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 <gregkh@suse.de>
  16  * Copyright (c) 2007-2009 Novell Inc.
  17  */
  18
  19 #include <linux/debugfs.h>
  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 struct dentry *deferred_devices;
  58 static bool initcalls_done;
  59
  60 /*
  61  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  62  * to prohibit probing of devices as it could be unsafe.
  63  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  64  */
  65 static bool defer_all_probes;
  66
  67 /*
  68  * deferred_probe_work_func() - Retry probing devices in the active list.
  69  */
  70 static void deferred_probe_work_func(struct work_struct *work)
  71 {
  72         struct device *dev;
  73         struct device_private *private;
  74         /*
  75          * This block processes every device in the deferred 'active' list.
  76          * Each device is removed from the active list and passed to
  77          * bus_probe_device() to re-attempt the probe.  The loop continues
  78          * until every device in the active list is removed and retried.
  79          *
  80          * Note: Once the device is removed from the list and the mutex is
  81          * released, it is possible for the device get freed by another thread
  82          * and cause a illegal pointer dereference.  This code uses
  83          * get/put_device() to ensure the device structure cannot disappear
  84          * from under our feet.
  85          */
  86         mutex_lock(&deferred_probe_mutex);
  87         while (!list_empty(&deferred_probe_active_list)) {
  88                 private = list_first_entry(&deferred_probe_active_list,
  89                                         typeof(*dev->p), deferred_probe);
  90                 dev = private->device;
  91                 list_del_init(&private->deferred_probe);
  92
  93                 get_device(dev);
  94
  95                 /*
  96                  * Drop the mutex while probing each device; the probe path may
  97                  * manipulate the deferred list
  98                  */
  99                 mutex_unlock(&deferred_probe_mutex);
 100
 101                 /*
 102                  * Force the device to the end of the dpm_list since
 103                  * the PM code assumes that the order we add things to
 104                  * the list is a good order for suspend but deferred
 105                  * probe makes that very unsafe.
 106                  */
 107                 device_pm_move_to_tail(dev);
 108
 109                 dev_dbg(dev, "Retrying from deferred list\n");
 110                 bus_probe_device(dev);
 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         schedule_work(&deferred_probe_work);
 179 }
 180
 181 /**
 182  * device_block_probing() - Block/defer 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_devs_show() - Show the devices in the deferred probe pending list.
 207  */
 208 static int deferred_devs_show(struct seq_file *s, void *data)
 209 {
 210         struct device_private *curr;
 211
 212         mutex_lock(&deferred_probe_mutex);
 213
 214         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 215                 seq_printf(s, "%s\n", dev_name(curr->device));
 216
 217         mutex_unlock(&deferred_probe_mutex);
 218
 219         return 0;
 220 }
 221 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 222
 223 static int deferred_probe_timeout = -1;
 224 static int __init deferred_probe_timeout_setup(char *str)
 225 {
 226         int timeout;
 227
 228         if (!kstrtoint(str, 10, &timeout))
 229                 deferred_probe_timeout = timeout;
 230         return 1;
 231 }
 232 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 233
 234 /**
 235  * driver_deferred_probe_check_state() - Check deferred probe state
 236  * @dev: device to check
 237  *
 238  * Returns -ENODEV if init is done and all built-in drivers have had a chance
 239  * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug
 240  * timeout has expired, or -EPROBE_DEFER if none of those conditions are met.
 241  *
 242  * Drivers or subsystems can opt-in to calling this function instead of directly
 243  * returning -EPROBE_DEFER.
 244  */
 245 int driver_deferred_probe_check_state(struct device *dev)
 246 {
 247         if (initcalls_done) {
 248                 if (!deferred_probe_timeout) {
 249                         dev_WARN(dev, "deferred probe timeout, ignoring dependency");
 250                         return -ETIMEDOUT;
 251                 }
 252                 dev_warn(dev, "ignoring dependency for device, assuming no driver");
 253                 return -ENODEV;
 254         }
 255         return -EPROBE_DEFER;
 256 }
 257
 258 static void deferred_probe_timeout_work_func(struct work_struct *work)
 259 {
 260         struct device_private *private, *p;
 261
 262         deferred_probe_timeout = 0;
 263         driver_deferred_probe_trigger();
 264         flush_work(&deferred_probe_work);
 265
 266         list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe)
 267                 dev_info(private->device, "deferred probe pending");
 268 }
 269 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 270
 271 /**
 272  * deferred_probe_initcall() - Enable probing of deferred devices
 273  *
 274  * We don't want to get in the way when the bulk of drivers are getting probed.
