drivers/base/bus.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
bus_get
bus_put
drv_attr_show
drv_attr_store
driver_release
bus_attr_show
bus_attr_store
bus_create_file
bus_remove_file
bus_release
bus_uevent_filter
unbind_store
bind_store
drivers_autoprobe_show
drivers_autoprobe_store
drivers_probe_store
next_device
bus_for_each_dev
bus_find_device
subsys_find_device_by_id
next_driver
bus_for_each_drv
bus_add_device
bus_probe_device
bus_remove_device
add_bind_files
remove_bind_files
add_probe_files
remove_probe_files
uevent_store
bus_add_driver
bus_remove_driver
bus_rescan_devices_helper
bus_rescan_devices
device_reprobe
find_bus
bus_add_groups
bus_remove_groups
klist_devices_get
klist_devices_put
bus_uevent_store
bus_register
bus_unregister
bus_register_notifier
bus_unregister_notifier
bus_get_kset
bus_get_device_klist
device_insertion_sort_klist
bus_sort_breadthfirst
subsys_dev_iter_init
subsys_dev_iter_next
subsys_dev_iter_exit
subsys_interface_register
subsys_interface_unregister
system_root_device_release
subsys_register
subsys_system_register
subsys_virtual_register
buses_init
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * bus.c - bus driver management
   4  *
   5  * Copyright (c) 2002-3 Patrick Mochel
   6  * Copyright (c) 2002-3 Open Source Development Labs
   7  * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
   8  * Copyright (c) 2007 Novell Inc.
   9  */
  10 
  11 #include <linux/async.h>
  12 #include <linux/device.h>
  13 #include <linux/module.h>
  14 #include <linux/errno.h>
  15 #include <linux/slab.h>
  16 #include <linux/init.h>
  17 #include <linux/string.h>
  18 #include <linux/mutex.h>
  19 #include <linux/sysfs.h>
  20 #include "base.h"
  21 #include "power/power.h"
  22 
  23 /* /sys/devices/system */
  24 static struct kset *system_kset;
  25 
  26 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
  27 
  28 /*
  29  * sysfs bindings for drivers
  30  */
  31 
  32 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
  33 
  34 #define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
  35         struct driver_attribute driver_attr_##_name =           \
  36                 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
  37 
  38 static int __must_check bus_rescan_devices_helper(struct device *dev,
  39                                                 void *data);
  40 
  41 static struct bus_type *bus_get(struct bus_type *bus)
  42 {
  43         if (bus) {
  44                 kset_get(&bus->p->subsys);
  45                 return bus;
  46         }
  47         return NULL;
  48 }
  49 
  50 static void bus_put(struct bus_type *bus)
  51 {
  52         if (bus)
  53                 kset_put(&bus->p->subsys);
  54 }
  55 
  56 static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
  57                              char *buf)
  58 {
  59         struct driver_attribute *drv_attr = to_drv_attr(attr);
  60         struct driver_private *drv_priv = to_driver(kobj);
  61         ssize_t ret = -EIO;
  62 
  63         if (drv_attr->show)
  64                 ret = drv_attr->show(drv_priv->driver, buf);
  65         return ret;
  66 }
  67 
  68 static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
  69                               const char *buf, size_t count)
  70 {
  71         struct driver_attribute *drv_attr = to_drv_attr(attr);
  72         struct driver_private *drv_priv = to_driver(kobj);
  73         ssize_t ret = -EIO;
  74 
  75         if (drv_attr->store)
  76                 ret = drv_attr->store(drv_priv->driver, buf, count);
  77         return ret;
  78 }
  79 
  80 static const struct sysfs_ops driver_sysfs_ops = {
  81         .show   = drv_attr_show,
  82         .store  = drv_attr_store,
  83 };
  84 
  85 static void driver_release(struct kobject *kobj)
  86 {
  87         struct driver_private *drv_priv = to_driver(kobj);
  88 
  89         pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
  90         kfree(drv_priv);
  91 }
  92 
  93 static struct kobj_type driver_ktype = {
  94         .sysfs_ops      = &driver_sysfs_ops,
  95         .release        = driver_release,
  96 };
  97 
  98 /*
  99  * sysfs bindings for buses
 100  */
 101 static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
 102                              char *buf)
 103 {
 104         struct bus_attribute *bus_attr = to_bus_attr(attr);
 105         struct subsys_private *subsys_priv = to_subsys_private(kobj);
 106         ssize_t ret = 0;
 107 
 108         if (bus_attr->show)
 109                 ret = bus_attr->show(subsys_priv->bus, buf);
 110         return ret;
 111 }
 112 
 113 static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
 114                               const char *buf, size_t count)
 115 {
 116         struct bus_attribute *bus_attr = to_bus_attr(attr);
 117         struct subsys_private *subsys_priv = to_subsys_private(kobj);
 118         ssize_t ret = 0;
 119 
 120         if (bus_attr->store)
 121                 ret = bus_attr->store(subsys_priv->bus, buf, count);
 122         return ret;
 123 }
 124 
 125 static const struct sysfs_ops bus_sysfs_ops = {
 126         .show   = bus_attr_show,
 127         .store  = bus_attr_store,
 128 };
 129 
 130 int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
 131 {
 132         int error;
