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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/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 | */ | |
53 | static DEFINE_MUTEX(deferred_probe_mutex); | |
54 | static LIST_HEAD(deferred_probe_pending_list); | |
55 | static LIST_HEAD(deferred_probe_active_list); | |
56 | static atomic_t deferred_trigger_count = ATOMIC_INIT(0); | |
57 | static bool initcalls_done; | |
58 | ||
59 | /* | |
60 | * In some cases, like suspend to RAM or hibernation, It might be reasonable | |
61 | * to prohibit probing of devices as it could be unsafe. | |
62 | * Once defer_all_probes is true all drivers probes will be forcibly deferred. | |
63 | */ | |
64 | static bool defer_all_probes; | |
65 | ||
66 | /* | |
67 | * For initcall_debug, show the deferred probes executed in late_initcall | |
68 | * processing. | |
69 | */ | |
70 | static void deferred_probe_debug(struct device *dev) | |
71 | { | |
72 | ktime_t calltime, delta, rettime; | |
73 | unsigned long long duration; | |
74 | ||
75 | printk(KERN_DEBUG "deferred probe %s @ %i\n", dev_name(dev), | |
76 | task_pid_nr(current)); | |
77 | calltime = ktime_get(); | |
78 | bus_probe_device(dev); | |
79 | rettime = ktime_get(); | |
80 | delta = ktime_sub(rettime, calltime); | |
81 | duration = (unsigned long long) ktime_to_ns(delta) >> 10; | |
82 | printk(KERN_DEBUG "deferred probe %s returned after %lld usecs\n", | |
83 | dev_name(dev), duration); | |
84 | } | |
85 | ||
86 | /* | |
87 | * deferred_probe_work_func() - Retry probing devices in the active list. | |
88 | */ | |
89 | static void deferred_probe_work_func(struct work_struct *work) | |
90 | { | |
91 | struct device *dev; | |
92 | struct device_private *private; | |
93 | /* | |
94 | * This block processes every device in the deferred 'active' list. | |
95 | * Each device is removed from the active list and passed to | |
96 | * bus_probe_device() to re-attempt the probe. The loop continues | |
97 | * until every device in the active list is removed and retried. | |
98 | * | |
99 | * Note: Once the device is removed from the list and the mutex is | |
100 | * released, it is possible for the device get freed by another thread | |
101 | * and cause a illegal pointer dereference. This code uses | |
102 | * get/put_device() to ensure the device structure cannot disappear | |
103 | * from under our feet. | |
104 | */ | |
105 | mutex_lock(&deferred_probe_mutex); | |
106 | while (!list_empty(&deferred_probe_active_list)) { | |
107 | private = list_first_entry(&deferred_probe_active_list, | |
108 | typeof(*dev->p), deferred_probe); | |
109 | dev = private->device; | |
110 | list_del_init(&private->deferred_probe); | |
111 | ||
112 | get_device(dev); | |
113 | ||
114 | /* | |
115 | * Drop the mutex while probing each device; the probe path may | |
116 | * manipulate the deferred list | |
117 | */ | |
118 | mutex_unlock(&deferred_probe_mutex); | |
119 | ||
120 | /* | |
121 | * Force the device to the end of the dpm_list since | |
122 | * the PM code assumes that the order we add things to | |
123 | * the list is a good order for suspend but deferred | |
124 | * probe makes that very unsafe. | |
125 | */ | |
126 | device_pm_lock(); | |
127 | device_pm_move_last(dev); | |
128 | device_pm_unlock(); | |
129 | ||
130 | dev_dbg(dev, "Retrying from deferred list\n"); | |
131 | if (initcall_debug && !initcalls_done) | |
132 | deferred_probe_debug(dev); | |
133 | else | |
134 | bus_probe_device(dev); | |
135 | ||
136 | mutex_lock(&deferred_probe_mutex); | |
137 | ||
138 | put_device(dev); | |
139 | } | |
140 | mutex_unlock(&deferred_probe_mutex); | |
141 | } | |
142 | static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func); | |
143 | ||
144 | static void driver_deferred_probe_add(struct device *dev) | |
145 | { | |
146 | mutex_lock(&deferred_probe_mutex); | |
147 | if (list_empty(&dev->p->deferred_probe)) { | |
148 | dev_dbg(dev, "Added to deferred list\n"); | |
