drivers/firmware/efivars.c

   1 /*
   2  * EFI Variables - efivars.c
   3  *
   4  * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
   5  * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
   6  *
   7  * This code takes all variables accessible from EFI runtime and
   8  *  exports them via sysfs
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; either version 2 of the License, or
  13  *  (at your option) any later version.
  14  *
  15  *  This program is distributed in the hope that it will be useful,
  16  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  *  GNU General Public License for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License
  21  *  along with this program; if not, write to the Free Software
  22  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23  *
  24  * Changelog:
  25  *
  26  *  17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
  27  *   remove check for efi_enabled in exit
  28  *   add MODULE_VERSION
  29  *
  30  *  26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
  31  *   minor bug fixes
  32  *
  33  *  21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
  34  *   converted driver to export variable information via sysfs
  35  *   and moved to drivers/firmware directory
  36  *   bumped revision number to v0.07 to reflect conversion & move
  37  *
  38  *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
  39  *   fix locking per Peter Chubb's findings
  40  *
  41  *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
  42  *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
  43  *
  44  *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
  45  *   use list_for_each_safe when deleting vars.
  46  *   remove ifdef CONFIG_SMP around include <linux/smp.h>
  47  *   v0.04 release to linux-ia64@linuxia64.org
  48  *
  49  *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
  50  *   Moved vars from /proc/efi to /proc/efi/vars, and made
  51  *   efi.c own the /proc/efi directory.
  52  *   v0.03 release to linux-ia64@linuxia64.org
  53  *
  54  *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
  55  *   At the request of Stephane, moved ownership of /proc/efi
  56  *   to efi.c, and now efivars lives under /proc/efi/vars.
  57  *
  58  *  12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
  59  *   Feedback received from Stephane Eranian incorporated.
  60  *   efivar_write() checks copy_from_user() return value.
  61  *   efivar_read/write() returns proper errno.
  62  *   v0.02 release to linux-ia64@linuxia64.org
  63  *
  64  *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
  65  *   v0.01 release to linux-ia64@linuxia64.org
  66  */
  67
  68 #include <linux/capability.h>
  69 #include <linux/types.h>
  70 #include <linux/errno.h>
  71 #include <linux/init.h>
  72 #include <linux/mm.h>
  73 #include <linux/module.h>
  74 #include <linux/string.h>
  75 #include <linux/smp.h>
  76 #include <linux/efi.h>
  77 #include <linux/sysfs.h>
  78 #include <linux/kobject.h>
  79 #include <linux/device.h>
  80 #include <linux/slab.h>
  81
  82 #include <asm/uaccess.h>
  83
  84 #define EFIVARS_VERSION "0.08"
  85 #define EFIVARS_DATE "2004-May-17"
  86
  87 MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
  88 MODULE_DESCRIPTION("sysfs interface to EFI Variables");
  89 MODULE_LICENSE("GPL");
  90 MODULE_VERSION(EFIVARS_VERSION);
  91
  92 /*
  93  * The maximum size of VariableName + Data = 1024
  94  * Therefore, it's reasonable to save that much
  95  * space in each part of the structure,
  96  * and we use a page for reading/writing.
