drivers/base/dd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * drivers/base/dd.c - The core device/driver interactions.
   4  *
   5  * This file contains the (sometimes tricky) code that controls the
   6  * interactions between devices and drivers, which primarily includes
   7  * driver binding and unbinding.
   8  *
   9  * All of this code used to exist in drivers/base/bus.c, but was
  10  * relocated to here in the name of compartmentalization (since it wasn't
  11  * strictly code just for the 'struct bus_type'.
  12  *
  13  * Copyright (c) 2002-5 Patrick Mochel
  14  * Copyright (c) 2002-3 Open Source Development Labs
  15  * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
  16  * Copyright (c) 2007-2009 Novell Inc.
  17  */
  18
  19 #include <linux/debugfs.h>
  20 #include <linux/device.h>
  21 #include <linux/delay.h>
  22 #include <linux/dma-map-ops.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/kthread.h>
  26 #include <linux/wait.h>
  27 #include <linux/async.h>
  28 #include <linux/pm_runtime.h>
  29 #include <linux/pinctrl/devinfo.h>
  30 #include <linux/slab.h>
  31
  32 #include "base.h"
  33 #include "power/power.h"
  34
  35 /*
  36  * Deferred Probe infrastructure.
  37  *
  38  * Sometimes driver probe order matters, but the kernel doesn't always have
  39  * dependency information which means some drivers will get probed before a
  40  * resource it depends on is available.  For example, an SDHCI driver may
  41  * first need a GPIO line from an i2c GPIO controller before it can be
  42  * initialized.  If a required resource is not available yet, a driver can
  43  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  44  *
  45  * Deferred probe maintains two lists of devices, a pending list and an active
  46  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  47  * pending list.  A successful driver probe will trigger moving all devices
  48  * from the pending to the active list so that the workqueue will eventually
  49  * retry them.
  50  *
  51  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  52  * of the (struct device*)->p->deferred_probe pointers are manipulated
  53  */
  54 static DEFINE_MUTEX(deferred_probe_mutex);
  55 static LIST_HEAD(deferred_probe_pending_list);
  56 static LIST_HEAD(deferred_probe_active_list);
  57 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
  58 static bool initcalls_done;
  59
  60 /* Save the async probe drivers' name from kernel cmdline */
  61 #define ASYNC_DRV_NAMES_MAX_LEN 256
  62 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
  63 static bool async_probe_default;
  64
  65 /*
  66  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  67  * to prohibit probing of devices as it could be unsafe.
  68  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  69  */
  70 static bool defer_all_probes;
  71
  72 static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
  73 {
  74         kfree(dev->p->deferred_probe_reason);
  75         dev->p->deferred_probe_reason = reason;
  76 }
  77
  78 /*
  79  * deferred_probe_work_func() - Retry probing devices in the active list.
  80  */
  81 static void deferred_probe_work_func(struct work_struct *work)
  82 {
  83         struct device *dev;
  84         struct device_private *private;
  85         /*
  86          * This block processes every device in the deferred 'active' list.
  87          * Each device is removed from the active list and passed to
  88          * bus_probe_device() to re-attempt the probe.  The loop continues
  89          * until every device in the active list is removed and retried.
  90          *
  91          * Note: Once the device is removed from the list and the mutex is
  92          * released, it is possible for the device get freed by another thread
  93          * and cause a illegal pointer dereference.  This code uses
  94          * get/put_device() to ensure the device structure cannot disappear
  95          * from under our feet.
  96          */
  97         mutex_lock(&deferred_probe_mutex);
  98         while (!list_empty(&deferred_probe_active_list)) {
  99                 private = list_first_entry(&deferred_probe_active_list,
 100                                         typeof(*dev->p), deferred_probe);
 101                 dev = private->device;
 102                 list_del_init(&private->deferred_probe);
 103
 104                 get_device(dev);
 105
 106                 __device_set_deferred_probe_reason(dev, NULL);
 107
 108                 /*
 109                  * Drop the mutex while probing each device; the probe path may
 110                  * manipulate the deferred list
 111                  */
 112                 mutex_unlock(&deferred_probe_mutex);
 113
 114                 /*
 115                  * Force the device to the end of the dpm_list since
 116                  * the PM code assumes that the order we add things to
 117                  * the list is a good order for suspend but deferred
 118                  * probe makes that very unsafe.
 119                  */
 120                 device_pm_move_to_tail(dev);
 121
 122                 dev_dbg(dev, "Retrying from deferred list\n");
 123                 bus_probe_device(dev);
 124                 mutex_lock(&deferred_probe_mutex);
 125
 126                 put_device(dev);
 127         }
 128         mutex_unlock(&deferred_probe_mutex);
 129 }
 130 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 131
 132 void driver_deferred_probe_add(struct device *dev)
 133 {
 134         if (!dev->can_match)
 135                 return;
 136
 137         mutex_lock(&deferred_probe_mutex);
 138         if (list_empty(&dev->p->deferred_probe)) {
 139                 dev_dbg(dev, "Added to deferred list\n");
 140                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 141         }
 142         mutex_unlock(&deferred_probe_mutex);
 143 }
 144
 145 void driver_deferred_probe_del(struct device *dev)
 146 {
 147         mutex_lock(&deferred_probe_mutex);
 148         if (!list_empty(&dev->p->deferred_probe)) {
 149                 dev_dbg(dev, "Removed from deferred list\n");
 150                 list_del_init(&dev->p->deferred_probe);
 151                 __device_set_deferred_probe_reason(dev, NULL);
 152         }
 153         mutex_unlock(&deferred_probe_mutex);
 154 }
 155
 156 static bool driver_deferred_probe_enable;
 157 /**
 158  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 159  *
 160  * This functions moves all devices from the pending list to the active
 161  * list and schedules the deferred probe workqueue to process them.  It
 162  * should be called anytime a driver is successfully bound to a device.
