1// SPDX-License-Identifier: GPL-2.0
2/*
3 * drivers/base/dd.c - The core device/driver interactions.
4 *
5 * This file contains the (sometimes tricky) code that controls the
6 * interactions between devices and drivers, which primarily includes
7 * driver binding and unbinding.
8 *
9 * All of this code used to exist in drivers/base/bus.c, but was
10 * relocated to here in the name of compartmentalization (since it wasn't
11 * strictly code just for the 'struct bus_type'.
12 *
13 * Copyright (c) 2002-5 Patrick Mochel
14 * Copyright (c) 2002-3 Open Source Development Labs
15 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
16 * Copyright (c) 2007-2009 Novell Inc.
17 */
18
19#include <linux/debugfs.h>
20#include <linux/device.h>
21#include <linux/delay.h>
22#include <linux/dma-map-ops.h>
23#include <linux/init.h>
24#include <linux/module.h>
25#include <linux/kthread.h>
26#include <linux/wait.h>
27#include <linux/async.h>
28#include <linux/pm_runtime.h>
29#include <linux/pinctrl/devinfo.h>
30#include <linux/slab.h>
31
32#include "base.h"
33#include "power/power.h"
34
35/*
36 * Deferred Probe infrastructure.
37 *
38 * Sometimes driver probe order matters, but the kernel doesn't always have
39 * dependency information which means some drivers will get probed before a
40 * resource it depends on is available. For example, an SDHCI driver may
41 * first need a GPIO line from an i2c GPIO controller before it can be
42 * initialized. If a required resource is not available yet, a driver can
43 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
44 *
45 * Deferred probe maintains two lists of devices, a pending list and an active
46 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
47 * pending list. A successful driver probe will trigger moving all devices
48 * from the pending to the active list so that the workqueue will eventually
49 * retry them.
50 *
51 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
52 * of the (struct device*)->p->deferred_probe pointers are manipulated
53 */
54static DEFINE_MUTEX(deferred_probe_mutex);
55static LIST_HEAD(deferred_probe_pending_list);
56static LIST_HEAD(deferred_probe_active_list);
57static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
58static bool initcalls_done;
59
60/* Save the async probe drivers' name from kernel cmdline */
61#define ASYNC_DRV_NAMES_MAX_LEN 256
62static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
63static bool async_probe_default;
64
65/*
66 * In some cases, like suspend to RAM or hibernation, It might be reasonable
67 * to prohibit probing of devices as it could be unsafe.
68 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
69 */
70static bool defer_all_probes;
71
72static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
73{
74 kfree(objp: dev->p->deferred_probe_reason);
75 dev->p->deferred_probe_reason = reason;
76}
77
78/*
79 * deferred_probe_work_func() - Retry probing devices in the active list.
80 */
81static void deferred_probe_work_func(struct work_struct *work)
82{
83 struct device *dev;
84 struct device_private *private;
85 /*
86 * This block processes every device in the deferred 'active' list.
87 * Each device is removed from the active list and passed to
88 * bus_probe_device() to re-attempt the probe. The loop continues
89 * until every device in the active list is removed and retried.
90 *
91 * Note: Once the device is removed from the list and the mutex is
92 * released, it is possible for the device get freed by another thread
93 * and cause a illegal pointer dereference. This code uses
94 * get/put_device() to ensure the device structure cannot disappear
95 * from under our feet.
96 */
97 mutex_lock(&deferred_probe_mutex);
98 while (!list_empty(head: &deferred_probe_active_list)) {
99 private = list_first_entry(&deferred_probe_active_list,
100 typeof(*dev->p), deferred_probe);
101 dev = private->device;
102 list_del_init(entry: &private->deferred_probe);
103
104 get_device(dev);
105
106 __device_set_deferred_probe_reason(dev, NULL);
107
108 /*
109 * Drop the mutex while probing each device; the probe path may
110 * manipulate the deferred list
111 */
112 mutex_unlock(lock: &deferred_probe_mutex);
113
114 /*
115 * Force the device to the end of the dpm_list since
116 * the PM code assumes that the order we add things to
117 * the list is a good order for suspend but deferred
118 * probe makes that very unsafe.
119 */
120 device_pm_move_to_tail(dev);
121
122 dev_dbg(dev, "Retrying from deferred list\n");
123 bus_probe_device(dev);
124 mutex_lock(&deferred_probe_mutex);
125
126 put_device(dev);
127 }
128 mutex_unlock(lock: &deferred_probe_mutex);
129}
130static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
131
132void driver_deferred_probe_add(struct device *dev)
133{
134 if (!dev->can_match)
135 return;
136
137 mutex_lock(&deferred_probe_mutex);
138 if (list_empty(head: &dev->p->deferred_probe)) {
139 dev_dbg(dev, "Added to deferred list\n");
140 list_add_tail(new: &dev->p->deferred_probe, head: &deferred_probe_pending_list);
141 }
142 mutex_unlock(lock: &deferred_probe_mutex);
143}
144
145void driver_deferred_probe_del(struct device *dev)
146{
147 mutex_lock(&deferred_probe_mutex);
148 if (!list_empty(head: &dev->p->deferred_probe)) {
149 dev_dbg(dev, "Removed from deferred list\n");
150 list_del_init(entry: &dev->p->deferred_probe);
151 __device_set_deferred_probe_reason(dev, NULL);
152 }
153 mutex_unlock(lock: &deferred_probe_mutex);
154}
155
156static bool driver_deferred_probe_enable;
157/**
158 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
159 *
160 * This functions moves all devices from the pending list to the active
161 * list and schedules the deferred probe workqueue to process them. It
162 * should be called anytime a driver is successfully bound to a device.
