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  */
54 static DEFINE_MUTEX(deferred_probe_mutex);
55 static LIST_HEAD(deferred_probe_pending_list);
56 static LIST_HEAD(deferred_probe_active_list);
57 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
58 static bool initcalls_done;
59 
60 /* Save the async probe drivers' name from kernel cmdline */
61 #define ASYNC_DRV_NAMES_MAX_LEN	256
62 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
63 static 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  */
70 static bool defer_all_probes;
71 
__device_set_deferred_probe_reason(const struct device * dev,char * reason)72 static 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  */
deferred_probe_work_func(struct work_struct * work)81 static 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 }
130 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
131 
driver_deferred_probe_add(struct device * dev)132 void 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 
driver_deferred_probe_del(struct device * dev)145 void 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 
156 static 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  */
driver_deferred_probe_trigger(void)175 void 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  */
device_block_probing(void)203 void 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  */
device_unblock_probing(void)216 void 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  */
device_set_deferred_probe_reason(const struct device * dev,struct va_format * vaf)227 void 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  */
deferred_devs_show(struct seq_file * s,void * data)243 static 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 }
257 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
258 
259 #ifdef CONFIG_MODULES
260 int driver_deferred_probe_timeout = 10;
261 #else
262 int driver_deferred_probe_timeout;
263 #endif
264 
265 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
266 
deferred_probe_timeout_setup(char * str)267 static int __init deferred_probe_timeout_setup(char *str)
268 {
269 	int timeout;
270 
271 	if (!kstrtoint(str, 10, &timeout))
272 		driver_deferred_probe_timeout = timeout;
273 	return 1;
274 }
275 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
276 
277 /**
278  * driver_deferred_probe_check_state() - Check deferred probe state
279  * @dev: device to check
280  *
281  * Return:
282  * * -ENODEV if initcalls have completed and modules are disabled.
283  * * -ETIMEDOUT if the deferred probe timeout was set and has expired
284  *   and modules are enabled.
285  * * -EPROBE_DEFER in other cases.
286  *
287  * Drivers or subsystems can opt-in to calling this function instead of directly
288  * returning -EPROBE_DEFER.
289  */
driver_deferred_probe_check_state(struct device * dev)290 int driver_deferred_probe_check_state(struct device *dev)
291 {
292 	if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
293 		dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
294 		return -ENODEV;
295 	}
296 
297 	if (!driver_deferred_probe_timeout && initcalls_done) {
298 		dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
299 		return -ETIMEDOUT;
300 	}
301 
302 	return -EPROBE_DEFER;
303 }
304 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
305 
deferred_probe_timeout_work_func(struct work_struct * work)306 static void deferred_probe_timeout_work_func(struct work_struct *work)
307 {
308 	struct device_private *p;
309 
310 	fw_devlink_drivers_done();
311 
312 	driver_deferred_probe_timeout = 0;
313 	driver_deferred_probe_trigger();
314 	flush_work(&deferred_probe_work);
315 
316 	mutex_lock(&deferred_probe_mutex);
317 	list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
318 		dev_info(p->device, "deferred probe pending\n");
319 	mutex_unlock(&deferred_probe_mutex);
320 }
321 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
322 
deferred_probe_extend_timeout(void)323 void 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  */
deferred_probe_initcall(void)344 static int deferred_probe_initcall(void)
345 {
346 	debugfs_create_file("devices_deferred", 0444, NULL, NULL,
347 			    &deferred_devs_fops);
348 
349 	driver_deferred_probe_enable = true;
350 	driver_deferred_probe_trigger();
351 	/* Sort as many dependencies as possible before exiting initcalls */
352 	flush_work(&deferred_probe_work);
353 	initcalls_done = true;
354 
355 	if (!IS_ENABLED(CONFIG_MODULES))
356 		fw_devlink_drivers_done();
357 
358 	/*
359 	 * Trigger deferred probe again, this time we won't defer anything
360 	 * that is optional
361 	 */
362 	driver_deferred_probe_trigger();
363 	flush_work(&deferred_probe_work);
364 
365 	if (driver_deferred_probe_timeout > 0) {
366 		schedule_delayed_work(&deferred_probe_timeout_work,
367 			driver_deferred_probe_timeout * HZ);
368 	}
369 	return 0;
370 }
371 late_initcall(deferred_probe_initcall);
372 
deferred_probe_exit(void)373 static void __exit deferred_probe_exit(void)
374 {
375 	debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
376 }
377 __exitcall(deferred_probe_exit);
378 
379 /**
380  * device_is_bound() - Check if device is bound to a driver
381  * @dev: device to check
382  *
383  * Returns true if passed device has already finished probing successfully
384  * against a driver.
