1 /* 2 * drivers/base/dd.c - The core device/driver interactions. 3 * 4 * This file contains the (sometimes tricky) code that controls the 5 * interactions between devices and drivers, which primarily includes 6 * driver binding and unbinding. 7 * 8 * All of this code used to exist in drivers/base/bus.c, but was 9 * relocated to here in the name of compartmentalization (since it wasn't 10 * strictly code just for the 'struct bus_type'. 11 * 12 * Copyright (c) 2002-5 Patrick Mochel 13 * Copyright (c) 2002-3 Open Source Development Labs 14 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de> 15 * Copyright (c) 2007-2009 Novell Inc. 16 * 17 * This file is released under the GPLv2 18 */ 19 20 #include <linux/device.h> 21 #include <linux/delay.h> 22 #include <linux/module.h> 23 #include <linux/kthread.h> 24 #include <linux/wait.h> 25 #include <linux/async.h> 26 #include <linux/pm_runtime.h> 27 #include <linux/pinctrl/devinfo.h> 28 29 #include "base.h" 30 #include "power/power.h" 31 32 /* 33 * Deferred Probe infrastructure. 34 * 35 * Sometimes driver probe order matters, but the kernel doesn't always have 36 * dependency information which means some drivers will get probed before a 37 * resource it depends on is available. For example, an SDHCI driver may 38 * first need a GPIO line from an i2c GPIO controller before it can be 39 * initialized. If a required resource is not available yet, a driver can 40 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook 41 * 42 * Deferred probe maintains two lists of devices, a pending list and an active 43 * list. A driver returning -EPROBE_DEFER causes the device to be added to the 44 * pending list. A successful driver probe will trigger moving all devices 45 * from the pending to the active list so that the workqueue will eventually 46 * retry them. 47 * 48 * The deferred_probe_mutex must be held any time the deferred_probe_*_list 49 * of the (struct device*)->p->deferred_probe pointers are manipulated 50 */ 51 static DEFINE_MUTEX(deferred_probe_mutex); 52 static LIST_HEAD(deferred_probe_pending_list); 53 static LIST_HEAD(deferred_probe_active_list); 54 static atomic_t deferred_trigger_count = ATOMIC_INIT(0); 55 56 static ssize_t deferred_probe_show(struct device *dev, 57 struct device_attribute *attr, char *buf) 58 { 59 bool value; 60 61 mutex_lock(&deferred_probe_mutex); 62 value = !list_empty(&dev->p->deferred_probe); 63 mutex_unlock(&deferred_probe_mutex); 64 65 return sprintf(buf, "%d\n", value); 66 } 67 DEVICE_ATTR_RO(deferred_probe); 68 69 /* 70 * In some cases, like suspend to RAM or hibernation, It might be reasonable 71 * to prohibit probing of devices as it could be unsafe. 72 * Once defer_all_probes is true all drivers probes will be forcibly deferred. 73 */ 74 static bool defer_all_probes; 75 76 /* 77 * deferred_probe_work_func() - Retry probing devices in the active list. 78 */ 79 static void deferred_probe_work_func(struct work_struct *work) 80 { 81 struct device *dev; 82 struct device_private *private; 83 /* 84 * This block processes every device in the deferred 'active' list. 85 * Each device is removed from the active list and passed to 86 * bus_probe_device() to re-attempt the probe. The loop continues 87 * until every device in the active list is removed and retried. 88 * 89 * Note: Once the device is removed from the list and the mutex is 90 * released, it is possible for the device get freed by another thread 91 * and cause a illegal pointer dereference. This code uses 92 * get/put_device() to ensure the device structure cannot disappear 93 * from under our feet. 94 */ 95 mutex_lock(&deferred_probe_mutex); 96 while (!list_empty(&deferred_probe_active_list)) { 97 private = list_first_entry(&deferred_probe_active_list, 98 typeof(*dev->p), deferred_probe); 99 dev = private->device; 100 list_del_init(&private->deferred_probe); 101 102 get_device(dev); 103 104 /* 105 * Drop the mutex while probing each device; the probe path may 106 * manipulate the deferred list 107 */ 108 mutex_unlock(&deferred_probe_mutex); 109 110 /* 111 * Force the device to the end of the dpm_list since 112 * the PM code assumes that the order we add things to 113 * the list is a good order for suspend but deferred 114 * probe makes that very unsafe. 