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                 } else {
 190                         /* account for '/' and path size minus terminal 0
 191                          * already in 'l'
 192                          */
 193                         fpsize += l;
 194                         allocl = fpsize;
 195                 }
 196         }
 197
 198         np = unflatten_dt_alloc(&mem, sizeof(struct device_node) + allocl,
 199                                 __alignof__(struct device_node));
 200         if (allnextpp) {
 201                 memset(np, 0, sizeof(*np));
 202                 np->full_name = ((char *)np) + sizeof(struct device_node);
 203                 if (new_format) {
 204                         char *fn = np->full_name;
 205                         /* rebuild full path for new format */
 206                         if (dad && dad->parent) {
 207                                 strcpy(fn, dad->full_name);
 208 #ifdef DEBUG
 209                                 if ((strlen(fn) + l + 1) != allocl) {
 210                                         pr_debug("%s: p: %d, l: %d, a: %d\n",
 211                                                 pathp, (int)strlen(fn),
 212                                                 l, allocl);
 213                                 }
 214 #endif
 215                                 fn += strlen(fn);
 216                         }
 217                         *(fn++) = '/';
 218                         memcpy(fn, pathp, l);
 219                 } else
 220                         memcpy(np->full_name, pathp, l);
 221                 prev_pp = &np->properties;
 222                 **allnextpp = np;
 223                 *allnextpp = &np->allnext;
 224                 if (dad != NULL) {
 225                         np->parent = dad;
 226                         /* we temporarily use the next field as `last_child'*/
 227                         if (dad->next == NULL)
 228                                 dad->child = np;
 229                         else
 230                                 dad->next->sibling = np;
 231                         dad->next = np;
 232                 }
 233                 kref_init(&np->kref);
 234         }
 235         /* process properties */
 236         while (1) {
 237                 u32 sz, noff;
 238                 char *pname;
 239
 240                 tag = be32_to_cpup((__be32 *)(*p));
 241                 if (tag == OF_DT_NOP) {
 242                         *p += 4;
 243                         continue;
 244                 }
 245                 if (tag != OF_DT_PROP)
 246                         break;
 247                 *p += 4;
 248                 sz = be32_to_cpup((__be32 *)(*p));
 249                 noff = be32_to_cpup((__be32 *)((*p) + 4));
 250                 *p += 8;
 251                 if (be32_to_cpu(blob->version) < 0x10)
 252                         *p = ALIGN(*p, sz >= 8 ? 8 : 4);
 253
 254                 pname = of_fdt_get_string(blob, noff);
 255                 if (pname == NULL) {
 256                         pr_info("Can't find property name in list !\n");
 257                         break;
 258                 }
 259                 if (strcmp(pname, "name") == 0)
 260                         has_name = 1;
 261                 l = strlen(pname) + 1;
 262                 pp = unflatten_dt_alloc(&mem, sizeof(struct property),
 263                                         __alignof__(struct property));
 264                 if (allnextpp) {
 265                         /* We accept flattened tree phandles either in
 266                          * ePAPR-style "phandle" properties, or the
 267                          * legacy "linux,phandle" properties.  If both
 268                          * appear and have different values, things
 269                          * will get weird.  Don't do that. */
 270                         if ((strcmp(pname, "phandle") == 0) ||
 271                             (strcmp(pname, "linux,phandle") == 0)) {
 272                                 if (np->phandle == 0)
 273                                         np->phandle = be32_to_cpup((__be32*)*p);
 274                         }
 275                         /* And we process the "ibm,phandle" property
 276                          * used in pSeries dynamic device tree
 277                          * stuff */
 278                         if (strcmp(pname, "ibm,phandle") == 0)
 279                                 np->phandle = be32_to_cpup((__be32 *)*p);
 280                         pp->name = pname;
 281                         pp->length = sz;
 282                         pp->value = (void *)*p;
 283                         *prev_pp = pp;
 284                         prev_pp = &pp->next;
 285                 }
