drivers/base/dd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * drivers/base/dd.c - The core device/driver interactions.
   4  *
   5  * This file contains the (sometimes tricky) code that controls the
   6  * interactions between devices and drivers, which primarily includes
   7  * driver binding and unbinding.
   8  *
   9  * All of this code used to exist in drivers/base/bus.c, but was
  10  * relocated to here in the name of compartmentalization (since it wasn't
  11  * strictly code just for the 'struct bus_type'.
  12  *
  13  * Copyright (c) 2002-5 Patrick Mochel
  14  * Copyright (c) 2002-3 Open Source Development Labs
  15  * Copyright (c) 2007-2009 Greg Kroah-Hartman <[email protected]>
  16  * Copyright (c) 2007-2009 Novell Inc.
  17  */
  18
  19 #include <linux/device.h>
  20 #include <linux/delay.h>
  21 #include <linux/dma-mapping.h>
  22 #include <linux/init.h>
  23 #include <linux/module.h>
  24 #include <linux/kthread.h>
  25 #include <linux/wait.h>
  26 #include <linux/async.h>
  27 #include <linux/pm_runtime.h>
  28 #include <linux/pinctrl/devinfo.h>
  29
  30 #include "base.h"
  31 #include "power/power.h"
  32
  33 /*
  34  * Deferred Probe infrastructure.
  35  *
  36  * Sometimes driver probe order matters, but the kernel doesn't always have
  37  * dependency information which means some drivers will get probed before a
  38  * resource it depends on is available.  For example, an SDHCI driver may
  39  * first need a GPIO line from an i2c GPIO controller before it can be
  40  * initialized.  If a required resource is not available yet, a driver can
  41  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  42  *
  43  * Deferred probe maintains two lists of devices, a pending list and an active
  44  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  45  * pending list.  A successful driver probe will trigger moving all devices
  46  * from the pending to the active list so that the workqueue will eventually
  47  * retry them.
  48  *
  49  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  50  * of the (struct device*)->p->deferred_probe pointers are manipulated
  51  */
  52 static DEFINE_MUTEX(deferred_probe_mutex);
  53 static LIST_HEAD(deferred_probe_pending_list);
  54 static LIST_HEAD(deferred_probe_active_list);
  55 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
  56 static bool initcalls_done;
  57
  58 /*
  59  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  60  * to prohibit probing of devices as it could be unsafe.
  61  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  62  */
  63 static bool defer_all_probes;
  64
  65 /*
  66  * For initcall_debug, show the deferred probes executed in late_initcall
  67  * processing.
  68  */
  69 static void deferred_probe_debug(struct device *dev)
  70 {
  71         ktime_t calltime, delta, rettime;
  72         unsigned long long duration;
  73
  74         printk(KERN_DEBUG "deferred probe %s @ %i\n", dev_name(dev),
  75                task_pid_nr(current));
  76         calltime = ktime_get();
  77         bus_probe_device(dev);
  78         rettime = ktime_get();
  79         delta = ktime_sub(rettime, calltime);
  80         duration = (unsigned long long) ktime_to_ns(delta) >> 10;
  81         printk(KERN_DEBUG "deferred probe %s returned after %lld usecs\n",
  82                dev_name(dev), duration);
  83 }
  84
  85 /*
  86  * deferred_probe_work_func() - Retry probing devices in the active list.
  87  */
  88 static void deferred_probe_work_func(struct work_struct *work)
  89 {
  90         struct device *dev;
  91         struct device_private *private;
  92         /*
  93          * This block processes every device in the deferred 'active' list.
  94          * Each device is removed from the active list and passed to
  95          * bus_probe_device() to re-attempt the probe.  The loop continues
  96          * until every device in the active list is removed and retried.
  97          *
  98          * Note: Once the device is removed from the list and the mutex is
  99          * released, it is possible for the device get freed by another thread
 100          * and cause a illegal pointer dereference.  This code uses
 101          * get/put_device() to ensure the device structure cannot disappear
 102          * from under our feet.