163 *
164 * Note, there is a race condition in multi-threaded probe. In the case where
165 * more than one device is probing at the same time, it is possible for one
166 * probe to complete successfully while another is about to defer. If the second
167 * depends on the first, then it will get put on the pending list after the
168 * trigger event has already occurred and will be stuck there.
169 *
170 * The atomic 'deferred_trigger_count' is used to determine if a successful
171 * trigger has occurred in the midst of probing a driver. If the trigger count
172 * changes in the midst of a probe, then deferred processing should be triggered
173 * again.
174 */
175void driver_deferred_probe_trigger(void)
176{
177 if (!driver_deferred_probe_enable)
178 return;
179
180 /*
181 * A successful probe means that all the devices in the pending list
182 * should be triggered to be reprobed. Move all the deferred devices
183 * into the active list so they can be retried by the workqueue
184 */
185 mutex_lock(&deferred_probe_mutex);
186 atomic_inc(v: &deferred_trigger_count);
187 list_splice_tail_init(list: &deferred_probe_pending_list,
188 head: &deferred_probe_active_list);
189 mutex_unlock(lock: &deferred_probe_mutex);
190
191 /*
192 * Kick the re-probe thread. It may already be scheduled, but it is
193 * safe to kick it again.
194 */
195 queue_work(wq: system_unbound_wq, work: &deferred_probe_work);
196}
197
198/**
199 * device_block_probing() - Block/defer device's probes
200 *
201 * It will disable probing of devices and defer their probes instead.
202 */
203void device_block_probing(void)
204{
205 defer_all_probes = true;
206 /* sync with probes to avoid races. */
207 wait_for_device_probe();
208}
209
210/**
211 * device_unblock_probing() - Unblock/enable device's probes
212 *
213 * It will restore normal behavior and trigger re-probing of deferred
214 * devices.
215 */
216void device_unblock_probing(void)
217{
218 defer_all_probes = false;
219 driver_deferred_probe_trigger();
220}
221
222/**
223 * device_set_deferred_probe_reason() - Set defer probe reason message for device
224 * @dev: the pointer to the struct device
225 * @vaf: the pointer to va_format structure with message
226 */
227void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
228{
229 const char *drv = dev_driver_string(dev);
230 char *reason;
231
232 mutex_lock(&deferred_probe_mutex);
233
234 reason = kasprintf(GFP_KERNEL, fmt: "%s: %pV", drv, vaf);
235 __device_set_deferred_probe_reason(dev, reason);
236
237 mutex_unlock(lock: &deferred_probe_mutex);
238}
239
240/*
241 * deferred_devs_show() - Show the devices in the deferred probe pending list.
242 */
243static int deferred_devs_show(struct seq_file *s, void *data)
244{
245 struct device_private *curr;
246
247 mutex_lock(&deferred_probe_mutex);
248
249 list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
250 seq_printf(m: s, fmt: "%s\t%s", dev_name(dev: curr->device),
251 curr->deferred_probe_reason ?: "\n");
252
253 mutex_unlock(lock: &deferred_probe_mutex);
254
255 return 0;
256}
257DEFINE_SHOW_ATTRIBUTE(deferred_devs);
258
259#ifdef CONFIG_MODULES
260static int driver_deferred_probe_timeout = 10;
261#else
262static int driver_deferred_probe_timeout;
263#endif
264
265static int __init deferred_probe_timeout_setup(char *str)
266{
267 int timeout;
268
269 if (!kstrtoint(s: str, base: 10, res: &timeout))
270 driver_deferred_probe_timeout = timeout;
271 return 1;
272}
273__setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
274
275/**
276 * driver_deferred_probe_check_state() - Check deferred probe state
277 * @dev: device to check
278 *
279 * Return:
280 * * -ENODEV if initcalls have completed and modules are disabled.
281 * * -ETIMEDOUT if the deferred probe timeout was set and has expired
282 * and modules are enabled.
283 * * -EPROBE_DEFER in other cases.
284 *
285 * Drivers or subsystems can opt-in to calling this function instead of directly
286 * returning -EPROBE_DEFER.
287 */
288int driver_deferred_probe_check_state(struct device *dev)
289{
290 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
291 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
292 return -ENODEV;
293 }
294
295 if (!driver_deferred_probe_timeout && initcalls_done) {
296 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
297 return -ETIMEDOUT;
298 }
299
300 return -EPROBE_DEFER;
301}
302EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
303
304static void deferred_probe_timeout_work_func(struct work_struct *work)
305{
306 struct device_private *p;
307
308 fw_devlink_drivers_done();
309
310 driver_deferred_probe_timeout = 0;
311 driver_deferred_probe_trigger();
312 flush_work(work: &deferred_probe_work);
313
314 mutex_lock(&deferred_probe_mutex);
315 list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
316 dev_warn(p->device, "deferred probe pending: %s", p->deferred_probe_reason ?: "(reason unknown)\n");
317 mutex_unlock(lock: &deferred_probe_mutex);
318
319 fw_devlink_probing_done();
320}
321static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
322
323void deferred_probe_extend_timeout(void)
324{
325 /*
326 * If the work hasn't been queued yet or if the work expired, don't
327 * start a new one.
