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/setup.h>
  27 #include <asm/page.h>
  28
  29 char *of_fdt_get_string(struct boot_param_header *blob, u32 offset)
  30 {
  31         return ((char *)blob) +
  32                 be32_to_cpu(blob->off_dt_strings) + offset;
  33 }
  34
  35 /**
  36  * of_fdt_get_property - Given a node in the given flat blob, return
  37  * the property ptr
  38  */
  39 void *of_fdt_get_property(struct boot_param_header *blob,
  40                        unsigned long node, const char *name,
  41                        unsigned long *size)
  42 {
  43         unsigned long p = node;
  44
  45         do {
  46                 u32 tag = be32_to_cpup((__be32 *)p);
  47                 u32 sz, noff;
  48                 const char *nstr;
  49
  50                 p += 4;
  51                 if (tag == OF_DT_NOP)
  52                         continue;
  53                 if (tag != OF_DT_PROP)
  54                         return NULL;
  55
  56                 sz = be32_to_cpup((__be32 *)p);
  57                 noff = be32_to_cpup((__be32 *)(p + 4));
  58                 p += 8;
  59                 if (be32_to_cpu(blob->version) < 0x10)
  60                         p = ALIGN(p, sz >= 8 ? 8 : 4);
  61
  62                 nstr = of_fdt_get_string(blob, noff);
  63                 if (nstr == NULL) {
  64                         pr_warning("Can't find property index name !\n");
  65                         return NULL;
  66                 }
  67                 if (strcmp(name, nstr) == 0) {
  68                         if (size)
  69                                 *size = sz;
  70                         return (void *)p;
  71                 }
  72                 p += sz;
  73                 p = ALIGN(p, 4);
  74         } while (1);
  75 }
  76
  77 /**
  78  * of_fdt_is_compatible - Return true if given node from the given blob has
  79  * compat in its compatible list
  80  * @blob: A device tree blob
  81  * @node: node to test
  82  * @compat: compatible string to compare with compatible list.
  83  *
  84  * On match, returns a non-zero value with smaller values returned for more
  85  * specific compatible values.
  86  */
  87 int of_fdt_is_compatible(struct boot_param_header *blob,
  88                       unsigned long node, const char *compat)
  89 {
  90         const char *cp;
  91         unsigned long cplen, l, score = 0;
  92
  93         cp = of_fdt_get_property(blob, node, "compatible", &cplen);
  94         if (cp == NULL)
  95                 return 0;
  96         while (cplen > 0) {
  97                 score++;
  98                 if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
  99                         return score;
 100                 l = strlen(cp) + 1;
 101                 cp += l;
 102                 cplen -= l;
 103         }
 104
 105         return 0;
 106 }
 107
 108 /**
 109  * of_fdt_match - Return true if node matches a list of compatible values
 110  */
 111 int of_fdt_match(struct boot_param_header *blob, unsigned long node,
 112                  const char *const *compat)
 113 {
 114         unsigned int tmp, score = 0;
 115
 116         if (!compat)
 117                 return 0;
 118
 119         while (*compat) {
 120                 tmp = of_fdt_is_compatible(blob, node, *compat);
 121                 if (tmp && (score == 0 || (tmp < score)))
 122                         score = tmp;
 123                 compat++;
 124         }
 125
 126         return score;
 127 }
 128
 129 static void *unflatten_dt_alloc(unsigned long *mem, unsigned long size,
 130                                        unsigned long align)
 131 {
 132         void *res;
 133
 134         *mem = ALIGN(*mem, align);
 135         res = (void *)*mem;
 136         *mem += size;
 137
 138         return res;
 139 }
 140
 141 /**
 142  * unflatten_dt_node - Alloc and populate a device_node from the flat tree
 143  * @blob: The parent device tree blob
 144  * @mem: Memory chunk to use for allocating device nodes and properties
 145  * @p: pointer to node in flat tree
 146  * @dad: Parent struct device_node
 147  * @allnextpp: pointer to ->allnext from last allocated device_node
 148  * @fpsize: Size of the node path up at the current depth.
