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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * drivers/base/dd.c - The core device/driver interactions.
4 *
5 * This file contains the (sometimes tricky) code that controls the
6 * interactions between devices and drivers, which primarily includes
7 * driver binding and unbinding.
8 *
9 * All of this code used to exist in drivers/base/bus.c, but was
10 * relocated to here in the name of compartmentalization (since it wasn't
11 * strictly code just for the 'struct bus_type'.
12 *
13 * Copyright (c) 2002-5 Patrick Mochel
14 * Copyright (c) 2002-3 Open Source Development Labs
15 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
16 * Copyright (c) 2007-2009 Novell Inc.
17 */
18
19#include <linux/debugfs.h>
20#include <linux/device.h>
21#include <linux/delay.h>
22#include <linux/dma-mapping.h>
23#include <linux/init.h>
24#include <linux/module.h>
25#include <linux/kthread.h>
26#include <linux/wait.h>
27#include <linux/async.h>
28#include <linux/pm_runtime.h>
29#include <linux/pinctrl/devinfo.h>
30#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 struct dentry *deferred_devices;
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];
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
72/*
73 * deferred_probe_work_func() - Retry probing devices in the active list.
74 */
75static void deferred_probe_work_func(struct work_struct *work)
76{
77 struct device *dev;
78 struct device_private *private;
79 /*
80 * This block processes every device in the deferred 'active' list.
81 * Each device is removed from the active list and passed to
82 * bus_probe_device() to re-attempt the probe. The loop continues
83 * until every device in the active list is removed and retried.
84 *
85 * Note: Once the device is removed from the list and the mutex is
86 * released, it is possible for the device get freed by another thread
87 * and cause a illegal pointer dereference. This code uses
88 * get/put_device() to ensure the device structure cannot disappear
89 * from under our feet.
90 */
91 mutex_lock(&deferred_probe_mutex);
92 while (!list_empty(&deferred_probe_active_list)) {
93 private = list_first_entry(&deferred_probe_active_list,
94 typeof(*dev->p), deferred_probe);
95 dev = private->device;
96 list_del_init(&private->deferred_probe);
97
98 get_device(dev);
99
100 /*
101 * Drop the mutex while probing each device; the probe path may
102 * manipulate the deferred list
103 */
104 mutex_unlock(&deferred_probe_mutex);
105
106 /*
107 * Force the device to the end of the dpm_list since
108 * the PM code assumes that the order we add things to
109 * the list is a good order for suspend but deferred
110 * probe makes that very unsafe.
111 */
112 device_pm_move_to_tail(dev);
113
114 dev_dbg(dev, "Retrying from deferred list\n");
115 bus_probe_device(dev);
116 mutex_lock(&deferred_probe_mutex);
117
118 put_device(dev);
119 }
120 mutex_unlock(&deferred_probe_mutex);
121}
122static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
123
124void driver_deferred_probe_add(struct device *dev)
125{
126 mutex_lock(&deferred_probe_mutex);
127 if (list_empty(&dev->p->deferred_probe)) {
128 dev_dbg(dev, "Added to deferred list\n");
129 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
130 }
131 mutex_unlock(&deferred_probe_mutex);
132}
133
134void driver_deferred_probe_del(struct device *dev)
135{
136 mutex_lock(&deferred_probe_mutex);
137 if (!list_empty(&dev->p->deferred_probe)) {
138 dev_dbg(dev, "Removed from deferred list\n");
139 list_del_init(&dev->p->deferred_probe);
140 kfree(dev->p->deferred_probe_reason);
141 dev->p->deferred_probe_reason = NULL;
142 }
143 mutex_unlock(&deferred_probe_mutex);
144}
145
146static bool driver_deferred_probe_enable = false;
147/**
148 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
149 *
150 * This functions moves all devices from the pending list to the active
151 * list and schedules the deferred probe workqueue to process them. It
152 * should be called anytime a driver is successfully bound to a device.
153 *
154 * Note, there is a race condition in multi-threaded probe. In the case where
155 * more than one device is probing at the same time, it is possible for one
156 * probe to complete successfully while another is about to defer. If the second
157 * depends on the first, then it will get put on the pending list after the
158 * trigger event has already occurred and will be stuck there.
159 *
160 * The atomic 'deferred_trigger_count' is used to determine if a successful
161 * trigger has occurred in the midst of probing a driver. If the trigger count
162 * changes in the midst of a probe, then deferred processing should be triggered
163 * again.
164 */
165static void driver_deferred_probe_trigger(void)
166{
167 if (!driver_deferred_probe_enable)
168 return;
169
170 /*
171 * A successful probe means that all the devices in the pending list
172 * should be triggered to be reprobed. Move all the deferred devices
173 * into the active list so they can be retried by the workqueue
174 */
175 mutex_lock(&deferred_probe_mutex);
176 atomic_inc(&deferred_trigger_count);
177 list_splice_tail_init(&deferred_probe_pending_list,
178 &deferred_probe_active_list);
179 mutex_unlock(&deferred_probe_mutex);
180
181 /*
182 * Kick the re-probe thread. It may already be scheduled, but it is
183 * safe to kick it again.
184 */
185 schedule_work(&deferred_probe_work);
186}
187
188/**
189 * device_block_probing() - Block/defer device's probes
190 *
191 * It will disable probing of devices and defer their probes instead.
192 */
193void device_block_probing(void)
194{
195 defer_all_probes = true;
196 /* sync with probes to avoid races. */
197 wait_for_device_probe();
198}
199
200/**
201 * device_unblock_probing() - Unblock/enable device's probes
202 *
203 * It will restore normal behavior and trigger re-probing of deferred
204 * devices.
205 */
206void device_unblock_probing(void)
207{
208 defer_all_probes = false;
209 driver_deferred_probe_trigger();
210}
211
212/**
213 * device_set_deferred_probe_reason() - Set defer probe reason message for device
214 * @dev: the pointer to the struct device
215 * @vaf: the pointer to va_format structure with message
216 */
217void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
218{
219 const char *drv = dev_driver_string(dev);
220
221 mutex_lock(&deferred_probe_mutex);
222
223 kfree(dev->p->deferred_probe_reason);
224 dev->p->deferred_probe_reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
225
226 mutex_unlock(&deferred_probe_mutex);
227}
228
229/*
230 * deferred_devs_show() - Show the devices in the deferred probe pending list.
231 */
232static int deferred_devs_show(struct seq_file *s, void *data)
233{
234 struct device_private *curr;
235
236 mutex_lock(&deferred_probe_mutex);
237
238 list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
239 seq_printf(s, "%s\t%s", dev_name(curr->device),
240 curr->device->p->deferred_probe_reason ?: "\n");
241
242 mutex_unlock(&deferred_probe_mutex);
243
244 return 0;
245}
246DEFINE_SHOW_ATTRIBUTE(deferred_devs);
247
248int driver_deferred_probe_timeout;
249EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
250static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue);
251
252static int __init deferred_probe_timeout_setup(char *str)
253{
254 int timeout;
255
256 if (!kstrtoint(str, 10, &timeout))
257 driver_deferred_probe_timeout = timeout;
258 return 1;
259}
260__setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
261
262/**
263 * driver_deferred_probe_check_state() - Check deferred probe state
264 * @dev: device to check
265 *
266 * Return:
267 * -ENODEV if initcalls have completed and modules are disabled.
268 * -ETIMEDOUT if the deferred probe timeout was set and has expired
269 * and modules are enabled.
270 * -EPROBE_DEFER in other cases.
271 *
272 * Drivers or subsystems can opt-in to calling this function instead of directly
273 * returning -EPROBE_DEFER.
