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         int state;
  90         struct mutex resource_lock;
  91         struct list_head reference;
  92 };
  93
  94 static struct list_head acpi_power_resource_list;
  95
  96 static const struct file_operations acpi_power_fops = {
  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)
 132 {
 133         acpi_status status = AE_OK;
 134         unsigned long sta = 0;
 135
 136
 137         if (!resource)
 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         if (sta & 0x01)
 145                 resource->state = ACPI_POWER_RESOURCE_STATE_ON;
 146         else
 147                 resource->state = ACPI_POWER_RESOURCE_STATE_OFF;
 148
 149         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] is %s\n",
 150                           resource->name, resource->state ? "on" : "off"));
 151
 152         return 0;
 153 }
 154
 155 static int acpi_power_get_list_state(struct acpi_handle_list *list, int *state)
 156 {
 157         int result = 0;
 158         struct acpi_power_resource *resource = NULL;
 159         u32 i = 0;
 160
 161
 162         if (!list || !state)
 163                 return -EINVAL;
 164
 165         /* The state of the list is 'on' IFF all resources are 'on'. */
 166
 167         for (i = 0; i < list->count; i++) {
 168                 result = acpi_power_get_context(list->handles[i], &resource);
 169                 if (result)
 170                         return result;
 171                 result = acpi_power_get_state(resource);
 172                 if (result)
 173                         return result;
 174
 175                 *state = resource->state;
 176
 177                 if (*state != ACPI_POWER_RESOURCE_STATE_ON)
 178                         break;
 179         }
 180
 181         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource list is %s\n",
 182                           *state ? "on" : "off"));
 183
 184         return result;
 185 }
 186
 187 static int acpi_power_on(acpi_handle handle, struct acpi_device *dev)
 188 {
 189         int result = 0;
 190         int found = 0;
 191         acpi_status status = AE_OK;
 192         struct acpi_power_resource *resource = NULL;
 193         struct list_head *node, *next;
 194         struct acpi_power_reference *ref;
 195
 196
 197         result = acpi_power_get_context(handle, &resource);
 198         if (result)
 199                 return result;
 200
 201         mutex_lock(&resource->resource_lock);
 202         list_for_each_safe(node, next, &resource->reference) {
 203                 ref = container_of(node, struct acpi_power_reference, node);
 204                 if (dev->handle == ref->device->handle) {
 205                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] already referenced by resource [%s]\n",
 206                                   dev->pnp.bus_id, resource->name));
 207                         found = 1;
 208                         break;
 209                 }
 210         }
 211
 212         if (!found) {
 213                 ref = kmalloc(sizeof (struct acpi_power_reference),
 214                     irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL);
 215                 if (!ref) {
 216                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "kmalloc() failed\n"));
 217                         mutex_unlock(&resource->resource_lock);
 218                         return -ENOMEM;
 219                 }
 220                 list_add_tail(&ref->node, &resource->reference);
 221                 ref->device = dev;
 222                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] added to resource [%s] references\n",
 223                           dev->pnp.bus_id, resource->name));
 224         }
 225         mutex_unlock(&resource->resource_lock);
 226
 227         if (resource->state == ACPI_POWER_RESOURCE_STATE_ON) {
 228                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] already on\n",
 229                                   resource->name));
 230                 return 0;
 231         }
 232
 233         status = acpi_evaluate_object(resource->device->handle, "_ON", NULL, NULL);
 234         if (ACPI_FAILURE(status))
 235                 return -ENODEV;
 236
 237         result = acpi_power_get_state(resource);
