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 <gregkh@suse.de>
  16  * Copyright (c) 2007-2009 Novell Inc.
  17  */
  18
  19 #include <linux/debugfs.h>
  20 #include <linux/device.h>
  21 #include <linux/delay.h>
  22 #include <linux/dma-map-ops.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/kthread.h>
  26 #include <linux/wait.h>
  27 #include <linux/async.h>
  28 #include <linux/pm_runtime.h>
  29 #include <linux/pinctrl/devinfo.h>
  30 #include <linux/slab.h>
  31
  32 #include "base.h"
  33 #include "power/power.h"
  34
  35 /*
  36  * Deferred Probe infrastructure.
  37  *
  38  * Sometimes driver probe order matters, but the kernel doesn't always have
  39  * dependency information which means some drivers will get probed before a
  40  * resource it depends on is available.  For example, an SDHCI driver may
  41  * first need a GPIO line from an i2c GPIO controller before it can be
  42  * initialized.  If a required resource is not available yet, a driver can
  43  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  44  *
  45  * Deferred probe maintains two lists of devices, a pending list and an active
  46  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  47  * pending list.  A successful driver probe will trigger moving all devices
  48  * from the pending to the active list so that the workqueue will eventually
  49  * retry them.
  50  *
  51  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  52  * of the (struct device*)->p->deferred_probe pointers are manipulated
  53  */
  54 static DEFINE_MUTEX(deferred_probe_mutex);
  55 static LIST_HEAD(deferred_probe_pending_list);
  56 static LIST_HEAD(deferred_probe_active_list);
  57 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
  58 static bool initcalls_done;
  59
  60 /* Save the async probe drivers' name from kernel cmdline */
  61 #define ASYNC_DRV_NAMES_MAX_LEN 256
  62 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
  63 static bool async_probe_default;
  64
  65 /*
  66  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  67  * to prohibit probing of devices as it could be unsafe.
  68  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  69  */
  70 static bool defer_all_probes;
  71
  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 static 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 static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue);
 267
 268 static int __init deferred_probe_timeout_setup(char *str)
 269 {
 270         int timeout;
 271
 272         if (!kstrtoint(str, 10, &timeout))
 273                 driver_deferred_probe_timeout = timeout;
 274         return 1;
 275 }
 276 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 277
 278 /**
 279  * driver_deferred_probe_check_state() - Check deferred probe state
 280  * @dev: device to check
 281  *
 282  * Return:
 283  * * -ENODEV if initcalls have completed and modules are disabled.
 284  * * -ETIMEDOUT if the deferred probe timeout was set and has expired
 285  *   and modules are enabled.
 286  * * -EPROBE_DEFER in other cases.
 287  *
 288  * Drivers or subsystems can opt-in to calling this function instead of directly
 289  * returning -EPROBE_DEFER.
 290  */
 291 int driver_deferred_probe_check_state(struct device *dev)
 292 {
 293         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 294                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 295                 return -ENODEV;
 296         }
 297
 298         if (!driver_deferred_probe_timeout && initcalls_done) {
 299                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 300                 return -ETIMEDOUT;
 301         }
 302
 303         return -EPROBE_DEFER;
 304 }
 305 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
 306
 307 static void deferred_probe_timeout_work_func(struct work_struct *work)
 308 {
 309         struct device_private *p;
 310
 311         fw_devlink_drivers_done();
 312
 313         driver_deferred_probe_timeout = 0;
 314         driver_deferred_probe_trigger();
 315         flush_work(&deferred_probe_work);
 316
 317         mutex_lock(&deferred_probe_mutex);
 318         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 319                 dev_info(p->device, "deferred probe pending\n");
 320         mutex_unlock(&deferred_probe_mutex);
 321         wake_up_all(&probe_timeout_waitqueue);
 322 }
 323 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 324
 325 void deferred_probe_extend_timeout(void)
 326 {
 327         /*
 328          * If the work hasn't been queued yet or if the work expired, don't
 329          * start a new one.
 330          */
 331         if (cancel_delayed_work(&deferred_probe_timeout_work)) {
 332                 schedule_delayed_work(&deferred_probe_timeout_work,
 333                                 driver_deferred_probe_timeout * HZ);
 334                 pr_debug("Extended deferred probe timeout by %d secs\n",
 335                                         driver_deferred_probe_timeout);
 336         }
 337 }
 338
 339 /**
 340  * deferred_probe_initcall() - Enable probing of deferred devices
 341  *
 342  * We don't want to get in the way when the bulk of drivers are getting probed.
