drivers/base/power/main.c

   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  *      device_resume_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 device_resume_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_resume_noirq - Power on all regular (non-sysdev) devices.
 348  *      @state: PM transition of the system being carried out.
 349  *
 350  *      Call the "noirq" resume handlers for all devices marked as
 351  *      DPM_OFF_IRQ and enable device drivers to receive interrupts.
 352  *
 353  *      Must be called under dpm_list_mtx.  Device drivers should not receive
 354  *      interrupts while it's being executed.
 355  */
 356 void dpm_resume_noirq(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 = device_resume_noirq(dev, state);
 367                         if (error)
 368                                 pm_dev_err(dev, state, " early", error);
 369                 }
 370         mutex_unlock(&dpm_list_mtx);
 371         resume_device_irqs();
 372 }
 373 EXPORT_SYMBOL_GPL(dpm_resume_noirq);
 374
 375 /**
 376  *      device_resume - Restore state for one device.
 377  *      @dev:   Device.
 378  *      @state: PM transition of the system being carried out.
 379  */
 380 static int device_resume(struct device *dev, pm_message_t state)
 381 {
 382         int error = 0;
 383
 384         TRACE_DEVICE(dev);
 385         TRACE_RESUME(0);
 386
 387         down(&dev->sem);
 388
 389         if (dev->bus) {
 390                 if (dev->bus->pm) {
 391                         pm_dev_dbg(dev, state, "");
 392                         error = pm_op(dev, dev->bus->pm, state);
 393                 } else if (dev->bus->resume) {
 394                         pm_dev_dbg(dev, state, "legacy ");
 395                         error = dev->bus->resume(dev);
 396                 }
 397                 if (error)
 398                         goto End;
 399         }
 400
 401         if (dev->type) {
 402                 if (dev->type->pm) {
 403                         pm_dev_dbg(dev, state, "type ");
 404                         error = pm_op(dev, dev->type->pm, state);
 405                 } else if (dev->type->resume) {
 406                         pm_dev_dbg(dev, state, "legacy type ");
 407                         error = dev->type->resume(dev);
 408                 }
 409                 if (error)
 410                         goto End;
 411         }
 412
 413         if (dev->class) {
 414                 if (dev->class->pm) {
 415                         pm_dev_dbg(dev, state, "class ");
 416                         error = pm_op(dev, dev->class->pm, state);
 417                 } else if (dev->class->resume) {
 418                         pm_dev_dbg(dev, state, "legacy class ");
 419                         error = dev->class->resume(dev);
 420                 }
 421         }
 422  End:
 423         up(&dev->sem);
 424
 425         TRACE_RESUME(error);
 426         return error;
 427 }
 428
 429 /**
 430  *      dpm_resume - Resume every device.
 431  *      @state: PM transition of the system being carried out.
 432  *
 433  *      Execute the appropriate "resume" callback for all devices the status of
 434  *      which indicates that they are inactive.
 435  */
 436 static void dpm_resume(pm_message_t state)
 437 {
 438         struct list_head list;
 439
 440         INIT_LIST_HEAD(&list);
 441         mutex_lock(&dpm_list_mtx);
 442         transition_started = false;
 443         while (!list_empty(&dpm_list)) {
 444                 struct device *dev = to_device(dpm_list.next);
 445
 446                 get_device(dev);
 447                 if (dev->power.status >= DPM_OFF) {
 448                         int error;
 449
 450                         dev->power.status = DPM_RESUMING;
 451                         mutex_unlock(&dpm_list_mtx);
 452
 453                         error = device_resume(dev, state);
 454
 455                         mutex_lock(&dpm_list_mtx);
 456                         if (error)
 457                                 pm_dev_err(dev, state, "", error);
 458                 } else if (dev->power.status == DPM_SUSPENDING) {
 459                         /* Allow new children of the device to be registered */
 460                         dev->power.status = DPM_RESUMING;
 461                 }
 462                 if (!list_empty(&dev->power.entry))
 463                         list_move_tail(&dev->power.entry, &list);
 464                 put_device(dev);
 465         }
 466         list_splice(&list, &dpm_list);
 467         mutex_unlock(&dpm_list_mtx);
 468 }
 469
 470 /**
 471  *      device_complete - Complete a PM transition for given device
 472  *      @dev:   Device.
