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-mapping.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
  31 #include "base.h"
  32 #include "power/power.h"
  33
  34 /*
  35  * Deferred Probe infrastructure.
  36  *
  37  * Sometimes driver probe order matters, but the kernel doesn't always have
  38  * dependency information which means some drivers will get probed before a
  39  * resource it depends on is available.  For example, an SDHCI driver may
  40  * first need a GPIO line from an i2c GPIO controller before it can be
  41  * initialized.  If a required resource is not available yet, a driver can
  42  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  43  *
  44  * Deferred probe maintains two lists of devices, a pending list and an active
  45  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  46  * pending list.  A successful driver probe will trigger moving all devices
  47  * from the pending to the active list so that the workqueue will eventually
  48  * retry them.
  49  *
  50  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  51  * of the (struct device*)->p->deferred_probe pointers are manipulated
  52  */
  53 static DEFINE_MUTEX(deferred_probe_mutex);
  54 static LIST_HEAD(deferred_probe_pending_list);
  55 static LIST_HEAD(deferred_probe_active_list);
  56 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
  57 static struct dentry *deferred_devices;
  58 static bool initcalls_done;
  59
  60 /* Save the async probe drivers' name from kernel cmdline */
  61 #define ASYNC_DRV_NAMES_MAX_LEN 256
  62 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
  63
  64 /*
  65  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  66  * to prohibit probing of devices as it could be unsafe.
  67  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  68  */
  69 static bool defer_all_probes;
  70
  71 /*
  72  * deferred_probe_work_func() - Retry probing devices in the active list.
  73  */
  74 static void deferred_probe_work_func(struct work_struct *work)
  75 {
  76         struct device *dev;
  77         struct device_private *private;
  78         /*
  79          * This block processes every device in the deferred 'active' list.
  80          * Each device is removed from the active list and passed to
  81          * bus_probe_device() to re-attempt the probe.  The loop continues
  82          * until every device in the active list is removed and retried.
  83          *
  84          * Note: Once the device is removed from the list and the mutex is
  85          * released, it is possible for the device get freed by another thread
  86          * and cause a illegal pointer dereference.  This code uses
  87          * get/put_device() to ensure the device structure cannot disappear
  88          * from under our feet.
  89          */
  90         mutex_lock(&deferred_probe_mutex);
  91         while (!list_empty(&deferred_probe_active_list)) {
  92                 private = list_first_entry(&deferred_probe_active_list,
  93                                         typeof(*dev->p), deferred_probe);
  94                 dev = private->device;
  95                 list_del_init(&private->deferred_probe);
  96
  97                 get_device(dev);
  98
  99                 /*
 100                  * Drop the mutex while probing each device; the probe path may
 101                  * manipulate the deferred list
 102                  */
 103                 mutex_unlock(&deferred_probe_mutex);
 104
 105                 /*
 106                  * Force the device to the end of the dpm_list since
 107                  * the PM code assumes that the order we add things to
 108                  * the list is a good order for suspend but deferred
 109                  * probe makes that very unsafe.
 110                  */
 111                 device_pm_move_to_tail(dev);
 112
 113                 dev_dbg(dev, "Retrying from deferred list\n");
 114                 bus_probe_device(dev);
 115                 mutex_lock(&deferred_probe_mutex);
 116
 117                 put_device(dev);
 118         }
 119         mutex_unlock(&deferred_probe_mutex);
 120 }
 121 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 122
 123 void driver_deferred_probe_add(struct device *dev)
 124 {
 125         mutex_lock(&deferred_probe_mutex);
 126         if (list_empty(&dev->p->deferred_probe)) {
 127                 dev_dbg(dev, "Added to deferred list\n");
 128                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 129         }
 130         mutex_unlock(&deferred_probe_mutex);
 131 }
 132
 133 void driver_deferred_probe_del(struct device *dev)
 134 {
 135         mutex_lock(&deferred_probe_mutex);
 136         if (!list_empty(&dev->p->deferred_probe)) {
 137                 dev_dbg(dev, "Removed from deferred list\n");
 138                 list_del_init(&dev->p->deferred_probe);
 139         }
 140         mutex_unlock(&deferred_probe_mutex);
 141 }
 142
 143 static bool driver_deferred_probe_enable = false;
 144 /**
 145  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 146  *
 147  * This functions moves all devices from the pending list to the active
 148  * list and schedules the deferred probe workqueue to process them.  It
 149  * should be called anytime a driver is successfully bound to a device.
 150  *
 151  * Note, there is a race condition in multi-threaded probe. In the case where
 152  * more than one device is probing at the same time, it is possible for one
 153  * probe to complete successfully while another is about to defer. If the second
 154  * depends on the first, then it will get put on the pending list after the
 155  * trigger event has already occurred and will be stuck there.
 156  *
 157  * The atomic 'deferred_trigger_count' is used to determine if a successful
 158  * trigger has occurred in the midst of probing a driver. If the trigger count
 159  * changes in the midst of a probe, then deferred processing should be triggered
 160  * again.
