drivers/of/fdt.c

   1 /*
   2  * Functions for working with the Flattened Device Tree data format
   3  *
   4  * Copyright 2009 Benjamin Herrenschmidt, IBM Corp
   5  * benh@kernel.crashing.org
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * version 2 as published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/initrd.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/of_fdt.h>
  17 #include <linux/string.h>
  18 #include <linux/errno.h>
  19 #include <linux/slab.h>
  20
  21 #ifdef CONFIG_PPC
  22 #include <asm/machdep.h>
  23 #endif /* CONFIG_PPC */
  24
  25 #include <asm/page.h>
  26
  27 char *of_fdt_get_string(struct boot_param_header *blob, u32 offset)
  28 {
  29         return ((char *)blob) +
  30                 be32_to_cpu(blob->off_dt_strings) + offset;
  31 }
  32
  33 /**
  34  * of_fdt_get_property - Given a node in the given flat blob, return
  35  * the property ptr
  36  */
  37 void *of_fdt_get_property(struct boot_param_header *blob,
  38                        unsigned long node, const char *name,
  39                        unsigned long *size)
  40 {
  41         unsigned long p = node;
  42
  43         do {
  44                 u32 tag = be32_to_cpup((__be32 *)p);
  45                 u32 sz, noff;
  46                 const char *nstr;
  47
  48                 p += 4;
  49                 if (tag == OF_DT_NOP)
  50                         continue;
  51                 if (tag != OF_DT_PROP)
  52                         return NULL;
  53
  54                 sz = be32_to_cpup((__be32 *)p);
  55                 noff = be32_to_cpup((__be32 *)(p + 4));
  56                 p += 8;
  57                 if (be32_to_cpu(blob->version) < 0x10)
  58                         p = ALIGN(p, sz >= 8 ? 8 : 4);
  59
  60                 nstr = of_fdt_get_string(blob, noff);
  61                 if (nstr == NULL) {
  62                         pr_warning("Can't find property index name !\n");
  63                         return NULL;
  64                 }
  65                 if (strcmp(name, nstr) == 0) {
  66                         if (size)
  67                                 *size = sz;
  68                         return (void *)p;
  69                 }
  70                 p += sz;
  71                 p = ALIGN(p, 4);
  72         } while (1);
  73 }
  74
  75 /**
  76  * of_fdt_is_compatible - Return true if given node from the given blob has
  77  * compat in its compatible list
  78  * @blob: A device tree blob
  79  * @node: node to test
  80  * @compat: compatible string to compare with compatible list.
  81  *
  82  * On match, returns a non-zero value with smaller values returned for more
  83  * specific compatible values.
  84  */
  85 int of_fdt_is_compatible(struct boot_param_header *blob,
  86                       unsigned long node, const char *compat)
  87 {
  88         const char *cp;
  89         unsigned long cplen, l, score = 0;
  90
  91         cp = of_fdt_get_property(blob, node, "compatible", &cplen);
  92         if (cp == NULL)
  93                 return 0;
  94         while (cplen > 0) {
  95                 score++;
  96                 if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
  97                         return score;
  98                 l = strlen(cp) + 1;
  99                 cp += l;
 100                 cplen -= l;
 101         }
 102
 103         return 0;
 104 }
 105
 106 /**
 107  * of_fdt_match - Return true if node matches a list of compatible values
 108  */
 109 int of_fdt_match(struct boot_param_header *blob, unsigned long node,
 110                  const char **compat)
 111 {
 112         unsigned int tmp, score = 0;
 113
 114         if (!compat)
 115                 return 0;
 116
 117         while (*compat) {
 118                 tmp = of_fdt_is_compatible(blob, node, *compat);
 119                 if (tmp && (score == 0 || (tmp < score)))
 120                         score = tmp;
 121                 compat++;
 122         }
 123
 124         return score;
 125 }
 126
 127 static void *unflatten_dt_alloc(unsigned long *mem, unsigned long size,
 128                                        unsigned long align)
 129 {
 130         void *res;
 131
 132         *mem = ALIGN(*mem, align);
 133         res = (void *)*mem;
 134         *mem += size;
 135
 136         return res;
 137 }
 138
 139 /**
 140  * unflatten_dt_node - Alloc and populate a device_node from the flat tree
 141  * @blob: The parent device tree blob
 142  * @mem: Memory chunk to use for allocating device nodes and properties
 143  * @p: pointer to node in flat tree
 144  * @dad: Parent struct device_node
 145  * @allnextpp: pointer to ->allnext from last allocated device_node
 146  * @fpsize: Size of the node path up at the current depth.
