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-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 int driver_deferred_probe_timeout = 10;
 261 #else
 262 int driver_deferred_probe_timeout;
 263 #endif
 264
 265 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
 266
 267 static int __init deferred_probe_timeout_setup(char *str)
 268 {
 269         int timeout;
 270
 271         if (!kstrtoint(str, 10, &timeout))
 272                 driver_deferred_probe_timeout = timeout;
 273         return 1;
 274 }
 275 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 276
 277 /**
 278  * driver_deferred_probe_check_state() - Check deferred probe state
 279  * @dev: device to check
 280  *
 281  * Return:
 282  * * -ENODEV if initcalls have completed and modules are disabled.
 283  * * -ETIMEDOUT if the deferred probe timeout was set and has expired
 284  *   and modules are enabled.
 285  * * -EPROBE_DEFER in other cases.
 286  *
 287  * Drivers or subsystems can opt-in to calling this function instead of directly
 288  * returning -EPROBE_DEFER.
 289  */
 290 int driver_deferred_probe_check_state(struct device *dev)
 291 {
 292         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 293                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 294                 return -ENODEV;
 295         }
 296
 297         if (!driver_deferred_probe_timeout && initcalls_done) {
 298                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 299                 return -ETIMEDOUT;
 300         }
 301
 302         return -EPROBE_DEFER;
 303 }
 304 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
 305
 306 static void deferred_probe_timeout_work_func(struct work_struct *work)
 307 {
 308         struct device_private *p;
 309
 310         fw_devlink_drivers_done();
 311
 312         driver_deferred_probe_timeout = 0;
 313         driver_deferred_probe_trigger();
 314         flush_work(&deferred_probe_work);
 315
 316         mutex_lock(&deferred_probe_mutex);
 317         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 318                 dev_info(p->device, "deferred probe pending\n");
 319         mutex_unlock(&deferred_probe_mutex);
 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         return 0;
 370 }
 371 late_initcall(deferred_probe_initcall);
 372
 373 static void __exit deferred_probe_exit(void)
 374 {
 375         debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
 376 }
 377 __exitcall(deferred_probe_exit);
 378
 379 /**
 380  * device_is_bound() - Check if device is bound to a driver
 381  * @dev: device to check
 382  *
 383  * Returns true if passed device has already finished probing successfully
 384  * against a driver.
 385  *
 386  * This function must be called with the device lock held.
 387  */
 388 bool device_is_bound(struct device *dev)
 389 {
 390         return dev->p && klist_node_attached(&dev->p->knode_driver);
 391 }
 392
 393 static void driver_bound(struct device *dev)
 394 {
 395         if (device_is_bound(dev)) {
 396                 pr_warn("%s: device %s already bound\n",
 397                         __func__, kobject_name(&dev->kobj));
 398                 return;
 399         }
 400
 401         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 402                  __func__, dev_name(dev));
 403
 404         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 405         device_links_driver_bound(dev);
 406
 407         device_pm_check_callbacks(dev);
 408
 409         /*
 410          * Make sure the device is no longer in one of the deferred lists and
 411          * kick off retrying all pending devices
 412          */
 413         driver_deferred_probe_del(dev);
 414         driver_deferred_probe_trigger();
 415
 416         if (dev->bus)
 417                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 418                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 419
 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         if (dev->bus)
 439                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 440                                              BUS_NOTIFY_BIND_DRIVER, dev);
 441
 442         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 443                                 kobject_name(&dev->kobj));
 444         if (ret)
 445                 goto fail;
 446
 447         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 448                                 "driver");
 449         if (ret)
 450                 goto rm_dev;
 451
 452         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 453                 return 0;
 454
 455         ret = device_create_file(dev, &dev_attr_coredump);
 456         if (!ret)
 457                 return 0;
 458
 459         sysfs_remove_link(&dev->kobj, "driver");
 460
 461 rm_dev:
 462         sysfs_remove_link(&dev->driver->p->kobj,
 463                           kobject_name(&dev->kobj));
 464
 465 fail:
 466         return ret;
 467 }
 468
 469 static void driver_sysfs_remove(struct device *dev)
 470 {
 471         struct device_driver *drv = dev->driver;
 472
 473         if (drv) {
 474                 if (drv->coredump)
 475                         device_remove_file(dev, &dev_attr_coredump);
 476                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 477                 sysfs_remove_link(&dev->kobj, "driver");
 478         }
 479 }
 480
 481 /**
 482  * device_bind_driver - bind a driver to one device.
