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
  64 /*
  65  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  66  * to prohibit probing of devices as it could be unsafe.
  67  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  68  */
  69 static bool defer_all_probes;
  70
  71 static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
  72 {
  73         kfree(dev->p->deferred_probe_reason);
  74         dev->p->deferred_probe_reason = reason;
  75 }
  76
  77 /*
  78  * deferred_probe_work_func() - Retry probing devices in the active list.
  79  */
  80 static void deferred_probe_work_func(struct work_struct *work)
  81 {
  82         struct device *dev;
  83         struct device_private *private;
  84         /*
  85          * This block processes every device in the deferred 'active' list.
  86          * Each device is removed from the active list and passed to
  87          * bus_probe_device() to re-attempt the probe.  The loop continues
  88          * until every device in the active list is removed and retried.
  89          *
  90          * Note: Once the device is removed from the list and the mutex is
  91          * released, it is possible for the device get freed by another thread
  92          * and cause a illegal pointer dereference.  This code uses
  93          * get/put_device() to ensure the device structure cannot disappear
  94          * from under our feet.
  95          */
  96         mutex_lock(&deferred_probe_mutex);
  97         while (!list_empty(&deferred_probe_active_list)) {
  98                 private = list_first_entry(&deferred_probe_active_list,
  99                                         typeof(*dev->p), deferred_probe);
 100                 dev = private->device;
 101                 list_del_init(&private->deferred_probe);
 102
 103                 get_device(dev);
 104
 105                 __device_set_deferred_probe_reason(dev, NULL);
 106
 107                 /*
 108                  * Drop the mutex while probing each device; the probe path may
 109                  * manipulate the deferred list
 110                  */
 111                 mutex_unlock(&deferred_probe_mutex);
 112
 113                 /*
 114                  * Force the device to the end of the dpm_list since
 115                  * the PM code assumes that the order we add things to
 116                  * the list is a good order for suspend but deferred
 117                  * probe makes that very unsafe.
 118                  */
 119                 device_pm_move_to_tail(dev);
 120
 121                 dev_dbg(dev, "Retrying from deferred list\n");
 122                 bus_probe_device(dev);
 123                 mutex_lock(&deferred_probe_mutex);
 124
 125                 put_device(dev);
 126         }
 127         mutex_unlock(&deferred_probe_mutex);
 128 }
 129 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 130
 131 void driver_deferred_probe_add(struct device *dev)
 132 {
 133         if (!dev->can_match)
 134                 return;
 135
 136         mutex_lock(&deferred_probe_mutex);
 137         if (list_empty(&dev->p->deferred_probe)) {
 138                 dev_dbg(dev, "Added to deferred list\n");
 139                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 140         }
 141         mutex_unlock(&deferred_probe_mutex);
 142 }
 143
 144 void driver_deferred_probe_del(struct device *dev)
 145 {
 146         mutex_lock(&deferred_probe_mutex);
 147         if (!list_empty(&dev->p->deferred_probe)) {
 148                 dev_dbg(dev, "Removed from deferred list\n");
 149                 list_del_init(&dev->p->deferred_probe);
 150                 __device_set_deferred_probe_reason(dev, NULL);
 151         }
 152         mutex_unlock(&deferred_probe_mutex);
 153 }
 154
 155 static bool driver_deferred_probe_enable;
 156 /**
 157  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 158  *
 159  * This functions moves all devices from the pending list to the active
 160  * list and schedules the deferred probe workqueue to process them.  It
 161  * should be called anytime a driver is successfully bound to a device.
 162  *
 163  * Note, there is a race condition in multi-threaded probe. In the case where
 164  * more than one device is probing at the same time, it is possible for one
 165  * probe to complete successfully while another is about to defer. If the second
 166  * depends on the first, then it will get put on the pending list after the
 167  * trigger event has already occurred and will be stuck there.
 168  *
 169  * The atomic 'deferred_trigger_count' is used to determine if a successful
 170  * trigger has occurred in the midst of probing a driver. If the trigger count
 171  * changes in the midst of a probe, then deferred processing should be triggered
 172  * again.
 173  */
 174 static void driver_deferred_probe_trigger(void)
 175 {
 176         if (!driver_deferred_probe_enable)
 177                 return;
 178
 179         /*
 180          * A successful probe means that all the devices in the pending list
 181          * should be triggered to be reprobed.  Move all the deferred devices
 182          * into the active list so they can be retried by the workqueue
 183          */
 184         mutex_lock(&deferred_probe_mutex);
 185         atomic_inc(&deferred_trigger_count);
 186         list_splice_tail_init(&deferred_probe_pending_list,
 187                               &deferred_probe_active_list);
 188         mutex_unlock(&deferred_probe_mutex);
 189
 190         /*
 191          * Kick the re-probe thread.  It may already be scheduled, but it is
 192          * safe to kick it again.
