drivers/of/address.c

   1
   2 #include <linux/device.h>
   3 #include <linux/io.h>
   4 #include <linux/ioport.h>
   5 #include <linux/module.h>
   6 #include <linux/of_address.h>
   7 #include <linux/pci_regs.h>
   8 #include <linux/string.h>
   9
  10 /* Max address size we deal with */
  11 #define OF_MAX_ADDR_CELLS       4
  12 #define OF_CHECK_ADDR_COUNT(na) ((na) > 0 && (na) <= OF_MAX_ADDR_CELLS)
  13 #define OF_CHECK_COUNTS(na, ns) (OF_CHECK_ADDR_COUNT(na) && (ns) > 0)
  14
  15 static struct of_bus *of_match_bus(struct device_node *np);
  16 static int __of_address_to_resource(struct device_node *dev,
  17                 const __be32 *addrp, u64 size, unsigned int flags,
  18                 const char *name, struct resource *r);
  19
  20 /* Debug utility */
  21 #ifdef DEBUG
  22 static void of_dump_addr(const char *s, const __be32 *addr, int na)
  23 {
  24         printk(KERN_DEBUG "%s", s);
  25         while (na--)
  26                 printk(" %08x", be32_to_cpu(*(addr++)));
  27         printk("\n");
  28 }
  29 #else
  30 static void of_dump_addr(const char *s, const __be32 *addr, int na) { }
  31 #endif
  32
  33 /* Callbacks for bus specific translators */
  34 struct of_bus {
  35         const char      *name;
  36         const char      *addresses;
  37         int             (*match)(struct device_node *parent);
  38         void            (*count_cells)(struct device_node *child,
  39                                        int *addrc, int *sizec);
  40         u64             (*map)(__be32 *addr, const __be32 *range,
  41                                 int na, int ns, int pna);
  42         int             (*translate)(__be32 *addr, u64 offset, int na);
  43         unsigned int    (*get_flags)(const __be32 *addr);
  44 };
  45
  46 /*
  47  * Default translator (generic bus)
  48  */
  49
  50 static void of_bus_default_count_cells(struct device_node *dev,
  51                                        int *addrc, int *sizec)
  52 {
  53         if (addrc)
  54                 *addrc = of_n_addr_cells(dev);
  55         if (sizec)
  56                 *sizec = of_n_size_cells(dev);
  57 }
  58
  59 static u64 of_bus_default_map(__be32 *addr, const __be32 *range,
  60                 int na, int ns, int pna)
  61 {
  62         u64 cp, s, da;
  63
  64         cp = of_read_number(range, na);
  65         s  = of_read_number(range + na + pna, ns);
  66         da = of_read_number(addr, na);
  67
  68         pr_debug("OF: default map, cp=%llx, s=%llx, da=%llx\n",
  69                  (unsigned long long)cp, (unsigned long long)s,
  70                  (unsigned long long)da);
  71
  72         if (da < cp || da >= (cp + s))
  73                 return OF_BAD_ADDR;
  74         return da - cp;
  75 }
  76
  77 static int of_bus_default_translate(__be32 *addr, u64 offset, int na)
  78 {
  79         u64 a = of_read_number(addr, na);
  80         memset(addr, 0, na * 4);
  81         a += offset;
  82         if (na > 1)
  83                 addr[na - 2] = cpu_to_be32(a >> 32);
  84         addr[na - 1] = cpu_to_be32(a & 0xffffffffu);
  85
  86         return 0;
  87 }
  88
  89 static unsigned int of_bus_default_get_flags(const __be32 *addr)
  90 {
  91         return IORESOURCE_MEM;
  92 }
  93
  94 #ifdef CONFIG_PCI
  95 /*
  96  * PCI bus specific translator
  97  */
  98
  99 static int of_bus_pci_match(struct device_node *np)
 100 {
 101         /*
 102          * "vci" is for the /chaos bridge on 1st-gen PCI powermacs
 103          * "ht" is hypertransport
 104          */
 105         return !strcmp(np->type, "pci") || !strcmp(np->type, "vci") ||
 106                 !strcmp(np->type, "ht");
 107 }
 108
 109 static void of_bus_pci_count_cells(struct device_node *np,
 110                                    int *addrc, int *sizec)
 111 {
 112         if (addrc)
 113                 *addrc = 3;
 114         if (sizec)
 115                 *sizec = 2;
 116 }
 117
 118 static unsigned int of_bus_pci_get_flags(const __be32 *addr)
 119 {
 120         unsigned int flags = 0;
 121         u32 w = be32_to_cpup(addr);
 122
 123         switch((w >> 24) & 0x03) {
 124         case 0x01:
 125                 flags |= IORESOURCE_IO;
