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  * Return: The node with refcount incremented.
  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  *
 108  * Return: 0 on device going from enabled to disabled, 1 on device
 109  * going from disabled to enabled and -1 on no change.
 110  */
 111 int of_reconfig_get_state_change(unsigned long action, struct of_reconfig_data *pr)
 112 {
 113         struct property *prop, *old_prop = NULL;
 114         int is_status, status_state, old_status_state, prev_state, new_state;
 115
 116         /* figure out if a device should be created or destroyed */
 117         switch (action) {
 118         case OF_RECONFIG_ATTACH_NODE:
 119         case OF_RECONFIG_DETACH_NODE:
 120                 prop = of_find_property(pr->dn, "status", NULL);
 121                 break;
 122         case OF_RECONFIG_ADD_PROPERTY:
 123         case OF_RECONFIG_REMOVE_PROPERTY:
 124                 prop = pr->prop;
 125                 break;
 126         case OF_RECONFIG_UPDATE_PROPERTY:
 127                 prop = pr->prop;
 128                 old_prop = pr->old_prop;
 129                 break;
 130         default:
 131                 return OF_RECONFIG_NO_CHANGE;
 132         }
 133
 134         is_status = 0;
 135         status_state = -1;
 136         old_status_state = -1;
 137         prev_state = -1;
 138         new_state = -1;
 139
 140         if (prop && !strcmp(prop->name, "status")) {
 141                 is_status = 1;
 142                 status_state = !strcmp(prop->value, "okay") ||
 143                                !strcmp(prop->value, "ok");
 144                 if (old_prop)
 145                         old_status_state = !strcmp(old_prop->value, "okay") ||
 146                                            !strcmp(old_prop->value, "ok");
 147         }
 148
 149         switch (action) {
 150         case OF_RECONFIG_ATTACH_NODE:
 151                 prev_state = 0;
 152                 /* -1 & 0 status either missing or okay */
 153                 new_state = status_state != 0;
 154                 break;
 155         case OF_RECONFIG_DETACH_NODE:
 156                 /* -1 & 0 status either missing or okay */
 157                 prev_state = status_state != 0;
 158                 new_state = 0;
 159                 break;
 160         case OF_RECONFIG_ADD_PROPERTY:
 161                 if (is_status) {
 162                         /* no status property -> enabled (legacy) */
 163                         prev_state = 1;
 164                         new_state = status_state;
 165                 }
 166                 break;
 167         case OF_RECONFIG_REMOVE_PROPERTY:
 168                 if (is_status) {
 169                         prev_state = status_state;
 170                         /* no status property -> enabled (legacy) */
 171                         new_state = 1;
 172                 }
 173                 break;
 174         case OF_RECONFIG_UPDATE_PROPERTY:
 175                 if (is_status) {
 176                         prev_state = old_status_state != 0;
 177                         new_state = status_state != 0;
 178                 }
 179                 break;
 180         }
 181
 182         if (prev_state == new_state)
 183                 return OF_RECONFIG_NO_CHANGE;
 184
 185         return new_state ? OF_RECONFIG_CHANGE_ADD : OF_RECONFIG_CHANGE_REMOVE;
 186 }
 187 EXPORT_SYMBOL_GPL(of_reconfig_get_state_change);
 188
 189 int of_property_notify(int action, struct device_node *np,
 190                        struct property *prop, struct property *oldprop)
 191 {
 192         struct of_reconfig_data pr;
 193
 194         /* only call notifiers if the node is attached */
 195         if (!of_node_is_attached(np))
 196                 return 0;
 197
 198         pr.dn = np;
 199         pr.prop = prop;
 200         pr.old_prop = oldprop;
 201         return of_reconfig_notify(action, &pr);
 202 }
 203
 204 static void __of_attach_node(struct device_node *np)
 205 {
 206         const __be32 *phandle;
 207         int sz;
 208
 209         if (!of_node_check_flag(np, OF_OVERLAY)) {
 210                 np->name = __of_get_property(np, "name", NULL);
 211                 if (!np->name)
 212                         np->name = "<NULL>";
 213
 214                 phandle = __of_get_property(np, "phandle", &sz);
 215                 if (!phandle)
 216                         phandle = __of_get_property(np, "linux,phandle", &sz);
 217                 if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
 218                         phandle = __of_get_property(np, "ibm,phandle", &sz);
 219                 if (phandle && (sz >= 4))
 220                         np->phandle = be32_to_cpup(phandle);
 221                 else
 222                         np->phandle = 0;
 223         }
 224
 225         np->child = NULL;
 226         np->sibling = np->parent->child;
 227         np->parent->child = np;
 228         of_node_clear_flag(np, OF_DETACHED);
 229 }
 230
 231 /**
 232  * of_attach_node() - Plug a device node into the tree and global list.
