1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * drivers/base/dd.c - The core device/driver interactions. 4 * 5 * This file contains the (sometimes tricky) code that controls the 6 * interactions between devices and drivers, which primarily includes 7 * driver binding and unbinding. 8 * 9 * All of this code used to exist in drivers/base/bus.c, but was 10 * relocated to here in the name of compartmentalization (since it wasn't 11 * strictly code just for the 'struct bus_type'. 12 * 13 * Copyright (c) 2002-5 Patrick Mochel 14 * Copyright (c) 2002-3 Open Source Development Labs 15 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de> 16 * Copyright (c) 2007-2009 Novell Inc. 17 */ 18 19 #include <linux/debugfs.h> 20 #include <linux/device.h> 21 #include <linux/delay.h> 22 #include <linux/dma-mapping.h> 23 #include <linux/init.h> 24 #include <linux/module.h> 25 #include <linux/kthread.h> 26 #include <linux/wait.h> 27 #include <linux/async.h> 28 #include <linux/pm_runtime.h> 29 #include <linux/pinctrl/devinfo.h> 30 31 #include "base.h" 32 #include "power/power.h" 33 34 /* 35 * Deferred Probe infrastructure. 36 * 37 * Sometimes driver probe order matters, but the kernel doesn't always have 38 * dependency information which means some drivers will get probed before a 39 * resource it depends on is available. For example, an SDHCI driver may 40 * first need a GPIO line from an i2c GPIO controller before it can be 41 * initialized. If a required resource is not available yet, a driver can 42 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook 43 * 44 * Deferred probe maintains two lists of devices, a pending list and an active 45 * list. A driver returning -EPROBE_DEFER causes the device to be added to the 46 * pending list. A successful driver probe will trigger moving all devices 47 * from the pending to the active list so that the workqueue will eventually 48 * retry them. 49 * 50 * The deferred_probe_mutex must be held any time the deferred_probe_*_list 51 * of the (struct device*)->p->deferred_probe pointers are manipulated 52 */ 53 static DEFINE_MUTEX(deferred_probe_mutex); 54 static LIST_HEAD(deferred_probe_pending_list); 55 static LIST_HEAD(deferred_probe_active_list); 56 static atomic_t deferred_trigger_count = ATOMIC_INIT(0); 57 static struct dentry *deferred_devices; 58 static bool initcalls_done; 59 60 /* Save the async probe drivers' name from kernel cmdline */ 61 #define ASYNC_DRV_NAMES_MAX_LEN 256 62 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN]; 63 64 /* 65 * In some cases, like suspend to RAM or hibernation, It might be reasonable 66 * to prohibit probing of devices as it could be unsafe. 67 * Once defer_all_probes is true all drivers probes will be forcibly deferred. 68 */ 69 static bool defer_all_probes; 70 71 /* 72 * deferred_probe_work_func() - Retry probing devices in the active list. 73 */ 74 static void deferred_probe_work_func(struct work_struct *work) 75 { 76 struct device *dev; 77 struct device_private *private; 78 /* 79 * This block processes every device in the deferred 'active' list. 80 * Each device is removed from the active list and passed to 81 * bus_probe_device() to re-attempt the probe. The loop continues 82 * until every device in the active list is removed and retried. 83 * 84 * Note: Once the device is removed from the list and the mutex is 85 * released, it is possible for the device get freed by another thread 86 * and cause a illegal pointer dereference. This code uses 87 * get/put_device() to ensure the device structure cannot disappear 88 * from under our feet. 89 */ 90 mutex_lock(&deferred_probe_mutex); 91 while (!list_empty(&deferred_probe_active_list)) { 92 private = list_first_entry(&deferred_probe_active_list, 93 typeof(*dev->p), deferred_probe); 94 dev = private->device; 95 list_del_init(&private->deferred_probe); 96 97 get_device(dev); 98 99 /* 100 * Drop the mutex while probing each device; the probe path may 101 * manipulate the deferred list 102 */ 103 mutex_unlock(&deferred_probe_mutex); 104 105 /* 106 * Force the device to the end of the dpm_list since 107 * the PM code assumes that the order we add things to 108 * the list is a good order for suspend but deferred 109 * probe makes that very unsafe. 