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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/device.h>
20#include <linux/delay.h>
21#include <linux/dma-mapping.h>
22#include <linux/init.h>
23#include <linux/module.h>
24#include <linux/kthread.h>
25#include <linux/wait.h>
26#include <linux/async.h>
27#include <linux/pm_runtime.h>
28#include <linux/pinctrl/devinfo.h>
29
30#include "base.h"
31#include "power/power.h"
32
33/*
34 * Deferred Probe infrastructure.
35 *
36 * Sometimes driver probe order matters, but the kernel doesn't always have
37 * dependency information which means some drivers will get probed before a
38 * resource it depends on is available. For example, an SDHCI driver may
39 * first need a GPIO line from an i2c GPIO controller before it can be
40 * initialized. If a required resource is not available yet, a driver can
41 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
42 *
43 * Deferred probe maintains two lists of devices, a pending list and an active
44 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
45 * pending list. A successful driver probe will trigger moving all devices
46 * from the pending to the active list so that the workqueue will eventually
47 * retry them.
48 *
49 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
50 * of the (struct device*)->p->deferred_probe pointers are manipulated
51 */
52static DEFINE_MUTEX(deferred_probe_mutex);
53static LIST_HEAD(deferred_probe_pending_list);
54static LIST_HEAD(deferred_probe_active_list);
55static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
56static bool initcalls_done;
57
58/*
59 * In some cases, like suspend to RAM or hibernation, It might be reasonable
60 * to prohibit probing of devices as it could be unsafe.
61 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
62 */
63static bool defer_all_probes;
64
65/*
66 * For initcall_debug, show the deferred probes executed in late_initcall
67 * processing.
68 */
69static void deferred_probe_debug(struct device *dev)
70{
71 ktime_t calltime, delta, rettime;
72 unsigned long long duration;
73
74 printk(KERN_DEBUG "deferred probe %s @ %i\n", dev_name(dev),
75 task_pid_nr(current));
76 calltime = ktime_get();
77 bus_probe_device(dev);
78 rettime = ktime_get();
79 delta = ktime_sub(rettime, calltime);
80 duration = (unsigned long long) ktime_to_ns(delta) >> 10;
81 printk(KERN_DEBUG "deferred probe %s returned after %lld usecs\n",
82 dev_name(dev), duration);
83}
84
85/*
86 * deferred_probe_work_func() - Retry probing devices in the active list.
87 */
88static void deferred_probe_work_func(struct work_struct *work)
89{
90 struct device *dev;
91 struct device_private *private;
92 /*
93 * This block processes every device in the deferred 'active' list.
94 * Each device is removed from the active list and passed to
95 * bus_probe_device() to re-attempt the probe. The loop continues
96 * until every device in the active list is removed and retried.
97 *
98 * Note: Once the device is removed from the list and the mutex is
99 * released, it is possible for the device get freed by another thread
100 * and cause a illegal pointer dereference. This code uses
101 * get/put_device() to ensure the device structure cannot disappear
102 * from under our feet.
103 */
104 mutex_lock(&deferred_probe_mutex);
105 while (!list_empty(&deferred_probe_active_list)) {
106 private = list_first_entry(&deferred_probe_active_list,
107 typeof(*dev->p), deferred_probe);
108 dev = private->device;
109 list_del_init(&private->deferred_probe);
110
111 get_device(dev);
112
113 /*
114 * Drop the mutex while probing each device; the probe path may
115 * manipulate the deferred list
116 */
117 mutex_unlock(&deferred_probe_mutex);
118
119 /*
120 * Force the device to the end of the dpm_list since
121 * the PM code assumes that the order we add things to
122 * the list is a good order for suspend but deferred
123 * probe makes that very unsafe.
124 */
125 device_pm_lock();
126 device_pm_move_last(dev);
127 device_pm_unlock();
128
129 dev_dbg(dev, "Retrying from deferred list\n");
130 if (initcall_debug && !initcalls_done)
131 deferred_probe_debug(dev);
132 else
133 bus_probe_device(dev);
134
135 mutex_lock(&deferred_probe_mutex);
136
137 put_device(dev);
138 }
139 mutex_unlock(&deferred_probe_mutex);
140}
141static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
142
143static void driver_deferred_probe_add(struct device *dev)
144{
145 mutex_lock(&deferred_probe_mutex);
146 if (list_empty(&dev->p->deferred_probe)) {
147 dev_dbg(dev, "Added to deferred list\n");
148 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
149 }
150 mutex_unlock(&deferred_probe_mutex);
151}
152
153void driver_deferred_probe_del(struct device *dev)
154{
155 mutex_lock(&deferred_probe_mutex);
156 if (!list_empty(&dev->p->deferred_probe)) {
157 dev_dbg(dev, "Removed from deferred list\n");
158 list_del_init(&dev->p->deferred_probe);
159 }
160 mutex_unlock(&deferred_probe_mutex);
161}
162
163static bool driver_deferred_probe_enable = false;
164/**
165 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
166 *
167 * This functions moves all devices from the pending list to the active
168 * list and schedules the deferred probe workqueue to process them. It
169 * should be called anytime a driver is successfully bound to a device.
170 *
171 * Note, there is a race condition in multi-threaded probe. In the case where
172 * more than one device is probing at the same time, it is possible for one
173 * probe to complete successfully while another is about to defer. If the second
174 * depends on the first, then it will get put on the pending list after the
175 * trigger event has already occurred and will be stuck there.
176 *
177 * The atomic 'deferred_trigger_count' is used to determine if a successful
178 * trigger has occurred in the midst of probing a driver. If the trigger count
179 * changes in the midst of a probe, then deferred processing should be triggered
180 * again.
181 */
182static void driver_deferred_probe_trigger(void)
183{
184 if (!driver_deferred_probe_enable)
185 return;
186
187 /*
188 * A successful probe means that all the devices in the pending list
189 * should be triggered to be reprobed. Move all the deferred devices
190 * into the active list so they can be retried by the workqueue
191 */
192 mutex_lock(&deferred_probe_mutex);
193 atomic_inc(&deferred_trigger_count);
194 list_splice_tail_init(&deferred_probe_pending_list,
195 &deferred_probe_active_list);
196 mutex_unlock(&deferred_probe_mutex);
197
198 /*
199 * Kick the re-probe thread. It may already be scheduled, but it is
200 * safe to kick it again.
201 */
202 schedule_work(&deferred_probe_work);
203}
204
205/**
206 * device_block_probing() - Block/defere device's probes
207 *
208 * It will disable probing of devices and defer their probes instead.
209 */
210void device_block_probing(void)
211{
212 defer_all_probes = true;
213 /* sync with probes to avoid races. */
214 wait_for_device_probe();
215}
216
217/**
218 * device_unblock_probing() - Unblock/enable device's probes
219 *
220 * It will restore normal behavior and trigger re-probing of deferred
221 * devices.
