1 /* 2 * Procedures for creating, accessing and interpreting the device tree. 3 * 4 * Paul Mackerras August 1996. 5 * Copyright (C) 1996-2005 Paul Mackerras. 6 * 7 * Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner. 8 * {engebret|bergner}@us.ibm.com 9 * 10 * Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net 11 * 12 * Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell and 13 * Grant Likely. 14 * 15 * This program is free software; you can redistribute it and/or 16 * modify it under the terms of the GNU General Public License 17 * as published by the Free Software Foundation; either version 18 * 2 of the License, or (at your option) any later version. 19 */ 20 #include <linux/module.h> 21 #include <linux/of.h> 22 #include <linux/spinlock.h> 23 24 struct device_node *allnodes; 25 26 /* use when traversing tree through the allnext, child, sibling, 27 * or parent members of struct device_node. 28 */ 29 DEFINE_RWLOCK(devtree_lock); 30 31 int of_n_addr_cells(struct device_node *np) 32 { 33 const int *ip; 34 35 do { 36 if (np->parent) 37 np = np->parent; 38 ip = of_get_property(np, "#address-cells", NULL); 39 if (ip) 40 return *ip; 41 } while (np->parent); 42 /* No #address-cells property for the root node */ 43 return OF_ROOT_NODE_ADDR_CELLS_DEFAULT; 44 } 45 EXPORT_SYMBOL(of_n_addr_cells); 46 47 int of_n_size_cells(struct device_node *np) 48 { 49 const int *ip; 50 51 do { 52 if (np->parent) 53 np = np->parent; 54 ip = of_get_property(np, "#size-cells", NULL); 55 if (ip) 56 return *ip; 57 } while (np->parent); 58 /* No #size-cells property for the root node */ 59 return OF_ROOT_NODE_SIZE_CELLS_DEFAULT; 60 } 61 EXPORT_SYMBOL(of_n_size_cells); 62 63 struct property *of_find_property(const struct device_node *np, 64 const char *name, 65 int *lenp) 66 { 67 struct property *pp; 68 69 if (!np) 70 return NULL; 71 72 read_lock(&devtree_lock); 73 for (pp = np->properties; pp != 0; pp = pp->next) { 74 if (of_prop_cmp(pp->name, name) == 0) { 75 if (lenp != 0) 76 *lenp = pp->length; 77 break; 78 } 79 } 80 read_unlock(&devtree_lock); 81 82 return pp; 83 } 84 EXPORT_SYMBOL(of_find_property); 85 86 /** 87 * of_find_all_nodes - Get next node in global list 88 * @prev: Previous node or NULL to start iteration 89 * of_node_put() will be called on it 90 * 91 * Returns a node pointer with refcount incremented, use 92 * of_node_put() on it when done. 93 */ 94 struct device_node *of_find_all_nodes(struct device_node *prev) 95 { 96 struct device_node *np; 97 98 read_lock(&devtree_lock); 99 np = prev ? prev->allnext : allnodes; 100 for (; np != NULL; np = np->allnext) 101 if (of_node_get(np)) 102 break; 103 of_node_put(prev); 104 read_unlock(&devtree_lock); 105 return np; 106 } 107 EXPORT_SYMBOL(of_find_all_nodes); 108 109 /* 110 * Find a property with a given name for a given node 111 * and return the value. 112 */ 113 const void *of_get_property(const struct device_node *np, const char *name, 114 int *lenp) 115 { 116 struct property *pp = of_find_property(np, name, lenp); 117 118 return pp ? pp->value : NULL; 119 } 120 EXPORT_SYMBOL(of_get_property); 121 122 /** Checks if the given "compat" string matches one of the strings in 123 * the device's "compatible" property 124 */ 125 int of_device_is_compatible(const struct device_node *device, 126 const char *compat) 127 { 128 const char* cp; 129 int cplen, l; 130 131 cp = of_get_property(device, "compatible", &cplen); 132 if (cp == NULL) 133 return 0; 134 while (cplen > 0) { 135 if (of_compat_cmp(cp, compat, strlen(compat)) == 0) 136 return 1; 137 l = strlen(cp) + 1; 138 cp += l; 139 cplen -= l; 140 } 141 142 return 0; 143 } 144 EXPORT_SYMBOL(of_device_is_compatible); 145 146 /** 147 * of_device_is_available - check if a device is available for use 148 * 149 * @device: Node to check for availability 150 * 151 * Returns 1 if the