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 */
53static DEFINE_MUTEX(deferred_probe_mutex);
54static LIST_HEAD(deferred_probe_pending_list);
55static LIST_HEAD(deferred_probe_active_list);
56static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
57static struct dentry *deferred_devices;
58static bool initcalls_done;
59
60/* Save the async probe drivers' name from kernel cmdline */
61#define ASYNC_DRV_NAMES_MAX_LEN 256
62static 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 */
69static bool defer_all_probes;
70
71/*
72 * deferred_probe_work_func() - Retry probing devices in the active list.
73 */
74static 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}
121static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
122
123void 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
133void 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
143static 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 */
162static 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 */
190void 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 */
203void 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 */
212static 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}
225DEFINE_SHOW_ATTRIBUTE(deferred_devs);
226
227static int deferred_probe_timeout = -1;
228static int __init deferred_probe_timeout_setup(char *str)
229{
230 int timeout;
231
232 if (!kstrtoint(str, 10, &timeout))
233 deferred_probe_timeout = timeout;
234 return 1;
235}
236__setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
237
238/**
239 * driver_deferred_probe_check_state() - Check deferred probe state
240 * @dev: device to check
241 *
242 * Returns -ENODEV if init is done and all built-in drivers have had a chance
243 * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug
244 * timeout has expired, or -EPROBE_DEFER if none of those conditions are met.
245 *
246 * Drivers or subsystems can opt-in to calling this function instead of directly
247 * returning -EPROBE_DEFER.
248 */
249int driver_deferred_probe_check_state(struct device *dev)
250{
251 if (initcalls_done) {
252 if (!deferred_probe_timeout) {
253 dev_WARN(dev, "deferred probe timeout, ignoring dependency");
254 return -ETIMEDOUT;
255 }
256 dev_warn(dev, "ignoring dependency for device, assuming no driver");
257 return -ENODEV;
258 }
259 return -EPROBE_DEFER;
260}
261
262static void deferred_probe_timeout_work_func(struct work_struct *work)
263{
264 struct device_private *private, *p;
265
266 deferred_probe_timeout = 0;
267 driver_deferred_probe_trigger();
268 flush_work(&deferred_probe_work);
269
270 list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe)
271 dev_info(private->device, "deferred probe pending");
272}
273static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
274
275/**
276 * deferred_probe_initcall() - Enable probing of deferred devices
277 *
278 * We don't want to get in the way when the bulk of drivers are getting probed.
279 * Instead, this initcall makes sure that deferred probing is delayed until
280 * late_initcall time.
281 */
282static int deferred_probe_initcall(void)
283{
284 deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
285 NULL, &deferred_devs_fops);
286
287 driver_deferred_probe_enable = true;
288 driver_deferred_probe_trigger();
289 /* Sort as many dependencies as possible before exiting initcalls */
290 flush_work(&deferred_probe_work);
291 initcalls_done = true;
292
293 /*
294 * Trigger deferred probe again, this time we won't defer anything
295 * that is optional
296 */
297 driver_deferred_probe_trigger();
298 flush_work(&deferred_probe_work);
299
300 if (deferred_probe_timeout > 0) {
301 schedule_delayed_work(&deferred_probe_timeout_work,
302 deferred_probe_timeout * HZ);
303 }
304 return 0;
305}
306late_initcall(deferred_probe_initcall);
307
308static void __exit deferred_probe_exit(void)
309{
310 debugfs_remove_recursive(deferred_devices);
311}
312__exitcall(deferred_probe_exit);
313
314/**
315 * device_is_bound() - Check if device is bound to a driver
316 * @dev: device to check
317 *
318 * Returns true if passed device has already finished probing successfully
319 * against a driver.
320 *
321 * This function must be called with the device lock held.
