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_domain.h>
29#include <linux/pm_runtime.h>
30#include <linux/pinctrl/devinfo.h>
31#include <linux/slab.h>
32
33#include "base.h"
34#include "power/power.h"
35
36/*
37 * Deferred Probe infrastructure.
38 *
39 * Sometimes driver probe order matters, but the kernel doesn't always have
40 * dependency information which means some drivers will get probed before a
41 * resource it depends on is available. For example, an SDHCI driver may
42 * first need a GPIO line from an i2c GPIO controller before it can be
43 * initialized. If a required resource is not available yet, a driver can
44 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
45 *
46 * Deferred probe maintains two lists of devices, a pending list and an active
47 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
48 * pending list. A successful driver probe will trigger moving all devices
49 * from the pending to the active list so that the workqueue will eventually
50 * retry them.
51 *
52 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
53 * of the (struct device*)->p->deferred_probe pointers are manipulated
54 */
55static DEFINE_MUTEX(deferred_probe_mutex);
56static LIST_HEAD(deferred_probe_pending_list);
57static LIST_HEAD(deferred_probe_active_list);
58static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
59static bool initcalls_done;
60
61/* Save the async probe drivers' name from kernel cmdline */
62#define ASYNC_DRV_NAMES_MAX_LEN 256
63static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
64static bool async_probe_default;
65
66/*
67 * In some cases, like suspend to RAM or hibernation, It might be reasonable
68 * to prohibit probing of devices as it could be unsafe.
69 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
70 */
71static bool defer_all_probes;
72
73static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
74{
75 kfree(objp: dev->p->deferred_probe_reason);
76 dev->p->deferred_probe_reason = reason;
77}
78
79/*
80 * deferred_probe_work_func() - Retry probing devices in the active list.
81 */
82static void deferred_probe_work_func(struct work_struct *work)
83{
84 struct device *dev;
85 struct device_private *private;
86 /*
87 * This block processes every device in the deferred 'active' list.
88 * Each device is removed from the active list and passed to
89 * bus_probe_device() to re-attempt the probe. The loop continues
90 * until every device in the active list is removed and retried.
91 *
92 * Note: Once the device is removed from the list and the mutex is
93 * released, it is possible for the device get freed by another thread
94 * and cause a illegal pointer dereference. This code uses
95 * get/put_device() to ensure the device structure cannot disappear
96 * from under our feet.
97 */
98 mutex_lock(lock: &deferred_probe_mutex);
99 while (!list_empty(head: &deferred_probe_active_list)) {
100 private = list_first_entry(&deferred_probe_active_list,
101 typeof(*dev->p), deferred_probe);
102 dev = private->device;
103 list_del_init(entry: &private->deferred_probe);
104
105 get_device(dev);
106
107 __device_set_deferred_probe_reason(dev, NULL);
108
109 /*
110 * Drop the mutex while probing each device; the probe path may
111 * manipulate the deferred list
112 */
113 mutex_unlock(lock: &deferred_probe_mutex);
114
115 /*
116 * Force the device to the end of the dpm_list since
117 * the PM code assumes that the order we add things to
118 * the list is a good order for suspend but deferred
119 * probe makes that very unsafe.
120 */
121 device_pm_move_to_tail(dev);
122
123 dev_dbg(dev, "Retrying from deferred list\n");
124 bus_probe_device(dev);
125 mutex_lock(lock: &deferred_probe_mutex);
126
127 put_device(dev);
128 }
129 mutex_unlock(lock: &deferred_probe_mutex);
130}
131static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
132
133void driver_deferred_probe_add(struct device *dev)
134{
135 if (!dev->can_match)
136 return;
137
138 mutex_lock(lock: &deferred_probe_mutex);
139 if (list_empty(head: &dev->p->deferred_probe)) {
140 dev_dbg(dev, "Added to deferred list\n");
141 list_add_tail(new: &dev->p->deferred_probe, head: &deferred_probe_pending_list);
142 }
143 mutex_unlock(lock: &deferred_probe_mutex);
144}
145
146void driver_deferred_probe_del(struct device *dev)
147{
148 mutex_lock(lock: &deferred_probe_mutex);
149 if (!list_empty(head: &dev->p->deferred_probe)) {
150 dev_dbg(dev, "Removed from deferred list\n");
151 list_del_init(entry: &dev->p->deferred_probe);
152 __device_set_deferred_probe_reason(dev, NULL);
153 }
154 mutex_unlock(lock: &deferred_probe_mutex);
155}
156
157static bool driver_deferred_probe_enable;
158/**
159 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
160 *
161 * This functions moves all devices from the pending list to the active
162 * list and schedules the deferred probe workqueue to process them. It
163 * should be called anytime a driver is successfully bound to a device.
164 *
165 * Note, there is a race condition in multi-threaded probe. In the case where
166 * more than one device is probing at the same time, it is possible for one
167 * probe to complete successfully while another is about to defer. If the second
168 * depends on the first, then it will get put on the pending list after the
169 * trigger event has already occurred and will be stuck there.
170 *
171 * The atomic 'deferred_trigger_count' is used to determine if a successful
172 * trigger has occurred in the midst of probing a driver. If the trigger count
173 * changes in the midst of a probe, then deferred processing should be triggered
174 * again.
