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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  *      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         }
 338  End:
 339         TRACE_RESUME(error);
 340         return error;
 341 }
 342
 343 /**
 344  *      dpm_resume_noirq - Power on all regular (non-sysdev) devices.
 345  *      @state: PM transition of the system being carried out.
 346  *
 347  *      Call the "noirq" resume handlers for all devices marked as
 348  *      DPM_OFF_IRQ and enable device drivers to receive interrupts.
 349  *
 350  *      Must be called under dpm_list_mtx.  Device drivers should not receive
 351  *      interrupts while it's being executed.
 352  */
 353 void dpm_resume_noirq(pm_message_t state)
 354 {
 355         struct device *dev;
 356
 357         mutex_lock(&dpm_list_mtx);
 358         list_for_each_entry(dev, &dpm_list, power.entry)
 359                 if (dev->power.status > DPM_OFF) {
 360                         int error;
 361
 362                         dev->power.status = DPM_OFF;
 363                         error = device_resume_noirq(dev, state);
 364                         if (error)
 365                                 pm_dev_err(dev, state, " early", error);
 366                 }
 367         mutex_unlock(&dpm_list_mtx);
 368         resume_device_irqs();
 369 }
 370 EXPORT_SYMBOL_GPL(dpm_resume_noirq);
 371
 372 /**
 373  *      device_resume - Restore state for one device.
 374  *      @dev:   Device.
 375  *      @state: PM transition of the system being carried out.
 376  */
 377 static int device_resume(struct device *dev, pm_message_t state)
 378 {
 379         int error = 0;
 380
 381         TRACE_DEVICE(dev);
 382         TRACE_RESUME(0);
 383
 384         down(&dev->sem);
 385
 386         if (dev->bus) {
 387                 if (dev->bus->pm) {
 388                         pm_dev_dbg(dev, state, "");
 389                         error = pm_op(dev, dev->bus->pm, state);
 390                 } else if (dev->bus->resume) {
 391                         pm_dev_dbg(dev, state, "legacy ");
 392                         error = dev->bus->resume(dev);
 393                 }
 394                 if (error)
 395                         goto End;
 396         }
 397
 398         if (dev->type) {
 399                 if (dev->type->pm) {
 400                         pm_dev_dbg(dev, state, "type ");
 401                         error = pm_op(dev, dev->type->pm, state);
 402                 } else if (dev->type->resume) {
 403                         pm_dev_dbg(dev, state, "legacy type ");
 404                         error = dev->type->resume(dev);
 405                 }
 406                 if (error)
 407                         goto End;
 408         }
 409
 410         if (dev->class) {
 411                 if (dev->class->pm) {
 412                         pm_dev_dbg(dev, state, "class ");
 413                         error = pm_op(dev, dev->class->pm, state);
 414                 } else if (dev->class->resume) {
 415                         pm_dev_dbg(dev, state, "legacy class ");
 416                         error = dev->class->resume(dev);
 417                 }
 418         }
 419  End:
 420         up(&dev->sem);
 421
 422         TRACE_RESUME(error);
 423         return error;
 424 }
 425
 426 /**
 427  *      dpm_resume - Resume every device.
 428  *      @state: PM transition of the system being carried out.
 429  *
 430  *      Execute the appropriate "resume" callback for all devices the status of
 431  *      which indicates that they are inactive.
 432  */
 433 static void dpm_resume(pm_message_t state)
 434 {
 435         struct list_head list;
 436
 437         INIT_LIST_HEAD(&list);
 438         mutex_lock(&dpm_list_mtx);
 439         transition_started = false;
 440         while (!list_empty(&dpm_list)) {
 441                 struct device *dev = to_device(dpm_list.next);
 442
 443                 get_device(dev);
 444                 if (dev->power.status >= DPM_OFF) {
 445                         int error;
 446
 447                         dev->power.status = DPM_RESUMING;
 448                         mutex_unlock(&dpm_list_mtx);
 449
 450                         error = device_resume(dev, state);
 451
 452                         mutex_lock(&dpm_list_mtx);
 453                         if (error)
 454                                 pm_dev_err(dev, state, "", error);
 455                 } else if (dev->power.status == DPM_SUSPENDING) {
 456                         /* Allow new children of the device to be registered */
 457                         dev->power.status = DPM_RESUMING;
 458                 }
 459                 if (!list_empty(&dev->power.entry))
 460                         list_move_tail(&dev->power.entry, &list);
 461                 put_device(dev);
 462         }
 463         list_splice(&list, &dpm_list);
 464         mutex_unlock(&dpm_list_mtx);
 465 }
 466
 467 /**
 468  *      device_complete - Complete a PM transition for given device
 469  *      @dev:   Device.