 193          */
 194         queue_work(system_unbound_wq, &deferred_probe_work);
 195 }
 196
 197 /**
 198  * device_block_probing() - Block/defer device's probes
 199  *
 200  *      It will disable probing of devices and defer their probes instead.
 201  */
 202 void device_block_probing(void)
 203 {
 204         defer_all_probes = true;
 205         /* sync with probes to avoid races. */
 206         wait_for_device_probe();
 207 }
 208
 209 /**
 210  * device_unblock_probing() - Unblock/enable device's probes
 211  *
 212  *      It will restore normal behavior and trigger re-probing of deferred
 213  * devices.
 214  */
 215 void device_unblock_probing(void)
 216 {
 217         defer_all_probes = false;
 218         driver_deferred_probe_trigger();
 219 }
 220
 221 /**
 222  * device_set_deferred_probe_reason() - Set defer probe reason message for device
 223  * @dev: the pointer to the struct device
 224  * @vaf: the pointer to va_format structure with message
 225  */
 226 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
 227 {
 228         const char *drv = dev_driver_string(dev);
 229         char *reason;
 230
 231         mutex_lock(&deferred_probe_mutex);
 232
 233         reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
 234         __device_set_deferred_probe_reason(dev, reason);
 235
 236         mutex_unlock(&deferred_probe_mutex);
 237 }
 238
 239 /*
 240  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 241  */
 242 static int deferred_devs_show(struct seq_file *s, void *data)
 243 {
 244         struct device_private *curr;
 245
 246         mutex_lock(&deferred_probe_mutex);
 247
 248         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 249                 seq_printf(s, "%s\t%s", dev_name(curr->device),
 250                            curr->device->p->deferred_probe_reason ?: "\n");
 251
 252         mutex_unlock(&deferred_probe_mutex);
 253
 254         return 0;
 255 }
 256 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 257
 258 int driver_deferred_probe_timeout;
 259 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
 260 static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue);
 261
 262 static int __init deferred_probe_timeout_setup(char *str)
 263 {
 264         int timeout;
 265
 266         if (!kstrtoint(str, 10, &timeout))
 267                 driver_deferred_probe_timeout = timeout;
 268         return 1;
 269 }
 270 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 271
 272 /**
 273  * driver_deferred_probe_check_state() - Check deferred probe state
 274  * @dev: device to check
 275  *
 276  * Return:
 277  * -ENODEV if initcalls have completed and modules are disabled.
 278  * -ETIMEDOUT if the deferred probe timeout was set and has expired
 279  *  and modules are enabled.
 280  * -EPROBE_DEFER in other cases.
 281  *
 282  * Drivers or subsystems can opt-in to calling this function instead of directly
 283  * returning -EPROBE_DEFER.
 284  */
 285 int driver_deferred_probe_check_state(struct device *dev)
 286 {
 287         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 288                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 289                 return -ENODEV;
 290         }
 291
 292         if (!driver_deferred_probe_timeout && initcalls_done) {
 293                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 294                 return -ETIMEDOUT;
 295         }
 296
 297         return -EPROBE_DEFER;
 298 }
 299 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
 300
 301 static void deferred_probe_timeout_work_func(struct work_struct *work)
 302 {
 303         struct device_private *p;
 304
 305         fw_devlink_drivers_done();
 306
 307         driver_deferred_probe_timeout = 0;
 308         driver_deferred_probe_trigger();
 309         flush_work(&deferred_probe_work);
 310
 311         mutex_lock(&deferred_probe_mutex);
 312         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 313                 dev_info(p->device, "deferred probe pending\n");
 314         mutex_unlock(&deferred_probe_mutex);
 315         wake_up_all(&probe_timeout_waitqueue);
 316 }
 317 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 318
 319 /**
 320  * deferred_probe_initcall() - Enable probing of deferred devices
 321  *
 322  * We don't want to get in the way when the bulk of drivers are getting probed.
 323  * Instead, this initcall makes sure that deferred probing is delayed until
 324  * late_initcall time.
 325  */
 326 static int deferred_probe_initcall(void)
 327 {
 328         debugfs_create_file("devices_deferred", 0444, NULL, NULL,
 329                             &deferred_devs_fops);
 330
 331         driver_deferred_probe_enable = true;
 332         driver_deferred_probe_trigger();
 333         /* Sort as many dependencies as possible before exiting initcalls */
 334         flush_work(&deferred_probe_work);
 335         initcalls_done = true;
 336
 337         if (!IS_ENABLED(CONFIG_MODULES))
 338                 fw_devlink_drivers_done();
 339
 340         /*
 341          * Trigger deferred probe again, this time we won't defer anything
 342          * that is optional
 343          */
 344         driver_deferred_probe_trigger();
 345         flush_work(&deferred_probe_work);
 346
 347         if (driver_deferred_probe_timeout > 0) {
 348                 schedule_delayed_work(&deferred_probe_timeout_work,
 349                         driver_deferred_probe_timeout * HZ);
 350         }
 351         return 0;
 352 }
 353 late_initcall(deferred_probe_initcall);
 354
 355 static void __exit deferred_probe_exit(void)
 356 {
 357         debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
 358 }
 359 __exitcall(deferred_probe_exit);
 360
 361 /**
 362  * device_is_bound() - Check if device is bound to a driver
 363  * @dev: device to check
 364  *
 365  * Returns true if passed device has already finished probing successfully
 366  * against a driver.
