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          * "pciex" is PCI Express
 103          * "vci" is for the /chaos bridge on 1st-gen PCI powermacs
 104          * "ht" is hypertransport
 105          */
 106         return !strcmp(np->type, "pci") || !strcmp(np->type, "pciex") ||
 107                 !strcmp(np->type, "vci") || !strcmp(np->type, "ht");
 108 }
 109
 110 static void of_bus_pci_count_cells(struct device_node *np,
 111                                    int *addrc, int *sizec)
 112 {
 113         if (addrc)
 114                 *addrc = 3;
 115         if (sizec)
 116                 *sizec = 2;
 117 }
 118
 119 static unsigned int of_bus_pci_get_flags(const __be32 *addr)
 120 {
 121         unsigned int flags = 0;
 122         u32 w = be32_to_cpup(addr);
 123
 124         switch((w >> 24) & 0x03) {
 125         case 0x01:
 126                 flags |= IORESOURCE_IO;
 127                 break;
 128         case 0x02: /* 32 bits */
 129         case 0x03: /* 64 bits */
 130                 flags |= IORESOURCE_MEM;
 131                 break;
 132         }
 133         if (w & 0x40000000)
 134                 flags |= IORESOURCE_PREFETCH;
 135         return flags;
 136 }
 137
 138 static u64 of_bus_pci_map(__be32 *addr, const __be32 *range, int na, int ns,
 139                 int pna)
 140 {
 141         u64 cp, s, da;
 142         unsigned int af, rf;
 143
 144         af = of_bus_pci_get_flags(addr);
 145         rf = of_bus_pci_get_flags(range);
 146
 147         /* Check address type match */
 148         if ((af ^ rf) & (IORESOURCE_MEM | IORESOURCE_IO))
 149                 return OF_BAD_ADDR;
 150
 151         /* Read address values, skipping high cell */
 152         cp = of_read_number(range + 1, na - 1);
 153         s  = of_read_number(range + na + pna, ns);
 154         da = of_read_number(addr + 1, na - 1);
 155
 156         pr_debug("OF: PCI map, cp=%llx, s=%llx, da=%llx\n",
 157                  (unsigned long long)cp, (unsigned long long)s,
 158                  (unsigned long long)da);
 159
 160         if (da < cp || da >= (cp + s))
 161                 return OF_BAD_ADDR;
 162         return da - cp;
 163 }
 164
 165 static int of_bus_pci_translate(__be32 *addr, u64 offset, int na)
 166 {
 167         return of_bus_default_translate(addr + 1, offset, na - 1);
 168 }
 169
 170 const __be32 *of_get_pci_address(struct device_node *dev, int bar_no, u64 *size,
 171                         unsigned int *flags)
 172 {
 173         const __be32 *prop;
 174         unsigned int psize;
 175         struct device_node *parent;
 176         struct of_bus *bus;
 177         int onesize, i, na, ns;
 178
 179         /* Get parent & match bus type */
 180         parent = of_get_parent(dev);
 181         if (parent == NULL)
 182                 return NULL;
 183         bus = of_match_bus(parent);
 184         if (strcmp(bus->name, "pci")) {
 185                 of_node_put(parent);
 186                 return NULL;
 187         }
 188         bus->count_cells(dev, &na, &ns);
 189         of_node_put(parent);
 190         if (!OF_CHECK_ADDR_COUNT(na))
 191                 return NULL;
 192
 193         /* Get "reg" or "assigned-addresses" property */
 194         prop = of_get_property(dev, bus->addresses, &psize);
 195         if (prop == NULL)
 196                 return NULL;
 197         psize /= 4;
 198
 199         onesize = na + ns;
 200         for (i = 0; psize >= onesize; psize -= onesize, prop += onesize, i++) {
 201                 u32 val = be32_to_cpu(prop[0]);
 202                 if ((val & 0xff) == ((bar_no * 4) + PCI_BASE_ADDRESS_0)) {
 203                         if (size)
 204                                 *size = of_read_number(prop + na, ns);
 205                         if (flags)
 206                                 *flags = bus->get_flags(prop);
 207                         return prop;
 208                 }
 209         }
 210         return NULL;
 211 }
 212 EXPORT_SYMBOL(of_get_pci_address);
 213
 214 int of_pci_address_to_resource(struct device_node *dev, int bar,
 215                                struct resource *r)
 216 {
 217         const __be32    *addrp;
 218         u64             size;
 219         unsigned int    flags;
 220
 221         addrp = of_get_pci_address(dev, bar, &size, &flags);
 222         if (addrp == NULL)
 223                 return -EINVAL;
 224         return __of_address_to_resource(dev, addrp, size, flags, NULL, r);
 225 }
 226 EXPORT_SYMBOL_GPL(of_pci_address_to_resource);
 227
 228 int of_pci_range_parser_init(struct of_pci_range_parser *parser,
 229                                 struct device_node *node)
 230 {
 231         const int na = 3, ns = 2;
