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 /* Save the async probe drivers' name from kernel cmdline */
  61 #define ASYNC_DRV_NAMES_MAX_LEN 256
  62 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
  63
  64 /*
  65  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  66  * to prohibit probing of devices as it could be unsafe.
  67  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  68  */
  69 static bool defer_all_probes;
  70
  71 /*
  72  * deferred_probe_work_func() - Retry probing devices in the active list.
  73  */
  74 static void deferred_probe_work_func(struct work_struct *work)
  75 {
  76         struct device *dev;
  77         struct device_private *private;
  78         /*
  79          * This block processes every device in the deferred 'active' list.
  80          * Each device is removed from the active list and passed to
  81          * bus_probe_device() to re-attempt the probe.  The loop continues
  82          * until every device in the active list is removed and retried.
  83          *
  84          * Note: Once the device is removed from the list and the mutex is
  85          * released, it is possible for the device get freed by another thread
  86          * and cause a illegal pointer dereference.  This code uses
  87          * get/put_device() to ensure the device structure cannot disappear
  88          * from under our feet.
  89          */
  90         mutex_lock(&deferred_probe_mutex);
  91         while (!list_empty(&deferred_probe_active_list)) {
  92                 private = list_first_entry(&deferred_probe_active_list,
  93                                         typeof(*dev->p), deferred_probe);
  94                 dev = private->device;
  95                 list_del_init(&private->deferred_probe);
  96
  97                 get_device(dev);
  98
  99                 /*
 100                  * Drop the mutex while probing each device; the probe path may
 101                  * manipulate the deferred list
 102                  */
 103                 mutex_unlock(&deferred_probe_mutex);
 104
 105                 /*
 106                  * Force the device to the end of the dpm_list since
 107                  * the PM code assumes that the order we add things to
 108                  * the list is a good order for suspend but deferred
 109                  * probe makes that very unsafe.
 110                  */
 111                 device_pm_move_to_tail(dev);
 112
 113                 dev_dbg(dev, "Retrying from deferred list\n");
 114                 bus_probe_device(dev);
 115                 mutex_lock(&deferred_probe_mutex);
 116
 117                 put_device(dev);
 118         }
 119         mutex_unlock(&deferred_probe_mutex);
 120 }
 121 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 122
 123 void driver_deferred_probe_add(struct device *dev)
 124 {
 125         mutex_lock(&deferred_probe_mutex);
 126         if (list_empty(&dev->p->deferred_probe)) {
 127                 dev_dbg(dev, "Added to deferred list\n");
 128                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 129         }
 130         mutex_unlock(&deferred_probe_mutex);
 131 }
 132
 133 void driver_deferred_probe_del(struct device *dev)
 134 {
 135         mutex_lock(&deferred_probe_mutex);
 136         if (!list_empty(&dev->p->deferred_probe)) {
 137                 dev_dbg(dev, "Removed from deferred list\n");
 138                 list_del_init(&dev->p->deferred_probe);
 139         }
 140         mutex_unlock(&deferred_probe_mutex);
 141 }
 142
 143 static bool driver_deferred_probe_enable = false;
 144 /**
 145  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 146  *
 147  * This functions moves all devices from the pending list to the active
 148  * list and schedules the deferred probe workqueue to process them.  It
 149  * should be called anytime a driver is successfully bound to a device.
 150  *
 151  * Note, there is a race condition in multi-threaded probe. In the case where
 152  * more than one device is probing at the same time, it is possible for one
 153  * probe to complete successfully while another is about to defer. If the second
 154  * depends on the first, then it will get put on the pending list after the
 155  * trigger event has already occurred and will be stuck there.
 156  *
 157  * The atomic 'deferred_trigger_count' is used to determine if a successful
 158  * trigger has occurred in the midst of probing a driver. If the trigger count
 159  * changes in the midst of a probe, then deferred processing should be triggered
 160  * again.
 161  */
 162 static void driver_deferred_probe_trigger(void)
 163 {
 164         if (!driver_deferred_probe_enable)
 165                 return;
 166
 167         /*
 168          * A successful probe means that all the devices in the pending list
 169          * should be triggered to be reprobed.  Move all the deferred devices
 170          * into the active list so they can be retried by the workqueue
 171          */
 172         mutex_lock(&deferred_probe_mutex);
 173         atomic_inc(&deferred_trigger_count);
 174         list_splice_tail_init(&deferred_probe_pending_list,
 175                               &deferred_probe_active_list);
 176         mutex_unlock(&deferred_probe_mutex);
 177
 178         /*
 179          * Kick the re-probe thread.  It may already be scheduled, but it is
 180          * safe to kick it again.
