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/lmb.h>
  14 #include <linux/initrd.h>
  15 #include <linux/of.h>
  16 #include <linux/of_fdt.h>
  17
  18 struct boot_param_header *initial_boot_params;
  19
  20 char *find_flat_dt_string(u32 offset)
  21 {
  22         return ((char *)initial_boot_params) +
  23                 initial_boot_params->off_dt_strings + offset;
  24 }
  25
  26 /**
  27  * of_scan_flat_dt - scan flattened tree blob and call callback on each.
  28  * @it: callback function
  29  * @data: context data pointer
  30  *
  31  * This function is used to scan the flattened device-tree, it is
  32  * used to extract the memory information at boot before we can
  33  * unflatten the tree
  34  */
  35 int __init of_scan_flat_dt(int (*it)(unsigned long node,
  36                                      const char *uname, int depth,
  37                                      void *data),
  38                            void *data)
  39 {
  40         unsigned long p = ((unsigned long)initial_boot_params) +
  41                 initial_boot_params->off_dt_struct;
  42         int rc = 0;
  43         int depth = -1;
  44
  45         do {
  46                 u32 tag = *((u32 *)p);
  47                 char *pathp;
  48
  49                 p += 4;
  50                 if (tag == OF_DT_END_NODE) {
  51                         depth--;
  52                         continue;
  53                 }
  54                 if (tag == OF_DT_NOP)
  55                         continue;
  56                 if (tag == OF_DT_END)
  57                         break;
  58                 if (tag == OF_DT_PROP) {
  59                         u32 sz = *((u32 *)p);
  60                         p += 8;
  61                         if (initial_boot_params->version < 0x10)
  62                                 p = _ALIGN(p, sz >= 8 ? 8 : 4);
  63                         p += sz;
  64                         p = _ALIGN(p, 4);
  65                         continue;
  66                 }
  67                 if (tag != OF_DT_BEGIN_NODE) {
  68                         pr_err("Invalid tag %x in flat device tree!\n", tag);
  69                         return -EINVAL;
  70                 }
  71                 depth++;
  72                 pathp = (char *)p;
  73                 p = _ALIGN(p + strlen(pathp) + 1, 4);
  74                 if ((*pathp) == '/') {
  75                         char *lp, *np;
  76                         for (lp = NULL, np = pathp; *np; np++)
  77                                 if ((*np) == '/')
  78                                         lp = np+1;
  79                         if (lp != NULL)
  80                                 pathp = lp;
  81                 }
  82                 rc = it(p, pathp, depth, data);
  83                 if (rc != 0)
  84                         break;
  85         } while (1);
  86
  87         return rc;
  88 }
  89
  90 /**
  91  * of_get_flat_dt_root - find the root node in the flat blob
  92  */
  93 unsigned long __init of_get_flat_dt_root(void)
  94 {
  95         unsigned long p = ((unsigned long)initial_boot_params) +
  96                 initial_boot_params->off_dt_struct;
  97
  98         while (*((u32 *)p) == OF_DT_NOP)
  99                 p += 4;
 100         BUG_ON(*((u32 *)p) != OF_DT_BEGIN_NODE);
 101         p += 4;
 102         return _ALIGN(p + strlen((char *)p) + 1, 4);
 103 }
 104
 105 /**
 106  * of_get_flat_dt_prop - Given a node in the flat blob, return the property ptr
 107  *
 108  * This function can be used within scan_flattened_dt callback to get
 109  * access to properties
 110  */
 111 void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
 112                                  unsigned long *size)
 113 {
 114         unsigned long p = node;
 115
 116         do {
 117                 u32 tag = *((u32 *)p);
 118                 u32 sz, noff;
 119                 const char *nstr;
 120
 121                 p += 4;
 122                 if (tag == OF_DT_NOP)
 123                         continue;
 124                 if (tag != OF_DT_PROP)
 125                         return NULL;
 126
 127                 sz = *((u32 *)p);
 128                 noff = *((u32 *)(p + 4));
 129                 p += 8;
 130                 if (initial_boot_params->version < 0x10)
 131                         p = _ALIGN(p, sz >= 8 ? 8 : 4);
 132
 133                 nstr = find_flat_dt_string(noff);
 134                 if (nstr == NULL) {
 135                         pr_warning("Can't find property index name !\n");
 136                         return NULL;
 137                 }
 138                 if (strcmp(name, nstr) == 0) {
 139                         if (size)
 140                                 *size = sz;
 141                         return (void *)p;
 142                 }
 143                 p += sz;
 144                 p = _ALIGN(p, 4);
 145         } while (1);
 146 }
 147
 148 /**
 149  * of_flat_dt_is_compatible - Return true if given node has compat in compatible list
 150  * @node: node to test
 151  * @compat: compatible string to compare with compatible list.
