text: #include <linux/types.h>
  #include <linux/string.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/ctype.h>
  #include <linux/dmi.h>
  #include <linux/efi.h>
  #include <linux/bootmem.h>
  #include <linux/random.h>
  #include <asm/dmi.h>
  #include <asm/unaligned.h>
  
  /*
   * DMI stands for "Desktop Management Interface".  It is part
   * of and an antecedent to, SMBIOS, which stands for System
   * Management BIOS.  See further: http://www.dmtf.org/standards
   */
  static const char dmi_empty_string[] = "        ";
  
  static u16 __initdata dmi_ver;
  /*
   * Catch too early calls to dmi_check_system():
   */
  static int dmi_initialized;
  
  /* DMI system identification string used during boot */
  static char dmi_ids_string[128] __initdata;
  
  static struct dmi_memdev_info {
  	const char *device;
  	const char *bank;
  	u16 handle;
  } *dmi_memdev;
  static int dmi_memdev_nr;
  
  static const char * __init dmi_string_nosave(const struct dmi_header *dm, u8 s)
  {
  	const u8 *bp = ((u8 *) dm) + dm->length;
  
  	if (s) {
  		s--;
  		while (s > 0 && *bp) {
  			bp += strlen(bp) + 1;
  			s--;
  		}
  
  		if (*bp != 0) {
  			size_t len = strlen(bp)+1;
  			size_t cmp_len = len > 8 ? 8 : len;
  
  			if (!memcmp(bp, dmi_empty_string, cmp_len))
  				return dmi_empty_string;
  			return bp;
  		}
  	}
  
  	return "";
  }
  
  static const char * __init dmi_string(const struct dmi_header *dm, u8 s)
  {
  	const char *bp = dmi_string_nosave(dm, s);
  	char *str;
  	size_t len;
  
  	if (bp == dmi_empty_string)
  		return dmi_empty_string;
  
  	len = strlen(bp) + 1;
  	str = dmi_alloc(len);
  	if (str != NULL)
  		strcpy(str, bp);
  
  	return str;
  }
  
  /*
   *	We have to be cautious here. We have seen BIOSes with DMI pointers
   *	pointing to completely the wrong place for example
   */
  static void dmi_table(u8 *buf, int len, int num,
  		      void (*decode)(const struct dmi_header *, void *),
  		      void *private_data)
  {
  	u8 *data = buf;
  	int i = 0;
  
  	/*
  	 *	Stop when we see all the items the table claimed to have
  	 *	OR we run off the end of the table (also happens)
  	 */
  	while ((i < num) && (data - buf + sizeof(struct dmi_header)) <= len) {
  		const struct dmi_header *dm = (const struct dmi_header *)data;
  
  		/*
  		 *  We want to know the total length (formatted area and
  		 *  strings) before decoding to make sure we won't run off the
  		 *  table in dmi_decode or dmi_string
  		 */
  		data += dm->length;
  		while ((data - buf < len - 1) && (data[0] || data[1]))
  			data++;
  		if (data - buf < len - 1)
  			decode(dm, private_data);
  		data += 2;
  		i++;
  	}
  }
  
  static u32 dmi_base;
  static u16 dmi_len;
  static u16 dmi_num;
  
  static int __init dmi_walk_early(void (*decode)(const struct dmi_header *,
  		void *))
  {
  	u8 *buf;
  
  	buf = dmi_early_remap(dmi_base, dmi_len);
  	if (buf == NULL)
  		return -1;
  
  	dmi_table(buf, dmi_len, dmi_num, decode, NULL);
  
  	add_device_randomness(buf, dmi_len);
  
  	dmi_early_unmap(buf, dmi_len);
  	return 0;
  }
  
  static int __init dmi_checksum(const u8 *buf, u8 len)
  {
  	u8 sum = 0;
  	int a;
  
  	for (a = 0; a < len; a++)
  		sum += buf[a];
  
  	return sum == 0;
  }
  
  static const char *dmi_ident[DMI_STRING_MAX];
  static LIST_HEAD(dmi_devices);
  int dmi_available;
  