385  *
386  * This function must be called with the device lock held.
387  */
device_is_bound(struct device * dev)388 bool device_is_bound(struct device *dev)
389 {
390 	return dev->p && klist_node_attached(&dev->p->knode_driver);
391 }
392 
driver_bound(struct device * dev)393 static void driver_bound(struct device *dev)
394 {
395 	if (device_is_bound(dev)) {
396 		pr_warn("%s: device %s already bound\n",
397 			__func__, kobject_name(&dev->kobj));
398 		return;
399 	}
400 
401 	pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
402 		 __func__, dev_name(dev));
403 
404 	klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
405 	device_links_driver_bound(dev);
406 
407 	device_pm_check_callbacks(dev);
408 
409 	/*
410 	 * Make sure the device is no longer in one of the deferred lists and
411 	 * kick off retrying all pending devices
412 	 */
413 	driver_deferred_probe_del(dev);
414 	driver_deferred_probe_trigger();
415 
416 	if (dev->bus)
417 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
418 					     BUS_NOTIFY_BOUND_DRIVER, dev);
419 
420 	kobject_uevent(&dev->kobj, KOBJ_BIND);
421 }
422 
coredump_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)423 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
424 			    const char *buf, size_t count)
425 {
426 	device_lock(dev);
427 	dev->driver->coredump(dev);
428 	device_unlock(dev);
429 
430 	return count;
431 }
432 static DEVICE_ATTR_WO(coredump);
433 
driver_sysfs_add(struct device * dev)434 static int driver_sysfs_add(struct device *dev)
435 {
436 	int ret;
437 
438 	if (dev->bus)
439 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
440 					     BUS_NOTIFY_BIND_DRIVER, dev);
441 
442 	ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
443 				kobject_name(&dev->kobj));
444 	if (ret)
445 		goto fail;
446 
447 	ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
448 				"driver");
449 	if (ret)
450 		goto rm_dev;
451 
452 	if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
453 		return 0;
454 
455 	ret = device_create_file(dev, &dev_attr_coredump);
456 	if (!ret)
457 		return 0;
458 
459 	sysfs_remove_link(&dev->kobj, "driver");
460 
461 rm_dev:
462 	sysfs_remove_link(&dev->driver->p->kobj,
463 			  kobject_name(&dev->kobj));
464 
465 fail:
466 	return ret;
467 }
468 
driver_sysfs_remove(struct device * dev)469 static void driver_sysfs_remove(struct device *dev)
470 {
471 	struct device_driver *drv = dev->driver;
472 
473 	if (drv) {
474 		if (drv->coredump)
475 			device_remove_file(dev, &dev_attr_coredump);
476 		sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
477 		sysfs_remove_link(&dev->kobj, "driver");
478 	}
479 }
480 
481 /**
482  * device_bind_driver - bind a driver to one device.
483  * @dev: device.
484  *
485  * Allow manual attachment of a driver to a device.
486  * Caller must have already set @dev->driver.
487  *
488  * Note that this does not modify the bus reference count.
489  * Please verify that is accounted for before calling this.
490  * (It is ok to call with no other effort from a driver's probe() method.)
491  *
492  * This function must be called with the device lock held.
493  *
494  * Callers should prefer to use device_driver_attach() instead.
