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/dma-mapping.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/kthread.h>
  26 #include <linux/wait.h>
  27 #include <linux/async.h>
  28 #include <linux/pm_runtime.h>
  29 #include <linux/pinctrl/devinfo.h>
  30
  31 #include "base.h"
  32 #include "power/power.h"
  33
  34 /*
  35  * Deferred Probe infrastructure.
  36  *
  37  * Sometimes driver probe order matters, but the kernel doesn't always have
  38  * dependency information which means some drivers will get probed before a
  39  * resource it depends on is available.  For example, an SDHCI driver may
  40  * first need a GPIO line from an i2c GPIO controller before it can be
  41  * initialized.  If a required resource is not available yet, a driver can
  42  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  43  *
  44  * Deferred probe maintains two lists of devices, a pending list and an active
  45  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  46  * pending list.  A successful driver probe will trigger moving all devices
  47  * from the pending to the active list so that the workqueue will eventually
  48  * retry them.
  49  *
  50  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  51  * of the (struct device*)->p->deferred_probe pointers are manipulated
  52  */
  53 static DEFINE_MUTEX(deferred_probe_mutex);
  54 static LIST_HEAD(deferred_probe_pending_list);
  55 static LIST_HEAD(deferred_probe_active_list);
  56 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
  57 static bool initcalls_done;
  58
  59 /*
  60  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  61  * to prohibit probing of devices as it could be unsafe.
  62  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  63  */
  64 static bool defer_all_probes;
  65
  66 /*
  67  * For initcall_debug, show the deferred probes executed in late_initcall
  68  * processing.
  69  */
  70 static void deferred_probe_debug(struct device *dev)
  71 {
  72         ktime_t calltime, delta, rettime;
  73         unsigned long long duration;
  74
  75         printk(KERN_DEBUG "deferred probe %s @ %i\n", dev_name(dev),
  76                task_pid_nr(current));
  77         calltime = ktime_get();
  78         bus_probe_device(dev);
  79         rettime = ktime_get();
  80         delta = ktime_sub(rettime, calltime);
  81         duration = (unsigned long long) ktime_to_ns(delta) >> 10;
  82         printk(KERN_DEBUG "deferred probe %s returned after %lld usecs\n",
  83                dev_name(dev), duration);
  84 }
  85
  86 /*
  87  * deferred_probe_work_func() - Retry probing devices in the active list.
  88  */
  89 static void deferred_probe_work_func(struct work_struct *work)
  90 {
  91         struct device *dev;
  92         struct device_private *private;
  93         /*
  94          * This block processes every device in the deferred 'active' list.
  95          * Each device is removed from the active list and passed to
  96          * bus_probe_device() to re-attempt the probe.  The loop continues
  97          * until every device in the active list is removed and retried.
  98          *
  99          * Note: Once the device is removed from the list and the mutex is
 100          * released, it is possible for the device get freed by another thread
 101          * and cause a illegal pointer dereference.  This code uses
 102          * get/put_device() to ensure the device structure cannot disappear
 103          * from under our feet.
 104          */
 105         mutex_lock(&deferred_probe_mutex);
 106         while (!list_empty(&deferred_probe_active_list)) {
 107                 private = list_first_entry(&deferred_probe_active_list,
 108                                         typeof(*dev->p), deferred_probe);
 109                 dev = private->device;
 110                 list_del_init(&private->deferred_probe);
 111
 112                 get_device(dev);
 113
 114                 /*
 115                  * Drop the mutex while probing each device; the probe path may
 116                  * manipulate the deferred list
 117                  */
 118                 mutex_unlock(&deferred_probe_mutex);
 119
 120                 /*
 121                  * Force the device to the end of the dpm_list since
 122                  * the PM code assumes that the order we add things to
 123                  * the list is a good order for suspend but deferred
 124                  * probe makes that very unsafe.