 133         if (bus_get(bus)) {
 134                 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
 135                 bus_put(bus);
 136         } else
 137                 error = -EINVAL;
 138         return error;
 139 }
 140 EXPORT_SYMBOL_GPL(bus_create_file);
 141 
 142 void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
 143 {
 144         if (bus_get(bus)) {
 145                 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
 146                 bus_put(bus);
 147         }
 148 }
 149 EXPORT_SYMBOL_GPL(bus_remove_file);
 150 
 151 static void bus_release(struct kobject *kobj)
 152 {
 153         struct subsys_private *priv = to_subsys_private(kobj);
 154         struct bus_type *bus = priv->bus;
 155 
 156         kfree(priv);
 157         bus->p = NULL;
 158 }
 159 
 160 static struct kobj_type bus_ktype = {
 161         .sysfs_ops      = &bus_sysfs_ops,
 162         .release        = bus_release,
 163 };
 164 
 165 static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
 166 {
 167         struct kobj_type *ktype = get_ktype(kobj);
 168 
 169         if (ktype == &bus_ktype)
 170                 return 1;
 171         return 0;
 172 }
 173 
 174 static const struct kset_uevent_ops bus_uevent_ops = {
 175         .filter = bus_uevent_filter,
 176 };
 177 
 178 static struct kset *bus_kset;
 179 
 180 /* Manually detach a device from its associated driver. */
 181 static ssize_t unbind_store(struct device_driver *drv, const char *buf,
 182                             size_t count)
 183 {
 184         struct bus_type *bus = bus_get(drv->bus);
 185         struct device *dev;
 186         int err = -ENODEV;
 187 
 188         dev = bus_find_device_by_name(bus, NULL, buf);
 189         if (dev && dev->driver == drv) {
 190                 device_driver_detach(dev);
 191                 err = count;
 192         }
 193         put_device(dev);
 194         bus_put(bus);
 195         return err;
 196 }
 197 static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, S_IWUSR, NULL, unbind_store);
 198 
 199 /*
 200  * Manually attach a device to a driver.
 201  * Note: the driver must want to bind to the device,
 202  * it is not possible to override the driver's id table.
 203  */
 204 static ssize_t bind_store(struct device_driver *drv, const char *buf,
 205                           size_t count)
 206 {
 207         struct bus_type *bus = bus_get(drv->bus);
 208         struct device *dev;
 209         int err = -ENODEV;
 210 
 211         dev = bus_find_device_by_name(bus, NULL, buf);
 212         if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
 213                 err = device_driver_attach(drv, dev);
 214 
 215                 if (err > 0) {
 216                         /* success */
 217                         err = count;
 218                 } else if (err == 0) {
 219                         /* driver didn't accept device */
 220                         err = -ENODEV;
 221                 }
 222         }
 223         put_device(dev);
 224         bus_put(bus);
 225         return err;
 226 }
 227 static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
 228 
 229 static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
 230 {
 231         return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
 232 }
 233 
 234 static ssize_t drivers_autoprobe_store(struct bus_type *bus,
 235                                        const char *buf, size_t count)
 236 {
 237         if (buf[0] == '0')
 238                 bus->p->drivers_autoprobe = 0;
 239         else
 240                 bus->p->drivers_autoprobe = 1;
 241         return count;
 242 }
 243 
 244 static ssize_t drivers_probe_store(struct bus_type *bus,
 245                                    const char *buf, size_t count)
 246 {
 247         struct device *dev;
 248         int err = -EINVAL;
 249 
 250         dev = bus_find_device_by_name(bus, NULL, buf);
 251         if (!dev)
 252                 return -ENODEV;
 253         if (bus_rescan_devices_helper(dev, NULL) == 0)
 254                 err = count;
 255         put_device(dev);
 256         return err;
 257 }
 258 
 259 static struct device *next_device(struct klist_iter *i)
 260 {
 261         struct klist_node *n = klist_next(i);
 262         struct device *dev = NULL;
 263         struct device_private *dev_prv;
 264 
 265         if (n) {
 266                 dev_prv = to_device_private_bus(n);
 267                 dev = dev_prv->device;
 268         }
 269         return dev;
 270 }
 271 
 272 /**
 273  * bus_for_each_dev - device iterator.
 274  * @bus: bus type.
 275  * @start: device to start iterating from.
 276  * @data: data for the callback.
 277  * @fn: function to be called for each device.
 278  *
 279  * Iterate over @bus's list of devices, and call @fn for each,
 280  * passing it @data. If @start is not NULL, we use that device to
 281  * begin iterating from.
 282  *
 283  * We check the return of @fn each time. If it returns anything
 284  * other than 0, we break out and return that value.
 285  *
 286  * NOTE: The device that returns a non-zero value is not retained
 287  * in any way, nor is its refcount incremented. If the caller needs
 288  * to retain this data, it should do so, and increment the reference
 289  * count in the supplied callback.
