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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/debugfs.h>
20#include <linux/device.h>
21#include <linux/delay.h>
22#include <linux/dma-map-ops.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#include <linux/slab.h>
31
32#include "base.h"
33#include "power/power.h"
34
35/*
36 * Deferred Probe infrastructure.
37 *
38 * Sometimes driver probe order matters, but the kernel doesn't always have
39 * dependency information which means some drivers will get probed before a
40 * resource it depends on is available. For example, an SDHCI driver may
41 * first need a GPIO line from an i2c GPIO controller before it can be
42 * initialized. If a required resource is not available yet, a driver can
43 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
44 *
45 * Deferred probe maintains two lists of devices, a pending list and an active
46 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
47 * pending list. A successful driver probe will trigger moving all devices
48 * from the pending to the active list so that the workqueue will eventually
49 * retry them.
50 *
51 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
52 * of the (struct device*)->p->deferred_probe pointers are manipulated
53 */
54static DEFINE_MUTEX(deferred_probe_mutex);
55static LIST_HEAD(deferred_probe_pending_list);
56static LIST_HEAD(deferred_probe_active_list);
57static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
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];
63static bool async_probe_default;
64
65/*
66 * In some cases, like suspend to RAM or hibernation, It might be reasonable
67 * to prohibit probing of devices as it could be unsafe.
68 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
69 */
70static bool defer_all_probes;
71
72static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
73{
74 kfree(dev->p->deferred_probe_reason);
75 dev->p->deferred_probe_reason = reason;
76}
77
78/*
79 * deferred_probe_work_func() - Retry probing devices in the active list.
80 */
81static void deferred_probe_work_func(struct work_struct *work)
82{
83 struct device *dev;
84 struct device_private *private;
85 /*
86 * This block processes every device in the deferred 'active' list.
87 * Each device is removed from the active list and passed to
88 * bus_probe_device() to re-attempt the probe. The loop continues
89 * until every device in the active list is removed and retried.
90 *
91 * Note: Once the device is removed from the list and the mutex is
92 * released, it is possible for the device get freed by another thread
93 * and cause a illegal pointer dereference. This code uses
94 * get/put_device() to ensure the device structure cannot disappear
95 * from under our feet.
96 */
97 mutex_lock(&deferred_probe_mutex);
98 while (!list_empty(&deferred_probe_active_list)) {
99 private = list_first_entry(&deferred_probe_active_list,
100 typeof(*dev->p), deferred_probe);
101 dev = private->device;
102 list_del_init(&private->deferred_probe);
103
104 get_device(dev);
105
106 __device_set_deferred_probe_reason(dev, NULL);
107
108 /*
109 * Drop the mutex while probing each device; the probe path may
110 * manipulate the deferred list
111 */
112 mutex_unlock(&deferred_probe_mutex);
113
114 /*
115 * Force the device to the end of the dpm_list since
116 * the PM code assumes that the order we add things to
117 * the list is a good order for suspend but deferred
118 * probe makes that very unsafe.
119 */
120 device_pm_move_to_tail(dev);
121
122 dev_dbg(dev, "Retrying from deferred list\n");
123 bus_probe_device(dev);
124 mutex_lock(&deferred_probe_mutex);
125
126 put_device(dev);
127 }
128 mutex_unlock(&deferred_probe_mutex);
129}
130static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
131
132void driver_deferred_probe_add(struct device *dev)
133{
134 if (!dev->can_match)
135 return;
136
137 mutex_lock(&deferred_probe_mutex);
138 if (list_empty(&dev->p->deferred_probe)) {
139 dev_dbg(dev, "Added to deferred list\n");
140 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
141 }
142 mutex_unlock(&deferred_probe_mutex);
143}
144
145void driver_deferred_probe_del(struct device *dev)
146{
147 mutex_lock(&deferred_probe_mutex);
148 if (!list_empty(&dev->p->deferred_probe)) {
149 dev_dbg(dev, "Removed from deferred list\n");
150 list_del_init(&dev->p->deferred_probe);
151 __device_set_deferred_probe_reason(dev, NULL);
152 }
153 mutex_unlock(&deferred_probe_mutex);
154}
155
156static bool driver_deferred_probe_enable;
157/**
158 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
159 *
160 * This functions moves all devices from the pending list to the active
161 * list and schedules the deferred probe workqueue to process them. It
162 * should be called anytime a driver is successfully bound to a device.
163 *
164 * Note, there is a race condition in multi-threaded probe. In the case where
165 * more than one device is probing at the same time, it is possible for one
166 * probe to complete successfully while another is about to defer. If the second
167 * depends on the first, then it will get put on the pending list after the
168 * trigger event has already occurred and will be stuck there.
169 *
170 * The atomic 'deferred_trigger_count' is used to determine if a successful
171 * trigger has occurred in the midst of probing a driver. If the trigger count
172 * changes in the midst of a probe, then deferred processing should be triggered
173 * again.
174 */
175void driver_deferred_probe_trigger(void)
176{
177 if (!driver_deferred_probe_enable)
178 return;
179
180 /*
181 * A successful probe means that all the devices in the pending list
182 * should be triggered to be reprobed. Move all the deferred devices
183 * into the active list so they can be retried by the workqueue
184 */
185 mutex_lock(&deferred_probe_mutex);
186 atomic_inc(&deferred_trigger_count);
187 list_splice_tail_init(&deferred_probe_pending_list,
188 &deferred_probe_active_list);
189 mutex_unlock(&deferred_probe_mutex);
190
191 /*
192 * Kick the re-probe thread. It may already be scheduled, but it is
193 * safe to kick it again.
194 */
195 queue_work(system_unbound_wq, &deferred_probe_work);
196}
197
198/**
199 * device_block_probing() - Block/defer device's probes
200 *
201 * It will disable probing of devices and defer their probes instead.
202 */
203void device_block_probing(void)
204{
205 defer_all_probes = true;
206 /* sync with probes to avoid races. */
207 wait_for_device_probe();
208}
209
210/**
211 * device_unblock_probing() - Unblock/enable device's probes
212 *
213 * It will restore normal behavior and trigger re-probing of deferred
214 * devices.
215 */
216void device_unblock_probing(void)
217{
218 defer_all_probes = false;
219 driver_deferred_probe_trigger();
220}
221
222/**
223 * device_set_deferred_probe_reason() - Set defer probe reason message for device
224 * @dev: the pointer to the struct device
225 * @vaf: the pointer to va_format structure with message
226 */
227void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
228{
229 const char *drv = dev_driver_string(dev);
230 char *reason;
231
232 mutex_lock(&deferred_probe_mutex);
233
234 reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
235 __device_set_deferred_probe_reason(dev, reason);
236
237 mutex_unlock(&deferred_probe_mutex);
238}
239
240/*
241 * deferred_devs_show() - Show the devices in the deferred probe pending list.
242 */
243static int deferred_devs_show(struct seq_file *s, void *data)
244{
245 struct device_private *curr;
246
247 mutex_lock(&deferred_probe_mutex);
248
249 list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
250 seq_printf(s, "%s\t%s", dev_name(curr->device),
251 curr->device->p->deferred_probe_reason ?: "\n");
252
253 mutex_unlock(&deferred_probe_mutex);
254
255 return 0;
256}
257DEFINE_SHOW_ATTRIBUTE(deferred_devs);
258
259#ifdef CONFIG_MODULES
260static int driver_deferred_probe_timeout = 10;
261#else
262static int driver_deferred_probe_timeout;
263#endif
264
265static int __init deferred_probe_timeout_setup(char *str)
266{
267 int timeout;
268
269 if (!kstrtoint(str, 10, &timeout))
270 driver_deferred_probe_timeout = timeout;
271 return 1;
272}
273__setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
274
275/**
276 * driver_deferred_probe_check_state() - Check deferred probe state
277 * @dev: device to check
278 *
279 * Return:
280 * * -ENODEV if initcalls have completed and modules are disabled.
281 * * -ETIMEDOUT if the deferred probe timeout was set and has expired
282 * and modules are enabled.
283 * * -EPROBE_DEFER in other cases.
284 *
285 * Drivers or subsystems can opt-in to calling this function instead of directly
286 * returning -EPROBE_DEFER.
287 */
288int driver_deferred_probe_check_state(struct device *dev)
289{
290 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
291 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
292 return -ENODEV;
293 }
294
295 if (!driver_deferred_probe_timeout && initcalls_done) {
296 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
297 return -ETIMEDOUT;
298 }
299
300 return -EPROBE_DEFER;
301}
302EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
303
304static void deferred_probe_timeout_work_func(struct work_struct *work)
305{
306 struct device_private *p;
307
308 fw_devlink_drivers_done();
309
310 driver_deferred_probe_timeout = 0;
311 driver_deferred_probe_trigger();
312 flush_work(&deferred_probe_work);
313
314 mutex_lock(&deferred_probe_mutex);
315 list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
316 dev_info(p->device, "deferred probe pending: %s", p->deferred_probe_reason ?: "(reason unknown)\n");
317 mutex_unlock(&deferred_probe_mutex);
318
319 fw_devlink_probing_done();
320}
321static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
322
323void deferred_probe_extend_timeout(void)
324{
325 /*
326 * If the work hasn't been queued yet or if the work expired, don't
327 * start a new one.