 125                  */
 126                 device_pm_lock();
 127                 device_pm_move_last(dev);
 128                 device_pm_unlock();
 129
 130                 dev_dbg(dev, "Retrying from deferred list\n");
 131                 if (initcall_debug && !initcalls_done)
 132                         deferred_probe_debug(dev);
 133                 else
 134                         bus_probe_device(dev);
 135
 136                 mutex_lock(&deferred_probe_mutex);
 137
 138                 put_device(dev);
 139         }
 140         mutex_unlock(&deferred_probe_mutex);
 141 }
 142 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 143
 144 static void driver_deferred_probe_add(struct device *dev)
 145 {
 146         mutex_lock(&deferred_probe_mutex);
 147         if (list_empty(&dev->p->deferred_probe)) {
 148                 dev_dbg(dev, "Added to deferred list\n");
 149                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 150         }
 151         mutex_unlock(&deferred_probe_mutex);
 152 }
 153
 154 void driver_deferred_probe_del(struct device *dev)
 155 {
 156         mutex_lock(&deferred_probe_mutex);
 157         if (!list_empty(&dev->p->deferred_probe)) {
 158                 dev_dbg(dev, "Removed from deferred list\n");
 159                 list_del_init(&dev->p->deferred_probe);
 160         }
 161         mutex_unlock(&deferred_probe_mutex);
 162 }
 163
 164 static bool driver_deferred_probe_enable = false;
 165 /**
 166  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 167  *
 168  * This functions moves all devices from the pending list to the active
 169  * list and schedules the deferred probe workqueue to process them.  It
 170  * should be called anytime a driver is successfully bound to a device.
 171  *
 172  * Note, there is a race condition in multi-threaded probe. In the case where
 173  * more than one device is probing at the same time, it is possible for one
 174  * probe to complete successfully while another is about to defer. If the second
 175  * depends on the first, then it will get put on the pending list after the
 176  * trigger event has already occurred and will be stuck there.
 177  *
 178  * The atomic 'deferred_trigger_count' is used to determine if a successful
 179  * trigger has occurred in the midst of probing a driver. If the trigger count
 180  * changes in the midst of a probe, then deferred processing should be triggered
 181  * again.
 182  */
 183 static void driver_deferred_probe_trigger(void)
 184 {
 185         if (!driver_deferred_probe_enable)
 186                 return;
 187
 188         /*
 189          * A successful probe means that all the devices in the pending list
 190          * should be triggered to be reprobed.  Move all the deferred devices
 191          * into the active list so they can be retried by the workqueue
 192          */
 193         mutex_lock(&deferred_probe_mutex);
 194         atomic_inc(&deferred_trigger_count);
 195         list_splice_tail_init(&deferred_probe_pending_list,
 196                               &deferred_probe_active_list);
 197         mutex_unlock(&deferred_probe_mutex);
 198
 199         /*
 200          * Kick the re-probe thread.  It may already be scheduled, but it is
 201          * safe to kick it again.
 202          */
 203         schedule_work(&deferred_probe_work);
 204 }
 205
 206 /**
 207  * device_block_probing() - Block/defere device's probes
 208  *
 209  *      It will disable probing of devices and defer their probes instead.
 210  */
 211 void device_block_probing(void)
 212 {
 213         defer_all_probes = true;
 214         /* sync with probes to avoid races. */
 215         wait_for_device_probe();
 216 }
 217
 218 /**
 219  * device_unblock_probing() - Unblock/enable device's probes
 220  *
 221  *      It will restore normal behavior and trigger re-probing of deferred
 222  * devices.
 223  */
 224 void device_unblock_probing(void)
 225 {
 226         defer_all_probes = false;
 227         driver_deferred_probe_trigger();
 228 }
 229
 230 /**
 231  * deferred_probe_initcall() - Enable probing of deferred devices
 232  *
 233  * We don't want to get in the way when the bulk of drivers are getting probed.
 234  * Instead, this initcall makes sure that deferred probing is delayed until
 235  * late_initcall time.
 236  */
 237 static int deferred_probe_initcall(void)
 238 {
 239         driver_deferred_probe_enable = true;
 240         driver_deferred_probe_trigger();
 241         /* Sort as many dependencies as possible before exiting initcalls */
 242         flush_work(&deferred_probe_work);
 243         initcalls_done = true;
 244         return 0;
 245 }
 246 late_initcall(deferred_probe_initcall);
 247
 248 /**
 249  * device_is_bound() - Check if device is bound to a driver
 250  * @dev: device to check
 251  *
 252  * Returns true if passed device has already finished probing successfully
 253  * against a driver.
 254  *
 255  * This function must be called with the device lock held.
