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