149 | list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list); | |
150 | } | |
151 | mutex_unlock(&deferred_probe_mutex); | |
152 | } | |
153 | ||
154 | void driver_deferred_probe_del(struct device *dev) | |
155 | { | |
156 | mutex_lock(&deferred_probe_mutex); | |
157 | if (!list_empty(&dev->p->deferred_probe)) { | |
158 | dev_dbg(dev, "Removed from deferred list\n"); | |
159 | list_del_init(&dev->p->deferred_probe); | |
160 | } | |
161 | mutex_unlock(&deferred_probe_mutex); | |
162 | } | |
163 | ||
164 | static bool driver_deferred_probe_enable = false; | |
165 | /** | |
166 | * driver_deferred_probe_trigger() - Kick off re-probing deferred devices | |
167 | * | |
168 | * This functions moves all devices from the pending list to the active | |
169 | * list and schedules the deferred probe workqueue to process them. It | |
170 | * should be called anytime a driver is successfully bound to a device. | |
171 | * | |
172 | * Note, there is a race condition in multi-threaded probe. In the case where | |
173 | * more than one device is probing at the same time, it is possible for one | |
174 | * probe to complete successfully while another is about to defer. If the second | |
175 | * depends on the first, then it will get put on the pending list after the | |
176 | * trigger event has already occurred and will be stuck there. | |
177 | * | |
178 | * The atomic 'deferred_trigger_count' is used to determine if a successful | |
179 | * trigger has occurred in the midst of probing a driver. If the trigger count | |
180 | * changes in the midst of a probe, then deferred processing should be triggered | |
181 | * again. | |
182 | */ | |
183 | static void driver_deferred_probe_trigger(void) | |
184 | { | |
185 | if (!driver_deferred_probe_enable) | |
186 | return; | |
187 | ||
188 | /* | |
189 | * A successful probe means that all the devices in the pending list | |
190 | * should be triggered to be reprobed. Move all the deferred devices | |
191 | * into the active list so they can be retried by the workqueue | |
192 | */ | |
193 | mutex_lock(&deferred_probe_mutex); | |
194 | atomic_inc(&deferred_trigger_count); | |
195 | list_splice_tail_init(&deferred_probe_pending_list, | |
196 | &deferred_probe_active_list); | |
197 | mutex_unlock(&deferred_probe_mutex); | |
198 | ||
199 | /* | |
200 | * Kick the re-probe thread. It may already be scheduled, but it is | |
201 | * safe to kick it again. | |
202 | */ | |
203 | schedule_work(&deferred_probe_work); | |
204 | } | |
205 | ||
206 | /** | |
207 | * device_block_probing() - Block/defere device's probes | |
208 | * | |
209 | * It will disable probing of devices and defer their probes instead. | |
210 | */ | |
211 | void device_block_probing(void) | |
212 | { | |
213 | defer_all_probes = true; | |
214 | /* sync with probes to avoid races. */ | |
215 | wait_for_device_probe(); | |
216 | } | |
217 | ||
218 | /** | |
219 | * device_unblock_probing() - Unblock/enable device's probes | |
220 | * | |
221 | * It will restore normal behavior and trigger re-probing of deferred | |
222 | * devices. | |
223 | */ | |
224 | void device_unblock_probing(void) | |
225 | { | |
226 | defer_all_probes = false; | |
227 | driver_deferred_probe_trigger(); | |
228 | } | |
229 | ||
230 | /** | |
231 | * deferred_probe_initcall() - Enable probing of deferred devices | |
232 | * | |
233 | * We don't want to get in the way when the bulk of drivers are getting probed. | |
234 | * Instead, this initcall makes sure that deferred probing is delayed until | |
235 | * late_initcall time. | |
236 | */ | |
237 | static int deferred_probe_initcall(void) | |
238 | { | |
239 | driver_deferred_probe_enable = true; | |
240 | driver_deferred_probe_trigger(); | |
241 | /* Sort as many dependencies as possible before exiting initcalls */ | |
242 | flush_work(&deferred_probe_work); | |
243 | initcalls_done = true; | |
244 | return 0; | |
245 | } | |
246 | late_initcall(deferred_probe_initcall); | |
247 | ||
248 | /** | |
