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