274 */
275int driver_deferred_probe_check_state(struct device *dev)
276{
277 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
278 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
279 return -ENODEV;
280 }
281
282 if (!driver_deferred_probe_timeout && initcalls_done) {
283 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
284 return -ETIMEDOUT;
285 }
286
287 return -EPROBE_DEFER;
288}
289
290static void deferred_probe_timeout_work_func(struct work_struct *work)
291{
292 struct device_private *private, *p;
293
294 driver_deferred_probe_timeout = 0;
295 driver_deferred_probe_trigger();
296 flush_work(&deferred_probe_work);
297
298 list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe)
299 dev_info(private->device, "deferred probe pending\n");
300 wake_up_all(&probe_timeout_waitqueue);
301}
302static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
303
304/**
305 * deferred_probe_initcall() - Enable probing of deferred devices
306 *
307 * We don't want to get in the way when the bulk of drivers are getting probed.
308 * Instead, this initcall makes sure that deferred probing is delayed until
309 * late_initcall time.
310 */
311static int deferred_probe_initcall(void)
312{
313 deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
314 NULL, &deferred_devs_fops);
315
316 driver_deferred_probe_enable = true;
317 driver_deferred_probe_trigger();
318 /* Sort as many dependencies as possible before exiting initcalls */
319 flush_work(&deferred_probe_work);
320 initcalls_done = true;
321
322 /*
323 * Trigger deferred probe again, this time we won't defer anything
324 * that is optional
325 */
326 driver_deferred_probe_trigger();
327 flush_work(&deferred_probe_work);
328
329 if (driver_deferred_probe_timeout > 0) {
330 schedule_delayed_work(&deferred_probe_timeout_work,
331 driver_deferred_probe_timeout * HZ);
332 }
333 return 0;
334}
335late_initcall(deferred_probe_initcall);
336
337static void __exit deferred_probe_exit(void)
338{
339 debugfs_remove_recursive(deferred_devices);
340}
341__exitcall(deferred_probe_exit);
342
343/**
344 * device_is_bound() - Check if device is bound to a driver
345 * @dev: device to check
346 *
347 * Returns true if passed device has already finished probing successfully
348 * against a driver.
349 *
350 * This function must be called with the device lock held.
351 */
352bool device_is_bound(struct device *dev)
353{
354 return dev->p && klist_node_attached(&dev->p->knode_driver);
355}
356
357static void driver_bound(struct device *dev)
358{
359 if (device_is_bound(dev)) {
360 pr_warn("%s: device %s already bound\n",
361 __func__, kobject_name(&dev->kobj));
362 return;
363 }
364
365 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
366 __func__, dev_name(dev));
367
368 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
369 device_links_driver_bound(dev);
370
371 device_pm_check_callbacks(dev);
372
373 /*
374 * Make sure the device is no longer in one of the deferred lists and
375 * kick off retrying all pending devices
376 */
377 driver_deferred_probe_del(dev);
378 driver_deferred_probe_trigger();
379
380 if (dev->bus)
381 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
382 BUS_NOTIFY_BOUND_DRIVER, dev);
383
384 kobject_uevent(&dev->kobj, KOBJ_BIND);
385}
386
387static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
388 const char *buf, size_t count)
389{
390 device_lock(dev);
391 dev->driver->coredump(dev);
392 device_unlock(dev);
393
394 return count;
395}
396static DEVICE_ATTR_WO(coredump);
397
398static int driver_sysfs_add(struct device *dev)
399{
400 int ret;
401
402 if (dev->bus)
403 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
404 BUS_NOTIFY_BIND_DRIVER, dev);
405
406 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
407 kobject_name(&dev->kobj));
408 if (ret)
409 goto fail;
410
411 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
412 "driver");
413 if (ret)
414 goto rm_dev;
415
416 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
417 !device_create_file(dev, &dev_attr_coredump))
418 return 0;
419
420 sysfs_remove_link(&dev->kobj, "driver");
421
422rm_dev:
423 sysfs_remove_link(&dev->driver->p->kobj,
424 kobject_name(&dev->kobj));
425
426fail:
427 return ret;
428}
429
430static void driver_sysfs_remove(struct device *dev)
431{
432 struct device_driver *drv = dev->driver;
433
434 if (drv) {
435 if (drv->coredump)
436 device_remove_file(dev, &dev_attr_coredump);
437 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
438 sysfs_remove_link(&dev->kobj, "driver");
439 }
440}
441
442/**
443 * device_bind_driver - bind a driver to one device.
444 * @dev: device.
445 *
446 * Allow manual attachment of a driver to a device.
447 * Caller must have already set @dev->driver.
448 *
449 * Note that this does not modify the bus reference count.
450 * Please verify that is accounted for before calling this.
451 * (It is ok to call with no other effort from a driver's probe() method.)
452 *
453 * This function must be called with the device lock held.
454 */
455int device_bind_driver(struct device *dev)
456{
457 int ret;
458
459 ret = driver_sysfs_add(dev);
460 if (!ret)
461 driver_bound(dev);
462 else if (dev->bus)
463 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
464 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
465 return ret;
466}
467EXPORT_SYMBOL_GPL(device_bind_driver);
468
469static atomic_t probe_count = ATOMIC_INIT(0);
470static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
471
472static void driver_deferred_probe_add_trigger(struct device *dev,
473 int local_trigger_count)
474{
475 driver_deferred_probe_add(dev);
476 /* Did a trigger occur while probing? Need to re-trigger if yes */
477 if (local_trigger_count != atomic_read(&deferred_trigger_count))
478 driver_deferred_probe_trigger();
479}
480
481static ssize_t state_synced_show(struct device *dev,
482 struct device_attribute *attr, char *buf)
483{
484 bool val;
485
486 device_lock(dev);
487 val = dev->state_synced;
488 device_unlock(dev);
489 return sprintf(buf, "%u\n", val);
490}
491static DEVICE_ATTR_RO(state_synced);
492
493static int really_probe(struct device *dev, struct device_driver *drv)
494{
495 int ret = -EPROBE_DEFER;
496 int local_trigger_count = atomic_read(&deferred_trigger_count);
497 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
498 !drv->suppress_bind_attrs;
499
500 if (defer_all_probes) {
501 /*
502 * Value of defer_all_probes can be set only by
503 * device_block_probing() which, in turn, will call
504 * wait_for_device_probe() right after that to avoid any races.