 163  *
 164  * Note, there is a race condition in multi-threaded probe. In the case where
 165  * more than one device is probing at the same time, it is possible for one
 166  * probe to complete successfully while another is about to defer. If the second
 167  * depends on the first, then it will get put on the pending list after the
 168  * trigger event has already occurred and will be stuck there.
 169  *
 170  * The atomic 'deferred_trigger_count' is used to determine if a successful
 171  * trigger has occurred in the midst of probing a driver. If the trigger count
 172  * changes in the midst of a probe, then deferred processing should be triggered
 173  * again.
 174  */
 175 static void driver_deferred_probe_trigger(void)
 176 {
 177         if (!driver_deferred_probe_enable)
 178                 return;
 179
 180         /*
 181          * A successful probe means that all the devices in the pending list
 182          * should be triggered to be reprobed.  Move all the deferred devices
 183          * into the active list so they can be retried by the workqueue
 184          */
 185         mutex_lock(&deferred_probe_mutex);
 186         atomic_inc(&deferred_trigger_count);
 187         list_splice_tail_init(&deferred_probe_pending_list,
 188                               &deferred_probe_active_list);
 189         mutex_unlock(&deferred_probe_mutex);
 190
 191         /*
 192          * Kick the re-probe thread.  It may already be scheduled, but it is
 193          * safe to kick it again.
 194          */
 195         queue_work(system_unbound_wq, &deferred_probe_work);
 196 }
 197
 198 /**
 199  * device_block_probing() - Block/defer device's probes
 200  *
 201  *      It will disable probing of devices and defer their probes instead.
 202  */
 203 void device_block_probing(void)
 204 {
 205         defer_all_probes = true;
 206         /* sync with probes to avoid races. */
 207         wait_for_device_probe();
 208 }
 209
 210 /**
 211  * device_unblock_probing() - Unblock/enable device's probes
 212  *
 213  *      It will restore normal behavior and trigger re-probing of deferred
 214  * devices.
 215  */
 216 void device_unblock_probing(void)
 217 {
 218         defer_all_probes = false;
 219         driver_deferred_probe_trigger();
 220 }
 221
 222 /**
 223  * device_set_deferred_probe_reason() - Set defer probe reason message for device
 224  * @dev: the pointer to the struct device
 225  * @vaf: the pointer to va_format structure with message
 226  */
 227 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
 228 {
 229         const char *drv = dev_driver_string(dev);
 230         char *reason;
 231
 232         mutex_lock(&deferred_probe_mutex);
 233
 234         reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
 235         __device_set_deferred_probe_reason(dev, reason);
 236
 237         mutex_unlock(&deferred_probe_mutex);
 238 }
 239
 240 /*
 241  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 242  */
 243 static int deferred_devs_show(struct seq_file *s, void *data)
 244 {
 245         struct device_private *curr;
 246
 247         mutex_lock(&deferred_probe_mutex);
 248
 249         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 250                 seq_printf(s, "%s\t%s", dev_name(curr->device),
 251                            curr->device->p->deferred_probe_reason ?: "\n");
 252
 253         mutex_unlock(&deferred_probe_mutex);
 254
 255         return 0;
 256 }
 257 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 258
 259 int driver_deferred_probe_timeout;
 260 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
 261
 262 static int __init deferred_probe_timeout_setup(char *str)
 263 {
 264         int timeout;
 265
 266         if (!kstrtoint(str, 10, &timeout))
 267                 driver_deferred_probe_timeout = timeout;
 268         return 1;
 269 }
 270 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 271
 272 /**
 273  * driver_deferred_probe_check_state() - Check deferred probe state
 274  * @dev: device to check
 275  *
 276  * Return:
 277  * * -ENODEV if initcalls have completed and modules are disabled.
 278  * * -ETIMEDOUT if the deferred probe timeout was set and has expired
 279  *   and modules are enabled.
 280  * * -EPROBE_DEFER in other cases.
 281  *
 282  * Drivers or subsystems can opt-in to calling this function instead of directly
 283  * returning -EPROBE_DEFER.
