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 /*
  61  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  62  * to prohibit probing of devices as it could be unsafe.
  63  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  64  */
  65 static bool defer_all_probes;
  66
  67 /*
  68  * deferred_probe_work_func() - Retry probing devices in the active list.
  69  */
  70 static void deferred_probe_work_func(struct work_struct *work)
  71 {
  72         struct device *dev;
  73         struct device_private *private;
  74         /*
  75          * This block processes every device in the deferred 'active' list.
  76          * Each device is removed from the active list and passed to
  77          * bus_probe_device() to re-attempt the probe.  The loop continues
  78          * until every device in the active list is removed and retried.
  79          *
  80          * Note: Once the device is removed from the list and the mutex is
  81          * released, it is possible for the device get freed by another thread
  82          * and cause a illegal pointer dereference.  This code uses
  83          * get/put_device() to ensure the device structure cannot disappear
  84          * from under our feet.
  85          */
  86         mutex_lock(&deferred_probe_mutex);
  87         while (!list_empty(&deferred_probe_active_list)) {
  88                 private = list_first_entry(&deferred_probe_active_list,
  89                                         typeof(*dev->p), deferred_probe);
  90                 dev = private->device;
  91                 list_del_init(&private->deferred_probe);
  92
  93                 get_device(dev);
  94
  95                 /*
  96                  * Drop the mutex while probing each device; the probe path may
  97                  * manipulate the deferred list
  98                  */
  99                 mutex_unlock(&deferred_probe_mutex);
 100
 101                 /*
 102                  * Force the device to the end of the dpm_list since
 103                  * the PM code assumes that the order we add things to
 104                  * the list is a good order for suspend but deferred
 105                  * probe makes that very unsafe.
 106                  */
 107                 device_pm_move_to_tail(dev);
 108
 109                 dev_dbg(dev, "Retrying from deferred list\n");
 110                 bus_probe_device(dev);
 111                 mutex_lock(&deferred_probe_mutex);
 112
 113                 put_device(dev);
 114         }
 115         mutex_unlock(&deferred_probe_mutex);
 116 }
 117 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 118
 119 void driver_deferred_probe_add(struct device *dev)
 120 {
 121         mutex_lock(&deferred_probe_mutex);
 122         if (list_empty(&dev->p->deferred_probe)) {
 123                 dev_dbg(dev, "Added to deferred list\n");
 124                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 125         }
 126         mutex_unlock(&deferred_probe_mutex);
 127 }
 128
 129 void driver_deferred_probe_del(struct device *dev)
 130 {
 131         mutex_lock(&deferred_probe_mutex);
 132         if (!list_empty(&dev->p->deferred_probe)) {
 133                 dev_dbg(dev, "Removed from deferred list\n");
 134                 list_del_init(&dev->p->deferred_probe);
 135         }
 136         mutex_unlock(&deferred_probe_mutex);
 137 }
 138
 139 static bool driver_deferred_probe_enable = false;
 140 /**
 141  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 142  *
 143  * This functions moves all devices from the pending list to the active
 144  * list and schedules the deferred probe workqueue to process them.  It
 145  * should be called anytime a driver is successfully bound to a device.
 146  *
 147  * Note, there is a race condition in multi-threaded probe. In the case where
 148  * more than one device is probing at the same time, it is possible for one
 149  * probe to complete successfully while another is about to defer. If the second
 150  * depends on the first, then it will get put on the pending list after the
 151  * trigger event has already occurred and will be stuck there.
 152  *
 153  * The atomic 'deferred_trigger_count' is used to determine if a successful
 154  * trigger has occurred in the midst of probing a driver. If the trigger count
 155  * changes in the midst of a probe, then deferred processing should be triggered
 156  * again.
 157  */
 158 static void driver_deferred_probe_trigger(void)
 159 {
 160         if (!driver_deferred_probe_enable)
 161                 return;
 162
 163         /*
 164          * A successful probe means that all the devices in the pending list
 165          * should be triggered to be reprobed.  Move all the deferred devices
 166          * into the active list so they can be retried by the workqueue
 167          */
 168         mutex_lock(&deferred_probe_mutex);
 169         atomic_inc(&deferred_trigger_count);
 170         list_splice_tail_init(&deferred_probe_pending_list,
 171                               &deferred_probe_active_list);
 172         mutex_unlock(&deferred_probe_mutex);
 173
 174         /*
 175          * Kick the re-probe thread.  It may already be scheduled, but it is
 176          * safe to kick it again.
