drivers/base/dd.c

   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 <[email protected]>
  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 struct dentry *deferred_devices;
  59 static bool initcalls_done;
  60
  61 /* Save the async probe drivers' name from kernel cmdline */
  62 #define ASYNC_DRV_NAMES_MAX_LEN 256
  63 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
  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
  72 /*
  73  * deferred_probe_work_func() - Retry probing devices in the active list.
  74  */
  75 static void deferred_probe_work_func(struct work_struct *work)
  76 {
  77         struct device *dev;
  78         struct device_private *private;
  79         /*
  80          * This block processes every device in the deferred 'active' list.
  81          * Each device is removed from the active list and passed to
  82          * bus_probe_device() to re-attempt the probe.  The loop continues
  83          * until every device in the active list is removed and retried.
  84          *
  85          * Note: Once the device is removed from the list and the mutex is
  86          * released, it is possible for the device get freed by another thread
  87          * and cause a illegal pointer dereference.  This code uses
  88          * get/put_device() to ensure the device structure cannot disappear
  89          * from under our feet.
  90          */
  91         mutex_lock(&deferred_probe_mutex);
  92         while (!list_empty(&deferred_probe_active_list)) {
  93                 private = list_first_entry(&deferred_probe_active_list,
  94                                         typeof(*dev->p), deferred_probe);
  95                 dev = private->device;
  96                 list_del_init(&private->deferred_probe);
  97
  98                 get_device(dev);
  99
 100                 kfree(dev->p->deferred_probe_reason);
 101                 dev->p->deferred_probe_reason = NULL;
 102
 103                 /*
 104                  * Drop the mutex while probing each device; the probe path may
 105                  * manipulate the deferred list
 106                  */
 107                 mutex_unlock(&deferred_probe_mutex);
 108
 109                 /*
 110                  * Force the device to the end of the dpm_list since
 111                  * the PM code assumes that the order we add things to
 112                  * the list is a good order for suspend but deferred
 113                  * probe makes that very unsafe.
 114                  */
 115                 device_pm_move_to_tail(dev);
 116
 117                 dev_dbg(dev, "Retrying from deferred list\n");
 118                 bus_probe_device(dev);
 119                 mutex_lock(&deferred_probe_mutex);
 120
 121                 put_device(dev);
 122         }
 123         mutex_unlock(&deferred_probe_mutex);
 124 }
 125 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 126
 127 void driver_deferred_probe_add(struct device *dev)
 128 {
 129         mutex_lock(&deferred_probe_mutex);
 130         if (list_empty(&dev->p->deferred_probe)) {
 131                 dev_dbg(dev, "Added to deferred list\n");
 132                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 133         }
 134         mutex_unlock(&deferred_probe_mutex);
 135 }
 136
 137 void driver_deferred_probe_del(struct device *dev)
 138 {
 139         mutex_lock(&deferred_probe_mutex);
 140         if (!list_empty(&dev->p->deferred_probe)) {
 141                 dev_dbg(dev, "Removed from deferred list\n");
 142                 list_del_init(&dev->p->deferred_probe);
 143                 kfree(dev->p->deferred_probe_reason);
 144                 dev->p->deferred_probe_reason = NULL;
 145         }
 146         mutex_unlock(&deferred_probe_mutex);
 147 }
 148
 149 static bool driver_deferred_probe_enable = false;
 150 /**
 151  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 152  *
 153  * This functions moves all devices from the pending list to the active
 154  * list and schedules the deferred probe workqueue to process them.  It
 155  * should be called anytime a driver is successfully bound to a device.
 156  *
 157  * Note, there is a race condition in multi-threaded probe. In the case where
 158  * more than one device is probing at the same time, it is possible for one
 159  * probe to complete successfully while another is about to defer. If the second
 160  * depends on the first, then it will get put on the pending list after the
 161  * trigger event has already occurred and will be stuck there.
 162  *
 163  * The atomic 'deferred_trigger_count' is used to determine if a successful
 164  * trigger has occurred in the midst of probing a driver. If the trigger count
 165  * changes in the midst of a probe, then deferred processing should be triggered
 166  * again.
 167  */
 168 static void driver_deferred_probe_trigger(void)
 169 {
 170         if (!driver_deferred_probe_enable)
 171                 return;
 172
 173         /*
 174          * A successful probe means that all the devices in the pending list
 175          * should be triggered to be reprobed.  Move all the deferred devices
 176          * into the active list so they can be retried by the workqueue
 177          */
 178         mutex_lock(&deferred_probe_mutex);
 179         atomic_inc(&deferred_trigger_count);
 180         list_splice_tail_init(&deferred_probe_pending_list,
 181                               &deferred_probe_active_list);
 182         mutex_unlock(&deferred_probe_mutex);
 183
 184         /*
 185          * Kick the re-probe thread.  It may already be scheduled, but it is
 186          * safe to kick it again.