 343  * Instead, this initcall makes sure that deferred probing is delayed until
 344  * late_initcall time.
 345  */
 346 static int deferred_probe_initcall(void)
 347 {
 348         debugfs_create_file("devices_deferred", 0444, NULL, NULL,
 349                             &deferred_devs_fops);
 350
 351         driver_deferred_probe_enable = true;
 352         driver_deferred_probe_trigger();
 353         /* Sort as many dependencies as possible before exiting initcalls */
 354         flush_work(&deferred_probe_work);
 355         initcalls_done = true;
 356
 357         if (!IS_ENABLED(CONFIG_MODULES))
 358                 fw_devlink_drivers_done();
 359
 360         /*
 361          * Trigger deferred probe again, this time we won't defer anything
 362          * that is optional
 363          */
 364         driver_deferred_probe_trigger();
 365         flush_work(&deferred_probe_work);
 366
 367         if (driver_deferred_probe_timeout > 0) {
 368                 schedule_delayed_work(&deferred_probe_timeout_work,
 369                         driver_deferred_probe_timeout * HZ);
 370         }
 371         return 0;
 372 }
 373 late_initcall(deferred_probe_initcall);
 374
 375 static void __exit deferred_probe_exit(void)
 376 {
 377         debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
 378 }
 379 __exitcall(deferred_probe_exit);
 380
 381 /**
 382  * device_is_bound() - Check if device is bound to a driver
 383  * @dev: device to check
 384  *
 385  * Returns true if passed device has already finished probing successfully
 386  * against a driver.
 387  *
 388  * This function must be called with the device lock held.
 389  */
 390 bool device_is_bound(struct device *dev)
 391 {
 392         return dev->p && klist_node_attached(&dev->p->knode_driver);
 393 }
 394
 395 static void driver_bound(struct device *dev)
 396 {
 397         if (device_is_bound(dev)) {
 398                 pr_warn("%s: device %s already bound\n",
 399                         __func__, kobject_name(&dev->kobj));
 400                 return;
 401         }
 402
 403         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 404                  __func__, dev_name(dev));
 405
 406         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 407         device_links_driver_bound(dev);
 408
 409         device_pm_check_callbacks(dev);
 410
 411         /*
 412          * Make sure the device is no longer in one of the deferred lists and
 413          * kick off retrying all pending devices
 414          */
 415         driver_deferred_probe_del(dev);
 416         driver_deferred_probe_trigger();
 417
 418         if (dev->bus)
 419                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 420                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 421
 422         kobject_uevent(&dev->kobj, KOBJ_BIND);
 423 }
 424
 425 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 426                             const char *buf, size_t count)
 427 {
 428         device_lock(dev);
 429         dev->driver->coredump(dev);
 430         device_unlock(dev);
 431
 432         return count;
 433 }
 434 static DEVICE_ATTR_WO(coredump);
 435
 436 static int driver_sysfs_add(struct device *dev)
 437 {
 438         int ret;
 439
 440         if (dev->bus)
 441                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 442                                              BUS_NOTIFY_BIND_DRIVER, dev);
 443
 444         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 445                                 kobject_name(&dev->kobj));
 446         if (ret)
 447                 goto fail;
 448
 449         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 450                                 "driver");
 451         if (ret)
 452                 goto rm_dev;
 453
 454         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 455                 return 0;
 456
 457         ret = device_create_file(dev, &dev_attr_coredump);
 458         if (!ret)
 459                 return 0;
 460
 461         sysfs_remove_link(&dev->kobj, "driver");
 462
 463 rm_dev:
 464         sysfs_remove_link(&dev->driver->p->kobj,
 465                           kobject_name(&dev->kobj));
 466
 467 fail:
 468         return ret;
 469 }
 470
 471 static void driver_sysfs_remove(struct device *dev)
 472 {
 473         struct device_driver *drv = dev->driver;
 474
 475         if (drv) {
 476                 if (drv->coredump)
 477                         device_remove_file(dev, &dev_attr_coredump);
 478                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 479                 sysfs_remove_link(&dev->kobj, "driver");
 480         }
 481 }
 482
 483 /**
 484  * device_bind_driver - bind a driver to one device.
 485  * @dev: device.
 486  *
 487  * Allow manual attachment of a driver to a device.
 488  * Caller must have already set @dev->driver.