 177          */
 178         schedule_work(&deferred_probe_work);
 179 }
 180
 181 /**
 182  * device_block_probing() - Block/defere device's probes
 183  *
 184  *      It will disable probing of devices and defer their probes instead.
 185  */
 186 void device_block_probing(void)
 187 {
 188         defer_all_probes = true;
 189         /* sync with probes to avoid races. */
 190         wait_for_device_probe();
 191 }
 192
 193 /**
 194  * device_unblock_probing() - Unblock/enable device's probes
 195  *
 196  *      It will restore normal behavior and trigger re-probing of deferred
 197  * devices.
 198  */
 199 void device_unblock_probing(void)
 200 {
 201         defer_all_probes = false;
 202         driver_deferred_probe_trigger();
 203 }
 204
 205 /*
 206  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 207  */
 208 static int deferred_devs_show(struct seq_file *s, void *data)
 209 {
 210         struct device_private *curr;
 211
 212         mutex_lock(&deferred_probe_mutex);
 213
 214         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 215                 seq_printf(s, "%s\n", dev_name(curr->device));
 216
 217         mutex_unlock(&deferred_probe_mutex);
 218
 219         return 0;
 220 }
 221 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 222
 223 #ifdef CONFIG_MODULES
 224 /*
 225  * In the case of modules, set the default probe timeout to
 226  * 30 seconds to give userland some time to load needed modules
 227  */
 228 static int deferred_probe_timeout = 30;
 229 #else
 230 /* In the case of !modules, no probe timeout needed */
 231 static int deferred_probe_timeout = -1;
 232 #endif
 233 static int __init deferred_probe_timeout_setup(char *str)
 234 {
 235         deferred_probe_timeout = simple_strtol(str, NULL, 10);
 236         return 1;
 237 }
 238 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 239
 240 /**
 241  * driver_deferred_probe_check_state() - Check deferred probe state
 242  * @dev: device to check
 243  *
 244  * Returns -ENODEV if init is done and all built-in drivers have had a chance
 245  * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug
 246  * timeout has expired, or -EPROBE_DEFER if none of those conditions are met.
 247  *
 248  * Drivers or subsystems can opt-in to calling this function instead of directly
 249  * returning -EPROBE_DEFER.
 250  */
 251 int driver_deferred_probe_check_state(struct device *dev)
 252 {
 253         if (initcalls_done) {
 254                 if (!deferred_probe_timeout) {
 255                         dev_WARN(dev, "deferred probe timeout, ignoring dependency");
 256                         return -ETIMEDOUT;
 257                 }
 258                 dev_warn(dev, "ignoring dependency for device, assuming no driver");
 259                 return -ENODEV;
 260         }
 261         return -EPROBE_DEFER;
 262 }
 263
 264 static void deferred_probe_timeout_work_func(struct work_struct *work)
 265 {
 266         struct device_private *p;
 267
 268         deferred_probe_timeout = 0;
 269         driver_deferred_probe_trigger();
 270         flush_work(&deferred_probe_work);
 271
 272         mutex_lock(&deferred_probe_mutex);
 273         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 274                 dev_info(p->device, "deferred probe pending\n");
 275         mutex_unlock(&deferred_probe_mutex);
 276 }
 277 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 278
 279 /**
 280  * deferred_probe_initcall() - Enable probing of deferred devices
 281  *
 282  * We don't want to get in the way when the bulk of drivers are getting probed.
 283  * Instead, this initcall makes sure that deferred probing is delayed until
 284  * late_initcall time.
