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 struct dentry *deferred_devices;
  59 static bool initcalls_done;
  60
  61 /* Save the async probe drivers' name from kernel cmdline */
  62 #define ASYNC_DRV_NAMES_MAX_LEN 256
  63 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
  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 /*
  73  * deferred_probe_work_func() - Retry probing devices in the active list.
  74  */
  75 static void deferred_probe_work_func(struct work_struct *work)
  76 {
  77         struct device *dev;
  78         struct device_private *private;
  79         /*
  80          * This block processes every device in the deferred 'active' list.
  81          * Each device is removed from the active list and passed to
  82          * bus_probe_device() to re-attempt the probe.  The loop continues
  83          * until every device in the active list is removed and retried.
  84          *
  85          * Note: Once the device is removed from the list and the mutex is
  86          * released, it is possible for the device get freed by another thread
  87          * and cause a illegal pointer dereference.  This code uses
  88          * get/put_device() to ensure the device structure cannot disappear
  89          * from under our feet.
  90          */
  91         mutex_lock(&deferred_probe_mutex);
  92         while (!list_empty(&deferred_probe_active_list)) {
  93                 private = list_first_entry(&deferred_probe_active_list,
  94                                         typeof(*dev->p), deferred_probe);
  95                 dev = private->device;
  96                 list_del_init(&private->deferred_probe);
  97
  98                 get_device(dev);
  99
 100                 kfree(dev->p->deferred_probe_reason);
 101                 dev->p->deferred_probe_reason = NULL;
 102
 103                 /*
 104                  * Drop the mutex while probing each device; the probe path may
 105                  * manipulate the deferred list
 106                  */
 107                 mutex_unlock(&deferred_probe_mutex);
 108
 109                 /*
 110                  * Force the device to the end of the dpm_list since
 111                  * the PM code assumes that the order we add things to
 112                  * the list is a good order for suspend but deferred
 113                  * probe makes that very unsafe.
 114                  */
 115                 device_pm_move_to_tail(dev);
 116
 117                 dev_dbg(dev, "Retrying from deferred list\n");
 118                 bus_probe_device(dev);
 119                 mutex_lock(&deferred_probe_mutex);
 120
 121                 put_device(dev);
 122         }
 123         mutex_unlock(&deferred_probe_mutex);
 124 }
 125 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 126
 127 void driver_deferred_probe_add(struct device *dev)
 128 {
 129         mutex_lock(&deferred_probe_mutex);
 130         if (list_empty(&dev->p->deferred_probe)) {
 131                 dev_dbg(dev, "Added to deferred list\n");
 132                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 133         }
 134         mutex_unlock(&deferred_probe_mutex);
 135 }
 136
 137 void driver_deferred_probe_del(struct device *dev)
 138 {
 139         mutex_lock(&deferred_probe_mutex);
 140         if (!list_empty(&dev->p->deferred_probe)) {
 141                 dev_dbg(dev, "Removed from deferred list\n");
 142                 list_del_init(&dev->p->deferred_probe);
 143                 kfree(dev->p->deferred_probe_reason);
 144                 dev->p->deferred_probe_reason = NULL;
 145         }
 146         mutex_unlock(&deferred_probe_mutex);
 147 }
 148
 149 static bool driver_deferred_probe_enable = false;
 150 /**
 151  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 152  *
 153  * This functions moves all devices from the pending list to the active
 154  * list and schedules the deferred probe workqueue to process them.  It
 155  * should be called anytime a driver is successfully bound to a device.
 156  *
 157  * Note, there is a race condition in multi-threaded probe. In the case where
 158  * more than one device is probing at the same time, it is possible for one
 159  * probe to complete successfully while another is about to defer. If the second
 160  * depends on the first, then it will get put on the pending list after the
 161  * trigger event has already occurred and will be stuck there.
 162  *
 163  * The atomic 'deferred_trigger_count' is used to determine if a successful
 164  * trigger has occurred in the midst of probing a driver. If the trigger count
 165  * changes in the midst of a probe, then deferred processing should be triggered
 166  * again.
 167  */
 168 static void driver_deferred_probe_trigger(void)
 169 {
 170         if (!driver_deferred_probe_enable)
 171                 return;
 172
 173         /*
 174          * A successful probe means that all the devices in the pending list
 175          * should be triggered to be reprobed.  Move all the deferred devices
 176          * into the active list so they can be retried by the workqueue
 177          */
 178         mutex_lock(&deferred_probe_mutex);
 179         atomic_inc(&deferred_trigger_count);
 180         list_splice_tail_init(&deferred_probe_pending_list,
 181                               &deferred_probe_active_list);
 182         mutex_unlock(&deferred_probe_mutex);
 183
 184         /*
 185          * Kick the re-probe thread.  It may already be scheduled, but it is
 186          * safe to kick it again.