 103          */
 104         mutex_lock(&deferred_probe_mutex);
 105         while (!list_empty(&deferred_probe_active_list)) {
 106                 private = list_first_entry(&deferred_probe_active_list,
 107                                         typeof(*dev->p), deferred_probe);
 108                 dev = private->device;
 109                 list_del_init(&private->deferred_probe);
 110
 111                 get_device(dev);
 112
 113                 /*
 114                  * Drop the mutex while probing each device; the probe path may
 115                  * manipulate the deferred list
 116                  */
 117                 mutex_unlock(&deferred_probe_mutex);
 118
 119                 /*
 120                  * Force the device to the end of the dpm_list since
 121                  * the PM code assumes that the order we add things to
 122                  * the list is a good order for suspend but deferred
 123                  * probe makes that very unsafe.
 124                  */
 125                 device_pm_lock();
 126                 device_pm_move_last(dev);
 127                 device_pm_unlock();
 128
 129                 dev_dbg(dev, "Retrying from deferred list\n");
 130                 if (initcall_debug && !initcalls_done)
 131                         deferred_probe_debug(dev);
 132                 else
 133                         bus_probe_device(dev);
 134
 135                 mutex_lock(&deferred_probe_mutex);
 136
 137                 put_device(dev);
 138         }
 139         mutex_unlock(&deferred_probe_mutex);
 140 }
 141 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 142
 143 static void driver_deferred_probe_add(struct device *dev)
 144 {
 145         mutex_lock(&deferred_probe_mutex);
 146         if (list_empty(&dev->p->deferred_probe)) {
 147                 dev_dbg(dev, "Added to deferred list\n");
 148                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 149         }
 150         mutex_unlock(&deferred_probe_mutex);
 151 }
 152
 153 void driver_deferred_probe_del(struct device *dev)
 154 {
 155         mutex_lock(&deferred_probe_mutex);
 156         if (!list_empty(&dev->p->deferred_probe)) {
 157                 dev_dbg(dev, "Removed from deferred list\n");
 158                 list_del_init(&dev->p->deferred_probe);
 159         }
 160         mutex_unlock(&deferred_probe_mutex);
 161 }
 162
 163 static bool driver_deferred_probe_enable = false;
 164 /**
 165  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 166  *
 167  * This functions moves all devices from the pending list to the active
 168  * list and schedules the deferred probe workqueue to process them.  It
 169  * should be called anytime a driver is successfully bound to a device.
 170  *
 171  * Note, there is a race condition in multi-threaded probe. In the case where
 172  * more than one device is probing at the same time, it is possible for one
 173  * probe to complete successfully while another is about to defer. If the second
 174  * depends on the first, then it will get put on the pending list after the
 175  * trigger event has already occurred and will be stuck there.
 176  *
 177  * The atomic 'deferred_trigger_count' is used to determine if a successful
 178  * trigger has occurred in the midst of probing a driver. If the trigger count
 179  * changes in the midst of a probe, then deferred processing should be triggered
 180  * again.
 181  */
 182 static void driver_deferred_probe_trigger(void)
 183 {
 184         if (!driver_deferred_probe_enable)
 185                 return;
 186
 187         /*
 188          * A successful probe means that all the devices in the pending list
 189          * should be triggered to be reprobed.  Move all the deferred devices
 190          * into the active list so they can be retried by the workqueue
 191          */
 192         mutex_lock(&deferred_probe_mutex);
 193         atomic_inc(&deferred_trigger_count);
 194         list_splice_tail_init(&deferred_probe_pending_list,
 195                               &deferred_probe_active_list);
 196         mutex_unlock(&deferred_probe_mutex);
 197
 198         /*
 199          * Kick the re-probe thread.  It may already be scheduled, but it is
 200          * safe to kick it again.
 201          */
 202         schedule_work(&deferred_probe_work);
 203 }
 204
 205 /**
 206  * device_block_probing() - Block/defere device's probes
 207  *
 208  *      It will disable probing of devices and defer their probes instead.
