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         /*
  73          * If the number of address cells is larger than 2 we assume the
  74          * mapping doesn't specify a physical address. Rather, the address
  75          * specifies an identifier that must match exactly.
  76          */
  77         if (na > 2 && memcmp(range, addr, na * 4) != 0)
  78                 return OF_BAD_ADDR;
  79
  80         if (da < cp || da >= (cp + s))
  81                 return OF_BAD_ADDR;
  82         return da - cp;
  83 }
  84
  85 static int of_bus_default_translate(__be32 *addr, u64 offset, int na)
  86 {
  87         u64 a = of_read_number(addr, na);
  88         memset(addr, 0, na * 4);
  89         a += offset;
  90         if (na > 1)
  91                 addr[na - 2] = cpu_to_be32(a >> 32);
  92         addr[na - 1] = cpu_to_be32(a & 0xffffffffu);
  93
  94         return 0;
  95 }
  96
  97 static unsigned int of_bus_default_get_flags(const __be32 *addr)
  98 {
  99         return IORESOURCE_MEM;
 100 }
 101
 102 #ifdef CONFIG_PCI
 103 /*
 104  * PCI bus specific translator
 105  */
 106
 107 static int of_bus_pci_match(struct device_node *np)
 108 {
 109         /*
 110          * "vci" is for the /chaos bridge on 1st-gen PCI powermacs
 111          * "ht" is hypertransport
 112          */
 113         return !strcmp(np->type, "pci") || !strcmp(np->type, "vci") ||
 114                 !strcmp(np->type, "ht");
 115 }
 116
 117 static void of_bus_pci_count_cells(struct device_node *np,
 118                                    int *addrc, int *sizec)
 119 {
 120         if (addrc)
 121                 *addrc = 3;
 122         if (sizec)
 123                 *sizec = 2;
 124 }
 125
 126 static unsigned int of_bus_pci_get_flags(const __be32 *addr)
 127 {
 128         unsigned int flags = 0;
 129         u32 w = be32_to_cpup(addr);
 130
 131         switch((w >> 24) & 0x03) {
 132         case 0x01:
 133                 flags |= IORESOURCE_IO;
 134                 break;
 135         case 0x02: /* 32 bits */
 136         case 0x03: /* 64 bits */
 137                 flags |= IORESOURCE_MEM;
 138                 break;
 139         }
 140         if (w & 0x40000000)
 141                 flags |= IORESOURCE_PREFETCH;
 142         return flags;
 143 }
 144
 145 static u64 of_bus_pci_map(__be32 *addr, const __be32 *range, int na, int ns,
 146                 int pna)
 147 {
 148         u64 cp, s, da;
 149         unsigned int af, rf;
 150
 151         af = of_bus_pci_get_flags(addr);
 152         rf = of_bus_pci_get_flags(range);
 153
 154         /* Check address type match */
 155         if ((af ^ rf) & (IORESOURCE_MEM | IORESOURCE_IO))
 156                 return OF_BAD_ADDR;
 157
 158         /* Read address values, skipping high cell */
 159         cp = of_read_number(range + 1, na - 1);
 160         s  = of_read_number(range + na + pna, ns);
 161         da = of_read_number(addr + 1, na - 1);
 162
 163         pr_debug("OF: PCI map, cp=%llx, s=%llx, da=%llx\n",
 164                  (unsigned long long)cp, (unsigned long long)s,
 165                  (unsigned long long)da);
 166
 167         if (da < cp || da >= (cp + s))
 168                 return OF_BAD_ADDR;
 169         return da - cp;
 170 }
 171
 172 static int of_bus_pci_translate(__be32 *addr, u64 offset, int na)
 173 {
 174         return of_bus_default_translate(addr + 1, offset, na - 1);
 175 }
 176
 177 const __be32 *of_get_pci_address(struct device_node *dev, int bar_no, u64 *size,
 178                         unsigned int *flags)
 179 {
 180         const __be32 *prop;
 181         unsigned int psize;
 182         struct device_node *parent;
 183         struct of_bus *bus;
 184         int onesize, i, na, ns;
 185
 186         /* Get parent & match bus type */
 187         parent = of_get_parent(dev);
 188         if (parent == NULL)
 189                 return NULL;
 190         bus = of_match_bus(parent);
 191         if (strcmp(bus->name, "pci")) {
 192                 of_node_put(parent);
 193                 return NULL;
 194         }
 195         bus->count_cells(dev, &na, &ns);