175 */
176void driver_deferred_probe_trigger(void)
177{
178 if (!driver_deferred_probe_enable)
179 return;
180
181 /*
182 * A successful probe means that all the devices in the pending list
183 * should be triggered to be reprobed. Move all the deferred devices
184 * into the active list so they can be retried by the workqueue
185 */
186 mutex_lock(lock: &deferred_probe_mutex);
187 atomic_inc(v: &deferred_trigger_count);
188 list_splice_tail_init(list: &deferred_probe_pending_list,
189 head: &deferred_probe_active_list);
190 mutex_unlock(lock: &deferred_probe_mutex);
191
192 /*
193 * Kick the re-probe thread. It may already be scheduled, but it is
194 * safe to kick it again.
195 */
196 queue_work(wq: system_unbound_wq, work: &deferred_probe_work);
197}
198
199/**
200 * device_block_probing() - Block/defer device's probes
201 *
202 * It will disable probing of devices and defer their probes instead.
203 */
204void device_block_probing(void)
205{
206 defer_all_probes = true;
207 /* sync with probes to avoid races. */
208 wait_for_device_probe();
209}
210
211/**
212 * device_unblock_probing() - Unblock/enable device's probes
213 *
214 * It will restore normal behavior and trigger re-probing of deferred
215 * devices.
216 */
217void device_unblock_probing(void)
218{
219 defer_all_probes = false;
220 driver_deferred_probe_trigger();
221}
222
223/**
224 * device_set_deferred_probe_reason() - Set defer probe reason message for device
225 * @dev: the pointer to the struct device
226 * @vaf: the pointer to va_format structure with message
227 */
228void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
229{
230 const char *drv = dev_driver_string(dev);
231 char *reason;
232
233 mutex_lock(lock: &deferred_probe_mutex);
234
235 reason = kasprintf(GFP_KERNEL, fmt: "%s: %pV", drv, vaf);
236 __device_set_deferred_probe_reason(dev, reason);
237
238 mutex_unlock(lock: &deferred_probe_mutex);
239}
240
241/*
242 * deferred_devs_show() - Show the devices in the deferred probe pending list.
243 */
244static int deferred_devs_show(struct seq_file *s, void *data)
245{
246 struct device_private *curr;
247
248 mutex_lock(lock: &deferred_probe_mutex);
249
250 list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
251 seq_printf(m: s, fmt: "%s\t%s", dev_name(dev: curr->device),
252 curr->deferred_probe_reason ?: "\n");
253
254 mutex_unlock(lock: &deferred_probe_mutex);
255
256 return 0;
257}
258DEFINE_SHOW_ATTRIBUTE(deferred_devs);
259
260#ifdef CONFIG_MODULES
261static int driver_deferred_probe_timeout = 10;
262#else
263static int driver_deferred_probe_timeout;
264#endif
265
266static int __init deferred_probe_timeout_setup(char *str)
267{
268 int timeout;
269
270 if (!kstrtoint(s: str, base: 10, res: &timeout))
271 driver_deferred_probe_timeout = timeout;
272 return 1;
273}
274__setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
275
276/**
277 * driver_deferred_probe_check_state() - Check deferred probe state
278 * @dev: device to check
279 *
280 * Return:
281 * * -ENODEV if initcalls have completed and modules are disabled.
282 * * -ETIMEDOUT if the deferred probe timeout was set and has expired
283 * and modules are enabled.
284 * * -EPROBE_DEFER in other cases.
285 *
286 * Drivers or subsystems can opt-in to calling this function instead of directly
287 * returning -EPROBE_DEFER.
288 */
289int driver_deferred_probe_check_state(struct device *dev)
290{
291 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
292 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
293 return -ENODEV;
294 }
295
296 if (!driver_deferred_probe_timeout && initcalls_done) {
297 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
298 return -ETIMEDOUT;
299 }
300
301 return -EPROBE_DEFER;
302}
303EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
304
305static void deferred_probe_timeout_work_func(struct work_struct *work)
306{
307 struct device_private *p;
308
309 fw_devlink_drivers_done();
310
311 driver_deferred_probe_timeout = 0;
312 driver_deferred_probe_trigger();
313 flush_work(work: &deferred_probe_work);
314
315 mutex_lock(lock: &deferred_probe_mutex);
316 list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
317 dev_warn(p->device, "deferred probe pending: %s", p->deferred_probe_reason ?: "(reason unknown)\n");
318 mutex_unlock(lock: &deferred_probe_mutex);
319
320 fw_devlink_probing_done();
321}
322static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
323
324void deferred_probe_extend_timeout(void)
325{
326 /*
327 * If the work hasn't been queued yet or if the work expired, don't
328 * start a new one.
329 */
330 if (cancel_delayed_work(dwork: &deferred_probe_timeout_work)) {
331 schedule_delayed_work(dwork: &deferred_probe_timeout_work,
332 delay: driver_deferred_probe_timeout * HZ);
333 pr_debug("Extended deferred probe timeout by %d secs\n",
334 driver_deferred_probe_timeout);
335 }
336}
337
338/**
339 * deferred_probe_initcall() - Enable probing of deferred devices
340 *
341 * We don't want to get in the way when the bulk of drivers are getting probed.
342 * Instead, this initcall makes sure that deferred probing is delayed until
343 * late_initcall time.
