
 417         const struct component_master_ops *ops)
 418 {
 419         struct master *master;
 420
 421         mutex_lock(&component_mutex);
 422         master = __master_find(dev, ops);
 423         if (master) {
 424                 take_down_master(master);
 425                 free_master(master);
 426         }
 427         mutex_unlock(&component_mutex);
 428 }
 429 EXPORT_SYMBOL_GPL(component_master_del);
 430
 431 static void component_unbind(struct component *component,
 432         struct master *master, void *data)
 433 {
 434         WARN_ON(!component->bound);
 435
 436         component->ops->unbind(component->dev, master->dev, data);
 437         component->bound = false;
 438
 439         /* Release all resources claimed in the binding of this component */
 440         devres_release_group(component->dev, component);
 441 }
 442
 443 void component_unbind_all(struct device *master_dev, void *data)
 444 {
 445         struct master *master;
 446         struct component *c;
 447         size_t i;
 448
 449         WARN_ON(!mutex_is_locked(&component_mutex));
 450
 451         master = __master_find(master_dev, NULL);
 452         if (!master)
 453                 return;
 454
 455         /* Unbind components in reverse order */
 456         for (i = master->match->num; i--; )
 457                 if (!master->match->compare[i].duplicate) {
 458                         c = master->match->compare[i].component;
 459                         component_unbind(c, master, data);
 460                 }
 461 }
 462 EXPORT_SYMBOL_GPL(component_unbind_all);
 463
 464 static int component_bind(struct component *component, struct master *master,
 465         void *data)
 466 {
 467         int ret;
 468
 469         /*
 470          * Each component initialises inside its own devres group.
 471          * This allows us to roll-back a failed component without
 472          * affecting anything else.
 473          */
 474         if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
 475                 return -ENOMEM;
 476
 477         /*
 478          * Also open a group for the device itself: this allows us
 479          * to release the resources claimed against the sub-device
 480          * at the appropriate moment.
 481          */
 482         if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
 483                 devres_release_group(master->dev, NULL);
 484                 return -ENOMEM;
 485         }
 486
 487         dev_dbg(master->dev, "binding %s (ops %ps)\n",
 488                 dev_name(component->dev), component->ops);
 489
 490         ret = component->ops->bind(component->dev, master->dev, data);
 491         if (!ret) {
 492                 component->bound = true;
 493
 494                 /*
 495                  * Close the component device's group so that resources
 496                  * allocated in the binding are encapsulated for removal
 497                  * at unbind.  Remove the group on the DRM device as we
 498                  * can clean those resources up independently.
 499                  */
 500                 devres_close_group(component->dev, NULL);
 501                 devres_remove_group(master->dev, NULL);
 502
 503                 dev_info(master->dev, "bound %s (ops %ps)\n",
 504                          dev_name(component->dev), component->ops);
 505         } else {
 506                 devres_release_group(component->dev, NULL);
 507                 devres_release_group(master->dev, NULL);
 508
 509                 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
 510                         dev_name(component->dev), component->ops, ret);
 511         }
 512
 513         return ret;
 514 }
 515
 516 int component_bind_all(struct device *master_dev, void *data)
 517 {
 518         struct master *master;
 519         struct component *c;
 520         size_t i;
 521         int ret = 0;
 522
 523         WARN_ON(!mutex_is_locked(&component_mutex));
 524
 525         master = __master_find(master_dev, NULL);
 526         if (!master)
 527                 return -EINVAL;
 528
 529         /* Bind components in match order */
 530         for (i = 0; i < master->match->num; i++)
 531                 if (!master->match->compare[i].duplicate) {
 532                         c = master->match->compare[i].component;
 533                         ret = component_bind(c, master, data);
 534                         if (ret)
 535                                 break;
 536                 }
 537
 538         if (ret != 0) {
 539                 for (; i--; )
 540                         if (!master->match->compare[i].duplicate) {
 541                                 c = master->match->compare[i].component;
 542                                 component_unbind(c, master, data);
 543                         }
 544         }
 545
 546         return ret;
 547 }
 548 EXPORT_SYMBOL_GPL(component_bind_all);
 549
 550 int component_add(struct device *dev, const struct component_ops *ops)
 551 {
 552         struct component *component;
 553         int ret;
 554
 555         component = kzalloc(sizeof(*component), GFP_KERNEL);
 556         if (!component)
 557                 return -ENOMEM;
 558
 559         component->ops = ops;
 560         component->dev = dev;
 561
 562         dev_dbg(dev, "adding component (ops %ps)\n", ops);
 563
 564         mutex_lock(&component_mutex);
 565         list_add_tail(&component->node, &component_list);
 566
 567         ret = try_to_bring_up_masters(component);
 568         if (ret < 0) {
 569                 if (component->master)
 570                         remove_component(component->master, component);
 571                 list_del(&component->node);
 572
 573                 kfree(component);
 574         }
 575         mutex_unlock(&component_mutex);
 576
 577         return ret < 0 ? ret : 0;
 578 }
 579 EXPORT_SYMBOL_GPL(component_add);
 580
 581 void component_del(struct device *dev, const struct component_ops *ops)
 582 {
 583         struct component *c, *component = NULL;
 584
 585         mutex_lock(&component_mutex);
 586         list_for_each_entry(c, &component_list, node)
 587                 if (c->dev == dev && c->ops == ops) {
 588                         list_del(&c->node);
 589                         component = c;
 590                         break;
 591                 }
 592
 593         if (component && component->master) {
 594                 take_down_master(component->master);
 595                 remove_component(component->master, component);
 596         }
 597
 598         mutex_unlock(&component_mutex);
 599
 600         WARN_ON(!component);
 601         kfree(component);
 602 }
 603 EXPORT_SYMBOL_GPL(component_del);
 604
 605 MODULE_LICENSE("GPL v2");