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 #define _COMPONENT              ACPI_POWER_COMPONENT
  48 ACPI_MODULE_NAME("power");
  49 #define ACPI_POWER_COMPONENT            0x00800000
  50 #define ACPI_POWER_CLASS                "power_resource"
  51 #define ACPI_POWER_DEVICE_NAME          "Power Resource"
  52 #define ACPI_POWER_FILE_INFO            "info"
  53 #define ACPI_POWER_FILE_STATUS          "state"
  54 #define ACPI_POWER_RESOURCE_STATE_OFF   0x00
  55 #define ACPI_POWER_RESOURCE_STATE_ON    0x01
  56 #define ACPI_POWER_RESOURCE_STATE_UNKNOWN 0xFF
  57 static int acpi_power_add(struct acpi_device *device);
  58 static int acpi_power_remove(struct acpi_device *device, int type);
  59 static int acpi_power_resume(struct acpi_device *device);
  60 static int acpi_power_open_fs(struct inode *inode, struct file *file);
  61
  62 static struct acpi_device_id power_device_ids[] = {
  63         {ACPI_POWER_HID, 0},
  64         {"", 0},
  65 };
  66 MODULE_DEVICE_TABLE(acpi, power_device_ids);
  67
  68 static struct acpi_driver acpi_power_driver = {
  69         .name = "power",
  70         .class = ACPI_POWER_CLASS,
  71         .ids = power_device_ids,
  72         .ops = {
  73                 .add = acpi_power_add,
  74                 .remove = acpi_power_remove,
  75                 .resume = acpi_power_resume,
  76                 },
  77 };
  78
  79 struct acpi_power_reference {
  80         struct list_head node;
  81         struct acpi_device *device;
  82 };
  83
  84 struct acpi_power_resource {
  85         struct acpi_device * device;
  86         acpi_bus_id name;
  87         u32 system_level;
  88         u32 order;
  89         struct mutex resource_lock;
  90         struct list_head reference;
  91 };
  92
  93 static struct list_head acpi_power_resource_list;
  94
  95 static const struct file_operations acpi_power_fops = {
  96         .owner = THIS_MODULE,
  97         .open = acpi_power_open_fs,
  98         .read = seq_read,
  99         .llseek = seq_lseek,
 100         .release = single_release,
 101 };
 102
 103 /* --------------------------------------------------------------------------
 104                              Power Resource Management
 105    -------------------------------------------------------------------------- */
 106
 107 static int
 108 acpi_power_get_context(acpi_handle handle,
 109                        struct acpi_power_resource **resource)
 110 {
 111         int result = 0;
 112         struct acpi_device *device = NULL;
 113
 114
 115         if (!resource)
 116                 return -ENODEV;
 117
 118         result = acpi_bus_get_device(handle, &device);
 119         if (result) {
 120                 printk(KERN_WARNING PREFIX "Getting context [%p]\n", handle);
 121                 return result;
 122         }
 123
 124         *resource = acpi_driver_data(device);
 125         if (!resource)
 126                 return -ENODEV;
 127
 128         return 0;
 129 }
 130
 131 static int acpi_power_get_state(struct acpi_power_resource *resource, int *state)
 132 {
 133         acpi_status status = AE_OK;
 134         unsigned long sta = 0;
 135
 136
 137         if (!resource || !state)
 138                 return -EINVAL;
 139
 140         status = acpi_evaluate_integer(resource->device->handle, "_STA", NULL, &sta);
 141         if (ACPI_FAILURE(status))
 142                 return -ENODEV;
 143
 144         *state = (sta & 0x01)?ACPI_POWER_RESOURCE_STATE_ON:
 145                               ACPI_POWER_RESOURCE_STATE_OFF;
 146
 147         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] is %s\n",
 148                           resource->name, state ? "on" : "off"));
 149
 150         return 0;
 151 }
 152
 153 static int acpi_power_get_list_state(struct acpi_handle_list *list, int *state)
 154 {
 155         int result = 0, state1;
 156         struct acpi_power_resource *resource = NULL;
 157         u32 i = 0;
 158
 159
 160         if (!list || !state)
 161                 return -EINVAL;
 162
 163         /* The state of the list is 'on' IFF all resources are 'on'. */
 164
 165         for (i = 0; i < list->count; i++) {
 166                 result = acpi_power_get_context(list->handles[i], &resource);
 167                 if (result)
 168                         return result;
 169                 result = acpi_power_get_state(resource, &state1);
 170                 if (result)
 171                         return result;
 172
 173                 *state = state1;
 174
 175                 if (*state != ACPI_POWER_RESOURCE_STATE_ON)
 176                         break;
 177         }
 178
 179         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource list is %s\n",
 180                           *state ? "on" : "off"));
 181
 182         return result;
 183 }
 184
 185 static int acpi_power_on(acpi_handle handle, struct acpi_device *dev)
 186 {
 187         int result = 0, state;
