drivers/acpi/power.c

   1 /*
   2  *  acpi_power.c - ACPI Bus Power Management ($Revision: 39 $)
   3  *
   4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   6  *
   7  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; either version 2 of the License, or (at
  12  *  your option) any later version.
  13  *
  14  *  This program is distributed in the hope that it will be useful, but
  15  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  *  General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License along
  20  *  with this program; if not, write to the Free Software Foundation, Inc.,
  21  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  22  *
  23  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  24  */
  25
  26 /*
  27  * ACPI power-managed devices may be controlled in two ways:
  28  * 1. via "Device Specific (D-State) Control"
  29  * 2. via "Power Resource Control".
  30  * This module is used to manage devices relying on Power Resource Control.
  31  *
  32  * An ACPI "power resource object" describes a software controllable power
  33  * plane, clock plane, or other resource used by a power managed device.
  34  * A device may rely on multiple power resources, and a power resource
  35  * may be shared by multiple devices.
  36  */
  37
  38 #include <linux/kernel.h>
  39 #include <linux/module.h>
  40 #include <linux/init.h>
  41 #include <linux/types.h>
  42 #include <linux/proc_fs.h>
  43 #include <linux/seq_file.h>
  44 #include <acpi/acpi_bus.h>
  45 #include <acpi/acpi_drivers.h>
  46
  47
  48 #define _COMPONENT              ACPI_POWER_COMPONENT
  49 ACPI_MODULE_NAME                ("acpi_power")
  50
  51 #define ACPI_POWER_COMPONENT            0x00800000
  52 #define ACPI_POWER_CLASS                "power_resource"
  53 #define ACPI_POWER_DRIVER_NAME          "ACPI Power Resource Driver"
  54 #define ACPI_POWER_DEVICE_NAME          "Power Resource"
  55 #define ACPI_POWER_FILE_INFO            "info"
  56 #define ACPI_POWER_FILE_STATUS          "state"
  57 #define ACPI_POWER_RESOURCE_STATE_OFF   0x00
  58 #define ACPI_POWER_RESOURCE_STATE_ON    0x01
  59 #define ACPI_POWER_RESOURCE_STATE_UNKNOWN 0xFF
  60
  61 static int acpi_power_add (struct acpi_device *device);
  62 static int acpi_power_remove (struct acpi_device *device, int type);
  63 static int acpi_power_open_fs(struct inode *inode, struct file *file);
  64
  65 static struct acpi_driver acpi_power_driver = {
  66         .name =         ACPI_POWER_DRIVER_NAME,
  67         .class =        ACPI_POWER_CLASS,
  68         .ids =          ACPI_POWER_HID,
  69         .ops =          {
  70                                 .add =          acpi_power_add,
  71                                 .remove =       acpi_power_remove,
  72                         },
  73 };
  74
  75 struct acpi_power_resource
  76 {
  77         acpi_handle             handle;
  78         acpi_bus_id             name;
  79         u32                     system_level;
  80         u32                     order;
  81         int                     state;
  82         int                     references;
  83 };
  84
  85 static struct list_head         acpi_power_resource_list;
  86
  87 static struct file_operations acpi_power_fops = {
  88         .open           = acpi_power_open_fs,
  89         .read           = seq_read,
  90         .llseek         = seq_lseek,
  91         .release        = single_release,
  92 };
  93
  94 /* --------------------------------------------------------------------------
  95                              Power Resource Management
  96    -------------------------------------------------------------------------- */
  97
  98 static int
  99 acpi_power_get_context (
 100         acpi_handle             handle,
 101         struct acpi_power_resource **resource)
 102 {
 103         int                     result = 0;
 104         struct acpi_device      *device = NULL;
 105
 106         ACPI_FUNCTION_TRACE("acpi_power_get_context");
 107
 108         if (!resource)
 109                 return_VALUE(-ENODEV);
 110
 111         result = acpi_bus_get_device(handle, &device);
 112         if (result) {
 113                 ACPI_DEBUG_PRINT((ACPI_DB_WARN, "Error getting context [%p]\n",