 187          */
 188         schedule_work(&deferred_probe_work);
 189 }
 190
 191 /**
 192  * device_block_probing() - Block/defer device's probes
 193  *
 194  *      It will disable probing of devices and defer their probes instead.
 195  */
 196 void device_block_probing(void)
 197 {
 198         defer_all_probes = true;
 199         /* sync with probes to avoid races. */
 200         wait_for_device_probe();
 201 }
 202
 203 /**
 204  * device_unblock_probing() - Unblock/enable device's probes
 205  *
 206  *      It will restore normal behavior and trigger re-probing of deferred
 207  * devices.
 208  */
 209 void device_unblock_probing(void)
 210 {
 211         defer_all_probes = false;
 212         driver_deferred_probe_trigger();
 213 }
 214
 215 /**
 216  * device_set_deferred_probe_reason() - Set defer probe reason message for device
 217  * @dev: the pointer to the struct device
 218  * @vaf: the pointer to va_format structure with message
 219  */
 220 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
 221 {
 222         const char *drv = dev_driver_string(dev);
 223
 224         mutex_lock(&deferred_probe_mutex);
 225
 226         kfree(dev->p->deferred_probe_reason);
 227         dev->p->deferred_probe_reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
 228
 229         mutex_unlock(&deferred_probe_mutex);
 230 }
 231
 232 /*
 233  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 234  */
 235 static int deferred_devs_show(struct seq_file *s, void *data)
 236 {
 237         struct device_private *curr;
 238
 239         mutex_lock(&deferred_probe_mutex);
 240
 241         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 242                 seq_printf(s, "%s\t%s", dev_name(curr->device),
 243                            curr->device->p->deferred_probe_reason ?: "\n");
 244
 245         mutex_unlock(&deferred_probe_mutex);
 246
 247         return 0;
 248 }
 249 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 250
 251 int driver_deferred_probe_timeout;
 252 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
 253 static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue);
 254
 255 static int __init deferred_probe_timeout_setup(char *str)
 256 {
 257         int timeout;
 258
 259         if (!kstrtoint(str, 10, &timeout))
 260                 driver_deferred_probe_timeout = timeout;
 261         return 1;
 262 }
 263 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 264
 265 /**
 266  * driver_deferred_probe_check_state() - Check deferred probe state
 267  * @dev: device to check
 268  *
 269  * Return:
 270  * -ENODEV if initcalls have completed and modules are disabled.
 271  * -ETIMEDOUT if the deferred probe timeout was set and has expired
 272  *  and modules are enabled.
 273  * -EPROBE_DEFER in other cases.
 274  *
 275  * Drivers or subsystems can opt-in to calling this function instead of directly
 276  * returning -EPROBE_DEFER.
 277  */
 278 int driver_deferred_probe_check_state(struct device *dev)
 279 {
 280         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 281                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 282                 return -ENODEV;
 283         }
 284
 285         if (!driver_deferred_probe_timeout && initcalls_done) {
 286                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 287                 return -ETIMEDOUT;
 288         }
 289
 290         return -EPROBE_DEFER;
 291 }
 292
 293 static void deferred_probe_timeout_work_func(struct work_struct *work)
 294 {
 295         struct device_private *private, *p;
 296
 297         driver_deferred_probe_timeout = 0;
 298         driver_deferred_probe_trigger();
 299         flush_work(&deferred_probe_work);
 300
 301         list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe)
 302                 dev_info(private->device, "deferred probe pending\n");
 303         wake_up_all(&probe_timeout_waitqueue);
 304 }
 305 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 306
 307 /**
 308  * deferred_probe_initcall() - Enable probing of deferred devices
 309  *
 310  * We don't want to get in the way when the bulk of drivers are getting probed.
 311  * Instead, this initcall makes sure that deferred probing is delayed until
 312  * late_initcall time.
 313  */
 314 static int deferred_probe_initcall(void)
 315 {
 316         deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
 317                                                NULL, &deferred_devs_fops);
 318
 319         driver_deferred_probe_enable = true;
 320         driver_deferred_probe_trigger();
 321         /* Sort as many dependencies as possible before exiting initcalls */
 322         flush_work(&deferred_probe_work);
 323         initcalls_done = true;
 324
 325         /*
 326          * Trigger deferred probe again, this time we won't defer anything
 327          * that is optional
 328          */
 329         driver_deferred_probe_trigger();
 330         flush_work(&deferred_probe_work);
 331
 332         if (driver_deferred_probe_timeout > 0) {
 333                 schedule_delayed_work(&deferred_probe_timeout_work,
 334                         driver_deferred_probe_timeout * HZ);
 335         }
 336         return 0;
 337 }
 338 late_initcall(deferred_probe_initcall);
 339
 340 static void __exit deferred_probe_exit(void)
 341 {
 342         debugfs_remove_recursive(deferred_devices);
 343 }
 344 __exitcall(deferred_probe_exit);
 345
 346 /**
 347  * device_is_bound() - Check if device is bound to a driver
 348  * @dev: device to check
 349  *
 350  * Returns true if passed device has already finished probing successfully
 351  * against a driver.
