drivers/of/dynamic.c

   1 /*
   2  * Support for dynamic device trees.
   3  *
   4  * On some platforms, the device tree can be manipulated at runtime.
   5  * The routines in this section support adding, removing and changing
   6  * device tree nodes.
   7  */
   8
   9 #include <linux/of.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/slab.h>
  12 #include <linux/string.h>
  13 #include <linux/proc_fs.h>
  14
  15 #include "of_private.h"
  16
  17 /**
  18  * of_node_get() - Increment refcount of a node
  19  * @node:       Node to inc refcount, NULL is supported to simplify writing of
  20  *              callers
  21  *
  22  * Returns node.
  23  */
  24 struct device_node *of_node_get(struct device_node *node)
  25 {
  26         if (node)
  27                 kobject_get(&node->kobj);
  28         return node;
  29 }
  30 EXPORT_SYMBOL(of_node_get);
  31
  32 /**
  33  * of_node_put() - Decrement refcount of a node
  34  * @node:       Node to dec refcount, NULL is supported to simplify writing of
  35  *              callers
  36  */
  37 void of_node_put(struct device_node *node)
  38 {
  39         if (node)
  40                 kobject_put(&node->kobj);
  41 }
  42 EXPORT_SYMBOL(of_node_put);
  43
  44 void __of_detach_node_sysfs(struct device_node *np)
  45 {
  46         struct property *pp;
  47
  48         BUG_ON(!of_node_is_initialized(np));
  49         if (!of_kset)
  50                 return;
  51
  52         /* only remove properties if on sysfs */
  53         if (of_node_is_attached(np)) {
  54                 for_each_property_of_node(np, pp)
  55                         sysfs_remove_bin_file(&np->kobj, &pp->attr);
  56                 kobject_del(&np->kobj);
  57         }
  58
  59         /* finally remove the kobj_init ref */
  60         of_node_put(np);
  61 }
  62
  63 static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain);
  64
  65 int of_reconfig_notifier_register(struct notifier_block *nb)
  66 {
  67         return blocking_notifier_chain_register(&of_reconfig_chain, nb);
  68 }
  69 EXPORT_SYMBOL_GPL(of_reconfig_notifier_register);
  70
  71 int of_reconfig_notifier_unregister(struct notifier_block *nb)
  72 {
  73         return blocking_notifier_chain_unregister(&of_reconfig_chain, nb);
  74 }
  75 EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister);
  76
  77 #ifdef DEBUG
  78 const char *action_names[] = {
  79         [OF_RECONFIG_ATTACH_NODE] = "ATTACH_NODE",
  80         [OF_RECONFIG_DETACH_NODE] = "DETACH_NODE",
  81         [OF_RECONFIG_ADD_PROPERTY] = "ADD_PROPERTY",
  82         [OF_RECONFIG_REMOVE_PROPERTY] = "REMOVE_PROPERTY",
  83         [OF_RECONFIG_UPDATE_PROPERTY] = "UPDATE_PROPERTY",
  84 };
  85 #endif
  86
  87 int of_reconfig_notify(unsigned long action, struct of_reconfig_data *p)
  88 {
  89         int rc;
  90 #ifdef DEBUG
  91         struct of_reconfig_data *pr = p;
  92
  93         switch (action) {
  94         case OF_RECONFIG_ATTACH_NODE:
  95         case OF_RECONFIG_DETACH_NODE:
  96                 pr_debug("of/notify %-15s %s\n", action_names[action],
  97                         pr->dn->full_name);
  98                 break;
  99         case OF_RECONFIG_ADD_PROPERTY:
 100         case OF_RECONFIG_REMOVE_PROPERTY:
 101         case OF_RECONFIG_UPDATE_PROPERTY:
 102                 pr_debug("of/notify %-15s %s:%s\n", action_names[action],
 103                         pr->dn->full_name, pr->prop->name);
 104                 break;
 105
 106         }
 107 #endif
 108         rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p);
 109         return notifier_to_errno(rc);
 110 }
 111
 112 /*
 113  * of_reconfig_get_state_change()       - Returns new state of device
 114  * @action      - action of the of notifier
 115  * @arg         - argument of the of notifier
 116  *
 117  * Returns the new state of a device based on the notifier used.
