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 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 static int driver_deferred_probe_timeout = 10;
 261 #else
 262 static int driver_deferred_probe_timeout;
 263 #endif
 264
 265 static int __init deferred_probe_timeout_setup(char *str)
 266 {
 267         int timeout;
 268
 269         if (!kstrtoint(str, 10, &timeout))
 270                 driver_deferred_probe_timeout = timeout;
 271         return 1;
 272 }
 273 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 274
 275 /**
 276  * driver_deferred_probe_check_state() - Check deferred probe state
 277  * @dev: device to check
 278  *
 279  * Return:
 280  * * -ENODEV if initcalls have completed and modules are disabled.
 281  * * -ETIMEDOUT if the deferred probe timeout was set and has expired
 282  *   and modules are enabled.
 283  * * -EPROBE_DEFER in other cases.
 284  *
 285  * Drivers or subsystems can opt-in to calling this function instead of directly
 286  * returning -EPROBE_DEFER.
 287  */
 288 int driver_deferred_probe_check_state(struct device *dev)
 289 {
 290         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 291                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 292                 return -ENODEV;
 293         }
 294
 295         if (!driver_deferred_probe_timeout && initcalls_done) {
 296                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 297                 return -ETIMEDOUT;
 298         }
 299
 300         return -EPROBE_DEFER;
 301 }
 302 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
 303
 304 static void deferred_probe_timeout_work_func(struct work_struct *work)
 305 {
 306         struct device_private *p;
 307
 308         fw_devlink_drivers_done();
 309
 310         driver_deferred_probe_timeout = 0;
 311         driver_deferred_probe_trigger();
 312         flush_work(&deferred_probe_work);
 313
 314         mutex_lock(&deferred_probe_mutex);
 315         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 316                 dev_info(p->device, "deferred probe pending\n");
 317         mutex_unlock(&deferred_probe_mutex);
 318
 319         fw_devlink_probing_done();
 320 }
 321 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 322
 323 void deferred_probe_extend_timeout(void)
 324 {
 325         /*
 326          * If the work hasn't been queued yet or if the work expired, don't
 327          * start a new one.
 328          */
 329         if (cancel_delayed_work(&deferred_probe_timeout_work)) {
 330                 schedule_delayed_work(&deferred_probe_timeout_work,
 331                                 driver_deferred_probe_timeout * HZ);
 332                 pr_debug("Extended deferred probe timeout by %d secs\n",
 333                                         driver_deferred_probe_timeout);
 334         }
 335 }
 336
 337 /**
 338  * deferred_probe_initcall() - Enable probing of deferred devices
 339  *
 340  * We don't want to get in the way when the bulk of drivers are getting probed.
 341  * Instead, this initcall makes sure that deferred probing is delayed until
 342  * late_initcall time.
 343  */
 344 static int deferred_probe_initcall(void)
 345 {
 346         debugfs_create_file("devices_deferred", 0444, NULL, NULL,
 347                             &deferred_devs_fops);
 348
 349         driver_deferred_probe_enable = true;
 350         driver_deferred_probe_trigger();
 351         /* Sort as many dependencies as possible before exiting initcalls */
 352         flush_work(&deferred_probe_work);
 353         initcalls_done = true;
 354
 355         if (!IS_ENABLED(CONFIG_MODULES))
 356                 fw_devlink_drivers_done();
 357
 358         /*
 359          * Trigger deferred probe again, this time we won't defer anything
 360          * that is optional
 361          */
 362         driver_deferred_probe_trigger();
 363         flush_work(&deferred_probe_work);
 364
 365         if (driver_deferred_probe_timeout > 0) {
 366                 schedule_delayed_work(&deferred_probe_timeout_work,
 367                         driver_deferred_probe_timeout * HZ);
 368         }
 369
 370         if (!IS_ENABLED(CONFIG_MODULES))
 371                 fw_devlink_probing_done();
 372
 373         return 0;
 374 }
 375 late_initcall(deferred_probe_initcall);
 376
 377 static void __exit deferred_probe_exit(void)
 378 {
 379         debugfs_lookup_and_remove("devices_deferred", NULL);
 380 }
 381 __exitcall(deferred_probe_exit);
 382
 383 /**
 384  * device_is_bound() - Check if device is bound to a driver
 385  * @dev: device to check
 386  *
 387  * Returns true if passed device has already finished probing successfully
 388  * against a driver.
