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   1 /*
   2  * drivers/base/power/main.c - Where the driver meets power management.
   3  *
   4  * Copyright (c) 2003 Patrick Mochel
   5  * Copyright (c) 2003 Open Source Development Lab
   6  *
   7  * This file is released under the GPLv2
   8  *
   9  *
  10  * The driver model core calls device_pm_add() when a device is registered.
  11  * This will intialize the embedded device_pm_info object in the device
  12  * and add it to the list of power-controlled devices. sysfs entries for
  13  * controlling device power management will also be added.
  14  *
  15  * A separate list is used for keeping track of power info, because the power
  16  * domain dependencies may differ from the ancestral dependencies that the
  17  * subsystem list maintains.
  18  */
  19
  20 #include <linux/device.h>
  21 #include <linux/kallsyms.h>
  22 #include <linux/mutex.h>
  23 #include <linux/pm.h>
  24 #include <linux/resume-trace.h>
  25 #include <linux/rwsem.h>
  26 #include <linux/interrupt.h>
  27
  28 #include "../base.h"
  29 #include "power.h"
  30
  31 /*
  32  * The entries in the dpm_list list are in a depth first order, simply
  33  * because children are guaranteed to be discovered after parents, and
  34  * are inserted at the back of the list on discovery.
  35  *
  36  * Since device_pm_add() may be called with a device semaphore held,
  37  * we must never try to acquire a device semaphore while holding
  38  * dpm_list_mutex.
  39  */
  40
  41 LIST_HEAD(dpm_list);
  42
  43 static DEFINE_MUTEX(dpm_list_mtx);
  44
  45 /*
  46  * Set once the preparation of devices for a PM transition has started, reset
  47  * before starting to resume devices.  Protected by dpm_list_mtx.
  48  */
  49 static bool transition_started;
  50
  51 /**
  52  *      device_pm_lock - lock the list of active devices used by the PM core
  53  */
  54 void device_pm_lock(void)
  55 {
  56         mutex_lock(&dpm_list_mtx);
  57 }
  58
  59 /**
  60  *      device_pm_unlock - unlock the list of active devices used by the PM core
  61  */
  62 void device_pm_unlock(void)
  63 {
  64         mutex_unlock(&dpm_list_mtx);
  65 }
  66
  67 /**
  68  *      device_pm_add - add a device to the list of active devices
  69  *      @dev:   Device to be added to the list
  70  */
  71 void device_pm_add(struct device *dev)
  72 {
  73         pr_debug("PM: Adding info for %s:%s\n",
  74                  dev->bus ? dev->bus->name : "No Bus",
  75                  kobject_name(&dev->kobj));
  76         mutex_lock(&dpm_list_mtx);
  77         if (dev->parent) {
  78                 if (dev->parent->power.status >= DPM_SUSPENDING)
  79                         dev_warn(dev, "parent %s should not be sleeping\n",
  80                                  dev_name(dev->parent));
  81         } else if (transition_started) {
  82                 /*
  83                  * We refuse to register parentless devices while a PM
  84                  * transition is in progress in order to avoid leaving them
  85                  * unhandled down the road
  86                  */
  87                 dev_WARN(dev, "Parentless device registered during a PM transaction\n");
  88         }
  89
  90         list_add_tail(&dev->power.entry, &dpm_list);
  91         mutex_unlock(&dpm_list_mtx);
  92 }
  93
  94 /**
  95  *      device_pm_remove - remove a device from the list of active devices
  96  *      @dev:   Device to be removed from the list
  97  *
  98  *      This function also removes the device's PM-related sysfs attributes.