  /*
   *	Save a DMI string
   */
  static void __init dmi_save_ident(const struct dmi_header *dm, int slot,
  		int string)
  {
  	const char *d = (const char *) dm;
  	const char *p;
  
  	if (dmi_ident[slot])
  		return;
  
  	p = dmi_string(dm, d[string]);
  	if (p == NULL)
  		return;
  
  	dmi_ident[slot] = p;
  }
  
  static void __init dmi_save_uuid(const struct dmi_header *dm, int slot,
  		int index)
  {
  	const u8 *d = (u8 *) dm + index;
  	char *s;
  	int is_ff = 1, is_00 = 1, i;
  
  	if (dmi_ident[slot])
  		return;
  
  	for (i = 0; i < 16 && (is_ff || is_00); i++) {
  		if (d[i] != 0x00)
  			is_00 = 0;
  		if (d[i] != 0xFF)
  			is_ff = 0;
  	}
  
  	if (is_ff || is_00)
  		return;
  
  	s = dmi_alloc(16*2+4+1);
  	if (!s)
  		return;
  
  	/*
  	 * As of version 2.6 of the SMBIOS specification, the first 3 fields of
  	 * the UUID are supposed to be little-endian encoded.  The specification
  	 * says that this is the defacto standard.
  	 */
  	if (dmi_ver >= 0x0206)
  		sprintf(s, "%pUL", d);
  	else
  		sprintf(s, "%pUB", d);
  
  	dmi_ident[slot] = s;
  }
  
  static void __init dmi_save_type(const struct dmi_header *dm, int slot,
  		int index)
  {
  	const u8 *d = (u8 *) dm + index;
  	char *s;
  
  	if (dmi_ident[slot])
  		return;
  
  	s = dmi_alloc(4);
  	if (!s)
  		return;
  
  	sprintf(s, "%u", *d & 0x7F);
  	dmi_ident[slot] = s;
  }
  
  static void __init dmi_save_one_device(int type, const char *name)
  {
  	struct dmi_device *dev;
  
  	/* No duplicate device */
  	if (dmi_find_device(type, name, NULL))
  		return;
  
  	dev = dmi_alloc(sizeof(*dev) + strlen(name) + 1);
  	if (!dev)
  		return;
  
  	dev->type = type;
  	strcpy((char *)(dev + 1), name);
  	dev->name = (char *)(dev + 1);
  	dev->device_data = NULL;
  	list_add(&dev->list, &dmi_devices);
  }
  
  static void __init dmi_save_devices(const struct dmi_header *dm)
  {
  	int i, count = (dm->length - sizeof(struct dmi_header)) / 2;
  
  	for (i = 0; i < count; i++) {
  		const char *d = (char *)(dm + 1) + (i * 2);
  
  		/* Skip disabled device */
  		if ((*d & 0x80) == 0)
  			continue;
  
  		dmi_save_one_device(*d & 0x7f, dmi_string_nosave(dm, *(d + 1)));
  	}
  }
  
  static void __init dmi_save_oem_strings_devices(const struct dmi_header *dm)
  {
  	int i, count = *(u8 *)(dm + 1);
  	struct dmi_device *dev;
  
  	for (i = 1; i <= count; i++) {
  		const char *devname = dmi_string(dm, i);
  
  		if (devname == dmi_empty_string)
  			continue;
  
  		dev = dmi_alloc(sizeof(*dev));
  		if (!dev)
  			break;
  
  		dev->type = DMI_DEV_TYPE_OEM_STRING;
  		dev->name = devname;
  		dev->device_data = NULL;
  
  		list_add(&dev->list, &dmi_devices);
  	}
  }
  
  static void __init dmi_save_ipmi_device(const struct dmi_header *dm)
  {
  	struct dmi_device *dev;
  	void *data;
  
  	data = dmi_alloc(dm->length);
  	if (data == NULL)
  		return;
  
  	memcpy(data, dm, dm->length);
  
  	dev = dmi_alloc(sizeof(*dev));
  	if (!dev)
  		return;
  
  	dev->type = DMI_DEV_TYPE_IPMI;
  	dev->name = "IPMI controller";
  	dev->device_data = data;
  