 352  *
 353  * This function must be called with the device lock held.
 354  */
 355 bool device_is_bound(struct device *dev)
 356 {
 357         return dev->p && klist_node_attached(&dev->p->knode_driver);
 358 }
 359
 360 static void driver_bound(struct device *dev)
 361 {
 362         if (device_is_bound(dev)) {
 363                 pr_warn("%s: device %s already bound\n",
 364                         __func__, kobject_name(&dev->kobj));
 365                 return;
 366         }
 367
 368         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 369                  __func__, dev_name(dev));
 370
 371         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 372         device_links_driver_bound(dev);
 373
 374         device_pm_check_callbacks(dev);
 375
 376         /*
 377          * Make sure the device is no longer in one of the deferred lists and
 378          * kick off retrying all pending devices
 379          */
 380         driver_deferred_probe_del(dev);
 381         driver_deferred_probe_trigger();
 382
 383         if (dev->bus)
 384                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 385                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 386
 387         kobject_uevent(&dev->kobj, KOBJ_BIND);
 388 }
 389
 390 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 391                             const char *buf, size_t count)
 392 {
 393         device_lock(dev);
 394         dev->driver->coredump(dev);
 395         device_unlock(dev);
 396
 397         return count;
 398 }
 399 static DEVICE_ATTR_WO(coredump);
 400
 401 static int driver_sysfs_add(struct device *dev)
 402 {
 403         int ret;
 404
 405         if (dev->bus)
 406                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 407                                              BUS_NOTIFY_BIND_DRIVER, dev);
 408
 409         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 410                                 kobject_name(&dev->kobj));
 411         if (ret)
 412                 goto fail;
 413
 414         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 415                                 "driver");
 416         if (ret)
 417                 goto rm_dev;
 418
 419         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
 420             !device_create_file(dev, &dev_attr_coredump))
 421                 return 0;
 422
 423         sysfs_remove_link(&dev->kobj, "driver");
 424
 425 rm_dev:
 426         sysfs_remove_link(&dev->driver->p->kobj,
 427                           kobject_name(&dev->kobj));
 428
 429 fail:
 430         return ret;
 431 }
 432
 433 static void driver_sysfs_remove(struct device *dev)
 434 {
 435         struct device_driver *drv = dev->driver;
 436
 437         if (drv) {
 438                 if (drv->coredump)
 439                         device_remove_file(dev, &dev_attr_coredump);
 440                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 441                 sysfs_remove_link(&dev->kobj, "driver");
 442         }
 443 }
 444
 445 /**
 446  * device_bind_driver - bind a driver to one device.
 447  * @dev: device.
 448  *
 449  * Allow manual attachment of a driver to a device.
 450  * Caller must have already set @dev->driver.
 451  *
 452  * Note that this does not modify the bus reference count.
 453  * Please verify that is accounted for before calling this.
 454  * (It is ok to call with no other effort from a driver's probe() method.)
 455  *
 456  * This function must be called with the device lock held.
 457  */
 458 int device_bind_driver(struct device *dev)
 459 {
 460         int ret;
 461
 462         ret = driver_sysfs_add(dev);
 463         if (!ret)
 464                 driver_bound(dev);
 465         else if (dev->bus)
 466                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 467                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 468         return ret;
 469 }
 470 EXPORT_SYMBOL_GPL(device_bind_driver);
 471
 472 static atomic_t probe_count = ATOMIC_INIT(0);
 473 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 474
 475 static void driver_deferred_probe_add_trigger(struct device *dev,
 476                                               int local_trigger_count)
 477 {
 478         driver_deferred_probe_add(dev);
 479         /* Did a trigger occur while probing? Need to re-trigger if yes */
 480         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 481                 driver_deferred_probe_trigger();
 482 }
 483
 484 static ssize_t state_synced_show(struct device *dev,
 485                                  struct device_attribute *attr, char *buf)
 486 {
 487         bool val;
 488
 489         device_lock(dev);
 490         val = dev->state_synced;
 491         device_unlock(dev);
 492
 493         return sysfs_emit(buf, "%u\n", val);
 494 }
 495 static DEVICE_ATTR_RO(state_synced);
 496
 497 static int really_probe(struct device *dev, struct device_driver *drv)
 498 {
 499         int ret = -EPROBE_DEFER;
 500         int local_trigger_count = atomic_read(&deferred_trigger_count);
 501         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 502                            !drv->suppress_bind_attrs;
 503
 504         if (defer_all_probes) {
 505                 /*
 506                  * Value of defer_all_probes can be set only by
 507                  * device_block_probing() which, in turn, will call
 508                  * wait_for_device_probe() right after that to avoid any races.