 126                 break;
 127         case 0x02: /* 32 bits */
 128         case 0x03: /* 64 bits */
 129                 flags |= IORESOURCE_MEM;
 130                 break;
 131         }
 132         if (w & 0x40000000)
 133                 flags |= IORESOURCE_PREFETCH;
 134         return flags;
 135 }
 136
 137 static u64 of_bus_pci_map(__be32 *addr, const __be32 *range, int na, int ns,
 138                 int pna)
 139 {
 140         u64 cp, s, da;
 141         unsigned int af, rf;
 142
 143         af = of_bus_pci_get_flags(addr);
 144         rf = of_bus_pci_get_flags(range);
 145
 146         /* Check address type match */
 147         if ((af ^ rf) & (IORESOURCE_MEM | IORESOURCE_IO))
 148                 return OF_BAD_ADDR;
 149
 150         /* Read address values, skipping high cell */
 151         cp = of_read_number(range + 1, na - 1);
 152         s  = of_read_number(range + na + pna, ns);
 153         da = of_read_number(addr + 1, na - 1);
 154
 155         pr_debug("OF: PCI map, cp=%llx, s=%llx, da=%llx\n",
 156                  (unsigned long long)cp, (unsigned long long)s,
 157                  (unsigned long long)da);
 158
 159         if (da < cp || da >= (cp + s))
 160                 return OF_BAD_ADDR;
 161         return da - cp;
 162 }
 163
 164 static int of_bus_pci_translate(__be32 *addr, u64 offset, int na)
 165 {
 166         return of_bus_default_translate(addr + 1, offset, na - 1);
 167 }
 168
 169 const __be32 *of_get_pci_address(struct device_node *dev, int bar_no, u64 *size,
 170                         unsigned int *flags)
 171 {
 172         const __be32 *prop;
 173         unsigned int psize;
 174         struct device_node *parent;
 175         struct of_bus *bus;
 176         int onesize, i, na, ns;
 177
 178         /* Get parent & match bus type */
 179         parent = of_get_parent(dev);
 180         if (parent == NULL)
 181                 return NULL;
 182         bus = of_match_bus(parent);
 183         if (strcmp(bus->name, "pci")) {
 184                 of_node_put(parent);
 185                 return NULL;
 186         }
 187         bus->count_cells(dev, &na, &ns);
 188         of_node_put(parent);
 189         if (!OF_CHECK_ADDR_COUNT(na))
 190                 return NULL;
 191
 192         /* Get "reg" or "assigned-addresses" property */
 193         prop = of_get_property(dev, bus->addresses, &psize);
 194         if (prop == NULL)
 195                 return NULL;
 196         psize /= 4;
 197
 198         onesize = na + ns;
 199         for (i = 0; psize >= onesize; psize -= onesize, prop += onesize, i++) {
 200                 u32 val = be32_to_cpu(prop[0]);
 201                 if ((val & 0xff) == ((bar_no * 4) + PCI_BASE_ADDRESS_0)) {
 202                         if (size)
 203                                 *size = of_read_number(prop + na, ns);
 204                         if (flags)
 205                                 *flags = bus->get_flags(prop);
 206                         return prop;
 207                 }
 208         }
 209         return NULL;
 210 }
 211 EXPORT_SYMBOL(of_get_pci_address);
 212
 213 int of_pci_address_to_resource(struct device_node *dev, int bar,
 214                                struct resource *r)
 215 {
 216         const __be32    *addrp;
 217         u64             size;
 218         unsigned int    flags;
 219
 220         addrp = of_get_pci_address(dev, bar, &size, &flags);
 221         if (addrp == NULL)
 222                 return -EINVAL;
 223         return __of_address_to_resource(dev, addrp, size, flags, NULL, r);
 224 }
 225 EXPORT_SYMBOL_GPL(of_pci_address_to_resource);
 226
 227 int of_pci_range_parser_init(struct of_pci_range_parser *parser,
 228                                 struct device_node *node)
 229 {
 230         const int na = 3, ns = 2;
 231         int rlen;
 232
 233         parser->node = node;
 234         parser->pna = of_n_addr_cells(node);
 235         parser->np = parser->pna + na + ns;
 236
 237         parser->range = of_get_property(node, "ranges", &rlen);
 238         if (parser->range == NULL)
 239                 return -ENOENT;
 240
 241         parser->end = parser->range + rlen / sizeof(__be32);
 242
 243         return 0;
 244 }
