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         if (!IS_ENABLED(CONFIG_SYSFS))
  49                 return;
  50
  51         BUG_ON(!of_node_is_initialized(np));
  52         if (!of_kset)
  53                 return;
  54
  55         /* only remove properties if on sysfs */
  56         if (of_node_is_attached(np)) {
  57                 for_each_property_of_node(np, pp)
  58                         sysfs_remove_bin_file(&np->kobj, &pp->attr);
  59                 kobject_del(&np->kobj);
  60         }
  61
  62         /* finally remove the kobj_init ref */
  63         of_node_put(np);
  64 }
  65
  66 static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain);
  67
  68 int of_reconfig_notifier_register(struct notifier_block *nb)
  69 {
  70         return blocking_notifier_chain_register(&of_reconfig_chain, nb);
  71 }
  72 EXPORT_SYMBOL_GPL(of_reconfig_notifier_register);
  73
  74 int of_reconfig_notifier_unregister(struct notifier_block *nb)
  75 {
  76         return blocking_notifier_chain_unregister(&of_reconfig_chain, nb);
  77 }
  78 EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister);
  79
  80 #ifdef DEBUG
  81 const char *action_names[] = {
  82         [OF_RECONFIG_ATTACH_NODE] = "ATTACH_NODE",
  83         [OF_RECONFIG_DETACH_NODE] = "DETACH_NODE",
  84         [OF_RECONFIG_ADD_PROPERTY] = "ADD_PROPERTY",
  85         [OF_RECONFIG_REMOVE_PROPERTY] = "REMOVE_PROPERTY",
  86         [OF_RECONFIG_UPDATE_PROPERTY] = "UPDATE_PROPERTY",
  87 };
  88 #endif
  89
  90 int of_reconfig_notify(unsigned long action, struct of_reconfig_data *p)
  91 {
  92         int rc;
  93 #ifdef DEBUG
  94         struct of_reconfig_data *pr = p;
  95
  96         switch (action) {
  97         case OF_RECONFIG_ATTACH_NODE:
  98         case OF_RECONFIG_DETACH_NODE:
  99                 pr_debug("of/notify %-15s %s\n", action_names[action],
 100                         pr->dn->full_name);
 101                 break;
 102         case OF_RECONFIG_ADD_PROPERTY:
 103         case OF_RECONFIG_REMOVE_PROPERTY:
 104         case OF_RECONFIG_UPDATE_PROPERTY:
 105                 pr_debug("of/notify %-15s %s:%s\n", action_names[action],
 106                         pr->dn->full_name, pr->prop->name);
 107                 break;
 108
 109         }
 110 #endif
 111         rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p);
 112         return notifier_to_errno(rc);
 113 }
 114
 115 /*
 116  * of_reconfig_get_state_change()       - Returns new state of device
 117  * @action      - action of the of notifier
 118  * @arg         - argument of the of notifier
 119  *
 120  * Returns the new state of a device based on the notifier used.
 121  * Returns 0 on device going from enabled to disabled, 1 on device
 122  * going from disabled to enabled and -1 on no change.
 123  */
 124 int of_reconfig_get_state_change(unsigned long action, struct of_reconfig_data *pr)
 125 {
 126         struct property *prop, *old_prop = NULL;
 127         int is_status, status_state, old_status_state, prev_state, new_state;
 128
 129         /* figure out if a device should be created or destroyed */
 130         switch (action) {
 131         case OF_RECONFIG_ATTACH_NODE:
 132         case OF_RECONFIG_DETACH_NODE:
 133                 prop = of_find_property(pr->dn, "status", NULL);
 134                 break;
 135         case OF_RECONFIG_ADD_PROPERTY:
 136         case OF_RECONFIG_REMOVE_PROPERTY:
 137                 prop = pr->prop;
 138                 break;
 139         case OF_RECONFIG_UPDATE_PROPERTY:
 140                 prop = pr->prop;
 141                 old_prop = pr->old_prop;
 142                 break;
 143         default:
 144                 return OF_RECONFIG_NO_CHANGE;
 145         }
 146
 147         is_status = 0;
 148         status_state = -1;
 149         old_status_state = -1;
 150         prev_state = -1;
 151         new_state = -1;
 152
 153         if (prop && !strcmp(prop->name, "status")) {
 154                 is_status = 1;
 155                 status_state = !strcmp(prop->value, "okay") ||
 156                                !strcmp(prop->value, "ok");
 157                 if (old_prop)
 158                         old_status_state = !strcmp(old_prop->value, "okay") ||
 159                                            !strcmp(old_prop->value, "ok");
 160         }
 161
 162         switch (action) {
 163         case OF_RECONFIG_ATTACH_NODE:
 164                 prev_state = 0;