  99  */
 100 void device_pm_remove(struct device *dev)
 101 {
 102         pr_debug("PM: Removing info for %s:%s\n",
 103                  dev->bus ? dev->bus->name : "No Bus",
 104                  kobject_name(&dev->kobj));
 105         mutex_lock(&dpm_list_mtx);
 106         list_del_init(&dev->power.entry);
 107         mutex_unlock(&dpm_list_mtx);
 108 }
 109
 110 /**
 111  *      device_pm_move_before - move device in dpm_list
 112  *      @deva:  Device to move in dpm_list
 113  *      @devb:  Device @deva should come before
 114  */
 115 void device_pm_move_before(struct device *deva, struct device *devb)
 116 {
 117         pr_debug("PM: Moving %s:%s before %s:%s\n",
 118                  deva->bus ? deva->bus->name : "No Bus",
 119                  kobject_name(&deva->kobj),
 120                  devb->bus ? devb->bus->name : "No Bus",
 121                  kobject_name(&devb->kobj));
 122         /* Delete deva from dpm_list and reinsert before devb. */
 123         list_move_tail(&deva->power.entry, &devb->power.entry);
 124 }
 125
 126 /**
 127  *      device_pm_move_after - move device in dpm_list
 128  *      @deva:  Device to move in dpm_list
 129  *      @devb:  Device @deva should come after
 130  */
 131 void device_pm_move_after(struct device *deva, struct device *devb)
 132 {
 133         pr_debug("PM: Moving %s:%s after %s:%s\n",
 134                  deva->bus ? deva->bus->name : "No Bus",
 135                  kobject_name(&deva->kobj),
 136                  devb->bus ? devb->bus->name : "No Bus",
 137                  kobject_name(&devb->kobj));
 138         /* Delete deva from dpm_list and reinsert after devb. */
 139         list_move(&deva->power.entry, &devb->power.entry);
 140 }
 141
 142 /**
 143  *      device_pm_move_last - move device to end of dpm_list
 144  *      @dev:   Device to move in dpm_list
 145  */
 146 void device_pm_move_last(struct device *dev)
 147 {
 148         pr_debug("PM: Moving %s:%s to end of list\n",
 149                  dev->bus ? dev->bus->name : "No Bus",
 150                  kobject_name(&dev->kobj));
 151         list_move_tail(&dev->power.entry, &dpm_list);
 152 }
 153
 154 /**
 155  *      pm_op - execute the PM operation appropiate for given PM event
 156  *      @dev:   Device.
 157  *      @ops:   PM operations to choose from.
 158  *      @state: PM transition of the system being carried out.
 159  */
 160 static int pm_op(struct device *dev, struct dev_pm_ops *ops,
 161                         pm_message_t state)
 162 {
 163         int error = 0;
 164
 165         switch (state.event) {
 166 #ifdef CONFIG_SUSPEND
 167         case PM_EVENT_SUSPEND:
 168                 if (ops->suspend) {
 169                         error = ops->suspend(dev);
 170                         suspend_report_result(ops->suspend, error);
 171                 }
 172                 break;
 173         case PM_EVENT_RESUME:
 174                 if (ops->resume) {
 175                         error = ops->resume(dev);
 176                         suspend_report_result(ops->resume, error);
 177                 }
 178                 break;
 179 #endif /* CONFIG_SUSPEND */
 180 #ifdef CONFIG_HIBERNATION
 181         case PM_EVENT_FREEZE:
 182         case PM_EVENT_QUIESCE:
 183                 if (ops->freeze) {
 184                         error = ops->freeze(dev);
 185                         suspend_report_result(ops->freeze, error);
 186                 }
 187                 break;
 188         case PM_EVENT_HIBERNATE:
 189                 if (ops->poweroff) {
 190                         error = ops->poweroff(dev);
 191                         suspend_report_result(ops->poweroff, error);
 192                 }
 193                 break;
 194         case PM_EVENT_THAW:
 195         case PM_EVENT_RECOVER:
 196                 if (ops->thaw) {
 197                         error = ops->thaw(dev);
 198                         suspend_report_result(ops->thaw, error);
 199                 }
 200                 break;
 201         case PM_EVENT_RESTORE:
 202                 if (ops->restore) {
 203                         error = ops->restore(dev);
 204                         suspend_report_result(ops->restore, error);
 205                 }
 206                 break;
 207 #endif /* CONFIG_HIBERNATION */
 208         default:
 209                 error = -EINVAL;
 210         }
 211         return error;
 212 }
 213
 214 /**
 215  *      pm_noirq_op - execute the PM operation appropiate for given PM event
 216  *      @dev:   Device.
 217  *      @ops:   PM operations to choose from.
 218  *      @state: PM transition of the system being carried out.
 219  *
 220  *      The operation is executed with interrupts disabled by the only remaining
 221  *      functional CPU in the system.