328 */
329 if (cancel_delayed_work(&deferred_probe_timeout_work)) {
330 schedule_delayed_work(&deferred_probe_timeout_work,
331 driver_deferred_probe_timeout * HZ);
332 pr_debug("Extended deferred probe timeout by %d secs\n",
333 driver_deferred_probe_timeout);
334 }
335}
336
337/**
338 * deferred_probe_initcall() - Enable probing of deferred devices
339 *
340 * We don't want to get in the way when the bulk of drivers are getting probed.
341 * Instead, this initcall makes sure that deferred probing is delayed until
342 * late_initcall time.
343 */
344static int deferred_probe_initcall(void)
345{
346 debugfs_create_file("devices_deferred", 0444, NULL, NULL,
347 &deferred_devs_fops);
348
349 driver_deferred_probe_enable = true;
350 driver_deferred_probe_trigger();
351 /* Sort as many dependencies as possible before exiting initcalls */
352 flush_work(&deferred_probe_work);
353 initcalls_done = true;
354
355 if (!IS_ENABLED(CONFIG_MODULES))
356 fw_devlink_drivers_done();
357
358 /*
359 * Trigger deferred probe again, this time we won't defer anything
360 * that is optional
361 */
362 driver_deferred_probe_trigger();
363 flush_work(&deferred_probe_work);
364
365 if (driver_deferred_probe_timeout > 0) {
366 schedule_delayed_work(&deferred_probe_timeout_work,
367 driver_deferred_probe_timeout * HZ);
368 }
369
370 if (!IS_ENABLED(CONFIG_MODULES))
371 fw_devlink_probing_done();
372
373 return 0;
374}
375late_initcall(deferred_probe_initcall);
376
377static void __exit deferred_probe_exit(void)
378{
379 debugfs_lookup_and_remove("devices_deferred", NULL);
380}
381__exitcall(deferred_probe_exit);
382
383/**
384 * device_is_bound() - Check if device is bound to a driver
385 * @dev: device to check
386 *
387 * Returns true if passed device has already finished probing successfully
388 * against a driver.
389 *
390 * This function must be called with the device lock held.
391 */
392bool device_is_bound(struct device *dev)
393{
394 return dev->p && klist_node_attached(&dev->p->knode_driver);
395}
396
397static void driver_bound(struct device *dev)
398{
399 if (device_is_bound(dev)) {
400 pr_warn("%s: device %s already bound\n",
401 __func__, kobject_name(&dev->kobj));
402 return;
403 }
404
405 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
406 __func__, dev_name(dev));
407
408 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
409 device_links_driver_bound(dev);
410
411 device_pm_check_callbacks(dev);
412
413 /*
414 * Make sure the device is no longer in one of the deferred lists and
415 * kick off retrying all pending devices
416 */
417 driver_deferred_probe_del(dev);
418 driver_deferred_probe_trigger();
419
420 bus_notify(dev, BUS_NOTIFY_BOUND_DRIVER);
421 kobject_uevent(&dev->kobj, KOBJ_BIND);
422}
423
424static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
425 const char *buf, size_t count)
426{
427 device_lock(dev);
428 dev->driver->coredump(dev);
429 device_unlock(dev);
430
431 return count;
432}
433static DEVICE_ATTR_WO(coredump);
434
435static int driver_sysfs_add(struct device *dev)
436{
437 int ret;
438
439 bus_notify(dev, BUS_NOTIFY_BIND_DRIVER);
440
441 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
442 kobject_name(&dev->kobj));
443 if (ret)
444 goto fail;
445
446 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
447 "driver");
448 if (ret)
449 goto rm_dev;
450
451 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
452 return 0;
453
454 ret = device_create_file(dev, &dev_attr_coredump);
455 if (!ret)
456 return 0;
457
458 sysfs_remove_link(&dev->kobj, "driver");
459
460rm_dev:
461 sysfs_remove_link(&dev->driver->p->kobj,
462 kobject_name(&dev->kobj));
463
464fail:
465 return ret;
466}
467
468static void driver_sysfs_remove(struct device *dev)
469{
470 struct device_driver *drv = dev->driver;
471
472 if (drv) {
473 if (drv->coredump)
474 device_remove_file(dev, &dev_attr_coredump);
475 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
476 sysfs_remove_link(&dev->kobj, "driver");
477 }
478}
479
480/**
481 * device_bind_driver - bind a driver to one device.
482 * @dev: device.
483 *
484 * Allow manual attachment of a driver to a device.
485 * Caller must have already set @dev->driver.
486 *
487 * Note that this does not modify the bus reference count.
488 * Please verify that is accounted for before calling this.
489 * (It is ok to call with no other effort from a driver's probe() method.)
490 *
491 * This function must be called with the device lock held.
492 *
493 * Callers should prefer to use device_driver_attach() instead.
494 */
495int device_bind_driver(struct device *dev)
496{
497 int ret;
498
499 ret = driver_sysfs_add(dev);
500 if (!ret) {
501 device_links_force_bind(dev);
502 driver_bound(dev);
503 }
504 else
505 bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
506 return ret;
507}
508EXPORT_SYMBOL_GPL(device_bind_driver);
509
510static atomic_t probe_count = ATOMIC_INIT(0);
511static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
512
513static ssize_t state_synced_store(struct device *dev,
514 struct device_attribute *attr,
515 const char *buf, size_t count)
516{
517 int ret = 0;
518
519 if (strcmp("1", buf))
520 return -EINVAL;
521
522 device_lock(dev);
523 if (!dev->state_synced) {
524 dev->state_synced = true;
525 dev_sync_state(dev);
526 } else {
527 ret = -EINVAL;
528 }
529 device_unlock(dev);
530
531 return ret ? ret : count;
532}
533
534static ssize_t state_synced_show(struct device *dev,
535 struct device_attribute *attr, char *buf)
536{
537 bool val;
538
539 device_lock(dev);
540 val = dev->state_synced;
541 device_unlock(dev);
542
543 return sysfs_emit(buf, "%u\n", val);
544}
545static DEVICE_ATTR_RW(state_synced);
546
547static void device_unbind_cleanup(struct device *dev)
548{
549 devres_release_all(dev);
550 arch_teardown_dma_ops(dev);
551 kfree(dev->dma_range_map);
552 dev->dma_range_map = NULL;
553 dev->driver = NULL;
554 dev_set_drvdata(dev, NULL);
555 if (dev->pm_domain && dev->pm_domain->dismiss)
556 dev->pm_domain->dismiss(dev);
557 pm_runtime_reinit(dev);
558 dev_pm_set_driver_flags(dev, 0);
559}
560
561static void device_remove(struct device *dev)
562{
563 device_remove_file(dev, &dev_attr_state_synced);
564 device_remove_groups(dev, dev->driver->dev_groups);
565
566 if (dev->bus && dev->bus->remove)
567 dev->bus->remove(dev);
568 else if (dev->driver->remove)
569 dev->driver->remove(dev);
570}
571
572static int call_driver_probe(struct device *dev, struct device_driver *drv)
573{
574 int ret = 0;
575
576 if (dev->bus->probe)
577 ret = dev->bus->probe(dev);
578 else if (drv->probe)
579 ret = drv->probe(dev);
580
581 switch (ret) {
582 case 0:
583 break;
584 case -EPROBE_DEFER:
585 /* Driver requested deferred probing */
586 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
587 break;
588 case -ENODEV:
589 case -ENXIO:
590 pr_debug("%s: probe of %s rejects match %d\n",
591 drv->name, dev_name(dev), ret);
592 break;
593 default:
594 /* driver matched but the probe failed */
595 pr_warn("%s: probe of %s failed with error %d\n",
596 drv->name, dev_name(dev), ret);
597 break;
598 }
599
600 return ret;
601}
602
603static int really_probe(struct device *dev, struct device_driver *drv)
604{
605 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
606 !drv->suppress_bind_attrs;
607 int ret, link_ret;
608
609 if (defer_all_probes) {
610 /*
611 * Value of defer_all_probes can be set only by
612 * device_block_probing() which, in turn, will call
613 * wait_for_device_probe() right after that to avoid any races.
614 */
615 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
616 return -EPROBE_DEFER;
617 }
618
619 link_ret = device_links_check_suppliers(dev);
620 if (link_ret == -EPROBE_DEFER)
621 return link_ret;
622
623 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
624 drv->bus->name, __func__, drv->name, dev_name(dev));
625 if (!list_empty(&dev->devres_head)) {
626 dev_crit(dev, "Resources present before probing\n");
627 ret = -EBUSY;
628 goto done;
629 }
630
631re_probe:
632 dev->driver = drv;
633
634 /* If using pinctrl, bind pins now before probing */
635 ret = pinctrl_bind_pins(dev);
636 if (ret)
637 goto pinctrl_bind_failed;
638
639 if (dev->bus->dma_configure) {
640 ret = dev->bus->dma_configure(dev);
641 if (ret)
642 goto pinctrl_bind_failed;
643 }
644
645 ret = driver_sysfs_add(dev);
646 if (ret) {
647 pr_err("%s: driver_sysfs_add(%s) failed\n",
648 __func__, dev_name(dev));
649 goto sysfs_failed;
650 }
651
652 if (dev->pm_domain && dev->pm_domain->activate) {
653 ret = dev->pm_domain->activate(dev);
654 if (ret)
655 goto probe_failed;
656 }
657
658 ret = call_driver_probe(dev, drv);
659 if (ret) {
660 /*
661 * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
662 * device might actually probe properly once some of its missing
663 * suppliers have probed. So, treat this as if the driver
664 * returned -EPROBE_DEFER.
665 */
666 if (link_ret == -EAGAIN)
667 ret = -EPROBE_DEFER;
668
669 /*
670 * Return probe errors as positive values so that the callers
671 * can distinguish them from other errors.