 509                  */
 510                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 511                 driver_deferred_probe_add(dev);
 512                 return ret;
 513         }
 514
 515         ret = device_links_check_suppliers(dev);
 516         if (ret == -EPROBE_DEFER)
 517                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 518         if (ret)
 519                 return ret;
 520
 521         atomic_inc(&probe_count);
 522         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 523                  drv->bus->name, __func__, drv->name, dev_name(dev));
 524         if (!list_empty(&dev->devres_head)) {
 525                 dev_crit(dev, "Resources present before probing\n");
 526                 ret = -EBUSY;
 527                 goto done;
 528         }
 529
 530 re_probe:
 531         dev->driver = drv;
 532
 533         /* If using pinctrl, bind pins now before probing */
 534         ret = pinctrl_bind_pins(dev);
 535         if (ret)
 536                 goto pinctrl_bind_failed;
 537
 538         if (dev->bus->dma_configure) {
 539                 ret = dev->bus->dma_configure(dev);
 540                 if (ret)
 541                         goto probe_failed;
 542         }
 543
 544         if (driver_sysfs_add(dev)) {
 545                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 546                        __func__, dev_name(dev));
 547                 goto probe_failed;
 548         }
 549
 550         if (dev->pm_domain && dev->pm_domain->activate) {
 551                 ret = dev->pm_domain->activate(dev);
 552                 if (ret)
 553                         goto probe_failed;
 554         }
 555
 556         if (dev->bus->probe) {
 557                 ret = dev->bus->probe(dev);
 558                 if (ret)
 559                         goto probe_failed;
 560         } else if (drv->probe) {
 561                 ret = drv->probe(dev);
 562                 if (ret)
 563                         goto probe_failed;
 564         }
 565
 566         if (device_add_groups(dev, drv->dev_groups)) {
 567                 dev_err(dev, "device_add_groups() failed\n");
 568                 goto dev_groups_failed;
 569         }
 570
 571         if (dev_has_sync_state(dev) &&
 572             device_create_file(dev, &dev_attr_state_synced)) {
 573                 dev_err(dev, "state_synced sysfs add failed\n");
 574                 goto dev_sysfs_state_synced_failed;
 575         }
 576
 577         if (test_remove) {
 578                 test_remove = false;
 579
 580                 device_remove_file(dev, &dev_attr_state_synced);
 581                 device_remove_groups(dev, drv->dev_groups);
 582
 583                 if (dev->bus->remove)
 584                         dev->bus->remove(dev);
 585                 else if (drv->remove)
 586                         drv->remove(dev);
 587
 588                 devres_release_all(dev);
 589                 driver_sysfs_remove(dev);
 590                 dev->driver = NULL;
 591                 dev_set_drvdata(dev, NULL);
 592                 if (dev->pm_domain && dev->pm_domain->dismiss)
 593                         dev->pm_domain->dismiss(dev);
 594                 pm_runtime_reinit(dev);
 595
 596                 goto re_probe;
 597         }
 598
 599         pinctrl_init_done(dev);
 600
 601         if (dev->pm_domain && dev->pm_domain->sync)
 602                 dev->pm_domain->sync(dev);
 603
 604         driver_bound(dev);
 605         ret = 1;
 606         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 607                  drv->bus->name, __func__, dev_name(dev), drv->name);
 608         goto done;
 609
 610 dev_sysfs_state_synced_failed:
 611         device_remove_groups(dev, drv->dev_groups);
 612 dev_groups_failed:
 613         if (dev->bus->remove)
 614                 dev->bus->remove(dev);
 615         else if (drv->remove)
 616                 drv->remove(dev);
 617 probe_failed:
 618         kfree(dev->dma_range_map);
 619         dev->dma_range_map = NULL;
 620         if (dev->bus)
 621                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 622                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 623 pinctrl_bind_failed:
 624         device_links_no_driver(dev);
 625         devres_release_all(dev);
 626         arch_teardown_dma_ops(dev);
 627         driver_sysfs_remove(dev);
 628         dev->driver = NULL;
 629         dev_set_drvdata(dev, NULL);
 630         if (dev->pm_domain && dev->pm_domain->dismiss)
 631                 dev->pm_domain->dismiss(dev);
 632         pm_runtime_reinit(dev);
 633         dev_pm_set_driver_flags(dev, 0);
 634
 635         switch (ret) {
 636         case -EPROBE_DEFER:
 637                 /* Driver requested deferred probing */
 638                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 639                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 640                 break;
 641         case -ENODEV:
 642         case -ENXIO:
 643                 pr_debug("%s: probe of %s rejects match %d\n",
 644                          drv->name, dev_name(dev), ret);
 645                 break;
 646         default:
 647                 /* driver matched but the probe failed */
 648                 pr_warn("%s: probe of %s failed with error %d\n",
 649                         drv->name, dev_name(dev), ret);
 650         }
 651         /*
 652          * Ignore errors returned by ->probe so that the next driver can try
 653          * its luck.