222 */
223void device_unblock_probing(void)
224{
225 defer_all_probes = false;
226 driver_deferred_probe_trigger();
227}
228
229/**
230 * deferred_probe_initcall() - Enable probing of deferred devices
231 *
232 * We don't want to get in the way when the bulk of drivers are getting probed.
233 * Instead, this initcall makes sure that deferred probing is delayed until
234 * late_initcall time.
235 */
236static int deferred_probe_initcall(void)
237{
238 driver_deferred_probe_enable = true;
239 driver_deferred_probe_trigger();
240 /* Sort as many dependencies as possible before exiting initcalls */
241 flush_work(&deferred_probe_work);
242 initcalls_done = true;
243 return 0;
244}
245late_initcall(deferred_probe_initcall);
246
247/**
248 * device_is_bound() - Check if device is bound to a driver
249 * @dev: device to check
250 *
251 * Returns true if passed device has already finished probing successfully
252 * against a driver.
253 *
254 * This function must be called with the device lock held.
255 */
256bool device_is_bound(struct device *dev)
257{
258 return dev->p && klist_node_attached(&dev->p->knode_driver);
259}
260
261static void driver_bound(struct device *dev)
262{
263 if (device_is_bound(dev)) {
264 printk(KERN_WARNING "%s: device %s already bound\n",
265 __func__, kobject_name(&dev->kobj));
266 return;
267 }
268
269 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
270 __func__, dev_name(dev));
271
272 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
273 device_links_driver_bound(dev);
274
275 device_pm_check_callbacks(dev);
276
277 /*
278 * Make sure the device is no longer in one of the deferred lists and
279 * kick off retrying all pending devices
280 */
281 driver_deferred_probe_del(dev);
282 driver_deferred_probe_trigger();
283
284 if (dev->bus)
285 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
286 BUS_NOTIFY_BOUND_DRIVER, dev);
287
288 kobject_uevent(&dev->kobj, KOBJ_BIND);
289}
290
291static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
292 const char *buf, size_t count)
293{
294 device_lock(dev);
295 dev->driver->coredump(dev);
296 device_unlock(dev);
297
298 return count;
299}
300static DEVICE_ATTR_WO(coredump);
301
302static int driver_sysfs_add(struct device *dev)
303{
304 int ret;
305
306 if (dev->bus)
307 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
308 BUS_NOTIFY_BIND_DRIVER, dev);
309
310 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
311 kobject_name(&dev->kobj));
312 if (ret)
313 goto fail;
314
315 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
316 "driver");
317 if (ret)
318 goto rm_dev;
319
320 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
321 !device_create_file(dev, &dev_attr_coredump))
322 return 0;
323
324 sysfs_remove_link(&dev->kobj, "driver");
325
326rm_dev:
327 sysfs_remove_link(&dev->driver->p->kobj,
328 kobject_name(&dev->kobj));
329
330fail:
331 return ret;
332}
333
334static void driver_sysfs_remove(struct device *dev)
335{
336 struct device_driver *drv = dev->driver;
337
338 if (drv) {
339 if (drv->coredump)
340 device_remove_file(dev, &dev_attr_coredump);
341 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
342 sysfs_remove_link(&dev->kobj, "driver");
343 }
344}
345
346/**
347 * device_bind_driver - bind a driver to one device.
348 * @dev: device.
349 *
350 * Allow manual attachment of a driver to a device.
351 * Caller must have already set @dev->driver.
352 *
353 * Note that this does not modify the bus reference count
354 * nor take the bus's rwsem. Please verify those are accounted
355 * for before calling this. (It is ok to call with no other effort
356 * from a driver's probe() method.)
357 *
358 * This function must be called with the device lock held.
359 */
360int device_bind_driver(struct device *dev)
361{
362 int ret;
363
364 ret = driver_sysfs_add(dev);
365 if (!ret)
366 driver_bound(dev);
367 else if (dev->bus)
368 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
369 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
370 return ret;
371}
372EXPORT_SYMBOL_GPL(device_bind_driver);
373
374static atomic_t probe_count = ATOMIC_INIT(0);
375static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
376
377static void driver_deferred_probe_add_trigger(struct device *dev,
378 int local_trigger_count)
379{
380 driver_deferred_probe_add(dev);
381 /* Did a trigger occur while probing? Need to re-trigger if yes */
382 if (local_trigger_count != atomic_read(&deferred_trigger_count))
383 driver_deferred_probe_trigger();
384}
385
386static int really_probe(struct device *dev, struct device_driver *drv)
387{
388 int ret = -EPROBE_DEFER;
389 int local_trigger_count = atomic_read(&deferred_trigger_count);
390 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
391 !drv->suppress_bind_attrs;
392
393 if (defer_all_probes) {
394 /*
395 * Value of defer_all_probes can be set only by
396 * device_defer_all_probes_enable() which, in turn, will call
397 * wait_for_device_probe() right after that to avoid any races.
