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 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/defere device's probes
 183  *
 184  *      It will disable probing of devices and defer their probes instead.
 185  */
 186 void device_block_probing(void)
 187 {
 188         defer_all_probes = true;
 189         /* sync with probes to avoid races. */
 190         wait_for_device_probe();
 191 }
 192
 193 /**
 194  * device_unblock_probing() - Unblock/enable device's probes
 195  *
 196  *      It will restore normal behavior and trigger re-probing of deferred
 197  * devices.
 198  */
 199 void device_unblock_probing(void)
 200 {
 201         defer_all_probes = false;
 202         driver_deferred_probe_trigger();
 203 }
 204
 205 /*
 206  * deferred_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         deferred_probe_timeout = simple_strtol(str, NULL, 10);
 227         return 1;
 228 }
 229 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 230
 231 /**
 232  * driver_deferred_probe_check_state() - Check deferred probe state
 233  * @dev: device to check
 234  *
 235  * Returns -ENODEV if init is done and all built-in drivers have had a chance
 236  * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug
 237  * timeout has expired, or -EPROBE_DEFER if none of those conditions are met.
 238  *
 239  * Drivers or subsystems can opt-in to calling this function instead of directly
 240  * returning -EPROBE_DEFER.
 241  */
 242 int driver_deferred_probe_check_state(struct device *dev)
 243 {
 244         if (initcalls_done) {
 245                 if (!deferred_probe_timeout) {
 246                         dev_WARN(dev, "deferred probe timeout, ignoring dependency");
 247                         return -ETIMEDOUT;
 248                 }
 249                 dev_warn(dev, "ignoring dependency for device, assuming no driver");
 250                 return -ENODEV;
 251         }
 252         return -EPROBE_DEFER;
 253 }
 254
 255 static void deferred_probe_timeout_work_func(struct work_struct *work)
 256 {
 257         struct device_private *p;
 258
 259         deferred_probe_timeout = 0;
 260         driver_deferred_probe_trigger();
 261         flush_work(&deferred_probe_work);
 262
 263         mutex_lock(&deferred_probe_mutex);
 264         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 265                 dev_info(p->device, "deferred probe pending\n");
 266         mutex_unlock(&deferred_probe_mutex);
 267 }
 268 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 269
 270 /**
 271  * deferred_probe_initcall() - Enable probing of deferred devices
 272  *
 273  * We don't want to get in the way when the bulk of drivers are getting probed.
 274  * Instead, this initcall makes sure that deferred probing is delayed until
 275  * late_initcall time.
 276  */
 277 static int deferred_probe_initcall(void)
 278 {
 279         deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
 280                                                NULL, &deferred_devs_fops);
 281
 282         driver_deferred_probe_enable = true;
 283         driver_deferred_probe_trigger();
 284         /* Sort as many dependencies as possible before exiting initcalls */
 285         flush_work(&deferred_probe_work);
 286         initcalls_done = true;
 287
 288         /*
 289          * Trigger deferred probe again, this time we won't defer anything
 290          * that is optional
 291          */
 292         driver_deferred_probe_trigger();
 293         flush_work(&deferred_probe_work);
 294
 295         if (deferred_probe_timeout > 0) {
 296                 schedule_delayed_work(&deferred_probe_timeout_work,
 297                         deferred_probe_timeout * HZ);
 298         }
 299         return 0;
 300 }
 301 late_initcall(deferred_probe_initcall);
 302
 303 static void __exit deferred_probe_exit(void)
 304 {
 305         debugfs_remove_recursive(deferred_devices);
 306 }
 307 __exitcall(deferred_probe_exit);
 308
 309 /**
 310  * device_is_bound() - Check if device is bound to a driver
 311  * @dev: device to check
 312  *
 313  * Returns true if passed device has already finished probing successfully
 314  * against a driver.
 315  *
 316  * This function must be called with the device lock held.