 473  *      @state: PM transition of the system being carried out.
 474  */
 475 static void device_complete(struct device *dev, pm_message_t state)
 476 {
 477         down(&dev->sem);
 478
 479         if (dev->class && dev->class->pm && dev->class->pm->complete) {
 480                 pm_dev_dbg(dev, state, "completing class ");
 481                 dev->class->pm->complete(dev);
 482         }
 483
 484         if (dev->type && dev->type->pm && dev->type->pm->complete) {
 485                 pm_dev_dbg(dev, state, "completing type ");
 486                 dev->type->pm->complete(dev);
 487         }
 488
 489         if (dev->bus && dev->bus->pm && dev->bus->pm->complete) {
 490                 pm_dev_dbg(dev, state, "completing ");
 491                 dev->bus->pm->complete(dev);
 492         }
 493
 494         up(&dev->sem);
 495 }
 496
 497 /**
 498  *      dpm_complete - Complete a PM transition for all devices.
 499  *      @state: PM transition of the system being carried out.
 500  *
 501  *      Execute the ->complete() callbacks for all devices that are not marked
 502  *      as DPM_ON.
 503  */
 504 static void dpm_complete(pm_message_t state)
 505 {
 506         struct list_head list;
 507
 508         INIT_LIST_HEAD(&list);
 509         mutex_lock(&dpm_list_mtx);
 510         while (!list_empty(&dpm_list)) {
 511                 struct device *dev = to_device(dpm_list.prev);
 512
 513                 get_device(dev);
 514                 if (dev->power.status > DPM_ON) {
 515                         dev->power.status = DPM_ON;
 516                         mutex_unlock(&dpm_list_mtx);
 517
 518                         device_complete(dev, state);
 519
 520                         mutex_lock(&dpm_list_mtx);
 521                 }
 522                 if (!list_empty(&dev->power.entry))
 523                         list_move(&dev->power.entry, &list);
 524                 put_device(dev);
 525         }
 526         list_splice(&list, &dpm_list);
 527         mutex_unlock(&dpm_list_mtx);
 528 }
 529
 530 /**
 531  *      dpm_resume_end - Restore state of each device in system.
 532  *      @state: PM transition of the system being carried out.
 533  *
 534  *      Resume all the devices, unlock them all, and allow new
 535  *      devices to be registered once again.
 536  */
 537 void dpm_resume_end(pm_message_t state)
 538 {
 539         might_sleep();
 540         dpm_resume(state);
 541         dpm_complete(state);
 542 }
 543 EXPORT_SYMBOL_GPL(dpm_resume_end);
 544
 545
 546 /*------------------------- Suspend routines -------------------------*/
 547
 548 /**
 549  *      resume_event - return a PM message representing the resume event
 550  *                     corresponding to given sleep state.
 551  *      @sleep_state: PM message representing a sleep state.
 552  */
 553 static pm_message_t resume_event(pm_message_t sleep_state)
 554 {
 555         switch (sleep_state.event) {
 556         case PM_EVENT_SUSPEND:
 557                 return PMSG_RESUME;
 558         case PM_EVENT_FREEZE:
 559         case PM_EVENT_QUIESCE:
 560                 return PMSG_RECOVER;
 561         case PM_EVENT_HIBERNATE:
 562                 return PMSG_RESTORE;
 563         }
 564         return PMSG_ON;
 565 }
 566
 567 /**
 568  *      device_suspend_noirq - Shut down one device (late suspend).
 569  *      @dev:   Device.
 570  *      @state: PM transition of the system being carried out.
 571  *
 572  *      This is called with interrupts off and only a single CPU running.
 573  */
 574 static int device_suspend_noirq(struct device *dev, pm_message_t state)
 575 {
 576         int error = 0;
 577
 578         if (!dev->bus)
 579                 return 0;
 580
 581         if (dev->bus->pm) {
 582                 pm_dev_dbg(dev, state, "LATE ");
 583                 error = pm_noirq_op(dev, dev->bus->pm, state);
 584         } else if (dev->bus->suspend_late) {
 585                 pm_dev_dbg(dev, state, "legacy LATE ");
 586                 error = dev->bus->suspend_late(dev, state);
 587                 suspend_report_result(dev->bus->suspend_late, error);
 588         }
 589         return error;
 590 }
 591
 592 /**
 593  *      dpm_suspend_noirq - Power down all regular (non-sysdev) devices.
