drivers/base/dd.c

   1 /*
   2  * drivers/base/dd.c - The core device/driver interactions.
   3  *
   4  * This file contains the (sometimes tricky) code that controls the
   5  * interactions between devices and drivers, which primarily includes
   6  * driver binding and unbinding.
   7  *
   8  * All of this code used to exist in drivers/base/bus.c, but was
   9  * relocated to here in the name of compartmentalization (since it wasn't
  10  * strictly code just for the 'struct bus_type'.
  11  *
  12  * Copyright (c) 2002-5 Patrick Mochel
  13  * Copyright (c) 2002-3 Open Source Development Labs
  14  * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
  15  * Copyright (c) 2007-2009 Novell Inc.
  16  *
  17  * This file is released under the GPLv2
  18  */
  19
  20 #include <linux/device.h>
  21 #include <linux/delay.h>
  22 #include <linux/module.h>
  23 #include <linux/kthread.h>
  24 #include <linux/wait.h>
  25 #include <linux/async.h>
  26 #include <linux/pm_runtime.h>
  27 #include <linux/pinctrl/devinfo.h>
  28
  29 #include "base.h"
  30 #include "power/power.h"
  31
  32 /*
  33  * Deferred Probe infrastructure.
  34  *
  35  * Sometimes driver probe order matters, but the kernel doesn't always have
  36  * dependency information which means some drivers will get probed before a
  37  * resource it depends on is available.  For example, an SDHCI driver may
  38  * first need a GPIO line from an i2c GPIO controller before it can be
  39  * initialized.  If a required resource is not available yet, a driver can
  40  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  41  *
  42  * Deferred probe maintains two lists of devices, a pending list and an active
  43  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  44  * pending list.  A successful driver probe will trigger moving all devices
  45  * from the pending to the active list so that the workqueue will eventually
  46  * retry them.
  47  *
  48  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  49  * of the (struct device*)->p->deferred_probe pointers are manipulated
  50  */
  51 static DEFINE_MUTEX(deferred_probe_mutex);
  52 static LIST_HEAD(deferred_probe_pending_list);
  53 static LIST_HEAD(deferred_probe_active_list);
  54 static struct workqueue_struct *deferred_wq;
  55 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
  56
  57 /*
  58  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  59  * to prohibit probing of devices as it could be unsafe.
  60  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  61  */
  62 static bool defer_all_probes;
  63
  64 /*
  65  * deferred_probe_work_func() - Retry probing devices in the active list.
  66  */
  67 static void deferred_probe_work_func(struct work_struct *work)
  68 {
  69         struct device *dev;
  70         struct device_private *private;
  71         /*
  72          * This block processes every device in the deferred 'active' list.
  73          * Each device is removed from the active list and passed to
  74          * bus_probe_device() to re-attempt the probe.  The loop continues
  75          * until every device in the active list is removed and retried.
  76          *
  77          * Note: Once the device is removed from the list and the mutex is
  78          * released, it is possible for the device get freed by another thread
  79          * and cause a illegal pointer dereference.  This code uses
  80          * get/put_device() to ensure the device structure cannot disappear
  81          * from under our feet.
  82          */
  83         mutex_lock(&deferred_probe_mutex);
  84         while (!list_empty(&deferred_probe_active_list)) {
  85                 private = list_first_entry(&deferred_probe_active_list,
  86                                         typeof(*dev->p), deferred_probe);
  87                 dev = private->device;
  88                 list_del_init(&private->deferred_probe);
  89
  90                 get_device(dev);
  91
  92                 /*
  93                  * Drop the mutex while probing each device; the probe path may
  94                  * manipulate the deferred list
  95                  */
  96                 mutex_unlock(&deferred_probe_mutex);
  97
  98                 /*
  99                  * Force the device to the end of the dpm_list since
 100                  * the PM code assumes that the order we add things to
 101                  * the list is a good order for suspend but deferred
 102                  * probe makes that very unsafe.