495  */
device_bind_driver(struct device * dev)496 int device_bind_driver(struct device *dev)
497 {
498 	int ret;
499 
500 	ret = driver_sysfs_add(dev);
501 	if (!ret) {
502 		device_links_force_bind(dev);
503 		driver_bound(dev);
504 	}
505 	else if (dev->bus)
506 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
507 					     BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
508 	return ret;
509 }
510 EXPORT_SYMBOL_GPL(device_bind_driver);
511 
512 static atomic_t probe_count = ATOMIC_INIT(0);
513 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
514 
state_synced_show(struct device * dev,struct device_attribute * attr,char * buf)515 static ssize_t state_synced_show(struct device *dev,
516 				 struct device_attribute *attr, char *buf)
517 {
518 	bool val;
519 
520 	device_lock(dev);
521 	val = dev->state_synced;
522 	device_unlock(dev);
523 
524 	return sysfs_emit(buf, "%u\n", val);
525 }
526 static DEVICE_ATTR_RO(state_synced);
527 
device_unbind_cleanup(struct device * dev)528 static void device_unbind_cleanup(struct device *dev)
529 {
530 	devres_release_all(dev);
531 	arch_teardown_dma_ops(dev);
532 	kfree(dev->dma_range_map);
533 	dev->dma_range_map = NULL;
534 	dev->driver = NULL;
535 	dev_set_drvdata(dev, NULL);
536 	if (dev->pm_domain && dev->pm_domain->dismiss)
537 		dev->pm_domain->dismiss(dev);
538 	pm_runtime_reinit(dev);
539 	dev_pm_set_driver_flags(dev, 0);
540 }
541 
device_remove(struct device * dev)542 static void device_remove(struct device *dev)
543 {
544 	device_remove_file(dev, &dev_attr_state_synced);
545 	device_remove_groups(dev, dev->driver->dev_groups);
546 
547 	if (dev->bus && dev->bus->remove)
548 		dev->bus->remove(dev);
549 	else if (dev->driver->remove)
550 		dev->driver->remove(dev);
551 }
552 
call_driver_probe(struct device * dev,struct device_driver * drv)553 static int call_driver_probe(struct device *dev, struct device_driver *drv)
554 {
555 	int ret = 0;
556 
557 	if (dev->bus->probe)
558 		ret = dev->bus->probe(dev);
559 	else if (drv->probe)
560 		ret = drv->probe(dev);
561 
562 	switch (ret) {
563 	case 0:
564 		break;
565 	case -EPROBE_DEFER:
566 		/* Driver requested deferred probing */
567 		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
568 		break;
569 	case -ENODEV:
570 	case -ENXIO:
571 		pr_debug("%s: probe of %s rejects match %d\n",
572 			 drv->name, dev_name(dev), ret);
573 		break;
574 	default:
575 		/* driver matched but the probe failed */
576 		pr_warn("%s: probe of %s failed with error %d\n",
577 			drv->name, dev_name(dev), ret);
578 		break;
579 	}
580 
581 	return ret;
582 }
583 
really_probe(struct device * dev,struct device_driver * drv)584 static int really_probe(struct device *dev, struct device_driver *drv)
585 {
586 	bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
587 			   !drv->suppress_bind_attrs;
588 	int ret, link_ret;
589 
590 	if (defer_all_probes) {
591 		/*
592 		 * Value of defer_all_probes can be set only by
593 		 * device_block_probing() which, in turn, will call
594 		 * wait_for_device_probe() right after that to avoid any races.
595 		 */
596 		dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
597 		return -EPROBE_DEFER;
598 	}
599 
600 	link_ret = device_links_check_suppliers(dev);
601 	if (link_ret == -EPROBE_DEFER)
602 		return link_ret;
603 
604 	pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
605 		 drv->bus->name, __func__, drv->name, dev_name(dev));
606 	if (!list_empty(&dev->devres_head)) {
607 		dev_crit(dev, "Resources present before probing\n");
608 		ret = -EBUSY;
609 		goto done;
610 	}
611 
612 re_probe:
613 	dev->driver = drv;
614 
615 	/* If using pinctrl, bind pins now before probing */
616 	ret = pinctrl_bind_pins(dev);
617 	if (ret)
618 		goto pinctrl_bind_failed;
619 
620 	if (dev->bus->dma_configure) {
621 		ret = dev->bus->dma_configure(dev);
622 		if (ret)
623 			goto pinctrl_bind_failed;
624 	}
625 
626 	ret = driver_sysfs_add(dev);
627 	if (ret) {
628 		pr_err("%s: driver_sysfs_add(%s) failed\n",
629 		       __func__, dev_name(dev));
630 		goto sysfs_failed;
631 	}
632 
633 	if (dev->pm_domain && dev->pm_domain->activate) {
634 		ret = dev->pm_domain->activate(dev);
635 		if (ret)
636 			goto probe_failed;
637 	}
638 
639 	ret = call_driver_probe(dev, drv);
640 	if (ret) {
641 		/*
642 		 * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
643 		 * device might actually probe properly once some of its missing
644 		 * suppliers have probed. So, treat this as if the driver
645 		 * returned -EPROBE_DEFER.
646 		 */
647 		if (link_ret == -EAGAIN)
648 			ret = -EPROBE_DEFER;
649 
650 		/*
651 		 * Return probe errors as positive values so that the callers
652 		 * can distinguish them from other errors.