328 */
329 if (cancel_delayed_work(dwork: &deferred_probe_timeout_work)) {
330 schedule_delayed_work(dwork: &deferred_probe_timeout_work,
331 delay: driver_deferred_probe_timeout * HZ);
332 pr_debug("Extended deferred probe timeout by %d secs\n",
333 driver_deferred_probe_timeout);
334 }
335}
336
337/**
338 * deferred_probe_initcall() - Enable probing of deferred devices
339 *
340 * We don't want to get in the way when the bulk of drivers are getting probed.
341 * Instead, this initcall makes sure that deferred probing is delayed until
342 * late_initcall time.
343 */
344static int deferred_probe_initcall(void)
345{
346 debugfs_create_file("devices_deferred", 0444, NULL, NULL,
347 &deferred_devs_fops);
348
349 driver_deferred_probe_enable = true;
350 driver_deferred_probe_trigger();
351 /* Sort as many dependencies as possible before exiting initcalls */
352 flush_work(work: &deferred_probe_work);
353 initcalls_done = true;
354
355 if (!IS_ENABLED(CONFIG_MODULES))
356 fw_devlink_drivers_done();
357
358 /*
359 * Trigger deferred probe again, this time we won't defer anything
360 * that is optional
361 */
362 driver_deferred_probe_trigger();
363 flush_work(work: &deferred_probe_work);
364
365 if (driver_deferred_probe_timeout > 0) {
366 schedule_delayed_work(dwork: &deferred_probe_timeout_work,
367 delay: driver_deferred_probe_timeout * HZ);
368 }
369
370 if (!IS_ENABLED(CONFIG_MODULES))
371 fw_devlink_probing_done();
372
373 return 0;
374}
375late_initcall(deferred_probe_initcall);
376
377static void __exit deferred_probe_exit(void)
378{
379 debugfs_lookup_and_remove(name: "devices_deferred", NULL);
380}
381__exitcall(deferred_probe_exit);
382
383/**
384 * device_is_bound() - Check if device is bound to a driver
385 * @dev: device to check
386 *
387 * Returns true if passed device has already finished probing successfully
388 * against a driver.
389 *
390 * This function must be called with the device lock held.
391 */
392bool device_is_bound(struct device *dev)
393{
394 return dev->p && klist_node_attached(n: &dev->p->knode_driver);
395}
396EXPORT_SYMBOL_GPL(device_is_bound);
397
398static void driver_bound(struct device *dev)
399{
400 if (device_is_bound(dev)) {
401 dev_warn(dev, "%s: device already bound\n", __func__);
402 return;
403 }
404
405 dev_dbg(dev, "driver: '%s': %s: bound to device\n", dev->driver->name,
406 __func__);
407
408 klist_add_tail(n: &dev->p->knode_driver, k: &dev->driver->p->klist_devices);
409 device_links_driver_bound(dev);
410
411 device_pm_check_callbacks(dev);
412
413 /*
414 * Make sure the device is no longer in one of the deferred lists and
415 * kick off retrying all pending devices
416 */
417 driver_deferred_probe_del(dev);
418 driver_deferred_probe_trigger();
419
420 bus_notify(dev, value: BUS_NOTIFY_BOUND_DRIVER);
421 kobject_uevent(kobj: &dev->kobj, action: KOBJ_BIND);
422}
423
424static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
425 const char *buf, size_t count)
426{
427 device_lock(dev);
428 dev->driver->coredump(dev);
429 device_unlock(dev);
430
431 return count;
432}
433static DEVICE_ATTR_WO(coredump);
434
435static int driver_sysfs_add(struct device *dev)
436{
437 int ret;
438
439 bus_notify(dev, value: BUS_NOTIFY_BIND_DRIVER);
440
441 ret = sysfs_create_link(kobj: &dev->driver->p->kobj, target: &dev->kobj,
442 name: kobject_name(kobj: &dev->kobj));
443 if (ret)
444 goto fail;
445
446 ret = sysfs_create_link(kobj: &dev->kobj, target: &dev->driver->p->kobj,
447 name: "driver");
448 if (ret)
449 goto rm_dev;
450
451 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
452 return 0;
453
454 ret = device_create_file(device: dev, entry: &dev_attr_coredump);
455 if (!ret)
456 return 0;
457
458 sysfs_remove_link(kobj: &dev->kobj, name: "driver");
459
460rm_dev:
461 sysfs_remove_link(kobj: &dev->driver->p->kobj,
462 name: kobject_name(kobj: &dev->kobj));
463
464fail:
465 return ret;
466}
467
468static void driver_sysfs_remove(struct device *dev)
469{
470 struct device_driver *drv = dev->driver;
471
472 if (drv) {
473 if (drv->coredump)
474 device_remove_file(dev, attr: &dev_attr_coredump);
475 sysfs_remove_link(kobj: &drv->p->kobj, name: kobject_name(kobj: &dev->kobj));
476 sysfs_remove_link(kobj: &dev->kobj, name: "driver");
477 }
478}
479
480/**
481 * device_bind_driver - bind a driver to one device.
482 * @dev: device.
483 *
484 * Allow manual attachment of a driver to a device.
485 * Caller must have already set @dev->driver.
486 *
487 * Note that this does not modify the bus reference count.
488 * Please verify that is accounted for before calling this.
489 * (It is ok to call with no other effort from a driver's probe() method.)
490 *
491 * This function must be called with the device lock held.
