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 <[email protected]>
  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 static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue);
 261
 262 static int __init deferred_probe_timeout_setup(char *str)
 263 {
 264         int timeout;
 265
 266         if (!kstrtoint(str, 10, &timeout))
 267                 driver_deferred_probe_timeout = timeout;
 268         return 1;
 269 }
 270 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 271
 272 /**
 273  * driver_deferred_probe_check_state() - Check deferred probe state
 274  * @dev: device to check
 275  *
 276  * Return:
 277  * -ENODEV if initcalls have completed and modules are disabled.
 278  * -ETIMEDOUT if the deferred probe timeout was set and has expired
 279  *  and modules are enabled.
 280  * -EPROBE_DEFER in other cases.
 281  *
 282  * Drivers or subsystems can opt-in to calling this function instead of directly
 283  * returning -EPROBE_DEFER.
 284  */
 285 int driver_deferred_probe_check_state(struct device *dev)
 286 {
 287         if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
 288                 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
 289                 return -ENODEV;
 290         }
 291
 292         if (!driver_deferred_probe_timeout && initcalls_done) {
 293                 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
 294                 return -ETIMEDOUT;
 295         }
 296
 297         return -EPROBE_DEFER;
 298 }
 299
 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         wake_up_all(&probe_timeout_waitqueue);
 315 }
 316 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 317
 318 /**
 319  * deferred_probe_initcall() - Enable probing of deferred devices
 320  *
 321  * We don't want to get in the way when the bulk of drivers are getting probed.
 322  * Instead, this initcall makes sure that deferred probing is delayed until
 323  * late_initcall time.
 324  */
 325 static int deferred_probe_initcall(void)
 326 {
 327         debugfs_create_file("devices_deferred", 0444, NULL, NULL,
 328                             &deferred_devs_fops);
 329
 330         driver_deferred_probe_enable = true;
 331         driver_deferred_probe_trigger();
 332         /* Sort as many dependencies as possible before exiting initcalls */
 333         flush_work(&deferred_probe_work);
 334         initcalls_done = true;
 335
 336         if (!IS_ENABLED(CONFIG_MODULES))
 337                 fw_devlink_drivers_done();
 338
 339         /*
 340          * Trigger deferred probe again, this time we won't defer anything
 341          * that is optional
 342          */
 343         driver_deferred_probe_trigger();
 344         flush_work(&deferred_probe_work);
 345
 346         if (driver_deferred_probe_timeout > 0) {
 347                 schedule_delayed_work(&deferred_probe_timeout_work,
 348                         driver_deferred_probe_timeout * HZ);
 349         }
 350         return 0;
 351 }
 352 late_initcall(deferred_probe_initcall);
 353
 354 static void __exit deferred_probe_exit(void)
 355 {
 356         debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
 357 }
 358 __exitcall(deferred_probe_exit);
 359
 360 /**
 361  * device_is_bound() - Check if device is bound to a driver
 362  * @dev: device to check
 363  *
 364  * Returns true if passed device has already finished probing successfully
 365  * against a driver.
 366  *
 367  * This function must be called with the device lock held.