 483  * @dev: device.
 484  *
 485  * Allow manual attachment of a driver to a device.
 486  * Caller must have already set @dev->driver.
 487  *
 488  * Note that this does not modify the bus reference count.
 489  * Please verify that is accounted for before calling this.
 490  * (It is ok to call with no other effort from a driver's probe() method.)
 491  *
 492  * This function must be called with the device lock held.
 493  *
 494  * Callers should prefer to use device_driver_attach() instead.
 495  */
 496 int device_bind_driver(struct device *dev)
 497 {
 498         int ret;
 499
 500         ret = driver_sysfs_add(dev);
 501         if (!ret) {
 502                 device_links_force_bind(dev);
 503                 driver_bound(dev);
 504         }
 505         else if (dev->bus)
 506                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 507                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 508         return ret;
 509 }
 510 EXPORT_SYMBOL_GPL(device_bind_driver);
 511
 512 static atomic_t probe_count = ATOMIC_INIT(0);
 513 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 514
 515 static ssize_t state_synced_show(struct device *dev,
 516                                  struct device_attribute *attr, char *buf)
 517 {
 518         bool val;
 519
 520         device_lock(dev);
 521         val = dev->state_synced;
 522         device_unlock(dev);
 523
 524         return sysfs_emit(buf, "%u\n", val);
 525 }
 526 static DEVICE_ATTR_RO(state_synced);
 527
 528 static void device_unbind_cleanup(struct device *dev)
 529 {
 530         devres_release_all(dev);
 531         arch_teardown_dma_ops(dev);
 532         kfree(dev->dma_range_map);
 533         dev->dma_range_map = NULL;
 534         dev->driver = NULL;
 535         dev_set_drvdata(dev, NULL);
 536         if (dev->pm_domain && dev->pm_domain->dismiss)
 537                 dev->pm_domain->dismiss(dev);
 538         pm_runtime_reinit(dev);
 539         dev_pm_set_driver_flags(dev, 0);
 540 }
 541
 542 static void device_remove(struct device *dev)
 543 {
 544         device_remove_file(dev, &dev_attr_state_synced);
 545         device_remove_groups(dev, dev->driver->dev_groups);
 546
 547         if (dev->bus && dev->bus->remove)
 548                 dev->bus->remove(dev);
 549         else if (dev->driver->remove)
 550                 dev->driver->remove(dev);
 551 }
 552
 553 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 554 {
 555         int ret = 0;
 556
 557         if (dev->bus->probe)
 558                 ret = dev->bus->probe(dev);
 559         else if (drv->probe)
 560                 ret = drv->probe(dev);
 561
 562         switch (ret) {
 563         case 0:
 564                 break;
 565         case -EPROBE_DEFER:
 566                 /* Driver requested deferred probing */
 567                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 568                 break;
 569         case -ENODEV:
 570         case -ENXIO:
 571                 pr_debug("%s: probe of %s rejects match %d\n",
 572                          drv->name, dev_name(dev), ret);
 573                 break;
 574         default:
 575                 /* driver matched but the probe failed */
 576                 pr_warn("%s: probe of %s failed with error %d\n",
 577                         drv->name, dev_name(dev), ret);
 578                 break;
 579         }
 580
 581         return ret;
 582 }
 583
 584 static int really_probe(struct device *dev, struct device_driver *drv)
 585 {
 586         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 587                            !drv->suppress_bind_attrs;
 588         int ret, link_ret;
 589
 590         if (defer_all_probes) {
 591                 /*
 592                  * Value of defer_all_probes can be set only by
 593                  * device_block_probing() which, in turn, will call
 594                  * wait_for_device_probe() right after that to avoid any races.
