drivers/base/dd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * drivers/base/dd.c - The core device/driver interactions.
   4  *
   5  * This file contains the (sometimes tricky) code that controls the
   6  * interactions between devices and drivers, which primarily includes
   7  * driver binding and unbinding.
   8  *
   9  * All of this code used to exist in drivers/base/bus.c, but was
  10  * relocated to here in the name of compartmentalization (since it wasn't
  11  * strictly code just for the 'struct bus_type'.
  12  *
  13  * Copyright (c) 2002-5 Patrick Mochel
  14  * Copyright (c) 2002-3 Open Source Development Labs
  15  * Copyright (c) 2007-2009 Greg Kroah-Hartman <[email protected]>
  16  * Copyright (c) 2007-2009 Novell Inc.
  17  */
  18
  19 #include <linux/debugfs.h>
  20 #include <linux/device.h>
  21 #include <linux/delay.h>
  22 #include <linux/dma-map-ops.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 #include <linux/slab.h>
  31
  32 #include "base.h"
  33 #include "power/power.h"
  34
  35 /*
  36  * Deferred Probe infrastructure.
  37  *
  38  * Sometimes driver probe order matters, but the kernel doesn't always have
  39  * dependency information which means some drivers will get probed before a
  40  * resource it depends on is available.  For example, an SDHCI driver may
  41  * first need a GPIO line from an i2c GPIO controller before it can be
  42  * initialized.  If a required resource is not available yet, a driver can
  43  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  44  *
  45  * Deferred probe maintains two lists of devices, a pending list and an active
  46  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  47  * pending list.  A successful driver probe will trigger moving all devices
  48  * from the pending to the active list so that the workqueue will eventually
  49  * retry them.
  50  *
  51  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  52  * of the (struct device*)->p->deferred_probe pointers are manipulated
  53  */
  54 static DEFINE_MUTEX(deferred_probe_mutex);
  55 static LIST_HEAD(deferred_probe_pending_list);
  56 static LIST_HEAD(deferred_probe_active_list);
  57 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
  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 static bool async_probe_default;
  64
  65 /*
  66  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  67  * to prohibit probing of devices as it could be unsafe.
  68  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  69  */
  70 static bool defer_all_probes;
  71
  72 static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
  73 {
  74         kfree(dev->p->deferred_probe_reason);
  75         dev->p->deferred_probe_reason = reason;
  76 }
  77
  78 /*
  79  * deferred_probe_work_func() - Retry probing devices in the active list.
  80  */
  81 static void deferred_probe_work_func(struct work_struct *work)
  82 {
  83         struct device *dev;
  84         struct device_private *private;
  85         /*
  86          * This block processes every device in the deferred 'active' list.
  87          * Each device is removed from the active list and passed to
  88          * bus_probe_device() to re-attempt the probe.  The loop continues
  89          * until every device in the active list is removed and retried.
  90          *
  91          * Note: Once the device is removed from the list and the mutex is
  92          * released, it is possible for the device get freed by another thread
  93          * and cause a illegal pointer dereference.  This code uses
  94          * get/put_device() to ensure the device structure cannot disappear
  95          * from under our feet.
  96          */
  97         mutex_lock(&deferred_probe_mutex);
  98         while (!list_empty(&deferred_probe_active_list)) {
  99                 private = list_first_entry(&deferred_probe_active_list,
 100                                         typeof(*dev->p), deferred_probe);
 101                 dev = private->device;
 102                 list_del_init(&private->deferred_probe);
 103
 104                 get_device(dev);
 105
 106                 __device_set_deferred_probe_reason(dev, NULL);
 107
 108                 /*
 109                  * Drop the mutex while probing each device; the probe path may
 110                  * manipulate the deferred list
 111                  */
 112                 mutex_unlock(&deferred_probe_mutex);
 113
 114                 /*
 115                  * Force the device to the end of the dpm_list since
 116                  * the PM code assumes that the order we add things to
 117                  * the list is a good order for suspend but deferred
 118                  * probe makes that very unsafe.
 119                  */
 120                 device_pm_move_to_tail(dev);
 121
 122                 dev_dbg(dev, "Retrying from deferred list\n");
 123                 bus_probe_device(dev);
 124                 mutex_lock(&deferred_probe_mutex);
 125
 126                 put_device(dev);
 127         }
 128         mutex_unlock(&deferred_probe_mutex);
 129 }
 130 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 131
 132 void driver_deferred_probe_add(struct device *dev)
 133 {
 134         if (!dev->can_match)
 135                 return;
 136
 137         mutex_lock(&deferred_probe_mutex);
 138         if (list_empty(&dev->p->deferred_probe)) {
 139                 dev_dbg(dev, "Added to deferred list\n");
 140                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 141         }
 142         mutex_unlock(&deferred_probe_mutex);
 143 }
 144
 145 void driver_deferred_probe_del(struct device *dev)
 146 {
 147         mutex_lock(&deferred_probe_mutex);
 148         if (!list_empty(&dev->p->deferred_probe)) {
 149                 dev_dbg(dev, "Removed from deferred list\n");
 150                 list_del_init(&dev->p->deferred_probe);
 151                 __device_set_deferred_probe_reason(dev, NULL);
 152         }
 153         mutex_unlock(&deferred_probe_mutex);
 154 }
 155
 156 static bool driver_deferred_probe_enable;
 157 /**
 158  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 159  *
 160  * This functions moves all devices from the pending list to the active
 161  * list and schedules the deferred probe workqueue to process them.  It
 162  * should be called anytime a driver is successfully bound to a device.