 149  */
 150 static unsigned long unflatten_dt_node(struct boot_param_header *blob,
 151                                 unsigned long mem,
 152                                 unsigned long *p,
 153                                 struct device_node *dad,
 154                                 struct device_node ***allnextpp,
 155                                 unsigned long fpsize)
 156 {
 157         struct device_node *np;
 158         struct property *pp, **prev_pp = NULL;
 159         char *pathp;
 160         u32 tag;
 161         unsigned int l, allocl;
 162         int has_name = 0;
 163         int new_format = 0;
 164
 165         tag = be32_to_cpup((__be32 *)(*p));
 166         if (tag != OF_DT_BEGIN_NODE) {
 167                 pr_err("Weird tag at start of node: %x\n", tag);
 168                 return mem;
 169         }
 170         *p += 4;
 171         pathp = (char *)*p;
 172         l = allocl = strlen(pathp) + 1;
 173         *p = ALIGN(*p + l, 4);
 174
 175         /* version 0x10 has a more compact unit name here instead of the full
 176          * path. we accumulate the full path size using "fpsize", we'll rebuild
 177          * it later. We detect this because the first character of the name is
 178          * not '/'.
 179          */
 180         if ((*pathp) != '/') {
 181                 new_format = 1;
 182                 if (fpsize == 0) {
 183                         /* root node: special case. fpsize accounts for path
 184                          * plus terminating zero. root node only has '/', so
 185                          * fpsize should be 2, but we want to avoid the first
 186                          * level nodes to have two '/' so we use fpsize 1 here
 187                          */
 188                         fpsize = 1;
 189                         allocl = 2;
 190                 } else {
 191                         /* account for '/' and path size minus terminal 0
 192                          * already in 'l'
 193                          */
 194                         fpsize += l;
 195                         allocl = fpsize;
 196                 }
 197         }
 198
 199         np = unflatten_dt_alloc(&mem, sizeof(struct device_node) + allocl,
 200                                 __alignof__(struct device_node));
 201         if (allnextpp) {
 202                 memset(np, 0, sizeof(*np));
 203                 np->full_name = ((char *)np) + sizeof(struct device_node);
 204                 if (new_format) {
 205                         char *fn = np->full_name;
 206                         /* rebuild full path for new format */
 207                         if (dad && dad->parent) {
 208                                 strcpy(fn, dad->full_name);
 209 #ifdef DEBUG
 210                                 if ((strlen(fn) + l + 1) != allocl) {
 211                                         pr_debug("%s: p: %d, l: %d, a: %d\n",
 212                                                 pathp, (int)strlen(fn),
 213                                                 l, allocl);
 214                                 }
 215 #endif
 216                                 fn += strlen(fn);
 217                         }
 218                         *(fn++) = '/';
 219                         memcpy(fn, pathp, l);
 220                 } else
 221                         memcpy(np->full_name, pathp, l);
 222                 prev_pp = &np->properties;
 223                 **allnextpp = np;
 224                 *allnextpp = &np->allnext;
 225                 if (dad != NULL) {
 226                         np->parent = dad;
 227                         /* we temporarily use the next field as `last_child'*/
 228                         if (dad->next == NULL)
 229                                 dad->child = np;
 230                         else
 231                                 dad->next->sibling = np;
 232                         dad->next = np;
 233                 }
 234                 kref_init(&np->kref);
 235         }
 236         /* process properties */
 237         while (1) {
 238                 u32 sz, noff;
 239                 char *pname;
 240
 241                 tag = be32_to_cpup((__be32 *)(*p));
 242                 if (tag == OF_DT_NOP) {
 243                         *p += 4;
 244                         continue;
 245                 }
 246                 if (tag != OF_DT_PROP)
 247                         break;
 248                 *p += 4;
 249                 sz = be32_to_cpup((__be32 *)(*p));
 250                 noff = be32_to_cpup((__be32 *)((*p) + 4));
 251                 *p += 8;
 252                 if (be32_to_cpu(blob->version) < 0x10)