 196         of_node_put(parent);
 197         if (!OF_CHECK_ADDR_COUNT(na))
 198                 return NULL;
 199
 200         /* Get "reg" or "assigned-addresses" property */
 201         prop = of_get_property(dev, bus->addresses, &psize);
 202         if (prop == NULL)
 203                 return NULL;
 204         psize /= 4;
 205
 206         onesize = na + ns;
 207         for (i = 0; psize >= onesize; psize -= onesize, prop += onesize, i++) {
 208                 u32 val = be32_to_cpu(prop[0]);
 209                 if ((val & 0xff) == ((bar_no * 4) + PCI_BASE_ADDRESS_0)) {
 210                         if (size)
 211                                 *size = of_read_number(prop + na, ns);
 212                         if (flags)
 213                                 *flags = bus->get_flags(prop);
 214                         return prop;
 215                 }
 216         }
 217         return NULL;
 218 }
 219 EXPORT_SYMBOL(of_get_pci_address);
 220
 221 int of_pci_address_to_resource(struct device_node *dev, int bar,
 222                                struct resource *r)
 223 {
 224         const __be32    *addrp;
 225         u64             size;
 226         unsigned int    flags;
 227
 228         addrp = of_get_pci_address(dev, bar, &size, &flags);
 229         if (addrp == NULL)
 230                 return -EINVAL;
 231         return __of_address_to_resource(dev, addrp, size, flags, NULL, r);
 232 }
 233 EXPORT_SYMBOL_GPL(of_pci_address_to_resource);
 234
 235 int of_pci_range_parser_init(struct of_pci_range_parser *parser,
 236                                 struct device_node *node)
 237 {
 238         const int na = 3, ns = 2;
 239         int rlen;
 240
 241         parser->node = node;
 242         parser->pna = of_n_addr_cells(node);
 243         parser->np = parser->pna + na + ns;
 244
 245         parser->range = of_get_property(node, "ranges", &rlen);
 246         if (parser->range == NULL)
 247                 return -ENOENT;
 248
 249         parser->end = parser->range + rlen / sizeof(__be32);
 250
 251         return 0;
 252 }
 253 EXPORT_SYMBOL_GPL(of_pci_range_parser_init);
 254
 255 struct of_pci_range *of_pci_range_parser_one(struct of_pci_range_parser *parser,
 256                                                 struct of_pci_range *range)
 257 {
 258         const int na = 3, ns = 2;
 259
 260         if (!range)
 261                 return NULL;
 262
 263         if (!parser->range || parser->range + parser->np > parser->end)
 264                 return NULL;
 265
 266         range->pci_space = parser->range[0];
 267         range->flags = of_bus_pci_get_flags(parser->range);
 268         range->pci_addr = of_read_number(parser->range + 1, ns);
 269         range->cpu_addr = of_translate_address(parser->node,
 270                                 parser->range + na);
 271         range->size = of_read_number(parser->range + parser->pna + na, ns);
 272
 273         parser->range += parser->np;
 274
 275         /* Now consume following elements while they are contiguous */
 276         while (parser->range + parser->np <= parser->end) {
 277                 u32 flags, pci_space;
 278                 u64 pci_addr, cpu_addr, size;
 279
 280                 pci_space = be32_to_cpup(parser->range);
 281                 flags = of_bus_pci_get_flags(parser->range);
 282                 pci_addr = of_read_number(parser->range + 1, ns);
 283                 cpu_addr = of_translate_address(parser->node,
 284                                 parser->range + na);
 285                 size = of_read_number(parser->range + parser->pna + na, ns);
 286
 287                 if (flags != range->flags)
 288                         break;
 289                 if (pci_addr != range->pci_addr + range->size ||
 290                     cpu_addr != range->cpu_addr + range->size)
 291                         break;
 292
 293                 range->size += size;
 294                 parser->range += parser->np;
 295         }
 296
 297         return range;
 298 }
 299 EXPORT_SYMBOL_GPL(of_pci_range_parser_one);
