drivers/base/dd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * drivers/base/dd.c - The core device/driver interactions.
   4  *
   5  * This file contains the (sometimes tricky) code that controls the
   6  * interactions between devices and drivers, which primarily includes
   7  * driver binding and unbinding.
   8  *
   9  * All of this code used to exist in drivers/base/bus.c, but was
  10  * relocated to here in the name of compartmentalization (since it wasn't
  11  * strictly code just for the 'struct bus_type'.
  12  *
  13  * Copyright (c) 2002-5 Patrick Mochel
  14  * Copyright (c) 2002-3 Open Source Development Labs
  15  * Copyright (c) 2007-2009 Greg Kroah-Hartman <[email protected]>
  16  * Copyright (c) 2007-2009 Novell Inc.
  17  */
  18
  19 #include <linux/debugfs.h>
  20 #include <linux/device.h>
  21 #include <linux/delay.h>
  22 #include <linux/dma-map-ops.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/kthread.h>
  26 #include <linux/wait.h>
  27 #include <linux/async.h>
  28 #include <linux/pm_runtime.h>
  29 #include <linux/pinctrl/devinfo.h>
  30 #include <linux/slab.h>
  31
  32 #include "base.h"
  33 #include "power/power.h"
  34
  35 /*
  36  * Deferred Probe infrastructure.
  37  *
  38  * Sometimes driver probe order matters, but the kernel doesn't always have
  39  * dependency information which means some drivers will get probed before a
  40  * resource it depends on is available.  For example, an SDHCI driver may
  41  * first need a GPIO line from an i2c GPIO controller before it can be
  42  * initialized.  If a required resource is not available yet, a driver can
  43  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  44  *
  45  * Deferred probe maintains two lists of devices, a pending list and an active
  46  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  47  * pending list.  A successful driver probe will trigger moving all devices
  48  * from the pending to the active list so that the workqueue will eventually
  49  * retry them.
  50  *
  51  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  52  * of the (struct device*)->p->deferred_probe pointers are manipulated
  53  */
  54 static DEFINE_MUTEX(deferred_probe_mutex);
  55 static LIST_HEAD(deferred_probe_pending_list);
  56 static LIST_HEAD(deferred_probe_active_list);
  57 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
  58 static bool initcalls_done;
  59
  60 /* Save the async probe drivers' name from kernel cmdline */
  61 #define ASYNC_DRV_NAMES_MAX_LEN 256
  62 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
  63 static bool async_probe_default;
  64
  65 /*
  66  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  67  * to prohibit probing of devices as it could be unsafe.
  68  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  69  */
  70 static bool defer_all_probes;
  71
  72 static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
  73 {
  74         kfree(dev->p->deferred_probe_reason);
  75         dev->p->deferred_probe_reason = reason;
  76 }
  77
  78 /*
  79  * deferred_probe_work_func() - Retry probing devices in the active list.
  80  */
  81 static void deferred_probe_work_func(struct work_struct *work)
  82 {
  83         struct device *dev;
  84         struct device_private *private;
  85         /*
  86          * This block processes every device in the deferred 'active' list.
  87          * Each device is removed from the active list and passed to
  88          * bus_probe_device() to re-attempt the probe.  The loop continues
  89          * until every device in the active list is removed and retried.
  90          *
  91          * Note: Once the device is removed from the list and the mutex is
  92          * released, it is possible for the device get freed by another thread
  93          * and cause a illegal pointer dereference.  This code uses
  94          * get/put_device() to ensure the device structure cannot disappear
  95          * from under our feet.
  96          */
  97         mutex_lock(&deferred_probe_mutex);
  98         while (!list_empty(&deferred_probe_active_list)) {
  99                 private = list_first_entry(&deferred_probe_active_list,
 100                                         typeof(*dev->p), deferred_probe);
 101                 dev = private->device;
 102                 list_del_init(&private->deferred_probe);
 103
 104                 get_device(dev);
 105
 106                 __device_set_deferred_probe_reason(dev, NULL);
 107
 108                 /*
 109                  * Drop the mutex while probing each device; the probe path may
 110                  * manipulate the deferred list
 111                  */
 112                 mutex_unlock(&deferred_probe_mutex);
 113
 114                 /*
 115                  * Force the device to the end of the dpm_list since
 116                  * the PM code assumes that the order we add things to
 117                  * the list is a good order for suspend but deferred
 118                  * probe makes that very unsafe.
