linux/drivers/firmware/dmi_scan.c
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   1#include <linux/types.h>
   2#include <linux/string.h>
   3#include <linux/init.h>
   4#include <linux/module.h>
   5#include <linux/ctype.h>
   6#include <linux/dmi.h>
   7#include <linux/efi.h>
   8#include <linux/bootmem.h>
   9#include <linux/random.h>
  10#include <asm/dmi.h>
  11
  12/*
  13 * DMI stands for "Desktop Management Interface".  It is part
  14 * of and an antecedent to, SMBIOS, which stands for System
  15 * Management BIOS.  See further: http://www.dmtf.org/standards
  16 */
  17static char dmi_empty_string[] = "        ";
  18
  19static u16 __initdata dmi_ver;
  20/*
  21 * Catch too early calls to dmi_check_system():
  22 */
  23static int dmi_initialized;
  24
  25/* DMI system identification string used during boot */
  26static char dmi_ids_string[128] __initdata;
  27
  28static const char * __init dmi_string_nosave(const struct dmi_header *dm, u8 s)
  29{
  30        const u8 *bp = ((u8 *) dm) + dm->length;
  31
  32        if (s) {
  33                s--;
  34                while (s > 0 && *bp) {
  35                        bp += strlen(bp) + 1;
  36                        s--;
  37                }
  38
  39                if (*bp != 0) {
  40                        size_t len = strlen(bp)+1;
  41                        size_t cmp_len = len > 8 ? 8 : len;
  42
  43                        if (!memcmp(bp, dmi_empty_string, cmp_len))
  44                                return dmi_empty_string;
  45                        return bp;
  46                }
  47        }
  48
  49        return "";
  50}
  51
  52static char * __init dmi_string(const struct dmi_header *dm, u8 s)
  53{
  54        const char *bp = dmi_string_nosave(dm, s);
  55        char *str;
  56        size_t len;
  57
  58        if (bp == dmi_empty_string)
  59                return dmi_empty_string;
  60
  61        len = strlen(bp) + 1;
  62        str = dmi_alloc(len);
  63        if (str != NULL)
  64                strcpy(str, bp);
  65        else
  66                printk(KERN_ERR "dmi_string: cannot allocate %Zu bytes.\n", len);
  67
  68        return str;
  69}
  70
  71/*
  72 *      We have to be cautious here. We have seen BIOSes with DMI pointers
  73 *      pointing to completely the wrong place for example
  74 */
  75static void dmi_table(u8 *buf, int len, int num,
  76                      void (*decode)(const struct dmi_header *, void *),
  77                      void *private_data)
  78{
  79        u8 *data = buf;
  80        int i = 0;
  81
  82        /*
  83         *      Stop when we see all the items the table claimed to have
  84         *      OR we run off the end of the table (also happens)
  85         */
  86        while ((i < num) && (data - buf + sizeof(struct dmi_header)) <= len) {
  87                const struct dmi_header *dm = (const struct dmi_header *)data;
  88
  89                /*
  90                 *  We want to know the total length (formatted area and
  91                 *  strings) before decoding to make sure we won't run off the
  92                 *  table in dmi_decode or dmi_string
  93                 */
  94                data += dm->length;
  95                while ((data - buf < len - 1) && (data[0] || data[1]))
  96                        data++;
  97                if (data - buf < len - 1)
  98                        decode(dm, private_data);
  99                data += 2;
 100                i++;
 101        }
 102}
 103
 104static u32 dmi_base;
 105static u16 dmi_len;
 106static u16 dmi_num;
 107
 108static int __init dmi_walk_early(void (*decode)(const struct dmi_header *,
 109                void *))
 110{
 111        u8 *buf;
 112
 113        buf = dmi_ioremap(dmi_base, dmi_len);
 114        if (buf == NULL)
 115                return -1;
 116
 117        dmi_table(buf, dmi_len, dmi_num, decode, NULL);
 118
 119        add_device_randomness(buf, dmi_len);
 120
 121        dmi_iounmap(buf, dmi_len);
 122        return 0;
 123}
 124
 125static int __init dmi_checksum(const u8 *buf, u8 len)
 126{
 127        u8 sum = 0;
 128        int a;
 129
 130        for (a = 0; a < len; a++)
 131                sum += buf[a];
 132
 133        return sum == 0;
 134}
 135
 136static char *dmi_ident[DMI_STRING_MAX];