 233  * @np:         Pointer to the caller's Device Node
 234  */
 235 int of_attach_node(struct device_node *np)
 236 {
 237         struct of_reconfig_data rd;
 238         unsigned long flags;
 239
 240         memset(&rd, 0, sizeof(rd));
 241         rd.dn = np;
 242
 243         mutex_lock(&of_mutex);
 244         raw_spin_lock_irqsave(&devtree_lock, flags);
 245         __of_attach_node(np);
 246         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 247
 248         __of_attach_node_sysfs(np);
 249         mutex_unlock(&of_mutex);
 250
 251         of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, &rd);
 252
 253         return 0;
 254 }
 255
 256 void __of_detach_node(struct device_node *np)
 257 {
 258         struct device_node *parent;
 259
 260         if (WARN_ON(of_node_check_flag(np, OF_DETACHED)))
 261                 return;
 262
 263         parent = np->parent;
 264         if (WARN_ON(!parent))
 265                 return;
 266
 267         if (parent->child == np)
 268                 parent->child = np->sibling;
 269         else {
 270                 struct device_node *prevsib;
 271                 for (prevsib = np->parent->child;
 272                      prevsib->sibling != np;
 273                      prevsib = prevsib->sibling)
 274                         ;
 275                 prevsib->sibling = np->sibling;
 276         }
 277
 278         of_node_set_flag(np, OF_DETACHED);
 279
 280         /* race with of_find_node_by_phandle() prevented by devtree_lock */
 281         __of_phandle_cache_inv_entry(np->phandle);
 282 }
 283
 284 /**
 285  * of_detach_node() - "Unplug" a node from the device tree.
 286  * @np:         Pointer to the caller's Device Node
 287  */
 288 int of_detach_node(struct device_node *np)
 289 {
 290         struct of_reconfig_data rd;
 291         unsigned long flags;
 292
 293         memset(&rd, 0, sizeof(rd));
 294         rd.dn = np;
 295
 296         mutex_lock(&of_mutex);
 297         raw_spin_lock_irqsave(&devtree_lock, flags);
 298         __of_detach_node(np);
 299         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 300
 301         __of_detach_node_sysfs(np);
 302         mutex_unlock(&of_mutex);
 303
 304         of_reconfig_notify(OF_RECONFIG_DETACH_NODE, &rd);
 305
 306         return 0;
 307 }
 308 EXPORT_SYMBOL_GPL(of_detach_node);
 309
 310 static void property_list_free(struct property *prop_list)
 311 {
 312         struct property *prop, *next;
 313
 314         for (prop = prop_list; prop != NULL; prop = next) {
 315                 next = prop->next;
 316                 kfree(prop->name);
 317                 kfree(prop->value);
 318                 kfree(prop);
 319         }
 320 }
 321
 322 /**
 323  * of_node_release() - release a dynamically allocated node
 324  * @kobj: kernel object of the node to be released
 325  *
 326  * In of_node_put() this function is passed to kref_put() as the destructor.
 327  */
 328 void of_node_release(struct kobject *kobj)
 329 {
 330         struct device_node *node = kobj_to_device_node(kobj);
 331
 332         /* We should never be releasing nodes that haven't been detached. */
 333         if (!of_node_check_flag(node, OF_DETACHED)) {
 334                 pr_err("ERROR: Bad of_node_put() on %pOF\n", node);
 335                 dump_stack();
 336                 return;
 337         }
 338         if (!of_node_check_flag(node, OF_DYNAMIC))
 339                 return;
 340
 341         if (of_node_check_flag(node, OF_OVERLAY)) {
 342
 343                 if (!of_node_check_flag(node, OF_OVERLAY_FREE_CSET)) {
 344                         /* premature refcount of zero, do not free memory */
 345                         pr_err("ERROR: memory leak before free overlay changeset,  %pOF\n",
 346                                node);
 347                         return;
 348                 }
 349
 350                 /*
 351                  * If node->properties non-empty then properties were added
 352                  * to this node either by different overlay that has not
 353                  * yet been removed, or by a non-overlay mechanism.