 163  *
 164  * Note, there is a race condition in multi-threaded probe. In the case where
 165  * more than one device is probing at the same time, it is possible for one
 166  * probe to complete successfully while another is about to defer. If the second
 167  * depends on the first, then it will get put on the pending list after the
 168  * trigger event has already occurred and will be stuck there.
 169  *
 170  * The atomic 'deferred_trigger_count' is used to determine if a successful
 171  * trigger has occurred in the midst of probing a driver. If the trigger count
 172  * changes in the midst of a probe, then deferred processing should be triggered
 173  * again.
 174  */
 175 void driver_deferred_probe_trigger(void)
 176 {
 177         if (!driver_deferred_probe_enable)
 178                 return;
 179
 180         /*
 181          * A successful probe means that all the devices in the pending list
 182          * should be triggered to be reprobed.  Move all the deferred devices
 183          * into the active list so they can be retried by the workqueue
 184          */
 185         mutex_lock(&deferred_probe_mutex);
 186         atomic_inc(&deferred_trigger_count);
 187         list_splice_tail_init(&deferred_probe_pending_list,
 188                               &deferred_probe_active_list);
 189         mutex_unlock(&deferred_probe_mutex);
 190
 191         /*
 192          * Kick the re-probe thread.  It may already be scheduled, but it is
 193          * safe to kick it again.
 194          */
 195         queue_work(system_unbound_wq, &deferred_probe_work);
 196 }
 197
 198 /**
 199  * device_block_probing() - Block/defer device's probes
 200  *
 201  *      It will disable probing of devices and defer their probes instead.
 202  */
 203 void device_block_probing(void)
 204 {
 205         defer_all_probes = true;
 206         /* sync with probes to avoid races. */
 207         wait_for_device_probe();
 208 }
 209
 210 /**
 211  * device_unblock_probing() - Unblock/enable device's probes
 212  *
 213  *      It will restore normal behavior and trigger re-probing of deferred
 214  * devices.
 215  */
 216 void device_unblock_probing(void)
 217 {
 218         defer_all_probes = false;
 219         driver_deferred_probe_trigger();
 220 }
 221
 222 /**
 223  * device_set_deferred_probe_reason() - Set defer probe reason message for device
 224  * @dev: the pointer to the struct device
 225  * @vaf: the pointer to va_format structure with message
 226  */
 227 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
 228 {
 229         const char *drv = dev_driver_string(dev);
 230         char *reason;
 231
 232         mutex_lock(&deferred_probe_mutex);
 233
 234         reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
 235         __device_set_deferred_probe_reason(dev, reason);
 236
 237         mutex_unlock(&deferred_probe_mutex);
 238 }
 239
 240 /*
 241  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 242  */
 243 static int deferred_devs_show(struct seq_file *s, void *data)
 244 {
 245         struct device_private *curr;
 246
 247         mutex_lock(&deferred_probe_mutex);
 248
 249         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 250                 seq_printf(s, "%s\t%s", dev_name(curr->device),
 251                            curr->device->p->deferred_probe_reason ?: "\n");
 252
 253         mutex_unlock(&deferred_probe_mutex);
 254
 255         return 0;
 256 }
 257 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 258
 259 #ifdef CONFIG_MODULES
 260 static int driver_deferred_probe_timeout = 10;
 261 #else
 262 static int driver_deferred_probe_timeout;
 263 #endif
 264
 265 static int __init deferred_probe_timeout_setup(char *str)
 266 {
 267         int timeout;
 268
 269         if (!kstrtoint(str, 10, &timeout))
 270                 driver_deferred_probe_timeout = timeout;
 271         return 1;
 272 }
 273 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 274
 275 /**
 276  * driver_deferred_probe_check_state() - Check deferred probe state
 277  * @dev: device to check
 278  *
 279  * Return:
 280  * * -ENODEV if initcalls have completed and modules are disabled.
 281  * * -ETIMEDOUT if the deferred probe timeout was set and has expired
 282  *   and modules are enabled.
 283  * * -EPROBE_DEFER in other cases.
 284  *
 285  * Drivers or subsystems can opt-in to calling this function instead of directly
 286  * returning -EPROBE_DEFER.
 287  */
 288 int driver_deferred_probe_check_state(struct device *dev)
 289 {
 290         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 291                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 292                 return -ENODEV;
 293         }
 294
 295         if (!driver_deferred_probe_timeout && initcalls_done) {
 296                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 297                 return -ETIMEDOUT;
 298         }
 299
 300         return -EPROBE_DEFER;
 301 }
 302 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
 303
 304 static void deferred_probe_timeout_work_func(struct work_struct *work)
 305 {
 306         struct device_private *p;
 307
 308         fw_devlink_drivers_done();
 309
 310         driver_deferred_probe_timeout = 0;
 311         driver_deferred_probe_trigger();
 312         flush_work(&deferred_probe_work);
 313
 314         mutex_lock(&deferred_probe_mutex);
 315         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 316                 dev_warn(p->device, "deferred probe pending: %s", p->deferred_probe_reason ?: "(reason unknown)\n");
 317         mutex_unlock(&deferred_probe_mutex);
 318
 319         fw_devlink_probing_done();
 320 }
 321 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 322
 323 void deferred_probe_extend_timeout(void)
 324 {
 325         /*
 326          * If the work hasn't been queued yet or if the work expired, don't
 327          * start a new one.
