drivers/base/dd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * drivers/base/dd.c - The core device/driver interactions.
   4  *
   5  * This file contains the (sometimes tricky) code that controls the
   6  * interactions between devices and drivers, which primarily includes
   7  * driver binding and unbinding.
   8  *
   9  * All of this code used to exist in drivers/base/bus.c, but was
  10  * relocated to here in the name of compartmentalization (since it wasn't
  11  * strictly code just for the 'struct bus_type'.
  12  *
  13  * Copyright (c) 2002-5 Patrick Mochel
  14  * Copyright (c) 2002-3 Open Source Development Labs
  15  * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
  16  * Copyright (c) 2007-2009 Novell Inc.
  17  */
  18
  19 #include <linux/debugfs.h>
  20 #include <linux/device.h>
  21 #include <linux/delay.h>
  22 #include <linux/dma-map-ops.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/kthread.h>
  26 #include <linux/wait.h>
  27 #include <linux/async.h>
  28 #include <linux/pm_runtime.h>
  29 #include <linux/pinctrl/devinfo.h>
  30 #include <linux/slab.h>
  31
  32 #include "base.h"
  33 #include "power/power.h"
  34
  35 /*
  36  * Deferred Probe infrastructure.
  37  *
  38  * Sometimes driver probe order matters, but the kernel doesn't always have
  39  * dependency information which means some drivers will get probed before a
  40  * resource it depends on is available.  For example, an SDHCI driver may
  41  * first need a GPIO line from an i2c GPIO controller before it can be
  42  * initialized.  If a required resource is not available yet, a driver can
  43  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  44  *
  45  * Deferred probe maintains two lists of devices, a pending list and an active
  46  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  47  * pending list.  A successful driver probe will trigger moving all devices
  48  * from the pending to the active list so that the workqueue will eventually
  49  * retry them.
  50  *
  51  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  52  * of the (struct device*)->p->deferred_probe pointers are manipulated
  53  */
  54 static DEFINE_MUTEX(deferred_probe_mutex);
  55 static LIST_HEAD(deferred_probe_pending_list);
  56 static LIST_HEAD(deferred_probe_active_list);
  57 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
  58 static bool initcalls_done;
  59
  60 /* Save the async probe drivers' name from kernel cmdline */
  61 #define ASYNC_DRV_NAMES_MAX_LEN 256
  62 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
  63
  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 static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
  72 {
  73         kfree(dev->p->deferred_probe_reason);
  74         dev->p->deferred_probe_reason = reason;
  75 }
  76
  77 /*
  78  * deferred_probe_work_func() - Retry probing devices in the active list.
  79  */
  80 static void deferred_probe_work_func(struct work_struct *work)
  81 {
  82         struct device *dev;
  83         struct device_private *private;
  84         /*
  85          * This block processes every device in the deferred 'active' list.
  86          * Each device is removed from the active list and passed to
  87          * bus_probe_device() to re-attempt the probe.  The loop continues
  88          * until every device in the active list is removed and retried.
  89          *
  90          * Note: Once the device is removed from the list and the mutex is
  91          * released, it is possible for the device get freed by another thread
  92          * and cause a illegal pointer dereference.  This code uses
  93          * get/put_device() to ensure the device structure cannot disappear
  94          * from under our feet.
  95          */
  96         mutex_lock(&deferred_probe_mutex);
  97         while (!list_empty(&deferred_probe_active_list)) {
  98                 private = list_first_entry(&deferred_probe_active_list,
  99                                         typeof(*dev->p), deferred_probe);
 100                 dev = private->device;
 101                 list_del_init(&private->deferred_probe);
 102
 103                 get_device(dev);
 104
 105                 __device_set_deferred_probe_reason(dev, NULL);
 106
 107                 /*
 108                  * Drop the mutex while probing each device; the probe path may
 109                  * manipulate the deferred list
 110                  */
 111                 mutex_unlock(&deferred_probe_mutex);
 112
 113                 /*
 114                  * Force the device to the end of the dpm_list since
 115                  * the PM code assumes that the order we add things to
 116                  * the list is a good order for suspend but deferred
 117                  * probe makes that very unsafe.
 118                  */
 119                 device_pm_move_to_tail(dev);
 120
 121                 dev_dbg(dev, "Retrying from deferred list\n");
 122                 bus_probe_device(dev);
 123                 mutex_lock(&deferred_probe_mutex);
 124
 125                 put_device(dev);
 126         }
 127         mutex_unlock(&deferred_probe_mutex);
 128 }
 129 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 130
 131 void driver_deferred_probe_add(struct device *dev)
 132 {
 133         if (!dev->can_match)
 134                 return;
 135
 136         mutex_lock(&deferred_probe_mutex);
 137         if (list_empty(&dev->p->deferred_probe)) {
 138                 dev_dbg(dev, "Added to deferred list\n");
 139                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 140         }
 141         mutex_unlock(&deferred_probe_mutex);
 142 }
 143
 144 void driver_deferred_probe_del(struct device *dev)
 145 {
 146         mutex_lock(&deferred_probe_mutex);
 147         if (!list_empty(&dev->p->deferred_probe)) {
 148                 dev_dbg(dev, "Removed from deferred list\n");
 149                 list_del_init(&dev->p->deferred_probe);
 150                 __device_set_deferred_probe_reason(dev, NULL);
 151         }
 152         mutex_unlock(&deferred_probe_mutex);
 153 }
 154
 155 static bool driver_deferred_probe_enable = false;
 156 /**
 157  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 158  *
 159  * This functions moves all devices from the pending list to the active
 160  * list and schedules the deferred probe workqueue to process them.  It
 161  * should be called anytime a driver is successfully bound to a device.
