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 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
  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  */
  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
 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
 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  */
 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  */
 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  */
 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  */
 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  */
 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
 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 static void deferred_probe_timeout_work_func(struct work_struct *work)
 278 {
 279         struct device_private *p;
 280
 281         fw_devlink_drivers_done();
 282
 283         driver_deferred_probe_trigger();
 284         flush_work(&deferred_probe_work);
 285
 286         mutex_lock(&deferred_probe_mutex);
 287         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 288                 dev_info(p->device, "deferred probe pending\n");
 289         mutex_unlock(&deferred_probe_mutex);
 290 }
 291 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 292
 293 void deferred_probe_extend_timeout(void)
 294 {
 295         /*
 296          * If the work hasn't been queued yet or if the work expired, don't
 297          * start a new one.
 298          */
 299         if (cancel_delayed_work(&deferred_probe_timeout_work)) {
 300                 schedule_delayed_work(&deferred_probe_timeout_work,
 301                                 driver_deferred_probe_timeout * HZ);
 302                 pr_debug("Extended deferred probe timeout by %d secs\n",
 303                                         driver_deferred_probe_timeout);
 304         }
 305 }
 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         debugfs_create_file("devices_deferred", 0444, NULL, NULL,
 317                             &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         if (!IS_ENABLED(CONFIG_MODULES))
 326                 fw_devlink_drivers_done();
 327
 328         /*
 329          * Trigger deferred probe again, this time we won't defer anything
 330          * that is optional
 331          */
 332         driver_deferred_probe_trigger();
 333         flush_work(&deferred_probe_work);
 334
 335         if (driver_deferred_probe_timeout > 0) {
 336                 schedule_delayed_work(&deferred_probe_timeout_work,
 337                         driver_deferred_probe_timeout * HZ);
 338         }
 339         return 0;
 340 }
 341 late_initcall(deferred_probe_initcall);
 342
 343 static void __exit deferred_probe_exit(void)
 344 {
 345         debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
 346 }
 347 __exitcall(deferred_probe_exit);
 348
 349 /**
 350  * device_is_bound() - Check if device is bound to a driver
 351  * @dev: device to check
 352  *
 353  * Returns true if passed device has already finished probing successfully
 354  * against a driver.
 355  *
 356  * This function must be called with the device lock held.
 357  */
 358 bool device_is_bound(struct device *dev)
 359 {
 360         return dev->p && klist_node_attached(&dev->p->knode_driver);
 361 }
 362
 363 static void driver_bound(struct device *dev)
 364 {
 365         if (device_is_bound(dev)) {
 366                 pr_warn("%s: device %s already bound\n",
 367                         __func__, kobject_name(&dev->kobj));
 368                 return;
 369         }
 370
 371         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 372                  __func__, dev_name(dev));
 373
 374         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 375         device_links_driver_bound(dev);
 376
 377         device_pm_check_callbacks(dev);
 378
 379         /*
 380          * Make sure the device is no longer in one of the deferred lists and
 381          * kick off retrying all pending devices
 382          */
 383         driver_deferred_probe_del(dev);
 384         driver_deferred_probe_trigger();
 385
 386         if (dev->bus)
 387                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 388                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 389
 390         kobject_uevent(&dev->kobj, KOBJ_BIND);
 391 }
 392
 393 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 394                             const char *buf, size_t count)
 395 {
 396         device_lock(dev);
 397         dev->driver->coredump(dev);
 398         device_unlock(dev);
 399
 400         return count;
 401 }
 402 static DEVICE_ATTR_WO(coredump);
 403
 404 static int driver_sysfs_add(struct device *dev)
 405 {
 406         int ret;
 407
 408         if (dev->bus)
 409                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 410                                              BUS_NOTIFY_BIND_DRIVER, dev);
 411
 412         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 413                                 kobject_name(&dev->kobj));
 414         if (ret)
 415                 goto fail;
 416
 417         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 418                                 "driver");
 419         if (ret)
 420                 goto rm_dev;
 421
 422         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 423                 return 0;
 424
 425         ret = device_create_file(dev, &dev_attr_coredump);
 426         if (!ret)
 427                 return 0;
 428
 429         sysfs_remove_link(&dev->kobj, "driver");
 430
 431 rm_dev:
 432         sysfs_remove_link(&dev->driver->p->kobj,
 433                           kobject_name(&dev->kobj));
 434
 435 fail:
 436         return ret;
 437 }
 438
 439 static void driver_sysfs_remove(struct device *dev)
 440 {
 441         struct device_driver *drv = dev->driver;
 442
 443         if (drv) {
 444                 if (drv->coredump)
 445                         device_remove_file(dev, &dev_attr_coredump);
 446                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 447                 sysfs_remove_link(&dev->kobj, "driver");
 448         }
 449 }
 450
 451 /**
 452  * device_bind_driver - bind a driver to one device.