 328          */
 329         if (cancel_delayed_work(&deferred_probe_timeout_work)) {
 330                 schedule_delayed_work(&deferred_probe_timeout_work,
 331                                 driver_deferred_probe_timeout * HZ);
 332                 pr_debug("Extended deferred probe timeout by %d secs\n",
 333                                         driver_deferred_probe_timeout);
 334         }
 335 }
 336
 337 /**
 338  * deferred_probe_initcall() - Enable probing of deferred devices
 339  *
 340  * We don't want to get in the way when the bulk of drivers are getting probed.
 341  * Instead, this initcall makes sure that deferred probing is delayed until
 342  * late_initcall time.
 343  */
 344 static int deferred_probe_initcall(void)
 345 {
 346         debugfs_create_file("devices_deferred", 0444, NULL, NULL,
 347                             &deferred_devs_fops);
 348
 349         driver_deferred_probe_enable = true;
 350         driver_deferred_probe_trigger();
 351         /* Sort as many dependencies as possible before exiting initcalls */
 352         flush_work(&deferred_probe_work);
 353         initcalls_done = true;
 354
 355         if (!IS_ENABLED(CONFIG_MODULES))
 356                 fw_devlink_drivers_done();
 357
 358         /*
 359          * Trigger deferred probe again, this time we won't defer anything
 360          * that is optional
 361          */
 362         driver_deferred_probe_trigger();
 363         flush_work(&deferred_probe_work);
 364
 365         if (driver_deferred_probe_timeout > 0) {
 366                 schedule_delayed_work(&deferred_probe_timeout_work,
 367                         driver_deferred_probe_timeout * HZ);
 368         }
 369
 370         if (!IS_ENABLED(CONFIG_MODULES))
 371                 fw_devlink_probing_done();
 372
 373         return 0;
 374 }
 375 late_initcall(deferred_probe_initcall);
 376
 377 static void __exit deferred_probe_exit(void)
 378 {
 379         debugfs_lookup_and_remove("devices_deferred", NULL);
 380 }
 381 __exitcall(deferred_probe_exit);
 382
 383 /**
 384  * device_is_bound() - Check if device is bound to a driver
 385  * @dev: device to check
 386  *
 387  * Returns true if passed device has already finished probing successfully
 388  * against a driver.
 389  *
 390  * This function must be called with the device lock held.
 391  */
 392 bool device_is_bound(struct device *dev)
 393 {
 394         return dev->p && klist_node_attached(&dev->p->knode_driver);
 395 }
 396
 397 static void driver_bound(struct device *dev)
 398 {
 399         if (device_is_bound(dev)) {
 400                 dev_warn(dev, "%s: device already bound\n", __func__);
 401                 return;
 402         }
 403
 404         dev_dbg(dev, "driver: '%s': %s: bound to device\n", dev->driver->name,
 405                 __func__);
 406
 407         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 408         device_links_driver_bound(dev);
 409
 410         device_pm_check_callbacks(dev);
 411
 412         /*
 413          * Make sure the device is no longer in one of the deferred lists and
 414          * kick off retrying all pending devices
 415          */
 416         driver_deferred_probe_del(dev);
 417         driver_deferred_probe_trigger();
 418
 419         bus_notify(dev, BUS_NOTIFY_BOUND_DRIVER);
 420         kobject_uevent(&dev->kobj, KOBJ_BIND);
 421 }
 422
 423 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 424                             const char *buf, size_t count)
 425 {
 426         device_lock(dev);
 427         dev->driver->coredump(dev);
 428         device_unlock(dev);
 429
 430         return count;
 431 }
 432 static DEVICE_ATTR_WO(coredump);
 433
 434 static int driver_sysfs_add(struct device *dev)
 435 {
 436         int ret;
 437
 438         bus_notify(dev, BUS_NOTIFY_BIND_DRIVER);
 439
 440         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 441                                 kobject_name(&dev->kobj));
 442         if (ret)
 443                 goto fail;
 444
 445         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 446                                 "driver");
 447         if (ret)
 448                 goto rm_dev;
 449
 450         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 451                 return 0;
 452
 453         ret = device_create_file(dev, &dev_attr_coredump);
 454         if (!ret)
 455                 return 0;
 456
 457         sysfs_remove_link(&dev->kobj, "driver");
 458
 459 rm_dev:
 460         sysfs_remove_link(&dev->driver->p->kobj,
 461                           kobject_name(&dev->kobj));
 462
 463 fail:
 464         return ret;
 465 }
 466
 467 static void driver_sysfs_remove(struct device *dev)
 468 {
 469         struct device_driver *drv = dev->driver;
 470
 471         if (drv) {
 472                 if (drv->coredump)
 473                         device_remove_file(dev, &dev_attr_coredump);
 474                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 475                 sysfs_remove_link(&dev->kobj, "driver");
 476         }
 477 }
 478
 479 /**
 480  * device_bind_driver - bind a driver to one device.
 481  * @dev: device.
 482  *
 483  * Allow manual attachment of a driver to a device.
 484  * Caller must have already set @dev->driver.
 485  *
 486  * Note that this does not modify the bus reference count.
 487  * Please verify that is accounted for before calling this.
 488  * (It is ok to call with no other effort from a driver's probe() method.)
 489  *
 490  * This function must be called with the device lock held.
 491  *
 492  * Callers should prefer to use device_driver_attach() instead.