 188         int found = 0;
 189         acpi_status status = AE_OK;
 190         struct acpi_power_resource *resource = NULL;
 191         struct list_head *node, *next;
 192         struct acpi_power_reference *ref;
 193
 194
 195         result = acpi_power_get_context(handle, &resource);
 196         if (result)
 197                 return result;
 198
 199         mutex_lock(&resource->resource_lock);
 200         list_for_each_safe(node, next, &resource->reference) {
 201                 ref = container_of(node, struct acpi_power_reference, node);
 202                 if (dev->handle == ref->device->handle) {
 203                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] already referenced by resource [%s]\n",
 204                                   dev->pnp.bus_id, resource->name));
 205                         found = 1;
 206                         break;
 207                 }
 208         }
 209
 210         if (!found) {
 211                 ref = kmalloc(sizeof (struct acpi_power_reference),
 212                     irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL);
 213                 if (!ref) {
 214                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "kmalloc() failed\n"));
 215                         mutex_unlock(&resource->resource_lock);
 216                         return -ENOMEM;
 217                 }
 218                 list_add_tail(&ref->node, &resource->reference);
 219                 ref->device = dev;
 220                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] added to resource [%s] references\n",
 221                           dev->pnp.bus_id, resource->name));
 222         }
 223         mutex_unlock(&resource->resource_lock);
 224
 225         status = acpi_evaluate_object(resource->device->handle, "_ON", NULL, NULL);
 226         if (ACPI_FAILURE(status))
 227                 return -ENODEV;
 228
 229         result = acpi_power_get_state(resource, &state);
 230         if (result)
 231                 return result;
 232         if (state != ACPI_POWER_RESOURCE_STATE_ON)
 233                 return -ENOEXEC;
 234
 235         /* Update the power resource's _device_ power state */
 236         resource->device->power.state = ACPI_STATE_D0;
 237
 238         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] turned on\n",
 239                           resource->name));
 240         return 0;
 241 }
 242
 243 static int acpi_power_off_device(acpi_handle handle, struct acpi_device *dev)
 244 {
 245         int result = 0, state;
 246         acpi_status status = AE_OK;
 247         struct acpi_power_resource *resource = NULL;
 248         struct list_head *node, *next;
 249         struct acpi_power_reference *ref;
 250
 251
 252         result = acpi_power_get_context(handle, &resource);
 253         if (result)
 254                 return result;
 255
 256         mutex_lock(&resource->resource_lock);
 257         list_for_each_safe(node, next, &resource->reference) {
 258                 ref = container_of(node, struct acpi_power_reference, node);
 259                 if (dev->handle == ref->device->handle) {
 260                         list_del(&ref->node);
 261                         kfree(ref);
 262                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] removed from resource [%s] references\n",
 263                             dev->pnp.bus_id, resource->name));
 264                         break;
 265                 }
 266         }
 267
 268         if (!list_empty(&resource->reference)) {
 269                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Cannot turn resource [%s] off - resource is in use\n",
 270                     resource->name));
 271                 mutex_unlock(&resource->resource_lock);
 272                 return 0;
 273         }
 274         mutex_unlock(&resource->resource_lock);
 275
 276         status = acpi_evaluate_object(resource->device->handle, "_OFF", NULL, NULL);
 277         if (ACPI_FAILURE(status))
 278                 return -ENODEV;
 279
 280         result = acpi_power_get_state(resource, &state);
 281         if (result)
 282                 return result;
 283         if (state != ACPI_POWER_RESOURCE_STATE_OFF)
 284                 return -ENOEXEC;
 285
 286         /* Update the power resource's _device_ power state */
 287         resource->device->power.state = ACPI_STATE_D3;
 288
 289         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] turned off\n",
 290                           resource->name));
 291
 292         return 0;
 293 }
 294
 295 /*
 296  * Prepare a wakeup device, two steps (Ref ACPI 2.0:P229):
 297  * 1. Power on the power resources required for the wakeup device
 298  * 2. Enable _PSW (power state wake) for the device if present
 299  */
 300 int acpi_enable_wakeup_device_power(struct acpi_device *dev)
 301 {
 302         union acpi_object arg = { ACPI_TYPE_INTEGER };