  97  */
  98
  99 struct efi_variable {
 100         efi_char16_t  VariableName[1024/sizeof(efi_char16_t)];
 101         efi_guid_t    VendorGuid;
 102         unsigned long DataSize;
 103         __u8          Data[1024];
 104         efi_status_t  Status;
 105         __u32         Attributes;
 106 } __attribute__((packed));
 107
 108
 109 struct efivar_entry {
 110         struct efivars *efivars;
 111         struct efi_variable var;
 112         struct list_head list;
 113         struct kobject kobj;
 114 };
 115
 116 struct efivar_attribute {
 117         struct attribute attr;
 118         ssize_t (*show) (struct efivar_entry *entry, char *buf);
 119         ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
 120 };
 121
 122
 123 #define EFIVAR_ATTR(_name, _mode, _show, _store) \
 124 struct efivar_attribute efivar_attr_##_name = { \
 125         .attr = {.name = __stringify(_name), .mode = _mode}, \
 126         .show = _show, \
 127         .store = _store, \
 128 };
 129
 130 #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
 131 #define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)
 132
 133 /*
 134  * Prototype for sysfs creation function
 135  */
 136 static int
 137 efivar_create_sysfs_entry(struct efivars *efivars,
 138                           unsigned long variable_name_size,
 139                           efi_char16_t *variable_name,
 140                           efi_guid_t *vendor_guid);
 141
 142 /* Return the number of unicode characters in data */
 143 static unsigned long
 144 utf8_strlen(efi_char16_t *data, unsigned long maxlength)
 145 {
 146         unsigned long length = 0;
 147
 148         while (*data++ != 0 && length < maxlength)
 149                 length++;
 150         return length;
 151 }
 152
 153 /*
 154  * Return the number of bytes is the length of this string
 155  * Note: this is NOT the same as the number of unicode characters
 156  */
 157 static inline unsigned long
 158 utf8_strsize(efi_char16_t *data, unsigned long maxlength)
 159 {
 160         return utf8_strlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
 161 }
 162
 163 static efi_status_t
 164 get_var_data(struct efivars *efivars, struct efi_variable *var)
 165 {
 166         efi_status_t status;
 167
 168         spin_lock(&efivars->lock);
 169         var->DataSize = 1024;
 170         status = efivars->ops->get_variable(var->VariableName,
 171                                             &var->VendorGuid,
 172                                             &var->Attributes,
 173                                             &var->DataSize,
 174                                             var->Data);
 175         spin_unlock(&efivars->lock);
 176         if (status != EFI_SUCCESS) {
 177                 printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
 178                         status);
 179         }
 180         return status;
 181 }
 182
 183 static ssize_t
 184 efivar_guid_read(struct efivar_entry *entry, char *buf)
 185 {
 186         struct efi_variable *var = &entry->var;
 187         char *str = buf;
 188
 189         if (!entry || !buf)
 190                 return 0;
 191
 192         efi_guid_unparse(&var->VendorGuid, str);
 193         str += strlen(str);
 194         str += sprintf(str, "\n");
 195
 196         return str - buf;
 197 }
 198
 199 static ssize_t
 200 efivar_attr_read(struct efivar_entry *entry, char *buf)
 201 {
 202         struct efi_variable *var = &entry->var;
 203         char *str = buf;
 204         efi_status_t status;
 205
 206         if (!entry || !buf)
 207                 return -EINVAL;
 208
 209         status = get_var_data(entry->efivars, var);
 210         if (status != EFI_SUCCESS)
 211                 return -EIO;
 212
 213         if (var->Attributes & 0x1)
 214                 str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
 215         if (var->Attributes & 0x2)
 216                 str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
 217         if (var->Attributes & 0x4)
 218                 str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
 219         return str - buf;
 220 }
 221
 222 static ssize_t
 223 efivar_size_read(struct efivar_entry *entry, char *buf)
 224 {
 225         struct efi_variable *var = &entry->var;
 226         char *str = buf;
 227         efi_status_t status;
 228
 229         if (!entry || !buf)
 230                 return -EINVAL;
 231
 232         status = get_var_data(entry->efivars, var);
 233         if (status != EFI_SUCCESS)
 234                 return -EIO;
 235
 236         str += sprintf(str, "0x%lx\n", var->DataSize);
 237         return str - buf;
 238 }
 239
 240 static ssize_t
 241 efivar_data_read(struct efivar_entry *entry, char *buf)
 242 {
 243         struct efi_variable *var = &entry->var;
 244         efi_status_t status;
 245
 246         if (!entry || !buf)
 247                 return -EINVAL;
 248
 249         status = get_var_data(entry->efivars, var);
 250         if (status != EFI_SUCCESS)
 251                 return -EIO;
 252
 253         memcpy(buf, var->Data, var->DataSize);
 254         return var->DataSize;
 255 }
 256 /*
 257  * We allow each variable to be edited via rewriting the
 258  * entire efi variable structure.