 103                  */
 104                 device_pm_lock();
 105                 device_pm_move_last(dev);
 106                 device_pm_unlock();
 107
 108                 dev_dbg(dev, "Retrying from deferred list\n");
 109                 bus_probe_device(dev);
 110
 111                 mutex_lock(&deferred_probe_mutex);
 112
 113                 put_device(dev);
 114         }
 115         mutex_unlock(&deferred_probe_mutex);
 116 }
 117 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 118
 119 static void driver_deferred_probe_add(struct device *dev)
 120 {
 121         mutex_lock(&deferred_probe_mutex);
 122         if (list_empty(&dev->p->deferred_probe)) {
 123                 dev_dbg(dev, "Added to deferred list\n");
 124                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 125         }
 126         mutex_unlock(&deferred_probe_mutex);
 127 }
 128
 129 void driver_deferred_probe_del(struct device *dev)
 130 {
 131         mutex_lock(&deferred_probe_mutex);
 132         if (!list_empty(&dev->p->deferred_probe)) {
 133                 dev_dbg(dev, "Removed from deferred list\n");
 134                 list_del_init(&dev->p->deferred_probe);
 135         }
 136         mutex_unlock(&deferred_probe_mutex);
 137 }
 138
 139 static bool driver_deferred_probe_enable = false;
 140 /**
 141  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 142  *
 143  * This functions moves all devices from the pending list to the active
 144  * list and schedules the deferred probe workqueue to process them.  It
 145  * should be called anytime a driver is successfully bound to a device.
 146  *
 147  * Note, there is a race condition in multi-threaded probe. In the case where
 148  * more than one device is probing at the same time, it is possible for one
 149  * probe to complete successfully while another is about to defer. If the second
 150  * depends on the first, then it will get put on the pending list after the
 151  * trigger event has already occurred and will be stuck there.
 152  *
 153  * The atomic 'deferred_trigger_count' is used to determine if a successful
 154  * trigger has occurred in the midst of probing a driver. If the trigger count
 155  * changes in the midst of a probe, then deferred processing should be triggered
 156  * again.
 157  */
 158 static void driver_deferred_probe_trigger(void)
 159 {
 160         if (!driver_deferred_probe_enable)
 161                 return;
 162
 163         /*
 164          * A successful probe means that all the devices in the pending list
 165          * should be triggered to be reprobed.  Move all the deferred devices
 166          * into the active list so they can be retried by the workqueue
 167          */
 168         mutex_lock(&deferred_probe_mutex);
 169         atomic_inc(&deferred_trigger_count);
 170         list_splice_tail_init(&deferred_probe_pending_list,
 171                               &deferred_probe_active_list);
 172         mutex_unlock(&deferred_probe_mutex);
 173
 174         /*
 175          * Kick the re-probe thread.  It may already be scheduled, but it is
 176          * safe to kick it again.
 177          */
 178         queue_work(deferred_wq, &deferred_probe_work);
 179 }
 180
 181 /**
 182  * device_block_probing() - Block/defere device's probes
 183  *
 184  *      It will disable probing of devices and defer their probes instead.
 185  */
 186 void device_block_probing(void)
 187 {
 188         defer_all_probes = true;
 189         /* sync with probes to avoid races. */
 190         wait_for_device_probe();
 191 }
 192
 193 /**
 194  * device_unblock_probing() - Unblock/enable device's probes
 195  *
 196  *      It will restore normal behavior and trigger re-probing of deferred
 197  * devices.
 198  */
 199 void device_unblock_probing(void)
 200 {
 201         defer_all_probes = false;
 202         driver_deferred_probe_trigger();
 203 }
 204
 205 /**
 206  * deferred_probe_initcall() - Enable probing of deferred devices
 207  *
 208  * We don't want to get in the way when the bulk of drivers are getting probed.