  	list_add_tail(&dev->list, &dmi_devices);
  }
  
  static void __init dmi_save_dev_onboard(int instance, int segment, int bus,
  					int devfn, const char *name)
  {
  	struct dmi_dev_onboard *onboard_dev;
  
  	onboard_dev = dmi_alloc(sizeof(*onboard_dev) + strlen(name) + 1);
  	if (!onboard_dev)
  		return;
  
  	onboard_dev->instance = instance;
  	onboard_dev->segment = segment;
  	onboard_dev->bus = bus;
  	onboard_dev->devfn = devfn;
  
  	strcpy((char *)&onboard_dev[1], name);
  	onboard_dev->dev.type = DMI_DEV_TYPE_DEV_ONBOARD;
  	onboard_dev->dev.name = (char *)&onboard_dev[1];
  	onboard_dev->dev.device_data = onboard_dev;
  
  	list_add(&onboard_dev->dev.list, &dmi_devices);
  }
  
  static void __init dmi_save_extended_devices(const struct dmi_header *dm)
  {
  	const u8 *d = (u8 *) dm + 5;
  
  	/* Skip disabled device */
  	if ((*d & 0x80) == 0)
  		return;
  
  	dmi_save_dev_onboard(*(d+1), *(u16 *)(d+2), *(d+4), *(d+5),
  			     dmi_string_nosave(dm, *(d-1)));
  	dmi_save_one_device(*d & 0x7f, dmi_string_nosave(dm, *(d - 1)));
  }
  
  static void __init count_mem_devices(const struct dmi_header *dm, void *v)
  {
  	if (dm->type != DMI_ENTRY_MEM_DEVICE)
  		return;
  	dmi_memdev_nr++;
  }
  
  static void __init save_mem_devices(const struct dmi_header *dm, void *v)
  {
  	const char *d = (const char *)dm;
  	static int nr;
  
  	if (dm->type != DMI_ENTRY_MEM_DEVICE)
  		return;
  	if (nr >= dmi_memdev_nr) {
  		pr_warn(FW_BUG "Too many DIMM entries in SMBIOS table\n");
  		return;
  	}
  	dmi_memdev[nr].handle = get_unaligned(&dm->handle);
  	dmi_memdev[nr].device = dmi_string(dm, d[0x10]);
  	dmi_memdev[nr].bank = dmi_string(dm, d[0x11]);
  	nr++;
  }
  
  void __init dmi_memdev_walk(void)
  {
  	if (!dmi_available)
  		return;
  
  	if (dmi_walk_early(count_mem_devices) == 0 && dmi_memdev_nr) {
  		dmi_memdev = dmi_alloc(sizeof(*dmi_memdev) * dmi_memdev_nr);
  		if (dmi_memdev)
  			dmi_walk_early(save_mem_devices);
  	}
  }
  
  /*
   *	Process a DMI table entry. Right now all we care about are the BIOS
   *	and machine entries. For 2.5 we should pull the smbus controller info
   *	out of here.
   */
  static void __init dmi_decode(const struct dmi_header *dm, void *dummy)
  {
  	switch (dm->type) {
  	case 0:		/* BIOS Information */
  		dmi_save_ident(dm, DMI_BIOS_VENDOR, 4);
  		dmi_save_ident(dm, DMI_BIOS_VERSION, 5);
  		dmi_save_ident(dm, DMI_BIOS_DATE, 8);
  		break;
  	case 1:		/* System Information */
  		dmi_save_ident(dm, DMI_SYS_VENDOR, 4);
  		dmi_save_ident(dm, DMI_PRODUCT_NAME, 5);
  		dmi_save_ident(dm, DMI_PRODUCT_VERSION, 6);
  		dmi_save_ident(dm, DMI_PRODUCT_SERIAL, 7);
  		dmi_save_uuid(dm, DMI_PRODUCT_UUID, 8);
  		break;
  	case 2:		/* Base Board Information */
  		dmi_save_ident(dm, DMI_BOARD_VENDOR, 4);
  		dmi_save_ident(dm, DMI_BOARD_NAME, 5);
  		dmi_save_ident(dm, DMI_BOARD_VERSION, 6);
  		dmi_save_ident(dm, DMI_BOARD_SERIAL, 7);
  		dmi_save_ident(dm, DMI_BOARD_ASSET_TAG, 8);
  		break;
  	case 3:		/* Chassis Information */
  		dmi_save_ident(dm, DMI_CHASSIS_VENDOR, 4);
  		dmi_save_type(dm, DMI_CHASSIS_TYPE, 5);
  		dmi_save_ident(dm, DMI_CHASSIS_VERSION, 6);
  		dmi_save_ident(dm, DMI_CHASSIS_SERIAL, 7);
  		dmi_save_ident(dm, DMI_CHASSIS_ASSET_TAG, 8);
  		break;
  	case 10:	/* Onboard Devices Information */
  		dmi_save_devices(dm);
  		break;
  	case 11:	/* OEM Strings */
  		dmi_save_oem_strings_devices(dm);
  		break;
  	case 38:	/* IPMI Device Information */
  		dmi_save_ipmi_device(dm);
  		break;
  	case 41:	/* Onboard Devices Extended Information */
  		dmi_save_extended_devices(dm);
  	}
  }
  