 285  */
 286 static int deferred_probe_initcall(void)
 287 {
 288         deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
 289                                                NULL, &deferred_devs_fops);
 290
 291         driver_deferred_probe_enable = true;
 292         driver_deferred_probe_trigger();
 293         /* Sort as many dependencies as possible before exiting initcalls */
 294         flush_work(&deferred_probe_work);
 295         initcalls_done = true;
 296
 297         /*
 298          * Trigger deferred probe again, this time we won't defer anything
 299          * that is optional
 300          */
 301         driver_deferred_probe_trigger();
 302         flush_work(&deferred_probe_work);
 303
 304         if (deferred_probe_timeout > 0) {
 305                 schedule_delayed_work(&deferred_probe_timeout_work,
 306                         deferred_probe_timeout * HZ);
 307         }
 308         return 0;
 309 }
 310 late_initcall(deferred_probe_initcall);
 311
 312 static void __exit deferred_probe_exit(void)
 313 {
 314         debugfs_remove_recursive(deferred_devices);
 315 }
 316 __exitcall(deferred_probe_exit);
 317
 318 /**
 319  * device_is_bound() - Check if device is bound to a driver
 320  * @dev: device to check
 321  *
 322  * Returns true if passed device has already finished probing successfully
 323  * against a driver.
 324  *
 325  * This function must be called with the device lock held.
 326  */
 327 bool device_is_bound(struct device *dev)
 328 {
 329         return dev->p && klist_node_attached(&dev->p->knode_driver);
 330 }
 331
 332 static void driver_bound(struct device *dev)
 333 {
 334         if (device_is_bound(dev)) {
 335                 printk(KERN_WARNING "%s: device %s already bound\n",
 336                         __func__, kobject_name(&dev->kobj));
 337                 return;
 338         }
 339
 340         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 341                  __func__, dev_name(dev));
 342
 343         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 344         device_links_driver_bound(dev);
 345
 346         device_pm_check_callbacks(dev);
 347
 348         /*
 349          * Make sure the device is no longer in one of the deferred lists and
 350          * kick off retrying all pending devices
 351          */
 352         driver_deferred_probe_del(dev);
 353         driver_deferred_probe_trigger();
 354
 355         if (dev->bus)
 356                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 357                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 358
 359         kobject_uevent(&dev->kobj, KOBJ_BIND);
 360 }
 361
 362 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 363                             const char *buf, size_t count)
 364 {
 365         device_lock(dev);
 366         dev->driver->coredump(dev);
 367         device_unlock(dev);
 368
 369         return count;
 370 }
 371 static DEVICE_ATTR_WO(coredump);
 372
 373 static int driver_sysfs_add(struct device *dev)
 374 {
 375         int ret;
 376
 377         if (dev->bus)
 378                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 379                                              BUS_NOTIFY_BIND_DRIVER, dev);
 380
 381         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 382                                 kobject_name(&dev->kobj));
 383         if (ret)
 384                 goto fail;
 385
 386         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 387                                 "driver");
 388         if (ret)
 389                 goto rm_dev;
 390
 391         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
 392             !device_create_file(dev, &dev_attr_coredump))
 393                 return 0;
 394
 395         sysfs_remove_link(&dev->kobj, "driver");
 396
 397 rm_dev:
 398         sysfs_remove_link(&dev->driver->p->kobj,
 399                           kobject_name(&dev->kobj));
 400
 401 fail:
 402         return ret;
 403 }
 404
 405 static void driver_sysfs_remove(struct device *dev)
 406 {
 407         struct device_driver *drv = dev->driver;
 408
 409         if (drv) {
 410                 if (drv->coredump)
 411                         device_remove_file(dev, &dev_attr_coredump);
 412                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 413                 sysfs_remove_link(&dev->kobj, "driver");
 414         }
 415 }
 416
 417 /**
 418  * device_bind_driver - bind a driver to one device.
 419  * @dev: device.
 420  *
 421  * Allow manual attachment of a driver to a device.
 422  * Caller must have already set @dev->driver.
 423  *
 424  * Note that this does not modify the bus reference count
 425  * nor take the bus's rwsem. Please verify those are accounted
 426  * for before calling this. (It is ok to call with no other effort
 427  * from a driver's probe() method.)
 428  *
 429  * This function must be called with the device lock held.
