linux/drivers/firmware/dmi-sysfs.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * dmi-sysfs.c
   4 *
   5 * This module exports the DMI tables read-only to userspace through the
   6 * sysfs file system.
   7 *
   8 * Data is currently found below
   9 *    /sys/firmware/dmi/...
  10 *
  11 * DMI attributes are presented in attribute files with names
  12 * formatted using %d-%d, so that the first integer indicates the
  13 * structure type (0-255), and the second field is the instance of that
  14 * entry.
  15 *
  16 * Copyright 2011 Google, Inc.
  17 */
  18
  19#include <linux/kernel.h>
  20#include <linux/init.h>
  21#include <linux/module.h>
  22#include <linux/types.h>
  23#include <linux/kobject.h>
  24#include <linux/dmi.h>
  25#include <linux/capability.h>
  26#include <linux/slab.h>
  27#include <linux/list.h>
  28#include <linux/io.h>
  29#include <asm/dmi.h>
  30
  31#define MAX_ENTRY_TYPE 255 /* Most of these aren't used, but we consider
  32                              the top entry type is only 8 bits */
  33
  34struct dmi_sysfs_entry {
  35        struct dmi_header dh;
  36        struct kobject kobj;
  37        int instance;
  38        int position;
  39        struct list_head list;
  40        struct kobject *child;
  41};
  42
  43/*
  44 * Global list of dmi_sysfs_entry.  Even though this should only be
  45 * manipulated at setup and teardown, the lazy nature of the kobject
  46 * system means we get lazy removes.
  47 */
  48static LIST_HEAD(entry_list);
  49static DEFINE_SPINLOCK(entry_list_lock);
  50
  51/* dmi_sysfs_attribute - Top level attribute. used by all entries. */
  52struct dmi_sysfs_attribute {
  53        struct attribute attr;
  54        ssize_t (*show)(struct dmi_sysfs_entry *entry, char *buf);
  55};
  56
  57#define DMI_SYSFS_ATTR(_entry, _name) \
  58struct dmi_sysfs_attribute dmi_sysfs_attr_##_entry##_##_name = { \
  59        .attr = {.name = __stringify(_name), .mode = 0400}, \
  60        .show = dmi_sysfs_##_entry##_##_name, \
  61}
  62
  63/*
  64 * dmi_sysfs_mapped_attribute - Attribute where we require the entry be
  65 * mapped in.  Use in conjunction with dmi_sysfs_specialize_attr_ops.
  66 */
  67struct dmi_sysfs_mapped_attribute {
  68        struct attribute attr;
  69        ssize_t (*show)(struct dmi_sysfs_entry *entry,
  70                        const struct dmi_header *dh,
  71                        char *buf);
  72};
  73
  74#define DMI_SYSFS_MAPPED_ATTR(_entry, _name) \
  75struct dmi_sysfs_mapped_attribute dmi_sysfs_attr_##_entry##_##_name = { \
  76        .attr = {.name = __stringify(_name), .mode = 0400}, \
  77        .show = dmi_sysfs_##_entry##_##_name, \
  78}
  79
  80/*************************************************
  81 * Generic DMI entry support.