 290  */
 291 int bus_for_each_dev(struct bus_type *bus, struct device *start,
 292                      void *data, int (*fn)(struct device *, void *))
 293 {
 294         struct klist_iter i;
 295         struct device *dev;
 296         int error = 0;
 297 
 298         if (!bus || !bus->p)
 299                 return -EINVAL;
 300 
 301         klist_iter_init_node(&bus->p->klist_devices, &i,
 302                              (start ? &start->p->knode_bus : NULL));
 303         while (!error && (dev = next_device(&i)))
 304                 error = fn(dev, data);
 305         klist_iter_exit(&i);
 306         return error;
 307 }
 308 EXPORT_SYMBOL_GPL(bus_for_each_dev);
 309 
 310 /**
 311  * bus_find_device - device iterator for locating a particular device.
 312  * @bus: bus type
 313  * @start: Device to begin with
 314  * @data: Data to pass to match function
 315  * @match: Callback function to check device
 316  *
 317  * This is similar to the bus_for_each_dev() function above, but it
 318  * returns a reference to a device that is 'found' for later use, as
 319  * determined by the @match callback.
 320  *
 321  * The callback should return 0 if the device doesn't match and non-zero
 322  * if it does.  If the callback returns non-zero, this function will
 323  * return to the caller and not iterate over any more devices.
 324  */
 325 struct device *bus_find_device(struct bus_type *bus,
 326                                struct device *start, const void *data,
 327                                int (*match)(struct device *dev, const void *data))
 328 {
 329         struct klist_iter i;
 330         struct device *dev;
 331 
 332         if (!bus || !bus->p)
 333                 return NULL;
 334 
 335         klist_iter_init_node(&bus->p->klist_devices, &i,
 336                              (start ? &start->p->knode_bus : NULL));
 337         while ((dev = next_device(&i)))
 338                 if (match(dev, data) && get_device(dev))
 339                         break;
 340         klist_iter_exit(&i);
 341         return dev;
 342 }
 343 EXPORT_SYMBOL_GPL(bus_find_device);
 344 
 345 /**
 346  * subsys_find_device_by_id - find a device with a specific enumeration number
 347  * @subsys: subsystem
 348  * @id: index 'id' in struct device
 349  * @hint: device to check first
 350  *
 351  * Check the hint's next object and if it is a match return it directly,
 352  * otherwise, fall back to a full list search. Either way a reference for
 353  * the returned object is taken.
 354  */
 355 struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
 356                                         struct device *hint)
 357 {
 358         struct klist_iter i;
 359         struct device *dev;
 360 
 361         if (!subsys)
 362                 return NULL;
 363 
 364         if (hint) {
 365                 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
 366                 dev = next_device(&i);
 367                 if (dev && dev->id == id && get_device(dev)) {
 368                         klist_iter_exit(&i);
 369                         return dev;
 370                 }
 371                 klist_iter_exit(&i);
 372         }
 373 
 374         klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
 375         while ((dev = next_device(&i))) {
 376                 if (dev->id == id && get_device(dev)) {
 377                         klist_iter_exit(&i);
 378                         return dev;
 379                 }
 380         }
 381         klist_iter_exit(&i);
 382         return NULL;
 383 }
 384 EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
 385 
 386 static struct device_driver *next_driver(struct klist_iter *i)
 387 {
 388         struct klist_node *n = klist_next(i);
 389         struct driver_private *drv_priv;
 390 
 391         if (n) {
 392                 drv_priv = container_of(n, struct driver_private, knode_bus);
 393                 return drv_priv->driver;
 394         }
 395         return NULL;
 396 }
 397 
 398 /**
 399  * bus_for_each_drv - driver iterator
 400  * @bus: bus we're dealing with.
 401  * @start: driver to start iterating on.
 402  * @data: data to pass to the callback.
 403  * @fn: function to call for each driver.
 404  *
 405  * This is nearly identical to the device iterator above.
 406  * We iterate over each driver that belongs to @bus, and call
 407  * @fn for each. If @fn returns anything but 0, we break out
 408  * and return it. If @start is not NULL, we use it as the head
 409  * of the list.
 410  *
 411  * NOTE: we don't return the driver that returns a non-zero
 412  * value, nor do we leave the reference count incremented for that
 413  * driver. If the caller needs to know that info, it must set it
 414  * in the callback. It must also be sure to increment the refcount
 415  * so it doesn't disappear before returning to the caller.
 416  */
 417 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
 418                      void *data, int (*fn)(struct device_driver *, void *))
 419 {
 420         struct klist_iter i;
 421         struct device_driver *drv;
 422         int error = 0;
 423 
 424         if (!bus)
 425                 return -EINVAL;
 426 
 427         klist_iter_init_node(&bus->p->klist_drivers, &i,
 428                              start ? &start->p->knode_bus : NULL);
 429         while ((drv = next_driver(&i)) && !error)
 430                 error = fn(drv, data);
 431         klist_iter_exit(&i);
 432         return error;
 433 }
 434 EXPORT_SYMBOL_GPL(bus_for_each_drv);
 435 
 436 /**
 437  * bus_add_device - add device to bus
 438  * @dev: device being added
 439  *
 440  * - Add device's bus attributes.