505 */
506 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
507 driver_deferred_probe_add(dev);
508 return ret;
509 }
510
511 ret = device_links_check_suppliers(dev);
512 if (ret == -EPROBE_DEFER)
513 driver_deferred_probe_add_trigger(dev, local_trigger_count);
514 if (ret)
515 return ret;
516
517 atomic_inc(&probe_count);
518 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
519 drv->bus->name, __func__, drv->name, dev_name(dev));
520 if (!list_empty(&dev->devres_head)) {
521 dev_crit(dev, "Resources present before probing\n");
522 ret = -EBUSY;
523 goto done;
524 }
525
526re_probe:
527 dev->driver = drv;
528
529 /* If using pinctrl, bind pins now before probing */
530 ret = pinctrl_bind_pins(dev);
531 if (ret)
532 goto pinctrl_bind_failed;
533
534 if (dev->bus->dma_configure) {
535 ret = dev->bus->dma_configure(dev);
536 if (ret)
537 goto probe_failed;
538 }
539
540 if (driver_sysfs_add(dev)) {
541 pr_err("%s: driver_sysfs_add(%s) failed\n",
542 __func__, dev_name(dev));
543 goto probe_failed;
544 }
545
546 if (dev->pm_domain && dev->pm_domain->activate) {
547 ret = dev->pm_domain->activate(dev);
548 if (ret)
549 goto probe_failed;
550 }
551
552 if (dev->bus->probe) {
553 ret = dev->bus->probe(dev);
554 if (ret)
555 goto probe_failed;
556 } else if (drv->probe) {
557 ret = drv->probe(dev);
558 if (ret)
559 goto probe_failed;
560 }
561
562 if (device_add_groups(dev, drv->dev_groups)) {
563 dev_err(dev, "device_add_groups() failed\n");
564 goto dev_groups_failed;
565 }
566
567 if (dev_has_sync_state(dev) &&
568 device_create_file(dev, &dev_attr_state_synced)) {
569 dev_err(dev, "state_synced sysfs add failed\n");
570 goto dev_sysfs_state_synced_failed;
571 }
572
573 if (test_remove) {
574 test_remove = false;
575
576 device_remove_file(dev, &dev_attr_state_synced);
577 device_remove_groups(dev, drv->dev_groups);
578
579 if (dev->bus->remove)
580 dev->bus->remove(dev);
581 else if (drv->remove)
582 drv->remove(dev);
583
584 devres_release_all(dev);
585 driver_sysfs_remove(dev);
586 dev->driver = NULL;
587 dev_set_drvdata(dev, NULL);
588 if (dev->pm_domain && dev->pm_domain->dismiss)
589 dev->pm_domain->dismiss(dev);
590 pm_runtime_reinit(dev);
591
592 goto re_probe;
593 }
594
595 pinctrl_init_done(dev);
596
597 if (dev->pm_domain && dev->pm_domain->sync)
598 dev->pm_domain->sync(dev);
599
600 driver_bound(dev);
601 ret = 1;
602 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
603 drv->bus->name, __func__, dev_name(dev), drv->name);
604 goto done;
605
606dev_sysfs_state_synced_failed:
607 device_remove_groups(dev, drv->dev_groups);
608dev_groups_failed:
609 if (dev->bus->remove)
610 dev->bus->remove(dev);
611 else if (drv->remove)
612 drv->remove(dev);
613probe_failed:
614 if (dev->bus)
615 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
616 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
617pinctrl_bind_failed:
618 device_links_no_driver(dev);
619 devres_release_all(dev);
620 arch_teardown_dma_ops(dev);
621 driver_sysfs_remove(dev);
622 dev->driver = NULL;
623 dev_set_drvdata(dev, NULL);
624 if (dev->pm_domain && dev->pm_domain->dismiss)
625 dev->pm_domain->dismiss(dev);
626 pm_runtime_reinit(dev);
627 dev_pm_set_driver_flags(dev, 0);
628
629 switch (ret) {
630 case -EPROBE_DEFER:
631 /* Driver requested deferred probing */
632 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
633 driver_deferred_probe_add_trigger(dev, local_trigger_count);
634 break;
635 case -ENODEV:
636 case -ENXIO:
637 pr_debug("%s: probe of %s rejects match %d\n",
638 drv->name, dev_name(dev), ret);
639 break;
640 default:
641 /* driver matched but the probe failed */
642 pr_warn("%s: probe of %s failed with error %d\n",
643 drv->name, dev_name(dev), ret);
644 }
645 /*
646 * Ignore errors returned by ->probe so that the next driver can try
647 * its luck.
648 */
649 ret = 0;
650done:
651 atomic_dec(&probe_count);
652 wake_up_all(&probe_waitqueue);
653 return ret;
654}
655
656/*
657 * For initcall_debug, show the driver probe time.
658 */
659static int really_probe_debug(struct device *dev, struct device_driver *drv)
660{
661 ktime_t calltime, delta, rettime;
662 int ret;
663
664 calltime = ktime_get();
665 ret = really_probe(dev, drv);
666 rettime = ktime_get();
667 delta = ktime_sub(rettime, calltime);
668 pr_debug("probe of %s returned %d after %lld usecs\n",
669 dev_name(dev), ret, (s64) ktime_to_us(delta));
670 return ret;
671}
672
673/**
674 * driver_probe_done
675 * Determine if the probe sequence is finished or not.
676 *
677 * Should somehow figure out how to use a semaphore, not an atomic variable...
678 */
679int driver_probe_done(void)
680{
681 int local_probe_count = atomic_read(&probe_count);
682
683 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
684 if (local_probe_count)
685 return -EBUSY;
686 return 0;
687}
688
689/**
690 * wait_for_device_probe
691 * Wait for device probing to be completed.
692 */
693void wait_for_device_probe(void)
694{
695 /* wait for probe timeout */
696 wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout);
697
698 /* wait for the deferred probe workqueue to finish */
699 flush_work(&deferred_probe_work);
700
701 /* wait for the known devices to complete their probing */
702 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
703 async_synchronize_full();
704}
705EXPORT_SYMBOL_GPL(wait_for_device_probe);
706
707/**
708 * driver_probe_device - attempt to bind device & driver together
709 * @drv: driver to bind a device to
710 * @dev: device to try to bind to the driver
711 *
712 * This function returns -ENODEV if the device is not registered,
713 * 1 if the device is bound successfully and 0 otherwise.
714 *
715 * This function must be called with @dev lock held. When called for a
716 * USB interface, @dev->parent lock must be held as well.
717 *
718 * If the device has a parent, runtime-resume the parent before driver probing.
719 */
720int driver_probe_device(struct device_driver *drv, struct device *dev)
721{
722 int ret = 0;
723
724 if (!device_is_registered(dev))
725 return -ENODEV;
726
727 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
728 drv->bus->name, __func__, dev_name(dev), drv->name);
729
730 pm_runtime_get_suppliers(dev);
731 if (dev->parent)
732 pm_runtime_get_sync(dev->parent);
733
734 pm_runtime_barrier(dev);
735 if (initcall_debug)
736 ret = really_probe_debug(dev, drv);
737 else
738 ret = really_probe(dev, drv);
739 pm_request_idle(dev);
740
741 if (dev->parent)
742 pm_runtime_put(dev->parent);
743
744 pm_runtime_put_suppliers(dev);
745 return ret;
746}
747
748static inline bool cmdline_requested_async_probing(const char *drv_name)
749{
750 return parse_option_str(async_probe_drv_names, drv_name);
751}
752
753/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
754static int __init save_async_options(char *buf)
755{
756 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
757 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
758
759 strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
760 return 0;
761}
762__setup("driver_async_probe=", save_async_options);
763
764bool driver_allows_async_probing(struct device_driver *drv)
765{
766 switch (drv->probe_type) {
767 case PROBE_PREFER_ASYNCHRONOUS:
768 return true;
769
770 case PROBE_FORCE_SYNCHRONOUS:
771 return false;
772
773 default:
774 if (cmdline_requested_async_probing(drv->name))
775 return true;
776
777 if (module_requested_async_probing(drv->owner))
778 return true;
779
780 return false;
781 }
782}
783
784struct device_attach_data {
785 struct device *dev;
786
787 /*
788 * Indicates whether we are are considering asynchronous probing or
789 * not. Only initial binding after device or driver registration
790 * (including deferral processing) may be done asynchronously, the
791 * rest is always synchronous, as we expect it is being done by
792 * request from userspace.
793 */
794 bool check_async;
795
796 /*
797 * Indicates if we are binding synchronous or asynchronous drivers.
798 * When asynchronous probing is enabled we'll execute 2 passes
799 * over drivers: first pass doing synchronous probing and second
800 * doing asynchronous probing (if synchronous did not succeed -
801 * most likely because there was no driver requiring synchronous
802 * probing - and we found asynchronous driver during first pass).
803 * The 2 passes are done because we can't shoot asynchronous
804 * probe for given device and driver from bus_for_each_drv() since
805 * driver pointer is not guaranteed to stay valid once
806 * bus_for_each_drv() iterates to the next driver on the bus.
807 */
808 bool want_async;
809
810 /*
811 * We'll set have_async to 'true' if, while scanning for matching
812 * driver, we'll encounter one that requests asynchronous probing.