 165                 /* -1 & 0 status either missing or okay */
 166                 new_state = status_state != 0;
 167                 break;
 168         case OF_RECONFIG_DETACH_NODE:
 169                 /* -1 & 0 status either missing or okay */
 170                 prev_state = status_state != 0;
 171                 new_state = 0;
 172                 break;
 173         case OF_RECONFIG_ADD_PROPERTY:
 174                 if (is_status) {
 175                         /* no status property -> enabled (legacy) */
 176                         prev_state = 1;
 177                         new_state = status_state;
 178                 }
 179                 break;
 180         case OF_RECONFIG_REMOVE_PROPERTY:
 181                 if (is_status) {
 182                         prev_state = status_state;
 183                         /* no status property -> enabled (legacy) */
 184                         new_state = 1;
 185                 }
 186                 break;
 187         case OF_RECONFIG_UPDATE_PROPERTY:
 188                 if (is_status) {
 189                         prev_state = old_status_state != 0;
 190                         new_state = status_state != 0;
 191                 }
 192                 break;
 193         }
 194
 195         if (prev_state == new_state)
 196                 return OF_RECONFIG_NO_CHANGE;
 197
 198         return new_state ? OF_RECONFIG_CHANGE_ADD : OF_RECONFIG_CHANGE_REMOVE;
 199 }
 200 EXPORT_SYMBOL_GPL(of_reconfig_get_state_change);
 201
 202 int of_property_notify(int action, struct device_node *np,
 203                        struct property *prop, struct property *oldprop)
 204 {
 205         struct of_reconfig_data pr;
 206
 207         /* only call notifiers if the node is attached */
 208         if (!of_node_is_attached(np))
 209                 return 0;
 210
 211         pr.dn = np;
 212         pr.prop = prop;
 213         pr.old_prop = oldprop;
 214         return of_reconfig_notify(action, &pr);
 215 }
 216
 217 void __of_attach_node(struct device_node *np)
 218 {
 219         const __be32 *phandle;
 220         int sz;
 221
 222         np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
 223         np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
 224
 225         phandle = __of_get_property(np, "phandle", &sz);
 226         if (!phandle)
 227                 phandle = __of_get_property(np, "linux,phandle", &sz);
 228         if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
 229                 phandle = __of_get_property(np, "ibm,phandle", &sz);
 230         np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;
 231
 232         np->child = NULL;
 233         np->sibling = np->parent->child;
 234         np->parent->child = np;
 235         of_node_clear_flag(np, OF_DETACHED);
 236 }
 237
 238 /**
 239  * of_attach_node() - Plug a device node into the tree and global list.
 240  */
 241 int of_attach_node(struct device_node *np)
 242 {
 243         struct of_reconfig_data rd;
 244         unsigned long flags;
 245
 246         memset(&rd, 0, sizeof(rd));
 247         rd.dn = np;
 248
 249         mutex_lock(&of_mutex);
 250         raw_spin_lock_irqsave(&devtree_lock, flags);
 251         __of_attach_node(np);
 252         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 253
 254         __of_attach_node_sysfs(np);
 255         mutex_unlock(&of_mutex);
 256
 257         of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, &rd);
 258
 259         return 0;
 260 }
 261
 262 void __of_detach_node(struct device_node *np)
 263 {
 264         struct device_node *parent;
 265
 266         if (WARN_ON(of_node_check_flag(np, OF_DETACHED)))
 267                 return;
 268
 269         parent = np->parent;
 270         if (WARN_ON(!parent))
 271                 return;
 272
 273         if (parent->child == np)
 274                 parent->child = np->sibling;
 275         else {
 276                 struct device_node *prevsib;
 277                 for (prevsib = np->parent->child;
 278                      prevsib->sibling != np;
 279                      prevsib = prevsib->sibling)
 280                         ;
 281                 prevsib->sibling = np->sibling;
 282         }
 283
 284         of_node_set_flag(np, OF_DETACHED);
 285 }
 286
 287 /**
 288  * of_detach_node() - "Unplug" a node from the device tree.
 289  *
 290  * The caller must hold a reference to the node.  The memory associated with
 291  * the node is not freed until its refcount goes to zero.