 275  * Instead, this initcall makes sure that deferred probing is delayed until
 276  * late_initcall time.
 277  */
 278 static int deferred_probe_initcall(void)
 279 {
 280         deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
 281                                                NULL, &deferred_devs_fops);
 282
 283         driver_deferred_probe_enable = true;
 284         driver_deferred_probe_trigger();
 285         /* Sort as many dependencies as possible before exiting initcalls */
 286         flush_work(&deferred_probe_work);
 287         initcalls_done = true;
 288
 289         /*
 290          * Trigger deferred probe again, this time we won't defer anything
 291          * that is optional
 292          */
 293         driver_deferred_probe_trigger();
 294         flush_work(&deferred_probe_work);
 295
 296         if (deferred_probe_timeout > 0) {
 297                 schedule_delayed_work(&deferred_probe_timeout_work,
 298                         deferred_probe_timeout * HZ);
 299         }
 300         return 0;
 301 }
 302 late_initcall(deferred_probe_initcall);
 303
 304 static void __exit deferred_probe_exit(void)
 305 {
 306         debugfs_remove_recursive(deferred_devices);
 307 }
 308 __exitcall(deferred_probe_exit);
 309
 310 /**
 311  * device_is_bound() - Check if device is bound to a driver
 312  * @dev: device to check
 313  *
 314  * Returns true if passed device has already finished probing successfully
 315  * against a driver.
 316  *
 317  * This function must be called with the device lock held.
 318  */
 319 bool device_is_bound(struct device *dev)
 320 {
 321         return dev->p && klist_node_attached(&dev->p->knode_driver);
 322 }
 323
 324 static void driver_bound(struct device *dev)
 325 {
 326         if (device_is_bound(dev)) {
 327                 printk(KERN_WARNING "%s: device %s already bound\n",
 328                         __func__, kobject_name(&dev->kobj));
 329                 return;
 330         }
 331
 332         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 333                  __func__, dev_name(dev));
 334
 335         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 336         device_links_driver_bound(dev);
 337
 338         device_pm_check_callbacks(dev);
 339
 340         /*
 341          * Make sure the device is no longer in one of the deferred lists and
 342          * kick off retrying all pending devices
 343          */
 344         driver_deferred_probe_del(dev);
 345         driver_deferred_probe_trigger();
 346
 347         if (dev->bus)
 348                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 349                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 350
 351         kobject_uevent(&dev->kobj, KOBJ_BIND);
 352 }
 353
 354 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 355                             const char *buf, size_t count)
 356 {
 357         device_lock(dev);
 358         dev->driver->coredump(dev);
 359         device_unlock(dev);
 360
 361         return count;
 362 }
 363 static DEVICE_ATTR_WO(coredump);
 364
 365 static int driver_sysfs_add(struct device *dev)
 366 {
 367         int ret;
 368
 369         if (dev->bus)
 370                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 371                                              BUS_NOTIFY_BIND_DRIVER, dev);
 372
 373         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 374                                 kobject_name(&dev->kobj));
 375         if (ret)
 376                 goto fail;
 377
 378         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 379                                 "driver");
 380         if (ret)
 381                 goto rm_dev;
 382
 383         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
 384             !device_create_file(dev, &dev_attr_coredump))
 385                 return 0;
 386
 387         sysfs_remove_link(&dev->kobj, "driver");
 388
 389 rm_dev:
 390         sysfs_remove_link(&dev->driver->p->kobj,
 391                           kobject_name(&dev->kobj));
 392
 393 fail:
 394         return ret;
 395 }
 396
 397 static void driver_sysfs_remove(struct device *dev)
 398 {
 399         struct device_driver *drv = dev->driver;
 400
 401         if (drv) {
 402                 if (drv->coredump)
 403                         device_remove_file(dev, &dev_attr_coredump);
 404                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 405                 sysfs_remove_link(&dev->kobj, "driver");
 406         }
 407 }
 408
 409 /**
 410  * device_bind_driver - bind a driver to one device.