 284  */
 285 int driver_deferred_probe_check_state(struct device *dev)
 286 {
 287         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 288                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 289                 return -ENODEV;
 290         }
 291
 292         if (!driver_deferred_probe_timeout && initcalls_done) {
 293                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 294                 return -ETIMEDOUT;
 295         }
 296
 297         return -EPROBE_DEFER;
 298 }
 299 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
 300
 301 static void deferred_probe_timeout_work_func(struct work_struct *work)
 302 {
 303         struct device_private *p;
 304
 305         fw_devlink_drivers_done();
 306
 307         driver_deferred_probe_timeout = 0;
 308         driver_deferred_probe_trigger();
 309         flush_work(&deferred_probe_work);
 310
 311         mutex_lock(&deferred_probe_mutex);
 312         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 313                 dev_info(p->device, "deferred probe pending\n");
 314         mutex_unlock(&deferred_probe_mutex);
 315 }
 316 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 317
 318 void deferred_probe_extend_timeout(void)
 319 {
 320         /*
 321          * If the work hasn't been queued yet or if the work expired, don't
 322          * start a new one.
 323          */
 324         if (cancel_delayed_work(&deferred_probe_timeout_work)) {
 325                 schedule_delayed_work(&deferred_probe_timeout_work,
 326                                 driver_deferred_probe_timeout * HZ);
 327                 pr_debug("Extended deferred probe timeout by %d secs\n",
 328                                         driver_deferred_probe_timeout);
 329         }
 330 }
 331
 332 /**
 333  * deferred_probe_initcall() - Enable probing of deferred devices
 334  *
 335  * We don't want to get in the way when the bulk of drivers are getting probed.
 336  * Instead, this initcall makes sure that deferred probing is delayed until
 337  * late_initcall time.
 338  */
 339 static int deferred_probe_initcall(void)
 340 {
 341         debugfs_create_file("devices_deferred", 0444, NULL, NULL,
 342                             &deferred_devs_fops);
 343
 344         driver_deferred_probe_enable = true;
 345         driver_deferred_probe_trigger();
 346         /* Sort as many dependencies as possible before exiting initcalls */
 347         flush_work(&deferred_probe_work);
 348         initcalls_done = true;
 349
 350         if (!IS_ENABLED(CONFIG_MODULES))
 351                 fw_devlink_drivers_done();
 352
 353         /*
 354          * Trigger deferred probe again, this time we won't defer anything
 355          * that is optional
 356          */
 357         driver_deferred_probe_trigger();
 358         flush_work(&deferred_probe_work);
 359
 360         if (driver_deferred_probe_timeout > 0) {
 361                 schedule_delayed_work(&deferred_probe_timeout_work,
 362                         driver_deferred_probe_timeout * HZ);
 363         }
 364         return 0;
 365 }
 366 late_initcall(deferred_probe_initcall);
 367
 368 static void __exit deferred_probe_exit(void)
 369 {
 370         debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
 371 }
 372 __exitcall(deferred_probe_exit);
 373
 374 /**
 375  * device_is_bound() - Check if device is bound to a driver
 376  * @dev: device to check
 377  *
 378  * Returns true if passed device has already finished probing successfully
 379  * against a driver.
 380  *
 381  * This function must be called with the device lock held.
 382  */
 383 bool device_is_bound(struct device *dev)
 384 {
 385         return dev->p && klist_node_attached(&dev->p->knode_driver);
 386 }
 387
 388 static void driver_bound(struct device *dev)
 389 {
 390         if (device_is_bound(dev)) {
 391                 pr_warn("%s: device %s already bound\n",
 392                         __func__, kobject_name(&dev->kobj));
 393                 return;
 394         }
 395
 396         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 397                  __func__, dev_name(dev));
 398
 399         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 400         device_links_driver_bound(dev);
 401
 402         device_pm_check_callbacks(dev);
 403
 404         /*
 405          * Make sure the device is no longer in one of the deferred lists and
 406          * kick off retrying all pending devices
 407          */
 408         driver_deferred_probe_del(dev);
 409         driver_deferred_probe_trigger();
 410
 411         if (dev->bus)
 412                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 413                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 414
 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         if (dev->bus)
 434                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 435                                              BUS_NOTIFY_BIND_DRIVER, dev);
 436
 437         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 438                                 kobject_name(&dev->kobj));
 439         if (ret)
 440                 goto fail;
 441
 442         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 443                                 "driver");
 444         if (ret)
 445                 goto rm_dev;
 446
 447         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 448                 return 0;
 449
 450         ret = device_create_file(dev, &dev_attr_coredump);
 451         if (!ret)
 452                 return 0;
 453
 454         sysfs_remove_link(&dev->kobj, "driver");
 455
 456 rm_dev:
 457         sysfs_remove_link(&dev->driver->p->kobj,
 458                           kobject_name(&dev->kobj));
 459
 460 fail:
 461         return ret;
 462 }
 463
 464 static void driver_sysfs_remove(struct device *dev)
 465 {
 466         struct device_driver *drv = dev->driver;
 467
 468         if (drv) {
 469                 if (drv->coredump)
 470                         device_remove_file(dev, &dev_attr_coredump);
 471                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 472                 sysfs_remove_link(&dev->kobj, "driver");
 473         }
 474 }
 475
 476 /**
 477  * device_bind_driver - bind a driver to one device.
 478  * @dev: device.
 479  *
 480  * Allow manual attachment of a driver to a device.
 481  * Caller must have already set @dev->driver.
 482  *
 483  * Note that this does not modify the bus reference count.
 484  * Please verify that is accounted for before calling this.
 485  * (It is ok to call with no other effort from a driver's probe() method.)
 486  *
 487  * This function must be called with the device lock held.