 389  *
 390  * This function must be called with the device lock held.
 391  */
 392 bool device_is_bound(struct device *dev)
 393 {
 394         return dev->p && klist_node_attached(&dev->p->knode_driver);
 395 }
 396
 397 static void driver_bound(struct device *dev)
 398 {
 399         if (device_is_bound(dev)) {
 400                 pr_warn("%s: device %s already bound\n",
 401                         __func__, kobject_name(&dev->kobj));
 402                 return;
 403         }
 404
 405         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 406                  __func__, dev_name(dev));
 407
 408         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 409         device_links_driver_bound(dev);
 410
 411         device_pm_check_callbacks(dev);
 412
 413         /*
 414          * Make sure the device is no longer in one of the deferred lists and
 415          * kick off retrying all pending devices
 416          */
 417         driver_deferred_probe_del(dev);
 418         driver_deferred_probe_trigger();
 419
 420         bus_notify(dev, BUS_NOTIFY_BOUND_DRIVER);
 421         kobject_uevent(&dev->kobj, KOBJ_BIND);
 422 }
 423
 424 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 425                             const char *buf, size_t count)
 426 {
 427         device_lock(dev);
 428         dev->driver->coredump(dev);
 429         device_unlock(dev);
 430
 431         return count;
 432 }
 433 static DEVICE_ATTR_WO(coredump);
 434
 435 static int driver_sysfs_add(struct device *dev)
 436 {
 437         int ret;
 438
 439         bus_notify(dev, BUS_NOTIFY_BIND_DRIVER);
 440
 441         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 442                                 kobject_name(&dev->kobj));
 443         if (ret)
 444                 goto fail;
 445
 446         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 447                                 "driver");
 448         if (ret)
 449                 goto rm_dev;
 450
 451         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 452                 return 0;
 453
 454         ret = device_create_file(dev, &dev_attr_coredump);
 455         if (!ret)
 456                 return 0;
 457
 458         sysfs_remove_link(&dev->kobj, "driver");
 459
 460 rm_dev:
 461         sysfs_remove_link(&dev->driver->p->kobj,
 462                           kobject_name(&dev->kobj));
 463
 464 fail:
 465         return ret;
 466 }
 467
 468 static void driver_sysfs_remove(struct device *dev)
 469 {
 470         struct device_driver *drv = dev->driver;
 471
 472         if (drv) {
 473                 if (drv->coredump)
 474                         device_remove_file(dev, &dev_attr_coredump);
 475                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 476                 sysfs_remove_link(&dev->kobj, "driver");
 477         }
 478 }
 479
 480 /**
 481  * device_bind_driver - bind a driver to one device.
 482  * @dev: device.
 483  *
 484  * Allow manual attachment of a driver to a device.
 485  * Caller must have already set @dev->driver.
 486  *
 487  * Note that this does not modify the bus reference count.
 488  * Please verify that is accounted for before calling this.
 489  * (It is ok to call with no other effort from a driver's probe() method.)
 490  *
 491  * This function must be called with the device lock held.
 492  *
 493  * Callers should prefer to use device_driver_attach() instead.