653 		 */
654 		ret = -ret;
655 		goto probe_failed;
656 	}
657 
658 	ret = device_add_groups(dev, drv->dev_groups);
659 	if (ret) {
660 		dev_err(dev, "device_add_groups() failed\n");
661 		goto dev_groups_failed;
662 	}
663 
664 	if (dev_has_sync_state(dev)) {
665 		ret = device_create_file(dev, &dev_attr_state_synced);
666 		if (ret) {
667 			dev_err(dev, "state_synced sysfs add failed\n");
668 			goto dev_sysfs_state_synced_failed;
669 		}
670 	}
671 
672 	if (test_remove) {
673 		test_remove = false;
674 
675 		device_remove(dev);
676 		driver_sysfs_remove(dev);
677 		device_unbind_cleanup(dev);
678 
679 		goto re_probe;
680 	}
681 
682 	pinctrl_init_done(dev);
683 
684 	if (dev->pm_domain && dev->pm_domain->sync)
685 		dev->pm_domain->sync(dev);
686 
687 	driver_bound(dev);
688 	pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
689 		 drv->bus->name, __func__, dev_name(dev), drv->name);
690 	goto done;
691 
692 dev_sysfs_state_synced_failed:
693 dev_groups_failed:
694 	device_remove(dev);
695 probe_failed:
696 	driver_sysfs_remove(dev);
697 sysfs_failed:
698 	if (dev->bus)
699 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
700 					     BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
701 	if (dev->bus && dev->bus->dma_cleanup)
702 		dev->bus->dma_cleanup(dev);
703 pinctrl_bind_failed:
704 	device_links_no_driver(dev);
705 	device_unbind_cleanup(dev);
706 done:
707 	return ret;
708 }
709 
710 /*
711  * For initcall_debug, show the driver probe time.
712  */
really_probe_debug(struct device * dev,struct device_driver * drv)713 static int really_probe_debug(struct device *dev, struct device_driver *drv)
714 {
715 	ktime_t calltime, rettime;
716 	int ret;
717 
718 	calltime = ktime_get();
719 	ret = really_probe(dev, drv);
720 	rettime = ktime_get();
721 	pr_debug("probe of %s returned %d after %lld usecs\n",
722 		 dev_name(dev), ret, ktime_us_delta(rettime, calltime));
723 	return ret;
724 }
725 
726 /**
727  * driver_probe_done
728  * Determine if the probe sequence is finished or not.
729  *
730  * Should somehow figure out how to use a semaphore, not an atomic variable...
731  */
driver_probe_done(void)732 int driver_probe_done(void)
733 {
734 	int local_probe_count = atomic_read(&probe_count);
735 
736 	pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
737 	if (local_probe_count)
738 		return -EBUSY;
739 	return 0;
740 }
741 
742 /**
743  * wait_for_device_probe
744  * Wait for device probing to be completed.
745  */
wait_for_device_probe(void)746 void wait_for_device_probe(void)
747 {
748 	/* wait for the deferred probe workqueue to finish */
749 	flush_work(&deferred_probe_work);
750 
751 	/* wait for the known devices to complete their probing */
752 	wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
753 	async_synchronize_full();
754 }
755 EXPORT_SYMBOL_GPL(wait_for_device_probe);
756 
__driver_probe_device(struct device_driver * drv,struct device * dev)757 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
758 {
759 	int ret = 0;
760 
761 	if (dev->p->dead || !device_is_registered(dev))
762 		return -ENODEV;
763 	if (dev->driver)
764 		return -EBUSY;
765 
766 	dev->can_match = true;
767 	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
768 		 drv->bus->name, __func__, dev_name(dev), drv->name);
769 
770 	pm_runtime_get_suppliers(dev);
771 	if (dev->parent)
772 		pm_runtime_get_sync(dev->parent);
773 
774 	pm_runtime_barrier(dev);
775 	if (initcall_debug)
776 		ret = really_probe_debug(dev, drv);
777 	else
778 		ret = really_probe(dev, drv);
779 	pm_request_idle(dev);
780 
781 	if (dev->parent)
782 		pm_runtime_put(dev->parent);
783 
784 	pm_runtime_put_suppliers(dev);
785 	return ret;
786 }
787 
788 /**
789  * driver_probe_device - attempt to bind device & driver together
790  * @drv: driver to bind a device to
791  * @dev: device to try to bind to the driver
792  *
793  * This function returns -ENODEV if the device is not registered, -EBUSY if it
794  * already has a driver, 0 if the device is bound successfully and a positive
795  * (inverted) error code for failures from the ->probe method.
796  *
797  * This function must be called with @dev lock held.  When called for a
798  * USB interface, @dev->parent lock must be held as well.
799  *
800  * If the device has a parent, runtime-resume the parent before driver probing.