 222  */
 223 static int pm_noirq_op(struct device *dev, struct dev_pm_ops *ops,
 224                         pm_message_t state)
 225 {
 226         int error = 0;
 227
 228         switch (state.event) {
 229 #ifdef CONFIG_SUSPEND
 230         case PM_EVENT_SUSPEND:
 231                 if (ops->suspend_noirq) {
 232                         error = ops->suspend_noirq(dev);
 233                         suspend_report_result(ops->suspend_noirq, error);
 234                 }
 235                 break;
 236         case PM_EVENT_RESUME:
 237                 if (ops->resume_noirq) {
 238                         error = ops->resume_noirq(dev);
 239                         suspend_report_result(ops->resume_noirq, error);
 240                 }
 241                 break;
 242 #endif /* CONFIG_SUSPEND */
 243 #ifdef CONFIG_HIBERNATION
 244         case PM_EVENT_FREEZE:
 245         case PM_EVENT_QUIESCE:
 246                 if (ops->freeze_noirq) {
 247                         error = ops->freeze_noirq(dev);
 248                         suspend_report_result(ops->freeze_noirq, error);
 249                 }
 250                 break;
 251         case PM_EVENT_HIBERNATE:
 252                 if (ops->poweroff_noirq) {
 253                         error = ops->poweroff_noirq(dev);
 254                         suspend_report_result(ops->poweroff_noirq, error);
 255                 }
 256                 break;
 257         case PM_EVENT_THAW:
 258         case PM_EVENT_RECOVER:
 259                 if (ops->thaw_noirq) {
 260                         error = ops->thaw_noirq(dev);
 261                         suspend_report_result(ops->thaw_noirq, error);
 262                 }
 263                 break;
 264         case PM_EVENT_RESTORE:
 265                 if (ops->restore_noirq) {
 266                         error = ops->restore_noirq(dev);
 267                         suspend_report_result(ops->restore_noirq, error);
 268                 }
 269                 break;
 270 #endif /* CONFIG_HIBERNATION */
 271         default:
 272                 error = -EINVAL;
 273         }
 274         return error;
 275 }
 276
 277 static char *pm_verb(int event)
 278 {
 279         switch (event) {
 280         case PM_EVENT_SUSPEND:
 281                 return "suspend";
 282         case PM_EVENT_RESUME:
 283                 return "resume";
 284         case PM_EVENT_FREEZE:
 285                 return "freeze";
 286         case PM_EVENT_QUIESCE:
 287                 return "quiesce";
 288         case PM_EVENT_HIBERNATE:
 289                 return "hibernate";
 290         case PM_EVENT_THAW:
 291                 return "thaw";
 292         case PM_EVENT_RESTORE:
 293                 return "restore";
 294         case PM_EVENT_RECOVER:
 295                 return "recover";
 296         default:
 297                 return "(unknown PM event)";
 298         }
 299 }
 300
 301 static void pm_dev_dbg(struct device *dev, pm_message_t state, char *info)
 302 {
 303         dev_dbg(dev, "%s%s%s\n", info, pm_verb(state.event),
 304                 ((state.event & PM_EVENT_SLEEP) && device_may_wakeup(dev)) ?
 305                 ", may wakeup" : "");
 306 }
 307
 308 static void pm_dev_err(struct device *dev, pm_message_t state, char *info,
 309                         int error)
 310 {
 311         printk(KERN_ERR "PM: Device %s failed to %s%s: error %d\n",
 312                 kobject_name(&dev->kobj), pm_verb(state.event), info, error);
 313 }
 314
 315 /*------------------------- Resume routines -------------------------*/
 316
 317 /**
 318  *      resume_device_noirq - Power on one device (early resume).
 319  *      @dev:   Device.
 320  *      @state: PM transition of the system being carried out.
 321  *
 322  *      Must be called with interrupts disabled.
 323  */
 324 static int resume_device_noirq(struct device *dev, pm_message_t state)
 325 {
 326         int error = 0;
 327
 328         TRACE_DEVICE(dev);
 329         TRACE_RESUME(0);
 330
 331         if (!dev->bus)
 332                 goto End;
 333
 334         if (dev->bus->pm) {
 335                 pm_dev_dbg(dev, state, "EARLY ");
 336                 error = pm_noirq_op(dev, dev->bus->pm, state);
 337         } else if (dev->bus->resume_early) {
 338                 pm_dev_dbg(dev, state, "legacy EARLY ");
 339                 error = dev->bus->resume_early(dev);
 340         }
 341  End:
 342         TRACE_RESUME(error);
 343         return error;
 344 }
 345
 346 /**
 347  *      dpm_power_up - Power on all regular (non-sysdev) devices.