 493  */
 494 int device_bind_driver(struct device *dev)
 495 {
 496         int ret;
 497
 498         ret = driver_sysfs_add(dev);
 499         if (!ret) {
 500                 device_links_force_bind(dev);
 501                 driver_bound(dev);
 502         }
 503         else
 504                 bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
 505         return ret;
 506 }
 507 EXPORT_SYMBOL_GPL(device_bind_driver);
 508
 509 static atomic_t probe_count = ATOMIC_INIT(0);
 510 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 511
 512 static ssize_t state_synced_store(struct device *dev,
 513                                   struct device_attribute *attr,
 514                                   const char *buf, size_t count)
 515 {
 516         int ret = 0;
 517
 518         if (strcmp("1", buf))
 519                 return -EINVAL;
 520
 521         device_lock(dev);
 522         if (!dev->state_synced) {
 523                 dev->state_synced = true;
 524                 dev_sync_state(dev);
 525         } else {
 526                 ret = -EINVAL;
 527         }
 528         device_unlock(dev);
 529
 530         return ret ? ret : count;
 531 }
 532
 533 static ssize_t state_synced_show(struct device *dev,
 534                                  struct device_attribute *attr, char *buf)
 535 {
 536         bool val;
 537
 538         device_lock(dev);
 539         val = dev->state_synced;
 540         device_unlock(dev);
 541
 542         return sysfs_emit(buf, "%u\n", val);
 543 }
 544 static DEVICE_ATTR_RW(state_synced);
 545
 546 static void device_unbind_cleanup(struct device *dev)
 547 {
 548         devres_release_all(dev);
 549         arch_teardown_dma_ops(dev);
 550         kfree(dev->dma_range_map);
 551         dev->dma_range_map = NULL;
 552         dev->driver = NULL;
 553         dev_set_drvdata(dev, NULL);
 554         if (dev->pm_domain && dev->pm_domain->dismiss)
 555                 dev->pm_domain->dismiss(dev);
 556         pm_runtime_reinit(dev);
 557         dev_pm_set_driver_flags(dev, 0);
 558 }
 559
 560 static void device_remove(struct device *dev)
 561 {
 562         device_remove_file(dev, &dev_attr_state_synced);
 563         device_remove_groups(dev, dev->driver->dev_groups);
 564
 565         if (dev->bus && dev->bus->remove)
 566                 dev->bus->remove(dev);
 567         else if (dev->driver->remove)
 568                 dev->driver->remove(dev);
 569 }
 570
 571 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 572 {
 573         int ret = 0;
 574
 575         if (dev->bus->probe)
 576                 ret = dev->bus->probe(dev);
 577         else if (drv->probe)
 578                 ret = drv->probe(dev);
 579
 580         switch (ret) {
 581         case 0:
 582                 break;
 583         case -EPROBE_DEFER:
 584                 /* Driver requested deferred probing */
 585                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 586                 break;
 587         case -ENODEV:
 588         case -ENXIO:
 589                 dev_dbg(dev, "probe with driver %s rejects match %d\n",
 590                         drv->name, ret);
 591                 break;
 592         default:
 593                 /* driver matched but the probe failed */
 594                 dev_err(dev, "probe with driver %s failed with error %d\n",
 595                         drv->name, ret);
 596                 break;
 597         }
 598
 599         return ret;
 600 }
 601
 602 static int really_probe(struct device *dev, struct device_driver *drv)
 603 {
 604         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 605                            !drv->suppress_bind_attrs;
 606         int ret, link_ret;
 607
 608         if (defer_all_probes) {
 609                 /*
 610                  * Value of defer_all_probes can be set only by
 611                  * device_block_probing() which, in turn, will call
 612                  * wait_for_device_probe() right after that to avoid any races.
 613                  */
 614                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 615                 return -EPROBE_DEFER;
 616         }
 617
 618         link_ret = device_links_check_suppliers(dev);
 619         if (link_ret == -EPROBE_DEFER)
 620                 return link_ret;
 621
 622         dev_dbg(dev, "bus: '%s': %s: probing driver %s with device\n",
 623                 drv->bus->name, __func__, drv->name);
 624         if (!list_empty(&dev->devres_head)) {
 625                 dev_crit(dev, "Resources present before probing\n");
 626                 ret = -EBUSY;
 627                 goto done;
 628         }
 629
 630 re_probe:
 631         dev->driver = drv;
 632
 633         /* If using pinctrl, bind pins now before probing */
 634         ret = pinctrl_bind_pins(dev);
 635         if (ret)
 636                 goto pinctrl_bind_failed;
 637
 638         if (dev->bus->dma_configure) {
 639                 ret = dev->bus->dma_configure(dev);
 640                 if (ret)
 641                         goto pinctrl_bind_failed;
 642         }
 643
 644         ret = driver_sysfs_add(dev);
 645         if (ret) {
 646                 dev_err(dev, "%s: driver_sysfs_add failed\n", __func__);
 647                 goto sysfs_failed;
 648         }
 649
 650         if (dev->pm_domain && dev->pm_domain->activate) {
 651                 ret = dev->pm_domain->activate(dev);
 652                 if (ret)
 653                         goto probe_failed;
 654         }
 655
 656         ret = call_driver_probe(dev, drv);
 657         if (ret) {
 658                 /*
 659                  * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
 660                  * device might actually probe properly once some of its missing
 661                  * suppliers have probed. So, treat this as if the driver
 662                  * returned -EPROBE_DEFER.
 663                  */
 664                 if (link_ret == -EAGAIN)
 665                         ret = -EPROBE_DEFER;
 666
 667                 /*
 668                  * Return probe errors as positive values so that the callers
 669                  * can distinguish them from other errors.