  static int __init print_filtered(char *buf, size_t len, const char *info)
  {
  	int c = 0;
  	const char *p;
  
  	if (!info)
  		return c;
  
  	for (p = info; *p; p++)
  		if (isprint(*p))
  			c += scnprintf(buf + c, len - c, "%c", *p);
  		else
  			c += scnprintf(buf + c, len - c, "\\x%02x", *p & 0xff);
  	return c;
  }
  
  static void __init dmi_format_ids(char *buf, size_t len)
  {
  	int c = 0;
  	const char *board;	/* Board Name is optional */
  
  	c += print_filtered(buf + c, len - c,
  			    dmi_get_system_info(DMI_SYS_VENDOR));
  	c += scnprintf(buf + c, len - c, " ");
  	c += print_filtered(buf + c, len - c,
  			    dmi_get_system_info(DMI_PRODUCT_NAME));
  
  	board = dmi_get_system_info(DMI_BOARD_NAME);
  	if (board) {
  		c += scnprintf(buf + c, len - c, "/");
  		c += print_filtered(buf + c, len - c, board);
  	}
  	c += scnprintf(buf + c, len - c, ", BIOS ");
  	c += print_filtered(buf + c, len - c,
  			    dmi_get_system_info(DMI_BIOS_VERSION));
  	c += scnprintf(buf + c, len - c, " ");
  	c += print_filtered(buf + c, len - c,
  			    dmi_get_system_info(DMI_BIOS_DATE));
  }
  
  /*
   * Check for DMI/SMBIOS headers in the system firmware image.  Any
   * SMBIOS header must start 16 bytes before the DMI header, so take a
   * 32 byte buffer and check for DMI at offset 16 and SMBIOS at offset
   * 0.  If the DMI header is present, set dmi_ver accordingly (SMBIOS
   * takes precedence) and return 0.  Otherwise return 1.
   */
  static int __init dmi_present(const u8 *buf)
  {
  	int smbios_ver;
  
  	if (memcmp(buf, "_SM_", 4) == 0 &&
  	    buf[5] < 32 && dmi_checksum(buf, buf[5])) {
  		smbios_ver = (buf[6] << 8) + buf[7];
  
  		/* Some BIOS report weird SMBIOS version, fix that up */
  		switch (smbios_ver) {
  		case 0x021F:
  		case 0x0221:
  			pr_debug("SMBIOS version fixup(2.%d->2.%d)\n",
  				 smbios_ver & 0xFF, 3);
  			smbios_ver = 0x0203;
  			break;
  		case 0x0233:
  			pr_debug("SMBIOS version fixup(2.%d->2.%d)\n", 51, 6);
  			smbios_ver = 0x0206;
  			break;
  		}
  	} else {
  		smbios_ver = 0;
  	}
  
  	buf += 16;
  
  	if (memcmp(buf, "_DMI_", 5) == 0 && dmi_checksum(buf, 15)) {
  		if (smbios_ver)
  			dmi_ver = smbios_ver;
  		else
  			dmi_ver = (buf[14] & 0xF0) << 4 | (buf[14] & 0x0F);
  		dmi_num = (buf[13] << 8) | buf[12];
  		dmi_len = (buf[7] << 8) | buf[6];
  		dmi_base = (buf[11] << 24) | (buf[10] << 16) |
  			(buf[9] << 8) | buf[8];
  