 259  */
 260 static ssize_t
 261 efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
 262 {
 263         struct efi_variable *new_var, *var = &entry->var;
 264         struct efivars *efivars = entry->efivars;
 265         efi_status_t status = EFI_NOT_FOUND;
 266
 267         if (count != sizeof(struct efi_variable))
 268                 return -EINVAL;
 269
 270         new_var = (struct efi_variable *)buf;
 271         /*
 272          * If only updating the variable data, then the name
 273          * and guid should remain the same
 274          */
 275         if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
 276                 efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
 277                 printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
 278                 return -EINVAL;
 279         }
 280
 281         if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
 282                 printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
 283                 return -EINVAL;
 284         }
 285
 286         spin_lock(&efivars->lock);
 287         status = efivars->ops->set_variable(new_var->VariableName,
 288                                             &new_var->VendorGuid,
 289                                             new_var->Attributes,
 290                                             new_var->DataSize,
 291                                             new_var->Data);
 292
 293         spin_unlock(&efivars->lock);
 294
 295         if (status != EFI_SUCCESS) {
 296                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
 297                         status);
 298                 return -EIO;
 299         }
 300
 301         memcpy(&entry->var, new_var, count);
 302         return count;
 303 }
 304
 305 static ssize_t
 306 efivar_show_raw(struct efivar_entry *entry, char *buf)
 307 {
 308         struct efi_variable *var = &entry->var;
 309         efi_status_t status;
 310
 311         if (!entry || !buf)
 312                 return 0;
 313
 314         status = get_var_data(entry->efivars, var);
 315         if (status != EFI_SUCCESS)
 316                 return -EIO;
 317
 318         memcpy(buf, var, sizeof(*var));
 319         return sizeof(*var);
 320 }
 321
 322 /*
 323  * Generic read/write functions that call the specific functions of
 324  * the attributes...
 325  */
 326 static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
 327                                 char *buf)
 328 {
 329         struct efivar_entry *var = to_efivar_entry(kobj);
 330         struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
 331         ssize_t ret = -EIO;
 332
 333         if (!capable(CAP_SYS_ADMIN))
 334                 return -EACCES;
 335
 336         if (efivar_attr->show) {
 337                 ret = efivar_attr->show(var, buf);
 338         }
 339         return ret;
 340 }
 341
 342 static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
 343                                 const char *buf, size_t count)
 344 {
 345         struct efivar_entry *var = to_efivar_entry(kobj);
 346         struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
 347         ssize_t ret = -EIO;
 348
 349         if (!capable(CAP_SYS_ADMIN))
 350                 return -EACCES;
 351
 352         if (efivar_attr->store)
 353                 ret = efivar_attr->store(var, buf, count);
 354
 355         return ret;
 356 }
 357
 358 static const struct sysfs_ops efivar_attr_ops = {
 359         .show = efivar_attr_show,
 360         .store = efivar_attr_store,
 361 };
 362
 363 static void efivar_release(struct kobject *kobj)
 364 {
 365         struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
 366         kfree(var);
 367 }
 368
 369 static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
 370 static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
 371 static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
 372 static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
 373 static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
 374
 375 static struct attribute *def_attrs[] = {
 376         &efivar_attr_guid.attr,
 377         &efivar_attr_size.attr,
 378         &efivar_attr_attributes.attr,
 379         &efivar_attr_data.attr,
 380         &efivar_attr_raw_var.attr,
 381         NULL,
 382 };
 383
 384 static struct kobj_type efivar_ktype = {
 385         .release = efivar_release,
 386         .sysfs_ops = &efivar_attr_ops,
 387         .default_attrs = def_attrs,
 388 };
 389
 390 static inline void
 391 efivar_unregister(struct efivar_entry *var)
 392 {
 393         kobject_put(&var->kobj);
 394 }
 395
 396
 397 static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
 398                              struct bin_attribute *bin_attr,
 399                              char *buf, loff_t pos, size_t count)
 400 {
 401         struct efi_variable *new_var = (struct efi_variable *)buf;
 402         struct efivars *efivars = bin_attr->private;
 403         struct efivar_entry *search_efivar, *n;
 404         unsigned long strsize1, strsize2;
 405         efi_status_t status = EFI_NOT_FOUND;
 406         int found = 0;
 407
 408         if (!capable(CAP_SYS_ADMIN))
 409                 return -EACCES;
 410
 411         spin_lock(&efivars->lock);
 412
 413         /*
 414          * Does this variable already exist?