 245 EXPORT_SYMBOL_GPL(of_pci_range_parser_init);
 246
 247 struct of_pci_range *of_pci_range_parser_one(struct of_pci_range_parser *parser,
 248                                                 struct of_pci_range *range)
 249 {
 250         const int na = 3, ns = 2;
 251
 252         if (!range)
 253                 return NULL;
 254
 255         if (!parser->range || parser->range + parser->np > parser->end)
 256                 return NULL;
 257
 258         range->pci_space = parser->range[0];
 259         range->flags = of_bus_pci_get_flags(parser->range);
 260         range->pci_addr = of_read_number(parser->range + 1, ns);
 261         range->cpu_addr = of_translate_address(parser->node,
 262                                 parser->range + na);
 263         range->size = of_read_number(parser->range + parser->pna + na, ns);
 264
 265         parser->range += parser->np;
 266
 267         /* Now consume following elements while they are contiguous */
 268         while (parser->range + parser->np <= parser->end) {
 269                 u32 flags, pci_space;
 270                 u64 pci_addr, cpu_addr, size;
 271
 272                 pci_space = be32_to_cpup(parser->range);
 273                 flags = of_bus_pci_get_flags(parser->range);
 274                 pci_addr = of_read_number(parser->range + 1, ns);
 275                 cpu_addr = of_translate_address(parser->node,
 276                                 parser->range + na);
 277                 size = of_read_number(parser->range + parser->pna + na, ns);
 278
 279                 if (flags != range->flags)
 280                         break;
 281                 if (pci_addr != range->pci_addr + range->size ||
 282                     cpu_addr != range->cpu_addr + range->size)
 283                         break;
 284
 285                 range->size += size;
 286                 parser->range += parser->np;
 287         }
 288
 289         return range;
 290 }
 291 EXPORT_SYMBOL_GPL(of_pci_range_parser_one);
 292
 293 #endif /* CONFIG_PCI */
 294
 295 /*
 296  * ISA bus specific translator
 297  */
 298
 299 static int of_bus_isa_match(struct device_node *np)
 300 {
 301         return !strcmp(np->name, "isa");
 302 }
 303
 304 static void of_bus_isa_count_cells(struct device_node *child,
 305                                    int *addrc, int *sizec)
 306 {
 307         if (addrc)
 308                 *addrc = 2;
 309         if (sizec)
 310                 *sizec = 1;
 311 }
 312
 313 static u64 of_bus_isa_map(__be32 *addr, const __be32 *range, int na, int ns,
 314                 int pna)
 315 {
 316         u64 cp, s, da;
 317
 318         /* Check address type match */
 319         if ((addr[0] ^ range[0]) & cpu_to_be32(1))
 320                 return OF_BAD_ADDR;
 321
 322         /* Read address values, skipping high cell */
 323         cp = of_read_number(range + 1, na - 1);
 324         s  = of_read_number(range + na + pna, ns);
 325         da = of_read_number(addr + 1, na - 1);
 326
 327         pr_debug("OF: ISA map, cp=%llx, s=%llx, da=%llx\n",
 328                  (unsigned long long)cp, (unsigned long long)s,
 329                  (unsigned long long)da);
 330
 331         if (da < cp || da >= (cp + s))
 332                 return OF_BAD_ADDR;
 333         return da - cp;
 334 }
 335
 336 static int of_bus_isa_translate(__be32 *addr, u64 offset, int na)
 337 {
 338         return of_bus_default_translate(addr + 1, offset, na - 1);
 339 }
 340
 341 static unsigned int of_bus_isa_get_flags(const __be32 *addr)
 342 {
 343         unsigned int flags = 0;
 344         u32 w = be32_to_cpup(addr);
 345
 346         if (w & 1)
 347                 flags |= IORESOURCE_IO;
 348         else
 349                 flags |= IORESOURCE_MEM;
 350         return flags;
 351 }
 352
 353 /*
 354  * Array of bus specific translators
 355  */
 356
 357 static struct of_bus of_busses[] = {
 358 #ifdef CONFIG_PCI
 359         /* PCI */
 360         {
 361                 .name = "pci",
 362                 .addresses = "assigned-addresses",
 363                 .match = of_bus_pci_match,
 364                 .count_cells = of_bus_pci_count_cells,
 365                 .map = of_bus_pci_map,
 366                 .translate = of_bus_pci_translate,