  82 *************************************************/
  83static void dmi_entry_free(struct kobject *kobj)
  84{
  85        kfree(kobj);
  86}
  87
  88static struct dmi_sysfs_entry *to_entry(struct kobject *kobj)
  89{
  90        return container_of(kobj, struct dmi_sysfs_entry, kobj);
  91}
  92
  93static struct dmi_sysfs_attribute *to_attr(struct attribute *attr)
  94{
  95        return container_of(attr, struct dmi_sysfs_attribute, attr);
  96}
  97
  98static ssize_t dmi_sysfs_attr_show(struct kobject *kobj,
  99                                   struct attribute *_attr, char *buf)
 100{
 101        struct dmi_sysfs_entry *entry = to_entry(kobj);
 102        struct dmi_sysfs_attribute *attr = to_attr(_attr);
 103
 104        /* DMI stuff is only ever admin visible */
 105        if (!capable(CAP_SYS_ADMIN))
 106                return -EACCES;
 107
 108        return attr->show(entry, buf);
 109}
 110
 111static const struct sysfs_ops dmi_sysfs_attr_ops = {
 112        .show = dmi_sysfs_attr_show,
 113};
 114
 115typedef ssize_t (*dmi_callback)(struct dmi_sysfs_entry *,
 116                                const struct dmi_header *dh, void *);
 117
 118struct find_dmi_data {
 119        struct dmi_sysfs_entry  *entry;
 120        dmi_callback            callback;
 121        void                    *private;
 122        int                     instance_countdown;
 123        ssize_t                 ret;
 124};
 125
 126static void find_dmi_entry_helper(const struct dmi_header *dh,
 127                                  void *_data)
 128{
 129        struct find_dmi_data *data = _data;
 130        struct dmi_sysfs_entry *entry = data->entry;
 131
 132        /* Is this the entry we want? */
 133        if (dh->type != entry->dh.type)
 134                return;
 135
 136        if (data->instance_countdown != 0) {
 137                /* try the next instance? */
 138                data->instance_countdown--;
 139                return;
 140        }
 141
 142        /*
 143         * Don't ever revisit the instance.  Short circuit later
 144         * instances by letting the instance_countdown run negative
 145         */
 146        data->instance_countdown--;
 147
 148        /* Found the entry */
 149        data->ret = data->callback(entry, dh, data->private);
 150}
 151
 152/* State for passing the read parameters through dmi_find_entry() */
 153struct dmi_read_state {
 154        char *buf;
 155        loff_t pos;
 156        size_t count;
 157};
 158
 159static ssize_t find_dmi_entry(struct dmi_sysfs_entry *entry,
 160                              dmi_callback callback, void *private)
 161{
 162        struct find_dmi_data data = {
 163                .entry = entry,
 164                .callback = callback,
 165                .private = private,
 166                .instance_countdown = entry->instance,
 167                .ret = -EIO,  /* To signal the entry disappeared */
 168        };
 169        int ret;
 170
 171        ret = dmi_walk(find_dmi_entry_helper, &data);
 172        /* This shouldn't happen, but just in case. */
 173        if (ret)
 174                return -EINVAL;
 175        return data.ret;
 176}
 177
 178/*
 179 * Calculate and return the byte length of the dmi entry identified by
 180 * dh.  This includes both the formatted portion as well as the
 181 * unformatted string space, including the two trailing nul characters.
 182 */
 183static size_t dmi_entry_length(const struct dmi_header *dh)
 184{
 185        const char *p = (const char *)dh;
 186
 187        p += dh->length;
 188
 189        while (p[0] || p[1])
 190                p++;
 191
 192        return 2 + p - (const char *)dh;
 193}
 194
 195/*************************************************
 196 * Support bits for specialized DMI entry support
 197 *************************************************/
 198struct dmi_entry_attr_show_data {
 199        struct attribute *attr;
 200        char *buf;
 201};
 202
 203static ssize_t dmi_entry_attr_show_helper(struct dmi_sysfs_entry *entry,
 204                                          const struct dmi_header *dh,
 205                                          void *_data)
 206{
 207        struct dmi_entry_attr_show_data *data = _data;
 208        struct dmi_sysfs_mapped_attribute *attr;
 209
 210        attr = container_of(data->attr,
 211                            struct dmi_sysfs_mapped_attribute, attr);
 212        return attr->show(entry, dh, data->buf);
 213}
 214
 215static ssize_t dmi_entry_attr_show(struct kobject *kobj,
 216                                   struct attribute *attr,
 217                                   char *buf)
 218{
 219        struct dmi_entry_attr_show_data data = {
 220                .attr = attr,
 221                .buf  = buf,
 222        };
 223        /* Find the entry according to our parent and call the
 224         * normalized show method hanging off of the attribute */
 225        return find_dmi_entry(to_entry(kobj->parent),
 226                              dmi_entry_attr_show_helper, &data);
 227}
 228
 229static const struct sysfs_ops dmi_sysfs_specialize_attr_ops = {
 230        .show = dmi_entry_attr_show,
 231};
 232
 233/*************************************************
 234 * Specialized DMI entry support.