 367  *
 368  * This function must be called with the device lock held.
 369  */
 370 bool device_is_bound(struct device *dev)
 371 {
 372         return dev->p && klist_node_attached(&dev->p->knode_driver);
 373 }
 374
 375 static void driver_bound(struct device *dev)
 376 {
 377         if (device_is_bound(dev)) {
 378                 pr_warn("%s: device %s already bound\n",
 379                         __func__, kobject_name(&dev->kobj));
 380                 return;
 381         }
 382
 383         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 384                  __func__, dev_name(dev));
 385
 386         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 387         device_links_driver_bound(dev);
 388
 389         device_pm_check_callbacks(dev);
 390
 391         /*
 392          * Make sure the device is no longer in one of the deferred lists and
 393          * kick off retrying all pending devices
 394          */
 395         driver_deferred_probe_del(dev);
 396         driver_deferred_probe_trigger();
 397
 398         if (dev->bus)
 399                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 400                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 401
 402         kobject_uevent(&dev->kobj, KOBJ_BIND);
 403 }
 404
 405 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 406                             const char *buf, size_t count)
 407 {
 408         device_lock(dev);
 409         dev->driver->coredump(dev);
 410         device_unlock(dev);
 411
 412         return count;
 413 }
 414 static DEVICE_ATTR_WO(coredump);
 415
 416 static int driver_sysfs_add(struct device *dev)
 417 {
 418         int ret;
 419
 420         if (dev->bus)
 421                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 422                                              BUS_NOTIFY_BIND_DRIVER, dev);
 423
 424         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 425                                 kobject_name(&dev->kobj));
 426         if (ret)
 427                 goto fail;
 428
 429         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 430                                 "driver");
 431         if (ret)
 432                 goto rm_dev;
 433
 434         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 435                 return 0;
 436
 437         ret = device_create_file(dev, &dev_attr_coredump);
 438         if (!ret)
 439                 return 0;
 440
 441         sysfs_remove_link(&dev->kobj, "driver");
 442
 443 rm_dev:
 444         sysfs_remove_link(&dev->driver->p->kobj,
 445                           kobject_name(&dev->kobj));
 446
 447 fail:
 448         return ret;
 449 }
 450
 451 static void driver_sysfs_remove(struct device *dev)
 452 {
 453         struct device_driver *drv = dev->driver;
 454
 455         if (drv) {
 456                 if (drv->coredump)
 457                         device_remove_file(dev, &dev_attr_coredump);
 458                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 459                 sysfs_remove_link(&dev->kobj, "driver");
 460         }
 461 }
 462
 463 /**
 464  * device_bind_driver - bind a driver to one device.
 465  * @dev: device.
 466  *
 467  * Allow manual attachment of a driver to a device.
 468  * Caller must have already set @dev->driver.
 469  *
 470  * Note that this does not modify the bus reference count.
 471  * Please verify that is accounted for before calling this.
 472  * (It is ok to call with no other effort from a driver's probe() method.)
 473  *
 474  * This function must be called with the device lock held.
 475  *
 476  * Callers should prefer to use device_driver_attach() instead.
