drivers/acpi/device_pm.c

   1 /*
   2  * drivers/acpi/device_pm.c - ACPI device power management routines.
   3  *
   4  * Copyright (C) 2012, Intel Corp.
   5  * Author: Rafael J. Wysocki <rafael.j.wysocki@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 version 2 as published
  11  *  by the Free Software Foundation.
  12  *
  13  *  This program is distributed in the hope that it will be useful, but
  14  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  *  General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License along
  19  *  with this program; if not, write to the Free Software Foundation, Inc.,
  20  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  21  *
  22  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  23  */
  24
  25 #include <linux/device.h>
  26 #include <linux/export.h>
  27 #include <linux/mutex.h>
  28 #include <linux/pm_qos.h>
  29 #include <linux/pm_runtime.h>
  30
  31 #include <acpi/acpi.h>
  32 #include <acpi/acpi_bus.h>
  33
  34 static DEFINE_MUTEX(acpi_pm_notifier_lock);
  35
  36 /**
  37  * acpi_add_pm_notifier - Register PM notifier for given ACPI device.
  38  * @adev: ACPI device to add the notifier for.
  39  * @context: Context information to pass to the notifier routine.
  40  *
  41  * NOTE: @adev need not be a run-wake or wakeup device to be a valid source of
  42  * PM wakeup events.  For example, wakeup events may be generated for bridges
  43  * if one of the devices below the bridge is signaling wakeup, even if the
  44  * bridge itself doesn't have a wakeup GPE associated with it.
  45  */
  46 acpi_status acpi_add_pm_notifier(struct acpi_device *adev,
  47                                  acpi_notify_handler handler, void *context)
  48 {
  49         acpi_status status = AE_ALREADY_EXISTS;
  50
  51         mutex_lock(&acpi_pm_notifier_lock);
  52
  53         if (adev->wakeup.flags.notifier_present)
  54                 goto out;
  55
  56         status = acpi_install_notify_handler(adev->handle,
  57                                              ACPI_SYSTEM_NOTIFY,
  58                                              handler, context);
  59         if (ACPI_FAILURE(status))
  60                 goto out;
  61
  62         adev->wakeup.flags.notifier_present = true;
  63
  64  out:
  65         mutex_unlock(&acpi_pm_notifier_lock);
  66         return status;
  67 }
  68
  69 /**
  70  * acpi_remove_pm_notifier - Unregister PM notifier from given ACPI device.
  71  * @adev: ACPI device to remove the notifier from.
  72  */
  73 acpi_status acpi_remove_pm_notifier(struct acpi_device *adev,
  74                                     acpi_notify_handler handler)
  75 {
  76         acpi_status status = AE_BAD_PARAMETER;
  77
  78         mutex_lock(&acpi_pm_notifier_lock);
  79
  80         if (!adev->wakeup.flags.notifier_present)
  81                 goto out;
  82
  83         status = acpi_remove_notify_handler(adev->handle,
  84                                             ACPI_SYSTEM_NOTIFY,
  85                                             handler);
  86         if (ACPI_FAILURE(status))
  87                 goto out;
  88
  89         adev->wakeup.flags.notifier_present = false;
  90
  91  out:
  92         mutex_unlock(&acpi_pm_notifier_lock);
  93         return status;
  94 }
  95
  96 /**
  97  * acpi_device_power_state - Get preferred power state of ACPI device.
  98  * @dev: Device whose preferred target power state to return.
  99  * @adev: ACPI device node corresponding to @dev.
 100  * @target_state: System state to match the resultant device state.
 101  * @d_max_in: Deepest low-power state to take into consideration.
 102  * @d_min_p: Location to store the upper limit of the allowed states range.
 103  * Return value: Preferred power state of the device on success, -ENODEV
 104  * (if there's no 'struct acpi_device' for @dev) or -EINVAL on failure
 105  *
 106  * Find the lowest power (highest number) ACPI device power state that the
 107  * device can be in while the system is in the state represented by
 108  * @target_state.  If @d_min_p is set, the highest power (lowest number) device
 109  * power state that @dev can be in for the given system sleep state is stored
 110  * at the location pointed to by it.