344 */
345static int deferred_probe_initcall(void)
346{
347 debugfs_create_file("devices_deferred", 0444, NULL, NULL,
348 &deferred_devs_fops);
349
350 driver_deferred_probe_enable = true;
351 driver_deferred_probe_trigger();
352 /* Sort as many dependencies as possible before exiting initcalls */
353 flush_work(work: &deferred_probe_work);
354 initcalls_done = true;
355
356 if (!IS_ENABLED(CONFIG_MODULES))
357 fw_devlink_drivers_done();
358
359 /*
360 * Trigger deferred probe again, this time we won't defer anything
361 * that is optional
362 */
363 driver_deferred_probe_trigger();
364 flush_work(work: &deferred_probe_work);
365
366 if (driver_deferred_probe_timeout > 0) {
367 schedule_delayed_work(dwork: &deferred_probe_timeout_work,
368 delay: driver_deferred_probe_timeout * HZ);
369 }
370
371 if (!IS_ENABLED(CONFIG_MODULES))
372 fw_devlink_probing_done();
373
374 return 0;
375}
376late_initcall(deferred_probe_initcall);
377
378static void __exit deferred_probe_exit(void)
379{
380 debugfs_lookup_and_remove(name: "devices_deferred", NULL);
381}
382__exitcall(deferred_probe_exit);
383
384/**
385 * device_is_bound() - Check if device is bound to a driver
386 * @dev: device to check
387 *
388 * Returns true if passed device has already finished probing successfully
389 * against a driver.
390 *
391 * This function must be called with the device lock held.
392 */
393bool device_is_bound(struct device *dev)
394{
395 return dev->p && klist_node_attached(n: &dev->p->knode_driver);
396}
397EXPORT_SYMBOL_GPL(device_is_bound);
398
399static void driver_bound(struct device *dev)
400{
401 if (device_is_bound(dev)) {
402 dev_warn(dev, "%s: device already bound\n", __func__);
403 return;
404 }
405
406 dev_dbg(dev, "driver: '%s': %s: bound to device\n", dev->driver->name,
407 __func__);
408
409 klist_add_tail(n: &dev->p->knode_driver, k: &dev->driver->p->klist_devices);
410 device_links_driver_bound(dev);
411
412 device_pm_check_callbacks(dev);
413
414 /*
415 * Make sure the device is no longer in one of the deferred lists and
416 * kick off retrying all pending devices
417 */
418 driver_deferred_probe_del(dev);
419 driver_deferred_probe_trigger();
420
421 bus_notify(dev, value: BUS_NOTIFY_BOUND_DRIVER);
422 kobject_uevent(kobj: &dev->kobj, action: KOBJ_BIND);
423}
424
425static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
426 const char *buf, size_t count)
427{
428 device_lock(dev);
429 dev->driver->coredump(dev);
430 device_unlock(dev);
431
432 return count;
433}
434static DEVICE_ATTR_WO(coredump);
435
436static int driver_sysfs_add(struct device *dev)
437{
438 int ret;
439
440 bus_notify(dev, value: BUS_NOTIFY_BIND_DRIVER);
441
442 ret = sysfs_create_link(kobj: &dev->driver->p->kobj, target: &dev->kobj,
443 name: kobject_name(kobj: &dev->kobj));
444 if (ret)
445 goto fail;
446
447 ret = sysfs_create_link(kobj: &dev->kobj, target: &dev->driver->p->kobj,
448 name: "driver");
449 if (ret)
450 goto rm_dev;
451
452 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
453 return 0;
454
455 ret = device_create_file(device: dev, entry: &dev_attr_coredump);
456 if (!ret)
457 return 0;
458
459 sysfs_remove_link(kobj: &dev->kobj, name: "driver");
460
461rm_dev:
462 sysfs_remove_link(kobj: &dev->driver->p->kobj,
463 name: kobject_name(kobj: &dev->kobj));
464
465fail:
466 return ret;
467}
468
469static void driver_sysfs_remove(struct device *dev)
470{
471 struct device_driver *drv = dev->driver;
472
473 if (drv) {
474 if (drv->coredump)
475 device_remove_file(dev, attr: &dev_attr_coredump);
476 sysfs_remove_link(kobj: &drv->p->kobj, name: kobject_name(kobj: &dev->kobj));
477 sysfs_remove_link(kobj: &dev->kobj, name: "driver");
478 }
479}
480
481/**
482 * device_bind_driver - bind a driver to one device.
483 * @dev: device.
484 *
485 * Allow manual attachment of a driver to a device.
486 * Caller must have already set @dev->driver.
487 *
488 * Note that this does not modify the bus reference count.
489 * Please verify that is accounted for before calling this.
490 * (It is ok to call with no other effort from a driver's probe() method.)
491 *
492 * This function must be called with the device lock held.
493 *
494 * Callers should prefer to use device_driver_attach() instead.