 430  */
 431 int device_bind_driver(struct device *dev)
 432 {
 433         int ret;
 434
 435         ret = driver_sysfs_add(dev);
 436         if (!ret)
 437                 driver_bound(dev);
 438         else if (dev->bus)
 439                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 440                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 441         return ret;
 442 }
 443 EXPORT_SYMBOL_GPL(device_bind_driver);
 444
 445 static atomic_t probe_count = ATOMIC_INIT(0);
 446 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 447
 448 static void driver_deferred_probe_add_trigger(struct device *dev,
 449                                               int local_trigger_count)
 450 {
 451         driver_deferred_probe_add(dev);
 452         /* Did a trigger occur while probing? Need to re-trigger if yes */
 453         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 454                 driver_deferred_probe_trigger();
 455 }
 456
 457 static int really_probe(struct device *dev, struct device_driver *drv)
 458 {
 459         int ret = -EPROBE_DEFER;
 460         int local_trigger_count = atomic_read(&deferred_trigger_count);
 461         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 462                            !drv->suppress_bind_attrs;
 463
 464         if (defer_all_probes) {
 465                 /*
 466                  * Value of defer_all_probes can be set only by
 467                  * device_defer_all_probes_enable() which, in turn, will call
 468                  * wait_for_device_probe() right after that to avoid any races.
 469                  */
 470                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 471                 driver_deferred_probe_add(dev);
 472                 return ret;
 473         }
 474
 475         ret = device_links_check_suppliers(dev);
 476         if (ret == -EPROBE_DEFER)
 477                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 478         if (ret)
 479                 return ret;
 480
 481         atomic_inc(&probe_count);
 482         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 483                  drv->bus->name, __func__, drv->name, dev_name(dev));
 484         if (!list_empty(&dev->devres_head)) {
 485                 dev_crit(dev, "Resources present before probing\n");
 486                 ret = -EBUSY;
 487                 goto done;
 488         }
 489
 490 re_probe:
 491         dev->driver = drv;
 492
 493         /* If using pinctrl, bind pins now before probing */
 494         ret = pinctrl_bind_pins(dev);
 495         if (ret)
 496                 goto pinctrl_bind_failed;
 497
 498         ret = dma_configure(dev);
 499         if (ret)
 500                 goto probe_failed;
 501
 502         if (driver_sysfs_add(dev)) {
 503                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 504                         __func__, dev_name(dev));
 505                 goto probe_failed;
 506         }
 507
 508         if (dev->pm_domain && dev->pm_domain->activate) {
 509                 ret = dev->pm_domain->activate(dev);
 510                 if (ret)
 511                         goto probe_failed;
 512         }
 513
 514         if (dev->bus->probe) {
 515                 ret = dev->bus->probe(dev);
 516                 if (ret)
 517                         goto probe_failed;
 518         } else if (drv->probe) {
 519                 ret = drv->probe(dev);
 520                 if (ret)
 521                         goto probe_failed;
 522         }
 523
 524         if (test_remove) {
 525                 test_remove = false;
 526
 527                 if (dev->bus->remove)
 528                         dev->bus->remove(dev);
 529                 else if (drv->remove)
 530                         drv->remove(dev);
 531
 532                 devres_release_all(dev);
 533                 driver_sysfs_remove(dev);
 534                 dev->driver = NULL;
 535                 dev_set_drvdata(dev, NULL);
 536                 if (dev->pm_domain && dev->pm_domain->dismiss)
 537                         dev->pm_domain->dismiss(dev);
 538                 pm_runtime_reinit(dev);
 539
 540                 goto re_probe;
 541         }
 542
 543         pinctrl_init_done(dev);
 544
 545         if (dev->pm_domain && dev->pm_domain->sync)
 546                 dev->pm_domain->sync(dev);
 547
 548         driver_bound(dev);
 549         ret = 1;
 550         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 551                  drv->bus->name, __func__, dev_name(dev), drv->name);
 552         goto done;
 553
 554 probe_failed:
 555         if (dev->bus)
 556                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 557                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 558 pinctrl_bind_failed:
 559         device_links_no_driver(dev);
 560         devres_release_all(dev);
 561         dma_deconfigure(dev);
 562         driver_sysfs_remove(dev);
 563         dev->driver = NULL;
 564         dev_set_drvdata(dev, NULL);
 565         if (dev->pm_domain && dev->pm_domain->dismiss)
 566                 dev->pm_domain->dismiss(dev);
 567         pm_runtime_reinit(dev);
 568         dev_pm_set_driver_flags(dev, 0);
 569
 570         switch (ret) {
 571         case -EPROBE_DEFER:
 572                 /* Driver requested deferred probing */
 573                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 574                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 575                 break;
 576         case -ENODEV:
 577         case -ENXIO:
 578                 pr_debug("%s: probe of %s rejects match %d\n",
 579                          drv->name, dev_name(dev), ret);
 580                 break;
 581         default:
 582                 /* driver matched but the probe failed */
 583                 printk(KERN_WARNING
 584                        "%s: probe of %s failed with error %d\n",
 585                        drv->name, dev_name(dev), ret);
 586         }
 587         /*
 588          * Ignore errors returned by ->probe so that the next driver can try
 589          * its luck.