 162  *
 163  * Note, there is a race condition in multi-threaded probe. In the case where
 164  * more than one device is probing at the same time, it is possible for one
 165  * probe to complete successfully while another is about to defer. If the second
 166  * depends on the first, then it will get put on the pending list after the
 167  * trigger event has already occurred and will be stuck there.
 168  *
 169  * The atomic 'deferred_trigger_count' is used to determine if a successful
 170  * trigger has occurred in the midst of probing a driver. If the trigger count
 171  * changes in the midst of a probe, then deferred processing should be triggered
 172  * again.
 173  */
 174 static void driver_deferred_probe_trigger(void)
 175 {
 176         if (!driver_deferred_probe_enable)
 177                 return;
 178
 179         /*
 180          * A successful probe means that all the devices in the pending list
 181          * should be triggered to be reprobed.  Move all the deferred devices
 182          * into the active list so they can be retried by the workqueue
 183          */
 184         mutex_lock(&deferred_probe_mutex);
 185         atomic_inc(&deferred_trigger_count);
 186         list_splice_tail_init(&deferred_probe_pending_list,
 187                               &deferred_probe_active_list);
 188         mutex_unlock(&deferred_probe_mutex);
 189
 190         /*
 191          * Kick the re-probe thread.  It may already be scheduled, but it is
 192          * safe to kick it again.
 193          */
 194         queue_work(system_unbound_wq, &deferred_probe_work);
 195 }
 196
 197 /**
 198  * device_block_probing() - Block/defer device's probes
 199  *
 200  *      It will disable probing of devices and defer their probes instead.
 201  */
 202 void device_block_probing(void)
 203 {
 204         defer_all_probes = true;
 205         /* sync with probes to avoid races. */
 206         wait_for_device_probe();
 207 }
 208
 209 /**
 210  * device_unblock_probing() - Unblock/enable device's probes
 211  *
 212  *      It will restore normal behavior and trigger re-probing of deferred
 213  * devices.
 214  */
 215 void device_unblock_probing(void)
 216 {
 217         defer_all_probes = false;
 218         driver_deferred_probe_trigger();
 219 }
 220
 221 /**
 222  * device_set_deferred_probe_reason() - Set defer probe reason message for device
 223  * @dev: the pointer to the struct device
 224  * @vaf: the pointer to va_format structure with message
 225  */
 226 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
 227 {
 228         const char *drv = dev_driver_string(dev);
 229         char *reason;
 230
 231         mutex_lock(&deferred_probe_mutex);
 232
 233         reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
 234         __device_set_deferred_probe_reason(dev, reason);
 235
 236         mutex_unlock(&deferred_probe_mutex);
 237 }
 238
 239 /*
 240  * deferred_devs_show() - Show the devices in the deferred probe pending list.
 241  */
 242 static int deferred_devs_show(struct seq_file *s, void *data)
 243 {
 244         struct device_private *curr;
 245
 246         mutex_lock(&deferred_probe_mutex);
 247
 248         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
 249                 seq_printf(s, "%s\t%s", dev_name(curr->device),
 250                            curr->device->p->deferred_probe_reason ?: "\n");
 251
 252         mutex_unlock(&deferred_probe_mutex);
 253
 254         return 0;
 255 }
 256 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 257
 258 int driver_deferred_probe_timeout;
 259 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
 260
 261 static int __init deferred_probe_timeout_setup(char *str)
 262 {
 263         int timeout;
 264
 265         if (!kstrtoint(str, 10, &timeout))
 266                 driver_deferred_probe_timeout = timeout;
 267         return 1;
 268 }
 269 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 270
 271 /**
 272  * driver_deferred_probe_check_state() - Check deferred probe state
 273  * @dev: device to check
 274  *
 275  * Return:
 276  * -ENODEV if initcalls have completed and modules are disabled.
 277  * -ETIMEDOUT if the deferred probe timeout was set and has expired
 278  *  and modules are enabled.
 279  * -EPROBE_DEFER in other cases.
 280  *
 281  * Drivers or subsystems can opt-in to calling this function instead of directly
 282  * returning -EPROBE_DEFER.
 283  */
 284 int driver_deferred_probe_check_state(struct device *dev)
 285 {
 286         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 287                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 288                 return -ENODEV;
 289         }
 290
 291         if (!driver_deferred_probe_timeout && initcalls_done) {
 292                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 293                 return -ETIMEDOUT;
 294         }
 295
 296         return -EPROBE_DEFER;
 297 }
 298 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
 299
 300 static void deferred_probe_timeout_work_func(struct work_struct *work)
 301 {
 302         struct device_private *p;
 303
 304         fw_devlink_drivers_done();
 305
 306         driver_deferred_probe_timeout = 0;
 307         driver_deferred_probe_trigger();
 308         flush_work(&deferred_probe_work);
 309
 310         mutex_lock(&deferred_probe_mutex);
 311         list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
 312                 dev_info(p->device, "deferred probe pending\n");
 313         mutex_unlock(&deferred_probe_mutex);
 314 }
 315 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 316
 317 /**
 318  * deferred_probe_initcall() - Enable probing of deferred devices
 319  *
 320  * We don't want to get in the way when the bulk of drivers are getting probed.