492 *
493 * Callers should prefer to use device_driver_attach() instead.
494 */
495int device_bind_driver(struct device *dev)
496{
497 int ret;
498
499 ret = driver_sysfs_add(dev);
500 if (!ret) {
501 device_links_force_bind(dev);
502 driver_bound(dev);
503 }
504 else
505 bus_notify(dev, value: BUS_NOTIFY_DRIVER_NOT_BOUND);
506 return ret;
507}
508EXPORT_SYMBOL_GPL(device_bind_driver);
509
510static atomic_t probe_count = ATOMIC_INIT(0);
511static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
512
513static ssize_t state_synced_store(struct device *dev,
514 struct device_attribute *attr,
515 const char *buf, size_t count)
516{
517 int ret = 0;
518
519 if (strcmp("1", buf))
520 return -EINVAL;
521
522 device_lock(dev);
523 if (!dev->state_synced) {
524 dev->state_synced = true;
525 dev_sync_state(dev);
526 } else {
527 ret = -EINVAL;
528 }
529 device_unlock(dev);
530
531 return ret ? ret : count;
532}
533
534static ssize_t state_synced_show(struct device *dev,
535 struct device_attribute *attr, char *buf)
536{
537 bool val;
538
539 device_lock(dev);
540 val = dev->state_synced;
541 device_unlock(dev);
542
543 return sysfs_emit(buf, fmt: "%u\n", val);
544}
545static DEVICE_ATTR_RW(state_synced);
546
547static void device_unbind_cleanup(struct device *dev)
548{
549 devres_release_all(dev);
550 arch_teardown_dma_ops(dev);
551 kfree(objp: dev->dma_range_map);
552 dev->dma_range_map = NULL;
553 device_set_driver(dev, NULL);
554 dev_set_drvdata(dev, NULL);
555 if (dev->pm_domain && dev->pm_domain->dismiss)
556 dev->pm_domain->dismiss(dev);
557 pm_runtime_reinit(dev);
558 dev_pm_set_driver_flags(dev, flags: 0);
559}
560
561static void device_remove(struct device *dev)
562{
563 device_remove_file(dev, attr: &dev_attr_state_synced);
564 device_remove_groups(dev, groups: dev->driver->dev_groups);
565
566 if (dev->bus && dev->bus->remove)
567 dev->bus->remove(dev);
568 else if (dev->driver->remove)
569 dev->driver->remove(dev);
570}
571
572static int call_driver_probe(struct device *dev, const struct device_driver *drv)
573{
574 int ret = 0;
575
576 if (dev->bus->probe)
577 ret = dev->bus->probe(dev);
578 else if (drv->probe)
579 ret = drv->probe(dev);
580
581 switch (ret) {
582 case 0:
583 break;
584 case -EPROBE_DEFER:
585 /* Driver requested deferred probing */
586 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
587 break;
588 case -ENODEV:
589 case -ENXIO:
590 dev_dbg(dev, "probe with driver %s rejects match %d\n",
591 drv->name, ret);
592 break;
593 default:
594 /* driver matched but the probe failed */
595 dev_err(dev, "probe with driver %s failed with error %d\n",
596 drv->name, ret);
597 break;
598 }
599
600 return ret;
601}
602
603static int really_probe(struct device *dev, const struct device_driver *drv)
604{
605 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
606 !drv->suppress_bind_attrs;
607 int ret, link_ret;
608
609 if (defer_all_probes) {
610 /*
611 * Value of defer_all_probes can be set only by
612 * device_block_probing() which, in turn, will call
613 * wait_for_device_probe() right after that to avoid any races.
614 */
615 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
616 return -EPROBE_DEFER;
617 }
618
619 link_ret = device_links_check_suppliers(dev);
620 if (link_ret == -EPROBE_DEFER)
621 return link_ret;
622
623 dev_dbg(dev, "bus: '%s': %s: probing driver %s with device\n",
624 drv->bus->name, __func__, drv->name);
625 if (!list_empty(head: &dev->devres_head)) {
626 dev_crit(dev, "Resources present before probing\n");
627 ret = -EBUSY;
628 goto done;
629 }
630
631re_probe:
632 device_set_driver(dev, drv);
633
634 /* If using pinctrl, bind pins now before probing */
635 ret = pinctrl_bind_pins(dev);
636 if (ret)
637 goto pinctrl_bind_failed;
638
639 if (dev->bus->dma_configure) {
640 ret = dev->bus->dma_configure(dev);
641 if (ret)
642 goto pinctrl_bind_failed;
643 }
644
645 ret = driver_sysfs_add(dev);
646 if (ret) {
647 dev_err(dev, "%s: driver_sysfs_add failed\n", __func__);
648 goto sysfs_failed;
649 }
650
651 if (dev->pm_domain && dev->pm_domain->activate) {
652 ret = dev->pm_domain->activate(dev);
653 if (ret)
654 goto probe_failed;
655 }
656
657 ret = call_driver_probe(dev, drv);
658 if (ret) {
659 /*
660 * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
661 * device might actually probe properly once some of its missing
662 * suppliers have probed. So, treat this as if the driver
663 * returned -EPROBE_DEFER.
664 */
665 if (link_ret == -EAGAIN)
666 ret = -EPROBE_DEFER;
667
668 /*
669 * Return probe errors as positive values so that the callers
670 * can distinguish them from other errors.
