Loading...
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
260static int driver_deferred_probe_timeout = 10;
261#else
262static int driver_deferred_probe_timeout;
263#endif
264
265static int __init deferred_probe_timeout_setup(char *str)
266{
267 int timeout;
268
269 if (!kstrtoint(str, 10, &timeout))
270 driver_deferred_probe_timeout = timeout;
271 return 1;
272}
273__setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
274
275/**
276 * driver_deferred_probe_check_state() - Check deferred probe state
277 * @dev: device to check
278 *
279 * Return:
280 * * -ENODEV if initcalls have completed and modules are disabled.
281 * * -ETIMEDOUT if the deferred probe timeout was set and has expired
282 * and modules are enabled.
283 * * -EPROBE_DEFER in other cases.
284 *
285 * Drivers or subsystems can opt-in to calling this function instead of directly
286 * returning -EPROBE_DEFER.
287 */
288int driver_deferred_probe_check_state(struct device *dev)
289{
290 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
291 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
292 return -ENODEV;
293 }
294
295 if (!driver_deferred_probe_timeout && initcalls_done) {
296 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
297 return -ETIMEDOUT;
298 }
299
300 return -EPROBE_DEFER;
301}
302EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
303
304static void deferred_probe_timeout_work_func(struct work_struct *work)
305{
306 struct device_private *p;
307
308 fw_devlink_drivers_done();
309
310 driver_deferred_probe_timeout = 0;
311 driver_deferred_probe_trigger();
312 flush_work(&deferred_probe_work);
313
314 mutex_lock(&deferred_probe_mutex);
315 list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
316 dev_info(p->device, "deferred probe pending: %s", p->deferred_probe_reason ?: "(reason unknown)\n");
317 mutex_unlock(&deferred_probe_mutex);
318
319 fw_devlink_probing_done();
320}
321static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
322
323void deferred_probe_extend_timeout(void)
324{
325 /*
326 * If the work hasn't been queued yet or if the work expired, don't
327 * start a new one.
328 */
329 if (cancel_delayed_work(&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
370 if (!IS_ENABLED(CONFIG_MODULES))
371 fw_devlink_probing_done();
372
373 return 0;
374}
375late_initcall(deferred_probe_initcall);
376
377static void __exit deferred_probe_exit(void)
378{
379 debugfs_lookup_and_remove("devices_deferred", NULL);
380}
381__exitcall(deferred_probe_exit);
382
383/**
384 * device_is_bound() - Check if device is bound to a driver
385 * @dev: device to check
386 *
387 * Returns true if passed device has already finished probing successfully
388 * against a driver.
389 *
390 * This function must be called with the device lock held.
391 */
392bool device_is_bound(struct device *dev)
393{
394 return dev->p && klist_node_attached(&dev->p->knode_driver);
395}
396
397static void driver_bound(struct device *dev)
398{
399 if (device_is_bound(dev)) {
400 pr_warn("%s: device %s already bound\n",
401 __func__, kobject_name(&dev->kobj));
402 return;
403 }
404
405 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
406 __func__, dev_name(dev));
407
408 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
409 device_links_driver_bound(dev);
410
411 device_pm_check_callbacks(dev);
412
413 /*
414 * Make sure the device is no longer in one of the deferred lists and
415 * kick off retrying all pending devices
416 */
417 driver_deferred_probe_del(dev);
418 driver_deferred_probe_trigger();
419
420 bus_notify(dev, BUS_NOTIFY_BOUND_DRIVER);
421 kobject_uevent(&dev->kobj, KOBJ_BIND);
422}
423
424static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
425 const char *buf, size_t count)
426{
427 device_lock(dev);
428 dev->driver->coredump(dev);
429 device_unlock(dev);
430
431 return count;
432}
433static DEVICE_ATTR_WO(coredump);
434
435static int driver_sysfs_add(struct device *dev)
436{
437 int ret;
438
439 bus_notify(dev, BUS_NOTIFY_BIND_DRIVER);
440
441 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
442 kobject_name(&dev->kobj));
443 if (ret)
444 goto fail;
445
446 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
447 "driver");
448 if (ret)
449 goto rm_dev;
450
451 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
452 return 0;
453
454 ret = device_create_file(dev, &dev_attr_coredump);
455 if (!ret)
456 return 0;
457
458 sysfs_remove_link(&dev->kobj, "driver");
459
460rm_dev:
461 sysfs_remove_link(&dev->driver->p->kobj,
462 kobject_name(&dev->kobj));
463
464fail:
465 return ret;
466}
467
468static void driver_sysfs_remove(struct device *dev)
469{
470 struct device_driver *drv = dev->driver;
471
472 if (drv) {
473 if (drv->coredump)
474 device_remove_file(dev, &dev_attr_coredump);
475 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
476 sysfs_remove_link(&dev->kobj, "driver");
477 }
478}
479
480/**
481 * device_bind_driver - bind a driver to one device.