 595                  */
 596                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 597                 return -EPROBE_DEFER;
 598         }
 599
 600         link_ret = device_links_check_suppliers(dev);
 601         if (link_ret == -EPROBE_DEFER)
 602                 return link_ret;
 603
 604         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 605                  drv->bus->name, __func__, drv->name, dev_name(dev));
 606         if (!list_empty(&dev->devres_head)) {
 607                 dev_crit(dev, "Resources present before probing\n");
 608                 ret = -EBUSY;
 609                 goto done;
 610         }
 611
 612 re_probe:
 613         dev->driver = drv;
 614
 615         /* If using pinctrl, bind pins now before probing */
 616         ret = pinctrl_bind_pins(dev);
 617         if (ret)
 618                 goto pinctrl_bind_failed;
 619
 620         if (dev->bus->dma_configure) {
 621                 ret = dev->bus->dma_configure(dev);
 622                 if (ret)
 623                         goto pinctrl_bind_failed;
 624         }
 625
 626         ret = driver_sysfs_add(dev);
 627         if (ret) {
 628                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 629                        __func__, dev_name(dev));
 630                 goto sysfs_failed;
 631         }
 632
 633         if (dev->pm_domain && dev->pm_domain->activate) {
 634                 ret = dev->pm_domain->activate(dev);
 635                 if (ret)
 636                         goto probe_failed;
 637         }
 638
 639         ret = call_driver_probe(dev, drv);
 640         if (ret) {
 641                 /*
 642                  * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
 643                  * device might actually probe properly once some of its missing
 644                  * suppliers have probed. So, treat this as if the driver
 645                  * returned -EPROBE_DEFER.
 646                  */
 647                 if (link_ret == -EAGAIN)
 648                         ret = -EPROBE_DEFER;
 649
 650                 /*
 651                  * Return probe errors as positive values so that the callers
 652                  * can distinguish them from other errors.
 653                  */
 654                 ret = -ret;
 655                 goto probe_failed;
 656         }
 657
 658         ret = device_add_groups(dev, drv->dev_groups);
 659         if (ret) {
 660                 dev_err(dev, "device_add_groups() failed\n");
 661                 goto dev_groups_failed;
 662         }
 663
 664         if (dev_has_sync_state(dev)) {
 665                 ret = device_create_file(dev, &dev_attr_state_synced);
 666                 if (ret) {
 667                         dev_err(dev, "state_synced sysfs add failed\n");
 668                         goto dev_sysfs_state_synced_failed;
 669                 }
 670         }
 671
 672         if (test_remove) {
 673                 test_remove = false;
 674
 675                 device_remove(dev);
 676                 driver_sysfs_remove(dev);
 677                 device_unbind_cleanup(dev);
 678
 679                 goto re_probe;
 680         }
 681
 682         pinctrl_init_done(dev);
 683
 684         if (dev->pm_domain && dev->pm_domain->sync)
 685                 dev->pm_domain->sync(dev);
 686
 687         driver_bound(dev);
 688         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 689                  drv->bus->name, __func__, dev_name(dev), drv->name);
 690         goto done;
 691
 692 dev_sysfs_state_synced_failed:
 693 dev_groups_failed:
 694         device_remove(dev);
 695 probe_failed:
 696         driver_sysfs_remove(dev);
 697 sysfs_failed:
 698         if (dev->bus)
 699                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 700                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 701         if (dev->bus && dev->bus->dma_cleanup)
 702                 dev->bus->dma_cleanup(dev);
 703 pinctrl_bind_failed:
 704         device_links_no_driver(dev);
 705         device_unbind_cleanup(dev);
 706 done:
 707         return ret;
 708 }
 709
 710 /*
 711  * For initcall_debug, show the driver probe time.