 137static LIST_HEAD(dmi_devices);
 138int dmi_available;
 139
 140/*
 141 *      Save a DMI string
 142 */
 143static void __init dmi_save_ident(const struct dmi_header *dm, int slot, int string)
 144{
 145        const char *d = (const char*) dm;
 146        char *p;
 147
 148        if (dmi_ident[slot])
 149                return;
 150
 151        p = dmi_string(dm, d[string]);
 152        if (p == NULL)
 153                return;
 154
 155        dmi_ident[slot] = p;
 156}
 157
 158static void __init dmi_save_uuid(const struct dmi_header *dm, int slot, int index)
 159{
 160        const u8 *d = (u8*) dm + index;
 161        char *s;
 162        int is_ff = 1, is_00 = 1, i;
 163
 164        if (dmi_ident[slot])
 165                return;
 166
 167        for (i = 0; i < 16 && (is_ff || is_00); i++) {
 168                if (d[i] != 0x00)
 169                        is_00 = 0;
 170                if (d[i] != 0xFF)
 171                        is_ff = 0;
 172        }
 173
 174        if (is_ff || is_00)
 175                return;
 176
 177        s = dmi_alloc(16*2+4+1);
 178        if (!s)
 179                return;
 180
 181        /*
 182         * As of version 2.6 of the SMBIOS specification, the first 3 fields of
 183         * the UUID are supposed to be little-endian encoded.  The specification
 184         * says that this is the defacto standard.
 185         */
 186        if (dmi_ver >= 0x0206)
 187                sprintf(s, "%pUL", d);
 188        else
 189                sprintf(s, "%pUB", d);
 190
 191        dmi_ident[slot] = s;
 192}
 193
 194static void __init dmi_save_type(const struct dmi_header *dm, int slot, int index)
 195{
 196        const u8 *d = (u8*) dm + index;
 197        char *s;
 198
 199        if (dmi_ident[slot])
 200                return;
 201
 202        s = dmi_alloc(4);
 203        if (!s)
 204                return;
 205
 206        sprintf(s, "%u", *d & 0x7F);
 207        dmi_ident[slot] = s;
 208}
 209
 210static void __init dmi_save_one_device(int type, const char *name)
 211{
 212        struct dmi_device *dev;
 213
 214        /* No duplicate device */
 215        if (dmi_find_device(type, name, NULL))
 216                return;
 217
 218        dev = dmi_alloc(sizeof(*dev) + strlen(name) + 1);
 219        if (!dev) {
 220                printk(KERN_ERR "dmi_save_one_device: out of memory.\n");
 221                return;
 222        }
 223
 224        dev->type = type;
 225        strcpy((char *)(dev + 1), name);
 226        dev->name = (char *)(dev + 1);
 227        dev->device_data = NULL;
 228        list_add(&dev->list, &dmi_devices);
 229}
 230
 231static void __init dmi_save_devices(const struct dmi_header *dm)
 232{
 233        int i, count = (dm->length - sizeof(struct dmi_header)) / 2;
 234
 235        for (i = 0; i < count; i++) {
 236                const char *d = (char *)(dm + 1) + (i * 2);
 237
 238                /* Skip disabled device */
 239                if ((*d & 0x80) == 0)
 240                        continue;
 241
 242                dmi_save_one_device(*d & 0x7f, dmi_string_nosave(dm, *(d + 1)));
 243        }
 244}
 245
 246static void __init dmi_save_oem_strings_devices(const struct dmi_header *dm)
 247{
 248        int i, count = *(u8 *)(dm + 1);
 249        struct dmi_device *dev;
 250
 251        for (i = 1; i <= count; i++) {
 252                char *devname = dmi_string(dm, i);
 253
 254                if (devname == dmi_empty_string)
 255                        continue;
 256
 257                dev = dmi_alloc(sizeof(*dev));
 258                if (!dev) {
 259                        printk(KERN_ERR
 260                           "dmi_save_oem_strings_devices: out of memory.\n");
 261                        break;
 262                }
 263
 264                dev->type = DMI_DEV_TYPE_OEM_STRING;
 265                dev->name = devname;
 266                dev->device_data = NULL;
 267
 268                list_add(&dev->list, &dmi_devices);
 269        }
 270}
 271
 272static void __init dmi_save_ipmi_device(const struct dmi_header *dm)
 273{
 274        struct dmi_device *dev;
 275        void * data;
 276
 277        data = dmi_alloc(dm->length);
 278        if (data == NULL) {
 279                printk(KERN_ERR "dmi_save_ipmi_device: out of memory.\n");
 280                return;
 281        }