801  */
driver_probe_device(struct device_driver * drv,struct device * dev)802 static int driver_probe_device(struct device_driver *drv, struct device *dev)
803 {
804 	int trigger_count = atomic_read(&deferred_trigger_count);
805 	int ret;
806 
807 	atomic_inc(&probe_count);
808 	ret = __driver_probe_device(drv, dev);
809 	if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
810 		driver_deferred_probe_add(dev);
811 
812 		/*
813 		 * Did a trigger occur while probing? Need to re-trigger if yes
814 		 */
815 		if (trigger_count != atomic_read(&deferred_trigger_count) &&
816 		    !defer_all_probes)
817 			driver_deferred_probe_trigger();
818 	}
819 	atomic_dec(&probe_count);
820 	wake_up_all(&probe_waitqueue);
821 	return ret;
822 }
823 
cmdline_requested_async_probing(const char * drv_name)824 static inline bool cmdline_requested_async_probing(const char *drv_name)
825 {
826 	bool async_drv;
827 
828 	async_drv = parse_option_str(async_probe_drv_names, drv_name);
829 
830 	return (async_probe_default != async_drv);
831 }
832 
833 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
save_async_options(char * buf)834 static int __init save_async_options(char *buf)
835 {
836 	if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
837 		pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
838 
839 	strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
840 	async_probe_default = parse_option_str(async_probe_drv_names, "*");
841 
842 	return 1;
843 }
844 __setup("driver_async_probe=", save_async_options);
845 
driver_allows_async_probing(struct device_driver * drv)846 bool driver_allows_async_probing(struct device_driver *drv)
847 {
848 	switch (drv->probe_type) {
849 	case PROBE_PREFER_ASYNCHRONOUS:
850 		return true;
851 
852 	case PROBE_FORCE_SYNCHRONOUS:
853 		return false;
854 
855 	default:
856 		if (cmdline_requested_async_probing(drv->name))
857 			return true;
858 
859 		if (module_requested_async_probing(drv->owner))
860 			return true;
861 
862 		return false;
863 	}
864 }
865 
866 struct device_attach_data {
867 	struct device *dev;
868 
869 	/*
870 	 * Indicates whether we are considering asynchronous probing or
871 	 * not. Only initial binding after device or driver registration
872 	 * (including deferral processing) may be done asynchronously, the
873 	 * rest is always synchronous, as we expect it is being done by
874 	 * request from userspace.
875 	 */
876 	bool check_async;
877 
878 	/*
879 	 * Indicates if we are binding synchronous or asynchronous drivers.
880 	 * When asynchronous probing is enabled we'll execute 2 passes
881 	 * over drivers: first pass doing synchronous probing and second
882 	 * doing asynchronous probing (if synchronous did not succeed -
883 	 * most likely because there was no driver requiring synchronous
884 	 * probing - and we found asynchronous driver during first pass).
885 	 * The 2 passes are done because we can't shoot asynchronous
886 	 * probe for given device and driver from bus_for_each_drv() since
887 	 * driver pointer is not guaranteed to stay valid once
888 	 * bus_for_each_drv() iterates to the next driver on the bus.
889 	 */
890 	bool want_async;
891 
892 	/*
893 	 * We'll set have_async to 'true' if, while scanning for matching
894 	 * driver, we'll encounter one that requests asynchronous probing.
895 	 */
896 	bool have_async;
897 };
898 
__device_attach_driver(struct device_driver * drv,void * _data)899 static int __device_attach_driver(struct device_driver *drv, void *_data)
900 {
901 	struct device_attach_data *data = _data;
902 	struct device *dev = data->dev;
903 	bool async_allowed;
904 	int ret;
905 
906 	ret = driver_match_device(drv, dev);
907 	if (ret == 0) {
908 		/* no match */
909 		return 0;
910 	} else if (ret == -EPROBE_DEFER) {
911 		dev_dbg(dev, "Device match requests probe deferral\n");
912 		dev->can_match = true;
913 		driver_deferred_probe_add(dev);
914 		/*
915 		 * Device can't match with a driver right now, so don't attempt
916 		 * to match or bind with other drivers on the bus.
917 		 */
918 		return ret;
919 	} else if (ret < 0) {
920 		dev_dbg(dev, "Bus failed to match device: %d\n", ret);
921 		return ret;
922 	} /* ret > 0 means positive match */
923 
924 	async_allowed = driver_allows_async_probing(drv);
925 
926 	if (async_allowed)
927 		data->have_async = true;
928 
929 	if (data->check_async && async_allowed != data->want_async)
930 		return 0;
931 
932 	/*
933 	 * Ignore errors returned by ->probe so that the next driver can try
934 	 * its luck.
935 	 */
936 	ret = driver_probe_device(drv, dev);
937 	if (ret < 0)
938 		return ret;
939 	return ret == 0;
940 }
941 
__device_attach_async_helper(void * _dev,async_cookie_t cookie)942 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
943 {
944 	struct device *dev = _dev;
945 	struct device_attach_data data = {
946 		.dev		= dev,
947 		.check_async	= true,
948 		.want_async	= true,
949 	};
950 
951 	device_lock(dev);
952 
953 	/*
954 	 * Check if device has already been removed or claimed. This may
955 	 * happen with driver loading, device discovery/registration,
956 	 * and deferred probe processing happens all at once with
957 	 * multiple threads.