 181          */
 182         schedule_work(&deferred_probe_work);
 183 }
 184
 185 /**
 186  * device_block_probing() - Block/defer device's probes
 187  *
 188  *      It will disable probing of devices and defer their probes instead.
 189  */
 190 void device_block_probing(void)
 191 {
 192         defer_all_probes = true;
 193         /* sync with probes to avoid races. */
 194         wait_for_device_probe();
 195 }
 196
 197 /**
 198  * device_unblock_probing() - Unblock/enable device's probes
 199  *
 200  *      It will restore normal behavior and trigger re-probing of deferred
 201  * devices.
 202  */
 203 void device_unblock_probing(void)
 204 {
 205         defer_all_probes = false;
 206         driver_deferred_probe_trigger();
 207 }
 208
 209 /*
 210  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 211  */
 212 static int deferred_devs_show(struct seq_file *s, void *data)
 213 {
 214         struct device_private *curr;
 215
 216         mutex_lock(&deferred_probe_mutex);
 217
 218         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 219                 seq_printf(s, "%s\n", dev_name(curr->device));
 220
 221         mutex_unlock(&deferred_probe_mutex);
 222
 223         return 0;
 224 }
 225 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 226
 227 static int deferred_probe_timeout = -1;
 228 static int __init deferred_probe_timeout_setup(char *str)
 229 {
 230         int timeout;
 231
 232         if (!kstrtoint(str, 10, &timeout))
 233                 deferred_probe_timeout = timeout;
 234         return 1;
 235 }
 236 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 237
 238 /**
 239  * driver_deferred_probe_check_state() - Check deferred probe state
 240  * @dev: device to check
 241  *
 242  * Returns -ENODEV if init is done and all built-in drivers have had a chance
 243  * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug
 244  * timeout has expired, or -EPROBE_DEFER if none of those conditions are met.
 245  *
 246  * Drivers or subsystems can opt-in to calling this function instead of directly
 247  * returning -EPROBE_DEFER.
 248  */
 249 int driver_deferred_probe_check_state(struct device *dev)
 250 {
 251         if (initcalls_done) {
 252                 if (!deferred_probe_timeout) {
 253                         dev_WARN(dev, "deferred probe timeout, ignoring dependency");
 254                         return -ETIMEDOUT;
 255                 }
 256                 dev_warn(dev, "ignoring dependency for device, assuming no driver");
 257                 return -ENODEV;
 258         }
 259         return -EPROBE_DEFER;
 260 }
 261
 262 static void deferred_probe_timeout_work_func(struct work_struct *work)
 263 {
 264         struct device_private *private, *p;
 265
 266         deferred_probe_timeout = 0;
 267         driver_deferred_probe_trigger();
 268         flush_work(&deferred_probe_work);
 269
 270         list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe)
 271                 dev_info(private->device, "deferred probe pending");
 272 }
 273 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 274
 275 /**
 276  * deferred_probe_initcall() - Enable probing of deferred devices
 277  *
 278  * We don't want to get in the way when the bulk of drivers are getting probed.
 279  * Instead, this initcall makes sure that deferred probing is delayed until
 280  * late_initcall time.
 281  */
 282 static int deferred_probe_initcall(void)
 283 {
 284         deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
 285                                                NULL, &deferred_devs_fops);
 286
 287         driver_deferred_probe_enable = true;
 288         driver_deferred_probe_trigger();
 289         /* Sort as many dependencies as possible before exiting initcalls */
 290         flush_work(&deferred_probe_work);
 291         initcalls_done = true;
 292
 293         /*
 294          * Trigger deferred probe again, this time we won't defer anything
 295          * that is optional
 296          */
 297         driver_deferred_probe_trigger();
 298         flush_work(&deferred_probe_work);
 299
 300         if (deferred_probe_timeout > 0) {
 301                 schedule_delayed_work(&deferred_probe_timeout_work,
 302                         deferred_probe_timeout * HZ);
 303         }
 304         return 0;
 305 }
 306 late_initcall(deferred_probe_initcall);
 307
 308 static void __exit deferred_probe_exit(void)
 309 {
 310         debugfs_remove_recursive(deferred_devices);
 311 }
 312 __exitcall(deferred_probe_exit);
 313
 314 /**
 315  * device_is_bound() - Check if device is bound to a driver
 316  * @dev: device to check
 317  *
 318  * Returns true if passed device has already finished probing successfully
 319  * against a driver.