 594  *      @state: PM transition of the system being carried out.
 595  *
 596  *      Prevent device drivers from receiving interrupts and call the "noirq"
 597  *      suspend handlers.
 598  *
 599  *      Must be called under dpm_list_mtx.
 600  */
 601 int dpm_suspend_noirq(pm_message_t state)
 602 {
 603         struct device *dev;
 604         int error = 0;
 605
 606         suspend_device_irqs();
 607         mutex_lock(&dpm_list_mtx);
 608         list_for_each_entry_reverse(dev, &dpm_list, power.entry) {
 609                 error = device_suspend_noirq(dev, state);
 610                 if (error) {
 611                         pm_dev_err(dev, state, " late", error);
 612                         break;
 613                 }
 614                 dev->power.status = DPM_OFF_IRQ;
 615         }
 616         mutex_unlock(&dpm_list_mtx);
 617         if (error)
 618                 dpm_resume_noirq(resume_event(state));
 619         return error;
 620 }
 621 EXPORT_SYMBOL_GPL(dpm_suspend_noirq);
 622
 623 /**
 624  *      device_suspend - Save state of one device.
 625  *      @dev:   Device.
 626  *      @state: PM transition of the system being carried out.
 627  */
 628 static int device_suspend(struct device *dev, pm_message_t state)
 629 {
 630         int error = 0;
 631
 632         down(&dev->sem);
 633
 634         if (dev->class) {
 635                 if (dev->class->pm) {
 636                         pm_dev_dbg(dev, state, "class ");
 637                         error = pm_op(dev, dev->class->pm, state);
 638                 } else if (dev->class->suspend) {
 639                         pm_dev_dbg(dev, state, "legacy class ");
 640                         error = dev->class->suspend(dev, state);
 641                         suspend_report_result(dev->class->suspend, error);
 642                 }
 643                 if (error)
 644                         goto End;
 645         }
 646
 647         if (dev->type) {
 648                 if (dev->type->pm) {
 649                         pm_dev_dbg(dev, state, "type ");
 650                         error = pm_op(dev, dev->type->pm, state);
 651                 } else if (dev->type->suspend) {
 652                         pm_dev_dbg(dev, state, "legacy type ");
 653                         error = dev->type->suspend(dev, state);
 654                         suspend_report_result(dev->type->suspend, error);
 655                 }
 656                 if (error)
 657                         goto End;
 658         }
 659
 660         if (dev->bus) {
 661                 if (dev->bus->pm) {
 662                         pm_dev_dbg(dev, state, "");
 663                         error = pm_op(dev, dev->bus->pm, state);
 664                 } else if (dev->bus->suspend) {
 665                         pm_dev_dbg(dev, state, "legacy ");
 666                         error = dev->bus->suspend(dev, state);
 667                         suspend_report_result(dev->bus->suspend, error);
 668                 }
 669         }
 670  End:
 671         up(&dev->sem);
 672
 673         return error;
 674 }
 675
 676 /**
 677  *      dpm_suspend - Suspend every device.
 678  *      @state: PM transition of the system being carried out.
 679  *
 680  *      Execute the appropriate "suspend" callbacks for all devices.
 681  */
 682 static int dpm_suspend(pm_message_t state)
 683 {
 684         struct list_head list;
 685         int error = 0;
 686
 687         INIT_LIST_HEAD(&list);
 688         mutex_lock(&dpm_list_mtx);
 689         while (!list_empty(&dpm_list)) {
 690                 struct device *dev = to_device(dpm_list.prev);
 691
 692                 get_device(dev);
 693                 mutex_unlock(&dpm_list_mtx);
 694
 695                 error = device_suspend(dev, state);
 696
 697                 mutex_lock(&dpm_list_mtx);
 698                 if (error) {
 699                         pm_dev_err(dev, state, "", error);
 700                         put_device(dev);
 701                         break;
 702                 }
 703                 dev->power.status = DPM_OFF;
 704                 if (!list_empty(&dev->power.entry))
 705                         list_move(&dev->power.entry, &list);
 706                 put_device(dev);
 707         }
 708         list_splice(&list, dpm_list.prev);
 709         mutex_unlock(&dpm_list_mtx);
 710         return error;
 711 }
 712
 713 /**
 714  *      device_prepare - Execute the ->prepare() callback(s) for given device.
