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   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/of.h>
  13 #include <linux/of_fdt.h>
  14
  15 struct boot_param_header *initial_boot_params;
  16
  17 char *find_flat_dt_string(u32 offset)
  18 {
  19         return ((char *)initial_boot_params) +
  20                 initial_boot_params->off_dt_strings + offset;
  21 }
  22
  23 /**
  24  * of_scan_flat_dt - scan flattened tree blob and call callback on each.
  25  * @it: callback function
  26  * @data: context data pointer
  27  *
  28  * This function is used to scan the flattened device-tree, it is
  29  * used to extract the memory information at boot before we can
  30  * unflatten the tree
  31  */
  32 int __init of_scan_flat_dt(int (*it)(unsigned long node,
  33                                      const char *uname, int depth,
  34                                      void *data),
  35                            void *data)
  36 {
  37         unsigned long p = ((unsigned long)initial_boot_params) +
  38                 initial_boot_params->off_dt_struct;
  39         int rc = 0;
  40         int depth = -1;
  41
  42         do {
  43                 u32 tag = *((u32 *)p);
  44                 char *pathp;
  45
  46                 p += 4;
  47                 if (tag == OF_DT_END_NODE) {
  48                         depth--;
  49                         continue;
  50                 }
  51                 if (tag == OF_DT_NOP)
  52                         continue;
  53                 if (tag == OF_DT_END)
  54                         break;
  55                 if (tag == OF_DT_PROP) {
  56                         u32 sz = *((u32 *)p);
  57                         p += 8;
  58                         if (initial_boot_params->version < 0x10)
  59                                 p = _ALIGN(p, sz >= 8 ? 8 : 4);
  60                         p += sz;
  61                         p = _ALIGN(p, 4);
  62                         continue;
  63                 }
  64                 if (tag != OF_DT_BEGIN_NODE) {
  65                         pr_err("Invalid tag %x in flat device tree!\n", tag);
  66                         return -EINVAL;
  67                 }
  68                 depth++;
  69                 pathp = (char *)p;
  70                 p = _ALIGN(p + strlen(pathp) + 1, 4);
  71                 if ((*pathp) == '/') {
  72                         char *lp, *np;
  73                         for (lp = NULL, np = pathp; *np; np++)
  74                                 if ((*np) == '/')
  75                                         lp = np+1;
  76                         if (lp != NULL)
  77                                 pathp = lp;
  78                 }
  79                 rc = it(p, pathp, depth, data);
  80                 if (rc != 0)
  81                         break;
  82         } while (1);
  83
  84         return rc;
  85 }