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         .open = acpi_power_open_fs,
  97         .read = seq_read,
  98         .llseek = seq_lseek,
  99         .release = single_release,
 100 };
 101
 102 /* --------------------------------------------------------------------------
 103                              Power Resource Management
 104    -------------------------------------------------------------------------- */
 105
 106 static int
 107 acpi_power_get_context(acpi_handle handle,
 108                        struct acpi_power_resource **resource)
 109 {
 110         int result = 0;
 111         struct acpi_device *device = NULL;
 112
 113
 114         if (!resource)
 115                 return -ENODEV;
 116
 117         result = acpi_bus_get_device(handle, &device);
 118         if (result) {
 119                 printk(KERN_WARNING PREFIX "Getting context [%p]\n", handle);
 120                 return result;
 121         }
 122
 123         *resource = acpi_driver_data(device);
 124         if (!resource)
 125                 return -ENODEV;
 126
 127         return 0;
 128 }
 129
 130 static int acpi_power_get_state(struct acpi_power_resource *resource, int *state)
 131 {
 132         acpi_status status = AE_OK;
 133         unsigned long sta = 0;
 134
 135
 136         if (!resource || !state)
 137                 return -EINVAL;
 138
 139         status = acpi_evaluate_integer(resource->device->handle, "_STA", NULL, &sta);
 140         if (ACPI_FAILURE(status))
 141                 return -ENODEV;
 142
 143         *state = (sta & 0x01)?ACPI_POWER_RESOURCE_STATE_ON:
 144                               ACPI_POWER_RESOURCE_STATE_OFF;
 145
 146         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] is %s\n",
 147                           resource->name, state ? "on" : "off"));
 148
 149         return 0;
 150 }
 151
 152 static int acpi_power_get_list_state(struct acpi_handle_list *list, int *state)
 153 {
 154         int result = 0, state1;
 155         struct acpi_power_resource *resource = NULL;
 156         u32 i = 0;
 157
 158
 159         if (!list || !state)
 160                 return -EINVAL;
 161
 162         /* The state of the list is 'on' IFF all resources are 'on'. */
 163
 164         for (i = 0; i < list->count; i++) {
 165                 result = acpi_power_get_context(list->handles[i], &resource);
 166                 if (result)
 167                         return result;
 168                 result = acpi_power_get_state(resource, &state1);
 169                 if (result)
 170                         return result;
 171
 172                 *state = state1;
 173
 174                 if (*state != ACPI_POWER_RESOURCE_STATE_ON)
 175                         break;
 176         }
 177
 178         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource list is %s\n",
 179                           *state ? "on" : "off"));
 180
 181         return result;
 182 }
 183
 184 static int acpi_power_on(acpi_handle handle, struct acpi_device *dev)
 185 {
 186         int result = 0, state;
 187         int found = 0;
 188         acpi_status status = AE_OK;
 189         struct acpi_power_resource *resource = NULL;
 190         struct list_head *node, *next;
 191         struct acpi_power_reference *ref;
 192
 193
 194         result = acpi_power_get_context(handle, &resource);
 195         if (result)
 196                 return result;
 197
 198         mutex_lock(&resource->resource_lock);
 199         list_for_each_safe(node, next, &resource->reference) {
 200                 ref = container_of(node, struct acpi_power_reference, node);
 201                 if (dev->handle == ref->device->handle) {
 202                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] already referenced by resource [%s]\n",
 203                                   dev->pnp.bus_id, resource->name));
 204                         found = 1;
 205                         break;
 206                 }
 207         }
 208
 209         if (!found) {
 210                 ref = kmalloc(sizeof (struct acpi_power_reference),
 211                     irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL);
 212                 if (!ref) {
 213                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "kmalloc() failed\n"));
 214                         mutex_unlock(&resource->resource_lock);