 441  * - Create links to device's bus.
 442  * - Add the device to its bus's list of devices.
 443  */
 444 int bus_add_device(struct device *dev)
 445 {
 446         struct bus_type *bus = bus_get(dev->bus);
 447         int error = 0;
 448 
 449         if (bus) {
 450                 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
 451                 error = device_add_groups(dev, bus->dev_groups);
 452                 if (error)
 453                         goto out_put;
 454                 error = sysfs_create_link(&bus->p->devices_kset->kobj,
 455                                                 &dev->kobj, dev_name(dev));
 456                 if (error)
 457                         goto out_groups;
 458                 error = sysfs_create_link(&dev->kobj,
 459                                 &dev->bus->p->subsys.kobj, "subsystem");
 460                 if (error)
 461                         goto out_subsys;
 462                 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
 463         }
 464         return 0;
 465 
 466 out_subsys:
 467         sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
 468 out_groups:
 469         device_remove_groups(dev, bus->dev_groups);
 470 out_put:
 471         bus_put(dev->bus);
 472         return error;
 473 }
 474 
 475 /**
 476  * bus_probe_device - probe drivers for a new device
 477  * @dev: device to probe
 478  *
 479  * - Automatically probe for a driver if the bus allows it.
 480  */
 481 void bus_probe_device(struct device *dev)
 482 {
 483         struct bus_type *bus = dev->bus;
 484         struct subsys_interface *sif;
 485 
 486         if (!bus)
 487                 return;
 488 
 489         if (bus->p->drivers_autoprobe)
 490                 device_initial_probe(dev);
 491 
 492         mutex_lock(&bus->p->mutex);
 493         list_for_each_entry(sif, &bus->p->interfaces, node)
 494                 if (sif->add_dev)
 495                         sif->add_dev(dev, sif);
 496         mutex_unlock(&bus->p->mutex);
 497 }
 498 
 499 /**
 500  * bus_remove_device - remove device from bus
 501  * @dev: device to be removed
 502  *
 503  * - Remove device from all interfaces.
 504  * - Remove symlink from bus' directory.
 505  * - Delete device from bus's list.
 506  * - Detach from its driver.
 507  * - Drop reference taken in bus_add_device().
 508  */
 509 void bus_remove_device(struct device *dev)
 510 {
 511         struct bus_type *bus = dev->bus;
 512         struct subsys_interface *sif;
 513 
 514         if (!bus)
 515                 return;
 516 
 517         mutex_lock(&bus->p->mutex);
 518         list_for_each_entry(sif, &bus->p->interfaces, node)
 519                 if (sif->remove_dev)
 520                         sif->remove_dev(dev, sif);
 521         mutex_unlock(&bus->p->mutex);
 522 
 523         sysfs_remove_link(&dev->kobj, "subsystem");
 524         sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
 525                           dev_name(dev));
 526         device_remove_groups(dev, dev->bus->dev_groups);
 527         if (klist_node_attached(&dev->p->knode_bus))
 528                 klist_del(&dev->p->knode_bus);
 529 
 530         pr_debug("bus: '%s': remove device %s\n",
 531                  dev->bus->name, dev_name(dev));
 532         device_release_driver(dev);
 533         bus_put(dev->bus);
 534 }
 535 
 536 static int __must_check add_bind_files(struct device_driver *drv)
 537 {
 538         int ret;
 539 
 540         ret = driver_create_file(drv, &driver_attr_unbind);
 541         if (ret == 0) {
 542                 ret = driver_create_file(drv, &driver_attr_bind);
 543                 if (ret)
 544                         driver_remove_file(drv, &driver_attr_unbind);
 545         }
 546         return ret;
 547 }
 548 
 549 static void remove_bind_files(struct device_driver *drv)
 550 {
 551         driver_remove_file(drv, &driver_attr_bind);
 552         driver_remove_file(drv, &driver_attr_unbind);
 553 }
 554 
 555 static BUS_ATTR_WO(drivers_probe);
 556 static BUS_ATTR_RW(drivers_autoprobe);
 557 
 558 static int add_probe_files(struct bus_type *bus)
 559 {
 560         int retval;
 561 
 562         retval = bus_create_file(bus, &bus_attr_drivers_probe);
 563         if (retval)
 564                 goto out;
 565 
 566         retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
 567         if (retval)
 568                 bus_remove_file(bus, &bus_attr_drivers_probe);
 569 out:
 570         return retval;
 571 }
 572 
 573 static void remove_probe_files(struct bus_type *bus)
 574 {
 575         bus_remove_file(bus, &bus_attr_drivers_autoprobe);
 576         bus_remove_file(bus, &bus_attr_drivers_probe);
 577 }
 578 
 579 static ssize_t uevent_store(struct device_driver *drv, const char *buf,
 580                             size_t count)
 581 {
 582         int rc;
 583 
 584         rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
 585         return rc ? rc : count;
 586 }
 587 static DRIVER_ATTR_WO(uevent);
 588 
 589 /**
 590  * bus_add_driver - Add a driver to the bus.