 494  */
 495 int device_bind_driver(struct device *dev)
 496 {
 497         int ret;
 498
 499         ret = driver_sysfs_add(dev);
 500         if (!ret) {
 501                 device_links_force_bind(dev);
 502                 driver_bound(dev);
 503         }
 504         else
 505                 bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
 506         return ret;
 507 }
 508 EXPORT_SYMBOL_GPL(device_bind_driver);
 509
 510 static atomic_t probe_count = ATOMIC_INIT(0);
 511 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 512
 513 static ssize_t state_synced_store(struct device *dev,
 514                                   struct device_attribute *attr,
 515                                   const char *buf, size_t count)
 516 {
 517         int ret = 0;
 518
 519         if (strcmp("1", buf))
 520                 return -EINVAL;
 521
 522         device_lock(dev);
 523         if (!dev->state_synced) {
 524                 dev->state_synced = true;
 525                 dev_sync_state(dev);
 526         } else {
 527                 ret = -EINVAL;
 528         }
 529         device_unlock(dev);
 530
 531         return ret ? ret : count;
 532 }
 533
 534 static ssize_t state_synced_show(struct device *dev,
 535                                  struct device_attribute *attr, char *buf)
 536 {
 537         bool val;
 538
 539         device_lock(dev);
 540         val = dev->state_synced;
 541         device_unlock(dev);
 542
 543         return sysfs_emit(buf, "%u\n", val);
 544 }
 545 static DEVICE_ATTR_RW(state_synced);
 546
 547 static void device_unbind_cleanup(struct device *dev)
 548 {
 549         devres_release_all(dev);
 550         arch_teardown_dma_ops(dev);
 551         kfree(dev->dma_range_map);
 552         dev->dma_range_map = NULL;
 553         dev->driver = NULL;
 554         dev_set_drvdata(dev, NULL);
 555         if (dev->pm_domain && dev->pm_domain->dismiss)
 556                 dev->pm_domain->dismiss(dev);
 557         pm_runtime_reinit(dev);
 558         dev_pm_set_driver_flags(dev, 0);
 559 }
 560
 561 static void device_remove(struct device *dev)
 562 {
 563         device_remove_file(dev, &dev_attr_state_synced);
 564         device_remove_groups(dev, dev->driver->dev_groups);
 565
 566         if (dev->bus && dev->bus->remove)
 567                 dev->bus->remove(dev);
 568         else if (dev->driver->remove)
 569                 dev->driver->remove(dev);
 570 }
 571
 572 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 573 {
 574         int ret = 0;
 575
 576         if (dev->bus->probe)
 577                 ret = dev->bus->probe(dev);
 578         else if (drv->probe)
 579                 ret = drv->probe(dev);
 580
 581         switch (ret) {
 582         case 0:
 583                 break;
 584         case -EPROBE_DEFER:
 585                 /* Driver requested deferred probing */
 586                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 587                 break;
 588         case -ENODEV:
 589         case -ENXIO:
 590                 pr_debug("%s: probe of %s rejects match %d\n",
 591                          drv->name, dev_name(dev), ret);
 592                 break;
 593         default:
 594                 /* driver matched but the probe failed */
 595                 pr_warn("%s: probe of %s failed with error %d\n",
 596                         drv->name, dev_name(dev), ret);
 597                 break;
 598         }
 599
 600         return ret;
 601 }
 602
 603 static int really_probe(struct device *dev, struct device_driver *drv)
 604 {
 605         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 606                            !drv->suppress_bind_attrs;
 607         int ret, link_ret;
 608
 609         if (defer_all_probes) {
 610                 /*
 611                  * Value of defer_all_probes can be set only by
 612                  * device_block_probing() which, in turn, will call
 613                  * wait_for_device_probe() right after that to avoid any races.
 614                  */
 615                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 616                 return -EPROBE_DEFER;
 617         }
 618
 619         link_ret = device_links_check_suppliers(dev);
 620         if (link_ret == -EPROBE_DEFER)
 621                 return link_ret;
 622
 623         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 624                  drv->bus->name, __func__, drv->name, dev_name(dev));
 625         if (!list_empty(&dev->devres_head)) {
 626                 dev_crit(dev, "Resources present before probing\n");
 627                 ret = -EBUSY;
 628                 goto done;
 629         }
 630
 631 re_probe:
 632         dev->driver = drv;
 633
 634         /* If using pinctrl, bind pins now before probing */
 635         ret = pinctrl_bind_pins(dev);
 636         if (ret)
 637                 goto pinctrl_bind_failed;
 638
 639         if (dev->bus->dma_configure) {
 640                 ret = dev->bus->dma_configure(dev);
 641                 if (ret)
 642                         goto pinctrl_bind_failed;
 643         }
 644
 645         ret = driver_sysfs_add(dev);
 646         if (ret) {
 647                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 648                        __func__, dev_name(dev));
 649                 goto sysfs_failed;
 650         }
 651
 652         if (dev->pm_domain && dev->pm_domain->activate) {
 653                 ret = dev->pm_domain->activate(dev);
 654                 if (ret)
 655                         goto probe_failed;
 656         }
 657
 658         ret = call_driver_probe(dev, drv);
 659         if (ret) {
 660                 /*
 661                  * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
 662                  * device might actually probe properly once some of its missing
 663                  * suppliers have probed. So, treat this as if the driver
 664                  * returned -EPROBE_DEFER.
 665                  */
 666                 if (link_ret == -EAGAIN)
 667                         ret = -EPROBE_DEFER;
 668
 669                 /*
 670                  * Return probe errors as positive values so that the callers
 671                  * can distinguish them from other errors.