 292  */
 293 int of_detach_node(struct device_node *np)
 294 {
 295         struct of_reconfig_data rd;
 296         unsigned long flags;
 297         int rc = 0;
 298
 299         memset(&rd, 0, sizeof(rd));
 300         rd.dn = np;
 301
 302         mutex_lock(&of_mutex);
 303         raw_spin_lock_irqsave(&devtree_lock, flags);
 304         __of_detach_node(np);
 305         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 306
 307         __of_detach_node_sysfs(np);
 308         mutex_unlock(&of_mutex);
 309
 310         of_reconfig_notify(OF_RECONFIG_DETACH_NODE, &rd);
 311
 312         return rc;
 313 }
 314
 315 /**
 316  * of_node_release() - release a dynamically allocated node
 317  * @kref: kref element of the node to be released
 318  *
 319  * In of_node_put() this function is passed to kref_put() as the destructor.
 320  */
 321 void of_node_release(struct kobject *kobj)
 322 {
 323         struct device_node *node = kobj_to_device_node(kobj);
 324         struct property *prop = node->properties;
 325
 326         /* We should never be releasing nodes that haven't been detached. */
 327         if (!of_node_check_flag(node, OF_DETACHED)) {
 328                 pr_err("ERROR: Bad of_node_put() on %s\n", node->full_name);
 329                 dump_stack();
 330                 return;
 331         }
 332
 333         if (!of_node_check_flag(node, OF_DYNAMIC))
 334                 return;
 335
 336         while (prop) {
 337                 struct property *next = prop->next;
 338                 kfree(prop->name);
 339                 kfree(prop->value);
 340                 kfree(prop);
 341                 prop = next;
 342
 343                 if (!prop) {
 344                         prop = node->deadprops;
 345                         node->deadprops = NULL;
 346                 }
 347         }
 348         kfree(node->full_name);
 349         kfree(node->data);
 350         kfree(node);
 351 }
 352
 353 /**
 354  * __of_prop_dup - Copy a property dynamically.
 355  * @prop:       Property to copy
 356  * @allocflags: Allocation flags (typically pass GFP_KERNEL)
 357  *
 358  * Copy a property by dynamically allocating the memory of both the
 359  * property structure and the property name & contents. The property's
 360  * flags have the OF_DYNAMIC bit set so that we can differentiate between
 361  * dynamically allocated properties and not.
 362  * Returns the newly allocated property or NULL on out of memory error.
 363  */
 364 struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
 365 {
 366         struct property *new;
 367
 368         new = kzalloc(sizeof(*new), allocflags);
 369         if (!new)
 370                 return NULL;
 371
 372         /*
 373          * NOTE: There is no check for zero length value.
 374          * In case of a boolean property, this will allocate a value
 375          * of zero bytes. We do this to work around the use
 376          * of of_get_property() calls on boolean values.
 377          */
 378         new->name = kstrdup(prop->name, allocflags);
 379         new->value = kmemdup(prop->value, prop->length, allocflags);
 380         new->length = prop->length;
 381         if (!new->name || !new->value)
 382                 goto err_free;
 383
 384         /* mark the property as dynamic */
 385         of_property_set_flag(new, OF_DYNAMIC);
 386
 387         return new;
 388
 389  err_free:
 390         kfree(new->name);
 391         kfree(new->value);
 392         kfree(new);
 393         return NULL;
 394 }
 395
 396 /**
 397  * __of_node_dup() - Duplicate or create an empty device node dynamically.
 398  * @fmt: Format string (plus vargs) for new full name of the device node
 399  *
 400  * Create an device tree node, either by duplicating an empty node or by allocating
 401  * an empty one suitable for further modification.  The node data are
 402  * dynamically allocated and all the node flags have the OF_DYNAMIC &
 403  * OF_DETACHED bits set. Returns the newly allocated node or NULL on out of
 404  * memory error.
 405  */
 406 struct device_node *__of_node_dup(const struct device_node *np, const char *fmt, ...)