115 */ 116 device_pm_lock(); 117 device_pm_move_last(dev); 118 device_pm_unlock(); 119 120 dev_dbg(dev, "Retrying from deferred list\n"); 121 bus_probe_device(dev); 122 123 mutex_lock(&deferred_probe_mutex); 124 125 put_device(dev); 126 } 127 mutex_unlock(&deferred_probe_mutex); 128 } 129 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func); 130 131 static void driver_deferred_probe_add(struct device *dev) 132 { 133 mutex_lock(&deferred_probe_mutex); 134 if (list_empty(&dev->p->deferred_probe)) { 135 dev_dbg(dev, "Added to deferred list\n"); 136 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list); 137 } 138 mutex_unlock(&deferred_probe_mutex); 139 } 140 141 void driver_deferred_probe_del(struct device *dev) 142 { 143 mutex_lock(&deferred_probe_mutex); 144 if (!list_empty(&dev->p->deferred_probe)) { 145 dev_dbg(dev, "Removed from deferred list\n"); 146 list_del_init(&dev->p->deferred_probe); 147 } 148 mutex_unlock(&deferred_probe_mutex); 149 } 150 151 static bool driver_deferred_probe_enable = false; 152 /** 153 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices 154 * 155 * This functions moves all devices from the pending list to the active 156 * list and schedules the deferred probe workqueue to process them. It 157 * should be called anytime a driver is successfully bound to a device. 158 * 159 * Note, there is a race condition in multi-threaded probe. In the case where 160 * more than one device is probing at the same time, it is possible for one 161 * probe to complete successfully while another is about to defer. If the second 162 * depends on the first, then it will get put on the pending list after the 163 * trigger event has already occurred and will be stuck there. 164 * 165 * The atomic 'deferred_trigger_count' is used to determine if a successful 166 * trigger has occurred in the midst of probing a driver. If the trigger count 167 * changes in the midst of a probe, then deferred processing should be triggered 168 * again. 169 */ 170 static void driver_deferred_probe_trigger(void) 171 { 172 if (!driver_deferred_probe_enable) 173 return; 174 175 /* 176 * A successful probe means that all the devices in the pending list 177 * should be triggered to be reprobed. Move all the deferred devices 178 * into the active list so they can be retried by the workqueue 179 */ 180 mutex_lock(&deferred_probe_mutex); 181 atomic_inc(&deferred_trigger_count); 182 list_splice_tail_init(&deferred_probe_pending_list, 183 &deferred_probe_active_list); 184 mutex_unlock(&deferred_probe_mutex); 185 186 /* 187 * Kick the re-probe thread. It may already be scheduled, but it is 188 * safe to kick it again. 189 */ 190 schedule_work(&deferred_probe_work); 191 } 192 193 /** 194 * device_block_probing() - Block/defere device's probes 195 * 196 * It will disable probing of devices and defer their probes instead. 197 */ 198 void device_block_probing(void) 199 { 200 defer_all_probes = true; 201 /* sync with probes to avoid races. */ 202 wait_for_device_probe(); 203 } 204 205 /** 206 * device_unblock_probing() - Unblock/enable device's probes 207 * 208 * It will restore normal behavior and trigger re-probing of deferred 209 * devices. 210 */ 211 void device_unblock_probing(void) 212 { 213 defer_all_probes = false; 214 driver_deferred_probe_trigger(); 215 } 216 217 /** 218 * deferred_probe_initcall() - Enable probing of deferred devices 219 * 220 * We don't want to get in the way when the bulk of drivers are getting probed. 