 470  *      @state: PM transition of the system being carried out.
 471  */
 472 static void device_complete(struct device *dev, pm_message_t state)
 473 {
 474         down(&dev->sem);
 475
 476         if (dev->class && dev->class->pm && dev->class->pm->complete) {
 477                 pm_dev_dbg(dev, state, "completing class ");
 478                 dev->class->pm->complete(dev);
 479         }
 480
 481         if (dev->type && dev->type->pm && dev->type->pm->complete) {
 482                 pm_dev_dbg(dev, state, "completing type ");
 483                 dev->type->pm->complete(dev);
 484         }
 485
 486         if (dev->bus && dev->bus->pm && dev->bus->pm->complete) {
 487                 pm_dev_dbg(dev, state, "completing ");
 488                 dev->bus->pm->complete(dev);
 489         }
 490
 491         up(&dev->sem);
 492 }
 493
 494 /**
 495  *      dpm_complete - Complete a PM transition for all devices.
 496  *      @state: PM transition of the system being carried out.
 497  *
 498  *      Execute the ->complete() callbacks for all devices that are not marked
 499  *      as DPM_ON.
 500  */
 501 static void dpm_complete(pm_message_t state)
 502 {
 503         struct list_head list;
 504
 505         INIT_LIST_HEAD(&list);
 506         mutex_lock(&dpm_list_mtx);
 507         while (!list_empty(&dpm_list)) {
 508                 struct device *dev = to_device(dpm_list.prev);
 509
 510                 get_device(dev);
 511                 if (dev->power.status > DPM_ON) {
 512                         dev->power.status = DPM_ON;
 513                         mutex_unlock(&dpm_list_mtx);
 514
 515                         device_complete(dev, state);
 516
 517                         mutex_lock(&dpm_list_mtx);
 518                 }
 519                 if (!list_empty(&dev->power.entry))
 520                         list_move(&dev->power.entry, &list);
 521                 put_device(dev);
 522         }
 523         list_splice(&list, &dpm_list);
 524         mutex_unlock(&dpm_list_mtx);
 525 }
 526
 527 /**
 528  *      dpm_resume_end - Restore state of each device in system.
 529  *      @state: PM transition of the system being carried out.
 530  *
 531  *      Resume all the devices, unlock them all, and allow new
 532  *      devices to be registered once again.
 533  */
 534 void dpm_resume_end(pm_message_t state)
 535 {
 536         might_sleep();
 537         dpm_resume(state);
 538         dpm_complete(state);
 539 }
 540 EXPORT_SYMBOL_GPL(dpm_resume_end);
 541
 542
 543 /*------------------------- Suspend routines -------------------------*/
 544
 545 /**
 546  *      resume_event - return a PM message representing the resume event
 547  *                     corresponding to given sleep state.
 548  *      @sleep_state: PM message representing a sleep state.
 549  */
 550 static pm_message_t resume_event(pm_message_t sleep_state)
 551 {
 552         switch (sleep_state.event) {
 553         case PM_EVENT_SUSPEND:
 554                 return PMSG_RESUME;
 555         case PM_EVENT_FREEZE:
 556         case PM_EVENT_QUIESCE:
 557                 return PMSG_RECOVER;
 558         case PM_EVENT_HIBERNATE:
 559                 return PMSG_RESTORE;
 560         }
 561         return PMSG_ON;
 562 }
 563
 564 /**
 565  *      device_suspend_noirq - Shut down one device (late suspend).
 566  *      @dev:   Device.
 567  *      @state: PM transition of the system being carried out.
 568  *
 569  *      This is called with interrupts off and only a single CPU running.