 348  *      @state: PM transition of the system being carried out.
 349  *
 350  *      Execute the appropriate "noirq resume" callback for all devices marked
 351  *      as DPM_OFF_IRQ.
 352  *
 353  *      Must be called under dpm_list_mtx.  Device drivers should not receive
 354  *      interrupts while it's being executed.
 355  */
 356 static void dpm_power_up(pm_message_t state)
 357 {
 358         struct device *dev;
 359
 360         mutex_lock(&dpm_list_mtx);
 361         list_for_each_entry(dev, &dpm_list, power.entry)
 362                 if (dev->power.status > DPM_OFF) {
 363                         int error;
 364
 365                         dev->power.status = DPM_OFF;
 366                         error = resume_device_noirq(dev, state);
 367                         if (error)
 368                                 pm_dev_err(dev, state, " early", error);
 369                 }
 370         mutex_unlock(&dpm_list_mtx);
 371 }
 372
 373 /**
 374  *      device_power_up - Turn on all devices that need special attention.
 375  *      @state: PM transition of the system being carried out.
 376  *
 377  *      Call the "early" resume handlers and enable device drivers to receive
 378  *      interrupts.
 379  */
 380 void device_power_up(pm_message_t state)
 381 {
 382         dpm_power_up(state);
 383         resume_device_irqs();
 384 }
 385 EXPORT_SYMBOL_GPL(device_power_up);
 386
 387 /**
 388  *      resume_device - Restore state for one device.
 389  *      @dev:   Device.
 390  *      @state: PM transition of the system being carried out.
 391  */
 392 static int resume_device(struct device *dev, pm_message_t state)
 393 {
 394         int error = 0;
 395
 396         TRACE_DEVICE(dev);
 397         TRACE_RESUME(0);
 398
 399         down(&dev->sem);
 400
 401         if (dev->bus) {
 402                 if (dev->bus->pm) {
 403                         pm_dev_dbg(dev, state, "");
 404                         error = pm_op(dev, dev->bus->pm, state);
 405                 } else if (dev->bus->resume) {
 406                         pm_dev_dbg(dev, state, "legacy ");
 407                         error = dev->bus->resume(dev);
 408                 }
 409                 if (error)
 410                         goto End;
 411         }
 412
 413         if (dev->type) {
 414                 if (dev->type->pm) {
 415                         pm_dev_dbg(dev, state, "type ");
 416                         error = pm_op(dev, dev->type->pm, state);
 417                 } else if (dev->type->resume) {
 418                         pm_dev_dbg(dev, state, "legacy type ");
 419                         error = dev->type->resume(dev);
 420                 }
 421                 if (error)
 422                         goto End;
 423         }
 424
 425         if (dev->class) {
 426                 if (dev->class->pm) {
 427                         pm_dev_dbg(dev, state, "class ");
 428                         error = pm_op(dev, dev->class->pm, state);
 429                 } else if (dev->class->resume) {
 430                         pm_dev_dbg(dev, state, "legacy class ");
 431                         error = dev->class->resume(dev);
 432                 }
 433         }
 434  End:
 435         up(&dev->sem);
 436
 437         TRACE_RESUME(error);
 438         return error;
 439 }
 440
 441 /**
 442  *      dpm_resume - Resume every device.
 443  *      @state: PM transition of the system being carried out.
 444  *
 445  *      Execute the appropriate "resume" callback for all devices the status of
 446  *      which indicates that they are inactive.
 447  */
 448 static void dpm_resume(pm_message_t state)
 449 {
 450         struct list_head list;
 451
 452         INIT_LIST_HEAD(&list);
 453         mutex_lock(&dpm_list_mtx);
 454         transition_started = false;
 455         while (!list_empty(&dpm_list)) {
 456                 struct device *dev = to_device(dpm_list.next);
 457
 458                 get_device(dev);
 459                 if (dev->power.status >= DPM_OFF) {
 460                         int error;
 461
 462                         dev->power.status = DPM_RESUMING;
 463                         mutex_unlock(&dpm_list_mtx);
 464
 465                         error = resume_device(dev, state);
 466
 467                         mutex_lock(&dpm_list_mtx);
 468                         if (error)
 469                                 pm_dev_err(dev, state, "", error);
 470                 } else if (dev->power.status == DPM_SUSPENDING) {
 471                         /* Allow new children of the device to be registered */
 472                         dev->power.status = DPM_RESUMING;
 473                 }
 474                 if (!list_empty(&dev->power.entry))
 475                         list_move_tail(&dev->power.entry, &list);
 476                 put_device(dev);
 477         }
 478         list_splice(&list, &dpm_list);
 479         mutex_unlock(&dpm_list_mtx);
 480 }
 481
 482 /**
 483  *      complete_device - Complete a PM transition for given device
 484  *      @dev:   Device.