249 | * device_is_bound() - Check if device is bound to a driver | |
250 | * @dev: device to check | |
251 | * | |
252 | * Returns true if passed device has already finished probing successfully | |
253 | * against a driver. | |
254 | * | |
255 | * This function must be called with the device lock held. | |
256 | */ | |
257 | bool device_is_bound(struct device *dev) | |
258 | { | |
259 | return dev->p && klist_node_attached(&dev->p->knode_driver); | |
260 | } | |
261 | ||
262 | static void driver_bound(struct device *dev) | |
263 | { | |
264 | if (device_is_bound(dev)) { | |
265 | printk(KERN_WARNING "%s: device %s already bound\n", | |
266 | __func__, kobject_name(&dev->kobj)); | |
267 | return; | |
268 | } | |
269 | ||
270 | pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name, | |
271 | __func__, dev_name(dev)); | |
272 | ||
273 | klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices); | |
274 | device_links_driver_bound(dev); | |
275 | ||
276 | device_pm_check_callbacks(dev); | |
277 | ||
278 | /* | |
279 | * Make sure the device is no longer in one of the deferred lists and | |
280 | * kick off retrying all pending devices | |
281 | */ | |
282 | driver_deferred_probe_del(dev); | |
283 | driver_deferred_probe_trigger(); | |
284 | ||
285 | if (dev->bus) | |
286 | blocking_notifier_call_chain(&dev->bus->p->bus_notifier, | |
287 | BUS_NOTIFY_BOUND_DRIVER, dev); | |
288 | ||
289 | kobject_uevent(&dev->kobj, KOBJ_BIND); | |
290 | } | |
291 | ||
292 | static int driver_sysfs_add(struct device *dev) | |
293 | { | |
294 | int ret; | |
295 | ||
296 | if (dev->bus) | |
297 | blocking_notifier_call_chain(&dev->bus->p->bus_notifier, | |
298 | BUS_NOTIFY_BIND_DRIVER, dev); | |
299 | ||
300 | ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj, | |
301 | kobject_name(&dev->kobj)); | |
302 | if (ret == 0) { | |
303 | ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj, | |
304 | "driver"); | |
305 | if (ret) | |
306 | sysfs_remove_link(&dev->driver->p->kobj, | |
307 | kobject_name(&dev->kobj)); | |
308 | } | |
309 | return ret; | |
310 | } | |
311 | ||
312 | static void driver_sysfs_remove(struct device *dev) | |
313 | { | |
314 | struct device_driver *drv = dev->driver; | |
315 | ||
316 | if (drv) { | |
317 | sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj)); | |
318 | sysfs_remove_link(&dev->kobj, "driver"); | |
319 | } | |
320 | } | |
321 | ||
322 | /** | |
323 | * device_bind_driver - bind a driver to one device. | |
324 | * @dev: device. | |
325 | * | |
326 | * Allow manual attachment of a driver to a device. | |
327 | * Caller must have already set @dev->driver. | |
328 | * | |
329 | * Note that this does not modify the bus reference count | |
330 | * nor take the bus's rwsem. Please verify those are accounted | |
331 | * for before calling this. (It is ok to call with no other effort | |
332 | * from a driver's probe() method.) | |
333 | * | |
334 | * This function must be called with the device lock held. | |
335 | */ | |
336 | int device_bind_driver(struct device *dev) | |
337 | { | |
338 | int ret; | |
339 | ||
340 | ret = driver_sysfs_add(dev); | |
341 | if (!ret) | |
342 | driver_bound(dev); | |
343 | else if (dev->bus) | |
344 | blocking_notifier_call_chain(&dev->bus->p->bus_notifier, | |
345 | BUS_NOTIFY_DRIVER_NOT_BOUND, dev); | |
346 | return ret; | |
347 | } | |
348 | EXPORT_SYMBOL_GPL(device_bind_driver); | |
349 | ||
350 | static atomic_t probe_count = ATOMIC_INIT(0); | |
351 | static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); | |
352 | ||
353 | static void driver_deferred_probe_add_trigger(struct device *dev, | |
354 | int local_trigger_count) | |
355 | { | |
356 | driver_deferred_probe_add(dev); | |
357 | /* Did a trigger occur while probing? Need to re-trigger if yes */ | |
358 | if (local_trigger_count != atomic_read(&deferred_trigger_count)) | |
359 | driver_deferred_probe_trigger(); | |
360 | } | |
361 | ||
362 | static int really_probe(struct device *dev, struct device_driver *drv) | |