 187          */
 188         schedule_work(&deferred_probe_work);
 189 }
 190
 191 /**
 192  * device_block_probing() - Block/defer device's probes
 193  *
 194  *      It will disable probing of devices and defer their probes instead.
 195  */
 196 void device_block_probing(void)
 197 {
 198         defer_all_probes = true;
 199         /* sync with probes to avoid races. */
 200         wait_for_device_probe();
 201 }
 202
 203 /**
 204  * device_unblock_probing() - Unblock/enable device's probes
 205  *
 206  *      It will restore normal behavior and trigger re-probing of deferred
 207  * devices.
 208  */
 209 void device_unblock_probing(void)
 210 {
 211         defer_all_probes = false;
 212         driver_deferred_probe_trigger();
 213 }
 214
 215 /**
 216  * device_set_deferred_probe_reason() - Set defer probe reason message for device
 217  * @dev: the pointer to the struct device
 218  * @vaf: the pointer to va_format structure with message
 219  */
 220 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
 221 {
 222         const char *drv = dev_driver_string(dev);
 223
 224         mutex_lock(&deferred_probe_mutex);
 225
 226         kfree(dev->p->deferred_probe_reason);
 227         dev->p->deferred_probe_reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
 228
 229         mutex_unlock(&deferred_probe_mutex);
 230 }
 231
 232 /*
 233  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 234  */
 235 static int deferred_devs_show(struct seq_file *s, void *data)
 236 {
 237         struct device_private *curr;
 238
 239         mutex_lock(&deferred_probe_mutex);
 240
 241         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 242                 seq_printf(s, "%s\t%s", dev_name(curr->device),
 243                            curr->device->p->deferred_probe_reason ?: "\n");
 244
 245         mutex_unlock(&deferred_probe_mutex);
 246
 247         return 0;
 248 }
 249 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 250
 251 int driver_deferred_probe_timeout;
 252 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
 253
 254 static int __init deferred_probe_timeout_setup(char *str)
 255 {
 256         int timeout;
 257
 258         if (!kstrtoint(str, 10, &timeout))
 259                 driver_deferred_probe_timeout = timeout;
 260         return 1;
 261 }
 262 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 263
 264 /**
 265  * driver_deferred_probe_check_state() - Check deferred probe state
 266  * @dev: device to check
 267  *
 268  * Return:
 269  * -ENODEV if initcalls have completed and modules are disabled.
 270  * -ETIMEDOUT if the deferred probe timeout was set and has expired
 271  *  and modules are enabled.
 272  * -EPROBE_DEFER in other cases.
 273  *
 274  * Drivers or subsystems can opt-in to calling this function instead of directly
 275  * returning -EPROBE_DEFER.
 276  */
 277 int driver_deferred_probe_check_state(struct device *dev)
 278 {
 279         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 280                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 281                 return -ENODEV;
 282         }
 283
 284         if (!driver_deferred_probe_timeout && initcalls_done) {
 285                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 286                 return -ETIMEDOUT;
 287         }
 288
 289         return -EPROBE_DEFER;
 290 }
 291
 292 static void deferred_probe_timeout_work_func(struct work_struct *work)
 293 {
 294         struct device_private *p;
 295
 296         driver_deferred_probe_timeout = 0;
 297         driver_deferred_probe_trigger();
 298         flush_work(&deferred_probe_work);
 299
 300         mutex_lock(&deferred_probe_mutex);
 301         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 302                 dev_info(p->device, "deferred probe pending\n");
 303         mutex_unlock(&deferred_probe_mutex);
 304 }
 305 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 306
 307 /**
 308  * deferred_probe_initcall() - Enable probing of deferred devices
 309  *
 310  * We don't want to get in the way when the bulk of drivers are getting probed.
 311  * Instead, this initcall makes sure that deferred probing is delayed until
 312  * late_initcall time.
 313  */
 314 static int deferred_probe_initcall(void)
 315 {
 316         deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
 317                                                NULL, &deferred_devs_fops);
 318
 319         driver_deferred_probe_enable = true;
 320         driver_deferred_probe_trigger();
 321         /* Sort as many dependencies as possible before exiting initcalls */
 322         flush_work(&deferred_probe_work);
 323         initcalls_done = true;
 324
 325         /*
 326          * Trigger deferred probe again, this time we won't defer anything
 327          * that is optional
 328          */
 329         driver_deferred_probe_trigger();
 330         flush_work(&deferred_probe_work);
 331
 332         if (driver_deferred_probe_timeout > 0) {
 333                 schedule_delayed_work(&deferred_probe_timeout_work,
 334                         driver_deferred_probe_timeout * HZ);
 335         }
 336         return 0;
 337 }
 338 late_initcall(deferred_probe_initcall);
 339
 340 static void __exit deferred_probe_exit(void)
 341 {
 342         debugfs_remove_recursive(deferred_devices);
 343 }
 344 __exitcall(deferred_probe_exit);
 345
 346 /**
 347  * device_is_bound() - Check if device is bound to a driver
 348  * @dev: device to check
 349  *
 350  * Returns true if passed device has already finished probing successfully
 351  * against a driver.