322 */
323bool device_is_bound(struct device *dev)
324{
325 return dev->p && klist_node_attached(&dev->p->knode_driver);
326}
327
328static void driver_bound(struct device *dev)
329{
330 if (device_is_bound(dev)) {
331 printk(KERN_WARNING "%s: device %s already bound\n",
332 __func__, kobject_name(&dev->kobj));
333 return;
334 }
335
336 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
337 __func__, dev_name(dev));
338
339 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
340 device_links_driver_bound(dev);
341
342 device_pm_check_callbacks(dev);
343
344 /*
345 * Make sure the device is no longer in one of the deferred lists and
346 * kick off retrying all pending devices
347 */
348 driver_deferred_probe_del(dev);
349 driver_deferred_probe_trigger();
350
351 if (dev->bus)
352 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
353 BUS_NOTIFY_BOUND_DRIVER, dev);
354
355 kobject_uevent(&dev->kobj, KOBJ_BIND);
356}
357
358static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
359 const char *buf, size_t count)
360{
361 device_lock(dev);
362 dev->driver->coredump(dev);
363 device_unlock(dev);
364
365 return count;
366}
367static DEVICE_ATTR_WO(coredump);
368
369static int driver_sysfs_add(struct device *dev)
370{
371 int ret;
372
373 if (dev->bus)
374 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
375 BUS_NOTIFY_BIND_DRIVER, dev);
376
377 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
378 kobject_name(&dev->kobj));
379 if (ret)
380 goto fail;
381
382 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
383 "driver");
384 if (ret)
385 goto rm_dev;
386
387 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
388 !device_create_file(dev, &dev_attr_coredump))
389 return 0;
390
391 sysfs_remove_link(&dev->kobj, "driver");
392
393rm_dev:
394 sysfs_remove_link(&dev->driver->p->kobj,
395 kobject_name(&dev->kobj));
396
397fail:
398 return ret;
399}
400
401static void driver_sysfs_remove(struct device *dev)
402{
403 struct device_driver *drv = dev->driver;
404
405 if (drv) {
406 if (drv->coredump)
407 device_remove_file(dev, &dev_attr_coredump);
408 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
409 sysfs_remove_link(&dev->kobj, "driver");
410 }
411}
412
413/**
414 * device_bind_driver - bind a driver to one device.
415 * @dev: device.
416 *
417 * Allow manual attachment of a driver to a device.
418 * Caller must have already set @dev->driver.
419 *
420 * Note that this does not modify the bus reference count
421 * nor take the bus's rwsem. Please verify those are accounted
422 * for before calling this. (It is ok to call with no other effort
423 * from a driver's probe() method.)
424 *
425 * This function must be called with the device lock held.
426 */
427int device_bind_driver(struct device *dev)
428{
429 int ret;
430
431 ret = driver_sysfs_add(dev);
432 if (!ret)
433 driver_bound(dev);
434 else if (dev->bus)
435 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
436 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
437 return ret;
438}
439EXPORT_SYMBOL_GPL(device_bind_driver);
440
441static atomic_t probe_count = ATOMIC_INIT(0);
442static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
443
444static void driver_deferred_probe_add_trigger(struct device *dev,
445 int local_trigger_count)
446{
447 driver_deferred_probe_add(dev);
448 /* Did a trigger occur while probing? Need to re-trigger if yes */
449 if (local_trigger_count != atomic_read(&deferred_trigger_count))
450 driver_deferred_probe_trigger();
451}
452
453static int really_probe(struct device *dev, struct device_driver *drv)
454{
455 int ret = -EPROBE_DEFER;
456 int local_trigger_count = atomic_read(&deferred_trigger_count);
457 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
458 !drv->suppress_bind_attrs;
459
460 if (defer_all_probes) {
461 /*
462 * Value of defer_all_probes can be set only by
463 * device_block_probing() which, in turn, will call
464 * wait_for_device_probe() right after that to avoid any races.