 654          */
 655         ret = 0;
 656 done:
 657         atomic_dec(&probe_count);
 658         wake_up_all(&probe_waitqueue);
 659         return ret;
 660 }
 661
 662 /*
 663  * For initcall_debug, show the driver probe time.
 664  */
 665 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 666 {
 667         ktime_t calltime, rettime;
 668         int ret;
 669
 670         calltime = ktime_get();
 671         ret = really_probe(dev, drv);
 672         rettime = ktime_get();
 673         pr_debug("probe of %s returned %d after %lld usecs\n",
 674                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 675         return ret;
 676 }
 677
 678 /**
 679  * driver_probe_done
 680  * Determine if the probe sequence is finished or not.
 681  *
 682  * Should somehow figure out how to use a semaphore, not an atomic variable...
 683  */
 684 int driver_probe_done(void)
 685 {
 686         int local_probe_count = atomic_read(&probe_count);
 687
 688         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 689         if (local_probe_count)
 690                 return -EBUSY;
 691         return 0;
 692 }
 693
 694 /**
 695  * wait_for_device_probe
 696  * Wait for device probing to be completed.
 697  */
 698 void wait_for_device_probe(void)
 699 {
 700         /* wait for probe timeout */
 701         wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout);
 702
 703         /* wait for the deferred probe workqueue to finish */
 704         flush_work(&deferred_probe_work);
 705
 706         /* wait for the known devices to complete their probing */
 707         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 708         async_synchronize_full();
 709 }
 710 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 711
 712 /**
 713  * driver_probe_device - attempt to bind device & driver together
 714  * @drv: driver to bind a device to
 715  * @dev: device to try to bind to the driver
 716  *
 717  * This function returns -ENODEV if the device is not registered,
 718  * 1 if the device is bound successfully and 0 otherwise.
 719  *
 720  * This function must be called with @dev lock held.  When called for a
 721  * USB interface, @dev->parent lock must be held as well.
 722  *
 723  * If the device has a parent, runtime-resume the parent before driver probing.
 724  */
 725 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 726 {
 727         int ret = 0;
 728
 729         if (!device_is_registered(dev))
 730                 return -ENODEV;
 731
 732         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 733                  drv->bus->name, __func__, dev_name(dev), drv->name);
 734
 735         pm_runtime_get_suppliers(dev);
 736         if (dev->parent)
 737                 pm_runtime_get_sync(dev->parent);
 738
 739         pm_runtime_barrier(dev);
 740         if (initcall_debug)
 741                 ret = really_probe_debug(dev, drv);
 742         else
 743                 ret = really_probe(dev, drv);
 744         pm_request_idle(dev);
 745
 746         if (dev->parent)
 747                 pm_runtime_put(dev->parent);
 748
 749         pm_runtime_put_suppliers(dev);
 750         return ret;
 751 }
 752
 753 static inline bool cmdline_requested_async_probing(const char *drv_name)
 754 {
 755         return parse_option_str(async_probe_drv_names, drv_name);
 756 }
 757
 758 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 759 static int __init save_async_options(char *buf)
 760 {
 761         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 762                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 763
 764         strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 765         return 0;
 766 }
 767 __setup("driver_async_probe=", save_async_options);
 768
 769 bool driver_allows_async_probing(struct device_driver *drv)
 770 {
 771         switch (drv->probe_type) {
 772         case PROBE_PREFER_ASYNCHRONOUS:
 773                 return true;
 774
 775         case PROBE_FORCE_SYNCHRONOUS:
 776                 return false;
 777
 778         default:
 779                 if (cmdline_requested_async_probing(drv->name))
 780                         return true;
 781
 782                 if (module_requested_async_probing(drv->owner))
 783                         return true;
 784
 785                 return false;
 786         }
 787 }
 788
 789 struct device_attach_data {
 790         struct device *dev;
 791
 792         /*
 793          * Indicates whether we are are considering asynchronous probing or
 794          * not. Only initial binding after device or driver registration
 795          * (including deferral processing) may be done asynchronously, the
 796          * rest is always synchronous, as we expect it is being done by
 797          * request from userspace.
 798          */
 799         bool check_async;
 800
 801         /*
 802          * Indicates if we are binding synchronous or asynchronous drivers.
 803          * When asynchronous probing is enabled we'll execute 2 passes
 804          * over drivers: first pass doing synchronous probing and second
 805          * doing asynchronous probing (if synchronous did not succeed -
 806          * most likely because there was no driver requiring synchronous
 807          * probing - and we found asynchronous driver during first pass).