 119                  */
 120                 device_pm_move_to_tail(dev);
 121
 122                 dev_dbg(dev, "Retrying from deferred list\n");
 123                 bus_probe_device(dev);
 124                 mutex_lock(&deferred_probe_mutex);
 125
 126                 put_device(dev);
 127         }
 128         mutex_unlock(&deferred_probe_mutex);
 129 }
 130 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 131
 132 void driver_deferred_probe_add(struct device *dev)
 133 {
 134         if (!dev->can_match)
 135                 return;
 136
 137         mutex_lock(&deferred_probe_mutex);
 138         if (list_empty(&dev->p->deferred_probe)) {
 139                 dev_dbg(dev, "Added to deferred list\n");
 140                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 141         }
 142         mutex_unlock(&deferred_probe_mutex);
 143 }
 144
 145 void driver_deferred_probe_del(struct device *dev)
 146 {
 147         mutex_lock(&deferred_probe_mutex);
 148         if (!list_empty(&dev->p->deferred_probe)) {
 149                 dev_dbg(dev, "Removed from deferred list\n");
 150                 list_del_init(&dev->p->deferred_probe);
 151                 __device_set_deferred_probe_reason(dev, NULL);
 152         }
 153         mutex_unlock(&deferred_probe_mutex);
 154 }
 155
 156 static bool driver_deferred_probe_enable;
 157 /**
 158  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 159  *
 160  * This functions moves all devices from the pending list to the active
 161  * list and schedules the deferred probe workqueue to process them.  It
 162  * should be called anytime a driver is successfully bound to a device.
 163  *
 164  * Note, there is a race condition in multi-threaded probe. In the case where
 165  * more than one device is probing at the same time, it is possible for one
 166  * probe to complete successfully while another is about to defer. If the second
 167  * depends on the first, then it will get put on the pending list after the
 168  * trigger event has already occurred and will be stuck there.
 169  *
 170  * The atomic 'deferred_trigger_count' is used to determine if a successful
 171  * trigger has occurred in the midst of probing a driver. If the trigger count
 172  * changes in the midst of a probe, then deferred processing should be triggered
 173  * again.
 174  */
 175 void driver_deferred_probe_trigger(void)
 176 {
 177         if (!driver_deferred_probe_enable)
 178                 return;
 179
 180         /*
 181          * A successful probe means that all the devices in the pending list
 182          * should be triggered to be reprobed.  Move all the deferred devices
 183          * into the active list so they can be retried by the workqueue
 184          */
 185         mutex_lock(&deferred_probe_mutex);
 186         atomic_inc(&deferred_trigger_count);
 187         list_splice_tail_init(&deferred_probe_pending_list,
 188                               &deferred_probe_active_list);
 189         mutex_unlock(&deferred_probe_mutex);
 190
 191         /*
 192          * Kick the re-probe thread.  It may already be scheduled, but it is
 193          * safe to kick it again.
 194          */
 195         queue_work(system_unbound_wq, &deferred_probe_work);
 196 }
 197
 198 /**
 199  * device_block_probing() - Block/defer device's probes
 200  *
 201  *      It will disable probing of devices and defer their probes instead.
 202  */
 203 void device_block_probing(void)
 204 {
 205         defer_all_probes = true;
 206         /* sync with probes to avoid races. */
 207         wait_for_device_probe();
 208 }
 209
 210 /**
 211  * device_unblock_probing() - Unblock/enable device's probes
 212  *
 213  *      It will restore normal behavior and trigger re-probing of deferred
 214  * devices.
 215  */
 216 void device_unblock_probing(void)
 217 {
 218         defer_all_probes = false;
 219         driver_deferred_probe_trigger();
 220 }
 221
 222 /**
 223  * device_set_deferred_probe_reason() - Set defer probe reason message for device
 224  * @dev: the pointer to the struct device
 225  * @vaf: the pointer to va_format structure with message
 226  */
 227 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
 228 {
 229         const char *drv = dev_driver_string(dev);
 230         char *reason;
 231
 232         mutex_lock(&deferred_probe_mutex);
 233
 234         reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
 235         __device_set_deferred_probe_reason(dev, reason);
 236
 237         mutex_unlock(&deferred_probe_mutex);
 238 }
 239
 240 /*
 241  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 242  */
 243 static int deferred_devs_show(struct seq_file *s, void *data)
 244 {
 245         struct device_private *curr;
 246
 247         mutex_lock(&deferred_probe_mutex);
 248
 249         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 250                 seq_printf(s, "%s\t%s", dev_name(curr->device),
 251                            curr->device->p->deferred_probe_reason ?: "\n");
 252
 253         mutex_unlock(&deferred_probe_mutex);
 254
 255         return 0;
 256 }
 257 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 258
 259 #ifdef CONFIG_MODULES
 260 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 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 320
 321 void deferred_probe_extend_timeout(void)
 322 {
 323         /*
 324          * If the work hasn't been queued yet or if the work expired, don't
 325          * start a new one.
 326          */
 327         if (cancel_delayed_work(&deferred_probe_timeout_work)) {
 328                 schedule_delayed_work(&deferred_probe_timeout_work,
 329                                 driver_deferred_probe_timeout * HZ);
 330                 pr_debug("Extended deferred probe timeout by %d secs\n",
 331                                         driver_deferred_probe_timeout);
 332         }
 333 }
 334
 335 /**
 336  * deferred_probe_initcall() - Enable probing of deferred devices
 337  *
 338  * We don't want to get in the way when the bulk of drivers are getting probed.
 339  * Instead, this initcall makes sure that deferred probing is delayed until
 340  * late_initcall time.