 672                  */
 673                 ret = -ret;
 674                 goto probe_failed;
 675         }
 676
 677         ret = device_add_groups(dev, drv->dev_groups);
 678         if (ret) {
 679                 dev_err(dev, "device_add_groups() failed\n");
 680                 goto dev_groups_failed;
 681         }
 682
 683         if (dev_has_sync_state(dev)) {
 684                 ret = device_create_file(dev, &dev_attr_state_synced);
 685                 if (ret) {
 686                         dev_err(dev, "state_synced sysfs add failed\n");
 687                         goto dev_sysfs_state_synced_failed;
 688                 }
 689         }
 690
 691         if (test_remove) {
 692                 test_remove = false;
 693
 694                 device_remove(dev);
 695                 driver_sysfs_remove(dev);
 696                 if (dev->bus && dev->bus->dma_cleanup)
 697                         dev->bus->dma_cleanup(dev);
 698                 device_unbind_cleanup(dev);
 699
 700                 goto re_probe;
 701         }
 702
 703         pinctrl_init_done(dev);
 704
 705         if (dev->pm_domain && dev->pm_domain->sync)
 706                 dev->pm_domain->sync(dev);
 707
 708         driver_bound(dev);
 709         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 710                  drv->bus->name, __func__, dev_name(dev), drv->name);
 711         goto done;
 712
 713 dev_sysfs_state_synced_failed:
 714 dev_groups_failed:
 715         device_remove(dev);
 716 probe_failed:
 717         driver_sysfs_remove(dev);
 718 sysfs_failed:
 719         bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
 720         if (dev->bus && dev->bus->dma_cleanup)
 721                 dev->bus->dma_cleanup(dev);
 722 pinctrl_bind_failed:
 723         device_links_no_driver(dev);
 724         device_unbind_cleanup(dev);
 725 done:
 726         return ret;
 727 }
 728
 729 /*
 730  * For initcall_debug, show the driver probe time.
 731  */
 732 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 733 {
 734         ktime_t calltime, rettime;
 735         int ret;
 736
 737         calltime = ktime_get();
 738         ret = really_probe(dev, drv);
 739         rettime = ktime_get();
 740         /*
 741          * Don't change this to pr_debug() because that requires
 742          * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the
 743          * kernel commandline to print this all the time at the debug level.
 744          */
 745         printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
 746                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 747         return ret;
 748 }
 749
 750 /**
 751  * driver_probe_done
 752  * Determine if the probe sequence is finished or not.
 753  *
 754  * Should somehow figure out how to use a semaphore, not an atomic variable...
 755  */
 756 bool __init driver_probe_done(void)
 757 {
 758         int local_probe_count = atomic_read(&probe_count);
 759
 760         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 761         return !local_probe_count;
 762 }
 763
 764 /**
 765  * wait_for_device_probe
 766  * Wait for device probing to be completed.
 767  */
 768 void wait_for_device_probe(void)
 769 {
 770         /* wait for the deferred probe workqueue to finish */
 771         flush_work(&deferred_probe_work);
 772
 773         /* wait for the known devices to complete their probing */
 774         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 775         async_synchronize_full();
 776 }
 777 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 778
 779 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 780 {
 781         int ret = 0;
 782
 783         if (dev->p->dead || !device_is_registered(dev))
 784                 return -ENODEV;
 785         if (dev->driver)
 786                 return -EBUSY;
 787
 788         dev->can_match = true;
 789         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 790                  drv->bus->name, __func__, dev_name(dev), drv->name);
 791
 792         pm_runtime_get_suppliers(dev);
 793         if (dev->parent)
 794                 pm_runtime_get_sync(dev->parent);
 795
 796         pm_runtime_barrier(dev);
 797         if (initcall_debug)
 798                 ret = really_probe_debug(dev, drv);
 799         else
 800                 ret = really_probe(dev, drv);
 801         pm_request_idle(dev);
 802
 803         if (dev->parent)
 804                 pm_runtime_put(dev->parent);
 805
 806         pm_runtime_put_suppliers(dev);
 807         return ret;
 808 }
 809
 810 /**
 811  * driver_probe_device - attempt to bind device & driver together
 812  * @drv: driver to bind a device to
 813  * @dev: device to try to bind to the driver
 814  *
 815  * This function returns -ENODEV if the device is not registered, -EBUSY if it
 816  * already has a driver, 0 if the device is bound successfully and a positive
 817  * (inverted) error code for failures from the ->probe method.