495 */
496int device_bind_driver(struct device *dev)
497{
498 int ret;
499
500 ret = driver_sysfs_add(dev);
501 if (!ret) {
502 device_links_force_bind(dev);
503 driver_bound(dev);
504 }
505 else
506 bus_notify(dev, value: BUS_NOTIFY_DRIVER_NOT_BOUND);
507 return ret;
508}
509EXPORT_SYMBOL_GPL(device_bind_driver);
510
511static atomic_t probe_count = ATOMIC_INIT(0);
512static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
513
514static ssize_t state_synced_store(struct device *dev,
515 struct device_attribute *attr,
516 const char *buf, size_t count)
517{
518 int ret = 0;
519
520 if (strcmp("1", buf))
521 return -EINVAL;
522
523 device_lock(dev);
524 if (!dev->state_synced) {
525 dev->state_synced = true;
526 dev_sync_state(dev);
527 } else {
528 ret = -EINVAL;
529 }
530 device_unlock(dev);
531
532 return ret ? ret : count;
533}
534
535static ssize_t state_synced_show(struct device *dev,
536 struct device_attribute *attr, char *buf)
537{
538 bool val;
539
540 device_lock(dev);
541 val = dev->state_synced;
542 device_unlock(dev);
543
544 return sysfs_emit(buf, fmt: "%u\n", val);
545}
546static DEVICE_ATTR_RW(state_synced);
547
548static void device_unbind_cleanup(struct device *dev)
549{
550 devres_release_all(dev);
551 arch_teardown_dma_ops(dev);
552 kfree(objp: dev->dma_range_map);
553 dev->dma_range_map = NULL;
554 device_set_driver(dev, NULL);
555 dev_set_drvdata(dev, NULL);
556 dev_pm_domain_detach(dev, power_off: dev->power.detach_power_off);
557 if (dev->pm_domain && dev->pm_domain->dismiss)
558 dev->pm_domain->dismiss(dev);
559 pm_runtime_reinit(dev);
560 dev_pm_set_driver_flags(dev, flags: 0);
561}
562
563static void device_remove(struct device *dev)
564{
565 device_remove_file(dev, attr: &dev_attr_state_synced);
566 device_remove_groups(dev, groups: dev->driver->dev_groups);
567
568 if (dev->bus && dev->bus->remove)
569 dev->bus->remove(dev);
570 else if (dev->driver->remove)
571 dev->driver->remove(dev);
572}
573
574static int call_driver_probe(struct device *dev, const struct device_driver *drv)
575{
576 int ret = 0;
577
578 if (dev->bus->probe)
579 ret = dev->bus->probe(dev);
580 else if (drv->probe)
581 ret = drv->probe(dev);
582
583 switch (ret) {
584 case 0:
585 break;
586 case -EPROBE_DEFER:
587 /* Driver requested deferred probing */
588 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
589 break;
590 case -ENODEV:
591 case -ENXIO:
592 dev_dbg(dev, "probe with driver %s rejects match %d\n",
593 drv->name, ret);
594 break;
595 default:
596 /* driver matched but the probe failed */
597 dev_err(dev, "probe with driver %s failed with error %d\n",
598 drv->name, ret);
599 break;
600 }
601
602 return ret;
603}
604
605static int really_probe(struct device *dev, const struct device_driver *drv)
606{
607 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
608 !drv->suppress_bind_attrs;
609 int ret, link_ret;
610
611 if (defer_all_probes) {
612 /*
613 * Value of defer_all_probes can be set only by
614 * device_block_probing() which, in turn, will call
615 * wait_for_device_probe() right after that to avoid any races.
616 */
617 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
618 return -EPROBE_DEFER;
619 }
620
621 link_ret = device_links_check_suppliers(dev);
622 if (link_ret == -EPROBE_DEFER)
623 return link_ret;
624
625 dev_dbg(dev, "bus: '%s': %s: probing driver %s with device\n",
626 drv->bus->name, __func__, drv->name);
627 if (!list_empty(head: &dev->devres_head)) {
628 dev_crit(dev, "Resources present before probing\n");
629 ret = -EBUSY;
630 goto done;
631 }
632
633re_probe:
634 device_set_driver(dev, drv);
635
636 /* If using pinctrl, bind pins now before probing */
637 ret = pinctrl_bind_pins(dev);
638 if (ret)
639 goto pinctrl_bind_failed;
640
641 if (dev->bus->dma_configure) {
642 ret = dev->bus->dma_configure(dev);
643 if (ret)
644 goto pinctrl_bind_failed;
645 }
646
647 ret = driver_sysfs_add(dev);
648 if (ret) {
649 dev_err(dev, "%s: driver_sysfs_add failed\n", __func__);
650 goto sysfs_failed;
651 }
652
653 if (dev->pm_domain && dev->pm_domain->activate) {
654 ret = dev->pm_domain->activate(dev);
655 if (ret)
656 goto probe_failed;
657 }
658
659 ret = call_driver_probe(dev, drv);
660 if (ret) {
661 /*
662 * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
663 * device might actually probe properly once some of its missing
664 * suppliers have probed. So, treat this as if the driver
665 * returned -EPROBE_DEFER.
666 */
667 if (link_ret == -EAGAIN)
668 ret = -EPROBE_DEFER;
669
670 /*
671 * Return probe errors as positive values so that the callers
672 * can distinguish them from other errors.