 407 {
 408         va_list vargs;
 409         struct device_node *node;
 410
 411         node = kzalloc(sizeof(*node), GFP_KERNEL);
 412         if (!node)
 413                 return NULL;
 414         va_start(vargs, fmt);
 415         node->full_name = kvasprintf(GFP_KERNEL, fmt, vargs);
 416         va_end(vargs);
 417         if (!node->full_name) {
 418                 kfree(node);
 419                 return NULL;
 420         }
 421
 422         of_node_set_flag(node, OF_DYNAMIC);
 423         of_node_set_flag(node, OF_DETACHED);
 424         of_node_init(node);
 425
 426         /* Iterate over and duplicate all properties */
 427         if (np) {
 428                 struct property *pp, *new_pp;
 429                 for_each_property_of_node(np, pp) {
 430                         new_pp = __of_prop_dup(pp, GFP_KERNEL);
 431                         if (!new_pp)
 432                                 goto err_prop;
 433                         if (__of_add_property(node, new_pp)) {
 434                                 kfree(new_pp->name);
 435                                 kfree(new_pp->value);
 436                                 kfree(new_pp);
 437                                 goto err_prop;
 438                         }
 439                 }
 440         }
 441         return node;
 442
 443  err_prop:
 444         of_node_put(node); /* Frees the node and properties */
 445         return NULL;
 446 }
 447
 448 static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
 449 {
 450         of_node_put(ce->np);
 451         list_del(&ce->node);
 452         kfree(ce);
 453 }
 454
 455 #ifdef DEBUG
 456 static void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 457 {
 458         switch (ce->action) {
 459         case OF_RECONFIG_ADD_PROPERTY:
 460         case OF_RECONFIG_REMOVE_PROPERTY:
 461         case OF_RECONFIG_UPDATE_PROPERTY:
 462                 pr_debug("of/cset<%p> %-15s %s/%s\n", ce, action_names[ce->action],
 463                         ce->np->full_name, ce->prop->name);
 464                 break;
 465         case OF_RECONFIG_ATTACH_NODE:
 466         case OF_RECONFIG_DETACH_NODE:
 467                 pr_debug("of/cset<%p> %-15s %s\n", ce, action_names[ce->action],
 468                         ce->np->full_name);
 469                 break;
 470         }
 471 }
 472 #else
 473 static inline void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 474 {
 475         /* empty */
 476 }
 477 #endif
 478
 479 static void __of_changeset_entry_invert(struct of_changeset_entry *ce,
 480                                           struct of_changeset_entry *rce)
 481 {
 482         memcpy(rce, ce, sizeof(*rce));
 483
 484         switch (ce->action) {
 485         case OF_RECONFIG_ATTACH_NODE:
 486                 rce->action = OF_RECONFIG_DETACH_NODE;
 487                 break;
 488         case OF_RECONFIG_DETACH_NODE:
 489                 rce->action = OF_RECONFIG_ATTACH_NODE;
 490                 break;
 491         case OF_RECONFIG_ADD_PROPERTY:
 492                 rce->action = OF_RECONFIG_REMOVE_PROPERTY;
 493                 break;
 494         case OF_RECONFIG_REMOVE_PROPERTY:
 495                 rce->action = OF_RECONFIG_ADD_PROPERTY;
 496                 break;
 497         case OF_RECONFIG_UPDATE_PROPERTY:
 498                 rce->old_prop = ce->prop;
 499                 rce->prop = ce->old_prop;
 500                 break;
 501         }
 502 }
 503
 504 static void __of_changeset_entry_notify(struct of_changeset_entry *ce, bool revert)
 505 {
 506         struct of_reconfig_data rd;
 507         struct of_changeset_entry ce_inverted;
 508         int ret;
 509
 510         if (revert) {
 511                 __of_changeset_entry_invert(ce, &ce_inverted);
 512                 ce = &ce_inverted;
 513         }
 514
 515         switch (ce->action) {
 516         case OF_RECONFIG_ATTACH_NODE:
 517         case OF_RECONFIG_DETACH_NODE:
 518                 memset(&rd, 0, sizeof(rd));
 519                 rd.dn = ce->np;
 520                 ret = of_reconfig_notify(ce->action, &rd);
 521                 break;
 522         case OF_RECONFIG_ADD_PROPERTY:
 523         case OF_RECONFIG_REMOVE_PROPERTY:
 524         case OF_RECONFIG_UPDATE_PROPERTY:
 525                 ret = of_property_notify(ce->action, ce->np, ce->prop, ce->old_prop);
 526                 break;
 527         default:
 528                 pr_err("%s: invalid devicetree changeset action: %i\n", __func__,
 529                         (int)ce->action);
 530                 return;
 531         }
 532
 533         if (ret)
 534                 pr_err("%s: notifier error @%s\n", __func__, ce->np->full_name);
 535 }
 536
 537 static int __of_changeset_entry_apply(struct of_changeset_entry *ce)
 538 {
 539         struct property *old_prop, **propp;
 540         unsigned long flags;
