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(&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(&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(&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(&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(&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_dfl_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(&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(&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(&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 if (dev->driver->p_cb.post_unbind_rust)
552 dev->driver->p_cb.post_unbind_rust(dev);
553 arch_teardown_dma_ops(dev);
554 kfree(objp: dev->dma_range_map);
555 dev->dma_range_map = NULL;
556 device_set_driver(dev, NULL);
557 dev_set_drvdata(dev, NULL);
558 dev_pm_domain_detach(dev, power_off: dev->power.detach_power_off);
559 if (dev->pm_domain && dev->pm_domain->dismiss)
560 dev->pm_domain->dismiss(dev);
561 pm_runtime_reinit(dev);
562 dev_pm_set_driver_flags(dev, flags: 0);
563}
564
565static void device_remove(struct device *dev)
566{
567 device_remove_file(dev, attr: &dev_attr_state_synced);
568 device_remove_groups(dev, groups: dev->driver->dev_groups);
569
570 if (dev->bus && dev->bus->remove)
571 dev->bus->remove(dev);
572 else if (dev->driver->remove)
573 dev->driver->remove(dev);
574}
575
576static int call_driver_probe(struct device *dev, const struct device_driver *drv)
577{
578 int ret = 0;
579
580 if (dev->bus->probe)
581 ret = dev->bus->probe(dev);
582 else if (drv->probe)
583 ret = drv->probe(dev);
584
585 switch (ret) {
586 case 0:
587 break;
588 case -EPROBE_DEFER:
589 /* Driver requested deferred probing */
590 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
591 break;
592 case -ENODEV:
593 case -ENXIO:
594 dev_dbg(dev, "probe with driver %s rejects match %d\n",
595 drv->name, ret);
596 break;
597 default:
598 /* driver matched but the probe failed */
599 dev_err(dev, "probe with driver %s failed with error %d\n",
600 drv->name, ret);
601 break;
602 }
603
604 return ret;
605}
606
607static int really_probe(struct device *dev, const struct device_driver *drv)
608{
609 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
610 !drv->suppress_bind_attrs;
611 int ret, link_ret;
612
613 if (defer_all_probes) {
614 /*
615 * Value of defer_all_probes can be set only by
616 * device_block_probing() which, in turn, will call
617 * wait_for_device_probe() right after that to avoid any races.
618 */
619 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
620 return -EPROBE_DEFER;
621 }
622
623 link_ret = device_links_check_suppliers(dev);
624 if (link_ret == -EPROBE_DEFER)
625 return link_ret;
626
627 dev_dbg(dev, "bus: '%s': %s: probing driver %s with device\n",
628 drv->bus->name, __func__, drv->name);
629 if (!list_empty(head: &dev->devres_head)) {
630 dev_crit(dev, "Resources present before probing\n");
631 ret = -EBUSY;
632 goto done;
633 }
634
635re_probe:
636 device_set_driver(dev, drv);
637
638 /* If using pinctrl, bind pins now before probing */
639 ret = pinctrl_bind_pins(dev);
640 if (ret)
641 goto pinctrl_bind_failed;
642
643 if (dev->bus->dma_configure) {
644 ret = dev->bus->dma_configure(dev);
645 if (ret)
646 goto pinctrl_bind_failed;
647 }
648
649 ret = driver_sysfs_add(dev);
650 if (ret) {
651 dev_err(dev, "%s: driver_sysfs_add failed\n", __func__);
652 goto sysfs_failed;
653 }
654
655 if (dev->pm_domain && dev->pm_domain->activate) {
656 ret = dev->pm_domain->activate(dev);
657 if (ret)
658 goto probe_failed;
659 }
660
661 ret = call_driver_probe(dev, drv);
662 if (ret) {
663 /*
664 * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
665 * device might actually probe properly once some of its missing
666 * suppliers have probed. So, treat this as if the driver
667 * returned -EPROBE_DEFER.
668 */
669 if (link_ret == -EAGAIN)
670 ret = -EPROBE_DEFER;
671
672 /*
673 * Return probe errors as positive values so that the callers
674 * can distinguish them from other errors.