 341  */
 342 static int deferred_probe_initcall(void)
 343 {
 344         debugfs_create_file("devices_deferred", 0444, NULL, NULL,
 345                             &deferred_devs_fops);
 346
 347         driver_deferred_probe_enable = true;
 348         driver_deferred_probe_trigger();
 349         /* Sort as many dependencies as possible before exiting initcalls */
 350         flush_work(&deferred_probe_work);
 351         initcalls_done = true;
 352
 353         if (!IS_ENABLED(CONFIG_MODULES))
 354                 fw_devlink_drivers_done();
 355
 356         /*
 357          * Trigger deferred probe again, this time we won't defer anything
 358          * that is optional
 359          */
 360         driver_deferred_probe_trigger();
 361         flush_work(&deferred_probe_work);
 362
 363         if (driver_deferred_probe_timeout > 0) {
 364                 schedule_delayed_work(&deferred_probe_timeout_work,
 365                         driver_deferred_probe_timeout * HZ);
 366         }
 367         return 0;
 368 }
 369 late_initcall(deferred_probe_initcall);
 370
 371 static void __exit deferred_probe_exit(void)
 372 {
 373         debugfs_lookup_and_remove("devices_deferred", NULL);
 374 }
 375 __exitcall(deferred_probe_exit);
 376
 377 /**
 378  * device_is_bound() - Check if device is bound to a driver
 379  * @dev: device to check
 380  *
 381  * Returns true if passed device has already finished probing successfully
 382  * against a driver.
 383  *
 384  * This function must be called with the device lock held.
 385  */
 386 bool device_is_bound(struct device *dev)
 387 {
 388         return dev->p && klist_node_attached(&dev->p->knode_driver);
 389 }
 390
 391 static void driver_bound(struct device *dev)
 392 {
 393         if (device_is_bound(dev)) {
 394                 pr_warn("%s: device %s already bound\n",
 395                         __func__, kobject_name(&dev->kobj));
 396                 return;
 397         }
 398
 399         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 400                  __func__, dev_name(dev));
 401
 402         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 403         device_links_driver_bound(dev);
 404
 405         device_pm_check_callbacks(dev);
 406
 407         /*
 408          * Make sure the device is no longer in one of the deferred lists and
 409          * kick off retrying all pending devices
 410          */
 411         driver_deferred_probe_del(dev);
 412         driver_deferred_probe_trigger();
 413
 414         bus_notify(dev, BUS_NOTIFY_BOUND_DRIVER);
 415         kobject_uevent(&dev->kobj, KOBJ_BIND);
 416 }
 417
 418 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 419                             const char *buf, size_t count)
 420 {
 421         device_lock(dev);
 422         dev->driver->coredump(dev);
 423         device_unlock(dev);
 424
 425         return count;
 426 }
 427 static DEVICE_ATTR_WO(coredump);
 428
 429 static int driver_sysfs_add(struct device *dev)
 430 {
 431         int ret;
 432
 433         bus_notify(dev, BUS_NOTIFY_BIND_DRIVER);
 434
 435         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 436                                 kobject_name(&dev->kobj));
 437         if (ret)
 438                 goto fail;
 439
 440         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 441                                 "driver");
 442         if (ret)
 443                 goto rm_dev;
 444
 445         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 446                 return 0;
 447
 448         ret = device_create_file(dev, &dev_attr_coredump);
 449         if (!ret)
 450                 return 0;
 451
 452         sysfs_remove_link(&dev->kobj, "driver");
 453
 454 rm_dev:
 455         sysfs_remove_link(&dev->driver->p->kobj,
 456                           kobject_name(&dev->kobj));
 457
 458 fail:
 459         return ret;
 460 }
 461
 462 static void driver_sysfs_remove(struct device *dev)
 463 {
 464         struct device_driver *drv = dev->driver;
 465
 466         if (drv) {
 467                 if (drv->coredump)
 468                         device_remove_file(dev, &dev_attr_coredump);
 469                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 470                 sysfs_remove_link(&dev->kobj, "driver");
 471         }
 472 }
 473
 474 /**
 475  * device_bind_driver - bind a driver to one device.
 476  * @dev: device.
 477  *
 478  * Allow manual attachment of a driver to a device.
 479  * Caller must have already set @dev->driver.
 480  *
 481  * Note that this does not modify the bus reference count.
 482  * Please verify that is accounted for before calling this.
 483  * (It is ok to call with no other effort from a driver's probe() method.)
 484  *
 485  * This function must be called with the device lock held.
 486  *
 487  * Callers should prefer to use device_driver_attach() instead.