 209  * Instead, this initcall makes sure that deferred probing is delayed until
 210  * late_initcall time.
 211  */
 212 static int deferred_probe_initcall(void)
 213 {
 214         deferred_wq = create_singlethread_workqueue("deferwq");
 215         if (WARN_ON(!deferred_wq))
 216                 return -ENOMEM;
 217
 218         driver_deferred_probe_enable = true;
 219         driver_deferred_probe_trigger();
 220         /* Sort as many dependencies as possible before exiting initcalls */
 221         flush_workqueue(deferred_wq);
 222         return 0;
 223 }
 224 late_initcall(deferred_probe_initcall);
 225
 226 static void driver_bound(struct device *dev)
 227 {
 228         if (klist_node_attached(&dev->p->knode_driver)) {
 229                 printk(KERN_WARNING "%s: device %s already bound\n",
 230                         __func__, kobject_name(&dev->kobj));
 231                 return;
 232         }
 233
 234         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 235                  __func__, dev_name(dev));
 236
 237         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 238
 239         /*
 240          * Make sure the device is no longer in one of the deferred lists and
 241          * kick off retrying all pending devices
 242          */
 243         driver_deferred_probe_del(dev);
 244         driver_deferred_probe_trigger();
 245
 246         if (dev->bus)
 247                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 248                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 249 }
 250
 251 static int driver_sysfs_add(struct device *dev)
 252 {
 253         int ret;
 254
 255         if (dev->bus)
 256                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 257                                              BUS_NOTIFY_BIND_DRIVER, dev);
 258
 259         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 260                           kobject_name(&dev->kobj));
 261         if (ret == 0) {
 262                 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 263                                         "driver");
 264                 if (ret)
 265                         sysfs_remove_link(&dev->driver->p->kobj,
 266                                         kobject_name(&dev->kobj));
 267         }
 268         return ret;
 269 }
 270
 271 static void driver_sysfs_remove(struct device *dev)
 272 {
 273         struct device_driver *drv = dev->driver;
 274
 275         if (drv) {
 276                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 277                 sysfs_remove_link(&dev->kobj, "driver");
 278         }
 279 }
 280
 281 /**
 282  * device_bind_driver - bind a driver to one device.
 283  * @dev: device.
 284  *
 285  * Allow manual attachment of a driver to a device.
 286  * Caller must have already set @dev->driver.
 287  *
 288  * Note that this does not modify the bus reference count
 289  * nor take the bus's rwsem. Please verify those are accounted
 290  * for before calling this. (It is ok to call with no other effort
 291  * from a driver's probe() method.)
 292  *
 293  * This function must be called with the device lock held.
 294  */
 295 int device_bind_driver(struct device *dev)
 296 {
 297         int ret;
 298
 299         ret = driver_sysfs_add(dev);
 300         if (!ret)
 301                 driver_bound(dev);
 302         else if (dev->bus)
 303                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 304                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 305         return ret;
 306 }
 307 EXPORT_SYMBOL_GPL(device_bind_driver);
 308
 309 static atomic_t probe_count = ATOMIC_INIT(0);
 310 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 311
 312 static int really_probe(struct device *dev, struct device_driver *drv)
 313 {
 314         int ret = -EPROBE_DEFER;
 315         int local_trigger_count = atomic_read(&deferred_trigger_count);
 316
 317         if (defer_all_probes) {
 318                 /*
 319                  * Value of defer_all_probes can be set only by
 320                  * device_defer_all_probes_enable() which, in turn, will call
 321                  * wait_for_device_probe() right after that to avoid any races.