 808          * The 2 passes are done because we can't shoot asynchronous
 809          * probe for given device and driver from bus_for_each_drv() since
 810          * driver pointer is not guaranteed to stay valid once
 811          * bus_for_each_drv() iterates to the next driver on the bus.
 812          */
 813         bool want_async;
 814
 815         /*
 816          * We'll set have_async to 'true' if, while scanning for matching
 817          * driver, we'll encounter one that requests asynchronous probing.
 818          */
 819         bool have_async;
 820 };
 821
 822 static int __device_attach_driver(struct device_driver *drv, void *_data)
 823 {
 824         struct device_attach_data *data = _data;
 825         struct device *dev = data->dev;
 826         bool async_allowed;
 827         int ret;
 828
 829         ret = driver_match_device(drv, dev);
 830         if (ret == 0) {
 831                 /* no match */
 832                 return 0;
 833         } else if (ret == -EPROBE_DEFER) {
 834                 dev_dbg(dev, "Device match requests probe deferral\n");
 835                 driver_deferred_probe_add(dev);
 836         } else if (ret < 0) {
 837                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 838                 return ret;
 839         } /* ret > 0 means positive match */
 840
 841         async_allowed = driver_allows_async_probing(drv);
 842
 843         if (async_allowed)
 844                 data->have_async = true;
 845
 846         if (data->check_async && async_allowed != data->want_async)
 847                 return 0;
 848
 849         return driver_probe_device(drv, dev);
 850 }
 851
 852 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 853 {
 854         struct device *dev = _dev;
 855         struct device_attach_data data = {
 856                 .dev            = dev,
 857                 .check_async    = true,
 858                 .want_async     = true,
 859         };
 860
 861         device_lock(dev);
 862
 863         /*
 864          * Check if device has already been removed or claimed. This may
 865          * happen with driver loading, device discovery/registration,
 866          * and deferred probe processing happens all at once with
 867          * multiple threads.
 868          */
 869         if (dev->p->dead || dev->driver)
 870                 goto out_unlock;
 871
 872         if (dev->parent)
 873                 pm_runtime_get_sync(dev->parent);
 874
 875         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 876         dev_dbg(dev, "async probe completed\n");
 877
 878         pm_request_idle(dev);
 879
 880         if (dev->parent)
 881                 pm_runtime_put(dev->parent);
 882 out_unlock:
 883         device_unlock(dev);
 884
 885         put_device(dev);
 886 }
 887
 888 static int __device_attach(struct device *dev, bool allow_async)
 889 {
 890         int ret = 0;
 891
 892         device_lock(dev);
 893         if (dev->p->dead) {
 894                 goto out_unlock;
 895         } else if (dev->driver) {
 896                 if (device_is_bound(dev)) {
 897                         ret = 1;
 898                         goto out_unlock;
 899                 }
 900                 ret = device_bind_driver(dev);
 901                 if (ret == 0)
 902                         ret = 1;
 903                 else {
 904                         dev->driver = NULL;
 905                         ret = 0;
 906                 }
 907         } else {
 908                 struct device_attach_data data = {
 909                         .dev = dev,
 910                         .check_async = allow_async,
 911                         .want_async = false,
 912                 };
 913
 914                 if (dev->parent)
 915                         pm_runtime_get_sync(dev->parent);
 916
 917                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 918                                         __device_attach_driver);
 919                 if (!ret && allow_async && data.have_async) {
 920                         /*
 921                          * If we could not find appropriate driver
 922                          * synchronously and we are allowed to do
 923                          * async probes and there are drivers that
 924                          * want to probe asynchronously, we'll
 925                          * try them.
 926                          */
 927                         dev_dbg(dev, "scheduling asynchronous probe\n");
 928                         get_device(dev);
 929                         async_schedule_dev(__device_attach_async_helper, dev);
 930                 } else {
 931                         pm_request_idle(dev);
 932                 }
 933
 934                 if (dev->parent)
 935                         pm_runtime_put(dev->parent);
 936         }
 937 out_unlock:
 938         device_unlock(dev);
 939         return ret;
 940 }
 941
 942 /**
 943  * device_attach - try to attach device to a driver.
 944  * @dev: device.
 945  *
 946  * Walk the list of drivers that the bus has and call
 947  * driver_probe_device() for each pair. If a compatible
 948  * pair is found, break out and return.
 949  *
 950  * Returns 1 if the device was bound to a driver;
 951  * 0 if no matching driver was found;
 952  * -ENODEV if the device is not registered.
 953  *
 954  * When called for a USB interface, @dev->parent lock must be held.