675 */
676 ret = -ret;
677 goto probe_failed;
678 }
679
680 ret = device_add_groups(dev, groups: drv->dev_groups);
681 if (ret) {
682 dev_err(dev, "device_add_groups() failed\n");
683 goto dev_groups_failed;
684 }
685
686 if (dev_has_sync_state(dev)) {
687 ret = device_create_file(device: dev, entry: &dev_attr_state_synced);
688 if (ret) {
689 dev_err(dev, "state_synced sysfs add failed\n");
690 goto dev_sysfs_state_synced_failed;
691 }
692 }
693
694 if (test_remove) {
695 test_remove = false;
696
697 device_remove(dev);
698 driver_sysfs_remove(dev);
699 if (dev->bus && dev->bus->dma_cleanup)
700 dev->bus->dma_cleanup(dev);
701 device_unbind_cleanup(dev);
702
703 goto re_probe;
704 }
705
706 pinctrl_init_done(dev);
707
708 if (dev->pm_domain && dev->pm_domain->sync)
709 dev->pm_domain->sync(dev);
710
711 driver_bound(dev);
712 dev_dbg(dev, "bus: '%s': %s: bound device to driver %s\n",
713 drv->bus->name, __func__, drv->name);
714 goto done;
715
716dev_sysfs_state_synced_failed:
717dev_groups_failed:
718 device_remove(dev);
719probe_failed:
720 driver_sysfs_remove(dev);
721sysfs_failed:
722 bus_notify(dev, value: BUS_NOTIFY_DRIVER_NOT_BOUND);
723 if (dev->bus && dev->bus->dma_cleanup)
724 dev->bus->dma_cleanup(dev);
725pinctrl_bind_failed:
726 device_links_no_driver(dev);
727 device_unbind_cleanup(dev);
728done:
729 return ret;
730}
731
732/*
733 * For initcall_debug, show the driver probe time.
734 */
735static int really_probe_debug(struct device *dev, const struct device_driver *drv)
736{
737 ktime_t calltime, rettime;
738 int ret;
739
740 calltime = ktime_get();
741 ret = really_probe(dev, drv);
742 rettime = ktime_get();
743 /*
744 * Don't change this to pr_debug() because that requires
745 * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the
746 * kernel commandline to print this all the time at the debug level.
747 */
748 printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
749 dev_name(dev), ret, ktime_us_delta(rettime, calltime));
750 return ret;
751}
752
753/**
754 * driver_probe_done
755 * Determine if the probe sequence is finished or not.
756 *
757 * Should somehow figure out how to use a semaphore, not an atomic variable...
758 */
759bool __init driver_probe_done(void)
760{
761 int local_probe_count = atomic_read(v: &probe_count);
762
763 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
764 return !local_probe_count;
765}
766
767/**
768 * wait_for_device_probe
769 * Wait for device probing to be completed.
770 */
771void wait_for_device_probe(void)
772{
773 /* wait for the deferred probe workqueue to finish */
774 flush_work(work: &deferred_probe_work);
775
776 /* wait for the known devices to complete their probing */
777 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
778 async_synchronize_full();
779}
780EXPORT_SYMBOL_GPL(wait_for_device_probe);
781
782static int __driver_probe_device(const struct device_driver *drv, struct device *dev)
783{
784 int ret = 0;
785
786 if (dev->p->dead || !device_is_registered(dev))
787 return -ENODEV;
788 if (dev->driver)
789 return -EBUSY;
790
791 dev->can_match = true;
792 dev_dbg(dev, "bus: '%s': %s: matched device with driver %s\n",
793 drv->bus->name, __func__, drv->name);
794
795 pm_runtime_get_suppliers(dev);
796 if (dev->parent)
797 pm_runtime_get_sync(dev: dev->parent);
798
799 pm_runtime_barrier(dev);
800 if (initcall_debug)
801 ret = really_probe_debug(dev, drv);
802 else
803 ret = really_probe(dev, drv);
804 pm_request_idle(dev);
805
806 if (dev->parent)
807 pm_runtime_put(dev: dev->parent);
808
809 pm_runtime_put_suppliers(dev);
810 return ret;
811}
812
813/**
814 * driver_probe_device - attempt to bind device & driver together
815 * @drv: driver to bind a device to
816 * @dev: device to try to bind to the driver
817 *
818 * This function returns -ENODEV if the device is not registered, -EBUSY if it
819 * already has a driver, 0 if the device is bound successfully and a positive
820 * (inverted) error code for failures from the ->probe method.
821 *
822 * This function must be called with @dev lock held. When called for a
823 * USB interface, @dev->parent lock must be held as well.