 591  * @drv: driver.
 592  */
 593 int bus_add_driver(struct device_driver *drv)
 594 {
 595         struct bus_type *bus;
 596         struct driver_private *priv;
 597         int error = 0;
 598 
 599         bus = bus_get(drv->bus);
 600         if (!bus)
 601                 return -EINVAL;
 602 
 603         pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
 604 
 605         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 606         if (!priv) {
 607                 error = -ENOMEM;
 608                 goto out_put_bus;
 609         }
 610         klist_init(&priv->klist_devices, NULL, NULL);
 611         priv->driver = drv;
 612         drv->p = priv;
 613         priv->kobj.kset = bus->p->drivers_kset;
 614         error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
 615                                      "%s", drv->name);
 616         if (error)
 617                 goto out_unregister;
 618 
 619         klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
 620         if (drv->bus->p->drivers_autoprobe) {
 621                 error = driver_attach(drv);
 622                 if (error)
 623                         goto out_unregister;
 624         }
 625         module_add_driver(drv->owner, drv);
 626 
 627         error = driver_create_file(drv, &driver_attr_uevent);
 628         if (error) {
 629                 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
 630                         __func__, drv->name);
 631         }
 632         error = driver_add_groups(drv, bus->drv_groups);
 633         if (error) {
 634                 /* How the hell do we get out of this pickle? Give up */
 635                 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
 636                         __func__, drv->name);
 637         }
 638 
 639         if (!drv->suppress_bind_attrs) {
 640                 error = add_bind_files(drv);
 641                 if (error) {
 642                         /* Ditto */
 643                         printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
 644                                 __func__, drv->name);
 645                 }
 646         }
 647 
 648         return 0;
 649 
 650 out_unregister:
 651         kobject_put(&priv->kobj);
 652         /* drv->p is freed in driver_release()  */
 653         drv->p = NULL;
 654 out_put_bus:
 655         bus_put(bus);
 656         return error;
 657 }
 658 
 659 /**
 660  * bus_remove_driver - delete driver from bus's knowledge.
 661  * @drv: driver.
 662  *
 663  * Detach the driver from the devices it controls, and remove
 664  * it from its bus's list of drivers. Finally, we drop the reference
 665  * to the bus we took in bus_add_driver().
 666  */
 667 void bus_remove_driver(struct device_driver *drv)
 668 {
 669         if (!drv->bus)
 670                 return;
 671 
 672         if (!drv->suppress_bind_attrs)
 673                 remove_bind_files(drv);
 674         driver_remove_groups(drv, drv->bus->drv_groups);
 675         driver_remove_file(drv, &driver_attr_uevent);
 676         klist_remove(&drv->p->knode_bus);
 677         pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
 678         driver_detach(drv);
 679         module_remove_driver(drv);
 680         kobject_put(&drv->p->kobj);
 681         bus_put(drv->bus);
 682 }
 683 
 684 /* Helper for bus_rescan_devices's iter */
 685 static int __must_check bus_rescan_devices_helper(struct device *dev,
 686                                                   void *data)
 687 {
 688         int ret = 0;
 689 
 690         if (!dev->driver) {
 691                 if (dev->parent && dev->bus->need_parent_lock)
 692                         device_lock(dev->parent);
 693                 ret = device_attach(dev);
 694                 if (dev->parent && dev->bus->need_parent_lock)
 695                         device_unlock(dev->parent);
 696         }
 697         return ret < 0 ? ret : 0;
 698 }
 699 
 700 /**
 701  * bus_rescan_devices - rescan devices on the bus for possible drivers
 702  * @bus: the bus to scan.
 703  *
 704  * This function will look for devices on the bus with no driver
 705  * attached and rescan it against existing drivers to see if it matches
 706  * any by calling device_attach() for the unbound devices.
 707  */
 708 int bus_rescan_devices(struct bus_type *bus)
 709 {
 710         return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
 711 }
 712 EXPORT_SYMBOL_GPL(bus_rescan_devices);
 713 
 714 /**
 715  * device_reprobe - remove driver for a device and probe for a new driver
 716  * @dev: the device to reprobe
 717  *
 718  * This function detaches the attached driver (if any) for the given
 719  * device and restarts the driver probing process.  It is intended
 720  * to use if probing criteria changed during a devices lifetime and
 721  * driver attachment should change accordingly.
 722  */
 723 int device_reprobe(struct device *dev)
 724 {
 725         if (dev->driver)
 726                 device_driver_detach(dev);
 727         return bus_rescan_devices_helper(dev, NULL);
 728 }
 729 EXPORT_SYMBOL_GPL(device_reprobe);
 730 
 731 /**
 732  * find_bus - locate bus by name.
 733  * @name: name of bus.
 734  *
 735  * Call kset_find_obj() to iterate over list of buses to
 736  * find a bus by name. Return bus if found.
 737  *
 738  * Note that kset_find_obj increments bus' reference count.