 368  */
 369 bool device_is_bound(struct device *dev)
 370 {
 371         return dev->p && klist_node_attached(&dev->p->knode_driver);
 372 }
 373
 374 static void driver_bound(struct device *dev)
 375 {
 376         if (device_is_bound(dev)) {
 377                 pr_warn("%s: device %s already bound\n",
 378                         __func__, kobject_name(&dev->kobj));
 379                 return;
 380         }
 381
 382         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
 383                  __func__, dev_name(dev));
 384
 385         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 386         device_links_driver_bound(dev);
 387
 388         device_pm_check_callbacks(dev);
 389
 390         /*
 391          * Make sure the device is no longer in one of the deferred lists and
 392          * kick off retrying all pending devices
 393          */
 394         driver_deferred_probe_del(dev);
 395         driver_deferred_probe_trigger();
 396
 397         if (dev->bus)
 398                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 399                                              BUS_NOTIFY_BOUND_DRIVER, dev);
 400
 401         kobject_uevent(&dev->kobj, KOBJ_BIND);
 402 }
 403
 404 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
 405                             const char *buf, size_t count)
 406 {
 407         device_lock(dev);
 408         dev->driver->coredump(dev);
 409         device_unlock(dev);
 410
 411         return count;
 412 }
 413 static DEVICE_ATTR_WO(coredump);
 414
 415 static int driver_sysfs_add(struct device *dev)
 416 {
 417         int ret;
 418
 419         if (dev->bus)
 420                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 421                                              BUS_NOTIFY_BIND_DRIVER, dev);
 422
 423         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 424                                 kobject_name(&dev->kobj));
 425         if (ret)
 426                 goto fail;
 427
 428         ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 429                                 "driver");
 430         if (ret)
 431                 goto rm_dev;
 432
 433         if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
 434                 return 0;
 435
 436         ret = device_create_file(dev, &dev_attr_coredump);
 437         if (!ret)
 438                 return 0;
 439
 440         sysfs_remove_link(&dev->kobj, "driver");
 441
 442 rm_dev:
 443         sysfs_remove_link(&dev->driver->p->kobj,
 444                           kobject_name(&dev->kobj));
 445
 446 fail:
 447         return ret;
 448 }
 449
 450 static void driver_sysfs_remove(struct device *dev)
 451 {
 452         struct device_driver *drv = dev->driver;
 453
 454         if (drv) {
 455                 if (drv->coredump)
 456                         device_remove_file(dev, &dev_attr_coredump);
 457                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 458                 sysfs_remove_link(&dev->kobj, "driver");
 459         }
 460 }
 461
 462 /**
 463  * device_bind_driver - bind a driver to one device.
 464  * @dev: device.
 465  *
 466  * Allow manual attachment of a driver to a device.
 467  * Caller must have already set @dev->driver.
 468  *
 469  * Note that this does not modify the bus reference count.
 470  * Please verify that is accounted for before calling this.
 471  * (It is ok to call with no other effort from a driver's probe() method.)
 472  *
 473  * This function must be called with the device lock held.
 474  */
 475 int device_bind_driver(struct device *dev)
 476 {
 477         int ret;
 478
 479         ret = driver_sysfs_add(dev);
 480         if (!ret) {
 481                 device_links_force_bind(dev);
 482                 driver_bound(dev);
 483         }
 484         else if (dev->bus)
 485                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 486                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 487         return ret;
 488 }
 489 EXPORT_SYMBOL_GPL(device_bind_driver);
 490
 491 static atomic_t probe_count = ATOMIC_INIT(0);
 492 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 493
 494 static void driver_deferred_probe_add_trigger(struct device *dev,
 495                                               int local_trigger_count)
 496 {
 497         driver_deferred_probe_add(dev);
 498         /* Did a trigger occur while probing? Need to re-trigger if yes */
 499         if (local_trigger_count != atomic_read(&deferred_trigger_count))
 500                 driver_deferred_probe_trigger();
 501 }
 502
 503 static ssize_t state_synced_show(struct device *dev,
 504                                  struct device_attribute *attr, char *buf)
 505 {
 506         bool val;
 507
 508         device_lock(dev);
 509         val = dev->state_synced;
 510         device_unlock(dev);
 511
 512         return sysfs_emit(buf, "%u\n", val);
 513 }
 514 static DEVICE_ATTR_RO(state_synced);
 515
 516 static int really_probe(struct device *dev, struct device_driver *drv)
 517 {
 518         int ret = -EPROBE_DEFER;
 519         int local_trigger_count = atomic_read(&deferred_trigger_count);
 520         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 521                            !drv->suppress_bind_attrs;
 522
 523         if (defer_all_probes) {
 524                 /*
 525                  * Value of defer_all_probes can be set only by
 526                  * device_block_probing() which, in turn, will call
 527                  * wait_for_device_probe() right after that to avoid any races.