 235 *************************************************/
 236
 237/*** Type 15 - System Event Table ***/
 238
 239#define DMI_SEL_ACCESS_METHOD_IO8       0x00
 240#define DMI_SEL_ACCESS_METHOD_IO2x8     0x01
 241#define DMI_SEL_ACCESS_METHOD_IO16      0x02
 242#define DMI_SEL_ACCESS_METHOD_PHYS32    0x03
 243#define DMI_SEL_ACCESS_METHOD_GPNV      0x04
 244
 245struct dmi_system_event_log {
 246        struct dmi_header header;
 247        u16     area_length;
 248        u16     header_start_offset;
 249        u16     data_start_offset;
 250        u8      access_method;
 251        u8      status;
 252        u32     change_token;
 253        union {
 254                struct {
 255                        u16 index_addr;
 256                        u16 data_addr;
 257                } io;
 258                u32     phys_addr32;
 259                u16     gpnv_handle;
 260                u32     access_method_address;
 261        };
 262        u8      header_format;
 263        u8      type_descriptors_supported_count;
 264        u8      per_log_type_descriptor_length;
 265        u8      supported_log_type_descriptos[0];
 266} __packed;
 267
 268#define DMI_SYSFS_SEL_FIELD(_field) \
 269static ssize_t dmi_sysfs_sel_##_field(struct dmi_sysfs_entry *entry, \
 270                                      const struct dmi_header *dh, \
 271                                      char *buf) \
 272{ \
 273        struct dmi_system_event_log sel; \
 274        if (sizeof(sel) > dmi_entry_length(dh)) \
 275                return -EIO; \
 276        memcpy(&sel, dh, sizeof(sel)); \
 277        return sprintf(buf, "%u\n", sel._field); \
 278} \
 279static DMI_SYSFS_MAPPED_ATTR(sel, _field)
 280
 281DMI_SYSFS_SEL_FIELD(area_length);
 282DMI_SYSFS_SEL_FIELD(header_start_offset);
 283DMI_SYSFS_SEL_FIELD(data_start_offset);
 284DMI_SYSFS_SEL_FIELD(access_method);
 285DMI_SYSFS_SEL_FIELD(status);
 286DMI_SYSFS_SEL_FIELD(change_token);
 287DMI_SYSFS_SEL_FIELD(access_method_address);
 288DMI_SYSFS_SEL_FIELD(header_format);
 289DMI_SYSFS_SEL_FIELD(type_descriptors_supported_count);
 290DMI_SYSFS_SEL_FIELD(per_log_type_descriptor_length);
 291
 292static struct attribute *dmi_sysfs_sel_attrs[] = {
 293        &dmi_sysfs_attr_sel_area_length.attr,
 294        &dmi_sysfs_attr_sel_header_start_offset.attr,
 295        &dmi_sysfs_attr_sel_data_start_offset.attr,
 296        &dmi_sysfs_attr_sel_access_method.attr,
 297        &dmi_sysfs_attr_sel_status.attr,
 298        &dmi_sysfs_attr_sel_change_token.attr,
 299        &dmi_sysfs_attr_sel_access_method_address.attr,
 300        &dmi_sysfs_attr_sel_header_format.attr,
 301        &dmi_sysfs_attr_sel_type_descriptors_supported_count.attr,
 302        &dmi_sysfs_attr_sel_per_log_type_descriptor_length.attr,
 303        NULL,
 304};
 305
 306
 307static struct kobj_type dmi_system_event_log_ktype = {
 308        .release = dmi_entry_free,
 309        .sysfs_ops = &dmi_sysfs_specialize_attr_ops,
 310        .default_attrs = dmi_sysfs_sel_attrs,
 311};
 312
 313typedef u8 (*sel_io_reader)(const struct dmi_system_event_log *sel,
 314                            loff_t offset);
 315
 316static DEFINE_MUTEX(io_port_lock);
 317
 318static u8 read_sel_8bit_indexed_io(const struct dmi_system_event_log *sel,
 319                                   loff_t offset)
 320{
 321        u8 ret;
 322
 323        mutex_lock(&io_port_lock);
 324        outb((u8)offset, sel->io.index_addr);
 325        ret = inb(sel->io.data_addr);
 326        mutex_unlock(&io_port_lock);
 327        return ret;
 328}
 329
 330static u8 read_sel_2x8bit_indexed_io(const struct dmi_system_event_log *sel,
 331                                     loff_t offset)
 332{
 333        u8 ret;
 334
 335        mutex_lock(&io_port_lock);
 336        outb((u8)offset, sel->io.index_addr);
 337        outb((u8)(offset >> 8), sel->io.index_addr + 1);
 338        ret = inb(sel->io.data_addr);
 339        mutex_unlock(&io_port_lock);
 340        return ret;
 341}
 342
 343static u8 read_sel_16bit_indexed_io(const struct dmi_system_event_log *sel,
 344                                    loff_t offset)
 345{
 346        u8 ret;
 347
 348        mutex_lock(&io_port_lock);
 349        outw((u16)offset, sel->io.index_addr);
 350        ret = inb(sel->io.data_addr);
 351        mutex_unlock(&io_port_lock);
 352        return ret;
 353}
 354
 355static sel_io_reader sel_io_readers[] = {