status property is absent or set to "okay" or "ok", 152 * 0 otherwise 153 */ 154 int of_device_is_available(const struct device_node *device) 155 { 156 const char *status; 157 int statlen; 158 159 status = of_get_property(device, "status", &statlen); 160 if (status == NULL) 161 return 1; 162 163 if (statlen > 0) { 164 if (!strcmp(status, "okay") || !strcmp(status, "ok")) 165 return 1; 166 } 167 168 return 0; 169 } 170 EXPORT_SYMBOL(of_device_is_available); 171 172 /** 173 * of_get_parent - Get a node's parent if any 174 * @node: Node to get parent 175 * 176 * Returns a node pointer with refcount incremented, use 177 * of_node_put() on it when done. 178 */ 179 struct device_node *of_get_parent(const struct device_node *node) 180 { 181 struct device_node *np; 182 183 if (!node) 184 return NULL; 185 186 read_lock(&devtree_lock); 187 np = of_node_get(node->parent); 188 read_unlock(&devtree_lock); 189 return np; 190 } 191 EXPORT_SYMBOL(of_get_parent); 192 193 /** 194 * of_get_next_parent - Iterate to a node's parent 195 * @node: Node to get parent of 196 * 197 * This is like of_get_parent() except that it drops the 198 * refcount on the passed node, making it suitable for iterating 199 * through a node's parents. 200 * 201 * Returns a node pointer with refcount incremented, use 202 * of_node_put() on it when done. 203 */ 204 struct device_node *of_get_next_parent(struct device_node *node) 205 { 206 struct device_node *parent; 207 208 if (!node) 209 return NULL; 210 211 read_lock(&devtree_lock); 212 parent = of_node_get(node->parent); 213 of_node_put(node); 214 read_unlock(&devtree_lock); 215 return parent; 216 } 217 218 /** 219 * of_get_next_child - Iterate a node childs 220 * @node: parent node 221 * @prev: previous child of the parent node, or NULL to get first 222 * 223 * Returns a node pointer with refcount incremented, use 224 * of_node_put() on it when done. 225 */ 226 struct device_node *of_get_next_child(const struct device_node *node, 227 struct device_node *prev) 228 { 229 struct device_node *next; 230 231 read_lock(&devtree_lock); 232 next = prev ? prev->sibling : node->child; 233 for (; next; next = next->sibling) 234 if (of_node_get(next)) 235 break; 236 of_node_put(prev); 237 read_unlock(&devtree_lock); 238 return next; 239 } 240 EXPORT_SYMBOL(of_get_next_child); 241 242 /** 243 * of_find_node_by_path - Find a node matching a full OF path 244 * @path: The full path to match 245 * 246 * Returns a node pointer with refcount incremented, use 247 * of_node_put() on it when done. 248 */ 249 struct device_node *of_find_node_by_path(const char *path) 250 { 251 struct device_node *np = allnodes; 252 253 read_lock(&devtree_lock); 254 for (; np; np = np->allnext) { 255 if (np->full_name && (of_node_cmp(np->full_name, path) == 0) 256 && of_node_get(np)) 257 break; 258 } 259 read_unlock(&devtree_lock); 260 return np; 261 } 262 EXPORT_SYMBOL(of_find_node_by_path); 263 264 /** 265 * of_find_node_by_name - Find a node by its "name" property 266 * @from: The node to start searching from or NULL, the node 267 * you pass will not be searched, only the next one 268 * will; typically, you pass what the previous call 269 * returned. of_node_put() will be called on it 270 * @name: The name string to match against 271 * 272 * Returns a node pointer with refcount incremented, use 273 * of_node_put() on it when done. 274 */ 275 struct device_node *of_find_node_by_name(struct device_node *from, 276 const char *name) 277 { 278 struct device_node *np; 279 280 read_lock(&devtree_lock); 281 np = from ? from->allnext : allnodes; 282 for (; np; np = np->allnext) 283 if (np->name && (of_node_cmp(np->name, name) == 0) 284 && of_node_get(np)) 285 break; 286 of_node_put(from); 287 read_unlock(&devtree_lock); 288 return np; 289 } 290 EXPORT_SYMBOL(of_find_node_by_name); 291 292 /** 293 * of_find_node_by_type - Find a node by its "device_type" property 294 * @from: The node to start searching from, or NULL to start searching 295 * the entire device tree. The node you pass will not be 296 * searched, only the next one will; typically, you pass 297 * what the previous call returned. of_node_put() will be 298 * called on from for you. 299 * @type: The type string to match against 300 * 301 * Returns a node pointer with refcount incremented, use 302 * of_node_put() on it when done. 303 */ 304 struct device_node *of_find_node_by_type(struct device_node *from, 305 const char *type) 306 { 307 struct device_node *np; 308 309 read_lock(&devtree_lock); 310 np = from ? from->allnext : allnodes; 311 for (; np; np = np->allnext) 312 if (np->type && (of_node_cmp(np->type, type) == 0) 313 && of_node_get(np)) 314 break; 315 of_node_put(from); 316 read_unlock(&devtree_lock); 317 return np; 318 } 319 EXPORT_SYMBOL(of_find_node_by_type); 320 321 /** 322 * of_find_compatible_node - Find a node based on type and one of the 323 * tokens in its "compatible" property 324 * @from: The node to start searching from or NULL, the node 325 * you pass will not be searched, only the next one 326 * will; typically, you pass what the previous call 327 * returned. of_node_put() will be called on it 328 * @type: The type string to match "device_type" or NULL to ignore 329 * @compatible: The string to match to one of the tokens in the device 330 * "compatible" list. 331 * 332 * Returns a node pointer with refcount incremented, use 333 * of_node_put() on it when done. 334 */ 335 struct device_node *of_find_compatible_node(struct device_node *from, 336 const char *type, const char *compatible) 337 { 338 struct device_node *np; 339 340 read_lock(&devtree_lock); 341 np = from ? from->allnext : allnodes; 342 for (; np; np = np->allnext) { 343 if (type 344 && !(np->type && (of_node_cmp(np->type, type) == 0))) 345 continue; 346 if (of_device_is_compatible(np, compatible) && of_node_get(np)) 347 break; 348 } 349 of_node_put(from); 350 read_unlock(&devtree_lock); 351 return np; 352 } 353 EXPORT_SYMBOL(of_find_compatible_node); 354 355 /** 356 * of_find_node_with_property - Find a node which has a property with 357 * the given name. 358 * @from: The node to start searching from or NULL, the node 359 * you pass will not be searched, only the next one 360 * will; typically, you pass what the previous call 361 * returned. of_node_put() will be called on it 362 * @prop_name: The name of the property to look for. 363 * 364 * Returns a node pointer with refcount incremented, use 365 * of_node_put() on it when done. 366 */ 367 struct device_node *of_find_node_with_property(struct device_node *from, 368 const char *prop_name) 369 { 370 struct device_node *np; 371 struct property *pp; 372 373 read_lock(&devtree_lock); 374 np = from ? from->allnext : allnodes; 375 for (; np; np = np->allnext) { 376 for (pp = np->properties; pp != 0; pp = pp->next) { 377 if (of_prop_cmp(pp->name, prop_name) == 0) { 378 of_node_get(np); 379 goto out; 380 } 381 } 382 } 383 out: 384 of_node_put(from); 385 read_unlock(&devtree_lock); 386 return np; 387 } 388 EXPORT_SYMBOL(of_find_node_with_property); 389 390 /** 391 * of_match_node - Tell if an device_node has a matching of_match structure 392 * @matches: array of of device match structures to search in 393 * @node: the of device structure to match against 394 * 395 * Low level utility function used by device matching. 396 */ 397 const struct of_device_id *of_match_node(const struct of_device_id *matches, 398 const struct device_node *node) 399 { 400 while (matches->name[0] || matches->type[0] || matches->compatible[0]) { 401 int match = 1; 402 if (matches->name[0]) 403 match &= node->name 404 && !strcmp(matches->name, node->name); 405 if (matches->type[0]) 406 match &= node->type 407 && !strcmp(matches->type, node->type); 408 if (matches->compatible[0]) 409 match &= of_device_is_compatible(node, 410 matches->compatible); 411 if (match) 412 return matches; 413 matches++; 414 } 415 return NULL; 416 } 417 EXPORT_SYMBOL(of_match_node); 418 419 /** 420 * of_find_matching_node - Find a node based on an of_device_id match 421 * table. 