 161  */
 162 static void driver_deferred_probe_trigger(void)
 163 {
 164         if (!driver_deferred_probe_enable)
 165                 return;
 166
 167         /*
 168          * A successful probe means that all the devices in the pending list
 169          * should be triggered to be reprobed.  Move all the deferred devices
 170          * into the active list so they can be retried by the workqueue
 171          */
 172         mutex_lock(&deferred_probe_mutex);
 173         atomic_inc(&deferred_trigger_count);
 174         list_splice_tail_init(&deferred_probe_pending_list,
 175                               &deferred_probe_active_list);
 176         mutex_unlock(&deferred_probe_mutex);
 177
 178         /*
 179          * Kick the re-probe thread.  It may already be scheduled, but it is
 180          * safe to kick it again.
 181          */
 182         schedule_work(&deferred_probe_work);
 183 }
 184
 185 /**
 186  * device_block_probing() - Block/defer device's probes
 187  *
 188  *      It will disable probing of devices and defer their probes instead.
 189  */
 190 void device_block_probing(void)
 191 {
 192         defer_all_probes = true;
 193         /* sync with probes to avoid races. */
 194         wait_for_device_probe();
 195 }
 196
 197 /**
 198  * device_unblock_probing() - Unblock/enable device's probes
 199  *
 200  *      It will restore normal behavior and trigger re-probing of deferred
 201  * devices.
 202  */
 203 void device_unblock_probing(void)
 204 {
 205         defer_all_probes = false;
 206         driver_deferred_probe_trigger();
 207 }
 208
 209 /*
 210  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 211  */
 212 static int deferred_devs_show(struct seq_file *s, void *data)
 213 {
 214         struct device_private *curr;
 215
 216         mutex_lock(&deferred_probe_mutex);
 217
 218         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 219                 seq_printf(s, "%s\n", dev_name(curr->device));
 220
 221         mutex_unlock(&deferred_probe_mutex);
 222
 223         return 0;
 224 }
 225 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 226
 227 static int deferred_probe_timeout = -1;
 228 static int __init deferred_probe_timeout_setup(char *str)
 229 {
 230         int timeout;
 231
 232         if (!kstrtoint(str, 10, &timeout))
 233                 deferred_probe_timeout = timeout;
 234         return 1;
 235 }
 236 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 237
 238 static int __driver_deferred_probe_check_state(struct device *dev)
 239 {
 240         if (!initcalls_done)
 241                 return -EPROBE_DEFER;
 242
 243         if (!deferred_probe_timeout) {
 244                 dev_WARN(dev, "deferred probe timeout, ignoring dependency");
 245                 return -ETIMEDOUT;
 246         }
 247
 248         return 0;
 249 }
 250
 251 /**
 252  * driver_deferred_probe_check_state() - Check deferred probe state
 253  * @dev: device to check
 254  *
 255  * Returns -ENODEV if init is done and all built-in drivers have had a chance
 256  * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug
 257  * timeout has expired, or -EPROBE_DEFER if none of those conditions are met.
 258  *
 259  * Drivers or subsystems can opt-in to calling this function instead of directly
 260  * returning -EPROBE_DEFER.
 261  */
 262 int driver_deferred_probe_check_state(struct device *dev)
 263 {
 264         int ret;
 265
 266         ret = __driver_deferred_probe_check_state(dev);
 267         if (ret < 0)
 268                 return ret;
 269
 270         dev_warn(dev, "ignoring dependency for device, assuming no driver");
 271
 272         return -ENODEV;
 273 }
 274
 275 /**
 276  * driver_deferred_probe_check_state_continue() - check deferred probe state
 277  * @dev: device to check
 278  *
 279  * Returns -ETIMEDOUT if deferred probe debug timeout has expired, or
 280  * -EPROBE_DEFER otherwise.
 281  *
 282  * Drivers or subsystems can opt-in to calling this function instead of
 283  * directly returning -EPROBE_DEFER.
 284  *
 285  * This is similar to driver_deferred_probe_check_state(), but it allows the
 286  * subsystem to keep deferring probe after built-in drivers have had a chance
 287  * to probe. One scenario where that is useful is if built-in drivers rely on
 288  * resources that are provided by modular drivers.
 289  */
 290 int driver_deferred_probe_check_state_continue(struct device *dev)
 291 {
 292         int ret;
 293
 294         ret = __driver_deferred_probe_check_state(dev);
 295         if (ret < 0)
 296                 return ret;
 297
 298         return -EPROBE_DEFER;
 299 }
 300
 301 static void deferred_probe_timeout_work_func(struct work_struct *work)
 302 {
 303         struct device_private *p;
 304
 305         deferred_probe_timeout = 0;
 306         driver_deferred_probe_trigger();
 307         flush_work(&deferred_probe_work);
 308
 309         mutex_lock(&deferred_probe_mutex);
 310         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 311                 dev_info(p->device, "deferred probe pending\n");
 312         mutex_unlock(&deferred_probe_mutex);
 313 }
 314 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 315
 316 /**
 317  * deferred_probe_initcall() - Enable probing of deferred devices
 318  *
 319  * We don't want to get in the way when the bulk of drivers are getting probed.