 282
 283        memcpy(data, dm, dm->length);
 284
 285        dev = dmi_alloc(sizeof(*dev));
 286        if (!dev) {
 287                printk(KERN_ERR "dmi_save_ipmi_device: out of memory.\n");
 288                return;
 289        }
 290
 291        dev->type = DMI_DEV_TYPE_IPMI;
 292        dev->name = "IPMI controller";
 293        dev->device_data = data;
 294
 295        list_add_tail(&dev->list, &dmi_devices);
 296}
 297
 298static void __init dmi_save_dev_onboard(int instance, int segment, int bus,
 299                                        int devfn, const char *name)
 300{
 301        struct dmi_dev_onboard *onboard_dev;
 302
 303        onboard_dev = dmi_alloc(sizeof(*onboard_dev) + strlen(name) + 1);
 304        if (!onboard_dev) {
 305                printk(KERN_ERR "dmi_save_dev_onboard: out of memory.\n");
 306                return;
 307        }
 308        onboard_dev->instance = instance;
 309        onboard_dev->segment = segment;
 310        onboard_dev->bus = bus;
 311        onboard_dev->devfn = devfn;
 312
 313        strcpy((char *)&onboard_dev[1], name);
 314        onboard_dev->dev.type = DMI_DEV_TYPE_DEV_ONBOARD;
 315        onboard_dev->dev.name = (char *)&onboard_dev[1];
 316        onboard_dev->dev.device_data = onboard_dev;
 317
 318        list_add(&onboard_dev->dev.list, &dmi_devices);
 319}
 320
 321static void __init dmi_save_extended_devices(const struct dmi_header *dm)
 322{
 323        const u8 *d = (u8*) dm + 5;
 324
 325        /* Skip disabled device */
 326        if ((*d & 0x80) == 0)
 327                return;
 328
 329        dmi_save_dev_onboard(*(d+1), *(u16 *)(d+2), *(d+4), *(d+5),
 330                             dmi_string_nosave(dm, *(d-1)));
 331        dmi_save_one_device(*d & 0x7f, dmi_string_nosave(dm, *(d - 1)));
 332}
 333
 334/*
 335 *      Process a DMI table entry. Right now all we care about are the BIOS
 336 *      and machine entries. For 2.5 we should pull the smbus controller info
 337 *      out of here.
 338 */
 339static void __init dmi_decode(const struct dmi_header *dm, void *dummy)
 340{
 341        switch(dm->type) {
 342        case 0:         /* BIOS Information */
 343                dmi_save_ident(dm, DMI_BIOS_VENDOR, 4);
 344                dmi_save_ident(dm, DMI_BIOS_VERSION, 5);
 345                dmi_save_ident(dm, DMI_BIOS_DATE, 8);
 346                break;
 347        case 1:         /* System Information */
 348                dmi_save_ident(dm, DMI_SYS_VENDOR, 4);
 349                dmi_save_ident(dm, DMI_PRODUCT_NAME, 5);
 350                dmi_save_ident(dm, DMI_PRODUCT_VERSION, 6);
 351                dmi_save_ident(dm, DMI_PRODUCT_SERIAL, 7);
 352                dmi_save_uuid(dm, DMI_PRODUCT_UUID, 8);
 353                break;
 354        case 2:         /* Base Board Information */
 355                dmi_save_ident(dm, DMI_BOARD_VENDOR, 4);
 356                dmi_save_ident(dm, DMI_BOARD_NAME, 5);
 357                dmi_save_ident(dm, DMI_BOARD_VERSION, 6);
 358                dmi_save_ident(dm, DMI_BOARD_SERIAL, 7);
 359                dmi_save_ident(dm, DMI_BOARD_ASSET_TAG, 8);
 360                break;
 361        case 3:         /* Chassis Information */
 362                dmi_save_ident(dm, DMI_CHASSIS_VENDOR, 4);
 363                dmi_save_type(dm, DMI_CHASSIS_TYPE, 5);
 364                dmi_save_ident(dm, DMI_CHASSIS_VERSION, 6);
 365                dmi_save_ident(dm, DMI_CHASSIS_SERIAL, 7);
 366                dmi_save_ident(dm, DMI_CHASSIS_ASSET_TAG, 8);
 367                break;
 368        case 10:        /* Onboard Devices Information */
 369                dmi_save_devices(dm);
 370                break;
 371        case 11:        /* OEM Strings */
 372                dmi_save_oem_strings_devices(dm);
 373                break;
 374        case 38:        /* IPMI Device Information */
 375                dmi_save_ipmi_device(dm);
 376                break;
 377        case 41:        /* Onboard Devices Extended Information */
 378                dmi_save_extended_devices(dm);
 379        }
 380}
 381
 382static int __init print_filtered(char *buf, size_t len, const char *info)
 383{
 384        int c = 0;
 385        const char *p;
 386
 387        if (!info)
 388                return c;
 389
 390        for (p = info; *p; p++)