 209  */
 210 void device_block_probing(void)
 211 {
 212         defer_all_probes = true;
 213         /* sync with probes to avoid races. */
 214         wait_for_device_probe();
 215 }
 216
 217 /**
 218  * device_unblock_probing() - Unblock/enable device's probes
 219  *
 220  *      It will restore normal behavior and trigger re-probing of deferred
 221  * devices.
 222  */
 223 void device_unblock_probing(void)
 224 {
 225         defer_all_probes = false;
 226         driver_deferred_probe_trigger();
 227 }
 228
 229 /**
 230  * deferred_probe_initcall() - Enable probing of deferred devices
 231  *
 232  * We don't want to get in the way when the bulk of drivers are getting probed.
 233  * Instead, this initcall makes sure that deferred probing is delayed until
 234  * late_initcall time.
 235  */
 236 static int deferred_probe_initcall(void)
 237 {
 238         driver_deferred_probe_enable = true;
 239         driver_deferred_probe_trigger();
 240         /* Sort as many dependencies as possible before exiting initcalls */
 241         flush_work(&deferred_probe_work);
 242         initcalls_done = true;
 243         return 0;
 244 }
 245 late_initcall(deferred_probe_initcall);
 246
 247 /**
 248  * device_is_bound() - Check if device is bound to a driver
 249  * @dev: device to check
 250  *
 251  * Returns true if passed device has already finished probing successfully
 252  * against a driver.
 253  *
 254  * This function must be called with the device lock held.
 255  */
 256 bool device_is_bound(struct device *dev)
 257 {
 258         return dev->p && klist_node_attached(&dev->p->knode_driver);
 259 }
 260
 261 static void driver_bound(struct device *dev)
 262 {
 263         if (device_is_bound(dev)) {
 264                 printk(KERN_WARNING "%s: device %s already bound\n",
 265                         __func__, kobject_name(&dev->kobj));
 266                 return;
 267         }
 268
 269         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 270                  __func__, dev_name(dev));
 271
 272         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 273         device_links_driver_bound(dev);
 274
 275         device_pm_check_callbacks(dev);
 276
 277         /*
 278          * Make sure the device is no longer in one of the deferred lists and
 279          * kick off retrying all pending devices
 280          */
 281         driver_deferred_probe_del(dev);
 282         driver_deferred_probe_trigger();
 283
 284         if (dev->bus)
 285                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 286                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 287
 288         kobject_uevent(&dev->kobj, KOBJ_BIND);
 289 }
 290
 291 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 292                             const char *buf, size_t count)
 293 {
 294         device_lock(dev);
 295         dev->driver->coredump(dev);
 296         device_unlock(dev);
 297
 298         return count;
 299 }
 300 static DEVICE_ATTR_WO(coredump);
 301
 302 static int driver_sysfs_add(struct device *dev)
 303 {
 304         int ret;
 305
 306         if (dev->bus)
 307                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 308                                              BUS_NOTIFY_BIND_DRIVER, dev);
 309
 310         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 311                                 kobject_name(&dev->kobj));
 312         if (ret)
 313                 goto fail;
 314
 315         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 316                                 "driver");
 317         if (ret)
 318                 goto rm_dev;
 319
 320         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
 321             !device_create_file(dev, &dev_attr_coredump))
 322                 return 0;
 323
 324         sysfs_remove_link(&dev->kobj, "driver");
 325
 326 rm_dev:
 327         sysfs_remove_link(&dev->driver->p->kobj,
 328                           kobject_name(&dev->kobj));
 329
 330 fail:
 331         return ret;
 332 }
 333
 334 static void driver_sysfs_remove(struct device *dev)
 335 {
 336         struct device_driver *drv = dev->driver;
 337
 338         if (drv) {
 339                 if (drv->coredump)
 340                         device_remove_file(dev, &dev_attr_coredump);
 341                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 342                 sysfs_remove_link(&dev->kobj, "driver");
 343         }
 344 }
 345
 346 /**
 347  * device_bind_driver - bind a driver to one device.
 348  * @dev: device.
 349  *
 350  * Allow manual attachment of a driver to a device.
 351  * Caller must have already set @dev->driver.