 320  * Instead, this initcall makes sure that deferred probing is delayed until
 321  * late_initcall time.
 322  */
 323 static int deferred_probe_initcall(void)
 324 {
 325         deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
 326                                                NULL, &deferred_devs_fops);
 327
 328         driver_deferred_probe_enable = true;
 329         driver_deferred_probe_trigger();
 330         /* Sort as many dependencies as possible before exiting initcalls */
 331         flush_work(&deferred_probe_work);
 332         initcalls_done = true;
 333
 334         /*
 335          * Trigger deferred probe again, this time we won't defer anything
 336          * that is optional
 337          */
 338         driver_deferred_probe_trigger();
 339         flush_work(&deferred_probe_work);
 340
 341         if (deferred_probe_timeout > 0) {
 342                 schedule_delayed_work(&deferred_probe_timeout_work,
 343                         deferred_probe_timeout * HZ);
 344         }
 345         return 0;
 346 }
 347 late_initcall(deferred_probe_initcall);
 348
 349 static void __exit deferred_probe_exit(void)
 350 {
 351         debugfs_remove_recursive(deferred_devices);
 352 }
 353 __exitcall(deferred_probe_exit);
 354
 355 /**
 356  * device_is_bound() - Check if device is bound to a driver
 357  * @dev: device to check
 358  *
 359  * Returns true if passed device has already finished probing successfully
 360  * against a driver.
 361  *
 362  * This function must be called with the device lock held.
 363  */
 364 bool device_is_bound(struct device *dev)
 365 {
 366         return dev->p && klist_node_attached(&dev->p->knode_driver);
 367 }
 368
 369 static void driver_bound(struct device *dev)
 370 {
 371         if (device_is_bound(dev)) {
 372                 printk(KERN_WARNING "%s: device %s already bound\n",
 373                         __func__, kobject_name(&dev->kobj));
 374                 return;
 375         }
 376
 377         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 378                  __func__, dev_name(dev));
 379
 380         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 381         device_links_driver_bound(dev);
 382
 383         device_pm_check_callbacks(dev);
 384
 385         /*
 386          * Make sure the device is no longer in one of the deferred lists and
 387          * kick off retrying all pending devices
 388          */
 389         driver_deferred_probe_del(dev);
 390         driver_deferred_probe_trigger();
 391
 392         if (dev->bus)
 393                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 394                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 395
 396         kobject_uevent(&dev->kobj, KOBJ_BIND);
 397 }
 398
 399 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 400                             const char *buf, size_t count)
 401 {
 402         device_lock(dev);
 403         dev->driver->coredump(dev);
 404         device_unlock(dev);
 405
 406         return count;
 407 }
 408 static DEVICE_ATTR_WO(coredump);
 409
 410 static int driver_sysfs_add(struct device *dev)
 411 {
 412         int ret;
 413
 414         if (dev->bus)
 415                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 416                                              BUS_NOTIFY_BIND_DRIVER, dev);
 417
 418         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 419                                 kobject_name(&dev->kobj));
 420         if (ret)
 421                 goto fail;
 422
 423         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 424                                 "driver");
 425         if (ret)
 426                 goto rm_dev;
 427
 428         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
 429             !device_create_file(dev, &dev_attr_coredump))
 430                 return 0;
 431
 432         sysfs_remove_link(&dev->kobj, "driver");
 433
 434 rm_dev:
 435         sysfs_remove_link(&dev->driver->p->kobj,
 436                           kobject_name(&dev->kobj));
 437
 438 fail:
 439         return ret;
 440 }
 441
 442 static void driver_sysfs_remove(struct device *dev)
 443 {
 444         struct device_driver *drv = dev->driver;
 445
 446         if (drv) {
 447                 if (drv->coredump)
 448                         device_remove_file(dev, &dev_attr_coredump);
 449                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 450                 sysfs_remove_link(&dev->kobj, "driver");
 451         }
 452 }
 453
 454 /**
 455  * device_bind_driver - bind a driver to one device.
 456  * @dev: device.
 457  *
 458  * Allow manual attachment of a driver to a device.
 459  * Caller must have already set @dev->driver.
 460  *
 461  * Note that this does not modify the bus reference count
 462  * nor take the bus's rwsem. Please verify those are accounted
 463  * for before calling this. (It is ok to call with no other effort
 464  * from a driver's probe() method.)
 465  *
 466  * This function must be called with the device lock held.