 256  */
 257 bool device_is_bound(struct device *dev)
 258 {
 259         return dev->p && klist_node_attached(&dev->p->knode_driver);
 260 }
 261
 262 static void driver_bound(struct device *dev)
 263 {
 264         if (device_is_bound(dev)) {
 265                 printk(KERN_WARNING "%s: device %s already bound\n",
 266                         __func__, kobject_name(&dev->kobj));
 267                 return;
 268         }
 269
 270         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 271                  __func__, dev_name(dev));
 272
 273         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 274         device_links_driver_bound(dev);
 275
 276         device_pm_check_callbacks(dev);
 277
 278         /*
 279          * Make sure the device is no longer in one of the deferred lists and
 280          * kick off retrying all pending devices
 281          */
 282         driver_deferred_probe_del(dev);
 283         driver_deferred_probe_trigger();
 284
 285         if (dev->bus)
 286                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 287                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 288
 289         kobject_uevent(&dev->kobj, KOBJ_BIND);
 290 }
 291
 292 static int driver_sysfs_add(struct device *dev)
 293 {
 294         int ret;
 295
 296         if (dev->bus)
 297                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 298                                              BUS_NOTIFY_BIND_DRIVER, dev);
 299
 300         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 301                           kobject_name(&dev->kobj));
 302         if (ret == 0) {
 303                 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 304                                         "driver");
 305                 if (ret)
 306                         sysfs_remove_link(&dev->driver->p->kobj,
 307                                         kobject_name(&dev->kobj));
 308         }
 309         return ret;
 310 }
 311
 312 static void driver_sysfs_remove(struct device *dev)
 313 {
 314         struct device_driver *drv = dev->driver;
 315
 316         if (drv) {
 317                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 318                 sysfs_remove_link(&dev->kobj, "driver");
 319         }
 320 }
 321
 322 /**
 323  * device_bind_driver - bind a driver to one device.
 324  * @dev: device.
 325  *
 326  * Allow manual attachment of a driver to a device.
 327  * Caller must have already set @dev->driver.
 328  *
 329  * Note that this does not modify the bus reference count
 330  * nor take the bus's rwsem. Please verify those are accounted
 331  * for before calling this. (It is ok to call with no other effort
 332  * from a driver's probe() method.)
 333  *
 334  * This function must be called with the device lock held.
 335  */
 336 int device_bind_driver(struct device *dev)
 337 {
 338         int ret;
 339
 340         ret = driver_sysfs_add(dev);
 341         if (!ret)
 342                 driver_bound(dev);
 343         else if (dev->bus)
 344                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 345                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 346         return ret;
 347 }
 348 EXPORT_SYMBOL_GPL(device_bind_driver);
 349
 350 static atomic_t probe_count = ATOMIC_INIT(0);
 351 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 352
 353 static void driver_deferred_probe_add_trigger(struct device *dev,
 354                                               int local_trigger_count)
 355 {
 356         driver_deferred_probe_add(dev);
 357         /* Did a trigger occur while probing? Need to re-trigger if yes */
 358         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 359                 driver_deferred_probe_trigger();
 360 }
 361
 362 static int really_probe(struct device *dev, struct device_driver *drv)
 363 {
 364         int ret = -EPROBE_DEFER;
 365         int local_trigger_count = atomic_read(&deferred_trigger_count);
 366         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 367                            !drv->suppress_bind_attrs;
 368
 369         if (defer_all_probes) {
 370                 /*
 371                  * Value of defer_all_probes can be set only by
 372                  * device_defer_all_probes_enable() which, in turn, will call
 373                  * wait_for_device_probe() right after that to avoid any races.