 453  * @dev: device.
 454  *
 455  * Allow manual attachment of a driver to a device.
 456  * Caller must have already set @dev->driver.
 457  *
 458  * Note that this does not modify the bus reference count.
 459  * Please verify that is accounted for before calling this.
 460  * (It is ok to call with no other effort from a driver's probe() method.)
 461  *
 462  * This function must be called with the device lock held.
 463  *
 464  * Callers should prefer to use device_driver_attach() instead.
 465  */
 466 int device_bind_driver(struct device *dev)
 467 {
 468         int ret;
 469
 470         ret = driver_sysfs_add(dev);
 471         if (!ret) {
 472                 device_links_force_bind(dev);
 473                 driver_bound(dev);
 474         }
 475         else if (dev->bus)
 476                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 477                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 478         return ret;
 479 }
 480 EXPORT_SYMBOL_GPL(device_bind_driver);
 481
 482 static atomic_t probe_count = ATOMIC_INIT(0);
 483 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 484
 485 static ssize_t state_synced_show(struct device *dev,
 486                                  struct device_attribute *attr, char *buf)
 487 {
 488         bool val;
 489
 490         device_lock(dev);
 491         val = dev->state_synced;
 492         device_unlock(dev);
 493
 494         return sysfs_emit(buf, "%u\n", val);
 495 }
 496 static DEVICE_ATTR_RO(state_synced);
 497
 498 static void device_unbind_cleanup(struct device *dev)
 499 {
 500         devres_release_all(dev);
 501         arch_teardown_dma_ops(dev);
 502         kfree(dev->dma_range_map);
 503         dev->dma_range_map = NULL;
 504         dev->driver = NULL;
 505         dev_set_drvdata(dev, NULL);
 506         if (dev->pm_domain && dev->pm_domain->dismiss)
 507                 dev->pm_domain->dismiss(dev);
 508         pm_runtime_reinit(dev);
 509         dev_pm_set_driver_flags(dev, 0);
 510 }
 511
 512 static void device_remove(struct device *dev)
 513 {
 514         device_remove_file(dev, &dev_attr_state_synced);
 515         device_remove_groups(dev, dev->driver->dev_groups);
 516
 517         if (dev->bus && dev->bus->remove)
 518                 dev->bus->remove(dev);
 519         else if (dev->driver->remove)
 520                 dev->driver->remove(dev);
 521 }
 522
 523 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 524 {
 525         int ret = 0;
 526
 527         if (dev->bus->probe)
 528                 ret = dev->bus->probe(dev);
 529         else if (drv->probe)
 530                 ret = drv->probe(dev);
 531
 532         switch (ret) {
 533         case 0:
 534                 break;
 535         case -EPROBE_DEFER:
 536                 /* Driver requested deferred probing */
 537                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 538                 break;
 539         case -ENODEV:
 540         case -ENXIO:
 541                 pr_debug("%s: probe of %s rejects match %d\n",
 542                          drv->name, dev_name(dev), ret);
 543                 break;
 544         default:
 545                 /* driver matched but the probe failed */
 546                 pr_warn("%s: probe of %s failed with error %d\n",
 547                         drv->name, dev_name(dev), ret);
 548                 break;
 549         }
 550
 551         return ret;
 552 }
 553
 554 static int really_probe(struct device *dev, struct device_driver *drv)
 555 {
 556         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 557                            !drv->suppress_bind_attrs;
 558         int ret, link_ret;
 559
 560         if (defer_all_probes) {
 561                 /*
 562                  * Value of defer_all_probes can be set only by
 563                  * device_block_probing() which, in turn, will call
 564                  * wait_for_device_probe() right after that to avoid any races.