482 * @dev: device.
483 *
484 * Allow manual attachment of a driver to a device.
485 * Caller must have already set @dev->driver.
486 *
487 * Note that this does not modify the bus reference count.
488 * Please verify that is accounted for before calling this.
489 * (It is ok to call with no other effort from a driver's probe() method.)
490 *
491 * This function must be called with the device lock held.
492 *
493 * Callers should prefer to use device_driver_attach() instead.
494 */
495int device_bind_driver(struct device *dev)
496{
497 int ret;
498
499 ret = driver_sysfs_add(dev);
500 if (!ret) {
501 device_links_force_bind(dev);
502 driver_bound(dev);
503 }
504 else
505 bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
506 return ret;
507}
508EXPORT_SYMBOL_GPL(device_bind_driver);
509
510static atomic_t probe_count = ATOMIC_INIT(0);
511static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
512
513static ssize_t state_synced_store(struct device *dev,
514 struct device_attribute *attr,
515 const char *buf, size_t count)
516{
517 int ret = 0;
518
519 if (strcmp("1", buf))
520 return -EINVAL;
521
522 device_lock(dev);
523 if (!dev->state_synced) {
524 dev->state_synced = true;
525 dev_sync_state(dev);
526 } else {
527 ret = -EINVAL;
528 }
529 device_unlock(dev);
530
531 return ret ? ret : count;
532}
533
534static ssize_t state_synced_show(struct device *dev,
535 struct device_attribute *attr, char *buf)
536{
537 bool val;
538
539 device_lock(dev);
540 val = dev->state_synced;
541 device_unlock(dev);
542
543 return sysfs_emit(buf, "%u\n", val);
544}
545static DEVICE_ATTR_RW(state_synced);
546
547static void device_unbind_cleanup(struct device *dev)
548{
549 devres_release_all(dev);
550 arch_teardown_dma_ops(dev);
551 kfree(dev->dma_range_map);
552 dev->dma_range_map = NULL;
553 dev->driver = NULL;
554 dev_set_drvdata(dev, NULL);
555 if (dev->pm_domain && dev->pm_domain->dismiss)
556 dev->pm_domain->dismiss(dev);
557 pm_runtime_reinit(dev);
558 dev_pm_set_driver_flags(dev, 0);
559}
560
561static void device_remove(struct device *dev)
562{
563 device_remove_file(dev, &dev_attr_state_synced);
564 device_remove_groups(dev, dev->driver->dev_groups);
565
566 if (dev->bus && dev->bus->remove)
567 dev->bus->remove(dev);
568 else if (dev->driver->remove)
569 dev->driver->remove(dev);
570}
571
572static int call_driver_probe(struct device *dev, struct device_driver *drv)
573{
574 int ret = 0;
575
576 if (dev->bus->probe)
577 ret = dev->bus->probe(dev);
578 else if (drv->probe)
579 ret = drv->probe(dev);
580
581 switch (ret) {
582 case 0:
583 break;
584 case -EPROBE_DEFER:
585 /* Driver requested deferred probing */
586 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
587 break;
588 case -ENODEV:
589 case -ENXIO:
590 pr_debug("%s: probe of %s rejects match %d\n",
591 drv->name, dev_name(dev), ret);
592 break;
593 default:
594 /* driver matched but the probe failed */
595 pr_warn("%s: probe of %s failed with error %d\n",
596 drv->name, dev_name(dev), ret);
597 break;
598 }
599
600 return ret;
601}
602
603static int really_probe(struct device *dev, struct device_driver *drv)
604{
605 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
606 !drv->suppress_bind_attrs;
607 int ret, link_ret;
608
609 if (defer_all_probes) {
610 /*
611 * Value of defer_all_probes can be set only by
612 * device_block_probing() which, in turn, will call
613 * wait_for_device_probe() right after that to avoid any races.