 118  * Returns 0 on device going from enabled to disabled, 1 on device
 119  * going from disabled to enabled and -1 on no change.
 120  */
 121 int of_reconfig_get_state_change(unsigned long action, struct of_reconfig_data *pr)
 122 {
 123         struct property *prop, *old_prop = NULL;
 124         int is_status, status_state, old_status_state, prev_state, new_state;
 125
 126         /* figure out if a device should be created or destroyed */
 127         switch (action) {
 128         case OF_RECONFIG_ATTACH_NODE:
 129         case OF_RECONFIG_DETACH_NODE:
 130                 prop = of_find_property(pr->dn, "status", NULL);
 131                 break;
 132         case OF_RECONFIG_ADD_PROPERTY:
 133         case OF_RECONFIG_REMOVE_PROPERTY:
 134                 prop = pr->prop;
 135                 break;
 136         case OF_RECONFIG_UPDATE_PROPERTY:
 137                 prop = pr->prop;
 138                 old_prop = pr->old_prop;
 139                 break;
 140         default:
 141                 return OF_RECONFIG_NO_CHANGE;
 142         }
 143
 144         is_status = 0;
 145         status_state = -1;
 146         old_status_state = -1;
 147         prev_state = -1;
 148         new_state = -1;
 149
 150         if (prop && !strcmp(prop->name, "status")) {
 151                 is_status = 1;
 152                 status_state = !strcmp(prop->value, "okay") ||
 153                                !strcmp(prop->value, "ok");
 154                 if (old_prop)
 155                         old_status_state = !strcmp(old_prop->value, "okay") ||
 156                                            !strcmp(old_prop->value, "ok");
 157         }
 158
 159         switch (action) {
 160         case OF_RECONFIG_ATTACH_NODE:
 161                 prev_state = 0;
 162                 /* -1 & 0 status either missing or okay */
 163                 new_state = status_state != 0;
 164                 break;
 165         case OF_RECONFIG_DETACH_NODE:
 166                 /* -1 & 0 status either missing or okay */
 167                 prev_state = status_state != 0;
 168                 new_state = 0;
 169                 break;
 170         case OF_RECONFIG_ADD_PROPERTY:
 171                 if (is_status) {
 172                         /* no status property -> enabled (legacy) */
 173                         prev_state = 1;
 174                         new_state = status_state;
 175                 }
 176                 break;
 177         case OF_RECONFIG_REMOVE_PROPERTY:
 178                 if (is_status) {
 179                         prev_state = status_state;
 180                         /* no status property -> enabled (legacy) */
 181                         new_state = 1;
 182                 }
 183                 break;
 184         case OF_RECONFIG_UPDATE_PROPERTY:
 185                 if (is_status) {
 186                         prev_state = old_status_state != 0;
 187                         new_state = status_state != 0;
 188                 }
 189                 break;
 190         }
 191
 192         if (prev_state == new_state)
 193                 return OF_RECONFIG_NO_CHANGE;
 194
 195         return new_state ? OF_RECONFIG_CHANGE_ADD : OF_RECONFIG_CHANGE_REMOVE;
 196 }
 197 EXPORT_SYMBOL_GPL(of_reconfig_get_state_change);
 198
 199 int of_property_notify(int action, struct device_node *np,
 200                        struct property *prop, struct property *oldprop)
 201 {
 202         struct of_reconfig_data pr;
 203
 204         /* only call notifiers if the node is attached */
 205         if (!of_node_is_attached(np))
 206                 return 0;
 207
 208         pr.dn = np;
 209         pr.prop = prop;
 210         pr.old_prop = oldprop;
 211         return of_reconfig_notify(action, &pr);
 212 }
 213
 214 void __of_attach_node(struct device_node *np)
 215 {
 216         const __be32 *phandle;
 217         int sz;
 218
 219         np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
 220         np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
 221
 222         phandle = __of_get_property(np, "phandle", &sz);
 223         if (!phandle)
 224                 phandle = __of_get_property(np, "linux,phandle", &sz);
 225         if (IS_ENABLED(PPC_PSERIES) && !phandle)
 226                 phandle = __of_get_property(np, "ibm,phandle", &sz);
 227         np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;
 228
 229         np->child = NULL;
 230         np->sibling = np->parent->child;
 231         np->allnext = np->parent->allnext;
 232         np->parent->allnext = np;
 233         np->parent->child = np;
 234         of_node_clear_flag(np, OF_DETACHED);
 235 }
 236
 237 /**
 238  * of_attach_node() - Plug a device node into the tree and global list.