 232         int rlen;
 233
 234         parser->node = node;
 235         parser->pna = of_n_addr_cells(node);
 236         parser->np = parser->pna + na + ns;
 237
 238         parser->range = of_get_property(node, "ranges", &rlen);
 239         if (parser->range == NULL)
 240                 return -ENOENT;
 241
 242         parser->end = parser->range + rlen / sizeof(__be32);
 243
 244         return 0;
 245 }
 246 EXPORT_SYMBOL_GPL(of_pci_range_parser_init);
 247
 248 struct of_pci_range *of_pci_range_parser_one(struct of_pci_range_parser *parser,
 249                                                 struct of_pci_range *range)
 250 {
 251         const int na = 3, ns = 2;
 252
 253         if (!range)
 254                 return NULL;
 255
 256         if (!parser->range || parser->range + parser->np > parser->end)
 257                 return NULL;
 258
 259         range->pci_space = parser->range[0];
 260         range->flags = of_bus_pci_get_flags(parser->range);
 261         range->pci_addr = of_read_number(parser->range + 1, ns);
 262         range->cpu_addr = of_translate_address(parser->node,
 263                                 parser->range + na);
 264         range->size = of_read_number(parser->range + parser->pna + na, ns);
 265
 266         parser->range += parser->np;
 267
 268         /* Now consume following elements while they are contiguous */
 269         while (parser->range + parser->np <= parser->end) {
 270                 u32 flags, pci_space;
 271                 u64 pci_addr, cpu_addr, size;
 272
 273                 pci_space = be32_to_cpup(parser->range);
 274                 flags = of_bus_pci_get_flags(parser->range);
 275                 pci_addr = of_read_number(parser->range + 1, ns);
 276                 cpu_addr = of_translate_address(parser->node,
 277                                 parser->range + na);
 278                 size = of_read_number(parser->range + parser->pna + na, ns);
 279
 280                 if (flags != range->flags)
 281                         break;
 282                 if (pci_addr != range->pci_addr + range->size ||
 283                     cpu_addr != range->cpu_addr + range->size)
 284                         break;
 285
 286                 range->size += size;
 287                 parser->range += parser->np;
 288         }
 289
 290         return range;
 291 }
 292 EXPORT_SYMBOL_GPL(of_pci_range_parser_one);
 293
 294 #endif /* CONFIG_PCI */
 295
 296 /*
 297  * ISA bus specific translator
 298  */
 299
 300 static int of_bus_isa_match(struct device_node *np)
 301 {
 302         return !strcmp(np->name, "isa");
 303 }
 304
 305 static void of_bus_isa_count_cells(struct device_node *child,
 306                                    int *addrc, int *sizec)
 307 {
 308         if (addrc)
 309                 *addrc = 2;
 310         if (sizec)
 311                 *sizec = 1;
 312 }
 313
 314 static u64 of_bus_isa_map(__be32 *addr, const __be32 *range, int na, int ns,
 315                 int pna)
 316 {
 317         u64 cp, s, da;
 318
 319         /* Check address type match */
 320         if ((addr[0] ^ range[0]) & cpu_to_be32(1))
 321                 return OF_BAD_ADDR;
 322
 323         /* Read address values, skipping high cell */
 324         cp = of_read_number(range + 1, na - 1);
 325         s  = of_read_number(range + na + pna, ns);
 326         da = of_read_number(addr + 1, na - 1);
 327
 328         pr_debug("OF: ISA map, cp=%llx, s=%llx, da=%llx\n",
 329                  (unsigned long long)cp, (unsigned long long)s,
 330                  (unsigned long long)da);
 331
 332         if (da < cp || da >= (cp + s))
 333                 return OF_BAD_ADDR;
 334         return da - cp;
 335 }
 336
 337 static int of_bus_isa_translate(__be32 *addr, u64 offset, int na)
 338 {
 339         return of_bus_default_translate(addr + 1, offset, na - 1);
 340 }
 341
 342 static unsigned int of_bus_isa_get_flags(const __be32 *addr)
 343 {
 344         unsigned int flags = 0;
 345         u32 w = be32_to_cpup(addr);
 346
 347         if (w & 1)
 348                 flags |= IORESOURCE_IO;
 349         else
 350                 flags |= IORESOURCE_MEM;
 351         return flags;
 352 }
 353
 354 /*
 355  * Array of bus specific translators
 356  */
 357
 358 static struct of_bus of_busses[] = {
 359 #ifdef CONFIG_PCI
 360         /* PCI */
 361         {
 362                 .name = "pci",
 363                 .addresses = "assigned-addresses",
 364                 .match = of_bus_pci_match,
 365                 .count_cells = of_bus_pci_count_cells,
 366                 .map = of_bus_pci_map,
 367                 .translate = of_bus_pci_translate,