 354                  */
 355                 if (node->properties)
 356                         pr_err("ERROR: %s(), unexpected properties in %pOF\n",
 357                                __func__, node);
 358         }
 359
 360         property_list_free(node->properties);
 361         property_list_free(node->deadprops);
 362         fwnode_links_purge(of_fwnode_handle(node));
 363
 364         kfree(node->full_name);
 365         kfree(node->data);
 366         kfree(node);
 367 }
 368
 369 /**
 370  * __of_prop_dup - Copy a property dynamically.
 371  * @prop:       Property to copy
 372  * @allocflags: Allocation flags (typically pass GFP_KERNEL)
 373  *
 374  * Copy a property by dynamically allocating the memory of both the
 375  * property structure and the property name & contents. The property's
 376  * flags have the OF_DYNAMIC bit set so that we can differentiate between
 377  * dynamically allocated properties and not.
 378  *
 379  * Return: The newly allocated property or NULL on out of memory error.
 380  */
 381 struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
 382 {
 383         struct property *new;
 384
 385         new = kzalloc(sizeof(*new), allocflags);
 386         if (!new)
 387                 return NULL;
 388
 389         /*
 390          * NOTE: There is no check for zero length value.
 391          * In case of a boolean property, this will allocate a value
 392          * of zero bytes. We do this to work around the use
 393          * of of_get_property() calls on boolean values.
 394          */
 395         new->name = kstrdup(prop->name, allocflags);
 396         new->value = kmemdup(prop->value, prop->length, allocflags);
 397         new->length = prop->length;
 398         if (!new->name || !new->value)
 399                 goto err_free;
 400
 401         /* mark the property as dynamic */
 402         of_property_set_flag(new, OF_DYNAMIC);
 403
 404         return new;
 405
 406  err_free:
 407         kfree(new->name);
 408         kfree(new->value);
 409         kfree(new);
 410         return NULL;
 411 }
 412
 413 /**
 414  * __of_node_dup() - Duplicate or create an empty device node dynamically.
 415  * @np:         if not NULL, contains properties to be duplicated in new node
 416  * @full_name:  string value to be duplicated into new node's full_name field
 417  *
 418  * Create a device tree node, optionally duplicating the properties of
 419  * another node.  The node data are dynamically allocated and all the node
 420  * flags have the OF_DYNAMIC & OF_DETACHED bits set.
 421  *
 422  * Return: The newly allocated node or NULL on out of memory error.
 423  */
 424 struct device_node *__of_node_dup(const struct device_node *np,
 425                                   const char *full_name)
 426 {
 427         struct device_node *node;
 428
 429         node = kzalloc(sizeof(*node), GFP_KERNEL);
 430         if (!node)
 431                 return NULL;
 432         node->full_name = kstrdup(full_name, GFP_KERNEL);
 433         if (!node->full_name) {
 434                 kfree(node);
 435                 return NULL;
 436         }
 437
 438         of_node_set_flag(node, OF_DYNAMIC);
 439         of_node_set_flag(node, OF_DETACHED);
 440         of_node_init(node);
 441
 442         /* Iterate over and duplicate all properties */
 443         if (np) {
 444                 struct property *pp, *new_pp;
 445                 for_each_property_of_node(np, pp) {
 446                         new_pp = __of_prop_dup(pp, GFP_KERNEL);
 447                         if (!new_pp)
 448                                 goto err_prop;
 449                         if (__of_add_property(node, new_pp)) {
 450                                 kfree(new_pp->name);
 451                                 kfree(new_pp->value);
 452                                 kfree(new_pp);
 453                                 goto err_prop;
 454                         }
 455                 }
 456         }
 457         return node;
 458
 459  err_prop:
 460         of_node_put(node); /* Frees the node and properties */
 461         return NULL;
 462 }
 463
 464 static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
 465 {
 466         if (ce->action == OF_RECONFIG_ATTACH_NODE &&
 467             of_node_check_flag(ce->np, OF_OVERLAY)) {
 468                 if (kref_read(&ce->np->kobj.kref) > 1) {