398 */
399 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
400 driver_deferred_probe_add(dev);
401 return ret;
402 }
403
404 ret = device_links_check_suppliers(dev);
405 if (ret == -EPROBE_DEFER)
406 driver_deferred_probe_add_trigger(dev, local_trigger_count);
407 if (ret)
408 return ret;
409
410 atomic_inc(&probe_count);
411 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
412 drv->bus->name, __func__, drv->name, dev_name(dev));
413 WARN_ON(!list_empty(&dev->devres_head));
414
415re_probe:
416 dev->driver = drv;
417
418 /* If using pinctrl, bind pins now before probing */
419 ret = pinctrl_bind_pins(dev);
420 if (ret)
421 goto pinctrl_bind_failed;
422
423 ret = dma_configure(dev);
424 if (ret)
425 goto dma_failed;
426
427 if (driver_sysfs_add(dev)) {
428 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
429 __func__, dev_name(dev));
430 goto probe_failed;
431 }
432
433 if (dev->pm_domain && dev->pm_domain->activate) {
434 ret = dev->pm_domain->activate(dev);
435 if (ret)
436 goto probe_failed;
437 }
438
439 /*
440 * Ensure devices are listed in devices_kset in correct order
441 * It's important to move Dev to the end of devices_kset before
442 * calling .probe, because it could be recursive and parent Dev
443 * should always go first
444 */
445 devices_kset_move_last(dev);
446
447 if (dev->bus->probe) {
448 ret = dev->bus->probe(dev);
449 if (ret)
450 goto probe_failed;
451 } else if (drv->probe) {
452 ret = drv->probe(dev);
453 if (ret)
454 goto probe_failed;
455 }
456
457 if (test_remove) {
458 test_remove = false;
459
460 if (dev->bus->remove)
461 dev->bus->remove(dev);
462 else if (drv->remove)
463 drv->remove(dev);
464
465 devres_release_all(dev);
466 driver_sysfs_remove(dev);
467 dev->driver = NULL;
468 dev_set_drvdata(dev, NULL);
469 if (dev->pm_domain && dev->pm_domain->dismiss)
470 dev->pm_domain->dismiss(dev);
471 pm_runtime_reinit(dev);
472
473 goto re_probe;
474 }
475
476 pinctrl_init_done(dev);
477
478 if (dev->pm_domain && dev->pm_domain->sync)
479 dev->pm_domain->sync(dev);
480
481 driver_bound(dev);
482 ret = 1;
483 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
484 drv->bus->name, __func__, dev_name(dev), drv->name);
485 goto done;
486
487probe_failed:
488 dma_deconfigure(dev);
489dma_failed:
490 if (dev->bus)
491 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
492 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
493pinctrl_bind_failed:
494 device_links_no_driver(dev);
495 devres_release_all(dev);
496 driver_sysfs_remove(dev);
497 dev->driver = NULL;
498 dev_set_drvdata(dev, NULL);
499 if (dev->pm_domain && dev->pm_domain->dismiss)
500 dev->pm_domain->dismiss(dev);
501 pm_runtime_reinit(dev);
502 dev_pm_set_driver_flags(dev, 0);
503
504 switch (ret) {
505 case -EPROBE_DEFER:
506 /* Driver requested deferred probing */
507 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
508 driver_deferred_probe_add_trigger(dev, local_trigger_count);
509 break;
510 case -ENODEV:
511 case -ENXIO:
512 pr_debug("%s: probe of %s rejects match %d\n",
513 drv->name, dev_name(dev), ret);
514 break;
515 default:
516 /* driver matched but the probe failed */
517 printk(KERN_WARNING
518 "%s: probe of %s failed with error %d\n",
519 drv->name, dev_name(dev), ret);
520 }
521 /*
522 * Ignore errors returned by ->probe so that the next driver can try
523 * its luck.
524 */
525 ret = 0;
526done:
527 atomic_dec(&probe_count);
528 wake_up(&probe_waitqueue);
529 return ret;
530}
531
532/**
533 * driver_probe_done
534 * Determine if the probe sequence is finished or not.
535 *
536 * Should somehow figure out how to use a semaphore, not an atomic variable...
537 */
538int driver_probe_done(void)
539{
540 pr_debug("%s: probe_count = %d\n", __func__,
541 atomic_read(&probe_count));
542 if (atomic_read(&probe_count))
543 return -EBUSY;
544 return 0;
545}
546
547/**
548 * wait_for_device_probe
549 * Wait for device probing to be completed.
550 */
551void wait_for_device_probe(void)
552{
553 /* wait for the deferred probe workqueue to finish */
554 flush_work(&deferred_probe_work);
555
556 /* wait for the known devices to complete their probing */
557 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
558 async_synchronize_full();
559}
560EXPORT_SYMBOL_GPL(wait_for_device_probe);
561
562/**
563 * driver_probe_device - attempt to bind device & driver together
564 * @drv: driver to bind a device to
565 * @dev: device to try to bind to the driver
566 *
567 * This function returns -ENODEV if the device is not registered,
568 * 1 if the device is bound successfully and 0 otherwise.
569 *
570 * This function must be called with @dev lock held. When called for a
571 * USB interface, @dev->parent lock must be held as well.
572 *
573 * If the device has a parent, runtime-resume the parent before driver probing.
574 */
575int driver_probe_device(struct device_driver *drv, struct device *dev)
576{
577 int ret = 0;
578
579 if (!device_is_registered(dev))
580 return -ENODEV;
581
582 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
583 drv->bus->name, __func__, dev_name(dev), drv->name);
584
585 pm_runtime_get_suppliers(dev);
586 if (dev->parent)
587 pm_runtime_get_sync(dev->parent);
588
589 pm_runtime_barrier(dev);
590 ret = really_probe(dev, drv);
591 pm_request_idle(dev);
592
593 if (dev->parent)
594 pm_runtime_put(dev->parent);
595
596 pm_runtime_put_suppliers(dev);
597 return ret;
598}
599
600bool driver_allows_async_probing(struct device_driver *drv)
601{
602 switch (drv->probe_type) {
603 case PROBE_PREFER_ASYNCHRONOUS:
604 return true;
605
606 case PROBE_FORCE_SYNCHRONOUS:
607 return false;
608
609 default:
610 if (module_requested_async_probing(drv->owner))
611 return true;
612
613 return false;
614 }
615}
616
617struct device_attach_data {
618 struct device *dev;
619
620 /*
621 * Indicates whether we are are considering asynchronous probing or
622 * not. Only initial binding after device or driver registration
623 * (including deferral processing) may be done asynchronously, the
624 * rest is always synchronous, as we expect it is being done by
625 * request from userspace.
626 */
627 bool check_async;
628
629 /*
630 * Indicates if we are binding synchronous or asynchronous drivers.
631 * When asynchronous probing is enabled we'll execute 2 passes
632 * over drivers: first pass doing synchronous probing and second
633 * doing asynchronous probing (if synchronous did not succeed -
634 * most likely because there was no driver requiring synchronous
635 * probing - and we found asynchronous driver during first pass).
636 * The 2 passes are done because we can't shoot asynchronous
637 * probe for given device and driver from bus_for_each_drv() since
638 * driver pointer is not guaranteed to stay valid once
639 * bus_for_each_drv() iterates to the next driver on the bus.
640 */
641 bool want_async;
642
643 /*
644 * We'll set have_async to 'true' if, while scanning for matching
645 * driver, we'll encounter one that requests asynchronous probing.
646 */
647 bool have_async;
648};
649
650static int __device_attach_driver(struct device_driver *drv, void *_data)
651{
652 struct device_attach_data *data = _data;
653 struct device *dev = data->dev;
654 bool async_allowed;
655 int ret;
656
657 /*
658 * Check if device has already been claimed. This may
659 * happen with driver loading, device discovery/registration,
660 * and deferred probe processing happens all at once with
661 * multiple threads.