 411  * @dev: device.
 412  *
 413  * Allow manual attachment of a driver to a device.
 414  * Caller must have already set @dev->driver.
 415  *
 416  * Note that this does not modify the bus reference count
 417  * nor take the bus's rwsem. Please verify those are accounted
 418  * for before calling this. (It is ok to call with no other effort
 419  * from a driver's probe() method.)
 420  *
 421  * This function must be called with the device lock held.
 422  */
 423 int device_bind_driver(struct device *dev)
 424 {
 425         int ret;
 426
 427         ret = driver_sysfs_add(dev);
 428         if (!ret)
 429                 driver_bound(dev);
 430         else if (dev->bus)
 431                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 432                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 433         return ret;
 434 }
 435 EXPORT_SYMBOL_GPL(device_bind_driver);
 436
 437 static atomic_t probe_count = ATOMIC_INIT(0);
 438 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 439
 440 static void driver_deferred_probe_add_trigger(struct device *dev,
 441                                               int local_trigger_count)
 442 {
 443         driver_deferred_probe_add(dev);
 444         /* Did a trigger occur while probing? Need to re-trigger if yes */
 445         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 446                 driver_deferred_probe_trigger();
 447 }
 448
 449 static int really_probe(struct device *dev, struct device_driver *drv)
 450 {
 451         int ret = -EPROBE_DEFER;
 452         int local_trigger_count = atomic_read(&deferred_trigger_count);
 453         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 454                            !drv->suppress_bind_attrs;
 455
 456         if (defer_all_probes) {
 457                 /*
 458                  * Value of defer_all_probes can be set only by
 459                  * device_block_probing() which, in turn, will call
 460                  * wait_for_device_probe() right after that to avoid any races.
 461                  */
 462                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 463                 driver_deferred_probe_add(dev);
 464                 return ret;
 465         }
 466
 467         ret = device_links_check_suppliers(dev);
 468         if (ret == -EPROBE_DEFER)
 469                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 470         if (ret)
 471                 return ret;
 472
 473         atomic_inc(&probe_count);
 474         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 475                  drv->bus->name, __func__, drv->name, dev_name(dev));
 476         WARN_ON(!list_empty(&dev->devres_head));
 477
 478 re_probe:
 479         dev->driver = drv;
 480
 481         /* If using pinctrl, bind pins now before probing */
 482         ret = pinctrl_bind_pins(dev);
 483         if (ret)
 484                 goto pinctrl_bind_failed;
 485
 486         if (dev->bus->dma_configure) {
 487                 ret = dev->bus->dma_configure(dev);
 488                 if (ret)
 489                         goto dma_failed;
 490         }
 491
 492         if (driver_sysfs_add(dev)) {
 493                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 494                         __func__, dev_name(dev));
 495                 goto probe_failed;
 496         }
 497
 498         if (dev->pm_domain && dev->pm_domain->activate) {
 499                 ret = dev->pm_domain->activate(dev);
 500                 if (ret)
 501                         goto probe_failed;
 502         }
 503
 504         if (dev->bus->probe) {
 505                 ret = dev->bus->probe(dev);
 506                 if (ret)
 507                         goto probe_failed;
 508         } else if (drv->probe) {
 509                 ret = drv->probe(dev);
 510                 if (ret)
 511                         goto probe_failed;
 512         }
 513
 514         if (test_remove) {
 515                 test_remove = false;
 516
 517                 if (dev->bus->remove)
 518                         dev->bus->remove(dev);
 519                 else if (drv->remove)
 520                         drv->remove(dev);
 521
 522                 devres_release_all(dev);
 523                 driver_sysfs_remove(dev);
 524                 dev->driver = NULL;
 525                 dev_set_drvdata(dev, NULL);