 300
 301 #endif /* CONFIG_PCI */
 302
 303 /*
 304  * ISA bus specific translator
 305  */
 306
 307 static int of_bus_isa_match(struct device_node *np)
 308 {
 309         return !strcmp(np->name, "isa");
 310 }
 311
 312 static void of_bus_isa_count_cells(struct device_node *child,
 313                                    int *addrc, int *sizec)
 314 {
 315         if (addrc)
 316                 *addrc = 2;
 317         if (sizec)
 318                 *sizec = 1;
 319 }
 320
 321 static u64 of_bus_isa_map(__be32 *addr, const __be32 *range, int na, int ns,
 322                 int pna)
 323 {
 324         u64 cp, s, da;
 325
 326         /* Check address type match */
 327         if ((addr[0] ^ range[0]) & cpu_to_be32(1))
 328                 return OF_BAD_ADDR;
 329
 330         /* Read address values, skipping high cell */
 331         cp = of_read_number(range + 1, na - 1);
 332         s  = of_read_number(range + na + pna, ns);
 333         da = of_read_number(addr + 1, na - 1);
 334
 335         pr_debug("OF: ISA map, cp=%llx, s=%llx, da=%llx\n",
 336                  (unsigned long long)cp, (unsigned long long)s,
 337                  (unsigned long long)da);
 338
 339         if (da < cp || da >= (cp + s))
 340                 return OF_BAD_ADDR;
 341         return da - cp;
 342 }
 343
 344 static int of_bus_isa_translate(__be32 *addr, u64 offset, int na)
 345 {
 346         return of_bus_default_translate(addr + 1, offset, na - 1);
 347 }
 348
 349 static unsigned int of_bus_isa_get_flags(const __be32 *addr)
 350 {
 351         unsigned int flags = 0;
 352         u32 w = be32_to_cpup(addr);
 353
 354         if (w & 1)
 355                 flags |= IORESOURCE_IO;
 356         else
 357                 flags |= IORESOURCE_MEM;
 358         return flags;
 359 }
 360
 361 /*
 362  * Array of bus specific translators
 363  */
 364
 365 static struct of_bus of_busses[] = {
 366 #ifdef CONFIG_PCI
 367         /* PCI */
 368         {
 369                 .name = "pci",
 370                 .addresses = "assigned-addresses",
 371                 .match = of_bus_pci_match,
 372                 .count_cells = of_bus_pci_count_cells,
 373                 .map = of_bus_pci_map,
 374                 .translate = of_bus_pci_translate,
 375                 .get_flags = of_bus_pci_get_flags,
 376         },
 377 #endif /* CONFIG_PCI */
 378         /* ISA */
 379         {
 380                 .name = "isa",
 381                 .addresses = "reg",
 382                 .match = of_bus_isa_match,
 383                 .count_cells = of_bus_isa_count_cells,
 384                 .map = of_bus_isa_map,
 385                 .translate = of_bus_isa_translate,
 386                 .get_flags = of_bus_isa_get_flags,
 387         },
 388         /* Default */
 389         {
 390                 .name = "default",
 391                 .addresses = "reg",
 392                 .match = NULL,
 393                 .count_cells = of_bus_default_count_cells,
 394                 .map = of_bus_default_map,
 395                 .translate = of_bus_default_translate,
 396                 .get_flags = of_bus_default_get_flags,
 397         },
 398 };
 399
 400 static struct of_bus *of_match_bus(struct device_node *np)
 401 {
 402         int i;
 403
 404         for (i = 0; i < ARRAY_SIZE(of_busses); i++)
 405                 if (!of_busses[i].match || of_busses[i].match(np))
 406                         return &of_busses[i];
 407         BUG();
 408         return NULL;
 409 }
 410
 411 static int of_translate_one(struct device_node *parent, struct of_bus *bus,
 412                             struct of_bus *pbus, __be32 *addr,
 413                             int na, int ns, int pna, const char *rprop)
 414 {
 415         const __be32 *ranges;
 416         unsigned int rlen;
 417         int rone;
 418         u64 offset = OF_BAD_ADDR;
 419
 420         /* Normally, an absence of a "ranges" property means we are
 421          * crossing a non-translatable boundary, and thus the addresses
 422          * below the current not cannot be converted to CPU physical ones.