  		if (dmi_walk_early(dmi_decode) == 0) {
  			if (smbios_ver) {
  				pr_info("SMBIOS %d.%d present.\n",
  				       dmi_ver >> 8, dmi_ver & 0xFF);
  			} else {
  				pr_info("Legacy DMI %d.%d present.\n",
  				       dmi_ver >> 8, dmi_ver & 0xFF);
  			}
  			dmi_format_ids(dmi_ids_string, sizeof(dmi_ids_string));
  			printk(KERN_DEBUG "DMI: %s\n", dmi_ids_string);
  			return 0;
  		}
  	}
  
  	return 1;
  }
  
  void __init dmi_scan_machine(void)
  {
  	char __iomem *p, *q;
  	char buf[32];
  
  	if (efi_enabled(EFI_CONFIG_TABLES)) {
  		if (efi.smbios == EFI_INVALID_TABLE_ADDR)
  			goto error;
  
  		/* This is called as a core_initcall() because it isn't
  		 * needed during early boot.  This also means we can
  		 * iounmap the space when we're done with it.
  		 */
  		p = dmi_early_remap(efi.smbios, 32);
  		if (p == NULL)
  			goto error;
  		memcpy_fromio(buf, p, 32);
  		dmi_early_unmap(p, 32);
  
  		if (!dmi_present(buf)) {
  			dmi_available = 1;
  			goto out;
  		}
  	} else if (IS_ENABLED(CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK)) {
  		p = dmi_early_remap(0xF0000, 0x10000);
  		if (p == NULL)
  			goto error;
  
  		/*
  		 * Iterate over all possible DMI header addresses q.
  		 * Maintain the 32 bytes around q in buf.  On the
  		 * first iteration, substitute zero for the
  		 * out-of-range bytes so there is no chance of falsely
  		 * detecting an SMBIOS header.
  		 */
  		memset(buf, 0, 16);
  		for (q = p; q < p + 0x10000; q += 16) {
  			memcpy_fromio(buf + 16, q, 16);
  			if (!dmi_present(buf)) {
  				dmi_available = 1;
  				dmi_early_unmap(p, 0x10000);
  				goto out;
  			}
  			memcpy(buf, buf + 16, 16);
  		}
  		dmi_early_unmap(p, 0x10000);
  	}
   error:
  	pr_info("DMI not present or invalid.\n");
   out:
  	dmi_initialized = 1;
  }
  
  /**
   * dmi_set_dump_stack_arch_desc - set arch description for dump_stack()
   *
   * Invoke dump_stack_set_arch_desc() with DMI system information so that
   * DMI identifiers are printed out on task dumps.  Arch boot code should
   * call this function after dmi_scan_machine() if it wants to print out DMI
   * identifiers on task dumps.
   */
  void __init dmi_set_dump_stack_arch_desc(void)
  {
  	dump_stack_set_arch_desc("%s", dmi_ids_string);
  }
  
  /**
   *	dmi_matches - check if dmi_system_id structure matches system DMI data
   *	@dmi: pointer to the dmi_system_id structure to check
   */
  static bool dmi_matches(const struct dmi_system_id *dmi)
  {
  	int i;
  
  	WARN(!dmi_initialized, KERN_ERR "dmi check: not initialized yet.\n");
  
  	for (i = 0; i < ARRAY_SIZE(dmi->matches); i++) {
  		int s = dmi->matches[i].slot;
  		if (s == DMI_NONE)
  			break;
  		if (dmi_ident[s]) {
  			if (!dmi->matches[i].exact_match &&
  			    strstr(dmi_ident[s], dmi->matches[i].substr))
  				continue;
  			else if (dmi->matches[i].exact_match &&
  				 !strcmp(dmi_ident[s], dmi->matches[i].substr))
  				continue;
  		}
  
  		/* No match */
  		return false;
  	}
  	return true;
  }
  
  /**
   *	dmi_is_end_of_table - check for end-of-table marker
   *	@dmi: pointer to the dmi_system_id structure to check
   */
  static bool dmi_is_end_of_table(const struct dmi_system_id *dmi)
  {
  	return dmi->matches[0].slot == DMI_NONE;
  }
  