 541         int ret = 0;
 542
 543         __of_changeset_entry_dump(ce);
 544
 545         raw_spin_lock_irqsave(&devtree_lock, flags);
 546         switch (ce->action) {
 547         case OF_RECONFIG_ATTACH_NODE:
 548                 __of_attach_node(ce->np);
 549                 break;
 550         case OF_RECONFIG_DETACH_NODE:
 551                 __of_detach_node(ce->np);
 552                 break;
 553         case OF_RECONFIG_ADD_PROPERTY:
 554                 /* If the property is in deadprops then it must be removed */
 555                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 556                         if (*propp == ce->prop) {
 557                                 *propp = ce->prop->next;
 558                                 ce->prop->next = NULL;
 559                                 break;
 560                         }
 561                 }
 562
 563                 ret = __of_add_property(ce->np, ce->prop);
 564                 if (ret) {
 565                         pr_err("%s: add_property failed @%s/%s\n",
 566                                 __func__, ce->np->full_name,
 567                                 ce->prop->name);
 568                         break;
 569                 }
 570                 break;
 571         case OF_RECONFIG_REMOVE_PROPERTY:
 572                 ret = __of_remove_property(ce->np, ce->prop);
 573                 if (ret) {
 574                         pr_err("%s: remove_property failed @%s/%s\n",
 575                                 __func__, ce->np->full_name,
 576                                 ce->prop->name);
 577                         break;
 578                 }
 579                 break;
 580
 581         case OF_RECONFIG_UPDATE_PROPERTY:
 582                 /* If the property is in deadprops then it must be removed */
 583                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 584                         if (*propp == ce->prop) {
 585                                 *propp = ce->prop->next;
 586                                 ce->prop->next = NULL;
 587                                 break;
 588                         }
 589                 }
 590
 591                 ret = __of_update_property(ce->np, ce->prop, &old_prop);
 592                 if (ret) {
 593                         pr_err("%s: update_property failed @%s/%s\n",
 594                                 __func__, ce->np->full_name,
 595                                 ce->prop->name);
 596                         break;
 597                 }
 598                 break;
 599         default:
 600                 ret = -EINVAL;
 601         }
 602         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 603
 604         if (ret)
 605                 return ret;
 606
 607         switch (ce->action) {
 608         case OF_RECONFIG_ATTACH_NODE:
 609                 __of_attach_node_sysfs(ce->np);
 610                 break;
 611         case OF_RECONFIG_DETACH_NODE:
 612                 __of_detach_node_sysfs(ce->np);
 613                 break;
 614         case OF_RECONFIG_ADD_PROPERTY:
 615                 /* ignore duplicate names */
 616                 __of_add_property_sysfs(ce->np, ce->prop);
 617                 break;
 618         case OF_RECONFIG_REMOVE_PROPERTY:
 619                 __of_remove_property_sysfs(ce->np, ce->prop);
 620                 break;
 621         case OF_RECONFIG_UPDATE_PROPERTY:
 622                 __of_update_property_sysfs(ce->np, ce->prop, ce->old_prop);
 623                 break;
 624         }
 625
 626         return 0;
 627 }
 628
 629 static inline int __of_changeset_entry_revert(struct of_changeset_entry *ce)
 630 {
 631         struct of_changeset_entry ce_inverted;
 632
 633         __of_changeset_entry_invert(ce, &ce_inverted);
 634         return __of_changeset_entry_apply(&ce_inverted);
 635 }
 636
 637 /**
 638  * of_changeset_init - Initialize a changeset for use
 639  *
 640  * @ocs:        changeset pointer
 641  *
 642  * Initialize a changeset structure
 643  */
 644 void of_changeset_init(struct of_changeset *ocs)
 645 {
 646         memset(ocs, 0, sizeof(*ocs));
 647         INIT_LIST_HEAD(&ocs->entries);
 648 }
 649
 650 /**
 651  * of_changeset_destroy - Destroy a changeset
 652  *
 653  * @ocs:        changeset pointer
 654  *
 655  * Destroys a changeset. Note that if a changeset is applied,
 656  * its changes to the tree cannot be reverted.
 657  */
 658 void of_changeset_destroy(struct of_changeset *ocs)
 659 {
 660         struct of_changeset_entry *ce, *cen;
 661
 662         list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node)
 663                 __of_changeset_entry_destroy(ce);
 664 }
 665
 666 /**
 667  * of_changeset_apply - Applies a changeset
 668  *
 669  * @ocs:        changeset pointer
 670  *
 671  * Applies a changeset to the live tree.