 352  *
 353  * This function must be called with the device lock held.
 354  */
 355 bool device_is_bound(struct device *dev)
 356 {
 357         return dev->p && klist_node_attached(&dev->p->knode_driver);
 358 }
 359
 360 static void driver_bound(struct device *dev)
 361 {
 362         if (device_is_bound(dev)) {
 363                 pr_warn("%s: device %s already bound\n",
 364                         __func__, kobject_name(&dev->kobj));
 365                 return;
 366         }
 367
 368         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 369                  __func__, dev_name(dev));
 370
 371         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 372         device_links_driver_bound(dev);
 373
 374         device_pm_check_callbacks(dev);
 375
 376         /*
 377          * Make sure the device is no longer in one of the deferred lists and
 378          * kick off retrying all pending devices
 379          */
 380         driver_deferred_probe_del(dev);
 381         driver_deferred_probe_trigger();
 382
 383         if (dev->bus)
 384                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 385                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 386
 387         kobject_uevent(&dev->kobj, KOBJ_BIND);
 388 }
 389
 390 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 391                             const char *buf, size_t count)
 392 {
 393         device_lock(dev);
 394         dev->driver->coredump(dev);
 395         device_unlock(dev);
 396
 397         return count;
 398 }
 399 static DEVICE_ATTR_WO(coredump);
 400
 401 static int driver_sysfs_add(struct device *dev)
 402 {
 403         int ret;
 404
 405         if (dev->bus)
 406                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 407                                              BUS_NOTIFY_BIND_DRIVER, dev);
 408
 409         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 410                                 kobject_name(&dev->kobj));
 411         if (ret)
 412                 goto fail;
 413
 414         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 415                                 "driver");
 416         if (ret)
 417                 goto rm_dev;
 418
 419         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
 420             !device_create_file(dev, &dev_attr_coredump))
 421                 return 0;
 422
 423         sysfs_remove_link(&dev->kobj, "driver");
 424
 425 rm_dev:
 426         sysfs_remove_link(&dev->driver->p->kobj,
 427                           kobject_name(&dev->kobj));
 428
 429 fail:
 430         return ret;
 431 }
 432
 433 static void driver_sysfs_remove(struct device *dev)
 434 {
 435         struct device_driver *drv = dev->driver;
 436
 437         if (drv) {
 438                 if (drv->coredump)
 439                         device_remove_file(dev, &dev_attr_coredump);
 440                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 441                 sysfs_remove_link(&dev->kobj, "driver");
 442         }
 443 }
 444
 445 /**
 446  * device_bind_driver - bind a driver to one device.
 447  * @dev: device.
 448  *
 449  * Allow manual attachment of a driver to a device.
 450  * Caller must have already set @dev->driver.
 451  *
 452  * Note that this does not modify the bus reference count.
 453  * Please verify that is accounted for before calling this.
 454  * (It is ok to call with no other effort from a driver's probe() method.)
 455  *
 456  * This function must be called with the device lock held.
 457  */
 458 int device_bind_driver(struct device *dev)
 459 {
 460         int ret;
 461
 462         ret = driver_sysfs_add(dev);
 463         if (!ret)
 464                 driver_bound(dev);
 465         else if (dev->bus)
 466                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 467                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 468         return ret;
 469 }
 470 EXPORT_SYMBOL_GPL(device_bind_driver);
 471
 472 static atomic_t probe_count = ATOMIC_INIT(0);
 473 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 474
 475 static void driver_deferred_probe_add_trigger(struct device *dev,
 476                                               int local_trigger_count)
 477 {
 478         driver_deferred_probe_add(dev);
 479         /* Did a trigger occur while probing? Need to re-trigger if yes */
 480         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 481                 driver_deferred_probe_trigger();
 482 }
 483
 484 static ssize_t state_synced_show(struct device *dev,
 485                                  struct device_attribute *attr, char *buf)
 486 {
 487         bool val;
 488
 489         device_lock(dev);
 490         val = dev->state_synced;
 491         device_unlock(dev);
 492
 493         return sysfs_emit(buf, "%u\n", val);
 494 }
 495 static DEVICE_ATTR_RO(state_synced);
 496
 497 static int really_probe(struct device *dev, struct device_driver *drv)
 498 {
 499         int ret = -EPROBE_DEFER;
 500         int local_trigger_count = atomic_read(&deferred_trigger_count);
 501         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 502                            !drv->suppress_bind_attrs;
 503
 504         if (defer_all_probes) {
 505                 /*
 506                  * Value of defer_all_probes can be set only by
 507                  * device_block_probing() which, in turn, will call
 508                  * wait_for_device_probe() right after that to avoid any races.