824 *
825 * If the device has a parent, runtime-resume the parent before driver probing.
826 */
827static int driver_probe_device(const struct device_driver *drv, struct device *dev)
828{
829 int trigger_count = atomic_read(v: &deferred_trigger_count);
830 int ret;
831
832 atomic_inc(v: &probe_count);
833 ret = __driver_probe_device(drv, dev);
834 if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
835 driver_deferred_probe_add(dev);
836
837 /*
838 * Did a trigger occur while probing? Need to re-trigger if yes
839 */
840 if (trigger_count != atomic_read(v: &deferred_trigger_count) &&
841 !defer_all_probes)
842 driver_deferred_probe_trigger();
843 }
844 atomic_dec(v: &probe_count);
845 wake_up_all(&probe_waitqueue);
846 return ret;
847}
848
849static inline bool cmdline_requested_async_probing(const char *drv_name)
850{
851 bool async_drv;
852
853 async_drv = parse_option_str(str: async_probe_drv_names, option: drv_name);
854
855 return (async_probe_default != async_drv);
856}
857
858/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
859static int __init save_async_options(char *buf)
860{
861 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
862 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
863
864 strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
865 async_probe_default = parse_option_str(str: async_probe_drv_names, option: "*");
866
867 return 1;
868}
869__setup("driver_async_probe=", save_async_options);
870
871static bool driver_allows_async_probing(const struct device_driver *drv)
872{
873 switch (drv->probe_type) {
874 case PROBE_PREFER_ASYNCHRONOUS:
875 return true;
876
877 case PROBE_FORCE_SYNCHRONOUS:
878 return false;
879
880 default:
881 if (cmdline_requested_async_probing(drv_name: drv->name))
882 return true;
883
884 if (module_requested_async_probing(module: drv->owner))
885 return true;
886
887 return false;
888 }
889}
890
891struct device_attach_data {
892 struct device *dev;
893
894 /*
895 * Indicates whether we are considering asynchronous probing or
896 * not. Only initial binding after device or driver registration
897 * (including deferral processing) may be done asynchronously, the
898 * rest is always synchronous, as we expect it is being done by
899 * request from userspace.
900 */
901 bool check_async;
902
903 /*
904 * Indicates if we are binding synchronous or asynchronous drivers.
905 * When asynchronous probing is enabled we'll execute 2 passes
906 * over drivers: first pass doing synchronous probing and second
907 * doing asynchronous probing (if synchronous did not succeed -
908 * most likely because there was no driver requiring synchronous
909 * probing - and we found asynchronous driver during first pass).
910 * The 2 passes are done because we can't shoot asynchronous
911 * probe for given device and driver from bus_for_each_drv() since
912 * driver pointer is not guaranteed to stay valid once
913 * bus_for_each_drv() iterates to the next driver on the bus.
914 */
915 bool want_async;
916
917 /*
918 * We'll set have_async to 'true' if, while scanning for matching
919 * driver, we'll encounter one that requests asynchronous probing.
920 */
921 bool have_async;
922};
923
924static int __device_attach_driver(struct device_driver *drv, void *_data)
925{
926 struct device_attach_data *data = _data;
927 struct device *dev = data->dev;
928 bool async_allowed;
929 int ret;
930
931 ret = driver_match_device(drv, dev);
932 if (ret == 0) {
933 /* no match */
934 return 0;
935 } else if (ret == -EPROBE_DEFER) {
936 dev_dbg(dev, "Device match requests probe deferral\n");
937 dev->can_match = true;
938 driver_deferred_probe_add(dev);
939 /*
940 * Device can't match with a driver right now, so don't attempt
941 * to match or bind with other drivers on the bus.
942 */
943 return ret;
944 } else if (ret < 0) {
945 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
946 return ret;
947 } /* ret > 0 means positive match */
948
949 async_allowed = driver_allows_async_probing(drv);
950
951 if (async_allowed)
952 data->have_async = true;
953
954 if (data->check_async && async_allowed != data->want_async)
955 return 0;
956
957 /*
958 * Ignore errors returned by ->probe so that the next driver can try
959 * its luck.