465 */
466 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
467 driver_deferred_probe_add(dev);
468 return ret;
469 }
470
471 ret = device_links_check_suppliers(dev);
472 if (ret == -EPROBE_DEFER)
473 driver_deferred_probe_add_trigger(dev, local_trigger_count);
474 if (ret)
475 return ret;
476
477 atomic_inc(&probe_count);
478 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
479 drv->bus->name, __func__, drv->name, dev_name(dev));
480 WARN_ON(!list_empty(&dev->devres_head));
481
482re_probe:
483 dev->driver = drv;
484
485 /* If using pinctrl, bind pins now before probing */
486 ret = pinctrl_bind_pins(dev);
487 if (ret)
488 goto pinctrl_bind_failed;
489
490 if (dev->bus->dma_configure) {
491 ret = dev->bus->dma_configure(dev);
492 if (ret)
493 goto dma_failed;
494 }
495
496 if (driver_sysfs_add(dev)) {
497 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
498 __func__, dev_name(dev));
499 goto probe_failed;
500 }
501
502 if (dev->pm_domain && dev->pm_domain->activate) {
503 ret = dev->pm_domain->activate(dev);
504 if (ret)
505 goto probe_failed;
506 }
507
508 if (dev->bus->probe) {
509 ret = dev->bus->probe(dev);
510 if (ret)
511 goto probe_failed;
512 } else if (drv->probe) {
513 ret = drv->probe(dev);
514 if (ret)
515 goto probe_failed;
516 }
517
518 if (test_remove) {
519 test_remove = false;
520
521 if (dev->bus->remove)
522 dev->bus->remove(dev);
523 else if (drv->remove)
524 drv->remove(dev);
525
526 devres_release_all(dev);
527 driver_sysfs_remove(dev);
528 dev->driver = NULL;
529 dev_set_drvdata(dev, NULL);
530 if (dev->pm_domain && dev->pm_domain->dismiss)
531 dev->pm_domain->dismiss(dev);
532 pm_runtime_reinit(dev);
533
534 goto re_probe;
535 }
536
537 pinctrl_init_done(dev);
538
539 if (dev->pm_domain && dev->pm_domain->sync)
540 dev->pm_domain->sync(dev);
541
542 driver_bound(dev);
543 ret = 1;
544 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
545 drv->bus->name, __func__, dev_name(dev), drv->name);
546 goto done;
547
548probe_failed:
549 arch_teardown_dma_ops(dev);
550dma_failed:
551 if (dev->bus)
552 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
553 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
554pinctrl_bind_failed:
555 device_links_no_driver(dev);
556 devres_release_all(dev);
557 driver_sysfs_remove(dev);
558 dev->driver = NULL;
559 dev_set_drvdata(dev, NULL);
560 if (dev->pm_domain && dev->pm_domain->dismiss)
561 dev->pm_domain->dismiss(dev);
562 pm_runtime_reinit(dev);
563 dev_pm_set_driver_flags(dev, 0);
564
565 switch (ret) {
566 case -EPROBE_DEFER:
567 /* Driver requested deferred probing */
568 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
569 driver_deferred_probe_add_trigger(dev, local_trigger_count);
570 break;
571 case -ENODEV:
572 case -ENXIO:
573 pr_debug("%s: probe of %s rejects match %d\n",
574 drv->name, dev_name(dev), ret);
575 break;
576 default:
577 /* driver matched but the probe failed */
578 printk(KERN_WARNING
579 "%s: probe of %s failed with error %d\n",
580 drv->name, dev_name(dev), ret);
581 }
582 /*
583 * Ignore errors returned by ->probe so that the next driver can try
584 * its luck.
585 */
586 ret = 0;
587done:
588 atomic_dec(&probe_count);
589 wake_up(&probe_waitqueue);
590 return ret;
591}
592
593/*
594 * For initcall_debug, show the driver probe time.
595 */
596static int really_probe_debug(struct device *dev, struct device_driver *drv)
597{
598 ktime_t calltime, delta, rettime;
599 int ret;
600
601 calltime = ktime_get();
602 ret = really_probe(dev, drv);
603 rettime = ktime_get();
604 delta = ktime_sub(rettime, calltime);
605 printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
606 dev_name(dev), ret, (s64) ktime_to_us(delta));
607 return ret;
608}
609
610/**
611 * driver_probe_done
612 * Determine if the probe sequence is finished or not.
613 *
614 * Should somehow figure out how to use a semaphore, not an atomic variable...
615 */
616int driver_probe_done(void)
617{
618 pr_debug("%s: probe_count = %d\n", __func__,
619 atomic_read(&probe_count));
620 if (atomic_read(&probe_count))
621 return -EBUSY;
622 return 0;
623}
624
625/**
626 * wait_for_device_probe
627 * Wait for device probing to be completed.