 509                  */
 510                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 511                 driver_deferred_probe_add(dev);
 512                 return ret;
 513         }
 514
 515         ret = device_links_check_suppliers(dev);
 516         if (ret == -EPROBE_DEFER)
 517                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 518         if (ret)
 519                 return ret;
 520
 521         atomic_inc(&probe_count);
 522         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 523                  drv->bus->name, __func__, drv->name, dev_name(dev));
 524         if (!list_empty(&dev->devres_head)) {
 525                 dev_crit(dev, "Resources present before probing\n");
 526                 ret = -EBUSY;
 527                 goto done;
 528         }
 529
 530 re_probe:
 531         dev->driver = drv;
 532
 533         /* If using pinctrl, bind pins now before probing */
 534         ret = pinctrl_bind_pins(dev);
 535         if (ret)
 536                 goto pinctrl_bind_failed;
 537
 538         if (dev->bus->dma_configure) {
 539                 ret = dev->bus->dma_configure(dev);
 540                 if (ret)
 541                         goto probe_failed;
 542         }
 543
 544         ret = driver_sysfs_add(dev);
 545         if (ret) {
 546                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 547                        __func__, dev_name(dev));
 548                 goto probe_failed;
 549         }
 550
 551         if (dev->pm_domain && dev->pm_domain->activate) {
 552                 ret = dev->pm_domain->activate(dev);
 553                 if (ret)
 554                         goto probe_failed;
 555         }
 556
 557         if (dev->bus->probe) {
 558                 ret = dev->bus->probe(dev);
 559                 if (ret)
 560                         goto probe_failed;
 561         } else if (drv->probe) {
 562                 ret = drv->probe(dev);
 563                 if (ret)
 564                         goto probe_failed;
 565         }
 566
 567         ret = device_add_groups(dev, drv->dev_groups);
 568         if (ret) {
 569                 dev_err(dev, "device_add_groups() failed\n");
 570                 goto dev_groups_failed;
 571         }
 572
 573         if (dev_has_sync_state(dev)) {
 574                 ret = device_create_file(dev, &dev_attr_state_synced);
 575                 if (ret) {
 576                         dev_err(dev, "state_synced sysfs add failed\n");
 577                         goto dev_sysfs_state_synced_failed;
 578                 }
 579         }
 580
 581         if (test_remove) {
 582                 test_remove = false;
 583
 584                 device_remove_file(dev, &dev_attr_state_synced);
 585                 device_remove_groups(dev, drv->dev_groups);
 586
 587                 if (dev->bus->remove)
 588                         dev->bus->remove(dev);
 589                 else if (drv->remove)
 590                         drv->remove(dev);
 591
 592                 devres_release_all(dev);
 593                 arch_teardown_dma_ops(dev);
 594                 kfree(dev->dma_range_map);
 595                 dev->dma_range_map = NULL;
 596                 driver_sysfs_remove(dev);
 597                 dev->driver = NULL;
 598                 dev_set_drvdata(dev, NULL);
 599                 if (dev->pm_domain && dev->pm_domain->dismiss)
 600                         dev->pm_domain->dismiss(dev);
 601                 pm_runtime_reinit(dev);
 602
 603                 goto re_probe;
 604         }
 605
 606         pinctrl_init_done(dev);
 607
 608         if (dev->pm_domain && dev->pm_domain->sync)
 609                 dev->pm_domain->sync(dev);
 610
 611         driver_bound(dev);
 612         ret = 1;
 613         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 614                  drv->bus->name, __func__, dev_name(dev), drv->name);
 615         goto done;
 616
 617 dev_sysfs_state_synced_failed:
 618         device_remove_groups(dev, drv->dev_groups);
 619 dev_groups_failed:
 620         if (dev->bus->remove)
 621                 dev->bus->remove(dev);
 622         else if (drv->remove)
 623                 drv->remove(dev);
 624 probe_failed:
 625         if (dev->bus)
 626                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 627                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 628 pinctrl_bind_failed:
 629         device_links_no_driver(dev);
 630         devres_release_all(dev);
 631         arch_teardown_dma_ops(dev);
 632         kfree(dev->dma_range_map);
 633         dev->dma_range_map = NULL;
 634         driver_sysfs_remove(dev);
 635         dev->driver = NULL;
 636         dev_set_drvdata(dev, NULL);
 637         if (dev->pm_domain && dev->pm_domain->dismiss)
 638                 dev->pm_domain->dismiss(dev);
 639         pm_runtime_reinit(dev);
 640         dev_pm_set_driver_flags(dev, 0);
 641
 642         switch (ret) {
 643         case -EPROBE_DEFER:
 644                 /* Driver requested deferred probing */
 645                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 646                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 647                 break;
 648         case -ENODEV:
 649         case -ENXIO:
 650                 pr_debug("%s: probe of %s rejects match %d\n",
 651                          drv->name, dev_name(dev), ret);
 652                 break;
 653         default:
 654                 /* driver matched but the probe failed */
 655                 pr_warn("%s: probe of %s failed with error %d\n",
 656                         drv->name, dev_name(dev), ret);
 657         }
 658         /*
 659          * Ignore errors returned by ->probe so that the next driver can try
 660          * its luck.