 485  *      @state: PM transition of the system being carried out.
 486  */
 487 static void complete_device(struct device *dev, pm_message_t state)
 488 {
 489         down(&dev->sem);
 490
 491         if (dev->class && dev->class->pm && dev->class->pm->complete) {
 492                 pm_dev_dbg(dev, state, "completing class ");
 493                 dev->class->pm->complete(dev);
 494         }
 495
 496         if (dev->type && dev->type->pm && dev->type->pm->complete) {
 497                 pm_dev_dbg(dev, state, "completing type ");
 498                 dev->type->pm->complete(dev);
 499         }
 500
 501         if (dev->bus && dev->bus->pm && dev->bus->pm->complete) {
 502                 pm_dev_dbg(dev, state, "completing ");
 503                 dev->bus->pm->complete(dev);
 504         }
 505
 506         up(&dev->sem);
 507 }
 508
 509 /**
 510  *      dpm_complete - Complete a PM transition for all devices.
 511  *      @state: PM transition of the system being carried out.
 512  *
 513  *      Execute the ->complete() callbacks for all devices that are not marked
 514  *      as DPM_ON.
 515  */
 516 static void dpm_complete(pm_message_t state)
 517 {
 518         struct list_head list;
 519
 520         INIT_LIST_HEAD(&list);
 521         mutex_lock(&dpm_list_mtx);
 522         while (!list_empty(&dpm_list)) {
 523                 struct device *dev = to_device(dpm_list.prev);
 524
 525                 get_device(dev);
 526                 if (dev->power.status > DPM_ON) {
 527                         dev->power.status = DPM_ON;
 528                         mutex_unlock(&dpm_list_mtx);
 529
 530                         complete_device(dev, state);
 531
 532                         mutex_lock(&dpm_list_mtx);
 533                 }
 534                 if (!list_empty(&dev->power.entry))
 535                         list_move(&dev->power.entry, &list);
 536                 put_device(dev);
 537         }
 538         list_splice(&list, &dpm_list);
 539         mutex_unlock(&dpm_list_mtx);
 540 }
 541
 542 /**
 543  *      device_resume - Restore state of each device in system.
 544  *      @state: PM transition of the system being carried out.
 545  *
 546  *      Resume all the devices, unlock them all, and allow new
 547  *      devices to be registered once again.
 548  */
 549 void device_resume(pm_message_t state)
 550 {
 551         might_sleep();
 552         dpm_resume(state);
 553         dpm_complete(state);
 554 }
 555 EXPORT_SYMBOL_GPL(device_resume);
 556
 557
 558 /*------------------------- Suspend routines -------------------------*/
 559
 560 /**
 561  *      resume_event - return a PM message representing the resume event
 562  *                     corresponding to given sleep state.
 563  *      @sleep_state: PM message representing a sleep state.
 564  */
 565 static pm_message_t resume_event(pm_message_t sleep_state)
 566 {
 567         switch (sleep_state.event) {
 568         case PM_EVENT_SUSPEND:
 569                 return PMSG_RESUME;
 570         case PM_EVENT_FREEZE:
 571         case PM_EVENT_QUIESCE:
 572                 return PMSG_RECOVER;
 573         case PM_EVENT_HIBERNATE:
 574                 return PMSG_RESTORE;
 575         }
 576         return PMSG_ON;
 577 }
 578
 579 /**
 580  *      suspend_device_noirq - Shut down one device (late suspend).
 581  *      @dev:   Device.
 582  *      @state: PM transition of the system being carried out.
 583  *
 584  *      This is called with interrupts off and only a single CPU running.