 469                         pr_err("ERROR: memory leak, expected refcount 1 instead of %d, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node %pOF\n",
 470                                kref_read(&ce->np->kobj.kref), ce->np);
 471                 } else {
 472                         of_node_set_flag(ce->np, OF_OVERLAY_FREE_CSET);
 473                 }
 474         }
 475
 476         of_node_put(ce->np);
 477         list_del(&ce->node);
 478         kfree(ce);
 479 }
 480
 481 #ifdef DEBUG
 482 static void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 483 {
 484         switch (ce->action) {
 485         case OF_RECONFIG_ADD_PROPERTY:
 486         case OF_RECONFIG_REMOVE_PROPERTY:
 487         case OF_RECONFIG_UPDATE_PROPERTY:
 488                 pr_debug("cset<%p> %-15s %pOF/%s\n", ce, action_names[ce->action],
 489                         ce->np, ce->prop->name);
 490                 break;
 491         case OF_RECONFIG_ATTACH_NODE:
 492         case OF_RECONFIG_DETACH_NODE:
 493                 pr_debug("cset<%p> %-15s %pOF\n", ce, action_names[ce->action],
 494                         ce->np);
 495                 break;
 496         }
 497 }
 498 #else
 499 static inline void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 500 {
 501         /* empty */
 502 }
 503 #endif
 504
 505 static void __of_changeset_entry_invert(struct of_changeset_entry *ce,
 506                                           struct of_changeset_entry *rce)
 507 {
 508         memcpy(rce, ce, sizeof(*rce));
 509
 510         switch (ce->action) {
 511         case OF_RECONFIG_ATTACH_NODE:
 512                 rce->action = OF_RECONFIG_DETACH_NODE;
 513                 break;
 514         case OF_RECONFIG_DETACH_NODE:
 515                 rce->action = OF_RECONFIG_ATTACH_NODE;
 516                 break;
 517         case OF_RECONFIG_ADD_PROPERTY:
 518                 rce->action = OF_RECONFIG_REMOVE_PROPERTY;
 519                 break;
 520         case OF_RECONFIG_REMOVE_PROPERTY:
 521                 rce->action = OF_RECONFIG_ADD_PROPERTY;
 522                 break;
 523         case OF_RECONFIG_UPDATE_PROPERTY:
 524                 rce->old_prop = ce->prop;
 525                 rce->prop = ce->old_prop;
 526                 /* update was used but original property did not exist */
 527                 if (!rce->prop) {
 528                         rce->action = OF_RECONFIG_REMOVE_PROPERTY;
 529                         rce->prop = ce->prop;
 530                 }
 531                 break;
 532         }
 533 }
 534
 535 static int __of_changeset_entry_notify(struct of_changeset_entry *ce,
 536                 bool revert)
 537 {
 538         struct of_reconfig_data rd;
 539         struct of_changeset_entry ce_inverted;
 540         int ret = 0;
 541
 542         if (revert) {
 543                 __of_changeset_entry_invert(ce, &ce_inverted);
 544                 ce = &ce_inverted;
 545         }
 546
 547         switch (ce->action) {
 548         case OF_RECONFIG_ATTACH_NODE:
 549         case OF_RECONFIG_DETACH_NODE:
 550                 memset(&rd, 0, sizeof(rd));
 551                 rd.dn = ce->np;
 552                 ret = of_reconfig_notify(ce->action, &rd);
 553                 break;
 554         case OF_RECONFIG_ADD_PROPERTY:
 555         case OF_RECONFIG_REMOVE_PROPERTY:
 556         case OF_RECONFIG_UPDATE_PROPERTY:
 557                 ret = of_property_notify(ce->action, ce->np, ce->prop, ce->old_prop);
 558                 break;
 559         default:
 560                 pr_err("invalid devicetree changeset action: %i\n",
 561                         (int)ce->action);
 562                 ret = -EINVAL;
 563         }
 564
 565         if (ret)
 566                 pr_err("changeset notifier error @%pOF\n", ce->np);
 567         return ret;
 568 }
 569
 570 static int __of_changeset_entry_apply(struct of_changeset_entry *ce)
 571 {
 572         struct property *old_prop, **propp;
 573         unsigned long flags;
 574         int ret = 0;
 575
 576         __of_changeset_entry_dump(ce);
 577
 578         raw_spin_lock_irqsave(&devtree_lock, flags);
 579         switch (ce->action) {
 580         case OF_RECONFIG_ATTACH_NODE:
 581                 __of_attach_node(ce->np);
 582                 break;
 583         case OF_RECONFIG_DETACH_NODE:
 584                 __of_detach_node(ce->np);
 585                 break;
