drivers/of/dynamic.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Support for dynamic device trees.
   4  *
   5  * On some platforms, the device tree can be manipulated at runtime.
   6  * The routines in this section support adding, removing and changing
   7  * device tree nodes.
   8  */
   9
  10 #define pr_fmt(fmt)     "OF: " fmt
  11
  12 #include <linux/of.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/slab.h>
  15 #include <linux/string.h>
  16 #include <linux/proc_fs.h>
  17
  18 #include "of_private.h"
  19
  20 static struct device_node *kobj_to_device_node(struct kobject *kobj)
  21 {
  22         return container_of(kobj, struct device_node, kobj);
  23 }
  24
  25 /**
  26  * of_node_get() - Increment refcount of a node
  27  * @node:       Node to inc refcount, NULL is supported to simplify writing of
  28  *              callers
  29  *
  30  * Returns node.
  31  */
  32 struct device_node *of_node_get(struct device_node *node)
  33 {
  34         if (node)
  35                 kobject_get(&node->kobj);
  36         return node;
  37 }
  38 EXPORT_SYMBOL(of_node_get);
  39
  40 /**
  41  * of_node_put() - Decrement refcount of a node
  42  * @node:       Node to dec refcount, NULL is supported to simplify writing of
  43  *              callers
  44  */
  45 void of_node_put(struct device_node *node)
  46 {
  47         if (node)
  48                 kobject_put(&node->kobj);
  49 }
  50 EXPORT_SYMBOL(of_node_put);
  51
  52 static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain);
  53
  54 int of_reconfig_notifier_register(struct notifier_block *nb)
  55 {
  56         return blocking_notifier_chain_register(&of_reconfig_chain, nb);
  57 }
  58 EXPORT_SYMBOL_GPL(of_reconfig_notifier_register);
  59
  60 int of_reconfig_notifier_unregister(struct notifier_block *nb)
  61 {
  62         return blocking_notifier_chain_unregister(&of_reconfig_chain, nb);
  63 }
  64 EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister);
  65
  66 #ifdef DEBUG
  67 const char *action_names[] = {
  68         [OF_RECONFIG_ATTACH_NODE] = "ATTACH_NODE",
  69         [OF_RECONFIG_DETACH_NODE] = "DETACH_NODE",
  70         [OF_RECONFIG_ADD_PROPERTY] = "ADD_PROPERTY",
  71         [OF_RECONFIG_REMOVE_PROPERTY] = "REMOVE_PROPERTY",
  72         [OF_RECONFIG_UPDATE_PROPERTY] = "UPDATE_PROPERTY",
  73 };
  74 #endif
  75
  76 int of_reconfig_notify(unsigned long action, struct of_reconfig_data *p)
  77 {
  78         int rc;
  79 #ifdef DEBUG
  80         struct of_reconfig_data *pr = p;
  81
  82         switch (action) {
  83         case OF_RECONFIG_ATTACH_NODE:
  84         case OF_RECONFIG_DETACH_NODE:
  85                 pr_debug("notify %-15s %pOF\n", action_names[action],
  86                         pr->dn);
  87                 break;
  88         case OF_RECONFIG_ADD_PROPERTY:
  89         case OF_RECONFIG_REMOVE_PROPERTY:
  90         case OF_RECONFIG_UPDATE_PROPERTY:
  91                 pr_debug("notify %-15s %pOF:%s\n", action_names[action],
  92                         pr->dn, pr->prop->name);
  93                 break;
  94
  95         }
  96 #endif
  97         rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p);
  98         return notifier_to_errno(rc);
  99 }
 100
 101 /*
 102  * of_reconfig_get_state_change()       - Returns new state of device
 103  * @action      - action of the of notifier
 104  * @arg         - argument of the of notifier
 105  *
 106  * Returns the new state of a device based on the notifier used.
 107  * Returns 0 on device going from enabled to disabled, 1 on device
 108  * going from disabled to enabled and -1 on no change.