 238         if (result)
 239                 return result;
 240         if (resource->state != ACPI_POWER_RESOURCE_STATE_ON)
 241                 return -ENOEXEC;
 242
 243         /* Update the power resource's _device_ power state */
 244         resource->device->power.state = ACPI_STATE_D0;
 245
 246         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] turned on\n",
 247                           resource->name));
 248         return 0;
 249 }
 250
 251 static int acpi_power_off_device(acpi_handle handle, struct acpi_device *dev)
 252 {
 253         int result = 0;
 254         acpi_status status = AE_OK;
 255         struct acpi_power_resource *resource = NULL;
 256         struct list_head *node, *next;
 257         struct acpi_power_reference *ref;
 258
 259
 260         result = acpi_power_get_context(handle, &resource);
 261         if (result)
 262                 return result;
 263
 264         mutex_lock(&resource->resource_lock);
 265         list_for_each_safe(node, next, &resource->reference) {
 266                 ref = container_of(node, struct acpi_power_reference, node);
 267                 if (dev->handle == ref->device->handle) {
 268                         list_del(&ref->node);
 269                         kfree(ref);
 270                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] removed from resource [%s] references\n",
 271                             dev->pnp.bus_id, resource->name));
 272                         break;
 273                 }
 274         }
 275
 276         if (!list_empty(&resource->reference)) {
 277                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Cannot turn resource [%s] off - resource is in use\n",
 278                     resource->name));
 279                 mutex_unlock(&resource->resource_lock);
 280                 return 0;
 281         }
 282         mutex_unlock(&resource->resource_lock);
 283
 284         if (resource->state == ACPI_POWER_RESOURCE_STATE_OFF) {
 285                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] already off\n",
 286                                   resource->name));
 287                 return 0;
 288         }
 289
 290         status = acpi_evaluate_object(resource->device->handle, "_OFF", NULL, NULL);
 291         if (ACPI_FAILURE(status))
 292                 return -ENODEV;
 293
 294         result = acpi_power_get_state(resource);
 295         if (result)
 296                 return result;
 297         if (resource->state != ACPI_POWER_RESOURCE_STATE_OFF)
 298                 return -ENOEXEC;
 299
 300         /* Update the power resource's _device_ power state */
 301         resource->device->power.state = ACPI_STATE_D3;
 302
 303         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] turned off\n",
 304                           resource->name));
 305
 306         return 0;
 307 }
 308
 309 /*
 310  * Prepare a wakeup device, two steps (Ref ACPI 2.0:P229):
 311  * 1. Power on the power resources required for the wakeup device
 312  * 2. Enable _PSW (power state wake) for the device if present
 313  */
 314 int acpi_enable_wakeup_device_power(struct acpi_device *dev)
 315 {
 316         union acpi_object arg = { ACPI_TYPE_INTEGER };
 317         struct acpi_object_list arg_list = { 1, &arg };
 318         acpi_status status = AE_OK;
 319         int i;
 320         int ret = 0;
 321
 322         if (!dev || !dev->wakeup.flags.valid)
 323                 return -1;
 324
 325         arg.integer.value = 1;
 326         /* Open power resource */
 327         for (i = 0; i < dev->wakeup.resources.count; i++) {
 328                 ret = acpi_power_on(dev->wakeup.resources.handles[i], dev);
 329                 if (ret) {
 330                         printk(KERN_ERR PREFIX "Transition power state\n");
 331                         dev->wakeup.flags.valid = 0;
 332                         return -1;
 333                 }
 334         }
 335
 336         /* Execute PSW */
 337         status = acpi_evaluate_object(dev->handle, "_PSW", &arg_list, NULL);
 338         if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
 339                 printk(KERN_ERR PREFIX "Evaluate _PSW\n");
 340                 dev->wakeup.flags.valid = 0;
 341                 ret = -1;
 342         }
 343
 344         return ret;