 488  */
 489 int device_bind_driver(struct device *dev)
 490 {
 491         int ret;
 492
 493         ret = driver_sysfs_add(dev);
 494         if (!ret) {
 495                 device_links_force_bind(dev);
 496                 driver_bound(dev);
 497         }
 498         else
 499                 bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
 500         return ret;
 501 }
 502 EXPORT_SYMBOL_GPL(device_bind_driver);
 503
 504 static atomic_t probe_count = ATOMIC_INIT(0);
 505 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 506
 507 static ssize_t state_synced_show(struct device *dev,
 508                                  struct device_attribute *attr, char *buf)
 509 {
 510         bool val;
 511
 512         device_lock(dev);
 513         val = dev->state_synced;
 514         device_unlock(dev);
 515
 516         return sysfs_emit(buf, "%u\n", val);
 517 }
 518 static DEVICE_ATTR_RO(state_synced);
 519
 520 static void device_unbind_cleanup(struct device *dev)
 521 {
 522         devres_release_all(dev);
 523         arch_teardown_dma_ops(dev);
 524         kfree(dev->dma_range_map);
 525         dev->dma_range_map = NULL;
 526         dev->driver = NULL;
 527         dev_set_drvdata(dev, NULL);
 528         if (dev->pm_domain && dev->pm_domain->dismiss)
 529                 dev->pm_domain->dismiss(dev);
 530         pm_runtime_reinit(dev);
 531         dev_pm_set_driver_flags(dev, 0);
 532 }
 533
 534 static void device_remove(struct device *dev)
 535 {
 536         device_remove_file(dev, &dev_attr_state_synced);
 537         device_remove_groups(dev, dev->driver->dev_groups);
 538
 539         if (dev->bus && dev->bus->remove)
 540                 dev->bus->remove(dev);
 541         else if (dev->driver->remove)
 542                 dev->driver->remove(dev);
 543 }
 544
 545 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 546 {
 547         int ret = 0;
 548
 549         if (dev->bus->probe)
 550                 ret = dev->bus->probe(dev);
 551         else if (drv->probe)
 552                 ret = drv->probe(dev);
 553
 554         switch (ret) {
 555         case 0:
 556                 break;
 557         case -EPROBE_DEFER:
 558                 /* Driver requested deferred probing */
 559                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 560                 break;
 561         case -ENODEV:
 562         case -ENXIO:
 563                 pr_debug("%s: probe of %s rejects match %d\n",
 564                          drv->name, dev_name(dev), ret);
 565                 break;
 566         default:
 567                 /* driver matched but the probe failed */
 568                 pr_warn("%s: probe of %s failed with error %d\n",
 569                         drv->name, dev_name(dev), ret);
 570                 break;
 571         }
 572
 573         return ret;
 574 }
 575
 576 static int really_probe(struct device *dev, struct device_driver *drv)
 577 {
 578         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 579                            !drv->suppress_bind_attrs;
 580         int ret, link_ret;
 581
 582         if (defer_all_probes) {
 583                 /*
 584                  * Value of defer_all_probes can be set only by
 585                  * device_block_probing() which, in turn, will call
 586                  * wait_for_device_probe() right after that to avoid any races.
 587                  */
 588                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 589                 return -EPROBE_DEFER;
 590         }
 591
 592         link_ret = device_links_check_suppliers(dev);
 593         if (link_ret == -EPROBE_DEFER)
 594                 return link_ret;
 595
 596         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 597                  drv->bus->name, __func__, drv->name, dev_name(dev));
 598         if (!list_empty(&dev->devres_head)) {
 599                 dev_crit(dev, "Resources present before probing\n");
 600                 ret = -EBUSY;
 601                 goto done;
 602         }
 603
 604 re_probe:
 605         dev->driver = drv;
 606
 607         /* If using pinctrl, bind pins now before probing */
 608         ret = pinctrl_bind_pins(dev);
 609         if (ret)
 610                 goto pinctrl_bind_failed;
 611
 612         if (dev->bus->dma_configure) {
 613                 ret = dev->bus->dma_configure(dev);
 614                 if (ret)
 615                         goto pinctrl_bind_failed;
 616         }
 617
 618         ret = driver_sysfs_add(dev);
 619         if (ret) {
 620                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 621                        __func__, dev_name(dev));
 622                 goto sysfs_failed;
 623         }
 624
 625         if (dev->pm_domain && dev->pm_domain->activate) {
 626                 ret = dev->pm_domain->activate(dev);
 627                 if (ret)
 628                         goto probe_failed;
 629         }
 630
 631         ret = call_driver_probe(dev, drv);
 632         if (ret) {
 633                 /*
 634                  * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
 635                  * device might actually probe properly once some of its missing
 636                  * suppliers have probed. So, treat this as if the driver
 637                  * returned -EPROBE_DEFER.
 638                  */
 639                 if (link_ret == -EAGAIN)
 640                         ret = -EPROBE_DEFER;
 641
 642                 /*
 643                  * Return probe errors as positive values so that the callers
 644                  * can distinguish them from other errors.
 645                  */
 646                 ret = -ret;
 647                 goto probe_failed;
 648         }
 649
 650         ret = device_add_groups(dev, drv->dev_groups);
 651         if (ret) {
 652                 dev_err(dev, "device_add_groups() failed\n");
 653                 goto dev_groups_failed;
 654         }
 655
 656         if (dev_has_sync_state(dev)) {
 657                 ret = device_create_file(dev, &dev_attr_state_synced);
 658                 if (ret) {
 659                         dev_err(dev, "state_synced sysfs add failed\n");
 660                         goto dev_sysfs_state_synced_failed;
 661                 }
 662         }
 663
 664         if (test_remove) {
 665                 test_remove = false;
 666
 667                 device_remove(dev);
 668                 driver_sysfs_remove(dev);
 669                 device_unbind_cleanup(dev);
 670
 671                 goto re_probe;
 672         }
 673
 674         pinctrl_init_done(dev);
 675
 676         if (dev->pm_domain && dev->pm_domain->sync)
 677                 dev->pm_domain->sync(dev);
 678
 679         driver_bound(dev);
 680         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 681                  drv->bus->name, __func__, dev_name(dev), drv->name);
 682         goto done;
 683
 684 dev_sysfs_state_synced_failed:
 685 dev_groups_failed:
 686         device_remove(dev);
 687 probe_failed:
 688         driver_sysfs_remove(dev);
 689 sysfs_failed:
 690         bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND);
 691         if (dev->bus && dev->bus->dma_cleanup)
 692                 dev->bus->dma_cleanup(dev);
 693 pinctrl_bind_failed:
 694         device_links_no_driver(dev);
 695         device_unbind_cleanup(dev);
 696 done:
 697         return ret;
 698 }
 699
 700 /*
 701  * For initcall_debug, show the driver probe time.