 352  *
 353  * Note that this does not modify the bus reference count
 354  * nor take the bus's rwsem. Please verify those are accounted
 355  * for before calling this. (It is ok to call with no other effort
 356  * from a driver's probe() method.)
 357  *
 358  * This function must be called with the device lock held.
 359  */
 360 int device_bind_driver(struct device *dev)
 361 {
 362         int ret;
 363
 364         ret = driver_sysfs_add(dev);
 365         if (!ret)
 366                 driver_bound(dev);
 367         else if (dev->bus)
 368                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 369                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 370         return ret;
 371 }
 372 EXPORT_SYMBOL_GPL(device_bind_driver);
 373
 374 static atomic_t probe_count = ATOMIC_INIT(0);
 375 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 376
 377 static void driver_deferred_probe_add_trigger(struct device *dev,
 378                                               int local_trigger_count)
 379 {
 380         driver_deferred_probe_add(dev);
 381         /* Did a trigger occur while probing? Need to re-trigger if yes */
 382         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 383                 driver_deferred_probe_trigger();
 384 }
 385
 386 static int really_probe(struct device *dev, struct device_driver *drv)
 387 {
 388         int ret = -EPROBE_DEFER;
 389         int local_trigger_count = atomic_read(&deferred_trigger_count);
 390         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 391                            !drv->suppress_bind_attrs;
 392
 393         if (defer_all_probes) {
 394                 /*
 395                  * Value of defer_all_probes can be set only by
 396                  * device_defer_all_probes_enable() which, in turn, will call
 397                  * wait_for_device_probe() right after that to avoid any races.
 398                  */
 399                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 400                 driver_deferred_probe_add(dev);
 401                 return ret;
 402         }
 403
 404         ret = device_links_check_suppliers(dev);
 405         if (ret == -EPROBE_DEFER)
 406                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 407         if (ret)
 408                 return ret;
 409
 410         atomic_inc(&probe_count);
 411         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 412                  drv->bus->name, __func__, drv->name, dev_name(dev));
 413         WARN_ON(!list_empty(&dev->devres_head));
 414
 415 re_probe:
 416         dev->driver = drv;
 417
 418         /* If using pinctrl, bind pins now before probing */
 419         ret = pinctrl_bind_pins(dev);
 420         if (ret)
 421                 goto pinctrl_bind_failed;
 422
 423         ret = dma_configure(dev);
 424         if (ret)
 425                 goto dma_failed;
 426
 427         if (driver_sysfs_add(dev)) {
 428                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 429                         __func__, dev_name(dev));
 430                 goto probe_failed;
 431         }
 432
 433         if (dev->pm_domain && dev->pm_domain->activate) {
 434                 ret = dev->pm_domain->activate(dev);
 435                 if (ret)
 436                         goto probe_failed;
 437         }
 438
 439         /*
 440          * Ensure devices are listed in devices_kset in correct order
 441          * It's important to move Dev to the end of devices_kset before
 442          * calling .probe, because it could be recursive and parent Dev
 443          * should always go first
 444          */
 445         devices_kset_move_last(dev);
 446
 447         if (dev->bus->probe) {
 448                 ret = dev->bus->probe(dev);
 449                 if (ret)
 450                         goto probe_failed;
 451         } else if (drv->probe) {
 452                 ret = drv->probe(dev);
 453                 if (ret)
 454                         goto probe_failed;
 455         }
 456
 457         if (test_remove) {
 458                 test_remove = false;
 459
 460                 if (dev->bus->remove)
 461                         dev->bus->remove(dev);
 462                 else if (drv->remove)
 463                         drv->remove(dev);
 464
 465                 devres_release_all(dev);
 466                 driver_sysfs_remove(dev);
 467                 dev->driver = NULL;
 468                 dev_set_drvdata(dev, NULL);
 469                 if (dev->pm_domain && dev->pm_domain->dismiss)
 470                         dev->pm_domain->dismiss(dev);
 471                 pm_runtime_reinit(dev);
 472
 473                 goto re_probe;
 474         }
 475
 476         pinctrl_init_done(dev);
 477
 478         if (dev->pm_domain && dev->pm_domain->sync)
 479                 dev->pm_domain->sync(dev);
 480
 481         driver_bound(dev);
 482         ret = 1;
 483         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 484                  drv->bus->name, __func__, dev_name(dev), drv->name);