 147  */
 148 static unsigned long unflatten_dt_node(struct boot_param_header *blob,
 149                                 unsigned long mem,
 150                                 unsigned long *p,
 151                                 struct device_node *dad,
 152                                 struct device_node ***allnextpp,
 153                                 unsigned long fpsize)
 154 {
 155         struct device_node *np;
 156         struct property *pp, **prev_pp = NULL;
 157         char *pathp;
 158         u32 tag;
 159         unsigned int l, allocl;
 160         int has_name = 0;
 161         int new_format = 0;
 162
 163         tag = be32_to_cpup((__be32 *)(*p));
 164         if (tag != OF_DT_BEGIN_NODE) {
 165                 pr_err("Weird tag at start of node: %x\n", tag);
 166                 return mem;
 167         }
 168         *p += 4;
 169         pathp = (char *)*p;
 170         l = allocl = strlen(pathp) + 1;
 171         *p = ALIGN(*p + l, 4);
 172
 173         /* version 0x10 has a more compact unit name here instead of the full
 174          * path. we accumulate the full path size using "fpsize", we'll rebuild
 175          * it later. We detect this because the first character of the name is
 176          * not '/'.
 177          */
 178         if ((*pathp) != '/') {
 179                 new_format = 1;
 180                 if (fpsize == 0) {
 181                         /* root node: special case. fpsize accounts for path
 182                          * plus terminating zero. root node only has '/', so
 183                          * fpsize should be 2, but we want to avoid the first
 184                          * level nodes to have two '/' so we use fpsize 1 here
 185                          */
 186                         fpsize = 1;
 187                         allocl = 2;
 188                 } else {
 189                         /* account for '/' and path size minus terminal 0
 190                          * already in 'l'
 191                          */
 192                         fpsize += l;
 193                         allocl = fpsize;
 194                 }
 195         }
 196
 197         np = unflatten_dt_alloc(&mem, sizeof(struct device_node) + allocl,
 198                                 __alignof__(struct device_node));
 199         if (allnextpp) {
 200                 memset(np, 0, sizeof(*np));
 201                 np->full_name = ((char *)np) + sizeof(struct device_node);
 202                 if (new_format) {
 203                         char *fn = np->full_name;
 204                         /* rebuild full path for new format */
 205                         if (dad && dad->parent) {
 206                                 strcpy(fn, dad->full_name);
 207 #ifdef DEBUG
 208                                 if ((strlen(fn) + l + 1) != allocl) {
 209                                         pr_debug("%s: p: %d, l: %d, a: %d\n",
 210                                                 pathp, (int)strlen(fn),
 211                                                 l, allocl);
 212                                 }
 213 #endif
 214                                 fn += strlen(fn);
 215                         }
 216                         *(fn++) = '/';
 217                         memcpy(fn, pathp, l);
 218                 } else
 219                         memcpy(np->full_name, pathp, l);
 220                 prev_pp = &np->properties;
 221                 **allnextpp = np;
 222                 *allnextpp = &np->allnext;
 223                 if (dad != NULL) {
 224                         np->parent = dad;
 225                         /* we temporarily use the next field as `last_child'*/
 226                         if (dad->next == NULL)
 227                                 dad->child = np;
 228                         else
 229                                 dad->next->sibling = np;
 230                         dad->next = np;
 231                 }
 232                 kref_init(&np->kref);
 233         }
 234         /* process properties */
 235         while (1) {
 236                 u32 sz, noff;
 237                 char *pname;
 238
 239                 tag = be32_to_cpup((__be32 *)(*p));
 240                 if (tag == OF_DT_NOP) {
 241                         *p += 4;
 242                         continue;
 243                 }
 244                 if (tag != OF_DT_PROP)
 245                         break;
 246                 *p += 4;
 247                 sz = be32_to_cpup((__be32 *)(*p));
 248                 noff = be32_to_cpup((__be32 *)((*p) + 4));
 249                 *p += 8;
 250                 if (be32_to_cpu(blob->version) < 0x10)