672 */
673 ret = -ret;
674 goto probe_failed;
675 }
676
677 ret = device_add_groups(dev, drv->dev_groups);
678 if (ret) {
679 dev_err(dev, "device_add_groups() failed\n");
680 goto dev_groups_failed;
681 }
682
683 if (dev_has_sync_state(dev)) {
684 ret = device_create_file(dev, &dev_attr_state_synced);
685 if (ret) {
686 dev_err(dev, "state_synced sysfs add failed\n");
687 goto dev_sysfs_state_synced_failed;
688 }
689 }
690
691 if (test_remove) {
692 test_remove = false;
693
694 device_remove(dev);
695 driver_sysfs_remove(dev);
696 if (dev->bus && dev->bus->dma_cleanup)
697 dev->bus->dma_cleanup(dev);
698 device_unbind_cleanup(dev);
699
700 goto re_probe;
701 }
702
703 pinctrl_init_done(dev);
704
705 if (dev->pm_domain && dev->pm_domain->sync)
706 dev->pm_domain->sync(dev);
707
708 driver_bound(dev);
709 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
710 drv->bus->name, __func__, dev_name(dev), drv->name);
711 goto done;
712
713dev_sysfs_state_synced_failed:
714dev_groups_failed:
715 device_remove(dev);
716probe_failed:
717 driver_sysfs_remove(dev);
718sysfs_failed:
719 bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
720 if (dev->bus && dev->bus->dma_cleanup)
721 dev->bus->dma_cleanup(dev);
722pinctrl_bind_failed:
723 device_links_no_driver(dev);
724 device_unbind_cleanup(dev);
725done:
726 return ret;
727}
728
729/*
730 * For initcall_debug, show the driver probe time.
731 */
732static int really_probe_debug(struct device *dev, struct device_driver *drv)
733{
734 ktime_t calltime, rettime;
735 int ret;
736
737 calltime = ktime_get();
738 ret = really_probe(dev, drv);
739 rettime = ktime_get();
740 /*
741 * Don't change this to pr_debug() because that requires
742 * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the
743 * kernel commandline to print this all the time at the debug level.
744 */
745 printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
746 dev_name(dev), ret, ktime_us_delta(rettime, calltime));
747 return ret;
748}
749
750/**
751 * driver_probe_done
752 * Determine if the probe sequence is finished or not.
753 *
754 * Should somehow figure out how to use a semaphore, not an atomic variable...
755 */
756bool __init driver_probe_done(void)
757{
758 int local_probe_count = atomic_read(&probe_count);
759
760 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
761 return !local_probe_count;
762}
763
764/**
765 * wait_for_device_probe
766 * Wait for device probing to be completed.
767 */
768void wait_for_device_probe(void)
769{
770 /* wait for the deferred probe workqueue to finish */
771 flush_work(&deferred_probe_work);
772
773 /* wait for the known devices to complete their probing */
774 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
775 async_synchronize_full();
776}
777EXPORT_SYMBOL_GPL(wait_for_device_probe);
778
779static int __driver_probe_device(struct device_driver *drv, struct device *dev)
780{
781 int ret = 0;
782
783 if (dev->p->dead || !device_is_registered(dev))
784 return -ENODEV;
785 if (dev->driver)
786 return -EBUSY;
787
788 dev->can_match = true;
789 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
790 drv->bus->name, __func__, dev_name(dev), drv->name);
791
792 pm_runtime_get_suppliers(dev);
793 if (dev->parent)
794 pm_runtime_get_sync(dev->parent);
795
796 pm_runtime_barrier(dev);
797 if (initcall_debug)
798 ret = really_probe_debug(dev, drv);
799 else
800 ret = really_probe(dev, drv);
801 pm_request_idle(dev);
802
803 if (dev->parent)
804 pm_runtime_put(dev->parent);
805
806 pm_runtime_put_suppliers(dev);
807 return ret;
808}
809
810/**
811 * driver_probe_device - attempt to bind device & driver together
812 * @drv: driver to bind a device to
813 * @dev: device to try to bind to the driver
814 *
815 * This function returns -ENODEV if the device is not registered, -EBUSY if it
816 * already has a driver, 0 if the device is bound successfully and a positive
817 * (inverted) error code for failures from the ->probe method.
818 *
819 * This function must be called with @dev lock held. When called for a
820 * USB interface, @dev->parent lock must be held as well.
821 *
822 * If the device has a parent, runtime-resume the parent before driver probing.
823 */
824static int driver_probe_device(struct device_driver *drv, struct device *dev)
825{
826 int trigger_count = atomic_read(&deferred_trigger_count);
827 int ret;
828
829 atomic_inc(&probe_count);
830 ret = __driver_probe_device(drv, dev);
831 if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
832 driver_deferred_probe_add(dev);
833
834 /*
835 * Did a trigger occur while probing? Need to re-trigger if yes
836 */
837 if (trigger_count != atomic_read(&deferred_trigger_count) &&
838 !defer_all_probes)
839 driver_deferred_probe_trigger();
840 }
841 atomic_dec(&probe_count);
842 wake_up_all(&probe_waitqueue);
843 return ret;
844}
845
846static inline bool cmdline_requested_async_probing(const char *drv_name)
847{
848 bool async_drv;
849
850 async_drv = parse_option_str(async_probe_drv_names, drv_name);
851
852 return (async_probe_default != async_drv);
853}
854
855/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
856static int __init save_async_options(char *buf)
857{
858 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
859 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
860
861 strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
862 async_probe_default = parse_option_str(async_probe_drv_names, "*");
863
864 return 1;
865}
866__setup("driver_async_probe=", save_async_options);
867
868static bool driver_allows_async_probing(struct device_driver *drv)
869{
870 switch (drv->probe_type) {
871 case PROBE_PREFER_ASYNCHRONOUS:
872 return true;
873
874 case PROBE_FORCE_SYNCHRONOUS:
875 return false;
876
877 default:
878 if (cmdline_requested_async_probing(drv->name))
879 return true;
880
881 if (module_requested_async_probing(drv->owner))
882 return true;
883
884 return false;
885 }
886}
887
888struct device_attach_data {
889 struct device *dev;
890
891 /*
892 * Indicates whether we are considering asynchronous probing or
893 * not. Only initial binding after device or driver registration
894 * (including deferral processing) may be done asynchronously, the
895 * rest is always synchronous, as we expect it is being done by
896 * request from userspace.
897 */
898 bool check_async;
899
900 /*
901 * Indicates if we are binding synchronous or asynchronous drivers.
902 * When asynchronous probing is enabled we'll execute 2 passes
903 * over drivers: first pass doing synchronous probing and second
904 * doing asynchronous probing (if synchronous did not succeed -
905 * most likely because there was no driver requiring synchronous
906 * probing - and we found asynchronous driver during first pass).
907 * The 2 passes are done because we can't shoot asynchronous
908 * probe for given device and driver from bus_for_each_drv() since
909 * driver pointer is not guaranteed to stay valid once
910 * bus_for_each_drv() iterates to the next driver on the bus.
911 */
912 bool want_async;
913
914 /*
915 * We'll set have_async to 'true' if, while scanning for matching
916 * driver, we'll encounter one that requests asynchronous probing.
917 */
918 bool have_async;
919};
920
921static int __device_attach_driver(struct device_driver *drv, void *_data)
922{
923 struct device_attach_data *data = _data;
924 struct device *dev = data->dev;
925 bool async_allowed;
926 int ret;
927
928 ret = driver_match_device(drv, dev);
929 if (ret == 0) {
930 /* no match */
931 return 0;
932 } else if (ret == -EPROBE_DEFER) {
933 dev_dbg(dev, "Device match requests probe deferral\n");
934 dev->can_match = true;
935 driver_deferred_probe_add(dev);
936 /*
937 * Device can't match with a driver right now, so don't attempt
938 * to match or bind with other drivers on the bus.
939 */
940 return ret;
941 } else if (ret < 0) {
942 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
943 return ret;
944 } /* ret > 0 means positive match */
945
946 async_allowed = driver_allows_async_probing(drv);
947
948 if (async_allowed)
949 data->have_async = true;
950
951 if (data->check_async && async_allowed != data->want_async)
952 return 0;
953
954 /*
955 * Ignore errors returned by ->probe so that the next driver can try
956 * its luck.
957 */
958 ret = driver_probe_device(drv, dev);
959 if (ret < 0)
960 return ret;
961 return ret == 0;
962}
963
964static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
965{
966 struct device *dev = _dev;
967 struct device_attach_data data = {
968 .dev = dev,
969 .check_async = true,
970 .want_async = true,
971 };
972
973 device_lock(dev);
974
975 /*
976 * Check if device has already been removed or claimed. This may
977 * happen with driver loading, device discovery/registration,
978 * and deferred probe processing happens all at once with
979 * multiple threads.