 467  */
 468 int device_bind_driver(struct device *dev)
 469 {
 470         int ret;
 471
 472         ret = driver_sysfs_add(dev);
 473         if (!ret)
 474                 driver_bound(dev);
 475         else if (dev->bus)
 476                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 477                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 478         return ret;
 479 }
 480 EXPORT_SYMBOL_GPL(device_bind_driver);
 481
 482 static atomic_t probe_count = ATOMIC_INIT(0);
 483 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 484
 485 static void driver_deferred_probe_add_trigger(struct device *dev,
 486                                               int local_trigger_count)
 487 {
 488         driver_deferred_probe_add(dev);
 489         /* Did a trigger occur while probing? Need to re-trigger if yes */
 490         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 491                 driver_deferred_probe_trigger();
 492 }
 493
 494 static int really_probe(struct device *dev, struct device_driver *drv)
 495 {
 496         int ret = -EPROBE_DEFER;
 497         int local_trigger_count = atomic_read(&deferred_trigger_count);
 498         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 499                            !drv->suppress_bind_attrs;
 500
 501         if (defer_all_probes) {
 502                 /*
 503                  * Value of defer_all_probes can be set only by
 504                  * device_block_probing() which, in turn, will call
 505                  * wait_for_device_probe() right after that to avoid any races.
 506                  */
 507                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 508                 driver_deferred_probe_add(dev);
 509                 return ret;
 510         }
 511
 512         ret = device_links_check_suppliers(dev);
 513         if (ret == -EPROBE_DEFER)
 514                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 515         if (ret)
 516                 return ret;
 517
 518         atomic_inc(&probe_count);
 519         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 520                  drv->bus->name, __func__, drv->name, dev_name(dev));
 521         if (!list_empty(&dev->devres_head)) {
 522                 dev_crit(dev, "Resources present before probing\n");
 523                 ret = -EBUSY;
 524                 goto done;
 525         }
 526
 527 re_probe:
 528         dev->driver = drv;
 529
 530         /* If using pinctrl, bind pins now before probing */
 531         ret = pinctrl_bind_pins(dev);
 532         if (ret)
 533                 goto pinctrl_bind_failed;
 534
 535         if (dev->bus->dma_configure) {
 536                 ret = dev->bus->dma_configure(dev);
 537                 if (ret)
 538                         goto probe_failed;
 539         }
 540
 541         if (driver_sysfs_add(dev)) {
 542                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 543                         __func__, dev_name(dev));
 544                 goto probe_failed;
 545         }
 546
 547         if (dev->pm_domain && dev->pm_domain->activate) {
 548                 ret = dev->pm_domain->activate(dev);
 549                 if (ret)
 550                         goto probe_failed;
 551         }
 552
 553         if (dev->bus->probe) {
 554                 ret = dev->bus->probe(dev);
 555                 if (ret)
 556                         goto probe_failed;
 557         } else if (drv->probe) {
 558                 ret = drv->probe(dev);
 559                 if (ret)
 560                         goto probe_failed;
 561         }
 562
 563         if (device_add_groups(dev, drv->dev_groups)) {
 564                 dev_err(dev, "device_add_groups() failed\n");
 565                 goto dev_groups_failed;
 566         }
 567
 568         if (test_remove) {
 569                 test_remove = false;
 570
 571                 device_remove_groups(dev, drv->dev_groups);
 572
 573                 if (dev->bus->remove)
 574                         dev->bus->remove(dev);
 575                 else if (drv->remove)
 576                         drv->remove(dev);
 577
 578                 devres_release_all(dev);
 579                 driver_sysfs_remove(dev);
 580                 dev->driver = NULL;
 581                 dev_set_drvdata(dev, NULL);
 582                 if (dev->pm_domain && dev->pm_domain->dismiss)
 583                         dev->pm_domain->dismiss(dev);
 584                 pm_runtime_reinit(dev);
 585
 586                 goto re_probe;
 587         }
 588
 589         pinctrl_init_done(dev);
 590
 591         if (dev->pm_domain && dev->pm_domain->sync)
 592                 dev->pm_domain->sync(dev);
 593
 594         driver_bound(dev);
 595         ret = 1;
 596         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 597                  drv->bus->name, __func__, dev_name(dev), drv->name);
 598         goto done;
 599
 600 dev_groups_failed:
 601         if (dev->bus->remove)
 602                 dev->bus->remove(dev);
 603         else if (drv->remove)
 604                 drv->remove(dev);
 605 probe_failed:
 606         if (dev->bus)
 607                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 608                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 609 pinctrl_bind_failed:
 610         device_links_no_driver(dev);
 611         devres_release_all(dev);
 612         arch_teardown_dma_ops(dev);
 613         driver_sysfs_remove(dev);
 614         dev->driver = NULL;
 615         dev_set_drvdata(dev, NULL);
 616         if (dev->pm_domain && dev->pm_domain->dismiss)
 617                 dev->pm_domain->dismiss(dev);
 618         pm_runtime_reinit(dev);
 619         dev_pm_set_driver_flags(dev, 0);
 620
 621         switch (ret) {
 622         case -EPROBE_DEFER:
 623                 /* Driver requested deferred probing */
 624                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 625                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 626                 break;
 627         case -ENODEV:
 628         case -ENXIO:
 629                 pr_debug("%s: probe of %s rejects match %d\n",
 630                          drv->name, dev_name(dev), ret);
 631                 break;
 632         default:
 633                 /* driver matched but the probe failed */
 634                 printk(KERN_WARNING
 635                        "%s: probe of %s failed with error %d\n",
 636                        drv->name, dev_name(dev), ret);
 637         }
 638         /*
 639          * Ignore errors returned by ->probe so that the next driver can try
 640          * its luck.