960 */
961 ret = driver_probe_device(drv, dev);
962 if (ret < 0)
963 return ret;
964 return ret == 0;
965}
966
967static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
968{
969 struct device *dev = _dev;
970 struct device_attach_data data = {
971 .dev = dev,
972 .check_async = true,
973 .want_async = true,
974 };
975
976 device_lock(dev);
977
978 /*
979 * Check if device has already been removed or claimed. This may
980 * happen with driver loading, device discovery/registration,
981 * and deferred probe processing happens all at once with
982 * multiple threads.
983 */
984 if (dev->p->dead || dev->driver)
985 goto out_unlock;
986
987 if (dev->parent)
988 pm_runtime_get_sync(dev: dev->parent);
989
990 bus_for_each_drv(bus: dev->bus, NULL, data: &data, fn: __device_attach_driver);
991 dev_dbg(dev, "async probe completed\n");
992
993 pm_request_idle(dev);
994
995 if (dev->parent)
996 pm_runtime_put(dev: dev->parent);
997out_unlock:
998 device_unlock(dev);
999
1000 put_device(dev);
1001}
1002
1003static int __device_attach(struct device *dev, bool allow_async)
1004{
1005 int ret = 0;
1006 bool async = false;
1007
1008 device_lock(dev);
1009 if (dev->p->dead) {
1010 goto out_unlock;
1011 } else if (dev->driver) {
1012 if (device_is_bound(dev)) {
1013 ret = 1;
1014 goto out_unlock;
1015 }
1016 ret = device_bind_driver(dev);
1017 if (ret == 0)
1018 ret = 1;
1019 else {
1020 device_set_driver(dev, NULL);
1021 ret = 0;
1022 }
1023 } else {
1024 struct device_attach_data data = {
1025 .dev = dev,
1026 .check_async = allow_async,
1027 .want_async = false,
1028 };
1029
1030 if (dev->parent)
1031 pm_runtime_get_sync(dev: dev->parent);
1032
1033 ret = bus_for_each_drv(bus: dev->bus, NULL, data: &data,
1034 fn: __device_attach_driver);
1035 if (!ret && allow_async && data.have_async) {
1036 /*
1037 * If we could not find appropriate driver
1038 * synchronously and we are allowed to do
1039 * async probes and there are drivers that
1040 * want to probe asynchronously, we'll
1041 * try them.
1042 */
1043 dev_dbg(dev, "scheduling asynchronous probe\n");
1044 get_device(dev);
1045 async = true;
1046 } else {
1047 pm_request_idle(dev);
1048 }
1049
1050 if (dev->parent)
1051 pm_runtime_put(dev: dev->parent);
1052 }
1053out_unlock:
1054 device_unlock(dev);
1055 if (async)
1056 async_schedule_dev(func: __device_attach_async_helper, dev);
1057 return ret;
1058}
1059
1060/**
1061 * device_attach - try to attach device to a driver.
1062 * @dev: device.
1063 *
1064 * Walk the list of drivers that the bus has and call
1065 * driver_probe_device() for each pair. If a compatible
1066 * pair is found, break out and return.
1067 *
1068 * Returns 1 if the device was bound to a driver;
1069 * 0 if no matching driver was found;
1070 * -ENODEV if the device is not registered.
1071 *
1072 * When called for a USB interface, @dev->parent lock must be held.
1073 */
1074int device_attach(struct device *dev)
1075{
1076 return __device_attach(dev, allow_async: false);
1077}
1078EXPORT_SYMBOL_GPL(device_attach);
1079
1080void device_initial_probe(struct device *dev)
1081{
1082 struct subsys_private *sp = bus_to_subsys(bus: dev->bus);
1083
1084 if (!sp)
1085 return;
1086
1087 if (sp->drivers_autoprobe)
1088 __device_attach(dev, allow_async: true);
1089
1090 subsys_put(sp);
1091}
1092
1093/*
1094 * __device_driver_lock - acquire locks needed to manipulate dev->drv
1095 * @dev: Device we will update driver info for
1096 * @parent: Parent device. Needed if the bus requires parent lock
1097 *
1098 * This function will take the required locks for manipulating dev->drv.
1099 * Normally this will just be the @dev lock, but when called for a USB
1100 * interface, @parent lock will be held as well.
1101 */
1102static void __device_driver_lock(struct device *dev, struct device *parent)
1103{
1104 if (parent && dev->bus->need_parent_lock)
1105 device_lock(dev: parent);
1106 device_lock(dev);
1107}
1108
1109/*
1110 * __device_driver_unlock - release locks needed to manipulate dev->drv
1111 * @dev: Device we will update driver info for
1112 * @parent: Parent device. Needed if the bus requires parent lock
1113 *
1114 * This function will release the required locks for manipulating dev->drv.