 955  */
 956 int device_attach(struct device *dev)
 957 {
 958         return __device_attach(dev, false);
 959 }
 960 EXPORT_SYMBOL_GPL(device_attach);
 961
 962 void device_initial_probe(struct device *dev)
 963 {
 964         __device_attach(dev, true);
 965 }
 966
 967 /*
 968  * __device_driver_lock - acquire locks needed to manipulate dev->drv
 969  * @dev: Device we will update driver info for
 970  * @parent: Parent device. Needed if the bus requires parent lock
 971  *
 972  * This function will take the required locks for manipulating dev->drv.
 973  * Normally this will just be the @dev lock, but when called for a USB
 974  * interface, @parent lock will be held as well.
 975  */
 976 static void __device_driver_lock(struct device *dev, struct device *parent)
 977 {
 978         if (parent && dev->bus->need_parent_lock)
 979                 device_lock(parent);
 980         device_lock(dev);
 981 }
 982
 983 /*
 984  * __device_driver_unlock - release locks needed to manipulate dev->drv
 985  * @dev: Device we will update driver info for
 986  * @parent: Parent device. Needed if the bus requires parent lock
 987  *
 988  * This function will release the required locks for manipulating dev->drv.
 989  * Normally this will just be the the @dev lock, but when called for a
 990  * USB interface, @parent lock will be released as well.
 991  */
 992 static void __device_driver_unlock(struct device *dev, struct device *parent)
 993 {
 994         device_unlock(dev);
 995         if (parent && dev->bus->need_parent_lock)
 996                 device_unlock(parent);
 997 }
 998
 999 /**
1000  * device_driver_attach - attach a specific driver to a specific device
1001  * @drv: Driver to attach
1002  * @dev: Device to attach it to
1003  *
1004  * Manually attach driver to a device. Will acquire both @dev lock and
1005  * @dev->parent lock if needed.
1006  */
1007 int device_driver_attach(struct device_driver *drv, struct device *dev)
1008 {
1009         int ret = 0;
1010
1011         __device_driver_lock(dev, dev->parent);
1012
1013         /*
1014          * If device has been removed or someone has already successfully
1015          * bound a driver before us just skip the driver probe call.
1016          */
1017         if (!dev->p->dead && !dev->driver)
1018                 ret = driver_probe_device(drv, dev);
1019
1020         __device_driver_unlock(dev, dev->parent);
1021
1022         return ret;
1023 }
1024
1025 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1026 {
1027         struct device *dev = _dev;
1028         struct device_driver *drv;
1029         int ret = 0;
1030
1031         __device_driver_lock(dev, dev->parent);
1032
1033         drv = dev->p->async_driver;
1034
1035         /*
1036          * If device has been removed or someone has already successfully
1037          * bound a driver before us just skip the driver probe call.
1038          */
1039         if (!dev->p->dead && !dev->driver)
1040                 ret = driver_probe_device(drv, dev);
1041
1042         __device_driver_unlock(dev, dev->parent);
1043
1044         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1045
1046         put_device(dev);
1047 }
1048
1049 static int __driver_attach(struct device *dev, void *data)
1050 {
1051         struct device_driver *drv = data;
1052         int ret;
1053
1054         /*
1055          * Lock device and try to bind to it. We drop the error
1056          * here and always return 0, because we need to keep trying
1057          * to bind to devices and some drivers will return an error
1058          * simply if it didn't support the device.
1059          *
1060          * driver_probe_device() will spit a warning if there
1061          * is an error.
1062          */
1063
1064         ret = driver_match_device(drv, dev);
1065         if (ret == 0) {
1066                 /* no match */
1067                 return 0;
1068         } else if (ret == -EPROBE_DEFER) {
1069                 dev_dbg(dev, "Device match requests probe deferral\n");
1070                 driver_deferred_probe_add(dev);
1071         } else if (ret < 0) {
1072                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1073                 return ret;
1074         } /* ret > 0 means positive match */
1075
1076         if (driver_allows_async_probing(drv)) {
1077                 /*
1078                  * Instead of probing the device synchronously we will
1079                  * probe it asynchronously to allow for more parallelism.
1080                  *
1081                  * We only take the device lock here in order to guarantee
1082                  * that the dev->driver and async_driver fields are protected
1083                  */
1084                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1085                 device_lock(dev);
1086                 if (!dev->driver) {
1087                         get_device(dev);
1088                         dev->p->async_driver = drv;
1089                         async_schedule_dev(__driver_attach_async_helper, dev);
1090                 }
1091                 device_unlock(dev);
1092                 return 0;
1093         }
1094
1095         device_driver_attach(drv, dev);
1096
1097         return 0;
1098 }
1099
1100 /**
1101  * driver_attach - try to bind driver to devices.
1102  * @drv: driver.
1103  *
1104  * Walk the list of devices that the bus has on it and try to
1105  * match the driver with each one.  If driver_probe_device()
1106  * returns 0 and the @dev->driver is set, we've found a
1107  * compatible pair.