673 */
674 ret = -ret;
675 goto probe_failed;
676 }
677
678 ret = device_add_groups(dev, groups: drv->dev_groups);
679 if (ret) {
680 dev_err(dev, "device_add_groups() failed\n");
681 goto dev_groups_failed;
682 }
683
684 if (dev_has_sync_state(dev)) {
685 ret = device_create_file(device: dev, entry: &dev_attr_state_synced);
686 if (ret) {
687 dev_err(dev, "state_synced sysfs add failed\n");
688 goto dev_sysfs_state_synced_failed;
689 }
690 }
691
692 if (test_remove) {
693 test_remove = false;
694
695 device_remove(dev);
696 driver_sysfs_remove(dev);
697 if (dev->bus && dev->bus->dma_cleanup)
698 dev->bus->dma_cleanup(dev);
699 device_unbind_cleanup(dev);
700
701 goto re_probe;
702 }
703
704 pinctrl_init_done(dev);
705
706 if (dev->pm_domain && dev->pm_domain->sync)
707 dev->pm_domain->sync(dev);
708
709 driver_bound(dev);
710 dev_dbg(dev, "bus: '%s': %s: bound device to driver %s\n",
711 drv->bus->name, __func__, drv->name);
712 goto done;
713
714dev_sysfs_state_synced_failed:
715dev_groups_failed:
716 device_remove(dev);
717probe_failed:
718 driver_sysfs_remove(dev);
719sysfs_failed:
720 bus_notify(dev, value: BUS_NOTIFY_DRIVER_NOT_BOUND);
721 if (dev->bus && dev->bus->dma_cleanup)
722 dev->bus->dma_cleanup(dev);
723pinctrl_bind_failed:
724 device_links_no_driver(dev);
725 device_unbind_cleanup(dev);
726done:
727 return ret;
728}
729
730/*
731 * For initcall_debug, show the driver probe time.
732 */
733static int really_probe_debug(struct device *dev, const struct device_driver *drv)
734{
735 ktime_t calltime, rettime;
736 int ret;
737
738 calltime = ktime_get();
739 ret = really_probe(dev, drv);
740 rettime = ktime_get();
741 /*
742 * Don't change this to pr_debug() because that requires
743 * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the
744 * kernel commandline to print this all the time at the debug level.
745 */
746 printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
747 dev_name(dev), ret, ktime_us_delta(rettime, calltime));
748 return ret;
749}
750
751/**
752 * driver_probe_done
753 * Determine if the probe sequence is finished or not.
754 *
755 * Should somehow figure out how to use a semaphore, not an atomic variable...
756 */
757bool __init driver_probe_done(void)
758{
759 int local_probe_count = atomic_read(v: &probe_count);
760
761 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
762 return !local_probe_count;
763}
764
765/**
766 * wait_for_device_probe
767 * Wait for device probing to be completed.
768 */
769void wait_for_device_probe(void)
770{
771 /* wait for the deferred probe workqueue to finish */
772 flush_work(work: &deferred_probe_work);
773
774 /* wait for the known devices to complete their probing */
775 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
776 async_synchronize_full();
777}
778EXPORT_SYMBOL_GPL(wait_for_device_probe);
779
780static int __driver_probe_device(const struct device_driver *drv, struct device *dev)
781{
782 int ret = 0;
783
784 if (dev->p->dead || !device_is_registered(dev))
785 return -ENODEV;
786 if (dev->driver)
787 return -EBUSY;
788
789 dev->can_match = true;
790 dev_dbg(dev, "bus: '%s': %s: matched device with driver %s\n",
791 drv->bus->name, __func__, drv->name);
792
793 pm_runtime_get_suppliers(dev);
794 if (dev->parent)
795 pm_runtime_get_sync(dev: dev->parent);
796
797 pm_runtime_barrier(dev);
798 if (initcall_debug)
799 ret = really_probe_debug(dev, drv);
800 else
801 ret = really_probe(dev, drv);
802 pm_request_idle(dev);
803
804 if (dev->parent)
805 pm_runtime_put(dev: dev->parent);
806
807 pm_runtime_put_suppliers(dev);
808 return ret;
809}
810
811/**
812 * driver_probe_device - attempt to bind device & driver together
813 * @drv: driver to bind a device to
814 * @dev: device to try to bind to the driver
815 *
816 * This function returns -ENODEV if the device is not registered, -EBUSY if it
817 * already has a driver, 0 if the device is bound successfully and a positive
818 * (inverted) error code for failures from the ->probe method.
819 *
820 * This function must be called with @dev lock held. When called for a
821 * USB interface, @dev->parent lock must be held as well.
822 *
823 * If the device has a parent, runtime-resume the parent before driver probing.
824 */
825static int driver_probe_device(const struct device_driver *drv, struct device *dev)
826{
827 int trigger_count = atomic_read(v: &deferred_trigger_count);
828 int ret;
829
830 atomic_inc(v: &probe_count);
831 ret = __driver_probe_device(drv, dev);
832 if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
833 driver_deferred_probe_add(dev);
834
835 /*
836 * Did a trigger occur while probing? Need to re-trigger if yes
837 */
838 if (trigger_count != atomic_read(v: &deferred_trigger_count) &&
839 !defer_all_probes)
840 driver_deferred_probe_trigger();
841 }
842 atomic_dec(v: &probe_count);
843 wake_up_all(&probe_waitqueue);
844 return ret;
845}
846
847static inline bool cmdline_requested_async_probing(const char *drv_name)
848{
849 bool async_drv;
850
851 async_drv = parse_option_str(str: async_probe_drv_names, option: drv_name);
852
853 return (async_probe_default != async_drv);
854}
855
856/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
857static int __init save_async_options(char *buf)
858{
859 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
860 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
861
862 strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
863 async_probe_default = parse_option_str(str: async_probe_drv_names, option: "*");
864
865 return 1;
866}
867__setup("driver_async_probe=", save_async_options);
868
869static bool driver_allows_async_probing(const struct device_driver *drv)
870{
871 switch (drv->probe_type) {
872 case PROBE_PREFER_ASYNCHRONOUS:
873 return true;
874
875 case PROBE_FORCE_SYNCHRONOUS:
876 return false;
877
878 default:
879 if (cmdline_requested_async_probing(drv_name: drv->name))
880 return true;
881
882 if (module_requested_async_probing(module: drv->owner))
883 return true;
884
885 return false;
886 }
887}
888
889struct device_attach_data {
890 struct device *dev;
891
892 /*
893 * Indicates whether we are considering asynchronous probing or
894 * not. Only initial binding after device or driver registration
895 * (including deferral processing) may be done asynchronously, the
896 * rest is always synchronous, as we expect it is being done by
897 * request from userspace.