 109  */
 110 int of_reconfig_get_state_change(unsigned long action, struct of_reconfig_data *pr)
 111 {
 112         struct property *prop, *old_prop = NULL;
 113         int is_status, status_state, old_status_state, prev_state, new_state;
 114
 115         /* figure out if a device should be created or destroyed */
 116         switch (action) {
 117         case OF_RECONFIG_ATTACH_NODE:
 118         case OF_RECONFIG_DETACH_NODE:
 119                 prop = of_find_property(pr->dn, "status", NULL);
 120                 break;
 121         case OF_RECONFIG_ADD_PROPERTY:
 122         case OF_RECONFIG_REMOVE_PROPERTY:
 123                 prop = pr->prop;
 124                 break;
 125         case OF_RECONFIG_UPDATE_PROPERTY:
 126                 prop = pr->prop;
 127                 old_prop = pr->old_prop;
 128                 break;
 129         default:
 130                 return OF_RECONFIG_NO_CHANGE;
 131         }
 132
 133         is_status = 0;
 134         status_state = -1;
 135         old_status_state = -1;
 136         prev_state = -1;
 137         new_state = -1;
 138
 139         if (prop && !strcmp(prop->name, "status")) {
 140                 is_status = 1;
 141                 status_state = !strcmp(prop->value, "okay") ||
 142                                !strcmp(prop->value, "ok");
 143                 if (old_prop)
 144                         old_status_state = !strcmp(old_prop->value, "okay") ||
 145                                            !strcmp(old_prop->value, "ok");
 146         }
 147
 148         switch (action) {
 149         case OF_RECONFIG_ATTACH_NODE:
 150                 prev_state = 0;
 151                 /* -1 & 0 status either missing or okay */
 152                 new_state = status_state != 0;
 153                 break;
 154         case OF_RECONFIG_DETACH_NODE:
 155                 /* -1 & 0 status either missing or okay */
 156                 prev_state = status_state != 0;
 157                 new_state = 0;
 158                 break;
 159         case OF_RECONFIG_ADD_PROPERTY:
 160                 if (is_status) {
 161                         /* no status property -> enabled (legacy) */
 162                         prev_state = 1;
 163                         new_state = status_state;
 164                 }
 165                 break;
 166         case OF_RECONFIG_REMOVE_PROPERTY:
 167                 if (is_status) {
 168                         prev_state = status_state;
 169                         /* no status property -> enabled (legacy) */
 170                         new_state = 1;
 171                 }
 172                 break;
 173         case OF_RECONFIG_UPDATE_PROPERTY:
 174                 if (is_status) {
 175                         prev_state = old_status_state != 0;
 176                         new_state = status_state != 0;
 177                 }
 178                 break;
 179         }
 180
 181         if (prev_state == new_state)
 182                 return OF_RECONFIG_NO_CHANGE;
 183
 184         return new_state ? OF_RECONFIG_CHANGE_ADD : OF_RECONFIG_CHANGE_REMOVE;
 185 }
 186 EXPORT_SYMBOL_GPL(of_reconfig_get_state_change);
 187
 188 int of_property_notify(int action, struct device_node *np,
 189                        struct property *prop, struct property *oldprop)
 190 {
 191         struct of_reconfig_data pr;
 192
 193         /* only call notifiers if the node is attached */
 194         if (!of_node_is_attached(np))
 195                 return 0;
 196
 197         pr.dn = np;
 198         pr.prop = prop;
 199         pr.old_prop = oldprop;
 200         return of_reconfig_notify(action, &pr);
 201 }
 202
 203 static void __of_attach_node(struct device_node *np)
 204 {
 205         const __be32 *phandle;
 206         int sz;
 207
 208         np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
 209         np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
 210
 211         phandle = __of_get_property(np, "phandle", &sz);
 212         if (!phandle)
 213                 phandle = __of_get_property(np, "linux,phandle", &sz);
 214         if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
 215                 phandle = __of_get_property(np, "ibm,phandle", &sz);
 216         np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;
 217
 218         np->child = NULL;
 219         np->sibling = np->parent->child;
 220         np->parent->child = np;
 221         of_node_clear_flag(np, OF_DETACHED);
 222 }
 223
 224 /**
 225  * of_attach_node() - Plug a device node into the tree and global list.