 321  * Instead, this initcall makes sure that deferred probing is delayed until
 322  * late_initcall time.
 323  */
 324 static int deferred_probe_initcall(void)
 325 {
 326         debugfs_create_file("devices_deferred", 0444, NULL, NULL,
 327                             &deferred_devs_fops);
 328
 329         driver_deferred_probe_enable = true;
 330         driver_deferred_probe_trigger();
 331         /* Sort as many dependencies as possible before exiting initcalls */
 332         flush_work(&deferred_probe_work);
 333         initcalls_done = true;
 334
 335         if (!IS_ENABLED(CONFIG_MODULES))
 336                 fw_devlink_drivers_done();
 337
 338         /*
 339          * Trigger deferred probe again, this time we won't defer anything
 340          * that is optional
 341          */
 342         driver_deferred_probe_trigger();
 343         flush_work(&deferred_probe_work);
 344
 345         if (driver_deferred_probe_timeout > 0) {
 346                 schedule_delayed_work(&deferred_probe_timeout_work,
 347                         driver_deferred_probe_timeout * HZ);
 348         }
 349         return 0;
 350 }
 351 late_initcall(deferred_probe_initcall);
 352
 353 static void __exit deferred_probe_exit(void)
 354 {
 355         debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
 356 }
 357 __exitcall(deferred_probe_exit);
 358
 359 /**
 360  * device_is_bound() - Check if device is bound to a driver
 361  * @dev: device to check
 362  *
 363  * Returns true if passed device has already finished probing successfully
 364  * against a driver.
 365  *
 366  * This function must be called with the device lock held.
 367  */
 368 bool device_is_bound(struct device *dev)
 369 {
 370         return dev->p && klist_node_attached(&dev->p->knode_driver);
 371 }
 372
 373 static void driver_bound(struct device *dev)
 374 {
 375         if (device_is_bound(dev)) {
 376                 pr_warn("%s: device %s already bound\n",
 377                         __func__, kobject_name(&dev->kobj));
 378                 return;
 379         }
 380
 381         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 382                  __func__, dev_name(dev));
 383
 384         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 385         device_links_driver_bound(dev);
 386
 387         device_pm_check_callbacks(dev);
 388
 389         /*
 390          * Make sure the device is no longer in one of the deferred lists and
 391          * kick off retrying all pending devices
 392          */
 393         driver_deferred_probe_del(dev);
 394         driver_deferred_probe_trigger();
 395
 396         if (dev->bus)
 397                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 398                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 399
 400         kobject_uevent(&dev->kobj, KOBJ_BIND);
 401 }
 402
 403 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 404                             const char *buf, size_t count)
 405 {
 406         device_lock(dev);
 407         dev->driver->coredump(dev);
 408         device_unlock(dev);
 409
 410         return count;
 411 }
 412 static DEVICE_ATTR_WO(coredump);
 413
 414 static int driver_sysfs_add(struct device *dev)
 415 {
 416         int ret;
 417
 418         if (dev->bus)
 419                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 420                                              BUS_NOTIFY_BIND_DRIVER, dev);
 421
 422         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 423                                 kobject_name(&dev->kobj));
 424         if (ret)
 425                 goto fail;
 426
 427         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 428                                 "driver");
 429         if (ret)
 430                 goto rm_dev;
 431
 432         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 433                 return 0;
 434
 435         ret = device_create_file(dev, &dev_attr_coredump);
 436         if (!ret)
 437                 return 0;
 438
 439         sysfs_remove_link(&dev->kobj, "driver");
 440
 441 rm_dev:
 442         sysfs_remove_link(&dev->driver->p->kobj,
 443                           kobject_name(&dev->kobj));
 444
 445 fail:
 446         return ret;
 447 }
 448
 449 static void driver_sysfs_remove(struct device *dev)
 450 {
 451         struct device_driver *drv = dev->driver;
 452
 453         if (drv) {
 454                 if (drv->coredump)
 455                         device_remove_file(dev, &dev_attr_coredump);
 456                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 457                 sysfs_remove_link(&dev->kobj, "driver");
 458         }
 459 }
 460
 461 /**
 462  * device_bind_driver - bind a driver to one device.
 463  * @dev: device.
 464  *
 465  * Allow manual attachment of a driver to a device.
 466  * Caller must have already set @dev->driver.
 467  *
 468  * Note that this does not modify the bus reference count.
 469  * Please verify that is accounted for before calling this.
 470  * (It is ok to call with no other effort from a driver's probe() method.)
 471  *
 472  * This function must be called with the device lock held.
 473  *
 474  * Callers should prefer to use device_driver_attach() instead.