 317  */
 318 bool device_is_bound(struct device *dev)
 319 {
 320         return dev->p && klist_node_attached(&dev->p->knode_driver);
 321 }
 322
 323 static void driver_bound(struct device *dev)
 324 {
 325         if (device_is_bound(dev)) {
 326                 printk(KERN_WARNING "%s: device %s already bound\n",
 327                         __func__, kobject_name(&dev->kobj));
 328                 return;
 329         }
 330
 331         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 332                  __func__, dev_name(dev));
 333
 334         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 335         device_links_driver_bound(dev);
 336
 337         device_pm_check_callbacks(dev);
 338
 339         /*
 340          * Make sure the device is no longer in one of the deferred lists and
 341          * kick off retrying all pending devices
 342          */
 343         driver_deferred_probe_del(dev);
 344         driver_deferred_probe_trigger();
 345
 346         if (dev->bus)
 347                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 348                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 349
 350         kobject_uevent(&dev->kobj, KOBJ_BIND);
 351 }
 352
 353 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 354                             const char *buf, size_t count)
 355 {
 356         device_lock(dev);
 357         dev->driver->coredump(dev);
 358         device_unlock(dev);
 359
 360         return count;
 361 }
 362 static DEVICE_ATTR_WO(coredump);
 363
 364 static int driver_sysfs_add(struct device *dev)
 365 {
 366         int ret;
 367
 368         if (dev->bus)
 369                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 370                                              BUS_NOTIFY_BIND_DRIVER, dev);
 371
 372         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 373                                 kobject_name(&dev->kobj));
 374         if (ret)
 375                 goto fail;
 376
 377         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 378                                 "driver");
 379         if (ret)
 380                 goto rm_dev;
 381
 382         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
 383             !device_create_file(dev, &dev_attr_coredump))
 384                 return 0;
 385
 386         sysfs_remove_link(&dev->kobj, "driver");
 387
 388 rm_dev:
 389         sysfs_remove_link(&dev->driver->p->kobj,
 390                           kobject_name(&dev->kobj));
 391
 392 fail:
 393         return ret;
 394 }
 395
 396 static void driver_sysfs_remove(struct device *dev)
 397 {
 398         struct device_driver *drv = dev->driver;
 399
 400         if (drv) {
 401                 if (drv->coredump)
 402                         device_remove_file(dev, &dev_attr_coredump);
 403                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 404                 sysfs_remove_link(&dev->kobj, "driver");
 405         }
 406 }
 407
 408 /**
 409  * device_bind_driver - bind a driver to one device.
 410  * @dev: device.
 411  *
 412  * Allow manual attachment of a driver to a device.
 413  * Caller must have already set @dev->driver.
 414  *
 415  * Note that this does not modify the bus reference count
 416  * nor take the bus's rwsem. Please verify those are accounted
 417  * for before calling this. (It is ok to call with no other effort
 418  * from a driver's probe() method.)
 419  *
 420  * This function must be called with the device lock held.
 421  */
 422 int device_bind_driver(struct device *dev)
 423 {
 424         int ret;
 425
 426         ret = driver_sysfs_add(dev);
 427         if (!ret)
 428                 driver_bound(dev);
 429         else if (dev->bus)
 430                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 431                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 432         return ret;
 433 }
 434 EXPORT_SYMBOL_GPL(device_bind_driver);
 435
 436 static atomic_t probe_count = ATOMIC_INIT(0);
 437 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 438
 439 static void driver_deferred_probe_add_trigger(struct device *dev,
 440                                               int local_trigger_count)
 441 {
 442         driver_deferred_probe_add(dev);
 443         /* Did a trigger occur while probing? Need to re-trigger if yes */
 444         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 445                 driver_deferred_probe_trigger();
 446 }
 447
 448 static int really_probe(struct device *dev, struct device_driver *drv)
 449 {
 450         int ret = -EPROBE_DEFER;
 451         int local_trigger_count = atomic_read(&deferred_trigger_count);
 452         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 453                            !drv->suppress_bind_attrs;
 454
 455         if (defer_all_probes) {
 456                 /*
 457                  * Value of defer_all_probes can be set only by
 458                  * device_defer_all_probes_enable() which, in turn, will call
 459                  * wait_for_device_probe() right after that to avoid any races.