 251                         *p = ALIGN(*p, sz >= 8 ? 8 : 4);
 252
 253                 pname = of_fdt_get_string(blob, noff);
 254                 if (pname == NULL) {
 255                         pr_info("Can't find property name in list !\n");
 256                         break;
 257                 }
 258                 if (strcmp(pname, "name") == 0)
 259                         has_name = 1;
 260                 l = strlen(pname) + 1;
 261                 pp = unflatten_dt_alloc(&mem, sizeof(struct property),
 262                                         __alignof__(struct property));
 263                 if (allnextpp) {
 264                         /* We accept flattened tree phandles either in
 265                          * ePAPR-style "phandle" properties, or the
 266                          * legacy "linux,phandle" properties.  If both
 267                          * appear and have different values, things
 268                          * will get weird.  Don't do that. */
 269                         if ((strcmp(pname, "phandle") == 0) ||
 270                             (strcmp(pname, "linux,phandle") == 0)) {
 271                                 if (np->phandle == 0)
 272                                         np->phandle = be32_to_cpup((__be32*)*p);
 273                         }
 274                         /* And we process the "ibm,phandle" property
 275                          * used in pSeries dynamic device tree
 276                          * stuff */
 277                         if (strcmp(pname, "ibm,phandle") == 0)
 278                                 np->phandle = be32_to_cpup((__be32 *)*p);
 279                         pp->name = pname;
 280                         pp->length = sz;
 281                         pp->value = (void *)*p;
 282                         *prev_pp = pp;
 283                         prev_pp = &pp->next;
 284                 }
 285                 *p = ALIGN((*p) + sz, 4);
 286         }
 287         /* with version 0x10 we may not have the name property, recreate
 288          * it here from the unit name if absent
 289          */
 290         if (!has_name) {
 291                 char *p1 = pathp, *ps = pathp, *pa = NULL;
 292                 int sz;
 293
 294                 while (*p1) {
 295                         if ((*p1) == '@')
 296                                 pa = p1;
 297                         if ((*p1) == '/')
 298                                 ps = p1 + 1;
 299                         p1++;
 300                 }
 301                 if (pa < ps)
 302                         pa = p1;
 303                 sz = (pa - ps) + 1;
 304                 pp = unflatten_dt_alloc(&mem, sizeof(struct property) + sz,
 305                                         __alignof__(struct property));
 306                 if (allnextpp) {
 307                         pp->name = "name";
 308                         pp->length = sz;
 309                         pp->value = pp + 1;
 310                         *prev_pp = pp;
 311                         prev_pp = &pp->next;
 312                         memcpy(pp->value, ps, sz - 1);
 313                         ((char *)pp->value)[sz - 1] = 0;
 314                         pr_debug("fixed up name for %s -> %s\n", pathp,
 315                                 (char *)pp->value);
 316                 }
 317         }
 318         if (allnextpp) {
 319                 *prev_pp = NULL;
 320                 np->name = of_get_property(np, "name", NULL);
 321                 np->type = of_get_property(np, "device_type", NULL);
 322
 323                 if (!np->name)
 324                         np->name = "<NULL>";
 325                 if (!np->type)
 326                         np->type = "<NULL>";
 327         }
 328         while (tag == OF_DT_BEGIN_NODE || tag == OF_DT_NOP) {
 329                 if (tag == OF_DT_NOP)
 330                         *p += 4;
 331                 else
 332                         mem = unflatten_dt_node(blob, mem, p, np, allnextpp,
 333                                                 fpsize);
 334                 tag = be32_to_cpup((__be32 *)(*p));
 335         }
 336         if (tag != OF_DT_END_NODE) {
 337                 pr_err("Weird tag at end of node: %x\n", tag);
 338                 return mem;
 339         }
 340         *p += 4;
 341         return mem;
 342 }
 343
 344 /**
 345  * __unflatten_device_tree - create tree of device_nodes from flat blob
 346  *
 347  * unflattens a device-tree, creating the
 348  * tree of struct device_node. It also fills the "name" and "type"
 349  * pointers of the nodes so the normal device-tree walking functions
 350  * can be used.