 528                  */
 529                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
 530                 driver_deferred_probe_add(dev);
 531                 return ret;
 532         }
 533
 534         ret = device_links_check_suppliers(dev);
 535         if (ret == -EPROBE_DEFER)
 536                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 537         if (ret)
 538                 return ret;
 539
 540         atomic_inc(&probe_count);
 541         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 542                  drv->bus->name, __func__, drv->name, dev_name(dev));
 543         if (!list_empty(&dev->devres_head)) {
 544                 dev_crit(dev, "Resources present before probing\n");
 545                 ret = -EBUSY;
 546                 goto done;
 547         }
 548
 549 re_probe:
 550         dev->driver = drv;
 551
 552         /* If using pinctrl, bind pins now before probing */
 553         ret = pinctrl_bind_pins(dev);
 554         if (ret)
 555                 goto pinctrl_bind_failed;
 556
 557         if (dev->bus->dma_configure) {
 558                 ret = dev->bus->dma_configure(dev);
 559                 if (ret)
 560                         goto probe_failed;
 561         }
 562
 563         if (driver_sysfs_add(dev)) {
 564                 pr_err("%s: driver_sysfs_add(%s) failed\n",
 565                        __func__, dev_name(dev));
 566                 goto probe_failed;
 567         }
 568
 569         if (dev->pm_domain && dev->pm_domain->activate) {
 570                 ret = dev->pm_domain->activate(dev);
 571                 if (ret)
 572                         goto probe_failed;
 573         }
 574
 575         if (dev->bus->probe) {
 576                 ret = dev->bus->probe(dev);
 577                 if (ret)
 578                         goto probe_failed;
 579         } else if (drv->probe) {
 580                 ret = drv->probe(dev);
 581                 if (ret)
 582                         goto probe_failed;
 583         }
 584
 585         if (device_add_groups(dev, drv->dev_groups)) {
 586                 dev_err(dev, "device_add_groups() failed\n");
 587                 goto dev_groups_failed;
 588         }
 589
 590         if (dev_has_sync_state(dev) &&
 591             device_create_file(dev, &dev_attr_state_synced)) {
 592                 dev_err(dev, "state_synced sysfs add failed\n");
 593                 goto dev_sysfs_state_synced_failed;
 594         }
 595
 596         if (test_remove) {
 597                 test_remove = false;
 598
 599                 device_remove_file(dev, &dev_attr_state_synced);
 600                 device_remove_groups(dev, drv->dev_groups);
 601
 602                 if (dev->bus->remove)
 603                         dev->bus->remove(dev);
 604                 else if (drv->remove)
 605                         drv->remove(dev);
 606
 607                 devres_release_all(dev);
 608                 driver_sysfs_remove(dev);
 609                 dev->driver = NULL;
 610                 dev_set_drvdata(dev, NULL);
 611                 if (dev->pm_domain && dev->pm_domain->dismiss)
 612                         dev->pm_domain->dismiss(dev);
 613                 pm_runtime_reinit(dev);
 614
 615                 goto re_probe;
 616         }
 617
 618         pinctrl_init_done(dev);
 619
 620         if (dev->pm_domain && dev->pm_domain->sync)
 621                 dev->pm_domain->sync(dev);
 622
 623         driver_bound(dev);
 624         ret = 1;
 625         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 626                  drv->bus->name, __func__, dev_name(dev), drv->name);
 627         goto done;
 628
 629 dev_sysfs_state_synced_failed:
 630         device_remove_groups(dev, drv->dev_groups);
 631 dev_groups_failed:
 632         if (dev->bus->remove)
 633                 dev->bus->remove(dev);
 634         else if (drv->remove)
 635                 drv->remove(dev);
 636 probe_failed:
 637         kfree(dev->dma_range_map);
 638         dev->dma_range_map = NULL;
 639         if (dev->bus)
 640                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 641                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 642 pinctrl_bind_failed:
 643         device_links_no_driver(dev);
 644         devres_release_all(dev);
 645         arch_teardown_dma_ops(dev);
 646         driver_sysfs_remove(dev);
 647         dev->driver = NULL;
 648         dev_set_drvdata(dev, NULL);
 649         if (dev->pm_domain && dev->pm_domain->dismiss)
 650                 dev->pm_domain->dismiss(dev);
 651         pm_runtime_reinit(dev);
 652         dev_pm_set_driver_flags(dev, 0);
 653
 654         switch (ret) {
 655         case -EPROBE_DEFER:
 656                 /* Driver requested deferred probing */
 657                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 658                 driver_deferred_probe_add_trigger(dev, local_trigger_count);
 659                 break;
 660         case -ENODEV:
 661         case -ENXIO:
 662                 pr_debug("%s: probe of %s rejects match %d\n",
 663                          drv->name, dev_name(dev), ret);
 664                 break;
 665         default:
 666                 /* driver matched but the probe failed */
 667                 pr_warn("%s: probe of %s failed with error %d\n",
 668                         drv->name, dev_name(dev), ret);
 669         }
 670         /*
 671          * Ignore errors returned by ->probe so that the next driver can try
 672          * its luck.