 460                  */
 461                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 462                 driver_deferred_probe_add(dev);
 463                 return ret;
 464         }
 465
 466         ret = device_links_check_suppliers(dev);
 467         if (ret == -EPROBE_DEFER)
 468                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 469         if (ret)
 470                 return ret;
 471
 472         atomic_inc(&probe_count);
 473         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 474                  drv->bus->name, __func__, drv->name, dev_name(dev));
 475         if (!list_empty(&dev->devres_head)) {
 476                 dev_crit(dev, "Resources present before probing\n");
 477                 ret = -EBUSY;
 478                 goto done;
 479         }
 480
 481 re_probe:
 482         dev->driver = drv;
 483
 484         /* If using pinctrl, bind pins now before probing */
 485         ret = pinctrl_bind_pins(dev);
 486         if (ret)
 487                 goto pinctrl_bind_failed;
 488
 489         ret = dma_configure(dev);
 490         if (ret)
 491                 goto probe_failed;
 492
 493         if (driver_sysfs_add(dev)) {
 494                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 495                         __func__, dev_name(dev));
 496                 goto probe_failed;
 497         }
 498
 499         if (dev->pm_domain && dev->pm_domain->activate) {
 500                 ret = dev->pm_domain->activate(dev);
 501                 if (ret)
 502                         goto probe_failed;
 503         }
 504
 505         if (dev->bus->probe) {
 506                 ret = dev->bus->probe(dev);
 507                 if (ret)
 508                         goto probe_failed;
 509         } else if (drv->probe) {
 510                 ret = drv->probe(dev);
 511                 if (ret)
 512                         goto probe_failed;
 513         }
 514
 515         if (test_remove) {
 516                 test_remove = false;
 517
 518                 if (dev->bus->remove)
 519                         dev->bus->remove(dev);
 520                 else if (drv->remove)
 521                         drv->remove(dev);
 522
 523                 devres_release_all(dev);
 524                 driver_sysfs_remove(dev);
 525                 dev->driver = NULL;
 526                 dev_set_drvdata(dev, NULL);
 527                 if (dev->pm_domain && dev->pm_domain->dismiss)
 528                         dev->pm_domain->dismiss(dev);
 529                 pm_runtime_reinit(dev);
 530
 531                 goto re_probe;
 532         }
 533
 534         pinctrl_init_done(dev);
 535
 536         if (dev->pm_domain && dev->pm_domain->sync)
 537                 dev->pm_domain->sync(dev);
 538
 539         driver_bound(dev);
 540         ret = 1;
 541         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 542                  drv->bus->name, __func__, dev_name(dev), drv->name);
 543         goto done;
 544
 545 probe_failed:
 546         if (dev->bus)
 547                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 548                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 549 pinctrl_bind_failed:
 550         device_links_no_driver(dev);
 551         devres_release_all(dev);
 552         dma_deconfigure(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_all(&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         ret = driver_match_device(drv, dev);
 735         if (ret == 0) {
 736                 /* no match */
 737                 return 0;
 738         } else if (ret == -EPROBE_DEFER) {
 739                 dev_dbg(dev, "Device match requests probe deferral\n");
 740                 driver_deferred_probe_add(dev);
 741                 /*
 742                  * Device can't match with a driver right now, so don't attempt
 743                  * to match or bind with other drivers on the bus.
 744                  */
 745                 return ret;
 746         } else if (ret < 0) {
 747                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 748                 return ret;
 749         } /* ret > 0 means positive match */
 750
 751         async_allowed = driver_allows_async_probing(drv);
 752
 753         if (async_allowed)
 754                 data->have_async = true;
 755
 756         if (data->check_async && async_allowed != data->want_async)
 757                 return 0;
 758
 759         return driver_probe_device(drv, dev);
 760 }
 761
 762 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 763 {
 764         struct device *dev = _dev;
 765         struct device_attach_data data = {
 766                 .dev            = dev,
 767                 .check_async    = true,
 768                 .want_async     = true,
 769         };
 770
 771         device_lock(dev);
 772
 773         /*
 774          * Check if device has already been removed or claimed. This may
 775          * happen with driver loading, device discovery/registration,
 776          * and deferred probe processing happens all at once with
 777          * multiple threads.
