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