614 */
615 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
616 return -EPROBE_DEFER;
617 }
618
619 link_ret = device_links_check_suppliers(dev);
620 if (link_ret == -EPROBE_DEFER)
621 return link_ret;
622
623 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
624 drv->bus->name, __func__, drv->name, dev_name(dev));
625 if (!list_empty(&dev->devres_head)) {
626 dev_crit(dev, "Resources present before probing\n");
627 ret = -EBUSY;
628 goto done;
629 }
630
631re_probe:
632 dev->driver = drv;
633
634 /* If using pinctrl, bind pins now before probing */
635 ret = pinctrl_bind_pins(dev);
636 if (ret)
637 goto pinctrl_bind_failed;
638
639 if (dev->bus->dma_configure) {
640 ret = dev->bus->dma_configure(dev);
641 if (ret)
642 goto pinctrl_bind_failed;
643 }
644
645 ret = driver_sysfs_add(dev);
646 if (ret) {
647 pr_err("%s: driver_sysfs_add(%s) failed\n",
648 __func__, dev_name(dev));
649 goto sysfs_failed;
650 }
651
652 if (dev->pm_domain && dev->pm_domain->activate) {
653 ret = dev->pm_domain->activate(dev);
654 if (ret)
655 goto probe_failed;
656 }
657
658 ret = call_driver_probe(dev, drv);
659 if (ret) {
660 /*
661 * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
662 * device might actually probe properly once some of its missing
663 * suppliers have probed. So, treat this as if the driver
664 * returned -EPROBE_DEFER.
665 */
666 if (link_ret == -EAGAIN)
667 ret = -EPROBE_DEFER;
668
669 /*
670 * Return probe errors as positive values so that the callers
671 * can distinguish them from other errors.
672 */
673 ret = -ret;
674 goto probe_failed;
675 }
676
677 ret = device_add_groups(dev, drv->dev_groups);
678 if (ret) {
679 dev_err(dev, "device_add_groups() failed\n");
680 goto dev_groups_failed;
681 }
682
683 if (dev_has_sync_state(dev)) {
684 ret = device_create_file(dev, &dev_attr_state_synced);
685 if (ret) {
686 dev_err(dev, "state_synced sysfs add failed\n");
687 goto dev_sysfs_state_synced_failed;
688 }
689 }
690
691 if (test_remove) {
692 test_remove = false;
693
694 device_remove(dev);
695 driver_sysfs_remove(dev);
696 if (dev->bus && dev->bus->dma_cleanup)
697 dev->bus->dma_cleanup(dev);
698 device_unbind_cleanup(dev);
699
700 goto re_probe;
701 }
702
703 pinctrl_init_done(dev);
704
705 if (dev->pm_domain && dev->pm_domain->sync)
706 dev->pm_domain->sync(dev);
707
708 driver_bound(dev);
709 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
710 drv->bus->name, __func__, dev_name(dev), drv->name);
711 goto done;
712
713dev_sysfs_state_synced_failed:
714dev_groups_failed:
715 device_remove(dev);
716probe_failed:
717 driver_sysfs_remove(dev);
718sysfs_failed:
719 bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
720 if (dev->bus && dev->bus->dma_cleanup)
721 dev->bus->dma_cleanup(dev);
722pinctrl_bind_failed:
723 device_links_no_driver(dev);
724 device_unbind_cleanup(dev);
725done:
726 return ret;
727}
728
729/*
730 * For initcall_debug, show the driver probe time.
