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