 590          */
 591         ret = 0;
 592 done:
 593         atomic_dec(&probe_count);
 594         wake_up_all(&probe_waitqueue);
 595         return ret;
 596 }
 597
 598 /*
 599  * For initcall_debug, show the driver probe time.
 600  */
 601 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 602 {
 603         ktime_t calltime, delta, rettime;
 604         int ret;
 605
 606         calltime = ktime_get();
 607         ret = really_probe(dev, drv);
 608         rettime = ktime_get();
 609         delta = ktime_sub(rettime, calltime);
 610         printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
 611                dev_name(dev), ret, (s64) ktime_to_us(delta));
 612         return ret;
 613 }
 614
 615 /**
 616  * driver_probe_done
 617  * Determine if the probe sequence is finished or not.
 618  *
 619  * Should somehow figure out how to use a semaphore, not an atomic variable...
 620  */
 621 int driver_probe_done(void)
 622 {
 623         pr_debug("%s: probe_count = %d\n", __func__,
 624                  atomic_read(&probe_count));
 625         if (atomic_read(&probe_count))
 626                 return -EBUSY;
 627         return 0;
 628 }
 629
 630 /**
 631  * wait_for_device_probe
 632  * Wait for device probing to be completed.
 633  */
 634 void wait_for_device_probe(void)
 635 {
 636         /* wait for the deferred probe workqueue to finish */
 637         flush_work(&deferred_probe_work);
 638
 639         /* wait for the known devices to complete their probing */
 640         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 641         async_synchronize_full();
 642 }
 643 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 644
 645 /**
 646  * driver_probe_device - attempt to bind device & driver together
 647  * @drv: driver to bind a device to
 648  * @dev: device to try to bind to the driver
 649  *
 650  * This function returns -ENODEV if the device is not registered,
 651  * 1 if the device is bound successfully and 0 otherwise.
 652  *
 653  * This function must be called with @dev lock held.  When called for a
 654  * USB interface, @dev->parent lock must be held as well.
 655  *
 656  * If the device has a parent, runtime-resume the parent before driver probing.
 657  */
 658 int driver_probe_device(struct device_driver *drv, struct device *dev)
 659 {
 660         int ret = 0;
 661
 662         if (!device_is_registered(dev))
 663                 return -ENODEV;
 664
 665         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 666                  drv->bus->name, __func__, dev_name(dev), drv->name);
 667
 668         pm_runtime_get_suppliers(dev);
 669         if (dev->parent)
 670                 pm_runtime_get_sync(dev->parent);
 671
 672         pm_runtime_barrier(dev);
 673         if (initcall_debug)
 674                 ret = really_probe_debug(dev, drv);
 675         else
 676                 ret = really_probe(dev, drv);
 677         pm_request_idle(dev);
 678
 679         if (dev->parent)
 680                 pm_runtime_put(dev->parent);
 681
 682         pm_runtime_put_suppliers(dev);
 683         return ret;
 684 }
 685
 686 bool driver_allows_async_probing(struct device_driver *drv)
 687 {
 688         switch (drv->probe_type) {
 689         case PROBE_PREFER_ASYNCHRONOUS:
 690                 return true;
 691
 692         case PROBE_FORCE_SYNCHRONOUS:
 693                 return false;
 694
 695         default:
 696                 if (module_requested_async_probing(drv->owner))
 697                         return true;
 698
 699                 return false;
 700         }
 701 }
 702
 703 struct device_attach_data {
 704         struct device *dev;
 705
 706         /*
 707          * Indicates whether we are are considering asynchronous probing or
 708          * not. Only initial binding after device or driver registration
 709          * (including deferral processing) may be done asynchronously, the
 710          * rest is always synchronous, as we expect it is being done by
 711          * request from userspace.