 322                  */
 323                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 324                 driver_deferred_probe_add(dev);
 325                 return ret;
 326         }
 327
 328         atomic_inc(&probe_count);
 329         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 330                  drv->bus->name, __func__, drv->name, dev_name(dev));
 331         WARN_ON(!list_empty(&dev->devres_head));
 332
 333         dev->driver = drv;
 334
 335         /* If using pinctrl, bind pins now before probing */
 336         ret = pinctrl_bind_pins(dev);
 337         if (ret)
 338                 goto pinctrl_bind_failed;
 339
 340         if (driver_sysfs_add(dev)) {
 341                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 342                         __func__, dev_name(dev));
 343                 goto probe_failed;
 344         }
 345
 346         if (dev->pm_domain && dev->pm_domain->activate) {
 347                 ret = dev->pm_domain->activate(dev);
 348                 if (ret)
 349                         goto probe_failed;
 350         }
 351
 352         /*
 353          * Ensure devices are listed in devices_kset in correct order
 354          * It's important to move Dev to the end of devices_kset before
 355          * calling .probe, because it could be recursive and parent Dev
 356          * should always go first
 357          */
 358         devices_kset_move_last(dev);
 359
 360         if (dev->bus->probe) {
 361                 ret = dev->bus->probe(dev);
 362                 if (ret)
 363                         goto probe_failed;
 364         } else if (drv->probe) {
 365                 ret = drv->probe(dev);
 366                 if (ret)
 367                         goto probe_failed;
 368         }
 369
 370         pinctrl_init_done(dev);
 371
 372         if (dev->pm_domain && dev->pm_domain->sync)
 373                 dev->pm_domain->sync(dev);
 374
 375         driver_bound(dev);
 376         ret = 1;
 377         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 378                  drv->bus->name, __func__, dev_name(dev), drv->name);
 379         goto done;
 380
 381 probe_failed:
 382         if (dev->bus)
 383                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 384                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 385 pinctrl_bind_failed:
 386         devres_release_all(dev);
 387         driver_sysfs_remove(dev);
 388         dev->driver = NULL;
 389         dev_set_drvdata(dev, NULL);
 390         if (dev->pm_domain && dev->pm_domain->dismiss)
 391                 dev->pm_domain->dismiss(dev);
 392         pm_runtime_reinit(dev);
 393
 394         switch (ret) {
 395         case -EPROBE_DEFER:
 396                 /* Driver requested deferred probing */
 397                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 398                 driver_deferred_probe_add(dev);
 399                 /* Did a trigger occur while probing? Need to re-trigger if yes */
 400                 if (local_trigger_count != atomic_read(&deferred_trigger_count))
 401                         driver_deferred_probe_trigger();
 402                 break;
 403         case -ENODEV:
 404         case -ENXIO:
 405                 pr_debug("%s: probe of %s rejects match %d\n",
 406                          drv->name, dev_name(dev), ret);
 407                 break;
 408         default:
 409                 /* driver matched but the probe failed */
 410                 printk(KERN_WARNING
 411                        "%s: probe of %s failed with error %d\n",
 412                        drv->name, dev_name(dev), ret);
 413         }
 414         /*
 415          * Ignore errors returned by ->probe so that the next driver can try
 416          * its luck.
 417          */
 418         ret = 0;
 419 done:
 420         atomic_dec(&probe_count);
 421         wake_up(&probe_waitqueue);
 422         return ret;
 423 }
 424
 425 /**
 426  * driver_probe_done
 427  * Determine if the probe sequence is finished or not.
 428  *
 429  * Should somehow figure out how to use a semaphore, not an atomic variable...
 430  */
 431 int driver_probe_done(void)
 432 {
 433         pr_debug("%s: probe_count = %d\n", __func__,
 434                  atomic_read(&probe_count));
 435         if (atomic_read(&probe_count))
 436                 return -EBUSY;
 437         return 0;
 438 }
 439
 440 /**
 441  * wait_for_device_probe
 442  * Wait for device probing to be completed.