221 * Instead, this initcall makes sure that deferred probing is delayed until 222 * late_initcall time. 223 */ 224 static int deferred_probe_initcall(void) 225 { 226 driver_deferred_probe_enable = true; 227 driver_deferred_probe_trigger(); 228 /* Sort as many dependencies as possible before exiting initcalls */ 229 flush_work(&deferred_probe_work); 230 return 0; 231 } 232 late_initcall(deferred_probe_initcall); 233 234 /** 235 * device_is_bound() - Check if device is bound to a driver 236 * @dev: device to check 237 * 238 * Returns true if passed device has already finished probing successfully 239 * against a driver. 240 * 241 * This function must be called with the device lock held. 242 */ 243 bool device_is_bound(struct device *dev) 244 { 245 return dev->p && klist_node_attached(&dev->p->knode_driver); 246 } 247 248 static void driver_bound(struct device *dev) 249 { 250 if (device_is_bound(dev)) { 251 printk(KERN_WARNING "%s: device %s already bound\n", 252 __func__, kobject_name(&dev->kobj)); 253 return; 254 } 255 256 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name, 257 __func__, dev_name(dev)); 258 259 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices); 260 device_links_driver_bound(dev); 261 262 device_pm_check_callbacks(dev); 263 264 /* 265 * Make sure the device is no longer in one of the deferred lists and 266 * kick off retrying all pending devices 267 */ 268 driver_deferred_probe_del(dev); 269 driver_deferred_probe_trigger(); 270 271 if (dev->bus) 272 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 273 BUS_NOTIFY_BOUND_DRIVER, dev); 274 } 275 276 static int driver_sysfs_add(struct device *dev) 277 { 278 int ret; 279 280 if (dev->bus) 281 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 282 BUS_NOTIFY_BIND_DRIVER, dev); 283 284 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj, 285 kobject_name(&dev->kobj)); 286 if (ret == 0) { 287 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj, 288 "driver"); 289 if (ret) 290 sysfs_remove_link(&dev->driver->p->kobj, 291 kobject_name(&dev->kobj)); 292 } 293 return ret; 294 } 295 296 static void driver_sysfs_remove(struct device *dev) 297 { 298 struct device_driver *drv = dev->driver; 299 300 if (drv) { 301 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj)); 302 sysfs_remove_link(&dev->kobj, "driver"); 303 } 304 } 305 306 /** 307 * device_bind_driver - bind a driver to one device. 308 * @dev: device. 309 * 310 * Allow manual attachment of a driver to a device. 311 * Caller must have already set @dev->driver. 312 * 313 * Note that this does not modify the bus reference count 314 * nor take the bus's rwsem. Please verify those are accounted 315 * for before calling this. (It is ok to call with no other effort 316 * from a driver's probe() method.) 317 * 318 * This function must be called with the device lock held. 319 */ 320 int device_bind_driver(struct device *dev) 321 { 322 int ret; 323 324 ret = driver_sysfs_add(dev); 325 if (!ret) 326 driver_bound(dev); 327 else if (dev->bus) 328 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 329 BUS_NOTIFY_DRIVER_NOT_BOUND, dev); 330 return ret; 331 } 332 EXPORT_SYMBOL_GPL(device_bind_driver); 333 334 static atomic_t probe_count = ATOMIC_INIT(0); 335 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); 336 337 static int really_probe(struct device *dev, struct device_driver *drv) 338 { 339 int ret = -EPROBE_DEFER; 340 int local_trigger_count = atomic_read(&deferred_trigger_count); 341 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) && 342 !drv->suppress_bind_attrs; 343 344 if (defer_all_probes) { 345 /* 346 * Value of defer_all_probes can be set only by 347 * device_defer_all_probes_enable() which, in turn, will call 348 * wait_for_device_probe() right after that to avoid any races. 