662 */
663 if (dev->driver)
664 return -EBUSY;
665
666 ret = driver_match_device(drv, dev);
667 if (ret == 0) {
668 /* no match */
669 return 0;
670 } else if (ret == -EPROBE_DEFER) {
671 dev_dbg(dev, "Device match requests probe deferral\n");
672 driver_deferred_probe_add(dev);
673 } else if (ret < 0) {
674 dev_dbg(dev, "Bus failed to match device: %d", ret);
675 return ret;
676 } /* ret > 0 means positive match */
677
678 async_allowed = driver_allows_async_probing(drv);
679
680 if (async_allowed)
681 data->have_async = true;
682
683 if (data->check_async && async_allowed != data->want_async)
684 return 0;
685
686 return driver_probe_device(drv, dev);
687}
688
689static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
690{
691 struct device *dev = _dev;
692 struct device_attach_data data = {
693 .dev = dev,
694 .check_async = true,
695 .want_async = true,
696 };
697
698 device_lock(dev);
699
700 if (dev->parent)
701 pm_runtime_get_sync(dev->parent);
702
703 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
704 dev_dbg(dev, "async probe completed\n");
705
706 pm_request_idle(dev);
707
708 if (dev->parent)
709 pm_runtime_put(dev->parent);
710
711 device_unlock(dev);
712
713 put_device(dev);
714}
715
716static int __device_attach(struct device *dev, bool allow_async)
717{
718 int ret = 0;
719
720 device_lock(dev);
721 if (dev->driver) {
722 if (device_is_bound(dev)) {
723 ret = 1;
724 goto out_unlock;
725 }
726 ret = device_bind_driver(dev);
727 if (ret == 0)
728 ret = 1;
729 else {
730 dev->driver = NULL;
731 ret = 0;
732 }
733 } else {
734 struct device_attach_data data = {
735 .dev = dev,
736 .check_async = allow_async,
737 .want_async = false,
738 };
739
740 if (dev->parent)
741 pm_runtime_get_sync(dev->parent);
742
743 ret = bus_for_each_drv(dev->bus, NULL, &data,
744 __device_attach_driver);
745 if (!ret && allow_async && data.have_async) {
746 /*
747 * If we could not find appropriate driver
748 * synchronously and we are allowed to do
749 * async probes and there are drivers that
750 * want to probe asynchronously, we'll
751 * try them.
752 */
753 dev_dbg(dev, "scheduling asynchronous probe\n");
754 get_device(dev);
755 async_schedule(__device_attach_async_helper, dev);
756 } else {
757 pm_request_idle(dev);
758 }
759
760 if (dev->parent)
761 pm_runtime_put(dev->parent);
762 }
763out_unlock:
764 device_unlock(dev);
765 return ret;
766}
767
768/**
769 * device_attach - try to attach device to a driver.
770 * @dev: device.
771 *
772 * Walk the list of drivers that the bus has and call
773 * driver_probe_device() for each pair. If a compatible
774 * pair is found, break out and return.
775 *
776 * Returns 1 if the device was bound to a driver;
777 * 0 if no matching driver was found;
778 * -ENODEV if the device is not registered.
779 *
780 * When called for a USB interface, @dev->parent lock must be held.
781 */
782int device_attach(struct device *dev)
783{
784 return __device_attach(dev, false);
785}
786EXPORT_SYMBOL_GPL(device_attach);
787
788void device_initial_probe(struct device *dev)
789{
790 __device_attach(dev, true);
791}
792
793static int __driver_attach(struct device *dev, void *data)
794{
795 struct device_driver *drv = data;
796 int ret;
797
798 /*
799 * Lock device and try to bind to it. We drop the error
800 * here and always return 0, because we need to keep trying
801 * to bind to devices and some drivers will return an error
802 * simply if it didn't support the device.
803 *
804 * driver_probe_device() will spit a warning if there
805 * is an error.
806 */
807
808 ret = driver_match_device(drv, dev);
809 if (ret == 0) {
810 /* no match */
811 return 0;
812 } else if (ret == -EPROBE_DEFER) {
813 dev_dbg(dev, "Device match requests probe deferral\n");
814 driver_deferred_probe_add(dev);
815 } else if (ret < 0) {
816 dev_dbg(dev, "Bus failed to match device: %d", ret);
817 return ret;
818 } /* ret > 0 means positive match */
819
820 if (dev->parent) /* Needed for USB */
821 device_lock(dev->parent);
822 device_lock(dev);
823 if (!dev->driver)
824 driver_probe_device(drv, dev);
825 device_unlock(dev);
826 if (dev->parent)
827 device_unlock(dev->parent);
828
829 return 0;
830}
831
832/**
833 * driver_attach - try to bind driver to devices.
834 * @drv: driver.
835 *
836 * Walk the list of devices that the bus has on it and try to
837 * match the driver with each one. If driver_probe_device()
838 * returns 0 and the @dev->driver is set, we've found a
839 * compatible pair.
840 */
841int driver_attach(struct device_driver *drv)
842{
843 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
844}
845EXPORT_SYMBOL_GPL(driver_attach);
846
847/*
848 * __device_release_driver() must be called with @dev lock held.
849 * When called for a USB interface, @dev->parent lock must be held as well.
850 */
851static void __device_release_driver(struct device *dev, struct device *parent)
852{
853 struct device_driver *drv;
854
855 drv = dev->driver;
856 if (drv) {
857 if (driver_allows_async_probing(drv))
858 async_synchronize_full();
859
860 while (device_links_busy(dev)) {
861 device_unlock(dev);
862 if (parent)
863 device_unlock(parent);
864
865 device_links_unbind_consumers(dev);
866 if (parent)
867 device_lock(parent);
868
869 device_lock(dev);
870 /*
871 * A concurrent invocation of the same function might
872 * have released the driver successfully while this one
873 * was waiting, so check for that.
874 */
875 if (dev->driver != drv)
876 return;
877 }
878
879 pm_runtime_get_sync(dev);
880 pm_runtime_clean_up_links(dev);
881
882 driver_sysfs_remove(dev);
883
884 if (dev->bus)
885 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
886 BUS_NOTIFY_UNBIND_DRIVER,
887 dev);
888
889 pm_runtime_put_sync(dev);
890
891 if (dev->bus && dev->bus->remove)
892 dev->bus->remove(dev);
893 else if (drv->remove)
894 drv->remove(dev);
895
896 device_links_driver_cleanup(dev);
897 dma_deconfigure(dev);
898
899 devres_release_all(dev);
900 dev->driver = NULL;
901 dev_set_drvdata(dev, NULL);
902 if (dev->pm_domain && dev->pm_domain->dismiss)
903 dev->pm_domain->dismiss(dev);
904 pm_runtime_reinit(dev);
905 dev_pm_set_driver_flags(dev, 0);
906
907 klist_remove(&dev->p->knode_driver);
908 device_pm_check_callbacks(dev);
909 if (dev->bus)
910 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
911 BUS_NOTIFY_UNBOUND_DRIVER,
912 dev);
913
914 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
915 }
916}
917
918void device_release_driver_internal(struct device *dev,
919 struct device_driver *drv,
920 struct device *parent)
921{
922 if (parent)
923 device_lock(parent);
924
925 device_lock(dev);
926 if (!drv || drv == dev->driver)
927 __device_release_driver(dev, parent);
928
929 device_unlock(dev);
930 if (parent)
931 device_unlock(parent);
932}
933
934/**
935 * device_release_driver - manually detach device from driver.
