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