drivers/of/dynamic.c

   1 /*
   2  * Support for dynamic device trees.
   3  *
   4  * On some platforms, the device tree can be manipulated at runtime.
   5  * The routines in this section support adding, removing and changing
   6  * device tree nodes.
   7  */
   8
   9 #include <linux/of.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/slab.h>
  12 #include <linux/string.h>
  13 #include <linux/proc_fs.h>
  14
  15 #include "of_private.h"
  16
  17 /**
  18  * of_node_get() - Increment refcount of a node
  19  * @node:       Node to inc refcount, NULL is supported to simplify writing of
  20  *              callers
  21  *
  22  * Returns node.
  23  */
  24 struct device_node *of_node_get(struct device_node *node)
  25 {
  26         if (node)
  27                 kobject_get(&node->kobj);
  28         return node;
  29 }
  30 EXPORT_SYMBOL(of_node_get);
  31
  32 /**
  33  * of_node_put() - Decrement refcount of a node
  34  * @node:       Node to dec refcount, NULL is supported to simplify writing of
  35  *              callers
  36  */
  37 void of_node_put(struct device_node *node)
  38 {
  39         if (node)
  40                 kobject_put(&node->kobj);
  41 }
  42 EXPORT_SYMBOL(of_node_put);
  43
  44 void __of_detach_node_sysfs(struct device_node *np)
  45 {
  46         struct property *pp;
  47
  48         if (!IS_ENABLED(CONFIG_SYSFS))
  49                 return;
  50
  51         BUG_ON(!of_node_is_initialized(np));
  52         if (!of_kset)
  53                 return;
  54
  55         /* only remove properties if on sysfs */
  56         if (of_node_is_attached(np)) {
  57                 for_each_property_of_node(np, pp)
  58                         sysfs_remove_bin_file(&np->kobj, &pp->attr);
  59                 kobject_del(&np->kobj);
  60         }
  61
  62         /* finally remove the kobj_init ref */
  63         of_node_put(np);
  64 }
  65
  66 static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain);
  67
  68 int of_reconfig_notifier_register(struct notifier_block *nb)
  69 {
  70         return blocking_notifier_chain_register(&of_reconfig_chain, nb);
  71 }
  72 EXPORT_SYMBOL_GPL(of_reconfig_notifier_register);
  73
  74 int of_reconfig_notifier_unregister(struct notifier_block *nb)
  75 {
  76         return blocking_notifier_chain_unregister(&of_reconfig_chain, nb);
  77 }
  78 EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister);
  79
  80 int of_reconfig_notify(unsigned long action, void *p)
  81 {
  82         int rc;
  83
  84         rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p);
  85         return notifier_to_errno(rc);
  86 }
  87
  88 int of_property_notify(int action, struct device_node *np,
  89                        struct property *prop, struct property *oldprop)
  90 {
  91         struct of_prop_reconfig pr;
  92
  93         /* only call notifiers if the node is attached */
  94         if (!of_node_is_attached(np))
  95                 return 0;
  96
  97         pr.dn = np;
  98         pr.prop = prop;
  99         pr.old_prop = oldprop;
 100         return of_reconfig_notify(action, &pr);
 101 }
 102
 103 void __of_attach_node(struct device_node *np)
 104 {
 105         const __be32 *phandle;
 106         int sz;
 107
 108         np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
 109         np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
 110
 111         phandle = __of_get_property(np, "phandle", &sz);
 112         if (!phandle)
 113                 phandle = __of_get_property(np, "linux,phandle", &sz);
 114         if (IS_ENABLED(PPC_PSERIES) && !phandle)
 115                 phandle = __of_get_property(np, "ibm,phandle", &sz);
 116         np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;
 117
 118         np->child = NULL;
 119         np->sibling = np->parent->child;
 120         np->allnext = np->parent->allnext;
 121         np->parent->allnext = np;
 122         np->parent->child = np;
 123         of_node_clear_flag(np, OF_DETACHED);
 124 }
 125
 126 /**
 127  * of_attach_node() - Plug a device node into the tree and global list.