813 */
814 bool have_async;
815};
816
817static int __device_attach_driver(struct device_driver *drv, void *_data)
818{
819 struct device_attach_data *data = _data;
820 struct device *dev = data->dev;
821 bool async_allowed;
822 int ret;
823
824 ret = driver_match_device(drv, dev);
825 if (ret == 0) {
826 /* no match */
827 return 0;
828 } else if (ret == -EPROBE_DEFER) {
829 dev_dbg(dev, "Device match requests probe deferral\n");
830 driver_deferred_probe_add(dev);
831 } else if (ret < 0) {
832 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
833 return ret;
834 } /* ret > 0 means positive match */
835
836 async_allowed = driver_allows_async_probing(drv);
837
838 if (async_allowed)
839 data->have_async = true;
840
841 if (data->check_async && async_allowed != data->want_async)
842 return 0;
843
844 return driver_probe_device(drv, dev);
845}
846
847static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
848{
849 struct device *dev = _dev;
850 struct device_attach_data data = {
851 .dev = dev,
852 .check_async = true,
853 .want_async = true,
854 };
855
856 device_lock(dev);
857
858 /*
859 * Check if device has already been removed or claimed. This may
860 * happen with driver loading, device discovery/registration,
861 * and deferred probe processing happens all at once with
862 * multiple threads.
863 */
864 if (dev->p->dead || dev->driver)
865 goto out_unlock;
866
867 if (dev->parent)
868 pm_runtime_get_sync(dev->parent);
869
870 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
871 dev_dbg(dev, "async probe completed\n");
872
873 pm_request_idle(dev);
874
875 if (dev->parent)
876 pm_runtime_put(dev->parent);
877out_unlock:
878 device_unlock(dev);
879
880 put_device(dev);
881}
882
883static int __device_attach(struct device *dev, bool allow_async)
884{
885 int ret = 0;
886
887 device_lock(dev);
888 if (dev->p->dead) {
889 goto out_unlock;
890 } else if (dev->driver) {
891 if (device_is_bound(dev)) {
892 ret = 1;
893 goto out_unlock;
894 }
895 ret = device_bind_driver(dev);
896 if (ret == 0)
897 ret = 1;
898 else {
899 dev->driver = NULL;
900 ret = 0;
901 }
902 } else {
903 struct device_attach_data data = {
904 .dev = dev,
905 .check_async = allow_async,
906 .want_async = false,
907 };
908
909 if (dev->parent)
910 pm_runtime_get_sync(dev->parent);
911
912 ret = bus_for_each_drv(dev->bus, NULL, &data,
913 __device_attach_driver);
914 if (!ret && allow_async && data.have_async) {
915 /*
916 * If we could not find appropriate driver
917 * synchronously and we are allowed to do
918 * async probes and there are drivers that
919 * want to probe asynchronously, we'll
920 * try them.
921 */
922 dev_dbg(dev, "scheduling asynchronous probe\n");
923 get_device(dev);
924 async_schedule_dev(__device_attach_async_helper, dev);
925 } else {
926 pm_request_idle(dev);
927 }
928
929 if (dev->parent)
930 pm_runtime_put(dev->parent);
931 }
932out_unlock:
933 device_unlock(dev);
934 return ret;
935}
936
937/**
938 * device_attach - try to attach device to a driver.
939 * @dev: device.
940 *
941 * Walk the list of drivers that the bus has and call
942 * driver_probe_device() for each pair. If a compatible
943 * pair is found, break out and return.
944 *
945 * Returns 1 if the device was bound to a driver;
946 * 0 if no matching driver was found;
947 * -ENODEV if the device is not registered.
948 *
949 * When called for a USB interface, @dev->parent lock must be held.
950 */
951int device_attach(struct device *dev)
952{
953 return __device_attach(dev, false);
954}
955EXPORT_SYMBOL_GPL(device_attach);
956
957void device_initial_probe(struct device *dev)
958{
959 __device_attach(dev, true);
960}
961
962/*
963 * __device_driver_lock - acquire locks needed to manipulate dev->drv
964 * @dev: Device we will update driver info for
965 * @parent: Parent device. Needed if the bus requires parent lock
966 *
967 * This function will take the required locks for manipulating dev->drv.
968 * Normally this will just be the @dev lock, but when called for a USB
969 * interface, @parent lock will be held as well.
970 */
971static void __device_driver_lock(struct device *dev, struct device *parent)
972{
973 if (parent && dev->bus->need_parent_lock)
974 device_lock(parent);
975 device_lock(dev);
976}
977
978/*
979 * __device_driver_unlock - release locks needed to manipulate dev->drv
980 * @dev: Device we will update driver info for
981 * @parent: Parent device. Needed if the bus requires parent lock
982 *
983 * This function will release the required locks for manipulating dev->drv.
984 * Normally this will just be the the @dev lock, but when called for a
985 * USB interface, @parent lock will be released as well.
986 */
987static void __device_driver_unlock(struct device *dev, struct device *parent)
988{
989 device_unlock(dev);
990 if (parent && dev->bus->need_parent_lock)
991 device_unlock(parent);
992}
993
994/**
995 * device_driver_attach - attach a specific driver to a specific device
996 * @drv: Driver to attach
997 * @dev: Device to attach it to
998 *
999 * Manually attach driver to a device. Will acquire both @dev lock and
1000 * @dev->parent lock if needed.
1001 */
1002int device_driver_attach(struct device_driver *drv, struct device *dev)
1003{
1004 int ret = 0;
1005
1006 __device_driver_lock(dev, dev->parent);
1007
1008 /*
1009 * If device has been removed or someone has already successfully
1010 * bound a driver before us just skip the driver probe call.
1011 */
1012 if (!dev->p->dead && !dev->driver)
1013 ret = driver_probe_device(drv, dev);
1014
1015 __device_driver_unlock(dev, dev->parent);
1016
1017 return ret;
1018}
1019
1020static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1021{
1022 struct device *dev = _dev;
1023 struct device_driver *drv;
1024 int ret = 0;
1025
1026 __device_driver_lock(dev, dev->parent);
1027
1028 drv = dev->p->async_driver;
1029
1030 /*
1031 * If device has been removed or someone has already successfully
1032 * bound a driver before us just skip the driver probe call.
1033 */
1034 if (!dev->p->dead && !dev->driver)
1035 ret = driver_probe_device(drv, dev);
1036
1037 __device_driver_unlock(dev, dev->parent);
1038
1039 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1040
1041 put_device(dev);
1042}
1043
1044static int __driver_attach(struct device *dev, void *data)
1045{
1046 struct device_driver *drv = data;
1047 int ret;
1048
1049 /*
1050 * Lock device and try to bind to it. We drop the error
1051 * here and always return 0, because we need to keep trying
1052 * to bind to devices and some drivers will return an error
1053 * simply if it didn't support the device.
1054 *
1055 * driver_probe_device() will spit a warning if there
1056 * is an error.
1057 */
1058
1059 ret = driver_match_device(drv, dev);
1060 if (ret == 0) {
1061 /* no match */
1062 return 0;
1063 } else if (ret == -EPROBE_DEFER) {
1064 dev_dbg(dev, "Device match requests probe deferral\n");
1065 driver_deferred_probe_add(dev);
1066 } else if (ret < 0) {
1067 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1068 return ret;
1069 } /* ret > 0 means positive match */
1070
1071 if (driver_allows_async_probing(drv)) {
1072 /*
1073 * Instead of probing the device synchronously we will
1074 * probe it asynchronously to allow for more parallelism.
1075 *
1076 * We only take the device lock here in order to guarantee
1077 * that the dev->driver and async_driver fields are protected
1078 */
1079 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1080 device_lock(dev);
1081 if (!dev->driver) {
1082 get_device(dev);
1083 dev->p->async_driver = drv;
1084 async_schedule_dev(__driver_attach_async_helper, dev);
1085 }
1086 device_unlock(dev);
1087 return 0;
1088 }
1089
1090 device_driver_attach(drv, dev);
1091
1092 return 0;
1093}
1094
1095/**
1096 * driver_attach - try to bind driver to devices.
1097 * @drv: driver.
1098 *
1099 * Walk the list of devices that the bus has on it and try to
1100 * match the driver with each one. If driver_probe_device()
1101 * returns 0 and the @dev->driver is set, we've found a
1102 * compatible pair.