 351  * @blob: The blob to expand
 352  * @mynodes: The device_node tree created by the call
 353  * @dt_alloc: An allocator that provides a virtual address to memory
 354  * for the resulting tree
 355  */
 356 static void __unflatten_device_tree(struct boot_param_header *blob,
 357                              struct device_node **mynodes,
 358                              void * (*dt_alloc)(u64 size, u64 align))
 359 {
 360         unsigned long start, mem, size;
 361         struct device_node **allnextp = mynodes;
 362
 363         pr_debug(" -> unflatten_device_tree()\n");
 364
 365         if (!blob) {
 366                 pr_debug("No device tree pointer\n");
 367                 return;
 368         }
 369
 370         pr_debug("Unflattening device tree:\n");
 371         pr_debug("magic: %08x\n", be32_to_cpu(blob->magic));
 372         pr_debug("size: %08x\n", be32_to_cpu(blob->totalsize));
 373         pr_debug("version: %08x\n", be32_to_cpu(blob->version));
 374
 375         if (be32_to_cpu(blob->magic) != OF_DT_HEADER) {
 376                 pr_err("Invalid device tree blob header\n");
 377                 return;
 378         }
 379
 380         /* First pass, scan for size */
 381         start = ((unsigned long)blob) +
 382                 be32_to_cpu(blob->off_dt_struct);
 383         size = unflatten_dt_node(blob, 0, &start, NULL, NULL, 0);
 384         size = (size | 3) + 1;
 385
 386         pr_debug("  size is %lx, allocating...\n", size);
 387
 388         /* Allocate memory for the expanded device tree */
 389         mem = (unsigned long)
 390                 dt_alloc(size + 4, __alignof__(struct device_node));
 391
 392         ((__be32 *)mem)[size / 4] = cpu_to_be32(0xdeadbeef);
 393
 394         pr_debug("  unflattening %lx...\n", mem);
 395
 396         /* Second pass, do actual unflattening */
 397         start = ((unsigned long)blob) +
 398                 be32_to_cpu(blob->off_dt_struct);
 399         unflatten_dt_node(blob, mem, &start, NULL, &allnextp, 0);
 400         if (be32_to_cpup((__be32 *)start) != OF_DT_END)
 401                 pr_warning("Weird tag at end of tree: %08x\n", *((u32 *)start));
 402         if (be32_to_cpu(((__be32 *)mem)[size / 4]) != 0xdeadbeef)
 403                 pr_warning("End of tree marker overwritten: %08x\n",
 404                            be32_to_cpu(((__be32 *)mem)[size / 4]));
 405         *allnextp = NULL;
 406
 407         pr_debug(" <- unflatten_device_tree()\n");
 408 }
 409
 410 static void *kernel_tree_alloc(u64 size, u64 align)
 411 {
 412         return kzalloc(size, GFP_KERNEL);
 413 }
 414
 415 /**
 416  * of_fdt_unflatten_tree - create tree of device_nodes from flat blob
 417  *
 418  * unflattens the device-tree passed by the firmware, creating the
 419  * tree of struct device_node. It also fills the "name" and "type"
 420  * pointers of the nodes so the normal device-tree walking functions
 421  * can be used.
 422  */
 423 void of_fdt_unflatten_tree(unsigned long *blob,
 424                         struct device_node **mynodes)
 425 {
 426         struct boot_param_header *device_tree =
 427                 (struct boot_param_header *)blob;
 428         __unflatten_device_tree(device_tree, mynodes, &kernel_tree_alloc);
 429 }
 430 EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree);
 431
 432 /* Everything below here references initial_boot_params directly. */
 433 int __initdata dt_root_addr_cells;
 434 int __initdata dt_root_size_cells;
 435
 436 struct boot_param_header *initial_boot_params;
 437
 438 #ifdef CONFIG_OF_EARLY_FLATTREE
 439
 440 /**
 441  * of_scan_flat_dt - scan flattened tree blob and call callback on each.