 565                  */
 566                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 567                 return -EPROBE_DEFER;
 568         }
 569
 570         link_ret = device_links_check_suppliers(dev);
 571         if (link_ret == -EPROBE_DEFER)
 572                 return link_ret;
 573
 574         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 575                  drv->bus->name, __func__, drv->name, dev_name(dev));
 576         if (!list_empty(&dev->devres_head)) {
 577                 dev_crit(dev, "Resources present before probing\n");
 578                 ret = -EBUSY;
 579                 goto done;
 580         }
 581
 582 re_probe:
 583         dev->driver = drv;
 584
 585         /* If using pinctrl, bind pins now before probing */
 586         ret = pinctrl_bind_pins(dev);
 587         if (ret)
 588                 goto pinctrl_bind_failed;
 589
 590         if (dev->bus->dma_configure) {
 591                 ret = dev->bus->dma_configure(dev);
 592                 if (ret)
 593                         goto pinctrl_bind_failed;
 594         }
 595
 596         ret = driver_sysfs_add(dev);
 597         if (ret) {
 598                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 599                        __func__, dev_name(dev));
 600                 goto sysfs_failed;
 601         }
 602
 603         if (dev->pm_domain && dev->pm_domain->activate) {
 604                 ret = dev->pm_domain->activate(dev);
 605                 if (ret)
 606                         goto probe_failed;
 607         }
 608
 609         ret = call_driver_probe(dev, drv);
 610         if (ret) {
 611                 /*
 612                  * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
 613                  * device might actually probe properly once some of its missing
 614                  * suppliers have probed. So, treat this as if the driver
 615                  * returned -EPROBE_DEFER.
 616                  */
 617                 if (link_ret == -EAGAIN)
 618                         ret = -EPROBE_DEFER;
 619
 620                 /*
 621                  * Return probe errors as positive values so that the callers
 622                  * can distinguish them from other errors.
 623                  */
 624                 ret = -ret;
 625                 goto probe_failed;
 626         }
 627
 628         ret = device_add_groups(dev, drv->dev_groups);
 629         if (ret) {
 630                 dev_err(dev, "device_add_groups() failed\n");
 631                 goto dev_groups_failed;
 632         }
 633
 634         if (dev_has_sync_state(dev)) {
 635                 ret = device_create_file(dev, &dev_attr_state_synced);
 636                 if (ret) {
 637                         dev_err(dev, "state_synced sysfs add failed\n");
 638                         goto dev_sysfs_state_synced_failed;
 639                 }
 640         }
 641
 642         if (test_remove) {
 643                 test_remove = false;
 644
 645                 device_remove(dev);
 646                 driver_sysfs_remove(dev);
 647                 device_unbind_cleanup(dev);
 648
 649                 goto re_probe;
 650         }
 651
 652         pinctrl_init_done(dev);
 653
 654         if (dev->pm_domain && dev->pm_domain->sync)
 655                 dev->pm_domain->sync(dev);
 656
 657         driver_bound(dev);
 658         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 659                  drv->bus->name, __func__, dev_name(dev), drv->name);
 660         goto done;
 661
 662 dev_sysfs_state_synced_failed:
 663 dev_groups_failed:
 664         device_remove(dev);
 665 probe_failed:
 666         driver_sysfs_remove(dev);
 667 sysfs_failed:
 668         if (dev->bus)
 669                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 670                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 671         if (dev->bus && dev->bus->dma_cleanup)
 672                 dev->bus->dma_cleanup(dev);
 673 pinctrl_bind_failed:
 674         device_links_no_driver(dev);
 675         device_unbind_cleanup(dev);
 676 done:
 677         return ret;
 678 }
 679
 680 /*
 681  * For initcall_debug, show the driver probe time.