 368                 .get_flags = of_bus_pci_get_flags,
 369         },
 370 #endif /* CONFIG_PCI */
 371         /* ISA */
 372         {
 373                 .name = "isa",
 374                 .addresses = "reg",
 375                 .match = of_bus_isa_match,
 376                 .count_cells = of_bus_isa_count_cells,
 377                 .map = of_bus_isa_map,
 378                 .translate = of_bus_isa_translate,
 379                 .get_flags = of_bus_isa_get_flags,
 380         },
 381         /* Default */
 382         {
 383                 .name = "default",
 384                 .addresses = "reg",
 385                 .match = NULL,
 386                 .count_cells = of_bus_default_count_cells,
 387                 .map = of_bus_default_map,
 388                 .translate = of_bus_default_translate,
 389                 .get_flags = of_bus_default_get_flags,
 390         },
 391 };
 392
 393 static struct of_bus *of_match_bus(struct device_node *np)
 394 {
 395         int i;
 396
 397         for (i = 0; i < ARRAY_SIZE(of_busses); i++)
 398                 if (!of_busses[i].match || of_busses[i].match(np))
 399                         return &of_busses[i];
 400         BUG();
 401         return NULL;
 402 }
 403
 404 static int of_empty_ranges_quirk(void)
 405 {
 406         if (IS_ENABLED(CONFIG_PPC)) {
 407                 /* To save cycles, we cache the result */
 408                 static int quirk_state = -1;
 409
 410                 if (quirk_state < 0)
 411                         quirk_state =
 412                                 of_machine_is_compatible("Power Macintosh") ||
 413                                 of_machine_is_compatible("MacRISC");
 414                 return quirk_state;
 415         }
 416         return false;
 417 }
 418
 419 static int of_translate_one(struct device_node *parent, struct of_bus *bus,
 420                             struct of_bus *pbus, __be32 *addr,
 421                             int na, int ns, int pna, const char *rprop)
 422 {
 423         const __be32 *ranges;
 424         unsigned int rlen;
 425         int rone;
 426         u64 offset = OF_BAD_ADDR;
 427
 428         /* Normally, an absence of a "ranges" property means we are
 429          * crossing a non-translatable boundary, and thus the addresses
 430          * below the current not cannot be converted to CPU physical ones.
 431          * Unfortunately, while this is very clear in the spec, it's not
 432          * what Apple understood, and they do have things like /uni-n or
 433          * /ht nodes with no "ranges" property and a lot of perfectly
 434          * useable mapped devices below them. Thus we treat the absence of
 435          * "ranges" as equivalent to an empty "ranges" property which means
 436          * a 1:1 translation at that level. It's up to the caller not to try
 437          * to translate addresses that aren't supposed to be translated in
 438          * the first place. --BenH.
 439          *
 440          * As far as we know, this damage only exists on Apple machines, so
 441          * This code is only enabled on powerpc. --gcl
 442          */
 443         ranges = of_get_property(parent, rprop, &rlen);
 444         if (ranges == NULL && !of_empty_ranges_quirk()) {
 445                 pr_err("OF: no ranges; cannot translate\n");
 446                 return 1;
 447         }
 448         if (ranges == NULL || rlen == 0) {
 449                 offset = of_read_number(addr, na);
 450                 memset(addr, 0, pna * 4);
 451                 pr_debug("OF: empty ranges; 1:1 translation\n");
 452                 goto finish;
 453         }
 454
 455         pr_debug("OF: walking ranges...\n");
 456
 457         /* Now walk through the ranges */
 458         rlen /= 4;
 459         rone = na + pna + ns;
 460         for (; rlen >= rone; rlen -= rone, ranges += rone) {
 461                 offset = bus->map(addr, ranges, na, ns, pna);
 462                 if (offset != OF_BAD_ADDR)
 463                         break;
 464         }
 465         if (offset == OF_BAD_ADDR) {
 466                 pr_debug("OF: not found !\n");
 467                 return 1;
 468         }
 469         memcpy(addr, ranges + na, 4 * pna);
 470
 471  finish:
 472         of_dump_addr("OF: parent translation for:", addr, pna);
 473         pr_debug("OF: with offset: %llx\n", (unsigned long long)offset);
 474
 475         /* Translate it into parent bus space */
 476         return pbus->translate(addr, offset, pna);
 477 }
 478
 479 /*
 480  * Translate an address from the device-tree into a CPU physical address,
 481  * this walks up the tree and applies the various bus mappings on the
 482  * way.