628 */
629void wait_for_device_probe(void)
630{
631 /* wait for the deferred probe workqueue to finish */
632 flush_work(&deferred_probe_work);
633
634 /* wait for the known devices to complete their probing */
635 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
636 async_synchronize_full();
637}
638EXPORT_SYMBOL_GPL(wait_for_device_probe);
639
640/**
641 * driver_probe_device - attempt to bind device & driver together
642 * @drv: driver to bind a device to
643 * @dev: device to try to bind to the driver
644 *
645 * This function returns -ENODEV if the device is not registered,
646 * 1 if the device is bound successfully and 0 otherwise.
647 *
648 * This function must be called with @dev lock held. When called for a
649 * USB interface, @dev->parent lock must be held as well.
650 *
651 * If the device has a parent, runtime-resume the parent before driver probing.
652 */
653int driver_probe_device(struct device_driver *drv, struct device *dev)
654{
655 int ret = 0;
656
657 if (!device_is_registered(dev))
658 return -ENODEV;
659
660 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
661 drv->bus->name, __func__, dev_name(dev), drv->name);
662
663 pm_runtime_get_suppliers(dev);
664 if (dev->parent)
665 pm_runtime_get_sync(dev->parent);
666
667 pm_runtime_barrier(dev);
668 if (initcall_debug)
669 ret = really_probe_debug(dev, drv);
670 else
671 ret = really_probe(dev, drv);
672 pm_request_idle(dev);
673
674 if (dev->parent)
675 pm_runtime_put(dev->parent);
676
677 pm_runtime_put_suppliers(dev);
678 return ret;
679}
680
681static inline bool cmdline_requested_async_probing(const char *drv_name)
682{
683 return parse_option_str(async_probe_drv_names, drv_name);
684}
685
686/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
687static int __init save_async_options(char *buf)
688{
689 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
690 printk(KERN_WARNING
691 "Too long list of driver names for 'driver_async_probe'!\n");
692
693 strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
694 return 0;
695}
696__setup("driver_async_probe=", save_async_options);
697
698bool driver_allows_async_probing(struct device_driver *drv)
699{
700 switch (drv->probe_type) {
701 case PROBE_PREFER_ASYNCHRONOUS:
702 return true;
703
704 case PROBE_FORCE_SYNCHRONOUS:
705 return false;
706
707 default:
708 if (cmdline_requested_async_probing(drv->name))
709 return true;
710
711 if (module_requested_async_probing(drv->owner))
712 return true;
713
714 return false;
715 }
716}
717
718struct device_attach_data {
719 struct device *dev;
720
721 /*
722 * Indicates whether we are are considering asynchronous probing or
723 * not. Only initial binding after device or driver registration
724 * (including deferral processing) may be done asynchronously, the
725 * rest is always synchronous, as we expect it is being done by
726 * request from userspace.
727 */
728 bool check_async;
729
730 /*
731 * Indicates if we are binding synchronous or asynchronous drivers.
732 * When asynchronous probing is enabled we'll execute 2 passes
733 * over drivers: first pass doing synchronous probing and second
734 * doing asynchronous probing (if synchronous did not succeed -
735 * most likely because there was no driver requiring synchronous
736 * probing - and we found asynchronous driver during first pass).
737 * The 2 passes are done because we can't shoot asynchronous
738 * probe for given device and driver from bus_for_each_drv() since
739 * driver pointer is not guaranteed to stay valid once
740 * bus_for_each_drv() iterates to the next driver on the bus.
741 */
742 bool want_async;
743
744 /*
745 * We'll set have_async to 'true' if, while scanning for matching
746 * driver, we'll encounter one that requests asynchronous probing.