 477  */
 478 int device_bind_driver(struct device *dev)
 479 {
 480         int ret;
 481
 482         ret = driver_sysfs_add(dev);
 483         if (!ret) {
 484                 device_links_force_bind(dev);
 485                 driver_bound(dev);
 486         }
 487         else if (dev->bus)
 488                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 489                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 490         return ret;
 491 }
 492 EXPORT_SYMBOL_GPL(device_bind_driver);
 493
 494 static atomic_t probe_count = ATOMIC_INIT(0);
 495 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 496
 497 static ssize_t state_synced_show(struct device *dev,
 498                                  struct device_attribute *attr, char *buf)
 499 {
 500         bool val;
 501
 502         device_lock(dev);
 503         val = dev->state_synced;
 504         device_unlock(dev);
 505
 506         return sysfs_emit(buf, "%u\n", val);
 507 }
 508 static DEVICE_ATTR_RO(state_synced);
 509
 510 static void device_unbind_cleanup(struct device *dev)
 511 {
 512         devres_release_all(dev);
 513         arch_teardown_dma_ops(dev);
 514         kfree(dev->dma_range_map);
 515         dev->dma_range_map = NULL;
 516         dev->driver = NULL;
 517         dev_set_drvdata(dev, NULL);
 518         if (dev->pm_domain && dev->pm_domain->dismiss)
 519                 dev->pm_domain->dismiss(dev);
 520         pm_runtime_reinit(dev);
 521         dev_pm_set_driver_flags(dev, 0);
 522 }
 523
 524 static void device_remove(struct device *dev)
 525 {
 526         device_remove_file(dev, &dev_attr_state_synced);
 527         device_remove_groups(dev, dev->driver->dev_groups);
 528
 529         if (dev->bus && dev->bus->remove)
 530                 dev->bus->remove(dev);
 531         else if (dev->driver->remove)
 532                 dev->driver->remove(dev);
 533 }
 534
 535 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 536 {
 537         int ret = 0;
 538
 539         if (dev->bus->probe)
 540                 ret = dev->bus->probe(dev);
 541         else if (drv->probe)
 542                 ret = drv->probe(dev);
 543
 544         switch (ret) {
 545         case 0:
 546                 break;
 547         case -EPROBE_DEFER:
 548                 /* Driver requested deferred probing */
 549                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 550                 break;
 551         case -ENODEV:
 552         case -ENXIO:
 553                 pr_debug("%s: probe of %s rejects match %d\n",
 554                          drv->name, dev_name(dev), ret);
 555                 break;
 556         default:
 557                 /* driver matched but the probe failed */
 558                 pr_warn("%s: probe of %s failed with error %d\n",
 559                         drv->name, dev_name(dev), ret);
 560                 break;
 561         }
 562
 563         return ret;
 564 }
 565
 566 static int really_probe(struct device *dev, struct device_driver *drv)
 567 {
 568         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 569                            !drv->suppress_bind_attrs;
 570         int ret;
 571
 572         if (defer_all_probes) {
 573                 /*
 574                  * Value of defer_all_probes can be set only by
 575                  * device_block_probing() which, in turn, will call
 576                  * wait_for_device_probe() right after that to avoid any races.
 577                  */
 578                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 579                 return -EPROBE_DEFER;
 580         }
 581
 582         ret = device_links_check_suppliers(dev);
 583         if (ret)
 584                 return ret;
 585
 586         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 587                  drv->bus->name, __func__, drv->name, dev_name(dev));
 588         if (!list_empty(&dev->devres_head)) {
 589                 dev_crit(dev, "Resources present before probing\n");
 590                 ret = -EBUSY;
 591                 goto done;
 592         }
 593
 594 re_probe:
 595         dev->driver = drv;
 596
 597         /* If using pinctrl, bind pins now before probing */
 598         ret = pinctrl_bind_pins(dev);
 599         if (ret)
 600                 goto pinctrl_bind_failed;
 601
 602         if (dev->bus->dma_configure) {
 603                 ret = dev->bus->dma_configure(dev);
 604                 if (ret)
 605                         goto pinctrl_bind_failed;
 606         }
 607
 608         ret = driver_sysfs_add(dev);
 609         if (ret) {
 610                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 611                        __func__, dev_name(dev));
 612                 goto sysfs_failed;
 613         }
 614
 615         if (dev->pm_domain && dev->pm_domain->activate) {
 616                 ret = dev->pm_domain->activate(dev);
 617                 if (ret)
 618                         goto probe_failed;
 619         }
 620
 621         ret = call_driver_probe(dev, drv);
 622         if (ret) {
 623                 /*
 624                  * Return probe errors as positive values so that the callers
 625                  * can distinguish them from other errors.
 626                  */
 627                 ret = -ret;
 628                 goto probe_failed;
 629         }
 630
 631         ret = device_add_groups(dev, drv->dev_groups);
 632         if (ret) {
 633                 dev_err(dev, "device_add_groups() failed\n");
 634                 goto dev_groups_failed;
 635         }
 636
 637         if (dev_has_sync_state(dev)) {
 638                 ret = device_create_file(dev, &dev_attr_state_synced);
 639                 if (ret) {
 640                         dev_err(dev, "state_synced sysfs add failed\n");
 641                         goto dev_sysfs_state_synced_failed;
 642                 }
 643         }
 644
 645         if (test_remove) {
 646                 test_remove = false;
 647
 648                 device_remove(dev);
 649                 driver_sysfs_remove(dev);
 650                 device_unbind_cleanup(dev);
 651
 652                 goto re_probe;
 653         }
 654
 655         pinctrl_init_done(dev);
 656
 657         if (dev->pm_domain && dev->pm_domain->sync)
 658                 dev->pm_domain->sync(dev);
 659
 660         driver_bound(dev);
 661         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 662                  drv->bus->name, __func__, dev_name(dev), drv->name);
 663         goto done;
 664
 665 dev_sysfs_state_synced_failed:
 666 dev_groups_failed:
 667         device_remove(dev);
 668 probe_failed:
 669         driver_sysfs_remove(dev);
 670 sysfs_failed:
 671         if (dev->bus)
 672                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 673                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 674 pinctrl_bind_failed:
 675         device_links_no_driver(dev);
 676         device_unbind_cleanup(dev);
 677 done:
 678         return ret;
 679 }
 680
 681 /*
 682  * For initcall_debug, show the driver probe time.