 586         case OF_RECONFIG_ADD_PROPERTY:
 587                 /* If the property is in deadprops then it must be removed */
 588                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 589                         if (*propp == ce->prop) {
 590                                 *propp = ce->prop->next;
 591                                 ce->prop->next = NULL;
 592                                 break;
 593                         }
 594                 }
 595
 596                 ret = __of_add_property(ce->np, ce->prop);
 597                 if (ret) {
 598                         pr_err("changeset: add_property failed @%pOF/%s\n",
 599                                 ce->np,
 600                                 ce->prop->name);
 601                         break;
 602                 }
 603                 break;
 604         case OF_RECONFIG_REMOVE_PROPERTY:
 605                 ret = __of_remove_property(ce->np, ce->prop);
 606                 if (ret) {
 607                         pr_err("changeset: remove_property failed @%pOF/%s\n",
 608                                 ce->np,
 609                                 ce->prop->name);
 610                         break;
 611                 }
 612                 break;
 613
 614         case OF_RECONFIG_UPDATE_PROPERTY:
 615                 /* If the property is in deadprops then it must be removed */
 616                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 617                         if (*propp == ce->prop) {
 618                                 *propp = ce->prop->next;
 619                                 ce->prop->next = NULL;
 620                                 break;
 621                         }
 622                 }
 623
 624                 ret = __of_update_property(ce->np, ce->prop, &old_prop);
 625                 if (ret) {
 626                         pr_err("changeset: update_property failed @%pOF/%s\n",
 627                                 ce->np,
 628                                 ce->prop->name);
 629                         break;
 630                 }
 631                 break;
 632         default:
 633                 ret = -EINVAL;
 634         }
 635         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 636
 637         if (ret)
 638                 return ret;
 639
 640         switch (ce->action) {
 641         case OF_RECONFIG_ATTACH_NODE:
 642                 __of_attach_node_sysfs(ce->np);
 643                 break;
 644         case OF_RECONFIG_DETACH_NODE:
 645                 __of_detach_node_sysfs(ce->np);
 646                 break;
 647         case OF_RECONFIG_ADD_PROPERTY:
 648                 /* ignore duplicate names */
 649                 __of_add_property_sysfs(ce->np, ce->prop);
 650                 break;
 651         case OF_RECONFIG_REMOVE_PROPERTY:
 652                 __of_remove_property_sysfs(ce->np, ce->prop);
 653                 break;
 654         case OF_RECONFIG_UPDATE_PROPERTY:
 655                 __of_update_property_sysfs(ce->np, ce->prop, ce->old_prop);
 656                 break;
 657         }
 658
 659         return 0;
 660 }
 661
 662 static inline int __of_changeset_entry_revert(struct of_changeset_entry *ce)
 663 {
 664         struct of_changeset_entry ce_inverted;
 665
 666         __of_changeset_entry_invert(ce, &ce_inverted);
 667         return __of_changeset_entry_apply(&ce_inverted);
 668 }
 669
 670 /**
 671  * of_changeset_init - Initialize a changeset for use
 672  *
 673  * @ocs:        changeset pointer
 674  *
 675  * Initialize a changeset structure
 676  */
 677 void of_changeset_init(struct of_changeset *ocs)
 678 {
 679         memset(ocs, 0, sizeof(*ocs));
 680         INIT_LIST_HEAD(&ocs->entries);
 681 }
 682 EXPORT_SYMBOL_GPL(of_changeset_init);
 683
 684 /**
 685  * of_changeset_destroy - Destroy a changeset
 686  *
 687  * @ocs:        changeset pointer
 688  *
 689  * Destroys a changeset. Note that if a changeset is applied,
 690  * its changes to the tree cannot be reverted.
 691  */
 692 void of_changeset_destroy(struct of_changeset *ocs)
 693 {
 694         struct of_changeset_entry *ce, *cen;
 695
 696         list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node)
 697                 __of_changeset_entry_destroy(ce);
 698 }
 699 EXPORT_SYMBOL_GPL(of_changeset_destroy);
 700
 701 /*
 702  * Apply the changeset entries in @ocs.