110 */ 111 device_pm_move_to_tail(dev); 112 113 dev_dbg(dev, "Retrying from deferred list\n"); 114 bus_probe_device(dev); 115 mutex_lock(&deferred_probe_mutex); 116 117 put_device(dev); 118 } 119 mutex_unlock(&deferred_probe_mutex); 120 } 121 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func); 122 123 void driver_deferred_probe_add(struct device *dev) 124 { 125 mutex_lock(&deferred_probe_mutex); 126 if (list_empty(&dev->p->deferred_probe)) { 127 dev_dbg(dev, "Added to deferred list\n"); 128 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list); 129 } 130 mutex_unlock(&deferred_probe_mutex); 131 } 132 133 void driver_deferred_probe_del(struct device *dev) 134 { 135 mutex_lock(&deferred_probe_mutex); 136 if (!list_empty(&dev->p->deferred_probe)) { 137 dev_dbg(dev, "Removed from deferred list\n"); 138 list_del_init(&dev->p->deferred_probe); 139 } 140 mutex_unlock(&deferred_probe_mutex); 141 } 142 143 static bool driver_deferred_probe_enable = false; 144 /** 145 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices 146 * 147 * This functions moves all devices from the pending list to the active 148 * list and schedules the deferred probe workqueue to process them. It 149 * should be called anytime a driver is successfully bound to a device. 150 * 151 * Note, there is a race condition in multi-threaded probe. In the case where 152 * more than one device is probing at the same time, it is possible for one 153 * probe to complete successfully while another is about to defer. If the second 154 * depends on the first, then it will get put on the pending list after the 155 * trigger event has already occurred and will be stuck there. 156 * 157 * The atomic 'deferred_trigger_count' is used to determine if a successful 158 * trigger has occurred in the midst of probing a driver. If the trigger count 159 * changes in the midst of a probe, then deferred processing should be triggered 160 * again. 161 */ 162 static void driver_deferred_probe_trigger(void) 163 { 164 if (!driver_deferred_probe_enable) 165 return; 166 167 driver_deferred_probe_force_trigger(); 168 } 169 170 void driver_deferred_probe_force_trigger(void) 171 { 172 /* 173 * A successful probe means that all the devices in the pending list 174 * should be triggered to be reprobed. Move all the deferred devices 175 * into the active list so they can be retried by the workqueue 176 */ 177 mutex_lock(&deferred_probe_mutex); 178 atomic_inc(&deferred_trigger_count); 179 list_splice_tail_init(&deferred_probe_pending_list, 180 &deferred_probe_active_list); 181 mutex_unlock(&deferred_probe_mutex); 182 183 /* 184 * Kick the re-probe thread. It may already be scheduled, but it is 185 * safe to kick it again. 186 */ 187 schedule_work(&deferred_probe_work); 188 } 189 190 /** 191 * device_block_probing() - Block/defer device's probes 192 * 193 * It will disable probing of devices and defer their probes instead. 194 */ 195 void device_block_probing(void) 196 { 197 defer_all_probes = true; 198 /* sync with probes to avoid races. */ 199 wait_for_device_probe(); 200 } 201 202 /** 203 * device_unblock_probing() - Unblock/enable device's probes 204 * 205 * It will restore normal behavior and trigger re-probing of deferred 206 * devices. 207 */ 208 void device_unblock_probing(void) 209 { 210 defer_all_probes = false; 211 driver_deferred_probe_trigger(); 212 } 213 214 /* 215 * deferred_devs_show() - Show the devices in the deferred probe pending list. 216 */ 217 static int deferred_devs_show(struct seq_file *s, void *data) 218 { 219 struct device_private *curr; 220 221 mutex_lock(&deferred_probe_mutex); 222 223 list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe) 224 seq_printf(s, "%s\n", dev_name(curr->device)); 225 226 mutex_unlock(&deferred_probe_mutex); 227 228 return 0; 229 } 230 DEFINE_SHOW_ATTRIBUTE(deferred_devs); 231 232 int driver_deferred_probe_timeout; 233 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout); 234 static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue); 235 236 static int __init deferred_probe_timeout_setup(char *str) 237 { 238 int timeout; 239 240 if (!kstrtoint(str, 10, &timeout)) 241 driver_deferred_probe_timeout = timeout; 242 return 1; 243 } 244 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup); 245 246 /** 247 * driver_deferred_probe_check_state() - Check deferred probe state 248 * @dev: device to check 249 * 250 * Return: 251 * -ENODEV if initcalls have completed and modules are disabled. 252 * -ETIMEDOUT if the deferred probe timeout was set and has expired 253 * and modules are enabled. 254 * -EPROBE_DEFER in other cases. 255 * 256 * Drivers or subsystems can opt-in to calling this function instead of directly 257 * returning -EPROBE_DEFER. 