 111  *
 112  * Callers must ensure that @dev and @adev are valid pointers and that @adev
 113  * actually corresponds to @dev before using this function.
 114  */
 115 int acpi_device_power_state(struct device *dev, struct acpi_device *adev,
 116                             u32 target_state, int d_max_in, int *d_min_p)
 117 {
 118         char acpi_method[] = "_SxD";
 119         unsigned long long d_min, d_max;
 120         bool wakeup = false;
 121
 122         if (d_max_in < ACPI_STATE_D0 || d_max_in > ACPI_STATE_D3)
 123                 return -EINVAL;
 124
 125         if (d_max_in > ACPI_STATE_D3_HOT) {
 126                 enum pm_qos_flags_status stat;
 127
 128                 stat = dev_pm_qos_flags(dev, PM_QOS_FLAG_NO_POWER_OFF);
 129                 if (stat == PM_QOS_FLAGS_ALL)
 130                         d_max_in = ACPI_STATE_D3_HOT;
 131         }
 132
 133         acpi_method[2] = '0' + target_state;
 134         /*
 135          * If the sleep state is S0, the lowest limit from ACPI is D3,
 136          * but if the device has _S0W, we will use the value from _S0W
 137          * as the lowest limit from ACPI.  Finally, we will constrain
 138          * the lowest limit with the specified one.
 139          */
 140         d_min = ACPI_STATE_D0;
 141         d_max = ACPI_STATE_D3;
 142
 143         /*
 144          * If present, _SxD methods return the minimum D-state (highest power
 145          * state) we can use for the corresponding S-states.  Otherwise, the
 146          * minimum D-state is D0 (ACPI 3.x).
 147          *
 148          * NOTE: We rely on acpi_evaluate_integer() not clobbering the integer
 149          * provided -- that's our fault recovery, we ignore retval.
 150          */
 151         if (target_state > ACPI_STATE_S0) {
 152                 acpi_evaluate_integer(adev->handle, acpi_method, NULL, &d_min);
 153                 wakeup = device_may_wakeup(dev) && adev->wakeup.flags.valid
 154                         && adev->wakeup.sleep_state >= target_state;
 155         } else if (dev_pm_qos_flags(dev, PM_QOS_FLAG_REMOTE_WAKEUP) !=
 156                         PM_QOS_FLAGS_NONE) {
 157                 wakeup = adev->wakeup.flags.valid;
 158         }
 159
 160         /*
 161          * If _PRW says we can wake up the system from the target sleep state,
 162          * the D-state returned by _SxD is sufficient for that (we assume a
 163          * wakeup-aware driver if wake is set).  Still, if _SxW exists
 164          * (ACPI 3.x), it should return the maximum (lowest power) D-state that
 165          * can wake the system.  _S0W may be valid, too.
 166          */
 167         if (wakeup) {
 168                 acpi_status status;
 169
 170                 acpi_method[3] = 'W';
 171                 status = acpi_evaluate_integer(adev->handle, acpi_method, NULL,
 172                                                 &d_max);
 173                 if (ACPI_FAILURE(status)) {
 174                         if (target_state != ACPI_STATE_S0 ||
 175                             status != AE_NOT_FOUND)
 176                                 d_max = d_min;
 177                 } else if (d_max < d_min) {
 178                         /* Warn the user of the broken DSDT */
 179                         printk(KERN_WARNING "ACPI: Wrong value from %s\n",
 180                                 acpi_method);
 181                         /* Sanitize it */
 182                         d_min = d_max;
 183                 }
 184         }
 185
 186         if (d_max_in < d_min)
 187                 return -EINVAL;
 188         if (d_min_p)
 189                 *d_min_p = d_min;
 190         /* constrain d_max with specified lowest limit (max number) */
 191         if (d_max > d_max_in) {
 192                 for (d_max = d_max_in; d_max > d_min; d_max--) {
 193                         if (adev->power.states[d_max].flags.valid)
 194                                 break;
 195                 }
 196         }
 197         return d_max;
 198 }
 199 EXPORT_SYMBOL_GPL(acpi_device_power_state);
 200
 201 /**
 202  * acpi_pm_device_sleep_state - Get preferred power state of ACPI device.