 443  */
 444 void wait_for_device_probe(void)
 445 {
 446         /* wait for the deferred probe workqueue to finish */
 447         if (driver_deferred_probe_enable)
 448                 flush_workqueue(deferred_wq);
 449
 450         /* wait for the known devices to complete their probing */
 451         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 452         async_synchronize_full();
 453 }
 454 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 455
 456 /**
 457  * driver_probe_device - attempt to bind device & driver together
 458  * @drv: driver to bind a device to
 459  * @dev: device to try to bind to the driver
 460  *
 461  * This function returns -ENODEV if the device is not registered,
 462  * 1 if the device is bound successfully and 0 otherwise.
 463  *
 464  * This function must be called with @dev lock held.  When called for a
 465  * USB interface, @dev->parent lock must be held as well.
 466  *
 467  * If the device has a parent, runtime-resume the parent before driver probing.
 468  */
 469 int driver_probe_device(struct device_driver *drv, struct device *dev)
 470 {
 471         int ret = 0;
 472
 473         if (!device_is_registered(dev))
 474                 return -ENODEV;
 475
 476         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 477                  drv->bus->name, __func__, dev_name(dev), drv->name);
 478
 479         if (dev->parent)
 480                 pm_runtime_get_sync(dev->parent);
 481
 482         pm_runtime_barrier(dev);
 483         ret = really_probe(dev, drv);
 484         pm_request_idle(dev);
 485
 486         if (dev->parent)
 487                 pm_runtime_put(dev->parent);
 488
 489         return ret;
 490 }
 491
 492 bool driver_allows_async_probing(struct device_driver *drv)
 493 {
 494         switch (drv->probe_type) {
 495         case PROBE_PREFER_ASYNCHRONOUS:
 496                 return true;
 497
 498         case PROBE_FORCE_SYNCHRONOUS:
 499                 return false;
 500
 501         default:
 502                 if (module_requested_async_probing(drv->owner))
 503                         return true;
 504
 505                 return false;
 506         }
 507 }
 508
 509 struct device_attach_data {
 510         struct device *dev;
 511
 512         /*
 513          * Indicates whether we are are considering asynchronous probing or
 514          * not. Only initial binding after device or driver registration
 515          * (including deferral processing) may be done asynchronously, the
 516          * rest is always synchronous, as we expect it is being done by
 517          * request from userspace.
 518          */
 519         bool check_async;
 520
 521         /*
 522          * Indicates if we are binding synchronous or asynchronous drivers.
 523          * When asynchronous probing is enabled we'll execute 2 passes
 524          * over drivers: first pass doing synchronous probing and second
 525          * doing asynchronous probing (if synchronous did not succeed -
 526          * most likely because there was no driver requiring synchronous
 527          * probing - and we found asynchronous driver during first pass).
 528          * The 2 passes are done because we can't shoot asynchronous
 529          * probe for given device and driver from bus_for_each_drv() since
 530          * driver pointer is not guaranteed to stay valid once
 531          * bus_for_each_drv() iterates to the next driver on the bus.
 532          */
 533         bool want_async;
 534
 535         /*
 536          * We'll set have_async to 'true' if, while scanning for matching
 537          * driver, we'll encounter one that requests asynchronous probing.
 538          */
 539         bool have_async;
 540 };
 541
 542 static int __device_attach_driver(struct device_driver *drv, void *_data)
 543 {
 544         struct device_attach_data *data = _data;
 545         struct device *dev = data->dev;
 546         bool async_allowed;
 547
 548         /*
 549          * Check if device has already been claimed. This may
 550          * happen with driver loading, device discovery/registration,
 551          * and deferred probe processing happens all at once with
 552          * multiple threads.