 226  */
 227 int of_attach_node(struct device_node *np)
 228 {
 229         struct of_reconfig_data rd;
 230         unsigned long flags;
 231
 232         memset(&rd, 0, sizeof(rd));
 233         rd.dn = np;
 234
 235         mutex_lock(&of_mutex);
 236         raw_spin_lock_irqsave(&devtree_lock, flags);
 237         __of_attach_node(np);
 238         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 239
 240         __of_attach_node_sysfs(np);
 241         mutex_unlock(&of_mutex);
 242
 243         of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, &rd);
 244
 245         return 0;
 246 }
 247
 248 void __of_detach_node(struct device_node *np)
 249 {
 250         struct device_node *parent;
 251
 252         if (WARN_ON(of_node_check_flag(np, OF_DETACHED)))
 253                 return;
 254
 255         parent = np->parent;
 256         if (WARN_ON(!parent))
 257                 return;
 258
 259         if (parent->child == np)
 260                 parent->child = np->sibling;
 261         else {
 262                 struct device_node *prevsib;
 263                 for (prevsib = np->parent->child;
 264                      prevsib->sibling != np;
 265                      prevsib = prevsib->sibling)
 266                         ;
 267                 prevsib->sibling = np->sibling;
 268         }
 269
 270         of_node_set_flag(np, OF_DETACHED);
 271 }
 272
 273 /**
 274  * of_detach_node() - "Unplug" a node from the device tree.
 275  *
 276  * The caller must hold a reference to the node.  The memory associated with
 277  * the node is not freed until its refcount goes to zero.
 278  */
 279 int of_detach_node(struct device_node *np)
 280 {
 281         struct of_reconfig_data rd;
 282         unsigned long flags;
 283         int rc = 0;
 284
 285         memset(&rd, 0, sizeof(rd));
 286         rd.dn = np;
 287
 288         mutex_lock(&of_mutex);
 289         raw_spin_lock_irqsave(&devtree_lock, flags);
 290         __of_detach_node(np);
 291         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 292
 293         __of_detach_node_sysfs(np);
 294         mutex_unlock(&of_mutex);
 295
 296         of_reconfig_notify(OF_RECONFIG_DETACH_NODE, &rd);
 297
 298         return rc;
 299 }
 300 EXPORT_SYMBOL_GPL(of_detach_node);
 301
 302 static void property_list_free(struct property *prop_list)
 303 {
 304         struct property *prop, *next;
 305
 306         for (prop = prop_list; prop != NULL; prop = next) {
 307                 next = prop->next;
 308                 kfree(prop->name);
 309                 kfree(prop->value);
 310                 kfree(prop);
 311         }
 312 }
 313
 314 /**
 315  * of_node_release() - release a dynamically allocated node
 316  * @kref: kref element of the node to be released
 317  *
 318  * In of_node_put() this function is passed to kref_put() as the destructor.
 319  */
 320 void of_node_release(struct kobject *kobj)
 321 {
 322         struct device_node *node = kobj_to_device_node(kobj);
 323
 324         /* We should never be releasing nodes that haven't been detached. */
 325         if (!of_node_check_flag(node, OF_DETACHED)) {
 326                 pr_err("ERROR: Bad of_node_put() on %pOF\n", node);
 327                 dump_stack();
 328                 return;
 329         }
 330         if (!of_node_check_flag(node, OF_DYNAMIC))
 331                 return;
 332
 333         property_list_free(node->properties);
 334         property_list_free(node->deadprops);
 335
 336         kfree(node->full_name);
 337         kfree(node->data);
 338         kfree(node);
 339 }
 340
 341 /**
 342  * __of_prop_dup - Copy a property dynamically.