 661          */
 662         ret = 0;
 663 done:
 664         atomic_dec(&probe_count);
 665         wake_up_all(&probe_waitqueue);
 666         return ret;
 667 }
 668
 669 /*
 670  * For initcall_debug, show the driver probe time.
 671  */
 672 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 673 {
 674         ktime_t calltime, rettime;
 675         int ret;
 676
 677         calltime = ktime_get();
 678         ret = really_probe(dev, drv);
 679         rettime = ktime_get();
 680         pr_debug("probe of %s returned %d after %lld usecs\n",
 681                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 682         return ret;
 683 }
 684
 685 /**
 686  * driver_probe_done
 687  * Determine if the probe sequence is finished or not.
 688  *
 689  * Should somehow figure out how to use a semaphore, not an atomic variable...
 690  */
 691 int driver_probe_done(void)
 692 {
 693         int local_probe_count = atomic_read(&probe_count);
 694
 695         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 696         if (local_probe_count)
 697                 return -EBUSY;
 698         return 0;
 699 }
 700
 701 /**
 702  * wait_for_device_probe
 703  * Wait for device probing to be completed.
 704  */
 705 void wait_for_device_probe(void)
 706 {
 707         /* wait for the deferred probe workqueue to finish */
 708         flush_work(&deferred_probe_work);
 709
 710         /* wait for the known devices to complete their probing */
 711         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 712         async_synchronize_full();
 713 }
 714 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 715
 716 /**
 717  * driver_probe_device - attempt to bind device & driver together
 718  * @drv: driver to bind a device to
 719  * @dev: device to try to bind to the driver
 720  *
 721  * This function returns -ENODEV if the device is not registered,
 722  * 1 if the device is bound successfully and 0 otherwise.
 723  *
 724  * This function must be called with @dev lock held.  When called for a
 725  * USB interface, @dev->parent lock must be held as well.
 726  *
 727  * If the device has a parent, runtime-resume the parent before driver probing.
 728  */
 729 int driver_probe_device(struct device_driver *drv, struct device *dev)
 730 {
 731         int ret = 0;
 732
 733         if (!device_is_registered(dev))
 734                 return -ENODEV;
 735
 736         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 737                  drv->bus->name, __func__, dev_name(dev), drv->name);
 738
 739         pm_runtime_get_suppliers(dev);
 740         if (dev->parent)
 741                 pm_runtime_get_sync(dev->parent);
 742
 743         pm_runtime_barrier(dev);
 744         if (initcall_debug)
 745                 ret = really_probe_debug(dev, drv);
 746         else
 747                 ret = really_probe(dev, drv);
 748         pm_request_idle(dev);
 749
 750         if (dev->parent)
 751                 pm_runtime_put(dev->parent);
 752
 753         pm_runtime_put_suppliers(dev);
 754         return ret;
 755 }
 756
 757 static inline bool cmdline_requested_async_probing(const char *drv_name)
 758 {
 759         return parse_option_str(async_probe_drv_names, drv_name);
 760 }
 761
 762 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 763 static int __init save_async_options(char *buf)
 764 {
 765         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 766                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 767
 768         strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 769         return 1;
 770 }
 771 __setup("driver_async_probe=", save_async_options);
 772
 773 bool driver_allows_async_probing(struct device_driver *drv)
 774 {
 775         switch (drv->probe_type) {
 776         case PROBE_PREFER_ASYNCHRONOUS:
 777                 return true;
 778
 779         case PROBE_FORCE_SYNCHRONOUS:
 780                 return false;
 781
 782         default:
 783                 if (cmdline_requested_async_probing(drv->name))
 784                         return true;
 785
 786                 if (module_requested_async_probing(drv->owner))
 787                         return true;
 788
 789                 return false;
 790         }
 791 }
 792
 793 struct device_attach_data {
 794         struct device *dev;
 795
 796         /*
 797          * Indicates whether we are are considering asynchronous probing or
 798          * not. Only initial binding after device or driver registration
 799          * (including deferral processing) may be done asynchronously, the
 800          * rest is always synchronous, as we expect it is being done by
 801          * request from userspace.
 802          */
 803         bool check_async;
 804
 805         /*
 806          * Indicates if we are binding synchronous or asynchronous drivers.
 807          * When asynchronous probing is enabled we'll execute 2 passes
 808          * over drivers: first pass doing synchronous probing and second
 809          * doing asynchronous probing (if synchronous did not succeed -
 810          * most likely because there was no driver requiring synchronous
 811          * probing - and we found asynchronous driver during first pass).
 812          * The 2 passes are done because we can't shoot asynchronous
 813          * probe for given device and driver from bus_for_each_drv() since
 814          * driver pointer is not guaranteed to stay valid once
 815          * bus_for_each_drv() iterates to the next driver on the bus.
