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