258 */ 259 int driver_deferred_probe_check_state(struct device *dev) 260 { 261 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) { 262 dev_warn(dev, "ignoring dependency for device, assuming no driver\n"); 263 return -ENODEV; 264 } 265 266 if (!driver_deferred_probe_timeout && initcalls_done) { 267 dev_warn(dev, "deferred probe timeout, ignoring dependency\n"); 268 return -ETIMEDOUT; 269 } 270 271 return -EPROBE_DEFER; 272 } 273 274 static void deferred_probe_timeout_work_func(struct work_struct *work) 275 { 276 struct device_private *private, *p; 277 278 driver_deferred_probe_timeout = 0; 279 driver_deferred_probe_trigger(); 280 flush_work(&deferred_probe_work); 281 282 list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe) 283 dev_info(private->device, "deferred probe pending\n"); 284 wake_up(&probe_timeout_waitqueue); 285 } 286 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func); 287 288 /** 289 * deferred_probe_initcall() - Enable probing of deferred devices 290 * 291 * We don't want to get in the way when the bulk of drivers are getting probed. 292 * Instead, this initcall makes sure that deferred probing is delayed until 293 * late_initcall time. 294 */ 295 static int deferred_probe_initcall(void) 296 { 297 deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL, 298 NULL, &deferred_devs_fops); 299 300 driver_deferred_probe_enable = true; 301 driver_deferred_probe_trigger(); 302 /* Sort as many dependencies as possible before exiting initcalls */ 303 flush_work(&deferred_probe_work); 304 initcalls_done = true; 305 306 /* 307 * Trigger deferred probe again, this time we won't defer anything 308 * that is optional 309 */ 310 driver_deferred_probe_trigger(); 311 flush_work(&deferred_probe_work); 312 313 if (driver_deferred_probe_timeout > 0) { 314 schedule_delayed_work(&deferred_probe_timeout_work, 315 driver_deferred_probe_timeout * HZ); 316 } 317 return 0; 318 } 319 late_initcall(deferred_probe_initcall); 320 321 static void __exit deferred_probe_exit(void) 322 { 323 debugfs_remove_recursive(deferred_devices); 324 } 325 __exitcall(deferred_probe_exit); 326 327 /** 328 * device_is_bound() - Check if device is bound to a driver 329 * @dev: device to check 330 * 331 * Returns true if passed device has already finished probing successfully 332 * against a driver. 333 * 334 * This function must be called with the device lock held. 335 */ 336 bool device_is_bound(struct device *dev) 337 { 338 return dev->p && klist_node_attached(&dev->p->knode_driver); 339 } 340 341 static void driver_bound(struct device *dev) 342 { 343 if (device_is_bound(dev)) { 344 pr_warn("%s: device %s already bound\n", 345 __func__, kobject_name(&dev->kobj)); 346 return; 347 } 348 349 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name, 350 __func__, dev_name(dev)); 351 352 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices); 353 device_links_driver_bound(dev); 354 355 device_pm_check_callbacks(dev); 356 357 /* 358 * Make sure the device is no longer in one of the deferred lists and 359 * kick off retrying all pending devices 360 */ 361 driver_deferred_probe_del(dev); 362 driver_deferred_probe_trigger(); 363 364 if (dev->bus) 365 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 366 BUS_NOTIFY_BOUND_DRIVER, dev); 367 368 kobject_uevent(&dev->kobj, KOBJ_BIND); 369 } 370 371 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr, 372 const char *buf, size_t count) 373 { 374 device_lock(dev); 375 dev->driver->coredump(dev); 376 device_unlock(dev); 377 378 return count; 379 } 380 static DEVICE_ATTR_WO(coredump); 381 382 static int driver_sysfs_add(struct device *dev) 383 { 384 int ret; 385 386 if (dev->bus) 387 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 388 BUS_NOTIFY_BIND_DRIVER, dev); 389 390 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj, 391 kobject_name(&dev->kobj)); 392 if (ret) 393 goto fail; 394 395 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj, 396 "driver"); 397 if (ret) 398 goto rm_dev; 399 400 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump || 401 !device_create_file(dev, &dev_attr_coredump)) 402 return 0; 403 404 sysfs_remove_link(&dev->kobj, "driver"); 405 406 rm_dev: 407 sysfs_remove_link(&dev->driver->p->kobj, 408 kobject_name(&dev->kobj)); 409 410 fail: 411 return ret; 412 } 413 414 static void driver_sysfs_remove(struct device *dev) 415 { 416 struct device_driver *drv = dev->driver; 417 418 if (drv) { 419 if (drv->coredump) 420 device_remove_file(dev, &dev_attr_coredump); 421 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj)); 422 sysfs_remove_link(&dev->kobj, "driver"); 423 } 424 } 425 426 /** 427 * device_bind_driver - bind a driver to one device. 