 320  *
 321  * This function must be called with the device lock held.
 322  */
 323 bool device_is_bound(struct device *dev)
 324 {
 325         return dev->p && klist_node_attached(&dev->p->knode_driver);
 326 }
 327
 328 static void driver_bound(struct device *dev)
 329 {
 330         if (device_is_bound(dev)) {
 331                 printk(KERN_WARNING "%s: device %s already bound\n",
 332                         __func__, kobject_name(&dev->kobj));
 333                 return;
 334         }
 335
 336         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 337                  __func__, dev_name(dev));
 338
 339         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 340         device_links_driver_bound(dev);
 341
 342         device_pm_check_callbacks(dev);
 343
 344         /*
 345          * Make sure the device is no longer in one of the deferred lists and
 346          * kick off retrying all pending devices
 347          */
 348         driver_deferred_probe_del(dev);
 349         driver_deferred_probe_trigger();
 350
 351         if (dev->bus)
 352                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 353                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 354
 355         kobject_uevent(&dev->kobj, KOBJ_BIND);
 356 }
 357
 358 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 359                             const char *buf, size_t count)
 360 {
 361         device_lock(dev);
 362         dev->driver->coredump(dev);
 363         device_unlock(dev);
 364
 365         return count;
 366 }
 367 static DEVICE_ATTR_WO(coredump);
 368
 369 static int driver_sysfs_add(struct device *dev)
 370 {
 371         int ret;
 372
 373         if (dev->bus)
 374                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 375                                              BUS_NOTIFY_BIND_DRIVER, dev);
 376
 377         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 378                                 kobject_name(&dev->kobj));
 379         if (ret)
 380                 goto fail;
 381
 382         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 383                                 "driver");
 384         if (ret)
 385                 goto rm_dev;
 386
 387         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
 388             !device_create_file(dev, &dev_attr_coredump))
 389                 return 0;
 390
 391         sysfs_remove_link(&dev->kobj, "driver");
 392
 393 rm_dev:
 394         sysfs_remove_link(&dev->driver->p->kobj,
 395                           kobject_name(&dev->kobj));
 396
 397 fail:
 398         return ret;
 399 }
 400
 401 static void driver_sysfs_remove(struct device *dev)
 402 {
 403         struct device_driver *drv = dev->driver;
 404
 405         if (drv) {
 406                 if (drv->coredump)
 407                         device_remove_file(dev, &dev_attr_coredump);
 408                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 409                 sysfs_remove_link(&dev->kobj, "driver");
 410         }
 411 }
 412
 413 /**
 414  * device_bind_driver - bind a driver to one device.
 415  * @dev: device.
 416  *
 417  * Allow manual attachment of a driver to a device.
 418  * Caller must have already set @dev->driver.
 419  *
 420  * Note that this does not modify the bus reference count
 421  * nor take the bus's rwsem. Please verify those are accounted
 422  * for before calling this. (It is ok to call with no other effort
 423  * from a driver's probe() method.)
 424  *
 425  * This function must be called with the device lock held.
 426  */
 427 int device_bind_driver(struct device *dev)
 428 {
 429         int ret;
 430
 431         ret = driver_sysfs_add(dev);
 432         if (!ret)
 433                 driver_bound(dev);
 434         else if (dev->bus)
 435                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 436                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 437         return ret;
 438 }
 439 EXPORT_SYMBOL_GPL(device_bind_driver);
 440
 441 static atomic_t probe_count = ATOMIC_INIT(0);
 442 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 443
 444 static void driver_deferred_probe_add_trigger(struct device *dev,
 445                                               int local_trigger_count)
 446 {
 447         driver_deferred_probe_add(dev);
 448         /* Did a trigger occur while probing? Need to re-trigger if yes */
 449         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 450                 driver_deferred_probe_trigger();
 451 }
 452
 453 static int really_probe(struct device *dev, struct device_driver *drv)
 454 {
 455         int ret = -EPROBE_DEFER;
 456         int local_trigger_count = atomic_read(&deferred_trigger_count);
 457         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 458                            !drv->suppress_bind_attrs;
 459
 460         if (defer_all_probes) {
 461                 /*
 462                  * Value of defer_all_probes can be set only by
 463                  * device_block_probing() which, in turn, will call
 464                  * wait_for_device_probe() right after that to avoid any races.