 703  * If apply fails, an attempt is made to revert the entries that were
 704  * successfully applied.
 705  *
 706  * If multiple revert errors occur then only the final revert error is reported.
 707  *
 708  * Returns 0 on success, a negative error value in case of an error.
 709  * If a revert error occurs, it is returned in *ret_revert.
 710  */
 711 int __of_changeset_apply_entries(struct of_changeset *ocs, int *ret_revert)
 712 {
 713         struct of_changeset_entry *ce;
 714         int ret, ret_tmp;
 715
 716         pr_debug("changeset: applying...\n");
 717         list_for_each_entry(ce, &ocs->entries, node) {
 718                 ret = __of_changeset_entry_apply(ce);
 719                 if (ret) {
 720                         pr_err("Error applying changeset (%d)\n", ret);
 721                         list_for_each_entry_continue_reverse(ce, &ocs->entries,
 722                                                              node) {
 723                                 ret_tmp = __of_changeset_entry_revert(ce);
 724                                 if (ret_tmp)
 725                                         *ret_revert = ret_tmp;
 726                         }
 727                         return ret;
 728                 }
 729         }
 730
 731         return 0;
 732 }
 733
 734 /*
 735  * Returns 0 on success, a negative error value in case of an error.
 736  *
 737  * If multiple changeset entry notification errors occur then only the
 738  * final notification error is reported.
 739  */
 740 int __of_changeset_apply_notify(struct of_changeset *ocs)
 741 {
 742         struct of_changeset_entry *ce;
 743         int ret = 0, ret_tmp;
 744
 745         pr_debug("changeset: emitting notifiers.\n");
 746
 747         /* drop the global lock while emitting notifiers */
 748         mutex_unlock(&of_mutex);
 749         list_for_each_entry(ce, &ocs->entries, node) {
 750                 ret_tmp = __of_changeset_entry_notify(ce, 0);
 751                 if (ret_tmp)
 752                         ret = ret_tmp;
 753         }
 754         mutex_lock(&of_mutex);
 755         pr_debug("changeset: notifiers sent.\n");
 756
 757         return ret;
 758 }
 759
 760 /*
 761  * Returns 0 on success, a negative error value in case of an error.
 762  *
 763  * If a changeset entry apply fails, an attempt is made to revert any
 764  * previous entries in the changeset.  If any of the reverts fails,
 765  * that failure is not reported.  Thus the state of the device tree
 766  * is unknown if an apply error occurs.
 767  */
 768 static int __of_changeset_apply(struct of_changeset *ocs)
 769 {
 770         int ret, ret_revert = 0;
 771
 772         ret = __of_changeset_apply_entries(ocs, &ret_revert);
 773         if (!ret)
 774                 ret = __of_changeset_apply_notify(ocs);
 775
 776         return ret;
 777 }
 778
 779 /**
 780  * of_changeset_apply - Applies a changeset
 781  *
 782  * @ocs:        changeset pointer
 783  *
 784  * Applies a changeset to the live tree.
 785  * Any side-effects of live tree state changes are applied here on
 786  * success, like creation/destruction of devices and side-effects
 787  * like creation of sysfs properties and directories.
 788  *
 789  * Return: 0 on success, a negative error value in case of an error.
 790  * On error the partially applied effects are reverted.
 791  */
 792 int of_changeset_apply(struct of_changeset *ocs)
 793 {
 794         int ret;
 795
 796         mutex_lock(&of_mutex);
 797         ret = __of_changeset_apply(ocs);
 798         mutex_unlock(&of_mutex);
 799
 800         return ret;
 801 }
 802 EXPORT_SYMBOL_GPL(of_changeset_apply);
 803
 804 /*
 805  * Revert the changeset entries in @ocs.
 806  * If revert fails, an attempt is made to re-apply the entries that were
 807  * successfully removed.
 808  *
 809  * If multiple re-apply errors occur then only the final apply error is
 810  * reported.
 811  *
 812  * Returns 0 on success, a negative error value in case of an error.
 813  * If an apply error occurs, it is returned in *ret_apply.