 683  */
 684 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 685 {
 686         ktime_t calltime, rettime;
 687         int ret;
 688
 689         calltime = ktime_get();
 690         ret = really_probe(dev, drv);
 691         rettime = ktime_get();
 692         pr_debug("probe of %s returned %d after %lld usecs\n",
 693                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 694         return ret;
 695 }
 696
 697 /**
 698  * driver_probe_done
 699  * Determine if the probe sequence is finished or not.
 700  *
 701  * Should somehow figure out how to use a semaphore, not an atomic variable...
 702  */
 703 int driver_probe_done(void)
 704 {
 705         int local_probe_count = atomic_read(&probe_count);
 706
 707         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 708         if (local_probe_count)
 709                 return -EBUSY;
 710         return 0;
 711 }
 712
 713 /**
 714  * wait_for_device_probe
 715  * Wait for device probing to be completed.
 716  */
 717 void wait_for_device_probe(void)
 718 {
 719         /* wait for probe timeout */
 720         wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout);
 721
 722         /* wait for the deferred probe workqueue to finish */
 723         flush_work(&deferred_probe_work);
 724
 725         /* wait for the known devices to complete their probing */
 726         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 727         async_synchronize_full();
 728 }
 729 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 730
 731 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 732 {
 733         int ret = 0;
 734
 735         if (dev->p->dead || !device_is_registered(dev))
 736                 return -ENODEV;
 737         if (dev->driver)
 738                 return -EBUSY;
 739
 740         dev->can_match = true;
 741         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 742                  drv->bus->name, __func__, dev_name(dev), drv->name);
 743
 744         pm_runtime_get_suppliers(dev);
 745         if (dev->parent)
 746                 pm_runtime_get_sync(dev->parent);
 747
 748         pm_runtime_barrier(dev);
 749         if (initcall_debug)
 750                 ret = really_probe_debug(dev, drv);
 751         else
 752                 ret = really_probe(dev, drv);
 753         pm_request_idle(dev);
 754
 755         if (dev->parent)
 756                 pm_runtime_put(dev->parent);
 757
 758         pm_runtime_put_suppliers(dev);
 759         return ret;
 760 }
 761
 762 /**
 763  * driver_probe_device - attempt to bind device & driver together
 764  * @drv: driver to bind a device to
 765  * @dev: device to try to bind to the driver
 766  *
 767  * This function returns -ENODEV if the device is not registered, -EBUSY if it
 768  * already has a driver, 0 if the device is bound successfully and a positive
 769  * (inverted) error code for failures from the ->probe method.
 770  *
 771  * This function must be called with @dev lock held.  When called for a
 772  * USB interface, @dev->parent lock must be held as well.
 773  *
 774  * If the device has a parent, runtime-resume the parent before driver probing.
 775  */
 776 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 777 {
 778         int trigger_count = atomic_read(&deferred_trigger_count);
 779         int ret;
 780
 781         atomic_inc(&probe_count);
 782         ret = __driver_probe_device(drv, dev);
 783         if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
 784                 driver_deferred_probe_add(dev);
 785
 786                 /*
 787                  * Did a trigger occur while probing? Need to re-trigger if yes
 788                  */
 789                 if (trigger_count != atomic_read(&deferred_trigger_count) &&
 790                     !defer_all_probes)
 791                         driver_deferred_probe_trigger();
 792         }
 793         atomic_dec(&probe_count);
 794         wake_up_all(&probe_waitqueue);
 795         return ret;
 796 }
 797
 798 static inline bool cmdline_requested_async_probing(const char *drv_name)
 799 {
 800         return parse_option_str(async_probe_drv_names, drv_name);
 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         return 1;
 811 }
 812 __setup("driver_async_probe=", save_async_options);
 813
 814 bool driver_allows_async_probing(struct device_driver *drv)
 815 {
 816         switch (drv->probe_type) {
 817         case PROBE_PREFER_ASYNCHRONOUS:
 818                 return true;
 819
 820         case PROBE_FORCE_SYNCHRONOUS:
 821                 return false;
 822
 823         default:
 824                 if (cmdline_requested_async_probing(drv->name))
 825                         return true;
 826
 827                 if (module_requested_async_probing(drv->owner))
 828                         return true;
 829
 830                 return false;
 831         }
 832 }
 833
 834 struct device_attach_data {
 835         struct device *dev;
 836
 837         /*
 838          * Indicates whether we are considering asynchronous probing or
 839          * not. Only initial binding after device or driver registration
 840          * (including deferral processing) may be done asynchronously, the
 841          * rest is always synchronous, as we expect it is being done by
 842          * request from userspace.