980 */
981 if (dev->p->dead || dev->driver)
982 goto out_unlock;
983
984 if (dev->parent)
985 pm_runtime_get_sync(dev->parent);
986
987 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
988 dev_dbg(dev, "async probe completed\n");
989
990 pm_request_idle(dev);
991
992 if (dev->parent)
993 pm_runtime_put(dev->parent);
994out_unlock:
995 device_unlock(dev);
996
997 put_device(dev);
998}
999
1000static int __device_attach(struct device *dev, bool allow_async)
1001{
1002 int ret = 0;
1003 bool async = false;
1004
1005 device_lock(dev);
1006 if (dev->p->dead) {
1007 goto out_unlock;
1008 } else if (dev->driver) {
1009 if (device_is_bound(dev)) {
1010 ret = 1;
1011 goto out_unlock;
1012 }
1013 ret = device_bind_driver(dev);
1014 if (ret == 0)
1015 ret = 1;
1016 else {
1017 dev->driver = NULL;
1018 ret = 0;
1019 }
1020 } else {
1021 struct device_attach_data data = {
1022 .dev = dev,
1023 .check_async = allow_async,
1024 .want_async = false,
1025 };
1026
1027 if (dev->parent)
1028 pm_runtime_get_sync(dev->parent);
1029
1030 ret = bus_for_each_drv(dev->bus, NULL, &data,
1031 __device_attach_driver);
1032 if (!ret && allow_async && data.have_async) {
1033 /*
1034 * If we could not find appropriate driver
1035 * synchronously and we are allowed to do
1036 * async probes and there are drivers that
1037 * want to probe asynchronously, we'll
1038 * try them.
1039 */
1040 dev_dbg(dev, "scheduling asynchronous probe\n");
1041 get_device(dev);
1042 async = true;
1043 } else {
1044 pm_request_idle(dev);
1045 }
1046
1047 if (dev->parent)
1048 pm_runtime_put(dev->parent);
1049 }
1050out_unlock:
1051 device_unlock(dev);
1052 if (async)
1053 async_schedule_dev(__device_attach_async_helper, dev);
1054 return ret;
1055}
1056
1057/**
1058 * device_attach - try to attach device to a driver.
1059 * @dev: device.
1060 *
1061 * Walk the list of drivers that the bus has and call
1062 * driver_probe_device() for each pair. If a compatible
1063 * pair is found, break out and return.
1064 *
1065 * Returns 1 if the device was bound to a driver;
1066 * 0 if no matching driver was found;
1067 * -ENODEV if the device is not registered.
1068 *
1069 * When called for a USB interface, @dev->parent lock must be held.
1070 */
1071int device_attach(struct device *dev)
1072{
1073 return __device_attach(dev, false);
1074}
1075EXPORT_SYMBOL_GPL(device_attach);
1076
1077void device_initial_probe(struct device *dev)
1078{
1079 __device_attach(dev, true);
1080}
1081
1082/*
1083 * __device_driver_lock - acquire locks needed to manipulate dev->drv
1084 * @dev: Device we will update driver info for
1085 * @parent: Parent device. Needed if the bus requires parent lock
1086 *
1087 * This function will take the required locks for manipulating dev->drv.
1088 * Normally this will just be the @dev lock, but when called for a USB
1089 * interface, @parent lock will be held as well.
1090 */
1091static void __device_driver_lock(struct device *dev, struct device *parent)
1092{
1093 if (parent && dev->bus->need_parent_lock)
1094 device_lock(parent);
1095 device_lock(dev);
1096}
1097
1098/*
1099 * __device_driver_unlock - release locks needed to manipulate dev->drv
1100 * @dev: Device we will update driver info for
1101 * @parent: Parent device. Needed if the bus requires parent lock
1102 *
1103 * This function will release the required locks for manipulating dev->drv.
1104 * Normally this will just be the @dev lock, but when called for a
1105 * USB interface, @parent lock will be released as well.
1106 */
1107static void __device_driver_unlock(struct device *dev, struct device *parent)
1108{
1109 device_unlock(dev);
1110 if (parent && dev->bus->need_parent_lock)
1111 device_unlock(parent);
1112}
1113
1114/**
1115 * device_driver_attach - attach a specific driver to a specific device
1116 * @drv: Driver to attach
1117 * @dev: Device to attach it to
1118 *
1119 * Manually attach driver to a device. Will acquire both @dev lock and
1120 * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1121 */
1122int device_driver_attach(struct device_driver *drv, struct device *dev)
1123{
1124 int ret;
1125
1126 __device_driver_lock(dev, dev->parent);
1127 ret = __driver_probe_device(drv, dev);
1128 __device_driver_unlock(dev, dev->parent);
1129
1130 /* also return probe errors as normal negative errnos */
1131 if (ret > 0)
1132 ret = -ret;
1133 if (ret == -EPROBE_DEFER)
1134 return -EAGAIN;
1135 return ret;
1136}
1137EXPORT_SYMBOL_GPL(device_driver_attach);
1138
1139static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1140{
1141 struct device *dev = _dev;
1142 struct device_driver *drv;
1143 int ret;
1144
1145 __device_driver_lock(dev, dev->parent);
1146 drv = dev->p->async_driver;
1147 dev->p->async_driver = NULL;
1148 ret = driver_probe_device(drv, dev);
1149 __device_driver_unlock(dev, dev->parent);
1150
1151 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1152
1153 put_device(dev);
1154}
1155
1156static int __driver_attach(struct device *dev, void *data)
1157{
1158 struct device_driver *drv = data;
1159 bool async = false;
1160 int ret;
1161
1162 /*
1163 * Lock device and try to bind to it. We drop the error
1164 * here and always return 0, because we need to keep trying
1165 * to bind to devices and some drivers will return an error
1166 * simply if it didn't support the device.
1167 *
1168 * driver_probe_device() will spit a warning if there
1169 * is an error.
1170 */
1171
1172 ret = driver_match_device(drv, dev);
1173 if (ret == 0) {
1174 /* no match */
1175 return 0;
1176 } else if (ret == -EPROBE_DEFER) {
1177 dev_dbg(dev, "Device match requests probe deferral\n");
1178 dev->can_match = true;
1179 driver_deferred_probe_add(dev);
1180 /*
1181 * Driver could not match with device, but may match with
1182 * another device on the bus.
1183 */
1184 return 0;
1185 } else if (ret < 0) {
1186 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1187 /*
1188 * Driver could not match with device, but may match with
1189 * another device on the bus.
1190 */
1191 return 0;
1192 } /* ret > 0 means positive match */
1193
1194 if (driver_allows_async_probing(drv)) {
1195 /*
1196 * Instead of probing the device synchronously we will
1197 * probe it asynchronously to allow for more parallelism.
1198 *
1199 * We only take the device lock here in order to guarantee
1200 * that the dev->driver and async_driver fields are protected
1201 */
1202 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1203 device_lock(dev);
1204 if (!dev->driver && !dev->p->async_driver) {
1205 get_device(dev);
1206 dev->p->async_driver = drv;
1207 async = true;
1208 }
1209 device_unlock(dev);
1210 if (async)
1211 async_schedule_dev(__driver_attach_async_helper, dev);
1212 return 0;
1213 }
1214
1215 __device_driver_lock(dev, dev->parent);
1216 driver_probe_device(drv, dev);
1217 __device_driver_unlock(dev, dev->parent);
1218
1219 return 0;
1220}
1221
1222/**
1223 * driver_attach - try to bind driver to devices.
1224 * @drv: driver.
1225 *
1226 * Walk the list of devices that the bus has on it and try to
1227 * match the driver with each one. If driver_probe_device()
1228 * returns 0 and the @dev->driver is set, we've found a
1229 * compatible pair.
1230 */
1231int driver_attach(struct device_driver *drv)
1232{
1233 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1234}
1235EXPORT_SYMBOL_GPL(driver_attach);
1236
1237/*
1238 * __device_release_driver() must be called with @dev lock held.
1239 * When called for a USB interface, @dev->parent lock must be held as well.
1240 */
1241static void __device_release_driver(struct device *dev, struct device *parent)
1242{
1243 struct device_driver *drv;
1244
1245 drv = dev->driver;
1246 if (drv) {
1247 pm_runtime_get_sync(dev);
1248
1249 while (device_links_busy(dev)) {
1250 __device_driver_unlock(dev, parent);
1251
1252 device_links_unbind_consumers(dev);
1253
1254 __device_driver_lock(dev, parent);
1255 /*
1256 * A concurrent invocation of the same function might
1257 * have released the driver successfully while this one
1258 * was waiting, so check for that.
1259 */
1260 if (dev->driver != drv) {
1261 pm_runtime_put(dev);
1262 return;
1263 }
1264 }
1265
1266 driver_sysfs_remove(dev);
1267
1268 bus_notify(dev, BUS_NOTIFY_UNBIND_DRIVER);
1269
1270 pm_runtime_put_sync(dev);
1271
1272 device_remove(dev);
1273
1274 if (dev->bus && dev->bus->dma_cleanup)
1275 dev->bus->dma_cleanup(dev);
1276
1277 device_unbind_cleanup(dev);
1278 device_links_driver_cleanup(dev);
1279
1280 klist_remove(&dev->p->knode_driver);
1281 device_pm_check_callbacks(dev);
1282
1283 bus_notify(dev, BUS_NOTIFY_UNBOUND_DRIVER);
1284 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1285 }
1286}
1287
1288void device_release_driver_internal(struct device *dev,
1289 struct device_driver *drv,
1290 struct device *parent)
1291{
1292 __device_driver_lock(dev, parent);
1293
1294 if (!drv || drv == dev->driver)
1295 __device_release_driver(dev, parent);
1296
1297 __device_driver_unlock(dev, parent);
1298}
1299
1300/**
1301 * device_release_driver - manually detach device from driver.
1302 * @dev: device.
1303 *
1304 * Manually detach device from driver.
1305 * When called for a USB interface, @dev->parent lock must be held.
1306 *
1307 * If this function is to be called with @dev->parent lock held, ensure that
1308 * the device's consumers are unbound in advance or that their locks can be
1309 * acquired under the @dev->parent lock.