 253                         *p = ALIGN(*p, sz >= 8 ? 8 : 4);
 254
 255                 pname = of_fdt_get_string(blob, noff);
 256                 if (pname == NULL) {
 257                         pr_info("Can't find property name in list !\n");
 258                         break;
 259                 }
 260                 if (strcmp(pname, "name") == 0)
 261                         has_name = 1;
 262                 l = strlen(pname) + 1;
 263                 pp = unflatten_dt_alloc(&mem, sizeof(struct property),
 264                                         __alignof__(struct property));
 265                 if (allnextpp) {
 266                         /* We accept flattened tree phandles either in
 267                          * ePAPR-style "phandle" properties, or the
 268                          * legacy "linux,phandle" properties.  If both
 269                          * appear and have different values, things
 270                          * will get weird.  Don't do that. */
 271                         if ((strcmp(pname, "phandle") == 0) ||
 272                             (strcmp(pname, "linux,phandle") == 0)) {
 273                                 if (np->phandle == 0)
 274                                         np->phandle = be32_to_cpup((__be32*)*p);
 275                         }
 276                         /* And we process the "ibm,phandle" property
 277                          * used in pSeries dynamic device tree
 278                          * stuff */
 279                         if (strcmp(pname, "ibm,phandle") == 0)
 280                                 np->phandle = be32_to_cpup((__be32 *)*p);
 281                         pp->name = pname;
 282                         pp->length = sz;
 283                         pp->value = (void *)*p;
 284                         *prev_pp = pp;
 285                         prev_pp = &pp->next;
 286                 }
 287                 *p = ALIGN((*p) + sz, 4);
 288         }
 289         /* with version 0x10 we may not have the name property, recreate
 290          * it here from the unit name if absent
 291          */
 292         if (!has_name) {
 293                 char *p1 = pathp, *ps = pathp, *pa = NULL;
 294                 int sz;
 295
 296                 while (*p1) {
 297                         if ((*p1) == '@')
 298                                 pa = p1;
 299                         if ((*p1) == '/')
 300                                 ps = p1 + 1;
 301                         p1++;
 302                 }
 303                 if (pa < ps)
 304                         pa = p1;
 305                 sz = (pa - ps) + 1;
 306                 pp = unflatten_dt_alloc(&mem, sizeof(struct property) + sz,
 307                                         __alignof__(struct property));
 308                 if (allnextpp) {
 309                         pp->name = "name";
 310                         pp->length = sz;
 311                         pp->value = pp + 1;
 312                         *prev_pp = pp;
 313                         prev_pp = &pp->next;
 314                         memcpy(pp->value, ps, sz - 1);
 315                         ((char *)pp->value)[sz - 1] = 0;
 316                         pr_debug("fixed up name for %s -> %s\n", pathp,
 317                                 (char *)pp->value);
 318                 }
 319         }
 320         if (allnextpp) {
 321                 *prev_pp = NULL;
 322                 np->name = of_get_property(np, "name", NULL);
 323                 np->type = of_get_property(np, "device_type", NULL);
 324
 325                 if (!np->name)
 326                         np->name = "<NULL>";
 327                 if (!np->type)
 328                         np->type = "<NULL>";
 329         }
 330         while (tag == OF_DT_BEGIN_NODE || tag == OF_DT_NOP) {
 331                 if (tag == OF_DT_NOP)
 332                         *p += 4;
 333                 else
 334                         mem = unflatten_dt_node(blob, mem, p, np, allnextpp,
 335                                                 fpsize);
 336                 tag = be32_to_cpup((__be32 *)(*p));
 337         }
 338         if (tag != OF_DT_END_NODE) {
 339                 pr_err("Weird tag at end of node: %x\n", tag);
 340                 return mem;
 341         }
 342         *p += 4;
 343         return mem;
 344 }
 345
 346 /**
 347  * __unflatten_device_tree - create tree of device_nodes from flat blob
 348  *
 349  * unflattens a device-tree, creating the
 350  * tree of struct device_node. It also fills the "name" and "type"
 351  * pointers of the nodes so the normal device-tree walking functions
 352  * can be used.
