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                 dev_info(master->dev, "master bind failed: %d\n", ret);
 166                 return ret;
 167         }
 168
 169         master->bound = true;
 170         return 1;
 171 }
 172
 173 static int try_to_bring_up_masters(struct component *component)
 174 {
 175         struct master *m;
 176         int ret = 0;
 177
 178         list_for_each_entry(m, &masters, node) {
 179                 if (!m->bound) {
 180                         ret = try_to_bring_up_master(m, component);
 181                         if (ret != 0)
 182                                 break;
 183                 }
 184         }
 185
 186         return ret;
 187 }
 188
 189 static void take_down_master(struct master *master)
 190 {
 191         if (master->bound) {
 192                 master->ops->unbind(master->dev);
 193                 devres_release_group(master->dev, NULL);
 194                 master->bound = false;
 195         }
 196 }
 197
 198 static void component_match_release(struct device *master,
 199         struct component_match *match)
 200 {
 201         unsigned int i;
 202
 203         for (i = 0; i < match->num; i++) {
 204                 struct component_match_array *mc = &match->compare[i];
 205
 206                 if (mc->release)
 207                         mc->release(master, mc->data);
 208         }
 209
 210         kfree(match->compare);
 211 }
 212
 213 static void devm_component_match_release(struct device *dev, void *res)
 214 {
 215         component_match_release(dev, res);
 216 }
 217
 218 static int component_match_realloc(struct device *dev,
 219         struct component_match *match, size_t num)
 220 {
 221         struct component_match_array *new;
 222
 223         if (match->alloc == num)
 224                 return 0;
 225
 226         new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);
 227         if (!new)
 228                 return -ENOMEM;
 229
 230         if (match->compare) {
 231                 memcpy(new, match->compare, sizeof(*new) *
 232                                             min(match->num, num));
 233                 kfree(match->compare);
 234         }
 235         match->compare = new;
 236         match->alloc = num;
 237
 238         return 0;
 239 }
 240
 241 /*
 242  * Add a component to be matched, with a release function.
 243  *
 244  * The match array is first created or extended if necessary.
 245  */
 246 void component_match_add_release(struct device *master,
 247         struct component_match **matchptr,
 248         void (*release)(struct device *, void *),
 249         int (*compare)(struct device *, void *), void *compare_data)
 250 {
 251         struct component_match *match = *matchptr;
 252
 253         if (IS_ERR(match))
 254                 return;
 255
 256         if (!match) {
 257                 match = devres_alloc(devm_component_match_release,
 258                                      sizeof(*match), GFP_KERNEL);
 259                 if (!match) {
 260                         *matchptr = ERR_PTR(-ENOMEM);
 261                         return;
 262                 }
 263
 264                 devres_add(master, match);
 265
 266                 *matchptr = match;
 267         }
 268
 269         if (match->num == match->alloc) {
 270                 size_t new_size = match->alloc + 16;
 271                 int ret;
 272
 273                 ret = component_match_realloc(master, match, new_size);
 274                 if (ret) {
 275                         *matchptr = ERR_PTR(ret);
 276                         return;
 277                 }
 278         }
 279
 280         match->compare[match->num].compare = compare;
 281         match->compare[match->num].release = release;
 282         match->compare[match->num].data = compare_data;
 283         match->compare[match->num].component = NULL;
 284         match->num++;
 285 }
 286 EXPORT_SYMBOL(component_match_add_release);
 287
 288 static void free_master(struct master *master)
 289 {
 290         struct component_match *match = master->match;
 291         int i;
 292
 293         list_del(&master->node);
 294
 295         if (match) {
 296                 for (i = 0; i < match->num; i++) {
 297                         struct component *c = match->compare[i].component;
 298                         if (c)
 299                                 c->master = NULL;
 300                 }
 301         }
 302
 303         kfree(master);
 304 }
 305
 306 int component_master_add_with_match(struct device *dev,
 307         const struct component_master_ops *ops,
 308         struct component_match *match)
 309 {
 310         struct master *master;
 311         int ret;
 312
 313         /* Reallocate the match array for its true size */
 314         ret = component_match_realloc(dev, match, match->num);
 315         if (ret)
 316                 return ret;
 317
 318         master = kzalloc(sizeof(*master), GFP_KERNEL);
 319         if (!master)
 320                 return -ENOMEM;
 321
 322         master->dev = dev;
 323         master->ops = ops;
 324         master->match = match;
 325
 326         /* Add to the list of available masters. */
 327         mutex_lock(&component_mutex);
 328         list_add(&master->node, &masters);
 329
 330         ret = try_to_bring_up_master(master, NULL);
 331
 332         if (ret < 0)
 333                 free_master(master);
 334
 335         mutex_unlock(&component_mutex);
 336
 337         return ret < 0 ? ret : 0;
 338 }
 339 EXPORT_SYMBOL_GPL(component_master_add_with_match);
 340
 341 void component_master_del(struct device *dev,
 342         const struct component_master_ops *ops)
 343 {
 344         struct master *master;
 345
 346         mutex_lock(&component_mutex);
 347         master = __master_find(dev, ops);
 348         if (master) {
 349                 take_down_master(master);
 350                 free_master(master);
 351         }
 352         mutex_unlock(&component_mutex);
 353 }
 354 EXPORT_SYMBOL_GPL(component_master_del);
 355
 356 static void component_unbind(struct component *component,
 357         struct master *master, void *data)
 358 {
 359         WARN_ON(!component->bound);
 360
 361         component->ops->unbind(component->dev, master->dev, data);
 362         component->bound = false;
 363
 364         /* Release all resources claimed in the binding of this component */
 365         devres_release_group(component->dev, component);
 366 }
 367
 368 void component_unbind_all(struct device *master_dev, void *data)
 369 {
 370         struct master *master;
 371         struct component *c;
 372         size_t i;
 373
 374         WARN_ON(!mutex_is_locked(&component_mutex));
 375
 376         master = __master_find(master_dev, NULL);
 377         if (!master)
 378                 return;
 379
 380         /* Unbind components in reverse order */
 381         for (i = master->match->num; i--; )
 382                 if (!master->match->compare[i].duplicate) {
 383                         c = master->match->compare[i].component;
 384                         component_unbind(c, master, data);
 385                 }
 386 }
 387 EXPORT_SYMBOL_GPL(component_unbind_all);
 388
 389 static int component_bind(struct component *component, struct master *master,
 390         void *data)
 391 {
 392         int ret;
 393
 394         /*
 395          * Each component initialises inside its own devres group.