671 */
672 ret = -ret;
673 goto probe_failed;
674 }
675
676 ret = device_add_groups(dev, groups: drv->dev_groups);
677 if (ret) {
678 dev_err(dev, "device_add_groups() failed\n");
679 goto dev_groups_failed;
680 }
681
682 if (dev_has_sync_state(dev)) {
683 ret = device_create_file(device: dev, entry: &dev_attr_state_synced);
684 if (ret) {
685 dev_err(dev, "state_synced sysfs add failed\n");
686 goto dev_sysfs_state_synced_failed;
687 }
688 }
689
690 if (test_remove) {
691 test_remove = false;
692
693 device_remove(dev);
694 driver_sysfs_remove(dev);
695 if (dev->bus && dev->bus->dma_cleanup)
696 dev->bus->dma_cleanup(dev);
697 device_unbind_cleanup(dev);
698
699 goto re_probe;
700 }
701
702 pinctrl_init_done(dev);
703
704 if (dev->pm_domain && dev->pm_domain->sync)
705 dev->pm_domain->sync(dev);
706
707 driver_bound(dev);
708 dev_dbg(dev, "bus: '%s': %s: bound device to driver %s\n",
709 drv->bus->name, __func__, drv->name);
710 goto done;
711
712dev_sysfs_state_synced_failed:
713dev_groups_failed:
714 device_remove(dev);
715probe_failed:
716 driver_sysfs_remove(dev);
717sysfs_failed:
718 bus_notify(dev, value: BUS_NOTIFY_DRIVER_NOT_BOUND);
719 if (dev->bus && dev->bus->dma_cleanup)
720 dev->bus->dma_cleanup(dev);
721pinctrl_bind_failed:
722 device_links_no_driver(dev);
723 device_unbind_cleanup(dev);
724done:
725 return ret;
726}
727
728/*
729 * For initcall_debug, show the driver probe time.
730 */
731static int really_probe_debug(struct device *dev, const struct device_driver *drv)
732{
733 ktime_t calltime, rettime;
734 int ret;
735
736 calltime = ktime_get();
737 ret = really_probe(dev, drv);
738 rettime = ktime_get();
739 /*
740 * Don't change this to pr_debug() because that requires
741 * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the
742 * kernel commandline to print this all the time at the debug level.
743 */
744 printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
745 dev_name(dev), ret, ktime_us_delta(rettime, calltime));
746 return ret;
747}
748
749/**
750 * driver_probe_done
751 * Determine if the probe sequence is finished or not.
752 *
753 * Should somehow figure out how to use a semaphore, not an atomic variable...
754 */
755bool __init driver_probe_done(void)
756{
757 int local_probe_count = atomic_read(v: &probe_count);
758
759 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
760 return !local_probe_count;
761}
762
763/**
764 * wait_for_device_probe
765 * Wait for device probing to be completed.
766 */
767void wait_for_device_probe(void)
768{
769 /* wait for the deferred probe workqueue to finish */
770 flush_work(work: &deferred_probe_work);
771
772 /* wait for the known devices to complete their probing */
773 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
774 async_synchronize_full();
775}
776EXPORT_SYMBOL_GPL(wait_for_device_probe);
777
778static int __driver_probe_device(const struct device_driver *drv, struct device *dev)
779{
780 int ret = 0;
781
782 if (dev->p->dead || !device_is_registered(dev))
783 return -ENODEV;
784 if (dev->driver)
785 return -EBUSY;
786
787 dev->can_match = true;
788 dev_dbg(dev, "bus: '%s': %s: matched device with driver %s\n",
789 drv->bus->name, __func__, drv->name);
790
791 pm_runtime_get_suppliers(dev);
792 if (dev->parent)
793 pm_runtime_get_sync(dev: dev->parent);
794
795 pm_runtime_barrier(dev);
796 if (initcall_debug)
797 ret = really_probe_debug(dev, drv);
798 else
799 ret = really_probe(dev, drv);
800 pm_request_idle(dev);
801
802 if (dev->parent)
803 pm_runtime_put(dev: dev->parent);
804
805 pm_runtime_put_suppliers(dev);
806 return ret;
807}
808
809/**
810 * driver_probe_device - attempt to bind device & driver together
811 * @drv: driver to bind a device to
812 * @dev: device to try to bind to the driver
813 *
814 * This function returns -ENODEV if the device is not registered, -EBUSY if it
815 * already has a driver, 0 if the device is bound successfully and a positive
816 * (inverted) error code for failures from the ->probe method.
817 *
818 * This function must be called with @dev lock held. When called for a
819 * USB interface, @dev->parent lock must be held as well.
820 *
821 * If the device has a parent, runtime-resume the parent before driver probing.