731 */
732static int really_probe_debug(struct device *dev, struct device_driver *drv)
733{
734 ktime_t calltime, rettime;
735 int ret;
736
737 calltime = ktime_get();
738 ret = really_probe(dev, drv);
739 rettime = ktime_get();
740 /*
741 * Don't change this to pr_debug() because that requires
742 * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the
743 * kernel commandline to print this all the time at the debug level.
744 */
745 printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
746 dev_name(dev), ret, ktime_us_delta(rettime, calltime));
747 return ret;
748}
749
750/**
751 * driver_probe_done
752 * Determine if the probe sequence is finished or not.
753 *
754 * Should somehow figure out how to use a semaphore, not an atomic variable...
755 */
756bool __init driver_probe_done(void)
757{
758 int local_probe_count = atomic_read(&probe_count);
759
760 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
761 return !local_probe_count;
762}
763
764/**
765 * wait_for_device_probe
766 * Wait for device probing to be completed.
767 */
768void wait_for_device_probe(void)
769{
770 /* wait for the deferred probe workqueue to finish */
771 flush_work(&deferred_probe_work);
772
773 /* wait for the known devices to complete their probing */
774 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
775 async_synchronize_full();
776}
777EXPORT_SYMBOL_GPL(wait_for_device_probe);
778
779static int __driver_probe_device(struct device_driver *drv, struct device *dev)
780{
781 int ret = 0;
782
783 if (dev->p->dead || !device_is_registered(dev))
784 return -ENODEV;
785 if (dev->driver)
786 return -EBUSY;
787
788 dev->can_match = true;
789 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
790 drv->bus->name, __func__, dev_name(dev), drv->name);
791
792 pm_runtime_get_suppliers(dev);
793 if (dev->parent)
794 pm_runtime_get_sync(dev->parent);
795
796 pm_runtime_barrier(dev);
797 if (initcall_debug)
798 ret = really_probe_debug(dev, drv);
799 else
800 ret = really_probe(dev, drv);
801 pm_request_idle(dev);
802
803 if (dev->parent)
804 pm_runtime_put(dev->parent);
805
806 pm_runtime_put_suppliers(dev);
807 return ret;
808}
809
810/**
811 * driver_probe_device - attempt to bind device & driver together
812 * @drv: driver to bind a device to
813 * @dev: device to try to bind to the driver
814 *
815 * This function returns -ENODEV if the device is not registered, -EBUSY if it
816 * already has a driver, 0 if the device is bound successfully and a positive
817 * (inverted) error code for failures from the ->probe method.
818 *
819 * This function must be called with @dev lock held. When called for a
820 * USB interface, @dev->parent lock must be held as well.
821 *
822 * If the device has a parent, runtime-resume the parent before driver probing.