 712          */
 713         bool check_async;
 714
 715         /*
 716          * Indicates if we are binding synchronous or asynchronous drivers.
 717          * When asynchronous probing is enabled we'll execute 2 passes
 718          * over drivers: first pass doing synchronous probing and second
 719          * doing asynchronous probing (if synchronous did not succeed -
 720          * most likely because there was no driver requiring synchronous
 721          * probing - and we found asynchronous driver during first pass).
 722          * The 2 passes are done because we can't shoot asynchronous
 723          * probe for given device and driver from bus_for_each_drv() since
 724          * driver pointer is not guaranteed to stay valid once
 725          * bus_for_each_drv() iterates to the next driver on the bus.
 726          */
 727         bool want_async;
 728
 729         /*
 730          * We'll set have_async to 'true' if, while scanning for matching
 731          * driver, we'll encounter one that requests asynchronous probing.
 732          */
 733         bool have_async;
 734 };
 735
 736 static int __device_attach_driver(struct device_driver *drv, void *_data)
 737 {
 738         struct device_attach_data *data = _data;
 739         struct device *dev = data->dev;
 740         bool async_allowed;
 741         int ret;
 742
 743         ret = driver_match_device(drv, dev);
 744         if (ret == 0) {
 745                 /* no match */
 746                 return 0;
 747         } else if (ret == -EPROBE_DEFER) {
 748                 dev_dbg(dev, "Device match requests probe deferral\n");
 749                 driver_deferred_probe_add(dev);
 750                 /*
 751                  * Device can't match with a driver right now, so don't attempt
 752                  * to match or bind with other drivers on the bus.
 753                  */
 754                 return ret;
 755         } else if (ret < 0) {
 756                 dev_dbg(dev, "Bus failed to match device: %d", ret);
 757                 return ret;
 758         } /* ret > 0 means positive match */
 759
 760         async_allowed = driver_allows_async_probing(drv);
 761
 762         if (async_allowed)
 763                 data->have_async = true;
 764
 765         if (data->check_async && async_allowed != data->want_async)
 766                 return 0;
 767
 768         return driver_probe_device(drv, dev);
 769 }
 770
 771 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 772 {
 773         struct device *dev = _dev;
 774         struct device_attach_data data = {
 775                 .dev            = dev,
 776                 .check_async    = true,
 777                 .want_async     = true,
 778         };
 779
 780         device_lock(dev);
 781
 782         /*
 783          * Check if device has already been removed or claimed. This may
 784          * happen with driver loading, device discovery/registration,
 785          * and deferred probe processing happens all at once with
 786          * multiple threads.
 787          */
 788         if (dev->p->dead || dev->driver)
 789                 goto out_unlock;
 790
 791         if (dev->parent)
 792                 pm_runtime_get_sync(dev->parent);
 793
 794         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 795         dev_dbg(dev, "async probe completed\n");
 796
 797         pm_request_idle(dev);
 798
 799         if (dev->parent)
 800                 pm_runtime_put(dev->parent);
 801 out_unlock:
 802         device_unlock(dev);
 803
 804         put_device(dev);
 805 }
 806
 807 static int __device_attach(struct device *dev, bool allow_async)
 808 {
 809         int ret = 0;
 810
 811         device_lock(dev);
 812         if (dev->p->dead) {
 813                 goto out_unlock;
 814         } else if (dev->driver) {
 815                 if (device_is_bound(dev)) {
 816                         ret = 1;
 817                         goto out_unlock;
 818                 }
 819                 ret = device_bind_driver(dev);
 820                 if (ret == 0)
 821                         ret = 1;
 822                 else {
 823                         dev->driver = NULL;
 824                         ret = 0;
 825                 }
 826         } else {
 827                 struct device_attach_data data = {
 828                         .dev = dev,
 829                         .check_async = allow_async,
 830                         .want_async = false,
 831                 };
 832
 833                 if (dev->parent)
 834                         pm_runtime_get_sync(dev->parent);
 835
 836                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 837                                         __device_attach_driver);
 838                 if (!ret && allow_async && data.have_async) {
 839                         /*
 840                          * If we could not find appropriate driver
 841                          * synchronously and we are allowed to do
 842                          * async probes and there are drivers that
 843                          * want to probe asynchronously, we'll
 844                          * try them.