422 * @from: The node to start searching from or NULL, the node 423 * you pass will not be searched, only the next one 424 * will; typically, you pass what the previous call 425 * returned. of_node_put() will be called on it 426 * @matches: array of of device match structures to search in 427 * 428 * Returns a node pointer with refcount incremented, use 429 * of_node_put() on it when done. 430 */ 431 struct device_node *of_find_matching_node(struct device_node *from, 432 const struct of_device_id *matches) 433 { 434 struct device_node *np; 435 436 read_lock(&devtree_lock); 437 np = from ? from->allnext : allnodes; 438 for (; np; np = np->allnext) { 439 if (of_match_node(matches, np) && of_node_get(np)) 440 break; 441 } 442 of_node_put(from); 443 read_unlock(&devtree_lock); 444 return np; 445 } 446 EXPORT_SYMBOL(of_find_matching_node); 447 448 /** 449 * of_modalias_table: Table of explicit compatible ==> modalias mappings 450 * 451 * This table allows particulare compatible property values to be mapped 452 * to modalias strings. This is useful for busses which do not directly 453 * understand the OF device tree but are populated based on data contained 454 * within the device tree. SPI and I2C are the two current users of this 455 * table. 456 * 457 * In most cases, devices do not need to be listed in this table because 458 * the modalias value can be derived directly from the compatible table. 459 * However, if for any reason a value cannot be derived, then this table 460 * provides a method to override the implicit derivation. 461 * 462 * At the moment, a single table is used for all bus types because it is 463 * assumed that the data size is small and that the compatible values 464 * should already be distinct enough to differentiate between SPI, I2C 465 * and other devices. 466 */ 467 struct of_modalias_table { 468 char *of_device; 469 char *modalias; 470 }; 471 static struct of_modalias_table of_modalias_table[] = { 472 { "fsl,mcu-mpc8349emitx", "mcu-mpc8349emitx" }, 473 { "mmc-spi-slot", "mmc_spi" }, 474 }; 475 476 /** 477 * of_modalias_node - Lookup appropriate modalias for a device node 478 * @node: pointer to a device tree node 479 * @modalias: Pointer to buffer that modalias value will be copied into 480 * @len: Length of modalias value 481 * 482 * Based on the value of the compatible property, this routine will determine 483 * an appropriate modalias value for a particular device tree node. Two 484 * separate methods are attempted to derive a modalias value. 485 * 486 * First method is to lookup the compatible value in of_modalias_table. 487 * Second is to strip off the manufacturer prefix from the first 488 * compatible entry and use the remainder as modalias 489 * 490 * This routine returns 0 on success 491 */ 492 int of_modalias_node(struct device_node *node, char *modalias, int len) 493 { 494 int i, cplen; 495 const char *compatible; 496 const char *p; 497 498 /* 1. search for exception list entry */ 499 for (i = 0; i < ARRAY_SIZE(of_modalias_table); i++) { 500 compatible = of_modalias_table[i].of_device; 501 if (!of_device_is_compatible(node, compatible)) 502 continue; 503 strlcpy(modalias, of_modalias_table[i].modalias, len); 504 return 0; 505 } 506 507 compatible = of_get_property(node, "compatible", &cplen); 508 if (!compatible) 509 return -ENODEV; 510 511 /* 2. take first compatible entry and strip manufacturer */ 512 p = strchr(compatible, ','); 513 if (!p) 514 return -ENODEV; 515 p++; 516 