958 	 */
959 	if (dev->p->dead || dev->driver)
960 		goto out_unlock;
961 
962 	if (dev->parent)
963 		pm_runtime_get_sync(dev->parent);
964 
965 	bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
966 	dev_dbg(dev, "async probe completed\n");
967 
968 	pm_request_idle(dev);
969 
970 	if (dev->parent)
971 		pm_runtime_put(dev->parent);
972 out_unlock:
973 	device_unlock(dev);
974 
975 	put_device(dev);
976 }
977 
__device_attach(struct device * dev,bool allow_async)978 static int __device_attach(struct device *dev, bool allow_async)
979 {
980 	int ret = 0;
981 	bool async = false;
982 
983 	device_lock(dev);
984 	if (dev->p->dead) {
985 		goto out_unlock;
986 	} else if (dev->driver) {
987 		if (device_is_bound(dev)) {
988 			ret = 1;
989 			goto out_unlock;
990 		}
991 		ret = device_bind_driver(dev);
992 		if (ret == 0)
993 			ret = 1;
994 		else {
995 			dev->driver = NULL;
996 			ret = 0;
997 		}
998 	} else {
999 		struct device_attach_data data = {
1000 			.dev = dev,
1001 			.check_async = allow_async,
1002 			.want_async = false,
1003 		};
1004 
1005 		if (dev->parent)
1006 			pm_runtime_get_sync(dev->parent);
1007 
1008 		ret = bus_for_each_drv(dev->bus, NULL, &data,
1009 					__device_attach_driver);
1010 		if (!ret && allow_async && data.have_async) {
1011 			/*
1012 			 * If we could not find appropriate driver
1013 			 * synchronously and we are allowed to do
1014 			 * async probes and there are drivers that
1015 			 * want to probe asynchronously, we'll
1016 			 * try them.
1017 			 */
1018 			dev_dbg(dev, "scheduling asynchronous probe\n");
1019 			get_device(dev);
1020 			async = true;
1021 		} else {
1022 			pm_request_idle(dev);
1023 		}
1024 
1025 		if (dev->parent)
1026 			pm_runtime_put(dev->parent);
1027 	}
1028 out_unlock:
1029 	device_unlock(dev);
1030 	if (async)
1031 		async_schedule_dev(__device_attach_async_helper, dev);
1032 	return ret;
1033 }
1034 
1035 /**
1036  * device_attach - try to attach device to a driver.
1037  * @dev: device.
1038  *
1039  * Walk the list of drivers that the bus has and call
1040  * driver_probe_device() for each pair. If a compatible
1041  * pair is found, break out and return.
1042  *
1043  * Returns 1 if the device was bound to a driver;
1044  * 0 if no matching driver was found;
1045  * -ENODEV if the device is not registered.
1046  *
1047  * When called for a USB interface, @dev->parent lock must be held.
1048  */
device_attach(struct device * dev)1049 int device_attach(struct device *dev)
1050 {
1051 	return __device_attach(dev, false);
1052 }
1053 EXPORT_SYMBOL_GPL(device_attach);
1054 
device_initial_probe(struct device * dev)1055 void device_initial_probe(struct device *dev)
1056 {
1057 	__device_attach(dev, true);
1058 }
1059 
1060 /*
1061  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1062  * @dev: Device we will update driver info for
1063  * @parent: Parent device. Needed if the bus requires parent lock
1064  *
1065  * This function will take the required locks for manipulating dev->drv.
1066  * Normally this will just be the @dev lock, but when called for a USB
1067  * interface, @parent lock will be held as well.
1068  */
__device_driver_lock(struct device * dev,struct device * parent)1069 static void __device_driver_lock(struct device *dev, struct device *parent)
1070 {
1071 	if (parent && dev->bus->need_parent_lock)
1072 		device_lock(parent);
1073 	device_lock(dev);
1074 }
1075 
1076 /*
1077  * __device_driver_unlock - release locks needed to manipulate dev->drv
1078  * @dev: Device we will update driver info for
1079  * @parent: Parent device. Needed if the bus requires parent lock
1080  *
1081  * This function will release the required locks for manipulating dev->drv.
1082  * Normally this will just be the @dev lock, but when called for a
1083  * USB interface, @parent lock will be released as well.