428 * @dev: device. 429 * 430 * Allow manual attachment of a driver to a device. 431 * Caller must have already set @dev->driver. 432 * 433 * Note that this does not modify the bus reference count 434 * nor take the bus's rwsem. Please verify those are accounted 435 * for before calling this. (It is ok to call with no other effort 436 * from a driver's probe() method.) 437 * 438 * This function must be called with the device lock held. 439 */ 440 int device_bind_driver(struct device *dev) 441 { 442 int ret; 443 444 ret = driver_sysfs_add(dev); 445 if (!ret) 446 driver_bound(dev); 447 else if (dev->bus) 448 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 449 BUS_NOTIFY_DRIVER_NOT_BOUND, dev); 450 return ret; 451 } 452 EXPORT_SYMBOL_GPL(device_bind_driver); 453 454 static atomic_t probe_count = ATOMIC_INIT(0); 455 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); 456 457 static void driver_deferred_probe_add_trigger(struct device *dev, 458 int local_trigger_count) 459 { 460 driver_deferred_probe_add(dev); 461 /* Did a trigger occur while probing? Need to re-trigger if yes */ 462 if (local_trigger_count != atomic_read(&deferred_trigger_count)) 463 driver_deferred_probe_trigger(); 464 } 465 466 static int really_probe(struct device *dev, struct device_driver *drv) 467 { 468 int ret = -EPROBE_DEFER; 469 int local_trigger_count = atomic_read(&deferred_trigger_count); 470 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) && 471 !drv->suppress_bind_attrs; 472 473 if (defer_all_probes) { 474 /* 475 * Value of defer_all_probes can be set only by 476 * device_block_probing() which, in turn, will call 477 * wait_for_device_probe() right after that to avoid any races. 478 */ 479 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name); 480 driver_deferred_probe_add(dev); 481 return ret; 482 } 483 484 ret = device_links_check_suppliers(dev); 485 if (ret == -EPROBE_DEFER) 486 driver_deferred_probe_add_trigger(dev, local_trigger_count); 487 if (ret) 488 return ret; 489 490 atomic_inc(&probe_count); 491 pr_debug("bus: '%s': %s: probing driver %s with device %s\n", 492 drv->bus->name, __func__, drv->name, dev_name(dev)); 493 if (!list_empty(&dev->devres_head)) { 494 dev_crit(dev, "Resources present before probing\n"); 495 return -EBUSY; 496 } 497 498 re_probe: 499 dev->driver = drv; 500 501 /* If using pinctrl, bind pins now before probing */ 502 ret = pinctrl_bind_pins(dev); 503 if (ret) 504 goto pinctrl_bind_failed; 505 506 if (dev->bus->dma_configure) { 507 ret = dev->bus->dma_configure(dev); 508 if (ret) 509 goto probe_failed; 510 } 511 512 if (driver_sysfs_add(dev)) { 513 pr_err("%s: driver_sysfs_add(%s) failed\n", 514 __func__, dev_name(dev)); 515 goto probe_failed; 516 } 517 518 if (dev->pm_domain && dev->pm_domain->activate) { 519 ret = dev->pm_domain->activate(dev); 520 if (ret) 521 goto probe_failed; 522 } 523 524 if (dev->bus->probe) { 525 ret = dev->bus->probe(dev); 526 if (ret) 527 goto probe_failed; 528 } else if (drv->probe) { 529 ret = drv->probe(dev); 530 if (ret) 531 goto probe_failed; 532 } 533 534 if (device_add_groups(dev, drv->dev_groups)) { 535 dev_err(dev, "device_add_groups() failed\n"); 536 goto dev_groups_failed; 537 } 538 539 if (test_remove) { 540 test_remove = false; 541 542 device_remove_groups(dev, drv->dev_groups); 543 544 if (dev->bus->remove) 545 dev->bus->remove(dev); 546 else if (drv->remove) 547 drv->remove(dev); 548 549 devres_release_all(dev); 550 driver_sysfs_remove(dev); 551 dev->driver = NULL; 552 dev_set_drvdata(dev, NULL); 553 if (dev->pm_domain && dev->pm_domain->dismiss) 554 dev->pm_domain->dismiss(dev); 555 pm_runtime_reinit(dev); 556 557 goto re_probe; 558 } 559 560 pinctrl_init_done(dev); 561 562 if (dev->pm_domain && dev->pm_domain->sync) 563 dev->pm_domain->sync(dev); 564 565 driver_bound(dev); 566 ret = 1; 567 pr_debug("bus: '%s': %s: bound device %s to driver %s\n", 568 drv->bus->name, __func__, dev_name(dev), drv->name); 569 goto done; 570 571 dev_groups_failed: 572 if (dev->bus->remove) 573 dev->bus->remove(dev); 574 else if (drv->remove) 575 drv->remove(dev); 576 probe_failed: 577 if (dev->bus) 578 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 579 BUS_NOTIFY_DRIVER_NOT_BOUND, dev); 580 pinctrl_bind_failed: 581 device_links_no_driver(dev); 582 devres_release_all(dev); 583 arch_teardown_dma_ops(dev); 584 driver_sysfs_remove(dev); 