 489  *
 490  * Note that this does not modify the bus reference count.
 491  * Please verify that is accounted for before calling this.
 492  * (It is ok to call with no other effort from a driver's probe() method.)
 493  *
 494  * This function must be called with the device lock held.
 495  *
 496  * Callers should prefer to use device_driver_attach() instead.
 497  */
 498 int device_bind_driver(struct device *dev)
 499 {
 500         int ret;
 501
 502         ret = driver_sysfs_add(dev);
 503         if (!ret) {
 504                 device_links_force_bind(dev);
 505                 driver_bound(dev);
 506         }
 507         else if (dev->bus)
 508                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 509                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 510         return ret;
 511 }
 512 EXPORT_SYMBOL_GPL(device_bind_driver);
 513
 514 static atomic_t probe_count = ATOMIC_INIT(0);
 515 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 516
 517 static ssize_t state_synced_show(struct device *dev,
 518                                  struct device_attribute *attr, char *buf)
 519 {
 520         bool val;
 521
 522         device_lock(dev);
 523         val = dev->state_synced;
 524         device_unlock(dev);
 525
 526         return sysfs_emit(buf, "%u\n", val);
 527 }
 528 static DEVICE_ATTR_RO(state_synced);
 529
 530 static void device_unbind_cleanup(struct device *dev)
 531 {
 532         devres_release_all(dev);
 533         arch_teardown_dma_ops(dev);
 534         kfree(dev->dma_range_map);
 535         dev->dma_range_map = NULL;
 536         dev->driver = NULL;
 537         dev_set_drvdata(dev, NULL);
 538         if (dev->pm_domain && dev->pm_domain->dismiss)
 539                 dev->pm_domain->dismiss(dev);
 540         pm_runtime_reinit(dev);
 541         dev_pm_set_driver_flags(dev, 0);
 542 }
 543
 544 static void device_remove(struct device *dev)
 545 {
 546         device_remove_file(dev, &dev_attr_state_synced);
 547         device_remove_groups(dev, dev->driver->dev_groups);
 548
 549         if (dev->bus && dev->bus->remove)
 550                 dev->bus->remove(dev);
 551         else if (dev->driver->remove)
 552                 dev->driver->remove(dev);
 553 }
 554
 555 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 556 {
 557         int ret = 0;
 558
 559         if (dev->bus->probe)
 560                 ret = dev->bus->probe(dev);
 561         else if (drv->probe)
 562                 ret = drv->probe(dev);
 563
 564         switch (ret) {
 565         case 0:
 566                 break;
 567         case -EPROBE_DEFER:
 568                 /* Driver requested deferred probing */
 569                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 570                 break;
 571         case -ENODEV:
 572         case -ENXIO:
 573                 pr_debug("%s: probe of %s rejects match %d\n",
 574                          drv->name, dev_name(dev), ret);
 575                 break;
 576         default:
 577                 /* driver matched but the probe failed */
 578                 pr_warn("%s: probe of %s failed with error %d\n",
 579                         drv->name, dev_name(dev), ret);
 580                 break;
 581         }
 582
 583         return ret;
 584 }
 585
 586 static int really_probe(struct device *dev, struct device_driver *drv)
 587 {
 588         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 589                            !drv->suppress_bind_attrs;
 590         int ret;
 591
 592         if (defer_all_probes) {
 593                 /*
 594                  * Value of defer_all_probes can be set only by
 595                  * device_block_probing() which, in turn, will call
 596                  * wait_for_device_probe() right after that to avoid any races.
 597                  */
 598                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 599                 return -EPROBE_DEFER;
 600         }
 601
 602         ret = device_links_check_suppliers(dev);
 603         if (ret)
 604                 return ret;
 605
 606         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 607                  drv->bus->name, __func__, drv->name, dev_name(dev));
 608         if (!list_empty(&dev->devres_head)) {
 609                 dev_crit(dev, "Resources present before probing\n");
 610                 ret = -EBUSY;
 611                 goto done;
 612         }
 613
 614 re_probe:
 615         dev->driver = drv;
 616
 617         /* If using pinctrl, bind pins now before probing */
 618         ret = pinctrl_bind_pins(dev);
 619         if (ret)
 620                 goto pinctrl_bind_failed;
 621
 622         if (dev->bus->dma_configure) {
 623                 ret = dev->bus->dma_configure(dev);
 624                 if (ret)
 625                         goto pinctrl_bind_failed;
 626         }
 627
 628         ret = driver_sysfs_add(dev);
 629         if (ret) {
 630                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 631                        __func__, dev_name(dev));
 632                 goto sysfs_failed;
 633         }
 634
 635         if (dev->pm_domain && dev->pm_domain->activate) {
 636                 ret = dev->pm_domain->activate(dev);
 637                 if (ret)
 638                         goto probe_failed;
 639         }
 640
 641         ret = call_driver_probe(dev, drv);
 642         if (ret) {
 643                 /*
 644                  * Return probe errors as positive values so that the callers
 645                  * can distinguish them from other errors.