 152  */
 153 int __init of_flat_dt_is_compatible(unsigned long node, const char *compat)
 154 {
 155         const char *cp;
 156         unsigned long cplen, l;
 157
 158         cp = of_get_flat_dt_prop(node, "compatible", &cplen);
 159         if (cp == NULL)
 160                 return 0;
 161         while (cplen > 0) {
 162                 if (strncasecmp(cp, compat, strlen(compat)) == 0)
 163                         return 1;
 164                 l = strlen(cp) + 1;
 165                 cp += l;
 166                 cplen -= l;
 167         }
 168
 169         return 0;
 170 }
 171
 172 static void *__init unflatten_dt_alloc(unsigned long *mem, unsigned long size,
 173                                        unsigned long align)
 174 {
 175         void *res;
 176
 177         *mem = _ALIGN(*mem, align);
 178         res = (void *)*mem;
 179         *mem += size;
 180
 181         return res;
 182 }
 183
 184 /**
 185  * unflatten_dt_node - Alloc and populate a device_node from the flat tree
 186  * @p: pointer to node in flat tree
 187  * @dad: Parent struct device_node
 188  * @allnextpp: pointer to ->allnext from last allocated device_node
 189  * @fpsize: Size of the node path up at the current depth.
 190  */
 191 unsigned long __init unflatten_dt_node(unsigned long mem,
 192                                         unsigned long *p,
 193                                         struct device_node *dad,
 194                                         struct device_node ***allnextpp,
 195                                         unsigned long fpsize)
 196 {
 197         struct device_node *np;
 198         struct property *pp, **prev_pp = NULL;
 199         char *pathp;
 200         u32 tag;
 201         unsigned int l, allocl;
 202         int has_name = 0;
 203         int new_format = 0;
 204
 205         tag = *((u32 *)(*p));
 206         if (tag != OF_DT_BEGIN_NODE) {
 207                 pr_err("Weird tag at start of node: %x\n", tag);
 208                 return mem;
 209         }
 210         *p += 4;
 211         pathp = (char *)*p;
 212         l = allocl = strlen(pathp) + 1;
 213         *p = _ALIGN(*p + l, 4);
 214
 215         /* version 0x10 has a more compact unit name here instead of the full
 216          * path. we accumulate the full path size using "fpsize", we'll rebuild
 217          * it later. We detect this because the first character of the name is
 218          * not '/'.