 423          * Unfortunately, while this is very clear in the spec, it's not
 424          * what Apple understood, and they do have things like /uni-n or
 425          * /ht nodes with no "ranges" property and a lot of perfectly
 426          * useable mapped devices below them. Thus we treat the absence of
 427          * "ranges" as equivalent to an empty "ranges" property which means
 428          * a 1:1 translation at that level. It's up to the caller not to try
 429          * to translate addresses that aren't supposed to be translated in
 430          * the first place. --BenH.
 431          *
 432          * As far as we know, this damage only exists on Apple machines, so
 433          * This code is only enabled on powerpc. --gcl
 434          */
 435         ranges = of_get_property(parent, rprop, &rlen);
 436 #if !defined(CONFIG_PPC)
 437         if (ranges == NULL) {
 438                 pr_err("OF: no ranges; cannot translate\n");
 439                 return 1;
 440         }
 441 #endif /* !defined(CONFIG_PPC) */
 442         if (ranges == NULL || rlen == 0) {
 443                 offset = of_read_number(addr, na);
 444                 memset(addr, 0, pna * 4);
 445                 pr_debug("OF: empty ranges; 1:1 translation\n");
 446                 goto finish;
 447         }
 448
 449         pr_debug("OF: walking ranges...\n");
 450
 451         /* Now walk through the ranges */
 452         rlen /= 4;
 453         rone = na + pna + ns;
 454         for (; rlen >= rone; rlen -= rone, ranges += rone) {
 455                 offset = bus->map(addr, ranges, na, ns, pna);
 456                 if (offset != OF_BAD_ADDR)
 457                         break;
 458         }
 459         if (offset == OF_BAD_ADDR) {
 460                 pr_debug("OF: not found !\n");
 461                 return 1;
 462         }
 463         memcpy(addr, ranges + na, 4 * pna);
 464
 465  finish:
 466         of_dump_addr("OF: parent translation for:", addr, pna);
 467         pr_debug("OF: with offset: %llx\n", (unsigned long long)offset);
 468
 469         /* Translate it into parent bus space */
 470         return pbus->translate(addr, offset, pna);
 471 }
 472
 473 /*
 474  * Translate an address from the device-tree into a CPU physical address,
 475  * this walks up the tree and applies the various bus mappings on the
 476  * way.
 477  *
 478  * Note: We consider that crossing any level with #size-cells == 0 to mean
 479  * that translation is impossible (that is we are not dealing with a value
 480  * that can be mapped to a cpu physical address). This is not really specified
 481  * that way, but this is traditionally the way IBM at least do things
 482  */
 483 static u64 __of_translate_address(struct device_node *dev,
 484                                   const __be32 *in_addr, const char *rprop)
 485 {
 486         struct device_node *parent = NULL;
 487         struct of_bus *bus, *pbus;
 488         __be32 addr[OF_MAX_ADDR_CELLS];
 489         int na, ns, pna, pns;
 490         u64 result = OF_BAD_ADDR;
 491
 492         pr_debug("OF: ** translation for device %s **\n", dev->full_name);
 493
 494         /* Increase refcount at current level */
 495         of_node_get(dev);
 496
 497         /* Get parent & match bus type */
 498         parent = of_get_parent(dev);
 499         if (parent == NULL)
 500                 goto bail;
 501         bus = of_match_bus(parent);
 502
 503         /* Count address cells & copy address locally */
 504         bus->count_cells(dev, &na, &ns);
 505         if (!OF_CHECK_COUNTS(na, ns)) {
 506                 printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
 507                        dev->full_name);
 508                 goto bail;
 509         }
 510         memcpy(addr, in_addr, na * 4);
 511
 512         pr_debug("OF: bus is %s (na=%d, ns=%d) on %s\n",
 513             bus->name, na, ns, parent->full_name);
 514         of_dump_addr("OF: translating address:", addr, na);
 515
 516         /* Translate */