 646                  */
 647                 ret = -ret;
 648                 goto probe_failed;
 649         }
 650
 651         ret = device_add_groups(dev, drv->dev_groups);
 652         if (ret) {
 653                 dev_err(dev, "device_add_groups() failed\n");
 654                 goto dev_groups_failed;
 655         }
 656
 657         if (dev_has_sync_state(dev)) {
 658                 ret = device_create_file(dev, &dev_attr_state_synced);
 659                 if (ret) {
 660                         dev_err(dev, "state_synced sysfs add failed\n");
 661                         goto dev_sysfs_state_synced_failed;
 662                 }
 663         }
 664
 665         if (test_remove) {
 666                 test_remove = false;
 667
 668                 device_remove(dev);
 669                 driver_sysfs_remove(dev);
 670                 device_unbind_cleanup(dev);
 671
 672                 goto re_probe;
 673         }
 674
 675         pinctrl_init_done(dev);
 676
 677         if (dev->pm_domain && dev->pm_domain->sync)
 678                 dev->pm_domain->sync(dev);
 679
 680         driver_bound(dev);
 681         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 682                  drv->bus->name, __func__, dev_name(dev), drv->name);
 683         goto done;
 684
 685 dev_sysfs_state_synced_failed:
 686 dev_groups_failed:
 687         device_remove(dev);
 688 probe_failed:
 689         driver_sysfs_remove(dev);
 690 sysfs_failed:
 691         if (dev->bus)
 692                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 693                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 694         if (dev->bus && dev->bus->dma_cleanup)
 695                 dev->bus->dma_cleanup(dev);
 696 pinctrl_bind_failed:
 697         device_links_no_driver(dev);
 698         device_unbind_cleanup(dev);
 699 done:
 700         return ret;
 701 }
 702
 703 /*
 704  * For initcall_debug, show the driver probe time.
 705  */
 706 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 707 {
 708         ktime_t calltime, rettime;
 709         int ret;
 710
 711         calltime = ktime_get();
 712         ret = really_probe(dev, drv);
 713         rettime = ktime_get();
 714         pr_debug("probe of %s returned %d after %lld usecs\n",
 715                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 716         return ret;
 717 }
 718
 719 /**
 720  * driver_probe_done
 721  * Determine if the probe sequence is finished or not.
 722  *
 723  * Should somehow figure out how to use a semaphore, not an atomic variable...
 724  */
 725 int driver_probe_done(void)
 726 {
 727         int local_probe_count = atomic_read(&probe_count);
 728
 729         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 730         if (local_probe_count)
 731                 return -EBUSY;
 732         return 0;
 733 }
 734
 735 /**
 736  * wait_for_device_probe
 737  * Wait for device probing to be completed.
 738  */
 739 void wait_for_device_probe(void)
 740 {
 741         /* wait for probe timeout */
 742         wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout);
 743
 744         /* wait for the deferred probe workqueue to finish */
 745         flush_work(&deferred_probe_work);
 746
 747         /* wait for the known devices to complete their probing */
 748         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 749         async_synchronize_full();
 750 }
 751 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 752
 753 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 754 {
 755         int ret = 0;
 756
 757         if (dev->p->dead || !device_is_registered(dev))
 758                 return -ENODEV;
 759         if (dev->driver)
 760                 return -EBUSY;
 761
 762         dev->can_match = true;
 763         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 764                  drv->bus->name, __func__, dev_name(dev), drv->name);
 765
 766         pm_runtime_get_suppliers(dev);
 767         if (dev->parent)
 768                 pm_runtime_get_sync(dev->parent);
 769
 770         pm_runtime_barrier(dev);
 771         if (initcall_debug)
 772                 ret = really_probe_debug(dev, drv);
 773         else
 774                 ret = really_probe(dev, drv);
 775         pm_request_idle(dev);
 776
 777         if (dev->parent)
 778                 pm_runtime_put(dev->parent);
 779
 780         pm_runtime_put_suppliers(dev);
 781         return ret;
 782 }
 783
 784 /**
 785  * driver_probe_device - attempt to bind device & driver together
 786  * @drv: driver to bind a device to
 787  * @dev: device to try to bind to the driver
 788  *
 789  * This function returns -ENODEV if the device is not registered, -EBUSY if it
 790  * already has a driver, 0 if the device is bound successfully and a positive
 791  * (inverted) error code for failures from the ->probe method.