822 */
823static int driver_probe_device(const struct device_driver *drv, struct device *dev)
824{
825 int trigger_count = atomic_read(v: &deferred_trigger_count);
826 int ret;
827
828 atomic_inc(v: &probe_count);
829 ret = __driver_probe_device(drv, dev);
830 if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
831 driver_deferred_probe_add(dev);
832
833 /*
834 * Did a trigger occur while probing? Need to re-trigger if yes
835 */
836 if (trigger_count != atomic_read(v: &deferred_trigger_count) &&
837 !defer_all_probes)
838 driver_deferred_probe_trigger();
839 }
840 atomic_dec(v: &probe_count);
841 wake_up_all(&probe_waitqueue);
842 return ret;
843}
844
845static inline bool cmdline_requested_async_probing(const char *drv_name)
846{
847 bool async_drv;
848
849 async_drv = parse_option_str(str: async_probe_drv_names, option: drv_name);
850
851 return (async_probe_default != async_drv);
852}
853
854/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
855static int __init save_async_options(char *buf)
856{
857 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
858 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
859
860 strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
861 async_probe_default = parse_option_str(str: async_probe_drv_names, option: "*");
862
863 return 1;
864}
865__setup("driver_async_probe=", save_async_options);
866
867static bool driver_allows_async_probing(const struct device_driver *drv)
868{
869 switch (drv->probe_type) {
870 case PROBE_PREFER_ASYNCHRONOUS:
871 return true;
872
873 case PROBE_FORCE_SYNCHRONOUS:
874 return false;
875
876 default:
877 if (cmdline_requested_async_probing(drv_name: drv->name))
878 return true;
879
880 if (module_requested_async_probing(module: drv->owner))
881 return true;
882
883 return false;
884 }
885}
886
887struct device_attach_data {
888 struct device *dev;
889
890 /*
891 * Indicates whether we are considering asynchronous probing or
892 * not. Only initial binding after device or driver registration
893 * (including deferral processing) may be done asynchronously, the
894 * rest is always synchronous, as we expect it is being done by
895 * request from userspace.
896 */
897 bool check_async;
898
899 /*
900 * Indicates if we are binding synchronous or asynchronous drivers.
901 * When asynchronous probing is enabled we'll execute 2 passes
902 * over drivers: first pass doing synchronous probing and second
903 * doing asynchronous probing (if synchronous did not succeed -
904 * most likely because there was no driver requiring synchronous
905 * probing - and we found asynchronous driver during first pass).
906 * The 2 passes are done because we can't shoot asynchronous
907 * probe for given device and driver from bus_for_each_drv() since
908 * driver pointer is not guaranteed to stay valid once
909 * bus_for_each_drv() iterates to the next driver on the bus.
910 */
911 bool want_async;
912
913 /*
914 * We'll set have_async to 'true' if, while scanning for matching
915 * driver, we'll encounter one that requests asynchronous probing.
916 */
917 bool have_async;
918};
919
920static int __device_attach_driver(struct device_driver *drv, void *_data)
921{
922 struct device_attach_data *data = _data;
923 struct device *dev = data->dev;
924 bool async_allowed;
925 int ret;
926
927 ret = driver_match_device(drv, dev);
928 if (ret == 0) {
929 /* no match */
930 return 0;
931 } else if (ret == -EPROBE_DEFER) {
932 dev_dbg(dev, "Device match requests probe deferral\n");
933 dev->can_match = true;
934 driver_deferred_probe_add(dev);
935 /*
936 * Device can't match with a driver right now, so don't attempt
937 * to match or bind with other drivers on the bus.
938 */
939 return ret;
940 } else if (ret < 0) {
941 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
942 return ret;
943 } /* ret > 0 means positive match */
944
945 async_allowed = driver_allows_async_probing(drv);
946
947 if (async_allowed)
948 data->have_async = true;
949
950 if (data->check_async && async_allowed != data->want_async)
951 return 0;
952
953 /*
954 * Ignore errors returned by ->probe so that the next driver can try
955 * its luck.
956 */
957 ret = driver_probe_device(drv, dev);
958 if (ret < 0)
959 return ret;
960 return ret == 0;
961}
962
963static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
964{
965 struct device *dev = _dev;
966 struct device_attach_data data = {
967 .dev = dev,
968 .check_async = true,
969 .want_async = true,
970 };
971
972 device_lock(dev);
973
974 /*
975 * Check if device has already been removed or claimed. This may
976 * happen with driver loading, device discovery/registration,
977 * and deferred probe processing happens all at once with
978 * multiple threads.
979 */
980 if (dev->p->dead || dev->driver)
981 goto out_unlock;
982
983 if (dev->parent)
984 pm_runtime_get_sync(dev: dev->parent);
985
986 bus_for_each_drv(bus: dev->bus, NULL, data: &data, fn: __device_attach_driver);
987 dev_dbg(dev, "async probe completed\n");
988
989 pm_request_idle(dev);
990
991 if (dev->parent)
992 pm_runtime_put(dev: dev->parent);
993out_unlock:
994 device_unlock(dev);
995
996 put_device(dev);
997}
998
999static int __device_attach(struct device *dev, bool allow_async)
1000{
1001 int ret = 0;
1002 bool async = false;
1003
1004 device_lock(dev);
1005 if (dev->p->dead) {
1006 goto out_unlock;
1007 } else if (dev->driver) {
1008 if (device_is_bound(dev)) {
1009 ret = 1;
1010 goto out_unlock;
1011 }
1012 ret = device_bind_driver(dev);
1013 if (ret == 0)
1014 ret = 1;
1015 else {
1016 device_set_driver(dev, NULL);
1017 ret = 0;
1018 }
1019 } else {
1020 struct device_attach_data data = {
1021 .dev = dev,
1022 .check_async = allow_async,
1023 .want_async = false,
1024 };
1025
1026 if (dev->parent)
1027 pm_runtime_get_sync(dev: dev->parent);
1028
1029 ret = bus_for_each_drv(bus: dev->bus, NULL, data: &data,
1030 fn: __device_attach_driver);
1031 if (!ret && allow_async && data.have_async) {
1032 /*
1033 * If we could not find appropriate driver
1034 * synchronously and we are allowed to do
1035 * async probes and there are drivers that
1036 * want to probe asynchronously, we'll
1037 * try them.