 303         struct acpi_object_list arg_list = { 1, &arg };
 304         acpi_status status = AE_OK;
 305         int i;
 306         int ret = 0;
 307
 308         if (!dev || !dev->wakeup.flags.valid)
 309                 return -1;
 310
 311         arg.integer.value = 1;
 312         /* Open power resource */
 313         for (i = 0; i < dev->wakeup.resources.count; i++) {
 314                 ret = acpi_power_on(dev->wakeup.resources.handles[i], dev);
 315                 if (ret) {
 316                         printk(KERN_ERR PREFIX "Transition power state\n");
 317                         dev->wakeup.flags.valid = 0;
 318                         return -1;
 319                 }
 320         }
 321
 322         /* Execute PSW */
 323         status = acpi_evaluate_object(dev->handle, "_PSW", &arg_list, NULL);
 324         if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
 325                 printk(KERN_ERR PREFIX "Evaluate _PSW\n");
 326                 dev->wakeup.flags.valid = 0;
 327                 ret = -1;
 328         }
 329
 330         return ret;
 331 }
 332
 333 /*
 334  * Shutdown a wakeup device, counterpart of above method
 335  * 1. Disable _PSW (power state wake)
 336  * 2. Shutdown down the power resources
 337  */
 338 int acpi_disable_wakeup_device_power(struct acpi_device *dev)
 339 {
 340         union acpi_object arg = { ACPI_TYPE_INTEGER };
 341         struct acpi_object_list arg_list = { 1, &arg };
 342         acpi_status status = AE_OK;
 343         int i;
 344         int ret = 0;
 345
 346
 347         if (!dev || !dev->wakeup.flags.valid)
 348                 return -1;
 349
 350         arg.integer.value = 0;
 351         /* Execute PSW */
 352         status = acpi_evaluate_object(dev->handle, "_PSW", &arg_list, NULL);
 353         if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
 354                 printk(KERN_ERR PREFIX "Evaluate _PSW\n");
 355                 dev->wakeup.flags.valid = 0;
 356                 return -1;
 357         }
 358
 359         /* Close power resource */
 360         for (i = 0; i < dev->wakeup.resources.count; i++) {
 361                 ret = acpi_power_off_device(dev->wakeup.resources.handles[i], dev);
 362                 if (ret) {
 363                         printk(KERN_ERR PREFIX "Transition power state\n");
 364                         dev->wakeup.flags.valid = 0;
 365                         return -1;
 366                 }
 367         }
 368
 369         return ret;
 370 }
 371
 372 /* --------------------------------------------------------------------------
 373                              Device Power Management
 374    -------------------------------------------------------------------------- */
 375
 376 int acpi_power_get_inferred_state(struct acpi_device *device)
 377 {
 378         int result = 0;
 379         struct acpi_handle_list *list = NULL;
 380         int list_state = 0;
 381         int i = 0;
 382
 383
 384         if (!device)
 385                 return -EINVAL;
 386
 387         device->power.state = ACPI_STATE_UNKNOWN;
 388
 389         /*
 390          * We know a device's inferred power state when all the resources
 391          * required for a given D-state are 'on'.
 392          */
 393         for (i = ACPI_STATE_D0; i < ACPI_STATE_D3; i++) {
 394                 list = &device->power.states[i].resources;
 395                 if (list->count < 1)
 396                         continue;
 397
 398                 result = acpi_power_get_list_state(list, &list_state);
 399                 if (result)
 400                         return result;
 401
 402                 if (list_state == ACPI_POWER_RESOURCE_STATE_ON) {
 403                         device->power.state = i;
 404                         return 0;
 405                 }
 406         }
 407
 408         device->power.state = ACPI_STATE_D3;
 409
 410         return 0;
 411 }
 412
 413 int acpi_power_transition(struct acpi_device *device, int state)
 414 {
 415         int result = 0;
 416         struct acpi_handle_list *cl = NULL;     /* Current Resources */
 417         struct acpi_handle_list *tl = NULL;     /* Target Resources */
 418         int i = 0;
 419
 420
 421         if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
 422                 return -EINVAL;
 423
 424         if ((device->power.state < ACPI_STATE_D0)
 425             || (device->power.state > ACPI_STATE_D3))
 426                 return -ENODEV;
 427
 428         cl = &device->power.states[device->power.state].resources;
 429         tl = &device->power.states[state].resources;
 430
 431         if (!cl->count && !tl->count) {
 432                 result = -ENODEV;
 433                 goto end;
 434         }
 435
 436         /* TBD: Resources must be ordered. */
 437
 438         /*
 439          * First we reference all power resources required in the target list
 440          * (e.g. so the device doesn't lose power while transitioning).