 215                         return -ENOMEM;
 216                 }
 217                 list_add_tail(&ref->node, &resource->reference);
 218                 ref->device = dev;
 219                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] added to resource [%s] references\n",
 220                           dev->pnp.bus_id, resource->name));
 221         }
 222         mutex_unlock(&resource->resource_lock);
 223
 224         status = acpi_evaluate_object(resource->device->handle, "_ON", NULL, NULL);
 225         if (ACPI_FAILURE(status))
 226                 return -ENODEV;
 227
 228         result = acpi_power_get_state(resource, &state);
 229         if (result)
 230                 return result;
 231         if (state != ACPI_POWER_RESOURCE_STATE_ON)
 232                 return -ENOEXEC;
 233
 234         /* Update the power resource's _device_ power state */
 235         resource->device->power.state = ACPI_STATE_D0;
 236
 237         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] turned on\n",
 238                           resource->name));
 239         return 0;
 240 }
 241
 242 static int acpi_power_off_device(acpi_handle handle, struct acpi_device *dev)
 243 {
 244         int result = 0, state;
 245         acpi_status status = AE_OK;
 246         struct acpi_power_resource *resource = NULL;
 247         struct list_head *node, *next;
 248         struct acpi_power_reference *ref;
 249
 250
 251         result = acpi_power_get_context(handle, &resource);
 252         if (result)
 253                 return result;
 254
 255         mutex_lock(&resource->resource_lock);
 256         list_for_each_safe(node, next, &resource->reference) {
 257                 ref = container_of(node, struct acpi_power_reference, node);
 258                 if (dev->handle == ref->device->handle) {
 259                         list_del(&ref->node);
 260                         kfree(ref);
 261                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] removed from resource [%s] references\n",
 262                             dev->pnp.bus_id, resource->name));
 263                         break;
 264                 }
 265         }
 266
 267         if (!list_empty(&resource->reference)) {
 268                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Cannot turn resource [%s] off - resource is in use\n",
 269                     resource->name));
 270                 mutex_unlock(&resource->resource_lock);
 271                 return 0;
 272         }
 273         mutex_unlock(&resource->resource_lock);
 274
 275         status = acpi_evaluate_object(resource->device->handle, "_OFF", NULL, NULL);
 276         if (ACPI_FAILURE(status))
 277                 return -ENODEV;
 278
 279         result = acpi_power_get_state(resource, &state);
 280         if (result)
 281                 return result;
 282         if (state != ACPI_POWER_RESOURCE_STATE_OFF)
 283                 return -ENOEXEC;
 284
 285         /* Update the power resource's _device_ power state */
 286         resource->device->power.state = ACPI_STATE_D3;
 287
 288         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] turned off\n",
 289                           resource->name));
 290
 291         return 0;
 292 }
 293
 294 /*
 295  * Prepare a wakeup device, two steps (Ref ACPI 2.0:P229):
 296  * 1. Power on the power resources required for the wakeup device
 297  * 2. Enable _PSW (power state wake) for the device if present
 298  */
 299 int acpi_enable_wakeup_device_power(struct acpi_device *dev)
 300 {
 301         union acpi_object arg = { ACPI_TYPE_INTEGER };
 302         struct acpi_object_list arg_list = { 1, &arg };
 303         acpi_status status = AE_OK;
 304         int i;
 305         int ret = 0;
 306
 307         if (!dev || !dev->wakeup.flags.valid)
 308                 return -1;
 309
 310         arg.integer.value = 1;
 311         /* Open power resource */
 312         for (i = 0; i < dev->wakeup.resources.count; i++) {
 313                 ret = acpi_power_on(dev->wakeup.resources.handles[i], dev);
 314                 if (ret) {
 315                         printk(KERN_ERR PREFIX "Transition power state\n");
 316                         dev->wakeup.flags.valid = 0;
 317                         return -1;
 318                 }
 319         }