 570  */
 571 static int device_suspend_noirq(struct device *dev, pm_message_t state)
 572 {
 573         int error = 0;
 574
 575         if (!dev->bus)
 576                 return 0;
 577
 578         if (dev->bus->pm) {
 579                 pm_dev_dbg(dev, state, "LATE ");
 580                 error = pm_noirq_op(dev, dev->bus->pm, state);
 581         }
 582         return error;
 583 }
 584
 585 /**
 586  *      dpm_suspend_noirq - Power down all regular (non-sysdev) devices.
 587  *      @state: PM transition of the system being carried out.
 588  *
 589  *      Prevent device drivers from receiving interrupts and call the "noirq"
 590  *      suspend handlers.
 591  *
 592  *      Must be called under dpm_list_mtx.
 593  */
 594 int dpm_suspend_noirq(pm_message_t state)
 595 {
 596         struct device *dev;
 597         int error = 0;
 598
 599         suspend_device_irqs();
 600         mutex_lock(&dpm_list_mtx);
 601         list_for_each_entry_reverse(dev, &dpm_list, power.entry) {
 602                 error = device_suspend_noirq(dev, state);
 603                 if (error) {
 604                         pm_dev_err(dev, state, " late", error);
 605                         break;
 606                 }
 607                 dev->power.status = DPM_OFF_IRQ;
 608         }
 609         mutex_unlock(&dpm_list_mtx);
 610         if (error)
 611                 dpm_resume_noirq(resume_event(state));
 612         return error;
 613 }
 614 EXPORT_SYMBOL_GPL(dpm_suspend_noirq);
 615
 616 /**
 617  *      device_suspend - Save state of one device.
 618  *      @dev:   Device.
 619  *      @state: PM transition of the system being carried out.
 620  */
 621 static int device_suspend(struct device *dev, pm_message_t state)
 622 {
 623         int error = 0;
 624
 625         down(&dev->sem);
 626
 627         if (dev->class) {
 628                 if (dev->class->pm) {
 629                         pm_dev_dbg(dev, state, "class ");
 630                         error = pm_op(dev, dev->class->pm, state);
 631                 } else if (dev->class->suspend) {
 632                         pm_dev_dbg(dev, state, "legacy class ");
 633                         error = dev->class->suspend(dev, state);
 634                         suspend_report_result(dev->class->suspend, error);
 635                 }
 636                 if (error)
 637                         goto End;
 638         }
 639
 640         if (dev->type) {
 641                 if (dev->type->pm) {
 642                         pm_dev_dbg(dev, state, "type ");
 643                         error = pm_op(dev, dev->type->pm, state);
 644                 } else if (dev->type->suspend) {
 645                         pm_dev_dbg(dev, state, "legacy type ");
 646                         error = dev->type->suspend(dev, state);
 647                         suspend_report_result(dev->type->suspend, error);
 648                 }
 649                 if (error)
 650                         goto End;
 651         }
 652
 653         if (dev->bus) {
 654                 if (dev->bus->pm) {
 655                         pm_dev_dbg(dev, state, "");
 656                         error = pm_op(dev, dev->bus->pm, state);
 657                 } else if (dev->bus->suspend) {
 658                         pm_dev_dbg(dev, state, "legacy ");
 659                         error = dev->bus->suspend(dev, state);
 660                         suspend_report_result(dev->bus->suspend, error);
 661                 }
 662         }
 663  End:
 664         up(&dev->sem);
 665
 666         return error;
 667 }
 668
 669 /**
 670  *      dpm_suspend - Suspend every device.
 671  *      @state: PM transition of the system being carried out.
 672  *
 673  *      Execute the appropriate "suspend" callbacks for all devices.
 674  */
 675 static int dpm_suspend(pm_message_t state)
 676 {
 677         struct list_head list;
 678         int error = 0;
 679
 680         INIT_LIST_HEAD(&list);
 681         mutex_lock(&dpm_list_mtx);
 682         while (!list_empty(&dpm_list)) {
 683                 struct device *dev = to_device(dpm_list.prev);
 684
 685                 get_device(dev);
 686                 mutex_unlock(&dpm_list_mtx);
 687
 688                 error = device_suspend(dev, state);
 689
 690                 mutex_lock(&dpm_list_mtx);
 691                 if (error) {
 692                         pm_dev_err(dev, state, "", error);
 693                         put_device(dev);
 694                         break;
 695                 }
 696                 dev->power.status = DPM_OFF;
 697                 if (!list_empty(&dev->power.entry))
 698                         list_move(&dev->power.entry, &list);
 699                 put_device(dev);
 700         }
 701         list_splice(&list, dpm_list.prev);
 702         mutex_unlock(&dpm_list_mtx);
 703         return error;
 704 }
 705
 706 /**
 707  *      device_prepare - Execute the ->prepare() callback(s) for given device.