 488  *
 489  * Callers should prefer to use device_driver_attach() instead.
 490  */
 491 int device_bind_driver(struct device *dev)
 492 {
 493         int ret;
 494
 495         ret = driver_sysfs_add(dev);
 496         if (!ret) {
 497                 device_links_force_bind(dev);
 498                 driver_bound(dev);
 499         }
 500         else if (dev->bus)
 501                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 502                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 503         return ret;
 504 }
 505 EXPORT_SYMBOL_GPL(device_bind_driver);
 506
 507 static atomic_t probe_count = ATOMIC_INIT(0);
 508 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 509
 510 static ssize_t state_synced_show(struct device *dev,
 511                                  struct device_attribute *attr, char *buf)
 512 {
 513         bool val;
 514
 515         device_lock(dev);
 516         val = dev->state_synced;
 517         device_unlock(dev);
 518
 519         return sysfs_emit(buf, "%u\n", val);
 520 }
 521 static DEVICE_ATTR_RO(state_synced);
 522
 523 static void device_unbind_cleanup(struct device *dev)
 524 {
 525         devres_release_all(dev);
 526         arch_teardown_dma_ops(dev);
 527         kfree(dev->dma_range_map);
 528         dev->dma_range_map = NULL;
 529         dev->driver = NULL;
 530         dev_set_drvdata(dev, NULL);
 531         if (dev->pm_domain && dev->pm_domain->dismiss)
 532                 dev->pm_domain->dismiss(dev);
 533         pm_runtime_reinit(dev);
 534         dev_pm_set_driver_flags(dev, 0);
 535 }
 536
 537 static void device_remove(struct device *dev)
 538 {
 539         device_remove_file(dev, &dev_attr_state_synced);
 540         device_remove_groups(dev, dev->driver->dev_groups);
 541
 542         if (dev->bus && dev->bus->remove)
 543                 dev->bus->remove(dev);
 544         else if (dev->driver->remove)
 545                 dev->driver->remove(dev);
 546 }
 547
 548 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 549 {
 550         int ret = 0;
 551
 552         if (dev->bus->probe)
 553                 ret = dev->bus->probe(dev);
 554         else if (drv->probe)
 555                 ret = drv->probe(dev);
 556
 557         switch (ret) {
 558         case 0:
 559                 break;
 560         case -EPROBE_DEFER:
 561                 /* Driver requested deferred probing */
 562                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 563                 break;
 564         case -ENODEV:
 565         case -ENXIO:
 566                 pr_debug("%s: probe of %s rejects match %d\n",
 567                          drv->name, dev_name(dev), ret);
 568                 break;
 569         default:
 570                 /* driver matched but the probe failed */
 571                 pr_warn("%s: probe of %s failed with error %d\n",
 572                         drv->name, dev_name(dev), ret);
 573                 break;
 574         }
 575
 576         return ret;
 577 }
 578
 579 static int really_probe(struct device *dev, struct device_driver *drv)
 580 {
 581         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 582                            !drv->suppress_bind_attrs;
 583         int ret;
 584
 585         if (defer_all_probes) {
 586                 /*
 587                  * Value of defer_all_probes can be set only by
 588                  * device_block_probing() which, in turn, will call
 589                  * wait_for_device_probe() right after that to avoid any races.
 590                  */
 591                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 592                 return -EPROBE_DEFER;
 593         }
 594
 595         ret = device_links_check_suppliers(dev);
 596         if (ret)
 597                 return ret;
 598
 599         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 600                  drv->bus->name, __func__, drv->name, dev_name(dev));
 601         if (!list_empty(&dev->devres_head)) {
 602                 dev_crit(dev, "Resources present before probing\n");
 603                 ret = -EBUSY;
 604                 goto done;
 605         }
 606
 607 re_probe:
 608         dev->driver = drv;
 609
 610         /* If using pinctrl, bind pins now before probing */
 611         ret = pinctrl_bind_pins(dev);
 612         if (ret)
 613                 goto pinctrl_bind_failed;
 614
 615         if (dev->bus->dma_configure) {
 616                 ret = dev->bus->dma_configure(dev);
 617                 if (ret)
 618                         goto pinctrl_bind_failed;
 619         }
 620
 621         ret = driver_sysfs_add(dev);
 622         if (ret) {
 623                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 624                        __func__, dev_name(dev));
 625                 goto sysfs_failed;
 626         }
 627
 628         if (dev->pm_domain && dev->pm_domain->activate) {
 629                 ret = dev->pm_domain->activate(dev);
 630                 if (ret)
 631                         goto probe_failed;
 632         }
 633
 634         ret = call_driver_probe(dev, drv);
 635         if (ret) {
 636                 /*
 637                  * Return probe errors as positive values so that the callers
 638                  * can distinguish them from other errors.