 353  * @blob: The blob to expand
 354  * @mynodes: The device_node tree created by the call
 355  * @dt_alloc: An allocator that provides a virtual address to memory
 356  * for the resulting tree
 357  */
 358 static void __unflatten_device_tree(struct boot_param_header *blob,
 359                              struct device_node **mynodes,
 360                              void * (*dt_alloc)(u64 size, u64 align))
 361 {
 362         unsigned long start, mem, size;
 363         struct device_node **allnextp = mynodes;
 364
 365         pr_debug(" -> unflatten_device_tree()\n");
 366
 367         if (!blob) {
 368                 pr_debug("No device tree pointer\n");
 369                 return;
 370         }
 371
 372         pr_debug("Unflattening device tree:\n");
 373         pr_debug("magic: %08x\n", be32_to_cpu(blob->magic));
 374         pr_debug("size: %08x\n", be32_to_cpu(blob->totalsize));
 375         pr_debug("version: %08x\n", be32_to_cpu(blob->version));
 376
 377         if (be32_to_cpu(blob->magic) != OF_DT_HEADER) {
 378                 pr_err("Invalid device tree blob header\n");
 379                 return;
 380         }
 381
 382         /* First pass, scan for size */
 383         start = ((unsigned long)blob) +
 384                 be32_to_cpu(blob->off_dt_struct);
 385         size = unflatten_dt_node(blob, 0, &start, NULL, NULL, 0);
 386         size = (size | 3) + 1;
 387
 388         pr_debug("  size is %lx, allocating...\n", size);
 389
 390         /* Allocate memory for the expanded device tree */
 391         mem = (unsigned long)
 392                 dt_alloc(size + 4, __alignof__(struct device_node));
 393
 394         ((__be32 *)mem)[size / 4] = cpu_to_be32(0xdeadbeef);
 395
 396         pr_debug("  unflattening %lx...\n", mem);
 397
 398         /* Second pass, do actual unflattening */
 399         start = ((unsigned long)blob) +
 400                 be32_to_cpu(blob->off_dt_struct);
 401         unflatten_dt_node(blob, mem, &start, NULL, &allnextp, 0);
 402         if (be32_to_cpup((__be32 *)start) != OF_DT_END)
 403                 pr_warning("Weird tag at end of tree: %08x\n", *((u32 *)start));
 404         if (be32_to_cpu(((__be32 *)mem)[size / 4]) != 0xdeadbeef)
 405                 pr_warning("End of tree marker overwritten: %08x\n",
 406                            be32_to_cpu(((__be32 *)mem)[size / 4]));
 407         *allnextp = NULL;
 408
 409         pr_debug(" <- unflatten_device_tree()\n");
 410 }
 411
 412 static void *kernel_tree_alloc(u64 size, u64 align)
 413 {
 414         return kzalloc(size, GFP_KERNEL);
 415 }
 416
 417 /**
 418  * of_fdt_unflatten_tree - create tree of device_nodes from flat blob
 419  *
 420  * unflattens the device-tree passed by the firmware, creating the
 421  * tree of struct device_node. It also fills the "name" and "type"
 422  * pointers of the nodes so the normal device-tree walking functions
 423  * can be used.
 424  */
 425 void of_fdt_unflatten_tree(unsigned long *blob,
 426                         struct device_node **mynodes)
 427 {
 428         struct boot_param_header *device_tree =
 429                 (struct boot_param_header *)blob;
 430         __unflatten_device_tree(device_tree, mynodes, &kernel_tree_alloc);
 431 }
 432 EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree);
 433
 434 /* Everything below here references initial_boot_params directly. */
 435 int __initdata dt_root_addr_cells;
 436 int __initdata dt_root_size_cells;
 437
 438 struct boot_param_header *initial_boot_params;
 439
 440 #ifdef CONFIG_OF_EARLY_FLATTREE
 441
 442 /**
 443  * of_scan_flat_dt - scan flattened tree blob and call callback on each.