 441          */
 442         for (i = 0; i < tl->count; i++) {
 443                 result = acpi_power_on(tl->handles[i], device);
 444                 if (result)
 445                         goto end;
 446         }
 447
 448         if (device->power.state == state) {
 449                 goto end;
 450         }
 451
 452         /*
 453          * Then we dereference all power resources used in the current list.
 454          */
 455         for (i = 0; i < cl->count; i++) {
 456                 result = acpi_power_off_device(cl->handles[i], device);
 457                 if (result)
 458                         goto end;
 459         }
 460
 461      end:
 462         if (result)
 463                 device->power.state = ACPI_STATE_UNKNOWN;
 464         else {
 465         /* We shouldn't change the state till all above operations succeed */
 466                 device->power.state = state;
 467         }
 468
 469         return result;
 470 }
 471
 472 /* --------------------------------------------------------------------------
 473                               FS Interface (/proc)
 474    -------------------------------------------------------------------------- */
 475
 476 static struct proc_dir_entry *acpi_power_dir;
 477
 478 static int acpi_power_seq_show(struct seq_file *seq, void *offset)
 479 {
 480         int count = 0;
 481         int result = 0, state;
 482         struct acpi_power_resource *resource = NULL;
 483         struct list_head *node, *next;
 484         struct acpi_power_reference *ref;
 485
 486
 487         resource = seq->private;
 488
 489         if (!resource)
 490                 goto end;
 491
 492         result = acpi_power_get_state(resource, &state);
 493         if (result)
 494                 goto end;
 495
 496         seq_puts(seq, "state:                   ");
 497         switch (state) {
 498         case ACPI_POWER_RESOURCE_STATE_ON:
 499                 seq_puts(seq, "on\n");
 500                 break;
 501         case ACPI_POWER_RESOURCE_STATE_OFF:
 502                 seq_puts(seq, "off\n");
 503                 break;
 504         default:
 505                 seq_puts(seq, "unknown\n");
 506                 break;
 507         }
 508
 509         mutex_lock(&resource->resource_lock);
 510         list_for_each_safe(node, next, &resource->reference) {
 511                 ref = container_of(node, struct acpi_power_reference, node);
 512                 count++;
 513         }
 514         mutex_unlock(&resource->resource_lock);
 515
 516         seq_printf(seq, "system level:            S%d\n"
 517                    "order:                   %d\n"
 518                    "reference count:         %d\n",
 519                    resource->system_level,
 520                    resource->order, count);
 521
 522       end:
 523         return 0;
 524 }
 525
 526 static int acpi_power_open_fs(struct inode *inode, struct file *file)
 527 {
 528         return single_open(file, acpi_power_seq_show, PDE(inode)->data);
 529 }
 530
 531 static int acpi_power_add_fs(struct acpi_device *device)
 532 {
 533         struct proc_dir_entry *entry = NULL;
 534
 535
 536         if (!device)
 537                 return -EINVAL;
 538
 539         if (!acpi_device_dir(device)) {
 540                 acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device),
 541                                                      acpi_power_dir);
 542                 if (!acpi_device_dir(device))
 543                         return -ENODEV;
 544         }
 545
 546         /* 'status' [R] */
 547         entry = proc_create_data(ACPI_POWER_FILE_STATUS,
 548                                  S_IRUGO, acpi_device_dir(device),
 549                                  &acpi_power_fops, acpi_driver_data(device));
 550         if (!entry)
 551                 return -EIO;
 552         return 0;
 553 }
 554
 555 static int acpi_power_remove_fs(struct acpi_device *device)
 556 {
 557
 558         if (acpi_device_dir(device)) {
 559                 remove_proc_entry(ACPI_POWER_FILE_STATUS,
 560                                   acpi_device_dir(device));
 561                 remove_proc_entry(acpi_device_bid(device), acpi_power_dir);
 562                 acpi_device_dir(device) = NULL;
 563         }
 564
 565         return 0;
 566 }
 567
 568 /* --------------------------------------------------------------------------
 569                                 Driver Interface
 570    -------------------------------------------------------------------------- */
 571
 572 static int acpi_power_add(struct acpi_device *device)
 573 {
 574         int result = 0, state;
 575         acpi_status status = AE_OK;
 576         struct acpi_power_resource *resource = NULL;
