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