 114                         handle));
 115                 return_VALUE(result);
 116         }
 117
 118         *resource = (struct acpi_power_resource *) acpi_driver_data(device);
 119         if (!resource)
 120                 return_VALUE(-ENODEV);
 121
 122         return_VALUE(0);
 123 }
 124
 125
 126 static int
 127 acpi_power_get_state (
 128         struct acpi_power_resource *resource)
 129 {
 130         acpi_status             status = AE_OK;
 131         unsigned long           sta = 0;
 132
 133         ACPI_FUNCTION_TRACE("acpi_power_get_state");
 134
 135         if (!resource)
 136                 return_VALUE(-EINVAL);
 137
 138         status = acpi_evaluate_integer(resource->handle, "_STA", NULL, &sta);
 139         if (ACPI_FAILURE(status))
 140                 return_VALUE(-ENODEV);
 141
 142         if (sta & 0x01)
 143                 resource->state = ACPI_POWER_RESOURCE_STATE_ON;
 144         else
 145                 resource->state = ACPI_POWER_RESOURCE_STATE_OFF;
 146
 147         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] is %s\n",
 148                 resource->name, resource->state?"on":"off"));
 149
 150         return_VALUE(0);
 151 }
 152
 153
 154 static int
 155 acpi_power_get_list_state (
 156         struct acpi_handle_list *list,
 157         int                     *state)
 158 {
 159         int                     result = 0;
 160         struct acpi_power_resource *resource = NULL;
 161         u32                     i = 0;
 162
 163         ACPI_FUNCTION_TRACE("acpi_power_get_list_state");
 164
 165         if (!list || !state)
 166                 return_VALUE(-EINVAL);
 167
 168         /* The state of the list is 'on' IFF all resources are 'on'. */
 169
 170         for (i=0; i<list->count; i++) {
 171                 result = acpi_power_get_context(list->handles[i], &resource);
 172                 if (result)
 173                         return_VALUE(result);
 174                 result = acpi_power_get_state(resource);
 175                 if (result)
 176                         return_VALUE(result);
 177
 178                 *state = resource->state;
 179
 180                 if (*state != ACPI_POWER_RESOURCE_STATE_ON)
 181                         break;
 182         }
 183
 184         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource list is %s\n",
 185                 *state?"on":"off"));
 186
 187         return_VALUE(result);
 188 }
 189
 190
 191 static int
 192 acpi_power_on (
 193         acpi_handle             handle)
 194 {
 195         int                     result = 0;
 196         acpi_status             status = AE_OK;
 197         struct acpi_device      *device = NULL;
 198         struct acpi_power_resource *resource = NULL;
 199
 200         ACPI_FUNCTION_TRACE("acpi_power_on");
 201
 202         result = acpi_power_get_context(handle, &resource);
 203         if (result)
 204                 return_VALUE(result);
 205
 206         resource->references++;
 207
 208         if ((resource->references > 1)
 209                 || (resource->state == ACPI_POWER_RESOURCE_STATE_ON)) {
 210                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] already on\n",
 211                         resource->name));
 212                 return_VALUE(0);
 213         }
 214
 215         status = acpi_evaluate_object(resource->handle, "_ON", NULL, NULL);
 216         if (ACPI_FAILURE(status))
 217                 return_VALUE(-ENODEV);
 218
 219         result = acpi_power_get_state(resource);
 220         if (result)
 221                 return_VALUE(result);
 222         if (resource->state != ACPI_POWER_RESOURCE_STATE_ON)
 223                 return_VALUE(-ENOEXEC);
 224
 225         /* Update the power resource's _device_ power state */
 226         result = acpi_bus_get_device(resource->handle, &device);
 227         if (result)
 228                 return_VALUE(result);
 229         device->power.state = ACPI_STATE_D0;
 230
 231         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] turned on\n",
 232                 resource->name));
 233
 234         return_VALUE(0);
 235 }
 236
 237
 238 static int
 239 acpi_power_off_device (
 240         acpi_handle             handle)
 241 {