 343  * @prop:       Property to copy
 344  * @allocflags: Allocation flags (typically pass GFP_KERNEL)
 345  *
 346  * Copy a property by dynamically allocating the memory of both the
 347  * property structure and the property name & contents. The property's
 348  * flags have the OF_DYNAMIC bit set so that we can differentiate between
 349  * dynamically allocated properties and not.
 350  * Returns the newly allocated property or NULL on out of memory error.
 351  */
 352 struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
 353 {
 354         struct property *new;
 355
 356         new = kzalloc(sizeof(*new), allocflags);
 357         if (!new)
 358                 return NULL;
 359
 360         /*
 361          * NOTE: There is no check for zero length value.
 362          * In case of a boolean property, this will allocate a value
 363          * of zero bytes. We do this to work around the use
 364          * of of_get_property() calls on boolean values.
 365          */
 366         new->name = kstrdup(prop->name, allocflags);
 367         new->value = kmemdup(prop->value, prop->length, allocflags);
 368         new->length = prop->length;
 369         if (!new->name || !new->value)
 370                 goto err_free;
 371
 372         /* mark the property as dynamic */
 373         of_property_set_flag(new, OF_DYNAMIC);
 374
 375         return new;
 376
 377  err_free:
 378         kfree(new->name);
 379         kfree(new->value);
 380         kfree(new);
 381         return NULL;
 382 }
 383
 384 /**
 385  * __of_node_dup() - Duplicate or create an empty device node dynamically.
 386  * @np:         if not NULL, contains properties to be duplicated in new node
 387  * @full_name:  string value to be duplicated into new node's full_name field
 388  *
 389  * Create a device tree node, optionally duplicating the properties of
 390  * another node.  The node data are dynamically allocated and all the node
 391  * flags have the OF_DYNAMIC & OF_DETACHED bits set.
 392  *
 393  * Returns the newly allocated node or NULL on out of memory error.
 394  */
 395 struct device_node *__of_node_dup(const struct device_node *np,
 396                                   const char *full_name)
 397 {
 398         struct device_node *node;
 399
 400         node = kzalloc(sizeof(*node), GFP_KERNEL);
 401         if (!node)
 402                 return NULL;
 403         node->full_name = kstrdup(full_name, GFP_KERNEL);
 404         if (!node->full_name) {
 405                 kfree(node);
 406                 return NULL;
 407         }
 408
 409         of_node_set_flag(node, OF_DYNAMIC);
 410         of_node_set_flag(node, OF_DETACHED);
 411         of_node_init(node);
 412
 413         /* Iterate over and duplicate all properties */
 414         if (np) {
 415                 struct property *pp, *new_pp;
 416                 for_each_property_of_node(np, pp) {
 417                         new_pp = __of_prop_dup(pp, GFP_KERNEL);
 418                         if (!new_pp)
 419                                 goto err_prop;
 420                         if (__of_add_property(node, new_pp)) {
 421                                 kfree(new_pp->name);
 422                                 kfree(new_pp->value);
 423                                 kfree(new_pp);
 424                                 goto err_prop;
 425                         }
 426                 }
 427         }
 428         return node;
 429
 430  err_prop:
 431         of_node_put(node); /* Frees the node and properties */
 432         return NULL;
 433 }
 434
 435 static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
 436 {
 437         of_node_put(ce->np);
 438         list_del(&ce->node);
 439         kfree(ce);
 440 }
 441
 442 #ifdef DEBUG
 443 static void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 444 {
 445         switch (ce->action) {
 446         case OF_RECONFIG_ADD_PROPERTY:
 447         case OF_RECONFIG_REMOVE_PROPERTY:
 448         case OF_RECONFIG_UPDATE_PROPERTY:
 449                 pr_debug("cset<%p> %-15s %pOF/%s\n", ce, action_names[ce->action],
 450                         ce->np, ce->prop->name);