 345 }
 346
 347 /*
 348  * Shutdown a wakeup device, counterpart of above method
 349  * 1. Disable _PSW (power state wake)
 350  * 2. Shutdown down the power resources
 351  */
 352 int acpi_disable_wakeup_device_power(struct acpi_device *dev)
 353 {
 354         union acpi_object arg = { ACPI_TYPE_INTEGER };
 355         struct acpi_object_list arg_list = { 1, &arg };
 356         acpi_status status = AE_OK;
 357         int i;
 358         int ret = 0;
 359
 360
 361         if (!dev || !dev->wakeup.flags.valid)
 362                 return -1;
 363
 364         arg.integer.value = 0;
 365         /* Execute PSW */
 366         status = acpi_evaluate_object(dev->handle, "_PSW", &arg_list, NULL);
 367         if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
 368                 printk(KERN_ERR PREFIX "Evaluate _PSW\n");
 369                 dev->wakeup.flags.valid = 0;
 370                 return -1;
 371         }
 372
 373         /* Close power resource */
 374         for (i = 0; i < dev->wakeup.resources.count; i++) {
 375                 ret = acpi_power_off_device(dev->wakeup.resources.handles[i], dev);
 376                 if (ret) {
 377                         printk(KERN_ERR PREFIX "Transition power state\n");
 378                         dev->wakeup.flags.valid = 0;
 379                         return -1;
 380                 }
 381         }
 382
 383         return ret;
 384 }
 385
 386 /* --------------------------------------------------------------------------
 387                              Device Power Management
 388    -------------------------------------------------------------------------- */
 389
 390 int acpi_power_get_inferred_state(struct acpi_device *device)
 391 {
 392         int result = 0;
 393         struct acpi_handle_list *list = NULL;
 394         int list_state = 0;
 395         int i = 0;
 396
 397
 398         if (!device)
 399                 return -EINVAL;
 400
 401         device->power.state = ACPI_STATE_UNKNOWN;
 402
 403         /*
 404          * We know a device's inferred power state when all the resources
 405          * required for a given D-state are 'on'.
 406          */
 407         for (i = ACPI_STATE_D0; i < ACPI_STATE_D3; i++) {
 408                 list = &device->power.states[i].resources;
 409                 if (list->count < 1)
 410                         continue;
 411
 412                 result = acpi_power_get_list_state(list, &list_state);
 413                 if (result)
 414                         return result;
 415
 416                 if (list_state == ACPI_POWER_RESOURCE_STATE_ON) {
 417                         device->power.state = i;
 418                         return 0;
 419                 }
 420         }
 421
 422         device->power.state = ACPI_STATE_D3;
 423
 424         return 0;
 425 }
 426
 427 int acpi_power_transition(struct acpi_device *device, int state)
 428 {
 429         int result = 0;
 430         struct acpi_handle_list *cl = NULL;     /* Current Resources */
 431         struct acpi_handle_list *tl = NULL;     /* Target Resources */
 432         int i = 0;
 433
 434
 435         if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
 436                 return -EINVAL;
 437
 438         if ((device->power.state < ACPI_STATE_D0)
 439             || (device->power.state > ACPI_STATE_D3))
 440                 return -ENODEV;
 441
 442         cl = &device->power.states[device->power.state].resources;
 443         tl = &device->power.states[state].resources;
 444
 445         if (!cl->count && !tl->count) {
 446                 result = -ENODEV;
 447                 goto end;
 448         }
 449
 450         /* TBD: Resources must be ordered. */
 451
 452         /*
 453          * First we reference all power resources required in the target list
 454          * (e.g. so the device doesn't lose power while transitioning).
 455          */
 456         for (i = 0; i < tl->count; i++) {
 457                 result = acpi_power_on(tl->handles[i], device);
 458                 if (result)
 459                         goto end;
 460         }
 461
 462         if (device->power.state == state) {
 463                 goto end;
 464         }
 465
 466         /*
 467          * Then we dereference all power resources used in the current list.