747 */
748 bool have_async;
749};
750
751static int __device_attach_driver(struct device_driver *drv, void *_data)
752{
753 struct device_attach_data *data = _data;
754 struct device *dev = data->dev;
755 bool async_allowed;
756 int ret;
757
758 ret = driver_match_device(drv, dev);
759 if (ret == 0) {
760 /* no match */
761 return 0;
762 } else if (ret == -EPROBE_DEFER) {
763 dev_dbg(dev, "Device match requests probe deferral\n");
764 driver_deferred_probe_add(dev);
765 } else if (ret < 0) {
766 dev_dbg(dev, "Bus failed to match device: %d", ret);
767 return ret;
768 } /* ret > 0 means positive match */
769
770 async_allowed = driver_allows_async_probing(drv);
771
772 if (async_allowed)
773 data->have_async = true;
774
775 if (data->check_async && async_allowed != data->want_async)
776 return 0;
777
778 return driver_probe_device(drv, dev);
779}
780
781static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
782{
783 struct device *dev = _dev;
784 struct device_attach_data data = {
785 .dev = dev,
786 .check_async = true,
787 .want_async = true,
788 };
789
790 device_lock(dev);
791
792 /*
793 * Check if device has already been removed or claimed. This may
794 * happen with driver loading, device discovery/registration,
795 * and deferred probe processing happens all at once with
796 * multiple threads.
797 */
798 if (dev->p->dead || dev->driver)
799 goto out_unlock;
800
801 if (dev->parent)
802 pm_runtime_get_sync(dev->parent);
803
804 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
805 dev_dbg(dev, "async probe completed\n");
806
807 pm_request_idle(dev);
808
809 if (dev->parent)
810 pm_runtime_put(dev->parent);
811out_unlock:
812 device_unlock(dev);
813
814 put_device(dev);
815}
816
817static int __device_attach(struct device *dev, bool allow_async)
818{
819 int ret = 0;
820
821 device_lock(dev);
822 if (dev->driver) {
823 if (device_is_bound(dev)) {
824 ret = 1;
825 goto out_unlock;
826 }
827 ret = device_bind_driver(dev);
828 if (ret == 0)
829 ret = 1;
830 else {
831 dev->driver = NULL;
832 ret = 0;
833 }
834 } else {
835 struct device_attach_data data = {
836 .dev = dev,
837 .check_async = allow_async,
838 .want_async = false,
839 };
840
841 if (dev->parent)
842 pm_runtime_get_sync(dev->parent);
843
844 ret = bus_for_each_drv(dev->bus, NULL, &data,
845 __device_attach_driver);
846 if (!ret && allow_async && data.have_async) {
847 /*
848 * If we could not find appropriate driver
849 * synchronously and we are allowed to do
850 * async probes and there are drivers that
851 * want to probe asynchronously, we'll
852 * try them.
853 */
854 dev_dbg(dev, "scheduling asynchronous probe\n");
855 get_device(dev);
856 async_schedule_dev(__device_attach_async_helper, dev);
857 } else {
858 pm_request_idle(dev);
859 }
860
861 if (dev->parent)
862 pm_runtime_put(dev->parent);
863 }
864out_unlock:
865 device_unlock(dev);
866 return ret;
867}
868
869/**
870 * device_attach - try to attach device to a driver.
871 * @dev: device.
872 *
873 * Walk the list of drivers that the bus has and call
874 * driver_probe_device() for each pair. If a compatible
875 * pair is found, break out and return.
876 *
877 * Returns 1 if the device was bound to a driver;
878 * 0 if no matching driver was found;
879 * -ENODEV if the device is not registered.
880 *
881 * When called for a USB interface, @dev->parent lock must be held.
882 */
883int device_attach(struct device *dev)
884{
885 return __device_attach(dev, false);
886}
887EXPORT_SYMBOL_GPL(device_attach);
888
889void device_initial_probe(struct device *dev)
890{
891 __device_attach(dev, true);
892}
893
894/*
895 * __device_driver_lock - acquire locks needed to manipulate dev->drv
896 * @dev: Device we will update driver info for
897 * @parent: Parent device. Needed if the bus requires parent lock
898 *
899 * This function will take the required locks for manipulating dev->drv.
900 * Normally this will just be the @dev lock, but when called for a USB
901 * interface, @parent lock will be held as well.
902 */
903static void __device_driver_lock(struct device *dev, struct device *parent)
904{
905 if (parent && dev->bus->need_parent_lock)
906 device_lock(parent);
907 device_lock(dev);
908}
909
910/*
911 * __device_driver_unlock - release locks needed to manipulate dev->drv
912 * @dev: Device we will update driver info for
913 * @parent: Parent device. Needed if the bus requires parent lock
914 *
915 * This function will release the required locks for manipulating dev->drv.