 128  */
 129 int of_attach_node(struct device_node *np)
 130 {
 131         unsigned long flags;
 132
 133         mutex_lock(&of_mutex);
 134         raw_spin_lock_irqsave(&devtree_lock, flags);
 135         __of_attach_node(np);
 136         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 137
 138         __of_attach_node_sysfs(np);
 139         mutex_unlock(&of_mutex);
 140
 141         of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, np);
 142
 143         return 0;
 144 }
 145
 146 void __of_detach_node(struct device_node *np)
 147 {
 148         struct device_node *parent;
 149
 150         if (WARN_ON(of_node_check_flag(np, OF_DETACHED)))
 151                 return;
 152
 153         parent = np->parent;
 154         if (WARN_ON(!parent))
 155                 return;
 156
 157         if (of_allnodes == np)
 158                 of_allnodes = np->allnext;
 159         else {
 160                 struct device_node *prev;
 161                 for (prev = of_allnodes;
 162                      prev->allnext != np;
 163                      prev = prev->allnext)
 164                         ;
 165                 prev->allnext = np->allnext;
 166         }
 167
 168         if (parent->child == np)
 169                 parent->child = np->sibling;
 170         else {
 171                 struct device_node *prevsib;
 172                 for (prevsib = np->parent->child;
 173                      prevsib->sibling != np;
 174                      prevsib = prevsib->sibling)
 175                         ;
 176                 prevsib->sibling = np->sibling;
 177         }
 178
 179         of_node_set_flag(np, OF_DETACHED);
 180 }
 181
 182 /**
 183  * of_detach_node() - "Unplug" a node from the device tree.
 184  *
 185  * The caller must hold a reference to the node.  The memory associated with
 186  * the node is not freed until its refcount goes to zero.
 187  */
 188 int of_detach_node(struct device_node *np)
 189 {
 190         unsigned long flags;
 191         int rc = 0;
 192
 193         mutex_lock(&of_mutex);
 194         raw_spin_lock_irqsave(&devtree_lock, flags);
 195         __of_detach_node(np);
 196         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 197
 198         __of_detach_node_sysfs(np);
 199         mutex_unlock(&of_mutex);
 200
 201         of_reconfig_notify(OF_RECONFIG_DETACH_NODE, np);
 202
 203         return rc;
 204 }
 205
 206 /**
 207  * of_node_release() - release a dynamically allocated node
 208  * @kref: kref element of the node to be released
 209  *
 210  * In of_node_put() this function is passed to kref_put() as the destructor.
 211  */
 212 void of_node_release(struct kobject *kobj)
 213 {
 214         struct device_node *node = kobj_to_device_node(kobj);
 215         struct property *prop = node->properties;
 216
 217         /* We should never be releasing nodes that haven't been detached. */
 218         if (!of_node_check_flag(node, OF_DETACHED)) {
 219                 pr_err("ERROR: Bad of_node_put() on %s\n", node->full_name);
 220                 dump_stack();
 221                 return;
 222         }
 223
 224         if (!of_node_check_flag(node, OF_DYNAMIC))
 225                 return;
 226
 227         while (prop) {
 228                 struct property *next = prop->next;
 229                 kfree(prop->name);
 230                 kfree(prop->value);
 231                 kfree(prop);
 232                 prop = next;
 233
 234                 if (!prop) {
 235                         prop = node->deadprops;
 236                         node->deadprops = NULL;
 237                 }
 238         }
 239         kfree(node->full_name);
 240         kfree(node->data);
 241         kfree(node);
 242 }
 243
 244 /**
 245  * __of_prop_dup - Copy a property dynamically.