 374                  */
 375                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 376                 driver_deferred_probe_add(dev);
 377                 return ret;
 378         }
 379
 380         ret = device_links_check_suppliers(dev);
 381         if (ret == -EPROBE_DEFER)
 382                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 383         if (ret)
 384                 return ret;
 385
 386         atomic_inc(&probe_count);
 387         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 388                  drv->bus->name, __func__, drv->name, dev_name(dev));
 389         WARN_ON(!list_empty(&dev->devres_head));
 390
 391 re_probe:
 392         dev->driver = drv;
 393
 394         /* If using pinctrl, bind pins now before probing */
 395         ret = pinctrl_bind_pins(dev);
 396         if (ret)
 397                 goto pinctrl_bind_failed;
 398
 399         ret = dma_configure(dev);
 400         if (ret)
 401                 goto dma_failed;
 402
 403         if (driver_sysfs_add(dev)) {
 404                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 405                         __func__, dev_name(dev));
 406                 goto probe_failed;
 407         }
 408
 409         if (dev->pm_domain && dev->pm_domain->activate) {
 410                 ret = dev->pm_domain->activate(dev);
 411                 if (ret)
 412                         goto probe_failed;
 413         }
 414
 415         /*
 416          * Ensure devices are listed in devices_kset in correct order
 417          * It's important to move Dev to the end of devices_kset before
 418          * calling .probe, because it could be recursive and parent Dev
 419          * should always go first
 420          */
 421         devices_kset_move_last(dev);
 422
 423         if (dev->bus->probe) {
 424                 ret = dev->bus->probe(dev);
 425                 if (ret)
 426                         goto probe_failed;
 427         } else if (drv->probe) {
 428                 ret = drv->probe(dev);
 429                 if (ret)
 430                         goto probe_failed;
 431         }
 432
 433         if (test_remove) {
 434                 test_remove = false;
 435
 436                 if (dev->bus->remove)
 437                         dev->bus->remove(dev);
 438                 else if (drv->remove)
 439                         drv->remove(dev);
 440
 441                 devres_release_all(dev);
 442                 driver_sysfs_remove(dev);
 443                 dev->driver = NULL;
 444                 dev_set_drvdata(dev, NULL);
 445                 if (dev->pm_domain && dev->pm_domain->dismiss)
 446                         dev->pm_domain->dismiss(dev);
 447                 pm_runtime_reinit(dev);
 448
 449                 goto re_probe;
 450         }
 451
 452         pinctrl_init_done(dev);
 453
 454         if (dev->pm_domain && dev->pm_domain->sync)
 455                 dev->pm_domain->sync(dev);
 456
 457         driver_bound(dev);
 458         ret = 1;
 459         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 460                  drv->bus->name, __func__, dev_name(dev), drv->name);
 461         goto done;
 462
 463 probe_failed:
 464         dma_deconfigure(dev);
 465 dma_failed:
 466         if (dev->bus)
 467                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 468                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 469 pinctrl_bind_failed:
 470         device_links_no_driver(dev);
 471         devres_release_all(dev);
 472         driver_sysfs_remove(dev);
 473         dev->driver = NULL;
 474         dev_set_drvdata(dev, NULL);
 475         if (dev->pm_domain && dev->pm_domain->dismiss)
 476                 dev->pm_domain->dismiss(dev);
 477         pm_runtime_reinit(dev);
 478         dev_pm_set_driver_flags(dev, 0);
 479
 480         switch (ret) {
 481         case -EPROBE_DEFER:
 482                 /* Driver requested deferred probing */
 483                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 484                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 485                 break;
 486         case -ENODEV:
 487         case -ENXIO:
 488                 pr_debug("%s: probe of %s rejects match %d\n",
 489                          drv->name, dev_name(dev), ret);
 490                 break;
 491         default:
 492                 /* driver matched but the probe failed */
 493                 printk(KERN_WARNING
 494                        "%s: probe of %s failed with error %d\n",
 495                        drv->name, dev_name(dev), ret);
 496         }
 497         /*
 498          * Ignore errors returned by ->probe so that the next driver can try
 499          * its luck.
 500          */
 501         ret = 0;
 502 done:
 503         atomic_dec(&probe_count);
 504         wake_up(&probe_waitqueue);
 505         return ret;
 506 }
 507
 508 /**
 509  * driver_probe_done
 510  * Determine if the probe sequence is finished or not.
 511  *
 512  * Should somehow figure out how to use a semaphore, not an atomic variable...
 513  */
 514 int driver_probe_done(void)
 515 {
 516         pr_debug("%s: probe_count = %d\n", __func__,
 517                  atomic_read(&probe_count));
 518         if (atomic_read(&probe_count))
 519                 return -EBUSY;
 520         return 0;
 521 }
 522
 523 /**
 524  * wait_for_device_probe
 525  * Wait for device probing to be completed.
 526  */
 527 void wait_for_device_probe(void)
 528 {
 529         /* wait for the deferred probe workqueue to finish */
 530         flush_work(&deferred_probe_work);
 531
 532         /* wait for the known devices to complete their probing */
 533         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 534         async_synchronize_full();
 535 }
 536 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 537
 538 /**
 539  * driver_probe_device - attempt to bind device & driver together
 540  * @drv: driver to bind a device to
 541  * @dev: device to try to bind to the driver
 542  *
 543  * This function returns -ENODEV if the device is not registered,
 544  * 1 if the device is bound successfully and 0 otherwise.