 475  */
 476 int device_bind_driver(struct device *dev)
 477 {
 478         int ret;
 479
 480         ret = driver_sysfs_add(dev);
 481         if (!ret) {
 482                 device_links_force_bind(dev);
 483                 driver_bound(dev);
 484         }
 485         else if (dev->bus)
 486                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 487                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 488         return ret;
 489 }
 490 EXPORT_SYMBOL_GPL(device_bind_driver);
 491
 492 static atomic_t probe_count = ATOMIC_INIT(0);
 493 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 494
 495 static ssize_t state_synced_show(struct device *dev,
 496                                  struct device_attribute *attr, char *buf)
 497 {
 498         bool val;
 499
 500         device_lock(dev);
 501         val = dev->state_synced;
 502         device_unlock(dev);
 503
 504         return sysfs_emit(buf, "%u\n", val);
 505 }
 506 static DEVICE_ATTR_RO(state_synced);
 507
 508
 509 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 510 {
 511         int ret = 0;
 512
 513         if (dev->bus->probe)
 514                 ret = dev->bus->probe(dev);
 515         else if (drv->probe)
 516                 ret = drv->probe(dev);
 517
 518         switch (ret) {
 519         case 0:
 520                 break;
 521         case -EPROBE_DEFER:
 522                 /* Driver requested deferred probing */
 523                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 524                 break;
 525         case -ENODEV:
 526         case -ENXIO:
 527                 pr_debug("%s: probe of %s rejects match %d\n",
 528                          drv->name, dev_name(dev), ret);
 529                 break;
 530         default:
 531                 /* driver matched but the probe failed */
 532                 pr_warn("%s: probe of %s failed with error %d\n",
 533                         drv->name, dev_name(dev), ret);
 534                 break;
 535         }
 536
 537         return ret;
 538 }
 539
 540 static int really_probe(struct device *dev, struct device_driver *drv)
 541 {
 542         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 543                            !drv->suppress_bind_attrs;
 544         int ret;
 545
 546         if (defer_all_probes) {
 547                 /*
 548                  * Value of defer_all_probes can be set only by
 549                  * device_block_probing() which, in turn, will call
 550                  * wait_for_device_probe() right after that to avoid any races.
 551                  */
 552                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 553                 return -EPROBE_DEFER;
 554         }
 555
 556         ret = device_links_check_suppliers(dev);
 557         if (ret)
 558                 return ret;
 559
 560         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 561                  drv->bus->name, __func__, drv->name, dev_name(dev));
 562         if (!list_empty(&dev->devres_head)) {
 563                 dev_crit(dev, "Resources present before probing\n");
 564                 ret = -EBUSY;
 565                 goto done;
 566         }
 567
 568 re_probe:
 569         dev->driver = drv;
 570
 571         /* If using pinctrl, bind pins now before probing */
 572         ret = pinctrl_bind_pins(dev);
 573         if (ret)
 574                 goto pinctrl_bind_failed;
 575
 576         if (dev->bus->dma_configure) {
 577                 ret = dev->bus->dma_configure(dev);
 578                 if (ret)
 579                         goto probe_failed;
 580         }
 581
 582         ret = driver_sysfs_add(dev);
 583         if (ret) {
 584                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 585                        __func__, dev_name(dev));
 586                 goto probe_failed;
 587         }
 588
 589         if (dev->pm_domain && dev->pm_domain->activate) {
 590                 ret = dev->pm_domain->activate(dev);
 591                 if (ret)
 592                         goto probe_failed;
 593         }
 594
 595         ret = call_driver_probe(dev, drv);
 596         if (ret) {
 597                 /*
 598                  * Return probe errors as positive values so that the callers
 599                  * can distinguish them from other errors.
 600                  */
 601                 ret = -ret;
 602                 goto probe_failed;
 603         }
 604
 605         ret = device_add_groups(dev, drv->dev_groups);
 606         if (ret) {
 607                 dev_err(dev, "device_add_groups() failed\n");
 608                 goto dev_groups_failed;
 609         }
 610
 611         if (dev_has_sync_state(dev)) {
 612                 ret = device_create_file(dev, &dev_attr_state_synced);
 613                 if (ret) {
 614                         dev_err(dev, "state_synced sysfs add failed\n");
 615                         goto dev_sysfs_state_synced_failed;
 616                 }
 617         }
 618
 619         if (test_remove) {
 620                 test_remove = false;
 621
 622                 device_remove_file(dev, &dev_attr_state_synced);
 623                 device_remove_groups(dev, drv->dev_groups);
 624
 625                 if (dev->bus->remove)
 626                         dev->bus->remove(dev);
 627                 else if (drv->remove)
 628                         drv->remove(dev);
 629
 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
 641                 goto re_probe;
 642         }
 643
 644         pinctrl_init_done(dev);
 645
 646         if (dev->pm_domain && dev->pm_domain->sync)
 647                 dev->pm_domain->sync(dev);
 648
 649         driver_bound(dev);
 650         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 651                  drv->bus->name, __func__, dev_name(dev), drv->name);
 652         goto done;
 653
 654 dev_sysfs_state_synced_failed:
 655         device_remove_groups(dev, drv->dev_groups);
 656 dev_groups_failed:
 657         if (dev->bus->remove)
 658                 dev->bus->remove(dev);
 659         else if (drv->remove)
 660                 drv->remove(dev);
 661 probe_failed:
 662         if (dev->bus)
 663                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 664                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 665 pinctrl_bind_failed:
 666         device_links_no_driver(dev);
 667         devres_release_all(dev);
 668         arch_teardown_dma_ops(dev);
 669         kfree(dev->dma_range_map);
 670         dev->dma_range_map = NULL;
 671         driver_sysfs_remove(dev);
 672         dev->driver = NULL;
 673         dev_set_drvdata(dev, NULL);
 674         if (dev->pm_domain && dev->pm_domain->dismiss)
 675                 dev->pm_domain->dismiss(dev);
 676         pm_runtime_reinit(dev);
 677         dev_pm_set_driver_flags(dev, 0);
 678 done:
 679         return ret;
 680 }
 681
 682 /*
 683  * For initcall_debug, show the driver probe time.