 415          */
 416         list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
 417                 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
 418                 strsize2 = utf8_strsize(new_var->VariableName, 1024);
 419                 if (strsize1 == strsize2 &&
 420                         !memcmp(&(search_efivar->var.VariableName),
 421                                 new_var->VariableName, strsize1) &&
 422                         !efi_guidcmp(search_efivar->var.VendorGuid,
 423                                 new_var->VendorGuid)) {
 424                         found = 1;
 425                         break;
 426                 }
 427         }
 428         if (found) {
 429                 spin_unlock(&efivars->lock);
 430                 return -EINVAL;
 431         }
 432
 433         /* now *really* create the variable via EFI */
 434         status = efivars->ops->set_variable(new_var->VariableName,
 435                                             &new_var->VendorGuid,
 436                                             new_var->Attributes,
 437                                             new_var->DataSize,
 438                                             new_var->Data);
 439
 440         if (status != EFI_SUCCESS) {
 441                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
 442                         status);
 443                 spin_unlock(&efivars->lock);
 444                 return -EIO;
 445         }
 446         spin_unlock(&efivars->lock);
 447
 448         /* Create the entry in sysfs.  Locking is not required here */
 449         status = efivar_create_sysfs_entry(efivars,
 450                                            utf8_strsize(new_var->VariableName,
 451                                                         1024),
 452                                            new_var->VariableName,
 453                                            &new_var->VendorGuid);
 454         if (status) {
 455                 printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.\n");
 456         }
 457         return count;
 458 }
 459
 460 static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
 461                              struct bin_attribute *bin_attr,
 462                              char *buf, loff_t pos, size_t count)
 463 {
 464         struct efi_variable *del_var = (struct efi_variable *)buf;
 465         struct efivars *efivars = bin_attr->private;
 466         struct efivar_entry *search_efivar, *n;
 467         unsigned long strsize1, strsize2;
 468         efi_status_t status = EFI_NOT_FOUND;
 469         int found = 0;
 470
 471         if (!capable(CAP_SYS_ADMIN))
 472                 return -EACCES;
 473
 474         spin_lock(&efivars->lock);
 475
 476         /*
 477          * Does this variable already exist?
 478          */
 479         list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
 480                 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
 481                 strsize2 = utf8_strsize(del_var->VariableName, 1024);
 482                 if (strsize1 == strsize2 &&
 483                         !memcmp(&(search_efivar->var.VariableName),
 484                                 del_var->VariableName, strsize1) &&
 485                         !efi_guidcmp(search_efivar->var.VendorGuid,
 486                                 del_var->VendorGuid)) {
 487                         found = 1;
 488                         break;
 489                 }
 490         }
 491         if (!found) {
 492                 spin_unlock(&efivars->lock);
 493                 return -EINVAL;
 494         }
 495         /* force the Attributes/DataSize to 0 to ensure deletion */
 496         del_var->Attributes = 0;
 497         del_var->DataSize = 0;
 498
 499         status = efivars->ops->set_variable(del_var->VariableName,
 500                                             &del_var->VendorGuid,
 501                                             del_var->Attributes,
 502                                             del_var->DataSize,
 503                                             del_var->Data);
 504
 505         if (status != EFI_SUCCESS) {
 506                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
 507                         status);
 508                 spin_unlock(&efivars->lock);
 509                 return -EIO;
 510         }
 511         list_del(&search_efivar->list);
 512         /* We need to release this lock before unregistering. */
 513         spin_unlock(&efivars->lock);
 514         efivar_unregister(search_efivar);
 515
 516         /* It's dead Jim.... */
 517         return count;
 518 }
 519
 520 /*
 521  * Let's not leave out systab information that snuck into
 522  * the efivars driver
 523  */
 524 static ssize_t systab_show(struct kobject *kobj,
 525                            struct kobj_attribute *attr, char *buf)
 526 {
 527         char *str = buf;
 528
 529         if (!kobj || !buf)
 530                 return -EINVAL;
 531
 532         if (efi.mps != EFI_INVALID_TABLE_ADDR)
 533                 str += sprintf(str, "MPS=0x%lx\n", efi.mps);
 534         if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
 535                 str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
 536         if (efi.acpi != EFI_INVALID_TABLE_ADDR)
 537                 str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
 538         if (efi.smbios != EFI_INVALID_TABLE_ADDR)
 539                 str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
 540         if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
 541                 str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
 542         if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
 543                 str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
 544         if (efi.uga != EFI_INVALID_TABLE_ADDR)
 545                 str += sprintf(str, "UGA=0x%lx\n", efi.uga);
 546
 547         return str - buf;
 548 }
 549
 550 static struct kobj_attribute efi_attr_systab =
 551                         __ATTR(systab, 0400, systab_show, NULL);
 552
 553 static struct attribute *efi_subsys_attrs[] = {
 554         &efi_attr_systab.attr,
 555         NULL,   /* maybe more in the future? */
 556 };
 557
 558 static struct attribute_group efi_subsys_attr_group = {
 559         .attrs = efi_subsys_attrs,
 560 };
 561
 562 static struct kobject *efi_kobj;
 563
 564 /*
 565  * efivar_create_sysfs_entry()
 566  * Requires:
 567  *    variable_name_size = number of bytes required to hold
 568  *                         variable_name (not counting the NULL
 569  *                         character at the end.