 465                  */
 466                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 467                 driver_deferred_probe_add(dev);
 468                 return ret;
 469         }
 470
 471         ret = device_links_check_suppliers(dev);
 472         if (ret == -EPROBE_DEFER)
 473                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 474         if (ret)
 475                 return ret;
 476
 477         atomic_inc(&probe_count);
 478         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 479                  drv->bus->name, __func__, drv->name, dev_name(dev));
 480         WARN_ON(!list_empty(&dev->devres_head));
 481
 482 re_probe:
 483         dev->driver = drv;
 484
 485         /* If using pinctrl, bind pins now before probing */
 486         ret = pinctrl_bind_pins(dev);
 487         if (ret)
 488                 goto pinctrl_bind_failed;
 489
 490         if (dev->bus->dma_configure) {
 491                 ret = dev->bus->dma_configure(dev);
 492                 if (ret)
 493                         goto probe_failed;
 494         }
 495
 496         if (driver_sysfs_add(dev)) {
 497                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 498                         __func__, dev_name(dev));
 499                 goto probe_failed;
 500         }
 501
 502         if (dev->pm_domain && dev->pm_domain->activate) {
 503                 ret = dev->pm_domain->activate(dev);
 504                 if (ret)
 505                         goto probe_failed;
 506         }
 507
 508         if (dev->bus->probe) {
 509                 ret = dev->bus->probe(dev);
 510                 if (ret)
 511                         goto probe_failed;
 512         } else if (drv->probe) {
 513                 ret = drv->probe(dev);
 514                 if (ret)
 515                         goto probe_failed;
 516         }
 517
 518         if (test_remove) {
 519                 test_remove = false;
 520
 521                 if (dev->bus->remove)
 522                         dev->bus->remove(dev);
 523                 else if (drv->remove)
 524                         drv->remove(dev);
 525
 526                 devres_release_all(dev);
 527                 driver_sysfs_remove(dev);
 528                 dev->driver = NULL;
 529                 dev_set_drvdata(dev, NULL);
 530                 if (dev->pm_domain && dev->pm_domain->dismiss)
 531                         dev->pm_domain->dismiss(dev);
 532                 pm_runtime_reinit(dev);
 533
 534                 goto re_probe;
 535         }
 536
 537         pinctrl_init_done(dev);
 538
 539         if (dev->pm_domain && dev->pm_domain->sync)
 540                 dev->pm_domain->sync(dev);
 541
 542         driver_bound(dev);
 543         ret = 1;
 544         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 545                  drv->bus->name, __func__, dev_name(dev), drv->name);
 546         goto done;
 547
 548 probe_failed:
 549         if (dev->bus)
 550                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 551                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 552 pinctrl_bind_failed:
 553         device_links_no_driver(dev);
 554         devres_release_all(dev);
 555         arch_teardown_dma_ops(dev);
 556         driver_sysfs_remove(dev);
 557         dev->driver = NULL;
 558         dev_set_drvdata(dev, NULL);
 559         if (dev->pm_domain && dev->pm_domain->dismiss)
 560                 dev->pm_domain->dismiss(dev);
 561         pm_runtime_reinit(dev);
 562         dev_pm_set_driver_flags(dev, 0);
 563
 564         switch (ret) {
 565         case -EPROBE_DEFER:
 566                 /* Driver requested deferred probing */
 567                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 568                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 569                 break;
 570         case -ENODEV:
 571         case -ENXIO:
 572                 pr_debug("%s: probe of %s rejects match %d\n",
 573                          drv->name, dev_name(dev), ret);
 574                 break;
 575         default:
 576                 /* driver matched but the probe failed */
 577                 printk(KERN_WARNING
 578                        "%s: probe of %s failed with error %d\n",
 579                        drv->name, dev_name(dev), ret);
 580         }
 581         /*
 582          * Ignore errors returned by ->probe so that the next driver can try
 583          * its luck.
 584          */
 585         ret = 0;
 586 done:
 587         atomic_dec(&probe_count);
 588         wake_up(&probe_waitqueue);
 589         return ret;
 590 }
 591
 592 /*
 593  * For initcall_debug, show the driver probe time.
 594  */
 595 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 596 {
 597         ktime_t calltime, delta, rettime;
 598         int ret;
 599
 600         calltime = ktime_get();
 601         ret = really_probe(dev, drv);
 602         rettime = ktime_get();
 603         delta = ktime_sub(rettime, calltime);
 604         printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
 605                dev_name(dev), ret, (s64) ktime_to_us(delta));
 606         return ret;
 607 }
 608
 609 /**
 610  * driver_probe_done
 611  * Determine if the probe sequence is finished or not.
 612  *
 613  * Should somehow figure out how to use a semaphore, not an atomic variable...