 712  */
 713 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 714 {
 715         ktime_t calltime, rettime;
 716         int ret;
 717
 718         calltime = ktime_get();
 719         ret = really_probe(dev, drv);
 720         rettime = ktime_get();
 721         pr_debug("probe of %s returned %d after %lld usecs\n",
 722                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 723         return ret;
 724 }
 725
 726 /**
 727  * driver_probe_done
 728  * Determine if the probe sequence is finished or not.
 729  *
 730  * Should somehow figure out how to use a semaphore, not an atomic variable...
 731  */
 732 int driver_probe_done(void)
 733 {
 734         int local_probe_count = atomic_read(&probe_count);
 735
 736         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 737         if (local_probe_count)
 738                 return -EBUSY;
 739         return 0;
 740 }
 741
 742 /**
 743  * wait_for_device_probe
 744  * Wait for device probing to be completed.
 745  */
 746 void wait_for_device_probe(void)
 747 {
 748         /* wait for the deferred probe workqueue to finish */
 749         flush_work(&deferred_probe_work);
 750
 751         /* wait for the known devices to complete their probing */
 752         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 753         async_synchronize_full();
 754 }
 755 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 756
 757 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 758 {
 759         int ret = 0;
 760
 761         if (dev->p->dead || !device_is_registered(dev))
 762                 return -ENODEV;
 763         if (dev->driver)
 764                 return -EBUSY;
 765
 766         dev->can_match = true;
 767         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 768                  drv->bus->name, __func__, dev_name(dev), drv->name);
 769
 770         pm_runtime_get_suppliers(dev);
 771         if (dev->parent)
 772                 pm_runtime_get_sync(dev->parent);
 773
 774         pm_runtime_barrier(dev);
 775         if (initcall_debug)
 776                 ret = really_probe_debug(dev, drv);
 777         else
 778                 ret = really_probe(dev, drv);
 779         pm_request_idle(dev);
 780
 781         if (dev->parent)
 782                 pm_runtime_put(dev->parent);
 783
 784         pm_runtime_put_suppliers(dev);
 785         return ret;
 786 }
 787
 788 /**
 789  * driver_probe_device - attempt to bind device & driver together
 790  * @drv: driver to bind a device to
 791  * @dev: device to try to bind to the driver
 792  *
 793  * This function returns -ENODEV if the device is not registered, -EBUSY if it
 794  * already has a driver, 0 if the device is bound successfully and a positive
 795  * (inverted) error code for failures from the ->probe method.
 796  *
 797  * This function must be called with @dev lock held.  When called for a
 798  * USB interface, @dev->parent lock must be held as well.
 799  *
 800  * If the device has a parent, runtime-resume the parent before driver probing.
 801  */
 802 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 803 {
 804         int trigger_count = atomic_read(&deferred_trigger_count);
 805         int ret;
 806
 807         atomic_inc(&probe_count);
 808         ret = __driver_probe_device(drv, dev);
 809         if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
 810                 driver_deferred_probe_add(dev);
 811
 812                 /*
 813                  * Did a trigger occur while probing? Need to re-trigger if yes
 814                  */
 815                 if (trigger_count != atomic_read(&deferred_trigger_count) &&
 816                     !defer_all_probes)
 817                         driver_deferred_probe_trigger();
 818         }
 819         atomic_dec(&probe_count);
 820         wake_up_all(&probe_waitqueue);
 821         return ret;
 822 }
 823
 824 static inline bool cmdline_requested_async_probing(const char *drv_name)
 825 {
 826         bool async_drv;
 827
 828         async_drv = parse_option_str(async_probe_drv_names, drv_name);
 829
 830         return (async_probe_default != async_drv);
 831 }
 832
 833 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 834 static int __init save_async_options(char *buf)
 835 {
 836         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 837                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 838
 839         strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 840         async_probe_default = parse_option_str(async_probe_drv_names, "*");
 841
 842         return 1;
 843 }
 844 __setup("driver_async_probe=", save_async_options);
 845
 846 bool driver_allows_async_probing(struct device_driver *drv)
 847 {
 848         switch (drv->probe_type) {
 849         case PROBE_PREFER_ASYNCHRONOUS:
 850                 return true;
 851
 852         case PROBE_FORCE_SYNCHRONOUS:
 853                 return false;
 854
 855         default:
 856                 if (cmdline_requested_async_probing(drv->name))
 857                         return true;
 858
 859                 if (module_requested_async_probing(drv->owner))
 860                         return true;
 861
 862                 return false;
 863         }
 864 }
 865
 866 struct device_attach_data {
 867         struct device *dev;
 868
 869         /*
 870          * Indicates whether we are considering asynchronous probing or
 871          * not. Only initial binding after device or driver registration
 872          * (including deferral processing) may be done asynchronously, the
 873          * rest is always synchronous, as we expect it is being done by
 874          * request from userspace.