823 */
824static int driver_probe_device(struct device_driver *drv, struct device *dev)
825{
826 int trigger_count = atomic_read(&deferred_trigger_count);
827 int ret;
828
829 atomic_inc(&probe_count);
830 ret = __driver_probe_device(drv, dev);
831 if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
832 driver_deferred_probe_add(dev);
833
834 /*
835 * Did a trigger occur while probing? Need to re-trigger if yes
836 */
837 if (trigger_count != atomic_read(&deferred_trigger_count) &&
838 !defer_all_probes)
839 driver_deferred_probe_trigger();
840 }
841 atomic_dec(&probe_count);
842 wake_up_all(&probe_waitqueue);
843 return ret;
844}
845
846static inline bool cmdline_requested_async_probing(const char *drv_name)
847{
848 bool async_drv;
849
850 async_drv = parse_option_str(async_probe_drv_names, drv_name);
851
852 return (async_probe_default != async_drv);
853}
854
855/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
856static int __init save_async_options(char *buf)
857{
858 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
859 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
860
861 strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
862 async_probe_default = parse_option_str(async_probe_drv_names, "*");
863
864 return 1;
865}
866__setup("driver_async_probe=", save_async_options);
867
868static bool driver_allows_async_probing(struct device_driver *drv)
869{
870 switch (drv->probe_type) {
871 case PROBE_PREFER_ASYNCHRONOUS:
872 return true;
873
874 case PROBE_FORCE_SYNCHRONOUS:
875 return false;
876
877 default:
878 if (cmdline_requested_async_probing(drv->name))
879 return true;
880
881 if (module_requested_async_probing(drv->owner))
882 return true;
883
884 return false;
885 }
886}
887
888struct device_attach_data {
889 struct device *dev;
890
891 /*
892 * Indicates whether we are considering asynchronous probing or
893 * not. Only initial binding after device or driver registration
894 * (including deferral processing) may be done asynchronously, the
895 * rest is always synchronous, as we expect it is being done by
896 * request from userspace.
897 */
898 bool check_async;
899
900 /*
901 * Indicates if we are binding synchronous or asynchronous drivers.
902 * When asynchronous probing is enabled we'll execute 2 passes
903 * over drivers: first pass doing synchronous probing and second
904 * doing asynchronous probing (if synchronous did not succeed -
905 * most likely because there was no driver requiring synchronous
906 * probing - and we found asynchronous driver during first pass).
907 * The 2 passes are done because we can't shoot asynchronous
908 * probe for given device and driver from bus_for_each_drv() since
909 * driver pointer is not guaranteed to stay valid once
910 * bus_for_each_drv() iterates to the next driver on the bus.
911 */
912 bool want_async;
913
914 /*
915 * We'll set have_async to 'true' if, while scanning for matching
916 * driver, we'll encounter one that requests asynchronous probing.
917 */
918 bool have_async;
919};
920
921static int __device_attach_driver(struct device_driver *drv, void *_data)
922{
923 struct device_attach_data *data = _data;
924 struct device *dev = data->dev;
925 bool async_allowed;
926 int ret;
927
928 ret = driver_match_device(drv, dev);
929 if (ret == 0) {
930 /* no match */
931 return 0;
932 } else if (ret == -EPROBE_DEFER) {
933 dev_dbg(dev, "Device match requests probe deferral\n");
934 dev->can_match = true;
935 driver_deferred_probe_add(dev);
936 /*
937 * Device can't match with a driver right now, so don't attempt
938 * to match or bind with other drivers on the bus.
939 */
940 return ret;
941 } else if (ret < 0) {
942 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
943 return ret;
944 } /* ret > 0 means positive match */
945
946 async_allowed = driver_allows_async_probing(drv);
947
948 if (async_allowed)
949 data->have_async = true;
950
951 if (data->check_async && async_allowed != data->want_async)
952 return 0;
953
954 /*
955 * Ignore errors returned by ->probe so that the next driver can try
956 * its luck.
957 */
958 ret = driver_probe_device(drv, dev);
959 if (ret < 0)
960 return ret;
961 return ret == 0;
962}
963
964static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
965{
966 struct device *dev = _dev;
967 struct device_attach_data data = {
968 .dev = dev,
969 .check_async = true,
970 .want_async = true,
971 };
972
973 device_lock(dev);
974
975 /*
976 * Check if device has already been removed or claimed. This may
977 * happen with driver loading, device discovery/registration,
978 * and deferred probe processing happens all at once with
979 * multiple threads.