898 */
899 bool check_async;
900
901 /*
902 * Indicates if we are binding synchronous or asynchronous drivers.
903 * When asynchronous probing is enabled we'll execute 2 passes
904 * over drivers: first pass doing synchronous probing and second
905 * doing asynchronous probing (if synchronous did not succeed -
906 * most likely because there was no driver requiring synchronous
907 * probing - and we found asynchronous driver during first pass).
908 * The 2 passes are done because we can't shoot asynchronous
909 * probe for given device and driver from bus_for_each_drv() since
910 * driver pointer is not guaranteed to stay valid once
911 * bus_for_each_drv() iterates to the next driver on the bus.
912 */
913 bool want_async;
914
915 /*
916 * We'll set have_async to 'true' if, while scanning for matching
917 * driver, we'll encounter one that requests asynchronous probing.
918 */
919 bool have_async;
920};
921
922static int __device_attach_driver(struct device_driver *drv, void *_data)
923{
924 struct device_attach_data *data = _data;
925 struct device *dev = data->dev;
926 bool async_allowed;
927 int ret;
928
929 ret = driver_match_device(drv, dev);
930 if (ret == 0) {
931 /* no match */
932 return 0;
933 } else if (ret == -EPROBE_DEFER) {
934 dev_dbg(dev, "Device match requests probe deferral\n");
935 dev->can_match = true;
936 driver_deferred_probe_add(dev);
937 /*
938 * Device can't match with a driver right now, so don't attempt
939 * to match or bind with other drivers on the bus.
940 */
941 return ret;
942 } else if (ret < 0) {
943 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
944 return ret;
945 } /* ret > 0 means positive match */
946
947 async_allowed = driver_allows_async_probing(drv);
948
949 if (async_allowed)
950 data->have_async = true;
951
952 if (data->check_async && async_allowed != data->want_async)
953 return 0;
954
955 /*
956 * Ignore errors returned by ->probe so that the next driver can try
957 * its luck.
958 */
959 ret = driver_probe_device(drv, dev);
960 if (ret < 0)
961 return ret;
962 return ret == 0;
963}
964
965static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
966{
967 struct device *dev = _dev;
968 struct device_attach_data data = {
969 .dev = dev,
970 .check_async = true,
971 .want_async = true,
972 };
973
974 device_lock(dev);
975
976 /*
977 * Check if device has already been removed or claimed. This may
978 * happen with driver loading, device discovery/registration,
979 * and deferred probe processing happens all at once with
980 * multiple threads.
981 */
982 if (dev->p->dead || dev->driver)
983 goto out_unlock;
984
985 if (dev->parent)
986 pm_runtime_get_sync(dev: dev->parent);
987
988 bus_for_each_drv(bus: dev->bus, NULL, data: &data, fn: __device_attach_driver);
989 dev_dbg(dev, "async probe completed\n");
990
991 pm_request_idle(dev);
992
993 if (dev->parent)
994 pm_runtime_put(dev: dev->parent);
995out_unlock:
996 device_unlock(dev);
997
998 put_device(dev);
999}
1000
1001static int __device_attach(struct device *dev, bool allow_async)
1002{
1003 int ret = 0;
1004 bool async = false;
1005
1006 device_lock(dev);
1007 if (dev->p->dead) {
1008 goto out_unlock;
1009 } else if (dev->driver) {
1010 if (device_is_bound(dev)) {
1011 ret = 1;
1012 goto out_unlock;
1013 }
1014 ret = device_bind_driver(dev);
1015 if (ret == 0)
1016 ret = 1;
1017 else {
1018 device_set_driver(dev, NULL);
1019 ret = 0;
1020 }
1021 } else {
1022 struct device_attach_data data = {
1023 .dev = dev,
1024 .check_async = allow_async,
1025 .want_async = false,
1026 };
1027
1028 if (dev->parent)
1029 pm_runtime_get_sync(dev: dev->parent);
1030
1031 ret = bus_for_each_drv(bus: dev->bus, NULL, data: &data,
1032 fn: __device_attach_driver);
1033 if (!ret && allow_async && data.have_async) {
1034 /*
1035 * If we could not find appropriate driver
1036 * synchronously and we are allowed to do
1037 * async probes and there are drivers that
1038 * want to probe asynchronously, we'll
1039 * try them.