 451                 break;
 452         case OF_RECONFIG_ATTACH_NODE:
 453         case OF_RECONFIG_DETACH_NODE:
 454                 pr_debug("cset<%p> %-15s %pOF\n", ce, action_names[ce->action],
 455                         ce->np);
 456                 break;
 457         }
 458 }
 459 #else
 460 static inline void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 461 {
 462         /* empty */
 463 }
 464 #endif
 465
 466 static void __of_changeset_entry_invert(struct of_changeset_entry *ce,
 467                                           struct of_changeset_entry *rce)
 468 {
 469         memcpy(rce, ce, sizeof(*rce));
 470
 471         switch (ce->action) {
 472         case OF_RECONFIG_ATTACH_NODE:
 473                 rce->action = OF_RECONFIG_DETACH_NODE;
 474                 break;
 475         case OF_RECONFIG_DETACH_NODE:
 476                 rce->action = OF_RECONFIG_ATTACH_NODE;
 477                 break;
 478         case OF_RECONFIG_ADD_PROPERTY:
 479                 rce->action = OF_RECONFIG_REMOVE_PROPERTY;
 480                 break;
 481         case OF_RECONFIG_REMOVE_PROPERTY:
 482                 rce->action = OF_RECONFIG_ADD_PROPERTY;
 483                 break;
 484         case OF_RECONFIG_UPDATE_PROPERTY:
 485                 rce->old_prop = ce->prop;
 486                 rce->prop = ce->old_prop;
 487                 /* update was used but original property did not exist */
 488                 if (!rce->prop) {
 489                         rce->action = OF_RECONFIG_REMOVE_PROPERTY;
 490                         rce->prop = ce->prop;
 491                 }
 492                 break;
 493         }
 494 }
 495
 496 static int __of_changeset_entry_notify(struct of_changeset_entry *ce,
 497                 bool revert)
 498 {
 499         struct of_reconfig_data rd;
 500         struct of_changeset_entry ce_inverted;
 501         int ret = 0;
 502
 503         if (revert) {
 504                 __of_changeset_entry_invert(ce, &ce_inverted);
 505                 ce = &ce_inverted;
 506         }
 507
 508         switch (ce->action) {
 509         case OF_RECONFIG_ATTACH_NODE:
 510         case OF_RECONFIG_DETACH_NODE:
 511                 memset(&rd, 0, sizeof(rd));
 512                 rd.dn = ce->np;
 513                 ret = of_reconfig_notify(ce->action, &rd);
 514                 break;
 515         case OF_RECONFIG_ADD_PROPERTY:
 516         case OF_RECONFIG_REMOVE_PROPERTY:
 517         case OF_RECONFIG_UPDATE_PROPERTY:
 518                 ret = of_property_notify(ce->action, ce->np, ce->prop, ce->old_prop);
 519                 break;
 520         default:
 521                 pr_err("invalid devicetree changeset action: %i\n",
 522                         (int)ce->action);
 523                 ret = -EINVAL;
 524         }
 525
 526         if (ret)
 527                 pr_err("changeset notifier error @%pOF\n", ce->np);
 528         return ret;
 529 }
 530
 531 static int __of_changeset_entry_apply(struct of_changeset_entry *ce)
 532 {
 533         struct property *old_prop, **propp;
 534         unsigned long flags;
 535         int ret = 0;
 536
 537         __of_changeset_entry_dump(ce);
 538
 539         raw_spin_lock_irqsave(&devtree_lock, flags);
 540         switch (ce->action) {
 541         case OF_RECONFIG_ATTACH_NODE:
 542                 __of_attach_node(ce->np);
 543                 break;
 544         case OF_RECONFIG_DETACH_NODE:
 545                 __of_detach_node(ce->np);
 546                 break;
 547         case OF_RECONFIG_ADD_PROPERTY:
 548                 /* If the property is in deadprops then it must be removed */
 549                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 550                         if (*propp == ce->prop) {
 551                                 *propp = ce->prop->next;
 552                                 ce->prop->next = NULL;
 553                                 break;
 554                         }
 555                 }
 556
 557                 ret = __of_add_property(ce->np, ce->prop);
 558                 if (ret) {