 203  * @dev: Device whose preferred target power state to return.
 204  * @d_min_p: Location to store the upper limit of the allowed states range.
 205  * @d_max_in: Deepest low-power state to take into consideration.
 206  * Return value: Preferred power state of the device on success, -ENODEV
 207  * (if there's no 'struct acpi_device' for @dev) or -EINVAL on failure
 208  *
 209  * The caller must ensure that @dev is valid before using this function.
 210  */
 211 int acpi_pm_device_sleep_state(struct device *dev, int *d_min_p, int d_max_in)
 212 {
 213         acpi_handle handle = DEVICE_ACPI_HANDLE(dev);
 214         struct acpi_device *adev;
 215
 216         if (!handle || ACPI_FAILURE(acpi_bus_get_device(handle, &adev))) {
 217                 dev_dbg(dev, "ACPI handle without context in %s!\n", __func__);
 218                 return -ENODEV;
 219         }
 220
 221         return acpi_device_power_state(dev, adev, acpi_target_system_state(),
 222                                        d_max_in, d_min_p);
 223 }
 224 EXPORT_SYMBOL(acpi_pm_device_sleep_state);
 225
 226 #ifdef CONFIG_PM_RUNTIME
 227 /**
 228  * acpi_wakeup_device - Wakeup notification handler for ACPI devices.
 229  * @handle: ACPI handle of the device the notification is for.
 230  * @event: Type of the signaled event.
 231  * @context: Device corresponding to @handle.
 232  */
 233 static void acpi_wakeup_device(acpi_handle handle, u32 event, void *context)
 234 {
 235         struct device *dev = context;
 236
 237         if (event == ACPI_NOTIFY_DEVICE_WAKE && dev) {
 238                 pm_wakeup_event(dev, 0);
 239                 pm_runtime_resume(dev);
 240         }
 241 }
 242
 243 /**
 244  * __acpi_device_run_wake - Enable/disable runtime remote wakeup for device.
 245  * @adev: ACPI device to enable/disable the remote wakeup for.
 246  * @enable: Whether to enable or disable the wakeup functionality.
 247  *
 248  * Enable/disable the GPE associated with @adev so that it can generate
 249  * wakeup signals for the device in response to external (remote) events and
 250  * enable/disable device wakeup power.
 251  *
 252  * Callers must ensure that @adev is a valid ACPI device node before executing
 253  * this function.
 254  */
 255 int __acpi_device_run_wake(struct acpi_device *adev, bool enable)
 256 {
 257         struct acpi_device_wakeup *wakeup = &adev->wakeup;
 258
 259         if (enable) {
 260                 acpi_status res;
 261                 int error;
 262
 263                 error = acpi_enable_wakeup_device_power(adev, ACPI_STATE_S0);
 264                 if (error)
 265                         return error;
 266
 267                 res = acpi_enable_gpe(wakeup->gpe_device, wakeup->gpe_number);
 268                 if (ACPI_FAILURE(res)) {
 269                         acpi_disable_wakeup_device_power(adev);
 270                         return -EIO;
 271                 }
 272         } else {
 273                 acpi_disable_gpe(wakeup->gpe_device, wakeup->gpe_number);
 274                 acpi_disable_wakeup_device_power(adev);
 275         }
 276         return 0;
 277 }
 278
 279 /**
 280  * acpi_pm_device_run_wake - Enable/disable remote wakeup for given device.
 281  * @dev: Device to enable/disable the platform to wake up.
 282  * @enable: Whether to enable or disable the wakeup functionality.