916 * Normally this will just be the the @dev lock, but when called for a
917 * USB interface, @parent lock will be released as well.
918 */
919static void __device_driver_unlock(struct device *dev, struct device *parent)
920{
921 device_unlock(dev);
922 if (parent && dev->bus->need_parent_lock)
923 device_unlock(parent);
924}
925
926/**
927 * device_driver_attach - attach a specific driver to a specific device
928 * @drv: Driver to attach
929 * @dev: Device to attach it to
930 *
931 * Manually attach driver to a device. Will acquire both @dev lock and
932 * @dev->parent lock if needed.
933 */
934int device_driver_attach(struct device_driver *drv, struct device *dev)
935{
936 int ret = 0;
937
938 __device_driver_lock(dev, dev->parent);
939
940 /*
941 * If device has been removed or someone has already successfully
942 * bound a driver before us just skip the driver probe call.
943 */
944 if (!dev->p->dead && !dev->driver)
945 ret = driver_probe_device(drv, dev);
946
947 __device_driver_unlock(dev, dev->parent);
948
949 return ret;
950}
951
952static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
953{
954 struct device *dev = _dev;
955 struct device_driver *drv;
956 int ret = 0;
957
958 __device_driver_lock(dev, dev->parent);
959
960 drv = dev->p->async_driver;
961
962 /*
963 * If device has been removed or someone has already successfully
964 * bound a driver before us just skip the driver probe call.
965 */
966 if (!dev->p->dead && !dev->driver)
967 ret = driver_probe_device(drv, dev);
968
969 __device_driver_unlock(dev, dev->parent);
970
971 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
972
973 put_device(dev);
974}
975
976static int __driver_attach(struct device *dev, void *data)
977{
978 struct device_driver *drv = data;
979 int ret;
980
981 /*
982 * Lock device and try to bind to it. We drop the error
983 * here and always return 0, because we need to keep trying
984 * to bind to devices and some drivers will return an error
985 * simply if it didn't support the device.
986 *
987 * driver_probe_device() will spit a warning if there
988 * is an error.
989 */
990
991 ret = driver_match_device(drv, dev);
992 if (ret == 0) {
993 /* no match */
994 return 0;
995 } else if (ret == -EPROBE_DEFER) {
996 dev_dbg(dev, "Device match requests probe deferral\n");
997 driver_deferred_probe_add(dev);
998 } else if (ret < 0) {
999 dev_dbg(dev, "Bus failed to match device: %d", ret);
1000 return ret;
1001 } /* ret > 0 means positive match */
1002
1003 if (driver_allows_async_probing(drv)) {
1004 /*
1005 * Instead of probing the device synchronously we will
1006 * probe it asynchronously to allow for more parallelism.
1007 *
1008 * We only take the device lock here in order to guarantee
1009 * that the dev->driver and async_driver fields are protected
1010 */
1011 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1012 device_lock(dev);
1013 if (!dev->driver) {
1014 get_device(dev);
1015 dev->p->async_driver = drv;
1016 async_schedule_dev(__driver_attach_async_helper, dev);
1017 }
1018 device_unlock(dev);
1019 return 0;
1020 }
1021
1022 device_driver_attach(drv, dev);
1023
1024 return 0;
1025}
1026
1027/**
1028 * driver_attach - try to bind driver to devices.
1029 * @drv: driver.
1030 *
1031 * Walk the list of devices that the bus has on it and try to
1032 * match the driver with each one. If driver_probe_device()
1033 * returns 0 and the @dev->driver is set, we've found a
1034 * compatible pair.
1035 */
1036int driver_attach(struct device_driver *drv)
1037{
1038 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1039}
1040EXPORT_SYMBOL_GPL(driver_attach);
1041
1042/*
1043 * __device_release_driver() must be called with @dev lock held.
1044 * When called for a USB interface, @dev->parent lock must be held as well.