1310 */
1311void device_release_driver(struct device *dev)
1312{
1313 /*
1314 * If anyone calls device_release_driver() recursively from
1315 * within their ->remove callback for the same device, they
1316 * will deadlock right here.
1317 */
1318 device_release_driver_internal(dev, NULL, NULL);
1319}
1320EXPORT_SYMBOL_GPL(device_release_driver);
1321
1322/**
1323 * device_driver_detach - detach driver from a specific device
1324 * @dev: device to detach driver from
1325 *
1326 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1327 * lock if needed.
1328 */
1329void device_driver_detach(struct device *dev)
1330{
1331 device_release_driver_internal(dev, NULL, dev->parent);
1332}
1333
1334/**
1335 * driver_detach - detach driver from all devices it controls.
1336 * @drv: driver.
1337 */
1338void driver_detach(struct device_driver *drv)
1339{
1340 struct device_private *dev_prv;
1341 struct device *dev;
1342
1343 if (driver_allows_async_probing(drv))
1344 async_synchronize_full();
1345
1346 for (;;) {
1347 spin_lock(&drv->p->klist_devices.k_lock);
1348 if (list_empty(&drv->p->klist_devices.k_list)) {
1349 spin_unlock(&drv->p->klist_devices.k_lock);
1350 break;
1351 }
1352 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1353 struct device_private,
1354 knode_driver.n_node);
1355 dev = dev_prv->device;
1356 get_device(dev);
1357 spin_unlock(&drv->p->klist_devices.k_lock);
1358 device_release_driver_internal(dev, drv, dev->parent);
1359 put_device(dev);
1360 }
1361}
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#include <linux/slab.h>
31
32#include "base.h"
33#include "power/power.h"
34
35/*
36 * Deferred Probe infrastructure.
37 *
38 * Sometimes driver probe order matters, but the kernel doesn't always have
39 * dependency information which means some drivers will get probed before a
40 * resource it depends on is available. For example, an SDHCI driver may
41 * first need a GPIO line from an i2c GPIO controller before it can be
42 * initialized. If a required resource is not available yet, a driver can
43 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
44 *
45 * Deferred probe maintains two lists of devices, a pending list and an active
46 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
47 * pending list. A successful driver probe will trigger moving all devices
48 * from the pending to the active list so that the workqueue will eventually
49 * retry them.
50 *
51 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
52 * of the (struct device*)->p->deferred_probe pointers are manipulated
53 */
54static DEFINE_MUTEX(deferred_probe_mutex);
55static LIST_HEAD(deferred_probe_pending_list);
56static LIST_HEAD(deferred_probe_active_list);
57static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
58static struct dentry *deferred_devices;
59static bool initcalls_done;
60
61/* Save the async probe drivers' name from kernel cmdline */
62#define ASYNC_DRV_NAMES_MAX_LEN 256
63static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
64
65/*
66 * In some cases, like suspend to RAM or hibernation, It might be reasonable
67 * to prohibit probing of devices as it could be unsafe.
68 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
69 */
70static bool defer_all_probes;
71
72/*
73 * deferred_probe_work_func() - Retry probing devices in the active list.
74 */
75static void deferred_probe_work_func(struct work_struct *work)
76{
77 struct device *dev;
78 struct device_private *private;
79 /*
80 * This block processes every device in the deferred 'active' list.
81 * Each device is removed from the active list and passed to
82 * bus_probe_device() to re-attempt the probe. The loop continues
83 * until every device in the active list is removed and retried.
84 *
85 * Note: Once the device is removed from the list and the mutex is
86 * released, it is possible for the device get freed by another thread
87 * and cause a illegal pointer dereference. This code uses
88 * get/put_device() to ensure the device structure cannot disappear
89 * from under our feet.
90 */
91 mutex_lock(&deferred_probe_mutex);
92 while (!list_empty(&deferred_probe_active_list)) {
93 private = list_first_entry(&deferred_probe_active_list,
94 typeof(*dev->p), deferred_probe);
95 dev = private->device;
96 list_del_init(&private->deferred_probe);
97
98 get_device(dev);
99
100 /*
101 * Drop the mutex while probing each device; the probe path may
102 * manipulate the deferred list
103 */
104 mutex_unlock(&deferred_probe_mutex);
105
106 /*
107 * Force the device to the end of the dpm_list since
108 * the PM code assumes that the order we add things to
109 * the list is a good order for suspend but deferred
110 * probe makes that very unsafe.
111 */
112 device_pm_move_to_tail(dev);
113
114 dev_dbg(dev, "Retrying from deferred list\n");
115 bus_probe_device(dev);
116 mutex_lock(&deferred_probe_mutex);
117
118 put_device(dev);
119 }
120 mutex_unlock(&deferred_probe_mutex);
121}
122static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
123
124void driver_deferred_probe_add(struct device *dev)
125{
126 mutex_lock(&deferred_probe_mutex);
127 if (list_empty(&dev->p->deferred_probe)) {
128 dev_dbg(dev, "Added to deferred list\n");
129 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
130 }
131 mutex_unlock(&deferred_probe_mutex);
132}
133
134void driver_deferred_probe_del(struct device *dev)
135{
136 mutex_lock(&deferred_probe_mutex);
137 if (!list_empty(&dev->p->deferred_probe)) {
138 dev_dbg(dev, "Removed from deferred list\n");
139 list_del_init(&dev->p->deferred_probe);
140 kfree(dev->p->deferred_probe_reason);
141 dev->p->deferred_probe_reason = NULL;
142 }
143 mutex_unlock(&deferred_probe_mutex);
144}
145
146static bool driver_deferred_probe_enable = false;
147/**
148 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
149 *
150 * This functions moves all devices from the pending list to the active
151 * list and schedules the deferred probe workqueue to process them. It
152 * should be called anytime a driver is successfully bound to a device.
153 *
154 * Note, there is a race condition in multi-threaded probe. In the case where
155 * more than one device is probing at the same time, it is possible for one
156 * probe to complete successfully while another is about to defer. If the second
157 * depends on the first, then it will get put on the pending list after the
158 * trigger event has already occurred and will be stuck there.
159 *
160 * The atomic 'deferred_trigger_count' is used to determine if a successful
161 * trigger has occurred in the midst of probing a driver. If the trigger count
162 * changes in the midst of a probe, then deferred processing should be triggered
163 * again.
164 */
165static void driver_deferred_probe_trigger(void)
166{
167 if (!driver_deferred_probe_enable)
168 return;
169
170 /*
171 * A successful probe means that all the devices in the pending list
172 * should be triggered to be reprobed. Move all the deferred devices
173 * into the active list so they can be retried by the workqueue
174 */
175 mutex_lock(&deferred_probe_mutex);
176 atomic_inc(&deferred_trigger_count);
177 list_splice_tail_init(&deferred_probe_pending_list,
178 &deferred_probe_active_list);
179 mutex_unlock(&deferred_probe_mutex);
180
181 /*
182 * Kick the re-probe thread. It may already be scheduled, but it is
183 * safe to kick it again.
184 */
185 schedule_work(&deferred_probe_work);
186}
187
188/**
189 * device_block_probing() - Block/defer device's probes
190 *
191 * It will disable probing of devices and defer their probes instead.
192 */
193void device_block_probing(void)
194{
195 defer_all_probes = true;
196 /* sync with probes to avoid races. */
197 wait_for_device_probe();
198}
199
200/**
201 * device_unblock_probing() - Unblock/enable device's probes
202 *
203 * It will restore normal behavior and trigger re-probing of deferred
204 * devices.
205 */
206void device_unblock_probing(void)
207{
208 defer_all_probes = false;
209 driver_deferred_probe_trigger();
210}
211
212/**
213 * device_set_deferred_probe_reason() - Set defer probe reason message for device
214 * @dev: the pointer to the struct device
215 * @vaf: the pointer to va_format structure with message
216 */
217void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
218{
219 const char *drv = dev_driver_string(dev);
220
221 mutex_lock(&deferred_probe_mutex);
222
223 kfree(dev->p->deferred_probe_reason);
224 dev->p->deferred_probe_reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
225
226 mutex_unlock(&deferred_probe_mutex);
227}
228
229/*
230 * deferred_devs_show() - Show the devices in the deferred probe pending list.
231 */
232static int deferred_devs_show(struct seq_file *s, void *data)
233{
234 struct device_private *curr;
235
236 mutex_lock(&deferred_probe_mutex);
237
238 list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
239 seq_printf(s, "%s\t%s", dev_name(curr->device),
240 curr->device->p->deferred_probe_reason ?: "\n");
241
242 mutex_unlock(&deferred_probe_mutex);
243
244 return 0;
245}
246DEFINE_SHOW_ATTRIBUTE(deferred_devs);
247
248int driver_deferred_probe_timeout;
249EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
250static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue);
251
252static int __init deferred_probe_timeout_setup(char *str)
253{
254 int timeout;
255
256 if (!kstrtoint(str, 10, &timeout))
257 driver_deferred_probe_timeout = timeout;
258 return 1;
259}
260__setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
261
262/**
263 * driver_deferred_probe_check_state() - Check deferred probe state
264 * @dev: device to check
265 *
266 * Return:
267 * -ENODEV if initcalls have completed and modules are disabled.
268 * -ETIMEDOUT if the deferred probe timeout was set and has expired
269 * and modules are enabled.
270 * -EPROBE_DEFER in other cases.
271 *
272 * Drivers or subsystems can opt-in to calling this function instead of directly
273 * returning -EPROBE_DEFER.