1103 */
1104int driver_attach(struct device_driver *drv)
1105{
1106 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1107}
1108EXPORT_SYMBOL_GPL(driver_attach);
1109
1110/*
1111 * __device_release_driver() must be called with @dev lock held.
1112 * When called for a USB interface, @dev->parent lock must be held as well.
1113 */
1114static void __device_release_driver(struct device *dev, struct device *parent)
1115{
1116 struct device_driver *drv;
1117
1118 drv = dev->driver;
1119 if (drv) {
1120 while (device_links_busy(dev)) {
1121 __device_driver_unlock(dev, parent);
1122
1123 device_links_unbind_consumers(dev);
1124
1125 __device_driver_lock(dev, parent);
1126 /*
1127 * A concurrent invocation of the same function might
1128 * have released the driver successfully while this one
1129 * was waiting, so check for that.
1130 */
1131 if (dev->driver != drv)
1132 return;
1133 }
1134
1135 pm_runtime_get_sync(dev);
1136 pm_runtime_clean_up_links(dev);
1137
1138 driver_sysfs_remove(dev);
1139
1140 if (dev->bus)
1141 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1142 BUS_NOTIFY_UNBIND_DRIVER,
1143 dev);
1144
1145 pm_runtime_put_sync(dev);
1146
1147 device_remove_file(dev, &dev_attr_state_synced);
1148 device_remove_groups(dev, drv->dev_groups);
1149
1150 if (dev->bus && dev->bus->remove)
1151 dev->bus->remove(dev);
1152 else if (drv->remove)
1153 drv->remove(dev);
1154
1155 device_links_driver_cleanup(dev);
1156
1157 devres_release_all(dev);
1158 arch_teardown_dma_ops(dev);
1159 dev->driver = NULL;
1160 dev_set_drvdata(dev, NULL);
1161 if (dev->pm_domain && dev->pm_domain->dismiss)
1162 dev->pm_domain->dismiss(dev);
1163 pm_runtime_reinit(dev);
1164 dev_pm_set_driver_flags(dev, 0);
1165
1166 klist_remove(&dev->p->knode_driver);
1167 device_pm_check_callbacks(dev);
1168 if (dev->bus)
1169 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1170 BUS_NOTIFY_UNBOUND_DRIVER,
1171 dev);
1172
1173 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1174 }
1175}
1176
1177void device_release_driver_internal(struct device *dev,
1178 struct device_driver *drv,
1179 struct device *parent)
1180{
1181 __device_driver_lock(dev, parent);
1182
1183 if (!drv || drv == dev->driver)
1184 __device_release_driver(dev, parent);
1185
1186 __device_driver_unlock(dev, parent);
1187}
1188
1189/**
1190 * device_release_driver - manually detach device from driver.
1191 * @dev: device.
1192 *
1193 * Manually detach device from driver.
1194 * When called for a USB interface, @dev->parent lock must be held.
1195 *
1196 * If this function is to be called with @dev->parent lock held, ensure that
1197 * the device's consumers are unbound in advance or that their locks can be
1198 * acquired under the @dev->parent lock.
1199 */
1200void device_release_driver(struct device *dev)
1201{
1202 /*
1203 * If anyone calls device_release_driver() recursively from
1204 * within their ->remove callback for the same device, they
1205 * will deadlock right here.
1206 */
1207 device_release_driver_internal(dev, NULL, NULL);
1208}
1209EXPORT_SYMBOL_GPL(device_release_driver);
1210
1211/**
1212 * device_driver_detach - detach driver from a specific device
1213 * @dev: device to detach driver from
1214 *
1215 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1216 * lock if needed.
1217 */
1218void device_driver_detach(struct device *dev)
1219{
1220 device_release_driver_internal(dev, NULL, dev->parent);
1221}
1222
1223/**
1224 * driver_detach - detach driver from all devices it controls.
1225 * @drv: driver.
1226 */
1227void driver_detach(struct device_driver *drv)
1228{
1229 struct device_private *dev_prv;
1230 struct device *dev;
1231
1232 if (driver_allows_async_probing(drv))
1233 async_synchronize_full();
1234
1235 for (;;) {
1236 spin_lock(&drv->p->klist_devices.k_lock);
1237 if (list_empty(&drv->p->klist_devices.k_list)) {
1238 spin_unlock(&drv->p->klist_devices.k_lock);
1239 break;
1240 }
1241 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1242 struct device_private,
1243 knode_driver.n_node);
1244 dev = dev_prv->device;
1245 get_device(dev);
1246 spin_unlock(&drv->p->klist_devices.k_lock);
1247 device_release_driver_internal(dev, drv, dev->parent);
1248 put_device(dev);
1249 }
1250}
1/*
2 * drivers/base/dd.c - The core device/driver interactions.
3 *
4 * This file contains the (sometimes tricky) code that controls the
5 * interactions between devices and drivers, which primarily includes
6 * driver binding and unbinding.
7 *
8 * All of this code used to exist in drivers/base/bus.c, but was
9 * relocated to here in the name of compartmentalization (since it wasn't
10 * strictly code just for the 'struct bus_type'.
11 *
12 * Copyright (c) 2002-5 Patrick Mochel
13 * Copyright (c) 2002-3 Open Source Development Labs
14 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
15 * Copyright (c) 2007-2009 Novell Inc.
16 *
17 * This file is released under the GPLv2
18 */
19
20#include <linux/device.h>
21#include <linux/delay.h>
22#include <linux/module.h>
23#include <linux/kthread.h>
24#include <linux/wait.h>
25#include <linux/async.h>
26#include <linux/pm_runtime.h>
27#include <linux/pinctrl/devinfo.h>
28
29#include "base.h"
30#include "power/power.h"
31
32/*
33 * Deferred Probe infrastructure.
34 *
35 * Sometimes driver probe order matters, but the kernel doesn't always have
36 * dependency information which means some drivers will get probed before a
37 * resource it depends on is available. For example, an SDHCI driver may
38 * first need a GPIO line from an i2c GPIO controller before it can be
39 * initialized. If a required resource is not available yet, a driver can
40 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
41 *
42 * Deferred probe maintains two lists of devices, a pending list and an active
43 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
44 * pending list. A successful driver probe will trigger moving all devices
45 * from the pending to the active list so that the workqueue will eventually
46 * retry them.
47 *
48 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
49 * of the (struct device*)->p->deferred_probe pointers are manipulated
50 */
51static DEFINE_MUTEX(deferred_probe_mutex);
52static LIST_HEAD(deferred_probe_pending_list);
53static LIST_HEAD(deferred_probe_active_list);
54static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
55
56/*
57 * In some cases, like suspend to RAM or hibernation, It might be reasonable
58 * to prohibit probing of devices as it could be unsafe.
59 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
60 */
61static bool defer_all_probes;
62
63/*
64 * deferred_probe_work_func() - Retry probing devices in the active list.
65 */
66static void deferred_probe_work_func(struct work_struct *work)
67{
68 struct device *dev;
69 struct device_private *private;
70 /*
71 * This block processes every device in the deferred 'active' list.
72 * Each device is removed from the active list and passed to
73 * bus_probe_device() to re-attempt the probe. The loop continues
74 * until every device in the active list is removed and retried.
75 *
76 * Note: Once the device is removed from the list and the mutex is
77 * released, it is possible for the device get freed by another thread
78 * and cause a illegal pointer dereference. This code uses
79 * get/put_device() to ensure the device structure cannot disappear
80 * from under our feet.
81 */
82 mutex_lock(&deferred_probe_mutex);
83 while (!list_empty(&deferred_probe_active_list)) {
84 private = list_first_entry(&deferred_probe_active_list,
85 typeof(*dev->p), deferred_probe);
86 dev = private->device;
87 list_del_init(&private->deferred_probe);
88
89 get_device(dev);
90
91 /*
92 * Drop the mutex while probing each device; the probe path may
93 * manipulate the deferred list
94 */
95 mutex_unlock(&deferred_probe_mutex);
96
97 /*
98 * Force the device to the end of the dpm_list since
99 * the PM code assumes that the order we add things to
100 * the list is a good order for suspend but deferred
101 * probe makes that very unsafe.