 283  */
 284 int acpi_pm_device_run_wake(struct device *phys_dev, bool enable)
 285 {
 286         struct acpi_device *adev;
 287         acpi_handle handle;
 288
 289         if (!device_run_wake(phys_dev))
 290                 return -EINVAL;
 291
 292         handle = DEVICE_ACPI_HANDLE(phys_dev);
 293         if (!handle || ACPI_FAILURE(acpi_bus_get_device(handle, &adev))) {
 294                 dev_dbg(phys_dev, "ACPI handle without context in %s!\n",
 295                         __func__);
 296                 return -ENODEV;
 297         }
 298
 299         return __acpi_device_run_wake(adev, enable);
 300 }
 301 EXPORT_SYMBOL(acpi_pm_device_run_wake);
 302 #else
 303 static inline void acpi_wakeup_device(acpi_handle handle, u32 event,
 304                                       void *context) {}
 305 #endif /* CONFIG_PM_RUNTIME */
 306
 307  #ifdef CONFIG_PM_SLEEP
 308 /**
 309  * __acpi_device_sleep_wake - Enable or disable device to wake up the system.
 310  * @dev: Device to enable/desible to wake up the system.
 311  * @target_state: System state the device is supposed to wake up from.
 312  * @enable: Whether to enable or disable @dev to wake up the system.
 313  */
 314 int __acpi_device_sleep_wake(struct acpi_device *adev, u32 target_state,
 315                              bool enable)
 316 {
 317         return enable ?
 318                 acpi_enable_wakeup_device_power(adev, target_state) :
 319                 acpi_disable_wakeup_device_power(adev);
 320 }
 321
 322 /**
 323  * acpi_pm_device_sleep_wake - Enable or disable device to wake up the system.
 324  * @dev: Device to enable/desible to wake up the system from sleep states.
 325  * @enable: Whether to enable or disable @dev to wake up the system.
 326  */
 327 int acpi_pm_device_sleep_wake(struct device *dev, bool enable)
 328 {
 329         acpi_handle handle;
 330         struct acpi_device *adev;
 331         int error;
 332
 333         if (!device_can_wakeup(dev))
 334                 return -EINVAL;
 335
 336         handle = DEVICE_ACPI_HANDLE(dev);
 337         if (!handle || ACPI_FAILURE(acpi_bus_get_device(handle, &adev))) {
 338                 dev_dbg(dev, "ACPI handle without context in %s!\n", __func__);
 339                 return -ENODEV;
 340         }
 341
 342         error = __acpi_device_sleep_wake(adev, acpi_target_system_state(),
 343                                          enable);
 344         if (!error)
 345                 dev_info(dev, "System wakeup %s by ACPI\n",
 346                                 enable ? "enabled" : "disabled");
 347
 348         return error;
 349 }
 350 #endif /* CONFIG_PM_SLEEP */
 351
 352 /**
 353  * acpi_dev_pm_get_node - Get ACPI device node for the given physical device.
 354  * @dev: Device to get the ACPI node for.
 355  */
 356 static struct acpi_device *acpi_dev_pm_get_node(struct device *dev)
 357 {
 358         acpi_handle handle = DEVICE_ACPI_HANDLE(dev);
 359         struct acpi_device *adev;
 360
 361         return handle && !acpi_bus_get_device(handle, &adev) ? adev : NULL;
 362 }
 363
 364 /**
 365  * acpi_dev_pm_low_power - Put ACPI device into a low-power state.
 366  * @dev: Device to put into a low-power state.
 367  * @adev: ACPI device node corresponding to @dev.
 368  * @system_state: System state to choose the device state for.
 369  */
 370 static int acpi_dev_pm_low_power(struct device *dev, struct acpi_device *adev,
 371                                  u32 system_state)
 372 {
 373         int power_state;
 374
 375         if (!acpi_device_power_manageable(adev))
 376                 return 0;
 377
 378         power_state = acpi_device_power_state(dev, adev, system_state,
 379                                               ACPI_STATE_D3, NULL);
 380         if (power_state < ACPI_STATE_D0 || power_state > ACPI_STATE_D3)
 381                 return -EIO;
 382
 383         return acpi_device_set_power(adev, power_state);
 384 }
 385
 386 /**
 387  * acpi_dev_pm_full_power - Put ACPI device into the full-power state.