 670                  */
 671                 ret = -ret;
 672                 goto probe_failed;
 673         }
 674
 675         ret = device_add_groups(dev, drv->dev_groups);
 676         if (ret) {
 677                 dev_err(dev, "device_add_groups() failed\n");
 678                 goto dev_groups_failed;
 679         }
 680
 681         if (dev_has_sync_state(dev)) {
 682                 ret = device_create_file(dev, &dev_attr_state_synced);
 683                 if (ret) {
 684                         dev_err(dev, "state_synced sysfs add failed\n");
 685                         goto dev_sysfs_state_synced_failed;
 686                 }
 687         }
 688
 689         if (test_remove) {
 690                 test_remove = false;
 691
 692                 device_remove(dev);
 693                 driver_sysfs_remove(dev);
 694                 if (dev->bus && dev->bus->dma_cleanup)
 695                         dev->bus->dma_cleanup(dev);
 696                 device_unbind_cleanup(dev);
 697
 698                 goto re_probe;
 699         }
 700
 701         pinctrl_init_done(dev);
 702
 703         if (dev->pm_domain && dev->pm_domain->sync)
 704                 dev->pm_domain->sync(dev);
 705
 706         driver_bound(dev);
 707         dev_dbg(dev, "bus: '%s': %s: bound device to driver %s\n",
 708                 drv->bus->name, __func__, drv->name);
 709         goto done;
 710
 711 dev_sysfs_state_synced_failed:
 712 dev_groups_failed:
 713         device_remove(dev);
 714 probe_failed:
 715         driver_sysfs_remove(dev);
 716 sysfs_failed:
 717         bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
 718         if (dev->bus && dev->bus->dma_cleanup)
 719                 dev->bus->dma_cleanup(dev);
 720 pinctrl_bind_failed:
 721         device_links_no_driver(dev);
 722         device_unbind_cleanup(dev);
 723 done:
 724         return ret;
 725 }
 726
 727 /*
 728  * For initcall_debug, show the driver probe time.
 729  */
 730 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 731 {
 732         ktime_t calltime, rettime;
 733         int ret;
 734
 735         calltime = ktime_get();
 736         ret = really_probe(dev, drv);
 737         rettime = ktime_get();
 738         /*
 739          * Don't change this to pr_debug() because that requires
 740          * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the
 741          * kernel commandline to print this all the time at the debug level.
 742          */
 743         printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
 744                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 745         return ret;
 746 }
 747
 748 /**
 749  * driver_probe_done
 750  * Determine if the probe sequence is finished or not.
 751  *
 752  * Should somehow figure out how to use a semaphore, not an atomic variable...
 753  */
 754 bool __init driver_probe_done(void)
 755 {
 756         int local_probe_count = atomic_read(&probe_count);
 757
 758         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 759         return !local_probe_count;
 760 }
 761
 762 /**
 763  * wait_for_device_probe
 764  * Wait for device probing to be completed.
 765  */
 766 void wait_for_device_probe(void)
 767 {
 768         /* wait for the deferred probe workqueue to finish */
 769         flush_work(&deferred_probe_work);
 770
 771         /* wait for the known devices to complete their probing */
 772         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 773         async_synchronize_full();
 774 }
 775 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 776
 777 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 778 {
 779         int ret = 0;
 780
 781         if (dev->p->dead || !device_is_registered(dev))
 782                 return -ENODEV;
 783         if (dev->driver)
 784                 return -EBUSY;
 785
 786         dev->can_match = true;
 787         dev_dbg(dev, "bus: '%s': %s: matched device with driver %s\n",
 788                 drv->bus->name, __func__, drv->name);
 789
 790         pm_runtime_get_suppliers(dev);
 791         if (dev->parent)
 792                 pm_runtime_get_sync(dev->parent);
 793
 794         pm_runtime_barrier(dev);
 795         if (initcall_debug)
 796                 ret = really_probe_debug(dev, drv);
 797         else
 798                 ret = really_probe(dev, drv);
 799         pm_request_idle(dev);
 800
 801         if (dev->parent)
 802                 pm_runtime_put(dev->parent);
 803
 804         pm_runtime_put_suppliers(dev);
 805         return ret;
 806 }
 807
 808 /**
 809  * driver_probe_device - attempt to bind device & driver together
 810  * @drv: driver to bind a device to
 811  * @dev: device to try to bind to the driver
 812  *
 813  * This function returns -ENODEV if the device is not registered, -EBUSY if it
 814  * already has a driver, 0 if the device is bound successfully and a positive
 815  * (inverted) error code for failures from the ->probe method.
 816  *
 817  * This function must be called with @dev lock held.  When called for a
 818  * USB interface, @dev->parent lock must be held as well.
 819  *
 820  * If the device has a parent, runtime-resume the parent before driver probing.