 570  *    efivars->lock is not held on entry or exit.
 571  * Returns 1 on failure, 0 on success
 572  */
 573 static int
 574 efivar_create_sysfs_entry(struct efivars *efivars,
 575                           unsigned long variable_name_size,
 576                           efi_char16_t *variable_name,
 577                           efi_guid_t *vendor_guid)
 578 {
 579         int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
 580         char *short_name;
 581         struct efivar_entry *new_efivar;
 582
 583         short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
 584         new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
 585
 586         if (!short_name || !new_efivar)  {
 587                 kfree(short_name);
 588                 kfree(new_efivar);
 589                 return 1;
 590         }
 591
 592         new_efivar->efivars = efivars;
 593         memcpy(new_efivar->var.VariableName, variable_name,
 594                 variable_name_size);
 595         memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));
 596
 597         /* Convert Unicode to normal chars (assume top bits are 0),
 598            ala UTF-8 */
 599         for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
 600                 short_name[i] = variable_name[i] & 0xFF;
 601         }
 602         /* This is ugly, but necessary to separate one vendor's
 603            private variables from another's.         */
 604
 605         *(short_name + strlen(short_name)) = '-';
 606         efi_guid_unparse(vendor_guid, short_name + strlen(short_name));
 607
 608         new_efivar->kobj.kset = efivars->kset;
 609         i = kobject_init_and_add(&new_efivar->kobj, &efivar_ktype, NULL,
 610                                  "%s", short_name);
 611         if (i) {
 612                 kfree(short_name);
 613                 kfree(new_efivar);
 614                 return 1;
 615         }
 616
 617         kobject_uevent(&new_efivar->kobj, KOBJ_ADD);
 618         kfree(short_name);
 619         short_name = NULL;
 620
 621         spin_lock(&efivars->lock);
 622         list_add(&new_efivar->list, &efivars->list);
 623         spin_unlock(&efivars->lock);
 624
 625         return 0;
 626 }
 627
 628 static int
 629 create_efivars_bin_attributes(struct efivars *efivars)
 630 {
 631         struct bin_attribute *attr;
 632         int error;
 633
 634         /* new_var */
 635         attr = kzalloc(sizeof(*attr), GFP_KERNEL);
 636         if (!attr)
 637                 return -ENOMEM;
 638
 639         attr->attr.name = "new_var";
 640         attr->attr.mode = 0200;
 641         attr->write = efivar_create;
 642         attr->private = efivars;
 643         efivars->new_var = attr;
 644
 645         /* del_var */
 646         attr = kzalloc(sizeof(*attr), GFP_KERNEL);
 647         if (!attr) {
 648                 error = -ENOMEM;
 649                 goto out_free;
 650         }
 651         attr->attr.name = "del_var";
 652         attr->attr.mode = 0200;
 653         attr->write = efivar_delete;
 654         attr->private = efivars;
 655         efivars->del_var = attr;
 656
 657         sysfs_bin_attr_init(efivars->new_var);
 658         sysfs_bin_attr_init(efivars->del_var);
 659
 660         /* Register */
 661         error = sysfs_create_bin_file(&efivars->kset->kobj,
 662                                       efivars->new_var);
 663         if (error) {
 664                 printk(KERN_ERR "efivars: unable to create new_var sysfs file"
 665                         " due to error %d\n", error);
 666                 goto out_free;
 667         }
 668         error = sysfs_create_bin_file(&efivars->kset->kobj,
 669                                       efivars->del_var);
 670         if (error) {
 671                 printk(KERN_ERR "efivars: unable to create del_var sysfs file"
 672                         " due to error %d\n", error);
 673                 sysfs_remove_bin_file(&efivars->kset->kobj,
 674                                       efivars->new_var);
 675                 goto out_free;
 676         }
 677
 678         return 0;
 679 out_free:
 680         kfree(efivars->del_var);
 681         efivars->del_var = NULL;
 682         kfree(efivars->new_var);
 683         efivars->new_var = NULL;
 684         return error;
 685 }
 686
 687 void unregister_efivars(struct efivars *efivars)
 688 {
 689         struct efivar_entry *entry, *n;
 690
 691         list_for_each_entry_safe(entry, n, &efivars->list, list) {
 692                 spin_lock(&efivars->lock);
 693                 list_del(&entry->list);
 694                 spin_unlock(&efivars->lock);
 695                 efivar_unregister(entry);
 696         }
 697         if (efivars->new_var)
 698                 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->new_var);
 699         if (efivars->del_var)