 778          */
 779         if (dev->p->dead || dev->driver)
 780                 goto out_unlock;
 781
 782         if (dev->parent)
 783                 pm_runtime_get_sync(dev->parent);
 784
 785         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 786         dev_dbg(dev, "async probe completed\n");
 787
 788         pm_request_idle(dev);
 789
 790         if (dev->parent)
 791                 pm_runtime_put(dev->parent);
 792 out_unlock:
 793         device_unlock(dev);
 794
 795         put_device(dev);
 796 }
 797
 798 static int __device_attach(struct device *dev, bool allow_async)
 799 {
 800         int ret = 0;
 801
 802         device_lock(dev);
 803         if (dev->p->dead) {
 804                 goto out_unlock;
 805         } else if (dev->driver) {
 806                 if (device_is_bound(dev)) {
 807                         ret = 1;
 808                         goto out_unlock;
 809                 }
 810                 ret = device_bind_driver(dev);
 811                 if (ret == 0)
 812                         ret = 1;
 813                 else {
 814                         dev->driver = NULL;
 815                         ret = 0;
 816                 }
 817         } else {
 818                 struct device_attach_data data = {
 819                         .dev = dev,
 820                         .check_async = allow_async,
 821                         .want_async = false,
 822                 };
 823
 824                 if (dev->parent)
 825                         pm_runtime_get_sync(dev->parent);
 826
 827                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 828                                         __device_attach_driver);
 829                 if (!ret && allow_async && data.have_async) {
 830                         /*
 831                          * If we could not find appropriate driver
 832                          * synchronously and we are allowed to do
 833                          * async probes and there are drivers that
 834                          * want to probe asynchronously, we'll
 835                          * try them.
 836                          */
 837                         dev_dbg(dev, "scheduling asynchronous probe\n");
 838                         get_device(dev);
 839                         async_schedule(__device_attach_async_helper, dev);
 840                 } else {
 841                         pm_request_idle(dev);
 842                 }
 843
 844                 if (dev->parent)
 845                         pm_runtime_put(dev->parent);
 846         }
 847 out_unlock:
 848         device_unlock(dev);
 849         return ret;
 850 }
 851
 852 /**
 853  * device_attach - try to attach device to a driver.
 854  * @dev: device.
 855  *
 856  * Walk the list of drivers that the bus has and call
 857  * driver_probe_device() for each pair. If a compatible
 858  * pair is found, break out and return.
 859  *
 860  * Returns 1 if the device was bound to a driver;
 861  * 0 if no matching driver was found;
 862  * -ENODEV if the device is not registered.
 863  *
 864  * When called for a USB interface, @dev->parent lock must be held.
 865  */
 866 int device_attach(struct device *dev)
 867 {
 868         return __device_attach(dev, false);
 869 }
 870 EXPORT_SYMBOL_GPL(device_attach);
 871
 872 void device_initial_probe(struct device *dev)
 873 {
 874         __device_attach(dev, true);
 875 }
 876
 877 static int __driver_attach(struct device *dev, void *data)
 878 {
 879         struct device_driver *drv = data;
 880         int ret;
 881
 882         /*
 883          * Lock device and try to bind to it. We drop the error
 884          * here and always return 0, because we need to keep trying
 885          * to bind to devices and some drivers will return an error
 886          * simply if it didn't support the device.
 887          *
 888          * driver_probe_device() will spit a warning if there
 889          * is an error.
 890          */
 891
 892         ret = driver_match_device(drv, dev);
 893         if (ret == 0) {
 894                 /* no match */
 895                 return 0;
 896         } else if (ret == -EPROBE_DEFER) {
 897                 dev_dbg(dev, "Device match requests probe deferral\n");
 898                 driver_deferred_probe_add(dev);
 899                 /*
 900                  * Driver could not match with device, but may match with
 901                  * another device on the bus.
 902                  */
 903                 return 0;
 904         } else if (ret < 0) {
 905                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 906                 return ret;
 907         } /* ret > 0 means positive match */
 908
 909         if (dev->parent && dev->bus->need_parent_lock)
 910                 device_lock(dev->parent);
 911         device_lock(dev);
 912         if (!dev->p->dead && !dev->driver)
 913                 driver_probe_device(drv, dev);
 914         device_unlock(dev);
 915         if (dev->parent && dev->bus->need_parent_lock)
 916                 device_unlock(dev->parent);
 917
 918         return 0;
 919 }
 920
 921 /**
 922  * driver_attach - try to bind driver to devices.
 923  * @drv: driver.
 924  *
 925  * Walk the list of devices that the bus has on it and try to
 926  * match the driver with each one.  If driver_probe_device()
 927  * returns 0 and the @dev->driver is set, we've found a
 928  * compatible pair.
 929  */
 930 int driver_attach(struct device_driver *drv)
 931 {
 932         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 933 }
 934 EXPORT_SYMBOL_GPL(driver_attach);
 935
 936 /*
 937  * __device_release_driver() must be called with @dev lock held.
 938  * When called for a USB interface, @dev->parent lock must be held as well.