274 */
275int driver_deferred_probe_check_state(struct device *dev)
276{
277 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
278 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
279 return -ENODEV;
280 }
281
282 if (!driver_deferred_probe_timeout && initcalls_done) {
283 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
284 return -ETIMEDOUT;
285 }
286
287 return -EPROBE_DEFER;
288}
289
290static void deferred_probe_timeout_work_func(struct work_struct *work)
291{
292 struct device_private *private, *p;
293
294 driver_deferred_probe_timeout = 0;
295 driver_deferred_probe_trigger();
296 flush_work(&deferred_probe_work);
297
298 list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe)
299 dev_info(private->device, "deferred probe pending\n");
300 wake_up_all(&probe_timeout_waitqueue);
301}
302static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
303
304/**
305 * deferred_probe_initcall() - Enable probing of deferred devices
306 *
307 * We don't want to get in the way when the bulk of drivers are getting probed.
308 * Instead, this initcall makes sure that deferred probing is delayed until
309 * late_initcall time.
310 */
311static int deferred_probe_initcall(void)
312{
313 deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
314 NULL, &deferred_devs_fops);
315
316 driver_deferred_probe_enable = true;
317 driver_deferred_probe_trigger();
318 /* Sort as many dependencies as possible before exiting initcalls */
319 flush_work(&deferred_probe_work);
320 initcalls_done = true;
321
322 /*
323 * Trigger deferred probe again, this time we won't defer anything
324 * that is optional
325 */
326 driver_deferred_probe_trigger();
327 flush_work(&deferred_probe_work);
328
329 if (driver_deferred_probe_timeout > 0) {
330 schedule_delayed_work(&deferred_probe_timeout_work,
331 driver_deferred_probe_timeout * HZ);
332 }
333 return 0;
334}
335late_initcall(deferred_probe_initcall);
336
337static void __exit deferred_probe_exit(void)
338{
339 debugfs_remove_recursive(deferred_devices);
340}
341__exitcall(deferred_probe_exit);
342
343/**
344 * device_is_bound() - Check if device is bound to a driver
345 * @dev: device to check
346 *
347 * Returns true if passed device has already finished probing successfully
348 * against a driver.
349 *
350 * This function must be called with the device lock held.
351 */
352bool device_is_bound(struct device *dev)
353{
354 return dev->p && klist_node_attached(&dev->p->knode_driver);
355}
356
357static void driver_bound(struct device *dev)
358{
359 if (device_is_bound(dev)) {
360 pr_warn("%s: device %s already bound\n",
361 __func__, kobject_name(&dev->kobj));
362 return;
363 }
364
365 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
366 __func__, dev_name(dev));
367
368 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
369 device_links_driver_bound(dev);
370
371 device_pm_check_callbacks(dev);
372
373 /*
374 * Make sure the device is no longer in one of the deferred lists and
375 * kick off retrying all pending devices
376 */
377 driver_deferred_probe_del(dev);
378 driver_deferred_probe_trigger();
379
380 if (dev->bus)
381 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
382 BUS_NOTIFY_BOUND_DRIVER, dev);
383
384 kobject_uevent(&dev->kobj, KOBJ_BIND);
385}
386
387static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
388 const char *buf, size_t count)
389{
390 device_lock(dev);
391 dev->driver->coredump(dev);
392 device_unlock(dev);
393
394 return count;
395}
396static DEVICE_ATTR_WO(coredump);
397
398static int driver_sysfs_add(struct device *dev)
399{
400 int ret;
401
402 if (dev->bus)
403 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
404 BUS_NOTIFY_BIND_DRIVER, dev);
405
406 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
407 kobject_name(&dev->kobj));
408 if (ret)
409 goto fail;
410
411 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
412 "driver");
413 if (ret)
414 goto rm_dev;
415
416 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
417 !device_create_file(dev, &dev_attr_coredump))
418 return 0;
419
420 sysfs_remove_link(&dev->kobj, "driver");
421
422rm_dev:
423 sysfs_remove_link(&dev->driver->p->kobj,
424 kobject_name(&dev->kobj));
425
426fail:
427 return ret;
428}
429
430static void driver_sysfs_remove(struct device *dev)
431{
432 struct device_driver *drv = dev->driver;
433
434 if (drv) {
435 if (drv->coredump)
436 device_remove_file(dev, &dev_attr_coredump);
437 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
438 sysfs_remove_link(&dev->kobj, "driver");
439 }
440}
441
442/**
443 * device_bind_driver - bind a driver to one device.
444 * @dev: device.
445 *
446 * Allow manual attachment of a driver to a device.
447 * Caller must have already set @dev->driver.
448 *
449 * Note that this does not modify the bus reference count.
450 * Please verify that is accounted for before calling this.
451 * (It is ok to call with no other effort from a driver's probe() method.)
452 *
453 * This function must be called with the device lock held.
454 */
455int device_bind_driver(struct device *dev)
456{
457 int ret;
458
459 ret = driver_sysfs_add(dev);
460 if (!ret)
461 driver_bound(dev);
462 else if (dev->bus)
463 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
464 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
465 return ret;
466}
467EXPORT_SYMBOL_GPL(device_bind_driver);
468
469static atomic_t probe_count = ATOMIC_INIT(0);
470static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
471
472static void driver_deferred_probe_add_trigger(struct device *dev,
473 int local_trigger_count)
474{
475 driver_deferred_probe_add(dev);
476 /* Did a trigger occur while probing? Need to re-trigger if yes */
477 if (local_trigger_count != atomic_read(&deferred_trigger_count))
478 driver_deferred_probe_trigger();
479}
480
481static ssize_t state_synced_show(struct device *dev,
482 struct device_attribute *attr, char *buf)
483{
484 bool val;
485
486 device_lock(dev);
487 val = dev->state_synced;
488 device_unlock(dev);
489 return sprintf(buf, "%u\n", val);
490}
491static DEVICE_ATTR_RO(state_synced);
492
493static int really_probe(struct device *dev, struct device_driver *drv)
494{
495 int ret = -EPROBE_DEFER;
496 int local_trigger_count = atomic_read(&deferred_trigger_count);
497 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
498 !drv->suppress_bind_attrs;
499
500 if (defer_all_probes) {
501 /*
502 * Value of defer_all_probes can be set only by
503 * device_block_probing() which, in turn, will call
504 * wait_for_device_probe() right after that to avoid any races.
505 */
506 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
507 driver_deferred_probe_add(dev);
508 return ret;
509 }
510
511 ret = device_links_check_suppliers(dev);
512 if (ret == -EPROBE_DEFER)
513 driver_deferred_probe_add_trigger(dev, local_trigger_count);
514 if (ret)
515 return ret;
516
517 atomic_inc(&probe_count);
518 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
519 drv->bus->name, __func__, drv->name, dev_name(dev));
520 if (!list_empty(&dev->devres_head)) {
521 dev_crit(dev, "Resources present before probing\n");
522 ret = -EBUSY;
523 goto done;
524 }
525
526re_probe:
527 dev->driver = drv;
528
529 /* If using pinctrl, bind pins now before probing */
530 ret = pinctrl_bind_pins(dev);
531 if (ret)
532 goto pinctrl_bind_failed;
533
534 if (dev->bus->dma_configure) {
535 ret = dev->bus->dma_configure(dev);
536 if (ret)
537 goto probe_failed;
538 }
539
540 if (driver_sysfs_add(dev)) {
541 pr_err("%s: driver_sysfs_add(%s) failed\n",
542 __func__, dev_name(dev));
543 goto probe_failed;
544 }
545
546 if (dev->pm_domain && dev->pm_domain->activate) {
547 ret = dev->pm_domain->activate(dev);
548 if (ret)
549 goto probe_failed;
550 }
551
552 if (dev->bus->probe) {
553 ret = dev->bus->probe(dev);
554 if (ret)
555 goto probe_failed;
556 } else if (drv->probe) {
557 ret = drv->probe(dev);
558 if (ret)
559 goto probe_failed;
560 }
561
562 if (device_add_groups(dev, drv->dev_groups)) {
563 dev_err(dev, "device_add_groups() failed\n");
564 goto dev_groups_failed;
565 }
566
567 if (dev_has_sync_state(dev) &&
568 device_create_file(dev, &dev_attr_state_synced)) {
569 dev_err(dev, "state_synced sysfs add failed\n");
570 goto dev_sysfs_state_synced_failed;
571 }
572
573 if (test_remove) {
574 test_remove = false;
575
576 device_remove_file(dev, &dev_attr_state_synced);
577 device_remove_groups(dev, drv->dev_groups);
578
579 if (dev->bus->remove)
580 dev->bus->remove(dev);
581 else if (drv->remove)
582 drv->remove(dev);
583
584 devres_release_all(dev);
585 driver_sysfs_remove(dev);
586 dev->driver = NULL;
587 dev_set_drvdata(dev, NULL);
588 if (dev->pm_domain && dev->pm_domain->dismiss)
589 dev->pm_domain->dismiss(dev);
590 pm_runtime_reinit(dev);
591
592 goto re_probe;
593 }
594
595 pinctrl_init_done(dev);
596
597 if (dev->pm_domain && dev->pm_domain->sync)
598 dev->pm_domain->sync(dev);
599
600 driver_bound(dev);
601 ret = 1;
602 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
603 drv->bus->name, __func__, dev_name(dev), drv->name);
604 goto done;
605
606dev_sysfs_state_synced_failed:
607 device_remove_groups(dev, drv->dev_groups);
608dev_groups_failed:
609 if (dev->bus->remove)
610 dev->bus->remove(dev);
611 else if (drv->remove)
612 drv->remove(dev);
613probe_failed:
614 if (dev->bus)
615 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
616 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
617pinctrl_bind_failed:
618 device_links_no_driver(dev);
619 devres_release_all(dev);
620 arch_teardown_dma_ops(dev);
621 driver_sysfs_remove(dev);
622 dev->driver = NULL;
623 dev_set_drvdata(dev, NULL);
624 if (dev->pm_domain && dev->pm_domain->dismiss)
625 dev->pm_domain->dismiss(dev);
626 pm_runtime_reinit(dev);
627 dev_pm_set_driver_flags(dev, 0);
628
629 switch (ret) {
630 case -EPROBE_DEFER:
631 /* Driver requested deferred probing */
632 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
633 driver_deferred_probe_add_trigger(dev, local_trigger_count);
634 break;
635 case -ENODEV:
636 case -ENXIO:
637 pr_debug("%s: probe of %s rejects match %d\n",
638 drv->name, dev_name(dev), ret);
639 break;
640 default:
641 /* driver matched but the probe failed */
642 pr_warn("%s: probe of %s failed with error %d\n",
643 drv->name, dev_name(dev), ret);
644 }
645 /*
646 * Ignore errors returned by ->probe so that the next driver can try
647 * its luck.