 700                 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->del_var);
 701         kfree(efivars->new_var);
 702         kfree(efivars->del_var);
 703         kset_unregister(efivars->kset);
 704 }
 705 EXPORT_SYMBOL_GPL(unregister_efivars);
 706
 707 int register_efivars(struct efivars *efivars,
 708                      const struct efivar_operations *ops,
 709                      struct kobject *parent_kobj)
 710 {
 711         efi_status_t status = EFI_NOT_FOUND;
 712         efi_guid_t vendor_guid;
 713         efi_char16_t *variable_name;
 714         unsigned long variable_name_size = 1024;
 715         int error = 0;
 716
 717         variable_name = kzalloc(variable_name_size, GFP_KERNEL);
 718         if (!variable_name) {
 719                 printk(KERN_ERR "efivars: Memory allocation failed.\n");
 720                 return -ENOMEM;
 721         }
 722
 723         spin_lock_init(&efivars->lock);
 724         INIT_LIST_HEAD(&efivars->list);
 725         efivars->ops = ops;
 726
 727         efivars->kset = kset_create_and_add("vars", NULL, parent_kobj);
 728         if (!efivars->kset) {
 729                 printk(KERN_ERR "efivars: Subsystem registration failed.\n");
 730                 error = -ENOMEM;
 731                 goto out;
 732         }
 733
 734         /*
 735          * Per EFI spec, the maximum storage allocated for both
 736          * the variable name and variable data is 1024 bytes.
 737          */
 738
 739         do {
 740                 variable_name_size = 1024;
 741
 742                 status = ops->get_next_variable(&variable_name_size,
 743                                                 variable_name,
 744                                                 &vendor_guid);
 745                 switch (status) {
 746                 case EFI_SUCCESS:
 747                         efivar_create_sysfs_entry(efivars,
 748                                                   variable_name_size,
 749                                                   variable_name,
 750                                                   &vendor_guid);
 751                         break;
 752                 case EFI_NOT_FOUND:
 753                         break;
 754                 default:
 755                         printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
 756                                 status);
 757                         status = EFI_NOT_FOUND;
 758                         break;
 759                 }
 760         } while (status != EFI_NOT_FOUND);
 761
 762         error = create_efivars_bin_attributes(efivars);
 763         if (error)
 764                 unregister_efivars(efivars);
 765
 766 out:
 767         kfree(variable_name);
 768
 769         return error;
 770 }
 771 EXPORT_SYMBOL_GPL(register_efivars);
 772
 773 static struct efivars __efivars;
 774 static struct efivar_operations ops;
 775
 776 /*
 777  * For now we register the efi subsystem with the firmware subsystem
 778  * and the vars subsystem with the efi subsystem.  In the future, it
 779  * might make sense to split off the efi subsystem into its own
 780  * driver, but for now only efivars will register with it, so just
 781  * include it here.
 782  */
 783
 784 static int __init
 785 efivars_init(void)
 786 {
 787         int error = 0;
 788
 789         printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
 790                EFIVARS_DATE);
 791
 792         if (!efi_enabled)
 793                 return 0;
 794
 795         /* For now we'll register the efi directory at /sys/firmware/efi */
 796         efi_kobj = kobject_create_and_add("efi", firmware_kobj);
 797         if (!efi_kobj) {
 798                 printk(KERN_ERR "efivars: Firmware registration failed.\n");
 799                 return -ENOMEM;
 800         }
 801
 802         ops.get_variable = efi.get_variable;
 803         ops.set_variable = efi.set_variable;
 804         ops.get_next_variable = efi.get_next_variable;
 805         error = register_efivars(&__efivars, &ops, efi_kobj);
 806         if (error)
 807                 goto err_put;
 808
 809         /* Don't forget the systab entry */
 810         error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
 811         if (error) {
 812                 printk(KERN_ERR
 813                        "efivars: Sysfs attribute export failed with error %d.\n",
 814                        error);
 815                 goto err_unregister;
 816         }
 817
 818         return 0;
 819
 820 err_unregister:
 821         unregister_efivars(&__efivars);
 822 err_put:
 823         kobject_put(efi_kobj);
 824         return error;
 825 }
 826
 827 static void __exit
 828 efivars_exit(void)
 829 {
 830         if (efi_enabled) {
 831                 unregister_efivars(&__efivars);
 832                 kobject_put(efi_kobj);
 833         }
 834 }
 835
 836 module_init(efivars_init);
 837 module_exit(efivars_exit);
 838