 239  */
 240 int of_attach_node(struct device_node *np)
 241 {
 242         struct of_reconfig_data rd;
 243         unsigned long flags;
 244
 245         memset(&rd, 0, sizeof(rd));
 246         rd.dn = np;
 247
 248         mutex_lock(&of_mutex);
 249         raw_spin_lock_irqsave(&devtree_lock, flags);
 250         __of_attach_node(np);
 251         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 252
 253         __of_attach_node_sysfs(np);
 254         mutex_unlock(&of_mutex);
 255
 256         of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, &rd);
 257
 258         return 0;
 259 }
 260
 261 void __of_detach_node(struct device_node *np)
 262 {
 263         struct device_node *parent;
 264
 265         if (WARN_ON(of_node_check_flag(np, OF_DETACHED)))
 266                 return;
 267
 268         parent = np->parent;
 269         if (WARN_ON(!parent))
 270                 return;
 271
 272         if (of_allnodes == np)
 273                 of_allnodes = np->allnext;
 274         else {
 275                 struct device_node *prev;
 276                 for (prev = of_allnodes;
 277                      prev->allnext != np;
 278                      prev = prev->allnext)
 279                         ;
 280                 prev->allnext = np->allnext;
 281         }
 282
 283         if (parent->child == np)
 284                 parent->child = np->sibling;
 285         else {
 286                 struct device_node *prevsib;
 287                 for (prevsib = np->parent->child;
 288                      prevsib->sibling != np;
 289                      prevsib = prevsib->sibling)
 290                         ;
 291                 prevsib->sibling = np->sibling;
 292         }
 293
 294         of_node_set_flag(np, OF_DETACHED);
 295 }
 296
 297 /**
 298  * of_detach_node() - "Unplug" a node from the device tree.
 299  *
 300  * The caller must hold a reference to the node.  The memory associated with
 301  * the node is not freed until its refcount goes to zero.
 302  */
 303 int of_detach_node(struct device_node *np)
 304 {
 305         struct of_reconfig_data rd;
 306         unsigned long flags;
 307         int rc = 0;
 308
 309         memset(&rd, 0, sizeof(rd));
 310         rd.dn = np;
 311
 312         mutex_lock(&of_mutex);
 313         raw_spin_lock_irqsave(&devtree_lock, flags);
 314         __of_detach_node(np);
 315         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 316
 317         __of_detach_node_sysfs(np);
 318         mutex_unlock(&of_mutex);
 319
 320         of_reconfig_notify(OF_RECONFIG_DETACH_NODE, &rd);
 321
 322         return rc;
 323 }
 324
 325 /**
 326  * of_node_release() - release a dynamically allocated node
 327  * @kref: kref element of the node to be released
 328  *
 329  * In of_node_put() this function is passed to kref_put() as the destructor.