 739  */
 740 #if 0
 741 struct bus_type *find_bus(char *name)
 742 {
 743         struct kobject *k = kset_find_obj(bus_kset, name);
 744         return k ? to_bus(k) : NULL;
 745 }
 746 #endif  /*  0  */
 747 
 748 static int bus_add_groups(struct bus_type *bus,
 749                           const struct attribute_group **groups)
 750 {
 751         return sysfs_create_groups(&bus->p->subsys.kobj, groups);
 752 }
 753 
 754 static void bus_remove_groups(struct bus_type *bus,
 755                               const struct attribute_group **groups)
 756 {
 757         sysfs_remove_groups(&bus->p->subsys.kobj, groups);
 758 }
 759 
 760 static void klist_devices_get(struct klist_node *n)
 761 {
 762         struct device_private *dev_prv = to_device_private_bus(n);
 763         struct device *dev = dev_prv->device;
 764 
 765         get_device(dev);
 766 }
 767 
 768 static void klist_devices_put(struct klist_node *n)
 769 {
 770         struct device_private *dev_prv = to_device_private_bus(n);
 771         struct device *dev = dev_prv->device;
 772 
 773         put_device(dev);
 774 }
 775 
 776 static ssize_t bus_uevent_store(struct bus_type *bus,
 777                                 const char *buf, size_t count)
 778 {
 779         int rc;
 780 
 781         rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
 782         return rc ? rc : count;
 783 }
 784 /*
 785  * "open code" the old BUS_ATTR() macro here.  We want to use BUS_ATTR_WO()
 786  * here, but can not use it as earlier in the file we have
 787  * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
 788  * function name.
 789  */
 790 static struct bus_attribute bus_attr_uevent = __ATTR(uevent, S_IWUSR, NULL,
 791                                                      bus_uevent_store);
 792 
 793 /**
 794  * bus_register - register a driver-core subsystem
 795  * @bus: bus to register
 796  *
 797  * Once we have that, we register the bus with the kobject
 798  * infrastructure, then register the children subsystems it has:
 799  * the devices and drivers that belong to the subsystem.
 800  */
 801 int bus_register(struct bus_type *bus)
 802 {
 803         int retval;
 804         struct subsys_private *priv;
 805         struct lock_class_key *key = &bus->lock_key;
 806 
 807         priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
 808         if (!priv)
 809                 return -ENOMEM;
 810 
 811         priv->bus = bus;
 812         bus->p = priv;
 813 
 814         BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
 815 
 816         retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
 817         if (retval)
 818                 goto out;
 819 
 820         priv->subsys.kobj.kset = bus_kset;
 821         priv->subsys.kobj.ktype = &bus_ktype;
 822         priv->drivers_autoprobe = 1;
 823 
 824         retval = kset_register(&priv->subsys);
 825         if (retval)
 826                 goto out;
 827 
 828         retval = bus_create_file(bus, &bus_attr_uevent);
 829         if (retval)
 830                 goto bus_uevent_fail;
 831 
 832         priv->devices_kset = kset_create_and_add("devices", NULL,
 833                                                  &priv->subsys.kobj);
 834         if (!priv->devices_kset) {
 835                 retval = -ENOMEM;
 836                 goto bus_devices_fail;
 837         }
 838 
 839         priv->drivers_kset = kset_create_and_add("drivers", NULL,
 840                                                  &priv->subsys.kobj);
 841         if (!priv->drivers_kset) {
 842                 retval = -ENOMEM;
 843                 goto bus_drivers_fail;
 844         }
 845 
 846         INIT_LIST_HEAD(&priv->interfaces);
 847         __mutex_init(&priv->mutex, "subsys mutex", key);
 848         klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
 849         klist_init(&priv->klist_drivers, NULL, NULL);
 850 
 851         retval = add_probe_files(bus);
 852         if (retval)
 853                 goto bus_probe_files_fail;
 854 
 855         retval = bus_add_groups(bus, bus->bus_groups);
 856         if (retval)
 857                 goto bus_groups_fail;
 858 
 859         pr_debug("bus: '%s': registered\n", bus->name);
 860         return 0;
 861 
 862 bus_groups_fail:
 863         remove_probe_files(bus);
 864 bus_probe_files_fail:
 865         kset_unregister(bus->p->drivers_kset);
 866 bus_drivers_fail:
 867         kset_unregister(bus->p->devices_kset);
 868 bus_devices_fail:
 869         bus_remove_file(bus, &bus_attr_uevent);
 870 bus_uevent_fail:
 871         kset_unregister(&bus->p->subsys);
 872 out:
 873         kfree(bus->p);
 874         bus->p = NULL;
 875         return retval;
 876 }
 877 EXPORT_SYMBOL_GPL(bus_register);
 878 
 879 /**
 880  * bus_unregister - remove a bus from the system
 881  * @bus: bus.
 882  *
 883  * Unregister the child subsystems and the bus itself.