 673          */
 674         ret = 0;
 675 done:
 676         atomic_dec(&probe_count);
 677         wake_up_all(&probe_waitqueue);
 678         return ret;
 679 }
 680
 681 /*
 682  * For initcall_debug, show the driver probe time.
 683  */
 684 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 685 {
 686         ktime_t calltime, rettime;
 687         int ret;
 688
 689         calltime = ktime_get();
 690         ret = really_probe(dev, drv);
 691         rettime = ktime_get();
 692         pr_debug("probe of %s returned %d after %lld usecs\n",
 693                  dev_name(dev), ret, ktime_us_delta(rettime, calltime));
 694         return ret;
 695 }
 696
 697 /**
 698  * driver_probe_done
 699  * Determine if the probe sequence is finished or not.
 700  *
 701  * Should somehow figure out how to use a semaphore, not an atomic variable...
 702  */
 703 int driver_probe_done(void)
 704 {
 705         int local_probe_count = atomic_read(&probe_count);
 706
 707         pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
 708         if (local_probe_count)
 709                 return -EBUSY;
 710         return 0;
 711 }
 712
 713 /**
 714  * wait_for_device_probe
 715  * Wait for device probing to be completed.
 716  */
 717 void wait_for_device_probe(void)
 718 {
 719         /* wait for probe timeout */
 720         wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout);
 721
 722         /* wait for the deferred probe workqueue to finish */
 723         flush_work(&deferred_probe_work);
 724
 725         /* wait for the known devices to complete their probing */
 726         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 727         async_synchronize_full();
 728 }
 729 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 730
 731 /**
 732  * driver_probe_device - attempt to bind device & driver together
 733  * @drv: driver to bind a device to
 734  * @dev: device to try to bind to the driver
 735  *
 736  * This function returns -ENODEV if the device is not registered,
 737  * 1 if the device is bound successfully and 0 otherwise.
 738  *
 739  * This function must be called with @dev lock held.  When called for a
 740  * USB interface, @dev->parent lock must be held as well.
 741  *
 742  * If the device has a parent, runtime-resume the parent before driver probing.
 743  */
 744 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 745 {
 746         int ret = 0;
 747
 748         if (!device_is_registered(dev))
 749                 return -ENODEV;
 750
 751         dev->can_match = true;
 752         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 753                  drv->bus->name, __func__, dev_name(dev), drv->name);
 754
 755         pm_runtime_get_suppliers(dev);
 756         if (dev->parent)
 757                 pm_runtime_get_sync(dev->parent);
 758
 759         pm_runtime_barrier(dev);
 760         if (initcall_debug)
 761                 ret = really_probe_debug(dev, drv);
 762         else
 763                 ret = really_probe(dev, drv);
 764         pm_request_idle(dev);
 765
 766         if (dev->parent)
 767                 pm_runtime_put(dev->parent);
 768
 769         pm_runtime_put_suppliers(dev);
 770         return ret;
 771 }
 772
 773 static inline bool cmdline_requested_async_probing(const char *drv_name)
 774 {
 775         return parse_option_str(async_probe_drv_names, drv_name);
 776 }
 777
 778 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 779 static int __init save_async_options(char *buf)
 780 {
 781         if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
 782                 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 783
 784         strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
 785         return 0;
 786 }
 787 __setup("driver_async_probe=", save_async_options);
 788
 789 bool driver_allows_async_probing(struct device_driver *drv)
 790 {
 791         switch (drv->probe_type) {
 792         case PROBE_PREFER_ASYNCHRONOUS:
 793                 return true;
 794
 795         case PROBE_FORCE_SYNCHRONOUS:
 796                 return false;
 797
 798         default:
 799                 if (cmdline_requested_async_probing(drv->name))
 800                         return true;
 801
 802                 if (module_requested_async_probing(drv->owner))
 803                         return true;
 804
 805                 return false;
 806         }
 807 }
 808
 809 struct device_attach_data {
 810         struct device *dev;
 811
 812         /*
 813          * Indicates whether we are are considering asynchronous probing or
 814          * not. Only initial binding after device or driver registration
 815          * (including deferral processing) may be done asynchronously, the
 816          * rest is always synchronous, as we expect it is being done by
 817          * request from userspace.