980 */
981 if (dev->p->dead || dev->driver)
982 goto out_unlock;
983
984 if (dev->parent)
985 pm_runtime_get_sync(dev->parent);
986
987 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
988 dev_dbg(dev, "async probe completed\n");
989
990 pm_request_idle(dev);
991
992 if (dev->parent)
993 pm_runtime_put(dev->parent);
994out_unlock:
995 device_unlock(dev);
996
997 put_device(dev);
998}
999
1000static int __device_attach(struct device *dev, bool allow_async)
1001{
1002 int ret = 0;
1003 bool async = false;
1004
1005 device_lock(dev);
1006 if (dev->p->dead) {
1007 goto out_unlock;
1008 } else if (dev->driver) {
1009 if (device_is_bound(dev)) {
1010 ret = 1;
1011 goto out_unlock;
1012 }
1013 ret = device_bind_driver(dev);
1014 if (ret == 0)
1015 ret = 1;
1016 else {
1017 dev->driver = NULL;
1018 ret = 0;
1019 }
1020 } else {
1021 struct device_attach_data data = {
1022 .dev = dev,
1023 .check_async = allow_async,
1024 .want_async = false,
1025 };
1026
1027 if (dev->parent)
1028 pm_runtime_get_sync(dev->parent);
1029
1030 ret = bus_for_each_drv(dev->bus, NULL, &data,
1031 __device_attach_driver);
1032 if (!ret && allow_async && data.have_async) {
1033 /*
1034 * If we could not find appropriate driver
1035 * synchronously and we are allowed to do
1036 * async probes and there are drivers that
1037 * want to probe asynchronously, we'll
1038 * try them.
1039 */
1040 dev_dbg(dev, "scheduling asynchronous probe\n");
1041 get_device(dev);
1042 async = true;
1043 } else {
1044 pm_request_idle(dev);
1045 }
1046
1047 if (dev->parent)
1048 pm_runtime_put(dev->parent);
1049 }
1050out_unlock:
1051 device_unlock(dev);
1052 if (async)
1053 async_schedule_dev(__device_attach_async_helper, dev);
1054 return ret;
1055}
1056
1057/**
1058 * device_attach - try to attach device to a driver.
1059 * @dev: device.
1060 *
1061 * Walk the list of drivers that the bus has and call
1062 * driver_probe_device() for each pair. If a compatible
1063 * pair is found, break out and return.
1064 *
1065 * Returns 1 if the device was bound to a driver;
1066 * 0 if no matching driver was found;
1067 * -ENODEV if the device is not registered.
1068 *
1069 * When called for a USB interface, @dev->parent lock must be held.
1070 */
1071int device_attach(struct device *dev)
1072{
1073 return __device_attach(dev, false);
1074}
1075EXPORT_SYMBOL_GPL(device_attach);
1076
1077void device_initial_probe(struct device *dev)
1078{
1079 __device_attach(dev, true);
1080}
1081
1082/*
1083 * __device_driver_lock - acquire locks needed to manipulate dev->drv
1084 * @dev: Device we will update driver info for
1085 * @parent: Parent device. Needed if the bus requires parent lock
1086 *
1087 * This function will take the required locks for manipulating dev->drv.
1088 * Normally this will just be the @dev lock, but when called for a USB
1089 * interface, @parent lock will be held as well.
1090 */
1091static void __device_driver_lock(struct device *dev, struct device *parent)
1092{
1093 if (parent && dev->bus->need_parent_lock)
1094 device_lock(parent);
1095 device_lock(dev);
1096}
1097
1098/*
1099 * __device_driver_unlock - release locks needed to manipulate dev->drv
1100 * @dev: Device we will update driver info for
1101 * @parent: Parent device. Needed if the bus requires parent lock
1102 *
1103 * This function will release the required locks for manipulating dev->drv.
1104 * Normally this will just be the @dev lock, but when called for a
1105 * USB interface, @parent lock will be released as well.