 816          */
 817         bool want_async;
 818
 819         /*
 820          * We'll set have_async to 'true' if, while scanning for matching
 821          * driver, we'll encounter one that requests asynchronous probing.
 822          */
 823         bool have_async;
 824 };
 825
 826 static int __device_attach_driver(struct device_driver *drv, void *_data)
 827 {
 828         struct device_attach_data *data = _data;
 829         struct device *dev = data->dev;
 830         bool async_allowed;
 831         int ret;
 832
 833         ret = driver_match_device(drv, dev);
 834         if (ret == 0) {
 835                 /* no match */
 836                 return 0;
 837         } else if (ret == -EPROBE_DEFER) {
 838                 dev_dbg(dev, "Device match requests probe deferral\n");
 839                 driver_deferred_probe_add(dev);
 840                 /*
 841                  * Device can't match with a driver right now, so don't attempt
 842                  * to match or bind with other drivers on the bus.
 843                  */
 844                 return ret;
 845         } else if (ret < 0) {
 846                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 847                 return ret;
 848         } /* ret > 0 means positive match */
 849
 850         async_allowed = driver_allows_async_probing(drv);
 851
 852         if (async_allowed)
 853                 data->have_async = true;
 854
 855         if (data->check_async && async_allowed != data->want_async)
 856                 return 0;
 857
 858         return driver_probe_device(drv, dev);
 859 }
 860
 861 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 862 {
 863         struct device *dev = _dev;
 864         struct device_attach_data data = {
 865                 .dev            = dev,
 866                 .check_async    = true,
 867                 .want_async     = true,
 868         };
 869
 870         device_lock(dev);
 871
 872         /*
 873          * Check if device has already been removed or claimed. This may
 874          * happen with driver loading, device discovery/registration,
 875          * and deferred probe processing happens all at once with
 876          * multiple threads.
 877          */
 878         if (dev->p->dead || dev->driver)
 879                 goto out_unlock;
 880
 881         if (dev->parent)
 882                 pm_runtime_get_sync(dev->parent);
 883
 884         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 885         dev_dbg(dev, "async probe completed\n");
 886
 887         pm_request_idle(dev);
 888
 889         if (dev->parent)
 890                 pm_runtime_put(dev->parent);
 891 out_unlock:
 892         device_unlock(dev);
 893
 894         put_device(dev);
 895 }
 896
 897 static int __device_attach(struct device *dev, bool allow_async)
 898 {
 899         int ret = 0;
 900         bool async = false;
 901
 902         device_lock(dev);
 903         if (dev->p->dead) {
 904                 goto out_unlock;
 905         } else if (dev->driver) {
 906                 if (device_is_bound(dev)) {
 907                         ret = 1;
 908                         goto out_unlock;
 909                 }
 910                 ret = device_bind_driver(dev);
 911                 if (ret == 0)
 912                         ret = 1;
 913                 else {
 914                         dev->driver = NULL;
 915                         ret = 0;
 916                 }
 917         } else {
 918                 struct device_attach_data data = {
 919                         .dev = dev,
 920                         .check_async = allow_async,
 921                         .want_async = false,
 922                 };
 923
 924                 if (dev->parent)
 925                         pm_runtime_get_sync(dev->parent);
 926
 927                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 928                                         __device_attach_driver);
 929                 if (!ret && allow_async && data.have_async) {
 930                         /*
 931                          * If we could not find appropriate driver
 932                          * synchronously and we are allowed to do
 933                          * async probes and there are drivers that
 934                          * want to probe asynchronously, we'll
 935                          * try them.
 936                          */
 937                         dev_dbg(dev, "scheduling asynchronous probe\n");
 938                         get_device(dev);
 939                         async = true;
 940                 } else {
 941                         pm_request_idle(dev);
 942                 }
 943
 944                 if (dev->parent)
 945                         pm_runtime_put(dev->parent);
 946         }
 947 out_unlock:
 948         device_unlock(dev);
 949         if (async)
 950                 async_schedule_dev(__device_attach_async_helper, dev);
 951         return ret;
 952 }
 953
 954 /**
 955  * device_attach - try to attach device to a driver.
 956  * @dev: device.
 957  *
 958  * Walk the list of drivers that the bus has and call
 959  * driver_probe_device() for each pair. If a compatible
 960  * pair is found, break out and return.
 961  *
 962  * Returns 1 if the device was bound to a driver;
 963  * 0 if no matching driver was found;
 964  * -ENODEV if the device is not registered.
 965  *
 966  * When called for a USB interface, @dev->parent lock must be held.
 967  */
 968 int device_attach(struct device *dev)
 969 {
 970         return __device_attach(dev, false);
 971 }
 972 EXPORT_SYMBOL_GPL(device_attach);
 973
 974 void device_initial_probe(struct device *dev)
 975 {
 976         __device_attach(dev, true);
 977 }
 978
 979 /*
 980  * __device_driver_lock - acquire locks needed to manipulate dev->drv
 981  * @dev: Device we will update driver info for
 982  * @parent: Parent device. Needed if the bus requires parent lock
 983  *
 984  * This function will take the required locks for manipulating dev->drv.