 818          */
 819         bool check_async;
 820
 821         /*
 822          * Indicates if we are binding synchronous or asynchronous drivers.
 823          * When asynchronous probing is enabled we'll execute 2 passes
 824          * over drivers: first pass doing synchronous probing and second
 825          * doing asynchronous probing (if synchronous did not succeed -
 826          * most likely because there was no driver requiring synchronous
 827          * probing - and we found asynchronous driver during first pass).
 828          * The 2 passes are done because we can't shoot asynchronous
 829          * probe for given device and driver from bus_for_each_drv() since
 830          * driver pointer is not guaranteed to stay valid once
 831          * bus_for_each_drv() iterates to the next driver on the bus.
 832          */
 833         bool want_async;
 834
 835         /*
 836          * We'll set have_async to 'true' if, while scanning for matching
 837          * driver, we'll encounter one that requests asynchronous probing.
 838          */
 839         bool have_async;
 840 };
 841
 842 static int __device_attach_driver(struct device_driver *drv, void *_data)
 843 {
 844         struct device_attach_data *data = _data;
 845         struct device *dev = data->dev;
 846         bool async_allowed;
 847         int ret;
 848
 849         ret = driver_match_device(drv, dev);
 850         if (ret == 0) {
 851                 /* no match */
 852                 return 0;
 853         } else if (ret == -EPROBE_DEFER) {
 854                 dev_dbg(dev, "Device match requests probe deferral\n");
 855                 dev->can_match = true;
 856                 driver_deferred_probe_add(dev);
 857         } else if (ret < 0) {
 858                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
 859                 return ret;
 860         } /* ret > 0 means positive match */
 861
 862         async_allowed = driver_allows_async_probing(drv);
 863
 864         if (async_allowed)
 865                 data->have_async = true;
 866
 867         if (data->check_async && async_allowed != data->want_async)
 868                 return 0;
 869
 870         return driver_probe_device(drv, dev);
 871 }
 872
 873 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
 874 {
 875         struct device *dev = _dev;
 876         struct device_attach_data data = {
 877                 .dev            = dev,
 878                 .check_async    = true,
 879                 .want_async     = true,
 880         };
 881
 882         device_lock(dev);
 883
 884         /*
 885          * Check if device has already been removed or claimed. This may
 886          * happen with driver loading, device discovery/registration,
 887          * and deferred probe processing happens all at once with
 888          * multiple threads.
 889          */
 890         if (dev->p->dead || dev->driver)
 891                 goto out_unlock;
 892
 893         if (dev->parent)
 894                 pm_runtime_get_sync(dev->parent);
 895
 896         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
 897         dev_dbg(dev, "async probe completed\n");
 898
 899         pm_request_idle(dev);
 900
 901         if (dev->parent)
 902                 pm_runtime_put(dev->parent);
 903 out_unlock:
 904         device_unlock(dev);
 905
 906         put_device(dev);
 907 }
 908
 909 static int __device_attach(struct device *dev, bool allow_async)
 910 {
 911         int ret = 0;
 912
 913         device_lock(dev);
 914         if (dev->p->dead) {
 915                 goto out_unlock;
 916         } else if (dev->driver) {
 917                 if (device_is_bound(dev)) {
 918                         ret = 1;
 919                         goto out_unlock;
 920                 }
 921                 ret = device_bind_driver(dev);
 922                 if (ret == 0)
 923                         ret = 1;
 924                 else {
 925                         dev->driver = NULL;
 926                         ret = 0;
 927                 }
 928         } else {
 929                 struct device_attach_data data = {
 930                         .dev = dev,
 931                         .check_async = allow_async,
 932                         .want_async = false,
 933                 };
 934
 935                 if (dev->parent)
 936                         pm_runtime_get_sync(dev->parent);
 937
 938                 ret = bus_for_each_drv(dev->bus, NULL, &data,
 939                                         __device_attach_driver);
 940                 if (!ret && allow_async && data.have_async) {
 941                         /*
 942                          * If we could not find appropriate driver
 943                          * synchronously and we are allowed to do
 944                          * async probes and there are drivers that
 945                          * want to probe asynchronously, we'll
 946                          * try them.