 517         for (;;) {
 518                 /* Switch to parent bus */
 519                 of_node_put(dev);
 520                 dev = parent;
 521                 parent = of_get_parent(dev);
 522
 523                 /* If root, we have finished */
 524                 if (parent == NULL) {
 525                         pr_debug("OF: reached root node\n");
 526                         result = of_read_number(addr, na);
 527                         break;
 528                 }
 529
 530                 /* Get new parent bus and counts */
 531                 pbus = of_match_bus(parent);
 532                 pbus->count_cells(dev, &pna, &pns);
 533                 if (!OF_CHECK_COUNTS(pna, pns)) {
 534                         printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
 535                                dev->full_name);
 536                         break;
 537                 }
 538
 539                 pr_debug("OF: parent bus is %s (na=%d, ns=%d) on %s\n",
 540                     pbus->name, pna, pns, parent->full_name);
 541
 542                 /* Apply bus translation */
 543                 if (of_translate_one(dev, bus, pbus, addr, na, ns, pna, rprop))
 544                         break;
 545
 546                 /* Complete the move up one level */
 547                 na = pna;
 548                 ns = pns;
 549                 bus = pbus;
 550
 551                 of_dump_addr("OF: one level translation:", addr, na);
 552         }
 553  bail:
 554         of_node_put(parent);
 555         of_node_put(dev);
 556
 557         return result;
 558 }
 559
 560 u64 of_translate_address(struct device_node *dev, const __be32 *in_addr)
 561 {
 562         return __of_translate_address(dev, in_addr, "ranges");
 563 }
 564 EXPORT_SYMBOL(of_translate_address);
 565
 566 u64 of_translate_dma_address(struct device_node *dev, const __be32 *in_addr)
 567 {
 568         return __of_translate_address(dev, in_addr, "dma-ranges");
 569 }
 570 EXPORT_SYMBOL(of_translate_dma_address);
 571
 572 bool of_can_translate_address(struct device_node *dev)
 573 {
 574         struct device_node *parent;
 575         struct of_bus *bus;
 576         int na, ns;
 577
 578         parent = of_get_parent(dev);
 579         if (parent == NULL)
 580                 return false;
 581
 582         bus = of_match_bus(parent);
 583         bus->count_cells(dev, &na, &ns);
 584
 585         of_node_put(parent);
 586
 587         return OF_CHECK_COUNTS(na, ns);
 588 }
 589 EXPORT_SYMBOL(of_can_translate_address);
 590
 591 const __be32 *of_get_address(struct device_node *dev, int index, u64 *size,
 592                     unsigned int *flags)
 593 {
 594         const __be32 *prop;
 595         unsigned int psize;
 596         struct device_node *parent;
 597         struct of_bus *bus;
 598         int onesize, i, na, ns;
 599
 600         /* Get parent & match bus type */
 601         parent = of_get_parent(dev);
 602         if (parent == NULL)
 603                 return NULL;
 604         bus = of_match_bus(parent);
 605         bus->count_cells(dev, &na, &ns);
 606         of_node_put(parent);
 607         if (!OF_CHECK_ADDR_COUNT(na))
 608                 return NULL;
 609
 610         /* Get "reg" or "assigned-addresses" property */
 611         prop = of_get_property(dev, bus->addresses, &psize);
 612         if (prop == NULL)
 613                 return NULL;
 614         psize /= 4;
 615
 616         onesize = na + ns;
 617         for (i = 0; psize >= onesize; psize -= onesize, prop += onesize, i++)
 618                 if (i == index) {
 619                         if (size)
 620                                 *size = of_read_number(prop + na, ns);
 621                         if (flags)
 622                                 *flags = bus->get_flags(prop);
 623                         return prop;
 624                 }
 625         return NULL;
 626 }
 627 EXPORT_SYMBOL(of_get_address);
 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);