 884  * Finally, we call bus_put() to release the refcount
 885  */
 886 void bus_unregister(struct bus_type *bus)
 887 {
 888         pr_debug("bus: '%s': unregistering\n", bus->name);
 889         if (bus->dev_root)
 890                 device_unregister(bus->dev_root);
 891         bus_remove_groups(bus, bus->bus_groups);
 892         remove_probe_files(bus);
 893         kset_unregister(bus->p->drivers_kset);
 894         kset_unregister(bus->p->devices_kset);
 895         bus_remove_file(bus, &bus_attr_uevent);
 896         kset_unregister(&bus->p->subsys);
 897 }
 898 EXPORT_SYMBOL_GPL(bus_unregister);
 899 
 900 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
 901 {
 902         return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
 903 }
 904 EXPORT_SYMBOL_GPL(bus_register_notifier);
 905 
 906 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
 907 {
 908         return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
 909 }
 910 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
 911 
 912 struct kset *bus_get_kset(struct bus_type *bus)
 913 {
 914         return &bus->p->subsys;
 915 }
 916 EXPORT_SYMBOL_GPL(bus_get_kset);
 917 
 918 struct klist *bus_get_device_klist(struct bus_type *bus)
 919 {
 920         return &bus->p->klist_devices;
 921 }
 922 EXPORT_SYMBOL_GPL(bus_get_device_klist);
 923 
 924 /*
 925  * Yes, this forcibly breaks the klist abstraction temporarily.  It
 926  * just wants to sort the klist, not change reference counts and
 927  * take/drop locks rapidly in the process.  It does all this while
 928  * holding the lock for the list, so objects can't otherwise be
 929  * added/removed while we're swizzling.
 930  */
 931 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
 932                                         int (*compare)(const struct device *a,
 933                                                         const struct device *b))
 934 {
 935         struct klist_node *n;
 936         struct device_private *dev_prv;
 937         struct device *b;
 938 
 939         list_for_each_entry(n, list, n_node) {
 940                 dev_prv = to_device_private_bus(n);
 941                 b = dev_prv->device;
 942                 if (compare(a, b) <= 0) {
 943                         list_move_tail(&a->p->knode_bus.n_node,
 944                                        &b->p->knode_bus.n_node);
 945                         return;
 946                 }
 947         }
 948         list_move_tail(&a->p->knode_bus.n_node, list);
 949 }
 950 
 951 void bus_sort_breadthfirst(struct bus_type *bus,
 952                            int (*compare)(const struct device *a,
 953                                           const struct device *b))
 954 {
 955         LIST_HEAD(sorted_devices);
 956         struct klist_node *n, *tmp;
 957         struct device_private *dev_prv;
 958         struct device *dev;
 959         struct klist *device_klist;
 960 
 961         device_klist = bus_get_device_klist(bus);
 962 
 963         spin_lock(&device_klist->k_lock);
 964         list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
 965                 dev_prv = to_device_private_bus(n);
 966                 dev = dev_prv->device;
 967                 device_insertion_sort_klist(dev, &sorted_devices, compare);
 968         }
 969         list_splice(&sorted_devices, &device_klist->k_list);
 970         spin_unlock(&device_klist->k_lock);
 971 }
 972 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
 973 
 974 /**
 975  * subsys_dev_iter_init - initialize subsys device iterator
 976  * @iter: subsys iterator to initialize
 977  * @subsys: the subsys we wanna iterate over
 978  * @start: the device to start iterating from, if any
 979  * @type: device_type of the devices to iterate over, NULL for all
 980  *
 981  * Initialize subsys iterator @iter such that it iterates over devices
 982  * of @subsys.  If @start is set, the list iteration will start there,
 983  * otherwise if it is NULL, the iteration starts at the beginning of
 984  * the list.
 985  */
 986 void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
 987                           struct device *start, const struct device_type *type)
 988 {
 989         struct klist_node *start_knode = NULL;
 990 
 991         if (start)
 992                 start_knode = &start->p->knode_bus;
 993         klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
 994         iter->type = type;
 995 }
 996 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
 997 
 998 /**
 999  * subsys_dev_iter_next - iterate to the next device
1000  * @iter: subsys iterator to proceed
1001  *
1002  * Proceed @iter to the next device and return it.  Returns NULL if
1003  * iteration is complete.
1004  *
1005  * The returned device is referenced and won't be released till
1006  * iterator is proceed to the next device or exited.  The caller is
1007  * free to do whatever it wants to do with the device including
1008  * calling back into subsys code.
1009  */
1010 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1011 {
1012         struct klist_node *knode;
1013         struct device *dev;
1014 
1015         for (;;) {
1016                 knode = klist_next(&iter->ki);
1017                 if (!knode)
1018                         return NULL;
1019                 dev = to_device_private_bus(knode)->device;
1020                 if (!iter->type || iter->type == dev->type)
1021                         return dev;
1022         }
1023 }
1024 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1025 
1026 /**
1027  * subsys_dev_iter_exit - finish iteration
1028  * @iter: subsys iterator to finish
1029  *
1030  * Finish an iteration.  Always call this function after iteration is
1031  * complete whether the iteration ran till the end or not.
