PM / sleep: Asynchronous threads for suspend_noirq

[linux/fpc-iii.git] / drivers / firmware / dmi_scan.c

#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)) {
                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) {
                                dmi_ver = smbios_ver;
                                pr_info("SMBIOS %d.%d present.\n",
                                       dmi_ver >> 8, dmi_ver & 0xFF);
                        } else {
                                dmi_ver = (buf[14] & 0xF0) << 4 |
                                           (buf[14] & 0x0F);
                                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);