 526                 if (dev->pm_domain && dev->pm_domain->dismiss)
 527                         dev->pm_domain->dismiss(dev);
 528                 pm_runtime_reinit(dev);
 529
 530                 goto re_probe;
 531         }
 532
 533         pinctrl_init_done(dev);
 534
 535         if (dev->pm_domain && dev->pm_domain->sync)
 536                 dev->pm_domain->sync(dev);
 537
 538         driver_bound(dev);
 539         ret = 1;
 540         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 541                  drv->bus->name, __func__, dev_name(dev), drv->name);
 542         goto done;
 543
 544 probe_failed:
 545         arch_teardown_dma_ops(dev);
 546 dma_failed:
 547         if (dev->bus)
 548                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 549                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 550 pinctrl_bind_failed:
 551         device_links_no_driver(dev);
 552         devres_release_all(dev);
 553         driver_sysfs_remove(dev);
 554         dev->driver = NULL;
 555         dev_set_drvdata(dev, NULL);
 556         if (dev->pm_domain && dev->pm_domain->dismiss)
 557                 dev->pm_domain->dismiss(dev);
 558         pm_runtime_reinit(dev);
 559         dev_pm_set_driver_flags(dev, 0);
 560
 561         switch (ret) {
 562         case -EPROBE_DEFER:
 563                 /* Driver requested deferred probing */
 564                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 565                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 566                 break;
 567         case -ENODEV:
 568         case -ENXIO:
 569                 pr_debug("%s: probe of %s rejects match %d\n",
 570                          drv->name, dev_name(dev), ret);
 571                 break;
 572         default:
 573                 /* driver matched but the probe failed */
 574                 printk(KERN_WARNING
 575                        "%s: probe of %s failed with error %d\n",
 576                        drv->name, dev_name(dev), ret);
 577         }
 578         /*
 579          * Ignore errors returned by ->probe so that the next driver can try
 580          * its luck.
 581          */
 582         ret = 0;
 583 done:
 584         atomic_dec(&probe_count);
 585         wake_up(&probe_waitqueue);
 586         return ret;
 587 }
 588
 589 /*
 590  * For initcall_debug, show the driver probe time.
 591  */
 592 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 593 {
 594         ktime_t calltime, delta, rettime;
 595         int ret;
 596
 597         calltime = ktime_get();
 598         ret = really_probe(dev, drv);
 599         rettime = ktime_get();
 600         delta = ktime_sub(rettime, calltime);
 601         printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
 602                dev_name(dev), ret, (s64) ktime_to_us(delta));
 603         return ret;
 604 }
 605
 606 /**
 607  * driver_probe_done
 608  * Determine if the probe sequence is finished or not.
 609  *
 610  * Should somehow figure out how to use a semaphore, not an atomic variable...
 611  */
 612 int driver_probe_done(void)
 613 {
 614         pr_debug("%s: probe_count = %d\n", __func__,
 615                  atomic_read(&probe_count));
 616         if (atomic_read(&probe_count))
 617                 return -EBUSY;
 618         return 0;
 619 }
 620
 621 /**
 622  * wait_for_device_probe
 623  * Wait for device probing to be completed.
 624  */
 625 void wait_for_device_probe(void)
 626 {
 627         /* wait for the deferred probe workqueue to finish */
 628         flush_work(&deferred_probe_work);
 629
 630         /* wait for the known devices to complete their probing */
 631         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 632         async_synchronize_full();
 633 }
 634 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 635
 636 /**
 637  * driver_probe_device - attempt to bind device & driver together
 638  * @drv: driver to bind a device to
 639  * @dev: device to try to bind to the driver
 640  *
 641  * This function returns -ENODEV if the device is not registered,
 642  * 1 if the device is bound successfully and 0 otherwise.
 643  *
 644  * This function must be called with @dev lock held.  When called for a
 645  * USB interface, @dev->parent lock must be held as well.
 646  *
 647  * If the device has a parent, runtime-resume the parent before driver probing.