1032  */
1033 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1034 {
1035         klist_iter_exit(&iter->ki);
1036 }
1037 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1038 
1039 int subsys_interface_register(struct subsys_interface *sif)
1040 {
1041         struct bus_type *subsys;
1042         struct subsys_dev_iter iter;
1043         struct device *dev;
1044 
1045         if (!sif || !sif->subsys)
1046                 return -ENODEV;
1047 
1048         subsys = bus_get(sif->subsys);
1049         if (!subsys)
1050                 return -EINVAL;
1051 
1052         mutex_lock(&subsys->p->mutex);
1053         list_add_tail(&sif->node, &subsys->p->interfaces);
1054         if (sif->add_dev) {
1055                 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1056                 while ((dev = subsys_dev_iter_next(&iter)))
1057                         sif->add_dev(dev, sif);
1058                 subsys_dev_iter_exit(&iter);
1059         }
1060         mutex_unlock(&subsys->p->mutex);
1061 
1062         return 0;
1063 }
1064 EXPORT_SYMBOL_GPL(subsys_interface_register);
1065 
1066 void subsys_interface_unregister(struct subsys_interface *sif)
1067 {
1068         struct bus_type *subsys;
1069         struct subsys_dev_iter iter;
1070         struct device *dev;
1071 
1072         if (!sif || !sif->subsys)
1073                 return;
1074 
1075         subsys = sif->subsys;
1076 
1077         mutex_lock(&subsys->p->mutex);
1078         list_del_init(&sif->node);
1079         if (sif->remove_dev) {
1080                 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1081                 while ((dev = subsys_dev_iter_next(&iter)))
1082                         sif->remove_dev(dev, sif);
1083                 subsys_dev_iter_exit(&iter);
1084         }
1085         mutex_unlock(&subsys->p->mutex);
1086 
1087         bus_put(subsys);
1088 }
1089 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1090 
1091 static void system_root_device_release(struct device *dev)
1092 {
1093         kfree(dev);
1094 }
1095 
1096 static int subsys_register(struct bus_type *subsys,
1097                            const struct attribute_group **groups,
1098                            struct kobject *parent_of_root)
1099 {
1100         struct device *dev;
1101         int err;
1102 
1103         err = bus_register(subsys);
1104         if (err < 0)
1105                 return err;
1106 
1107         dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1108         if (!dev) {
1109                 err = -ENOMEM;
1110                 goto err_dev;
1111         }
1112 
1113         err = dev_set_name(dev, "%s", subsys->name);
1114         if (err < 0)
1115                 goto err_name;
1116 
1117         dev->kobj.parent = parent_of_root;
1118         dev->groups = groups;
1119         dev->release = system_root_device_release;
1120 
1121         err = device_register(dev);
1122         if (err < 0)
1123                 goto err_dev_reg;
1124 
1125         subsys->dev_root = dev;
1126         return 0;
1127 
1128 err_dev_reg:
1129         put_device(dev);
1130         dev = NULL;
1131 err_name:
1132         kfree(dev);
1133 err_dev:
1134         bus_unregister(subsys);
1135         return err;
1136 }
1137 
1138 /**
1139  * subsys_system_register - register a subsystem at /sys/devices/system/
1140  * @subsys: system subsystem
1141  * @groups: default attributes for the root device
1142  *
1143  * All 'system' subsystems have a /sys/devices/system/<name> root device
1144  * with the name of the subsystem. The root device can carry subsystem-
1145  * wide attributes. All registered devices are below this single root
1146  * device and are named after the subsystem with a simple enumeration
1147  * number appended. The registered devices are not explicitly named;
1148  * only 'id' in the device needs to be set.
1149  *
1150  * Do not use this interface for anything new, it exists for compatibility
1151  * with bad ideas only. New subsystems should use plain subsystems; and
1152  * add the subsystem-wide attributes should be added to the subsystem
1153  * directory itself and not some create fake root-device placed in
1154  * /sys/devices/system/<name>.
1155  */
1156 int subsys_system_register(struct bus_type *subsys,
1157                            const struct attribute_group **groups)
1158 {
1159         return subsys_register(subsys, groups, &system_kset->kobj);
1160 }
1161 EXPORT_SYMBOL_GPL(subsys_system_register);
1162 
1163 /**
1164  * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1165  * @subsys: virtual subsystem
1166  * @groups: default attributes for the root device
1167  *
1168  * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1169  * with the name of the subystem.  The root device can carry subsystem-wide
1170  * attributes.  All registered devices are below this single root device.
1171  * There's no restriction on device naming.  This is for kernel software
1172  * constructs which need sysfs interface.
1173  */
1174 int subsys_virtual_register(struct bus_type *subsys,
1175                             const struct attribute_group **groups)
1176 {
1177         struct kobject *virtual_dir;
1178 
1179         virtual_dir = virtual_device_parent(NULL);
1180         if (!virtual_dir)
1181                 return -ENOMEM;
1182 
1183         return subsys_register(subsys, groups, virtual_dir);
1184 }
1185 EXPORT_SYMBOL_GPL(subsys_virtual_register);
1186 
1187 int __init buses_init(void)
1188 {
1189         bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1190         if (!bus_kset)
1191                 return -ENOMEM;
1192 
1193         system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1194         if (!system_kset)
1195                 return -ENOMEM;
1196 
1197         return 0;
1198 }
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/base/bus.c

DEFINITIONS
