drivers/base/component.c

   1 /*
   2  * Componentized device handling.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This is work in progress.  We gather up the component devices into a list,
   9  * and bind them when instructed.  At the moment, we're specific to the DRM
  10  * subsystem, and only handles one master device, but this doesn't have to be
  11  * the case.
  12  */
  13 #include <linux/component.h>
  14 #include <linux/device.h>
  15 #include <linux/kref.h>
  16 #include <linux/list.h>
  17 #include <linux/module.h>
  18 #include <linux/mutex.h>
  19 #include <linux/slab.h>
  20
  21 struct component_match {
  22         size_t alloc;
  23         size_t num;
  24         struct {
  25                 void *data;
  26                 int (*fn)(struct device *, void *);
  27         } compare[0];
  28 };
  29
  30 struct master {
  31         struct list_head node;
  32         struct list_head components;
  33         bool bound;
  34
  35         const struct component_master_ops *ops;
  36         struct device *dev;
  37         struct component_match *match;
  38 };
  39
  40 struct component {
  41         struct list_head node;
  42         struct list_head master_node;
  43         struct master *master;
  44         bool bound;
  45
  46         const struct component_ops *ops;
  47         struct device *dev;
  48 };
  49
  50 static DEFINE_MUTEX(component_mutex);
  51 static LIST_HEAD(component_list);
  52 static LIST_HEAD(masters);
  53
  54 static struct master *__master_find(struct device *dev,
  55         const struct component_master_ops *ops)
  56 {
  57         struct master *m;
  58
  59         list_for_each_entry(m, &masters, node)
  60                 if (m->dev == dev && (!ops || m->ops == ops))
  61                         return m;
  62
  63         return NULL;
  64 }
  65
  66 /* Attach an unattached component to a master. */
  67 static void component_attach_master(struct master *master, struct component *c)
  68 {
  69         c->master = master;
  70
  71         list_add_tail(&c->master_node, &master->components);
  72 }
  73
  74 /* Detach a component from a master. */
  75 static void component_detach_master(struct master *master, struct component *c)
  76 {
  77         list_del(&c->master_node);
  78
  79         c->master = NULL;
  80 }
  81
  82 /*
  83  * Add a component to a master, finding the component via the compare
  84  * function and compare data.  This is safe to call for duplicate matches
  85  * and will not result in the same component being added multiple times.
  86  */
  87 static int component_master_add_child(struct master *master,
  88         int (*compare)(struct device *, void *), void *compare_data)
  89 {
  90         struct component *c;
  91         int ret = -ENXIO;
  92
  93         list_for_each_entry(c, &component_list, node) {
  94                 if (c->master && c->master != master)
  95                         continue;
  96
  97                 if (compare(c->dev, compare_data)) {
  98                         if (!c->master)
  99                                 component_attach_master(master, c);
 100                         ret = 0;
 101                         break;
 102                 }
 103         }
 104
 105         return ret;
 106 }
 107
 108 static int find_components(struct master *master)
 109 {
 110         struct component_match *match = master->match;
 111         size_t i;
 112         int ret = 0;
 113
 114         /*
 115          * Scan the array of match functions and attach
 116          * any components which are found to this master.
 117          */
 118         for (i = 0; i < match->num; i++) {
 119                 ret = component_master_add_child(master,
 120                                                  match->compare[i].fn,
 121                                                  match->compare[i].data);
 122                 if (ret)
 123                         break;
 124         }
 125         return ret;
 126 }
 127
 128 /* Detach all attached components from this master */
 129 static void master_remove_components(struct master *master)
 130 {
 131         while (!list_empty(&master->components)) {
 132                 struct component *c = list_first_entry(&master->components,
 133                                         struct component, master_node);
 134
 135                 WARN_ON(c->master != master);
 136
 137                 component_detach_master(master, c);
 138         }
 139 }
 140
 141 /*
 142  * Try to bring up a master.  If component is NULL, we're interested in
 143  * this master, otherwise it's a component which must be present to try
 144  * and bring up the master.
 145  *
 146  * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
 147  */
 148 static int try_to_bring_up_master(struct master *master,
 149         struct component *component)
 150 {
 151         int ret;
 152
 153         if (master->bound)
 154                 return 0;
 155
 156         /*
 157          * Search the list of components, looking for components that
 158          * belong to this master, and attach them to the master.