 818  *
 819  * This function must be called with @dev lock held.  When called for a
 820  * USB interface, @dev->parent lock must be held as well.
 821  *
 822  * If the device has a parent, runtime-resume the parent before driver probing.
 823  */
 824 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 825 {
 826         int trigger_count = atomic_read(&deferred_trigger_count);
 827         int ret;
 828
 829         atomic_inc(&probe_count);
 830         ret = __driver_probe_device(drv, dev);
 831         if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
 832                 driver_deferred_probe_add(dev);
 833
 834                 /*
 835                  * Did a trigger occur while probing? Need to re-trigger if yes
 836                  */
 837                 if (trigger_count != atomic_read(&deferred_trigger_count) &&
 838                     !defer_all_probes)
 839                         driver_deferred_probe_trigger();
 840         }
 841         atomic_dec(&probe_count);
 842         wake_up_all(&probe_waitqueue);
 843         return ret;
 844 }
 845
 846 static inline bool cmdline_requested_async_probing(const char *drv_name)
 847 {
 848         bool async_drv;
 849
 850         async_drv = parse_option_str(async_probe_drv_names, drv_name);
 851
 852         return (async_probe_default != async_drv);
 853 }
 854
 855 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 856 static int __init save_async_options(char *buf)
 857 {
 858         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 859                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 860
 861         strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 862         async_probe_default = parse_option_str(async_probe_drv_names, "*");
 863
 864         return 1;
 865 }
 866 __setup("driver_async_probe=", save_async_options);
 867
 868 static bool driver_allows_async_probing(struct device_driver *drv)
 869 {
 870         switch (drv->probe_type) {
 871         case PROBE_PREFER_ASYNCHRONOUS:
 872                 return true;
 873
 874         case PROBE_FORCE_SYNCHRONOUS:
 875                 return false;
 876
 877         default:
 878                 if (cmdline_requested_async_probing(drv->name))
 879                         return true;
 880
 881                 if (module_requested_async_probing(drv->owner))
 882                         return true;
 883
 884                 return false;
 885         }
 886 }
 887
 888 struct device_attach_data {
 889         struct device *dev;
 890
 891         /*
 892          * Indicates whether we are considering asynchronous probing or
 893          * not. Only initial binding after device or driver registration
 894          * (including deferral processing) may be done asynchronously, the
 895          * rest is always synchronous, as we expect it is being done by
 896          * request from userspace.
 897          */
 898         bool check_async;
 899
 900         /*
 901          * Indicates if we are binding synchronous or asynchronous drivers.
 902          * When asynchronous probing is enabled we'll execute 2 passes
 903          * over drivers: first pass doing synchronous probing and second
 904          * doing asynchronous probing (if synchronous did not succeed -
 905          * most likely because there was no driver requiring synchronous
 906          * probing - and we found asynchronous driver during first pass).
 907          * The 2 passes are done because we can't shoot asynchronous
 908          * probe for given device and driver from bus_for_each_drv() since
 909          * driver pointer is not guaranteed to stay valid once
 910          * bus_for_each_drv() iterates to the next driver on the bus.
 911          */
 912         bool want_async;
 913
 914         /*
 915          * We'll set have_async to 'true' if, while scanning for matching
 916          * driver, we'll encounter one that requests asynchronous probing.
 917          */
 918         bool have_async;
 919 };
 920
 921 static int __device_attach_driver(struct device_driver *drv, void *_data)
 922 {
 923         struct device_attach_data *data = _data;
 924         struct device *dev = data->dev;
 925         bool async_allowed;
 926         int ret;
 927
 928         ret = driver_match_device(drv, dev);
 929         if (ret == 0) {
 930                 /* no match */
 931                 return 0;
 932         } else if (ret == -EPROBE_DEFER) {
 933                 dev_dbg(dev, "Device match requests probe deferral\n");
 934                 dev->can_match = true;
 935                 driver_deferred_probe_add(dev);
 936                 /*
 937                  * Device can't match with a driver right now, so don't attempt
 938                  * to match or bind with other drivers on the bus.
 939                  */
 940                 return ret;
 941         } else if (ret < 0) {
 942                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 943                 return ret;
 944         } /* ret > 0 means positive match */
 945
 946         async_allowed = driver_allows_async_probing(drv);
 947
 948         if (async_allowed)
 949                 data->have_async = true;
 950
 951         if (data->check_async && async_allowed != data->want_async)
 952                 return 0;
 953
 954         /*
 955          * Ignore errors returned by ->probe so that the next driver can try
 956          * its luck.