 947                          */
 948                         dev_dbg(dev, "scheduling asynchronous probe\n");
 949                         get_device(dev);
 950                         async_schedule_dev(__device_attach_async_helper, dev);
 951                 } else {
 952                         pm_request_idle(dev);
 953                 }
 954
 955                 if (dev->parent)
 956                         pm_runtime_put(dev->parent);
 957         }
 958 out_unlock:
 959         device_unlock(dev);
 960         return ret;
 961 }
 962
 963 /**
 964  * device_attach - try to attach device to a driver.
 965  * @dev: device.
 966  *
 967  * Walk the list of drivers that the bus has and call
 968  * driver_probe_device() for each pair. If a compatible
 969  * pair is found, break out and return.
 970  *
 971  * Returns 1 if the device was bound to a driver;
 972  * 0 if no matching driver was found;
 973  * -ENODEV if the device is not registered.
 974  *
 975  * When called for a USB interface, @dev->parent lock must be held.
 976  */
 977 int device_attach(struct device *dev)
 978 {
 979         return __device_attach(dev, false);
 980 }
 981 EXPORT_SYMBOL_GPL(device_attach);
 982
 983 void device_initial_probe(struct device *dev)
 984 {
 985         __device_attach(dev, true);
 986 }
 987
 988 /*
 989  * __device_driver_lock - acquire locks needed to manipulate dev->drv
 990  * @dev: Device we will update driver info for
 991  * @parent: Parent device. Needed if the bus requires parent lock
 992  *
 993  * This function will take the required locks for manipulating dev->drv.
 994  * Normally this will just be the @dev lock, but when called for a USB
 995  * interface, @parent lock will be held as well.
 996  */
 997 static void __device_driver_lock(struct device *dev, struct device *parent)
 998 {
 999         if (parent && dev->bus->need_parent_lock)
1000                 device_lock(parent);
1001         device_lock(dev);
1002 }
1003
1004 /*
1005  * __device_driver_unlock - release locks needed to manipulate dev->drv
1006  * @dev: Device we will update driver info for
1007  * @parent: Parent device. Needed if the bus requires parent lock
1008  *
1009  * This function will release the required locks for manipulating dev->drv.
1010  * Normally this will just be the the @dev lock, but when called for a
1011  * USB interface, @parent lock will be released as well.
1012  */
1013 static void __device_driver_unlock(struct device *dev, struct device *parent)
1014 {
1015         device_unlock(dev);
1016         if (parent && dev->bus->need_parent_lock)
1017                 device_unlock(parent);
1018 }
1019
1020 /**
1021  * device_driver_attach - attach a specific driver to a specific device
1022  * @drv: Driver to attach
1023  * @dev: Device to attach it to
1024  *
1025  * Manually attach driver to a device. Will acquire both @dev lock and
1026  * @dev->parent lock if needed.
1027  */
1028 int device_driver_attach(struct device_driver *drv, struct device *dev)
1029 {
1030         int ret = 0;
1031
1032         __device_driver_lock(dev, dev->parent);
1033
1034         /*
1035          * If device has been removed or someone has already successfully
1036          * bound a driver before us just skip the driver probe call.
1037          */
1038         if (!dev->p->dead && !dev->driver)
1039                 ret = driver_probe_device(drv, dev);
1040
1041         __device_driver_unlock(dev, dev->parent);
1042
1043         return ret;
1044 }
1045
1046 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1047 {
1048         struct device *dev = _dev;
1049         struct device_driver *drv;
1050         int ret = 0;
1051
1052         __device_driver_lock(dev, dev->parent);
1053
1054         drv = dev->p->async_driver;
1055
1056         /*
1057          * If device has been removed or someone has already successfully
1058          * bound a driver before us just skip the driver probe call.