363 | { | |
364 | int ret = -EPROBE_DEFER; | |
365 | int local_trigger_count = atomic_read(&deferred_trigger_count); | |
366 | bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) && | |
367 | !drv->suppress_bind_attrs; | |
368 | ||
369 | if (defer_all_probes) { | |
370 | /* | |
371 | * Value of defer_all_probes can be set only by | |
372 | * device_defer_all_probes_enable() which, in turn, will call | |
373 | * wait_for_device_probe() right after that to avoid any races. | |
374 | */ | |
375 | dev_dbg(dev, "Driver %s force probe deferral\n", drv->name); | |
376 | driver_deferred_probe_add(dev); | |
377 | return ret; | |
378 | } | |
379 | ||
380 | ret = device_links_check_suppliers(dev); | |
381 | if (ret == -EPROBE_DEFER) | |
382 | driver_deferred_probe_add_trigger(dev, local_trigger_count); | |
383 | if (ret) | |
384 | return ret; | |
385 | ||
386 | atomic_inc(&probe_count); | |
387 | pr_debug("bus: '%s': %s: probing driver %s with device %s\n", | |
388 | drv->bus->name, __func__, drv->name, dev_name(dev)); | |
389 | WARN_ON(!list_empty(&dev->devres_head)); | |
390 | ||
391 | re_probe: | |
392 | dev->driver = drv; | |
393 | ||
394 | /* If using pinctrl, bind pins now before probing */ | |
395 | ret = pinctrl_bind_pins(dev); | |
396 | if (ret) | |
397 | goto pinctrl_bind_failed; | |
398 | ||
399 | ret = dma_configure(dev); | |
400 | if (ret) | |
401 | goto probe_failed; | |
402 | ||
403 | if (driver_sysfs_add(dev)) { | |
404 | printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n", | |
405 | __func__, dev_name(dev)); | |
406 | goto probe_failed; | |
407 | } | |
408 | ||
409 | if (dev->pm_domain && dev->pm_domain->activate) { | |
410 | ret = dev->pm_domain->activate(dev); | |
411 | if (ret) | |
412 | goto probe_failed; | |
413 | } | |
414 | ||
415 | if (dev->bus->probe) { | |
416 | ret = dev->bus->probe(dev); | |
417 | if (ret) | |
418 | goto probe_failed; | |
419 | } else if (drv->probe) { | |
420 | ret = drv->probe(dev); | |
421 | if (ret) | |
422 | goto probe_failed; | |
423 | } | |
424 | ||
425 | if (test_remove) { | |
426 | test_remove = false; | |
427 | ||
428 | if (dev->bus->remove) | |
429 | dev->bus->remove(dev); | |
430 | else if (drv->remove) | |
431 | drv->remove(dev); | |
432 | ||
433 | devres_release_all(dev); | |
434 | driver_sysfs_remove(dev); | |
435 | dev->driver = NULL; | |
436 | dev_set_drvdata(dev, NULL); | |
437 | if (dev->pm_domain && dev->pm_domain->dismiss) | |
438 | dev->pm_domain->dismiss(dev); | |
439 | pm_runtime_reinit(dev); | |
440 | ||
441 | goto re_probe; | |
442 | } | |
443 | ||
444 | pinctrl_init_done(dev); | |
445 | ||
446 | if (dev->pm_domain && dev->pm_domain->sync) | |
447 | dev->pm_domain->sync(dev); | |
448 | ||
449 | driver_bound(dev); | |
450 | ret = 1; | |
451 | pr_debug("bus: '%s': %s: bound device %s to driver %s\n", | |
452 | drv->bus->name, __func__, dev_name(dev), drv->name); | |
453 | goto done; | |
454 | ||
455 | probe_failed: | |
456 | if (dev->bus) | |
457 | blocking_notifier_call_chain(&dev->bus->p->bus_notifier, | |
458 | BUS_NOTIFY_DRIVER_NOT_BOUND, dev); | |
459 | pinctrl_bind_failed: | |
460 | device_links_no_driver(dev); | |
461 | devres_release_all(dev); | |
462 | dma_deconfigure(dev); | |
463 | driver_sysfs_remove(dev); | |
464 | dev->driver = NULL; | |
465 | dev_set_drvdata(dev, NULL); | |
466 | if (dev->pm_domain && dev->pm_domain->dismiss) | |
467 | dev->pm_domain->dismiss(dev); | |
468 | pm_runtime_reinit(dev); | |
469 | dev_pm_set_driver_flags(dev, 0); | |
470 | ||
471 | switch (ret) { | |
472 | case -EPROBE_DEFER: | |
473 | /* Driver requested deferred probing */ | |
474 | dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name); | |
475 | driver_deferred_probe_add_trigger(dev, local_trigger_count); | |
476 | break; | |
477 | case -ENODEV: | |
478 | case -ENXIO: | |
479 | pr_debug("%s: probe of %s rejects match %d\n", | |
480 | drv->name, dev_name(dev), ret); | |
481 | break; | |
482 | default: | |
483 | /* driver matched but the probe failed */ | |