 468          */
 469         for (i = 0; i < cl->count; i++) {
 470                 result = acpi_power_off_device(cl->handles[i], device);
 471                 if (result)
 472                         goto end;
 473         }
 474
 475      end:
 476         if (result) {
 477                 device->power.state = ACPI_STATE_UNKNOWN;
 478                 printk(KERN_WARNING PREFIX "Transitioning device [%s] to D%d\n",
 479                               device->pnp.bus_id, state);
 480         } else {
 481         /* We shouldn't change the state till all above operations succeed */
 482                 device->power.state = state;
 483         }
 484
 485         return result;
 486 }
 487
 488 /* --------------------------------------------------------------------------
 489                               FS Interface (/proc)
 490    -------------------------------------------------------------------------- */
 491
 492 static struct proc_dir_entry *acpi_power_dir;
 493
 494 static int acpi_power_seq_show(struct seq_file *seq, void *offset)
 495 {
 496         int count = 0;
 497         int result = 0;
 498         struct acpi_power_resource *resource = NULL;
 499         struct list_head *node, *next;
 500         struct acpi_power_reference *ref;
 501
 502
 503         resource = seq->private;
 504
 505         if (!resource)
 506                 goto end;
 507
 508         result = acpi_power_get_state(resource);
 509         if (result)
 510                 goto end;
 511
 512         seq_puts(seq, "state:                   ");
 513         switch (resource->state) {
 514         case ACPI_POWER_RESOURCE_STATE_ON:
 515                 seq_puts(seq, "on\n");
 516                 break;
 517         case ACPI_POWER_RESOURCE_STATE_OFF:
 518                 seq_puts(seq, "off\n");
 519                 break;
 520         default:
 521                 seq_puts(seq, "unknown\n");
 522                 break;
 523         }
 524
 525         mutex_lock(&resource->resource_lock);
 526         list_for_each_safe(node, next, &resource->reference) {
 527                 ref = container_of(node, struct acpi_power_reference, node);
 528                 count++;
 529         }
 530         mutex_unlock(&resource->resource_lock);
 531
 532         seq_printf(seq, "system level:            S%d\n"
 533                    "order:                   %d\n"
 534                    "reference count:         %d\n",
 535                    resource->system_level,
 536                    resource->order, count);
 537
 538       end:
 539         return 0;
 540 }
 541
 542 static int acpi_power_open_fs(struct inode *inode, struct file *file)
 543 {
 544         return single_open(file, acpi_power_seq_show, PDE(inode)->data);
 545 }
 546
 547 static int acpi_power_add_fs(struct acpi_device *device)
 548 {
 549         struct proc_dir_entry *entry = NULL;
 550
 551
 552         if (!device)
 553                 return -EINVAL;
 554
 555         if (!acpi_device_dir(device)) {
 556                 acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device),
 557                                                      acpi_power_dir);
 558                 if (!acpi_device_dir(device))
 559                         return -ENODEV;
 560         }
 561
 562         /* 'status' [R] */
 563         entry = create_proc_entry(ACPI_POWER_FILE_STATUS,
 564                                   S_IRUGO, acpi_device_dir(device));
 565         if (!entry)
 566                 return -EIO;
 567         else {
 568                 entry->proc_fops = &acpi_power_fops;
 569                 entry->data = acpi_driver_data(device);
 570         }
 571
 572         return 0;
 573 }
 574
 575 static int acpi_power_remove_fs(struct acpi_device *device)
 576 {
 577
 578         if (acpi_device_dir(device)) {
 579                 remove_proc_entry(ACPI_POWER_FILE_STATUS,
 580                                   acpi_device_dir(device));
 581                 remove_proc_entry(acpi_device_bid(device), acpi_power_dir);
 582                 acpi_device_dir(device) = NULL;
 583         }
 584
 585         return 0;
 586 }
 587
 588 /* --------------------------------------------------------------------------
 589                                 Driver Interface
 590    -------------------------------------------------------------------------- */
 591
 592 static int acpi_power_add(struct acpi_device *device)
 593 {
 594         int result = 0;
 595         acpi_status status = AE_OK;
 596         struct acpi_power_resource *resource = NULL;
 597         union acpi_object acpi_object;