 246  * @prop:       Property to copy
 247  * @allocflags: Allocation flags (typically pass GFP_KERNEL)
 248  *
 249  * Copy a property by dynamically allocating the memory of both the
 250  * property stucture and the property name & contents. The property's
 251  * flags have the OF_DYNAMIC bit set so that we can differentiate between
 252  * dynamically allocated properties and not.
 253  * Returns the newly allocated property or NULL on out of memory error.
 254  */
 255 struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
 256 {
 257         struct property *new;
 258
 259         new = kzalloc(sizeof(*new), allocflags);
 260         if (!new)
 261                 return NULL;
 262
 263         /*
 264          * NOTE: There is no check for zero length value.
 265          * In case of a boolean property, this will allocate a value
 266          * of zero bytes. We do this to work around the use
 267          * of of_get_property() calls on boolean values.
 268          */
 269         new->name = kstrdup(prop->name, allocflags);
 270         new->value = kmemdup(prop->value, prop->length, allocflags);
 271         new->length = prop->length;
 272         if (!new->name || !new->value)
 273                 goto err_free;
 274
 275         /* mark the property as dynamic */
 276         of_property_set_flag(new, OF_DYNAMIC);
 277
 278         return new;
 279
 280  err_free:
 281         kfree(new->name);
 282         kfree(new->value);
 283         kfree(new);
 284         return NULL;
 285 }
 286
 287 /**
 288  * __of_node_alloc() - Create an empty device node dynamically.
 289  * @full_name:  Full name of the new device node
 290  * @allocflags: Allocation flags (typically pass GFP_KERNEL)
 291  *
 292  * Create an empty device tree node, suitable for further modification.
 293  * The node data are dynamically allocated and all the node flags
 294  * have the OF_DYNAMIC & OF_DETACHED bits set.
 295  * Returns the newly allocated node or NULL on out of memory error.
 296  */
 297 struct device_node *__of_node_alloc(const char *full_name, gfp_t allocflags)
 298 {
 299         struct device_node *node;
 300
 301         node = kzalloc(sizeof(*node), allocflags);
 302         if (!node)
 303                 return NULL;
 304
 305         node->full_name = kstrdup(full_name, allocflags);
 306         of_node_set_flag(node, OF_DYNAMIC);
 307         of_node_set_flag(node, OF_DETACHED);
 308         if (!node->full_name)
 309                 goto err_free;
 310
 311         of_node_init(node);
 312
 313         return node;
 314
 315  err_free:
 316         kfree(node->full_name);
 317         kfree(node);
 318         return NULL;
 319 }
 320
 321 static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
 322 {
 323         of_node_put(ce->np);
 324         list_del(&ce->node);
 325         kfree(ce);
 326 }
 327
 328 #ifdef DEBUG
 329 static void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 330 {
 331         switch (ce->action) {
 332         case OF_RECONFIG_ADD_PROPERTY:
 333                 pr_debug("%p: %s %s/%s\n",
 334                         ce, "ADD_PROPERTY   ", ce->np->full_name,
 335                         ce->prop->name);
 336                 break;
 337         case OF_RECONFIG_REMOVE_PROPERTY:
 338                 pr_debug("%p: %s %s/%s\n",
 339                         ce, "REMOVE_PROPERTY", ce->np->full_name,
 340                         ce->prop->name);
 341                 break;
 342         case OF_RECONFIG_UPDATE_PROPERTY:
 343                 pr_debug("%p: %s %s/%s\n",
 344                         ce, "UPDATE_PROPERTY", ce->np->full_name,
 345                         ce->prop->name);
 346                 break;
 347         case OF_RECONFIG_ATTACH_NODE:
 348                 pr_debug("%p: %s %s\n",
 349                         ce, "ATTACH_NODE    ", ce->np->full_name);
 350                 break;