 396          * This allows us to roll-back a failed component without
 397          * affecting anything else.
 398          */
 399         if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
 400                 return -ENOMEM;
 401
 402         /*
 403          * Also open a group for the device itself: this allows us
 404          * to release the resources claimed against the sub-device
 405          * at the appropriate moment.
 406          */
 407         if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
 408                 devres_release_group(master->dev, NULL);
 409                 return -ENOMEM;
 410         }
 411
 412         dev_dbg(master->dev, "binding %s (ops %ps)\n",
 413                 dev_name(component->dev), component->ops);
 414
 415         ret = component->ops->bind(component->dev, master->dev, data);
 416         if (!ret) {
 417                 component->bound = true;
 418
 419                 /*
 420                  * Close the component device's group so that resources
 421                  * allocated in the binding are encapsulated for removal
 422                  * at unbind.  Remove the group on the DRM device as we
 423                  * can clean those resources up independently.
 424                  */
 425                 devres_close_group(component->dev, NULL);
 426                 devres_remove_group(master->dev, NULL);
 427
 428                 dev_info(master->dev, "bound %s (ops %ps)\n",
 429                          dev_name(component->dev), component->ops);
 430         } else {
 431                 devres_release_group(component->dev, NULL);
 432                 devres_release_group(master->dev, NULL);
 433
 434                 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
 435                         dev_name(component->dev), component->ops, ret);
 436         }
 437
 438         return ret;
 439 }
 440
 441 int component_bind_all(struct device *master_dev, void *data)
 442 {
 443         struct master *master;
 444         struct component *c;
 445         size_t i;
 446         int ret = 0;
 447
 448         WARN_ON(!mutex_is_locked(&component_mutex));
 449
 450         master = __master_find(master_dev, NULL);
 451         if (!master)
 452                 return -EINVAL;
 453
 454         /* Bind components in match order */
 455         for (i = 0; i < master->match->num; i++)
 456                 if (!master->match->compare[i].duplicate) {
 457                         c = master->match->compare[i].component;
 458                         ret = component_bind(c, master, data);
 459                         if (ret)
 460                                 break;
 461                 }
 462
 463         if (ret != 0) {
 464                 for (; i--; )
 465                         if (!master->match->compare[i].duplicate) {
 466                                 c = master->match->compare[i].component;
 467                                 component_unbind(c, master, data);
 468                         }
 469         }
 470
 471         return ret;
 472 }
 473 EXPORT_SYMBOL_GPL(component_bind_all);
 474
 475 int component_add(struct device *dev, const struct component_ops *ops)
 476 {
 477         struct component *component;
 478         int ret;
 479
 480         component = kzalloc(sizeof(*component), GFP_KERNEL);
 481         if (!component)
 482                 return -ENOMEM;
 483
 484         component->ops = ops;
 485         component->dev = dev;
 486
 487         dev_dbg(dev, "adding component (ops %ps)\n", ops);
 488
 489         mutex_lock(&component_mutex);
 490         list_add_tail(&component->node, &component_list);
 491
 492         ret = try_to_bring_up_masters(component);
 493         if (ret < 0) {
 494                 if (component->master)
 495                         remove_component(component->master, component);
 496                 list_del(&component->node);
 497
 498                 kfree(component);
 499         }
 500         mutex_unlock(&component_mutex);
 501
 502         return ret < 0 ? ret : 0;
 503 }
 504 EXPORT_SYMBOL_GPL(component_add);
 505
 506 void component_del(struct device *dev, const struct component_ops *ops)
 507 {
 508         struct component *c, *component = NULL;
 509
 510         mutex_lock(&component_mutex);
 511         list_for_each_entry(c, &component_list, node)
 512                 if (c->dev == dev && c->ops == ops) {
 513                         list_del(&c->node);
 514                         component = c;
 515                         break;
 516                 }
 517
 518         if (component && component->master) {
 519                 take_down_master(component->master);
 520                 remove_component(component->master, component);
 521         }
 522
 523         mutex_unlock(&component_mutex);
 524
 525         WARN_ON(!component);
 526         kfree(component);
 527 }
 528 EXPORT_SYMBOL_GPL(component_del);
 529
 530 MODULE_LICENSE("GPL v2");