 545  *
 546  * This function must be called with @dev lock held.  When called for a
 547  * USB interface, @dev->parent lock must be held as well.
 548  *
 549  * If the device has a parent, runtime-resume the parent before driver probing.
 550  */
 551 int driver_probe_device(struct device_driver *drv, struct device *dev)
 552 {
 553         int ret = 0;
 554
 555         if (!device_is_registered(dev))
 556                 return -ENODEV;
 557
 558         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 559                  drv->bus->name, __func__, dev_name(dev), drv->name);
 560
 561         pm_runtime_get_suppliers(dev);
 562         if (dev->parent)
 563                 pm_runtime_get_sync(dev->parent);
 564
 565         pm_runtime_barrier(dev);
 566         ret = really_probe(dev, drv);
 567         pm_request_idle(dev);
 568
 569         if (dev->parent)
 570                 pm_runtime_put(dev->parent);
 571
 572         pm_runtime_put_suppliers(dev);
 573         return ret;
 574 }
 575
 576 bool driver_allows_async_probing(struct device_driver *drv)
 577 {
 578         switch (drv->probe_type) {
 579         case PROBE_PREFER_ASYNCHRONOUS:
 580                 return true;
 581
 582         case PROBE_FORCE_SYNCHRONOUS:
 583                 return false;
 584
 585         default:
 586                 if (module_requested_async_probing(drv->owner))
 587                         return true;
 588
 589                 return false;
 590         }
 591 }
 592
 593 struct device_attach_data {
 594         struct device *dev;
 595
 596         /*
 597          * Indicates whether we are are considering asynchronous probing or
 598          * not. Only initial binding after device or driver registration
 599          * (including deferral processing) may be done asynchronously, the
 600          * rest is always synchronous, as we expect it is being done by
 601          * request from userspace.
 602          */
 603         bool check_async;
 604
 605         /*
 606          * Indicates if we are binding synchronous or asynchronous drivers.
 607          * When asynchronous probing is enabled we'll execute 2 passes
 608          * over drivers: first pass doing synchronous probing and second
 609          * doing asynchronous probing (if synchronous did not succeed -
 610          * most likely because there was no driver requiring synchronous
 611          * probing - and we found asynchronous driver during first pass).
 612          * The 2 passes are done because we can't shoot asynchronous
 613          * probe for given device and driver from bus_for_each_drv() since
 614          * driver pointer is not guaranteed to stay valid once
 615          * bus_for_each_drv() iterates to the next driver on the bus.
 616          */
 617         bool want_async;
 618
 619         /*
 620          * We'll set have_async to 'true' if, while scanning for matching
 621          * driver, we'll encounter one that requests asynchronous probing.
 622          */
 623         bool have_async;
 624 };
 625
 626 static int __device_attach_driver(struct device_driver *drv, void *_data)
 627 {
 628         struct device_attach_data *data = _data;
 629         struct device *dev = data->dev;
 630         bool async_allowed;
 631         int ret;
 632
 633         /*
 634          * Check if device has already been claimed. This may
 635          * happen with driver loading, device discovery/registration,
 636          * and deferred probe processing happens all at once with
 637          * multiple threads.