 485         goto done;
 486
 487 probe_failed:
 488         dma_deconfigure(dev);
 489 dma_failed:
 490         if (dev->bus)
 491                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 492                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 493 pinctrl_bind_failed:
 494         device_links_no_driver(dev);
 495         devres_release_all(dev);
 496         driver_sysfs_remove(dev);
 497         dev->driver = NULL;
 498         dev_set_drvdata(dev, NULL);
 499         if (dev->pm_domain && dev->pm_domain->dismiss)
 500                 dev->pm_domain->dismiss(dev);
 501         pm_runtime_reinit(dev);
 502         dev_pm_set_driver_flags(dev, 0);
 503
 504         switch (ret) {
 505         case -EPROBE_DEFER:
 506                 /* Driver requested deferred probing */
 507                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 508                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 509                 break;
 510         case -ENODEV:
 511         case -ENXIO:
 512                 pr_debug("%s: probe of %s rejects match %d\n",
 513                          drv->name, dev_name(dev), ret);
 514                 break;
 515         default:
 516                 /* driver matched but the probe failed */
 517                 printk(KERN_WARNING
 518                        "%s: probe of %s failed with error %d\n",
 519                        drv->name, dev_name(dev), ret);
 520         }
 521         /*
 522          * Ignore errors returned by ->probe so that the next driver can try
 523          * its luck.
 524          */
 525         ret = 0;
 526 done:
 527         atomic_dec(&probe_count);
 528         wake_up(&probe_waitqueue);
 529         return ret;
 530 }
 531
 532 /**
 533  * driver_probe_done
 534  * Determine if the probe sequence is finished or not.
 535  *
 536  * Should somehow figure out how to use a semaphore, not an atomic variable...
 537  */
 538 int driver_probe_done(void)
 539 {
 540         pr_debug("%s: probe_count = %d\n", __func__,
 541                  atomic_read(&probe_count));
 542         if (atomic_read(&probe_count))
 543                 return -EBUSY;
 544         return 0;
 545 }
 546
 547 /**
 548  * wait_for_device_probe
 549  * Wait for device probing to be completed.
 550  */
 551 void wait_for_device_probe(void)
 552 {
 553         /* wait for the deferred probe workqueue to finish */
 554         flush_work(&deferred_probe_work);
 555
 556         /* wait for the known devices to complete their probing */
 557         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 558         async_synchronize_full();
 559 }
 560 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 561
 562 /**
 563  * driver_probe_device - attempt to bind device & driver together
 564  * @drv: driver to bind a device to
 565  * @dev: device to try to bind to the driver
 566  *
 567  * This function returns -ENODEV if the device is not registered,
 568  * 1 if the device is bound successfully and 0 otherwise.
 569  *
 570  * This function must be called with @dev lock held.  When called for a
 571  * USB interface, @dev->parent lock must be held as well.
 572  *
 573  * If the device has a parent, runtime-resume the parent before driver probing.
 574  */
 575 int driver_probe_device(struct device_driver *drv, struct device *dev)
 576 {
 577         int ret = 0;
 578
 579         if (!device_is_registered(dev))
 580                 return -ENODEV;
 581
 582         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 583                  drv->bus->name, __func__, dev_name(dev), drv->name);
 584
 585         pm_runtime_get_suppliers(dev);
 586         if (dev->parent)
 587                 pm_runtime_get_sync(dev->parent);
 588
 589         pm_runtime_barrier(dev);
 590         ret = really_probe(dev, drv);
 591         pm_request_idle(dev);
 592
 593         if (dev->parent)
 594                 pm_runtime_put(dev->parent);
 595
 596         pm_runtime_put_suppliers(dev);
 597         return ret;
 598 }
 599
 600 bool driver_allows_async_probing(struct device_driver *drv)
 601 {
 602         switch (drv->probe_type) {
 603         case PROBE_PREFER_ASYNCHRONOUS:
 604                 return true;
 605
 606         case PROBE_FORCE_SYNCHRONOUS:
 607                 return false;
 608
 609         default:
 610                 if (module_requested_async_probing(drv->owner))
 611                         return true;
 612
 613                 return false;
 614         }
 615 }
 616
 617 struct device_attach_data {
 618         struct device *dev;
 619
 620         /*
 621          * Indicates whether we are are considering asynchronous probing or
 622          * not. Only initial binding after device or driver registration
 623          * (including deferral processing) may be done asynchronously, the
 624          * rest is always synchronous, as we expect it is being done by
 625          * request from userspace.