 391                if (isprint(*p))
 392                        c += scnprintf(buf + c, len - c, "%c", *p);
 393                else
 394                        c += scnprintf(buf + c, len - c, "\\x%02x", *p & 0xff);
 395        return c;
 396}
 397
 398static void __init dmi_format_ids(char *buf, size_t len)
 399{
 400        int c = 0;
 401        const char *board;      /* Board Name is optional */
 402
 403        c += print_filtered(buf + c, len - c,
 404                            dmi_get_system_info(DMI_SYS_VENDOR));
 405        c += scnprintf(buf + c, len - c, " ");
 406        c += print_filtered(buf + c, len - c,
 407                            dmi_get_system_info(DMI_PRODUCT_NAME));
 408
 409        board = dmi_get_system_info(DMI_BOARD_NAME);
 410        if (board) {
 411                c += scnprintf(buf + c, len - c, "/");
 412                c += print_filtered(buf + c, len - c, board);
 413        }
 414        c += scnprintf(buf + c, len - c, ", BIOS ");
 415        c += print_filtered(buf + c, len - c,
 416                            dmi_get_system_info(DMI_BIOS_VERSION));
 417        c += scnprintf(buf + c, len - c, " ");
 418        c += print_filtered(buf + c, len - c,
 419                            dmi_get_system_info(DMI_BIOS_DATE));
 420}
 421
 422/*
 423 * Check for DMI/SMBIOS headers in the system firmware image.  Any
 424 * SMBIOS header must start 16 bytes before the DMI header, so take a
 425 * 32 byte buffer and check for DMI at offset 16 and SMBIOS at offset
 426 * 0.  If the DMI header is present, set dmi_ver accordingly (SMBIOS
 427 * takes precedence) and return 0.  Otherwise return 1.
 428 */
 429static int __init dmi_present(const u8 *buf)
 430{
 431        int smbios_ver;
 432
 433        if (memcmp(buf, "_SM_", 4) == 0 &&
 434            buf[5] < 32 && dmi_checksum(buf, buf[5])) {
 435                smbios_ver = (buf[6] << 8) + buf[7];
 436
 437                /* Some BIOS report weird SMBIOS version, fix that up */
 438                switch (smbios_ver) {
 439                case 0x021F:
 440                case 0x0221:
 441                        pr_debug("SMBIOS version fixup(2.%d->2.%d)\n",
 442                                 smbios_ver & 0xFF, 3);
 443                        smbios_ver = 0x0203;
 444                        break;
 445                case 0x0233:
 446                        pr_debug("SMBIOS version fixup(2.%d->2.%d)\n", 51, 6);
 447                        smbios_ver = 0x0206;
 448                        break;
 449                }
 450        } else {
 451                smbios_ver = 0;
 452        }
 453
 454        buf += 16;
 455
 456        if (memcmp(buf, "_DMI_", 5) == 0 && dmi_checksum(buf, 15)) {
 457                dmi_num = (buf[13] << 8) | buf[12];
 458                dmi_len = (buf[7] << 8) | buf[6];
 459                dmi_base = (buf[11] << 24) | (buf[10] << 16) |
 460                        (buf[9] << 8) | buf[8];
 461
 462                if (dmi_walk_early(dmi_decode) == 0) {
 463                        if (smbios_ver) {
 464                                dmi_ver = smbios_ver;
 465                                pr_info("SMBIOS %d.%d present.\n",
 466                                       dmi_ver >> 8, dmi_ver & 0xFF);
 467                        } else {
 468                                dmi_ver = (buf[14] & 0xF0) << 4 |
 469                                           (buf[14] & 0x0F);
 470                                pr_info("Legacy DMI %d.%d present.\n",
 471                                       dmi_ver >> 8, dmi_ver & 0xFF);
 472                        }
 473                        dmi_format_ids(dmi_ids_string, sizeof(dmi_ids_string));
 474                        printk(KERN_DEBUG "DMI: %s\n", dmi_ids_string);
 475                        return 0;
 476                }
 477        }
 478
 479        return 1;
 480}
 481
 482void __init dmi_scan_machine(void)
 483{
 484        char __iomem *p, *q;
 485        char buf[32];
 486
 487        if (efi_enabled(EFI_CONFIG_TABLES)) {
 488                if (efi.smbios == EFI_INVALID_TABLE_ADDR)
 489                        goto error;
 490
 491                /* This is called as a core_initcall() because it isn't
 492                 * needed during early boot.  This also means we can
 493                 * iounmap the space when we're done with it.