 442  * @it: callback function
 443  * @data: context data pointer
 444  *
 445  * This function is used to scan the flattened device-tree, it is
 446  * used to extract the memory information at boot before we can
 447  * unflatten the tree
 448  */
 449 int __init of_scan_flat_dt(int (*it)(unsigned long node,
 450                                      const char *uname, int depth,
 451                                      void *data),
 452                            void *data)
 453 {
 454         unsigned long p = ((unsigned long)initial_boot_params) +
 455                 be32_to_cpu(initial_boot_params->off_dt_struct);
 456         int rc = 0;
 457         int depth = -1;
 458
 459         do {
 460                 u32 tag = be32_to_cpup((__be32 *)p);
 461                 char *pathp;
 462
 463                 p += 4;
 464                 if (tag == OF_DT_END_NODE) {
 465                         depth--;
 466                         continue;
 467                 }
 468                 if (tag == OF_DT_NOP)
 469                         continue;
 470                 if (tag == OF_DT_END)
 471                         break;
 472                 if (tag == OF_DT_PROP) {
 473                         u32 sz = be32_to_cpup((__be32 *)p);
 474                         p += 8;
 475                         if (be32_to_cpu(initial_boot_params->version) < 0x10)
 476                                 p = ALIGN(p, sz >= 8 ? 8 : 4);
 477                         p += sz;
 478                         p = ALIGN(p, 4);
 479                         continue;
 480                 }
 481                 if (tag != OF_DT_BEGIN_NODE) {
 482                         pr_err("Invalid tag %x in flat device tree!\n", tag);
 483                         return -EINVAL;
 484                 }
 485                 depth++;
 486                 pathp = (char *)p;
 487                 p = ALIGN(p + strlen(pathp) + 1, 4);
 488                 if ((*pathp) == '/') {
 489                         char *lp, *np;
 490                         for (lp = NULL, np = pathp; *np; np++)
 491                                 if ((*np) == '/')
 492                                         lp = np+1;
 493                         if (lp != NULL)
 494                                 pathp = lp;
 495                 }
 496                 rc = it(p, pathp, depth, data);
 497                 if (rc != 0)
 498                         break;
 499         } while (1);
 500
 501         return rc;
 502 }
 503
 504 /**
 505  * of_get_flat_dt_root - find the root node in the flat blob
 506  */
 507 unsigned long __init of_get_flat_dt_root(void)
 508 {
 509         unsigned long p = ((unsigned long)initial_boot_params) +
 510                 be32_to_cpu(initial_boot_params->off_dt_struct);
 511
 512         while (be32_to_cpup((__be32 *)p) == OF_DT_NOP)
 513                 p += 4;
 514         BUG_ON(be32_to_cpup((__be32 *)p) != OF_DT_BEGIN_NODE);
 515         p += 4;
 516         return ALIGN(p + strlen((char *)p) + 1, 4);
 517 }
 518
 519 /**
 520  * of_get_flat_dt_prop - Given a node in the flat blob, return the property ptr
 521  *
 522  * This function can be used within scan_flattened_dt callback to get
 523  * access to properties
 524  */
 525 void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
 526                                  unsigned long *size)
 527 {
 528         return of_fdt_get_property(initial_boot_params, node, name, size);
 529 }
 530
 531 /**
 532  * of_flat_dt_is_compatible - Return true if given node has compat in compatible list
 533  * @node: node to test
 534  * @compat: compatible string to compare with compatible list.
 535  */
 536 int __init of_flat_dt_is_compatible(unsigned long node, const char *compat)
 537 {
 538         return of_fdt_is_compatible(initial_boot_params, node, compat);
 539 }
 540
 541 /**
 542  * of_flat_dt_match - Return true if node matches a list of compatible values
 543  */
 544 int __init of_flat_dt_match(unsigned long node, const char **compat)
 545 {
 546         return of_fdt_match(initial_boot_params, node, compat);
 547 }
 548
 549 #ifdef CONFIG_BLK_DEV_INITRD
 550 /**
 551  * early_init_dt_check_for_initrd - Decode initrd location from flat tree
 552  * @node: reference to node containing initrd location ('chosen')
 553  */
 554 void __init early_init_dt_check_for_initrd(unsigned long node)
 555 {
 556         unsigned long start, end, len;
 557         __be32 *prop;
 558
 559         pr_debug("Looking for initrd properties... ");
 560
 561         prop = of_get_flat_dt_prop(node, "linux,initrd-start", &len);
 562         if (!prop)
 563                 return;
 564         start = of_read_ulong(prop, len/4);
 565
 566         prop = of_get_flat_dt_prop(node, "linux,initrd-end", &len);
 567         if (!prop)
 568                 return;
 569         end = of_read_ulong(prop, len/4);
 570
 571         early_init_dt_setup_initrd_arch(start, end);
 572         pr_debug("initrd_start=0x%lx  initrd_end=0x%lx\n", start, end);
 573 }
 574 #else
 575 inline void early_init_dt_check_for_initrd(unsigned long node)
 576 {
 577 }
 578 #endif /* CONFIG_BLK_DEV_INITRD */
 579
 580 /**
 581  * early_init_dt_scan_root - fetch the top level address and size cells
 582  */
 583 int __init early_init_dt_scan_root(unsigned long node, const char *uname,
 584                                    int depth, void *data)
 585 {
 586         __be32 *prop;
 587
 588         if (depth != 0)
 589                 return 0;
 590
 591         dt_root_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
 592         dt_root_addr_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
 593
 594         prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
 595         if (prop)
 596                 dt_root_size_cells = be32_to_cpup(prop);
 597         pr_debug("dt_root_size_cells = %x\n", dt_root_size_cells);
 598
 599         prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
 600         if (prop)
 601                 dt_root_addr_cells = be32_to_cpup(prop);
 602         pr_debug("dt_root_addr_cells = %x\n", dt_root_addr_cells);
 603
 604         /* break now */
 605         return 1;
 606 }
 607
 608 u64 __init dt_mem_next_cell(int s, __be32 **cellp)
 609 {
 610         __be32 *p = *cellp;
 611
 612         *cellp = p + s;
 613         return of_read_number(p, s);
 614 }
 615
 616 /**
 617  * early_init_dt_scan_memory - Look for an parse memory nodes
 618  */
 619 int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
 620                                      int depth, void *data)
 621 {
 622         char *type = of_get_flat_dt_prop(node, "device_type", NULL);
 623         __be32 *reg, *endp;
 624         unsigned long l;
 625
 626         /* We are scanning "memory" nodes only */
 627         if (type == NULL) {
 628                 /*
 629                  * The longtrail doesn't have a device_type on the
 630                  * /memory node, so look for the node called /memory@0.