349 */ 350 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name); 351 driver_deferred_probe_add(dev); 352 return ret; 353 } 354 355 ret = device_links_check_suppliers(dev); 356 if (ret) 357 return ret; 358 359 atomic_inc(&probe_count); 360 pr_debug("bus: '%s': %s: probing driver %s with device %s\n", 361 drv->bus->name, __func__, drv->name, dev_name(dev)); 362 WARN_ON(!list_empty(&dev->devres_head)); 363 364 re_probe: 365 dev->driver = drv; 366 367 /* If using pinctrl, bind pins now before probing */ 368 ret = pinctrl_bind_pins(dev); 369 if (ret) 370 goto pinctrl_bind_failed; 371 372 if (driver_sysfs_add(dev)) { 373 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n", 374 __func__, dev_name(dev)); 375 goto probe_failed; 376 } 377 378 if (dev->pm_domain && dev->pm_domain->activate) { 379 ret = dev->pm_domain->activate(dev); 380 if (ret) 381 goto probe_failed; 382 } 383 384 /* 385 * Ensure devices are listed in devices_kset in correct order 386 * It's important to move Dev to the end of devices_kset before 387 * calling .probe, because it could be recursive and parent Dev 388 * should always go first 389 */ 390 devices_kset_move_last(dev); 391 392 if (dev->bus->probe) { 393 ret = dev->bus->probe(dev); 394 if (ret) 395 goto probe_failed; 396 } else if (drv->probe) { 397 ret = drv->probe(dev); 398 if (ret) 399 goto probe_failed; 400 } 401 402 if (test_remove) { 403 test_remove = false; 404 405 if (dev->bus->remove) 406 dev->bus->remove(dev); 407 else if (drv->remove) 408 drv->remove(dev); 409 410 devres_release_all(dev); 411 driver_sysfs_remove(dev); 412 dev->driver = NULL; 413 dev_set_drvdata(dev, NULL); 414 if (dev->pm_domain && dev->pm_domain->dismiss) 415 dev->pm_domain->dismiss(dev); 416 pm_runtime_reinit(dev); 417 418 goto re_probe; 419 } 420 421 pinctrl_init_done(dev); 422 423 if (dev->pm_domain && dev->pm_domain->sync) 424 dev->pm_domain->sync(dev); 425 426 driver_bound(dev); 427 ret = 1; 428 pr_debug("bus: '%s': %s: bound device %s to driver %s\n", 429 drv->bus->name, __func__, dev_name(dev), drv->name); 430 goto done; 431 432 probe_failed: 433 if (dev->bus) 434 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 435 BUS_NOTIFY_DRIVER_NOT_BOUND, dev); 436 pinctrl_bind_failed: 437 device_links_no_driver(dev); 438 devres_release_all(dev); 439 driver_sysfs_remove(dev); 440 dev->driver = NULL; 441 dev_set_drvdata(dev, NULL); 442 if (dev->pm_domain && dev->pm_domain->dismiss) 443 dev->pm_domain->dismiss(dev); 444 pm_runtime_reinit(dev); 445 446 switch (ret) { 447 case -EPROBE_DEFER: 448 /* Driver requested deferred probing */ 449 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name); 450 driver_deferred_probe_add(dev); 451 /* Did a trigger occur while probing? Need to re-trigger if yes */ 452 if (local_trigger_count != atomic_read(&deferred_trigger_count)) 453 driver_deferred_probe_trigger(); 454 break; 455 case -ENODEV: 456 case -ENXIO: 457 pr_debug("%s: probe of %s rejects match %d\n", 458 drv->name, dev_name(dev), ret); 459 break; 460 default: 461 /* driver matched but the probe failed */ 462 printk(KERN_WARNING 463 "%s: probe of %s failed with error %d\n", 464 drv->name, dev_name(dev), ret); 465 } 466 /* 467 * Ignore errors returned by ->probe so that the next driver can try 468 * its luck. 469 */ 470 ret = 0; 471 done: 472 atomic_dec(&probe_count); 473 wake_up(&probe_waitqueue); 474 return ret; 475 } 476 477 /** 478 * driver_probe_done 479 * Determine if the probe sequence is finished or not. 480 * 481 * Should somehow figure out how to use a semaphore, not an atomic variable... 482 */ 483 int driver_probe_done(void) 484 { 485 pr_debug("%s: probe_count = %d\n", __func__, 486 atomic_read(&probe_count)); 487 if (atomic_read(&probe_count)) 488 return -EBUSY; 489 return 0; 490 } 491 492 /** 493 * wait_for_device_probe 494 * Wait for device probing to be completed. 