 286                 *p = ALIGN((*p) + sz, 4);
 287         }
 288         /* with version 0x10 we may not have the name property, recreate
 289          * it here from the unit name if absent
 290          */
 291         if (!has_name) {
 292                 char *p1 = pathp, *ps = pathp, *pa = NULL;
 293                 int sz;
 294
 295                 while (*p1) {
 296                         if ((*p1) == '@')
 297                                 pa = p1;
 298                         if ((*p1) == '/')
 299                                 ps = p1 + 1;
 300                         p1++;
 301                 }
 302                 if (pa < ps)
 303                         pa = p1;
 304                 sz = (pa - ps) + 1;
 305                 pp = unflatten_dt_alloc(&mem, sizeof(struct property) + sz,
 306                                         __alignof__(struct property));
 307                 if (allnextpp) {
 308                         pp->name = "name";
 309                         pp->length = sz;
 310                         pp->value = pp + 1;
 311                         *prev_pp = pp;
 312                         prev_pp = &pp->next;
 313                         memcpy(pp->value, ps, sz - 1);
 314                         ((char *)pp->value)[sz - 1] = 0;
 315                         pr_debug("fixed up name for %s -> %s\n", pathp,
 316                                 (char *)pp->value);
 317                 }
 318         }
 319         if (allnextpp) {
 320                 *prev_pp = NULL;
 321                 np->name = of_get_property(np, "name", NULL);
 322                 np->type = of_get_property(np, "device_type", NULL);
 323
 324                 if (!np->name)
 325                         np->name = "<NULL>";
 326                 if (!np->type)
 327                         np->type = "<NULL>";
 328         }
 329         while (tag == OF_DT_BEGIN_NODE || tag == OF_DT_NOP) {
 330                 if (tag == OF_DT_NOP)
 331                         *p += 4;
 332                 else
 333                         mem = unflatten_dt_node(blob, mem, p, np, allnextpp,
 334                                                 fpsize);
 335                 tag = be32_to_cpup((__be32 *)(*p));
 336         }
 337         if (tag != OF_DT_END_NODE) {
 338                 pr_err("Weird tag at end of node: %x\n", tag);
 339                 return mem;
 340         }
 341         *p += 4;
 342         return mem;
 343 }
 344
 345 /**
 346  * __unflatten_device_tree - create tree of device_nodes from flat blob
 347  *
 348  * unflattens a device-tree, creating the
 349  * tree of struct device_node. It also fills the "name" and "type"
 350  * pointers of the nodes so the normal device-tree walking functions
 351  * can be used.
 352  * @blob: The blob to expand
 353  * @mynodes: The device_node tree created by the call
 354  * @dt_alloc: An allocator that provides a virtual address to memory
 355  * for the resulting tree
 356  */
 357 static void __unflatten_device_tree(struct boot_param_header *blob,
 358                              struct device_node **mynodes,
 359                              void * (*dt_alloc)(u64 size, u64 align))
 360 {
 361         unsigned long start, mem, size;
 362         struct device_node **allnextp = mynodes;
 363
 364         pr_debug(" -> unflatten_device_tree()\n");
 365
 366         if (!blob) {
 367                 pr_debug("No device tree pointer\n");
 368                 return;
 369         }
 370
 371         pr_debug("Unflattening device tree:\n");
 372         pr_debug("magic: %08x\n", be32_to_cpu(blob->magic));
 373         pr_debug("size: %08x\n", be32_to_cpu(blob->totalsize));
 374         pr_debug("version: %08x\n", be32_to_cpu(blob->version));
 375
 376         if (be32_to_cpu(blob->magic) != OF_DT_HEADER) {
 377                 pr_err("Invalid device tree blob header\n");
 378                 return;
 379         }
 380
 381         /* First pass, scan for size */
 382         start = ((unsigned long)blob) +
 383                 be32_to_cpu(blob->off_dt_struct);
 384         size = unflatten_dt_node(blob, 0, &start, NULL, NULL, 0);
 385         size = (size | 3) + 1;
 386
 387         pr_debug("  size is %lx, allocating...\n", size);
 388
 389         /* Allocate memory for the expanded device tree */
 390         mem = (unsigned long)
 391                 dt_alloc(size + 4, __alignof__(struct device_node));
 392
 393         memset((void *)mem, 0, size);
 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                 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                         char *lp, *np;
 493                         for (lp = NULL, np = pathp; *np; np++)
 494                                 if ((*np) == '/')
 495                                         lp = np+1;