936 * @dev: device.
937 *
938 * Manually detach device from driver.
939 * When called for a USB interface, @dev->parent lock must be held.
940 *
941 * If this function is to be called with @dev->parent lock held, ensure that
942 * the device's consumers are unbound in advance or that their locks can be
943 * acquired under the @dev->parent lock.
944 */
945void device_release_driver(struct device *dev)
946{
947 /*
948 * If anyone calls device_release_driver() recursively from
949 * within their ->remove callback for the same device, they
950 * will deadlock right here.
951 */
952 device_release_driver_internal(dev, NULL, NULL);
953}
954EXPORT_SYMBOL_GPL(device_release_driver);
955
956/**
957 * driver_detach - detach driver from all devices it controls.
958 * @drv: driver.
959 */
960void driver_detach(struct device_driver *drv)
961{
962 struct device_private *dev_prv;
963 struct device *dev;
964
965 for (;;) {
966 spin_lock(&drv->p->klist_devices.k_lock);
967 if (list_empty(&drv->p->klist_devices.k_list)) {
968 spin_unlock(&drv->p->klist_devices.k_lock);
969 break;
970 }
971 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
972 struct device_private,
973 knode_driver.n_node);
974 dev = dev_prv->device;
975 get_device(dev);
976 spin_unlock(&drv->p->klist_devices.k_lock);
977 device_release_driver_internal(dev, drv, dev->parent);
978 put_device(dev);
979 }
980}
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 */
51static DEFINE_MUTEX(deferred_probe_mutex);
52static LIST_HEAD(deferred_probe_pending_list);
53static LIST_HEAD(deferred_probe_active_list);
54static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
55
56/*
57 * In some cases, like suspend to RAM or hibernation, It might be reasonable
58 * to prohibit probing of devices as it could be unsafe.
59 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
60 */
61static bool defer_all_probes;
62
63/*
64 * deferred_probe_work_func() - Retry probing devices in the active list.
65 */
66static void deferred_probe_work_func(struct work_struct *work)
67{
68 struct device *dev;
69 struct device_private *private;
70 /*
71 * This block processes every device in the deferred 'active' list.
72 * Each device is removed from the active list and passed to
73 * bus_probe_device() to re-attempt the probe. The loop continues
74 * until every device in the active list is removed and retried.
75 *
76 * Note: Once the device is removed from the list and the mutex is
77 * released, it is possible for the device get freed by another thread
78 * and cause a illegal pointer dereference. This code uses
79 * get/put_device() to ensure the device structure cannot disappear
80 * from under our feet.
81 */
82 mutex_lock(&deferred_probe_mutex);
83 while (!list_empty(&deferred_probe_active_list)) {
84 private = list_first_entry(&deferred_probe_active_list,
85 typeof(*dev->p), deferred_probe);
86 dev = private->device;
87 list_del_init(&private->deferred_probe);
88
89 get_device(dev);
90
91 /*
92 * Drop the mutex while probing each device; the probe path may
93 * manipulate the deferred list
94 */
95 mutex_unlock(&deferred_probe_mutex);
96
97 /*
98 * Force the device to the end of the dpm_list since
99 * the PM code assumes that the order we add things to
100 * the list is a good order for suspend but deferred
101 * probe makes that very unsafe.
102 */
103 device_pm_lock();
104 device_pm_move_last(dev);
105 device_pm_unlock();
106
107 dev_dbg(dev, "Retrying from deferred list\n");
108 bus_probe_device(dev);
109
110 mutex_lock(&deferred_probe_mutex);
111
112 put_device(dev);
113 }
114 mutex_unlock(&deferred_probe_mutex);
115}
116static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
117
118static void driver_deferred_probe_add(struct device *dev)
119{
120 mutex_lock(&deferred_probe_mutex);
121 if (list_empty(&dev->p->deferred_probe)) {
122 dev_dbg(dev, "Added to deferred list\n");
123 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
124 }
125 mutex_unlock(&deferred_probe_mutex);
126}
127
128void driver_deferred_probe_del(struct device *dev)
129{
130 mutex_lock(&deferred_probe_mutex);
131 if (!list_empty(&dev->p->deferred_probe)) {
132 dev_dbg(dev, "Removed from deferred list\n");
133 list_del_init(&dev->p->deferred_probe);
134 }
135 mutex_unlock(&deferred_probe_mutex);
136}
137
138static bool driver_deferred_probe_enable = false;
139/**
140 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
141 *
142 * This functions moves all devices from the pending list to the active
143 * list and schedules the deferred probe workqueue to process them. It
144 * should be called anytime a driver is successfully bound to a device.
145 *
146 * Note, there is a race condition in multi-threaded probe. In the case where
147 * more than one device is probing at the same time, it is possible for one
148 * probe to complete successfully while another is about to defer. If the second
149 * depends on the first, then it will get put on the pending list after the
150 * trigger event has already occurred and will be stuck there.
151 *
152 * The atomic 'deferred_trigger_count' is used to determine if a successful
153 * trigger has occurred in the midst of probing a driver. If the trigger count
154 * changes in the midst of a probe, then deferred processing should be triggered
155 * again.
156 */
157static void driver_deferred_probe_trigger(void)
158{
159 if (!driver_deferred_probe_enable)
160 return;
161
162 /*
163 * A successful probe means that all the devices in the pending list
164 * should be triggered to be reprobed. Move all the deferred devices
165 * into the active list so they can be retried by the workqueue
166 */
167 mutex_lock(&deferred_probe_mutex);
168 atomic_inc(&deferred_trigger_count);
169 list_splice_tail_init(&deferred_probe_pending_list,
170 &deferred_probe_active_list);
171 mutex_unlock(&deferred_probe_mutex);
172
173 /*
174 * Kick the re-probe thread. It may already be scheduled, but it is
175 * safe to kick it again.
176 */
177 schedule_work(&deferred_probe_work);
178}
179
180/**
181 * device_block_probing() - Block/defere device's probes
182 *
183 * It will disable probing of devices and defer their probes instead.
184 */
185void device_block_probing(void)
186{
187 defer_all_probes = true;
188 /* sync with probes to avoid races. */
189 wait_for_device_probe();
190}
191
192/**
193 * device_unblock_probing() - Unblock/enable device's probes
194 *
195 * It will restore normal behavior and trigger re-probing of deferred
196 * devices.
197 */
198void device_unblock_probing(void)
199{
200 defer_all_probes = false;
201 driver_deferred_probe_trigger();
202}
203
204/**
205 * deferred_probe_initcall() - Enable probing of deferred devices
206 *
207 * We don't want to get in the way when the bulk of drivers are getting probed.