 320
 321         /* Execute PSW */
 322         status = acpi_evaluate_object(dev->handle, "_PSW", &arg_list, NULL);
 323         if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
 324                 printk(KERN_ERR PREFIX "Evaluate _PSW\n");
 325                 dev->wakeup.flags.valid = 0;
 326                 ret = -1;
 327         }
 328
 329         return ret;
 330 }
 331
 332 /*
 333  * Shutdown a wakeup device, counterpart of above method
 334  * 1. Disable _PSW (power state wake)
 335  * 2. Shutdown down the power resources
 336  */
 337 int acpi_disable_wakeup_device_power(struct acpi_device *dev)
 338 {
 339         union acpi_object arg = { ACPI_TYPE_INTEGER };
 340         struct acpi_object_list arg_list = { 1, &arg };
 341         acpi_status status = AE_OK;
 342         int i;
 343         int ret = 0;
 344
 345
 346         if (!dev || !dev->wakeup.flags.valid)
 347                 return -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                 printk(KERN_ERR PREFIX "Evaluate _PSW\n");
 354                 dev->wakeup.flags.valid = 0;
 355                 return -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], dev);
 361                 if (ret) {
 362                         printk(KERN_ERR PREFIX "Transition power state\n");
 363                         dev->wakeup.flags.valid = 0;
 364                         return -1;
 365                 }
 366         }
 367
 368         return ret;
 369 }
 370
 371 /* --------------------------------------------------------------------------
 372                              Device Power Management
 373    -------------------------------------------------------------------------- */
 374
 375 int acpi_power_get_inferred_state(struct acpi_device *device)
 376 {
 377         int result = 0;
 378         struct acpi_handle_list *list = NULL;
 379         int list_state = 0;
 380         int i = 0;
 381
 382
 383         if (!device)
 384                 return -EINVAL;
 385
 386         device->power.state = ACPI_STATE_UNKNOWN;
 387
 388         /*
 389          * We know a device's inferred power state when all the resources
 390          * required for a given D-state are 'on'.
 391          */
 392         for (i = ACPI_STATE_D0; i < ACPI_STATE_D3; i++) {
 393                 list = &device->power.states[i].resources;
 394                 if (list->count < 1)
 395                         continue;
 396
 397                 result = acpi_power_get_list_state(list, &list_state);
 398                 if (result)
 399                         return result;
 400
 401                 if (list_state == ACPI_POWER_RESOURCE_STATE_ON) {
 402                         device->power.state = i;
 403                         return 0;
 404                 }
 405         }
 406
 407         device->power.state = ACPI_STATE_D3;
 408
 409         return 0;
 410 }
 411
 412 int acpi_power_transition(struct acpi_device *device, int state)
 413 {
 414         int result = 0;
 415         struct acpi_handle_list *cl = NULL;     /* Current Resources */
 416         struct acpi_handle_list *tl = NULL;     /* Target Resources */
 417         int i = 0;
 418
 419
 420         if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
 421                 return -EINVAL;
 422
 423         if ((device->power.state < ACPI_STATE_D0)
 424             || (device->power.state > ACPI_STATE_D3))
 425                 return -ENODEV;
 426
 427         cl = &device->power.states[device->power.state].resources;
 428         tl = &device->power.states[state].resources;
 429
 430         if (!cl->count && !tl->count) {
 431                 result = -ENODEV;
 432                 goto end;
 433         }
 434
 435         /* TBD: Resources must be ordered. */
 436
 437         /*
 438          * First we reference all power resources required in the target list
 439          * (e.g. so the device doesn't lose power while transitioning).
 440          */
 441         for (i = 0; i < tl->count; i++) {
 442                 result = acpi_power_on(tl->handles[i], device);
 443                 if (result)
 444                         goto end;
 445         }
 446
 447         if (device->power.state == state) {
 448                 goto end;
 449         }
 450
 451         /*
 452          * Then we dereference all power resources used in the current list.