484 | printk(KERN_WARNING | |
485 | "%s: probe of %s failed with error %d\n", | |
486 | drv->name, dev_name(dev), ret); | |
487 | } | |
488 | /* | |
489 | * Ignore errors returned by ->probe so that the next driver can try | |
490 | * its luck. | |
491 | */ | |
492 | ret = 0; | |
493 | done: | |
494 | atomic_dec(&probe_count); | |
495 | wake_up(&probe_waitqueue); | |
496 | return ret; | |
497 | } | |
498 | ||
499 | /** | |
500 | * driver_probe_done | |
501 | * Determine if the probe sequence is finished or not. | |
502 | * | |
503 | * Should somehow figure out how to use a semaphore, not an atomic variable... | |
504 | */ | |
505 | int driver_probe_done(void) | |
506 | { | |
507 | pr_debug("%s: probe_count = %d\n", __func__, | |
508 | atomic_read(&probe_count)); | |
509 | if (atomic_read(&probe_count)) | |
510 | return -EBUSY; | |
511 | return 0; | |
512 | } | |
513 | ||
514 | /** | |
515 | * wait_for_device_probe | |
516 | * Wait for device probing to be completed. | |
517 | */ | |
518 | void wait_for_device_probe(void) | |
519 | { | |
520 | /* wait for the deferred probe workqueue to finish */ | |
521 | flush_work(&deferred_probe_work); | |
522 | ||
523 | /* wait for the known devices to complete their probing */ | |
524 | wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); | |
525 | async_synchronize_full(); | |
526 | } | |
527 | EXPORT_SYMBOL_GPL(wait_for_device_probe); | |
528 | ||
529 | /** | |
530 | * driver_probe_device - attempt to bind device & driver together | |
531 | * @drv: driver to bind a device to | |
532 | * @dev: device to try to bind to the driver | |
533 | * | |
534 | * This function returns -ENODEV if the device is not registered, | |
535 | * 1 if the device is bound successfully and 0 otherwise. | |
536 | * | |
537 | * This function must be called with @dev lock held. When called for a | |
538 | * USB interface, @dev->parent lock must be held as well. | |
539 | * | |
540 | * If the device has a parent, runtime-resume the parent before driver probing. | |
541 | */ | |
542 | int driver_probe_device(struct device_driver *drv, struct device *dev) | |
543 | { | |
544 | int ret = 0; | |
545 | ||
546 | if (!device_is_registered(dev)) | |
547 | return -ENODEV; | |
548 | ||
549 | pr_debug("bus: '%s': %s: matched device %s with driver %s\n", | |
550 | drv->bus->name, __func__, dev_name(dev), drv->name); | |
551 | ||
552 | pm_runtime_get_suppliers(dev); | |
553 | if (dev->parent) | |
554 | pm_runtime_get_sync(dev->parent); | |
555 | ||
556 | pm_runtime_barrier(dev); | |
557 | ret = really_probe(dev, drv); | |
558 | pm_request_idle(dev); | |
559 | ||
560 | if (dev->parent) | |
561 | pm_runtime_put(dev->parent); | |
562 | ||
563 | pm_runtime_put_suppliers(dev); | |
564 | return ret; | |
565 | } | |
566 | ||
567 | bool driver_allows_async_probing(struct device_driver *drv) | |
568 | { | |
569 | switch (drv->probe_type) { | |
570 | case PROBE_PREFER_ASYNCHRONOUS: | |
571 | return true; | |
572 | ||
573 | case PROBE_FORCE_SYNCHRONOUS: | |
574 | return false; | |
575 | ||
576 | default: | |
577 | if (module_requested_async_probing(drv->owner)) | |
578 | return true; | |
579 | ||
580 | return false; | |
581 | } | |
582 | } | |
583 | ||
584 | struct device_attach_data { | |
585 | struct device *dev; | |
586 | ||
587 | /* | |
588 | * Indicates whether we are are considering asynchronous probing or | |
589 | * not. Only initial binding after device or driver registration | |
590 | * (including deferral processing) may be done asynchronously, the | |
591 | * rest is always synchronous, as we expect it is being done by | |
592 | * request from userspace. | |
593 | */ | |
594 | bool check_async; | |
595 | ||
596 | /* | |
597 | * Indicates if we are binding synchronous or asynchronous drivers. | |
598 | * When asynchronous probing is enabled we'll execute 2 passes | |
599 | * over drivers: first pass doing synchronous probing and second | |
600 | * doing asynchronous probing (if synchronous did not succeed - | |