 845                          */
 846                         dev_dbg(dev, "scheduling asynchronous probe\n");
 847                         get_device(dev);
 848                         async_schedule(__device_attach_async_helper, dev);
 849                 } else {
 850                         pm_request_idle(dev);
 851                 }
 852
 853                 if (dev->parent)
 854                         pm_runtime_put(dev->parent);
 855         }
 856 out_unlock:
 857         device_unlock(dev);
 858         return ret;
 859 }
 860
 861 /**
 862  * device_attach - try to attach device to a driver.
 863  * @dev: device.
 864  *
 865  * Walk the list of drivers that the bus has and call
 866  * driver_probe_device() for each pair. If a compatible
 867  * pair is found, break out and return.
 868  *
 869  * Returns 1 if the device was bound to a driver;
 870  * 0 if no matching driver was found;
 871  * -ENODEV if the device is not registered.
 872  *
 873  * When called for a USB interface, @dev->parent lock must be held.
 874  */
 875 int device_attach(struct device *dev)
 876 {
 877         return __device_attach(dev, false);
 878 }
 879 EXPORT_SYMBOL_GPL(device_attach);
 880
 881 void device_initial_probe(struct device *dev)
 882 {
 883         __device_attach(dev, true);
 884 }
 885
 886 static int __driver_attach(struct device *dev, void *data)
 887 {
 888         struct device_driver *drv = data;
 889         int ret;
 890
 891         /*
 892          * Lock device and try to bind to it. We drop the error
 893          * here and always return 0, because we need to keep trying
 894          * to bind to devices and some drivers will return an error
 895          * simply if it didn't support the device.
 896          *
 897          * driver_probe_device() will spit a warning if there
 898          * is an error.
 899          */
 900
 901         ret = driver_match_device(drv, dev);
 902         if (ret == 0) {
 903                 /* no match */
 904                 return 0;
 905         } else if (ret == -EPROBE_DEFER) {
 906                 dev_dbg(dev, "Device match requests probe deferral\n");
 907                 driver_deferred_probe_add(dev);
 908                 /*
 909                  * Driver could not match with device, but may match with
 910                  * another device on the bus.
 911                  */
 912                 return 0;
 913         } else if (ret < 0) {
 914                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 915                 /*
 916                  * Driver could not match with device, but may match with
 917                  * another device on the bus.
 918                  */
 919                 return 0;
 920         } /* ret > 0 means positive match */
 921
 922         if (dev->parent && dev->bus->need_parent_lock)
 923                 device_lock(dev->parent);
 924         device_lock(dev);
 925         if (!dev->p->dead && !dev->driver)
 926                 driver_probe_device(drv, dev);
 927         device_unlock(dev);
 928         if (dev->parent && dev->bus->need_parent_lock)
 929                 device_unlock(dev->parent);
 930
 931         return 0;
 932 }
 933
 934 /**
 935  * driver_attach - try to bind driver to devices.
 936  * @drv: driver.
 937  *
 938  * Walk the list of devices that the bus has on it and try to
 939  * match the driver with each one.  If driver_probe_device()
 940  * returns 0 and the @dev->driver is set, we've found a
 941  * compatible pair.
 942  */
 943 int driver_attach(struct device_driver *drv)
 944 {
 945         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 946 }
 947 EXPORT_SYMBOL_GPL(driver_attach);
 948
 949 /*
 950  * __device_release_driver() must be called with @dev lock held.
 951  * When called for a USB interface, @dev->parent lock must be held as well.