 792  *
 793  * This function must be called with @dev lock held.  When called for a
 794  * USB interface, @dev->parent lock must be held as well.
 795  *
 796  * If the device has a parent, runtime-resume the parent before driver probing.
 797  */
 798 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 799 {
 800         int trigger_count = atomic_read(&deferred_trigger_count);
 801         int ret;
 802
 803         atomic_inc(&probe_count);
 804         ret = __driver_probe_device(drv, dev);
 805         if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
 806                 driver_deferred_probe_add(dev);
 807
 808                 /*
 809                  * Did a trigger occur while probing? Need to re-trigger if yes
 810                  */
 811                 if (trigger_count != atomic_read(&deferred_trigger_count) &&
 812                     !defer_all_probes)
 813                         driver_deferred_probe_trigger();
 814         }
 815         atomic_dec(&probe_count);
 816         wake_up_all(&probe_waitqueue);
 817         return ret;
 818 }
 819
 820 static inline bool cmdline_requested_async_probing(const char *drv_name)
 821 {
 822         bool async_drv;
 823
 824         async_drv = parse_option_str(async_probe_drv_names, drv_name);
 825
 826         return (async_probe_default != async_drv);
 827 }
 828
 829 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 830 static int __init save_async_options(char *buf)
 831 {
 832         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 833                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 834
 835         strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 836         async_probe_default = parse_option_str(async_probe_drv_names, "*");
 837
 838         return 1;
 839 }
 840 __setup("driver_async_probe=", save_async_options);
 841
 842 bool driver_allows_async_probing(struct device_driver *drv)
 843 {
 844         switch (drv->probe_type) {
 845         case PROBE_PREFER_ASYNCHRONOUS:
 846                 return true;
 847
 848         case PROBE_FORCE_SYNCHRONOUS:
 849                 return false;
 850
 851         default:
 852                 if (cmdline_requested_async_probing(drv->name))
 853                         return true;
 854
 855                 if (module_requested_async_probing(drv->owner))
 856                         return true;
 857
 858                 return false;
 859         }
 860 }
 861
 862 struct device_attach_data {
 863         struct device *dev;
 864
 865         /*
 866          * Indicates whether we are considering asynchronous probing or
 867          * not. Only initial binding after device or driver registration
 868          * (including deferral processing) may be done asynchronously, the
 869          * rest is always synchronous, as we expect it is being done by
 870          * request from userspace.
 871          */
 872         bool check_async;
 873
 874         /*
 875          * Indicates if we are binding synchronous or asynchronous drivers.
 876          * When asynchronous probing is enabled we'll execute 2 passes
 877          * over drivers: first pass doing synchronous probing and second
 878          * doing asynchronous probing (if synchronous did not succeed -
 879          * most likely because there was no driver requiring synchronous
 880          * probing - and we found asynchronous driver during first pass).
 881          * The 2 passes are done because we can't shoot asynchronous
 882          * probe for given device and driver from bus_for_each_drv() since
 883          * driver pointer is not guaranteed to stay valid once
 884          * bus_for_each_drv() iterates to the next driver on the bus.
 885          */
 886         bool want_async;
 887
 888         /*
 889          * We'll set have_async to 'true' if, while scanning for matching
 890          * driver, we'll encounter one that requests asynchronous probing.
 891          */
 892         bool have_async;
 893 };
 894
 895 static int __device_attach_driver(struct device_driver *drv, void *_data)
 896 {
 897         struct device_attach_data *data = _data;
 898         struct device *dev = data->dev;
 899         bool async_allowed;
 900         int ret;
 901
 902         ret = driver_match_device(drv, dev);
 903         if (ret == 0) {
 904                 /* no match */
 905                 return 0;
 906         } else if (ret == -EPROBE_DEFER) {
 907                 dev_dbg(dev, "Device match requests probe deferral\n");
 908                 dev->can_match = true;
 909                 driver_deferred_probe_add(dev);
 910         } else if (ret < 0) {
 911                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 912                 return ret;
 913         } /* ret > 0 means positive match */
 914
 915         async_allowed = driver_allows_async_probing(drv);
 916
 917         if (async_allowed)
 918                 data->have_async = true;
 919
 920         if (data->check_async && async_allowed != data->want_async)
 921                 return 0;
 922
 923         /*
 924          * Ignore errors returned by ->probe so that the next driver can try
 925          * its luck.