 367                 .get_flags = of_bus_pci_get_flags,
 368         },
 369 #endif /* CONFIG_PCI */
 370         /* ISA */
 371         {
 372                 .name = "isa",
 373                 .addresses = "reg",
 374                 .match = of_bus_isa_match,
 375                 .count_cells = of_bus_isa_count_cells,
 376                 .map = of_bus_isa_map,
 377                 .translate = of_bus_isa_translate,
 378                 .get_flags = of_bus_isa_get_flags,
 379         },
 380         /* Default */
 381         {
 382                 .name = "default",
 383                 .addresses = "reg",
 384                 .match = NULL,
 385                 .count_cells = of_bus_default_count_cells,
 386                 .map = of_bus_default_map,
 387                 .translate = of_bus_default_translate,
 388                 .get_flags = of_bus_default_get_flags,
 389         },
 390 };
 391
 392 static struct of_bus *of_match_bus(struct device_node *np)
 393 {
 394         int i;
 395
 396         for (i = 0; i < ARRAY_SIZE(of_busses); i++)
 397                 if (!of_busses[i].match || of_busses[i].match(np))
 398                         return &of_busses[i];
 399         BUG();
 400         return NULL;
 401 }
 402
 403 static int of_translate_one(struct device_node *parent, struct of_bus *bus,
 404                             struct of_bus *pbus, __be32 *addr,
 405                             int na, int ns, int pna, const char *rprop)
 406 {
 407         const __be32 *ranges;
 408         unsigned int rlen;
 409         int rone;
 410         u64 offset = OF_BAD_ADDR;
 411
 412         /* Normally, an absence of a "ranges" property means we are
 413          * crossing a non-translatable boundary, and thus the addresses
 414          * below the current not cannot be converted to CPU physical ones.
 415          * Unfortunately, while this is very clear in the spec, it's not
 416          * what Apple understood, and they do have things like /uni-n or
 417          * /ht nodes with no "ranges" property and a lot of perfectly
 418          * useable mapped devices below them. Thus we treat the absence of
 419          * "ranges" as equivalent to an empty "ranges" property which means
 420          * a 1:1 translation at that level. It's up to the caller not to try
 421          * to translate addresses that aren't supposed to be translated in
 422          * the first place. --BenH.
 423          *
 424          * As far as we know, this damage only exists on Apple machines, so
 425          * This code is only enabled on powerpc. --gcl
 426          */
 427         ranges = of_get_property(parent, rprop, &rlen);
 428 #if !defined(CONFIG_PPC)
 429         if (ranges == NULL) {
 430                 pr_err("OF: no ranges; cannot translate\n");
 431                 return 1;
 432         }
 433 #endif /* !defined(CONFIG_PPC) */
 434         if (ranges == NULL || rlen == 0) {
 435                 offset = of_read_number(addr, na);
 436                 memset(addr, 0, pna * 4);
 437                 pr_debug("OF: empty ranges; 1:1 translation\n");
 438                 goto finish;
 439         }
 440
 441         pr_debug("OF: walking ranges...\n");
 442
 443         /* Now walk through the ranges */
 444         rlen /= 4;
 445         rone = na + pna + ns;
 446         for (; rlen >= rone; rlen -= rone, ranges += rone) {
 447                 offset = bus->map(addr, ranges, na, ns, pna);
 448                 if (offset != OF_BAD_ADDR)
 449                         break;
 450         }
 451         if (offset == OF_BAD_ADDR) {
 452                 pr_debug("OF: not found !\n");
 453                 return 1;
 454         }
 455         memcpy(addr, ranges + na, 4 * pna);
 456
 457  finish:
 458         of_dump_addr("OF: parent translation for:", addr, pna);
 459         pr_debug("OF: with offset: %llx\n", (unsigned long long)offset);
 460
 461         /* Translate it into parent bus space */
 462         return pbus->translate(addr, offset, pna);
 463 }
 464
 465 /*
 466  * Translate an address from the device-tree into a CPU physical address,
 467  * this walks up the tree and applies the various bus mappings on the
 468  * way.