 483  *
 484  * Note: We consider that crossing any level with #size-cells == 0 to mean
 485  * that translation is impossible (that is we are not dealing with a value
 486  * that can be mapped to a cpu physical address). This is not really specified
 487  * that way, but this is traditionally the way IBM at least do things
 488  */
 489 static u64 __of_translate_address(struct device_node *dev,
 490                                   const __be32 *in_addr, const char *rprop)
 491 {
 492         struct device_node *parent = NULL;
 493         struct of_bus *bus, *pbus;
 494         __be32 addr[OF_MAX_ADDR_CELLS];
 495         int na, ns, pna, pns;
 496         u64 result = OF_BAD_ADDR;
 497
 498         pr_debug("OF: ** translation for device %s **\n", dev->full_name);
 499
 500         /* Increase refcount at current level */
 501         of_node_get(dev);
 502
 503         /* Get parent & match bus type */
 504         parent = of_get_parent(dev);
 505         if (parent == NULL)
 506                 goto bail;
 507         bus = of_match_bus(parent);
 508
 509         /* Count address cells & copy address locally */
 510         bus->count_cells(dev, &na, &ns);
 511         if (!OF_CHECK_COUNTS(na, ns)) {
 512                 printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
 513                        dev->full_name);
 514                 goto bail;
 515         }
 516         memcpy(addr, in_addr, na * 4);
 517
 518         pr_debug("OF: bus is %s (na=%d, ns=%d) on %s\n",
 519             bus->name, na, ns, parent->full_name);
 520         of_dump_addr("OF: translating address:", addr, na);
 521
 522         /* Translate */
 523         for (;;) {
 524                 /* Switch to parent bus */
 525                 of_node_put(dev);
 526                 dev = parent;
 527                 parent = of_get_parent(dev);
 528
 529                 /* If root, we have finished */
 530                 if (parent == NULL) {
 531                         pr_debug("OF: reached root node\n");
 532                         result = of_read_number(addr, na);
 533                         break;
 534                 }
 535
 536                 /* Get new parent bus and counts */
 537                 pbus = of_match_bus(parent);
 538                 pbus->count_cells(dev, &pna, &pns);
 539                 if (!OF_CHECK_COUNTS(pna, pns)) {
 540                         printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
 541                                dev->full_name);
 542                         break;
 543                 }
 544
 545                 pr_debug("OF: parent bus is %s (na=%d, ns=%d) on %s\n",
 546                     pbus->name, pna, pns, parent->full_name);
 547
 548                 /* Apply bus translation */
 549                 if (of_translate_one(dev, bus, pbus, addr, na, ns, pna, rprop))
 550                         break;
 551
 552                 /* Complete the move up one level */
 553                 na = pna;
 554                 ns = pns;
 555                 bus = pbus;
 556
 557                 of_dump_addr("OF: one level translation:", addr, na);
 558         }
 559  bail:
 560         of_node_put(parent);
 561         of_node_put(dev);
 562
 563         return result;
 564 }
 565
 566 u64 of_translate_address(struct device_node *dev, const __be32 *in_addr)
 567 {
 568         return __of_translate_address(dev, in_addr, "ranges");
 569 }
 570 EXPORT_SYMBOL(of_translate_address);
 571
 572 u64 of_translate_dma_address(struct device_node *dev, const __be32 *in_addr)
 573 {
 574         return __of_translate_address(dev, in_addr, "dma-ranges");
 575 }
 576 EXPORT_SYMBOL(of_translate_dma_address);
 577
 578 bool of_can_translate_address(struct device_node *dev)
 579 {
 580         struct device_node *parent;
 581         struct of_bus *bus;
 582         int na, ns;
 583
 584         parent = of_get_parent(dev);
 585         if (parent == NULL)
 586                 return false;
 587
 588         bus = of_match_bus(parent);
 589         bus->count_cells(dev, &na, &ns);
 590
 591         of_node_put(parent);
 592
 593         return OF_CHECK_COUNTS(na, ns);
 594 }
 595 EXPORT_SYMBOL(of_can_translate_address);
 596
 597 const __be32 *of_get_address(struct device_node *dev, int index, u64 *size,
 598                     unsigned int *flags)
 599 {
 600         const __be32 *prop;
 601         unsigned int psize;
 602         struct device_node *parent;
 603         struct of_bus *bus;
 604         int onesize, i, na, ns;
 605