 444  * @it: callback function
 445  * @data: context data pointer
 446  *
 447  * This function is used to scan the flattened device-tree, it is
 448  * used to extract the memory information at boot before we can
 449  * unflatten the tree
 450  */
 451 int __init of_scan_flat_dt(int (*it)(unsigned long node,
 452                                      const char *uname, int depth,
 453                                      void *data),
 454                            void *data)
 455 {
 456         unsigned long p = ((unsigned long)initial_boot_params) +
 457                 be32_to_cpu(initial_boot_params->off_dt_struct);
 458         int rc = 0;
 459         int depth = -1;
 460
 461         do {
 462                 u32 tag = be32_to_cpup((__be32 *)p);
 463                 char *pathp;
 464
 465                 p += 4;
 466                 if (tag == OF_DT_END_NODE) {
 467                         depth--;
 468                         continue;
 469                 }
 470                 if (tag == OF_DT_NOP)
 471                         continue;
 472                 if (tag == OF_DT_END)
 473                         break;
 474                 if (tag == OF_DT_PROP) {
 475                         u32 sz = be32_to_cpup((__be32 *)p);
 476                         p += 8;
 477                         if (be32_to_cpu(initial_boot_params->version) < 0x10)
 478                                 p = ALIGN(p, sz >= 8 ? 8 : 4);
 479                         p += sz;
 480                         p = ALIGN(p, 4);
 481                         continue;
 482                 }
 483                 if (tag != OF_DT_BEGIN_NODE) {
 484                         pr_err("Invalid tag %x in flat device tree!\n", tag);
 485                         return -EINVAL;
 486                 }
 487                 depth++;
 488                 pathp = (char *)p;
 489                 p = ALIGN(p + strlen(pathp) + 1, 4);
 490                 if ((*pathp) == '/') {
 491                         char *lp, *np;
 492                         for (lp = NULL, np = pathp; *np; np++)
 493                                 if ((*np) == '/')
 494                                         lp = np+1;
 495                         if (lp != NULL)
 496                                 pathp = lp;
 497                 }
 498                 rc = it(p, pathp, depth, data);
 499                 if (rc != 0)
 500                         break;
 501         } while (1);
 502
 503         return rc;
 504 }
 505
 506 /**
 507  * of_get_flat_dt_root - find the root node in the flat blob
 508  */
 509 unsigned long __init of_get_flat_dt_root(void)
 510 {
 511         unsigned long p = ((unsigned long)initial_boot_params) +
 512                 be32_to_cpu(initial_boot_params->off_dt_struct);
 513
 514         while (be32_to_cpup((__be32 *)p) == OF_DT_NOP)
 515                 p += 4;
 516         BUG_ON(be32_to_cpup((__be32 *)p) != OF_DT_BEGIN_NODE);
 517         p += 4;
 518         return ALIGN(p + strlen((char *)p) + 1, 4);
 519 }
 520
 521 /**
 522  * of_get_flat_dt_prop - Given a node in the flat blob, return the property ptr
 523  *
 524  * This function can be used within scan_flattened_dt callback to get
 525  * access to properties
 526  */
 527 void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
 528                                  unsigned long *size)
 529 {
 530         return of_fdt_get_property(initial_boot_params, node, name, size);
 531 }
 532
 533 /**
 534  * of_flat_dt_is_compatible - Return true if given node has compat in compatible list
 535  * @node: node to test
 536  * @compat: compatible string to compare with compatible list.
 537  */
 538 int __init of_flat_dt_is_compatible(unsigned long node, const char *compat)
 539 {
 540         return of_fdt_is_compatible(initial_boot_params, node, compat);
 541 }
 542
 543 /**
 544  * of_flat_dt_match - Return true if node matches a list of compatible values
 545  */
 546 int __init of_flat_dt_match(unsigned long node, const char *const *compat)
 547 {
 548         return of_fdt_match(initial_boot_params, node, compat);
 549 }
 550
 551 #ifdef CONFIG_BLK_DEV_INITRD
 552 /**
 553  * early_init_dt_check_for_initrd - Decode initrd location from flat tree
 554  * @node: reference to node containing initrd location ('chosen')
 555  */
 556 void __init early_init_dt_check_for_initrd(unsigned long node)
 557 {
 558         unsigned long start, end, len;
 559         __be32 *prop;
 560
 561         pr_debug("Looking for initrd properties... ");
 562
 563         prop = of_get_flat_dt_prop(node, "linux,initrd-start", &len);
 564         if (!prop)
 565                 return;
 566         start = of_read_ulong(prop, len/4);
 567
 568         prop = of_get_flat_dt_prop(node, "linux,initrd-end", &len);
 569         if (!prop)
 570                 return;
 571         end = of_read_ulong(prop, len/4);
 572
 573         early_init_dt_setup_initrd_arch(start, end);
 574         pr_debug("initrd_start=0x%lx  initrd_end=0x%lx\n", start, end);
 575 }
 576 #else
 577 inline void early_init_dt_check_for_initrd(unsigned long node)
 578 {
 579 }
 580 #endif /* CONFIG_BLK_DEV_INITRD */
 581
 582 /**
 583  * early_init_dt_scan_root - fetch the top level address and size cells
 584  */
 585 int __init early_init_dt_scan_root(unsigned long node, const char *uname,
 586                                    int depth, void *data)
 587 {
 588         __be32 *prop;
 589
 590         if (depth != 0)
 591                 return 0;
 592
 593         dt_root_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
 594         dt_root_addr_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
 595
 596         prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
 597         if (prop)
 598                 dt_root_size_cells = be32_to_cpup(prop);
 599         pr_debug("dt_root_size_cells = %x\n", dt_root_size_cells);
 600
 601         prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
 602         if (prop)
 603                 dt_root_addr_cells = be32_to_cpup(prop);
 604         pr_debug("dt_root_addr_cells = %x\n", dt_root_addr_cells);
 605
 606         /* break now */
 607         return 1;
 608 }
 609
 610 u64 __init dt_mem_next_cell(int s, __be32 **cellp)
 611 {
 612         __be32 *p = *cellp;
 613
 614         *cellp = p + s;
 615         return of_read_number(p, s);
 616 }
 617
 618 /**
 619  * early_init_dt_scan_memory - Look for an parse memory nodes
 620  */
 621 int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
 622                                      int depth, void *data)
 623 {
 624         char *type = of_get_flat_dt_prop(node, "device_type", NULL);
 625         __be32 *reg, *endp;
 626         unsigned long l;
 627
 628         /* We are scanning "memory" nodes only */
 629         if (type == NULL) {
 630                 /*
 631                  * The longtrail doesn't have a device_type on the
 632                  * /memory node, so look for the node called /memory@0.