 159          */
 160         if (find_components(master)) {
 161                 /* Failed to find all components */
 162                 ret = 0;
 163                 goto out;
 164         }
 165
 166         if (component && component->master != master) {
 167                 ret = 0;
 168                 goto out;
 169         }
 170
 171         if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) {
 172                 ret = -ENOMEM;
 173                 goto out;
 174         }
 175
 176         /* Found all components */
 177         ret = master->ops->bind(master->dev);
 178         if (ret < 0) {
 179                 devres_release_group(master->dev, NULL);
 180                 dev_info(master->dev, "master bind failed: %d\n", ret);
 181                 goto out;
 182         }
 183
 184         master->bound = true;
 185         return 1;
 186
 187 out:
 188         master_remove_components(master);
 189
 190         return ret;
 191 }
 192
 193 static int try_to_bring_up_masters(struct component *component)
 194 {
 195         struct master *m;
 196         int ret = 0;
 197
 198         list_for_each_entry(m, &masters, node) {
 199                 ret = try_to_bring_up_master(m, component);
 200                 if (ret != 0)
 201                         break;
 202         }
 203
 204         return ret;
 205 }
 206
 207 static void take_down_master(struct master *master)
 208 {
 209         if (master->bound) {
 210                 master->ops->unbind(master->dev);
 211                 devres_release_group(master->dev, NULL);
 212                 master->bound = false;
 213         }
 214
 215         master_remove_components(master);
 216 }
 217
 218 static size_t component_match_size(size_t num)
 219 {
 220         return offsetof(struct component_match, compare[num]);
 221 }
 222
 223 static struct component_match *component_match_realloc(struct device *dev,
 224         struct component_match *match, size_t num)
 225 {
 226         struct component_match *new;
 227
 228         if (match && match->alloc == num)
 229                 return match;
 230
 231         new = devm_kmalloc(dev, component_match_size(num), GFP_KERNEL);
 232         if (!new)
 233                 return ERR_PTR(-ENOMEM);
 234
 235         if (match) {
 236                 memcpy(new, match, component_match_size(min(match->num, num)));
 237                 devm_kfree(dev, match);
 238         } else {
 239                 new->num = 0;
 240         }
 241
 242         new->alloc = num;
 243
 244         return new;
 245 }
 246
 247 /*
 248  * Add a component to be matched.
 249  *
 250  * The match array is first created or extended if necessary.
 251  */
 252 void component_match_add(struct device *dev, struct component_match **matchptr,
 253         int (*compare)(struct device *, void *), void *compare_data)
 254 {
 255         struct component_match *match = *matchptr;
 256
 257         if (IS_ERR(match))
 258                 return;
 259
 260         if (!match || match->num == match->alloc) {
 261                 size_t new_size = match ? match->alloc + 16 : 15;
 262
 263                 match = component_match_realloc(dev, match, new_size);
 264
 265                 *matchptr = match;
 266
 267                 if (IS_ERR(match))
 268                         return;
 269         }
 270
 271         match->compare[match->num].fn = compare;
 272         match->compare[match->num].data = compare_data;
 273         match->num++;
 274 }
 275 EXPORT_SYMBOL(component_match_add);
 276
 277 int component_master_add_with_match(struct device *dev,
 278         const struct component_master_ops *ops,
 279         struct component_match *match)
 280 {
 281         struct master *master;
 282         int ret;
 283
 284         /* Reallocate the match array for its true size */
 285         match = component_match_realloc(dev, match, match->num);
 286         if (IS_ERR(match))
 287                 return PTR_ERR(match);
 288
 289         master = kzalloc(sizeof(*master), GFP_KERNEL);
 290         if (!master)
 291                 return -ENOMEM;
 292
 293         master->dev = dev;
 294         master->ops = ops;
 295         master->match = match;
 296         INIT_LIST_HEAD(&master->components);
 297
 298         /* Add to the list of available masters. */
 299         mutex_lock(&component_mutex);
 300         list_add(&master->node, &masters);
 301
 302         ret = try_to_bring_up_master(master, NULL);
 303
 304         if (ret < 0) {
 305                 /* Delete off the list if we weren't successful */
 306                 list_del(&master->node);
 307                 kfree(master);
 308         }
 309         mutex_unlock(&component_mutex);
 310
 311         return ret < 0 ? ret : 0;
 312 }
 313 EXPORT_SYMBOL_GPL(component_master_add_with_match);
 314
 315 void component_master_del(struct device *dev,
 316         const struct component_master_ops *ops)
 317 {
 318         struct master *master;
 319
 320         mutex_lock(&component_mutex);
 321         master = __master_find(dev, ops);
 322         if (master) {
 323                 take_down_master(master);
 324
 325                 list_del(&master->node);
 326                 kfree(master);
 327         }
 328         mutex_unlock(&component_mutex);
 329 }
 330 EXPORT_SYMBOL_GPL(component_master_del);
 331
 332 static void component_unbind(struct component *component,
 333         struct master *master, void *data)
 334 {
 335         WARN_ON(!component->bound);
 336
 337         component->ops->unbind(component->dev, master->dev, data);
 338         component->bound = false;
 339
 340         /* Release all resources claimed in the binding of this component */
 341         devres_release_group(component->dev, component);
 342 }
 343
 344 void component_unbind_all(struct device *master_dev, void *data)
 345 {
 346         struct master *master;
 347         struct component *c;
 348
 349         WARN_ON(!mutex_is_locked(&component_mutex));
 350
 351         master = __master_find(master_dev, NULL);
 352         if (!master)
 353                 return;
 354
 355         list_for_each_entry_reverse(c, &master->components, master_node)
 356                 component_unbind(c, master, data);
 357 }
 358 EXPORT_SYMBOL_GPL(component_unbind_all);
 359
 360 static int component_bind(struct component *component, struct master *master,
 361         void *data)
 362 {
 363         int ret;
 364
 365         /*
 366          * Each component initialises inside its own devres group.