 875          */
 876         bool check_async;
 877
 878         /*
 879          * Indicates if we are binding synchronous or asynchronous drivers.
 880          * When asynchronous probing is enabled we'll execute 2 passes
 881          * over drivers: first pass doing synchronous probing and second
 882          * doing asynchronous probing (if synchronous did not succeed -
 883          * most likely because there was no driver requiring synchronous
 884          * probing - and we found asynchronous driver during first pass).
 885          * The 2 passes are done because we can't shoot asynchronous
 886          * probe for given device and driver from bus_for_each_drv() since
 887          * driver pointer is not guaranteed to stay valid once
 888          * bus_for_each_drv() iterates to the next driver on the bus.
 889          */
 890         bool want_async;
 891
 892         /*
 893          * We'll set have_async to 'true' if, while scanning for matching
 894          * driver, we'll encounter one that requests asynchronous probing.
 895          */
 896         bool have_async;
 897 };
 898
 899 static int __device_attach_driver(struct device_driver *drv, void *_data)
 900 {
 901         struct device_attach_data *data = _data;
 902         struct device *dev = data->dev;
 903         bool async_allowed;
 904         int ret;
 905
 906         ret = driver_match_device(drv, dev);
 907         if (ret == 0) {
 908                 /* no match */
 909                 return 0;
 910         } else if (ret == -EPROBE_DEFER) {
 911                 dev_dbg(dev, "Device match requests probe deferral\n");
 912                 dev->can_match = true;
 913                 driver_deferred_probe_add(dev);
 914                 /*
 915                  * Device can't match with a driver right now, so don't attempt
 916                  * to match or bind with other drivers on the bus.
 917                  */
 918                 return ret;
 919         } else if (ret < 0) {
 920                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 921                 return ret;
 922         } /* ret > 0 means positive match */
 923
 924         async_allowed = driver_allows_async_probing(drv);
 925
 926         if (async_allowed)
 927                 data->have_async = true;
 928
 929         if (data->check_async && async_allowed != data->want_async)
 930                 return 0;
 931
 932         /*
 933          * Ignore errors returned by ->probe so that the next driver can try
 934          * its luck.
 935          */
 936         ret = driver_probe_device(drv, dev);
 937         if (ret < 0)
 938                 return ret;
 939         return ret == 0;
 940 }
 941
 942 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 943 {
 944         struct device *dev = _dev;
 945         struct device_attach_data data = {
 946                 .dev            = dev,
 947                 .check_async    = true,
 948                 .want_async     = true,
 949         };
 950
 951         device_lock(dev);
 952
 953         /*
 954          * Check if device has already been removed or claimed. This may
 955          * happen with driver loading, device discovery/registration,
 956          * and deferred probe processing happens all at once with
 957          * multiple threads.