 553          */
 554         if (dev->driver)
 555                 return -EBUSY;
 556
 557         if (!driver_match_device(drv, dev))
 558                 return 0;
 559
 560         async_allowed = driver_allows_async_probing(drv);
 561
 562         if (async_allowed)
 563                 data->have_async = true;
 564
 565         if (data->check_async && async_allowed != data->want_async)
 566                 return 0;
 567
 568         return driver_probe_device(drv, dev);
 569 }
 570
 571 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 572 {
 573         struct device *dev = _dev;
 574         struct device_attach_data data = {
 575                 .dev            = dev,
 576                 .check_async    = true,
 577                 .want_async     = true,
 578         };
 579
 580         device_lock(dev);
 581
 582         if (dev->parent)
 583                 pm_runtime_get_sync(dev->parent);
 584
 585         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 586         dev_dbg(dev, "async probe completed\n");
 587
 588         pm_request_idle(dev);
 589
 590         if (dev->parent)
 591                 pm_runtime_put(dev->parent);
 592
 593         device_unlock(dev);
 594
 595         put_device(dev);
 596 }
 597
 598 static int __device_attach(struct device *dev, bool allow_async)
 599 {
 600         int ret = 0;
 601
 602         device_lock(dev);
 603         if (dev->driver) {
 604                 if (klist_node_attached(&dev->p->knode_driver)) {
 605                         ret = 1;
 606                         goto out_unlock;
 607                 }
 608                 ret = device_bind_driver(dev);
 609                 if (ret == 0)
 610                         ret = 1;
 611                 else {
 612                         dev->driver = NULL;
 613                         ret = 0;
 614                 }
 615         } else {
 616                 struct device_attach_data data = {
 617                         .dev = dev,
 618                         .check_async = allow_async,
 619                         .want_async = false,
 620                 };
 621
 622                 if (dev->parent)
 623                         pm_runtime_get_sync(dev->parent);
 624
 625                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 626                                         __device_attach_driver);
 627                 if (!ret && allow_async && data.have_async) {
 628                         /*
 629                          * If we could not find appropriate driver
 630                          * synchronously and we are allowed to do
 631                          * async probes and there are drivers that
 632                          * want to probe asynchronously, we'll
 633                          * try them.
 634                          */
 635                         dev_dbg(dev, "scheduling asynchronous probe\n");
 636                         get_device(dev);
 637                         async_schedule(__device_attach_async_helper, dev);
 638                 } else {
 639                         pm_request_idle(dev);
 640                 }
 641
 642                 if (dev->parent)
 643                         pm_runtime_put(dev->parent);
 644         }
 645 out_unlock:
 646         device_unlock(dev);
 647         return ret;
 648 }
 649
 650 /**
 651  * device_attach - try to attach device to a driver.
 652  * @dev: device.
 653  *
 654  * Walk the list of drivers that the bus has and call
 655  * driver_probe_device() for each pair. If a compatible
 656  * pair is found, break out and return.
 657  *
 658  * Returns 1 if the device was bound to a driver;
 659  * 0 if no matching driver was found;
 660  * -ENODEV if the device is not registered.
 661  *
 662  * When called for a USB interface, @dev->parent lock must be held.
 663  */
 664 int device_attach(struct device *dev)
 665 {
 666         return __device_attach(dev, false);
 667 }
 668 EXPORT_SYMBOL_GPL(device_attach);
 669
 670 void device_initial_probe(struct device *dev)
 671 {
 672         __device_attach(dev, true);
 673 }
 674
 675 static int __driver_attach(struct device *dev, void *data)
 676 {
 677         struct device_driver *drv = data;
 678
 679         /*
 680          * Lock device and try to bind to it. We drop the error
 681          * here and always return 0, because we need to keep trying
 682          * to bind to devices and some drivers will return an error
 683          * simply if it didn't support the device.
 684          *
 685          * driver_probe_device() will spit a warning if there
 686          * is an error.
 687          */
 688
 689         if (!driver_match_device(drv, dev))
 690                 return 0;
 691
 692         if (dev->parent)        /* Needed for USB */
 693                 device_lock(dev->parent);
 694         device_lock(dev);
 695         if (!dev->driver)
 696                 driver_probe_device(drv, dev);
 697         device_unlock(dev);
 698         if (dev->parent)
 699                 device_unlock(dev->parent);
 700
 701         return 0;
 702 }
 703
 704 /**
 705  * driver_attach - try to bind driver to devices.