 641          */
 642         ret = 0;
 643 done:
 644         atomic_dec(&probe_count);
 645         wake_up_all(&probe_waitqueue);
 646         return ret;
 647 }
 648
 649 /*
 650  * For initcall_debug, show the driver probe time.
 651  */
 652 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 653 {
 654         ktime_t calltime, delta, rettime;
 655         int ret;
 656
 657         calltime = ktime_get();
 658         ret = really_probe(dev, drv);
 659         rettime = ktime_get();
 660         delta = ktime_sub(rettime, calltime);
 661         printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
 662                dev_name(dev), ret, (s64) ktime_to_us(delta));
 663         return ret;
 664 }
 665
 666 /**
 667  * driver_probe_done
 668  * Determine if the probe sequence is finished or not.
 669  *
 670  * Should somehow figure out how to use a semaphore, not an atomic variable...
 671  */
 672 int driver_probe_done(void)
 673 {
 674         pr_debug("%s: probe_count = %d\n", __func__,
 675                  atomic_read(&probe_count));
 676         if (atomic_read(&probe_count))
 677                 return -EBUSY;
 678         return 0;
 679 }
 680
 681 /**
 682  * wait_for_device_probe
 683  * Wait for device probing to be completed.
 684  */
 685 void wait_for_device_probe(void)
 686 {
 687         /* wait for the deferred probe workqueue to finish */
 688         flush_work(&deferred_probe_work);
 689
 690         /* wait for the known devices to complete their probing */
 691         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 692         async_synchronize_full();
 693 }
 694 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 695
 696 /**
 697  * driver_probe_device - attempt to bind device & driver together
 698  * @drv: driver to bind a device to
 699  * @dev: device to try to bind to the driver
 700  *
 701  * This function returns -ENODEV if the device is not registered,
 702  * 1 if the device is bound successfully and 0 otherwise.
 703  *
 704  * This function must be called with @dev lock held.  When called for a
 705  * USB interface, @dev->parent lock must be held as well.
 706  *
 707  * If the device has a parent, runtime-resume the parent before driver probing.
 708  */
 709 int driver_probe_device(struct device_driver *drv, struct device *dev)
 710 {
 711         int ret = 0;
 712
 713         if (!device_is_registered(dev))
 714                 return -ENODEV;
 715
 716         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 717                  drv->bus->name, __func__, dev_name(dev), drv->name);
 718
 719         pm_runtime_get_suppliers(dev);
 720         if (dev->parent)
 721                 pm_runtime_get_sync(dev->parent);
 722
 723         pm_runtime_barrier(dev);
 724         if (initcall_debug)
 725                 ret = really_probe_debug(dev, drv);
 726         else
 727                 ret = really_probe(dev, drv);
 728         pm_request_idle(dev);
 729
 730         if (dev->parent)
 731                 pm_runtime_put(dev->parent);
 732
 733         pm_runtime_put_suppliers(dev);
 734         return ret;
 735 }
 736
 737 static inline bool cmdline_requested_async_probing(const char *drv_name)
 738 {
 739         return parse_option_str(async_probe_drv_names, drv_name);
 740 }
 741
 742 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 743 static int __init save_async_options(char *buf)
 744 {
 745         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 746                 printk(KERN_WARNING
 747                         "Too long list of driver names for 'driver_async_probe'!\n");
 748
 749         strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 750         return 1;
 751 }
 752 __setup("driver_async_probe=", save_async_options);
 753
 754 bool driver_allows_async_probing(struct device_driver *drv)
 755 {
 756         switch (drv->probe_type) {
 757         case PROBE_PREFER_ASYNCHRONOUS:
 758                 return true;
 759
 760         case PROBE_FORCE_SYNCHRONOUS:
 761                 return false;
 762
 763         default:
 764                 if (cmdline_requested_async_probing(drv->name))
 765                         return true;
 766
 767                 if (module_requested_async_probing(drv->owner))
 768                         return true;
 769
 770                 return false;
 771         }
 772 }
 773
 774 struct device_attach_data {
 775         struct device *dev;
 776
 777         /*
 778          * Indicates whether we are are considering asynchronous probing or
 779          * not. Only initial binding after device or driver registration
 780          * (including deferral processing) may be done asynchronously, the
 781          * rest is always synchronous, as we expect it is being done by
 782          * request from userspace.
 783          */
 784         bool check_async;
 785
 786         /*
 787          * Indicates if we are binding synchronous or asynchronous drivers.
 788          * When asynchronous probing is enabled we'll execute 2 passes
 789          * over drivers: first pass doing synchronous probing and second
 790          * doing asynchronous probing (if synchronous did not succeed -
 791          * most likely because there was no driver requiring synchronous
 792          * probing - and we found asynchronous driver during first pass).