 702  */
 703 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 704 {
 705         ktime_t calltime, rettime;
 706         int ret;
 707
 708         calltime = ktime_get();
 709         ret = really_probe(dev, drv);
 710         rettime = ktime_get();
 711         pr_debug("probe of %s returned %d after %lld usecs\n",
 712                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 713         return ret;
 714 }
 715
 716 /**
 717  * driver_probe_done
 718  * Determine if the probe sequence is finished or not.
 719  *
 720  * Should somehow figure out how to use a semaphore, not an atomic variable...
 721  */
 722 int driver_probe_done(void)
 723 {
 724         int local_probe_count = atomic_read(&probe_count);
 725
 726         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 727         if (local_probe_count)
 728                 return -EBUSY;
 729         return 0;
 730 }
 731
 732 /**
 733  * wait_for_device_probe
 734  * Wait for device probing to be completed.
 735  */
 736 void wait_for_device_probe(void)
 737 {
 738         /* wait for the deferred probe workqueue to finish */
 739         flush_work(&deferred_probe_work);
 740
 741         /* wait for the known devices to complete their probing */
 742         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 743         async_synchronize_full();
 744 }
 745 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 746
 747 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 748 {
 749         int ret = 0;
 750
 751         if (dev->p->dead || !device_is_registered(dev))
 752                 return -ENODEV;
 753         if (dev->driver)
 754                 return -EBUSY;
 755
 756         dev->can_match = true;
 757         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 758                  drv->bus->name, __func__, dev_name(dev), drv->name);
 759
 760         pm_runtime_get_suppliers(dev);
 761         if (dev->parent)
 762                 pm_runtime_get_sync(dev->parent);
 763
 764         pm_runtime_barrier(dev);
 765         if (initcall_debug)
 766                 ret = really_probe_debug(dev, drv);
 767         else
 768                 ret = really_probe(dev, drv);
 769         pm_request_idle(dev);
 770
 771         if (dev->parent)
 772                 pm_runtime_put(dev->parent);
 773
 774         pm_runtime_put_suppliers(dev);
 775         return ret;
 776 }
 777
 778 /**
 779  * driver_probe_device - attempt to bind device & driver together
 780  * @drv: driver to bind a device to
 781  * @dev: device to try to bind to the driver
 782  *
 783  * This function returns -ENODEV if the device is not registered, -EBUSY if it
 784  * already has a driver, 0 if the device is bound successfully and a positive
 785  * (inverted) error code for failures from the ->probe method.
 786  *
 787  * This function must be called with @dev lock held.  When called for a
 788  * USB interface, @dev->parent lock must be held as well.
 789  *
 790  * If the device has a parent, runtime-resume the parent before driver probing.
 791  */
 792 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 793 {
 794         int trigger_count = atomic_read(&deferred_trigger_count);
 795         int ret;
 796
 797         atomic_inc(&probe_count);
 798         ret = __driver_probe_device(drv, dev);
 799         if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
 800                 driver_deferred_probe_add(dev);
 801
 802                 /*
 803                  * Did a trigger occur while probing? Need to re-trigger if yes
 804                  */
 805                 if (trigger_count != atomic_read(&deferred_trigger_count) &&
 806                     !defer_all_probes)
 807                         driver_deferred_probe_trigger();
 808         }
 809         atomic_dec(&probe_count);
 810         wake_up_all(&probe_waitqueue);
 811         return ret;
 812 }
 813
 814 static inline bool cmdline_requested_async_probing(const char *drv_name)
 815 {
 816         bool async_drv;
 817
 818         async_drv = parse_option_str(async_probe_drv_names, drv_name);
 819
 820         return (async_probe_default != async_drv);
 821 }
 822
 823 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 824 static int __init save_async_options(char *buf)
 825 {
 826         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 827                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 828
 829         strscpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 830         async_probe_default = parse_option_str(async_probe_drv_names, "*");
 831
 832         return 1;
 833 }
 834 __setup("driver_async_probe=", save_async_options);
 835
 836 static bool driver_allows_async_probing(struct device_driver *drv)
 837 {
 838         switch (drv->probe_type) {
 839         case PROBE_PREFER_ASYNCHRONOUS:
 840                 return true;
 841
 842         case PROBE_FORCE_SYNCHRONOUS:
 843                 return false;
 844
 845         default:
 846                 if (cmdline_requested_async_probing(drv->name))
 847                         return true;
 848
 849                 if (module_requested_async_probing(drv->owner))
 850                         return true;
 851
 852                 return false;
 853         }
 854 }
 855
 856 struct device_attach_data {
 857         struct device *dev;
 858
 859         /*
 860          * Indicates whether we are considering asynchronous probing or
 861          * not. Only initial binding after device or driver registration
 862          * (including deferral processing) may be done asynchronously, the
 863          * rest is always synchronous, as we expect it is being done by
 864          * request from userspace.