 577         union acpi_object acpi_object;
 578         struct acpi_buffer buffer = { sizeof(acpi_object), &acpi_object };
 579
 580
 581         if (!device)
 582                 return -EINVAL;
 583
 584         resource = kzalloc(sizeof(struct acpi_power_resource), GFP_KERNEL);
 585         if (!resource)
 586                 return -ENOMEM;
 587
 588         resource->device = device;
 589         mutex_init(&resource->resource_lock);
 590         INIT_LIST_HEAD(&resource->reference);
 591         strcpy(resource->name, device->pnp.bus_id);
 592         strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
 593         strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
 594         acpi_driver_data(device) = resource;
 595
 596         /* Evalute the object to get the system level and resource order. */
 597         status = acpi_evaluate_object(device->handle, NULL, NULL, &buffer);
 598         if (ACPI_FAILURE(status)) {
 599                 result = -ENODEV;
 600                 goto end;
 601         }
 602         resource->system_level = acpi_object.power_resource.system_level;
 603         resource->order = acpi_object.power_resource.resource_order;
 604
 605         result = acpi_power_get_state(resource, &state);
 606         if (result)
 607                 goto end;
 608
 609         switch (state) {
 610         case ACPI_POWER_RESOURCE_STATE_ON:
 611                 device->power.state = ACPI_STATE_D0;
 612                 break;
 613         case ACPI_POWER_RESOURCE_STATE_OFF:
 614                 device->power.state = ACPI_STATE_D3;
 615                 break;
 616         default:
 617                 device->power.state = ACPI_STATE_UNKNOWN;
 618                 break;
 619         }
 620
 621         result = acpi_power_add_fs(device);
 622         if (result)
 623                 goto end;
 624
 625         printk(KERN_INFO PREFIX "%s [%s] (%s)\n", acpi_device_name(device),
 626                acpi_device_bid(device), state ? "on" : "off");
 627
 628       end:
 629         if (result)
 630                 kfree(resource);
 631
 632         return result;
 633 }
 634
 635 static int acpi_power_remove(struct acpi_device *device, int type)
 636 {
 637         struct acpi_power_resource *resource = NULL;
 638         struct list_head *node, *next;
 639
 640
 641         if (!device || !acpi_driver_data(device))
 642                 return -EINVAL;
 643
 644         resource = acpi_driver_data(device);
 645
 646         acpi_power_remove_fs(device);
 647
 648         mutex_lock(&resource->resource_lock);
 649         list_for_each_safe(node, next, &resource->reference) {
 650                 struct acpi_power_reference *ref = container_of(node, struct acpi_power_reference, node);
 651                 list_del(&ref->node);
 652                 kfree(ref);
 653         }
 654         mutex_unlock(&resource->resource_lock);
 655
 656         kfree(resource);
 657
 658         return 0;
 659 }
 660
 661 static int acpi_power_resume(struct acpi_device *device)
 662 {
 663         int result = 0, state;
 664         struct acpi_power_resource *resource = NULL;
 665         struct acpi_power_reference *ref;
 666
 667         if (!device || !acpi_driver_data(device))
 668                 return -EINVAL;
 669
 670         resource = (struct acpi_power_resource *)acpi_driver_data(device);
 671
 672         result = acpi_power_get_state(resource, &state);
 673         if (result)
 674                 return result;
 675
 676         mutex_lock(&resource->resource_lock);
 677         if (state == ACPI_POWER_RESOURCE_STATE_OFF &&
 678             !list_empty(&resource->reference)) {
 679                 ref = container_of(resource->reference.next, struct acpi_power_reference, node);
 680                 mutex_unlock(&resource->resource_lock);
 681                 result = acpi_power_on(device->handle, ref->device);
 682                 return result;
 683         }
 684
 685         mutex_unlock(&resource->resource_lock);
 686         return 0;
 687 }
 688
 689 static int __init acpi_power_init(void)
 690 {
 691         int result = 0;
 692
 693
 694         if (acpi_disabled)
 695                 return 0;
 696
 697         INIT_LIST_HEAD(&acpi_power_resource_list);
 698
 699         acpi_power_dir = proc_mkdir(ACPI_POWER_CLASS, acpi_root_dir);
 700         if (!acpi_power_dir)
 701                 return -ENODEV;
 702
 703         result = acpi_bus_register_driver(&acpi_power_driver);
 704         if (result < 0) {
 705                 remove_proc_entry(ACPI_POWER_CLASS, acpi_root_dir);
 706                 return -ENODEV;
 707         }
 708
 709         return 0;
 710 }
 711
 712 subsys_initcall(acpi_power_init);