 793          * The 2 passes are done because we can't shoot asynchronous
 794          * probe for given device and driver from bus_for_each_drv() since
 795          * driver pointer is not guaranteed to stay valid once
 796          * bus_for_each_drv() iterates to the next driver on the bus.
 797          */
 798         bool want_async;
 799
 800         /*
 801          * We'll set have_async to 'true' if, while scanning for matching
 802          * driver, we'll encounter one that requests asynchronous probing.
 803          */
 804         bool have_async;
 805 };
 806
 807 static int __device_attach_driver(struct device_driver *drv, void *_data)
 808 {
 809         struct device_attach_data *data = _data;
 810         struct device *dev = data->dev;
 811         bool async_allowed;
 812         int ret;
 813
 814         ret = driver_match_device(drv, dev);
 815         if (ret == 0) {
 816                 /* no match */
 817                 return 0;
 818         } else if (ret == -EPROBE_DEFER) {
 819                 dev_dbg(dev, "Device match requests probe deferral\n");
 820                 driver_deferred_probe_add(dev);
 821                 /*
 822                  * Device can't match with a driver right now, so don't attempt
 823                  * to match or bind with other drivers on the bus.
 824                  */
 825                 return ret;
 826         } else if (ret < 0) {
 827                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 828                 return ret;
 829         } /* ret > 0 means positive match */
 830
 831         async_allowed = driver_allows_async_probing(drv);
 832
 833         if (async_allowed)
 834                 data->have_async = true;
 835
 836         if (data->check_async && async_allowed != data->want_async)
 837                 return 0;
 838
 839         return driver_probe_device(drv, dev);
 840 }
 841
 842 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 843 {
 844         struct device *dev = _dev;
 845         struct device_attach_data data = {
 846                 .dev            = dev,
 847                 .check_async    = true,
 848                 .want_async     = true,
 849         };
 850
 851         device_lock(dev);
 852
 853         /*
 854          * Check if device has already been removed or claimed. This may
 855          * happen with driver loading, device discovery/registration,
 856          * and deferred probe processing happens all at once with
 857          * multiple threads.
 858          */
 859         if (dev->p->dead || dev->driver)
 860                 goto out_unlock;
 861
 862         if (dev->parent)
 863                 pm_runtime_get_sync(dev->parent);
 864
 865         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 866         dev_dbg(dev, "async probe completed\n");
 867
 868         pm_request_idle(dev);
 869
 870         if (dev->parent)
 871                 pm_runtime_put(dev->parent);
 872 out_unlock:
 873         device_unlock(dev);
 874
 875         put_device(dev);
 876 }
 877
 878 static int __device_attach(struct device *dev, bool allow_async)
 879 {
 880         int ret = 0;
 881         bool async = false;
 882
 883         device_lock(dev);
 884         if (dev->p->dead) {
 885                 goto out_unlock;
 886         } else if (dev->driver) {
 887                 if (device_is_bound(dev)) {
 888                         ret = 1;
 889                         goto out_unlock;
 890                 }
 891                 ret = device_bind_driver(dev);
 892                 if (ret == 0)
 893                         ret = 1;
 894                 else {
 895                         dev->driver = NULL;
 896                         ret = 0;
 897                 }
 898         } else {
 899                 struct device_attach_data data = {
 900                         .dev = dev,
 901                         .check_async = allow_async,
 902                         .want_async = false,
 903                 };
 904
 905                 if (dev->parent)
 906                         pm_runtime_get_sync(dev->parent);
 907
 908                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 909                                         __device_attach_driver);
 910                 if (!ret && allow_async && data.have_async) {
 911                         /*
 912                          * If we could not find appropriate driver
 913                          * synchronously and we are allowed to do
 914                          * async probes and there are drivers that
 915                          * want to probe asynchronously, we'll
 916                          * try them.
 917                          */
 918                         dev_dbg(dev, "scheduling asynchronous probe\n");
 919                         get_device(dev);
 920                         async = true;
 921                 } else {
 922                         pm_request_idle(dev);
 923                 }
 924
 925                 if (dev->parent)
 926                         pm_runtime_put(dev->parent);
 927         }
 928 out_unlock:
 929         device_unlock(dev);
 930         if (async)
 931                 async_schedule_dev(__device_attach_async_helper, dev);
 932         return ret;
 933 }
 934
 935 /**
 936  * device_attach - try to attach device to a driver.
 937  * @dev: device.
 938  *
 939  * Walk the list of drivers that the bus has and call
 940  * driver_probe_device() for each pair. If a compatible
 941  * pair is found, break out and return.
 942  *
 943  * Returns 1 if the device was bound to a driver;
 944  * 0 if no matching driver was found;
 945  * -ENODEV if the device is not registered.
 946  *
 947  * When called for a USB interface, @dev->parent lock must be held.