585 dev->driver = NULL; 586 dev_set_drvdata(dev, NULL); 587 if (dev->pm_domain && dev->pm_domain->dismiss) 588 dev->pm_domain->dismiss(dev); 589 pm_runtime_reinit(dev); 590 dev_pm_set_driver_flags(dev, 0); 591 592 switch (ret) { 593 case -EPROBE_DEFER: 594 /* Driver requested deferred probing */ 595 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name); 596 driver_deferred_probe_add_trigger(dev, local_trigger_count); 597 break; 598 case -ENODEV: 599 case -ENXIO: 600 pr_debug("%s: probe of %s rejects match %d\n", 601 drv->name, dev_name(dev), ret); 602 break; 603 default: 604 /* driver matched but the probe failed */ 605 pr_warn("%s: probe of %s failed with error %d\n", 606 drv->name, dev_name(dev), ret); 607 } 608 /* 609 * Ignore errors returned by ->probe so that the next driver can try 610 * its luck. 611 */ 612 ret = 0; 613 done: 614 atomic_dec(&probe_count); 615 wake_up(&probe_waitqueue); 616 return ret; 617 } 618 619 /* 620 * For initcall_debug, show the driver probe time. 621 */ 622 static int really_probe_debug(struct device *dev, struct device_driver *drv) 623 { 624 ktime_t calltime, delta, rettime; 625 int ret; 626 627 calltime = ktime_get(); 628 ret = really_probe(dev, drv); 629 rettime = ktime_get(); 630 delta = ktime_sub(rettime, calltime); 631 pr_debug("probe of %s returned %d after %lld usecs\n", 632 dev_name(dev), ret, (s64) ktime_to_us(delta)); 633 return ret; 634 } 635 636 /** 637 * driver_probe_done 638 * Determine if the probe sequence is finished or not. 639 * 640 * Should somehow figure out how to use a semaphore, not an atomic variable... 641 */ 642 int driver_probe_done(void) 643 { 644 int local_probe_count = atomic_read(&probe_count); 645 646 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count); 647 if (local_probe_count) 648 return -EBUSY; 649 return 0; 650 } 651 652 /** 653 * wait_for_device_probe 654 * Wait for device probing to be completed. 655 */ 656 void wait_for_device_probe(void) 657 { 658 /* wait for probe timeout */ 659 wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout); 660 661 /* wait for the deferred probe workqueue to finish */ 662 flush_work(&deferred_probe_work); 663 664 /* wait for the known devices to complete their probing */ 665 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); 666 async_synchronize_full(); 667 } 668 EXPORT_SYMBOL_GPL(wait_for_device_probe); 669 670 /** 671 * driver_probe_device - attempt to bind device & driver together 672 * @drv: driver to bind a device to 673 * @dev: device to try to bind to the driver 674 * 675 * This function returns -ENODEV if the device is not registered, 676 * 1 if the device is bound successfully and 0 otherwise. 677 * 678 * This function must be called with @dev lock held. When called for a 679 * USB interface, @dev->parent lock must be held as well. 680 * 681 * If the device has a parent, runtime-resume the parent before driver probing. 682 */ 683 int driver_probe_device(struct device_driver *drv, struct device *dev) 684 { 685 int ret = 0; 686 687 if (!device_is_registered(dev)) 688 return -ENODEV; 689 690 pr_debug("bus: '%s': %s: matched device %s with driver %s\n", 691 drv->bus->name, __func__, dev_name(dev), drv->name); 692 693 pm_runtime_get_suppliers(dev); 694 if (dev->parent) 695 pm_runtime_get_sync(dev->parent); 696 697 pm_runtime_barrier(dev); 698 if (initcall_debug) 699 ret = really_probe_debug(dev, drv); 700 else 701 ret = really_probe(dev, drv); 702 pm_request_idle(dev); 703 704 if (dev->parent) 705 pm_runtime_put(dev->parent); 706 707 pm_runtime_put_suppliers(dev); 708 return ret; 709 } 710 711 static inline bool cmdline_requested_async_probing(const char *drv_name) 712 { 713 return parse_option_str(async_probe_drv_names, drv_name); 714 } 715 716 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */ 717 static int __init save_async_options(char *buf) 718 { 719 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN) 720 pr_warn("Too long list of driver names for 'driver_async_probe'!\n"); 721 722 strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN); 723 return 0; 724 } 725 __setup("driver_async_probe=", save_async_options); 726 727 bool driver_allows_async_probing(struct device_driver *drv) 728 { 729 switch (drv->probe_type) { 730 case PROBE_PREFER_ASYNCHRONOUS: 731 return true; 732 733 case PROBE_FORCE_SYNCHRONOUS: 734 return false; 735 736 default: 737 if (cmdline_requested_async_probing(drv->name)) 738 return true; 739 740 if (module_requested_async_probing(drv->owner)) 741 return true; 742 743 return false; 744 } 745 } 746 747 struct device_attach_data { 748 struct device *dev; 749 750 /* 751 * Indicates whether we are are considering asynchronous probing or 752 * not. Only initial binding after device or driver registration 753 * (including deferral processing) may be done asynchronously, the 754 * rest is always synchronous, as we expect it is being done by 755 * request from userspace. 