 356        [DMI_SEL_ACCESS_METHOD_IO8]     = read_sel_8bit_indexed_io,
 357        [DMI_SEL_ACCESS_METHOD_IO2x8]   = read_sel_2x8bit_indexed_io,
 358        [DMI_SEL_ACCESS_METHOD_IO16]    = read_sel_16bit_indexed_io,
 359};
 360
 361static ssize_t dmi_sel_raw_read_io(struct dmi_sysfs_entry *entry,
 362                                   const struct dmi_system_event_log *sel,
 363                                   char *buf, loff_t pos, size_t count)
 364{
 365        ssize_t wrote = 0;
 366
 367        sel_io_reader io_reader = sel_io_readers[sel->access_method];
 368
 369        while (count && pos < sel->area_length) {
 370                count--;
 371                *(buf++) = io_reader(sel, pos++);
 372                wrote++;
 373        }
 374
 375        return wrote;
 376}
 377
 378static ssize_t dmi_sel_raw_read_phys32(struct dmi_sysfs_entry *entry,
 379                                       const struct dmi_system_event_log *sel,
 380                                       char *buf, loff_t pos, size_t count)
 381{
 382        u8 __iomem *mapped;
 383        ssize_t wrote = 0;
 384
 385        mapped = dmi_remap(sel->access_method_address, sel->area_length);
 386        if (!mapped)
 387                return -EIO;
 388
 389        while (count && pos < sel->area_length) {
 390                count--;
 391                *(buf++) = readb(mapped + pos++);
 392                wrote++;
 393        }
 394
 395        dmi_unmap(mapped);
 396        return wrote;
 397}
 398
 399static ssize_t dmi_sel_raw_read_helper(struct dmi_sysfs_entry *entry,
 400                                       const struct dmi_header *dh,
 401                                       void *_state)
 402{
 403        struct dmi_read_state *state = _state;
 404        struct dmi_system_event_log sel;
 405
 406        if (sizeof(sel) > dmi_entry_length(dh))
 407                return -EIO;
 408
 409        memcpy(&sel, dh, sizeof(sel));
 410
 411        switch (sel.access_method) {
 412        case DMI_SEL_ACCESS_METHOD_IO8:
 413        case DMI_SEL_ACCESS_METHOD_IO2x8:
 414        case DMI_SEL_ACCESS_METHOD_IO16:
 415                return dmi_sel_raw_read_io(entry, &sel, state->buf,
 416                                           state->pos, state->count);
 417        case DMI_SEL_ACCESS_METHOD_PHYS32:
 418                return dmi_sel_raw_read_phys32(entry, &sel, state->buf,
 419                                               state->pos, state->count);
 420        case DMI_SEL_ACCESS_METHOD_GPNV:
 421                pr_info("dmi-sysfs: GPNV support missing.\n");
 422                return -EIO;
 423        default:
 424                pr_info("dmi-sysfs: Unknown access method %02x\n",
 425                        sel.access_method);
 426                return -EIO;
 427        }
 428}
 429
 430static ssize_t dmi_sel_raw_read(struct file *filp, struct kobject *kobj,
 431                                struct bin_attribute *bin_attr,
 432                                char *buf, loff_t pos, size_t count)
 433{
 434        struct dmi_sysfs_entry *entry = to_entry(kobj->parent);
 435        struct dmi_read_state state = {
 436                .buf = buf,
 437                .pos = pos,
 438                .count = count,
 439        };
 440
 441        return find_dmi_entry(entry, dmi_sel_raw_read_helper, &state);
 442}
 443
 444static struct bin_attribute dmi_sel_raw_attr = {
 445        .attr = {.name = "raw_event_log", .mode = 0400},
 446        .read = dmi_sel_raw_read,
 447};
 448
 449static int dmi_system_event_log(struct dmi_sysfs_entry *entry)
 450{
 451        int ret;
 452
 453        entry->child = kzalloc(sizeof(*entry->child), GFP_KERNEL);
 454        if (!entry->child)
 455                return -ENOMEM;
 456        ret = kobject_init_and_add(entry->child,
 457                                   &dmi_system_event_log_ktype,
 458                                   &entry->kobj,
 459                                   "system_event_log");
 460        if (ret)
 461                goto out_free;
 462
 463        ret = sysfs_create_bin_file(entry->child, &dmi_sel_raw_attr);
 464        if (ret)
 465                goto out_del;
 466
 467        return 0;
 468
 469out_del:
 470        kobject_del(entry->child);
 471out_free:
 472        kfree(entry->child);
 473        return ret;
 474}
 475
 476/*************************************************
 477 * Generic DMI entry support.