 351         case OF_RECONFIG_DETACH_NODE:
 352                 pr_debug("%p: %s %s\n",
 353                         ce, "DETACH_NODE    ", ce->np->full_name);
 354                 break;
 355         }
 356 }
 357 #else
 358 static inline void __of_changeset_entry_dump(struct of_changeset_entry *ce)
 359 {
 360         /* empty */
 361 }
 362 #endif
 363
 364 static void __of_changeset_entry_invert(struct of_changeset_entry *ce,
 365                                           struct of_changeset_entry *rce)
 366 {
 367         memcpy(rce, ce, sizeof(*rce));
 368
 369         switch (ce->action) {
 370         case OF_RECONFIG_ATTACH_NODE:
 371                 rce->action = OF_RECONFIG_DETACH_NODE;
 372                 break;
 373         case OF_RECONFIG_DETACH_NODE:
 374                 rce->action = OF_RECONFIG_ATTACH_NODE;
 375                 break;
 376         case OF_RECONFIG_ADD_PROPERTY:
 377                 rce->action = OF_RECONFIG_REMOVE_PROPERTY;
 378                 break;
 379         case OF_RECONFIG_REMOVE_PROPERTY:
 380                 rce->action = OF_RECONFIG_ADD_PROPERTY;
 381                 break;
 382         case OF_RECONFIG_UPDATE_PROPERTY:
 383                 rce->old_prop = ce->prop;
 384                 rce->prop = ce->old_prop;
 385                 break;
 386         }
 387 }
 388
 389 static void __of_changeset_entry_notify(struct of_changeset_entry *ce, bool revert)
 390 {
 391         struct of_changeset_entry ce_inverted;
 392         int ret;
 393
 394         if (revert) {
 395                 __of_changeset_entry_invert(ce, &ce_inverted);
 396                 ce = &ce_inverted;
 397         }
 398
 399         switch (ce->action) {
 400         case OF_RECONFIG_ATTACH_NODE:
 401         case OF_RECONFIG_DETACH_NODE:
 402                 ret = of_reconfig_notify(ce->action, ce->np);
 403                 break;
 404         case OF_RECONFIG_ADD_PROPERTY:
 405         case OF_RECONFIG_REMOVE_PROPERTY:
 406         case OF_RECONFIG_UPDATE_PROPERTY:
 407                 ret = of_property_notify(ce->action, ce->np, ce->prop, ce->old_prop);
 408                 break;
 409         default:
 410                 pr_err("%s: invalid devicetree changeset action: %i\n", __func__,
 411                         (int)ce->action);
 412                 return;
 413         }
 414
 415         if (ret)
 416                 pr_err("%s: notifier error @%s\n", __func__, ce->np->full_name);
 417 }
 418
 419 static int __of_changeset_entry_apply(struct of_changeset_entry *ce)
 420 {
 421         struct property *old_prop, **propp;
 422         unsigned long flags;
 423         int ret = 0;
 424
 425         __of_changeset_entry_dump(ce);
 426
 427         raw_spin_lock_irqsave(&devtree_lock, flags);
 428         switch (ce->action) {
 429         case OF_RECONFIG_ATTACH_NODE:
 430                 __of_attach_node(ce->np);
 431                 break;
 432         case OF_RECONFIG_DETACH_NODE:
 433                 __of_detach_node(ce->np);
 434                 break;
 435         case OF_RECONFIG_ADD_PROPERTY:
 436                 /* If the property is in deadprops then it must be removed */
 437                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 438                         if (*propp == ce->prop) {
 439                                 *propp = ce->prop->next;
 440                                 ce->prop->next = NULL;
 441                                 break;
 442                         }
 443                 }
 444
 445                 ret = __of_add_property(ce->np, ce->prop);
 446                 if (ret) {
 447                         pr_err("%s: add_property failed @%s/%s\n",
 448                                 __func__, ce->np->full_name,
 449                                 ce->prop->name);
 450                         break;
 451                 }
 452                 break;
 453         case OF_RECONFIG_REMOVE_PROPERTY:
 454                 ret = __of_remove_property(ce->np, ce->prop);
 455                 if (ret) {
 456                         pr_err("%s: remove_property failed @%s/%s\n",
 457                                 __func__, ce->np->full_name,
 458                                 ce->prop->name);
 459                         break;
 460                 }
 461                 break;
 462
 463         case OF_RECONFIG_UPDATE_PROPERTY:
 464                 /* If the property is in deadprops then it must be removed */
 465                 for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
 466                         if (*propp == ce->prop) {
 467                                 *propp = ce->prop->next;
 468                                 ce->prop->next = NULL;
 469                                 break;
 470                         }
 471                 }
 472
 473                 ret = __of_update_property(ce->np, ce->prop, &old_prop);
 474                 if (ret) {
 475                         pr_err("%s: update_property failed @%s/%s\n",
 476                                 __func__, ce->np->full_name,
 477                                 ce->prop->name);
 478                         break;
 479                 }
 480                 break;
 481         default:
 482                 ret = -EINVAL;
 483         }
 484         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 485
 486         if (ret)
 487                 return ret;
 488
 489         switch (ce->action) {
 490         case OF_RECONFIG_ATTACH_NODE:
 491                 __of_attach_node_sysfs(ce->np);
 492                 break;
 493         case OF_RECONFIG_DETACH_NODE:
 494                 __of_detach_node_sysfs(ce->np);
 495                 break;
 496         case OF_RECONFIG_ADD_PROPERTY:
 497                 /* ignore duplicate names */
 498                 __of_add_property_sysfs(ce->np, ce->prop);
 499                 break;
 500         case OF_RECONFIG_REMOVE_PROPERTY:
 501                 __of_remove_property_sysfs(ce->np, ce->prop);
 502                 break;
 503         case OF_RECONFIG_UPDATE_PROPERTY:
 504                 __of_update_property_sysfs(ce->np, ce->prop, ce->old_prop);
 505                 break;
 506         }
 507
 508         return 0;
 509 }
 510
 511 static inline int __of_changeset_entry_revert(struct of_changeset_entry *ce)
 512 {
 513         struct of_changeset_entry ce_inverted;
 514
 515         __of_changeset_entry_invert(ce, &ce_inverted);
 516         return __of_changeset_entry_apply(&ce_inverted);
 517 }
 518
 519 /**
 520  * of_changeset_init - Initialize a changeset for use
 521  *
 522  * @ocs:        changeset pointer
 523  *
 524  * Initialize a changeset structure
 525  */
 526 void of_changeset_init(struct of_changeset *ocs)
 527 {
 528         memset(ocs, 0, sizeof(*ocs));
 529         INIT_LIST_HEAD(&ocs->entries);
 530 }
 531
 532 /**
 533  * of_changeset_destroy - Destroy a changeset
 534  *
 535  * @ocs:        changeset pointer
 536  *
 537  * Destroys a changeset. Note that if a changeset is applied,
 538  * its changes to the tree cannot be reverted.
 539  */
 540 void of_changeset_destroy(struct of_changeset *ocs)
 541 {
 542         struct of_changeset_entry *ce, *cen;
 543
 544         list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node)
 545                 __of_changeset_entry_destroy(ce);
 546 }
 547
 548 /**
 549  * of_changeset_apply - Applies a changeset
 550  *
 551  * @ocs:        changeset pointer
 552  *
 553  * Applies a changeset to the live tree.
 554  * Any side-effects of live tree state changes are applied here on
 555  * sucess, like creation/destruction of devices and side-effects
 556  * like creation of sysfs properties and directories.
 557  * Returns 0 on success, a negative error value in case of an error.
 558  * On error the partially applied effects are reverted.