 648  */
 649 int driver_probe_device(struct device_driver *drv, struct device *dev)
 650 {
 651         int ret = 0;
 652
 653         if (!device_is_registered(dev))
 654                 return -ENODEV;
 655
 656         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 657                  drv->bus->name, __func__, dev_name(dev), drv->name);
 658
 659         pm_runtime_get_suppliers(dev);
 660         if (dev->parent)
 661                 pm_runtime_get_sync(dev->parent);
 662
 663         pm_runtime_barrier(dev);
 664         if (initcall_debug)
 665                 ret = really_probe_debug(dev, drv);
 666         else
 667                 ret = really_probe(dev, drv);
 668         pm_request_idle(dev);
 669
 670         if (dev->parent)
 671                 pm_runtime_put(dev->parent);
 672
 673         pm_runtime_put_suppliers(dev);
 674         return ret;
 675 }
 676
 677 bool driver_allows_async_probing(struct device_driver *drv)
 678 {
 679         switch (drv->probe_type) {
 680         case PROBE_PREFER_ASYNCHRONOUS:
 681                 return true;
 682
 683         case PROBE_FORCE_SYNCHRONOUS:
 684                 return false;
 685
 686         default:
 687                 if (module_requested_async_probing(drv->owner))
 688                         return true;
 689
 690                 return false;
 691         }
 692 }
 693
 694 struct device_attach_data {
 695         struct device *dev;
 696
 697         /*
 698          * Indicates whether we are are considering asynchronous probing or
 699          * not. Only initial binding after device or driver registration
 700          * (including deferral processing) may be done asynchronously, the
 701          * rest is always synchronous, as we expect it is being done by
 702          * request from userspace.
 703          */
 704         bool check_async;
 705
 706         /*
 707          * Indicates if we are binding synchronous or asynchronous drivers.
 708          * When asynchronous probing is enabled we'll execute 2 passes
 709          * over drivers: first pass doing synchronous probing and second
 710          * doing asynchronous probing (if synchronous did not succeed -
 711          * most likely because there was no driver requiring synchronous
 712          * probing - and we found asynchronous driver during first pass).
 713          * The 2 passes are done because we can't shoot asynchronous
 714          * probe for given device and driver from bus_for_each_drv() since
 715          * driver pointer is not guaranteed to stay valid once
 716          * bus_for_each_drv() iterates to the next driver on the bus.
 717          */
 718         bool want_async;
 719
 720         /*
 721          * We'll set have_async to 'true' if, while scanning for matching
 722          * driver, we'll encounter one that requests asynchronous probing.
 723          */
 724         bool have_async;
 725 };
 726
 727 static int __device_attach_driver(struct device_driver *drv, void *_data)
 728 {
 729         struct device_attach_data *data = _data;
 730         struct device *dev = data->dev;
 731         bool async_allowed;
 732         int ret;
 733
 734         /*
 735          * Check if device has already been claimed. This may
 736          * happen with driver loading, device discovery/registration,
 737          * and deferred probe processing happens all at once with
 738          * multiple threads.
 739          */
 740         if (dev->driver)
 741                 return -EBUSY;
 742
 743         ret = driver_match_device(drv, dev);
 744         if (ret == 0) {
 745                 /* no match */
 746                 return 0;
 747         } else if (ret == -EPROBE_DEFER) {
 748                 dev_dbg(dev, "Device match requests probe deferral\n");
 749                 driver_deferred_probe_add(dev);
 750         } else if (ret < 0) {
 751                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 752                 return ret;
 753         } /* ret > 0 means positive match */
 754
 755         async_allowed = driver_allows_async_probing(drv);
 756
 757         if (async_allowed)
 758                 data->have_async = true;
 759
 760         if (data->check_async && async_allowed != data->want_async)
 761                 return 0;
 762
 763         return driver_probe_device(drv, dev);
 764 }
 765
 766 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 767 {
 768         struct device *dev = _dev;
 769         struct device_attach_data data = {
 770                 .dev            = dev,
 771                 .check_async    = true,
 772                 .want_async     = true,
 773         };
 774
 775         device_lock(dev);
 776
 777         if (dev->parent)
 778                 pm_runtime_get_sync(dev->parent);
 779
 780         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 781         dev_dbg(dev, "async probe completed\n");
 782
 783         pm_request_idle(dev);
 784
 785         if (dev->parent)
 786                 pm_runtime_put(dev->parent);
 787
 788         device_unlock(dev);
 789
 790         put_device(dev);
 791 }
 792
 793 static int __device_attach(struct device *dev, bool allow_async)
 794 {
 795         int ret = 0;
 796
 797         device_lock(dev);
 798         if (dev->driver) {
 799                 if (device_is_bound(dev)) {
 800                         ret = 1;
 801                         goto out_unlock;
 802                 }
 803                 ret = device_bind_driver(dev);
 804                 if (ret == 0)
 805                         ret = 1;
 806                 else {
 807                         dev->driver = NULL;
 808                         ret = 0;
 809                 }
 810         } else {
 811                 struct device_attach_data data = {
 812                         .dev = dev,
 813                         .check_async = allow_async,
 814                         .want_async = false,
 815                 };
 816
 817                 if (dev->parent)
 818                         pm_runtime_get_sync(dev->parent);
 819
 820                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 821                                         __device_attach_driver);
 822                 if (!ret && allow_async && data.have_async) {
 823                         /*
 824                          * If we could not find appropriate driver
 825                          * synchronously and we are allowed to do
 826                          * async probes and there are drivers that
 827                          * want to probe asynchronously, we'll
 828                          * try them.