102 */
103 device_pm_lock();
104 device_pm_move_last(dev);
105 device_pm_unlock();
106
107 dev_dbg(dev, "Retrying from deferred list\n");
108 bus_probe_device(dev);
109
110 mutex_lock(&deferred_probe_mutex);
111
112 put_device(dev);
113 }
114 mutex_unlock(&deferred_probe_mutex);
115}
116static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
117
118static void driver_deferred_probe_add(struct device *dev)
119{
120 mutex_lock(&deferred_probe_mutex);
121 if (list_empty(&dev->p->deferred_probe)) {
122 dev_dbg(dev, "Added to deferred list\n");
123 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
124 }
125 mutex_unlock(&deferred_probe_mutex);
126}
127
128void driver_deferred_probe_del(struct device *dev)
129{
130 mutex_lock(&deferred_probe_mutex);
131 if (!list_empty(&dev->p->deferred_probe)) {
132 dev_dbg(dev, "Removed from deferred list\n");
133 list_del_init(&dev->p->deferred_probe);
134 }
135 mutex_unlock(&deferred_probe_mutex);
136}
137
138static bool driver_deferred_probe_enable = false;
139/**
140 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
141 *
142 * This functions moves all devices from the pending list to the active
143 * list and schedules the deferred probe workqueue to process them. It
144 * should be called anytime a driver is successfully bound to a device.
145 *
146 * Note, there is a race condition in multi-threaded probe. In the case where
147 * more than one device is probing at the same time, it is possible for one
148 * probe to complete successfully while another is about to defer. If the second
149 * depends on the first, then it will get put on the pending list after the
150 * trigger event has already occurred and will be stuck there.
151 *
152 * The atomic 'deferred_trigger_count' is used to determine if a successful
153 * trigger has occurred in the midst of probing a driver. If the trigger count
154 * changes in the midst of a probe, then deferred processing should be triggered
155 * again.
156 */
157static void driver_deferred_probe_trigger(void)
158{
159 if (!driver_deferred_probe_enable)
160 return;
161
162 /*
163 * A successful probe means that all the devices in the pending list
164 * should be triggered to be reprobed. Move all the deferred devices
165 * into the active list so they can be retried by the workqueue
166 */
167 mutex_lock(&deferred_probe_mutex);
168 atomic_inc(&deferred_trigger_count);
169 list_splice_tail_init(&deferred_probe_pending_list,
170 &deferred_probe_active_list);
171 mutex_unlock(&deferred_probe_mutex);
172
173 /*
174 * Kick the re-probe thread. It may already be scheduled, but it is
175 * safe to kick it again.
176 */
177 schedule_work(&deferred_probe_work);
178}
179
180/**
181 * device_block_probing() - Block/defere device's probes
182 *
183 * It will disable probing of devices and defer their probes instead.
184 */
185void device_block_probing(void)
186{
187 defer_all_probes = true;
188 /* sync with probes to avoid races. */
189 wait_for_device_probe();
190}
191
192/**
193 * device_unblock_probing() - Unblock/enable device's probes
194 *
195 * It will restore normal behavior and trigger re-probing of deferred
196 * devices.
197 */
198void device_unblock_probing(void)
199{
200 defer_all_probes = false;
201 driver_deferred_probe_trigger();
202}
203
204/**
205 * deferred_probe_initcall() - Enable probing of deferred devices
206 *
207 * We don't want to get in the way when the bulk of drivers are getting probed.
208 * Instead, this initcall makes sure that deferred probing is delayed until
209 * late_initcall time.
210 */
211static int deferred_probe_initcall(void)
212{
213 driver_deferred_probe_enable = true;
214 driver_deferred_probe_trigger();
215 /* Sort as many dependencies as possible before exiting initcalls */
216 flush_work(&deferred_probe_work);
217 return 0;
218}
219late_initcall(deferred_probe_initcall);
220
221/**
222 * device_is_bound() - Check if device is bound to a driver
223 * @dev: device to check
224 *
225 * Returns true if passed device has already finished probing successfully
226 * against a driver.
227 *
228 * This function must be called with the device lock held.
229 */
230bool device_is_bound(struct device *dev)
231{
232 return dev->p && klist_node_attached(&dev->p->knode_driver);
233}
234
235static void driver_bound(struct device *dev)
236{
237 if (device_is_bound(dev)) {
238 printk(KERN_WARNING "%s: device %s already bound\n",
239 __func__, kobject_name(&dev->kobj));
240 return;
241 }
242
243 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
244 __func__, dev_name(dev));
245
246 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
247 device_links_driver_bound(dev);
248
249 device_pm_check_callbacks(dev);
250
251 /*
252 * Make sure the device is no longer in one of the deferred lists and
253 * kick off retrying all pending devices
254 */
255 driver_deferred_probe_del(dev);
256 driver_deferred_probe_trigger();
257
258 if (dev->bus)
259 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
260 BUS_NOTIFY_BOUND_DRIVER, dev);
261}
262
263static int driver_sysfs_add(struct device *dev)
264{
265 int ret;
266
267 if (dev->bus)
268 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
269 BUS_NOTIFY_BIND_DRIVER, dev);
270
271 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
272 kobject_name(&dev->kobj));
273 if (ret == 0) {
274 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
275 "driver");
276 if (ret)
277 sysfs_remove_link(&dev->driver->p->kobj,
278 kobject_name(&dev->kobj));
279 }
280 return ret;
281}
282
283static void driver_sysfs_remove(struct device *dev)
284{
285 struct device_driver *drv = dev->driver;
286
287 if (drv) {
288 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
289 sysfs_remove_link(&dev->kobj, "driver");
290 }
291}
292
293/**
294 * device_bind_driver - bind a driver to one device.
295 * @dev: device.
296 *
297 * Allow manual attachment of a driver to a device.
298 * Caller must have already set @dev->driver.
299 *
300 * Note that this does not modify the bus reference count
301 * nor take the bus's rwsem. Please verify those are accounted
302 * for before calling this. (It is ok to call with no other effort
303 * from a driver's probe() method.)
304 *
305 * This function must be called with the device lock held.
306 */
307int device_bind_driver(struct device *dev)
308{
309 int ret;
310
311 ret = driver_sysfs_add(dev);
312 if (!ret)
313 driver_bound(dev);
314 else if (dev->bus)
315 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
316 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
317 return ret;
318}
319EXPORT_SYMBOL_GPL(device_bind_driver);
320
321static atomic_t probe_count = ATOMIC_INIT(0);
322static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
323
324static int really_probe(struct device *dev, struct device_driver *drv)
325{
326 int ret = -EPROBE_DEFER;
327 int local_trigger_count = atomic_read(&deferred_trigger_count);
328 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
329 !drv->suppress_bind_attrs;
330
331 if (defer_all_probes) {
332 /*
333 * Value of defer_all_probes can be set only by
334 * device_defer_all_probes_enable() which, in turn, will call
335 * wait_for_device_probe() right after that to avoid any races.