 926          */
 927         ret = driver_probe_device(drv, dev);
 928         if (ret < 0)
 929                 return ret;
 930         return ret == 0;
 931 }
 932
 933 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 934 {
 935         struct device *dev = _dev;
 936         struct device_attach_data data = {
 937                 .dev            = dev,
 938                 .check_async    = true,
 939                 .want_async     = true,
 940         };
 941
 942         device_lock(dev);
 943
 944         /*
 945          * Check if device has already been removed or claimed. This may
 946          * happen with driver loading, device discovery/registration,
 947          * and deferred probe processing happens all at once with
 948          * multiple threads.
 949          */
 950         if (dev->p->dead || dev->driver)
 951                 goto out_unlock;
 952
 953         if (dev->parent)
 954                 pm_runtime_get_sync(dev->parent);
 955
 956         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 957         dev_dbg(dev, "async probe completed\n");
 958
 959         pm_request_idle(dev);
 960
 961         if (dev->parent)
 962                 pm_runtime_put(dev->parent);
 963 out_unlock:
 964         device_unlock(dev);
 965
 966         put_device(dev);
 967 }
 968
 969 static int __device_attach(struct device *dev, bool allow_async)
 970 {
 971         int ret = 0;
 972         bool async = false;
 973
 974         device_lock(dev);
 975         if (dev->p->dead) {
 976                 goto out_unlock;
 977         } else if (dev->driver) {
 978                 if (device_is_bound(dev)) {
 979                         ret = 1;
 980                         goto out_unlock;
 981                 }
 982                 ret = device_bind_driver(dev);
 983                 if (ret == 0)
 984                         ret = 1;
 985                 else {
 986                         dev->driver = NULL;
 987                         ret = 0;
 988                 }
 989         } else {
 990                 struct device_attach_data data = {
 991                         .dev = dev,
 992                         .check_async = allow_async,
 993                         .want_async = false,
 994                 };
 995
 996                 if (dev->parent)
 997                         pm_runtime_get_sync(dev->parent);
 998
 999                 ret = bus_for_each_drv(dev->bus, NULL, &data,
1000                                         __device_attach_driver);
1001                 if (!ret && allow_async && data.have_async) {
1002                         /*
1003                          * If we could not find appropriate driver
1004                          * synchronously and we are allowed to do
1005                          * async probes and there are drivers that
1006                          * want to probe asynchronously, we'll
1007                          * try them.
1008                          */
1009                         dev_dbg(dev, "scheduling asynchronous probe\n");
1010                         get_device(dev);
1011                         async = true;
1012                 } else {
1013                         pm_request_idle(dev);
1014                 }
1015
1016                 if (dev->parent)
1017                         pm_runtime_put(dev->parent);
1018         }
1019 out_unlock:
1020         device_unlock(dev);
1021         if (async)
1022                 async_schedule_dev(__device_attach_async_helper, dev);
1023         return ret;
1024 }
1025
1026 /**
1027  * device_attach - try to attach device to a driver.
1028  * @dev: device.
1029  *
1030  * Walk the list of drivers that the bus has and call
1031  * driver_probe_device() for each pair. If a compatible
1032  * pair is found, break out and return.
1033  *
1034  * Returns 1 if the device was bound to a driver;
1035  * 0 if no matching driver was found;
1036  * -ENODEV if the device is not registered.
1037  *
1038  * When called for a USB interface, @dev->parent lock must be held.
1039  */
1040 int device_attach(struct device *dev)
1041 {
1042         return __device_attach(dev, false);
1043 }
1044 EXPORT_SYMBOL_GPL(device_attach);
1045
1046 void device_initial_probe(struct device *dev)
1047 {
1048         __device_attach(dev, true);
1049 }
1050
1051 /*
1052  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1053  * @dev: Device we will update driver info for
1054  * @parent: Parent device. Needed if the bus requires parent lock
1055  *
1056  * This function will take the required locks for manipulating dev->drv.