1106 */
1107static void __device_driver_unlock(struct device *dev, struct device *parent)
1108{
1109 device_unlock(dev);
1110 if (parent && dev->bus->need_parent_lock)
1111 device_unlock(parent);
1112}
1113
1114/**
1115 * device_driver_attach - attach a specific driver to a specific device
1116 * @drv: Driver to attach
1117 * @dev: Device to attach it to
1118 *
1119 * Manually attach driver to a device. Will acquire both @dev lock and
1120 * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1121 */
1122int device_driver_attach(struct device_driver *drv, struct device *dev)
1123{
1124 int ret;
1125
1126 __device_driver_lock(dev, dev->parent);
1127 ret = __driver_probe_device(drv, dev);
1128 __device_driver_unlock(dev, dev->parent);
1129
1130 /* also return probe errors as normal negative errnos */
1131 if (ret > 0)
1132 ret = -ret;
1133 if (ret == -EPROBE_DEFER)
1134 return -EAGAIN;
1135 return ret;
1136}
1137EXPORT_SYMBOL_GPL(device_driver_attach);
1138
1139static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1140{
1141 struct device *dev = _dev;
1142 struct device_driver *drv;
1143 int ret;
1144
1145 __device_driver_lock(dev, dev->parent);
1146 drv = dev->p->async_driver;
1147 dev->p->async_driver = NULL;
1148 ret = driver_probe_device(drv, dev);
1149 __device_driver_unlock(dev, dev->parent);
1150
1151 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1152
1153 put_device(dev);
1154}
1155
1156static int __driver_attach(struct device *dev, void *data)
1157{
1158 struct device_driver *drv = data;
1159 bool async = false;
1160 int ret;
1161
1162 /*
1163 * Lock device and try to bind to it. We drop the error
1164 * here and always return 0, because we need to keep trying
1165 * to bind to devices and some drivers will return an error
1166 * simply if it didn't support the device.
1167 *
1168 * driver_probe_device() will spit a warning if there
1169 * is an error.
1170 */
1171
1172 ret = driver_match_device(drv, dev);
1173 if (ret == 0) {
1174 /* no match */
1175 return 0;
1176 } else if (ret == -EPROBE_DEFER) {
1177 dev_dbg(dev, "Device match requests probe deferral\n");
1178 dev->can_match = true;
1179 driver_deferred_probe_add(dev);
1180 /*
1181 * Driver could not match with device, but may match with
1182 * another device on the bus.
1183 */
1184 return 0;
1185 } else if (ret < 0) {
1186 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1187 /*
1188 * Driver could not match with device, but may match with
1189 * another device on the bus.
1190 */
1191 return 0;
1192 } /* ret > 0 means positive match */
1193
1194 if (driver_allows_async_probing(drv)) {
1195 /*
1196 * Instead of probing the device synchronously we will
1197 * probe it asynchronously to allow for more parallelism.
1198 *
1199 * We only take the device lock here in order to guarantee
1200 * that the dev->driver and async_driver fields are protected
1201 */
1202 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1203 device_lock(dev);
1204 if (!dev->driver && !dev->p->async_driver) {
1205 get_device(dev);
1206 dev->p->async_driver = drv;
1207 async = true;
1208 }
1209 device_unlock(dev);
1210 if (async)
1211 async_schedule_dev(__driver_attach_async_helper, dev);
1212 return 0;
1213 }
1214
1215 __device_driver_lock(dev, dev->parent);
1216 driver_probe_device(drv, dev);
1217 __device_driver_unlock(dev, dev->parent);
1218
1219 return 0;
1220}
1221
1222/**
1223 * driver_attach - try to bind driver to devices.
1224 * @drv: driver.
1225 *
1226 * Walk the list of devices that the bus has on it and try to
1227 * match the driver with each one. If driver_probe_device()
1228 * returns 0 and the @dev->driver is set, we've found a
1229 * compatible pair.
1230 */
1231int driver_attach(struct device_driver *drv)
1232{
1233 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1234}
1235EXPORT_SYMBOL_GPL(driver_attach);
1236
1237/*
1238 * __device_release_driver() must be called with @dev lock held.