1040 */
1041 dev_dbg(dev, "scheduling asynchronous probe\n");
1042 get_device(dev);
1043 async = true;
1044 } else {
1045 pm_request_idle(dev);
1046 }
1047
1048 if (dev->parent)
1049 pm_runtime_put(dev: dev->parent);
1050 }
1051out_unlock:
1052 device_unlock(dev);
1053 if (async)
1054 async_schedule_dev(func: __device_attach_async_helper, dev);
1055 return ret;
1056}
1057
1058/**
1059 * device_attach - try to attach device to a driver.
1060 * @dev: device.
1061 *
1062 * Walk the list of drivers that the bus has and call
1063 * driver_probe_device() for each pair. If a compatible
1064 * pair is found, break out and return.
1065 *
1066 * Returns 1 if the device was bound to a driver;
1067 * 0 if no matching driver was found;
1068 * -ENODEV if the device is not registered.
1069 *
1070 * When called for a USB interface, @dev->parent lock must be held.
1071 */
1072int device_attach(struct device *dev)
1073{
1074 return __device_attach(dev, allow_async: false);
1075}
1076EXPORT_SYMBOL_GPL(device_attach);
1077
1078void device_initial_probe(struct device *dev)
1079{
1080 __device_attach(dev, allow_async: true);
1081}
1082
1083/*
1084 * __device_driver_lock - acquire locks needed to manipulate dev->drv
1085 * @dev: Device we will update driver info for
1086 * @parent: Parent device. Needed if the bus requires parent lock
1087 *
1088 * This function will take the required locks for manipulating dev->drv.
1089 * Normally this will just be the @dev lock, but when called for a USB
1090 * interface, @parent lock will be held as well.
1091 */
1092static void __device_driver_lock(struct device *dev, struct device *parent)
1093{
1094 if (parent && dev->bus->need_parent_lock)
1095 device_lock(dev: parent);
1096 device_lock(dev);
1097}
1098
1099/*
1100 * __device_driver_unlock - release locks needed to manipulate dev->drv
1101 * @dev: Device we will update driver info for
1102 * @parent: Parent device. Needed if the bus requires parent lock
1103 *
1104 * This function will release the required locks for manipulating dev->drv.
1105 * Normally this will just be the @dev lock, but when called for a
1106 * USB interface, @parent lock will be released as well.
1107 */
1108static void __device_driver_unlock(struct device *dev, struct device *parent)
1109{
1110 device_unlock(dev);
1111 if (parent && dev->bus->need_parent_lock)
1112 device_unlock(dev: parent);
1113}
1114
1115/**
1116 * device_driver_attach - attach a specific driver to a specific device
1117 * @drv: Driver to attach
1118 * @dev: Device to attach it to
1119 *
1120 * Manually attach driver to a device. Will acquire both @dev lock and
1121 * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1122 */
1123int device_driver_attach(const struct device_driver *drv, struct device *dev)
1124{
1125 int ret;
1126
1127 __device_driver_lock(dev, parent: dev->parent);
1128 ret = __driver_probe_device(drv, dev);
1129 __device_driver_unlock(dev, parent: dev->parent);
1130
1131 /* also return probe errors as normal negative errnos */
1132 if (ret > 0)
1133 ret = -ret;
1134 if (ret == -EPROBE_DEFER)
1135 return -EAGAIN;
1136 return ret;
1137}
1138EXPORT_SYMBOL_GPL(device_driver_attach);
1139
1140static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1141{
1142 struct device *dev = _dev;
1143 const struct device_driver *drv;
1144 int ret;
1145
1146 __device_driver_lock(dev, parent: dev->parent);
1147 drv = dev->p->async_driver;
1148 dev->p->async_driver = NULL;
1149 ret = driver_probe_device(drv, dev);
1150 __device_driver_unlock(dev, parent: dev->parent);
1151
1152 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1153
1154 put_device(dev);
1155}
1156
1157static int __driver_attach(struct device *dev, void *data)
1158{
1159 const struct device_driver *drv = data;
1160 bool async = false;
1161 int ret;
1162
1163 /*
1164 * Lock device and try to bind to it. We drop the error
1165 * here and always return 0, because we need to keep trying
1166 * to bind to devices and some drivers will return an error
1167 * simply if it didn't support the device.
1168 *
1169 * driver_probe_device() will spit a warning if there
1170 * is an error.
1171 */
1172
1173 ret = driver_match_device(drv, dev);
1174 if (ret == 0) {
1175 /* no match */
1176 return 0;
1177 } else if (ret == -EPROBE_DEFER) {
1178 dev_dbg(dev, "Device match requests probe deferral\n");
1179 dev->can_match = true;
1180 driver_deferred_probe_add(dev);
1181 /*
1182 * Driver could not match with device, but may match with
1183 * another device on the bus.
1184 */
1185 return 0;
1186 } else if (ret < 0) {
1187 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1188 /*
1189 * Driver could not match with device, but may match with
1190 * another device on the bus.
1191 */
1192 return 0;
1193 } /* ret > 0 means positive match */
1194
1195 if (driver_allows_async_probing(drv)) {
1196 /*
1197 * Instead of probing the device synchronously we will
1198 * probe it asynchronously to allow for more parallelism.