648 */
649 ret = 0;
650done:
651 atomic_dec(&probe_count);
652 wake_up_all(&probe_waitqueue);
653 return ret;
654}
655
656/*
657 * For initcall_debug, show the driver probe time.
658 */
659static int really_probe_debug(struct device *dev, struct device_driver *drv)
660{
661 ktime_t calltime, delta, rettime;
662 int ret;
663
664 calltime = ktime_get();
665 ret = really_probe(dev, drv);
666 rettime = ktime_get();
667 delta = ktime_sub(rettime, calltime);
668 pr_debug("probe of %s returned %d after %lld usecs\n",
669 dev_name(dev), ret, (s64) ktime_to_us(delta));
670 return ret;
671}
672
673/**
674 * driver_probe_done
675 * Determine if the probe sequence is finished or not.
676 *
677 * Should somehow figure out how to use a semaphore, not an atomic variable...
678 */
679int driver_probe_done(void)
680{
681 int local_probe_count = atomic_read(&probe_count);
682
683 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
684 if (local_probe_count)
685 return -EBUSY;
686 return 0;
687}
688
689/**
690 * wait_for_device_probe
691 * Wait for device probing to be completed.
692 */
693void wait_for_device_probe(void)
694{
695 /* wait for probe timeout */
696 wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout);
697
698 /* wait for the deferred probe workqueue to finish */
699 flush_work(&deferred_probe_work);
700
701 /* wait for the known devices to complete their probing */
702 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
703 async_synchronize_full();
704}
705EXPORT_SYMBOL_GPL(wait_for_device_probe);
706
707/**
708 * driver_probe_device - attempt to bind device & driver together
709 * @drv: driver to bind a device to
710 * @dev: device to try to bind to the driver
711 *
712 * This function returns -ENODEV if the device is not registered,
713 * 1 if the device is bound successfully and 0 otherwise.
714 *
715 * This function must be called with @dev lock held. When called for a
716 * USB interface, @dev->parent lock must be held as well.
717 *
718 * If the device has a parent, runtime-resume the parent before driver probing.
719 */
720int driver_probe_device(struct device_driver *drv, struct device *dev)
721{
722 int ret = 0;
723
724 if (!device_is_registered(dev))
725 return -ENODEV;
726
727 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
728 drv->bus->name, __func__, dev_name(dev), drv->name);
729
730 pm_runtime_get_suppliers(dev);
731 if (dev->parent)
732 pm_runtime_get_sync(dev->parent);
733
734 pm_runtime_barrier(dev);
735 if (initcall_debug)
736 ret = really_probe_debug(dev, drv);
737 else
738 ret = really_probe(dev, drv);
739 pm_request_idle(dev);
740
741 if (dev->parent)
742 pm_runtime_put(dev->parent);
743
744 pm_runtime_put_suppliers(dev);
745 return ret;
746}
747
748static inline bool cmdline_requested_async_probing(const char *drv_name)
749{
750 return parse_option_str(async_probe_drv_names, drv_name);
751}
752
753/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
754static int __init save_async_options(char *buf)
755{
756 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
757 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
758
759 strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
760 return 0;
761}
762__setup("driver_async_probe=", save_async_options);
763
764bool driver_allows_async_probing(struct device_driver *drv)
765{
766 switch (drv->probe_type) {
767 case PROBE_PREFER_ASYNCHRONOUS:
768 return true;
769
770 case PROBE_FORCE_SYNCHRONOUS:
771 return false;
772
773 default:
774 if (cmdline_requested_async_probing(drv->name))
775 return true;
776
777 if (module_requested_async_probing(drv->owner))
778 return true;
779
780 return false;
781 }
782}
783
784struct device_attach_data {
785 struct device *dev;
786
787 /*
788 * Indicates whether we are are considering asynchronous probing or
789 * not. Only initial binding after device or driver registration
790 * (including deferral processing) may be done asynchronously, the
791 * rest is always synchronous, as we expect it is being done by
792 * request from userspace.
793 */
794 bool check_async;
795
796 /*
797 * Indicates if we are binding synchronous or asynchronous drivers.
798 * When asynchronous probing is enabled we'll execute 2 passes
799 * over drivers: first pass doing synchronous probing and second
800 * doing asynchronous probing (if synchronous did not succeed -
801 * most likely because there was no driver requiring synchronous
802 * probing - and we found asynchronous driver during first pass).
803 * The 2 passes are done because we can't shoot asynchronous
804 * probe for given device and driver from bus_for_each_drv() since
805 * driver pointer is not guaranteed to stay valid once
806 * bus_for_each_drv() iterates to the next driver on the bus.
807 */
808 bool want_async;
809
810 /*
811 * We'll set have_async to 'true' if, while scanning for matching
812 * driver, we'll encounter one that requests asynchronous probing.
813 */
814 bool have_async;
815};
816
817static int __device_attach_driver(struct device_driver *drv, void *_data)
818{
819 struct device_attach_data *data = _data;
820 struct device *dev = data->dev;
821 bool async_allowed;
822 int ret;
823
824 ret = driver_match_device(drv, dev);
825 if (ret == 0) {
826 /* no match */
827 return 0;
828 } else if (ret == -EPROBE_DEFER) {
829 dev_dbg(dev, "Device match requests probe deferral\n");
830 driver_deferred_probe_add(dev);
831 } else if (ret < 0) {
832 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
833 return ret;
834 } /* ret > 0 means positive match */
835
836 async_allowed = driver_allows_async_probing(drv);
837
838 if (async_allowed)
839 data->have_async = true;
840
841 if (data->check_async && async_allowed != data->want_async)
842 return 0;
843
844 return driver_probe_device(drv, dev);
845}
846
847static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
848{
849 struct device *dev = _dev;
850 struct device_attach_data data = {
851 .dev = dev,
852 .check_async = true,
853 .want_async = true,
854 };
855
856 device_lock(dev);
857
858 /*
859 * Check if device has already been removed or claimed. This may
860 * happen with driver loading, device discovery/registration,
861 * and deferred probe processing happens all at once with
862 * multiple threads.
863 */
864 if (dev->p->dead || dev->driver)
865 goto out_unlock;
866
867 if (dev->parent)
868 pm_runtime_get_sync(dev->parent);
869
870 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
871 dev_dbg(dev, "async probe completed\n");
872
873 pm_request_idle(dev);
874
875 if (dev->parent)
876 pm_runtime_put(dev->parent);
877out_unlock:
878 device_unlock(dev);
879
880 put_device(dev);
881}
882
883static int __device_attach(struct device *dev, bool allow_async)
884{
885 int ret = 0;
886
887 device_lock(dev);
888 if (dev->p->dead) {
889 goto out_unlock;
890 } else if (dev->driver) {
891 if (device_is_bound(dev)) {
892 ret = 1;
893 goto out_unlock;
894 }
895 ret = device_bind_driver(dev);
896 if (ret == 0)
897 ret = 1;
898 else {
899 dev->driver = NULL;
900 ret = 0;
901 }
902 } else {
903 struct device_attach_data data = {
904 .dev = dev,
905 .check_async = allow_async,
906 .want_async = false,
907 };
908
909 if (dev->parent)
910 pm_runtime_get_sync(dev->parent);
911
912 ret = bus_for_each_drv(dev->bus, NULL, &data,
913 __device_attach_driver);
914 if (!ret && allow_async && data.have_async) {
915 /*
916 * If we could not find appropriate driver
917 * synchronously and we are allowed to do
918 * async probes and there are drivers that
919 * want to probe asynchronously, we'll
920 * try them.
921 */
922 dev_dbg(dev, "scheduling asynchronous probe\n");
923 get_device(dev);
924 async_schedule_dev(__device_attach_async_helper, dev);
925 } else {
926 pm_request_idle(dev);
927 }
928
929 if (dev->parent)
930 pm_runtime_put(dev->parent);
931 }
932out_unlock:
933 device_unlock(dev);
934 return ret;
935}
936
937/**
938 * device_attach - try to attach device to a driver.
939 * @dev: device.
940 *
941 * Walk the list of drivers that the bus has and call
942 * driver_probe_device() for each pair. If a compatible
943 * pair is found, break out and return.