 684  */
 685 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 686 {
 687         ktime_t calltime, rettime;
 688         int ret;
 689
 690         calltime = ktime_get();
 691         ret = really_probe(dev, drv);
 692         rettime = ktime_get();
 693         pr_debug("probe of %s returned %d after %lld usecs\n",
 694                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 695         return ret;
 696 }
 697
 698 /**
 699  * driver_probe_done
 700  * Determine if the probe sequence is finished or not.
 701  *
 702  * Should somehow figure out how to use a semaphore, not an atomic variable...
 703  */
 704 int driver_probe_done(void)
 705 {
 706         int local_probe_count = atomic_read(&probe_count);
 707
 708         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 709         if (local_probe_count)
 710                 return -EBUSY;
 711         return 0;
 712 }
 713
 714 /**
 715  * wait_for_device_probe
 716  * Wait for device probing to be completed.
 717  */
 718 void wait_for_device_probe(void)
 719 {
 720         /* wait for the deferred probe workqueue to finish */
 721         flush_work(&deferred_probe_work);
 722
 723         /* wait for the known devices to complete their probing */
 724         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 725         async_synchronize_full();
 726 }
 727 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 728
 729 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 730 {
 731         int ret = 0;
 732
 733         if (dev->p->dead || !device_is_registered(dev))
 734                 return -ENODEV;
 735         if (dev->driver)
 736                 return -EBUSY;
 737
 738         dev->can_match = true;
 739         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 740                  drv->bus->name, __func__, dev_name(dev), drv->name);
 741
 742         pm_runtime_get_suppliers(dev);
 743         if (dev->parent)
 744                 pm_runtime_get_sync(dev->parent);
 745
 746         pm_runtime_barrier(dev);
 747         if (initcall_debug)
 748                 ret = really_probe_debug(dev, drv);
 749         else
 750                 ret = really_probe(dev, drv);
 751         pm_request_idle(dev);
 752
 753         if (dev->parent)
 754                 pm_runtime_put(dev->parent);
 755
 756         pm_runtime_put_suppliers(dev);
 757         return ret;
 758 }
 759
 760 /**
 761  * driver_probe_device - attempt to bind device & driver together
 762  * @drv: driver to bind a device to
 763  * @dev: device to try to bind to the driver
 764  *
 765  * This function returns -ENODEV if the device is not registered, -EBUSY if it
 766  * already has a driver, 0 if the device is bound successfully and a positive
 767  * (inverted) error code for failures from the ->probe method.
 768  *
 769  * This function must be called with @dev lock held.  When called for a
 770  * USB interface, @dev->parent lock must be held as well.
 771  *
 772  * If the device has a parent, runtime-resume the parent before driver probing.
 773  */
 774 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 775 {
 776         int trigger_count = atomic_read(&deferred_trigger_count);
 777         int ret;
 778
 779         atomic_inc(&probe_count);
 780         ret = __driver_probe_device(drv, dev);
 781         if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
 782                 driver_deferred_probe_add(dev);
 783
 784                 /*
 785                  * Did a trigger occur while probing? Need to re-trigger if yes
 786                  */
 787                 if (trigger_count != atomic_read(&deferred_trigger_count) &&
 788                     !defer_all_probes)
 789                         driver_deferred_probe_trigger();
 790         }
 791         atomic_dec(&probe_count);
 792         wake_up_all(&probe_waitqueue);
 793         return ret;
 794 }
 795
 796 static inline bool cmdline_requested_async_probing(const char *drv_name)
 797 {
 798         return parse_option_str(async_probe_drv_names, drv_name);
 799 }
 800
 801 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 802 static int __init save_async_options(char *buf)
 803 {
 804         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 805                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 806
 807         strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 808         return 1;
 809 }
 810 __setup("driver_async_probe=", save_async_options);
 811
 812 bool driver_allows_async_probing(struct device_driver *drv)
 813 {
 814         switch (drv->probe_type) {
 815         case PROBE_PREFER_ASYNCHRONOUS:
 816                 return true;
 817
 818         case PROBE_FORCE_SYNCHRONOUS:
 819                 return false;
 820
 821         default:
 822                 if (cmdline_requested_async_probing(drv->name))
 823                         return true;
 824
 825                 if (module_requested_async_probing(drv->owner))
 826                         return true;
 827
 828                 return false;
 829         }
 830 }
 831
 832 struct device_attach_data {
 833         struct device *dev;
 834
 835         /*
 836          * Indicates whether we are are considering asynchronous probing or
 837          * not. Only initial binding after device or driver registration
 838          * (including deferral processing) may be done asynchronously, the
 839          * rest is always synchronous, as we expect it is being done by
 840          * request from userspace.