1045 */
1046static void __device_release_driver(struct device *dev, struct device *parent)
1047{
1048 struct device_driver *drv;
1049
1050 drv = dev->driver;
1051 if (drv) {
1052 while (device_links_busy(dev)) {
1053 __device_driver_unlock(dev, parent);
1054
1055 device_links_unbind_consumers(dev);
1056
1057 __device_driver_lock(dev, parent);
1058 /*
1059 * A concurrent invocation of the same function might
1060 * have released the driver successfully while this one
1061 * was waiting, so check for that.
1062 */
1063 if (dev->driver != drv)
1064 return;
1065 }
1066
1067 pm_runtime_get_sync(dev);
1068 pm_runtime_clean_up_links(dev);
1069
1070 driver_sysfs_remove(dev);
1071
1072 if (dev->bus)
1073 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1074 BUS_NOTIFY_UNBIND_DRIVER,
1075 dev);
1076
1077 pm_runtime_put_sync(dev);
1078
1079 if (dev->bus && dev->bus->remove)
1080 dev->bus->remove(dev);
1081 else if (drv->remove)
1082 drv->remove(dev);
1083
1084 device_links_driver_cleanup(dev);
1085
1086 devres_release_all(dev);
1087 arch_teardown_dma_ops(dev);
1088 dev->driver = NULL;
1089 dev_set_drvdata(dev, NULL);
1090 if (dev->pm_domain && dev->pm_domain->dismiss)
1091 dev->pm_domain->dismiss(dev);
1092 pm_runtime_reinit(dev);
1093 dev_pm_set_driver_flags(dev, 0);
1094
1095 klist_remove(&dev->p->knode_driver);
1096 device_pm_check_callbacks(dev);
1097 if (dev->bus)
1098 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1099 BUS_NOTIFY_UNBOUND_DRIVER,
1100 dev);
1101
1102 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1103 }
1104}
1105
1106void device_release_driver_internal(struct device *dev,
1107 struct device_driver *drv,
1108 struct device *parent)
1109{
1110 __device_driver_lock(dev, parent);
1111
1112 if (!drv || drv == dev->driver)
1113 __device_release_driver(dev, parent);
1114
1115 __device_driver_unlock(dev, parent);
1116}
1117
1118/**
1119 * device_release_driver - manually detach device from driver.
1120 * @dev: device.
1121 *
1122 * Manually detach device from driver.
1123 * When called for a USB interface, @dev->parent lock must be held.
1124 *
1125 * If this function is to be called with @dev->parent lock held, ensure that
1126 * the device's consumers are unbound in advance or that their locks can be
1127 * acquired under the @dev->parent lock.
1128 */
1129void device_release_driver(struct device *dev)
1130{
1131 /*
1132 * If anyone calls device_release_driver() recursively from
1133 * within their ->remove callback for the same device, they
1134 * will deadlock right here.
1135 */
1136 device_release_driver_internal(dev, NULL, NULL);
1137}
1138EXPORT_SYMBOL_GPL(device_release_driver);
1139
1140/**
1141 * device_driver_detach - detach driver from a specific device
1142 * @dev: device to detach driver from
1143 *
1144 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1145 * lock if needed.
1146 */
1147void device_driver_detach(struct device *dev)
1148{
1149 device_release_driver_internal(dev, NULL, dev->parent);
1150}
1151
1152/**
1153 * driver_detach - detach driver from all devices it controls.
1154 * @drv: driver.
1155 */
1156void driver_detach(struct device_driver *drv)
1157{
1158 struct device_private *dev_prv;
1159 struct device *dev;
1160
1161 if (driver_allows_async_probing(drv))
1162 async_synchronize_full();
1163
1164 for (;;) {
1165 spin_lock(&drv->p->klist_devices.k_lock);
1166 if (list_empty(&drv->p->klist_devices.k_list)) {
1167 spin_unlock(&drv->p->klist_devices.k_lock);
1168 break;
1169 }
1170 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
1171 struct device_private,
1172 knode_driver.n_node);
1173 dev = dev_prv->device;
1174 get_device(dev);
1175 spin_unlock(&drv->p->klist_devices.k_lock);
1176 device_release_driver_internal(dev, drv, dev->parent);
1177 put_device(dev);
1178 }
1179}
1180