1057  * Normally this will just be the @dev lock, but when called for a USB
1058  * interface, @parent lock will be held as well.
1059  */
1060 static void __device_driver_lock(struct device *dev, struct device *parent)
1061 {
1062         if (parent && dev->bus->need_parent_lock)
1063                 device_lock(parent);
1064         device_lock(dev);
1065 }
1066
1067 /*
1068  * __device_driver_unlock - release locks needed to manipulate dev->drv
1069  * @dev: Device we will update driver info for
1070  * @parent: Parent device. Needed if the bus requires parent lock
1071  *
1072  * This function will release the required locks for manipulating dev->drv.
1073  * Normally this will just be the @dev lock, but when called for a
1074  * USB interface, @parent lock will be released as well.
1075  */
1076 static void __device_driver_unlock(struct device *dev, struct device *parent)
1077 {
1078         device_unlock(dev);
1079         if (parent && dev->bus->need_parent_lock)
1080                 device_unlock(parent);
1081 }
1082
1083 /**
1084  * device_driver_attach - attach a specific driver to a specific device
1085  * @drv: Driver to attach
1086  * @dev: Device to attach it to
1087  *
1088  * Manually attach driver to a device. Will acquire both @dev lock and
1089  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1090  */
1091 int device_driver_attach(struct device_driver *drv, struct device *dev)
1092 {
1093         int ret;
1094
1095         __device_driver_lock(dev, dev->parent);
1096         ret = __driver_probe_device(drv, dev);
1097         __device_driver_unlock(dev, dev->parent);
1098
1099         /* also return probe errors as normal negative errnos */
1100         if (ret > 0)
1101                 ret = -ret;
1102         if (ret == -EPROBE_DEFER)
1103                 return -EAGAIN;
1104         return ret;
1105 }
1106 EXPORT_SYMBOL_GPL(device_driver_attach);
1107
1108 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1109 {
1110         struct device *dev = _dev;
1111         struct device_driver *drv;
1112         int ret;
1113
1114         __device_driver_lock(dev, dev->parent);
1115         drv = dev->p->async_driver;
1116         dev->p->async_driver = NULL;
1117         ret = driver_probe_device(drv, dev);
1118         __device_driver_unlock(dev, dev->parent);
1119
1120         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1121
1122         put_device(dev);
1123 }
1124
1125 static int __driver_attach(struct device *dev, void *data)
1126 {
1127         struct device_driver *drv = data;
1128         int ret;
1129
1130         /*
1131          * Lock device and try to bind to it. We drop the error
1132          * here and always return 0, because we need to keep trying
1133          * to bind to devices and some drivers will return an error
1134          * simply if it didn't support the device.
1135          *
1136          * driver_probe_device() will spit a warning if there
1137          * is an error.
1138          */
1139
1140         ret = driver_match_device(drv, dev);
1141         if (ret == 0) {
1142                 /* no match */
1143                 return 0;
1144         } else if (ret == -EPROBE_DEFER) {
1145                 dev_dbg(dev, "Device match requests probe deferral\n");
1146                 dev->can_match = true;
1147                 driver_deferred_probe_add(dev);
1148         } else if (ret < 0) {
1149                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1150                 return ret;
1151         } /* ret > 0 means positive match */
1152
1153         if (driver_allows_async_probing(drv)) {
1154                 /*
1155                  * Instead of probing the device synchronously we will
1156                  * probe it asynchronously to allow for more parallelism.
1157                  *
1158                  * We only take the device lock here in order to guarantee
1159                  * that the dev->driver and async_driver fields are protected
1160                  */
1161                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1162                 device_lock(dev);
1163                 if (!dev->driver && !dev->p->async_driver) {
1164                         get_device(dev);
1165                         dev->p->async_driver = drv;
1166                         async_schedule_dev(__driver_attach_async_helper, dev);
1167                 }
1168                 device_unlock(dev);
1169                 return 0;
1170         }
1171
1172         __device_driver_lock(dev, dev->parent);
1173         driver_probe_device(drv, dev);
1174         __device_driver_unlock(dev, dev->parent);
1175
1176         return 0;
1177 }
1178
1179 /**
1180  * driver_attach - try to bind driver to devices.
1181  * @drv: driver.
1182  *
1183  * Walk the list of devices that the bus has on it and try to
1184  * match the driver with each one.  If driver_probe_device()
1185  * returns 0 and the @dev->driver is set, we've found a
1186  * compatible pair.