1115 * Normally this will just be the @dev lock, but when called for a
1116 * USB interface, @parent lock will be released as well.
1117 */
1118static void __device_driver_unlock(struct device *dev, struct device *parent)
1119{
1120 device_unlock(dev);
1121 if (parent && dev->bus->need_parent_lock)
1122 device_unlock(dev: parent);
1123}
1124
1125/**
1126 * device_driver_attach - attach a specific driver to a specific device
1127 * @drv: Driver to attach
1128 * @dev: Device to attach it to
1129 *
1130 * Manually attach driver to a device. Will acquire both @dev lock and
1131 * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1132 */
1133int device_driver_attach(const struct device_driver *drv, struct device *dev)
1134{
1135 int ret;
1136
1137 __device_driver_lock(dev, parent: dev->parent);
1138 ret = __driver_probe_device(drv, dev);
1139 __device_driver_unlock(dev, parent: dev->parent);
1140
1141 /* also return probe errors as normal negative errnos */
1142 if (ret > 0)
1143 ret = -ret;
1144 if (ret == -EPROBE_DEFER)
1145 return -EAGAIN;
1146 return ret;
1147}
1148EXPORT_SYMBOL_GPL(device_driver_attach);
1149
1150static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1151{
1152 struct device *dev = _dev;
1153 const struct device_driver *drv;
1154 int ret;
1155
1156 __device_driver_lock(dev, parent: dev->parent);
1157 drv = dev->p->async_driver;
1158 dev->p->async_driver = NULL;
1159 ret = driver_probe_device(drv, dev);
1160 __device_driver_unlock(dev, parent: dev->parent);
1161
1162 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1163
1164 put_device(dev);
1165}
1166
1167static int __driver_attach(struct device *dev, void *data)
1168{
1169 const struct device_driver *drv = data;
1170 bool async = false;
1171 int ret;
1172
1173 /*
1174 * Lock device and try to bind to it. We drop the error
1175 * here and always return 0, because we need to keep trying
1176 * to bind to devices and some drivers will return an error
1177 * simply if it didn't support the device.
1178 *
1179 * driver_probe_device() will spit a warning if there
1180 * is an error.
1181 */
1182
1183 ret = driver_match_device(drv, dev);
1184 if (ret == 0) {
1185 /* no match */
1186 return 0;
1187 } else if (ret == -EPROBE_DEFER) {
1188 dev_dbg(dev, "Device match requests probe deferral\n");
1189 dev->can_match = true;
1190 driver_deferred_probe_add(dev);
1191 /*
1192 * Driver could not match with device, but may match with
1193 * another device on the bus.
1194 */
1195 return 0;
1196 } else if (ret < 0) {
1197 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1198 /*
1199 * Driver could not match with device, but may match with
1200 * another device on the bus.
1201 */
1202 return 0;
1203 } /* ret > 0 means positive match */
1204
1205 if (driver_allows_async_probing(drv)) {
1206 /*
1207 * Instead of probing the device synchronously we will
1208 * probe it asynchronously to allow for more parallelism.
1209 *
1210 * We only take the device lock here in order to guarantee
1211 * that the dev->driver and async_driver fields are protected
1212 */
1213 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1214 device_lock(dev);
1215 if (!dev->driver && !dev->p->async_driver) {
1216 get_device(dev);
1217 dev->p->async_driver = drv;
1218 async = true;
1219 }
1220 device_unlock(dev);
1221 if (async)
1222 async_schedule_dev(func: __driver_attach_async_helper, dev);
1223 return 0;
1224 }
1225
1226 __device_driver_lock(dev, parent: dev->parent);
1227 driver_probe_device(drv, dev);
1228 __device_driver_unlock(dev, parent: dev->parent);
1229
1230 return 0;
1231}
1232
1233/**
1234 * driver_attach - try to bind driver to devices.
1235 * @drv: driver.
1236 *
1237 * Walk the list of devices that the bus has on it and try to
1238 * match the driver with each one. If driver_probe_device()
1239 * returns 0 and the @dev->driver is set, we've found a
1240 * compatible pair.