1108  */
1109 int driver_attach(struct device_driver *drv)
1110 {
1111         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1112 }
1113 EXPORT_SYMBOL_GPL(driver_attach);
1114
1115 /*
1116  * __device_release_driver() must be called with @dev lock held.
1117  * When called for a USB interface, @dev->parent lock must be held as well.
1118  */
1119 static void __device_release_driver(struct device *dev, struct device *parent)
1120 {
1121         struct device_driver *drv;
1122
1123         drv = dev->driver;
1124         if (drv) {
1125                 pm_runtime_get_sync(dev);
1126
1127                 while (device_links_busy(dev)) {
1128                         __device_driver_unlock(dev, parent);
1129
1130                         device_links_unbind_consumers(dev);
1131
1132                         __device_driver_lock(dev, parent);
1133                         /*
1134                          * A concurrent invocation of the same function might
1135                          * have released the driver successfully while this one
1136                          * was waiting, so check for that.
1137                          */
1138                         if (dev->driver != drv) {
1139                                 pm_runtime_put(dev);
1140                                 return;
1141                         }
1142                 }
1143
1144                 driver_sysfs_remove(dev);
1145
1146                 if (dev->bus)
1147                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1148                                                      BUS_NOTIFY_UNBIND_DRIVER,
1149                                                      dev);
1150
1151                 pm_runtime_put_sync(dev);
1152
1153                 device_remove_file(dev, &dev_attr_state_synced);
1154                 device_remove_groups(dev, drv->dev_groups);
1155
1156                 if (dev->bus && dev->bus->remove)
1157                         dev->bus->remove(dev);
1158                 else if (drv->remove)
1159                         drv->remove(dev);
1160
1161                 device_links_driver_cleanup(dev);
1162
1163                 devres_release_all(dev);
1164                 arch_teardown_dma_ops(dev);
1165                 dev->driver = NULL;
1166                 dev_set_drvdata(dev, NULL);
1167                 if (dev->pm_domain && dev->pm_domain->dismiss)
1168                         dev->pm_domain->dismiss(dev);
1169                 pm_runtime_reinit(dev);
1170                 dev_pm_set_driver_flags(dev, 0);
1171
1172                 klist_remove(&dev->p->knode_driver);
1173                 device_pm_check_callbacks(dev);
1174                 if (dev->bus)
1175                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1176                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1177                                                      dev);
1178
1179                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1180         }
1181 }
1182
1183 void device_release_driver_internal(struct device *dev,
1184                                     struct device_driver *drv,
1185                                     struct device *parent)
1186 {
1187         __device_driver_lock(dev, parent);
1188
1189         if (!drv || drv == dev->driver)
1190                 __device_release_driver(dev, parent);
1191
1192         __device_driver_unlock(dev, parent);
1193 }
1194
1195 /**
1196  * device_release_driver - manually detach device from driver.
1197  * @dev: device.
1198  *
1199  * Manually detach device from driver.
1200  * When called for a USB interface, @dev->parent lock must be held.
1201  *
1202  * If this function is to be called with @dev->parent lock held, ensure that
1203  * the device's consumers are unbound in advance or that their locks can be
1204  * acquired under the @dev->parent lock.
1205  */
1206 void device_release_driver(struct device *dev)
1207 {
1208         /*
1209          * If anyone calls device_release_driver() recursively from
1210          * within their ->remove callback for the same device, they
1211          * will deadlock right here.
1212          */
1213         device_release_driver_internal(dev, NULL, NULL);
1214 }
1215 EXPORT_SYMBOL_GPL(device_release_driver);
1216
1217 /**
1218  * device_driver_detach - detach driver from a specific device
1219  * @dev: device to detach driver from
1220  *
1221  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1222  * lock if needed.
1223  */
1224 void device_driver_detach(struct device *dev)
1225 {
1226         device_release_driver_internal(dev, NULL, dev->parent);
1227 }
1228
1229 /**
1230  * driver_detach - detach driver from all devices it controls.
1231  * @drv: driver.
1232  */
1233 void driver_detach(struct device_driver *drv)
1234 {
1235         struct device_private *dev_prv;
1236         struct device *dev;
1237
1238         if (driver_allows_async_probing(drv))
1239                 async_synchronize_full();
1240
1241         for (;;) {
1242                 spin_lock(&drv->p->klist_devices.k_lock);
1243                 if (list_empty(&drv->p->klist_devices.k_list)) {
1244                         spin_unlock(&drv->p->klist_devices.k_lock);
1245                         break;
1246                 }
1247                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1248                                      struct device_private,
1249                                      knode_driver.n_node);
1250                 dev = dev_prv->device;
1251                 get_device(dev);
1252                 spin_unlock(&drv->p->klist_devices.k_lock);
1253                 device_release_driver_internal(dev, drv, dev->parent);
1254                 put_device(dev);
1255         }
1256 }