 453          */
 454         for (i = 0; i < cl->count; i++) {
 455                 result = acpi_power_off_device(cl->handles[i], device);
 456                 if (result)
 457                         goto end;
 458         }
 459
 460      end:
 461         if (result) {
 462                 device->power.state = ACPI_STATE_UNKNOWN;
 463                 printk(KERN_WARNING PREFIX "Transitioning device [%s] to D%d\n",
 464                               device->pnp.bus_id, state);
 465         } else {
 466         /* We shouldn't change the state till all above operations succeed */
 467                 device->power.state = state;
 468         }
 469
 470         return result;
 471 }
 472
 473 /* --------------------------------------------------------------------------
 474                               FS Interface (/proc)
 475    -------------------------------------------------------------------------- */
 476
 477 static struct proc_dir_entry *acpi_power_dir;
 478
 479 static int acpi_power_seq_show(struct seq_file *seq, void *offset)
 480 {
 481         int count = 0;
 482         int result = 0, state;
 483         struct acpi_power_resource *resource = NULL;
 484         struct list_head *node, *next;
 485         struct acpi_power_reference *ref;
 486
 487
 488         resource = seq->private;
 489
 490         if (!resource)
 491                 goto end;
 492
 493         result = acpi_power_get_state(resource, &state);
 494         if (result)
 495                 goto end;
 496
 497         seq_puts(seq, "state:                   ");
 498         switch (state) {
 499         case ACPI_POWER_RESOURCE_STATE_ON:
 500                 seq_puts(seq, "on\n");
 501                 break;
 502         case ACPI_POWER_RESOURCE_STATE_OFF:
 503                 seq_puts(seq, "off\n");
 504                 break;
 505         default:
 506                 seq_puts(seq, "unknown\n");
 507                 break;
 508         }
 509
 510         mutex_lock(&resource->resource_lock);
 511         list_for_each_safe(node, next, &resource->reference) {
 512                 ref = container_of(node, struct acpi_power_reference, node);
 513                 count++;
 514         }
 515         mutex_unlock(&resource->resource_lock);
 516
 517         seq_printf(seq, "system level:            S%d\n"
 518                    "order:                   %d\n"
 519                    "reference count:         %d\n",
 520                    resource->system_level,
 521                    resource->order, count);
 522
 523       end:
 524         return 0;
 525 }
 526
 527 static int acpi_power_open_fs(struct inode *inode, struct file *file)
 528 {
 529         return single_open(file, acpi_power_seq_show, PDE(inode)->data);
 530 }
 531
 532 static int acpi_power_add_fs(struct acpi_device *device)
 533 {
 534         struct proc_dir_entry *entry = NULL;
 535
 536
 537         if (!device)
 538                 return -EINVAL;
 539
 540         if (!acpi_device_dir(device)) {
 541                 acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device),
 542                                                      acpi_power_dir);
 543                 if (!acpi_device_dir(device))
 544                         return -ENODEV;
 545         }
 546
 547         /* 'status' [R] */
 548         entry = create_proc_entry(ACPI_POWER_FILE_STATUS,
 549                                   S_IRUGO, acpi_device_dir(device));
 550         if (!entry)
 551                 return -EIO;
 552         else {
 553                 entry->proc_fops = &acpi_power_fops;
 554                 entry->data = acpi_driver_data(device);
 555         }
 556
 557         return 0;
 558 }
 559
 560 static int acpi_power_remove_fs(struct acpi_device *device)
 561 {
 562
 563         if (acpi_device_dir(device)) {
 564                 remove_proc_entry(ACPI_POWER_FILE_STATUS,
 565                                   acpi_device_dir(device));
 566                 remove_proc_entry(acpi_device_bid(device), acpi_power_dir);
 567                 acpi_device_dir(device) = NULL;
 568         }
 569
 570         return 0;
 571 }
 572
 573 /* --------------------------------------------------------------------------
 574                                 Driver Interface
 575    -------------------------------------------------------------------------- */
 576
 577 static int acpi_power_add(struct acpi_device *device)
 578 {
 579         int result = 0, state;
 580         acpi_status status = AE_OK;
 581         struct acpi_power_resource *resource = NULL;
 582         union acpi_object acpi_object;