 626          */
 627         bool check_async;
 628
 629         /*
 630          * Indicates if we are binding synchronous or asynchronous drivers.
 631          * When asynchronous probing is enabled we'll execute 2 passes
 632          * over drivers: first pass doing synchronous probing and second
 633          * doing asynchronous probing (if synchronous did not succeed -
 634          * most likely because there was no driver requiring synchronous
 635          * probing - and we found asynchronous driver during first pass).
 636          * The 2 passes are done because we can't shoot asynchronous
 637          * probe for given device and driver from bus_for_each_drv() since
 638          * driver pointer is not guaranteed to stay valid once
 639          * bus_for_each_drv() iterates to the next driver on the bus.
 640          */
 641         bool want_async;
 642
 643         /*
 644          * We'll set have_async to 'true' if, while scanning for matching
 645          * driver, we'll encounter one that requests asynchronous probing.
 646          */
 647         bool have_async;
 648 };
 649
 650 static int __device_attach_driver(struct device_driver *drv, void *_data)
 651 {
 652         struct device_attach_data *data = _data;
 653         struct device *dev = data->dev;
 654         bool async_allowed;
 655         int ret;
 656
 657         /*
 658          * Check if device has already been claimed. This may
 659          * happen with driver loading, device discovery/registration,
 660          * and deferred probe processing happens all at once with
 661          * multiple threads.
 662          */
 663         if (dev->driver)
 664                 return -EBUSY;
 665
 666         ret = driver_match_device(drv, dev);
 667         if (ret == 0) {
 668                 /* no match */
 669                 return 0;
 670         } else if (ret == -EPROBE_DEFER) {
 671                 dev_dbg(dev, "Device match requests probe deferral\n");
 672                 driver_deferred_probe_add(dev);
 673         } else if (ret < 0) {
 674                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 675                 return ret;
 676         } /* ret > 0 means positive match */
 677
 678         async_allowed = driver_allows_async_probing(drv);
 679
 680         if (async_allowed)
 681                 data->have_async = true;
 682
 683         if (data->check_async && async_allowed != data->want_async)
 684                 return 0;
 685
 686         return driver_probe_device(drv, dev);
 687 }
 688
 689 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 690 {
 691         struct device *dev = _dev;
 692         struct device_attach_data data = {
 693                 .dev            = dev,
 694                 .check_async    = true,
 695                 .want_async     = true,
 696         };
 697
 698         device_lock(dev);
 699
 700         if (dev->parent)
 701                 pm_runtime_get_sync(dev->parent);
 702
 703         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 704         dev_dbg(dev, "async probe completed\n");
 705
 706         pm_request_idle(dev);
 707
 708         if (dev->parent)
 709                 pm_runtime_put(dev->parent);
 710
 711         device_unlock(dev);
 712
 713         put_device(dev);
 714 }
 715
 716 static int __device_attach(struct device *dev, bool allow_async)
 717 {
 718         int ret = 0;
 719
 720         device_lock(dev);
 721         if (dev->driver) {
 722                 if (device_is_bound(dev)) {
 723                         ret = 1;
 724                         goto out_unlock;
 725                 }
 726                 ret = device_bind_driver(dev);
 727                 if (ret == 0)
 728                         ret = 1;
 729                 else {
 730                         dev->driver = NULL;
 731                         ret = 0;
 732                 }
 733         } else {
 734                 struct device_attach_data data = {
 735                         .dev = dev,
 736                         .check_async = allow_async,
 737                         .want_async = false,
 738                 };
 739
 740                 if (dev->parent)
 741                         pm_runtime_get_sync(dev->parent);
 742
 743                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 744                                         __device_attach_driver);
 745                 if (!ret && allow_async && data.have_async) {
 746                         /*
 747                          * If we could not find appropriate driver
 748                          * synchronously and we are allowed to do
 749                          * async probes and there are drivers that
 750                          * want to probe asynchronously, we'll
 751                          * try them.