208 * Instead, this initcall makes sure that deferred probing is delayed until
209 * late_initcall time.
210 */
211static int deferred_probe_initcall(void)
212{
213 driver_deferred_probe_enable = true;
214 driver_deferred_probe_trigger();
215 /* Sort as many dependencies as possible before exiting initcalls */
216 flush_work(&deferred_probe_work);
217 return 0;
218}
219late_initcall(deferred_probe_initcall);
220
221/**
222 * device_is_bound() - Check if device is bound to a driver
223 * @dev: device to check
224 *
225 * Returns true if passed device has already finished probing successfully
226 * against a driver.
227 *
228 * This function must be called with the device lock held.
229 */
230bool device_is_bound(struct device *dev)
231{
232 return dev->p && klist_node_attached(&dev->p->knode_driver);
233}
234
235static void driver_bound(struct device *dev)
236{
237 if (device_is_bound(dev)) {
238 printk(KERN_WARNING "%s: device %s already bound\n",
239 __func__, kobject_name(&dev->kobj));
240 return;
241 }
242
243 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
244 __func__, dev_name(dev));
245
246 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
247 device_links_driver_bound(dev);
248
249 device_pm_check_callbacks(dev);
250
251 /*
252 * Make sure the device is no longer in one of the deferred lists and
253 * kick off retrying all pending devices
254 */
255 driver_deferred_probe_del(dev);
256 driver_deferred_probe_trigger();
257
258 if (dev->bus)
259 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
260 BUS_NOTIFY_BOUND_DRIVER, dev);
261}
262
263static int driver_sysfs_add(struct device *dev)
264{
265 int ret;
266
267 if (dev->bus)
268 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
269 BUS_NOTIFY_BIND_DRIVER, dev);
270
271 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
272 kobject_name(&dev->kobj));
273 if (ret == 0) {
274 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
275 "driver");
276 if (ret)
277 sysfs_remove_link(&dev->driver->p->kobj,
278 kobject_name(&dev->kobj));
279 }
280 return ret;
281}
282
283static void driver_sysfs_remove(struct device *dev)
284{
285 struct device_driver *drv = dev->driver;
286
287 if (drv) {
288 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
289 sysfs_remove_link(&dev->kobj, "driver");
290 }
291}
292
293/**
294 * device_bind_driver - bind a driver to one device.
295 * @dev: device.
296 *
297 * Allow manual attachment of a driver to a device.
298 * Caller must have already set @dev->driver.
299 *
300 * Note that this does not modify the bus reference count
301 * nor take the bus's rwsem. Please verify those are accounted
302 * for before calling this. (It is ok to call with no other effort
303 * from a driver's probe() method.)
304 *
305 * This function must be called with the device lock held.
306 */
307int device_bind_driver(struct device *dev)
308{
309 int ret;
310
311 ret = driver_sysfs_add(dev);
312 if (!ret)
313 driver_bound(dev);
314 else if (dev->bus)
315 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
316 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
317 return ret;
318}
319EXPORT_SYMBOL_GPL(device_bind_driver);
320
321static atomic_t probe_count = ATOMIC_INIT(0);
322static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
323
324static int really_probe(struct device *dev, struct device_driver *drv)
325{
326 int ret = -EPROBE_DEFER;
327 int local_trigger_count = atomic_read(&deferred_trigger_count);
328 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
329 !drv->suppress_bind_attrs;
330
331 if (defer_all_probes) {
332 /*
333 * Value of defer_all_probes can be set only by
334 * device_defer_all_probes_enable() which, in turn, will call
335 * wait_for_device_probe() right after that to avoid any races.
336 */
337 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
338 driver_deferred_probe_add(dev);
339 return ret;
340 }
341
342 ret = device_links_check_suppliers(dev);
343 if (ret)
344 return ret;
345
346 atomic_inc(&probe_count);
347 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
348 drv->bus->name, __func__, drv->name, dev_name(dev));
349 WARN_ON(!list_empty(&dev->devres_head));
350
351re_probe:
352 dev->driver = drv;
353
354 /* If using pinctrl, bind pins now before probing */
355 ret = pinctrl_bind_pins(dev);
356 if (ret)
357 goto pinctrl_bind_failed;
358
359 if (driver_sysfs_add(dev)) {
360 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
361 __func__, dev_name(dev));
362 goto probe_failed;
363 }
364
365 if (dev->pm_domain && dev->pm_domain->activate) {
366 ret = dev->pm_domain->activate(dev);
367 if (ret)
368 goto probe_failed;
369 }
370
371 /*
372 * Ensure devices are listed in devices_kset in correct order
373 * It's important to move Dev to the end of devices_kset before
374 * calling .probe, because it could be recursive and parent Dev
375 * should always go first
376 */
377 devices_kset_move_last(dev);
378
379 if (dev->bus->probe) {
380 ret = dev->bus->probe(dev);
381 if (ret)
382 goto probe_failed;
383 } else if (drv->probe) {
384 ret = drv->probe(dev);
385 if (ret)
386 goto probe_failed;
387 }
388
389 if (test_remove) {
390 test_remove = false;
391
392 if (dev->bus->remove)
393 dev->bus->remove(dev);
394 else if (drv->remove)
395 drv->remove(dev);
396
397 devres_release_all(dev);
398 driver_sysfs_remove(dev);
399 dev->driver = NULL;
400 dev_set_drvdata(dev, NULL);
401 if (dev->pm_domain && dev->pm_domain->dismiss)
402 dev->pm_domain->dismiss(dev);
403 pm_runtime_reinit(dev);
404
405 goto re_probe;
406 }
407
408 pinctrl_init_done(dev);
409
410 if (dev->pm_domain && dev->pm_domain->sync)
411 dev->pm_domain->sync(dev);
412
413 driver_bound(dev);
414 ret = 1;
415 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
416 drv->bus->name, __func__, dev_name(dev), drv->name);
417 goto done;
418
419probe_failed:
420 if (dev->bus)
421 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
422 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
423pinctrl_bind_failed:
424 device_links_no_driver(dev);
425 devres_release_all(dev);
426 driver_sysfs_remove(dev);
427 dev->driver = NULL;
428 dev_set_drvdata(dev, NULL);
429 if (dev->pm_domain && dev->pm_domain->dismiss)
430 dev->pm_domain->dismiss(dev);
431 pm_runtime_reinit(dev);
432
433 switch (ret) {
434 case -EPROBE_DEFER:
435 /* Driver requested deferred probing */
436 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
437 driver_deferred_probe_add(dev);
438 /* Did a trigger occur while probing? Need to re-trigger if yes */
439 if (local_trigger_count != atomic_read(&deferred_trigger_count))
440 driver_deferred_probe_trigger();
441 break;
442 case -ENODEV:
443 case -ENXIO:
444 pr_debug("%s: probe of %s rejects match %d\n",
445 drv->name, dev_name(dev), ret);
446 break;
447 default:
448 /* driver matched but the probe failed */
449 printk(KERN_WARNING
450 "%s: probe of %s failed with error %d\n",
451 drv->name, dev_name(dev), ret);
452 }
453 /*
454 * Ignore errors returned by ->probe so that the next driver can try
455 * its luck.