 494                 */
 495                p = dmi_ioremap(efi.smbios, 32);
 496                if (p == NULL)
 497                        goto error;
 498                memcpy_fromio(buf, p, 32);
 499                dmi_iounmap(p, 32);
 500
 501                if (!dmi_present(buf)) {
 502                        dmi_available = 1;
 503                        goto out;
 504                }
 505        }
 506        else {
 507                /*
 508                 * no iounmap() for that ioremap(); it would be a no-op, but
 509                 * it's so early in setup that sucker gets confused into doing
 510                 * what it shouldn't if we actually call it.
 511                 */
 512                p = dmi_ioremap(0xF0000, 0x10000);
 513                if (p == NULL)
 514                        goto error;
 515
 516                /*
 517                 * Iterate over all possible DMI header addresses q.
 518                 * Maintain the 32 bytes around q in buf.  On the
 519                 * first iteration, substitute zero for the
 520                 * out-of-range bytes so there is no chance of falsely
 521                 * detecting an SMBIOS header.
 522                 */
 523                memset(buf, 0, 16);
 524                for (q = p; q < p + 0x10000; q += 16) {
 525                        memcpy_fromio(buf + 16, q, 16);
 526                        if (!dmi_present(buf)) {
 527                                dmi_available = 1;
 528                                dmi_iounmap(p, 0x10000);
 529                                goto out;
 530                        }
 531                        memcpy(buf, buf + 16, 16);
 532                }
 533                dmi_iounmap(p, 0x10000);
 534        }
 535 error:
 536        printk(KERN_INFO "DMI not present or invalid.\n");
 537 out:
 538        dmi_initialized = 1;
 539}
 540
 541/**
 542 * dmi_set_dump_stack_arch_desc - set arch description for dump_stack()
 543 *
 544 * Invoke dump_stack_set_arch_desc() with DMI system information so that
 545 * DMI identifiers are printed out on task dumps.  Arch boot code should
 546 * call this function after dmi_scan_machine() if it wants to print out DMI
 547 * identifiers on task dumps.
 548 */
 549void __init dmi_set_dump_stack_arch_desc(void)
 550{
 551        dump_stack_set_arch_desc("%s", dmi_ids_string);
 552}
 553
 554/**
 555 *      dmi_matches - check if dmi_system_id structure matches system DMI data
 556 *      @dmi: pointer to the dmi_system_id structure to check
 557 */
 558static bool dmi_matches(const struct dmi_system_id *dmi)
 559{
 560        int i;
 561
 562        WARN(!dmi_initialized, KERN_ERR "dmi check: not initialized yet.\n");
 563
 564        for (i = 0; i < ARRAY_SIZE(dmi->matches); i++) {
 565                int s = dmi->matches[i].slot;
 566                if (s == DMI_NONE)
 567                        break;
 568                if (dmi_ident[s]) {
 569                        if (!dmi->matches[i].exact_match &&
 570                            strstr(dmi_ident[s], dmi->matches[i].substr))
 571                                continue;
 572                        else if (dmi->matches[i].exact_match &&
 573                                 !strcmp(dmi_ident[s], dmi->matches[i].substr))
 574                                continue;
 575                }
 576
 577                /* No match */
 578                return false;
 579        }
 580        return true;
 581}
 582
 583/**
 584 *      dmi_is_end_of_table - check for end-of-table marker
 585 *      @dmi: pointer to the dmi_system_id structure to check
 586 */
 587static bool dmi_is_end_of_table(const struct dmi_system_id *dmi)
 588{
 589        return dmi->matches[0].slot == DMI_NONE;
 590}
 591
 592/**
 593 *      dmi_check_system - check system DMI data
 594 *      @list: array of dmi_system_id structures to match against
 595 *              All non-null elements of the list must match
 596 *              their slot's (field index's) data (i.e., each
 597 *              list string must be a substring of the specified
 598 *              DMI slot's string data) to be considered a
 599 *              successful match.