 614  */
 615 int driver_probe_done(void)
 616 {
 617         pr_debug("%s: probe_count = %d\n", __func__,
 618                  atomic_read(&probe_count));
 619         if (atomic_read(&probe_count))
 620                 return -EBUSY;
 621         return 0;
 622 }
 623
 624 /**
 625  * wait_for_device_probe
 626  * Wait for device probing to be completed.
 627  */
 628 void wait_for_device_probe(void)
 629 {
 630         /* wait for the deferred probe workqueue to finish */
 631         flush_work(&deferred_probe_work);
 632
 633         /* wait for the known devices to complete their probing */
 634         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 635         async_synchronize_full();
 636 }
 637 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 638
 639 /**
 640  * driver_probe_device - attempt to bind device & driver together
 641  * @drv: driver to bind a device to
 642  * @dev: device to try to bind to the driver
 643  *
 644  * This function returns -ENODEV if the device is not registered,
 645  * 1 if the device is bound successfully and 0 otherwise.
 646  *
 647  * This function must be called with @dev lock held.  When called for a
 648  * USB interface, @dev->parent lock must be held as well.
 649  *
 650  * If the device has a parent, runtime-resume the parent before driver probing.
 651  */
 652 int driver_probe_device(struct device_driver *drv, struct device *dev)
 653 {
 654         int ret = 0;
 655
 656         if (!device_is_registered(dev))
 657                 return -ENODEV;
 658
 659         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 660                  drv->bus->name, __func__, dev_name(dev), drv->name);
 661
 662         pm_runtime_get_suppliers(dev);
 663         if (dev->parent)
 664                 pm_runtime_get_sync(dev->parent);
 665
 666         pm_runtime_barrier(dev);
 667         if (initcall_debug)
 668                 ret = really_probe_debug(dev, drv);
 669         else
 670                 ret = really_probe(dev, drv);
 671         pm_request_idle(dev);
 672
 673         if (dev->parent)
 674                 pm_runtime_put(dev->parent);
 675
 676         pm_runtime_put_suppliers(dev);
 677         return ret;
 678 }
 679
 680 static inline bool cmdline_requested_async_probing(const char *drv_name)
 681 {
 682         return parse_option_str(async_probe_drv_names, drv_name);
 683 }
 684
 685 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 686 static int __init save_async_options(char *buf)
 687 {
 688         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 689                 printk(KERN_WARNING
 690                         "Too long list of driver names for 'driver_async_probe'!\n");
 691
 692         strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 693         return 0;
 694 }
 695 __setup("driver_async_probe=", save_async_options);
 696
 697 bool driver_allows_async_probing(struct device_driver *drv)
 698 {
 699         switch (drv->probe_type) {
 700         case PROBE_PREFER_ASYNCHRONOUS:
 701                 return true;
 702
 703         case PROBE_FORCE_SYNCHRONOUS:
 704                 return false;
 705
 706         default:
 707                 if (cmdline_requested_async_probing(drv->name))
 708                         return true;
 709
 710                 if (module_requested_async_probing(drv->owner))
 711                         return true;
 712
 713                 return false;
 714         }
 715 }
 716
 717 struct device_attach_data {
 718         struct device *dev;
 719
 720         /*
 721          * Indicates whether we are are considering asynchronous probing or
 722          * not. Only initial binding after device or driver registration
 723          * (including deferral processing) may be done asynchronously, the
 724          * rest is always synchronous, as we expect it is being done by
 725          * request from userspace.
 726          */
 727         bool check_async;
 728
 729         /*
 730          * Indicates if we are binding synchronous or asynchronous drivers.
 731          * When asynchronous probing is enabled we'll execute 2 passes
 732          * over drivers: first pass doing synchronous probing and second
 733          * doing asynchronous probing (if synchronous did not succeed -
 734          * most likely because there was no driver requiring synchronous
 735          * probing - and we found asynchronous driver during first pass).
 736          * The 2 passes are done because we can't shoot asynchronous
 737          * probe for given device and driver from bus_for_each_drv() since
 738          * driver pointer is not guaranteed to stay valid once
 739          * bus_for_each_drv() iterates to the next driver on the bus.
 740          */
 741         bool want_async;
 742
 743         /*
 744          * We'll set have_async to 'true' if, while scanning for matching
 745          * driver, we'll encounter one that requests asynchronous probing.