 496                         if (lp != NULL)
 497                                 pathp = lp;
 498                 }
 499                 rc = it(p, pathp, depth, data);
 500                 if (rc != 0)
 501                         break;
 502         } while (1);
 503
 504         return rc;
 505 }
 506
 507 /**
 508  * of_get_flat_dt_root - find the root node in the flat blob
 509  */
 510 unsigned long __init of_get_flat_dt_root(void)
 511 {
 512         unsigned long p = ((unsigned long)initial_boot_params) +
 513                 be32_to_cpu(initial_boot_params->off_dt_struct);
 514
 515         while (be32_to_cpup((__be32 *)p) == OF_DT_NOP)
 516                 p += 4;
 517         BUG_ON(be32_to_cpup((__be32 *)p) != OF_DT_BEGIN_NODE);
 518         p += 4;
 519         return ALIGN(p + strlen((char *)p) + 1, 4);
 520 }
 521
 522 /**
 523  * of_get_flat_dt_prop - Given a node in the flat blob, return the property ptr
 524  *
 525  * This function can be used within scan_flattened_dt callback to get
 526  * access to properties
 527  */
 528 void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
 529                                  unsigned long *size)
 530 {
 531         return of_fdt_get_property(initial_boot_params, node, name, size);
 532 }
 533
 534 /**
 535  * of_flat_dt_is_compatible - Return true if given node has compat in compatible list
 536  * @node: node to test
 537  * @compat: compatible string to compare with compatible list.
 538  */
 539 int __init of_flat_dt_is_compatible(unsigned long node, const char *compat)
 540 {
 541         return of_fdt_is_compatible(initial_boot_params, node, compat);
 542 }
 543
 544 /**
 545  * of_flat_dt_match - Return true if node matches a list of compatible values
 546  */
 547 int __init of_flat_dt_match(unsigned long node, const char *const *compat)
 548 {
 549         return of_fdt_match(initial_boot_params, node, compat);
 550 }
 551
 552 #ifdef CONFIG_BLK_DEV_INITRD
 553 /**
 554  * early_init_dt_check_for_initrd - Decode initrd location from flat tree
 555  * @node: reference to node containing initrd location ('chosen')
 556  */
 557 void __init early_init_dt_check_for_initrd(unsigned long node)
 558 {
 559         unsigned long start, end, len;
 560         __be32 *prop;
 561
 562         pr_debug("Looking for initrd properties... ");
 563
 564         prop = of_get_flat_dt_prop(node, "linux,initrd-start", &len);
 565         if (!prop)
 566                 return;
 567         start = of_read_ulong(prop, len/4);
 568
 569         prop = of_get_flat_dt_prop(node, "linux,initrd-end", &len);
 570         if (!prop)
 571                 return;
 572         end = of_read_ulong(prop, len/4);
 573
 574         early_init_dt_setup_initrd_arch(start, end);
 575         pr_debug("initrd_start=0x%lx  initrd_end=0x%lx\n", start, end);
 576 }
 577 #else
 578 inline void early_init_dt_check_for_initrd(unsigned long node)
 579 {
 580 }
 581 #endif /* CONFIG_BLK_DEV_INITRD */
 582
 583 /**
 584  * early_init_dt_scan_root - fetch the top level address and size cells
 585  */
 586 int __init early_init_dt_scan_root(unsigned long node, const char *uname,
 587                                    int depth, void *data)
 588 {
 589         __be32 *prop;
 590
 591         if (depth != 0)
 592                 return 0;
 593
 594         dt_root_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
 595         dt_root_addr_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
 596
 597         prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
 598         if (prop)
 599                 dt_root_size_cells = be32_to_cpup(prop);
 600         pr_debug("dt_root_size_cells = %x\n", dt_root_size_cells);
 601
 602         prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
 603         if (prop)
 604                 dt_root_addr_cells = be32_to_cpup(prop);
 605         pr_debug("dt_root_addr_cells = %x\n", dt_root_addr_cells);
 606
 607         /* break now */
 608         return 1;
 609 }
 610
 611 u64 __init dt_mem_next_cell(int s, __be32 **cellp)
 612 {
 613         __be32 *p = *cellp;
 614
 615         *cellp = p + s;
 616         return of_read_number(p, s);
 617 }
 618
 619 /**
 620  * early_init_dt_scan_memory - Look for an parse memory nodes
 621  */
 622 int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
 623                                      int depth, void *data)
 624 {
 625         char *type = of_get_flat_dt_prop(node, "device_type", NULL);
 626         __be32 *reg, *endp;
 627         unsigned long l;
 628
 629         /* We are scanning "memory" nodes only */
 630         if (type == NULL) {
 631                 /*
 632                  * The longtrail doesn't have a device_type on the
 633                  * /memory node, so look for the node called /memory@0.