 682  */
 683 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 684 {
 685         ktime_t calltime, rettime;
 686         int ret;
 687
 688         calltime = ktime_get();
 689         ret = really_probe(dev, drv);
 690         rettime = ktime_get();
 691         pr_debug("probe of %s returned %d after %lld usecs\n",
 692                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 693         return ret;
 694 }
 695
 696 /**
 697  * driver_probe_done
 698  * Determine if the probe sequence is finished or not.
 699  *
 700  * Should somehow figure out how to use a semaphore, not an atomic variable...
 701  */
 702 int driver_probe_done(void)
 703 {
 704         int local_probe_count = atomic_read(&probe_count);
 705
 706         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 707         if (local_probe_count)
 708                 return -EBUSY;
 709         return 0;
 710 }
 711
 712 /**
 713  * wait_for_device_probe
 714  * Wait for device probing to be completed.
 715  */
 716 void wait_for_device_probe(void)
 717 {
 718         /* wait for the deferred probe workqueue to finish */
 719         flush_work(&deferred_probe_work);
 720
 721         /* wait for the known devices to complete their probing */
 722         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 723         async_synchronize_full();
 724 }
 725 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 726
 727 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 728 {
 729         int ret = 0;
 730
 731         if (dev->p->dead || !device_is_registered(dev))
 732                 return -ENODEV;
 733         if (dev->driver)
 734                 return -EBUSY;
 735
 736         dev->can_match = true;
 737         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 738                  drv->bus->name, __func__, dev_name(dev), drv->name);
 739
 740         pm_runtime_get_suppliers(dev);
 741         if (dev->parent)
 742                 pm_runtime_get_sync(dev->parent);
 743
 744         pm_runtime_barrier(dev);
 745         if (initcall_debug)
 746                 ret = really_probe_debug(dev, drv);
 747         else
 748                 ret = really_probe(dev, drv);
 749         pm_request_idle(dev);
 750
 751         if (dev->parent)
 752                 pm_runtime_put(dev->parent);
 753
 754         pm_runtime_put_suppliers(dev);
 755         return ret;
 756 }
 757
 758 /**
 759  * driver_probe_device - attempt to bind device & driver together
 760  * @drv: driver to bind a device to
 761  * @dev: device to try to bind to the driver
 762  *
 763  * This function returns -ENODEV if the device is not registered, -EBUSY if it
 764  * already has a driver, 0 if the device is bound successfully and a positive
 765  * (inverted) error code for failures from the ->probe method.
 766  *
 767  * This function must be called with @dev lock held.  When called for a
 768  * USB interface, @dev->parent lock must be held as well.
 769  *
 770  * If the device has a parent, runtime-resume the parent before driver probing.