756 */ 757 bool check_async; 758 759 /* 760 * Indicates if we are binding synchronous or asynchronous drivers. 761 * When asynchronous probing is enabled we'll execute 2 passes 762 * over drivers: first pass doing synchronous probing and second 763 * doing asynchronous probing (if synchronous did not succeed - 764 * most likely because there was no driver requiring synchronous 765 * probing - and we found asynchronous driver during first pass). 766 * The 2 passes are done because we can't shoot asynchronous 767 * probe for given device and driver from bus_for_each_drv() since 768 * driver pointer is not guaranteed to stay valid once 769 * bus_for_each_drv() iterates to the next driver on the bus. 770 */ 771 bool want_async; 772 773 /* 774 * We'll set have_async to 'true' if, while scanning for matching 775 * driver, we'll encounter one that requests asynchronous probing. 776 */ 777 bool have_async; 778 }; 779 780 static int __device_attach_driver(struct device_driver *drv, void *_data) 781 { 782 struct device_attach_data *data = _data; 783 struct device *dev = data->dev; 784 bool async_allowed; 785 int ret; 786 787 ret = driver_match_device(drv, dev); 788 if (ret == 0) { 789 /* no match */ 790 return 0; 791 } else if (ret == -EPROBE_DEFER) { 792 dev_dbg(dev, "Device match requests probe deferral\n"); 793 driver_deferred_probe_add(dev); 794 } else if (ret < 0) { 795 dev_dbg(dev, "Bus failed to match device: %d\n", ret); 796 return ret; 797 } /* ret > 0 means positive match */ 798 799 async_allowed = driver_allows_async_probing(drv); 800 801 if (async_allowed) 802 data->have_async = true; 803 804 if (data->check_async && async_allowed != data->want_async) 805 return 0; 806 807 return driver_probe_device(drv, dev); 808 } 809 810 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) 811 { 812 struct device *dev = _dev; 813 struct device_attach_data data = { 814 .dev = dev, 815 .check_async = true, 816 .want_async = true, 817 }; 818 819 device_lock(dev); 820 821 /* 822 * Check if device has already been removed or claimed. This may 823 * happen with driver loading, device discovery/registration, 824 * and deferred probe processing happens all at once with 825 * multiple threads. 826 */ 827 if (dev->p->dead || dev->driver) 828 goto out_unlock; 829 830 if (dev->parent) 831 pm_runtime_get_sync(dev->parent); 832 833 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver); 834 dev_dbg(dev, "async probe completed\n"); 835 836 pm_request_idle(dev); 837 838 if (dev->parent) 839 pm_runtime_put(dev->parent); 840 out_unlock: 841 device_unlock(dev); 842 843 put_device(dev); 844 } 845 846 static int __device_attach(struct device *dev, bool allow_async) 847 { 848 int ret = 0; 849 850 device_lock(dev); 851 if (dev->driver) { 852 if (device_is_bound(dev)) { 853 ret = 1; 854 goto out_unlock; 855 } 856 ret = device_bind_driver(dev); 857 if (ret == 0) 858 ret = 1; 859 else { 860 dev->driver = NULL; 861 ret = 0; 862 } 863 } else { 864 struct device_attach_data data = { 865 .dev = dev, 866 .check_async = allow_async, 867 .want_async = false, 868 }; 869 870 if (dev->parent) 871 pm_runtime_get_sync(dev->parent); 872 873 ret = bus_for_each_drv(dev->bus, NULL, &data, 874 __device_attach_driver); 875 if (!ret && allow_async && data.have_async) { 876 /* 877 * If we could not find appropriate driver 878 * synchronously and we are allowed to do 879 * async probes and there are drivers that 880 * want to probe asynchronously, we'll 881 * try them. 882 */ 883 dev_dbg(dev, "scheduling asynchronous probe\n"); 884 get_device(dev); 885 async_schedule_dev(__device_attach_async_helper, dev); 886 } else { 887 pm_request_idle(dev); 888 } 889 890 if (dev->parent) 891 pm_runtime_put(dev->parent); 892 } 893 out_unlock: 894 device_unlock(dev); 895 return ret; 896 } 897 898 /** 899 * device_attach - try to attach device to a driver. 900 * @dev: device. 901 * 902 * Walk the list of drivers that the bus has and call 903 * driver_probe_device() for each pair. If a compatible 904 * pair is found, break out and return. 