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
 211 static void devm_component_match_release(struct device *dev, void *res)
 212 {
 213         component_match_release(dev, res);
 214 }
 215
 216 static int component_match_realloc(struct device *dev,
 217         struct component_match *match, size_t num)
 218 {
 219         struct component_match_array *new;
 220
 221         if (match->alloc == num)
 222                 return 0;
 223
 224         new = devm_kmalloc_array(dev, num, sizeof(*new), GFP_KERNEL);
 225         if (!new)
 226                 return -ENOMEM;
 227
 228         if (match->compare) {
 229                 memcpy(new, match->compare, sizeof(*new) *
 230                                             min(match->num, num));
 231                 devm_kfree(dev, match->compare);
 232         }
 233         match->compare = new;
 234         match->alloc = num;
 235
 236         return 0;
 237 }
 238
 239 /*
 240  * Add a component to be matched, with a release function.
 241  *
 242  * The match array is first created or extended if necessary.
 243  */
 244 void component_match_add_release(struct device *master,
 245         struct component_match **matchptr,
 246         void (*release)(struct device *, void *),
 247         int (*compare)(struct device *, void *), void *compare_data)
 248 {
 249         struct component_match *match = *matchptr;
 250
 251         if (IS_ERR(match))
 252                 return;
 253
 254         if (!match) {
 255                 match = devres_alloc(devm_component_match_release,
 256                                      sizeof(*match), GFP_KERNEL);
 257                 if (!match) {
 258                         *matchptr = ERR_PTR(-ENOMEM);
 259                         return;
 260                 }
 261
 262                 devres_add(master, match);
 263
 264                 *matchptr = match;
 265         }
 266
 267         if (match->num == match->alloc) {
 268                 size_t new_size = match ? match->alloc + 16 : 15;
 269                 int ret;
 270
 271                 ret = component_match_realloc(master, match, new_size);
 272                 if (ret) {
 273                         *matchptr = ERR_PTR(ret);
 274                         return;
 275                 }
 276         }
 277
 278         match->compare[match->num].compare = compare;
 279         match->compare[match->num].release = release;
 280         match->compare[match->num].data = compare_data;
 281         match->compare[match->num].component = NULL;
 282         match->num++;
 283 }
 284 EXPORT_SYMBOL(component_match_add_release);
 285
 286 int component_master_add_with_match(struct device *dev,
 287         const struct component_master_ops *ops,
 288         struct component_match *match)
 289 {
 290         struct master *master;
 291         int ret;
 292
 293         /* Reallocate the match array for its true size */
 294         ret = component_match_realloc(dev, match, match->num);
 295         if (ret)
 296                 return ret;
 297
 298         master = kzalloc(sizeof(*master), GFP_KERNEL);
 299         if (!master)
 300                 return -ENOMEM;
 301
 302         master->dev = dev;
 303         master->ops = ops;
 304         master->match = match;
 305
 306         /* Add to the list of available masters. */
 307         mutex_lock(&component_mutex);
 308         list_add(&master->node, &masters);
 309
 310         ret = try_to_bring_up_master(master, NULL);
 311
 312         if (ret < 0) {
 313                 /* Delete off the list if we weren't successful */
 314                 list_del(&master->node);
 315                 kfree(master);
 316         }
 317         mutex_unlock(&component_mutex);
 318
 319         return ret < 0 ? ret : 0;
 320 }
 321 EXPORT_SYMBOL_GPL(component_master_add_with_match);
 322
 323 void component_master_del(struct device *dev,
 324         const struct component_master_ops *ops)
 325 {
 326         struct master *master;
 327         int i;
 328
 329         mutex_lock(&component_mutex);
 330         master = __master_find(dev, ops);
 331         if (master) {
 332                 struct component_match *match = master->match;
 333
 334                 take_down_master(master);
 335
 336                 list_del(&master->node);
 337
 338                 if (match) {
 339                         for (i = 0; i < match->num; i++) {
 340                                 struct component *c = match->compare[i].component;
 341                                 if (c)
 342                                         c->master = NULL;
 343                         }
 344                 }
 345                 kfree(master);
 346         }
 347         mutex_unlock(&component_mutex);
 348 }
 349 EXPORT_SYMBOL_GPL(component_master_del);
 350
 351 static void component_unbind(struct component *component,
 352         struct master *master, void *data)
 353 {
 354         WARN_ON(!component->bound);
 355
 356         component->ops->unbind(component->dev, master->dev, data);
 357         component->bound = false;
 358
 359         /* Release all resources claimed in the binding of this component */
 360         devres_release_group(component->dev, component);
 361 }
 362
 363 void component_unbind_all(struct device *master_dev, void *data)
 364 {
 365         struct master *master;
 366         struct component *c;
 367         size_t i;
 368
 369         WARN_ON(!mutex_is_locked(&component_mutex));
 370
 371         master = __master_find(master_dev, NULL);
 372         if (!master)
 373                 return;
 374
 375         /* Unbind components in reverse order */
 376         for (i = master->match->num; i--; )
 377                 if (!master->match->compare[i].duplicate) {
 378                         c = master->match->compare[i].component;
 379                         component_unbind(c, master, data);
 380                 }
 381 }
 382 EXPORT_SYMBOL_GPL(component_unbind_all);
 383
 384 static int component_bind(struct component *component, struct master *master,
 385         void *data)
 386 {
 387         int ret;
 388
 389         /*
 390          * Each component initialises inside its own devres group.