 367          * This allows us to roll-back a failed component without
 368          * affecting anything else.
 369          */
 370         if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
 371                 return -ENOMEM;
 372
 373         /*
 374          * Also open a group for the device itself: this allows us
 375          * to release the resources claimed against the sub-device
 376          * at the appropriate moment.
 377          */
 378         if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
 379                 devres_release_group(master->dev, NULL);
 380                 return -ENOMEM;
 381         }
 382
 383         dev_dbg(master->dev, "binding %s (ops %ps)\n",
 384                 dev_name(component->dev), component->ops);
 385
 386         ret = component->ops->bind(component->dev, master->dev, data);
 387         if (!ret) {
 388                 component->bound = true;
 389
 390                 /*
 391                  * Close the component device's group so that resources
 392                  * allocated in the binding are encapsulated for removal
 393                  * at unbind.  Remove the group on the DRM device as we
 394                  * can clean those resources up independently.
 395                  */
 396                 devres_close_group(component->dev, NULL);
 397                 devres_remove_group(master->dev, NULL);
 398
 399                 dev_info(master->dev, "bound %s (ops %ps)\n",
 400                          dev_name(component->dev), component->ops);
 401         } else {
 402                 devres_release_group(component->dev, NULL);
 403                 devres_release_group(master->dev, NULL);
 404
 405                 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
 406                         dev_name(component->dev), component->ops, ret);
 407         }
 408
 409         return ret;
 410 }
 411
 412 int component_bind_all(struct device *master_dev, void *data)
 413 {
 414         struct master *master;
 415         struct component *c;
 416         int ret = 0;
 417
 418         WARN_ON(!mutex_is_locked(&component_mutex));
 419
 420         master = __master_find(master_dev, NULL);
 421         if (!master)
 422                 return -EINVAL;
 423
 424         list_for_each_entry(c, &master->components, master_node) {
 425                 ret = component_bind(c, master, data);
 426                 if (ret)
 427                         break;
 428         }
 429
 430         if (ret != 0) {
 431                 list_for_each_entry_continue_reverse(c, &master->components,
 432                                                      master_node)
 433                         component_unbind(c, master, data);
 434         }
 435
 436         return ret;
 437 }
 438 EXPORT_SYMBOL_GPL(component_bind_all);
 439
 440 int component_add(struct device *dev, const struct component_ops *ops)
 441 {
 442         struct component *component;
 443         int ret;
 444
 445         component = kzalloc(sizeof(*component), GFP_KERNEL);
 446         if (!component)
 447                 return -ENOMEM;
 448
 449         component->ops = ops;
 450         component->dev = dev;
 451
 452         dev_dbg(dev, "adding component (ops %ps)\n", ops);
 453
 454         mutex_lock(&component_mutex);
 455         list_add_tail(&component->node, &component_list);
 456
 457         ret = try_to_bring_up_masters(component);
 458         if (ret < 0) {
 459                 list_del(&component->node);
 460
 461                 kfree(component);
 462         }
 463         mutex_unlock(&component_mutex);
 464
 465         return ret < 0 ? ret : 0;
 466 }
 467 EXPORT_SYMBOL_GPL(component_add);
 468
 469 void component_del(struct device *dev, const struct component_ops *ops)
 470 {
 471         struct component *c, *component = NULL;
 472
 473         mutex_lock(&component_mutex);
 474         list_for_each_entry(c, &component_list, node)
 475                 if (c->dev == dev && c->ops == ops) {
 476                         list_del(&c->node);
 477                         component = c;
 478                         break;
 479                 }
 480
 481         if (component && component->master)
 482                 take_down_master(component->master);
 483
 484         mutex_unlock(&component_mutex);
 485
 486         WARN_ON(!component);
 487         kfree(component);
 488 }
 489 EXPORT_SYMBOL_GPL(component_del);
 490
 491 MODULE_LICENSE("GPL v2");