 639                  */
 640                 ret = -ret;
 641                 goto probe_failed;
 642         }
 643
 644         ret = device_add_groups(dev, drv->dev_groups);
 645         if (ret) {
 646                 dev_err(dev, "device_add_groups() failed\n");
 647                 goto dev_groups_failed;
 648         }
 649
 650         if (dev_has_sync_state(dev)) {
 651                 ret = device_create_file(dev, &dev_attr_state_synced);
 652                 if (ret) {
 653                         dev_err(dev, "state_synced sysfs add failed\n");
 654                         goto dev_sysfs_state_synced_failed;
 655                 }
 656         }
 657
 658         if (test_remove) {
 659                 test_remove = false;
 660
 661                 device_remove(dev);
 662                 driver_sysfs_remove(dev);
 663                 device_unbind_cleanup(dev);
 664
 665                 goto re_probe;
 666         }
 667
 668         pinctrl_init_done(dev);
 669
 670         if (dev->pm_domain && dev->pm_domain->sync)
 671                 dev->pm_domain->sync(dev);
 672
 673         driver_bound(dev);
 674         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 675                  drv->bus->name, __func__, dev_name(dev), drv->name);
 676         goto done;
 677
 678 dev_sysfs_state_synced_failed:
 679 dev_groups_failed:
 680         device_remove(dev);
 681 probe_failed:
 682         driver_sysfs_remove(dev);
 683 sysfs_failed:
 684         if (dev->bus)
 685                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 686                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 687         if (dev->bus && dev->bus->dma_cleanup)
 688                 dev->bus->dma_cleanup(dev);
 689 pinctrl_bind_failed:
 690         device_links_no_driver(dev);
 691         device_unbind_cleanup(dev);
 692 done:
 693         return ret;
 694 }
 695
 696 /*
 697  * For initcall_debug, show the driver probe time.
 698  */
 699 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 700 {
 701         ktime_t calltime, rettime;
 702         int ret;
 703
 704         calltime = ktime_get();
 705         ret = really_probe(dev, drv);
 706         rettime = ktime_get();
 707         pr_debug("probe of %s returned %d after %lld usecs\n",
 708                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 709         return ret;
 710 }
 711
 712 /**
 713  * driver_probe_done
 714  * Determine if the probe sequence is finished or not.
 715  *
 716  * Should somehow figure out how to use a semaphore, not an atomic variable...
 717  */
 718 int driver_probe_done(void)
 719 {
 720         int local_probe_count = atomic_read(&probe_count);
 721
 722         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 723         if (local_probe_count)
 724                 return -EBUSY;
 725         return 0;
 726 }
 727
 728 /**
 729  * wait_for_device_probe
 730  * Wait for device probing to be completed.
 731  */
 732 void wait_for_device_probe(void)
 733 {
 734         /* wait for the deferred probe workqueue to finish */
 735         flush_work(&deferred_probe_work);
 736
 737         /* wait for the known devices to complete their probing */
 738         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 739         async_synchronize_full();
 740 }
 741 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 742
 743 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 744 {
 745         int ret = 0;
 746
 747         if (dev->p->dead || !device_is_registered(dev))
 748                 return -ENODEV;
 749         if (dev->driver)
 750                 return -EBUSY;
 751
 752         dev->can_match = true;
 753         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 754                  drv->bus->name, __func__, dev_name(dev), drv->name);
 755
 756         pm_runtime_get_suppliers(dev);
 757         if (dev->parent)
 758                 pm_runtime_get_sync(dev->parent);
 759
 760         pm_runtime_barrier(dev);
 761         if (initcall_debug)
 762                 ret = really_probe_debug(dev, drv);
 763         else
 764                 ret = really_probe(dev, drv);
 765         pm_request_idle(dev);
 766
 767         if (dev->parent)
 768                 pm_runtime_put(dev->parent);
 769
 770         pm_runtime_put_suppliers(dev);
 771         return ret;
 772 }
 773
 774 /**
 775  * driver_probe_device - attempt to bind device & driver together
 776  * @drv: driver to bind a device to
 777  * @dev: device to try to bind to the driver
 778  *
 779  * This function returns -ENODEV if the device is not registered, -EBUSY if it
 780  * already has a driver, 0 if the device is bound successfully and a positive
 781  * (inverted) error code for failures from the ->probe method.
 782  *
 783  * This function must be called with @dev lock held.  When called for a
 784  * USB interface, @dev->parent lock must be held as well.
 785  *
 786  * If the device has a parent, runtime-resume the parent before driver probing.
 787  */
 788 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 789 {
 790         int trigger_count = atomic_read(&deferred_trigger_count);
 791         int ret;
 792
 793         atomic_inc(&probe_count);
 794         ret = __driver_probe_device(drv, dev);
 795         if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
 796                 driver_deferred_probe_add(dev);
 797
 798                 /*
 799                  * Did a trigger occur while probing? Need to re-trigger if yes
 800                  */
 801                 if (trigger_count != atomic_read(&deferred_trigger_count) &&
 802                     !defer_all_probes)
 803                         driver_deferred_probe_trigger();
 804         }
 805         atomic_dec(&probe_count);
 806         wake_up_all(&probe_waitqueue);
 807         return ret;
 808 }
 809
 810 static inline bool cmdline_requested_async_probing(const char *drv_name)
 811 {
 812         bool async_drv;
 813
 814         async_drv = parse_option_str(async_probe_drv_names, drv_name);
 815
 816         return (async_probe_default != async_drv);
 817 }
 818
 819 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 820 static int __init save_async_options(char *buf)
 821 {
 822         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 823                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 824
 825         strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 826         async_probe_default = parse_option_str(async_probe_drv_names, "*");
 827
 828         return 1;
 829 }
 830 __setup("driver_async_probe=", save_async_options);
 831
 832 bool driver_allows_async_probing(struct device_driver *drv)
 833 {
 834         switch (drv->probe_type) {
 835         case PROBE_PREFER_ASYNCHRONOUS:
 836                 return true;
 837
 838         case PROBE_FORCE_SYNCHRONOUS:
 839                 return false;
 840
 841         default:
 842                 if (cmdline_requested_async_probing(drv->name))
 843                         return true;
 844
 845                 if (module_requested_async_probing(drv->owner))
 846                         return true;
 847
 848                 return false;
 849         }
 850 }
 851
 852 struct device_attach_data {
 853         struct device *dev;
 854
 855         /*
 856          * Indicates whether we are considering asynchronous probing or
 857          * not. Only initial binding after device or driver registration
 858          * (including deferral processing) may be done asynchronously, the
 859          * rest is always synchronous, as we expect it is being done by
 860          * request from userspace.