 391          * This allows us to roll-back a failed component without
 392          * affecting anything else.
 393          */
 394         if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
 395                 return -ENOMEM;
 396
 397         /*
 398          * Also open a group for the device itself: this allows us
 399          * to release the resources claimed against the sub-device
 400          * at the appropriate moment.
 401          */
 402         if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
 403                 devres_release_group(master->dev, NULL);
 404                 return -ENOMEM;
 405         }
 406
 407         dev_dbg(master->dev, "binding %s (ops %ps)\n",
 408                 dev_name(component->dev), component->ops);
 409
 410         ret = component->ops->bind(component->dev, master->dev, data);
 411         if (!ret) {
 412                 component->bound = true;
 413
 414                 /*
 415                  * Close the component device's group so that resources
 416                  * allocated in the binding are encapsulated for removal
 417                  * at unbind.  Remove the group on the DRM device as we
 418                  * can clean those resources up independently.
 419                  */
 420                 devres_close_group(component->dev, NULL);
 421                 devres_remove_group(master->dev, NULL);
 422
 423                 dev_info(master->dev, "bound %s (ops %ps)\n",
 424                          dev_name(component->dev), component->ops);
 425         } else {
 426                 devres_release_group(component->dev, NULL);
 427                 devres_release_group(master->dev, NULL);
 428
 429                 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
 430                         dev_name(component->dev), component->ops, ret);
 431         }
 432
 433         return ret;
 434 }
 435
 436 int component_bind_all(struct device *master_dev, void *data)
 437 {
 438         struct master *master;
 439         struct component *c;
 440         size_t i;
 441         int ret = 0;
 442
 443         WARN_ON(!mutex_is_locked(&component_mutex));
 444
 445         master = __master_find(master_dev, NULL);
 446         if (!master)
 447                 return -EINVAL;
 448
 449         /* Bind components in match order */
 450         for (i = 0; i < master->match->num; i++)
 451                 if (!master->match->compare[i].duplicate) {
 452                         c = master->match->compare[i].component;
 453                         ret = component_bind(c, master, data);
 454                         if (ret)
 455                                 break;
 456                 }
 457
 458         if (ret != 0) {
 459                 for (; i--; )
 460                         if (!master->match->compare[i].duplicate) {
 461                                 c = master->match->compare[i].component;
 462                                 component_unbind(c, master, data);
 463                         }
 464         }
 465
 466         return ret;
 467 }
 468 EXPORT_SYMBOL_GPL(component_bind_all);
 469
 470 int component_add(struct device *dev, const struct component_ops *ops)
 471 {
 472         struct component *component;
 473         int ret;
 474
 475         component = kzalloc(sizeof(*component), GFP_KERNEL);
 476         if (!component)
 477                 return -ENOMEM;
 478
 479         component->ops = ops;
 480         component->dev = dev;
 481
 482         dev_dbg(dev, "adding component (ops %ps)\n", ops);
 483
 484         mutex_lock(&component_mutex);
 485         list_add_tail(&component->node, &component_list);
 486
 487         ret = try_to_bring_up_masters(component);
 488         if (ret < 0) {
 489                 list_del(&component->node);
 490
 491                 kfree(component);
 492         }
 493         mutex_unlock(&component_mutex);
 494
 495         return ret < 0 ? ret : 0;
 496 }
 497 EXPORT_SYMBOL_GPL(component_add);
 498
 499 void component_del(struct device *dev, const struct component_ops *ops)
 500 {
 501         struct component *c, *component = NULL;
 502
 503         mutex_lock(&component_mutex);
 504         list_for_each_entry(c, &component_list, node)
 505                 if (c->dev == dev && c->ops == ops) {
 506                         list_del(&c->node);
 507                         component = c;
 508                         break;
 509                 }
 510
 511         if (component && component->master) {
 512                 take_down_master(component->master);
 513                 remove_component(component->master, component);
 514         }
 515
 516         mutex_unlock(&component_mutex);
 517
 518         WARN_ON(!component);
 519         kfree(component);
 520 }
 521 EXPORT_SYMBOL_GPL(component_del);
 522
 523 MODULE_LICENSE("GPL v2");