 958          */
 959         if (dev->p->dead || dev->driver)
 960                 goto out_unlock;
 961
 962         if (dev->parent)
 963                 pm_runtime_get_sync(dev->parent);
 964
 965         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 966         dev_dbg(dev, "async probe completed\n");
 967
 968         pm_request_idle(dev);
 969
 970         if (dev->parent)
 971                 pm_runtime_put(dev->parent);
 972 out_unlock:
 973         device_unlock(dev);
 974
 975         put_device(dev);
 976 }
 977
 978 static int __device_attach(struct device *dev, bool allow_async)
 979 {
 980         int ret = 0;
 981         bool async = false;
 982
 983         device_lock(dev);
 984         if (dev->p->dead) {
 985                 goto out_unlock;
 986         } else if (dev->driver) {
 987                 if (device_is_bound(dev)) {
 988                         ret = 1;
 989                         goto out_unlock;
 990                 }
 991                 ret = device_bind_driver(dev);
 992                 if (ret == 0)
 993                         ret = 1;
 994                 else {
 995                         dev->driver = NULL;
 996                         ret = 0;
 997                 }
 998         } else {
 999                 struct device_attach_data data = {
1000                         .dev = dev,
1001                         .check_async = allow_async,
1002                         .want_async = false,
1003                 };
1004
1005                 if (dev->parent)
1006                         pm_runtime_get_sync(dev->parent);
1007
1008                 ret = bus_for_each_drv(dev->bus, NULL, &data,
1009                                         __device_attach_driver);
1010                 if (!ret && allow_async && data.have_async) {
1011                         /*
1012                          * If we could not find appropriate driver
1013                          * synchronously and we are allowed to do
1014                          * async probes and there are drivers that
1015                          * want to probe asynchronously, we'll
1016                          * try them.
1017                          */
1018                         dev_dbg(dev, "scheduling asynchronous probe\n");
1019                         get_device(dev);
1020                         async = true;
1021                 } else {
1022                         pm_request_idle(dev);
1023                 }
1024
1025                 if (dev->parent)
1026                         pm_runtime_put(dev->parent);
1027         }
1028 out_unlock:
1029         device_unlock(dev);
1030         if (async)
1031                 async_schedule_dev(__device_attach_async_helper, dev);
1032         return ret;
1033 }
1034
1035 /**
1036  * device_attach - try to attach device to a driver.
1037  * @dev: device.
1038  *
1039  * Walk the list of drivers that the bus has and call
1040  * driver_probe_device() for each pair. If a compatible
1041  * pair is found, break out and return.
1042  *
1043  * Returns 1 if the device was bound to a driver;
1044  * 0 if no matching driver was found;
1045  * -ENODEV if the device is not registered.
1046  *
1047  * When called for a USB interface, @dev->parent lock must be held.
1048  */
1049 int device_attach(struct device *dev)
1050 {
1051         return __device_attach(dev, false);
1052 }
1053 EXPORT_SYMBOL_GPL(device_attach);
1054
1055 void device_initial_probe(struct device *dev)
1056 {
1057         __device_attach(dev, true);
1058 }
1059
1060 /*
1061  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1062  * @dev: Device we will update driver info for
1063  * @parent: Parent device. Needed if the bus requires parent lock
1064  *
1065  * This function will take the required locks for manipulating dev->drv.
1066  * Normally this will just be the @dev lock, but when called for a USB
1067  * interface, @parent lock will be held as well.
1068  */
1069 static void __device_driver_lock(struct device *dev, struct device *parent)
1070 {
1071         if (parent && dev->bus->need_parent_lock)
1072                 device_lock(parent);
1073         device_lock(dev);
1074 }
1075
1076 /*
1077  * __device_driver_unlock - release locks needed to manipulate dev->drv
1078  * @dev: Device we will update driver info for
1079  * @parent: Parent device. Needed if the bus requires parent lock
1080  *
1081  * This function will release the required locks for manipulating dev->drv.
1082  * Normally this will just be the @dev lock, but when called for a
1083  * USB interface, @parent lock will be released as well.