1038 */
1039 dev_dbg(dev, "scheduling asynchronous probe\n");
1040 get_device(dev);
1041 async = true;
1042 } else {
1043 pm_request_idle(dev);
1044 }
1045
1046 if (dev->parent)
1047 pm_runtime_put(dev: dev->parent);
1048 }
1049out_unlock:
1050 device_unlock(dev);
1051 if (async)
1052 async_schedule_dev(func: __device_attach_async_helper, dev);
1053 return ret;
1054}
1055
1056/**
1057 * device_attach - try to attach device to a driver.
1058 * @dev: device.
1059 *
1060 * Walk the list of drivers that the bus has and call
1061 * driver_probe_device() for each pair. If a compatible
1062 * pair is found, break out and return.
1063 *
1064 * Returns 1 if the device was bound to a driver;
1065 * 0 if no matching driver was found;
1066 * -ENODEV if the device is not registered.
1067 *
1068 * When called for a USB interface, @dev->parent lock must be held.
1069 */
1070int device_attach(struct device *dev)
1071{
1072 return __device_attach(dev, allow_async: false);
1073}
1074EXPORT_SYMBOL_GPL(device_attach);
1075
1076void device_initial_probe(struct device *dev)
1077{
1078 __device_attach(dev, allow_async: true);
1079}
1080
1081/*
1082 * __device_driver_lock - acquire locks needed to manipulate dev->drv
1083 * @dev: Device we will update driver info for
1084 * @parent: Parent device. Needed if the bus requires parent lock
1085 *
1086 * This function will take the required locks for manipulating dev->drv.
1087 * Normally this will just be the @dev lock, but when called for a USB
1088 * interface, @parent lock will be held as well.
1089 */
1090static void __device_driver_lock(struct device *dev, struct device *parent)
1091{
1092 if (parent && dev->bus->need_parent_lock)
1093 device_lock(dev: parent);
1094 device_lock(dev);
1095}
1096
1097/*
1098 * __device_driver_unlock - release locks needed to manipulate dev->drv
1099 * @dev: Device we will update driver info for
1100 * @parent: Parent device. Needed if the bus requires parent lock
1101 *
1102 * This function will release the required locks for manipulating dev->drv.
1103 * Normally this will just be the @dev lock, but when called for a
1104 * USB interface, @parent lock will be released as well.
1105 */
1106static void __device_driver_unlock(struct device *dev, struct device *parent)
1107{
1108 device_unlock(dev);
1109 if (parent && dev->bus->need_parent_lock)
1110 device_unlock(dev: parent);
1111}
1112
1113/**
1114 * device_driver_attach - attach a specific driver to a specific device
1115 * @drv: Driver to attach
1116 * @dev: Device to attach it to
1117 *
1118 * Manually attach driver to a device. Will acquire both @dev lock and
1119 * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1120 */
1121int device_driver_attach(const struct device_driver *drv, struct device *dev)
1122{
1123 int ret;
1124
1125 __device_driver_lock(dev, parent: dev->parent);
1126 ret = __driver_probe_device(drv, dev);
1127 __device_driver_unlock(dev, parent: dev->parent);
1128
1129 /* also return probe errors as normal negative errnos */
1130 if (ret > 0)
1131 ret = -ret;
1132 if (ret == -EPROBE_DEFER)
1133 return -EAGAIN;
1134 return ret;
1135}
1136EXPORT_SYMBOL_GPL(device_driver_attach);
1137
1138static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1139{
1140 struct device *dev = _dev;
1141 const struct device_driver *drv;
1142 int ret;
1143
1144 __device_driver_lock(dev, parent: dev->parent);
1145 drv = dev->p->async_driver;
1146 dev->p->async_driver = NULL;
1147 ret = driver_probe_device(drv, dev);
1148 __device_driver_unlock(dev, parent: dev->parent);
1149
1150 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1151
1152 put_device(dev);
1153}
1154
1155static int __driver_attach(struct device *dev, void *data)
1156{
1157 const struct device_driver *drv = data;
1158 bool async = false;
1159 int ret;
1160
1161 /*
1162 * Lock device and try to bind to it. We drop the error
1163 * here and always return 0, because we need to keep trying
1164 * to bind to devices and some drivers will return an error
1165 * simply if it didn't support the device.
1166 *
1167 * driver_probe_device() will spit a warning if there
1168 * is an error.
1169 */
1170
1171 ret = driver_match_device(drv, dev);
1172 if (ret == 0) {
1173 /* no match */
1174 return 0;
1175 } else if (ret == -EPROBE_DEFER) {
1176 dev_dbg(dev, "Device match requests probe deferral\n");
1177 dev->can_match = true;
1178 driver_deferred_probe_add(dev);
1179 /*
1180 * Driver could not match with device, but may match with
1181 * another device on the bus.
1182 */
1183 return 0;
1184 } else if (ret < 0) {
1185 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1186 /*
1187 * Driver could not match with device, but may match with
1188 * another device on the bus.
1189 */
1190 return 0;
1191 } /* ret > 0 means positive match */
1192
1193 if (driver_allows_async_probing(drv)) {
1194 /*
1195 * Instead of probing the device synchronously we will
1196 * probe it asynchronously to allow for more parallelism.