 771  */
 772 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 773 {
 774         int trigger_count = atomic_read(&deferred_trigger_count);
 775         int ret;
 776
 777         atomic_inc(&probe_count);
 778         ret = __driver_probe_device(drv, dev);
 779         if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
 780                 driver_deferred_probe_add(dev);
 781
 782                 /*
 783                  * Did a trigger occur while probing? Need to re-trigger if yes
 784                  */
 785                 if (trigger_count != atomic_read(&deferred_trigger_count) &&
 786                     !defer_all_probes)
 787                         driver_deferred_probe_trigger();
 788         }
 789         atomic_dec(&probe_count);
 790         wake_up_all(&probe_waitqueue);
 791         return ret;
 792 }
 793
 794 static inline bool cmdline_requested_async_probing(const char *drv_name)
 795 {
 796         bool async_drv;
 797
 798         async_drv = parse_option_str(async_probe_drv_names, drv_name);
 799
 800         return (async_probe_default != async_drv);
 801 }
 802
 803 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 804 static int __init save_async_options(char *buf)
 805 {
 806         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 807                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 808
 809         strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 810         async_probe_default = parse_option_str(async_probe_drv_names, "*");
 811
 812         return 1;
 813 }
 814 __setup("driver_async_probe=", save_async_options);
 815
 816 bool driver_allows_async_probing(struct device_driver *drv)
 817 {
 818         switch (drv->probe_type) {
 819         case PROBE_PREFER_ASYNCHRONOUS:
 820                 return true;
 821
 822         case PROBE_FORCE_SYNCHRONOUS:
 823                 return false;
 824
 825         default:
 826                 if (cmdline_requested_async_probing(drv->name))
 827                         return true;
 828
 829                 if (module_requested_async_probing(drv->owner))
 830                         return true;
 831
 832                 return false;
 833         }
 834 }
 835
 836 struct device_attach_data {
 837         struct device *dev;
 838
 839         /*
 840          * Indicates whether we are considering asynchronous probing or
 841          * not. Only initial binding after device or driver registration
 842          * (including deferral processing) may be done asynchronously, the
 843          * rest is always synchronous, as we expect it is being done by
 844          * request from userspace.
 845          */
 846         bool check_async;
 847
 848         /*
 849          * Indicates if we are binding synchronous or asynchronous drivers.
 850          * When asynchronous probing is enabled we'll execute 2 passes
 851          * over drivers: first pass doing synchronous probing and second
 852          * doing asynchronous probing (if synchronous did not succeed -
 853          * most likely because there was no driver requiring synchronous
 854          * probing - and we found asynchronous driver during first pass).
 855          * The 2 passes are done because we can't shoot asynchronous
 856          * probe for given device and driver from bus_for_each_drv() since
 857          * driver pointer is not guaranteed to stay valid once
 858          * bus_for_each_drv() iterates to the next driver on the bus.
 859          */
 860         bool want_async;
 861
 862         /*
 863          * We'll set have_async to 'true' if, while scanning for matching
 864          * driver, we'll encounter one that requests asynchronous probing.
 865          */
 866         bool have_async;
 867 };
 868
 869 static int __device_attach_driver(struct device_driver *drv, void *_data)
 870 {
 871         struct device_attach_data *data = _data;
 872         struct device *dev = data->dev;
 873         bool async_allowed;
 874         int ret;
 875
 876         ret = driver_match_device(drv, dev);
 877         if (ret == 0) {
 878                 /* no match */
 879                 return 0;
 880         } else if (ret == -EPROBE_DEFER) {
 881                 dev_dbg(dev, "Device match requests probe deferral\n");
 882                 dev->can_match = true;
 883                 driver_deferred_probe_add(dev);
 884         } else if (ret < 0) {
 885                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 886                 return ret;
 887         } /* ret > 0 means positive match */
 888
 889         async_allowed = driver_allows_async_probing(drv);
 890
 891         if (async_allowed)
 892                 data->have_async = true;
 893
 894         if (data->check_async && async_allowed != data->want_async)
 895                 return 0;
 896
 897         /*
 898          * Ignore errors returned by ->probe so that the next driver can try
 899          * its luck.
 900          */
 901         ret = driver_probe_device(drv, dev);
 902         if (ret < 0)
 903                 return ret;
 904         return ret == 0;
 905 }
 906
 907 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 908 {
 909         struct device *dev = _dev;
 910         struct device_attach_data data = {
 911                 .dev            = dev,
 912                 .check_async    = true,
 913                 .want_async     = true,
 914         };
 915
 916         device_lock(dev);
 917
 918         /*
 919          * Check if device has already been removed or claimed. This may
 920          * happen with driver loading, device discovery/registration,
 921          * and deferred probe processing happens all at once with
 922          * multiple threads.