 388  * @adev: ACPI device node to put into the full-power state.
 389  */
 390 static int acpi_dev_pm_full_power(struct acpi_device *adev)
 391 {
 392         return acpi_device_power_manageable(adev) ?
 393                 acpi_device_set_power(adev, ACPI_STATE_D0) : 0;
 394 }
 395
 396 #ifdef CONFIG_PM_RUNTIME
 397 /**
 398  * acpi_dev_runtime_suspend - Put device into a low-power state using ACPI.
 399  * @dev: Device to put into a low-power state.
 400  *
 401  * Put the given device into a runtime low-power state using the standard ACPI
 402  * mechanism.  Set up remote wakeup if desired, choose the state to put the
 403  * device into (this checks if remote wakeup is expected to work too), and set
 404  * the power state of the device.
 405  */
 406 int acpi_dev_runtime_suspend(struct device *dev)
 407 {
 408         struct acpi_device *adev = acpi_dev_pm_get_node(dev);
 409         bool remote_wakeup;
 410         int error;
 411
 412         if (!adev)
 413                 return 0;
 414
 415         remote_wakeup = dev_pm_qos_flags(dev, PM_QOS_FLAG_REMOTE_WAKEUP) >
 416                                 PM_QOS_FLAGS_NONE;
 417         error = __acpi_device_run_wake(adev, remote_wakeup);
 418         if (remote_wakeup && error)
 419                 return -EAGAIN;
 420
 421         error = acpi_dev_pm_low_power(dev, adev, ACPI_STATE_S0);
 422         if (error)
 423                 __acpi_device_run_wake(adev, false);
 424
 425         return error;
 426 }
 427 EXPORT_SYMBOL_GPL(acpi_dev_runtime_suspend);
 428
 429 /**
 430  * acpi_dev_runtime_resume - Put device into the full-power state using ACPI.
 431  * @dev: Device to put into the full-power state.
 432  *
 433  * Put the given device into the full-power state using the standard ACPI
 434  * mechanism at run time.  Set the power state of the device to ACPI D0 and
 435  * disable remote wakeup.
 436  */
 437 int acpi_dev_runtime_resume(struct device *dev)
 438 {
 439         struct acpi_device *adev = acpi_dev_pm_get_node(dev);
 440         int error;
 441
 442         if (!adev)
 443                 return 0;
 444
 445         error = acpi_dev_pm_full_power(adev);
 446         __acpi_device_run_wake(adev, false);
 447         return error;
 448 }
 449 EXPORT_SYMBOL_GPL(acpi_dev_runtime_resume);
 450
 451 /**
 452  * acpi_subsys_runtime_suspend - Suspend device using ACPI.
 453  * @dev: Device to suspend.
 454  *
 455  * Carry out the generic runtime suspend procedure for @dev and use ACPI to put
 456  * it into a runtime low-power state.
 457  */
 458 int acpi_subsys_runtime_suspend(struct device *dev)
 459 {
 460         int ret = pm_generic_runtime_suspend(dev);
 461         return ret ? ret : acpi_dev_runtime_suspend(dev);
 462 }
 463 EXPORT_SYMBOL_GPL(acpi_subsys_runtime_suspend);
 464
 465 /**
 466  * acpi_subsys_runtime_resume - Resume device using ACPI.
 467  * @dev: Device to Resume.
 468  *
 469  * Use ACPI to put the given device into the full-power state and carry out the
 470  * generic runtime resume procedure for it.
 471  */
 472 int acpi_subsys_runtime_resume(struct device *dev)
 473 {
 474         int ret = acpi_dev_runtime_resume(dev);
 475         return ret ? ret : pm_generic_runtime_resume(dev);
 476 }
 477 EXPORT_SYMBOL_GPL(acpi_subsys_runtime_resume);
 478 #endif /* CONFIG_PM_RUNTIME */
 479
 480 #ifdef CONFIG_PM_SLEEP
 481 /**
 482  * acpi_dev_suspend_late - Put device into a low-power state using ACPI.