1197 *
1198 * We only take the device lock here in order to guarantee
1199 * that the dev->driver and async_driver fields are protected
1200 */
1201 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1202 device_lock(dev);
1203 if (!dev->driver && !dev->p->async_driver) {
1204 get_device(dev);
1205 dev->p->async_driver = drv;
1206 async = true;
1207 }
1208 device_unlock(dev);
1209 if (async)
1210 async_schedule_dev(func: __driver_attach_async_helper, dev);
1211 return 0;
1212 }
1213
1214 __device_driver_lock(dev, parent: dev->parent);
1215 driver_probe_device(drv, dev);
1216 __device_driver_unlock(dev, parent: dev->parent);
1217
1218 return 0;
1219}
1220
1221/**
1222 * driver_attach - try to bind driver to devices.
1223 * @drv: driver.
1224 *
1225 * Walk the list of devices that the bus has on it and try to
1226 * match the driver with each one. If driver_probe_device()
1227 * returns 0 and the @dev->driver is set, we've found a
1228 * compatible pair.
1229 */
1230int driver_attach(const struct device_driver *drv)
1231{
1232 /* The (void *) will be put back to const * in __driver_attach() */
1233 return bus_for_each_dev(bus: drv->bus, NULL, data: (void *)drv, fn: __driver_attach);
1234}
1235EXPORT_SYMBOL_GPL(driver_attach);
1236
1237/*
1238 * __device_release_driver() must be called with @dev lock held.
1239 * When called for a USB interface, @dev->parent lock must be held as well.
1240 */
1241static void __device_release_driver(struct device *dev, struct device *parent)
1242{
1243 struct device_driver *drv;
1244
1245 drv = dev->driver;
1246 if (drv) {
1247 pm_runtime_get_sync(dev);
1248
1249 while (device_links_busy(dev)) {
1250 __device_driver_unlock(dev, parent);
1251
1252 device_links_unbind_consumers(dev);
1253
1254 __device_driver_lock(dev, parent);
1255 /*
1256 * A concurrent invocation of the same function might
1257 * have released the driver successfully while this one
1258 * was waiting, so check for that.
1259 */
1260 if (dev->driver != drv) {
1261 pm_runtime_put(dev);
1262 return;
1263 }
1264 }
1265
1266 driver_sysfs_remove(dev);
1267
1268 bus_notify(dev, value: BUS_NOTIFY_UNBIND_DRIVER);
1269
1270 pm_runtime_put_sync(dev);
1271
1272 device_remove(dev);
1273
1274 if (dev->bus && dev->bus->dma_cleanup)
1275 dev->bus->dma_cleanup(dev);
1276
1277 device_unbind_cleanup(dev);
1278 device_links_driver_cleanup(dev);
1279
1280 klist_remove(n: &dev->p->knode_driver);
1281 device_pm_check_callbacks(dev);
1282
1283 bus_notify(dev, value: BUS_NOTIFY_UNBOUND_DRIVER);
1284 kobject_uevent(kobj: &dev->kobj, action: KOBJ_UNBIND);
1285 }
1286}
1287
1288void device_release_driver_internal(struct device *dev,
1289 const struct device_driver *drv,
1290 struct device *parent)
1291{
1292 __device_driver_lock(dev, parent);
1293
1294 if (!drv || drv == dev->driver)
1295 __device_release_driver(dev, parent);
1296
1297 __device_driver_unlock(dev, parent);
1298}
1299
1300/**
1301 * device_release_driver - manually detach device from driver.
1302 * @dev: device.
1303 *
1304 * Manually detach device from driver.
1305 * When called for a USB interface, @dev->parent lock must be held.
1306 *
1307 * If this function is to be called with @dev->parent lock held, ensure that
1308 * the device's consumers are unbound in advance or that their locks can be
1309 * acquired under the @dev->parent lock.
1310 */
1311void device_release_driver(struct device *dev)
1312{
1313 /*
1314 * If anyone calls device_release_driver() recursively from
1315 * within their ->remove callback for the same device, they
1316 * will deadlock right here.
1317 */
1318 device_release_driver_internal(dev, NULL, NULL);
1319}
1320EXPORT_SYMBOL_GPL(device_release_driver);
1321
1322/**
1323 * device_driver_detach - detach driver from a specific device
1324 * @dev: device to detach driver from
1325 *
1326 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1327 * lock if needed.
1328 */
1329void device_driver_detach(struct device *dev)
1330{
1331 device_release_driver_internal(dev, NULL, parent: dev->parent);
1332}
1333
1334/**
1335 * driver_detach - detach driver from all devices it controls.
1336 * @drv: driver.
1337 */
1338void driver_detach(const struct device_driver *drv)
1339{
1340 struct device_private *dev_prv;
1341 struct device *dev;
1342
1343 if (driver_allows_async_probing(drv))
1344 async_synchronize_full();
1345
1346 for (;;) {
1347 spin_lock(lock: &drv->p->klist_devices.k_lock);
1348 if (list_empty(head: &drv->p->klist_devices.k_list)) {
1349 spin_unlock(lock: &drv->p->klist_devices.k_lock);
1350 break;
1351 }
1352 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1353 struct device_private,
1354 knode_driver.n_node);
1355 dev = dev_prv->device;
1356 get_device(dev);
1357 spin_unlock(lock: &drv->p->klist_devices.k_lock);
1358 device_release_driver_internal(dev, drv, parent: dev->parent);
1359 put_device(dev);
1360 }
1361}
1362

source code of linux/drivers/base/dd.c

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