 242         int                     result = 0;
 243         acpi_status             status = AE_OK;
 244         struct acpi_device      *device = NULL;
 245         struct acpi_power_resource *resource = NULL;
 246
 247         ACPI_FUNCTION_TRACE("acpi_power_off_device");
 248
 249         result = acpi_power_get_context(handle, &resource);
 250         if (result)
 251                 return_VALUE(result);
 252
 253         if (resource->references)
 254                 resource->references--;
 255
 256         if (resource->references) {
 257                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 258                         "Resource [%s] is still in use, dereferencing\n",
 259                         device->pnp.bus_id));
 260                 return_VALUE(0);
 261         }
 262
 263         if (resource->state == ACPI_POWER_RESOURCE_STATE_OFF) {
 264                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] already off\n",
 265                         device->pnp.bus_id));
 266                 return_VALUE(0);
 267         }
 268
 269         status = acpi_evaluate_object(resource->handle, "_OFF", NULL, NULL);
 270         if (ACPI_FAILURE(status))
 271                 return_VALUE(-ENODEV);
 272
 273         result = acpi_power_get_state(resource);
 274         if (result)
 275                 return_VALUE(result);
 276         if (resource->state != ACPI_POWER_RESOURCE_STATE_OFF)
 277                 return_VALUE(-ENOEXEC);
 278
 279         /* Update the power resource's _device_ power state */
 280         result = acpi_bus_get_device(resource->handle, &device);
 281         if (result)
 282                 return_VALUE(result);
 283         device->power.state = ACPI_STATE_D3;
 284
 285         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] turned off\n",
 286                 resource->name));
 287
 288         return_VALUE(0);
 289 }
 290
 291 /*
 292  * Prepare a wakeup device, two steps (Ref ACPI 2.0:P229):
 293  * 1. Power on the power resources required for the wakeup device
 294  * 2. Enable _PSW (power state wake) for the device if present
 295  */
 296 int acpi_enable_wakeup_device_power (struct acpi_device *dev)
 297 {
 298         union acpi_object               arg = {ACPI_TYPE_INTEGER};
 299         struct acpi_object_list arg_list = {1, &arg};
 300         acpi_status                     status = AE_OK;
 301         int                                     i;
 302         int                                     ret = 0;
 303
 304         ACPI_FUNCTION_TRACE("acpi_enable_wakeup_device_power");
 305         if (!dev || !dev->wakeup.flags.valid)
 306                 return_VALUE(-1);
 307
 308         arg.integer.value = 1;
 309         /* Open power resource */
 310         for (i = 0; i < dev->wakeup.resources.count; i++) {
 311                 ret = acpi_power_on(dev->wakeup.resources.handles[i]);
 312                 if (ret) {
 313                         ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 314                                 "Error transition power state\n"));
 315                         dev->wakeup.flags.valid = 0;
 316                         return_VALUE(-1);
 317                 }
 318         }
 319
 320         /* Execute PSW */
 321         status = acpi_evaluate_object(dev->handle, "_PSW", &arg_list, NULL);
 322         if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
 323                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error evaluate _PSW\n"));
 324                 dev->wakeup.flags.valid = 0;
 325                 ret = -1;
 326         }
 327
 328         return_VALUE(ret);
 329 }
 330
 331 /*
 332  * Shutdown a wakeup device, counterpart of above method
 333  * 1. Disable _PSW (power state wake)
 334  * 2. Shutdown down the power resources
 335  */
 336 int acpi_disable_wakeup_device_power (struct acpi_device *dev)
 337 {
 338         union acpi_object               arg = {ACPI_TYPE_INTEGER};
 339         struct acpi_object_list arg_list = {1, &arg};
 340         acpi_status                     status = AE_OK;
 341         int                                     i;
 342         int                                     ret = 0;
 343
 344         ACPI_FUNCTION_TRACE("acpi_disable_wakeup_device_power");