 829                          */
 830                         dev_dbg(dev, "scheduling asynchronous probe\n");
 831                         get_device(dev);
 832                         async_schedule(__device_attach_async_helper, dev);
 833                 } else {
 834                         pm_request_idle(dev);
 835                 }
 836
 837                 if (dev->parent)
 838                         pm_runtime_put(dev->parent);
 839         }
 840 out_unlock:
 841         device_unlock(dev);
 842         return ret;
 843 }
 844
 845 /**
 846  * device_attach - try to attach device to a driver.
 847  * @dev: device.
 848  *
 849  * Walk the list of drivers that the bus has and call
 850  * driver_probe_device() for each pair. If a compatible
 851  * pair is found, break out and return.
 852  *
 853  * Returns 1 if the device was bound to a driver;
 854  * 0 if no matching driver was found;
 855  * -ENODEV if the device is not registered.
 856  *
 857  * When called for a USB interface, @dev->parent lock must be held.
 858  */
 859 int device_attach(struct device *dev)
 860 {
 861         return __device_attach(dev, false);
 862 }
 863 EXPORT_SYMBOL_GPL(device_attach);
 864
 865 void device_initial_probe(struct device *dev)
 866 {
 867         __device_attach(dev, true);
 868 }
 869
 870 static int __driver_attach(struct device *dev, void *data)
 871 {
 872         struct device_driver *drv = data;
 873         int ret;
 874
 875         /*
 876          * Lock device and try to bind to it. We drop the error
 877          * here and always return 0, because we need to keep trying
 878          * to bind to devices and some drivers will return an error
 879          * simply if it didn't support the device.
 880          *
 881          * driver_probe_device() will spit a warning if there
 882          * is an error.
 883          */
 884
 885         ret = driver_match_device(drv, dev);
 886         if (ret == 0) {
 887                 /* no match */
 888                 return 0;
 889         } else if (ret == -EPROBE_DEFER) {
 890                 dev_dbg(dev, "Device match requests probe deferral\n");
 891                 driver_deferred_probe_add(dev);
 892         } else if (ret < 0) {
 893                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 894                 return ret;
 895         } /* ret > 0 means positive match */
 896
 897         if (dev->parent && dev->bus->need_parent_lock)
 898                 device_lock(dev->parent);
 899         device_lock(dev);
 900         if (!dev->driver)
 901                 driver_probe_device(drv, dev);
 902         device_unlock(dev);
 903         if (dev->parent && dev->bus->need_parent_lock)
 904                 device_unlock(dev->parent);
 905
 906         return 0;
 907 }
 908
 909 /**
 910  * driver_attach - try to bind driver to devices.
 911  * @drv: driver.
 912  *
 913  * Walk the list of devices that the bus has on it and try to
 914  * match the driver with each one.  If driver_probe_device()
 915  * returns 0 and the @dev->driver is set, we've found a
 916  * compatible pair.
 917  */
 918 int driver_attach(struct device_driver *drv)
 919 {
 920         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 921 }
 922 EXPORT_SYMBOL_GPL(driver_attach);
 923
 924 /*
 925  * __device_release_driver() must be called with @dev lock held.
 926  * When called for a USB interface, @dev->parent lock must be held as well.