 957          */
 958         ret = driver_probe_device(drv, dev);
 959         if (ret < 0)
 960                 return ret;
 961         return ret == 0;
 962 }
 963
 964 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 965 {
 966         struct device *dev = _dev;
 967         struct device_attach_data data = {
 968                 .dev            = dev,
 969                 .check_async    = true,
 970                 .want_async     = true,
 971         };
 972
 973         device_lock(dev);
 974
 975         /*
 976          * Check if device has already been removed or claimed. This may
 977          * happen with driver loading, device discovery/registration,
 978          * and deferred probe processing happens all at once with
 979          * multiple threads.
 980          */
 981         if (dev->p->dead || dev->driver)
 982                 goto out_unlock;
 983
 984         if (dev->parent)
 985                 pm_runtime_get_sync(dev->parent);
 986
 987         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 988         dev_dbg(dev, "async probe completed\n");
 989
 990         pm_request_idle(dev);
 991
 992         if (dev->parent)
 993                 pm_runtime_put(dev->parent);
 994 out_unlock:
 995         device_unlock(dev);
 996
 997         put_device(dev);
 998 }
 999
1000 static int __device_attach(struct device *dev, bool allow_async)
1001 {
1002         int ret = 0;
1003         bool async = false;
1004
1005         device_lock(dev);
1006         if (dev->p->dead) {
1007                 goto out_unlock;
1008         } else if (dev->driver) {
1009                 if (device_is_bound(dev)) {
1010                         ret = 1;
1011                         goto out_unlock;
1012                 }
1013                 ret = device_bind_driver(dev);
1014                 if (ret == 0)
1015                         ret = 1;
1016                 else {
1017                         dev->driver = NULL;
1018                         ret = 0;
1019                 }
1020         } else {
1021                 struct device_attach_data data = {
1022                         .dev = dev,
1023                         .check_async = allow_async,
1024                         .want_async = false,
1025                 };
1026
1027                 if (dev->parent)
1028                         pm_runtime_get_sync(dev->parent);
1029
1030                 ret = bus_for_each_drv(dev->bus, NULL, &data,
1031                                         __device_attach_driver);
1032                 if (!ret && allow_async && data.have_async) {
1033                         /*
1034                          * If we could not find appropriate driver
1035                          * synchronously and we are allowed to do
1036                          * async probes and there are drivers that
1037                          * want to probe asynchronously, we'll
1038                          * try them.
1039                          */
1040                         dev_dbg(dev, "scheduling asynchronous probe\n");
1041                         get_device(dev);
1042                         async = true;
1043                 } else {
1044                         pm_request_idle(dev);
1045                 }
1046
1047                 if (dev->parent)
1048                         pm_runtime_put(dev->parent);
1049         }
1050 out_unlock:
1051         device_unlock(dev);
1052         if (async)
1053                 async_schedule_dev(__device_attach_async_helper, dev);
1054         return ret;
1055 }
1056
1057 /**
1058  * device_attach - try to attach device to a driver.
1059  * @dev: device.
1060  *
1061  * Walk the list of drivers that the bus has and call
1062  * driver_probe_device() for each pair. If a compatible
1063  * pair is found, break out and return.
1064  *
1065  * Returns 1 if the device was bound to a driver;
1066  * 0 if no matching driver was found;
1067  * -ENODEV if the device is not registered.
1068  *
1069  * When called for a USB interface, @dev->parent lock must be held.
1070  */
1071 int device_attach(struct device *dev)
1072 {
1073         return __device_attach(dev, false);
1074 }
1075 EXPORT_SYMBOL_GPL(device_attach);
1076
1077 void device_initial_probe(struct device *dev)
1078 {
1079         __device_attach(dev, true);
1080 }
1081
1082 /*
1083  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1084  * @dev: Device we will update driver info for
1085  * @parent: Parent device. Needed if the bus requires parent lock
1086  *
1087  * This function will take the required locks for manipulating dev->drv.
1088  * Normally this will just be the @dev lock, but when called for a USB
1089  * interface, @parent lock will be held as well.