1084  */
__device_driver_unlock(struct device * dev,struct device * parent)1085 static void __device_driver_unlock(struct device *dev, struct device *parent)
1086 {
1087 	device_unlock(dev);
1088 	if (parent && dev->bus->need_parent_lock)
1089 		device_unlock(parent);
1090 }
1091 
1092 /**
1093  * device_driver_attach - attach a specific driver to a specific device
1094  * @drv: Driver to attach
1095  * @dev: Device to attach it to
1096  *
1097  * Manually attach driver to a device. Will acquire both @dev lock and
1098  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1099  */
device_driver_attach(struct device_driver * drv,struct device * dev)1100 int device_driver_attach(struct device_driver *drv, struct device *dev)
1101 {
1102 	int ret;
1103 
1104 	__device_driver_lock(dev, dev->parent);
1105 	ret = __driver_probe_device(drv, dev);
1106 	__device_driver_unlock(dev, dev->parent);
1107 
1108 	/* also return probe errors as normal negative errnos */
1109 	if (ret > 0)
1110 		ret = -ret;
1111 	if (ret == -EPROBE_DEFER)
1112 		return -EAGAIN;
1113 	return ret;
1114 }
1115 EXPORT_SYMBOL_GPL(device_driver_attach);
1116 
__driver_attach_async_helper(void * _dev,async_cookie_t cookie)1117 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1118 {
1119 	struct device *dev = _dev;
1120 	struct device_driver *drv;
1121 	int ret;
1122 
1123 	__device_driver_lock(dev, dev->parent);
1124 	drv = dev->p->async_driver;
1125 	dev->p->async_driver = NULL;
1126 	ret = driver_probe_device(drv, dev);
1127 	__device_driver_unlock(dev, dev->parent);
1128 
1129 	dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1130 
1131 	put_device(dev);
1132 }
1133 
__driver_attach(struct device * dev,void * data)1134 static int __driver_attach(struct device *dev, void *data)
1135 {
1136 	struct device_driver *drv = data;
1137 	bool async = false;
1138 	int ret;
1139 
1140 	/*
1141 	 * Lock device and try to bind to it. We drop the error
1142 	 * here and always return 0, because we need to keep trying
1143 	 * to bind to devices and some drivers will return an error
1144 	 * simply if it didn't support the device.
1145 	 *
1146 	 * driver_probe_device() will spit a warning if there
1147 	 * is an error.
1148 	 */
1149 
1150 	ret = driver_match_device(drv, dev);
1151 	if (ret == 0) {
1152 		/* no match */
1153 		return 0;
1154 	} else if (ret == -EPROBE_DEFER) {
1155 		dev_dbg(dev, "Device match requests probe deferral\n");
1156 		dev->can_match = true;
1157 		driver_deferred_probe_add(dev);
1158 		/*
1159 		 * Driver could not match with device, but may match with
1160 		 * another device on the bus.
1161 		 */
1162 		return 0;
1163 	} else if (ret < 0) {
1164 		dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1165 		/*
1166 		 * Driver could not match with device, but may match with
1167 		 * another device on the bus.
1168 		 */
1169 		return 0;
1170 	} /* ret > 0 means positive match */
1171 
1172 	if (driver_allows_async_probing(drv)) {
1173 		/*
1174 		 * Instead of probing the device synchronously we will
1175 		 * probe it asynchronously to allow for more parallelism.
1176 		 *
1177 		 * We only take the device lock here in order to guarantee
1178 		 * that the dev->driver and async_driver fields are protected
1179 		 */
1180 		dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1181 		device_lock(dev);
1182 		if (!dev->driver && !dev->p->async_driver) {
1183 			get_device(dev);
1184 			dev->p->async_driver = drv;
1185 			async = true;
1186 		}
1187 		device_unlock(dev);
1188 		if (async)
1189 			async_schedule_dev(__driver_attach_async_helper, dev);
1190 		return 0;
1191 	}
1192 
1193 	__device_driver_lock(dev, dev->parent);
1194 	driver_probe_device(drv, dev);
1195 	__device_driver_unlock(dev, dev->parent);
1196 
1197 	return 0;
1198 }
1199 
1200 /**
1201  * driver_attach - try to bind driver to devices.
1202  * @drv: driver.
1203  *
1204  * Walk the list of devices that the bus has on it and try to
1205  * match the driver with each one.  If driver_probe_device()
1206  * returns 0 and the @dev->driver is set, we've found a
1207  * compatible pair.
1208  */
driver_attach(struct device_driver * drv)1209 int driver_attach(struct device_driver *drv)
1210 {
1211 	return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1212 }
1213 EXPORT_SYMBOL_GPL(driver_attach);
1214 
1215 /*
1216  * __device_release_driver() must be called with @dev lock held.