 583         struct acpi_buffer buffer = { sizeof(acpi_object), &acpi_object };
 584
 585
 586         if (!device)
 587                 return -EINVAL;
 588
 589         resource = kzalloc(sizeof(struct acpi_power_resource), GFP_KERNEL);
 590         if (!resource)
 591                 return -ENOMEM;
 592
 593         resource->device = device;
 594         mutex_init(&resource->resource_lock);
 595         INIT_LIST_HEAD(&resource->reference);
 596         strcpy(resource->name, device->pnp.bus_id);
 597         strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
 598         strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
 599         acpi_driver_data(device) = resource;
 600
 601         /* Evalute the object to get the system level and resource order. */
 602         status = acpi_evaluate_object(device->handle, NULL, NULL, &buffer);
 603         if (ACPI_FAILURE(status)) {
 604                 result = -ENODEV;
 605                 goto end;
 606         }
 607         resource->system_level = acpi_object.power_resource.system_level;
 608         resource->order = acpi_object.power_resource.resource_order;
 609
 610         result = acpi_power_get_state(resource, &state);
 611         if (result)
 612                 goto end;
 613
 614         switch (state) {
 615         case ACPI_POWER_RESOURCE_STATE_ON:
 616                 device->power.state = ACPI_STATE_D0;
 617                 break;
 618         case ACPI_POWER_RESOURCE_STATE_OFF:
 619                 device->power.state = ACPI_STATE_D3;
 620                 break;
 621         default:
 622                 device->power.state = ACPI_STATE_UNKNOWN;
 623                 break;
 624         }
 625
 626         result = acpi_power_add_fs(device);
 627         if (result)
 628                 goto end;
 629
 630         printk(KERN_INFO PREFIX "%s [%s] (%s)\n", acpi_device_name(device),
 631                acpi_device_bid(device), state ? "on" : "off");
 632
 633       end:
 634         if (result)
 635                 kfree(resource);
 636
 637         return result;
 638 }
 639
 640 static int acpi_power_remove(struct acpi_device *device, int type)
 641 {
 642         struct acpi_power_resource *resource = NULL;
 643         struct list_head *node, *next;
 644
 645
 646         if (!device || !acpi_driver_data(device))
 647                 return -EINVAL;
 648
 649         resource = acpi_driver_data(device);
 650
 651         acpi_power_remove_fs(device);
 652
 653         mutex_lock(&resource->resource_lock);
 654         list_for_each_safe(node, next, &resource->reference) {
 655                 struct acpi_power_reference *ref = container_of(node, struct acpi_power_reference, node);
 656                 list_del(&ref->node);
 657                 kfree(ref);
 658         }
 659         mutex_unlock(&resource->resource_lock);
 660
 661         kfree(resource);
 662
 663         return 0;
 664 }
 665
 666 static int acpi_power_resume(struct acpi_device *device)
 667 {
 668         int result = 0, state;
 669         struct acpi_power_resource *resource = NULL;
 670         struct acpi_power_reference *ref;
 671
 672         if (!device || !acpi_driver_data(device))
 673                 return -EINVAL;
 674
 675         resource = (struct acpi_power_resource *)acpi_driver_data(device);
 676
 677         result = acpi_power_get_state(resource, &state);
 678         if (result)
 679                 return result;
 680
 681         mutex_lock(&resource->resource_lock);
 682         if (state == ACPI_POWER_RESOURCE_STATE_OFF &&
 683             !list_empty(&resource->reference)) {
 684                 ref = container_of(resource->reference.next, struct acpi_power_reference, node);
 685                 mutex_unlock(&resource->resource_lock);
 686                 result = acpi_power_on(device->handle, ref->device);
 687                 return result;
 688         }
 689
 690         mutex_unlock(&resource->resource_lock);
 691         return 0;
 692 }
 693
 694 static int __init acpi_power_init(void)
 695 {
 696         int result = 0;
 697
 698
 699         if (acpi_disabled)
 700                 return 0;
 701
 702         INIT_LIST_HEAD(&acpi_power_resource_list);
 703
 704         acpi_power_dir = proc_mkdir(ACPI_POWER_CLASS, acpi_root_dir);
 705         if (!acpi_power_dir)
 706                 return -ENODEV;
 707
 708         result = acpi_bus_register_driver(&acpi_power_driver);
 709         if (result < 0) {
 710                 remove_proc_entry(ACPI_POWER_CLASS, acpi_root_dir);
 711                 return -ENODEV;
 712         }
 713
 714         return 0;
 715 }
 716
 717 subsys_initcall(acpi_power_init);