1084  */
1085 static void __device_driver_unlock(struct device *dev, struct device *parent)
1086 {
1087         device_unlock(dev);
1088         if (parent && dev->bus->need_parent_lock)
1089                 device_unlock(parent);
1090 }
1091
1092 /**
1093  * device_driver_attach - attach a specific driver to a specific device
1094  * @drv: Driver to attach
1095  * @dev: Device to attach it to
1096  *
1097  * Manually attach driver to a device. Will acquire both @dev lock and
1098  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1099  */
1100 int device_driver_attach(struct device_driver *drv, struct device *dev)
1101 {
1102         int ret;
1103
1104         __device_driver_lock(dev, dev->parent);
1105         ret = __driver_probe_device(drv, dev);
1106         __device_driver_unlock(dev, dev->parent);
1107
1108         /* also return probe errors as normal negative errnos */
1109         if (ret > 0)
1110                 ret = -ret;
1111         if (ret == -EPROBE_DEFER)
1112                 return -EAGAIN;
1113         return ret;
1114 }
1115 EXPORT_SYMBOL_GPL(device_driver_attach);
1116
1117 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1118 {
1119         struct device *dev = _dev;
1120         struct device_driver *drv;
1121         int ret;
1122
1123         __device_driver_lock(dev, dev->parent);
1124         drv = dev->p->async_driver;
1125         dev->p->async_driver = NULL;
1126         ret = driver_probe_device(drv, dev);
1127         __device_driver_unlock(dev, dev->parent);
1128
1129         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1130
1131         put_device(dev);
1132 }
1133
1134 static int __driver_attach(struct device *dev, void *data)
1135 {
1136         struct device_driver *drv = data;
1137         bool async = false;
1138         int ret;
1139
1140         /*
1141          * Lock device and try to bind to it. We drop the error
1142          * here and always return 0, because we need to keep trying
1143          * to bind to devices and some drivers will return an error
1144          * simply if it didn't support the device.
1145          *
1146          * driver_probe_device() will spit a warning if there
1147          * is an error.
1148          */
1149
1150         ret = driver_match_device(drv, dev);
1151         if (ret == 0) {
1152                 /* no match */
1153                 return 0;
1154         } else if (ret == -EPROBE_DEFER) {
1155                 dev_dbg(dev, "Device match requests probe deferral\n");
1156                 dev->can_match = true;
1157                 driver_deferred_probe_add(dev);
1158                 /*
1159                  * Driver could not match with device, but may match with
1160                  * another device on the bus.
1161                  */
1162                 return 0;
1163         } else if (ret < 0) {
1164                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1165                 return ret;
1166         } /* ret > 0 means positive match */
1167
1168         if (driver_allows_async_probing(drv)) {
1169                 /*
1170                  * Instead of probing the device synchronously we will
1171                  * probe it asynchronously to allow for more parallelism.
1172                  *
1173                  * We only take the device lock here in order to guarantee
1174                  * that the dev->driver and async_driver fields are protected
1175                  */
1176                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1177                 device_lock(dev);
1178                 if (!dev->driver && !dev->p->async_driver) {
1179                         get_device(dev);
1180                         dev->p->async_driver = drv;
1181                         async = true;
1182                 }
1183                 device_unlock(dev);
1184                 if (async)
1185                         async_schedule_dev(__driver_attach_async_helper, dev);
1186                 return 0;
1187         }
1188
1189         __device_driver_lock(dev, dev->parent);
1190         driver_probe_device(drv, dev);
1191         __device_driver_unlock(dev, dev->parent);
1192
1193         return 0;
1194 }
1195
1196 /**
1197  * driver_attach - try to bind driver to devices.
1198  * @drv: driver.
1199  *
1200  * Walk the list of devices that the bus has on it and try to
1201  * match the driver with each one.  If driver_probe_device()
1202  * returns 0 and the @dev->driver is set, we've found a
1203  * compatible pair.
1204  */
1205 int driver_attach(struct device_driver *drv)
1206 {
1207         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1208 }
1209 EXPORT_SYMBOL_GPL(driver_attach);
1210
1211 /*
1212  * __device_release_driver() must be called with @dev lock held.
1213  * When called for a USB interface, @dev->parent lock must be held as well.