 861          */
 862         bool check_async;
 863
 864         /*
 865          * Indicates if we are binding synchronous or asynchronous drivers.
 866          * When asynchronous probing is enabled we'll execute 2 passes
 867          * over drivers: first pass doing synchronous probing and second
 868          * doing asynchronous probing (if synchronous did not succeed -
 869          * most likely because there was no driver requiring synchronous
 870          * probing - and we found asynchronous driver during first pass).
 871          * The 2 passes are done because we can't shoot asynchronous
 872          * probe for given device and driver from bus_for_each_drv() since
 873          * driver pointer is not guaranteed to stay valid once
 874          * bus_for_each_drv() iterates to the next driver on the bus.
 875          */
 876         bool want_async;
 877
 878         /*
 879          * We'll set have_async to 'true' if, while scanning for matching
 880          * driver, we'll encounter one that requests asynchronous probing.
 881          */
 882         bool have_async;
 883 };
 884
 885 static int __device_attach_driver(struct device_driver *drv, void *_data)
 886 {
 887         struct device_attach_data *data = _data;
 888         struct device *dev = data->dev;
 889         bool async_allowed;
 890         int ret;
 891
 892         ret = driver_match_device(drv, dev);
 893         if (ret == 0) {
 894                 /* no match */
 895                 return 0;
 896         } else if (ret == -EPROBE_DEFER) {
 897                 dev_dbg(dev, "Device match requests probe deferral\n");
 898                 dev->can_match = true;
 899                 driver_deferred_probe_add(dev);
 900         } else if (ret < 0) {
 901                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 902                 return ret;
 903         } /* ret > 0 means positive match */
 904
 905         async_allowed = driver_allows_async_probing(drv);
 906
 907         if (async_allowed)
 908                 data->have_async = true;
 909
 910         if (data->check_async && async_allowed != data->want_async)
 911                 return 0;
 912
 913         /*
 914          * Ignore errors returned by ->probe so that the next driver can try
 915          * its luck.
 916          */
 917         ret = driver_probe_device(drv, dev);
 918         if (ret < 0)
 919                 return ret;
 920         return ret == 0;
 921 }
 922
 923 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 924 {
 925         struct device *dev = _dev;
 926         struct device_attach_data data = {
 927                 .dev            = dev,
 928                 .check_async    = true,
 929                 .want_async     = true,
 930         };
 931
 932         device_lock(dev);
 933
 934         /*
 935          * Check if device has already been removed or claimed. This may
 936          * happen with driver loading, device discovery/registration,
 937          * and deferred probe processing happens all at once with
 938          * multiple threads.
 939          */
 940         if (dev->p->dead || dev->driver)
 941                 goto out_unlock;
 942
 943         if (dev->parent)
 944                 pm_runtime_get_sync(dev->parent);
 945
 946         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 947         dev_dbg(dev, "async probe completed\n");
 948
 949         pm_request_idle(dev);
 950
 951         if (dev->parent)
 952                 pm_runtime_put(dev->parent);
 953 out_unlock:
 954         device_unlock(dev);
 955
 956         put_device(dev);
 957 }
 958
 959 static int __device_attach(struct device *dev, bool allow_async)
 960 {
 961         int ret = 0;
 962         bool async = false;
 963
 964         device_lock(dev);
 965         if (dev->p->dead) {
 966                 goto out_unlock;
 967         } else if (dev->driver) {
 968                 if (device_is_bound(dev)) {
 969                         ret = 1;
 970                         goto out_unlock;
 971                 }
 972                 ret = device_bind_driver(dev);
 973                 if (ret == 0)
 974                         ret = 1;
 975                 else {
 976                         dev->driver = NULL;
 977                         ret = 0;
 978                 }
 979         } else {
 980                 struct device_attach_data data = {
 981                         .dev = dev,
 982                         .check_async = allow_async,
 983                         .want_async = false,
 984                 };
 985
 986                 if (dev->parent)
 987                         pm_runtime_get_sync(dev->parent);
 988
 989                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 990                                         __device_attach_driver);
 991                 if (!ret && allow_async && data.have_async) {
 992                         /*
 993                          * If we could not find appropriate driver
 994                          * synchronously and we are allowed to do
 995                          * async probes and there are drivers that
 996                          * want to probe asynchronously, we'll
 997                          * try them.