 939  */
 940 static void __device_release_driver(struct device *dev, struct device *parent)
 941 {
 942         struct device_driver *drv;
 943
 944         drv = dev->driver;
 945         if (drv) {
 946                 pm_runtime_get_sync(dev);
 947
 948                 while (device_links_busy(dev)) {
 949                         device_unlock(dev);
 950                         if (parent && dev->bus->need_parent_lock)
 951                                 device_unlock(parent);
 952
 953                         device_links_unbind_consumers(dev);
 954                         if (parent && dev->bus->need_parent_lock)
 955                                 device_lock(parent);
 956
 957                         device_lock(dev);
 958                         /*
 959                          * A concurrent invocation of the same function might
 960                          * have released the driver successfully while this one
 961                          * was waiting, so check for that.
 962                          */
 963                         if (dev->driver != drv) {
 964                                 pm_runtime_put(dev);
 965                                 return;
 966                         }
 967                 }
 968
 969                 pm_runtime_clean_up_links(dev);
 970
 971                 driver_sysfs_remove(dev);
 972
 973                 if (dev->bus)
 974                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 975                                                      BUS_NOTIFY_UNBIND_DRIVER,
 976                                                      dev);
 977
 978                 pm_runtime_put_sync(dev);
 979
 980                 if (dev->bus && dev->bus->remove)
 981                         dev->bus->remove(dev);
 982                 else if (drv->remove)
 983                         drv->remove(dev);
 984
 985                 device_links_driver_cleanup(dev);
 986
 987                 devres_release_all(dev);
 988                 dma_deconfigure(dev);
 989                 dev->driver = NULL;
 990                 dev_set_drvdata(dev, NULL);
 991                 if (dev->pm_domain && dev->pm_domain->dismiss)
 992                         dev->pm_domain->dismiss(dev);
 993                 pm_runtime_reinit(dev);
 994                 dev_pm_set_driver_flags(dev, 0);
 995
 996                 klist_remove(&dev->p->knode_driver);
 997                 device_pm_check_callbacks(dev);
 998                 if (dev->bus)
 999                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1000                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1001                                                      dev);
1002
1003                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1004         }
1005 }
1006
1007 void device_release_driver_internal(struct device *dev,
1008                                     struct device_driver *drv,
1009                                     struct device *parent)
1010 {
1011         if (parent && dev->bus->need_parent_lock)
1012                 device_lock(parent);
1013
1014         device_lock(dev);
1015         if (!drv || drv == dev->driver)
1016                 __device_release_driver(dev, parent);
1017
1018         device_unlock(dev);
1019         if (parent && dev->bus->need_parent_lock)
1020                 device_unlock(parent);
1021 }
1022
1023 /**
1024  * device_release_driver - manually detach device from driver.
1025  * @dev: device.
1026  *
1027  * Manually detach device from driver.
1028  * When called for a USB interface, @dev->parent lock must be held.
1029  *
1030  * If this function is to be called with @dev->parent lock held, ensure that
1031  * the device's consumers are unbound in advance or that their locks can be
1032  * acquired under the @dev->parent lock.
1033  */
1034 void device_release_driver(struct device *dev)
1035 {
1036         /*
1037          * If anyone calls device_release_driver() recursively from
1038          * within their ->remove callback for the same device, they
1039          * will deadlock right here.
1040          */
1041         device_release_driver_internal(dev, NULL, NULL);
1042 }
1043 EXPORT_SYMBOL_GPL(device_release_driver);
1044
1045 /**
1046  * driver_detach - detach driver from all devices it controls.
1047  * @drv: driver.
1048  */
1049 void driver_detach(struct device_driver *drv)
1050 {
1051         struct device_private *dev_prv;
1052         struct device *dev;
1053
1054         if (driver_allows_async_probing(drv))
1055                 async_synchronize_full();
1056
1057         for (;;) {
1058                 spin_lock(&drv->p->klist_devices.k_lock);
1059                 if (list_empty(&drv->p->klist_devices.k_list)) {
1060                         spin_unlock(&drv->p->klist_devices.k_lock);
1061                         break;
1062                 }
1063                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
1064                                      struct device_private,
1065                                      knode_driver.n_node);
1066                 dev = dev_prv->device;
1067                 get_device(dev);
1068                 spin_unlock(&drv->p->klist_devices.k_lock);
1069                 device_release_driver_internal(dev, drv, dev->parent);
1070                 put_device(dev);
1071         }
1072 }