 585  */
 586 static int suspend_device_noirq(struct device *dev, pm_message_t state)
 587 {
 588         int error = 0;
 589
 590         if (!dev->bus)
 591                 return 0;
 592
 593         if (dev->bus->pm) {
 594                 pm_dev_dbg(dev, state, "LATE ");
 595                 error = pm_noirq_op(dev, dev->bus->pm, state);
 596         } else if (dev->bus->suspend_late) {
 597                 pm_dev_dbg(dev, state, "legacy LATE ");
 598                 error = dev->bus->suspend_late(dev, state);
 599                 suspend_report_result(dev->bus->suspend_late, error);
 600         }
 601         return error;
 602 }
 603
 604 /**
 605  *      device_power_down - Shut down special devices.
 606  *      @state: PM transition of the system being carried out.
 607  *
 608  *      Prevent device drivers from receiving interrupts and call the "late"
 609  *      suspend handlers.
 610  *
 611  *      Must be called under dpm_list_mtx.
 612  */
 613 int device_power_down(pm_message_t state)
 614 {
 615         struct device *dev;
 616         int error = 0;
 617
 618         suspend_device_irqs();
 619         mutex_lock(&dpm_list_mtx);
 620         list_for_each_entry_reverse(dev, &dpm_list, power.entry) {
 621                 error = suspend_device_noirq(dev, state);
 622                 if (error) {
 623                         pm_dev_err(dev, state, " late", error);
 624                         break;
 625                 }
 626                 dev->power.status = DPM_OFF_IRQ;
 627         }
 628         mutex_unlock(&dpm_list_mtx);
 629         if (error)
 630                 device_power_up(resume_event(state));
 631         return error;
 632 }
 633 EXPORT_SYMBOL_GPL(device_power_down);
 634
 635 /**
 636  *      suspend_device - Save state of one device.
 637  *      @dev:   Device.
 638  *      @state: PM transition of the system being carried out.
 639  */
 640 static int suspend_device(struct device *dev, pm_message_t state)
 641 {
 642         int error = 0;
 643
 644         down(&dev->sem);
 645
 646         if (dev->class) {
 647                 if (dev->class->pm) {
 648                         pm_dev_dbg(dev, state, "class ");
 649                         error = pm_op(dev, dev->class->pm, state);
 650                 } else if (dev->class->suspend) {
 651                         pm_dev_dbg(dev, state, "legacy class ");
 652                         error = dev->class->suspend(dev, state);
 653                         suspend_report_result(dev->class->suspend, error);
 654                 }
 655                 if (error)
 656                         goto End;
 657         }
 658
 659         if (dev->type) {
 660                 if (dev->type->pm) {
 661                         pm_dev_dbg(dev, state, "type ");
 662                         error = pm_op(dev, dev->type->pm, state);
 663                 } else if (dev->type->suspend) {
 664                         pm_dev_dbg(dev, state, "legacy type ");
 665                         error = dev->type->suspend(dev, state);
 666                         suspend_report_result(dev->type->suspend, error);
 667                 }
 668                 if (error)
 669                         goto End;
 670         }
 671
 672         if (dev->bus) {
 673                 if (dev->bus->pm) {
 674                         pm_dev_dbg(dev, state, "");
 675                         error = pm_op(dev, dev->bus->pm, state);
 676                 } else if (dev->bus->suspend) {
 677                         pm_dev_dbg(dev, state, "legacy ");
 678                         error = dev->bus->suspend(dev, state);
 679                         suspend_report_result(dev->bus->suspend, error);
 680                 }
 681         }
 682  End:
 683         up(&dev->sem);
 684
 685         return error;
 686 }
 687
 688 /**
 689  *      dpm_suspend - Suspend every device.
 690  *      @state: PM transition of the system being carried out.
 691  *
 692  *      Execute the appropriate "suspend" callbacks for all devices.
 693  */
 694 static int dpm_suspend(pm_message_t state)
 695 {
 696         struct list_head list;
 697         int error = 0;
 698
 699         INIT_LIST_HEAD(&list);
 700         mutex_lock(&dpm_list_mtx);
 701         while (!list_empty(&dpm_list)) {
 702                 struct device *dev = to_device(dpm_list.prev);
 703
 704                 get_device(dev);
 705                 mutex_unlock(&dpm_list_mtx);
 706
 707                 error = suspend_device(dev, state);
 708
 709                 mutex_lock(&dpm_list_mtx);
 710                 if (error) {
 711                         pm_dev_err(dev, state, "", error);
 712                         put_device(dev);
 713                         break;
 714                 }
 715                 dev->power.status = DPM_OFF;
 716                 if (!list_empty(&dev->power.entry))
 717                         list_move(&dev->power.entry, &list);
 718                 put_device(dev);
 719         }
 720         list_splice(&list, dpm_list.prev);
 721         mutex_unlock(&dpm_list_mtx);
 722         return error;
 723 }
 724
 725 /**
 726  *      prepare_device - Execute the ->prepare() callback(s) for given device.