1059          */
1060         if (!dev->p->dead && !dev->driver)
1061                 ret = driver_probe_device(drv, dev);
1062
1063         __device_driver_unlock(dev, dev->parent);
1064
1065         dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1066
1067         put_device(dev);
1068 }
1069
1070 static int __driver_attach(struct device *dev, void *data)
1071 {
1072         struct device_driver *drv = data;
1073         int ret;
1074
1075         /*
1076          * Lock device and try to bind to it. We drop the error
1077          * here and always return 0, because we need to keep trying
1078          * to bind to devices and some drivers will return an error
1079          * simply if it didn't support the device.
1080          *
1081          * driver_probe_device() will spit a warning if there
1082          * is an error.
1083          */
1084
1085         ret = driver_match_device(drv, dev);
1086         if (ret == 0) {
1087                 /* no match */
1088                 return 0;
1089         } else if (ret == -EPROBE_DEFER) {
1090                 dev_dbg(dev, "Device match requests probe deferral\n");
1091                 dev->can_match = true;
1092                 driver_deferred_probe_add(dev);
1093         } else if (ret < 0) {
1094                 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1095                 return ret;
1096         } /* ret > 0 means positive match */
1097
1098         if (driver_allows_async_probing(drv)) {
1099                 /*
1100                  * Instead of probing the device synchronously we will
1101                  * probe it asynchronously to allow for more parallelism.
1102                  *
1103                  * We only take the device lock here in order to guarantee
1104                  * that the dev->driver and async_driver fields are protected
1105                  */
1106                 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1107                 device_lock(dev);
1108                 if (!dev->driver) {
1109                         get_device(dev);
1110                         dev->p->async_driver = drv;
1111                         async_schedule_dev(__driver_attach_async_helper, dev);
1112                 }
1113                 device_unlock(dev);
1114                 return 0;
1115         }
1116
1117         device_driver_attach(drv, dev);
1118
1119         return 0;
1120 }
1121
1122 /**
1123  * driver_attach - try to bind driver to devices.
1124  * @drv: driver.
1125  *
1126  * Walk the list of devices that the bus has on it and try to
1127  * match the driver with each one.  If driver_probe_device()
1128  * returns 0 and the @dev->driver is set, we've found a
1129  * compatible pair.
1130  */
1131 int driver_attach(struct device_driver *drv)
1132 {
1133         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1134 }
1135 EXPORT_SYMBOL_GPL(driver_attach);
1136
1137 /*
1138  * __device_release_driver() must be called with @dev lock held.
1139  * When called for a USB interface, @dev->parent lock must be held as well.
1140  */
1141 static void __device_release_driver(struct device *dev, struct device *parent)
1142 {
1143         struct device_driver *drv;
1144
1145         drv = dev->driver;
1146         if (drv) {
1147                 pm_runtime_get_sync(dev);
1148
1149                 while (device_links_busy(dev)) {
1150                         __device_driver_unlock(dev, parent);
1151
1152                         device_links_unbind_consumers(dev);
1153
1154                         __device_driver_lock(dev, parent);
1155                         /*
1156                          * A concurrent invocation of the same function might
1157                          * have released the driver successfully while this one
1158                          * was waiting, so check for that.
1159                          */
1160                         if (dev->driver != drv) {
1161                                 pm_runtime_put(dev);
1162                                 return;
1163                         }
1164                 }
1165
1166                 driver_sysfs_remove(dev);
1167
1168                 if (dev->bus)
1169                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1170                                                      BUS_NOTIFY_UNBIND_DRIVER,
1171                                                      dev);
1172
1173                 pm_runtime_put_sync(dev);
1174
1175                 device_remove_file(dev, &dev_attr_state_synced);
1176                 device_remove_groups(dev, drv->dev_groups);
1177
1178                 if (dev->bus && dev->bus->remove)
1179                         dev->bus->remove(dev);
1180                 else if (drv->remove)
1181                         drv->remove(dev);
1182
1183                 device_links_driver_cleanup(dev);
1184
1185                 devres_release_all(dev);
1186                 arch_teardown_dma_ops(dev);
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 }