 752                          */
 753                         dev_dbg(dev, "scheduling asynchronous probe\n");
 754                         get_device(dev);
 755                         async_schedule(__device_attach_async_helper, dev);
 756                 } else {
 757                         pm_request_idle(dev);
 758                 }
 759
 760                 if (dev->parent)
 761                         pm_runtime_put(dev->parent);
 762         }
 763 out_unlock:
 764         device_unlock(dev);
 765         return ret;
 766 }
 767
 768 /**
 769  * device_attach - try to attach device to a driver.
 770  * @dev: device.
 771  *
 772  * Walk the list of drivers that the bus has and call
 773  * driver_probe_device() for each pair. If a compatible
 774  * pair is found, break out and return.
 775  *
 776  * Returns 1 if the device was bound to a driver;
 777  * 0 if no matching driver was found;
 778  * -ENODEV if the device is not registered.
 779  *
 780  * When called for a USB interface, @dev->parent lock must be held.
 781  */
 782 int device_attach(struct device *dev)
 783 {
 784         return __device_attach(dev, false);
 785 }
 786 EXPORT_SYMBOL_GPL(device_attach);
 787
 788 void device_initial_probe(struct device *dev)
 789 {
 790         __device_attach(dev, true);
 791 }
 792
 793 static int __driver_attach(struct device *dev, void *data)
 794 {
 795         struct device_driver *drv = data;
 796         int ret;
 797
 798         /*
 799          * Lock device and try to bind to it. We drop the error
 800          * here and always return 0, because we need to keep trying
 801          * to bind to devices and some drivers will return an error
 802          * simply if it didn't support the device.
 803          *
 804          * driver_probe_device() will spit a warning if there
 805          * is an error.
 806          */
 807
 808         ret = driver_match_device(drv, dev);
 809         if (ret == 0) {
 810                 /* no match */
 811                 return 0;
 812         } else if (ret == -EPROBE_DEFER) {
 813                 dev_dbg(dev, "Device match requests probe deferral\n");
 814                 driver_deferred_probe_add(dev);
 815         } else if (ret < 0) {
 816                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 817                 return ret;
 818         } /* ret > 0 means positive match */
 819
 820         if (dev->parent)        /* Needed for USB */
 821                 device_lock(dev->parent);
 822         device_lock(dev);
 823         if (!dev->driver)
 824                 driver_probe_device(drv, dev);
 825         device_unlock(dev);
 826         if (dev->parent)
 827                 device_unlock(dev->parent);
 828
 829         return 0;
 830 }
 831
 832 /**
 833  * driver_attach - try to bind driver to devices.
 834  * @drv: driver.
 835  *
 836  * Walk the list of devices that the bus has on it and try to
 837  * match the driver with each one.  If driver_probe_device()
 838  * returns 0 and the @dev->driver is set, we've found a
 839  * compatible pair.
 840  */
 841 int driver_attach(struct device_driver *drv)
 842 {
 843         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 844 }
 845 EXPORT_SYMBOL_GPL(driver_attach);
 846
 847 /*
 848  * __device_release_driver() must be called with @dev lock held.
 849  * When called for a USB interface, @dev->parent lock must be held as well.