 330  */
 331 void of_node_release(struct kobject *kobj)
 332 {
 333         struct device_node *node = kobj_to_device_node(kobj);
 334         struct property *prop = node->properties;
 335
 336         /* We should never be releasing nodes that haven't been detached. */
 337         if (!of_node_check_flag(node, OF_DETACHED)) {
 338                 pr_err("ERROR: Bad of_node_put() on %s\n", node->full_name);
 339                 dump_stack();
 340                 return;
 341         }
 342
 343         if (!of_node_check_flag(node, OF_DYNAMIC))
 344                 return;
 345
 346         while (prop) {
 347                 struct property *next = prop->next;
 348                 kfree(prop->name);
 349                 kfree(prop->value);
 350                 kfree(prop);
 351                 prop = next;
 352
 353                 if (!prop) {
 354                         prop = node->deadprops;
 355                         node->deadprops = NULL;
 356                 }
 357         }
 358         kfree(node->full_name);
 359         kfree(node->data);
 360         kfree(node);
 361 }
 362
 363 /**
 364  * __of_prop_dup - Copy a property dynamically.
 365  * @prop:       Property to copy
 366  * @allocflags: Allocation flags (typically pass GFP_KERNEL)
 367  *
 368  * Copy a property by dynamically allocating the memory of both the
 369  * property stucture and the property name & contents. The property's
 370  * flags have the OF_DYNAMIC bit set so that we can differentiate between
 371  * dynamically allocated properties and not.
 372  * Returns the newly allocated property or NULL on out of memory error.
 373  */
 374 struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
 375 {
 376         struct property *new;
 377
 378         new = kzalloc(sizeof(*new), allocflags);
 379         if (!new)
 380                 return NULL;
 381
 382         /*
 383          * NOTE: There is no check for zero length value.
 384          * In case of a boolean property This will allocate a value
 385          * of zero bytes. We do this to work around the use
 386          * of of_get_property() calls on boolean values.
 387          */
 388         new->name = kstrdup(prop->name, allocflags);
 389         new->value = kmemdup(prop->value, prop->length, allocflags);
 390         new->length = prop->length;
 391         if (!new->name || !new->value)
 392                 goto err_free;
 393
 394         /* mark the property as dynamic */
 395         of_property_set_flag(new, OF_DYNAMIC);
 396
 397         return new;
 398
 399  err_free:
 400         kfree(new->name);
 401         kfree(new->value);
 402         kfree(new);
 403         return NULL;
 404 }
 405
 406 /**
 407  * __of_node_alloc() - Create an empty device node dynamically.
 408  * @full_name:  Full name of the new device node
 409  * @allocflags: Allocation flags (typically pass GFP_KERNEL)
 410  *
 411  * Create an empty device tree node, suitable for further modification.
 412  * The node data are dynamically allocated and all the node flags
 413  * have the OF_DYNAMIC & OF_DETACHED bits set.
 414  * Returns the newly allocated node or NULL on out of memory error.
 415  */
 416 struct device_node *__of_node_alloc(const char *full_name, gfp_t allocflags)
 417 {
 418         struct device_node *node;
 419
 420         node = kzalloc(sizeof(*node), allocflags);
 421         if (!node)
 422                 return NULL;
 423
 424         node->full_name = kstrdup(full_name, allocflags);
 425         of_node_set_flag(node, OF_DYNAMIC);
 426         of_node_set_flag(node, OF_DETACHED);
 427         if (!node->full_name)
 428                 goto err_free;
 429
 430         of_node_init(node);
 431
 432         return node;
 433
 434  err_free:
 435         kfree(node->full_name);
 436         kfree(node);
 437         return NULL;
 438 }
 439
 440 static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
 441 {
 442         of_node_put(ce->np);
 443         list_del(&ce->node);
 444         kfree(ce);
 445 }
 446
 447 #ifdef DEBUG
 448 static void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 449 {
 450         switch (ce->action) {