 345
 346         if (!dev || !dev->wakeup.flags.valid)
 347                 return_VALUE(-1);
 348
 349         arg.integer.value = 0;
 350         /* Execute PSW */
 351         status = acpi_evaluate_object(dev->handle, "_PSW", &arg_list, NULL);
 352         if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
 353                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error evaluate _PSW\n"));
 354                 dev->wakeup.flags.valid = 0;
 355                 return_VALUE(-1);
 356         }
 357
 358         /* Close power resource */
 359         for (i = 0; i < dev->wakeup.resources.count; i++) {
 360                 ret = acpi_power_off_device(dev->wakeup.resources.handles[i]);
 361                 if (ret) {
 362                         ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 363                                 "Error transition power state\n"));
 364                         dev->wakeup.flags.valid = 0;
 365                         return_VALUE(-1);
 366                 }
 367         }
 368
 369         return_VALUE(ret);
 370 }
 371
 372 /* --------------------------------------------------------------------------
 373                              Device Power Management
 374    -------------------------------------------------------------------------- */
 375
 376 int
 377 acpi_power_get_inferred_state (
 378         struct acpi_device      *device)
 379 {
 380         int                     result = 0;
 381         struct acpi_handle_list *list = NULL;
 382         int                     list_state = 0;
 383         int                     i = 0;
 384
 385         ACPI_FUNCTION_TRACE("acpi_power_get_inferred_state");
 386
 387         if (!device)
 388                 return_VALUE(-EINVAL);
 389
 390         device->power.state = ACPI_STATE_UNKNOWN;
 391
 392         /*
 393          * We know a device's inferred power state when all the resources
 394          * required for a given D-state are 'on'.
 395          */
 396         for (i=ACPI_STATE_D0; i<ACPI_STATE_D3; i++) {
 397                 list = &device->power.states[i].resources;
 398                 if (list->count < 1)
 399                         continue;
 400
 401                 result = acpi_power_get_list_state(list, &list_state);
 402                 if (result)
 403                         return_VALUE(result);
 404
 405                 if (list_state == ACPI_POWER_RESOURCE_STATE_ON) {
 406                         device->power.state = i;
 407                         return_VALUE(0);
 408                 }
 409         }
 410
 411         device->power.state = ACPI_STATE_D3;
 412
 413         return_VALUE(0);
 414 }
 415
 416
 417 int
 418 acpi_power_transition (
 419         struct acpi_device      *device,
 420         int                     state)
 421 {
 422         int                     result = 0;
 423         struct acpi_handle_list *cl = NULL;     /* Current Resources */
 424         struct acpi_handle_list *tl = NULL;     /* Target Resources */
 425         int                     i = 0;
 426
 427         ACPI_FUNCTION_TRACE("acpi_power_transition");
 428
 429         if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
 430                 return_VALUE(-EINVAL);
 431
 432         if ((device->power.state < ACPI_STATE_D0) || (device->power.state > ACPI_STATE_D3))
 433                 return_VALUE(-ENODEV);
 434
 435         cl = &device->power.states[device->power.state].resources;
 436         tl = &device->power.states[state].resources;
 437
 438         device->power.state = ACPI_STATE_UNKNOWN;
 439
 440         if (!cl->count && !tl->count) {
 441                 result = -ENODEV;
 442                 goto end;
 443         }
 444
 445         /* TBD: Resources must be ordered. */
 446
 447         /*
 448          * First we reference all power resources required in the target list
 449          * (e.g. so the device doesn't lose power while transitioning).
 450          */
 451         for (i=0; i<tl->count; i++) {
 452                 result = acpi_power_on(tl->handles[i]);
 453                 if (result)
 454                         goto end;
 455         }
 456
 457         /*
 458          * Then we dereference all power resources used in the current list.