 927  */
 928 static void __device_release_driver(struct device *dev, struct device *parent)
 929 {
 930         struct device_driver *drv;
 931
 932         drv = dev->driver;
 933         if (drv) {
 934                 while (device_links_busy(dev)) {
 935                         device_unlock(dev);
 936                         if (parent && dev->bus->need_parent_lock)
 937                                 device_unlock(parent);
 938
 939                         device_links_unbind_consumers(dev);
 940                         if (parent && dev->bus->need_parent_lock)
 941                                 device_lock(parent);
 942
 943                         device_lock(dev);
 944                         /*
 945                          * A concurrent invocation of the same function might
 946                          * have released the driver successfully while this one
 947                          * was waiting, so check for that.
 948                          */
 949                         if (dev->driver != drv)
 950                                 return;
 951                 }
 952
 953                 pm_runtime_get_sync(dev);
 954                 pm_runtime_clean_up_links(dev);
 955
 956                 driver_sysfs_remove(dev);
 957
 958                 if (dev->bus)
 959                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 960                                                      BUS_NOTIFY_UNBIND_DRIVER,
 961                                                      dev);
 962
 963                 pm_runtime_put_sync(dev);
 964
 965                 if (dev->bus && dev->bus->remove)
 966                         dev->bus->remove(dev);
 967                 else if (drv->remove)
 968                         drv->remove(dev);
 969
 970                 device_links_driver_cleanup(dev);
 971                 arch_teardown_dma_ops(dev);
 972
 973                 devres_release_all(dev);
 974                 dev->driver = NULL;
 975                 dev_set_drvdata(dev, NULL);
 976                 if (dev->pm_domain && dev->pm_domain->dismiss)
 977                         dev->pm_domain->dismiss(dev);
 978                 pm_runtime_reinit(dev);
 979                 dev_pm_set_driver_flags(dev, 0);
 980
 981                 klist_remove(&dev->p->knode_driver);
 982                 device_pm_check_callbacks(dev);
 983                 if (dev->bus)
 984                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 985                                                      BUS_NOTIFY_UNBOUND_DRIVER,
 986                                                      dev);
 987
 988                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
 989         }
 990 }
 991
 992 void device_release_driver_internal(struct device *dev,
 993                                     struct device_driver *drv,
 994                                     struct device *parent)
 995 {
 996         if (parent && dev->bus->need_parent_lock)
 997                 device_lock(parent);
 998
 999         device_lock(dev);
1000         if (!drv || drv == dev->driver)
1001                 __device_release_driver(dev, parent);
1002
1003         device_unlock(dev);
1004         if (parent && dev->bus->need_parent_lock)
1005                 device_unlock(parent);
1006 }
1007
1008 /**
1009  * device_release_driver - manually detach device from driver.
1010  * @dev: device.
1011  *
1012  * Manually detach device from driver.
1013  * When called for a USB interface, @dev->parent lock must be held.
1014  *
1015  * If this function is to be called with @dev->parent lock held, ensure that
1016  * the device's consumers are unbound in advance or that their locks can be
1017  * acquired under the @dev->parent lock.
1018  */
1019 void device_release_driver(struct device *dev)
1020 {
1021         /*
1022          * If anyone calls device_release_driver() recursively from
1023          * within their ->remove callback for the same device, they
1024          * will deadlock right here.
1025          */
1026         device_release_driver_internal(dev, NULL, NULL);
1027 }
1028 EXPORT_SYMBOL_GPL(device_release_driver);
1029
1030 /**
1031  * driver_detach - detach driver from all devices it controls.
1032  * @drv: driver.
1033  */
1034 void driver_detach(struct device_driver *drv)
1035 {
1036         struct device_private *dev_prv;
1037         struct device *dev;
1038
1039         if (driver_allows_async_probing(drv))
1040                 async_synchronize_full();
1041
1042         for (;;) {
1043                 spin_lock(&drv->p->klist_devices.k_lock);
1044                 if (list_empty(&drv->p->klist_devices.k_list)) {
1045                         spin_unlock(&drv->p->klist_devices.k_lock);
1046                         break;
1047                 }
1048                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
1049                                      struct device_private,
1050                                      knode_driver.n_node);
1051                 dev = dev_prv->device;
1052                 get_device(dev);
1053                 spin_unlock(&drv->p->klist_devices.k_lock);
1054                 device_release_driver_internal(dev, drv, dev->parent);
1055                 put_device(dev);
1056         }
1057 }