 600 *
 601 *      Walk the blacklist table running matching functions until someone
 602 *      returns non zero or we hit the end. Callback function is called for
 603 *      each successful match. Returns the number of matches.
 604 */
 605int dmi_check_system(const struct dmi_system_id *list)
 606{
 607        int count = 0;
 608        const struct dmi_system_id *d;
 609
 610        for (d = list; !dmi_is_end_of_table(d); d++)
 611                if (dmi_matches(d)) {
 612                        count++;
 613                        if (d->callback && d->callback(d))
 614                                break;
 615                }
 616
 617        return count;
 618}
 619EXPORT_SYMBOL(dmi_check_system);
 620
 621/**
 622 *      dmi_first_match - find dmi_system_id structure matching system DMI data
 623 *      @list: array of dmi_system_id structures to match against
 624 *              All non-null elements of the list must match
 625 *              their slot's (field index's) data (i.e., each
 626 *              list string must be a substring of the specified
 627 *              DMI slot's string data) to be considered a
 628 *              successful match.
 629 *
 630 *      Walk the blacklist table until the first match is found.  Return the
 631 *      pointer to the matching entry or NULL if there's no match.
 632 */
 633const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list)
 634{
 635        const struct dmi_system_id *d;
 636
 637        for (d = list; !dmi_is_end_of_table(d); d++)
 638                if (dmi_matches(d))
 639                        return d;
 640
 641        return NULL;
 642}
 643EXPORT_SYMBOL(dmi_first_match);
 644
 645/**
 646 *      dmi_get_system_info - return DMI data value
 647 *      @field: data index (see enum dmi_field)
 648 *
 649 *      Returns one DMI data value, can be used to perform
 650 *      complex DMI data checks.
 651 */
 652const char *dmi_get_system_info(int field)
 653{
 654        return dmi_ident[field];
 655}
 656EXPORT_SYMBOL(dmi_get_system_info);
 657
 658/**
 659 * dmi_name_in_serial - Check if string is in the DMI product serial information
 660 * @str: string to check for
 661 */
 662int dmi_name_in_serial(const char *str)
 663{
 664        int f = DMI_PRODUCT_SERIAL;
 665        if (dmi_ident[f] && strstr(dmi_ident[f], str))
 666                return 1;
 667        return 0;
 668}
 669
 670/**
 671 *      dmi_name_in_vendors - Check if string is in the DMI system or board vendor name
 672 *      @str:   Case sensitive Name
 673 */
 674int dmi_name_in_vendors(const char *str)
 675{
 676        static int fields[] = { DMI_SYS_VENDOR, DMI_BOARD_VENDOR, DMI_NONE };
 677        int i;
 678        for (i = 0; fields[i] != DMI_NONE; i++) {
 679                int f = fields[i];
 680                if (dmi_ident[f] && strstr(dmi_ident[f], str))
 681                        return 1;
 682        }
 683        return 0;
 684}
 685EXPORT_SYMBOL(dmi_name_in_vendors);
 686
 687/**
 688 *      dmi_find_device - find onboard device by type/name
 689 *      @type: device type or %DMI_DEV_TYPE_ANY to match all device types
 690 *      @name: device name string or %NULL to match all
 691 *      @from: previous device found in search, or %NULL for new search.
 692 *
 693 *      Iterates through the list of known onboard devices. If a device is
 694 *      found with a matching @vendor and @device, a pointer to its device
 695 *      structure is returned.  Otherwise, %NULL is returned.
 696 *      A new search is initiated by passing %NULL as the @from argument.
 697 *      If @from is not %NULL, searches continue from next device.