 841          */
 842         bool check_async;
 843
 844         /*
 845          * Indicates if we are binding synchronous or asynchronous drivers.
 846          * When asynchronous probing is enabled we'll execute 2 passes
 847          * over drivers: first pass doing synchronous probing and second
 848          * doing asynchronous probing (if synchronous did not succeed -
 849          * most likely because there was no driver requiring synchronous
 850          * probing - and we found asynchronous driver during first pass).
 851          * The 2 passes are done because we can't shoot asynchronous
 852          * probe for given device and driver from bus_for_each_drv() since
 853          * driver pointer is not guaranteed to stay valid once
 854          * bus_for_each_drv() iterates to the next driver on the bus.
 855          */
 856         bool want_async;
 857
 858         /*
 859          * We'll set have_async to 'true' if, while scanning for matching
 860          * driver, we'll encounter one that requests asynchronous probing.
 861          */
 862         bool have_async;
 863 };
 864
 865 static int __device_attach_driver(struct device_driver *drv, void *_data)
 866 {
 867         struct device_attach_data *data = _data;
 868         struct device *dev = data->dev;
 869         bool async_allowed;
 870         int ret;
 871
 872         ret = driver_match_device(drv, dev);
 873         if (ret == 0) {
 874                 /* no match */
 875                 return 0;
 876         } else if (ret == -EPROBE_DEFER) {
 877                 dev_dbg(dev, "Device match requests probe deferral\n");
 878                 dev->can_match = true;
 879                 driver_deferred_probe_add(dev);
 880                 /*
 881                  * Device can't match with a driver right now, so don't attempt
 882                  * to match or bind with other drivers on the bus.
 883                  */
 884                 return ret;
 885         } else if (ret < 0) {
 886                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 887                 return ret;
 888         } /* ret > 0 means positive match */
 889
 890         async_allowed = driver_allows_async_probing(drv);
 891
 892         if (async_allowed)
 893                 data->have_async = true;
 894
 895         if (data->check_async && async_allowed != data->want_async)
 896                 return 0;
 897
 898         /*
 899          * Ignore errors returned by ->probe so that the next driver can try
 900          * its luck.
 901          */
 902         ret = driver_probe_device(drv, dev);
 903         if (ret < 0)
 904                 return ret;
 905         return ret == 0;
 906 }
 907
 908 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 909 {
 910         struct device *dev = _dev;
 911         struct device_attach_data data = {
 912                 .dev            = dev,
 913                 .check_async    = true,
 914                 .want_async     = true,
 915         };
 916
 917         device_lock(dev);
 918
 919         /*
 920          * Check if device has already been removed or claimed. This may
 921          * happen with driver loading, device discovery/registration,
 922          * and deferred probe processing happens all at once with
 923          * multiple threads.
 924          */
 925         if (dev->p->dead || dev->driver)
 926                 goto out_unlock;
 927
 928         if (dev->parent)
 929                 pm_runtime_get_sync(dev->parent);
 930
 931         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 932         dev_dbg(dev, "async probe completed\n");
 933
 934         pm_request_idle(dev);
 935
 936         if (dev->parent)
 937                 pm_runtime_put(dev->parent);
 938 out_unlock:
 939         device_unlock(dev);
 940
 941         put_device(dev);
 942 }
 943
 944 static int __device_attach(struct device *dev, bool allow_async)
 945 {
 946         int ret = 0;
 947         bool async = false;
 948
 949         device_lock(dev);
 950         if (dev->p->dead) {
 951                 goto out_unlock;
 952         } else if (dev->driver) {
 953                 if (device_is_bound(dev)) {
 954                         ret = 1;
 955                         goto out_unlock;
 956                 }
 957                 ret = device_bind_driver(dev);
 958                 if (ret == 0)
 959                         ret = 1;
 960                 else {
 961                         dev->driver = NULL;
 962                         ret = 0;
 963                 }
 964         } else {
 965                 struct device_attach_data data = {
 966                         .dev = dev,
 967                         .check_async = allow_async,
 968                         .want_async = false,
 969                 };
 970
 971                 if (dev->parent)
 972                         pm_runtime_get_sync(dev->parent);
 973
 974                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 975                                         __device_attach_driver);
 976                 if (!ret && allow_async && data.have_async) {
 977                         /*
 978                          * If we could not find appropriate driver
 979                          * synchronously and we are allowed to do
 980                          * async probes and there are drivers that
 981                          * want to probe asynchronously, we'll
 982                          * try them.
 983                          */
 984                         dev_dbg(dev, "scheduling asynchronous probe\n");
 985                         get_device(dev);
 986                         async = true;
 987                 } else {
 988                         pm_request_idle(dev);
 989                 }
 990
 991                 if (dev->parent)
 992                         pm_runtime_put(dev->parent);
 993         }
 994 out_unlock:
 995         device_unlock(dev);
 996         if (async)
 997                 async_schedule_dev(__device_attach_async_helper, dev);
 998         return ret;
 999 }
1000
1001 /**
1002  * device_attach - try to attach device to a driver.
1003  * @dev: device.
1004  *
1005  * Walk the list of drivers that the bus has and call
1006  * driver_probe_device() for each pair. If a compatible
1007  * pair is found, break out and return.