456 */
457 ret = 0;
458done:
459 atomic_dec(&probe_count);
460 wake_up(&probe_waitqueue);
461 return ret;
462}
463
464/**
465 * driver_probe_done
466 * Determine if the probe sequence is finished or not.
467 *
468 * Should somehow figure out how to use a semaphore, not an atomic variable...
469 */
470int driver_probe_done(void)
471{
472 pr_debug("%s: probe_count = %d\n", __func__,
473 atomic_read(&probe_count));
474 if (atomic_read(&probe_count))
475 return -EBUSY;
476 return 0;
477}
478
479/**
480 * wait_for_device_probe
481 * Wait for device probing to be completed.
482 */
483void wait_for_device_probe(void)
484{
485 /* wait for the deferred probe workqueue to finish */
486 flush_work(&deferred_probe_work);
487
488 /* wait for the known devices to complete their probing */
489 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
490 async_synchronize_full();
491}
492EXPORT_SYMBOL_GPL(wait_for_device_probe);
493
494/**
495 * driver_probe_device - attempt to bind device & driver together
496 * @drv: driver to bind a device to
497 * @dev: device to try to bind to the driver
498 *
499 * This function returns -ENODEV if the device is not registered,
500 * 1 if the device is bound successfully and 0 otherwise.
501 *
502 * This function must be called with @dev lock held. When called for a
503 * USB interface, @dev->parent lock must be held as well.
504 *
505 * If the device has a parent, runtime-resume the parent before driver probing.
506 */
507int driver_probe_device(struct device_driver *drv, struct device *dev)
508{
509 int ret = 0;
510
511 if (!device_is_registered(dev))
512 return -ENODEV;
513
514 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
515 drv->bus->name, __func__, dev_name(dev), drv->name);
516
517 pm_runtime_get_suppliers(dev);
518 if (dev->parent)
519 pm_runtime_get_sync(dev->parent);
520
521 pm_runtime_barrier(dev);
522 ret = really_probe(dev, drv);
523 pm_request_idle(dev);
524
525 if (dev->parent)
526 pm_runtime_put(dev->parent);
527
528 pm_runtime_put_suppliers(dev);
529 return ret;
530}
531
532bool driver_allows_async_probing(struct device_driver *drv)
533{
534 switch (drv->probe_type) {
535 case PROBE_PREFER_ASYNCHRONOUS:
536 return true;
537
538 case PROBE_FORCE_SYNCHRONOUS:
539 return false;
540
541 default:
542 if (module_requested_async_probing(drv->owner))
543 return true;
544
545 return false;
546 }
547}
548
549struct device_attach_data {
550 struct device *dev;
551
552 /*
553 * Indicates whether we are are considering asynchronous probing or
554 * not. Only initial binding after device or driver registration
555 * (including deferral processing) may be done asynchronously, the
556 * rest is always synchronous, as we expect it is being done by
557 * request from userspace.
558 */
559 bool check_async;
560
561 /*
562 * Indicates if we are binding synchronous or asynchronous drivers.
563 * When asynchronous probing is enabled we'll execute 2 passes
564 * over drivers: first pass doing synchronous probing and second
565 * doing asynchronous probing (if synchronous did not succeed -
566 * most likely because there was no driver requiring synchronous
567 * probing - and we found asynchronous driver during first pass).
568 * The 2 passes are done because we can't shoot asynchronous
569 * probe for given device and driver from bus_for_each_drv() since
570 * driver pointer is not guaranteed to stay valid once
571 * bus_for_each_drv() iterates to the next driver on the bus.
572 */
573 bool want_async;
574
575 /*
576 * We'll set have_async to 'true' if, while scanning for matching
577 * driver, we'll encounter one that requests asynchronous probing.
578 */
579 bool have_async;
580};
581
582static int __device_attach_driver(struct device_driver *drv, void *_data)
583{
584 struct device_attach_data *data = _data;
585 struct device *dev = data->dev;
586 bool async_allowed;
587 int ret;
588
589 /*
590 * Check if device has already been claimed. This may
591 * happen with driver loading, device discovery/registration,
592 * and deferred probe processing happens all at once with
593 * multiple threads.
594 */
595 if (dev->driver)
596 return -EBUSY;
597
598 ret = driver_match_device(drv, dev);
599 if (ret == 0) {
600 /* no match */
601 return 0;
602 } else if (ret == -EPROBE_DEFER) {
603 dev_dbg(dev, "Device match requests probe deferral\n");
604 driver_deferred_probe_add(dev);
605 } else if (ret < 0) {
606 dev_dbg(dev, "Bus failed to match device: %d", ret);
607 return ret;
608 } /* ret > 0 means positive match */
609
610 async_allowed = driver_allows_async_probing(drv);
611
612 if (async_allowed)
613 data->have_async = true;
614
615 if (data->check_async && async_allowed != data->want_async)
616 return 0;
617
618 return driver_probe_device(drv, dev);
619}
620
621static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
622{
623 struct device *dev = _dev;
624 struct device_attach_data data = {
625 .dev = dev,
626 .check_async = true,
627 .want_async = true,
628 };
629
630 device_lock(dev);
631
632 if (dev->parent)
633 pm_runtime_get_sync(dev->parent);
634
635 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
636 dev_dbg(dev, "async probe completed\n");
637
638 pm_request_idle(dev);
639
640 if (dev->parent)
641 pm_runtime_put(dev->parent);
642
643 device_unlock(dev);
644
645 put_device(dev);
646}
647
648static int __device_attach(struct device *dev, bool allow_async)
649{
650 int ret = 0;
651
652 device_lock(dev);
653 if (dev->driver) {
654 if (device_is_bound(dev)) {
655 ret = 1;
656 goto out_unlock;
657 }
658 ret = device_bind_driver(dev);
659 if (ret == 0)
660 ret = 1;
661 else {
662 dev->driver = NULL;
663 ret = 0;
664 }
665 } else {
666 struct device_attach_data data = {
667 .dev = dev,
668 .check_async = allow_async,
669 .want_async = false,
670 };
671
672 if (dev->parent)
673 pm_runtime_get_sync(dev->parent);
674
675 ret = bus_for_each_drv(dev->bus, NULL, &data,
676 __device_attach_driver);
677 if (!ret && allow_async && data.have_async) {
678 /*
679 * If we could not find appropriate driver
680 * synchronously and we are allowed to do
681 * async probes and there are drivers that
682 * want to probe asynchronously, we'll
683 * try them.