1241 */
1242int driver_attach(const struct device_driver *drv)
1243{
1244 /* The (void *) will be put back to const * in __driver_attach() */
1245 return bus_for_each_dev(bus: drv->bus, NULL, data: (void *)drv, fn: __driver_attach);
1246}
1247EXPORT_SYMBOL_GPL(driver_attach);
1248
1249/*
1250 * __device_release_driver() must be called with @dev lock held.
1251 * When called for a USB interface, @dev->parent lock must be held as well.
1252 */
1253static void __device_release_driver(struct device *dev, struct device *parent)
1254{
1255 struct device_driver *drv;
1256
1257 drv = dev->driver;
1258 if (drv) {
1259 pm_runtime_get_sync(dev);
1260
1261 while (device_links_busy(dev)) {
1262 __device_driver_unlock(dev, parent);
1263
1264 device_links_unbind_consumers(dev);
1265
1266 __device_driver_lock(dev, parent);
1267 /*
1268 * A concurrent invocation of the same function might
1269 * have released the driver successfully while this one
1270 * was waiting, so check for that.
1271 */
1272 if (dev->driver != drv) {
1273 pm_runtime_put(dev);
1274 return;
1275 }
1276 }
1277
1278 driver_sysfs_remove(dev);
1279
1280 bus_notify(dev, value: BUS_NOTIFY_UNBIND_DRIVER);
1281
1282 pm_runtime_put_sync(dev);
1283
1284 device_remove(dev);
1285
1286 if (dev->bus && dev->bus->dma_cleanup)
1287 dev->bus->dma_cleanup(dev);
1288
1289 device_unbind_cleanup(dev);
1290 device_links_driver_cleanup(dev);
1291
1292 klist_remove(n: &dev->p->knode_driver);
1293 device_pm_check_callbacks(dev);
1294
1295 bus_notify(dev, value: BUS_NOTIFY_UNBOUND_DRIVER);
1296 kobject_uevent(kobj: &dev->kobj, action: KOBJ_UNBIND);
1297 }
1298}
1299
1300void device_release_driver_internal(struct device *dev,
1301 const struct device_driver *drv,
1302 struct device *parent)
1303{
1304 __device_driver_lock(dev, parent);
1305
1306 if (!drv || drv == dev->driver)
1307 __device_release_driver(dev, parent);
1308
1309 __device_driver_unlock(dev, parent);
1310}
1311
1312/**
1313 * device_release_driver - manually detach device from driver.
1314 * @dev: device.
1315 *
1316 * Manually detach device from driver.
1317 * When called for a USB interface, @dev->parent lock must be held.
1318 *
1319 * If this function is to be called with @dev->parent lock held, ensure that
1320 * the device's consumers are unbound in advance or that their locks can be
1321 * acquired under the @dev->parent lock.
1322 */
1323void device_release_driver(struct device *dev)
1324{
1325 /*
1326 * If anyone calls device_release_driver() recursively from
1327 * within their ->remove callback for the same device, they
1328 * will deadlock right here.
1329 */
1330 device_release_driver_internal(dev, NULL, NULL);
1331}
1332EXPORT_SYMBOL_GPL(device_release_driver);
1333
1334/**
1335 * device_driver_detach - detach driver from a specific device
1336 * @dev: device to detach driver from
1337 *
1338 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1339 * lock if needed.
1340 */
1341void device_driver_detach(struct device *dev)
1342{
1343 device_release_driver_internal(dev, NULL, parent: dev->parent);
1344}
1345
1346/**
1347 * driver_detach - detach driver from all devices it controls.
1348 * @drv: driver.
1349 */
1350void driver_detach(const struct device_driver *drv)
1351{
1352 struct device_private *dev_prv;
1353 struct device *dev;
1354
1355 if (driver_allows_async_probing(drv))
1356 async_synchronize_full();
1357
1358 for (;;) {
1359 spin_lock(lock: &drv->p->klist_devices.k_lock);
1360 if (list_empty(head: &drv->p->klist_devices.k_list)) {
1361 spin_unlock(lock: &drv->p->klist_devices.k_lock);
1362 break;
1363 }
1364 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1365 struct device_private,
1366 knode_driver.n_node);
1367 dev = dev_prv->device;
1368 get_device(dev);
1369 spin_unlock(lock: &drv->p->klist_devices.k_lock);
1370 device_release_driver_internal(dev, drv, parent: dev->parent);
1371 put_device(dev);
1372 }
1373}
1374

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