495 */ 496 void wait_for_device_probe(void) 497 { 498 /* wait for the deferred probe workqueue to finish */ 499 flush_work(&deferred_probe_work); 500 501 /* wait for the known devices to complete their probing */ 502 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); 503 async_synchronize_full(); 504 } 505 EXPORT_SYMBOL_GPL(wait_for_device_probe); 506 507 /** 508 * driver_probe_device - attempt to bind device & driver together 509 * @drv: driver to bind a device to 510 * @dev: device to try to bind to the driver 511 * 512 * This function returns -ENODEV if the device is not registered, 513 * 1 if the device is bound successfully and 0 otherwise. 514 * 515 * This function must be called with @dev lock held. When called for a 516 * USB interface, @dev->parent lock must be held as well. 517 * 518 * If the device has a parent, runtime-resume the parent before driver probing. 519 */ 520 int driver_probe_device(struct device_driver *drv, struct device *dev) 521 { 522 int ret = 0; 523 524 if (!device_is_registered(dev)) 525 return -ENODEV; 526 527 pr_debug("bus: '%s': %s: matched device %s with driver %s\n", 528 drv->bus->name, __func__, dev_name(dev), drv->name); 529 530 pm_runtime_get_suppliers(dev); 531 if (dev->parent) 532 pm_runtime_get_sync(dev->parent); 533 534 pm_runtime_barrier(dev); 535 ret = really_probe(dev, drv); 536 pm_request_idle(dev); 537 538 if (dev->parent) 539 pm_runtime_put(dev->parent); 540 541 pm_runtime_put_suppliers(dev); 542 return ret; 543 } 544 545 bool driver_allows_async_probing(struct device_driver *drv) 546 { 547 switch (drv->probe_type) { 548 case PROBE_PREFER_ASYNCHRONOUS: 549 return true; 550 551 case PROBE_FORCE_SYNCHRONOUS: 552 return false; 553 554 default: 555 if (module_requested_async_probing(drv->owner)) 556 return true; 557 558 return false; 559 } 560 } 561 562 struct device_attach_data { 563 struct device *dev; 564 565 /* 566 * Indicates whether we are are considering asynchronous probing or 567 * not. Only initial binding after device or driver registration 568 * (including deferral processing) may be done asynchronously, the 569 * rest is always synchronous, as we expect it is being done by 570 * request from userspace. 571 */ 572 bool check_async; 573 574 /* 575 * Indicates if we are binding synchronous or asynchronous drivers. 576 * When asynchronous probing is enabled we'll execute 2 passes 577 * over drivers: first pass doing synchronous probing and second 578 * doing asynchronous probing (if synchronous did not succeed - 579 * most likely because there was no driver requiring synchronous 580 * probing - and we found asynchronous driver during first pass). 581 * The 2 passes are done because we can't shoot asynchronous 582 * probe for given device and driver from bus_for_each_drv() since 583 * driver pointer is not guaranteed to stay valid once 584 * bus_for_each_drv() iterates to the next driver on the bus. 585 */ 586 bool want_async; 587 588 /* 589 * We'll set have_async to 'true' if, while scanning for matching 590 * driver, we'll encounter one that requests asynchronous probing. 591 */ 592 bool have_async; 593 }; 594 595 static int __device_attach_driver(struct device_driver *drv, void *_data) 596 { 597 struct device_attach_data *data = _data; 598 struct device *dev = data->dev; 599 bool async_allowed; 600 int ret; 601 602 /* 603 * Check if device has already been claimed. This may 604 * happen with driver loading, device discovery/registration, 605 * and deferred probe processing happens all at once with 606 * multiple threads. 