 469  *
 470  * Note: We consider that crossing any level with #size-cells == 0 to mean
 471  * that translation is impossible (that is we are not dealing with a value
 472  * that can be mapped to a cpu physical address). This is not really specified
 473  * that way, but this is traditionally the way IBM at least do things
 474  */
 475 static u64 __of_translate_address(struct device_node *dev,
 476                                   const __be32 *in_addr, const char *rprop)
 477 {
 478         struct device_node *parent = NULL;
 479         struct of_bus *bus, *pbus;
 480         __be32 addr[OF_MAX_ADDR_CELLS];
 481         int na, ns, pna, pns;
 482         u64 result = OF_BAD_ADDR;
 483
 484         pr_debug("OF: ** translation for device %s **\n", of_node_full_name(dev));
 485
 486         /* Increase refcount at current level */
 487         of_node_get(dev);
 488
 489         /* Get parent & match bus type */
 490         parent = of_get_parent(dev);
 491         if (parent == NULL)
 492                 goto bail;
 493         bus = of_match_bus(parent);
 494
 495         /* Count address cells & copy address locally */
 496         bus->count_cells(dev, &na, &ns);
 497         if (!OF_CHECK_COUNTS(na, ns)) {
 498                 printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
 499                        of_node_full_name(dev));
 500                 goto bail;
 501         }
 502         memcpy(addr, in_addr, na * 4);
 503
 504         pr_debug("OF: bus is %s (na=%d, ns=%d) on %s\n",
 505             bus->name, na, ns, of_node_full_name(parent));
 506         of_dump_addr("OF: translating address:", addr, na);
 507
 508         /* Translate */
 509         for (;;) {
 510                 /* Switch to parent bus */
 511                 of_node_put(dev);
 512                 dev = parent;
 513                 parent = of_get_parent(dev);
 514
 515                 /* If root, we have finished */
 516                 if (parent == NULL) {
 517                         pr_debug("OF: reached root node\n");
 518                         result = of_read_number(addr, na);
 519                         break;
 520                 }
 521
 522                 /* Get new parent bus and counts */
 523                 pbus = of_match_bus(parent);
 524                 pbus->count_cells(dev, &pna, &pns);
 525                 if (!OF_CHECK_COUNTS(pna, pns)) {
 526                         printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
 527                                of_node_full_name(dev));
 528                         break;
 529                 }
 530
 531                 pr_debug("OF: parent bus is %s (na=%d, ns=%d) on %s\n",
 532                     pbus->name, pna, pns, of_node_full_name(parent));
 533
 534                 /* Apply bus translation */
 535                 if (of_translate_one(dev, bus, pbus, addr, na, ns, pna, rprop))
 536                         break;
 537
 538                 /* Complete the move up one level */
 539                 na = pna;
 540                 ns = pns;
 541                 bus = pbus;
 542
 543                 of_dump_addr("OF: one level translation:", addr, na);
 544         }
 545  bail:
 546         of_node_put(parent);
 547         of_node_put(dev);
 548
 549         return result;
 550 }
 551
 552 u64 of_translate_address(struct device_node *dev, const __be32 *in_addr)
 553 {
 554         return __of_translate_address(dev, in_addr, "ranges");
 555 }
 556 EXPORT_SYMBOL(of_translate_address);
 557
 558 u64 of_translate_dma_address(struct device_node *dev, const __be32 *in_addr)
 559 {
 560         return __of_translate_address(dev, in_addr, "dma-ranges");
 561 }
 562 EXPORT_SYMBOL(of_translate_dma_address);
 563
 564 bool of_can_translate_address(struct device_node *dev)
 565 {
 566         struct device_node *parent;
 567         struct of_bus *bus;
 568         int na, ns;
 569
 570         parent = of_get_parent(dev);
 571         if (parent == NULL)
 572                 return false;
 573
 574         bus = of_match_bus(parent);
 575         bus->count_cells(dev, &na, &ns);
 576
 577         of_node_put(parent);
 578
 579         return OF_CHECK_COUNTS(na, ns);
 580 }
 581 EXPORT_SYMBOL(of_can_translate_address);
 582
 583 const __be32 *of_get_address(struct device_node *dev, int index, u64 *size,
 584                     unsigned int *flags)
 585 {
 586         const __be32 *prop;
 587         unsigned int psize;
 588         struct device_node *parent;
 589         struct of_bus *bus;
 590         int onesize, i, na, ns;
 591
 592         /* Get parent & match bus type */
 593         parent = of_get_parent(dev);