336 */
337 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
338 driver_deferred_probe_add(dev);
339 return ret;
340 }
341
342 ret = device_links_check_suppliers(dev);
343 if (ret)
344 return ret;
345
346 atomic_inc(&probe_count);
347 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
348 drv->bus->name, __func__, drv->name, dev_name(dev));
349 WARN_ON(!list_empty(&dev->devres_head));
350
351re_probe:
352 dev->driver = drv;
353
354 /* If using pinctrl, bind pins now before probing */
355 ret = pinctrl_bind_pins(dev);
356 if (ret)
357 goto pinctrl_bind_failed;
358
359 if (driver_sysfs_add(dev)) {
360 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
361 __func__, dev_name(dev));
362 goto probe_failed;
363 }
364
365 if (dev->pm_domain && dev->pm_domain->activate) {
366 ret = dev->pm_domain->activate(dev);
367 if (ret)
368 goto probe_failed;
369 }
370
371 /*
372 * Ensure devices are listed in devices_kset in correct order
373 * It's important to move Dev to the end of devices_kset before
374 * calling .probe, because it could be recursive and parent Dev
375 * should always go first
376 */
377 devices_kset_move_last(dev);
378
379 if (dev->bus->probe) {
380 ret = dev->bus->probe(dev);
381 if (ret)
382 goto probe_failed;
383 } else if (drv->probe) {
384 ret = drv->probe(dev);
385 if (ret)
386 goto probe_failed;
387 }
388
389 if (test_remove) {
390 test_remove = false;
391
392 if (dev->bus->remove)
393 dev->bus->remove(dev);
394 else if (drv->remove)
395 drv->remove(dev);
396
397 devres_release_all(dev);
398 driver_sysfs_remove(dev);
399 dev->driver = NULL;
400 dev_set_drvdata(dev, NULL);
401 if (dev->pm_domain && dev->pm_domain->dismiss)
402 dev->pm_domain->dismiss(dev);
403 pm_runtime_reinit(dev);
404
405 goto re_probe;
406 }
407
408 pinctrl_init_done(dev);
409
410 if (dev->pm_domain && dev->pm_domain->sync)
411 dev->pm_domain->sync(dev);
412
413 driver_bound(dev);
414 ret = 1;
415 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
416 drv->bus->name, __func__, dev_name(dev), drv->name);
417 goto done;
418
419probe_failed:
420 if (dev->bus)
421 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
422 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
423pinctrl_bind_failed:
424 device_links_no_driver(dev);
425 devres_release_all(dev);
426 driver_sysfs_remove(dev);
427 dev->driver = NULL;
428 dev_set_drvdata(dev, NULL);
429 if (dev->pm_domain && dev->pm_domain->dismiss)
430 dev->pm_domain->dismiss(dev);
431 pm_runtime_reinit(dev);
432
433 switch (ret) {
434 case -EPROBE_DEFER:
435 /* Driver requested deferred probing */
436 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
437 driver_deferred_probe_add(dev);
438 /* Did a trigger occur while probing? Need to re-trigger if yes */
439 if (local_trigger_count != atomic_read(&deferred_trigger_count))
440 driver_deferred_probe_trigger();
441 break;
442 case -ENODEV:
443 case -ENXIO:
444 pr_debug("%s: probe of %s rejects match %d\n",
445 drv->name, dev_name(dev), ret);
446 break;
447 default:
448 /* driver matched but the probe failed */
449 printk(KERN_WARNING
450 "%s: probe of %s failed with error %d\n",
451 drv->name, dev_name(dev), ret);
452 }
453 /*
454 * Ignore errors returned by ->probe so that the next driver can try
455 * its luck.
456 */
457 ret = 0;
458done:
459 atomic_dec(&probe_count);
460 wake_up(&probe_waitqueue);
461 return ret;
462}
463
464/**
465 * driver_probe_done
466 * Determine if the probe sequence is finished or not.
467 *
468 * Should somehow figure out how to use a semaphore, not an atomic variable...
469 */
470int driver_probe_done(void)
471{
472 pr_debug("%s: probe_count = %d\n", __func__,
473 atomic_read(&probe_count));
474 if (atomic_read(&probe_count))
475 return -EBUSY;
476 return 0;
477}
478
479/**
480 * wait_for_device_probe
481 * Wait for device probing to be completed.
482 */
483void wait_for_device_probe(void)
484{
485 /* wait for the deferred probe workqueue to finish */
486 flush_work(&deferred_probe_work);
487
488 /* wait for the known devices to complete their probing */
489 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
490 async_synchronize_full();
491}
492EXPORT_SYMBOL_GPL(wait_for_device_probe);
493
494/**
495 * driver_probe_device - attempt to bind device & driver together
496 * @drv: driver to bind a device to
497 * @dev: device to try to bind to the driver
498 *
499 * This function returns -ENODEV if the device is not registered,
500 * 1 if the device is bound successfully and 0 otherwise.
501 *
502 * This function must be called with @dev lock held. When called for a
503 * USB interface, @dev->parent lock must be held as well.
504 *
505 * If the device has a parent, runtime-resume the parent before driver probing.
506 */
507int driver_probe_device(struct device_driver *drv, struct device *dev)
508{
509 int ret = 0;
510
511 if (!device_is_registered(dev))
512 return -ENODEV;
513
514 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
515 drv->bus->name, __func__, dev_name(dev), drv->name);
516
517 pm_runtime_get_suppliers(dev);
518 if (dev->parent)
519 pm_runtime_get_sync(dev->parent);
520
521 pm_runtime_barrier(dev);
522 ret = really_probe(dev, drv);
523 pm_request_idle(dev);
524
525 if (dev->parent)
526 pm_runtime_put(dev->parent);
527
528 pm_runtime_put_suppliers(dev);
529 return ret;
530}
531
532bool driver_allows_async_probing(struct device_driver *drv)
533{
534 switch (drv->probe_type) {
535 case PROBE_PREFER_ASYNCHRONOUS:
536 return true;
537
538 case PROBE_FORCE_SYNCHRONOUS:
539 return false;
540
541 default:
542 if (module_requested_async_probing(drv->owner))
543 return true;
544
545 return false;
546 }
547}
548
549struct device_attach_data {
550 struct device *dev;
551
552 /*
553 * Indicates whether we are are considering asynchronous probing or
554 * not. Only initial binding after device or driver registration
555 * (including deferral processing) may be done asynchronously, the
556 * rest is always synchronous, as we expect it is being done by
557 * request from userspace.
558 */
559 bool check_async;
560
561 /*
562 * Indicates if we are binding synchronous or asynchronous drivers.
563 * When asynchronous probing is enabled we'll execute 2 passes
564 * over drivers: first pass doing synchronous probing and second
565 * doing asynchronous probing (if synchronous did not succeed -
566 * most likely because there was no driver requiring synchronous
567 * probing - and we found asynchronous driver during first pass).
568 * The 2 passes are done because we can't shoot asynchronous
569 * probe for given device and driver from bus_for_each_drv() since
570 * driver pointer is not guaranteed to stay valid once
571 * bus_for_each_drv() iterates to the next driver on the bus.
572 */
573 bool want_async;
574
575 /*
576 * We'll set have_async to 'true' if, while scanning for matching
577 * driver, we'll encounter one that requests asynchronous probing.
578 */
579 bool have_async;
580};
581
582static int __device_attach_driver(struct device_driver *drv, void *_data)
583{
584 struct device_attach_data *data = _data;
585 struct device *dev = data->dev;
586 bool async_allowed;
587 int ret;
588
589 /*
590 * Check if device has already been claimed. This may
591 * happen with driver loading, device discovery/registration,
592 * and deferred probe processing happens all at once with
593 * multiple threads.