 698 */
 699const struct dmi_device * dmi_find_device(int type, const char *name,
 700                                    const struct dmi_device *from)
 701{
 702        const struct list_head *head = from ? &from->list : &dmi_devices;
 703        struct list_head *d;
 704
 705        for(d = head->next; d != &dmi_devices; d = d->next) {
 706                const struct dmi_device *dev =
 707                        list_entry(d, struct dmi_device, list);
 708
 709                if (((type == DMI_DEV_TYPE_ANY) || (dev->type == type)) &&
 710                    ((name == NULL) || (strcmp(dev->name, name) == 0)))
 711                        return dev;
 712        }
 713
 714        return NULL;
 715}
 716EXPORT_SYMBOL(dmi_find_device);
 717
 718/**
 719 *      dmi_get_date - parse a DMI date
 720 *      @field: data index (see enum dmi_field)
 721 *      @yearp: optional out parameter for the year
 722 *      @monthp: optional out parameter for the month
 723 *      @dayp: optional out parameter for the day
 724 *
 725 *      The date field is assumed to be in the form resembling
 726 *      [mm[/dd]]/yy[yy] and the result is stored in the out
 727 *      parameters any or all of which can be omitted.
 728 *
 729 *      If the field doesn't exist, all out parameters are set to zero
 730 *      and false is returned.  Otherwise, true is returned with any
 731 *      invalid part of date set to zero.
 732 *
 733 *      On return, year, month and day are guaranteed to be in the
 734 *      range of [0,9999], [0,12] and [0,31] respectively.
 735 */
 736bool dmi_get_date(int field, int *yearp, int *monthp, int *dayp)
 737{
 738        int year = 0, month = 0, day = 0;
 739        bool exists;
 740        const char *s, *y;
 741        char *e;
 742
 743        s = dmi_get_system_info(field);
 744        exists = s;
 745        if (!exists)
 746                goto out;
 747
 748        /*
 749         * Determine year first.  We assume the date string resembles
 750         * mm/dd/yy[yy] but the original code extracted only the year
 751         * from the end.  Keep the behavior in the spirit of no
 752         * surprises.
 753         */
 754        y = strrchr(s, '/');
 755        if (!y)
 756                goto out;
 757
 758        y++;
 759        year = simple_strtoul(y, &e, 10);
 760        if (y != e && year < 100) {     /* 2-digit year */
 761                year += 1900;
 762                if (year < 1996)        /* no dates < spec 1.0 */
 763                        year += 100;
 764        }
 765        if (year > 9999)                /* year should fit in %04d */
 766                year = 0;
 767
 768        /* parse the mm and dd */
 769        month = simple_strtoul(s, &e, 10);
 770        if (s == e || *e != '/' || !month || month > 12) {
 771                month = 0;
 772                goto out;
 773        }
 774
 775        s = e + 1;
 776        day = simple_strtoul(s, &e, 10);
 777        if (s == y || s == e || *e != '/' || day > 31)
 778                day = 0;
 779out:
 780        if (yearp)
 781                *yearp = year;
 782        if (monthp)
 783                *monthp = month;
 784        if (dayp)
 785                *dayp = day;
 786        return exists;
 787}
 788EXPORT_SYMBOL(dmi_get_date);
 789
 790/**
 791 *      dmi_walk - Walk the DMI table and get called back for every record
 792 *      @decode: Callback function
 793 *      @private_data: Private data to be passed to the callback function
 794 *
 795 *      Returns -1 when the DMI table can't be reached, 0 on success.
 796 */
 797int dmi_walk(void (*decode)(const struct dmi_header *, void *),
 798             void *private_data)
 799{
 800        u8 *buf;
 801
 802        if (!dmi_available)
 803                return -1;
 804
 805        buf = ioremap(dmi_base, dmi_len);
 806        if (buf == NULL)
 807                return -1;
 808
 809        dmi_table(buf, dmi_len, dmi_num, decode, private_data);
 810
 811        iounmap(buf);
 812        return 0;
 813}
 814EXPORT_SYMBOL_GPL(dmi_walk);
 815
 816/**
 817 * dmi_match - compare a string to the dmi field (if exists)
 818 * @f: DMI field identifier
 819 * @str: string to compare the DMI field to
 820 *
 821 * Returns true if the requested field equals to the str (including NULL).
 822 */
 823bool dmi_match(enum dmi_field f, const char *str)
 824{
 825        const char *info = dmi_get_system_info(f);
 826
 827        if (info == NULL || str == NULL)
 828                return info == str;
 829
 830        return !strcmp(info, str);
 831}
 832EXPORT_SYMBOL_GPL(dmi_match);
 833
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