 559                         pr_err("changeset: add_property failed @%pOF/%s\n",
 560                                 ce->np,
 561                                 ce->prop->name);
 562                         break;
 563                 }
 564                 break;
 565         case OF_RECONFIG_REMOVE_PROPERTY:
 566                 ret = __of_remove_property(ce->np, ce->prop);
 567                 if (ret) {
 568                         pr_err("changeset: remove_property failed @%pOF/%s\n",
 569                                 ce->np,
 570                                 ce->prop->name);
 571                         break;
 572                 }
 573                 break;
 574
 575         case OF_RECONFIG_UPDATE_PROPERTY:
 576                 /* If the property is in deadprops then it must be removed */
 577                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 578                         if (*propp == ce->prop) {
 579                                 *propp = ce->prop->next;
 580                                 ce->prop->next = NULL;
 581                                 break;
 582                         }
 583                 }
 584
 585                 ret = __of_update_property(ce->np, ce->prop, &old_prop);
 586                 if (ret) {
 587                         pr_err("changeset: update_property failed @%pOF/%s\n",
 588                                 ce->np,
 589                                 ce->prop->name);
 590                         break;
 591                 }
 592                 break;
 593         default:
 594                 ret = -EINVAL;
 595         }
 596         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 597
 598         if (ret)
 599                 return ret;
 600
 601         switch (ce->action) {
 602         case OF_RECONFIG_ATTACH_NODE:
 603                 __of_attach_node_sysfs(ce->np);
 604                 break;
 605         case OF_RECONFIG_DETACH_NODE:
 606                 __of_detach_node_sysfs(ce->np);
 607                 break;
 608         case OF_RECONFIG_ADD_PROPERTY:
 609                 /* ignore duplicate names */
 610                 __of_add_property_sysfs(ce->np, ce->prop);
 611                 break;
 612         case OF_RECONFIG_REMOVE_PROPERTY:
 613                 __of_remove_property_sysfs(ce->np, ce->prop);
 614                 break;
 615         case OF_RECONFIG_UPDATE_PROPERTY:
 616                 __of_update_property_sysfs(ce->np, ce->prop, ce->old_prop);
 617                 break;
 618         }
 619
 620         return 0;
 621 }
 622
 623 static inline int __of_changeset_entry_revert(struct of_changeset_entry *ce)
 624 {
 625         struct of_changeset_entry ce_inverted;
 626
 627         __of_changeset_entry_invert(ce, &ce_inverted);
 628         return __of_changeset_entry_apply(&ce_inverted);
 629 }
 630
 631 /**
 632  * of_changeset_init - Initialize a changeset for use
 633  *
 634  * @ocs:        changeset pointer
 635  *
 636  * Initialize a changeset structure
 637  */
 638 void of_changeset_init(struct of_changeset *ocs)
 639 {
 640         memset(ocs, 0, sizeof(*ocs));
 641         INIT_LIST_HEAD(&ocs->entries);
 642 }
 643 EXPORT_SYMBOL_GPL(of_changeset_init);
 644
 645 /**
 646  * of_changeset_destroy - Destroy a changeset
 647  *
 648  * @ocs:        changeset pointer
 649  *
 650  * Destroys a changeset. Note that if a changeset is applied,
 651  * its changes to the tree cannot be reverted.
 652  */
 653 void of_changeset_destroy(struct of_changeset *ocs)
 654 {
 655         struct of_changeset_entry *ce, *cen;
 656
 657         list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node)
 658                 __of_changeset_entry_destroy(ce);
 659 }
 660 EXPORT_SYMBOL_GPL(of_changeset_destroy);
 661
 662 /*
 663  * Apply the changeset entries in @ocs.
 664  * If apply fails, an attempt is made to revert the entries that were
 665  * successfully applied.
 666  *
 667  * If multiple revert errors occur then only the final revert error is reported.
 668  *
 669  * Returns 0 on success, a negative error value in case of an error.
 670  * If a revert error occurs, it is returned in *ret_revert.