 850  */
 851 static void __device_release_driver(struct device *dev, struct device *parent)
 852 {
 853         struct device_driver *drv;
 854
 855         drv = dev->driver;
 856         if (drv) {
 857                 if (driver_allows_async_probing(drv))
 858                         async_synchronize_full();
 859
 860                 while (device_links_busy(dev)) {
 861                         device_unlock(dev);
 862                         if (parent)
 863                                 device_unlock(parent);
 864
 865                         device_links_unbind_consumers(dev);
 866                         if (parent)
 867                                 device_lock(parent);
 868
 869                         device_lock(dev);
 870                         /*
 871                          * A concurrent invocation of the same function might
 872                          * have released the driver successfully while this one
 873                          * was waiting, so check for that.
 874                          */
 875                         if (dev->driver != drv)
 876                                 return;
 877                 }
 878
 879                 pm_runtime_get_sync(dev);
 880                 pm_runtime_clean_up_links(dev);
 881
 882                 driver_sysfs_remove(dev);
 883
 884                 if (dev->bus)
 885                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 886                                                      BUS_NOTIFY_UNBIND_DRIVER,
 887                                                      dev);
 888
 889                 pm_runtime_put_sync(dev);
 890
 891                 if (dev->bus && dev->bus->remove)
 892                         dev->bus->remove(dev);
 893                 else if (drv->remove)
 894                         drv->remove(dev);
 895
 896                 device_links_driver_cleanup(dev);
 897                 dma_deconfigure(dev);
 898
 899                 devres_release_all(dev);
 900                 dev->driver = NULL;
 901                 dev_set_drvdata(dev, NULL);
 902                 if (dev->pm_domain && dev->pm_domain->dismiss)
 903                         dev->pm_domain->dismiss(dev);
 904                 pm_runtime_reinit(dev);
 905                 dev_pm_set_driver_flags(dev, 0);
 906
 907                 klist_remove(&dev->p->knode_driver);
 908                 device_pm_check_callbacks(dev);
 909                 if (dev->bus)
 910                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 911                                                      BUS_NOTIFY_UNBOUND_DRIVER,
 912                                                      dev);
 913
 914                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
 915         }
 916 }
 917
 918 void device_release_driver_internal(struct device *dev,
 919                                     struct device_driver *drv,
 920                                     struct device *parent)
 921 {
 922         if (parent)
 923                 device_lock(parent);
 924
 925         device_lock(dev);
 926         if (!drv || drv == dev->driver)
 927                 __device_release_driver(dev, parent);
 928
 929         device_unlock(dev);
 930         if (parent)
 931                 device_unlock(parent);
 932 }
 933
 934 /**
 935  * device_release_driver - manually detach device from driver.
 936  * @dev: device.
 937  *
 938  * Manually detach device from driver.
 939  * When called for a USB interface, @dev->parent lock must be held.
 940  *
 941  * If this function is to be called with @dev->parent lock held, ensure that
 942  * the device's consumers are unbound in advance or that their locks can be
 943  * acquired under the @dev->parent lock.
 944  */
 945 void device_release_driver(struct device *dev)
 946 {
 947         /*
 948          * If anyone calls device_release_driver() recursively from
 949          * within their ->remove callback for the same device, they
 950          * will deadlock right here.
 951          */
 952         device_release_driver_internal(dev, NULL, NULL);
 953 }
 954 EXPORT_SYMBOL_GPL(device_release_driver);
 955
 956 /**
 957  * driver_detach - detach driver from all devices it controls.
 958  * @drv: driver.
 959  */
 960 void driver_detach(struct device_driver *drv)
 961 {
 962         struct device_private *dev_prv;
 963         struct device *dev;
 964
 965         for (;;) {
 966                 spin_lock(&drv->p->klist_devices.k_lock);
 967                 if (list_empty(&drv->p->klist_devices.k_list)) {
 968                         spin_unlock(&drv->p->klist_devices.k_lock);
 969                         break;
 970                 }
 971                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
 972                                      struct device_private,
 973                                      knode_driver.n_node);
 974                 dev = dev_prv->device;
 975                 get_device(dev);
 976                 spin_unlock(&drv->p->klist_devices.k_lock);
 977                 device_release_driver_internal(dev, drv, dev->parent);
 978                 put_device(dev);
 979         }
 980 }