 923          */
 924         if (dev->p->dead || dev->driver)
 925                 goto out_unlock;
 926
 927         if (dev->parent)
 928                 pm_runtime_get_sync(dev->parent);
 929
 930         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 931         dev_dbg(dev, "async probe completed\n");
 932
 933         pm_request_idle(dev);
 934
 935         if (dev->parent)
 936                 pm_runtime_put(dev->parent);
 937 out_unlock:
 938         device_unlock(dev);
 939
 940         put_device(dev);
 941 }
 942
 943 static int __device_attach(struct device *dev, bool allow_async)
 944 {
 945         int ret = 0;
 946         bool async = false;
 947
 948         device_lock(dev);
 949         if (dev->p->dead) {
 950                 goto out_unlock;
 951         } else if (dev->driver) {
 952                 if (device_is_bound(dev)) {
 953                         ret = 1;
 954                         goto out_unlock;
 955                 }
 956                 ret = device_bind_driver(dev);
 957                 if (ret == 0)
 958                         ret = 1;
 959                 else {
 960                         dev->driver = NULL;
 961                         ret = 0;
 962                 }
 963         } else {
 964                 struct device_attach_data data = {
 965                         .dev = dev,
 966                         .check_async = allow_async,
 967                         .want_async = false,
 968                 };
 969
 970                 if (dev->parent)
 971                         pm_runtime_get_sync(dev->parent);
 972
 973                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 974                                         __device_attach_driver);
 975                 if (!ret && allow_async && data.have_async) {
 976                         /*
 977                          * If we could not find appropriate driver
 978                          * synchronously and we are allowed to do
 979                          * async probes and there are drivers that
 980                          * want to probe asynchronously, we'll
 981                          * try them.
 982                          */
 983                         dev_dbg(dev, "scheduling asynchronous probe\n");
 984                         get_device(dev);
 985                         async = true;
 986                 } else {
 987                         pm_request_idle(dev);
 988                 }
 989
 990                 if (dev->parent)
 991                         pm_runtime_put(dev->parent);
 992         }
 993 out_unlock:
 994         device_unlock(dev);
 995         if (async)
 996                 async_schedule_dev(__device_attach_async_helper, dev);
 997         return ret;
 998 }
 999
1000 /**
1001  * device_attach - try to attach device to a driver.
1002  * @dev: device.
1003  *
1004  * Walk the list of drivers that the bus has and call
1005  * driver_probe_device() for each pair. If a compatible
1006  * pair is found, break out and return.
1007  *
1008  * Returns 1 if the device was bound to a driver;
1009  * 0 if no matching driver was found;
1010  * -ENODEV if the device is not registered.
1011  *
1012  * When called for a USB interface, @dev->parent lock must be held.
1013  */
1014 int device_attach(struct device *dev)
1015 {
1016         return __device_attach(dev, false);
1017 }
1018 EXPORT_SYMBOL_GPL(device_attach);
1019
1020 void device_initial_probe(struct device *dev)
1021 {
1022         __device_attach(dev, true);
1023 }
1024
1025 /*
1026  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1027  * @dev: Device we will update driver info for
1028  * @parent: Parent device. Needed if the bus requires parent lock
1029  *
1030  * This function will take the required locks for manipulating dev->drv.
1031  * Normally this will just be the @dev lock, but when called for a USB
1032  * interface, @parent lock will be held as well.
1033  */
1034 static void __device_driver_lock(struct device *dev, struct device *parent)
1035 {
1036         if (parent && dev->bus->need_parent_lock)
1037                 device_lock(parent);
1038         device_lock(dev);
1039 }
1040
1041 /*
1042  * __device_driver_unlock - release locks needed to manipulate dev->drv
1043  * @dev: Device we will update driver info for
1044  * @parent: Parent device. Needed if the bus requires parent lock
1045  *
1046  * This function will release the required locks for manipulating dev->drv.
1047  * Normally this will just be the @dev lock, but when called for a
1048  * USB interface, @parent lock will be released as well.