 865          */
 866         bool check_async;
 867
 868         /*
 869          * Indicates if we are binding synchronous or asynchronous drivers.
 870          * When asynchronous probing is enabled we'll execute 2 passes
 871          * over drivers: first pass doing synchronous probing and second
 872          * doing asynchronous probing (if synchronous did not succeed -
 873          * most likely because there was no driver requiring synchronous
 874          * probing - and we found asynchronous driver during first pass).
 875          * The 2 passes are done because we can't shoot asynchronous
 876          * probe for given device and driver from bus_for_each_drv() since
 877          * driver pointer is not guaranteed to stay valid once
 878          * bus_for_each_drv() iterates to the next driver on the bus.
 879          */
 880         bool want_async;
 881
 882         /*
 883          * We'll set have_async to 'true' if, while scanning for matching
 884          * driver, we'll encounter one that requests asynchronous probing.
 885          */
 886         bool have_async;
 887 };
 888
 889 static int __device_attach_driver(struct device_driver *drv, void *_data)
 890 {
 891         struct device_attach_data *data = _data;
 892         struct device *dev = data->dev;
 893         bool async_allowed;
 894         int ret;
 895
 896         ret = driver_match_device(drv, dev);
 897         if (ret == 0) {
 898                 /* no match */
 899                 return 0;
 900         } else if (ret == -EPROBE_DEFER) {
 901                 dev_dbg(dev, "Device match requests probe deferral\n");
 902                 dev->can_match = true;
 903                 driver_deferred_probe_add(dev);
 904                 /*
 905                  * Device can't match with a driver right now, so don't attempt
 906                  * to match or bind with other drivers on the bus.
 907                  */
 908                 return ret;
 909         } else if (ret < 0) {
 910                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 911                 return ret;
 912         } /* ret > 0 means positive match */
 913
 914         async_allowed = driver_allows_async_probing(drv);
 915
 916         if (async_allowed)
 917                 data->have_async = true;
 918
 919         if (data->check_async && async_allowed != data->want_async)
 920                 return 0;
 921
 922         /*
 923          * Ignore errors returned by ->probe so that the next driver can try
 924          * its luck.
 925          */
 926         ret = driver_probe_device(drv, dev);
 927         if (ret < 0)
 928                 return ret;
 929         return ret == 0;
 930 }
 931
 932 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 933 {
 934         struct device *dev = _dev;
 935         struct device_attach_data data = {
 936                 .dev            = dev,
 937                 .check_async    = true,
 938                 .want_async     = true,
 939         };
 940
 941         device_lock(dev);
 942
 943         /*
 944          * Check if device has already been removed or claimed. This may
 945          * happen with driver loading, device discovery/registration,
 946          * and deferred probe processing happens all at once with
 947          * multiple threads.
 948          */
 949         if (dev->p->dead || dev->driver)
 950                 goto out_unlock;
 951
 952         if (dev->parent)
 953                 pm_runtime_get_sync(dev->parent);
 954
 955         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 956         dev_dbg(dev, "async probe completed\n");
 957
 958         pm_request_idle(dev);
 959
 960         if (dev->parent)
 961                 pm_runtime_put(dev->parent);
 962 out_unlock:
 963         device_unlock(dev);
 964
 965         put_device(dev);
 966 }
 967
 968 static int __device_attach(struct device *dev, bool allow_async)
 969 {
 970         int ret = 0;
 971         bool async = false;
 972
 973         device_lock(dev);
 974         if (dev->p->dead) {
 975                 goto out_unlock;
 976         } else if (dev->driver) {
 977                 if (device_is_bound(dev)) {
 978                         ret = 1;
 979                         goto out_unlock;
 980                 }
 981                 ret = device_bind_driver(dev);
 982                 if (ret == 0)
 983                         ret = 1;
 984                 else {
 985                         dev->driver = NULL;
 986                         ret = 0;
 987                 }
 988         } else {
 989                 struct device_attach_data data = {
 990                         .dev = dev,
 991                         .check_async = allow_async,
 992                         .want_async = false,
 993                 };
 994
 995                 if (dev->parent)
 996                         pm_runtime_get_sync(dev->parent);
 997
 998                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 999                                         __device_attach_driver);
1000                 if (!ret && allow_async && data.have_async) {
1001                         /*
1002                          * If we could not find appropriate driver
1003                          * synchronously and we are allowed to do
1004                          * async probes and there are drivers that
1005                          * want to probe asynchronously, we'll
1006                          * try them.