1090  */
1091 static void __device_driver_lock(struct device *dev, struct device *parent)
1092 {
1093         if (parent && dev->bus->need_parent_lock)
1094                 device_lock(parent);
1095         device_lock(dev);
1096 }
1097
1098 /*
1099  * __device_driver_unlock - release locks needed to manipulate dev->drv
1100  * @dev: Device we will update driver info for
1101  * @parent: Parent device. Needed if the bus requires parent lock
1102  *
1103  * This function will release the required locks for manipulating dev->drv.
1104  * Normally this will just be the @dev lock, but when called for a
1105  * USB interface, @parent lock will be released as well.
1106  */
1107 static void __device_driver_unlock(struct device *dev, struct device *parent)
1108 {
1109         device_unlock(dev);
1110         if (parent && dev->bus->need_parent_lock)
1111                 device_unlock(parent);
1112 }
1113
1114 /**
1115  * device_driver_attach - attach a specific driver to a specific device
1116  * @drv: Driver to attach
1117  * @dev: Device to attach it to
1118  *
1119  * Manually attach driver to a device. Will acquire both @dev lock and
1120  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1121  */
1122 int device_driver_attach(struct device_driver *drv, struct device *dev)
1123 {
1124         int ret;
1125
1126         __device_driver_lock(dev, dev->parent);
1127         ret = __driver_probe_device(drv, dev);
1128         __device_driver_unlock(dev, dev->parent);
1129
1130         /* also return probe errors as normal negative errnos */
1131         if (ret > 0)
1132                 ret = -ret;
1133         if (ret == -EPROBE_DEFER)
1134                 return -EAGAIN;
1135         return ret;
1136 }
1137 EXPORT_SYMBOL_GPL(device_driver_attach);
1138
1139 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1140 {
1141         struct device *dev = _dev;
1142         struct device_driver *drv;
1143         int ret;
1144
1145         __device_driver_lock(dev, dev->parent);
1146         drv = dev->p->async_driver;
1147         dev->p->async_driver = NULL;
1148         ret = driver_probe_device(drv, dev);
1149         __device_driver_unlock(dev, dev->parent);
1150
1151         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1152
1153         put_device(dev);
1154 }
1155
1156 static int __driver_attach(struct device *dev, void *data)
1157 {
1158         struct device_driver *drv = data;
1159         bool async = false;
1160         int ret;
1161
1162         /*
1163          * Lock device and try to bind to it. We drop the error
1164          * here and always return 0, because we need to keep trying
1165          * to bind to devices and some drivers will return an error
1166          * simply if it didn't support the device.
1167          *
1168          * driver_probe_device() will spit a warning if there
1169          * is an error.
1170          */
1171
1172         ret = driver_match_device(drv, dev);
1173         if (ret == 0) {
1174                 /* no match */
1175                 return 0;
1176         } else if (ret == -EPROBE_DEFER) {
1177                 dev_dbg(dev, "Device match requests probe deferral\n");
1178                 dev->can_match = true;
1179                 driver_deferred_probe_add(dev);
1180                 /*
1181                  * Driver could not match with device, but may match with
1182                  * another device on the bus.
1183                  */
1184                 return 0;
1185         } else if (ret < 0) {
1186                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1187                 /*
1188                  * Driver could not match with device, but may match with
1189                  * another device on the bus.
1190                  */
1191                 return 0;
1192         } /* ret > 0 means positive match */
1193
1194         if (driver_allows_async_probing(drv)) {
1195                 /*
1196                  * Instead of probing the device synchronously we will
1197                  * probe it asynchronously to allow for more parallelism.
1198                  *
1199                  * We only take the device lock here in order to guarantee
1200                  * that the dev->driver and async_driver fields are protected
1201                  */
1202                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1203                 device_lock(dev);
1204                 if (!dev->driver && !dev->p->async_driver) {
1205                         get_device(dev);
1206                         dev->p->async_driver = drv;
1207                         async = true;
1208                 }
1209                 device_unlock(dev);
1210                 if (async)
1211                         async_schedule_dev(__driver_attach_async_helper, dev);
1212                 return 0;
1213         }
1214
1215         __device_driver_lock(dev, dev->parent);
1216         driver_probe_device(drv, dev);
1217         __device_driver_unlock(dev, dev->parent);
1218
1219         return 0;
1220 }
1221
1222 /**
1223  * driver_attach - try to bind driver to devices.
1224  * @drv: driver.
1225  *
1226  * Walk the list of devices that the bus has on it and try to
1227  * match the driver with each one.  If driver_probe_device()
1228  * returns 0 and the @dev->driver is set, we've found a
1229  * compatible pair.