 948  */
 949 int device_attach(struct device *dev)
 950 {
 951         return __device_attach(dev, false);
 952 }
 953 EXPORT_SYMBOL_GPL(device_attach);
 954
 955 void device_initial_probe(struct device *dev)
 956 {
 957         __device_attach(dev, true);
 958 }
 959
 960 /*
 961  * __device_driver_lock - acquire locks needed to manipulate dev->drv
 962  * @dev: Device we will update driver info for
 963  * @parent: Parent device. Needed if the bus requires parent lock
 964  *
 965  * This function will take the required locks for manipulating dev->drv.
 966  * Normally this will just be the @dev lock, but when called for a USB
 967  * interface, @parent lock will be held as well.
 968  */
 969 static void __device_driver_lock(struct device *dev, struct device *parent)
 970 {
 971         if (parent && dev->bus->need_parent_lock)
 972                 device_lock(parent);
 973         device_lock(dev);
 974 }
 975
 976 /*
 977  * __device_driver_unlock - release locks needed to manipulate dev->drv
 978  * @dev: Device we will update driver info for
 979  * @parent: Parent device. Needed if the bus requires parent lock
 980  *
 981  * This function will release the required locks for manipulating dev->drv.
 982  * Normally this will just be the the @dev lock, but when called for a
 983  * USB interface, @parent lock will be released as well.
 984  */
 985 static void __device_driver_unlock(struct device *dev, struct device *parent)
 986 {
 987         device_unlock(dev);
 988         if (parent && dev->bus->need_parent_lock)
 989                 device_unlock(parent);
 990 }
 991
 992 /**
 993  * device_driver_attach - attach a specific driver to a specific device
 994  * @drv: Driver to attach
 995  * @dev: Device to attach it to
 996  *
 997  * Manually attach driver to a device. Will acquire both @dev lock and
 998  * @dev->parent lock if needed.
 999  */
1000 int device_driver_attach(struct device_driver *drv, struct device *dev)
1001 {
1002         int ret = 0;
1003
1004         __device_driver_lock(dev, dev->parent);
1005
1006         /*
1007          * If device has been removed or someone has already successfully
1008          * bound a driver before us just skip the driver probe call.
1009          */
1010         if (!dev->p->dead && !dev->driver)
1011                 ret = driver_probe_device(drv, dev);
1012
1013         __device_driver_unlock(dev, dev->parent);
1014
1015         return ret;
1016 }
1017
1018 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1019 {
1020         struct device *dev = _dev;
1021         struct device_driver *drv;
1022         int ret = 0;
1023
1024         __device_driver_lock(dev, dev->parent);
1025
1026         drv = dev->p->async_driver;
1027
1028         /*
1029          * If device has been removed or someone has already successfully
1030          * bound a driver before us just skip the driver probe call.
1031          */
1032         if (!dev->p->dead && !dev->driver)
1033                 ret = driver_probe_device(drv, dev);
1034
1035         __device_driver_unlock(dev, dev->parent);
1036
1037         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1038
1039         put_device(dev);
1040 }
1041
1042 static int __driver_attach(struct device *dev, void *data)
1043 {
1044         struct device_driver *drv = data;
1045         bool async = false;
1046         int ret;
1047
1048         /*
1049          * Lock device and try to bind to it. We drop the error
1050          * here and always return 0, because we need to keep trying
1051          * to bind to devices and some drivers will return an error
1052          * simply if it didn't support the device.
1053          *
1054          * driver_probe_device() will spit a warning if there
1055          * is an error.
1056          */
1057
1058         ret = driver_match_device(drv, dev);
1059         if (ret == 0) {
1060                 /* no match */
1061                 return 0;
1062         } else if (ret == -EPROBE_DEFER) {
1063                 dev_dbg(dev, "Device match requests probe deferral\n");
1064                 driver_deferred_probe_add(dev);
1065                 /*
1066                  * Driver could not match with device, but may match with
1067                  * another device on the bus.
1068                  */
1069                 return 0;
1070         } else if (ret < 0) {
1071                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1072                 /*
1073                  * Driver could not match with device, but may match with
1074                  * another device on the bus.
1075                  */
1076                 return 0;
1077         } /* ret > 0 means positive match */
1078
1079         if (driver_allows_async_probing(drv)) {
1080                 /*
1081                  * Instead of probing the device synchronously we will
1082                  * probe it asynchronously to allow for more parallelism.
1083                  *
1084                  * We only take the device lock here in order to guarantee
1085                  * that the dev->driver and async_driver fields are protected
1086                  */
1087                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1088                 device_lock(dev);
1089                 if (!dev->driver) {
1090                         get_device(dev);
1091                         dev->p->async_driver = drv;
1092                         async = true;
1093                 }
1094                 device_unlock(dev);
1095                 if (async)
1096                         async_schedule_dev(__driver_attach_async_helper, dev);
1097                 return 0;
1098         }
1099
1100         device_driver_attach(drv, dev);
1101
1102         return 0;
1103 }
1104
1105 /**
1106  * driver_attach - try to bind driver to devices.
1107  * @drv: driver.