 821  */
 822 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 823 {
 824         int trigger_count = atomic_read(&deferred_trigger_count);
 825         int ret;
 826
 827         atomic_inc(&probe_count);
 828         ret = __driver_probe_device(drv, dev);
 829         if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
 830                 driver_deferred_probe_add(dev);
 831
 832                 /*
 833                  * Did a trigger occur while probing? Need to re-trigger if yes
 834                  */
 835                 if (trigger_count != atomic_read(&deferred_trigger_count) &&
 836                     !defer_all_probes)
 837                         driver_deferred_probe_trigger();
 838         }
 839         atomic_dec(&probe_count);
 840         wake_up_all(&probe_waitqueue);
 841         return ret;
 842 }
 843
 844 static inline bool cmdline_requested_async_probing(const char *drv_name)
 845 {
 846         bool async_drv;
 847
 848         async_drv = parse_option_str(async_probe_drv_names, drv_name);
 849
 850         return (async_probe_default != async_drv);
 851 }
 852
 853 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 854 static int __init save_async_options(char *buf)
 855 {
 856         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 857                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 858
 859         strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 860         async_probe_default = parse_option_str(async_probe_drv_names, "*");
 861
 862         return 1;
 863 }
 864 __setup("driver_async_probe=", save_async_options);
 865
 866 static bool driver_allows_async_probing(struct device_driver *drv)
 867 {
 868         switch (drv->probe_type) {
 869         case PROBE_PREFER_ASYNCHRONOUS:
 870                 return true;
 871
 872         case PROBE_FORCE_SYNCHRONOUS:
 873                 return false;
 874
 875         default:
 876                 if (cmdline_requested_async_probing(drv->name))
 877                         return true;
 878
 879                 if (module_requested_async_probing(drv->owner))
 880                         return true;
 881
 882                 return false;
 883         }
 884 }
 885
 886 struct device_attach_data {
 887         struct device *dev;
 888
 889         /*
 890          * Indicates whether we are considering asynchronous probing or
 891          * not. Only initial binding after device or driver registration
 892          * (including deferral processing) may be done asynchronously, the
 893          * rest is always synchronous, as we expect it is being done by
 894          * request from userspace.
 895          */
 896         bool check_async;
 897
 898         /*
 899          * Indicates if we are binding synchronous or asynchronous drivers.
 900          * When asynchronous probing is enabled we'll execute 2 passes
 901          * over drivers: first pass doing synchronous probing and second
 902          * doing asynchronous probing (if synchronous did not succeed -
 903          * most likely because there was no driver requiring synchronous
 904          * probing - and we found asynchronous driver during first pass).
 905          * The 2 passes are done because we can't shoot asynchronous
 906          * probe for given device and driver from bus_for_each_drv() since
 907          * driver pointer is not guaranteed to stay valid once
 908          * bus_for_each_drv() iterates to the next driver on the bus.
 909          */
 910         bool want_async;
 911
 912         /*
 913          * We'll set have_async to 'true' if, while scanning for matching
 914          * driver, we'll encounter one that requests asynchronous probing.
 915          */
 916         bool have_async;
 917 };
 918
 919 static int __device_attach_driver(struct device_driver *drv, void *_data)
 920 {
 921         struct device_attach_data *data = _data;
 922         struct device *dev = data->dev;
 923         bool async_allowed;
 924         int ret;
 925
 926         ret = driver_match_device(drv, dev);
 927         if (ret == 0) {
 928                 /* no match */
 929                 return 0;
 930         } else if (ret == -EPROBE_DEFER) {
 931                 dev_dbg(dev, "Device match requests probe deferral\n");
 932                 dev->can_match = true;
 933                 driver_deferred_probe_add(dev);
 934                 /*
 935                  * Device can't match with a driver right now, so don't attempt
 936                  * to match or bind with other drivers on the bus.
 937                  */
 938                 return ret;
 939         } else if (ret < 0) {
 940                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 941                 return ret;
 942         } /* ret > 0 means positive match */
 943
 944         async_allowed = driver_allows_async_probing(drv);
 945
 946         if (async_allowed)
 947                 data->have_async = true;
 948
 949         if (data->check_async && async_allowed != data->want_async)
 950                 return 0;
 951
 952         /*
 953          * Ignore errors returned by ->probe so that the next driver can try
 954          * its luck.
 955          */
 956         ret = driver_probe_device(drv, dev);
 957         if (ret < 0)
 958                 return ret;
 959         return ret == 0;
 960 }
 961
 962 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 963 {
 964         struct device *dev = _dev;
 965         struct device_attach_data data = {
 966                 .dev            = dev,
 967                 .check_async    = true,
 968                 .want_async     = true,
 969         };
 970
 971         device_lock(dev);
 972
 973         /*
 974          * Check if device has already been removed or claimed. This may
 975          * happen with driver loading, device discovery/registration,
 976          * and deferred probe processing happens all at once with
 977          * multiple threads.
 978          */
 979         if (dev->p->dead || dev->driver)
 980                 goto out_unlock;
 981
 982         if (dev->parent)
 983                 pm_runtime_get_sync(dev->parent);
 984
 985         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 986         dev_dbg(dev, "async probe completed\n");
 987
 988         pm_request_idle(dev);
 989
 990         if (dev->parent)
 991                 pm_runtime_put(dev->parent);
 992 out_unlock:
 993         device_unlock(dev);
 994
 995         put_device(dev);
 996 }
 997
 998 static int __device_attach(struct device *dev, bool allow_async)
 999 {
1000         int ret = 0;
1001         bool async = false;
1002
1003         device_lock(dev);
1004         if (dev->p->dead) {
1005                 goto out_unlock;
1006         } else if (dev->driver) {
1007                 if (device_is_bound(dev)) {
1008                         ret = 1;
1009                         goto out_unlock;
1010                 }
1011                 ret = device_bind_driver(dev);
1012                 if (ret == 0)
1013                         ret = 1;
1014                 else {
1015                         dev->driver = NULL;
1016                         ret = 0;
1017                 }
1018         } else {
1019                 struct device_attach_data data = {
1020                         .dev = dev,
1021                         .check_async = allow_async,
1022                         .want_async = false,
1023                 };
1024
1025                 if (dev->parent)
1026                         pm_runtime_get_sync(dev->parent);
1027
1028                 ret = bus_for_each_drv(dev->bus, NULL, &data,
1029                                         __device_attach_driver);
1030                 if (!ret && allow_async && data.have_async) {
1031                         /*
1032                          * If we could not find appropriate driver
1033                          * synchronously and we are allowed to do
1034                          * async probes and there are drivers that
1035                          * want to probe asynchronously, we'll
1036                          * try them.