 594         if (parent == NULL)
 595                 return NULL;
 596         bus = of_match_bus(parent);
 597         bus->count_cells(dev, &na, &ns);
 598         of_node_put(parent);
 599         if (!OF_CHECK_ADDR_COUNT(na))
 600                 return NULL;
 601
 602         /* Get "reg" or "assigned-addresses" property */
 603         prop = of_get_property(dev, bus->addresses, &psize);
 604         if (prop == NULL)
 605                 return NULL;
 606         psize /= 4;
 607
 608         onesize = na + ns;
 609         for (i = 0; psize >= onesize; psize -= onesize, prop += onesize, i++)
 610                 if (i == index) {
 611                         if (size)
 612                                 *size = of_read_number(prop + na, ns);
 613                         if (flags)
 614                                 *flags = bus->get_flags(prop);
 615                         return prop;
 616                 }
 617         return NULL;
 618 }
 619 EXPORT_SYMBOL(of_get_address);
 620
 621 unsigned long __weak pci_address_to_pio(phys_addr_t address)
 622 {
 623         if (address > IO_SPACE_LIMIT)
 624                 return (unsigned long)-1;
 625
 626         return (unsigned long) address;
 627 }
 628
 629 static int __of_address_to_resource(struct device_node *dev,
 630                 const __be32 *addrp, u64 size, unsigned int flags,
 631                 const char *name, struct resource *r)
 632 {
 633         u64 taddr;
 634
 635         if ((flags & (IORESOURCE_IO | IORESOURCE_MEM)) == 0)
 636                 return -EINVAL;
 637         taddr = of_translate_address(dev, addrp);
 638         if (taddr == OF_BAD_ADDR)
 639                 return -EINVAL;
 640         memset(r, 0, sizeof(struct resource));
 641         if (flags & IORESOURCE_IO) {
 642                 unsigned long port;
 643                 port = pci_address_to_pio(taddr);
 644                 if (port == (unsigned long)-1)
 645                         return -EINVAL;
 646                 r->start = port;
 647                 r->end = port + size - 1;
 648         } else {
 649                 r->start = taddr;
 650                 r->end = taddr + size - 1;
 651         }
 652         r->flags = flags;
 653         r->name = name ? name : dev->full_name;
 654
 655         return 0;
 656 }
 657
 658 /**
 659  * of_address_to_resource - Translate device tree address and return as resource
 660  *
 661  * Note that if your address is a PIO address, the conversion will fail if
 662  * the physical address can't be internally converted to an IO token with
 663  * pci_address_to_pio(), that is because it's either called to early or it
 664  * can't be matched to any host bridge IO space
 665  */
 666 int of_address_to_resource(struct device_node *dev, int index,
 667                            struct resource *r)
 668 {
 669         const __be32    *addrp;
 670         u64             size;
 671         unsigned int    flags;
 672         const char      *name = NULL;
 673
 674         addrp = of_get_address(dev, index, &size, &flags);
 675         if (addrp == NULL)
 676                 return -EINVAL;
 677
 678         /* Get optional "reg-names" property to add a name to a resource */
 679         of_property_read_string_index(dev, "reg-names", index, &name);
 680
 681         return __of_address_to_resource(dev, addrp, size, flags, name, r);
 682 }
 683 EXPORT_SYMBOL_GPL(of_address_to_resource);
 684
 685 struct device_node *of_find_matching_node_by_address(struct device_node *from,
 686                                         const struct of_device_id *matches,
 687                                         u64 base_address)
 688 {
 689         struct device_node *dn = of_find_matching_node(from, matches);
 690         struct resource res;
 691
 692         while (dn) {
 693                 if (of_address_to_resource(dn, 0, &res))
 694                         continue;
 695                 if (res.start == base_address)
 696                         return dn;
 697                 dn = of_find_matching_node(dn, matches);
 698         }
 699
 700         return NULL;
 701 }
 702
 703
 704 /**
 705  * of_iomap - Maps the memory mapped IO for a given device_node
 706  * @device:     the device whose io range will be mapped
 707  * @index:      index of the io range
 708  *
 709  * Returns a pointer to the mapped memory
 710  */
 711 void __iomem *of_iomap(struct device_node *np, int index)
 712 {
 713         struct resource res;
 714
 715         if (of_address_to_resource(np, index, &res))
 716                 return NULL;
 717
 718         return ioremap(res.start, resource_size(&res));
 719 }
 720 EXPORT_SYMBOL(of_iomap);