601 | * most likely because there was no driver requiring synchronous | |
602 | * probing - and we found asynchronous driver during first pass). | |
603 | * The 2 passes are done because we can't shoot asynchronous | |
604 | * probe for given device and driver from bus_for_each_drv() since | |
605 | * driver pointer is not guaranteed to stay valid once | |
606 | * bus_for_each_drv() iterates to the next driver on the bus. | |
607 | */ | |
608 | bool want_async; | |
609 | ||
610 | /* | |
611 | * We'll set have_async to 'true' if, while scanning for matching | |
612 | * driver, we'll encounter one that requests asynchronous probing. | |
613 | */ | |
614 | bool have_async; | |
615 | }; | |
616 | ||
617 | static int __device_attach_driver(struct device_driver *drv, void *_data) | |
618 | { | |
619 | struct device_attach_data *data = _data; | |
620 | struct device *dev = data->dev; | |
621 | bool async_allowed; | |
622 | int ret; | |
623 | ||
624 | ret = driver_match_device(drv, dev); | |
625 | if (ret == 0) { | |
626 | /* no match */ | |
627 | return 0; | |
628 | } else if (ret == -EPROBE_DEFER) { | |
629 | dev_dbg(dev, "Device match requests probe deferral\n"); | |
630 | driver_deferred_probe_add(dev); | |
631 | } else if (ret < 0) { | |
632 | dev_dbg(dev, "Bus failed to match device: %d", ret); | |
633 | return ret; | |
634 | } /* ret > 0 means positive match */ | |
635 | ||
636 | async_allowed = driver_allows_async_probing(drv); | |
637 | ||
638 | if (async_allowed) | |
639 | data->have_async = true; | |
640 | ||
641 | if (data->check_async && async_allowed != data->want_async) | |
642 | return 0; | |
643 | ||
644 | return driver_probe_device(drv, dev); | |
645 | } | |
646 | ||
647 | static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) | |
648 | { | |
649 | struct device *dev = _dev; | |
650 | struct device_attach_data data = { | |
651 | .dev = dev, | |
652 | .check_async = true, | |
653 | .want_async = true, | |
654 | }; | |
655 | ||
656 | device_lock(dev); | |
657 | ||
658 | /* | |
659 | * Check if device has already been removed or claimed. This may | |
660 | * happen with driver loading, device discovery/registration, | |
661 | * and deferred probe processing happens all at once with | |
662 | * multiple threads. | |
663 | */ | |
664 | if (dev->p->dead || dev->driver) | |
665 | goto out_unlock; | |
666 | ||
667 | if (dev->parent) | |
668 | pm_runtime_get_sync(dev->parent); | |
669 | ||
670 | bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver); | |
671 | dev_dbg(dev, "async probe completed\n"); | |
672 | ||
673 | pm_request_idle(dev); | |
674 | ||
675 | if (dev->parent) | |
676 | pm_runtime_put(dev->parent); | |
677 | out_unlock: | |
678 | device_unlock(dev); | |
679 | ||
680 | put_device(dev); | |
681 | } | |
682 | ||
683 | static int __device_attach(struct device *dev, bool allow_async) | |
684 | { | |
685 | int ret = 0; | |
686 | ||
687 | device_lock(dev); | |
688 | if (dev->driver) { | |
689 | if (device_is_bound(dev)) { | |
690 | ret = 1; | |
691 | goto out_unlock; | |
692 | } | |
693 | ret = device_bind_driver(dev); | |
694 | if (ret == 0) | |
695 | ret = 1; | |
696 | else { | |
697 | dev->driver = NULL; | |
698 | ret = 0; | |
699 | } | |
700 | } else { | |
701 | struct device_attach_data data = { | |
702 | .dev = dev, | |
703 | .check_async = allow_async, | |
704 | .want_async = false, | |
705 | }; | |
706 | ||
707 | if (dev->parent) | |
708 | pm_runtime_get_sync(dev->parent); | |
709 | ||
710 | ret = bus_for_each_drv(dev->bus, NULL, &data, | |
711 | __device_attach_driver); | |
712 | if (!ret && allow_async && data.have_async) { | |
713 | /* | |
714 | * If we could not find appropriate driver | |
715 | * synchronously and we are allowed to do | |
716 | * async probes and there are drivers that | |
717 | * want to probe asynchronously, we'll | |
718 | * try them. | |
719 | */ | |
720 | dev_dbg(dev, "scheduling asynchronous probe\n"); | |
721 | get_device(dev); | |
722 | async_schedule(__device_attach_async_helper, dev); | |