 638          */
 639         if (dev->driver)
 640                 return -EBUSY;
 641
 642         ret = driver_match_device(drv, dev);
 643         if (ret == 0) {
 644                 /* no match */
 645                 return 0;
 646         } else if (ret == -EPROBE_DEFER) {
 647                 dev_dbg(dev, "Device match requests probe deferral\n");
 648                 driver_deferred_probe_add(dev);
 649         } else if (ret < 0) {
 650                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 651                 return ret;
 652         } /* ret > 0 means positive match */
 653
 654         async_allowed = driver_allows_async_probing(drv);
 655
 656         if (async_allowed)
 657                 data->have_async = true;
 658
 659         if (data->check_async && async_allowed != data->want_async)
 660                 return 0;
 661
 662         return driver_probe_device(drv, dev);
 663 }
 664
 665 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 666 {
 667         struct device *dev = _dev;
 668         struct device_attach_data data = {
 669                 .dev            = dev,
 670                 .check_async    = true,
 671                 .want_async     = true,
 672         };
 673
 674         device_lock(dev);
 675
 676         if (dev->parent)
 677                 pm_runtime_get_sync(dev->parent);
 678
 679         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 680         dev_dbg(dev, "async probe completed\n");
 681
 682         pm_request_idle(dev);
 683
 684         if (dev->parent)
 685                 pm_runtime_put(dev->parent);
 686
 687         device_unlock(dev);
 688
 689         put_device(dev);
 690 }
 691
 692 static int __device_attach(struct device *dev, bool allow_async)
 693 {
 694         int ret = 0;
 695
 696         device_lock(dev);
 697         if (dev->driver) {
 698                 if (device_is_bound(dev)) {
 699                         ret = 1;
 700                         goto out_unlock;
 701                 }
 702                 ret = device_bind_driver(dev);
 703                 if (ret == 0)
 704                         ret = 1;
 705                 else {
 706                         dev->driver = NULL;
 707                         ret = 0;
 708                 }
 709         } else {
 710                 struct device_attach_data data = {
 711                         .dev = dev,
 712                         .check_async = allow_async,
 713                         .want_async = false,
 714                 };
 715
 716                 if (dev->parent)
 717                         pm_runtime_get_sync(dev->parent);
 718
 719                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 720                                         __device_attach_driver);
 721                 if (!ret && allow_async && data.have_async) {
 722                         /*
 723                          * If we could not find appropriate driver
 724                          * synchronously and we are allowed to do
 725                          * async probes and there are drivers that
 726                          * want to probe asynchronously, we'll
 727                          * try them.
 728                          */
 729                         dev_dbg(dev, "scheduling asynchronous probe\n");
 730                         get_device(dev);
 731                         async_schedule(__device_attach_async_helper, dev);
 732                 } else {
 733                         pm_request_idle(dev);
 734                 }
 735
 736                 if (dev->parent)
 737                         pm_runtime_put(dev->parent);
 738         }
 739 out_unlock:
 740         device_unlock(dev);
 741         return ret;
 742 }
 743
 744 /**
 745  * device_attach - try to attach device to a driver.
 746  * @dev: device.
 747  *
 748  * Walk the list of drivers that the bus has and call
 749  * driver_probe_device() for each pair. If a compatible
 750  * pair is found, break out and return.
 751  *
 752  * Returns 1 if the device was bound to a driver;
 753  * 0 if no matching driver was found;
 754  * -ENODEV if the device is not registered.
 755  *
 756  * When called for a USB interface, @dev->parent lock must be held.
 757  */
 758 int device_attach(struct device *dev)
 759 {
 760         return __device_attach(dev, false);
 761 }
 762 EXPORT_SYMBOL_GPL(device_attach);
 763
 764 void device_initial_probe(struct device *dev)
 765 {
 766         __device_attach(dev, true);
 767 }
 768
 769 static int __driver_attach(struct device *dev, void *data)
 770 {
 771         struct device_driver *drv = data;
 772         int ret;
 773
 774         /*
 775          * Lock device and try to bind to it. We drop the error
 776          * here and always return 0, because we need to keep trying
 777          * to bind to devices and some drivers will return an error
 778          * simply if it didn't support the device.
 779          *
 780          * driver_probe_device() will spit a warning if there
 781          * is an error.
 782          */
 783
 784         ret = driver_match_device(drv, dev);
 785         if (ret == 0) {
 786                 /* no match */
 787                 return 0;
 788         } else if (ret == -EPROBE_DEFER) {
 789                 dev_dbg(dev, "Device match requests probe deferral\n");
 790                 driver_deferred_probe_add(dev);
 791         } else if (ret < 0) {
 792                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 793                 return ret;
 794         } /* ret > 0 means positive match */
 795
 796         if (dev->parent)        /* Needed for USB */
 797                 device_lock(dev->parent);
 798         device_lock(dev);
 799         if (!dev->driver)
 800                 driver_probe_device(drv, dev);
 801         device_unlock(dev);
 802         if (dev->parent)
 803                 device_unlock(dev->parent);
 804
 805         return 0;
 806 }
 807
 808 /**
 809  * driver_attach - try to bind driver to devices.
 810  * @drv: driver.
 811  *
 812  * Walk the list of devices that the bus has on it and try to
 813  * match the driver with each one.  If driver_probe_device()
 814  * returns 0 and the @dev->driver is set, we've found a
 815  * compatible pair.
 816  */
 817 int driver_attach(struct device_driver *drv)
 818 {
 819         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 820 }
 821 EXPORT_SYMBOL_GPL(driver_attach);
 822
 823 /*
 824  * __device_release_driver() must be called with @dev lock held.