 985  * Normally this will just be the @dev lock, but when called for a USB
 986  * interface, @parent lock will be held as well.
 987  */
 988 static void __device_driver_lock(struct device *dev, struct device *parent)
 989 {
 990         if (parent && dev->bus->need_parent_lock)
 991                 device_lock(parent);
 992         device_lock(dev);
 993 }
 994
 995 /*
 996  * __device_driver_unlock - release locks needed to manipulate dev->drv
 997  * @dev: Device we will update driver info for
 998  * @parent: Parent device. Needed if the bus requires parent lock
 999  *
1000  * This function will release the required locks for manipulating dev->drv.
1001  * Normally this will just be the the @dev lock, but when called for a
1002  * USB interface, @parent lock will be released as well.
1003  */
1004 static void __device_driver_unlock(struct device *dev, struct device *parent)
1005 {
1006         device_unlock(dev);
1007         if (parent && dev->bus->need_parent_lock)
1008                 device_unlock(parent);
1009 }
1010
1011 /**
1012  * device_driver_attach - attach a specific driver to a specific device
1013  * @drv: Driver to attach
1014  * @dev: Device to attach it to
1015  *
1016  * Manually attach driver to a device. Will acquire both @dev lock and
1017  * @dev->parent lock if needed.
1018  */
1019 int device_driver_attach(struct device_driver *drv, struct device *dev)
1020 {
1021         int ret = 0;
1022
1023         __device_driver_lock(dev, dev->parent);
1024
1025         /*
1026          * If device has been removed or someone has already successfully
1027          * bound a driver before us just skip the driver probe call.
1028          */
1029         if (!dev->p->dead && !dev->driver)
1030                 ret = driver_probe_device(drv, dev);
1031
1032         __device_driver_unlock(dev, dev->parent);
1033
1034         return ret;
1035 }
1036
1037 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1038 {
1039         struct device *dev = _dev;
1040         struct device_driver *drv;
1041         int ret = 0;
1042
1043         __device_driver_lock(dev, dev->parent);
1044
1045         drv = dev->p->async_driver;
1046
1047         /*
1048          * If device has been removed or someone has already successfully
1049          * bound a driver before us just skip the driver probe call.
1050          */
1051         if (!dev->p->dead && !dev->driver)
1052                 ret = driver_probe_device(drv, dev);
1053
1054         __device_driver_unlock(dev, dev->parent);
1055
1056         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1057
1058         put_device(dev);
1059 }
1060
1061 static int __driver_attach(struct device *dev, void *data)
1062 {
1063         struct device_driver *drv = data;
1064         bool async = false;
1065         int ret;
1066
1067         /*
1068          * Lock device and try to bind to it. We drop the error
1069          * here and always return 0, because we need to keep trying
1070          * to bind to devices and some drivers will return an error
1071          * simply if it didn't support the device.
1072          *
1073          * driver_probe_device() will spit a warning if there
1074          * is an error.
1075          */
1076
1077         ret = driver_match_device(drv, dev);
1078         if (ret == 0) {
1079                 /* no match */
1080                 return 0;
1081         } else if (ret == -EPROBE_DEFER) {
1082                 dev_dbg(dev, "Device match requests probe deferral\n");
1083                 driver_deferred_probe_add(dev);
1084                 /*
1085                  * Driver could not match with device, but may match with
1086                  * another device on the bus.
1087                  */
1088                 return 0;
1089         } else if (ret < 0) {
1090                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1091                 return ret;
1092         } /* ret > 0 means positive match */
1093
1094         if (driver_allows_async_probing(drv)) {
1095                 /*
1096                  * Instead of probing the device synchronously we will
1097                  * probe it asynchronously to allow for more parallelism.
1098                  *
1099                  * We only take the device lock here in order to guarantee
1100                  * that the dev->driver and async_driver fields are protected
1101                  */
1102                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1103                 device_lock(dev);
1104                 if (!dev->driver) {
1105                         get_device(dev);
1106                         dev->p->async_driver = drv;
1107                         async = true;
1108                 }
1109                 device_unlock(dev);
1110                 if (async)
1111                         async_schedule_dev(__driver_attach_async_helper, dev);
1112                 return 0;
1113         }
1114
1115         device_driver_attach(drv, dev);
1116
1117         return 0;
1118 }
1119
1120 /**
1121  * driver_attach - try to bind driver to devices.
1122  * @drv: driver.
1123  *
1124  * Walk the list of devices that the bus has on it and try to
1125  * match the driver with each one.  If driver_probe_device()
1126  * returns 0 and the @dev->driver is set, we've found a
1127  * compatible pair.