 459          */
 460         for (i=0; i<cl->count; i++) {
 461                 result = acpi_power_off_device(cl->handles[i]);
 462                 if (result)
 463                         goto end;
 464         }
 465
 466         /* We shouldn't change the state till all above operations succeed */
 467         device->power.state = state;
 468 end:
 469         if (result)
 470                 ACPI_DEBUG_PRINT((ACPI_DB_WARN,
 471                         "Error transitioning device [%s] to D%d\n",
 472                         device->pnp.bus_id, state));
 473
 474         return_VALUE(result);
 475 }
 476
 477
 478 /* --------------------------------------------------------------------------
 479                               FS Interface (/proc)
 480    -------------------------------------------------------------------------- */
 481
 482 static struct proc_dir_entry    *acpi_power_dir;
 483
 484 static int acpi_power_seq_show(struct seq_file *seq, void *offset)
 485 {
 486         struct acpi_power_resource *resource = NULL;
 487
 488         ACPI_FUNCTION_TRACE("acpi_power_seq_show");
 489
 490         resource = (struct acpi_power_resource *)seq->private;
 491
 492         if (!resource)
 493                 goto end;
 494
 495         seq_puts(seq, "state:                   ");
 496         switch (resource->state) {
 497         case ACPI_POWER_RESOURCE_STATE_ON:
 498                 seq_puts(seq, "on\n");
 499                 break;
 500         case ACPI_POWER_RESOURCE_STATE_OFF:
 501                 seq_puts(seq, "off\n");
 502                 break;
 503         default:
 504                 seq_puts(seq, "unknown\n");
 505                 break;
 506         }
 507
 508         seq_printf(seq, "system level:            S%d\n"
 509                         "order:                   %d\n"
 510                         "reference count:         %d\n",
 511                         resource->system_level,
 512                         resource->order,
 513                         resource->references);
 514
 515 end:
 516         return_VALUE(0);
 517 }
 518
 519 static int acpi_power_open_fs(struct inode *inode, struct file *file)
 520 {
 521         return single_open(file, acpi_power_seq_show, PDE(inode)->data);
 522 }
 523
 524 static int
 525 acpi_power_add_fs (
 526         struct acpi_device      *device)
 527 {
 528         struct proc_dir_entry   *entry = NULL;
 529
 530         ACPI_FUNCTION_TRACE("acpi_power_add_fs");
 531
 532         if (!device)
 533                 return_VALUE(-EINVAL);
 534
 535         if (!acpi_device_dir(device)) {
 536                 acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device),
 537                         acpi_power_dir);
 538                 if (!acpi_device_dir(device))
 539                         return_VALUE(-ENODEV);
 540         }
 541
 542         /* 'status' [R] */
 543         entry = create_proc_entry(ACPI_POWER_FILE_STATUS,
 544                 S_IRUGO, acpi_device_dir(device));
 545         if (!entry)
 546                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 547                         "Unable to create '%s' fs entry\n",
 548                         ACPI_POWER_FILE_STATUS));
 549         else {
 550                 entry->proc_fops = &acpi_power_fops;
 551                 entry->data = acpi_driver_data(device);
 552         }
 553
 554         return_VALUE(0);
 555 }
 556
 557
 558 static int
 559 acpi_power_remove_fs (
 560         struct acpi_device      *device)
 561 {
 562         ACPI_FUNCTION_TRACE("acpi_power_remove_fs");
 563
 564         if (acpi_device_dir(device)) {
 565                 remove_proc_entry(ACPI_POWER_FILE_STATUS,
 566                                   acpi_device_dir(device));
 567                 remove_proc_entry(acpi_device_bid(device), acpi_power_dir);
 568                 acpi_device_dir(device) = NULL;
 569         }
 570
 571         return_VALUE(0);
 572 }
 573
 574