 219          */
 220         if ((*pathp) != '/') {
 221                 new_format = 1;
 222                 if (fpsize == 0) {
 223                         /* root node: special case. fpsize accounts for path
 224                          * plus terminating zero. root node only has '/', so
 225                          * fpsize should be 2, but we want to avoid the first
 226                          * level nodes to have two '/' so we use fpsize 1 here
 227                          */
 228                         fpsize = 1;
 229                         allocl = 2;
 230                 } else {
 231                         /* account for '/' and path size minus terminal 0
 232                          * already in 'l'
 233                          */
 234                         fpsize += l;
 235                         allocl = fpsize;
 236                 }
 237         }
 238
 239         np = unflatten_dt_alloc(&mem, sizeof(struct device_node) + allocl,
 240                                 __alignof__(struct device_node));
 241         if (allnextpp) {
 242                 memset(np, 0, sizeof(*np));
 243                 np->full_name = ((char *)np) + sizeof(struct device_node);
 244                 if (new_format) {
 245                         char *fn = np->full_name;
 246                         /* rebuild full path for new format */
 247                         if (dad && dad->parent) {
 248                                 strcpy(fn, dad->full_name);
 249 #ifdef DEBUG
 250                                 if ((strlen(fn) + l + 1) != allocl) {
 251                                         pr_debug("%s: p: %d, l: %d, a: %d\n",
 252                                                 pathp, (int)strlen(fn),
 253                                                 l, allocl);
 254                                 }
 255 #endif
 256                                 fn += strlen(fn);
 257                         }
 258                         *(fn++) = '/';
 259                         memcpy(fn, pathp, l);
 260                 } else
 261                         memcpy(np->full_name, pathp, l);
 262                 prev_pp = &np->properties;
 263                 **allnextpp = np;
 264                 *allnextpp = &np->allnext;
 265                 if (dad != NULL) {
 266                         np->parent = dad;
 267                         /* we temporarily use the next field as `last_child'*/
 268                         if (dad->next == NULL)
 269                                 dad->child = np;
 270                         else
 271                                 dad->next->sibling = np;
 272                         dad->next = np;
 273                 }
 274                 kref_init(&np->kref);
 275         }
 276         while (1) {
 277                 u32 sz, noff;
 278                 char *pname;
 279
 280                 tag = *((u32 *)(*p));
 281                 if (tag == OF_DT_NOP) {
 282                         *p += 4;
 283                         continue;
 284                 }
 285                 if (tag != OF_DT_PROP)
 286                         break;
 287                 *p += 4;
 288                 sz = *((u32 *)(*p));
 289                 noff = *((u32 *)((*p) + 4));
 290                 *p += 8;
 291                 if (initial_boot_params->version < 0x10)
 292                         *p = _ALIGN(*p, sz >= 8 ? 8 : 4);
 293
 294                 pname = find_flat_dt_string(noff);
 295                 if (pname == NULL) {
 296                         pr_info("Can't find property name in list !\n");
 297                         break;
 298                 }
 299                 if (strcmp(pname, "name") == 0)
 300                         has_name = 1;
 301                 l = strlen(pname) + 1;
 302                 pp = unflatten_dt_alloc(&mem, sizeof(struct property),
 303                                         __alignof__(struct property));
 304                 if (allnextpp) {
 305                         if (strcmp(pname, "linux,phandle") == 0) {
 306                                 np->node = *((u32 *)*p);
 307                                 if (np->linux_phandle == 0)
 308                                         np->linux_phandle = np->node;
 309                         }
 310                         if (strcmp(pname, "ibm,phandle") == 0)
 311                                 np->linux_phandle = *((u32 *)*p);
 312                         pp->name = pname;
 313                         pp->length = sz;
 314                         pp->value = (void *)*p;
 315                         *prev_pp = pp;
 316                         prev_pp = &pp->next;
 317                 }
 318                 *p = _ALIGN((*p) + sz, 4);
 319         }
 320         /* with version 0x10 we may not have the name property, recreate
 321          * it here from the unit name if absent
 322          */
 323         if (!has_name) {
 324                 char *p1 = pathp, *ps = pathp, *pa = NULL;
 325                 int sz;
 326
 327                 while (*p1) {
 328                         if ((*p1) == '@')
 329                                 pa = p1;
