drivers/of/dynamic.c

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