607 */ 608 if (dev->driver) 609 return -EBUSY; 610 611 ret = driver_match_device(drv, dev); 612 if (ret == 0) { 613 /* no match */ 614 return 0; 615 } else if (ret == -EPROBE_DEFER) { 616 dev_dbg(dev, "Device match requests probe deferral\n"); 617 driver_deferred_probe_add(dev); 618 } else if (ret < 0) { 619 dev_dbg(dev, "Bus failed to match device: %d", ret); 620 return ret; 621 } /* ret > 0 means positive match */ 622 623 async_allowed = driver_allows_async_probing(drv); 624 625 if (async_allowed) 626 data->have_async = true; 627 628 if (data->check_async && async_allowed != data->want_async) 629 return 0; 630 631 return driver_probe_device(drv, dev); 632 } 633 634 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) 635 { 636 struct device *dev = _dev; 637 struct device_attach_data data = { 638 .dev = dev, 639 .check_async = true, 640 .want_async = true, 641 }; 642 643 device_lock(dev); 644 645 if (dev->parent) 646 pm_runtime_get_sync(dev->parent); 647 648 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver); 649 dev_dbg(dev, "async probe completed\n"); 650 651 pm_request_idle(dev); 652 653 if (dev->parent) 654 pm_runtime_put(dev->parent); 655 656 device_unlock(dev); 657 658 put_device(dev); 659 } 660 661 static int __device_attach(struct device *dev, bool allow_async) 662 { 663 int ret = 0; 664 665 device_lock(dev); 666 if (dev->driver) { 667 if (device_is_bound(dev)) { 668 ret = 1; 669 goto out_unlock; 670 } 671 ret = device_bind_driver(dev); 672 if (ret == 0) 673 ret = 1; 674 else { 675 dev->driver = NULL; 676 ret = 0; 677 } 678 } else { 679 struct device_attach_data data = { 680 .dev = dev, 681 .check_async = allow_async, 682 .want_async = false, 683 }; 684 685 if (dev->parent) 686 pm_runtime_get_sync(dev->parent); 687 688 ret = bus_for_each_drv(dev->bus, NULL, &data, 689 __device_attach_driver); 690 if (!ret && allow_async && data.have_async) { 691 /* 692 * If we could not find appropriate driver 693 * synchronously and we are allowed to do 694 * async probes and there are drivers that 695 * want to probe asynchronously, we'll 696 * try them. 697 */ 698 dev_dbg(dev, "scheduling asynchronous probe\n"); 699 get_device(dev); 700 async_schedule(__device_attach_async_helper, dev); 701 } else { 702 pm_request_idle(dev); 703 } 704 705 if (dev->parent) 706 pm_runtime_put(dev->parent); 707 } 708 out_unlock: 709 device_unlock(dev); 710 return ret; 711 } 712 713 /** 714 * device_attach - try to attach device to a driver. 715 * @dev: device. 716 * 717 * Walk the list of drivers that the bus has and call 718 * driver_probe_device() for each pair. If a compatible 719 * pair is found, break out and return. 720 * 721 * Returns 1 if the device was bound to a driver; 722 * 0 if no matching driver was found; 723 * -ENODEV if the device is not registered. 724 * 725 * When called for a USB interface, @dev->parent lock must be held. 726 */ 727 int device_attach(struct device *dev) 728 { 729 return __device_attach(dev, false); 730 } 731 EXPORT_SYMBOL_GPL(device_attach); 732 733 void device_initial_probe(struct device *dev) 734 { 735 __device_attach(dev, true); 736 } 737 738 static int __driver_attach(struct device *dev, void *data) 739 { 740 struct device_driver *drv = data; 741 int ret; 742 743 /* 744 * Lock device and try to bind to it. We drop the error 745 * here and always return 0, because we need to keep trying 746 * to bind to devices and some drivers will return an error 747 * simply if it didn't support the device. 748 * 749 * driver_probe_device() will spit a warning if there 750 * is an error. 751 */ 752 753 ret = driver_match_device(drv, dev); 754 if (ret == 0) { 755 /* no match */ 756 return 0; 757 } else if (ret == -EPROBE_DEFER) { 758 dev_dbg(dev, "Device match requests probe deferral\n"); 759 driver_deferred_probe_add(dev); 760 } else if (ret < 0) { 761 dev_dbg(dev, "Bus failed to match device: %d", ret); 762 return ret; 763 } /* ret > 0 means positive match */ 764 765 if (dev->parent) /* Needed for USB */ 766 device_lock(dev->parent); 767 device_lock(dev); 768 if (!dev->driver) 769 driver_probe_device(drv, dev); 770 device_unlock(dev); 771 if (dev->parent) 772 device_unlock(dev->parent); 773 774 return 0; 775 } 776 777 /** 778 * driver_attach - try to bind driver to devices. 779 * @drv: driver. 