684 */
685 dev_dbg(dev, "scheduling asynchronous probe\n");
686 get_device(dev);
687 async_schedule(__device_attach_async_helper, dev);
688 } else {
689 pm_request_idle(dev);
690 }
691
692 if (dev->parent)
693 pm_runtime_put(dev->parent);
694 }
695out_unlock:
696 device_unlock(dev);
697 return ret;
698}
699
700/**
701 * device_attach - try to attach device to a driver.
702 * @dev: device.
703 *
704 * Walk the list of drivers that the bus has and call
705 * driver_probe_device() for each pair. If a compatible
706 * pair is found, break out and return.
707 *
708 * Returns 1 if the device was bound to a driver;
709 * 0 if no matching driver was found;
710 * -ENODEV if the device is not registered.
711 *
712 * When called for a USB interface, @dev->parent lock must be held.
713 */
714int device_attach(struct device *dev)
715{
716 return __device_attach(dev, false);
717}
718EXPORT_SYMBOL_GPL(device_attach);
719
720void device_initial_probe(struct device *dev)
721{
722 __device_attach(dev, true);
723}
724
725static int __driver_attach(struct device *dev, void *data)
726{
727 struct device_driver *drv = data;
728 int ret;
729
730 /*
731 * Lock device and try to bind to it. We drop the error
732 * here and always return 0, because we need to keep trying
733 * to bind to devices and some drivers will return an error
734 * simply if it didn't support the device.
735 *
736 * driver_probe_device() will spit a warning if there
737 * is an error.
738 */
739
740 ret = driver_match_device(drv, dev);
741 if (ret == 0) {
742 /* no match */
743 return 0;
744 } else if (ret == -EPROBE_DEFER) {
745 dev_dbg(dev, "Device match requests probe deferral\n");
746 driver_deferred_probe_add(dev);
747 } else if (ret < 0) {
748 dev_dbg(dev, "Bus failed to match device: %d", ret);
749 return ret;
750 } /* ret > 0 means positive match */
751
752 if (dev->parent) /* Needed for USB */
753 device_lock(dev->parent);
754 device_lock(dev);
755 if (!dev->driver)
756 driver_probe_device(drv, dev);
757 device_unlock(dev);
758 if (dev->parent)
759 device_unlock(dev->parent);
760
761 return 0;
762}
763
764/**
765 * driver_attach - try to bind driver to devices.
766 * @drv: driver.
767 *
768 * Walk the list of devices that the bus has on it and try to
769 * match the driver with each one. If driver_probe_device()
770 * returns 0 and the @dev->driver is set, we've found a
771 * compatible pair.
772 */
773int driver_attach(struct device_driver *drv)
774{
775 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
776}
777EXPORT_SYMBOL_GPL(driver_attach);
778
779/*
780 * __device_release_driver() must be called with @dev lock held.
781 * When called for a USB interface, @dev->parent lock must be held as well.
782 */
783static void __device_release_driver(struct device *dev, struct device *parent)
784{
785 struct device_driver *drv;
786
787 drv = dev->driver;
788 if (drv) {
789 if (driver_allows_async_probing(drv))
790 async_synchronize_full();
791
792 while (device_links_busy(dev)) {
793 device_unlock(dev);
794 if (parent)
795 device_unlock(parent);
796
797 device_links_unbind_consumers(dev);
798 if (parent)
799 device_lock(parent);
800
801 device_lock(dev);
802 /*
803 * A concurrent invocation of the same function might
804 * have released the driver successfully while this one
805 * was waiting, so check for that.
806 */
807 if (dev->driver != drv)
808 return;
809 }
810
811 pm_runtime_get_sync(dev);
812 pm_runtime_clean_up_links(dev);
813
814 driver_sysfs_remove(dev);
815
816 if (dev->bus)
817 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
818 BUS_NOTIFY_UNBIND_DRIVER,
819 dev);
820
821 pm_runtime_put_sync(dev);
822
823 if (dev->bus && dev->bus->remove)
824 dev->bus->remove(dev);
825 else if (drv->remove)
826 drv->remove(dev);
827
828 device_links_driver_cleanup(dev);
829 devres_release_all(dev);
830 dev->driver = NULL;
831 dev_set_drvdata(dev, NULL);
832 if (dev->pm_domain && dev->pm_domain->dismiss)
833 dev->pm_domain->dismiss(dev);
834 pm_runtime_reinit(dev);
835
836 klist_remove(&dev->p->knode_driver);
837 device_pm_check_callbacks(dev);
838 if (dev->bus)
839 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
840 BUS_NOTIFY_UNBOUND_DRIVER,
841 dev);
842 }
843}
844
845void device_release_driver_internal(struct device *dev,
846 struct device_driver *drv,
847 struct device *parent)
848{
849 if (parent)
850 device_lock(parent);
851
852 device_lock(dev);
853 if (!drv || drv == dev->driver)
854 __device_release_driver(dev, parent);
855
856 device_unlock(dev);
857 if (parent)
858 device_unlock(parent);
859}
860
861/**
862 * device_release_driver - manually detach device from driver.
863 * @dev: device.
864 *
865 * Manually detach device from driver.
866 * When called for a USB interface, @dev->parent lock must be held.
867 *
868 * If this function is to be called with @dev->parent lock held, ensure that
869 * the device's consumers are unbound in advance or that their locks can be
870 * acquired under the @dev->parent lock.
871 */
872void device_release_driver(struct device *dev)
873{
874 /*
875 * If anyone calls device_release_driver() recursively from
876 * within their ->remove callback for the same device, they
877 * will deadlock right here.
878 */
879 device_release_driver_internal(dev, NULL, NULL);
880}
881EXPORT_SYMBOL_GPL(device_release_driver);
882
883/**
884 * driver_detach - detach driver from all devices it controls.
885 * @drv: driver.
886 */
887void driver_detach(struct device_driver *drv)
888{
889 struct device_private *dev_prv;
890 struct device *dev;
891
892 for (;;) {
893 spin_lock(&drv->p->klist_devices.k_lock);
894 if (list_empty(&drv->p->klist_devices.k_list)) {
895 spin_unlock(&drv->p->klist_devices.k_lock);
896 break;
897 }
898 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
899 struct device_private,
900 knode_driver.n_node);
901 dev = dev_prv->device;
902 get_device(dev);
903 spin_unlock(&drv->p->klist_devices.k_lock);
904 device_release_driver_internal(dev, drv, dev->parent);
905 put_device(dev);
906 }
907}