 746          */
 747         bool have_async;
 748 };
 749
 750 static int __device_attach_driver(struct device_driver *drv, void *_data)
 751 {
 752         struct device_attach_data *data = _data;
 753         struct device *dev = data->dev;
 754         bool async_allowed;
 755         int ret;
 756
 757         ret = driver_match_device(drv, dev);
 758         if (ret == 0) {
 759                 /* no match */
 760                 return 0;
 761         } else if (ret == -EPROBE_DEFER) {
 762                 dev_dbg(dev, "Device match requests probe deferral\n");
 763                 driver_deferred_probe_add(dev);
 764         } else if (ret < 0) {
 765                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 766                 return ret;
 767         } /* ret > 0 means positive match */
 768
 769         async_allowed = driver_allows_async_probing(drv);
 770
 771         if (async_allowed)
 772                 data->have_async = true;
 773
 774         if (data->check_async && async_allowed != data->want_async)
 775                 return 0;
 776
 777         return driver_probe_device(drv, dev);
 778 }
 779
 780 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 781 {
 782         struct device *dev = _dev;
 783         struct device_attach_data data = {
 784                 .dev            = dev,
 785                 .check_async    = true,
 786                 .want_async     = true,
 787         };
 788
 789         device_lock(dev);
 790
 791         /*
 792          * Check if device has already been removed or claimed. This may
 793          * happen with driver loading, device discovery/registration,
 794          * and deferred probe processing happens all at once with
 795          * multiple threads.
 796          */
 797         if (dev->p->dead || dev->driver)
 798                 goto out_unlock;
 799
 800         if (dev->parent)
 801                 pm_runtime_get_sync(dev->parent);
 802
 803         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 804         dev_dbg(dev, "async probe completed\n");
 805
 806         pm_request_idle(dev);
 807
 808         if (dev->parent)
 809                 pm_runtime_put(dev->parent);
 810 out_unlock:
 811         device_unlock(dev);
 812
 813         put_device(dev);
 814 }
 815
 816 static int __device_attach(struct device *dev, bool allow_async)
 817 {
 818         int ret = 0;
 819
 820         device_lock(dev);
 821         if (dev->driver) {
 822                 if (device_is_bound(dev)) {
 823                         ret = 1;
 824                         goto out_unlock;
 825                 }
 826                 ret = device_bind_driver(dev);
 827                 if (ret == 0)
 828                         ret = 1;
 829                 else {
 830                         dev->driver = NULL;
 831                         ret = 0;
 832                 }
 833         } else {
 834                 struct device_attach_data data = {
 835                         .dev = dev,
 836                         .check_async = allow_async,
 837                         .want_async = false,
 838                 };
 839
 840                 if (dev->parent)
 841                         pm_runtime_get_sync(dev->parent);
 842
 843                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 844                                         __device_attach_driver);
 845                 if (!ret && allow_async && data.have_async) {
 846                         /*
 847                          * If we could not find appropriate driver
 848                          * synchronously and we are allowed to do
 849                          * async probes and there are drivers that
 850                          * want to probe asynchronously, we'll
 851                          * try them.
 852                          */
 853                         dev_dbg(dev, "scheduling asynchronous probe\n");
 854                         get_device(dev);
 855                         async_schedule_dev(__device_attach_async_helper, dev);
 856                 } else {
 857                         pm_request_idle(dev);
 858                 }
 859
 860                 if (dev->parent)
 861                         pm_runtime_put(dev->parent);
 862         }
 863 out_unlock:
 864         device_unlock(dev);
 865         return ret;
 866 }
 867
 868 /**
 869  * device_attach - try to attach device to a driver.
 870  * @dev: device.
 871  *
 872  * Walk the list of drivers that the bus has and call
 873  * driver_probe_device() for each pair. If a compatible
 874  * pair is found, break out and return.
 875  *
 876  * Returns 1 if the device was bound to a driver;
 877  * 0 if no matching driver was found;
 878  * -ENODEV if the device is not registered.
 879  *
 880  * When called for a USB interface, @dev->parent lock must be held.
 881  */
 882 int device_attach(struct device *dev)
 883 {
 884         return __device_attach(dev, false);
 885 }
 886 EXPORT_SYMBOL_GPL(device_attach);
 887
 888 void device_initial_probe(struct device *dev)
 889 {
 890         __device_attach(dev, true);
 891 }
 892
 893 /*
 894  * __device_driver_lock - acquire locks needed to manipulate dev->drv
 895  * @dev: Device we will update driver info for
 896  * @parent: Parent device. Needed if the bus requires parent lock
 897  *
 898  * This function will take the required locks for manipulating dev->drv.
 899  * Normally this will just be the @dev lock, but when called for a USB
 900  * interface, @parent lock will be held as well.