 814  */
 815 int __of_changeset_revert_entries(struct of_changeset *ocs, int *ret_apply)
 816 {
 817         struct of_changeset_entry *ce;
 818         int ret, ret_tmp;
 819
 820         pr_debug("changeset: reverting...\n");
 821         list_for_each_entry_reverse(ce, &ocs->entries, node) {
 822                 ret = __of_changeset_entry_revert(ce);
 823                 if (ret) {
 824                         pr_err("Error reverting changeset (%d)\n", ret);
 825                         list_for_each_entry_continue(ce, &ocs->entries, node) {
 826                                 ret_tmp = __of_changeset_entry_apply(ce);
 827                                 if (ret_tmp)
 828                                         *ret_apply = ret_tmp;
 829                         }
 830                         return ret;
 831                 }
 832         }
 833
 834         return 0;
 835 }
 836
 837 /*
 838  * If multiple changeset entry notification errors occur then only the
 839  * final notification error is reported.
 840  */
 841 int __of_changeset_revert_notify(struct of_changeset *ocs)
 842 {
 843         struct of_changeset_entry *ce;
 844         int ret = 0, ret_tmp;
 845
 846         pr_debug("changeset: emitting notifiers.\n");
 847
 848         /* drop the global lock while emitting notifiers */
 849         mutex_unlock(&of_mutex);
 850         list_for_each_entry_reverse(ce, &ocs->entries, node) {
 851                 ret_tmp = __of_changeset_entry_notify(ce, 1);
 852                 if (ret_tmp)
 853                         ret = ret_tmp;
 854         }
 855         mutex_lock(&of_mutex);
 856         pr_debug("changeset: notifiers sent.\n");
 857
 858         return ret;
 859 }
 860
 861 static int __of_changeset_revert(struct of_changeset *ocs)
 862 {
 863         int ret, ret_reply;
 864
 865         ret_reply = 0;
 866         ret = __of_changeset_revert_entries(ocs, &ret_reply);
 867
 868         if (!ret)
 869                 ret = __of_changeset_revert_notify(ocs);
 870
 871         return ret;
 872 }
 873
 874 /**
 875  * of_changeset_revert - Reverts an applied changeset
 876  *
 877  * @ocs:        changeset pointer
 878  *
 879  * Reverts a changeset returning the state of the tree to what it
 880  * was before the application.
 881  * Any side-effects like creation/destruction of devices and
 882  * removal of sysfs properties and directories are applied.
 883  *
 884  * Return: 0 on success, a negative error value in case of an error.
 885  */
 886 int of_changeset_revert(struct of_changeset *ocs)
 887 {
 888         int ret;
 889
 890         mutex_lock(&of_mutex);
 891         ret = __of_changeset_revert(ocs);
 892         mutex_unlock(&of_mutex);
 893
 894         return ret;
 895 }
 896 EXPORT_SYMBOL_GPL(of_changeset_revert);
 897
 898 /**
 899  * of_changeset_action - Add an action to the tail of the changeset list
 900  *
 901  * @ocs:        changeset pointer
 902  * @action:     action to perform
 903  * @np:         Pointer to device node
 904  * @prop:       Pointer to property
 905  *
 906  * On action being one of:
 907  * + OF_RECONFIG_ATTACH_NODE
 908  * + OF_RECONFIG_DETACH_NODE,
 909  * + OF_RECONFIG_ADD_PROPERTY
 910  * + OF_RECONFIG_REMOVE_PROPERTY,
 911  * + OF_RECONFIG_UPDATE_PROPERTY
 912  *
 913  * Return: 0 on success, a negative error value in case of an error.
 914  */
 915 int of_changeset_action(struct of_changeset *ocs, unsigned long action,
 916                 struct device_node *np, struct property *prop)
 917 {
 918         struct of_changeset_entry *ce;
 919
 920         ce = kzalloc(sizeof(*ce), GFP_KERNEL);
 921         if (!ce)
 922                 return -ENOMEM;
 923
 924         /* get a reference to the node */
 925         ce->action = action;
 926         ce->np = of_node_get(np);
 927         ce->prop = prop;
 928
 929         if (action == OF_RECONFIG_UPDATE_PROPERTY && prop)
 930                 ce->old_prop = of_find_property(np, prop->name, NULL);
 931
 932         /* add it to the list */
 933         list_add_tail(&ce->node, &ocs->entries);
 934         return 0;
 935 }
 936 EXPORT_SYMBOL_GPL(of_changeset_action);