 634                  */
 635                 if (depth != 1 || strcmp(uname, "memory@0") != 0)
 636                         return 0;
 637         } else if (strcmp(type, "memory") != 0)
 638                 return 0;
 639
 640         reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
 641         if (reg == NULL)
 642                 reg = of_get_flat_dt_prop(node, "reg", &l);
 643         if (reg == NULL)
 644                 return 0;
 645
 646         endp = reg + (l / sizeof(__be32));
 647
 648         pr_debug("memory scan node %s, reg size %ld, data: %x %x %x %x,\n",
 649             uname, l, reg[0], reg[1], reg[2], reg[3]);
 650
 651         while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
 652                 u64 base, size;
 653
 654                 base = dt_mem_next_cell(dt_root_addr_cells, &reg);
 655                 size = dt_mem_next_cell(dt_root_size_cells, &reg);
 656
 657                 if (size == 0)
 658                         continue;
 659                 pr_debug(" - %llx ,  %llx\n", (unsigned long long)base,
 660                     (unsigned long long)size);
 661
 662                 early_init_dt_add_memory_arch(base, size);
 663         }
 664
 665         return 0;
 666 }
 667
 668 int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 669                                      int depth, void *data)
 670 {
 671         unsigned long l;
 672         char *p;
 673
 674         pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
 675
 676         if (depth != 1 || !data ||
 677             (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
 678                 return 0;
 679
 680         early_init_dt_check_for_initrd(node);
 681
 682         /* Retrieve command line */
 683         p = of_get_flat_dt_prop(node, "bootargs", &l);
 684         if (p != NULL && l > 0)
 685                 strlcpy(data, p, min((int)l, COMMAND_LINE_SIZE));
 686
 687         /*
 688          * CONFIG_CMDLINE is meant to be a default in case nothing else
 689          * managed to set the command line, unless CONFIG_CMDLINE_FORCE
 690          * is set in which case we override whatever was found earlier.
 691          */
 692 #ifdef CONFIG_CMDLINE
 693 #ifndef CONFIG_CMDLINE_FORCE
 694         if (!((char *)data)[0])
 695 #endif
 696                 strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 697 #endif /* CONFIG_CMDLINE */
 698
 699         pr_debug("Command line is: %s\n", (char*)data);
 700
 701         /* break now */
 702         return 1;
 703 }
 704
 705 /**
 706  * unflatten_device_tree - create tree of device_nodes from flat blob
 707  *
 708  * unflattens the device-tree passed by the firmware, creating the
 709  * tree of struct device_node. It also fills the "name" and "type"
 710  * pointers of the nodes so the normal device-tree walking functions
 711  * can be used.
 712  */
 713 void __init unflatten_device_tree(void)
 714 {
 715         __unflatten_device_tree(initial_boot_params, &allnodes,
 716                                 early_init_dt_alloc_memory_arch);
 717
 718         /* Get pointer to "/chosen" and "/aliasas" nodes for use everywhere */
 719         of_alias_scan(early_init_dt_alloc_memory_arch);
 720 }
 721
 722 #endif /* CONFIG_OF_EARLY_FLATTREE */