723 | } else { | |
724 | pm_request_idle(dev); | |
725 | } | |
726 | ||
727 | if (dev->parent) | |
728 | pm_runtime_put(dev->parent); | |
729 | } | |
730 | out_unlock: | |
731 | device_unlock(dev); | |
732 | return ret; | |
733 | } | |
734 | ||
735 | /** | |
736 | * device_attach - try to attach device to a driver. | |
737 | * @dev: device. | |
738 | * | |
739 | * Walk the list of drivers that the bus has and call | |
740 | * driver_probe_device() for each pair. If a compatible | |
741 | * pair is found, break out and return. | |
742 | * | |
743 | * Returns 1 if the device was bound to a driver; | |
744 | * 0 if no matching driver was found; | |
745 | * -ENODEV if the device is not registered. | |
746 | * | |
747 | * When called for a USB interface, @dev->parent lock must be held. | |
748 | */ | |
749 | int device_attach(struct device *dev) | |
750 | { | |
751 | return __device_attach(dev, false); | |
752 | } | |
753 | EXPORT_SYMBOL_GPL(device_attach); | |
754 | ||
755 | void device_initial_probe(struct device *dev) | |
756 | { | |
757 | __device_attach(dev, true); | |
758 | } | |
759 | ||
760 | static int __driver_attach(struct device *dev, void *data) | |
761 | { | |
762 | struct device_driver *drv = data; | |
763 | int ret; | |
764 | ||
765 | /* | |
766 | * Lock device and try to bind to it. We drop the error | |
767 | * here and always return 0, because we need to keep trying | |
768 | * to bind to devices and some drivers will return an error | |
769 | * simply if it didn't support the device. | |
770 | * | |
771 | * driver_probe_device() will spit a warning if there | |
772 | * is an error. | |
773 | */ | |
774 | ||
775 | ret = driver_match_device(drv, dev); | |
776 | if (ret == 0) { | |
777 | /* no match */ | |
778 | return 0; | |
779 | } else if (ret == -EPROBE_DEFER) { | |
780 | dev_dbg(dev, "Device match requests probe deferral\n"); | |
781 | driver_deferred_probe_add(dev); | |
782 | } else if (ret < 0) { | |
783 | dev_dbg(dev, "Bus failed to match device: %d", ret); | |
784 | return ret; | |
785 | } /* ret > 0 means positive match */ | |
786 | ||
787 | if (dev->parent) /* Needed for USB */ | |
788 | device_lock(dev->parent); | |
789 | device_lock(dev); | |
790 | if (!dev->p->dead && !dev->driver) | |
791 | driver_probe_device(drv, dev); | |
792 | device_unlock(dev); | |
793 | if (dev->parent) | |
794 | device_unlock(dev->parent); | |
795 | ||
796 | return 0; | |
797 | } | |
798 | ||
799 | /** | |
800 | * driver_attach - try to bind driver to devices. | |
801 | * @drv: driver. | |
802 | * | |
803 | * Walk the list of devices that the bus has on it and try to | |
804 | * match the driver with each one. If driver_probe_device() | |
805 | * returns 0 and the @dev->driver is set, we've found a | |
806 | * compatible pair. | |
807 | */ | |
808 | int driver_attach(struct device_driver *drv) | |
809 | { | |
810 | return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); | |
811 | } | |
812 | EXPORT_SYMBOL_GPL(driver_attach); | |
813 | ||
814 | void *vfio_pci_driver_ptr = (void *)0xdeadfeed; | |
815 | EXPORT_SYMBOL(vfio_pci_driver_ptr); | |
816 | ||
817 | /* | |
818 | * __device_release_driver() must be called with @dev lock held. | |
819 | * When called for a USB interface, @dev->parent lock must be held as well. | |
820 | */ | |
821 | static void __device_release_driver(struct device *dev, struct device *parent) | |
822 | { | |
823 | struct device_driver *drv; | |
824 | ||
825 | drv = dev->driver; | |
826 | if (drv) { | |
827 | while (device_links_busy(dev)) { | |
828 | device_unlock(dev); | |
829 | if (parent) | |
830 | device_unlock(parent); | |
831 | ||
832 | device_links_unbind_consumers(dev); | |
833 | if (parent) | |
834 | device_lock(parent); | |
835 | ||
836 | device_lock(dev); | |
837 | /* | |
838 | * A concurrent invocation of the same function might | |
839 | * have released the driver successfully while this one | |
840 | * was waiting, so check for that. | |
841 | */ | |