 598         struct acpi_buffer buffer = { sizeof(acpi_object), &acpi_object };
 599
 600
 601         if (!device)
 602                 return -EINVAL;
 603
 604         resource = kzalloc(sizeof(struct acpi_power_resource), GFP_KERNEL);
 605         if (!resource)
 606                 return -ENOMEM;
 607
 608         resource->device = device;
 609         mutex_init(&resource->resource_lock);
 610         INIT_LIST_HEAD(&resource->reference);
 611         strcpy(resource->name, device->pnp.bus_id);
 612         strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
 613         strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
 614         acpi_driver_data(device) = resource;
 615
 616         /* Evalute the object to get the system level and resource order. */
 617         status = acpi_evaluate_object(device->handle, NULL, NULL, &buffer);
 618         if (ACPI_FAILURE(status)) {
 619                 result = -ENODEV;
 620                 goto end;
 621         }
 622         resource->system_level = acpi_object.power_resource.system_level;
 623         resource->order = acpi_object.power_resource.resource_order;
 624
 625         result = acpi_power_get_state(resource);
 626         if (result)
 627                 goto end;
 628
 629         switch (resource->state) {
 630         case ACPI_POWER_RESOURCE_STATE_ON:
 631                 device->power.state = ACPI_STATE_D0;
 632                 break;
 633         case ACPI_POWER_RESOURCE_STATE_OFF:
 634                 device->power.state = ACPI_STATE_D3;
 635                 break;
 636         default:
 637                 device->power.state = ACPI_STATE_UNKNOWN;
 638                 break;
 639         }
 640
 641         result = acpi_power_add_fs(device);
 642         if (result)
 643                 goto end;
 644
 645         printk(KERN_INFO PREFIX "%s [%s] (%s)\n", acpi_device_name(device),
 646                acpi_device_bid(device), resource->state ? "on" : "off");
 647
 648       end:
 649         if (result)
 650                 kfree(resource);
 651
 652         return result;
 653 }
 654
 655 static int acpi_power_remove(struct acpi_device *device, int type)
 656 {
 657         struct acpi_power_resource *resource = NULL;
 658         struct list_head *node, *next;
 659
 660
 661         if (!device || !acpi_driver_data(device))
 662                 return -EINVAL;
 663
 664         resource = acpi_driver_data(device);
 665
 666         acpi_power_remove_fs(device);
 667
 668         mutex_lock(&resource->resource_lock);
 669         list_for_each_safe(node, next, &resource->reference) {
 670                 struct acpi_power_reference *ref = container_of(node, struct acpi_power_reference, node);
 671                 list_del(&ref->node);
 672                 kfree(ref);
 673         }
 674         mutex_unlock(&resource->resource_lock);
 675
 676         kfree(resource);
 677
 678         return 0;
 679 }
 680
 681 static int acpi_power_resume(struct acpi_device *device)
 682 {
 683         int result = 0;
 684         struct acpi_power_resource *resource = NULL;
 685         struct acpi_power_reference *ref;
 686
 687         if (!device || !acpi_driver_data(device))
 688                 return -EINVAL;
 689
 690         resource = (struct acpi_power_resource *)acpi_driver_data(device);
 691
 692         result = acpi_power_get_state(resource);
 693         if (result)
 694                 return result;
 695
 696         mutex_lock(&resource->resource_lock);
 697         if ((resource->state == ACPI_POWER_RESOURCE_STATE_OFF) &&
 698             !list_empty(&resource->reference)) {
 699                 ref = container_of(resource->reference.next, struct acpi_power_reference, node);
 700                 mutex_unlock(&resource->resource_lock);
 701                 result = acpi_power_on(device->handle, ref->device);
 702                 return result;
 703         }
 704
 705         mutex_unlock(&resource->resource_lock);
 706         return 0;
 707 }
 708
 709 static int __init acpi_power_init(void)
 710 {
 711         int result = 0;
 712
 713
 714         if (acpi_disabled)
 715                 return 0;
 716
 717         INIT_LIST_HEAD(&acpi_power_resource_list);
 718
 719         acpi_power_dir = proc_mkdir(ACPI_POWER_CLASS, acpi_root_dir);
 720         if (!acpi_power_dir)
 721                 return -ENODEV;
 722
 723         result = acpi_bus_register_driver(&acpi_power_driver);
 724         if (result < 0) {
 725                 remove_proc_entry(ACPI_POWER_CLASS, acpi_root_dir);
 726                 return -ENODEV;
 727         }
 728
 729         return 0;
 730 }
 731
 732 subsys_initcall(acpi_power_init);