 451         case OF_RECONFIG_ADD_PROPERTY:
 452         case OF_RECONFIG_REMOVE_PROPERTY:
 453         case OF_RECONFIG_UPDATE_PROPERTY:
 454                 pr_debug("of/cset<%p> %-15s %s/%s\n", ce, action_names[ce->action],
 455                         ce->np->full_name, ce->prop->name);
 456                 break;
 457         case OF_RECONFIG_ATTACH_NODE:
 458         case OF_RECONFIG_DETACH_NODE:
 459                 pr_debug("of/cset<%p> %-15s %s\n", ce, action_names[ce->action],
 460                         ce->np->full_name);
 461                 break;
 462         }
 463 }
 464 #else
 465 static inline void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 466 {
 467         /* empty */
 468 }
 469 #endif
 470
 471 static void __of_changeset_entry_invert(struct of_changeset_entry *ce,
 472                                           struct of_changeset_entry *rce)
 473 {
 474         memcpy(rce, ce, sizeof(*rce));
 475
 476         switch (ce->action) {
 477         case OF_RECONFIG_ATTACH_NODE:
 478                 rce->action = OF_RECONFIG_DETACH_NODE;
 479                 break;
 480         case OF_RECONFIG_DETACH_NODE:
 481                 rce->action = OF_RECONFIG_ATTACH_NODE;
 482                 break;
 483         case OF_RECONFIG_ADD_PROPERTY:
 484                 rce->action = OF_RECONFIG_REMOVE_PROPERTY;
 485                 break;
 486         case OF_RECONFIG_REMOVE_PROPERTY:
 487                 rce->action = OF_RECONFIG_ADD_PROPERTY;
 488                 break;
 489         case OF_RECONFIG_UPDATE_PROPERTY:
 490                 rce->old_prop = ce->prop;
 491                 rce->prop = ce->old_prop;
 492                 break;
 493         }
 494 }
 495
 496 static void __of_changeset_entry_notify(struct of_changeset_entry *ce, bool revert)
 497 {
 498         struct of_reconfig_data rd;
 499         struct of_changeset_entry ce_inverted;
 500         int ret;
 501
 502         if (revert) {
 503                 __of_changeset_entry_invert(ce, &ce_inverted);
 504                 ce = &ce_inverted;
 505         }
 506
 507         switch (ce->action) {
 508         case OF_RECONFIG_ATTACH_NODE:
 509         case OF_RECONFIG_DETACH_NODE:
 510                 memset(&rd, 0, sizeof(rd));
 511                 rd.dn = ce->np;
 512                 ret = of_reconfig_notify(ce->action, &rd);
 513                 break;
 514         case OF_RECONFIG_ADD_PROPERTY:
 515         case OF_RECONFIG_REMOVE_PROPERTY:
 516         case OF_RECONFIG_UPDATE_PROPERTY:
 517                 ret = of_property_notify(ce->action, ce->np, ce->prop, ce->old_prop);
 518                 break;
 519         default:
 520                 pr_err("%s: invalid devicetree changeset action: %i\n", __func__,
 521                         (int)ce->action);
 522                 return;
 523         }
 524
 525         if (ret)
 526                 pr_err("%s: notifier error @%s\n", __func__, ce->np->full_name);
 527 }
 528
 529 static int __of_changeset_entry_apply(struct of_changeset_entry *ce)
 530 {
 531         struct property *old_prop, **propp;
 532         unsigned long flags;
 533         int ret = 0;
 534
 535         __of_changeset_entry_dump(ce);
 536
 537         raw_spin_lock_irqsave(&devtree_lock, flags);
 538         switch (ce->action) {
 539         case OF_RECONFIG_ATTACH_NODE:
 540                 __of_attach_node(ce->np);
 541                 break;
 542         case OF_RECONFIG_DETACH_NODE:
 543                 __of_detach_node(ce->np);
 544                 break;
 545         case OF_RECONFIG_ADD_PROPERTY:
 546                 /* If the property is in deadprops then it must be removed */
 547                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 548                         if (*propp == ce->prop) {
 549                                 *propp = ce->prop->next;
 550                                 ce->prop->next = NULL;
 551                                 break;
 552                         }
 553                 }
 554
 555                 ret = __of_add_property(ce->np, ce->prop);
 556                 if (ret) {
 557                         pr_err("%s: add_property failed @%s/%s\n",