 998                          */
 999                         dev_dbg(dev, "scheduling asynchronous probe\n");
1000                         get_device(dev);
1001                         async = true;
1002                 } else {
1003                         pm_request_idle(dev);
1004                 }
1005
1006                 if (dev->parent)
1007                         pm_runtime_put(dev->parent);
1008         }
1009 out_unlock:
1010         device_unlock(dev);
1011         if (async)
1012                 async_schedule_dev(__device_attach_async_helper, dev);
1013         return ret;
1014 }
1015
1016 /**
1017  * device_attach - try to attach device to a driver.
1018  * @dev: device.
1019  *
1020  * Walk the list of drivers that the bus has and call
1021  * driver_probe_device() for each pair. If a compatible
1022  * pair is found, break out and return.
1023  *
1024  * Returns 1 if the device was bound to a driver;
1025  * 0 if no matching driver was found;
1026  * -ENODEV if the device is not registered.
1027  *
1028  * When called for a USB interface, @dev->parent lock must be held.
1029  */
1030 int device_attach(struct device *dev)
1031 {
1032         return __device_attach(dev, false);
1033 }
1034 EXPORT_SYMBOL_GPL(device_attach);
1035
1036 void device_initial_probe(struct device *dev)
1037 {
1038         __device_attach(dev, true);
1039 }
1040
1041 /*
1042  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1043  * @dev: Device we will update driver info for
1044  * @parent: Parent device. Needed if the bus requires parent lock
1045  *
1046  * This function will take the required locks for manipulating dev->drv.
1047  * Normally this will just be the @dev lock, but when called for a USB
1048  * interface, @parent lock will be held as well.
1049  */
1050 static void __device_driver_lock(struct device *dev, struct device *parent)
1051 {
1052         if (parent && dev->bus->need_parent_lock)
1053                 device_lock(parent);
1054         device_lock(dev);
1055 }
1056
1057 /*
1058  * __device_driver_unlock - release locks needed to manipulate dev->drv
1059  * @dev: Device we will update driver info for
1060  * @parent: Parent device. Needed if the bus requires parent lock
1061  *
1062  * This function will release the required locks for manipulating dev->drv.
1063  * Normally this will just be the @dev lock, but when called for a
1064  * USB interface, @parent lock will be released as well.
1065  */
1066 static void __device_driver_unlock(struct device *dev, struct device *parent)
1067 {
1068         device_unlock(dev);
1069         if (parent && dev->bus->need_parent_lock)
1070                 device_unlock(parent);
1071 }
1072
1073 /**
1074  * device_driver_attach - attach a specific driver to a specific device
1075  * @drv: Driver to attach
1076  * @dev: Device to attach it to
1077  *
1078  * Manually attach driver to a device. Will acquire both @dev lock and
1079  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1080  */
1081 int device_driver_attach(struct device_driver *drv, struct device *dev)
1082 {
1083         int ret;
1084
1085         __device_driver_lock(dev, dev->parent);
1086         ret = __driver_probe_device(drv, dev);
1087         __device_driver_unlock(dev, dev->parent);
1088
1089         /* also return probe errors as normal negative errnos */
1090         if (ret > 0)
1091                 ret = -ret;
1092         if (ret == -EPROBE_DEFER)
1093                 return -EAGAIN;
1094         return ret;
1095 }
1096 EXPORT_SYMBOL_GPL(device_driver_attach);
1097
1098 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1099 {
1100         struct device *dev = _dev;
1101         struct device_driver *drv;
1102         int ret;
1103
1104         __device_driver_lock(dev, dev->parent);
1105         drv = dev->p->async_driver;
1106         dev->p->async_driver = NULL;
1107         ret = driver_probe_device(drv, dev);
1108         __device_driver_unlock(dev, dev->parent);
1109
1110         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1111
1112         put_device(dev);
1113 }
1114
1115 static int __driver_attach(struct device *dev, void *data)
1116 {
1117         struct device_driver *drv = data;
1118         int ret;
1119
1120         /*
1121          * Lock device and try to bind to it. We drop the error
1122          * here and always return 0, because we need to keep trying
1123          * to bind to devices and some drivers will return an error
1124          * simply if it didn't support the device.
1125          *
1126          * driver_probe_device() will spit a warning if there
1127          * is an error.
1128          */
1129
1130         ret = driver_match_device(drv, dev);
1131         if (ret == 0) {
1132                 /* no match */
1133                 return 0;
1134         } else if (ret == -EPROBE_DEFER) {
1135                 dev_dbg(dev, "Device match requests probe deferral\n");
1136                 dev->can_match = true;
1137                 driver_deferred_probe_add(dev);
1138         } else if (ret < 0) {
1139                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1140                 return ret;
1141         } /* ret > 0 means positive match */
1142
1143         if (driver_allows_async_probing(drv)) {
1144                 /*
1145                  * Instead of probing the device synchronously we will
1146                  * probe it asynchronously to allow for more parallelism.