1217  * When called for a USB interface, @dev->parent lock must be held as well.
1218  */
__device_release_driver(struct device * dev,struct device * parent)1219 static void __device_release_driver(struct device *dev, struct device *parent)
1220 {
1221 	struct device_driver *drv;
1222 
1223 	drv = dev->driver;
1224 	if (drv) {
1225 		pm_runtime_get_sync(dev);
1226 
1227 		while (device_links_busy(dev)) {
1228 			__device_driver_unlock(dev, parent);
1229 
1230 			device_links_unbind_consumers(dev);
1231 
1232 			__device_driver_lock(dev, parent);
1233 			/*
1234 			 * A concurrent invocation of the same function might
1235 			 * have released the driver successfully while this one
1236 			 * was waiting, so check for that.
1237 			 */
1238 			if (dev->driver != drv) {
1239 				pm_runtime_put(dev);
1240 				return;
1241 			}
1242 		}
1243 
1244 		driver_sysfs_remove(dev);
1245 
1246 		if (dev->bus)
1247 			blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1248 						     BUS_NOTIFY_UNBIND_DRIVER,
1249 						     dev);
1250 
1251 		pm_runtime_put_sync(dev);
1252 
1253 		device_remove(dev);
1254 
1255 		if (dev->bus && dev->bus->dma_cleanup)
1256 			dev->bus->dma_cleanup(dev);
1257 
1258 		device_links_driver_cleanup(dev);
1259 		device_unbind_cleanup(dev);
1260 
1261 		klist_remove(&dev->p->knode_driver);
1262 		device_pm_check_callbacks(dev);
1263 		if (dev->bus)
1264 			blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1265 						     BUS_NOTIFY_UNBOUND_DRIVER,
1266 						     dev);
1267 
1268 		kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1269 	}
1270 }
1271 
device_release_driver_internal(struct device * dev,struct device_driver * drv,struct device * parent)1272 void device_release_driver_internal(struct device *dev,
1273 				    struct device_driver *drv,
1274 				    struct device *parent)
1275 {
1276 	__device_driver_lock(dev, parent);
1277 
1278 	if (!drv || drv == dev->driver)
1279 		__device_release_driver(dev, parent);
1280 
1281 	__device_driver_unlock(dev, parent);
1282 }
1283 
1284 /**
1285  * device_release_driver - manually detach device from driver.
1286  * @dev: device.
1287  *
1288  * Manually detach device from driver.
1289  * When called for a USB interface, @dev->parent lock must be held.
1290  *
1291  * If this function is to be called with @dev->parent lock held, ensure that
1292  * the device's consumers are unbound in advance or that their locks can be
1293  * acquired under the @dev->parent lock.
1294  */
device_release_driver(struct device * dev)1295 void device_release_driver(struct device *dev)
1296 {
1297 	/*
1298 	 * If anyone calls device_release_driver() recursively from
1299 	 * within their ->remove callback for the same device, they
1300 	 * will deadlock right here.
1301 	 */
1302 	device_release_driver_internal(dev, NULL, NULL);
1303 }
1304 EXPORT_SYMBOL_GPL(device_release_driver);
1305 
1306 /**
1307  * device_driver_detach - detach driver from a specific device
1308  * @dev: device to detach driver from
1309  *
1310  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1311  * lock if needed.
1312  */
device_driver_detach(struct device * dev)1313 void device_driver_detach(struct device *dev)
1314 {
1315 	device_release_driver_internal(dev, NULL, dev->parent);
1316 }
1317 
1318 /**
1319  * driver_detach - detach driver from all devices it controls.
1320  * @drv: driver.
1321  */
driver_detach(struct device_driver * drv)1322 void driver_detach(struct device_driver *drv)
1323 {
1324 	struct device_private *dev_prv;
1325 	struct device *dev;
1326 
1327 	if (driver_allows_async_probing(drv))
1328 		async_synchronize_full();
1329 
1330 	for (;;) {
1331 		spin_lock(&drv->p->klist_devices.k_lock);
1332 		if (list_empty(&drv->p->klist_devices.k_list)) {
1333 			spin_unlock(&drv->p->klist_devices.k_lock);
1334 			break;
1335 		}
1336 		dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1337 				     struct device_private,
1338 				     knode_driver.n_node);
1339 		dev = dev_prv->device;
1340 		get_device(dev);
1341 		spin_unlock(&drv->p->klist_devices.k_lock);
1342 		device_release_driver_internal(dev, drv, dev->parent);
1343 		put_device(dev);
1344 	}
1345 }
1346