 843          */
 844         bool check_async;
 845
 846         /*
 847          * Indicates if we are binding synchronous or asynchronous drivers.
 848          * When asynchronous probing is enabled we'll execute 2 passes
 849          * over drivers: first pass doing synchronous probing and second
 850          * doing asynchronous probing (if synchronous did not succeed -
 851          * most likely because there was no driver requiring synchronous
 852          * probing - and we found asynchronous driver during first pass).
 853          * The 2 passes are done because we can't shoot asynchronous
 854          * probe for given device and driver from bus_for_each_drv() since
 855          * driver pointer is not guaranteed to stay valid once
 856          * bus_for_each_drv() iterates to the next driver on the bus.
 857          */
 858         bool want_async;
 859
 860         /*
 861          * We'll set have_async to 'true' if, while scanning for matching
 862          * driver, we'll encounter one that requests asynchronous probing.
 863          */
 864         bool have_async;
 865 };
 866
 867 static int __device_attach_driver(struct device_driver *drv, void *_data)
 868 {
 869         struct device_attach_data *data = _data;
 870         struct device *dev = data->dev;
 871         bool async_allowed;
 872         int ret;
 873
 874         ret = driver_match_device(drv, dev);
 875         if (ret == 0) {
 876                 /* no match */
 877                 return 0;
 878         } else if (ret == -EPROBE_DEFER) {
 879                 dev_dbg(dev, "Device match requests probe deferral\n");
 880                 dev->can_match = true;
 881                 driver_deferred_probe_add(dev);
 882         } else if (ret < 0) {
 883                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 884                 return ret;
 885         } /* ret > 0 means positive match */
 886
 887         async_allowed = driver_allows_async_probing(drv);
 888
 889         if (async_allowed)
 890                 data->have_async = true;
 891
 892         if (data->check_async && async_allowed != data->want_async)
 893                 return 0;
 894
 895         /*
 896          * Ignore errors returned by ->probe so that the next driver can try
 897          * its luck.
 898          */
 899         ret = driver_probe_device(drv, dev);
 900         if (ret < 0)
 901                 return ret;
 902         return ret == 0;
 903 }
 904
 905 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 906 {
 907         struct device *dev = _dev;
 908         struct device_attach_data data = {
 909                 .dev            = dev,
 910                 .check_async    = true,
 911                 .want_async     = true,
 912         };
 913
 914         device_lock(dev);
 915
 916         /*
 917          * Check if device has already been removed or claimed. This may
 918          * happen with driver loading, device discovery/registration,
 919          * and deferred probe processing happens all at once with
 920          * multiple threads.
 921          */
 922         if (dev->p->dead || dev->driver)
 923                 goto out_unlock;
 924
 925         if (dev->parent)
 926                 pm_runtime_get_sync(dev->parent);
 927
 928         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 929         dev_dbg(dev, "async probe completed\n");
 930
 931         pm_request_idle(dev);
 932
 933         if (dev->parent)
 934                 pm_runtime_put(dev->parent);
 935 out_unlock:
 936         device_unlock(dev);
 937
 938         put_device(dev);
 939 }
 940
 941 static int __device_attach(struct device *dev, bool allow_async)
 942 {
 943         int ret = 0;
 944
 945         device_lock(dev);
 946         if (dev->p->dead) {
 947                 goto out_unlock;
 948         } else if (dev->driver) {
 949                 if (device_is_bound(dev)) {
 950                         ret = 1;
 951                         goto out_unlock;
 952                 }
 953                 ret = device_bind_driver(dev);
 954                 if (ret == 0)
 955                         ret = 1;
 956                 else {
 957                         dev->driver = NULL;
 958                         ret = 0;
 959                 }
 960         } else {
 961                 struct device_attach_data data = {
 962                         .dev = dev,
 963                         .check_async = allow_async,
 964                         .want_async = false,
 965                 };
 966
 967                 if (dev->parent)
 968                         pm_runtime_get_sync(dev->parent);
 969
 970                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 971                                         __device_attach_driver);
 972                 if (!ret && allow_async && data.have_async) {
 973                         /*
 974                          * If we could not find appropriate driver
 975                          * synchronously and we are allowed to do
 976                          * async probes and there are drivers that
 977                          * want to probe asynchronously, we'll
 978                          * try them.
 979                          */
 980                         dev_dbg(dev, "scheduling asynchronous probe\n");
 981                         get_device(dev);
 982                         async_schedule_dev(__device_attach_async_helper, dev);
 983                 } else {
 984                         pm_request_idle(dev);
 985                 }
 986
 987                 if (dev->parent)
 988                         pm_runtime_put(dev->parent);
 989         }
 990 out_unlock:
 991         device_unlock(dev);
 992         return ret;
 993 }
 994
 995 /**
 996  * device_attach - try to attach device to a driver.