 575 /* --------------------------------------------------------------------------
 576                                 Driver Interface
 577    -------------------------------------------------------------------------- */
 578
 579 static int
 580 acpi_power_add (
 581         struct acpi_device      *device)
 582 {
 583         int                     result = 0;
 584         acpi_status             status = AE_OK;
 585         struct acpi_power_resource *resource = NULL;
 586         union acpi_object       acpi_object;
 587         struct acpi_buffer      buffer = {sizeof(acpi_object), &acpi_object};
 588
 589         ACPI_FUNCTION_TRACE("acpi_power_add");
 590
 591         if (!device)
 592                 return_VALUE(-EINVAL);
 593
 594         resource = kmalloc(sizeof(struct acpi_power_resource), GFP_KERNEL);
 595         if (!resource)
 596                 return_VALUE(-ENOMEM);
 597         memset(resource, 0, sizeof(struct acpi_power_resource));
 598
 599         resource->handle = device->handle;
 600         strcpy(resource->name, device->pnp.bus_id);
 601         strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
 602         strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
 603         acpi_driver_data(device) = resource;
 604
 605         /* Evalute the object to get the system level and resource order. */
 606         status = acpi_evaluate_object(resource->handle, NULL, NULL, &buffer);
 607         if (ACPI_FAILURE(status)) {
 608                 result = -ENODEV;
 609                 goto end;
 610         }
 611         resource->system_level = acpi_object.power_resource.system_level;
 612         resource->order = acpi_object.power_resource.resource_order;
 613
 614         result = acpi_power_get_state(resource);
 615         if (result)
 616                 goto end;
 617
 618         switch (resource->state) {
 619         case ACPI_POWER_RESOURCE_STATE_ON:
 620                 device->power.state = ACPI_STATE_D0;
 621                 break;
 622         case ACPI_POWER_RESOURCE_STATE_OFF:
 623                 device->power.state = ACPI_STATE_D3;
 624                 break;
 625         default:
 626                 device->power.state = ACPI_STATE_UNKNOWN;
 627                 break;
 628         }
 629
 630         result = acpi_power_add_fs(device);
 631         if (result)
 632                 goto end;
 633
 634         printk(KERN_INFO PREFIX "%s [%s] (%s)\n", acpi_device_name(device),
 635                 acpi_device_bid(device), resource->state?"on":"off");
 636
 637 end:
 638         if (result)
 639                 kfree(resource);
 640
 641         return_VALUE(result);
 642 }
 643
 644
 645 static int
 646 acpi_power_remove (
 647         struct acpi_device      *device,
 648         int                     type)
 649 {
 650         struct acpi_power_resource *resource = NULL;
 651
 652         ACPI_FUNCTION_TRACE("acpi_power_remove");
 653
 654         if (!device || !acpi_driver_data(device))
 655                 return_VALUE(-EINVAL);
 656
 657         resource = (struct acpi_power_resource *) acpi_driver_data(device);
 658
 659         acpi_power_remove_fs(device);
 660
 661         kfree(resource);
 662
 663         return_VALUE(0);
 664 }
 665
 666
 667 static int __init acpi_power_init (void)
 668 {
 669         int                     result = 0;
 670
 671         ACPI_FUNCTION_TRACE("acpi_power_init");
 672
 673         if (acpi_disabled)
 674                 return_VALUE(0);
 675
 676         INIT_LIST_HEAD(&acpi_power_resource_list);
 677
 678         acpi_power_dir = proc_mkdir(ACPI_POWER_CLASS, acpi_root_dir);
 679         if (!acpi_power_dir)
 680                 return_VALUE(-ENODEV);
 681
 682         result = acpi_bus_register_driver(&acpi_power_driver);
 683         if (result < 0) {
 684                 remove_proc_entry(ACPI_POWER_CLASS, acpi_root_dir);
 685                 return_VALUE(-ENODEV);
 686         }
 687
 688         return_VALUE(0);
 689 }
 690
 691 subsys_initcall(acpi_power_init);
 692