 606         /* Get parent & match bus type */
 607         parent = of_get_parent(dev);
 608         if (parent == NULL)
 609                 return NULL;
 610         bus = of_match_bus(parent);
 611         bus->count_cells(dev, &na, &ns);
 612         of_node_put(parent);
 613         if (!OF_CHECK_ADDR_COUNT(na))
 614                 return NULL;
 615
 616         /* Get "reg" or "assigned-addresses" property */
 617         prop = of_get_property(dev, bus->addresses, &psize);
 618         if (prop == NULL)
 619                 return NULL;
 620         psize /= 4;
 621
 622         onesize = na + ns;
 623         for (i = 0; psize >= onesize; psize -= onesize, prop += onesize, i++)
 624                 if (i == index) {
 625                         if (size)
 626                                 *size = of_read_number(prop + na, ns);
 627                         if (flags)
 628                                 *flags = bus->get_flags(prop);
 629                         return prop;
 630                 }
 631         return NULL;
 632 }
 633 EXPORT_SYMBOL(of_get_address);
 634
 635 static int __of_address_to_resource(struct device_node *dev,
 636                 const __be32 *addrp, u64 size, unsigned int flags,
 637                 const char *name, struct resource *r)
 638 {
 639         u64 taddr;
 640
 641         if ((flags & (IORESOURCE_IO | IORESOURCE_MEM)) == 0)
 642                 return -EINVAL;
 643         taddr = of_translate_address(dev, addrp);
 644         if (taddr == OF_BAD_ADDR)
 645                 return -EINVAL;
 646         memset(r, 0, sizeof(struct resource));
 647         if (flags & IORESOURCE_IO) {
 648                 unsigned long port;
 649                 port = pci_address_to_pio(taddr);
 650                 if (port == (unsigned long)-1)
 651                         return -EINVAL;
 652                 r->start = port;
 653                 r->end = port + size - 1;
 654         } else {
 655                 r->start = taddr;
 656                 r->end = taddr + size - 1;
 657         }
 658         r->flags = flags;
 659         r->name = name ? name : dev->full_name;
 660
 661         return 0;
 662 }
 663
 664 /**
 665  * of_address_to_resource - Translate device tree address and return as resource
 666  *
 667  * Note that if your address is a PIO address, the conversion will fail if
 668  * the physical address can't be internally converted to an IO token with
 669  * pci_address_to_pio(), that is because it's either called to early or it
 670  * can't be matched to any host bridge IO space
 671  */
 672 int of_address_to_resource(struct device_node *dev, int index,
 673                            struct resource *r)
 674 {
 675         const __be32    *addrp;
 676         u64             size;
 677         unsigned int    flags;
 678         const char      *name = NULL;
 679
 680         addrp = of_get_address(dev, index, &size, &flags);
 681         if (addrp == NULL)
 682                 return -EINVAL;
 683
 684         /* Get optional "reg-names" property to add a name to a resource */
 685         of_property_read_string_index(dev, "reg-names", index, &name);
 686
 687         return __of_address_to_resource(dev, addrp, size, flags, name, r);
 688 }
 689 EXPORT_SYMBOL_GPL(of_address_to_resource);
 690
 691 struct device_node *of_find_matching_node_by_address(struct device_node *from,
 692                                         const struct of_device_id *matches,
 693                                         u64 base_address)
 694 {
 695         struct device_node *dn = of_find_matching_node(from, matches);
 696         struct resource res;
 697
 698         while (dn) {
 699                 if (of_address_to_resource(dn, 0, &res))
 700                         continue;
 701                 if (res.start == base_address)
 702                         return dn;
 703                 dn = of_find_matching_node(dn, matches);
 704         }
 705
 706         return NULL;
 707 }
 708
 709
 710 /**
 711  * of_iomap - Maps the memory mapped IO for a given device_node
 712  * @device:     the device whose io range will be mapped
 713  * @index:      index of the io range
 714  *
 715  * Returns a pointer to the mapped memory
 716  */
 717 void __iomem *of_iomap(struct device_node *np, int index)
 718 {
 719         struct resource res;
 720
 721         if (of_address_to_resource(np, index, &res))
 722                 return NULL;
 723
 724         return ioremap(res.start, resource_size(&res));
 725 }
 726 EXPORT_SYMBOL(of_iomap);