1128  */
1129 int driver_attach(struct device_driver *drv)
1130 {
1131         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1132 }
1133 EXPORT_SYMBOL_GPL(driver_attach);
1134
1135 /*
1136  * __device_release_driver() must be called with @dev lock held.
1137  * When called for a USB interface, @dev->parent lock must be held as well.
1138  */
1139 static void __device_release_driver(struct device *dev, struct device *parent)
1140 {
1141         struct device_driver *drv;
1142
1143         drv = dev->driver;
1144         if (drv) {
1145                 pm_runtime_get_sync(dev);
1146
1147                 while (device_links_busy(dev)) {
1148                         __device_driver_unlock(dev, parent);
1149
1150                         device_links_unbind_consumers(dev);
1151
1152                         __device_driver_lock(dev, parent);
1153                         /*
1154                          * A concurrent invocation of the same function might
1155                          * have released the driver successfully while this one
1156                          * was waiting, so check for that.
1157                          */
1158                         if (dev->driver != drv) {
1159                                 pm_runtime_put(dev);
1160                                 return;
1161                         }
1162                 }
1163
1164                 driver_sysfs_remove(dev);
1165
1166                 if (dev->bus)
1167                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1168                                                      BUS_NOTIFY_UNBIND_DRIVER,
1169                                                      dev);
1170
1171                 pm_runtime_put_sync(dev);
1172
1173                 device_remove_file(dev, &dev_attr_state_synced);
1174                 device_remove_groups(dev, drv->dev_groups);
1175
1176                 if (dev->bus && dev->bus->remove)
1177                         dev->bus->remove(dev);
1178                 else if (drv->remove)
1179                         drv->remove(dev);
1180
1181                 device_links_driver_cleanup(dev);
1182
1183                 devres_release_all(dev);
1184                 arch_teardown_dma_ops(dev);
1185                 kfree(dev->dma_range_map);
1186                 dev->dma_range_map = NULL;
1187                 dev->driver = NULL;
1188                 dev_set_drvdata(dev, NULL);
1189                 if (dev->pm_domain && dev->pm_domain->dismiss)
1190                         dev->pm_domain->dismiss(dev);
1191                 pm_runtime_reinit(dev);
1192                 dev_pm_set_driver_flags(dev, 0);
1193
1194                 klist_remove(&dev->p->knode_driver);
1195                 device_pm_check_callbacks(dev);
1196                 if (dev->bus)
1197                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1198                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1199                                                      dev);
1200
1201                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1202         }
1203 }
1204
1205 void device_release_driver_internal(struct device *dev,
1206                                     struct device_driver *drv,
1207                                     struct device *parent)
1208 {
1209         __device_driver_lock(dev, parent);
1210
1211         if (!drv || drv == dev->driver)
1212                 __device_release_driver(dev, parent);
1213
1214         __device_driver_unlock(dev, parent);
1215 }
1216
1217 /**
1218  * device_release_driver - manually detach device from driver.
1219  * @dev: device.
1220  *
1221  * Manually detach device from driver.
1222  * When called for a USB interface, @dev->parent lock must be held.
1223  *
1224  * If this function is to be called with @dev->parent lock held, ensure that
1225  * the device's consumers are unbound in advance or that their locks can be
1226  * acquired under the @dev->parent lock.
1227  */
1228 void device_release_driver(struct device *dev)
1229 {
1230         /*
1231          * If anyone calls device_release_driver() recursively from
1232          * within their ->remove callback for the same device, they
1233          * will deadlock right here.
1234          */
1235         device_release_driver_internal(dev, NULL, NULL);
1236 }
1237 EXPORT_SYMBOL_GPL(device_release_driver);
1238
1239 /**
1240  * device_driver_detach - detach driver from a specific device
1241  * @dev: device to detach driver from
1242  *
1243  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1244  * lock if needed.
1245  */
1246 void device_driver_detach(struct device *dev)
1247 {
1248         device_release_driver_internal(dev, NULL, dev->parent);
1249 }
1250
1251 /**
1252  * driver_detach - detach driver from all devices it controls.
1253  * @drv: driver.
1254  */
1255 void driver_detach(struct device_driver *drv)
1256 {
1257         struct device_private *dev_prv;
1258         struct device *dev;
1259
1260         if (driver_allows_async_probing(drv))
1261                 async_synchronize_full();
1262
1263         for (;;) {
1264                 spin_lock(&drv->p->klist_devices.k_lock);
1265                 if (list_empty(&drv->p->klist_devices.k_list)) {
1266                         spin_unlock(&drv->p->klist_devices.k_lock);
1267                         break;
1268                 }
1269                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1270                                      struct device_private,
1271                                      knode_driver.n_node);
1272                 dev = dev_prv->device;
1273                 get_device(dev);
1274                 spin_unlock(&drv->p->klist_devices.k_lock);
1275                 device_release_driver_internal(dev, drv, dev->parent);
1276                 put_device(dev);
1277         }
1278 }