842 | if (dev->driver != drv) | |
843 | return; | |
844 | } | |
845 | ||
846 | pm_runtime_get_sync(dev); | |
847 | pm_runtime_clean_up_links(dev); | |
848 | ||
849 | driver_sysfs_remove(dev); | |
850 | ||
851 | if (dev->bus) | |
852 | blocking_notifier_call_chain(&dev->bus->p->bus_notifier, | |
853 | BUS_NOTIFY_UNBIND_DRIVER, | |
854 | dev); | |
855 | ||
856 | pm_runtime_put_sync(dev); | |
857 | ||
858 | if (dev->bus && dev->bus->remove) | |
859 | dev->bus->remove(dev); | |
860 | else if (drv->remove) | |
861 | drv->remove(dev); | |
862 | /* | |
863 | * A concurrent invocation of the same function might | |
864 | * have released the driver successfully while this one | |
865 | * was waiting, so check for that. | |
866 | * LP: #1792099 | |
867 | * | |
868 | * Limit this to the vfio_pci_driver as some drivers NULL | |
869 | * out this pointer in their remove() function. | |
870 | * LP: #1803942 | |
871 | */ | |
872 | if (drv == vfio_pci_driver_ptr && dev->driver != drv) | |
873 | return; | |
874 | ||
875 | device_links_driver_cleanup(dev); | |
876 | ||
877 | devres_release_all(dev); | |
878 | dma_deconfigure(dev); | |
879 | dev->driver = NULL; | |
880 | dev_set_drvdata(dev, NULL); | |
881 | if (dev->pm_domain && dev->pm_domain->dismiss) | |
882 | dev->pm_domain->dismiss(dev); | |
883 | pm_runtime_reinit(dev); | |
884 | dev_pm_set_driver_flags(dev, 0); | |
885 | ||
886 | klist_remove(&dev->p->knode_driver); | |
887 | device_pm_check_callbacks(dev); | |
888 | if (dev->bus) | |
889 | blocking_notifier_call_chain(&dev->bus->p->bus_notifier, | |
890 | BUS_NOTIFY_UNBOUND_DRIVER, | |
891 | dev); | |
892 | ||
893 | kobject_uevent(&dev->kobj, KOBJ_UNBIND); | |
894 | } | |
895 | } | |
896 | ||
897 | void device_release_driver_internal(struct device *dev, | |
898 | struct device_driver *drv, | |
899 | struct device *parent) | |
900 | { | |
901 | if (parent) | |
902 | device_lock(parent); | |
903 | ||
904 | device_lock(dev); | |
905 | if (!drv || drv == dev->driver) | |
906 | __device_release_driver(dev, parent); | |
907 | ||
908 | device_unlock(dev); | |
909 | if (parent) | |
910 | device_unlock(parent); | |
911 | } | |
912 | ||
913 | /** | |
914 | * device_release_driver - manually detach device from driver. | |
915 | * @dev: device. | |
916 | * | |
917 | * Manually detach device from driver. | |
918 | * When called for a USB interface, @dev->parent lock must be held. | |
919 | * | |
920 | * If this function is to be called with @dev->parent lock held, ensure that | |
921 | * the device's consumers are unbound in advance or that their locks can be | |
922 | * acquired under the @dev->parent lock. | |
923 | */ | |
924 | void device_release_driver(struct device *dev) | |
925 | { | |
926 | /* | |
927 | * If anyone calls device_release_driver() recursively from | |
928 | * within their ->remove callback for the same device, they | |
929 | * will deadlock right here. | |
930 | */ | |
931 | device_release_driver_internal(dev, NULL, NULL); | |
932 | } | |
933 | EXPORT_SYMBOL_GPL(device_release_driver); | |
934 | ||
935 | /** | |
936 | * driver_detach - detach driver from all devices it controls. | |
937 | * @drv: driver. | |
938 | */ | |
939 | void driver_detach(struct device_driver *drv) | |
940 | { | |
941 | struct device_private *dev_prv; | |
942 | struct device *dev; | |
943 | ||
944 | if (driver_allows_async_probing(drv)) | |
945 | async_synchronize_full(); | |
946 | ||
947 | for (;;) { | |
948 | spin_lock(&drv->p->klist_devices.k_lock); | |
949 | if (list_empty(&drv->p->klist_devices.k_list)) { | |
950 | spin_unlock(&drv->p->klist_devices.k_lock); | |
951 | break; | |
952 | } | |
953 | dev_prv = list_entry(drv->p->klist_devices.k_list.prev, | |
954 | struct device_private, | |
955 | knode_driver.n_node); | |
956 | dev = dev_prv->device; | |
957 | get_device(dev); | |
958 | spin_unlock(&drv->p->klist_devices.k_lock); | |
959 | device_release_driver_internal(dev, drv, dev->parent); | |
960 | put_device(dev); | |
961 | } | |
962 | } |