944 *
945 * Returns 1 if the device was bound to a driver;
946 * 0 if no matching driver was found;
947 * -ENODEV if the device is not registered.
948 *
949 * When called for a USB interface, @dev->parent lock must be held.
950 */
951int device_attach(struct device *dev)
952{
953 return __device_attach(dev, false);
954}
955EXPORT_SYMBOL_GPL(device_attach);
956
957void device_initial_probe(struct device *dev)
958{
959 __device_attach(dev, true);
960}
961
962/*
963 * __device_driver_lock - acquire locks needed to manipulate dev->drv
964 * @dev: Device we will update driver info for
965 * @parent: Parent device. Needed if the bus requires parent lock
966 *
967 * This function will take the required locks for manipulating dev->drv.
968 * Normally this will just be the @dev lock, but when called for a USB
969 * interface, @parent lock will be held as well.
970 */
971static void __device_driver_lock(struct device *dev, struct device *parent)
972{
973 if (parent && dev->bus->need_parent_lock)
974 device_lock(parent);
975 device_lock(dev);
976}
977
978/*
979 * __device_driver_unlock - release locks needed to manipulate dev->drv
980 * @dev: Device we will update driver info for
981 * @parent: Parent device. Needed if the bus requires parent lock
982 *
983 * This function will release the required locks for manipulating dev->drv.
984 * Normally this will just be the the @dev lock, but when called for a
985 * USB interface, @parent lock will be released as well.
986 */
987static void __device_driver_unlock(struct device *dev, struct device *parent)
988{
989 device_unlock(dev);
990 if (parent && dev->bus->need_parent_lock)
991 device_unlock(parent);
992}
993
994/**
995 * device_driver_attach - attach a specific driver to a specific device
996 * @drv: Driver to attach
997 * @dev: Device to attach it to
998 *
999 * Manually attach driver to a device. Will acquire both @dev lock and
1000 * @dev->parent lock if needed.
1001 */
1002int device_driver_attach(struct device_driver *drv, struct device *dev)
1003{
1004 int ret = 0;
1005
1006 __device_driver_lock(dev, dev->parent);
1007
1008 /*
1009 * If device has been removed or someone has already successfully
1010 * bound a driver before us just skip the driver probe call.
1011 */
1012 if (!dev->p->dead && !dev->driver)
1013 ret = driver_probe_device(drv, dev);
1014
1015 __device_driver_unlock(dev, dev->parent);
1016
1017 return ret;
1018}
1019
1020static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1021{
1022 struct device *dev = _dev;
1023 struct device_driver *drv;
1024 int ret = 0;
1025
1026 __device_driver_lock(dev, dev->parent);
1027
1028 drv = dev->p->async_driver;
1029
1030 /*
1031 * If device has been removed or someone has already successfully
1032 * bound a driver before us just skip the driver probe call.
1033 */
1034 if (!dev->p->dead && !dev->driver)
1035 ret = driver_probe_device(drv, dev);
1036
1037 __device_driver_unlock(dev, dev->parent);
1038
1039 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1040
1041 put_device(dev);
1042}
1043
1044static int __driver_attach(struct device *dev, void *data)
1045{
1046 struct device_driver *drv = data;
1047 int ret;
1048
1049 /*
1050 * Lock device and try to bind to it. We drop the error
1051 * here and always return 0, because we need to keep trying
1052 * to bind to devices and some drivers will return an error
1053 * simply if it didn't support the device.
1054 *
1055 * driver_probe_device() will spit a warning if there
1056 * is an error.
1057 */
1058
1059 ret = driver_match_device(drv, dev);
1060 if (ret == 0) {
1061 /* no match */
1062 return 0;
1063 } else if (ret == -EPROBE_DEFER) {
1064 dev_dbg(dev, "Device match requests probe deferral\n");
1065 driver_deferred_probe_add(dev);
1066 } else if (ret < 0) {
1067 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1068 return ret;
1069 } /* ret > 0 means positive match */
1070
1071 if (driver_allows_async_probing(drv)) {
1072 /*
1073 * Instead of probing the device synchronously we will
1074 * probe it asynchronously to allow for more parallelism.
1075 *
1076 * We only take the device lock here in order to guarantee
1077 * that the dev->driver and async_driver fields are protected
1078 */
1079 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1080 device_lock(dev);
1081 if (!dev->driver) {
1082 get_device(dev);
1083 dev->p->async_driver = drv;
1084 async_schedule_dev(__driver_attach_async_helper, dev);
1085 }
1086 device_unlock(dev);
1087 return 0;
1088 }
1089
1090 device_driver_attach(drv, dev);
1091
1092 return 0;
1093}
1094
1095/**
1096 * driver_attach - try to bind driver to devices.
1097 * @drv: driver.
1098 *
1099 * Walk the list of devices that the bus has on it and try to
1100 * match the driver with each one. If driver_probe_device()
1101 * returns 0 and the @dev->driver is set, we've found a
1102 * compatible pair.
1103 */
1104int driver_attach(struct device_driver *drv)
1105{
1106 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1107}
1108EXPORT_SYMBOL_GPL(driver_attach);
1109
1110/*
1111 * __device_release_driver() must be called with @dev lock held.
1112 * When called for a USB interface, @dev->parent lock must be held as well.
1113 */
1114static void __device_release_driver(struct device *dev, struct device *parent)
1115{
1116 struct device_driver *drv;
1117
1118 drv = dev->driver;
1119 if (drv) {
1120 while (device_links_busy(dev)) {
1121 __device_driver_unlock(dev, parent);
1122
1123 device_links_unbind_consumers(dev);
1124
1125 __device_driver_lock(dev, parent);
1126 /*
1127 * A concurrent invocation of the same function might
1128 * have released the driver successfully while this one
1129 * was waiting, so check for that.
1130 */
1131 if (dev->driver != drv)
1132 return;
1133 }
1134
1135 pm_runtime_get_sync(dev);
1136 pm_runtime_clean_up_links(dev);
1137
1138 driver_sysfs_remove(dev);
1139
1140 if (dev->bus)
1141 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1142 BUS_NOTIFY_UNBIND_DRIVER,
1143 dev);
1144
1145 pm_runtime_put_sync(dev);
1146
1147 device_remove_file(dev, &dev_attr_state_synced);
1148 device_remove_groups(dev, drv->dev_groups);
1149
1150 if (dev->bus && dev->bus->remove)
1151 dev->bus->remove(dev);
1152 else if (drv->remove)
1153 drv->remove(dev);
1154
1155 device_links_driver_cleanup(dev);
1156
1157 devres_release_all(dev);
1158 arch_teardown_dma_ops(dev);
1159 dev->driver = NULL;
1160 dev_set_drvdata(dev, NULL);
1161 if (dev->pm_domain && dev->pm_domain->dismiss)
1162 dev->pm_domain->dismiss(dev);
1163 pm_runtime_reinit(dev);
1164 dev_pm_set_driver_flags(dev, 0);
1165
1166 klist_remove(&dev->p->knode_driver);
1167 device_pm_check_callbacks(dev);
1168 if (dev->bus)
1169 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1170 BUS_NOTIFY_UNBOUND_DRIVER,
1171 dev);
1172
1173 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1174 }
1175}
1176
1177void device_release_driver_internal(struct device *dev,
1178 struct device_driver *drv,
1179 struct device *parent)
1180{
1181 __device_driver_lock(dev, parent);
1182
1183 if (!drv || drv == dev->driver)
1184 __device_release_driver(dev, parent);
1185
1186 __device_driver_unlock(dev, parent);
1187}
1188
1189/**
1190 * device_release_driver - manually detach device from driver.
1191 * @dev: device.
1192 *
1193 * Manually detach device from driver.
1194 * When called for a USB interface, @dev->parent lock must be held.
1195 *
1196 * If this function is to be called with @dev->parent lock held, ensure that
1197 * the device's consumers are unbound in advance or that their locks can be
1198 * acquired under the @dev->parent lock.
1199 */
1200void device_release_driver(struct device *dev)
1201{
1202 /*
1203 * If anyone calls device_release_driver() recursively from
1204 * within their ->remove callback for the same device, they
1205 * will deadlock right here.
1206 */
1207 device_release_driver_internal(dev, NULL, NULL);
1208}
1209EXPORT_SYMBOL_GPL(device_release_driver);
1210
1211/**
1212 * device_driver_detach - detach driver from a specific device
1213 * @dev: device to detach driver from
1214 *
1215 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1216 * lock if needed.
1217 */
1218void device_driver_detach(struct device *dev)
1219{
1220 device_release_driver_internal(dev, NULL, dev->parent);
1221}
1222
1223/**
1224 * driver_detach - detach driver from all devices it controls.
1225 * @drv: driver.
1226 */
1227void driver_detach(struct device_driver *drv)
1228{
1229 struct device_private *dev_prv;
1230 struct device *dev;
1231
1232 if (driver_allows_async_probing(drv))
1233 async_synchronize_full();
1234
1235 for (;;) {
1236 spin_lock(&drv->p->klist_devices.k_lock);
1237 if (list_empty(&drv->p->klist_devices.k_list)) {
1238 spin_unlock(&drv->p->klist_devices.k_lock);
1239 break;
1240 }
1241 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1242 struct device_private,
1243 knode_driver.n_node);
1244 dev = dev_prv->device;
1245 get_device(dev);
1246 spin_unlock(&drv->p->klist_devices.k_lock);
1247 device_release_driver_internal(dev, drv, dev->parent);
1248 put_device(dev);
1249 }
1250}