 558                                 __func__, ce->np->full_name,
 559                                 ce->prop->name);
 560                         break;
 561                 }
 562                 break;
 563         case OF_RECONFIG_REMOVE_PROPERTY:
 564                 ret = __of_remove_property(ce->np, ce->prop);
 565                 if (ret) {
 566                         pr_err("%s: remove_property failed @%s/%s\n",
 567                                 __func__, ce->np->full_name,
 568                                 ce->prop->name);
 569                         break;
 570                 }
 571                 break;
 572
 573         case OF_RECONFIG_UPDATE_PROPERTY:
 574                 /* If the property is in deadprops then it must be removed */
 575                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 576                         if (*propp == ce->prop) {
 577                                 *propp = ce->prop->next;
 578                                 ce->prop->next = NULL;
 579                                 break;
 580                         }
 581                 }
 582
 583                 ret = __of_update_property(ce->np, ce->prop, &old_prop);
 584                 if (ret) {
 585                         pr_err("%s: update_property failed @%s/%s\n",
 586                                 __func__, ce->np->full_name,
 587                                 ce->prop->name);
 588                         break;
 589                 }
 590                 break;
 591         default:
 592                 ret = -EINVAL;
 593         }
 594         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 595
 596         if (ret)
 597                 return ret;
 598
 599         switch (ce->action) {
 600         case OF_RECONFIG_ATTACH_NODE:
 601                 __of_attach_node_sysfs(ce->np);
 602                 break;
 603         case OF_RECONFIG_DETACH_NODE:
 604                 __of_detach_node_sysfs(ce->np);
 605                 break;
 606         case OF_RECONFIG_ADD_PROPERTY:
 607                 /* ignore duplicate names */
 608                 __of_add_property_sysfs(ce->np, ce->prop);
 609                 break;
 610         case OF_RECONFIG_REMOVE_PROPERTY:
 611                 __of_remove_property_sysfs(ce->np, ce->prop);
 612                 break;
 613         case OF_RECONFIG_UPDATE_PROPERTY:
 614                 __of_update_property_sysfs(ce->np, ce->prop, ce->old_prop);
 615                 break;
 616         }
 617
 618         return 0;
 619 }
 620
 621 static inline int __of_changeset_entry_revert(struct of_changeset_entry *ce)
 622 {
 623         struct of_changeset_entry ce_inverted;
 624
 625         __of_changeset_entry_invert(ce, &ce_inverted);
 626         return __of_changeset_entry_apply(&ce_inverted);
 627 }
 628
 629 /**
 630  * of_changeset_init - Initialize a changeset for use
 631  *
 632  * @ocs:        changeset pointer
 633  *
 634  * Initialize a changeset structure
 635  */
 636 void of_changeset_init(struct of_changeset *ocs)
 637 {
 638         memset(ocs, 0, sizeof(*ocs));
 639         INIT_LIST_HEAD(&ocs->entries);
 640 }
 641
 642 /**
 643  * of_changeset_destroy - Destroy a changeset
 644  *
 645  * @ocs:        changeset pointer
 646  *
 647  * Destroys a changeset. Note that if a changeset is applied,
 648  * its changes to the tree cannot be reverted.
 649  */
 650 void of_changeset_destroy(struct of_changeset *ocs)
 651 {
 652         struct of_changeset_entry *ce, *cen;
 653
 654         list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node)
 655                 __of_changeset_entry_destroy(ce);
 656 }
 657
 658 /**
 659  * of_changeset_apply - Applies a changeset
 660  *
 661  * @ocs:        changeset pointer
 662  *
 663  * Applies a changeset to the live tree.
 664  * Any side-effects of live tree state changes are applied here on
 665  * sucess, like creation/destruction of devices and side-effects
 666  * like creation of sysfs properties and directories.
 667  * Returns 0 on success, a negative error value in case of an error.
 668  * On error the partially applied effects are reverted.