594 */
595 if (dev->driver)
596 return -EBUSY;
597
598 ret = driver_match_device(drv, dev);
599 if (ret == 0) {
600 /* no match */
601 return 0;
602 } else if (ret == -EPROBE_DEFER) {
603 dev_dbg(dev, "Device match requests probe deferral\n");
604 driver_deferred_probe_add(dev);
605 } else if (ret < 0) {
606 dev_dbg(dev, "Bus failed to match device: %d", ret);
607 return ret;
608 } /* ret > 0 means positive match */
609
610 async_allowed = driver_allows_async_probing(drv);
611
612 if (async_allowed)
613 data->have_async = true;
614
615 if (data->check_async && async_allowed != data->want_async)
616 return 0;
617
618 return driver_probe_device(drv, dev);
619}
620
621static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
622{
623 struct device *dev = _dev;
624 struct device_attach_data data = {
625 .dev = dev,
626 .check_async = true,
627 .want_async = true,
628 };
629
630 device_lock(dev);
631
632 if (dev->parent)
633 pm_runtime_get_sync(dev->parent);
634
635 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
636 dev_dbg(dev, "async probe completed\n");
637
638 pm_request_idle(dev);
639
640 if (dev->parent)
641 pm_runtime_put(dev->parent);
642
643 device_unlock(dev);
644
645 put_device(dev);
646}
647
648static int __device_attach(struct device *dev, bool allow_async)
649{
650 int ret = 0;
651
652 device_lock(dev);
653 if (dev->driver) {
654 if (device_is_bound(dev)) {
655 ret = 1;
656 goto out_unlock;
657 }
658 ret = device_bind_driver(dev);
659 if (ret == 0)
660 ret = 1;
661 else {
662 dev->driver = NULL;
663 ret = 0;
664 }
665 } else {
666 struct device_attach_data data = {
667 .dev = dev,
668 .check_async = allow_async,
669 .want_async = false,
670 };
671
672 if (dev->parent)
673 pm_runtime_get_sync(dev->parent);
674
675 ret = bus_for_each_drv(dev->bus, NULL, &data,
676 __device_attach_driver);
677 if (!ret && allow_async && data.have_async) {
678 /*
679 * If we could not find appropriate driver
680 * synchronously and we are allowed to do
681 * async probes and there are drivers that
682 * want to probe asynchronously, we'll
683 * try them.
684 */
685 dev_dbg(dev, "scheduling asynchronous probe\n");
686 get_device(dev);
687 async_schedule(__device_attach_async_helper, dev);
688 } else {
689 pm_request_idle(dev);
690 }
691
692 if (dev->parent)
693 pm_runtime_put(dev->parent);
694 }
695out_unlock:
696 device_unlock(dev);
697 return ret;
698}
699
700/**
701 * device_attach - try to attach device to a driver.
702 * @dev: device.
703 *
704 * Walk the list of drivers that the bus has and call
705 * driver_probe_device() for each pair. If a compatible
706 * pair is found, break out and return.
707 *
708 * Returns 1 if the device was bound to a driver;
709 * 0 if no matching driver was found;
710 * -ENODEV if the device is not registered.
711 *
712 * When called for a USB interface, @dev->parent lock must be held.
713 */
714int device_attach(struct device *dev)
715{
716 return __device_attach(dev, false);
717}
718EXPORT_SYMBOL_GPL(device_attach);
719
720void device_initial_probe(struct device *dev)
721{
722 __device_attach(dev, true);
723}
724
725static int __driver_attach(struct device *dev, void *data)
726{
727 struct device_driver *drv = data;
728 int ret;
729
730 /*
731 * Lock device and try to bind to it. We drop the error
732 * here and always return 0, because we need to keep trying
733 * to bind to devices and some drivers will return an error
734 * simply if it didn't support the device.
735 *
736 * driver_probe_device() will spit a warning if there
737 * is an error.
738 */
739
740 ret = driver_match_device(drv, dev);
741 if (ret == 0) {
742 /* no match */
743 return 0;
744 } else if (ret == -EPROBE_DEFER) {
745 dev_dbg(dev, "Device match requests probe deferral\n");
746 driver_deferred_probe_add(dev);
747 } else if (ret < 0) {
748 dev_dbg(dev, "Bus failed to match device: %d", ret);
749 return ret;
750 } /* ret > 0 means positive match */
751
752 if (dev->parent) /* Needed for USB */
753 device_lock(dev->parent);
754 device_lock(dev);
755 if (!dev->driver)
756 driver_probe_device(drv, dev);
757 device_unlock(dev);
758 if (dev->parent)
759 device_unlock(dev->parent);
760
761 return 0;
762}
763
764/**
765 * driver_attach - try to bind driver to devices.
766 * @drv: driver.
767 *
768 * Walk the list of devices that the bus has on it and try to
769 * match the driver with each one. If driver_probe_device()
770 * returns 0 and the @dev->driver is set, we've found a
771 * compatible pair.
772 */
773int driver_attach(struct device_driver *drv)
774{
775 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
776}
777EXPORT_SYMBOL_GPL(driver_attach);
778
779/*
780 * __device_release_driver() must be called with @dev lock held.
781 * When called for a USB interface, @dev->parent lock must be held as well.
782 */
783static void __device_release_driver(struct device *dev, struct device *parent)
784{
785 struct device_driver *drv;
786
787 drv = dev->driver;
788 if (drv) {
789 if (driver_allows_async_probing(drv))
790 async_synchronize_full();
791
792 while (device_links_busy(dev)) {
793 device_unlock(dev);
794 if (parent)
795 device_unlock(parent);
796
797 device_links_unbind_consumers(dev);
798 if (parent)
799 device_lock(parent);
800
801 device_lock(dev);
802 /*
803 * A concurrent invocation of the same function might
804 * have released the driver successfully while this one
805 * was waiting, so check for that.
806 */
807 if (dev->driver != drv)
808 return;
809 }
810
811 pm_runtime_get_sync(dev);
812 pm_runtime_clean_up_links(dev);
813
814 driver_sysfs_remove(dev);
815
816 if (dev->bus)
817 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
818 BUS_NOTIFY_UNBIND_DRIVER,
819 dev);
820
821 pm_runtime_put_sync(dev);
822
823 if (dev->bus && dev->bus->remove)
824 dev->bus->remove(dev);
825 else if (drv->remove)
826 drv->remove(dev);
827
828 device_links_driver_cleanup(dev);
829 devres_release_all(dev);
830 dev->driver = NULL;
831 dev_set_drvdata(dev, NULL);
832 if (dev->pm_domain && dev->pm_domain->dismiss)
833 dev->pm_domain->dismiss(dev);
834 pm_runtime_reinit(dev);
835
836 klist_remove(&dev->p->knode_driver);
837 device_pm_check_callbacks(dev);
838 if (dev->bus)
839 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
840 BUS_NOTIFY_UNBOUND_DRIVER,
841 dev);
842 }
843}
844
845void device_release_driver_internal(struct device *dev,
846 struct device_driver *drv,
847 struct device *parent)
848{
849 if (parent)
850 device_lock(parent);
851
852 device_lock(dev);
853 if (!drv || drv == dev->driver)
854 __device_release_driver(dev, parent);
855
856 device_unlock(dev);
857 if (parent)
858 device_unlock(parent);
859}
860
861/**
862 * device_release_driver - manually detach device from driver.
863 * @dev: device.
864 *
865 * Manually detach device from driver.
866 * When called for a USB interface, @dev->parent lock must be held.
867 *
868 * If this function is to be called with @dev->parent lock held, ensure that
869 * the device's consumers are unbound in advance or that their locks can be
870 * acquired under the @dev->parent lock.
871 */
872void device_release_driver(struct device *dev)
873{
874 /*
875 * If anyone calls device_release_driver() recursively from
876 * within their ->remove callback for the same device, they
877 * will deadlock right here.
878 */
879 device_release_driver_internal(dev, NULL, NULL);
880}
881EXPORT_SYMBOL_GPL(device_release_driver);
882
883/**
884 * driver_detach - detach driver from all devices it controls.
885 * @drv: driver.
886 */
887void driver_detach(struct device_driver *drv)
888{
889 struct device_private *dev_prv;
890 struct device *dev;
891
892 for (;;) {
893 spin_lock(&drv->p->klist_devices.k_lock);
894 if (list_empty(&drv->p->klist_devices.k_list)) {
895 spin_unlock(&drv->p->klist_devices.k_lock);
896 break;
897 }
898 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
899 struct device_private,
900 knode_driver.n_node);
901 dev = dev_prv->device;
902 get_device(dev);
903 spin_unlock(&drv->p->klist_devices.k_lock);
904 device_release_driver_internal(dev, drv, dev->parent);
905 put_device(dev);
906 }
907}