 478 *************************************************/
 479
 480static ssize_t dmi_sysfs_entry_length(struct dmi_sysfs_entry *entry, char *buf)
 481{
 482        return sprintf(buf, "%d\n", entry->dh.length);
 483}
 484
 485static ssize_t dmi_sysfs_entry_handle(struct dmi_sysfs_entry *entry, char *buf)
 486{
 487        return sprintf(buf, "%d\n", entry->dh.handle);
 488}
 489
 490static ssize_t dmi_sysfs_entry_type(struct dmi_sysfs_entry *entry, char *buf)
 491{
 492        return sprintf(buf, "%d\n", entry->dh.type);
 493}
 494
 495static ssize_t dmi_sysfs_entry_instance(struct dmi_sysfs_entry *entry,
 496                                        char *buf)
 497{
 498        return sprintf(buf, "%d\n", entry->instance);
 499}
 500
 501static ssize_t dmi_sysfs_entry_position(struct dmi_sysfs_entry *entry,
 502                                        char *buf)
 503{
 504        return sprintf(buf, "%d\n", entry->position);
 505}
 506
 507static DMI_SYSFS_ATTR(entry, length);
 508static DMI_SYSFS_ATTR(entry, handle);
 509static DMI_SYSFS_ATTR(entry, type);
 510static DMI_SYSFS_ATTR(entry, instance);
 511static DMI_SYSFS_ATTR(entry, position);
 512
 513static struct attribute *dmi_sysfs_entry_attrs[] = {
 514        &dmi_sysfs_attr_entry_length.attr,
 515        &dmi_sysfs_attr_entry_handle.attr,
 516        &dmi_sysfs_attr_entry_type.attr,
 517        &dmi_sysfs_attr_entry_instance.attr,
 518        &dmi_sysfs_attr_entry_position.attr,
 519        NULL,
 520};
 521
 522static ssize_t dmi_entry_raw_read_helper(struct dmi_sysfs_entry *entry,
 523                                         const struct dmi_header *dh,
 524                                         void *_state)
 525{
 526        struct dmi_read_state *state = _state;
 527        size_t entry_length;
 528
 529        entry_length = dmi_entry_length(dh);
 530
 531        return memory_read_from_buffer(state->buf, state->count,
 532                                       &state->pos, dh, entry_length);
 533}
 534
 535static ssize_t dmi_entry_raw_read(struct file *filp,
 536                                  struct kobject *kobj,
 537                                  struct bin_attribute *bin_attr,
 538                                  char *buf, loff_t pos, size_t count)
 539{
 540        struct dmi_sysfs_entry *entry = to_entry(kobj);
 541        struct dmi_read_state state = {
 542                .buf = buf,
 543                .pos = pos,
 544                .count = count,
 545        };
 546
 547        return find_dmi_entry(entry, dmi_entry_raw_read_helper, &state);
 548}
 549
 550static const struct bin_attribute dmi_entry_raw_attr = {
 551        .attr = {.name = "raw", .mode = 0400},
 552        .read = dmi_entry_raw_read,
 553};
 554
 555static void dmi_sysfs_entry_release(struct kobject *kobj)
 556{
 557        struct dmi_sysfs_entry *entry = to_entry(kobj);
 558
 559        spin_lock(&entry_list_lock);
 560        list_del(&entry->list);
 561        spin_unlock(&entry_list_lock);
 562        kfree(entry);
 563}
 564
 565static struct kobj_type dmi_sysfs_entry_ktype = {
 566        .release = dmi_sysfs_entry_release,
 567        .sysfs_ops = &dmi_sysfs_attr_ops,
 568        .default_attrs = dmi_sysfs_entry_attrs,
 569};
 570
 571static struct kset *dmi_kset;
 572
 573/* Global count of all instances seen.  Only for setup */
 574static int __initdata instance_counts[MAX_ENTRY_TYPE + 1];
 575
 576/* Global positional count of all entries seen.  Only for setup */
 577static int __initdata position_count;
 578
 579static void __init dmi_sysfs_register_handle(const struct dmi_header *dh,