 901  */
 902 static void __device_driver_lock(struct device *dev, struct device *parent)
 903 {
 904         if (parent && dev->bus->need_parent_lock)
 905                 device_lock(parent);
 906         device_lock(dev);
 907 }
 908
 909 /*
 910  * __device_driver_unlock - release locks needed to manipulate dev->drv
 911  * @dev: Device we will update driver info for
 912  * @parent: Parent device. Needed if the bus requires parent lock
 913  *
 914  * This function will release the required locks for manipulating dev->drv.
 915  * Normally this will just be the the @dev lock, but when called for a
 916  * USB interface, @parent lock will be released as well.
 917  */
 918 static void __device_driver_unlock(struct device *dev, struct device *parent)
 919 {
 920         device_unlock(dev);
 921         if (parent && dev->bus->need_parent_lock)
 922                 device_unlock(parent);
 923 }
 924
 925 /**
 926  * device_driver_attach - attach a specific driver to a specific device
 927  * @drv: Driver to attach
 928  * @dev: Device to attach it to
 929  *
 930  * Manually attach driver to a device. Will acquire both @dev lock and
 931  * @dev->parent lock if needed.
 932  */
 933 int device_driver_attach(struct device_driver *drv, struct device *dev)
 934 {
 935         int ret = 0;
 936
 937         __device_driver_lock(dev, dev->parent);
 938
 939         /*
 940          * If device has been removed or someone has already successfully
 941          * bound a driver before us just skip the driver probe call.
 942          */
 943         if (!dev->p->dead && !dev->driver)
 944                 ret = driver_probe_device(drv, dev);
 945
 946         __device_driver_unlock(dev, dev->parent);
 947
 948         return ret;
 949 }
 950
 951 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
 952 {
 953         struct device *dev = _dev;
 954         struct device_driver *drv;
 955         int ret = 0;
 956
 957         __device_driver_lock(dev, dev->parent);
 958
 959         drv = dev->p->async_driver;
 960
 961         /*
 962          * If device has been removed or someone has already successfully
 963          * bound a driver before us just skip the driver probe call.
 964          */
 965         if (!dev->p->dead && !dev->driver)
 966                 ret = driver_probe_device(drv, dev);
 967
 968         __device_driver_unlock(dev, dev->parent);
 969
 970         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
 971
 972         put_device(dev);
 973 }
 974
 975 static int __driver_attach(struct device *dev, void *data)
 976 {
 977         struct device_driver *drv = data;
 978         int ret;
 979
 980         /*
 981          * Lock device and try to bind to it. We drop the error
 982          * here and always return 0, because we need to keep trying
 983          * to bind to devices and some drivers will return an error
 984          * simply if it didn't support the device.
 985          *
 986          * driver_probe_device() will spit a warning if there
 987          * is an error.
 988          */
 989
 990         ret = driver_match_device(drv, dev);
 991         if (ret == 0) {
 992                 /* no match */
 993                 return 0;
 994         } else if (ret == -EPROBE_DEFER) {
 995                 dev_dbg(dev, "Device match requests probe deferral\n");
 996                 driver_deferred_probe_add(dev);
 997         } else if (ret < 0) {
 998                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 999                 return ret;
1000         } /* ret > 0 means positive match */
1001
1002         if (driver_allows_async_probing(drv)) {
1003                 /*
1004                  * Instead of probing the device synchronously we will
1005                  * probe it asynchronously to allow for more parallelism.
1006                  *
1007                  * We only take the device lock here in order to guarantee
1008                  * that the dev->driver and async_driver fields are protected
1009                  */
1010                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1011                 device_lock(dev);
1012                 if (!dev->driver) {
1013                         get_device(dev);
1014                         dev->p->async_driver = drv;
1015                         async_schedule_dev(__driver_attach_async_helper, dev);
1016                 }
1017                 device_unlock(dev);
1018                 return 0;
1019         }
1020
1021         device_driver_attach(drv, dev);
1022
1023         return 0;
1024 }
1025
1026 /**
1027  * driver_attach - try to bind driver to devices.
1028  * @drv: driver.
1029  *
1030  * Walk the list of devices that the bus has on it and try to
1031  * match the driver with each one.  If driver_probe_device()
1032  * returns 0 and the @dev->driver is set, we've found a
1033  * compatible pair.
1034  */
1035 int driver_attach(struct device_driver *drv)
1036 {
1037         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1038 }
1039 EXPORT_SYMBOL_GPL(driver_attach);
1040
1041 /*
1042  * __device_release_driver() must be called with @dev lock held.
