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