1049  */
1050 static void __device_driver_unlock(struct device *dev, struct device *parent)
1051 {
1052         device_unlock(dev);
1053         if (parent && dev->bus->need_parent_lock)
1054                 device_unlock(parent);
1055 }
1056
1057 /**
1058  * device_driver_attach - attach a specific driver to a specific device
1059  * @drv: Driver to attach
1060  * @dev: Device to attach it to
1061  *
1062  * Manually attach driver to a device. Will acquire both @dev lock and
1063  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1064  */
1065 int device_driver_attach(struct device_driver *drv, struct device *dev)
1066 {
1067         int ret;
1068
1069         __device_driver_lock(dev, dev->parent);
1070         ret = __driver_probe_device(drv, dev);
1071         __device_driver_unlock(dev, dev->parent);
1072
1073         /* also return probe errors as normal negative errnos */
1074         if (ret > 0)
1075                 ret = -ret;
1076         if (ret == -EPROBE_DEFER)
1077                 return -EAGAIN;
1078         return ret;
1079 }
1080 EXPORT_SYMBOL_GPL(device_driver_attach);
1081
1082 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1083 {
1084         struct device *dev = _dev;
1085         struct device_driver *drv;
1086         int ret;
1087
1088         __device_driver_lock(dev, dev->parent);
1089         drv = dev->p->async_driver;
1090         dev->p->async_driver = NULL;
1091         ret = driver_probe_device(drv, dev);
1092         __device_driver_unlock(dev, dev->parent);
1093
1094         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1095
1096         put_device(dev);
1097 }
1098
1099 static int __driver_attach(struct device *dev, void *data)
1100 {
1101         struct device_driver *drv = data;
1102         bool async = false;
1103         int ret;
1104
1105         /*
1106          * Lock device and try to bind to it. We drop the error
1107          * here and always return 0, because we need to keep trying
1108          * to bind to devices and some drivers will return an error
1109          * simply if it didn't support the device.
1110          *
1111          * driver_probe_device() will spit a warning if there
1112          * is an error.
1113          */
1114
1115         ret = driver_match_device(drv, dev);
1116         if (ret == 0) {
1117                 /* no match */
1118                 return 0;
1119         } else if (ret == -EPROBE_DEFER) {
1120                 dev_dbg(dev, "Device match requests probe deferral\n");
1121                 dev->can_match = true;
1122                 driver_deferred_probe_add(dev);
1123         } else if (ret < 0) {
1124                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1125                 return ret;
1126         } /* ret > 0 means positive match */
1127
1128         if (driver_allows_async_probing(drv)) {
1129                 /*
1130                  * Instead of probing the device synchronously we will
1131                  * probe it asynchronously to allow for more parallelism.
1132                  *
1133                  * We only take the device lock here in order to guarantee
1134                  * that the dev->driver and async_driver fields are protected
1135                  */
1136                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1137                 device_lock(dev);
1138                 if (!dev->driver && !dev->p->async_driver) {
1139                         get_device(dev);
1140                         dev->p->async_driver = drv;
1141                         async = true;
1142                 }
1143                 device_unlock(dev);
1144                 if (async)
1145                         async_schedule_dev(__driver_attach_async_helper, dev);
1146                 return 0;
1147         }
1148
1149         __device_driver_lock(dev, dev->parent);
1150         driver_probe_device(drv, dev);
1151         __device_driver_unlock(dev, dev->parent);
1152
1153         return 0;
1154 }
1155
1156 /**
1157  * driver_attach - try to bind driver to devices.
1158  * @drv: driver.
1159  *
1160  * Walk the list of devices that the bus has on it and try to
1161  * match the driver with each one.  If driver_probe_device()
1162  * returns 0 and the @dev->driver is set, we've found a
1163  * compatible pair.
1164  */
1165 int driver_attach(struct device_driver *drv)
1166 {
1167         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1168 }
1169 EXPORT_SYMBOL_GPL(driver_attach);
1170
1171 /*
1172  * __device_release_driver() must be called with @dev lock held.
1173  * When called for a USB interface, @dev->parent lock must be held as well.