1008  *
1009  * Returns 1 if the device was bound to a driver;
1010  * 0 if no matching driver was found;
1011  * -ENODEV if the device is not registered.
1012  *
1013  * When called for a USB interface, @dev->parent lock must be held.
1014  */
1015 int device_attach(struct device *dev)
1016 {
1017         return __device_attach(dev, false);
1018 }
1019 EXPORT_SYMBOL_GPL(device_attach);
1020
1021 void device_initial_probe(struct device *dev)
1022 {
1023         __device_attach(dev, true);
1024 }
1025
1026 /*
1027  * __device_driver_lock - acquire locks needed to manipulate dev->drv
1028  * @dev: Device we will update driver info for
1029  * @parent: Parent device. Needed if the bus requires parent lock
1030  *
1031  * This function will take the required locks for manipulating dev->drv.
1032  * Normally this will just be the @dev lock, but when called for a USB
1033  * interface, @parent lock will be held as well.
1034  */
1035 static void __device_driver_lock(struct device *dev, struct device *parent)
1036 {
1037         if (parent && dev->bus->need_parent_lock)
1038                 device_lock(parent);
1039         device_lock(dev);
1040 }
1041
1042 /*
1043  * __device_driver_unlock - release locks needed to manipulate dev->drv
1044  * @dev: Device we will update driver info for
1045  * @parent: Parent device. Needed if the bus requires parent lock
1046  *
1047  * This function will release the required locks for manipulating dev->drv.
1048  * Normally this will just be the the @dev lock, but when called for a
1049  * USB interface, @parent lock will be released as well.
1050  */
1051 static void __device_driver_unlock(struct device *dev, struct device *parent)
1052 {
1053         device_unlock(dev);
1054         if (parent && dev->bus->need_parent_lock)
1055                 device_unlock(parent);
1056 }
1057
1058 /**
1059  * device_driver_attach - attach a specific driver to a specific device
1060  * @drv: Driver to attach
1061  * @dev: Device to attach it to
1062  *
1063  * Manually attach driver to a device. Will acquire both @dev lock and
1064  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1065  */
1066 int device_driver_attach(struct device_driver *drv, struct device *dev)
1067 {
1068         int ret;
1069
1070         __device_driver_lock(dev, dev->parent);
1071         ret = __driver_probe_device(drv, dev);
1072         __device_driver_unlock(dev, dev->parent);
1073
1074         /* also return probe errors as normal negative errnos */
1075         if (ret > 0)
1076                 ret = -ret;
1077         if (ret == -EPROBE_DEFER)
1078                 return -EAGAIN;
1079         return ret;
1080 }
1081 EXPORT_SYMBOL_GPL(device_driver_attach);
1082
1083 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1084 {
1085         struct device *dev = _dev;
1086         struct device_driver *drv;
1087         int ret;
1088
1089         __device_driver_lock(dev, dev->parent);
1090         drv = dev->p->async_driver;
1091         ret = driver_probe_device(drv, dev);
1092         __device_driver_unlock(dev, dev->parent);
1093
1094         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1095
1096         put_device(dev);
1097 }
1098
1099 static int __driver_attach(struct device *dev, void *data)
1100 {
1101         struct device_driver *drv = data;
1102         bool async = false;
1103         int ret;
1104
1105         /*
1106          * Lock device and try to bind to it. We drop the error
1107          * here and always return 0, because we need to keep trying
1108          * to bind to devices and some drivers will return an error
1109          * simply if it didn't support the device.
1110          *
1111          * driver_probe_device() will spit a warning if there
1112          * is an error.
1113          */
1114
1115         ret = driver_match_device(drv, dev);
1116         if (ret == 0) {
1117                 /* no match */
1118                 return 0;
1119         } else if (ret == -EPROBE_DEFER) {
1120                 dev_dbg(dev, "Device match requests probe deferral\n");
1121                 dev->can_match = true;
1122                 driver_deferred_probe_add(dev);
1123                 /*
1124                  * Driver could not match with device, but may match with
1125                  * another device on the bus.
1126                  */
1127                 return 0;
1128         } else if (ret < 0) {
1129                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1130                 /*
1131                  * Driver could not match with device, but may match with
1132                  * another device on the bus.
1133                  */
1134                 return 0;
1135         } /* ret > 0 means positive match */
1136
1137         if (driver_allows_async_probing(drv)) {
1138                 /*
1139                  * Instead of probing the device synchronously we will
1140                  * probe it asynchronously to allow for more parallelism.
1141                  *
1142                  * We only take the device lock here in order to guarantee
1143                  * that the dev->driver and async_driver fields are protected
1144                  */
1145                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1146                 device_lock(dev);
1147                 if (!dev->driver) {
1148                         get_device(dev);
1149                         dev->p->async_driver = drv;
1150                         async = true;
1151                 }
1152                 device_unlock(dev);
1153                 if (async)
1154                         async_schedule_dev(__driver_attach_async_helper, dev);
1155                 return 0;
1156         }
1157
1158         __device_driver_lock(dev, dev->parent);
1159         driver_probe_device(drv, dev);
1160         __device_driver_unlock(dev, dev->parent);
1161
1162         return 0;
1163 }
1164
1165 /**
1166  * driver_attach - try to bind driver to devices.
1167  * @drv: driver.