 631                  */
 632                 if (depth != 1 || strcmp(uname, "memory@0") != 0)
 633                         return 0;
 634         } else if (strcmp(type, "memory") != 0)
 635                 return 0;
 636
 637         reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
 638         if (reg == NULL)
 639                 reg = of_get_flat_dt_prop(node, "reg", &l);
 640         if (reg == NULL)
 641                 return 0;
 642
 643         endp = reg + (l / sizeof(__be32));
 644
 645         pr_debug("memory scan node %s, reg size %ld, data: %x %x %x %x,\n",
 646             uname, l, reg[0], reg[1], reg[2], reg[3]);
 647
 648         while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
 649                 u64 base, size;
 650
 651                 base = dt_mem_next_cell(dt_root_addr_cells, &reg);
 652                 size = dt_mem_next_cell(dt_root_size_cells, &reg);
 653
 654                 if (size == 0)
 655                         continue;
 656                 pr_debug(" - %llx ,  %llx\n", (unsigned long long)base,
 657                     (unsigned long long)size);
 658
 659                 early_init_dt_add_memory_arch(base, size);
 660         }
 661
 662         return 0;
 663 }
 664
 665 int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 666                                      int depth, void *data)
 667 {
 668         unsigned long l;
 669         char *p;
 670
 671         pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
 672
 673         if (depth != 1 || !data ||
 674             (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
 675                 return 0;
 676
 677         early_init_dt_check_for_initrd(node);
 678
 679         /* Retrieve command line */
 680         p = of_get_flat_dt_prop(node, "bootargs", &l);
 681         if (p != NULL && l > 0)
 682                 strlcpy(data, p, min((int)l, COMMAND_LINE_SIZE));
 683
 684         /*
 685          * CONFIG_CMDLINE is meant to be a default in case nothing else
 686          * managed to set the command line, unless CONFIG_CMDLINE_FORCE
 687          * is set in which case we override whatever was found earlier.
 688          */
 689 #ifdef CONFIG_CMDLINE
 690 #ifndef CONFIG_CMDLINE_FORCE
 691         if (!((char *)data)[0])
 692 #endif
 693                 strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 694 #endif /* CONFIG_CMDLINE */
 695
 696         pr_debug("Command line is: %s\n", (char*)data);
 697
 698         /* break now */
 699         return 1;
 700 }
 701
 702 /**
 703  * unflatten_device_tree - create tree of device_nodes from flat blob
 704  *
 705  * unflattens the device-tree passed by the firmware, creating the
 706  * tree of struct device_node. It also fills the "name" and "type"
 707  * pointers of the nodes so the normal device-tree walking functions
 708  * can be used.
 709  */
 710 void __init unflatten_device_tree(void)
 711 {
 712         __unflatten_device_tree(initial_boot_params, &allnodes,
 713                                 early_init_dt_alloc_memory_arch);
 714
 715         /* Get pointer to "/chosen" and "/aliasas" nodes for use everywhere */
 716         of_alias_scan(early_init_dt_alloc_memory_arch);
 717 }
 718
 719 #endif /* CONFIG_OF_EARLY_FLATTREE */