1037                          */
1038                         dev_dbg(dev, "scheduling asynchronous probe\n");
1039                         get_device(dev);
1040                         async = true;
1041                 } else {
1042                         pm_request_idle(dev);
1043                 }
1044
1045                 if (dev->parent)
1046                         pm_runtime_put(dev->parent);
1047         }
1048 out_unlock:
1049         device_unlock(dev);
1050         if (async)
1051                 async_schedule_dev(__device_attach_async_helper, dev);
1052         return ret;
1053 }
1054
1055 /**
1056  * device_attach - try to attach device to a driver.
1057  * @dev: device.
1058  *
1059  * Walk the list of drivers that the bus has and call
1060  * driver_probe_device() for each pair. If a compatible
1061  * pair is found, break out and return.
1062  *
1063  * Returns 1 if the device was bound to a driver;
1064  * 0 if no matching driver was found;
1065  * -ENODEV if the device is not registered.
1066  *
1067  * When called for a USB interface, @dev->parent lock must be held.
1068  */
1069 int device_attach(struct device *dev)
1070 {
1071         return __device_attach(dev, false);
1072 }
1073 EXPORT_SYMBOL_GPL(device_attach);
1074
1075 void device_initial_probe(struct device *dev)
1076 {
1077         __device_attach(dev, true);
1078 }
1079
1080 /*
1081  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1082  * @dev: Device we will update driver info for
1083  * @parent: Parent device. Needed if the bus requires parent lock
1084  *
1085  * This function will take the required locks for manipulating dev->drv.
1086  * Normally this will just be the @dev lock, but when called for a USB
1087  * interface, @parent lock will be held as well.
1088  */
1089 static void __device_driver_lock(struct device *dev, struct device *parent)
1090 {
1091         if (parent && dev->bus->need_parent_lock)
1092                 device_lock(parent);
1093         device_lock(dev);
1094 }
1095
1096 /*
1097  * __device_driver_unlock - release locks needed to manipulate dev->drv
1098  * @dev: Device we will update driver info for
1099  * @parent: Parent device. Needed if the bus requires parent lock
1100  *
1101  * This function will release the required locks for manipulating dev->drv.
1102  * Normally this will just be the @dev lock, but when called for a
1103  * USB interface, @parent lock will be released as well.
1104  */
1105 static void __device_driver_unlock(struct device *dev, struct device *parent)
1106 {
1107         device_unlock(dev);
1108         if (parent && dev->bus->need_parent_lock)
1109                 device_unlock(parent);
1110 }
1111
1112 /**
1113  * device_driver_attach - attach a specific driver to a specific device
1114  * @drv: Driver to attach
1115  * @dev: Device to attach it to
1116  *
1117  * Manually attach driver to a device. Will acquire both @dev lock and
1118  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1119  */
1120 int device_driver_attach(struct device_driver *drv, struct device *dev)
1121 {
1122         int ret;
1123
1124         __device_driver_lock(dev, dev->parent);
1125         ret = __driver_probe_device(drv, dev);
1126         __device_driver_unlock(dev, dev->parent);
1127
1128         /* also return probe errors as normal negative errnos */
1129         if (ret > 0)
1130                 ret = -ret;
1131         if (ret == -EPROBE_DEFER)
1132                 return -EAGAIN;
1133         return ret;
1134 }
1135 EXPORT_SYMBOL_GPL(device_driver_attach);
1136
1137 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1138 {
1139         struct device *dev = _dev;
1140         struct device_driver *drv;
1141         int ret;
1142
1143         __device_driver_lock(dev, dev->parent);
1144         drv = dev->p->async_driver;
1145         dev->p->async_driver = NULL;
1146         ret = driver_probe_device(drv, dev);
1147         __device_driver_unlock(dev, dev->parent);
1148
1149         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1150
1151         put_device(dev);
1152 }
1153
1154 static int __driver_attach(struct device *dev, void *data)
1155 {
1156         struct device_driver *drv = data;
1157         bool async = false;
1158         int ret;
1159
1160         /*
1161          * Lock device and try to bind to it. We drop the error
1162          * here and always return 0, because we need to keep trying
1163          * to bind to devices and some drivers will return an error
1164          * simply if it didn't support the device.
1165          *
1166          * driver_probe_device() will spit a warning if there
1167          * is an error.
1168          */
1169
1170         ret = driver_match_device(drv, dev);
1171         if (ret == 0) {
1172                 /* no match */
1173                 return 0;
1174         } else if (ret == -EPROBE_DEFER) {
1175                 dev_dbg(dev, "Device match requests probe deferral\n");
1176                 dev->can_match = true;
1177                 driver_deferred_probe_add(dev);
1178                 /*
1179                  * Driver could not match with device, but may match with
1180                  * another device on the bus.
1181                  */
1182                 return 0;
1183         } else if (ret < 0) {
1184                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1185                 /*
1186                  * Driver could not match with device, but may match with
1187                  * another device on the bus.