1147                  *
1148                  * We only take the device lock here in order to guarantee
1149                  * that the dev->driver and async_driver fields are protected
1150                  */
1151                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1152                 device_lock(dev);
1153                 if (!dev->driver && !dev->p->async_driver) {
1154                         get_device(dev);
1155                         dev->p->async_driver = drv;
1156                         async_schedule_dev(__driver_attach_async_helper, dev);
1157                 }
1158                 device_unlock(dev);
1159                 return 0;
1160         }
1161
1162         __device_driver_lock(dev, dev->parent);
1163         driver_probe_device(drv, dev);
1164         __device_driver_unlock(dev, dev->parent);
1165
1166         return 0;
1167 }
1168
1169 /**
1170  * driver_attach - try to bind driver to devices.
1171  * @drv: driver.
1172  *
1173  * Walk the list of devices that the bus has on it and try to
1174  * match the driver with each one.  If driver_probe_device()
1175  * returns 0 and the @dev->driver is set, we've found a
1176  * compatible pair.
1177  */
1178 int driver_attach(struct device_driver *drv)
1179 {
1180         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1181 }
1182 EXPORT_SYMBOL_GPL(driver_attach);
1183
1184 /*
1185  * __device_release_driver() must be called with @dev lock held.
1186  * When called for a USB interface, @dev->parent lock must be held as well.
1187  */
1188 static void __device_release_driver(struct device *dev, struct device *parent)
1189 {
1190         struct device_driver *drv;
1191
1192         drv = dev->driver;
1193         if (drv) {
1194                 pm_runtime_get_sync(dev);
1195
1196                 while (device_links_busy(dev)) {
1197                         __device_driver_unlock(dev, parent);
1198
1199                         device_links_unbind_consumers(dev);
1200
1201                         __device_driver_lock(dev, parent);
1202                         /*
1203                          * A concurrent invocation of the same function might
1204                          * have released the driver successfully while this one
1205                          * was waiting, so check for that.
1206                          */
1207                         if (dev->driver != drv) {
1208                                 pm_runtime_put(dev);
1209                                 return;
1210                         }
1211                 }
1212
1213                 driver_sysfs_remove(dev);
1214
1215                 if (dev->bus)
1216                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1217                                                      BUS_NOTIFY_UNBIND_DRIVER,
1218                                                      dev);
1219
1220                 pm_runtime_put_sync(dev);
1221
1222                 device_remove(dev);
1223
1224                 if (dev->bus && dev->bus->dma_cleanup)
1225                         dev->bus->dma_cleanup(dev);
1226
1227                 device_links_driver_cleanup(dev);
1228                 device_unbind_cleanup(dev);
1229
1230                 klist_remove(&dev->p->knode_driver);
1231                 device_pm_check_callbacks(dev);
1232                 if (dev->bus)
1233                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1234                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1235                                                      dev);
1236
1237                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1238         }
1239 }
1240
1241 void device_release_driver_internal(struct device *dev,
1242                                     struct device_driver *drv,
1243                                     struct device *parent)
1244 {
1245         __device_driver_lock(dev, parent);
1246
1247         if (!drv || drv == dev->driver)
1248                 __device_release_driver(dev, parent);
1249
1250         __device_driver_unlock(dev, parent);
1251 }
1252
1253 /**
1254  * device_release_driver - manually detach device from driver.
1255  * @dev: device.
1256  *
1257  * Manually detach device from driver.
1258  * When called for a USB interface, @dev->parent lock must be held.
1259  *
1260  * If this function is to be called with @dev->parent lock held, ensure that
1261  * the device's consumers are unbound in advance or that their locks can be
1262  * acquired under the @dev->parent lock.
1263  */
1264 void device_release_driver(struct device *dev)
1265 {
1266         /*
1267          * If anyone calls device_release_driver() recursively from
1268          * within their ->remove callback for the same device, they
1269          * will deadlock right here.
1270          */
1271         device_release_driver_internal(dev, NULL, NULL);
1272 }
1273 EXPORT_SYMBOL_GPL(device_release_driver);
1274
1275 /**
1276  * device_driver_detach - detach driver from a specific device
1277  * @dev: device to detach driver from
1278  *
1279  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1280  * lock if needed.
1281  */
1282 void device_driver_detach(struct device *dev)
1283 {
1284         device_release_driver_internal(dev, NULL, dev->parent);
1285 }
1286
1287 /**
1288  * driver_detach - detach driver from all devices it controls.
1289  * @drv: driver.
1290  */
1291 void driver_detach(struct device_driver *drv)
1292 {
1293         struct device_private *dev_prv;
1294         struct device *dev;
1295
1296         if (driver_allows_async_probing(drv))
1297                 async_synchronize_full();
1298
1299         for (;;) {
1300                 spin_lock(&drv->p->klist_devices.k_lock);
1301                 if (list_empty(&drv->p->klist_devices.k_list)) {
1302                         spin_unlock(&drv->p->klist_devices.k_lock);
1303                         break;
1304                 }
1305                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1306                                      struct device_private,
1307                                      knode_driver.n_node);
1308                 dev = dev_prv->device;
1309                 get_device(dev);
1310                 spin_unlock(&drv->p->klist_devices.k_lock);
1311                 device_release_driver_internal(dev, drv, dev->parent);
1312                 put_device(dev);
1313         }
1314 }