 708  *      @dev:   Device.
 709  *      @state: PM transition of the system being carried out.
 710  */
 711 static int device_prepare(struct device *dev, pm_message_t state)
 712 {
 713         int error = 0;
 714
 715         down(&dev->sem);
 716
 717         if (dev->bus && dev->bus->pm && dev->bus->pm->prepare) {
 718                 pm_dev_dbg(dev, state, "preparing ");
 719                 error = dev->bus->pm->prepare(dev);
 720                 suspend_report_result(dev->bus->pm->prepare, error);
 721                 if (error)
 722                         goto End;
 723         }
 724
 725         if (dev->type && dev->type->pm && dev->type->pm->prepare) {
 726                 pm_dev_dbg(dev, state, "preparing type ");
 727                 error = dev->type->pm->prepare(dev);
 728                 suspend_report_result(dev->type->pm->prepare, error);
 729                 if (error)
 730                         goto End;
 731         }
 732
 733         if (dev->class && dev->class->pm && dev->class->pm->prepare) {
 734                 pm_dev_dbg(dev, state, "preparing class ");
 735                 error = dev->class->pm->prepare(dev);
 736                 suspend_report_result(dev->class->pm->prepare, error);
 737         }
 738  End:
 739         up(&dev->sem);
 740
 741         return error;
 742 }
 743
 744 /**
 745  *      dpm_prepare - Prepare all devices for a PM transition.
 746  *      @state: PM transition of the system being carried out.
 747  *
 748  *      Execute the ->prepare() callback for all devices.
 749  */
 750 static int dpm_prepare(pm_message_t state)
 751 {
 752         struct list_head list;
 753         int error = 0;
 754
 755         INIT_LIST_HEAD(&list);
 756         mutex_lock(&dpm_list_mtx);
 757         transition_started = true;
 758         while (!list_empty(&dpm_list)) {
 759                 struct device *dev = to_device(dpm_list.next);
 760
 761                 get_device(dev);
 762                 dev->power.status = DPM_PREPARING;
 763                 mutex_unlock(&dpm_list_mtx);
 764
 765                 error = device_prepare(dev, state);
 766
 767                 mutex_lock(&dpm_list_mtx);
 768                 if (error) {
 769                         dev->power.status = DPM_ON;
 770                         if (error == -EAGAIN) {
 771                                 put_device(dev);
 772                                 continue;
 773                         }
 774                         printk(KERN_ERR "PM: Failed to prepare device %s "
 775                                 "for power transition: error %d\n",
 776                                 kobject_name(&dev->kobj), error);
 777                         put_device(dev);
 778                         break;
 779                 }
 780                 dev->power.status = DPM_SUSPENDING;
 781                 if (!list_empty(&dev->power.entry))
 782                         list_move_tail(&dev->power.entry, &list);
 783                 put_device(dev);
 784         }
 785         list_splice(&list, &dpm_list);
 786         mutex_unlock(&dpm_list_mtx);
 787         return error;
 788 }
 789
 790 /**
 791  *      dpm_suspend_start - Save state and stop all devices in system.
 792  *      @state: PM transition of the system being carried out.
 793  *
 794  *      Prepare and suspend all devices.
 795  */
 796 int dpm_suspend_start(pm_message_t state)
 797 {
 798         int error;
 799
 800         might_sleep();
 801         error = dpm_prepare(state);
 802         if (!error)
 803                 error = dpm_suspend(state);
 804         return error;
 805 }
 806 EXPORT_SYMBOL_GPL(dpm_suspend_start);
 807
 808 void __suspend_report_result(const char *function, void *fn, int ret)
 809 {
 810         if (ret)
 811                 printk(KERN_ERR "%s(): %pF returns %d\n", function, fn, ret);
 812 }
 813 EXPORT_SYMBOL_GPL(__suspend_report_result);