 483  * @dev: Device to put into a low-power state.
 484  *
 485  * Put the given device into a low-power state during system transition to a
 486  * sleep state using the standard ACPI mechanism.  Set up system wakeup if
 487  * desired, choose the state to put the device into (this checks if system
 488  * wakeup is expected to work too), and set the power state of the device.
 489  */
 490 int acpi_dev_suspend_late(struct device *dev)
 491 {
 492         struct acpi_device *adev = acpi_dev_pm_get_node(dev);
 493         u32 target_state;
 494         bool wakeup;
 495         int error;
 496
 497         if (!adev)
 498                 return 0;
 499
 500         target_state = acpi_target_system_state();
 501         wakeup = device_may_wakeup(dev);
 502         error = __acpi_device_sleep_wake(adev, target_state, wakeup);
 503         if (wakeup && error)
 504                 return error;
 505
 506         error = acpi_dev_pm_low_power(dev, adev, target_state);
 507         if (error)
 508                 __acpi_device_sleep_wake(adev, ACPI_STATE_UNKNOWN, false);
 509
 510         return error;
 511 }
 512 EXPORT_SYMBOL_GPL(acpi_dev_suspend_late);
 513
 514 /**
 515  * acpi_dev_resume_early - Put device into the full-power state using ACPI.
 516  * @dev: Device to put into the full-power state.
 517  *
 518  * Put the given device into the full-power state using the standard ACPI
 519  * mechanism during system transition to the working state.  Set the power
 520  * state of the device to ACPI D0 and disable remote wakeup.
 521  */
 522 int acpi_dev_resume_early(struct device *dev)
 523 {
 524         struct acpi_device *adev = acpi_dev_pm_get_node(dev);
 525         int error;
 526
 527         if (!adev)
 528                 return 0;
 529
 530         error = acpi_dev_pm_full_power(adev);
 531         __acpi_device_sleep_wake(adev, ACPI_STATE_UNKNOWN, false);
 532         return error;
 533 }
 534 EXPORT_SYMBOL_GPL(acpi_dev_resume_early);
 535
 536 /**
 537  * acpi_subsys_prepare - Prepare device for system transition to a sleep state.
 538  * @dev: Device to prepare.
 539  */
 540 int acpi_subsys_prepare(struct device *dev)
 541 {
 542         /*
 543          * Follow PCI and resume devices suspended at run time before running
 544          * their system suspend callbacks.
 545          */
 546         pm_runtime_resume(dev);
 547         return pm_generic_prepare(dev);
 548 }
 549 EXPORT_SYMBOL_GPL(acpi_subsys_prepare);
 550
 551 /**
 552  * acpi_subsys_suspend_late - Suspend device using ACPI.
 553  * @dev: Device to suspend.
 554  *
 555  * Carry out the generic late suspend procedure for @dev and use ACPI to put
 556  * it into a low-power state during system transition into a sleep state.
 557  */
 558 int acpi_subsys_suspend_late(struct device *dev)
 559 {
 560         int ret = pm_generic_suspend_late(dev);
 561         return ret ? ret : acpi_dev_suspend_late(dev);
 562 }
 563 EXPORT_SYMBOL_GPL(acpi_subsys_suspend_late);
 564
 565 /**
 566  * acpi_subsys_resume_early - Resume device using ACPI.
 567  * @dev: Device to Resume.
 568  *
 569  * Use ACPI to put the given device into the full-power state and carry out the
 570  * generic early resume procedure for it during system transition into the
 571  * working state.