1214  */
1215 static void __device_release_driver(struct device *dev, struct device *parent)
1216 {
1217         struct device_driver *drv;
1218
1219         drv = dev->driver;
1220         if (drv) {
1221                 pm_runtime_get_sync(dev);
1222
1223                 while (device_links_busy(dev)) {
1224                         __device_driver_unlock(dev, parent);
1225
1226                         device_links_unbind_consumers(dev);
1227
1228                         __device_driver_lock(dev, parent);
1229                         /*
1230                          * A concurrent invocation of the same function might
1231                          * have released the driver successfully while this one
1232                          * was waiting, so check for that.
1233                          */
1234                         if (dev->driver != drv) {
1235                                 pm_runtime_put(dev);
1236                                 return;
1237                         }
1238                 }
1239
1240                 driver_sysfs_remove(dev);
1241
1242                 if (dev->bus)
1243                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1244                                                      BUS_NOTIFY_UNBIND_DRIVER,
1245                                                      dev);
1246
1247                 pm_runtime_put_sync(dev);
1248
1249                 device_remove(dev);
1250
1251                 if (dev->bus && dev->bus->dma_cleanup)
1252                         dev->bus->dma_cleanup(dev);
1253
1254                 device_links_driver_cleanup(dev);
1255                 device_unbind_cleanup(dev);
1256
1257                 klist_remove(&dev->p->knode_driver);
1258                 device_pm_check_callbacks(dev);
1259                 if (dev->bus)
1260                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1261                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1262                                                      dev);
1263
1264                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1265         }
1266 }
1267
1268 void device_release_driver_internal(struct device *dev,
1269                                     struct device_driver *drv,
1270                                     struct device *parent)
1271 {
1272         __device_driver_lock(dev, parent);
1273
1274         if (!drv || drv == dev->driver)
1275                 __device_release_driver(dev, parent);
1276
1277         __device_driver_unlock(dev, parent);
1278 }
1279
1280 /**
1281  * device_release_driver - manually detach device from driver.
1282  * @dev: device.
1283  *
1284  * Manually detach device from driver.
1285  * When called for a USB interface, @dev->parent lock must be held.
1286  *
1287  * If this function is to be called with @dev->parent lock held, ensure that
1288  * the device's consumers are unbound in advance or that their locks can be
1289  * acquired under the @dev->parent lock.
1290  */
1291 void device_release_driver(struct device *dev)
1292 {
1293         /*
1294          * If anyone calls device_release_driver() recursively from
1295          * within their ->remove callback for the same device, they
1296          * will deadlock right here.
1297          */
1298         device_release_driver_internal(dev, NULL, NULL);
1299 }
1300 EXPORT_SYMBOL_GPL(device_release_driver);
1301
1302 /**
1303  * device_driver_detach - detach driver from a specific device
1304  * @dev: device to detach driver from
1305  *
1306  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1307  * lock if needed.
1308  */
1309 void device_driver_detach(struct device *dev)
1310 {
1311         device_release_driver_internal(dev, NULL, dev->parent);
1312 }
1313
1314 /**
1315  * driver_detach - detach driver from all devices it controls.
1316  * @drv: driver.
1317  */
1318 void driver_detach(struct device_driver *drv)
1319 {
1320         struct device_private *dev_prv;
1321         struct device *dev;
1322
1323         if (driver_allows_async_probing(drv))
1324                 async_synchronize_full();
1325
1326         for (;;) {
1327                 spin_lock(&drv->p->klist_devices.k_lock);
1328                 if (list_empty(&drv->p->klist_devices.k_list)) {
1329                         spin_unlock(&drv->p->klist_devices.k_lock);
1330                         break;
1331                 }
1332                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1333                                      struct device_private,
1334                                      knode_driver.n_node);
1335                 dev = dev_prv->device;
1336                 get_device(dev);
1337                 spin_unlock(&drv->p->klist_devices.k_lock);
1338                 device_release_driver_internal(dev, drv, dev->parent);
1339                 put_device(dev);
1340         }
1341 }