strlcpy(modalias, p, len); 517 return 0; 518 } 519 EXPORT_SYMBOL_GPL(of_modalias_node); 520 521 /** 522 * of_parse_phandle - Resolve a phandle property to a device_node pointer 523 * @np: Pointer to device node holding phandle property 524 * @phandle_name: Name of property holding a phandle value 525 * @index: For properties holding a table of phandles, this is the index into 526 * the table 527 * 528 * Returns the device_node pointer with refcount incremented. Use 529 * of_node_put() on it when done. 530 */ 531 struct device_node * 532 of_parse_phandle(struct device_node *np, const char *phandle_name, int index) 533 { 534 const phandle *phandle; 535 int size; 536 537 phandle = of_get_property(np, phandle_name, &size); 538 if ((!phandle) || (size < sizeof(*phandle) * (index + 1))) 539 return NULL; 540 541 return of_find_node_by_phandle(phandle[index]); 542 } 543 EXPORT_SYMBOL(of_parse_phandle); 544 545 /** 546 * of_parse_phandles_with_args - Find a node pointed by phandle in a list 547 * @np: pointer to a device tree node containing a list 548 * @list_name: property name that contains a list 549 * @cells_name: property name that specifies phandles' arguments count 550 * @index: index of a phandle to parse out 551 * @out_node: optional pointer to device_node struct pointer (will be filled) 552 * @out_args: optional pointer to arguments pointer (will be filled) 553 * 554 * This function is useful to parse lists of phandles and their arguments. 555 * Returns 0 on success and fills out_node and out_args, on error returns 556 * appropriate errno value. 557 * 558 * Example: 559 * 560 * phandle1: node1 { 561 * #list-cells = <2>; 562 * } 563 * 564 * phandle2: node2 { 565 * #list-cells = <1>; 566 * } 567 * 568 * node3 { 569 * list = <&phandle1 1 2 &phandle2 3>; 570 * } 571 * 572 * To get a device_node of the `node2' node you may call this: 573 * of_parse_phandles_with_args(node3, "list", "#list-cells", 2, &node2, &args); 574 */ 575 int of_parse_phandles_with_args(struct device_node *np, const char *list_name, 576 const char *cells_name, int index, 577 struct device_node **out_node, 578 const void **out_args) 579 { 580 int ret = -EINVAL; 581 const u32 *list; 582 const u32 *list_end; 583 int size; 584 int cur_index = 0; 585 struct device_node *node = NULL; 586 const void *args = NULL; 587 588 list = of_get_property(np, list_name, &size); 589 if (!list) { 590 ret = -ENOENT; 591 goto err0; 592 } 593 list_end = list + size / sizeof(*list); 594 595 while (list < list_end) { 596 const u32 *cells; 597 const phandle *phandle; 598 599 phandle = list++; 600 args = list; 601 602 /* one cell hole in the list = <>; */ 603 if (!*phandle) 604 goto next; 605 606 node = of_find_node_by_phandle(*phandle); 607 if (!node) { 608 pr_debug("%s: could not find phandle\n", 609 np->full_name); 610 goto err0; 611 } 612 613 cells = of_get_property(node, cells_name, &size); 614 if (!cells || size != sizeof(*cells)) { 615 pr_debug("%s: could not get %s for %s\n", 616 np->full_name, cells_name, node->full_name); 617 goto err1; 618 } 619 620 list += *cells; 621 if (list > list_end) { 622 pr_debug("%s: insufficient arguments length\n", 623 np->full_name); 624 goto err1; 625 } 626 next: 627 if (cur_index == index) 628 break; 629 630 of_node_put(node); 631 node = NULL; 632 args = NULL; 633 cur_index++; 634 } 635 636 if (!node) { 637 /* 638 * args w/o node indicates that the loop above has stopped at 639 * the 'hole' cell. Report this differently. 640 */ 641 if (args) 642 ret = -EEXIST; 643 else 644 ret = -ENOENT; 645 goto err0; 646 } 647 648 if (out_node) 649 *out_node = node; 650 if (out_args) 651 *out_args = args; 652 653 return 0; 654 err1: 655 of_node_put(node); 656 err0: 657 pr_debug("%s failed with status %d\n", __func__, ret); 658 return ret; 659 } 660 EXPORT_SYMBOL(of_parse_phandles_with_args); 661