 330                         if ((*p1) == '/')
 331                                 ps = p1 + 1;
 332                         p1++;
 333                 }
 334                 if (pa < ps)
 335                         pa = p1;
 336                 sz = (pa - ps) + 1;
 337                 pp = unflatten_dt_alloc(&mem, sizeof(struct property) + sz,
 338                                         __alignof__(struct property));
 339                 if (allnextpp) {
 340                         pp->name = "name";
 341                         pp->length = sz;
 342                         pp->value = pp + 1;
 343                         *prev_pp = pp;
 344                         prev_pp = &pp->next;
 345                         memcpy(pp->value, ps, sz - 1);
 346                         ((char *)pp->value)[sz - 1] = 0;
 347                         pr_debug("fixed up name for %s -> %s\n", pathp,
 348                                 (char *)pp->value);
 349                 }
 350         }
 351         if (allnextpp) {
 352                 *prev_pp = NULL;
 353                 np->name = of_get_property(np, "name", NULL);
 354                 np->type = of_get_property(np, "device_type", NULL);
 355
 356                 if (!np->name)
 357                         np->name = "<NULL>";
 358                 if (!np->type)
 359                         np->type = "<NULL>";
 360         }
 361         while (tag == OF_DT_BEGIN_NODE) {
 362                 mem = unflatten_dt_node(mem, p, np, allnextpp, fpsize);
 363                 tag = *((u32 *)(*p));
 364         }
 365         if (tag != OF_DT_END_NODE) {
 366                 pr_err("Weird tag at end of node: %x\n", tag);
 367                 return mem;
 368         }
 369         *p += 4;
 370         return mem;
 371 }
 372
 373 #ifdef CONFIG_BLK_DEV_INITRD
 374 /**
 375  * early_init_dt_check_for_initrd - Decode initrd location from flat tree
 376  * @node: reference to node containing initrd location ('chosen')
 377  */
 378 void __init early_init_dt_check_for_initrd(unsigned long node)
 379 {
 380         unsigned long len;
 381         u32 *prop;
 382
 383         pr_debug("Looking for initrd properties... ");
 384
 385         prop = of_get_flat_dt_prop(node, "linux,initrd-start", &len);
 386         if (prop) {
 387                 initrd_start = (unsigned long)
 388                                 __va(of_read_ulong(prop, len/4));
 389
 390                 prop = of_get_flat_dt_prop(node, "linux,initrd-end", &len);
 391                 if (prop) {
 392                         initrd_end = (unsigned long)
 393                                 __va(of_read_ulong(prop, len/4));
 394                         initrd_below_start_ok = 1;
 395                 } else {
 396                         initrd_start = 0;
 397                 }
 398         }
 399
 400         pr_debug("initrd_start=0x%lx  initrd_end=0x%lx\n",
 401                  initrd_start, initrd_end);
 402 }
 403 #else
 404 inline void early_init_dt_check_for_initrd(unsigned long node)
 405 {
 406 }
 407 #endif /* CONFIG_BLK_DEV_INITRD */
 408
 409 /**
 410  * unflatten_device_tree - create tree of device_nodes from flat blob
 411  *
 412  * unflattens the device-tree passed by the firmware, creating the
 413  * tree of struct device_node. It also fills the "name" and "type"
 414  * pointers of the nodes so the normal device-tree walking functions
 415  * can be used.
 416  */
 417 void __init unflatten_device_tree(void)
 418 {
 419         unsigned long start, mem, size;
 420         struct device_node **allnextp = &allnodes;
 421
 422         pr_debug(" -> unflatten_device_tree()\n");
 423
 424         /* First pass, scan for size */
 425         start = ((unsigned long)initial_boot_params) +
 426                 initial_boot_params->off_dt_struct;
 427         size = unflatten_dt_node(0, &start, NULL, NULL, 0);
 428         size = (size | 3) + 1;
 429
 430         pr_debug("  size is %lx, allocating...\n", size);
 431
 432         /* Allocate memory for the expanded device tree */
 433         mem = lmb_alloc(size + 4, __alignof__(struct device_node));
 434         mem = (unsigned long) __va(mem);
 435
 436         ((u32 *)mem)[size / 4] = 0xdeadbeef;
 437
 438         pr_debug("  unflattening %lx...\n", mem);
 439
 440         /* Second pass, do actual unflattening */
 441         start = ((unsigned long)initial_boot_params) +
 442                 initial_boot_params->off_dt_struct;
 443         unflatten_dt_node(mem, &start, NULL, &allnextp, 0);
 444         if (*((u32 *)start) != OF_DT_END)
 445                 pr_warning("Weird tag at end of tree: %08x\n", *((u32 *)start));
 446         if (((u32 *)mem)[size / 4] != 0xdeadbeef)
 447                 pr_warning("End of tree marker overwritten: %08x\n",
 448                            ((u32 *)mem)[size / 4]);
 449         *allnextp = NULL;
 450
 451         /* Get pointer to OF "/chosen" node for use everywhere */
 452         of_chosen = of_find_node_by_path("/chosen");
 453         if (of_chosen == NULL)
 454                 of_chosen = of_find_node_by_path("/chosen@0");
 455
 456         pr_debug(" <- unflatten_device_tree()\n");
 457 }