 580                                             void *_ret)
 581{
 582        struct dmi_sysfs_entry *entry;
 583        int *ret = _ret;
 584
 585        /* If a previous entry saw an error, short circuit */
 586        if (*ret)
 587                return;
 588
 589        /* Allocate and register a new entry into the entries set */
 590        entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 591        if (!entry) {
 592                *ret = -ENOMEM;
 593                return;
 594        }
 595
 596        /* Set the key */
 597        memcpy(&entry->dh, dh, sizeof(*dh));
 598        entry->instance = instance_counts[dh->type]++;
 599        entry->position = position_count++;
 600
 601        entry->kobj.kset = dmi_kset;
 602        *ret = kobject_init_and_add(&entry->kobj, &dmi_sysfs_entry_ktype, NULL,
 603                                    "%d-%d", dh->type, entry->instance);
 604
 605        if (*ret) {
 606                kfree(entry);
 607                return;
 608        }
 609
 610        /* Thread on the global list for cleanup */
 611        spin_lock(&entry_list_lock);
 612        list_add_tail(&entry->list, &entry_list);
 613        spin_unlock(&entry_list_lock);
 614
 615        /* Handle specializations by type */
 616        switch (dh->type) {
 617        case DMI_ENTRY_SYSTEM_EVENT_LOG:
 618                *ret = dmi_system_event_log(entry);
 619                break;
 620        default:
 621                /* No specialization */
 622                break;
 623        }
 624        if (*ret)
 625                goto out_err;
 626
 627        /* Create the raw binary file to access the entry */
 628        *ret = sysfs_create_bin_file(&entry->kobj, &dmi_entry_raw_attr);
 629        if (*ret)
 630                goto out_err;
 631
 632        return;
 633out_err:
 634        kobject_put(entry->child);
 635        kobject_put(&entry->kobj);
 636        return;
 637}
 638
 639static void cleanup_entry_list(void)
 640{
 641        struct dmi_sysfs_entry *entry, *next;
 642
 643        /* No locks, we are on our way out */
 644        list_for_each_entry_safe(entry, next, &entry_list, list) {
 645                kobject_put(entry->child);
 646                kobject_put(&entry->kobj);
 647        }
 648}
 649
 650static int __init dmi_sysfs_init(void)
 651{
 652        int error;
 653        int val;
 654
 655        if (!dmi_kobj) {
 656                pr_debug("dmi-sysfs: dmi entry is absent.\n");
 657                error = -ENODATA;
 658                goto err;
 659        }
 660
 661        dmi_kset = kset_create_and_add("entries", NULL, dmi_kobj);
 662        if (!dmi_kset) {
 663                error = -ENOMEM;
 664                goto err;
 665        }
 666
 667        val = 0;
 668        error = dmi_walk(dmi_sysfs_register_handle, &val);
 669        if (error)
 670                goto err;
 671        if (val) {
 672                error = val;
 673                goto err;
 674        }
 675
 676        pr_debug("dmi-sysfs: loaded.\n");
 677
 678        return 0;
 679err:
 680        cleanup_entry_list();
 681        kset_unregister(dmi_kset);
 682        return error;
 683}
 684
 685/* clean up everything. */
 686static void __exit dmi_sysfs_exit(void)
 687{
 688        pr_debug("dmi-sysfs: unloading.\n");
 689        cleanup_entry_list();
 690        kset_unregister(dmi_kset);
 691}
 692
 693module_init(dmi_sysfs_init);
 694module_exit(dmi_sysfs_exit);
 695
 696MODULE_AUTHOR("Mike Waychison <mikew@google.com>");
 697MODULE_DESCRIPTION("DMI sysfs support");
 698MODULE_LICENSE("GPL");
 699