1239 * When called for a USB interface, @dev->parent lock must be held as well.
1240 */
1241static void __device_release_driver(struct device *dev, struct device *parent)
1242{
1243 struct device_driver *drv;
1244
1245 drv = dev->driver;
1246 if (drv) {
1247 pm_runtime_get_sync(dev);
1248
1249 while (device_links_busy(dev)) {
1250 __device_driver_unlock(dev, parent);
1251
1252 device_links_unbind_consumers(dev);
1253
1254 __device_driver_lock(dev, parent);
1255 /*
1256 * A concurrent invocation of the same function might
1257 * have released the driver successfully while this one
1258 * was waiting, so check for that.
1259 */
1260 if (dev->driver != drv) {
1261 pm_runtime_put(dev);
1262 return;
1263 }
1264 }
1265
1266 driver_sysfs_remove(dev);
1267
1268 bus_notify(dev, BUS_NOTIFY_UNBIND_DRIVER);
1269
1270 pm_runtime_put_sync(dev);
1271
1272 device_remove(dev);
1273
1274 if (dev->bus && dev->bus->dma_cleanup)
1275 dev->bus->dma_cleanup(dev);
1276
1277 device_unbind_cleanup(dev);
1278 device_links_driver_cleanup(dev);
1279
1280 klist_remove(&dev->p->knode_driver);
1281 device_pm_check_callbacks(dev);
1282
1283 bus_notify(dev, BUS_NOTIFY_UNBOUND_DRIVER);
1284 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1285 }
1286}
1287
1288void device_release_driver_internal(struct device *dev,
1289 struct device_driver *drv,
1290 struct device *parent)
1291{
1292 __device_driver_lock(dev, parent);
1293
1294 if (!drv || drv == dev->driver)
1295 __device_release_driver(dev, parent);
1296
1297 __device_driver_unlock(dev, parent);
1298}
1299
1300/**
1301 * device_release_driver - manually detach device from driver.
1302 * @dev: device.
1303 *
1304 * Manually detach device from driver.
1305 * When called for a USB interface, @dev->parent lock must be held.
1306 *
1307 * If this function is to be called with @dev->parent lock held, ensure that
1308 * the device's consumers are unbound in advance or that their locks can be
1309 * acquired under the @dev->parent lock.
1310 */
1311void device_release_driver(struct device *dev)
1312{
1313 /*
1314 * If anyone calls device_release_driver() recursively from
1315 * within their ->remove callback for the same device, they
1316 * will deadlock right here.
1317 */
1318 device_release_driver_internal(dev, NULL, NULL);
1319}
1320EXPORT_SYMBOL_GPL(device_release_driver);
1321
1322/**
1323 * device_driver_detach - detach driver from a specific device
1324 * @dev: device to detach driver from
1325 *
1326 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1327 * lock if needed.
1328 */
1329void device_driver_detach(struct device *dev)
1330{
1331 device_release_driver_internal(dev, NULL, dev->parent);
1332}
1333
1334/**
1335 * driver_detach - detach driver from all devices it controls.
1336 * @drv: driver.
1337 */
1338void driver_detach(struct device_driver *drv)
1339{
1340 struct device_private *dev_prv;
1341 struct device *dev;
1342
1343 if (driver_allows_async_probing(drv))
1344 async_synchronize_full();
1345
1346 for (;;) {
1347 spin_lock(&drv->p->klist_devices.k_lock);
1348 if (list_empty(&drv->p->klist_devices.k_list)) {
1349 spin_unlock(&drv->p->klist_devices.k_lock);
1350 break;
1351 }
1352 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1353 struct device_private,
1354 knode_driver.n_node);
1355 dev = dev_prv->device;
1356 get_device(dev);
1357 spin_unlock(&drv->p->klist_devices.k_lock);
1358 device_release_driver_internal(dev, drv, dev->parent);
1359 put_device(dev);
1360 }
1361}
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}