 559  */
 560 int of_changeset_apply(struct of_changeset *ocs)
 561 {
 562         struct of_changeset_entry *ce;
 563         int ret;
 564
 565         /* perform the rest of the work */
 566         pr_debug("of_changeset: applying...\n");
 567         list_for_each_entry(ce, &ocs->entries, node) {
 568                 ret = __of_changeset_entry_apply(ce);
 569                 if (ret) {
 570                         pr_err("%s: Error applying changeset (%d)\n", __func__, ret);
 571                         list_for_each_entry_continue_reverse(ce, &ocs->entries, node)
 572                                 __of_changeset_entry_revert(ce);
 573                         return ret;
 574                 }
 575         }
 576         pr_debug("of_changeset: applied, emitting notifiers.\n");
 577
 578         /* drop the global lock while emitting notifiers */
 579         mutex_unlock(&of_mutex);
 580         list_for_each_entry(ce, &ocs->entries, node)
 581                 __of_changeset_entry_notify(ce, 0);
 582         mutex_lock(&of_mutex);
 583         pr_debug("of_changeset: notifiers sent.\n");
 584
 585         return 0;
 586 }
 587
 588 /**
 589  * of_changeset_revert - Reverts an applied changeset
 590  *
 591  * @ocs:        changeset pointer
 592  *
 593  * Reverts a changeset returning the state of the tree to what it
 594  * was before the application.
 595  * Any side-effects like creation/destruction of devices and
 596  * removal of sysfs properties and directories are applied.
 597  * Returns 0 on success, a negative error value in case of an error.
 598  */
 599 int of_changeset_revert(struct of_changeset *ocs)
 600 {
 601         struct of_changeset_entry *ce;
 602         int ret;
 603
 604         pr_debug("of_changeset: reverting...\n");
 605         list_for_each_entry_reverse(ce, &ocs->entries, node) {
 606                 ret = __of_changeset_entry_revert(ce);
 607                 if (ret) {
 608                         pr_err("%s: Error reverting changeset (%d)\n", __func__, ret);
 609                         list_for_each_entry_continue(ce, &ocs->entries, node)
 610                                 __of_changeset_entry_apply(ce);
 611                         return ret;
 612                 }
 613         }
 614         pr_debug("of_changeset: reverted, emitting notifiers.\n");
 615
 616         /* drop the global lock while emitting notifiers */
 617         mutex_unlock(&of_mutex);
 618         list_for_each_entry_reverse(ce, &ocs->entries, node)
 619                 __of_changeset_entry_notify(ce, 1);
 620         mutex_lock(&of_mutex);
 621         pr_debug("of_changeset: notifiers sent.\n");
 622
 623         return 0;
 624 }
 625
 626 /**
 627  * of_changeset_action - Perform a changeset action
 628  *
 629  * @ocs:        changeset pointer
 630  * @action:     action to perform
 631  * @np:         Pointer to device node
 632  * @prop:       Pointer to property
 633  *
 634  * On action being one of:
 635  * + OF_RECONFIG_ATTACH_NODE
 636  * + OF_RECONFIG_DETACH_NODE,
 637  * + OF_RECONFIG_ADD_PROPERTY
 638  * + OF_RECONFIG_REMOVE_PROPERTY,
 639  * + OF_RECONFIG_UPDATE_PROPERTY
 640  * Returns 0 on success, a negative error value in case of an error.
 641  */
 642 int of_changeset_action(struct of_changeset *ocs, unsigned long action,
 643                 struct device_node *np, struct property *prop)
 644 {
 645         struct of_changeset_entry *ce;
 646
 647         ce = kzalloc(sizeof(*ce), GFP_KERNEL);
 648         if (!ce) {
 649                 pr_err("%s: Failed to allocate\n", __func__);
 650                 return -ENOMEM;
 651         }
 652         /* get a reference to the node */
 653         ce->action = action;
 654         ce->np = of_node_get(np);
 655         ce->prop = prop;
 656
 657         if (action == OF_RECONFIG_UPDATE_PROPERTY && prop)
 658                 ce->old_prop = of_find_property(np, prop->name, NULL);
 659
 660         /* add it to the list */
 661         list_add_tail(&ce->node, &ocs->entries);
 662         return 0;
 663 }