1174  */
1175 static void __device_release_driver(struct device *dev, struct device *parent)
1176 {
1177         struct device_driver *drv;
1178
1179         drv = dev->driver;
1180         if (drv) {
1181                 pm_runtime_get_sync(dev);
1182
1183                 while (device_links_busy(dev)) {
1184                         __device_driver_unlock(dev, parent);
1185
1186                         device_links_unbind_consumers(dev);
1187
1188                         __device_driver_lock(dev, parent);
1189                         /*
1190                          * A concurrent invocation of the same function might
1191                          * have released the driver successfully while this one
1192                          * was waiting, so check for that.
1193                          */
1194                         if (dev->driver != drv) {
1195                                 pm_runtime_put(dev);
1196                                 return;
1197                         }
1198                 }
1199
1200                 driver_sysfs_remove(dev);
1201
1202                 if (dev->bus)
1203                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1204                                                      BUS_NOTIFY_UNBIND_DRIVER,
1205                                                      dev);
1206
1207                 pm_runtime_put_sync(dev);
1208
1209                 device_remove(dev);
1210
1211                 if (dev->bus && dev->bus->dma_cleanup)
1212                         dev->bus->dma_cleanup(dev);
1213
1214                 device_links_driver_cleanup(dev);
1215                 device_unbind_cleanup(dev);
1216
1217                 klist_remove(&dev->p->knode_driver);
1218                 device_pm_check_callbacks(dev);
1219                 if (dev->bus)
1220                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1221                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1222                                                      dev);
1223
1224                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1225         }
1226 }
1227
1228 void device_release_driver_internal(struct device *dev,
1229                                     struct device_driver *drv,
1230                                     struct device *parent)
1231 {
1232         __device_driver_lock(dev, parent);
1233
1234         if (!drv || drv == dev->driver)
1235                 __device_release_driver(dev, parent);
1236
1237         __device_driver_unlock(dev, parent);
1238 }
1239
1240 /**
1241  * device_release_driver - manually detach device from driver.
1242  * @dev: device.
1243  *
1244  * Manually detach device from driver.
1245  * When called for a USB interface, @dev->parent lock must be held.
1246  *
1247  * If this function is to be called with @dev->parent lock held, ensure that
1248  * the device's consumers are unbound in advance or that their locks can be
1249  * acquired under the @dev->parent lock.
1250  */
1251 void device_release_driver(struct device *dev)
1252 {
1253         /*
1254          * If anyone calls device_release_driver() recursively from
1255          * within their ->remove callback for the same device, they
1256          * will deadlock right here.
1257          */
1258         device_release_driver_internal(dev, NULL, NULL);
1259 }
1260 EXPORT_SYMBOL_GPL(device_release_driver);
1261
1262 /**
1263  * device_driver_detach - detach driver from a specific device
1264  * @dev: device to detach driver from
1265  *
1266  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1267  * lock if needed.
1268  */
1269 void device_driver_detach(struct device *dev)
1270 {
1271         device_release_driver_internal(dev, NULL, dev->parent);
1272 }
1273
1274 /**
1275  * driver_detach - detach driver from all devices it controls.
1276  * @drv: driver.
1277  */
1278 void driver_detach(struct device_driver *drv)
1279 {
1280         struct device_private *dev_prv;
1281         struct device *dev;
1282
1283         if (driver_allows_async_probing(drv))
1284                 async_synchronize_full();
1285
1286         for (;;) {
1287                 spin_lock(&drv->p->klist_devices.k_lock);
1288                 if (list_empty(&drv->p->klist_devices.k_list)) {
1289                         spin_unlock(&drv->p->klist_devices.k_lock);
1290                         break;
1291                 }
1292                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1293                                      struct device_private,
1294                                      knode_driver.n_node);
1295                 dev = dev_prv->device;
1296                 get_device(dev);
1297                 spin_unlock(&drv->p->klist_devices.k_lock);
1298                 device_release_driver_internal(dev, drv, dev->parent);
1299                 put_device(dev);
1300         }
1301 }