 706  * @drv: driver.
 707  *
 708  * Walk the list of devices that the bus has on it and try to
 709  * match the driver with each one.  If driver_probe_device()
 710  * returns 0 and the @dev->driver is set, we've found a
 711  * compatible pair.
 712  */
 713 int driver_attach(struct device_driver *drv)
 714 {
 715         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 716 }
 717 EXPORT_SYMBOL_GPL(driver_attach);
 718
 719 /*
 720  * __device_release_driver() must be called with @dev lock held.
 721  * When called for a USB interface, @dev->parent lock must be held as well.
 722  */
 723 static void __device_release_driver(struct device *dev)
 724 {
 725         struct device_driver *drv;
 726
 727         drv = dev->driver;
 728         if (drv) {
 729                 if (driver_allows_async_probing(drv))
 730                         async_synchronize_full();
 731
 732                 pm_runtime_get_sync(dev);
 733
 734                 driver_sysfs_remove(dev);
 735
 736                 if (dev->bus)
 737                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 738                                                      BUS_NOTIFY_UNBIND_DRIVER,
 739                                                      dev);
 740
 741                 pm_runtime_put_sync(dev);
 742
 743                 if (dev->bus && dev->bus->remove)
 744                         dev->bus->remove(dev);
 745                 else if (drv->remove)
 746                         drv->remove(dev);
 747                 devres_release_all(dev);
 748                 dev->driver = NULL;
 749                 dev_set_drvdata(dev, NULL);
 750                 if (dev->pm_domain && dev->pm_domain->dismiss)
 751                         dev->pm_domain->dismiss(dev);
 752                 pm_runtime_reinit(dev);
 753
 754                 klist_remove(&dev->p->knode_driver);
 755                 if (dev->bus)
 756                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 757                                                      BUS_NOTIFY_UNBOUND_DRIVER,
 758                                                      dev);
 759         }
 760 }
 761
 762 /**
 763  * device_release_driver - manually detach device from driver.
 764  * @dev: device.
 765  *
 766  * Manually detach device from driver.
 767  * When called for a USB interface, @dev->parent lock must be held.
 768  */
 769 void device_release_driver(struct device *dev)
 770 {
 771         /*
 772          * If anyone calls device_release_driver() recursively from
 773          * within their ->remove callback for the same device, they
 774          * will deadlock right here.
 775          */
 776         device_lock(dev);
 777         __device_release_driver(dev);
 778         device_unlock(dev);
 779 }
 780 EXPORT_SYMBOL_GPL(device_release_driver);
 781
 782 /**
 783  * driver_detach - detach driver from all devices it controls.
 784  * @drv: driver.
 785  */
 786 void driver_detach(struct device_driver *drv)
 787 {
 788         struct device_private *dev_prv;
 789         struct device *dev;
 790
 791         for (;;) {
 792                 spin_lock(&drv->p->klist_devices.k_lock);
 793                 if (list_empty(&drv->p->klist_devices.k_list)) {
 794                         spin_unlock(&drv->p->klist_devices.k_lock);
 795                         break;
 796                 }
 797                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
 798                                      struct device_private,
 799                                      knode_driver.n_node);
 800                 dev = dev_prv->device;
 801                 get_device(dev);
 802                 spin_unlock(&drv->p->klist_devices.k_lock);
 803
 804                 if (dev->parent)        /* Needed for USB */
 805                         device_lock(dev->parent);
 806                 device_lock(dev);
 807                 if (dev->driver == drv)
 808                         __device_release_driver(dev);
 809                 device_unlock(dev);
 810                 if (dev->parent)
 811                         device_unlock(dev->parent);
 812                 put_device(dev);
 813         }
 814 }