1007                          */
1008                         dev_dbg(dev, "scheduling asynchronous probe\n");
1009                         get_device(dev);
1010                         async = true;
1011                 } else {
1012                         pm_request_idle(dev);
1013                 }
1014
1015                 if (dev->parent)
1016                         pm_runtime_put(dev->parent);
1017         }
1018 out_unlock:
1019         device_unlock(dev);
1020         if (async)
1021                 async_schedule_dev(__device_attach_async_helper, dev);
1022         return ret;
1023 }
1024
1025 /**
1026  * device_attach - try to attach device to a driver.
1027  * @dev: device.
1028  *
1029  * Walk the list of drivers that the bus has and call
1030  * driver_probe_device() for each pair. If a compatible
1031  * pair is found, break out and return.
1032  *
1033  * Returns 1 if the device was bound to a driver;
1034  * 0 if no matching driver was found;
1035  * -ENODEV if the device is not registered.
1036  *
1037  * When called for a USB interface, @dev->parent lock must be held.
1038  */
1039 int device_attach(struct device *dev)
1040 {
1041         return __device_attach(dev, false);
1042 }
1043 EXPORT_SYMBOL_GPL(device_attach);
1044
1045 void device_initial_probe(struct device *dev)
1046 {
1047         __device_attach(dev, true);
1048 }
1049
1050 /*
1051  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1052  * @dev: Device we will update driver info for
1053  * @parent: Parent device. Needed if the bus requires parent lock
1054  *
1055  * This function will take the required locks for manipulating dev->drv.
1056  * Normally this will just be the @dev lock, but when called for a USB
1057  * interface, @parent lock will be held as well.
1058  */
1059 static void __device_driver_lock(struct device *dev, struct device *parent)
1060 {
1061         if (parent && dev->bus->need_parent_lock)
1062                 device_lock(parent);
1063         device_lock(dev);
1064 }
1065
1066 /*
1067  * __device_driver_unlock - release locks needed to manipulate dev->drv
1068  * @dev: Device we will update driver info for
1069  * @parent: Parent device. Needed if the bus requires parent lock
1070  *
1071  * This function will release the required locks for manipulating dev->drv.
1072  * Normally this will just be the @dev lock, but when called for a
1073  * USB interface, @parent lock will be released as well.
1074  */
1075 static void __device_driver_unlock(struct device *dev, struct device *parent)
1076 {
1077         device_unlock(dev);
1078         if (parent && dev->bus->need_parent_lock)
1079                 device_unlock(parent);
1080 }
1081
1082 /**
1083  * device_driver_attach - attach a specific driver to a specific device
1084  * @drv: Driver to attach
1085  * @dev: Device to attach it to
1086  *
1087  * Manually attach driver to a device. Will acquire both @dev lock and
1088  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1089  */
1090 int device_driver_attach(struct device_driver *drv, struct device *dev)
1091 {
1092         int ret;
1093
1094         __device_driver_lock(dev, dev->parent);
1095         ret = __driver_probe_device(drv, dev);
1096         __device_driver_unlock(dev, dev->parent);
1097
1098         /* also return probe errors as normal negative errnos */
1099         if (ret > 0)
1100                 ret = -ret;
1101         if (ret == -EPROBE_DEFER)
1102                 return -EAGAIN;
1103         return ret;
1104 }
1105 EXPORT_SYMBOL_GPL(device_driver_attach);
1106
1107 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1108 {
1109         struct device *dev = _dev;
1110         struct device_driver *drv;
1111         int ret;
1112
1113         __device_driver_lock(dev, dev->parent);
1114         drv = dev->p->async_driver;
1115         dev->p->async_driver = NULL;
1116         ret = driver_probe_device(drv, dev);
1117         __device_driver_unlock(dev, dev->parent);
1118
1119         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1120
1121         put_device(dev);
1122 }
1123
1124 static int __driver_attach(struct device *dev, void *data)
1125 {
1126         struct device_driver *drv = data;
1127         bool async = false;
1128         int ret;
1129
1130         /*
1131          * Lock device and try to bind to it. We drop the error
1132          * here and always return 0, because we need to keep trying
1133          * to bind to devices and some drivers will return an error
1134          * simply if it didn't support the device.
1135          *
1136          * driver_probe_device() will spit a warning if there
1137          * is an error.
1138          */
1139
1140         ret = driver_match_device(drv, dev);
1141         if (ret == 0) {
1142                 /* no match */
1143                 return 0;
1144         } else if (ret == -EPROBE_DEFER) {
1145                 dev_dbg(dev, "Device match requests probe deferral\n");
1146                 dev->can_match = true;
1147                 driver_deferred_probe_add(dev);
1148                 /*
1149                  * Driver could not match with device, but may match with
1150                  * another device on the bus.
1151                  */
1152                 return 0;
1153         } else if (ret < 0) {
1154                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1155                 /*
1156                  * Driver could not match with device, but may match with
1157                  * another device on the bus.
1158                  */
1159                 return 0;
1160         } /* ret > 0 means positive match */
1161
1162         if (driver_allows_async_probing(drv)) {
1163                 /*
1164                  * Instead of probing the device synchronously we will
1165                  * probe it asynchronously to allow for more parallelism.