  /**
   *	dmi_check_system - check system DMI data
   *	@list: array of dmi_system_id structures to match against
   *		All non-null elements of the list must match
   *		their slot's (field index's) data (i.e., each
   *		list string must be a substring of the specified
   *		DMI slot's string data) to be considered a
   *		successful match.
   *
   *	Walk the blacklist table running matching functions until someone
   *	returns non zero or we hit the end. Callback function is called for
   *	each successful match. Returns the number of matches.
   */
  int dmi_check_system(const struct dmi_system_id *list)
  {
  	int count = 0;
  	const struct dmi_system_id *d;
  
  	for (d = list; !dmi_is_end_of_table(d); d++)
  		if (dmi_matches(d)) {
  			count++;
  			if (d->callback && d->callback(d))
  				break;
  		}
  
  	return count;
  }
  EXPORT_SYMBOL(dmi_check_system);
  
  /**
   *	dmi_first_match - find dmi_system_id structure matching system DMI data
   *	@list: array of dmi_system_id structures to match against
   *		All non-null elements of the list must match
   *		their slot's (field index's) data (i.e., each
   *		list string must be a substring of the specified
   *		DMI slot's string data) to be considered a
   *		successful match.
   *
   *	Walk the blacklist table until the first match is found.  Return the
   *	pointer to the matching entry or NULL if there's no match.
   */
  const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list)
  {
  	const struct dmi_system_id *d;
  
  	for (d = list; !dmi_is_end_of_table(d); d++)
  		if (dmi_matches(d))
  			return d;
  
  	return NULL;
  }
  EXPORT_SYMBOL(dmi_first_match);
  
  /**
   *	dmi_get_system_info - return DMI data value
   *	@field: data index (see enum dmi_field)
   *
   *	Returns one DMI data value, can be used to perform
   *	complex DMI data checks.
   */
  const char *dmi_get_system_info(int field)
  {
  	return dmi_ident[field];
  }
  EXPORT_SYMBOL(dmi_get_system_info);
  
  /**
   * dmi_name_in_serial - Check if string is in the DMI product serial information
   * @str: string to check for
   */
  int dmi_name_in_serial(const char *str)
  {
  	int f = DMI_PRODUCT_SERIAL;
  	if (dmi_ident[f] && strstr(dmi_ident[f], str))
  		return 1;
  	return 0;
  }
  
  /**
   *	dmi_name_in_vendors - Check if string is in the DMI system or board vendor name
   *	@str: Case sensitive Name
   */
  int dmi_name_in_vendors(const char *str)
  {
  	static int fields[] = { DMI_SYS_VENDOR, DMI_BOARD_VENDOR, DMI_NONE };
  	int i;
  	for (i = 0; fields[i] != DMI_NONE; i++) {
  		int f = fields[i];
  		if (dmi_ident[f] && strstr(dmi_ident[f], str))
  			return 1;
  	}
  	return 0;
  }
  EXPORT_SYMBOL(dmi_name_in_vendors);
  
  /**
   *	dmi_find_device - find onboard device by type/name
   *	@type: device type or %DMI_DEV_TYPE_ANY to match all device types
   *	@name: device name string or %NULL to match all
   *	@from: previous device found in search, or %NULL for new search.
   *
   *	Iterates through the list of known onboard devices. If a device is
   *	found with a matching @vendor and @device, a pointer to its device
   *	structure is returned.  Otherwise, %NULL is returned.
   *	A new search is initiated by passing %NULL as the @from argument.
   *	If @from is not %NULL, searches continue from next device.
   */
  const struct dmi_device *dmi_find_device(int type, const char *name,
  				    const struct dmi_device *from)
  {
  	const struct list_head *head = from ? &from->list : &dmi_devices;
  	struct list_head *d;
  
  	for (d = head->next; d != &dmi_devices; d = d->next) {
  		const struct dmi_device *dev =
  			list_entry(d, struct dmi_device, list);
  
  		if (((type == DMI_DEV_TYPE_ANY) || (dev->type == type)) &&
  		    ((name == NULL) || (strcmp(dev->name, name) == 0)))
  			return dev;
  	}
  
  	return NULL;
  }
  EXPORT_SYMBOL(dmi_find_device);
  