 633                  */
 634                 if (depth != 1 || strcmp(uname, "memory@0") != 0)
 635                         return 0;
 636         } else if (strcmp(type, "memory") != 0)
 637                 return 0;
 638
 639         reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
 640         if (reg == NULL)
 641                 reg = of_get_flat_dt_prop(node, "reg", &l);
 642         if (reg == NULL)
 643                 return 0;
 644
 645         endp = reg + (l / sizeof(__be32));
 646
 647         pr_debug("memory scan node %s, reg size %ld, data: %x %x %x %x,\n",
 648             uname, l, reg[0], reg[1], reg[2], reg[3]);
 649
 650         while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
 651                 u64 base, size;
 652
 653                 base = dt_mem_next_cell(dt_root_addr_cells, &reg);
 654                 size = dt_mem_next_cell(dt_root_size_cells, &reg);
 655
 656                 if (size == 0)
 657                         continue;
 658                 pr_debug(" - %llx ,  %llx\n", (unsigned long long)base,
 659                     (unsigned long long)size);
 660
 661                 early_init_dt_add_memory_arch(base, size);
 662         }
 663
 664         return 0;
 665 }
 666
 667 int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 668                                      int depth, void *data)
 669 {
 670         unsigned long l;
 671         char *p;
 672
 673         pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
 674
 675         if (depth != 1 || !data ||
 676             (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
 677                 return 0;
 678
 679         early_init_dt_check_for_initrd(node);
 680
 681         /* Retrieve command line */
 682         p = of_get_flat_dt_prop(node, "bootargs", &l);
 683         if (p != NULL && l > 0)
 684                 strlcpy(data, p, min((int)l, COMMAND_LINE_SIZE));
 685
 686         /*
 687          * CONFIG_CMDLINE is meant to be a default in case nothing else
 688          * managed to set the command line, unless CONFIG_CMDLINE_FORCE
 689          * is set in which case we override whatever was found earlier.
 690          */
 691 #ifdef CONFIG_CMDLINE
 692 #ifndef CONFIG_CMDLINE_FORCE
 693         if (!((char *)data)[0])
 694 #endif
 695                 strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 696 #endif /* CONFIG_CMDLINE */
 697
 698         pr_debug("Command line is: %s\n", (char*)data);
 699
 700         /* break now */
 701         return 1;
 702 }
 703
 704 /**
 705  * unflatten_device_tree - create tree of device_nodes from flat blob
 706  *
 707  * unflattens the device-tree passed by the firmware, creating the
 708  * tree of struct device_node. It also fills the "name" and "type"
 709  * pointers of the nodes so the normal device-tree walking functions
 710  * can be used.
 711  */
 712 void __init unflatten_device_tree(void)
 713 {
 714         __unflatten_device_tree(initial_boot_params, &allnodes,
 715                                 early_init_dt_alloc_memory_arch);
 716
 717         /* Get pointer to "/chosen" and "/aliasas" nodes for use everywhere */
 718         of_alias_scan(early_init_dt_alloc_memory_arch);
 719 }
 720
 721 #endif /* CONFIG_OF_EARLY_FLATTREE */