1166                  *
1167                  * We only take the device lock here in order to guarantee
1168                  * that the dev->driver and async_driver fields are protected
1169                  */
1170                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1171                 device_lock(dev);
1172                 if (!dev->driver && !dev->p->async_driver) {
1173                         get_device(dev);
1174                         dev->p->async_driver = drv;
1175                         async = true;
1176                 }
1177                 device_unlock(dev);
1178                 if (async)
1179                         async_schedule_dev(__driver_attach_async_helper, dev);
1180                 return 0;
1181         }
1182
1183         __device_driver_lock(dev, dev->parent);
1184         driver_probe_device(drv, dev);
1185         __device_driver_unlock(dev, dev->parent);
1186
1187         return 0;
1188 }
1189
1190 /**
1191  * driver_attach - try to bind driver to devices.
1192  * @drv: driver.
1193  *
1194  * Walk the list of devices that the bus has on it and try to
1195  * match the driver with each one.  If driver_probe_device()
1196  * returns 0 and the @dev->driver is set, we've found a
1197  * compatible pair.
1198  */
1199 int driver_attach(struct device_driver *drv)
1200 {
1201         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1202 }
1203 EXPORT_SYMBOL_GPL(driver_attach);
1204
1205 /*
1206  * __device_release_driver() must be called with @dev lock held.
1207  * When called for a USB interface, @dev->parent lock must be held as well.
1208  */
1209 static void __device_release_driver(struct device *dev, struct device *parent)
1210 {
1211         struct device_driver *drv;
1212
1213         drv = dev->driver;
1214         if (drv) {
1215                 pm_runtime_get_sync(dev);
1216
1217                 while (device_links_busy(dev)) {
1218                         __device_driver_unlock(dev, parent);
1219
1220                         device_links_unbind_consumers(dev);
1221
1222                         __device_driver_lock(dev, parent);
1223                         /*
1224                          * A concurrent invocation of the same function might
1225                          * have released the driver successfully while this one
1226                          * was waiting, so check for that.
1227                          */
1228                         if (dev->driver != drv) {
1229                                 pm_runtime_put(dev);
1230                                 return;
1231                         }
1232                 }
1233
1234                 driver_sysfs_remove(dev);
1235
1236                 bus_notify(dev, BUS_NOTIFY_UNBIND_DRIVER);
1237
1238                 pm_runtime_put_sync(dev);
1239
1240                 device_remove(dev);
1241
1242                 if (dev->bus && dev->bus->dma_cleanup)
1243                         dev->bus->dma_cleanup(dev);
1244
1245                 device_links_driver_cleanup(dev);
1246                 device_unbind_cleanup(dev);
1247
1248                 klist_remove(&dev->p->knode_driver);
1249                 device_pm_check_callbacks(dev);
1250
1251                 bus_notify(dev, BUS_NOTIFY_UNBOUND_DRIVER);
1252                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1253         }
1254 }
1255
1256 void device_release_driver_internal(struct device *dev,
1257                                     struct device_driver *drv,
1258                                     struct device *parent)
1259 {
1260         __device_driver_lock(dev, parent);
1261
1262         if (!drv || drv == dev->driver)
1263                 __device_release_driver(dev, parent);
1264
1265         __device_driver_unlock(dev, parent);
1266 }
1267
1268 /**
1269  * device_release_driver - manually detach device from driver.
1270  * @dev: device.
1271  *
1272  * Manually detach device from driver.
1273  * When called for a USB interface, @dev->parent lock must be held.
1274  *
1275  * If this function is to be called with @dev->parent lock held, ensure that
1276  * the device's consumers are unbound in advance or that their locks can be
1277  * acquired under the @dev->parent lock.
1278  */
1279 void device_release_driver(struct device *dev)
1280 {
1281         /*
1282          * If anyone calls device_release_driver() recursively from
1283          * within their ->remove callback for the same device, they
1284          * will deadlock right here.
1285          */
1286         device_release_driver_internal(dev, NULL, NULL);
1287 }
1288 EXPORT_SYMBOL_GPL(device_release_driver);
1289
1290 /**
1291  * device_driver_detach - detach driver from a specific device
1292  * @dev: device to detach driver from
1293  *
1294  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1295  * lock if needed.
1296  */
1297 void device_driver_detach(struct device *dev)
1298 {
1299         device_release_driver_internal(dev, NULL, dev->parent);
1300 }
1301
1302 /**
1303  * driver_detach - detach driver from all devices it controls.
1304  * @drv: driver.
1305  */
1306 void driver_detach(struct device_driver *drv)
1307 {
1308         struct device_private *dev_prv;
1309         struct device *dev;
1310
1311         if (driver_allows_async_probing(drv))
1312                 async_synchronize_full();
1313
1314         for (;;) {
1315                 spin_lock(&drv->p->klist_devices.k_lock);
1316                 if (list_empty(&drv->p->klist_devices.k_list)) {
1317                         spin_unlock(&drv->p->klist_devices.k_lock);
1318                         break;
1319                 }
1320                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1321                                      struct device_private,
1322                                      knode_driver.n_node);
1323                 dev = dev_prv->device;
1324                 get_device(dev);
1325                 spin_unlock(&drv->p->klist_devices.k_lock);
1326                 device_release_driver_internal(dev, drv, dev->parent);
1327                 put_device(dev);
1328         }
1329 }