 997  * @dev: device.
 998  *
 999  * Walk the list of drivers that the bus has and call
1000  * driver_probe_device() for each pair. If a compatible
1001  * pair is found, break out and return.
1002  *
1003  * Returns 1 if the device was bound to a driver;
1004  * 0 if no matching driver was found;
1005  * -ENODEV if the device is not registered.
1006  *
1007  * When called for a USB interface, @dev->parent lock must be held.
1008  */
1009 int device_attach(struct device *dev)
1010 {
1011         return __device_attach(dev, false);
1012 }
1013 EXPORT_SYMBOL_GPL(device_attach);
1014
1015 void device_initial_probe(struct device *dev)
1016 {
1017         __device_attach(dev, true);
1018 }
1019
1020 /*
1021  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1022  * @dev: Device we will update driver info for
1023  * @parent: Parent device. Needed if the bus requires parent lock
1024  *
1025  * This function will take the required locks for manipulating dev->drv.
1026  * Normally this will just be the @dev lock, but when called for a USB
1027  * interface, @parent lock will be held as well.
1028  */
1029 static void __device_driver_lock(struct device *dev, struct device *parent)
1030 {
1031         if (parent && dev->bus->need_parent_lock)
1032                 device_lock(parent);
1033         device_lock(dev);
1034 }
1035
1036 /*
1037  * __device_driver_unlock - release locks needed to manipulate dev->drv
1038  * @dev: Device we will update driver info for
1039  * @parent: Parent device. Needed if the bus requires parent lock
1040  *
1041  * This function will release the required locks for manipulating dev->drv.
1042  * Normally this will just be the @dev lock, but when called for a
1043  * USB interface, @parent lock will be released as well.
1044  */
1045 static void __device_driver_unlock(struct device *dev, struct device *parent)
1046 {
1047         device_unlock(dev);
1048         if (parent && dev->bus->need_parent_lock)
1049                 device_unlock(parent);
1050 }
1051
1052 /**
1053  * device_driver_attach - attach a specific driver to a specific device
1054  * @drv: Driver to attach
1055  * @dev: Device to attach it to
1056  *
1057  * Manually attach driver to a device. Will acquire both @dev lock and
1058  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1059  */
1060 int device_driver_attach(struct device_driver *drv, struct device *dev)
1061 {
1062         int ret;
1063
1064         __device_driver_lock(dev, dev->parent);
1065         ret = __driver_probe_device(drv, dev);
1066         __device_driver_unlock(dev, dev->parent);
1067
1068         /* also return probe errors as normal negative errnos */
1069         if (ret > 0)
1070                 ret = -ret;
1071         if (ret == -EPROBE_DEFER)
1072                 return -EAGAIN;
1073         return ret;
1074 }
1075 EXPORT_SYMBOL_GPL(device_driver_attach);
1076
1077 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1078 {
1079         struct device *dev = _dev;
1080         struct device_driver *drv;
1081         int ret;
1082
1083         __device_driver_lock(dev, dev->parent);
1084         drv = dev->p->async_driver;
1085         ret = driver_probe_device(drv, dev);
1086         __device_driver_unlock(dev, dev->parent);
1087
1088         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1089
1090         put_device(dev);
1091 }
1092
1093 static int __driver_attach(struct device *dev, void *data)
1094 {
1095         struct device_driver *drv = data;
1096         int ret;
1097
1098         /*
1099          * Lock device and try to bind to it. We drop the error
1100          * here and always return 0, because we need to keep trying
1101          * to bind to devices and some drivers will return an error
1102          * simply if it didn't support the device.
1103          *
1104          * driver_probe_device() will spit a warning if there
1105          * is an error.
1106          */
1107
1108         ret = driver_match_device(drv, dev);
1109         if (ret == 0) {
1110                 /* no match */
1111                 return 0;
1112         } else if (ret == -EPROBE_DEFER) {
1113                 dev_dbg(dev, "Device match requests probe deferral\n");
1114                 dev->can_match = true;
1115                 driver_deferred_probe_add(dev);
1116         } else if (ret < 0) {
1117                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1118                 return ret;
1119         } /* ret > 0 means positive match */
1120
1121         if (driver_allows_async_probing(drv)) {
1122                 /*
1123                  * Instead of probing the device synchronously we will
1124                  * probe it asynchronously to allow for more parallelism.