1187  */
1188 int driver_attach(struct device_driver *drv)
1189 {
1190         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1191 }
1192 EXPORT_SYMBOL_GPL(driver_attach);
1193
1194 /*
1195  * __device_release_driver() must be called with @dev lock held.
1196  * When called for a USB interface, @dev->parent lock must be held as well.
1197  */
1198 static void __device_release_driver(struct device *dev, struct device *parent)
1199 {
1200         struct device_driver *drv;
1201
1202         drv = dev->driver;
1203         if (drv) {
1204                 pm_runtime_get_sync(dev);
1205
1206                 while (device_links_busy(dev)) {
1207                         __device_driver_unlock(dev, parent);
1208
1209                         device_links_unbind_consumers(dev);
1210
1211                         __device_driver_lock(dev, parent);
1212                         /*
1213                          * A concurrent invocation of the same function might
1214                          * have released the driver successfully while this one
1215                          * was waiting, so check for that.
1216                          */
1217                         if (dev->driver != drv) {
1218                                 pm_runtime_put(dev);
1219                                 return;
1220                         }
1221                 }
1222
1223                 driver_sysfs_remove(dev);
1224
1225                 if (dev->bus)
1226                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1227                                                      BUS_NOTIFY_UNBIND_DRIVER,
1228                                                      dev);
1229
1230                 pm_runtime_put_sync(dev);
1231
1232                 device_remove(dev);
1233
1234                 if (dev->bus && dev->bus->dma_cleanup)
1235                         dev->bus->dma_cleanup(dev);
1236
1237                 device_links_driver_cleanup(dev);
1238                 device_unbind_cleanup(dev);
1239
1240                 klist_remove(&dev->p->knode_driver);
1241                 device_pm_check_callbacks(dev);
1242                 if (dev->bus)
1243                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1244                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1245                                                      dev);
1246
1247                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1248         }
1249 }
1250
1251 void device_release_driver_internal(struct device *dev,
1252                                     struct device_driver *drv,
1253                                     struct device *parent)
1254 {
1255         __device_driver_lock(dev, parent);
1256
1257         if (!drv || drv == dev->driver)
1258                 __device_release_driver(dev, parent);
1259
1260         __device_driver_unlock(dev, parent);
1261 }
1262
1263 /**
1264  * device_release_driver - manually detach device from driver.
1265  * @dev: device.
1266  *
1267  * Manually detach device from driver.
1268  * When called for a USB interface, @dev->parent lock must be held.
1269  *
1270  * If this function is to be called with @dev->parent lock held, ensure that
1271  * the device's consumers are unbound in advance or that their locks can be
1272  * acquired under the @dev->parent lock.
1273  */
1274 void device_release_driver(struct device *dev)
1275 {
1276         /*
1277          * If anyone calls device_release_driver() recursively from
1278          * within their ->remove callback for the same device, they
1279          * will deadlock right here.
1280          */
1281         device_release_driver_internal(dev, NULL, NULL);
1282 }
1283 EXPORT_SYMBOL_GPL(device_release_driver);
1284
1285 /**
1286  * device_driver_detach - detach driver from a specific device
1287  * @dev: device to detach driver from
1288  *
1289  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1290  * lock if needed.
1291  */
1292 void device_driver_detach(struct device *dev)
1293 {
1294         device_release_driver_internal(dev, NULL, dev->parent);
1295 }
1296
1297 /**
1298  * driver_detach - detach driver from all devices it controls.
1299  * @drv: driver.
1300  */
1301 void driver_detach(struct device_driver *drv)
1302 {
1303         struct device_private *dev_prv;
1304         struct device *dev;
1305
1306         if (driver_allows_async_probing(drv))
1307                 async_synchronize_full();
1308
1309         for (;;) {
1310                 spin_lock(&drv->p->klist_devices.k_lock);
1311                 if (list_empty(&drv->p->klist_devices.k_list)) {
1312                         spin_unlock(&drv->p->klist_devices.k_lock);
1313                         break;
1314                 }
1315                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1316                                      struct device_private,
1317                                      knode_driver.n_node);
1318                 dev = dev_prv->device;
1319                 get_device(dev);
1320                 spin_unlock(&drv->p->klist_devices.k_lock);
1321                 device_release_driver_internal(dev, drv, dev->parent);
1322                 put_device(dev);
1323         }
1324 }