 825  * When called for a USB interface, @dev->parent lock must be held as well.
 826  */
 827 static void __device_release_driver(struct device *dev, struct device *parent)
 828 {
 829         struct device_driver *drv;
 830
 831         drv = dev->driver;
 832         if (drv) {
 833                 if (driver_allows_async_probing(drv))
 834                         async_synchronize_full();
 835
 836                 while (device_links_busy(dev)) {
 837                         device_unlock(dev);
 838                         if (parent)
 839                                 device_unlock(parent);
 840
 841                         device_links_unbind_consumers(dev);
 842                         if (parent)
 843                                 device_lock(parent);
 844
 845                         device_lock(dev);
 846                         /*
 847                          * A concurrent invocation of the same function might
 848                          * have released the driver successfully while this one
 849                          * was waiting, so check for that.
 850                          */
 851                         if (dev->driver != drv)
 852                                 return;
 853                 }
 854
 855                 pm_runtime_get_sync(dev);
 856                 pm_runtime_clean_up_links(dev);
 857
 858                 driver_sysfs_remove(dev);
 859
 860                 if (dev->bus)
 861                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 862                                                      BUS_NOTIFY_UNBIND_DRIVER,
 863                                                      dev);
 864
 865                 pm_runtime_put_sync(dev);
 866
 867                 if (dev->bus && dev->bus->remove)
 868                         dev->bus->remove(dev);
 869                 else if (drv->remove)
 870                         drv->remove(dev);
 871
 872                 device_links_driver_cleanup(dev);
 873                 dma_deconfigure(dev);
 874
 875                 devres_release_all(dev);
 876                 dev->driver = NULL;
 877                 dev_set_drvdata(dev, NULL);
 878                 if (dev->pm_domain && dev->pm_domain->dismiss)
 879                         dev->pm_domain->dismiss(dev);
 880                 pm_runtime_reinit(dev);
 881                 dev_pm_set_driver_flags(dev, 0);
 882
 883                 klist_remove(&dev->p->knode_driver);
 884                 device_pm_check_callbacks(dev);
 885                 if (dev->bus)
 886                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 887                                                      BUS_NOTIFY_UNBOUND_DRIVER,
 888                                                      dev);
 889
 890                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
 891         }
 892 }
 893
 894 void device_release_driver_internal(struct device *dev,
 895                                     struct device_driver *drv,
 896                                     struct device *parent)
 897 {
 898         if (parent)
 899                 device_lock(parent);
 900
 901         device_lock(dev);
 902         if (!drv || drv == dev->driver)
 903                 __device_release_driver(dev, parent);
 904
 905         device_unlock(dev);
 906         if (parent)
 907                 device_unlock(parent);
 908 }
 909
 910 /**
 911  * device_release_driver - manually detach device from driver.
 912  * @dev: device.
 913  *
 914  * Manually detach device from driver.
 915  * When called for a USB interface, @dev->parent lock must be held.
 916  *
 917  * If this function is to be called with @dev->parent lock held, ensure that
 918  * the device's consumers are unbound in advance or that their locks can be
 919  * acquired under the @dev->parent lock.
 920  */
 921 void device_release_driver(struct device *dev)
 922 {
 923         /*
 924          * If anyone calls device_release_driver() recursively from
 925          * within their ->remove callback for the same device, they
 926          * will deadlock right here.
 927          */
 928         device_release_driver_internal(dev, NULL, NULL);
 929 }
 930 EXPORT_SYMBOL_GPL(device_release_driver);
 931
 932 /**
 933  * driver_detach - detach driver from all devices it controls.
 934  * @drv: driver.
 935  */
 936 void driver_detach(struct device_driver *drv)
 937 {
 938         struct device_private *dev_prv;
 939         struct device *dev;
 940
 941         for (;;) {
 942                 spin_lock(&drv->p->klist_devices.k_lock);
 943                 if (list_empty(&drv->p->klist_devices.k_list)) {
 944                         spin_unlock(&drv->p->klist_devices.k_lock);
 945                         break;
 946                 }
 947                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
 948                                      struct device_private,
 949                                      knode_driver.n_node);
 950                 dev = dev_prv->device;
 951                 get_device(dev);
 952                 spin_unlock(&drv->p->klist_devices.k_lock);
 953                 device_release_driver_internal(dev, drv, dev->parent);
 954                 put_device(dev);
 955         }
 956 }