905 * 906 * Returns 1 if the device was bound to a driver; 907 * 0 if no matching driver was found; 908 * -ENODEV if the device is not registered. 909 * 910 * When called for a USB interface, @dev->parent lock must be held. 911 */ 912 int device_attach(struct device *dev) 913 { 914 return __device_attach(dev, false); 915 } 916 EXPORT_SYMBOL_GPL(device_attach); 917 918 void device_initial_probe(struct device *dev) 919 { 920 __device_attach(dev, true); 921 } 922 923 /* 924 * __device_driver_lock - acquire locks needed to manipulate dev->drv 925 * @dev: Device we will update driver info for 926 * @parent: Parent device. Needed if the bus requires parent lock 927 * 928 * This function will take the required locks for manipulating dev->drv. 929 * Normally this will just be the @dev lock, but when called for a USB 930 * interface, @parent lock will be held as well. 931 */ 932 static void __device_driver_lock(struct device *dev, struct device *parent) 933 { 934 if (parent && dev->bus->need_parent_lock) 935 device_lock(parent); 936 device_lock(dev); 937 } 938 939 /* 940 * __device_driver_unlock - release locks needed to manipulate dev->drv 941 * @dev: Device we will update driver info for 942 * @parent: Parent device. Needed if the bus requires parent lock 943 * 944 * This function will release the required locks for manipulating dev->drv. 945 * Normally this will just be the the @dev lock, but when called for a 946 * USB interface, @parent lock will be released as well. 947 */ 948 static void __device_driver_unlock(struct device *dev, struct device *parent) 949 { 950 device_unlock(dev); 951 if (parent && dev->bus->need_parent_lock) 952 device_unlock(parent); 953 } 954 955 /** 956 * device_driver_attach - attach a specific driver to a specific device 957 * @drv: Driver to attach 958 * @dev: Device to attach it to 959 * 960 * Manually attach driver to a device. Will acquire both @dev lock and 961 * @dev->parent lock if needed. 962 */ 963 int device_driver_attach(struct device_driver *drv, struct device *dev) 964 { 965 int ret = 0; 966 967 __device_driver_lock(dev, dev->parent); 968 969 /* 970 * If device has been removed or someone has already successfully 971 * bound a driver before us just skip the driver probe call. 972 */ 973 if (!dev->p->dead && !dev->driver) 974 ret = driver_probe_device(drv, dev); 975 976 __device_driver_unlock(dev, dev->parent); 977 978 return ret; 979 } 980 981 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie) 982 { 983 struct device *dev = _dev; 984 struct device_driver *drv; 985 int ret = 0; 986 987 __device_driver_lock(dev, dev->parent); 988 989 drv = dev->p->async_driver; 990 991 /* 992 * If device has been removed or someone has already successfully 993 * bound a driver before us just skip the driver probe call. 994 */ 995 if (!dev->p->dead && !dev->driver) 996 ret = driver_probe_device(drv, dev); 997 998 __device_driver_unlock(dev, dev->parent); 999 1000 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret); 1001 1002 put_device(dev); 1003 } 1004 1005 static int __driver_attach(struct device *dev, void *data) 1006 { 1007 struct device_driver *drv = data; 1008 int ret; 1009 1010 /* 1011 * Lock device and try to bind to it. We drop the error 1012 * here and always return 0, because we need to keep trying 1013 * to bind to devices and some drivers will return an error 1014 * simply if it didn't support the device. 1015 * 1016 * driver_probe_device() will spit a warning if there 1017 * is an error. 1018 */ 1019 1020 ret = driver_match_device(drv, dev); 1021 if (ret == 0) { 1022 /* no match */ 1023 return 0; 1024 } else if (ret == -EPROBE_DEFER) { 1025 dev_dbg(dev, "Device match requests probe deferral\n"); 1026 driver_deferred_probe_add(dev); 1027 } else if (ret < 0) { 1028 dev_dbg(dev, "Bus failed to match device: %d\n", ret); 1029 return ret; 1030 } /* ret > 0 means positive match */ 1031 1032 if (driver_allows_async_probing(drv)) { 1033 /* 1034 * Instead of probing the device synchronously we will 1035 * probe it asynchronously to allow for more parallelism. 1036 * 1037 * We only take the device lock here in order to guarantee 1038 * that the dev->driver and async_driver fields are protected 1039 */ 1040 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name); 1041 device_lock(dev); 1042 if (!dev->driver) { 1043 get_device(dev); 1044 dev->p->async_driver = drv; 1045 async_schedule_dev(__driver_attach_async_helper, dev); 1046 } 1047 device_unlock(dev); 1048 return 0; 1049 } 1050 1051 device_driver_attach(drv, dev); 1052 1053 return 0; 1054 } 1055 1056 /** 1057 * driver_attach - try to bind driver to devices. 