  /**
   *	dmi_get_date - parse a DMI date
   *	@field:	data index (see enum dmi_field)
   *	@yearp: optional out parameter for the year
   *	@monthp: optional out parameter for the month
   *	@dayp: optional out parameter for the day
   *
   *	The date field is assumed to be in the form resembling
   *	[mm[/dd]]/yy[yy] and the result is stored in the out
   *	parameters any or all of which can be omitted.
   *
   *	If the field doesn't exist, all out parameters are set to zero
   *	and false is returned.  Otherwise, true is returned with any
   *	invalid part of date set to zero.
   *
   *	On return, year, month and day are guaranteed to be in the
   *	range of [0,9999], [0,12] and [0,31] respectively.
   */
  bool dmi_get_date(int field, int *yearp, int *monthp, int *dayp)
  {
  	int year = 0, month = 0, day = 0;
  	bool exists;
  	const char *s, *y;
  	char *e;
  
  	s = dmi_get_system_info(field);
  	exists = s;
  	if (!exists)
  		goto out;
  
  	/*
  	 * Determine year first.  We assume the date string resembles
  	 * mm/dd/yy[yy] but the original code extracted only the year
  	 * from the end.  Keep the behavior in the spirit of no
  	 * surprises.
  	 */
  	y = strrchr(s, '/');
  	if (!y)
  		goto out;
  
  	y++;
  	year = simple_strtoul(y, &e, 10);
  	if (y != e && year < 100) {	/* 2-digit year */
  		year += 1900;
  		if (year < 1996)	/* no dates < spec 1.0 */
  			year += 100;
  	}
  	if (year > 9999)		/* year should fit in %04d */
  		year = 0;
  
  	/* parse the mm and dd */
  	month = simple_strtoul(s, &e, 10);
  	if (s == e || *e != '/' || !month || month > 12) {
  		month = 0;
  		goto out;
  	}
  
  	s = e + 1;
  	day = simple_strtoul(s, &e, 10);
  	if (s == y || s == e || *e != '/' || day > 31)
  		day = 0;
  out:
  	if (yearp)
  		*yearp = year;
  	if (monthp)
  		*monthp = month;
  	if (dayp)
  		*dayp = day;
  	return exists;
  }
  EXPORT_SYMBOL(dmi_get_date);
  
  /**
   *	dmi_walk - Walk the DMI table and get called back for every record
   *	@decode: Callback function
   *	@private_data: Private data to be passed to the callback function
   *
   *	Returns -1 when the DMI table can't be reached, 0 on success.
   */
  int dmi_walk(void (*decode)(const struct dmi_header *, void *),
  	     void *private_data)
  {
  	u8 *buf;
  
  	if (!dmi_available)
  		return -1;
  
  	buf = dmi_remap(dmi_base, dmi_len);
  	if (buf == NULL)
  		return -1;
  
  	dmi_table(buf, dmi_len, dmi_num, decode, private_data);
  
  	dmi_unmap(buf);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(dmi_walk);
  
  /**
   * dmi_match - compare a string to the dmi field (if exists)
   * @f: DMI field identifier
   * @str: string to compare the DMI field to
   *
   * Returns true if the requested field equals to the str (including NULL).
   */
  bool dmi_match(enum dmi_field f, const char *str)
  {
  	const char *info = dmi_get_system_info(f);
  
  	if (info == NULL || str == NULL)
  		return info == str;
  
  	return !strcmp(info, str);
  }
  EXPORT_SYMBOL_GPL(dmi_match);
  
  void dmi_memdev_name(u16 handle, const char **bank, const char **device)
  {
  	int n;
  
  	if (dmi_memdev == NULL)
  		return;
  
  	for (n = 0; n < dmi_memdev_nr; n++) {
  		if (handle == dmi_memdev[n].handle) {
  			*bank = dmi_memdev[n].bank;
  			*device = dmi_memdev[n].device;
  			break;
  		}
  	}
  }
  EXPORT_SYMBOL_GPL(dmi_memdev_name);
  