1188                  */
1189                 return 0;
1190         } /* ret > 0 means positive match */
1191
1192         if (driver_allows_async_probing(drv)) {
1193                 /*
1194                  * Instead of probing the device synchronously we will
1195                  * probe it asynchronously to allow for more parallelism.
1196                  *
1197                  * We only take the device lock here in order to guarantee
1198                  * that the dev->driver and async_driver fields are protected
1199                  */
1200                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1201                 device_lock(dev);
1202                 if (!dev->driver && !dev->p->async_driver) {
1203                         get_device(dev);
1204                         dev->p->async_driver = drv;
1205                         async = true;
1206                 }
1207                 device_unlock(dev);
1208                 if (async)
1209                         async_schedule_dev(__driver_attach_async_helper, dev);
1210                 return 0;
1211         }
1212
1213         __device_driver_lock(dev, dev->parent);
1214         driver_probe_device(drv, dev);
1215         __device_driver_unlock(dev, dev->parent);
1216
1217         return 0;
1218 }
1219
1220 /**
1221  * driver_attach - try to bind driver to devices.
1222  * @drv: driver.
1223  *
1224  * Walk the list of devices that the bus has on it and try to
1225  * match the driver with each one.  If driver_probe_device()
1226  * returns 0 and the @dev->driver is set, we've found a
1227  * compatible pair.
1228  */
1229 int driver_attach(struct device_driver *drv)
1230 {
1231         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1232 }
1233 EXPORT_SYMBOL_GPL(driver_attach);
1234
1235 /*
1236  * __device_release_driver() must be called with @dev lock held.
1237  * When called for a USB interface, @dev->parent lock must be held as well.
1238  */
1239 static void __device_release_driver(struct device *dev, struct device *parent)
1240 {
1241         struct device_driver *drv;
1242
1243         drv = dev->driver;
1244         if (drv) {
1245                 pm_runtime_get_sync(dev);
1246
1247                 while (device_links_busy(dev)) {
1248                         __device_driver_unlock(dev, parent);
1249
1250                         device_links_unbind_consumers(dev);
1251
1252                         __device_driver_lock(dev, parent);
1253                         /*
1254                          * A concurrent invocation of the same function might
1255                          * have released the driver successfully while this one
1256                          * was waiting, so check for that.
1257                          */
1258                         if (dev->driver != drv) {
1259                                 pm_runtime_put(dev);
1260                                 return;
1261                         }
1262                 }
1263
1264                 driver_sysfs_remove(dev);
1265
1266                 bus_notify(dev, BUS_NOTIFY_UNBIND_DRIVER);
1267
1268                 pm_runtime_put_sync(dev);
1269
1270                 device_remove(dev);
1271
1272                 if (dev->bus && dev->bus->dma_cleanup)
1273                         dev->bus->dma_cleanup(dev);
1274
1275                 device_unbind_cleanup(dev);
1276                 device_links_driver_cleanup(dev);
1277
1278                 klist_remove(&dev->p->knode_driver);
1279                 device_pm_check_callbacks(dev);
1280
1281                 bus_notify(dev, BUS_NOTIFY_UNBOUND_DRIVER);
1282                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1283         }
1284 }
1285
1286 void device_release_driver_internal(struct device *dev,
1287                                     struct device_driver *drv,
1288                                     struct device *parent)
1289 {
1290         __device_driver_lock(dev, parent);
1291
1292         if (!drv || drv == dev->driver)
1293                 __device_release_driver(dev, parent);
1294
1295         __device_driver_unlock(dev, parent);
1296 }
1297
1298 /**
1299  * device_release_driver - manually detach device from driver.
1300  * @dev: device.
1301  *
1302  * Manually detach device from driver.
1303  * When called for a USB interface, @dev->parent lock must be held.
1304  *
1305  * If this function is to be called with @dev->parent lock held, ensure that
1306  * the device's consumers are unbound in advance or that their locks can be
1307  * acquired under the @dev->parent lock.
1308  */
1309 void device_release_driver(struct device *dev)
1310 {
1311         /*
1312          * If anyone calls device_release_driver() recursively from
1313          * within their ->remove callback for the same device, they
1314          * will deadlock right here.
1315          */
1316         device_release_driver_internal(dev, NULL, NULL);
1317 }
1318 EXPORT_SYMBOL_GPL(device_release_driver);
1319
1320 /**
1321  * device_driver_detach - detach driver from a specific device
1322  * @dev: device to detach driver from
1323  *
1324  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1325  * lock if needed.
1326  */
1327 void device_driver_detach(struct device *dev)
1328 {
1329         device_release_driver_internal(dev, NULL, dev->parent);
1330 }
1331
1332 /**
1333  * driver_detach - detach driver from all devices it controls.
1334  * @drv: driver.
1335  */
1336 void driver_detach(struct device_driver *drv)
1337 {
1338         struct device_private *dev_prv;
1339         struct device *dev;
1340
1341         if (driver_allows_async_probing(drv))
1342                 async_synchronize_full();
1343
1344         for (;;) {
1345                 spin_lock(&drv->p->klist_devices.k_lock);
1346                 if (list_empty(&drv->p->klist_devices.k_list)) {
1347                         spin_unlock(&drv->p->klist_devices.k_lock);
1348                         break;
1349                 }
1350                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1351                                      struct device_private,
1352                                      knode_driver.n_node);
1353                 dev = dev_prv->device;
1354                 get_device(dev);
1355                 spin_unlock(&drv->p->klist_devices.k_lock);
1356                 device_release_driver_internal(dev, drv, dev->parent);
1357                 put_device(dev);
1358         }
1359 }