1043  * When called for a USB interface, @dev->parent lock must be held as well.
1044  */
1045 static void __device_release_driver(struct device *dev, struct device *parent)
1046 {
1047         struct device_driver *drv;
1048
1049         drv = dev->driver;
1050         if (drv) {
1051                 while (device_links_busy(dev)) {
1052                         __device_driver_unlock(dev, parent);
1053
1054                         device_links_unbind_consumers(dev);
1055
1056                         __device_driver_lock(dev, parent);
1057                         /*
1058                          * A concurrent invocation of the same function might
1059                          * have released the driver successfully while this one
1060                          * was waiting, so check for that.
1061                          */
1062                         if (dev->driver != drv)
1063                                 return;
1064                 }
1065
1066                 pm_runtime_get_sync(dev);
1067                 pm_runtime_clean_up_links(dev);
1068
1069                 driver_sysfs_remove(dev);
1070
1071                 if (dev->bus)
1072                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1073                                                      BUS_NOTIFY_UNBIND_DRIVER,
1074                                                      dev);
1075
1076                 pm_runtime_put_sync(dev);
1077
1078                 if (dev->bus && dev->bus->remove)
1079                         dev->bus->remove(dev);
1080                 else if (drv->remove)
1081                         drv->remove(dev);
1082
1083                 device_links_driver_cleanup(dev);
1084
1085                 devres_release_all(dev);
1086                 arch_teardown_dma_ops(dev);
1087                 dev->driver = NULL;
1088                 dev_set_drvdata(dev, NULL);
1089                 if (dev->pm_domain && dev->pm_domain->dismiss)
1090                         dev->pm_domain->dismiss(dev);
1091                 pm_runtime_reinit(dev);
1092                 dev_pm_set_driver_flags(dev, 0);
1093
1094                 klist_remove(&dev->p->knode_driver);
1095                 device_pm_check_callbacks(dev);
1096                 if (dev->bus)
1097                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1098                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1099                                                      dev);
1100
1101                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1102         }
1103 }
1104
1105 void device_release_driver_internal(struct device *dev,
1106                                     struct device_driver *drv,
1107                                     struct device *parent)
1108 {
1109         __device_driver_lock(dev, parent);
1110
1111         if (!drv || drv == dev->driver)
1112                 __device_release_driver(dev, parent);
1113
1114         __device_driver_unlock(dev, parent);
1115 }
1116
1117 /**
1118  * device_release_driver - manually detach device from driver.
1119  * @dev: device.
1120  *
1121  * Manually detach device from driver.
1122  * When called for a USB interface, @dev->parent lock must be held.
1123  *
1124  * If this function is to be called with @dev->parent lock held, ensure that
1125  * the device's consumers are unbound in advance or that their locks can be
1126  * acquired under the @dev->parent lock.
1127  */
1128 void device_release_driver(struct device *dev)
1129 {
1130         /*
1131          * If anyone calls device_release_driver() recursively from
1132          * within their ->remove callback for the same device, they
1133          * will deadlock right here.
1134          */
1135         device_release_driver_internal(dev, NULL, NULL);
1136 }
1137 EXPORT_SYMBOL_GPL(device_release_driver);
1138
1139 /**
1140  * device_driver_detach - detach driver from a specific device
1141  * @dev: device to detach driver from
1142  *
1143  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1144  * lock if needed.
1145  */
1146 void device_driver_detach(struct device *dev)
1147 {
1148         device_release_driver_internal(dev, NULL, dev->parent);
1149 }
1150
1151 /**
1152  * driver_detach - detach driver from all devices it controls.
1153  * @drv: driver.
1154  */
1155 void driver_detach(struct device_driver *drv)
1156 {
1157         struct device_private *dev_prv;
1158         struct device *dev;
1159
1160         if (driver_allows_async_probing(drv))
1161                 async_synchronize_full();
1162
1163         for (;;) {
1164                 spin_lock(&drv->p->klist_devices.k_lock);
1165                 if (list_empty(&drv->p->klist_devices.k_list)) {
1166                         spin_unlock(&drv->p->klist_devices.k_lock);
1167                         break;
1168                 }
1169                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
1170                                      struct device_private,
1171                                      knode_driver.n_node);
1172                 dev = dev_prv->device;
1173                 get_device(dev);
1174                 spin_unlock(&drv->p->klist_devices.k_lock);
1175                 device_release_driver_internal(dev, drv, dev->parent);
1176                 put_device(dev);
1177         }
1178 }