 671  */
 672 int __of_changeset_apply_entries(struct of_changeset *ocs, int *ret_revert)
 673 {
 674         struct of_changeset_entry *ce;
 675         int ret, ret_tmp;
 676
 677         pr_debug("changeset: applying...\n");
 678         list_for_each_entry(ce, &ocs->entries, node) {
 679                 ret = __of_changeset_entry_apply(ce);
 680                 if (ret) {
 681                         pr_err("Error applying changeset (%d)\n", ret);
 682                         list_for_each_entry_continue_reverse(ce, &ocs->entries,
 683                                                              node) {
 684                                 ret_tmp = __of_changeset_entry_revert(ce);
 685                                 if (ret_tmp)
 686                                         *ret_revert = ret_tmp;
 687                         }
 688                         return ret;
 689                 }
 690         }
 691
 692         return 0;
 693 }
 694
 695 /*
 696  * Returns 0 on success, a negative error value in case of an error.
 697  *
 698  * If multiple changeset entry notification errors occur then only the
 699  * final notification error is reported.
 700  */
 701 int __of_changeset_apply_notify(struct of_changeset *ocs)
 702 {
 703         struct of_changeset_entry *ce;
 704         int ret = 0, ret_tmp;
 705
 706         pr_debug("changeset: emitting notifiers.\n");
 707
 708         /* drop the global lock while emitting notifiers */
 709         mutex_unlock(&of_mutex);
 710         list_for_each_entry(ce, &ocs->entries, node) {
 711                 ret_tmp = __of_changeset_entry_notify(ce, 0);
 712                 if (ret_tmp)
 713                         ret = ret_tmp;
 714         }
 715         mutex_lock(&of_mutex);
 716         pr_debug("changeset: notifiers sent.\n");
 717
 718         return ret;
 719 }
 720
 721 /*
 722  * Returns 0 on success, a negative error value in case of an error.
 723  *
 724  * If a changeset entry apply fails, an attempt is made to revert any
 725  * previous entries in the changeset.  If any of the reverts fails,
 726  * that failure is not reported.  Thus the state of the device tree
 727  * is unknown if an apply error occurs.
 728  */
 729 static int __of_changeset_apply(struct of_changeset *ocs)
 730 {
 731         int ret, ret_revert = 0;
 732
 733         ret = __of_changeset_apply_entries(ocs, &ret_revert);
 734         if (!ret)
 735                 ret = __of_changeset_apply_notify(ocs);
 736
 737         return ret;
 738 }
 739
 740 /**
 741  * of_changeset_apply - Applies a changeset
 742  *
 743  * @ocs:        changeset pointer
 744  *
 745  * Applies a changeset to the live tree.
 746  * Any side-effects of live tree state changes are applied here on
 747  * success, like creation/destruction of devices and side-effects
 748  * like creation of sysfs properties and directories.
 749  * Returns 0 on success, a negative error value in case of an error.
 750  * On error the partially applied effects are reverted.
 751  */
 752 int of_changeset_apply(struct of_changeset *ocs)
 753 {
 754         int ret;
 755
 756         mutex_lock(&of_mutex);
 757         ret = __of_changeset_apply(ocs);
 758         mutex_unlock(&of_mutex);
 759
 760         return ret;
 761 }
 762 EXPORT_SYMBOL_GPL(of_changeset_apply);
 763
 764 /*
 765  * Revert the changeset entries in @ocs.
 766  * If revert fails, an attempt is made to re-apply the entries that were
 767  * successfully removed.
 768  *
 769  * If multiple re-apply errors occur then only the final apply error is
 770  * reported.
 771  *
 772  * Returns 0 on success, a negative error value in case of an error.
 773  * If an apply error occurs, it is returned in *ret_apply.