 715  *      @dev:   Device.
 716  *      @state: PM transition of the system being carried out.
 717  */
 718 static int device_prepare(struct device *dev, pm_message_t state)
 719 {
 720         int error = 0;
 721
 722         down(&dev->sem);
 723
 724         if (dev->bus && dev->bus->pm && dev->bus->pm->prepare) {
 725                 pm_dev_dbg(dev, state, "preparing ");
 726                 error = dev->bus->pm->prepare(dev);
 727                 suspend_report_result(dev->bus->pm->prepare, error);
 728                 if (error)
 729                         goto End;
 730         }
 731
 732         if (dev->type && dev->type->pm && dev->type->pm->prepare) {
 733                 pm_dev_dbg(dev, state, "preparing type ");
 734                 error = dev->type->pm->prepare(dev);
 735                 suspend_report_result(dev->type->pm->prepare, error);
 736                 if (error)
 737                         goto End;
 738         }
 739
 740         if (dev->class && dev->class->pm && dev->class->pm->prepare) {
 741                 pm_dev_dbg(dev, state, "preparing class ");
 742                 error = dev->class->pm->prepare(dev);
 743                 suspend_report_result(dev->class->pm->prepare, error);
 744         }
 745  End:
 746         up(&dev->sem);
 747
 748         return error;
 749 }
 750
 751 /**
 752  *      dpm_prepare - Prepare all devices for a PM transition.
 753  *      @state: PM transition of the system being carried out.
 754  *
 755  *      Execute the ->prepare() callback for all devices.
 756  */
 757 static int dpm_prepare(pm_message_t state)
 758 {
 759         struct list_head list;
 760         int error = 0;
 761
 762         INIT_LIST_HEAD(&list);
 763         mutex_lock(&dpm_list_mtx);
 764         transition_started = true;
 765         while (!list_empty(&dpm_list)) {
 766                 struct device *dev = to_device(dpm_list.next);
 767
 768                 get_device(dev);
 769                 dev->power.status = DPM_PREPARING;
 770                 mutex_unlock(&dpm_list_mtx);
 771
 772                 error = device_prepare(dev, state);
 773
 774                 mutex_lock(&dpm_list_mtx);
 775                 if (error) {
 776                         dev->power.status = DPM_ON;
 777                         if (error == -EAGAIN) {
 778                                 put_device(dev);
 779                                 continue;
 780                         }
 781                         printk(KERN_ERR "PM: Failed to prepare device %s "
 782                                 "for power transition: error %d\n",
 783                                 kobject_name(&dev->kobj), error);
 784                         put_device(dev);
 785                         break;
 786                 }
 787                 dev->power.status = DPM_SUSPENDING;
 788                 if (!list_empty(&dev->power.entry))
 789                         list_move_tail(&dev->power.entry, &list);
 790                 put_device(dev);
 791         }
 792         list_splice(&list, &dpm_list);
 793         mutex_unlock(&dpm_list_mtx);
 794         return error;
 795 }
 796
 797 /**
 798  *      dpm_suspend_start - Save state and stop all devices in system.
 799  *      @state: PM transition of the system being carried out.
 800  *
 801  *      Prepare and suspend all devices.
 802  */
 803 int dpm_suspend_start(pm_message_t state)
 804 {
 805         int error;
 806
 807         might_sleep();
 808         error = dpm_prepare(state);
 809         if (!error)
 810                 error = dpm_suspend(state);
 811         return error;
 812 }
 813 EXPORT_SYMBOL_GPL(dpm_suspend_start);
 814
 815 void __suspend_report_result(const char *function, void *fn, int ret)
 816 {
 817         if (ret)
 818                 printk(KERN_ERR "%s(): %pF returns %d\n", function, fn, ret);
 819 }
 820 EXPORT_SYMBOL_GPL(__suspend_report_result);