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