1168  *
1169  * Walk the list of devices that the bus has on it and try to
1170  * match the driver with each one.  If driver_probe_device()
1171  * returns 0 and the @dev->driver is set, we've found a
1172  * compatible pair.
1173  */
1174 int driver_attach(struct device_driver *drv)
1175 {
1176         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1177 }
1178 EXPORT_SYMBOL_GPL(driver_attach);
1179
1180 /*
1181  * __device_release_driver() must be called with @dev lock held.
1182  * When called for a USB interface, @dev->parent lock must be held as well.
1183  */
1184 static void __device_release_driver(struct device *dev, struct device *parent)
1185 {
1186         struct device_driver *drv;
1187
1188         drv = dev->driver;
1189         if (drv) {
1190                 pm_runtime_get_sync(dev);
1191
1192                 while (device_links_busy(dev)) {
1193                         __device_driver_unlock(dev, parent);
1194
1195                         device_links_unbind_consumers(dev);
1196
1197                         __device_driver_lock(dev, parent);
1198                         /*
1199                          * A concurrent invocation of the same function might
1200                          * have released the driver successfully while this one
1201                          * was waiting, so check for that.
1202                          */
1203                         if (dev->driver != drv) {
1204                                 pm_runtime_put(dev);
1205                                 return;
1206                         }
1207                 }
1208
1209                 driver_sysfs_remove(dev);
1210
1211                 if (dev->bus)
1212                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1213                                                      BUS_NOTIFY_UNBIND_DRIVER,
1214                                                      dev);
1215
1216                 pm_runtime_put_sync(dev);
1217
1218                 device_remove_file(dev, &dev_attr_state_synced);
1219                 device_remove_groups(dev, drv->dev_groups);
1220
1221                 if (dev->bus && dev->bus->remove)
1222                         dev->bus->remove(dev);
1223                 else if (drv->remove)
1224                         drv->remove(dev);
1225
1226                 device_links_driver_cleanup(dev);
1227
1228                 devres_release_all(dev);
1229                 arch_teardown_dma_ops(dev);
1230                 kfree(dev->dma_range_map);
1231                 dev->dma_range_map = NULL;
1232                 dev->driver = NULL;
1233                 dev_set_drvdata(dev, NULL);
1234                 if (dev->pm_domain && dev->pm_domain->dismiss)
1235                         dev->pm_domain->dismiss(dev);
1236                 pm_runtime_reinit(dev);
1237                 dev_pm_set_driver_flags(dev, 0);
1238
1239                 klist_remove(&dev->p->knode_driver);
1240                 device_pm_check_callbacks(dev);
1241                 if (dev->bus)
1242                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1243                                                      BUS_NOTIFY_UNBOUND_DRIVER,
1244                                                      dev);
1245
1246                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1247         }
1248 }
1249
1250 void device_release_driver_internal(struct device *dev,
1251                                     struct device_driver *drv,
1252                                     struct device *parent)
1253 {
1254         __device_driver_lock(dev, parent);
1255
1256         if (!drv || drv == dev->driver)
1257                 __device_release_driver(dev, parent);
1258
1259         __device_driver_unlock(dev, parent);
1260 }
1261
1262 /**
1263  * device_release_driver - manually detach device from driver.
1264  * @dev: device.
1265  *
1266  * Manually detach device from driver.
1267  * When called for a USB interface, @dev->parent lock must be held.
1268  *
1269  * If this function is to be called with @dev->parent lock held, ensure that
1270  * the device's consumers are unbound in advance or that their locks can be
1271  * acquired under the @dev->parent lock.
1272  */
1273 void device_release_driver(struct device *dev)
1274 {
1275         /*
1276          * If anyone calls device_release_driver() recursively from
1277          * within their ->remove callback for the same device, they
1278          * will deadlock right here.
1279          */
1280         device_release_driver_internal(dev, NULL, NULL);
1281 }
1282 EXPORT_SYMBOL_GPL(device_release_driver);
1283
1284 /**
1285  * device_driver_detach - detach driver from a specific device
1286  * @dev: device to detach driver from
1287  *
1288  * Detach driver from device. Will acquire both @dev lock and @dev->parent
1289  * lock if needed.
1290  */
1291 void device_driver_detach(struct device *dev)
1292 {
1293         device_release_driver_internal(dev, NULL, dev->parent);
1294 }
1295
1296 /**
1297  * driver_detach - detach driver from all devices it controls.
1298  * @drv: driver.
1299  */
1300 void driver_detach(struct device_driver *drv)
1301 {
1302         struct device_private *dev_prv;
1303         struct device *dev;
1304
1305         if (driver_allows_async_probing(drv))
1306                 async_synchronize_full();
1307
1308         for (;;) {
1309                 spin_lock(&drv->p->klist_devices.k_lock);
1310                 if (list_empty(&drv->p->klist_devices.k_list)) {
1311                         spin_unlock(&drv->p->klist_devices.k_lock);
1312                         break;
1313                 }
1314                 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1315                                      struct device_private,
1316                                      knode_driver.n_node);
1317                 dev = dev_prv->device;
1318                 get_device(dev);
1319                 spin_unlock(&drv->p->klist_devices.k_lock);
1320                 device_release_driver_internal(dev, drv, dev->parent);
1321                 put_device(dev);
1322         }
1323 }