 727  *      @dev:   Device.
 728  *      @state: PM transition of the system being carried out.
 729  */
 730 static int prepare_device(struct device *dev, pm_message_t state)
 731 {
 732         int error = 0;
 733
 734         down(&dev->sem);
 735
 736         if (dev->bus && dev->bus->pm && dev->bus->pm->prepare) {
 737                 pm_dev_dbg(dev, state, "preparing ");
 738                 error = dev->bus->pm->prepare(dev);
 739                 suspend_report_result(dev->bus->pm->prepare, error);
 740                 if (error)
 741                         goto End;
 742         }
 743
 744         if (dev->type && dev->type->pm && dev->type->pm->prepare) {
 745                 pm_dev_dbg(dev, state, "preparing type ");
 746                 error = dev->type->pm->prepare(dev);
 747                 suspend_report_result(dev->type->pm->prepare, error);
 748                 if (error)
 749                         goto End;
 750         }
 751
 752         if (dev->class && dev->class->pm && dev->class->pm->prepare) {
 753                 pm_dev_dbg(dev, state, "preparing class ");
 754                 error = dev->class->pm->prepare(dev);
 755                 suspend_report_result(dev->class->pm->prepare, error);
 756         }
 757  End:
 758         up(&dev->sem);
 759
 760         return error;
 761 }
 762
 763 /**
 764  *      dpm_prepare - Prepare all devices for a PM transition.
 765  *      @state: PM transition of the system being carried out.
 766  *
 767  *      Execute the ->prepare() callback for all devices.
 768  */
 769 static int dpm_prepare(pm_message_t state)
 770 {
 771         struct list_head list;
 772         int error = 0;
 773
 774         INIT_LIST_HEAD(&list);
 775         mutex_lock(&dpm_list_mtx);
 776         transition_started = true;
 777         while (!list_empty(&dpm_list)) {
 778                 struct device *dev = to_device(dpm_list.next);
 779
 780                 get_device(dev);
 781                 dev->power.status = DPM_PREPARING;
 782                 mutex_unlock(&dpm_list_mtx);
 783
 784                 error = prepare_device(dev, state);
 785
 786                 mutex_lock(&dpm_list_mtx);
 787                 if (error) {
 788                         dev->power.status = DPM_ON;
 789                         if (error == -EAGAIN) {
 790                                 put_device(dev);
 791                                 continue;
 792                         }
 793                         printk(KERN_ERR "PM: Failed to prepare device %s "
 794                                 "for power transition: error %d\n",
 795                                 kobject_name(&dev->kobj), error);
 796                         put_device(dev);
 797                         break;
 798                 }
 799                 dev->power.status = DPM_SUSPENDING;
 800                 if (!list_empty(&dev->power.entry))
 801                         list_move_tail(&dev->power.entry, &list);
 802                 put_device(dev);
 803         }
 804         list_splice(&list, &dpm_list);
 805         mutex_unlock(&dpm_list_mtx);
 806         return error;
 807 }
 808
 809 /**
 810  *      device_suspend - Save state and stop all devices in system.
 811  *      @state: PM transition of the system being carried out.
 812  *
 813  *      Prepare and suspend all devices.
 814  */
 815 int device_suspend(pm_message_t state)
 816 {
 817         int error;
 818
 819         might_sleep();
 820         error = dpm_prepare(state);
 821         if (!error)
 822                 error = dpm_suspend(state);
 823         return error;
 824 }
 825 EXPORT_SYMBOL_GPL(device_suspend);
 826
 827 void __suspend_report_result(const char *function, void *fn, int ret)
 828 {
 829         if (ret)
 830                 printk(KERN_ERR "%s(): %pF returns %d\n", function, fn, ret);
 831 }
 832 EXPORT_SYMBOL_GPL(__suspend_report_result);