1125                  *
1126                  * We only take the device lock here in order to guarantee
1127                  * that the dev->driver and async_driver fields are protected
1128                  */
1129                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1130                 device_lock(dev);
1131                 if (!dev->driver) {
1132                         get_device(dev);
1133                         dev->p->async_driver = drv;
1134                         async_schedule_dev(__driver_attach_async_helper, dev);
1135                 }
1136                 device_unlock(dev);
1137                 return 0;
1138         }
1139
1140         __device_driver_lock(dev, dev->parent);
1141         driver_probe_device(drv, dev);
1142         __device_driver_unlock(dev, dev->parent);
1143
1144         return 0;
1145 }
1146
1147 /**
1148  * driver_attach - try to bind driver to devices.
1149  * @drv: driver.
1150  *
1151  * Walk the list of devices that the bus has on it and try to
1152  * match the driver with each one.  If driver_probe_device()
1153  * returns 0 and the @dev->driver is set, we've found a
1154  * compatible pair.
1155  */
1156 int driver_attach(struct device_driver *drv)
1157 {
1158         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1159 }
1160 EXPORT_SYMBOL_GPL(driver_attach);
1161
1162 /*
1163  * __device_release_driver() must be called with @dev lock held.
1164  * When called for a USB interface, @dev->parent lock must be held as well.
1165  */
1166 static void __device_release_driver(struct device *dev, struct device *parent)
1167 {
1168         struct device_driver *drv;
1169
1170         drv = dev->driver;
1171         if (drv) {
1172                 pm_runtime_get_sync(dev);
1173
1174                 while (device_links_busy(dev)) {
1175                         __device_driver_unlock(dev, parent);
1176
1177                         device_links_unbind_consumers(dev);
1178
1179                         __device_driver_lock(dev, parent);
1180                         /*
1181                          * A concurrent invocation of the same function might
1182                          * have released the driver successfully while this one
1183                          * was waiting, so check for that.
1184                          */
1185                         if (dev->driver != drv) {
1186                                 pm_runtime_put(dev);
1187                                 return;
1188                         }
1189                 }
1190
1191                 driver_sysfs_remove(dev);
1192
1193                 if (dev->bus)
1194                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1195                                                      BUS_NOTIFY_UNBIND_DRIVER,
1196                                                      dev);
1197
1198                 pm_runtime_put_sync(dev);
1199
1200                 device_remove(dev);
1201
1202                 device_links_driver_cleanup(dev);
1203                 device_unbind_cleanup(dev);
1204
1205                 klist_remove(&dev->p->knode_driver);
1206                 device_pm_check_callbacks(dev);
1207                 if (dev->bus)
1208                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1209                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1210                                                      dev);
1211
1212                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1213         }
1214 }
1215
1216 void device_release_driver_internal(struct device *dev,
1217                                     struct device_driver *drv,
1218                                     struct device *parent)
1219 {
1220         __device_driver_lock(dev, parent);
1221
1222         if (!drv || drv == dev->driver)
1223                 __device_release_driver(dev, parent);
1224
1225         __device_driver_unlock(dev, parent);
1226 }
1227
1228 /**
1229  * device_release_driver - manually detach device from driver.
1230  * @dev: device.
1231  *
1232  * Manually detach device from driver.
1233  * When called for a USB interface, @dev->parent lock must be held.
1234  *
1235  * If this function is to be called with @dev->parent lock held, ensure that
1236  * the device's consumers are unbound in advance or that their locks can be
1237  * acquired under the @dev->parent lock.
1238  */
1239 void device_release_driver(struct device *dev)
1240 {
1241         /*
1242          * If anyone calls device_release_driver() recursively from
1243          * within their ->remove callback for the same device, they
1244          * will deadlock right here.
1245          */
1246         device_release_driver_internal(dev, NULL, NULL);
1247 }
1248 EXPORT_SYMBOL_GPL(device_release_driver);
1249
1250 /**
1251  * device_driver_detach - detach driver from a specific device
1252  * @dev: device to detach driver from
1253  *
1254  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1255  * lock if needed.
1256  */
1257 void device_driver_detach(struct device *dev)
1258 {
1259         device_release_driver_internal(dev, NULL, dev->parent);
1260 }
1261
1262 /**
1263  * driver_detach - detach driver from all devices it controls.
1264  * @drv: driver.
1265  */
1266 void driver_detach(struct device_driver *drv)
1267 {
1268         struct device_private *dev_prv;
1269         struct device *dev;
1270
1271         if (driver_allows_async_probing(drv))
1272                 async_synchronize_full();
1273
1274         for (;;) {
1275                 spin_lock(&drv->p->klist_devices.k_lock);
1276                 if (list_empty(&drv->p->klist_devices.k_list)) {
1277                         spin_unlock(&drv->p->klist_devices.k_lock);
1278                         break;
1279                 }
1280                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1281                                      struct device_private,
1282                                      knode_driver.n_node);
1283                 dev = dev_prv->device;
1284                 get_device(dev);
1285                 spin_unlock(&drv->p->klist_devices.k_lock);
1286                 device_release_driver_internal(dev, drv, dev->parent);
1287                 put_device(dev);
1288         }
1289 }