1199 *
1200 * We only take the device lock here in order to guarantee
1201 * that the dev->driver and async_driver fields are protected
1202 */
1203 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1204 device_lock(dev);
1205 if (!dev->driver && !dev->p->async_driver) {
1206 get_device(dev);
1207 dev->p->async_driver = drv;
1208 async = true;
1209 }
1210 device_unlock(dev);
1211 if (async)
1212 async_schedule_dev(func: __driver_attach_async_helper, dev);
1213 return 0;
1214 }
1215
1216 __device_driver_lock(dev, parent: dev->parent);
1217 driver_probe_device(drv, dev);
1218 __device_driver_unlock(dev, parent: dev->parent);
1219
1220 return 0;
1221}
1222
1223/**
1224 * driver_attach - try to bind driver to devices.
1225 * @drv: driver.
1226 *
1227 * Walk the list of devices that the bus has on it and try to
1228 * match the driver with each one. If driver_probe_device()
1229 * returns 0 and the @dev->driver is set, we've found a
1230 * compatible pair.
1231 */
1232int driver_attach(const struct device_driver *drv)
1233{
1234 /* The (void *) will be put back to const * in __driver_attach() */
1235 return bus_for_each_dev(bus: drv->bus, NULL, data: (void *)drv, fn: __driver_attach);
1236}
1237EXPORT_SYMBOL_GPL(driver_attach);
1238
1239/*
1240 * __device_release_driver() must be called with @dev lock held.
1241 * When called for a USB interface, @dev->parent lock must be held as well.
1242 */
1243static void __device_release_driver(struct device *dev, struct device *parent)
1244{
1245 struct device_driver *drv;
1246
1247 drv = dev->driver;
1248 if (drv) {
1249 pm_runtime_get_sync(dev);
1250
1251 while (device_links_busy(dev)) {
1252 __device_driver_unlock(dev, parent);
1253
1254 device_links_unbind_consumers(dev);
1255
1256 __device_driver_lock(dev, parent);
1257 /*
1258 * A concurrent invocation of the same function might
1259 * have released the driver successfully while this one
1260 * was waiting, so check for that.
1261 */
1262 if (dev->driver != drv) {
1263 pm_runtime_put(dev);
1264 return;
1265 }
1266 }
1267
1268 driver_sysfs_remove(dev);
1269
1270 bus_notify(dev, value: BUS_NOTIFY_UNBIND_DRIVER);
1271
1272 pm_runtime_put_sync(dev);
1273
1274 device_remove(dev);
1275
1276 if (dev->bus && dev->bus->dma_cleanup)
1277 dev->bus->dma_cleanup(dev);
1278
1279 device_unbind_cleanup(dev);
1280 device_links_driver_cleanup(dev);
1281
1282 klist_remove(n: &dev->p->knode_driver);
1283 device_pm_check_callbacks(dev);
1284
1285 bus_notify(dev, value: BUS_NOTIFY_UNBOUND_DRIVER);
1286 kobject_uevent(kobj: &dev->kobj, action: KOBJ_UNBIND);
1287 }
1288}
1289
1290void device_release_driver_internal(struct device *dev,
1291 const struct device_driver *drv,
1292 struct device *parent)
1293{
1294 __device_driver_lock(dev, parent);
1295
1296 if (!drv || drv == dev->driver)
1297 __device_release_driver(dev, parent);
1298
1299 __device_driver_unlock(dev, parent);
1300}
1301
1302/**
1303 * device_release_driver - manually detach device from driver.
1304 * @dev: device.
1305 *
1306 * Manually detach device from driver.
1307 * When called for a USB interface, @dev->parent lock must be held.
1308 *
1309 * If this function is to be called with @dev->parent lock held, ensure that
1310 * the device's consumers are unbound in advance or that their locks can be
1311 * acquired under the @dev->parent lock.
1312 */
1313void device_release_driver(struct device *dev)
1314{
1315 /*
1316 * If anyone calls device_release_driver() recursively from
1317 * within their ->remove callback for the same device, they
1318 * will deadlock right here.
1319 */
1320 device_release_driver_internal(dev, NULL, NULL);
1321}
1322EXPORT_SYMBOL_GPL(device_release_driver);
1323
1324/**
1325 * device_driver_detach - detach driver from a specific device
1326 * @dev: device to detach driver from
1327 *
1328 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1329 * lock if needed.
1330 */
1331void device_driver_detach(struct device *dev)
1332{
1333 device_release_driver_internal(dev, NULL, parent: dev->parent);
1334}
1335
1336/**
1337 * driver_detach - detach driver from all devices it controls.
1338 * @drv: driver.
1339 */
1340void driver_detach(const struct device_driver *drv)
1341{
1342 struct device_private *dev_prv;
1343 struct device *dev;
1344
1345 if (driver_allows_async_probing(drv))
1346 async_synchronize_full();
1347
1348 for (;;) {
1349 spin_lock(lock: &drv->p->klist_devices.k_lock);
1350 if (list_empty(head: &drv->p->klist_devices.k_list)) {
1351 spin_unlock(lock: &drv->p->klist_devices.k_lock);
1352 break;
1353 }
1354 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1355 struct device_private,
1356 knode_driver.n_node);
1357 dev = dev_prv->device;
1358 get_device(dev);
1359 spin_unlock(lock: &drv->p->klist_devices.k_lock);
1360 device_release_driver_internal(dev, drv, parent: dev->parent);
1361 put_device(dev);
1362 }
1363}
1364