 572  */
 573 int acpi_subsys_resume_early(struct device *dev)
 574 {
 575         int ret = acpi_dev_resume_early(dev);
 576         return ret ? ret : pm_generic_resume_early(dev);
 577 }
 578 EXPORT_SYMBOL_GPL(acpi_subsys_resume_early);
 579 #endif /* CONFIG_PM_SLEEP */
 580
 581 static struct dev_pm_domain acpi_general_pm_domain = {
 582         .ops = {
 583 #ifdef CONFIG_PM_RUNTIME
 584                 .runtime_suspend = acpi_subsys_runtime_suspend,
 585                 .runtime_resume = acpi_subsys_runtime_resume,
 586                 .runtime_idle = pm_generic_runtime_idle,
 587 #endif
 588 #ifdef CONFIG_PM_SLEEP
 589                 .prepare = acpi_subsys_prepare,
 590                 .suspend_late = acpi_subsys_suspend_late,
 591                 .resume_early = acpi_subsys_resume_early,
 592                 .poweroff_late = acpi_subsys_suspend_late,
 593                 .restore_early = acpi_subsys_resume_early,
 594 #endif
 595         },
 596 };
 597
 598 /**
 599  * acpi_dev_pm_attach - Prepare device for ACPI power management.
 600  * @dev: Device to prepare.
 601  * @power_on: Whether or not to power on the device.
 602  *
 603  * If @dev has a valid ACPI handle that has a valid struct acpi_device object
 604  * attached to it, install a wakeup notification handler for the device and
 605  * add it to the general ACPI PM domain.  If @power_on is set, the device will
 606  * be put into the ACPI D0 state before the function returns.
 607  *
 608  * This assumes that the @dev's bus type uses generic power management callbacks
 609  * (or doesn't use any power management callbacks at all).
 610  *
 611  * Callers must ensure proper synchronization of this function with power
 612  * management callbacks.
 613  */
 614 int acpi_dev_pm_attach(struct device *dev, bool power_on)
 615 {
 616         struct acpi_device *adev = acpi_dev_pm_get_node(dev);
 617
 618         if (!adev)
 619                 return -ENODEV;
 620
 621         if (dev->pm_domain)
 622                 return -EEXIST;
 623
 624         acpi_add_pm_notifier(adev, acpi_wakeup_device, dev);
 625         dev->pm_domain = &acpi_general_pm_domain;
 626         if (power_on) {
 627                 acpi_dev_pm_full_power(adev);
 628                 __acpi_device_run_wake(adev, false);
 629         }
 630         return 0;
 631 }
 632 EXPORT_SYMBOL_GPL(acpi_dev_pm_attach);
 633
 634 /**
 635  * acpi_dev_pm_detach - Remove ACPI power management from the device.
 636  * @dev: Device to take care of.
 637  * @power_off: Whether or not to try to remove power from the device.
 638  *
 639  * Remove the device from the general ACPI PM domain and remove its wakeup
 640  * notifier.  If @power_off is set, additionally remove power from the device if
 641  * possible.
 642  *
 643  * Callers must ensure proper synchronization of this function with power
 644  * management callbacks.
 645  */
 646 void acpi_dev_pm_detach(struct device *dev, bool power_off)
 647 {
 648         struct acpi_device *adev = acpi_dev_pm_get_node(dev);
 649
 650         if (adev && dev->pm_domain == &acpi_general_pm_domain) {
 651                 dev->pm_domain = NULL;
 652                 acpi_remove_pm_notifier(adev, acpi_wakeup_device);
 653                 if (power_off) {
 654                         /*
 655                          * If the device's PM QoS resume latency limit or flags
 656                          * have been exposed to user space, they have to be
 657                          * hidden at this point, so that they don't affect the
 658                          * choice of the low-power state to put the device into.
 659                          */
 660                         dev_pm_qos_hide_latency_limit(dev);
 661                         dev_pm_qos_hide_flags(dev);
 662                         __acpi_device_run_wake(adev, false);
 663                         acpi_dev_pm_low_power(dev, adev, ACPI_STATE_S0);
 664                 }
 665         }
 666 }
 667 EXPORT_SYMBOL_GPL(acpi_dev_pm_detach);