 952  */
 953 static void __device_release_driver(struct device *dev, struct device *parent)
 954 {
 955         struct device_driver *drv;
 956
 957         drv = dev->driver;
 958         if (drv) {
 959                 pm_runtime_get_sync(dev);
 960
 961                 while (device_links_busy(dev)) {
 962                         device_unlock(dev);
 963                         if (parent && dev->bus->need_parent_lock)
 964                                 device_unlock(parent);
 965
 966                         device_links_unbind_consumers(dev);
 967                         if (parent && dev->bus->need_parent_lock)
 968                                 device_lock(parent);
 969
 970                         device_lock(dev);
 971                         /*
 972                          * A concurrent invocation of the same function might
 973                          * have released the driver successfully while this one
 974                          * was waiting, so check for that.
 975                          */
 976                         if (dev->driver != drv) {
 977                                 pm_runtime_put(dev);
 978                                 return;
 979                         }
 980                 }
 981
 982                 pm_runtime_clean_up_links(dev);
 983
 984                 driver_sysfs_remove(dev);
 985
 986                 if (dev->bus)
 987                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 988                                                      BUS_NOTIFY_UNBIND_DRIVER,
 989                                                      dev);
 990
 991                 pm_runtime_put_sync(dev);
 992
 993                 if (dev->bus && dev->bus->remove)
 994                         dev->bus->remove(dev);
 995                 else if (drv->remove)
 996                         drv->remove(dev);
 997
 998                 device_links_driver_cleanup(dev);
 999
1000                 devres_release_all(dev);
1001                 dma_deconfigure(dev);
1002                 dev->driver = NULL;
1003                 dev_set_drvdata(dev, NULL);
1004                 if (dev->pm_domain && dev->pm_domain->dismiss)
1005                         dev->pm_domain->dismiss(dev);
1006                 pm_runtime_reinit(dev);
1007                 dev_pm_set_driver_flags(dev, 0);
1008
1009                 klist_remove(&dev->p->knode_driver);
1010                 device_pm_check_callbacks(dev);
1011                 if (dev->bus)
1012                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1013                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1014                                                      dev);
1015
1016                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1017         }
1018 }
1019
1020 void device_release_driver_internal(struct device *dev,
1021                                     struct device_driver *drv,
1022                                     struct device *parent)
1023 {
1024         if (parent && dev->bus->need_parent_lock)
1025                 device_lock(parent);
1026
1027         device_lock(dev);
1028         if (!drv || drv == dev->driver)
1029                 __device_release_driver(dev, parent);
1030
1031         device_unlock(dev);
1032         if (parent && dev->bus->need_parent_lock)
1033                 device_unlock(parent);
1034 }
1035
1036 /**
1037  * device_release_driver - manually detach device from driver.
1038  * @dev: device.
1039  *
1040  * Manually detach device from driver.
1041  * When called for a USB interface, @dev->parent lock must be held.
1042  *
1043  * If this function is to be called with @dev->parent lock held, ensure that
1044  * the device's consumers are unbound in advance or that their locks can be
1045  * acquired under the @dev->parent lock.
1046  */
1047 void device_release_driver(struct device *dev)
1048 {
1049         /*
1050          * If anyone calls device_release_driver() recursively from
1051          * within their ->remove callback for the same device, they
1052          * will deadlock right here.
1053          */
1054         device_release_driver_internal(dev, NULL, NULL);
1055 }
1056 EXPORT_SYMBOL_GPL(device_release_driver);
1057
1058 /**
1059  * driver_detach - detach driver from all devices it controls.
1060  * @drv: driver.
1061  */
1062 void driver_detach(struct device_driver *drv)
1063 {
1064         struct device_private *dev_prv;
1065         struct device *dev;
1066
1067         if (driver_allows_async_probing(drv))
1068                 async_synchronize_full();
1069
1070         for (;;) {
1071                 spin_lock(&drv->p->klist_devices.k_lock);
1072                 if (list_empty(&drv->p->klist_devices.k_list)) {
1073                         spin_unlock(&drv->p->klist_devices.k_lock);
1074                         break;
1075                 }
1076                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
1077                                      struct device_private,
1078                                      knode_driver.n_node);
1079                 dev = dev_prv->device;
1080                 get_device(dev);
1081                 spin_unlock(&drv->p->klist_devices.k_lock);
1082                 device_release_driver_internal(dev, drv, dev->parent);
1083                 put_device(dev);
1084         }
1085 }