 669  */
 670 int of_changeset_apply(struct of_changeset *ocs)
 671 {
 672         struct of_changeset_entry *ce;
 673         int ret;
 674
 675         /* perform the rest of the work */
 676         pr_debug("of_changeset: applying...\n");
 677         list_for_each_entry(ce, &ocs->entries, node) {
 678                 ret = __of_changeset_entry_apply(ce);
 679                 if (ret) {
 680                         pr_err("%s: Error applying changeset (%d)\n", __func__, ret);
 681                         list_for_each_entry_continue_reverse(ce, &ocs->entries, node)
 682                                 __of_changeset_entry_revert(ce);
 683                         return ret;
 684                 }
 685         }
 686         pr_debug("of_changeset: applied, emitting notifiers.\n");
 687
 688         /* drop the global lock while emitting notifiers */
 689         mutex_unlock(&of_mutex);
 690         list_for_each_entry(ce, &ocs->entries, node)
 691                 __of_changeset_entry_notify(ce, 0);
 692         mutex_lock(&of_mutex);
 693         pr_debug("of_changeset: notifiers sent.\n");
 694
 695         return 0;
 696 }
 697
 698 /**
 699  * of_changeset_revert - Reverts an applied changeset
 700  *
 701  * @ocs:        changeset pointer
 702  *
 703  * Reverts a changeset returning the state of the tree to what it
 704  * was before the application.
 705  * Any side-effects like creation/destruction of devices and
 706  * removal of sysfs properties and directories are applied.
 707  * Returns 0 on success, a negative error value in case of an error.
 708  */
 709 int of_changeset_revert(struct of_changeset *ocs)
 710 {
 711         struct of_changeset_entry *ce;
 712         int ret;
 713
 714         pr_debug("of_changeset: reverting...\n");
 715         list_for_each_entry_reverse(ce, &ocs->entries, node) {
 716                 ret = __of_changeset_entry_revert(ce);
 717                 if (ret) {
 718                         pr_err("%s: Error reverting changeset (%d)\n", __func__, ret);
 719                         list_for_each_entry_continue(ce, &ocs->entries, node)
 720                                 __of_changeset_entry_apply(ce);
 721                         return ret;
 722                 }
 723         }
 724         pr_debug("of_changeset: reverted, emitting notifiers.\n");
 725
 726         /* drop the global lock while emitting notifiers */
 727         mutex_unlock(&of_mutex);
 728         list_for_each_entry_reverse(ce, &ocs->entries, node)
 729                 __of_changeset_entry_notify(ce, 1);
 730         mutex_lock(&of_mutex);
 731         pr_debug("of_changeset: notifiers sent.\n");
 732
 733         return 0;
 734 }
 735
 736 /**
 737  * of_changeset_action - Perform a changeset action
 738  *
 739  * @ocs:        changeset pointer
 740  * @action:     action to perform
 741  * @np:         Pointer to device node
 742  * @prop:       Pointer to property
 743  *
 744  * On action being one of:
 745  * + OF_RECONFIG_ATTACH_NODE
 746  * + OF_RECONFIG_DETACH_NODE,
 747  * + OF_RECONFIG_ADD_PROPERTY
 748  * + OF_RECONFIG_REMOVE_PROPERTY,
 749  * + OF_RECONFIG_UPDATE_PROPERTY
 750  * Returns 0 on success, a negative error value in case of an error.
 751  */
 752 int of_changeset_action(struct of_changeset *ocs, unsigned long action,
 753                 struct device_node *np, struct property *prop)
 754 {
 755         struct of_changeset_entry *ce;
 756
 757         ce = kzalloc(sizeof(*ce), GFP_KERNEL);
 758         if (!ce) {
 759                 pr_err("%s: Failed to allocate\n", __func__);
 760                 return -ENOMEM;
 761         }
 762         /* get a reference to the node */
 763         ce->action = action;
 764         ce->np = of_node_get(np);
 765         ce->prop = prop;
 766
 767         if (action == OF_RECONFIG_UPDATE_PROPERTY && prop)
 768                 ce->old_prop = of_find_property(np, prop->name, NULL);
 769
 770         /* add it to the list */
 771         list_add_tail(&ce->node, &ocs->entries);
 772         return 0;
 773 }