1230  */
1231 int driver_attach(struct device_driver *drv)
1232 {
1233         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1234 }
1235 EXPORT_SYMBOL_GPL(driver_attach);
1236
1237 /*
1238  * __device_release_driver() must be called with @dev lock held.
1239  * When called for a USB interface, @dev->parent lock must be held as well.
1240  */
1241 static void __device_release_driver(struct device *dev, struct device *parent)
1242 {
1243         struct device_driver *drv;
1244
1245         drv = dev->driver;
1246         if (drv) {
1247                 pm_runtime_get_sync(dev);
1248
1249                 while (device_links_busy(dev)) {
1250                         __device_driver_unlock(dev, parent);
1251
1252                         device_links_unbind_consumers(dev);
1253
1254                         __device_driver_lock(dev, parent);
1255                         /*
1256                          * A concurrent invocation of the same function might
1257                          * have released the driver successfully while this one
1258                          * was waiting, so check for that.
1259                          */
1260                         if (dev->driver != drv) {
1261                                 pm_runtime_put(dev);
1262                                 return;
1263                         }
1264                 }
1265
1266                 driver_sysfs_remove(dev);
1267
1268                 bus_notify(dev, BUS_NOTIFY_UNBIND_DRIVER);
1269
1270                 pm_runtime_put_sync(dev);
1271
1272                 device_remove(dev);
1273
1274                 if (dev->bus && dev->bus->dma_cleanup)
1275                         dev->bus->dma_cleanup(dev);
1276
1277                 device_links_driver_cleanup(dev);
1278                 device_unbind_cleanup(dev);
1279
1280                 klist_remove(&dev->p->knode_driver);
1281                 device_pm_check_callbacks(dev);
1282
1283                 bus_notify(dev, BUS_NOTIFY_UNBOUND_DRIVER);
1284                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1285         }
1286 }
1287
1288 void device_release_driver_internal(struct device *dev,
1289                                     struct device_driver *drv,
1290                                     struct device *parent)
1291 {
1292         __device_driver_lock(dev, parent);
1293
1294         if (!drv || drv == dev->driver)
1295                 __device_release_driver(dev, parent);
1296
1297         __device_driver_unlock(dev, parent);
1298 }
1299
1300 /**
1301  * device_release_driver - manually detach device from driver.
1302  * @dev: device.
1303  *
1304  * Manually detach device from driver.
1305  * When called for a USB interface, @dev->parent lock must be held.
1306  *
1307  * If this function is to be called with @dev->parent lock held, ensure that
1308  * the device's consumers are unbound in advance or that their locks can be
1309  * acquired under the @dev->parent lock.
1310  */
1311 void device_release_driver(struct device *dev)
1312 {
1313         /*
1314          * If anyone calls device_release_driver() recursively from
1315          * within their ->remove callback for the same device, they
1316          * will deadlock right here.
1317          */
1318         device_release_driver_internal(dev, NULL, NULL);
1319 }
1320 EXPORT_SYMBOL_GPL(device_release_driver);
1321
1322 /**
1323  * device_driver_detach - detach driver from a specific device
1324  * @dev: device to detach driver from
1325  *
1326  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1327  * lock if needed.
1328  */
1329 void device_driver_detach(struct device *dev)
1330 {
1331         device_release_driver_internal(dev, NULL, dev->parent);
1332 }
1333
1334 /**
1335  * driver_detach - detach driver from all devices it controls.
1336  * @drv: driver.
1337  */
1338 void driver_detach(struct device_driver *drv)
1339 {
1340         struct device_private *dev_prv;
1341         struct device *dev;
1342
1343         if (driver_allows_async_probing(drv))
1344                 async_synchronize_full();
1345
1346         for (;;) {
1347                 spin_lock(&drv->p->klist_devices.k_lock);
1348                 if (list_empty(&drv->p->klist_devices.k_list)) {
1349                         spin_unlock(&drv->p->klist_devices.k_lock);
1350                         break;
1351                 }
1352                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1353                                      struct device_private,
1354                                      knode_driver.n_node);
1355                 dev = dev_prv->device;
1356                 get_device(dev);
1357                 spin_unlock(&drv->p->klist_devices.k_lock);
1358                 device_release_driver_internal(dev, drv, dev->parent);
1359                 put_device(dev);
1360         }
1361 }