1058 * @drv: driver. 1059 * 1060 * Walk the list of devices that the bus has on it and try to 1061 * match the driver with each one. If driver_probe_device() 1062 * returns 0 and the @dev->driver is set, we've found a 1063 * compatible pair. 1064 */ 1065 int driver_attach(struct device_driver *drv) 1066 { 1067 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); 1068 } 1069 EXPORT_SYMBOL_GPL(driver_attach); 1070 1071 /* 1072 * __device_release_driver() must be called with @dev lock held. 1073 * When called for a USB interface, @dev->parent lock must be held as well. 1074 */ 1075 static void __device_release_driver(struct device *dev, struct device *parent) 1076 { 1077 struct device_driver *drv; 1078 1079 drv = dev->driver; 1080 if (drv) { 1081 while (device_links_busy(dev)) { 1082 __device_driver_unlock(dev, parent); 1083 1084 device_links_unbind_consumers(dev); 1085 1086 __device_driver_lock(dev, parent); 1087 /* 1088 * A concurrent invocation of the same function might 1089 * have released the driver successfully while this one 1090 * was waiting, so check for that. 1091 */ 1092 if (dev->driver != drv) 1093 return; 1094 } 1095 1096 pm_runtime_get_sync(dev); 1097 pm_runtime_clean_up_links(dev); 1098 1099 driver_sysfs_remove(dev); 1100 1101 if (dev->bus) 1102 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 1103 BUS_NOTIFY_UNBIND_DRIVER, 1104 dev); 1105 1106 pm_runtime_put_sync(dev); 1107 1108 device_remove_groups(dev, drv->dev_groups); 1109 1110 if (dev->bus && dev->bus->remove) 1111 dev->bus->remove(dev); 1112 else if (drv->remove) 1113 drv->remove(dev); 1114 1115 device_links_driver_cleanup(dev); 1116 1117 devres_release_all(dev); 1118 arch_teardown_dma_ops(dev); 1119 dev->driver = NULL; 1120 dev_set_drvdata(dev, NULL); 1121 if (dev->pm_domain && dev->pm_domain->dismiss) 1122 dev->pm_domain->dismiss(dev); 1123 pm_runtime_reinit(dev); 1124 dev_pm_set_driver_flags(dev, 0); 1125 1126 klist_remove(&dev->p->knode_driver); 1127 device_pm_check_callbacks(dev); 1128 if (dev->bus) 1129 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 1130 BUS_NOTIFY_UNBOUND_DRIVER, 1131 dev); 1132 1133 kobject_uevent(&dev->kobj, KOBJ_UNBIND); 1134 } 1135 } 1136 1137 void device_release_driver_internal(struct device *dev, 1138 struct device_driver *drv, 1139 struct device *parent) 1140 { 1141 __device_driver_lock(dev, parent); 1142 1143 if (!drv || drv == dev->driver) 1144 __device_release_driver(dev, parent); 1145 1146 __device_driver_unlock(dev, parent); 1147 } 1148 1149 /** 1150 * device_release_driver - manually detach device from driver. 1151 * @dev: device. 1152 * 1153 * Manually detach device from driver. 1154 * When called for a USB interface, @dev->parent lock must be held. 1155 * 1156 * If this function is to be called with @dev->parent lock held, ensure that 1157 * the device's consumers are unbound in advance or that their locks can be 1158 * acquired under the @dev->parent lock. 1159 */ 1160 void device_release_driver(struct device *dev) 1161 { 1162 /* 1163 * If anyone calls device_release_driver() recursively from 1164 * within their ->remove callback for the same device, they 1165 * will deadlock right here. 1166 */ 1167 device_release_driver_internal(dev, NULL, NULL); 1168 } 1169 EXPORT_SYMBOL_GPL(device_release_driver); 1170 1171 /** 1172 * device_driver_detach - detach driver from a specific device 1173 * @dev: device to detach driver from 1174 * 1175 * Detach driver from device. Will acquire both @dev lock and @dev->parent 1176 * lock if needed. 1177 */ 1178 void device_driver_detach(struct device *dev) 1179 { 1180 device_release_driver_internal(dev, NULL, dev->parent); 1181 } 1182 1183 /** 1184 * driver_detach - detach driver from all devices it controls. 1185 * @drv: driver. 1186 */ 1187 void driver_detach(struct device_driver *drv) 1188 { 1189 struct device_private *dev_prv; 1190 struct device *dev; 1191 1192 if (driver_allows_async_probing(drv)) 1193 async_synchronize_full(); 1194 1195 for (;;) { 1196 spin_lock(&drv->p->klist_devices.k_lock); 1197 if (list_empty(&drv->p->klist_devices.k_list)) { 1198 spin_unlock(&drv->p->klist_devices.k_lock); 1199 break; 1200 } 1201 dev_prv = list_last_entry(&drv->p->klist_devices.k_list, 1202 struct device_private, 1203 knode_driver.n_node); 1204 dev = dev_prv->device; 1205 get_device(dev); 1206 spin_unlock(&drv->p->klist_devices.k_lock); 1207 device_release_driver_internal(dev, drv, dev->parent); 1208 put_device(dev); 1209 } 1210 } 1211