 774  */
 775 int __of_changeset_revert_entries(struct of_changeset *ocs, int *ret_apply)
 776 {
 777         struct of_changeset_entry *ce;
 778         int ret, ret_tmp;
 779
 780         pr_debug("changeset: reverting...\n");
 781         list_for_each_entry_reverse(ce, &ocs->entries, node) {
 782                 ret = __of_changeset_entry_revert(ce);
 783                 if (ret) {
 784                         pr_err("Error reverting changeset (%d)\n", ret);
 785                         list_for_each_entry_continue(ce, &ocs->entries, node) {
 786                                 ret_tmp = __of_changeset_entry_apply(ce);
 787                                 if (ret_tmp)
 788                                         *ret_apply = ret_tmp;
 789                         }
 790                         return ret;
 791                 }
 792         }
 793
 794         return 0;
 795 }
 796
 797 /*
 798  * If multiple changeset entry notification errors occur then only the
 799  * final notification error is reported.
 800  */
 801 int __of_changeset_revert_notify(struct of_changeset *ocs)
 802 {
 803         struct of_changeset_entry *ce;
 804         int ret = 0, ret_tmp;
 805
 806         pr_debug("changeset: emitting notifiers.\n");
 807
 808         /* drop the global lock while emitting notifiers */
 809         mutex_unlock(&of_mutex);
 810         list_for_each_entry_reverse(ce, &ocs->entries, node) {
 811                 ret_tmp = __of_changeset_entry_notify(ce, 1);
 812                 if (ret_tmp)
 813                         ret = ret_tmp;
 814         }
 815         mutex_lock(&of_mutex);
 816         pr_debug("changeset: notifiers sent.\n");
 817
 818         return ret;
 819 }
 820
 821 static int __of_changeset_revert(struct of_changeset *ocs)
 822 {
 823         int ret, ret_reply;
 824
 825         ret_reply = 0;
 826         ret = __of_changeset_revert_entries(ocs, &ret_reply);
 827
 828         if (!ret)
 829                 ret = __of_changeset_revert_notify(ocs);
 830
 831         return ret;
 832 }
 833
 834 /**
 835  * of_changeset_revert - Reverts an applied changeset
 836  *
 837  * @ocs:        changeset pointer
 838  *
 839  * Reverts a changeset returning the state of the tree to what it
 840  * was before the application.
 841  * Any side-effects like creation/destruction of devices and
 842  * removal of sysfs properties and directories are applied.
 843  * Returns 0 on success, a negative error value in case of an error.
 844  */
 845 int of_changeset_revert(struct of_changeset *ocs)
 846 {
 847         int ret;
 848
 849         mutex_lock(&of_mutex);
 850         ret = __of_changeset_revert(ocs);
 851         mutex_unlock(&of_mutex);
 852
 853         return ret;
 854 }
 855 EXPORT_SYMBOL_GPL(of_changeset_revert);
 856
 857 /**
 858  * of_changeset_action - Add an action to the tail of the changeset list
 859  *
 860  * @ocs:        changeset pointer
 861  * @action:     action to perform
 862  * @np:         Pointer to device node
 863  * @prop:       Pointer to property
 864  *
 865  * On action being one of:
 866  * + OF_RECONFIG_ATTACH_NODE
 867  * + OF_RECONFIG_DETACH_NODE,
 868  * + OF_RECONFIG_ADD_PROPERTY
 869  * + OF_RECONFIG_REMOVE_PROPERTY,
 870  * + OF_RECONFIG_UPDATE_PROPERTY
 871  * Returns 0 on success, a negative error value in case of an error.
 872  */
 873 int of_changeset_action(struct of_changeset *ocs, unsigned long action,
 874                 struct device_node *np, struct property *prop)
 875 {
 876         struct of_changeset_entry *ce;
 877
 878         ce = kzalloc(sizeof(*ce), GFP_KERNEL);
 879         if (!ce)
 880                 return -ENOMEM;
 881
 882         /* get a reference to the node */
 883         ce->action = action;
 884         ce->np = of_node_get(np);
 885         ce->prop = prop;
 886
 887         if (action == OF_RECONFIG_UPDATE_PROPERTY && prop)
 888                 ce->old_prop = of_find_property(np, prop->name, NULL);
 889
 890         /* add it to the list */
 891         list_add_tail(&ce->node, &ocs->entries);
 892         return 0;
 893 }
 894 EXPORT_SYMBOL_GPL(of_changeset_action);