1108  *
1109  * Walk the list of devices that the bus has on it and try to
1110  * match the driver with each one.  If driver_probe_device()
1111  * returns 0 and the @dev->driver is set, we've found a
1112  * compatible pair.
1113  */
1114 int driver_attach(struct device_driver *drv)
1115 {
1116         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1117 }
1118 EXPORT_SYMBOL_GPL(driver_attach);
1119
1120 /*
1121  * __device_release_driver() must be called with @dev lock held.
1122  * When called for a USB interface, @dev->parent lock must be held as well.
1123  */
1124 static void __device_release_driver(struct device *dev, struct device *parent)
1125 {
1126         struct device_driver *drv;
1127
1128         drv = dev->driver;
1129         if (drv) {
1130                 pm_runtime_get_sync(dev);
1131
1132                 while (device_links_busy(dev)) {
1133                         __device_driver_unlock(dev, parent);
1134
1135                         device_links_unbind_consumers(dev);
1136
1137                         __device_driver_lock(dev, parent);
1138                         /*
1139                          * A concurrent invocation of the same function might
1140                          * have released the driver successfully while this one
1141                          * was waiting, so check for that.
1142                          */
1143                         if (dev->driver != drv) {
1144                                 pm_runtime_put(dev);
1145                                 return;
1146                         }
1147                 }
1148
1149                 driver_sysfs_remove(dev);
1150
1151                 if (dev->bus)
1152                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1153                                                      BUS_NOTIFY_UNBIND_DRIVER,
1154                                                      dev);
1155
1156                 pm_runtime_put_sync(dev);
1157
1158                 device_remove_groups(dev, drv->dev_groups);
1159
1160                 if (dev->bus && dev->bus->remove)
1161                         dev->bus->remove(dev);
1162                 else if (drv->remove)
1163                         drv->remove(dev);
1164
1165                 device_links_driver_cleanup(dev);
1166
1167                 devres_release_all(dev);
1168                 arch_teardown_dma_ops(dev);
1169                 dev->driver = NULL;
1170                 dev_set_drvdata(dev, NULL);
1171                 if (dev->pm_domain && dev->pm_domain->dismiss)
1172                         dev->pm_domain->dismiss(dev);
1173                 pm_runtime_reinit(dev);
1174                 dev_pm_set_driver_flags(dev, 0);
1175
1176                 klist_remove(&dev->p->knode_driver);
1177                 device_pm_check_callbacks(dev);
1178                 if (dev->bus)
1179                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1180                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1181                                                      dev);
1182
1183                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1184         }
1185 }
1186
1187 void device_release_driver_internal(struct device *dev,
1188                                     struct device_driver *drv,
1189                                     struct device *parent)
1190 {
1191         __device_driver_lock(dev, parent);
1192
1193         if (!drv || drv == dev->driver)
1194                 __device_release_driver(dev, parent);
1195
1196         __device_driver_unlock(dev, parent);
1197 }
1198
1199 /**
1200  * device_release_driver - manually detach device from driver.
1201  * @dev: device.
1202  *
1203  * Manually detach device from driver.
1204  * When called for a USB interface, @dev->parent lock must be held.
1205  *
1206  * If this function is to be called with @dev->parent lock held, ensure that
1207  * the device's consumers are unbound in advance or that their locks can be
1208  * acquired under the @dev->parent lock.
1209  */
1210 void device_release_driver(struct device *dev)
1211 {
1212         /*
1213          * If anyone calls device_release_driver() recursively from
1214          * within their ->remove callback for the same device, they
1215          * will deadlock right here.
1216          */
1217         device_release_driver_internal(dev, NULL, NULL);
1218 }
1219 EXPORT_SYMBOL_GPL(device_release_driver);
1220
1221 /**
1222  * device_driver_detach - detach driver from a specific device
1223  * @dev: device to detach driver from
1224  *
1225  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1226  * lock if needed.
1227  */
1228 void device_driver_detach(struct device *dev)
1229 {
1230         device_release_driver_internal(dev, NULL, dev->parent);
1231 }
1232
1233 /**
1234  * driver_detach - detach driver from all devices it controls.
1235  * @drv: driver.
1236  */
1237 void driver_detach(struct device_driver *drv)
1238 {
1239         struct device_private *dev_prv;
1240         struct device *dev;
1241
1242         if (driver_allows_async_probing(drv))
1243                 async_synchronize_full();
1244
1245         for (;;) {
1246                 spin_lock(&drv->p->klist_devices.k_lock);
1247                 if (list_empty(&drv->p->klist_devices.k_list)) {
1248                         spin_unlock(&drv->p->klist_devices.k_lock);
1249                         break;
1250                 }
1251                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
1252                                      struct device_private,
1253                                      knode_driver.n_node);
1254                 dev = dev_prv->device;
1255                 get_device(dev);
1256                 spin_unlock(&drv->p->klist_devices.k_lock);
1257                 device_release_driver_internal(dev, drv, dev->parent);
1258                 put_device(dev);
1259         }
1260 }