 672  * Any side-effects of live tree state changes are applied here on
 673  * sucess, like creation/destruction of devices and side-effects
 674  * like creation of sysfs properties and directories.
 675  * Returns 0 on success, a negative error value in case of an error.
 676  * On error the partially applied effects are reverted.
 677  */
 678 int of_changeset_apply(struct of_changeset *ocs)
 679 {
 680         struct of_changeset_entry *ce;
 681         int ret;
 682
 683         /* perform the rest of the work */
 684         pr_debug("of_changeset: applying...\n");
 685         list_for_each_entry(ce, &ocs->entries, node) {
 686                 ret = __of_changeset_entry_apply(ce);
 687                 if (ret) {
 688                         pr_err("%s: Error applying changeset (%d)\n", __func__, ret);
 689                         list_for_each_entry_continue_reverse(ce, &ocs->entries, node)
 690                                 __of_changeset_entry_revert(ce);
 691                         return ret;
 692                 }
 693         }
 694         pr_debug("of_changeset: applied, emitting notifiers.\n");
 695
 696         /* drop the global lock while emitting notifiers */
 697         mutex_unlock(&of_mutex);
 698         list_for_each_entry(ce, &ocs->entries, node)
 699                 __of_changeset_entry_notify(ce, 0);
 700         mutex_lock(&of_mutex);
 701         pr_debug("of_changeset: notifiers sent.\n");
 702
 703         return 0;
 704 }
 705
 706 /**
 707  * of_changeset_revert - Reverts an applied changeset
 708  *
 709  * @ocs:        changeset pointer
 710  *
 711  * Reverts a changeset returning the state of the tree to what it
 712  * was before the application.
 713  * Any side-effects like creation/destruction of devices and
 714  * removal of sysfs properties and directories are applied.
 715  * Returns 0 on success, a negative error value in case of an error.
 716  */
 717 int of_changeset_revert(struct of_changeset *ocs)
 718 {
 719         struct of_changeset_entry *ce;
 720         int ret;
 721
 722         pr_debug("of_changeset: reverting...\n");
 723         list_for_each_entry_reverse(ce, &ocs->entries, node) {
 724                 ret = __of_changeset_entry_revert(ce);
 725                 if (ret) {
 726                         pr_err("%s: Error reverting changeset (%d)\n", __func__, ret);
 727                         list_for_each_entry_continue(ce, &ocs->entries, node)
 728                                 __of_changeset_entry_apply(ce);
 729                         return ret;
 730                 }
 731         }
 732         pr_debug("of_changeset: reverted, emitting notifiers.\n");
 733
 734         /* drop the global lock while emitting notifiers */
 735         mutex_unlock(&of_mutex);
 736         list_for_each_entry_reverse(ce, &ocs->entries, node)
 737                 __of_changeset_entry_notify(ce, 1);
 738         mutex_lock(&of_mutex);
 739         pr_debug("of_changeset: notifiers sent.\n");
 740
 741         return 0;
 742 }
 743
 744 /**
 745  * of_changeset_action - Perform a changeset action
 746  *
 747  * @ocs:        changeset pointer
 748  * @action:     action to perform
 749  * @np:         Pointer to device node
 750  * @prop:       Pointer to property
 751  *
 752  * On action being one of:
 753  * + OF_RECONFIG_ATTACH_NODE
 754  * + OF_RECONFIG_DETACH_NODE,
 755  * + OF_RECONFIG_ADD_PROPERTY
 756  * + OF_RECONFIG_REMOVE_PROPERTY,
 757  * + OF_RECONFIG_UPDATE_PROPERTY
 758  * Returns 0 on success, a negative error value in case of an error.
 759  */
 760 int of_changeset_action(struct of_changeset *ocs, unsigned long action,
 761                 struct device_node *np, struct property *prop)
 762 {
 763         struct of_changeset_entry *ce;
 764
 765         ce = kzalloc(sizeof(*ce), GFP_KERNEL);
 766         if (!ce) {
 767                 pr_err("%s: Failed to allocate\n", __func__);
 768                 return -ENOMEM;
 769         }
 770         /* get a reference to the node */
 771         ce->action = action;
 772         ce->np = of_node_get(np);
 773         ce->prop = prop;
 774
 775         if (action == OF_RECONFIG_UPDATE_PROPERTY && prop)
 776                 ce->old_prop = of_find_property(np, prop->name, NULL);
 777
 778         /* add it to the list */
 779         list_add_tail(&ce->node, &ocs->entries);
 780         return 0;
 781 }