780 * 781 * Walk the list of devices that the bus has on it and try to 782 * match the driver with each one. If driver_probe_device() 783 * returns 0 and the @dev->driver is set, we've found a 784 * compatible pair. 785 */ 786 int driver_attach(struct device_driver *drv) 787 { 788 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); 789 } 790 EXPORT_SYMBOL_GPL(driver_attach); 791 792 /* 793 * __device_release_driver() must be called with @dev lock held. 794 * When called for a USB interface, @dev->parent lock must be held as well. 795 */ 796 static void __device_release_driver(struct device *dev, struct device *parent) 797 { 798 struct device_driver *drv; 799 800 drv = dev->driver; 801 if (drv) { 802 if (driver_allows_async_probing(drv)) 803 async_synchronize_full(); 804 805 while (device_links_busy(dev)) { 806 device_unlock(dev); 807 if (parent) 808 device_unlock(parent); 809 810 device_links_unbind_consumers(dev); 811 if (parent) 812 device_lock(parent); 813 814 device_lock(dev); 815 /* 816 * A concurrent invocation of the same function might 817 * have released the driver successfully while this one 818 * was waiting, so check for that. 819 */ 820 if (dev->driver != drv) 821 return; 822 } 823 824 pm_runtime_get_sync(dev); 825 pm_runtime_clean_up_links(dev); 826 827 driver_sysfs_remove(dev); 828 829 if (dev->bus) 830 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 831 BUS_NOTIFY_UNBIND_DRIVER, 832 dev); 833 834 pm_runtime_put_sync(dev); 835 836 if (dev->bus && dev->bus->remove) 837 dev->bus->remove(dev); 838 else if (drv->remove) 839 drv->remove(dev); 840 841 device_links_driver_cleanup(dev); 842 devres_release_all(dev); 843 dev->driver = NULL; 844 dev_set_drvdata(dev, NULL); 845 if (dev->pm_domain && dev->pm_domain->dismiss) 846 dev->pm_domain->dismiss(dev); 847 pm_runtime_reinit(dev); 848 849 klist_remove(&dev->p->knode_driver); 850 device_pm_check_callbacks(dev); 851 if (dev->bus) 852 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 853 BUS_NOTIFY_UNBOUND_DRIVER, 854 dev); 855 } 856 } 857 858 void device_release_driver_internal(struct device *dev, 859 struct device_driver *drv, 860 struct device *parent) 861 { 862 if (parent) 863 device_lock(parent); 864 865 device_lock(dev); 866 if (!drv || drv == dev->driver) 867 __device_release_driver(dev, parent); 868 869 device_unlock(dev); 870 if (parent) 871 device_unlock(parent); 872 } 873 874 /** 875 * device_release_driver - manually detach device from driver. 876 * @dev: device. 877 * 878 * Manually detach device from driver. 879 * When called for a USB interface, @dev->parent lock must be held. 880 * 881 * If this function is to be called with @dev->parent lock held, ensure that 882 * the device's consumers are unbound in advance or that their locks can be 883 * acquired under the @dev->parent lock. 884 */ 885 void device_release_driver(struct device *dev) 886 { 887 /* 888 * If anyone calls device_release_driver() recursively from 889 * within their ->remove callback for the same device, they 890 * will deadlock right here. 891 */ 892 device_release_driver_internal(dev, NULL, NULL); 893 } 894 EXPORT_SYMBOL_GPL(device_release_driver); 895 896 /** 897 * driver_detach - detach driver from all devices it controls. 898 * @drv: driver. 899 */ 900 void driver_detach(struct device_driver *drv) 901 { 902 struct device_private *dev_prv; 903 struct device *dev; 904 905 for (;;) { 906 spin_lock(&drv->p->klist_devices.k_lock); 907 if (list_empty(&drv->p->klist_devices.k_list)) { 908 spin_unlock(&drv->p->klist_devices.k_lock); 909 break; 910 } 911 dev_prv = list_entry(drv->p->klist_devices.k_list.prev, 912 struct device_private, 913 knode_driver.n_node); 914 dev = dev_prv->device; 915 get_device(dev); 916 spin_unlock(&drv->p->klist_devices.k_lock); 917 device_release_driver_internal(dev, drv, dev->parent); 918 put_device(dev); 919 } 920 } 921