drivers/base/bus.c

   1 /*
   2  * bus.c - bus driver management
   3  *
   4  * Copyright (c) 2002-3 Patrick Mochel
   5  * Copyright (c) 2002-3 Open Source Development Labs
   6  * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
   7  * Copyright (c) 2007 Novell Inc.
   8  *
   9  * This file is released under the GPLv2
  10  *
  11  */
  12
  13 #include <linux/device.h>
  14 #include <linux/module.h>
  15 #include <linux/errno.h>
  16 #include <linux/slab.h>
  17 #include <linux/init.h>
  18 #include <linux/string.h>
  19 #include "base.h"
  20 #include "power/power.h"
  21
  22 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
  23 #define to_bus(obj) container_of(obj, struct bus_type_private, subsys.kobj)
  24
  25 /*
  26  * sysfs bindings for drivers
  27  */
  28
  29 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
  30
  31
  32 static int __must_check bus_rescan_devices_helper(struct device *dev,
  33                                                 void *data);
  34
  35 static struct bus_type *bus_get(struct bus_type *bus)
  36 {
  37         if (bus) {
  38                 kset_get(&bus->p->subsys);
  39                 return bus;
  40         }
  41         return NULL;
  42 }
  43
  44 static void bus_put(struct bus_type *bus)
  45 {
  46         if (bus)
  47                 kset_put(&bus->p->subsys);
  48 }
  49
  50 static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
  51                              char *buf)
  52 {
  53         struct driver_attribute *drv_attr = to_drv_attr(attr);
  54         struct driver_private *drv_priv = to_driver(kobj);
  55         ssize_t ret = -EIO;
  56
  57         if (drv_attr->show)
  58                 ret = drv_attr->show(drv_priv->driver, buf);
  59         return ret;
  60 }
  61
  62 static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
  63                               const char *buf, size_t count)
  64 {
  65         struct driver_attribute *drv_attr = to_drv_attr(attr);
  66         struct driver_private *drv_priv = to_driver(kobj);
  67         ssize_t ret = -EIO;
  68
  69         if (drv_attr->store)
  70                 ret = drv_attr->store(drv_priv->driver, buf, count);
  71         return ret;
  72 }
  73
  74 static const struct sysfs_ops driver_sysfs_ops = {
  75         .show   = drv_attr_show,
  76         .store  = drv_attr_store,
  77 };
  78
  79 static void driver_release(struct kobject *kobj)
  80 {
  81         struct driver_private *drv_priv = to_driver(kobj);
  82
  83         pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
  84         kfree(drv_priv);
  85 }
  86
  87 static struct kobj_type driver_ktype = {
  88         .sysfs_ops      = &driver_sysfs_ops,
  89         .release        = driver_release,
  90 };
  91
  92 /*
  93  * sysfs bindings for buses
  94  */
  95 static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
  96                              char *buf)
  97 {
  98         struct bus_attribute *bus_attr = to_bus_attr(attr);
  99         struct bus_type_private *bus_priv = to_bus(kobj);
 100         ssize_t ret = 0;
 101
 102         if (bus_attr->show)
 103                 ret = bus_attr->show(bus_priv->bus, buf);
 104         return ret;
 105 }
 106
 107 static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
 108                               const char *buf, size_t count)
 109 {
 110         struct bus_attribute *bus_attr = to_bus_attr(attr);
 111         struct bus_type_private *bus_priv = to_bus(kobj);
 112         ssize_t ret = 0;
 113
 114         if (bus_attr->store)
 115                 ret = bus_attr->store(bus_priv->bus, buf, count);
 116         return ret;
 117 }
 118
 119 static const struct sysfs_ops bus_sysfs_ops = {
 120         .show   = bus_attr_show,
 121         .store  = bus_attr_store,
 122 };
 123
 124 int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
 125 {
 126         int error;
 127         if (bus_get(bus)) {
 128                 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
 129                 bus_put(bus);
 130         } else
 131                 error = -EINVAL;
 132         return error;
 133 }
 134 EXPORT_SYMBOL_GPL(bus_create_file);
 135
 136 void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
 137 {
 138         if (bus_get(bus)) {
 139                 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
 140                 bus_put(bus);
 141         }
 142 }
 143 EXPORT_SYMBOL_GPL(bus_remove_file);
 144
 145 static struct kobj_type bus_ktype = {
 146         .sysfs_ops      = &bus_sysfs_ops,
 147 };
 148
 149 static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
 150 {
 151         struct kobj_type *ktype = get_ktype(kobj);
 152
 153         if (ktype == &bus_ktype)
 154                 return 1;
 155         return 0;
 156 }
 157
 158 static const struct kset_uevent_ops bus_uevent_ops = {
 159         .filter = bus_uevent_filter,
 160 };
 161
 162 static struct kset *bus_kset;
 163
 164
 165 #ifdef CONFIG_HOTPLUG
 166 /* Manually detach a device from its associated driver. */
 167 static ssize_t driver_unbind(struct device_driver *drv,
 168                              const char *buf, size_t count)
 169 {
 170         struct bus_type *bus = bus_get(drv->bus);
 171         struct device *dev;
 172         int err = -ENODEV;
 173
 174         dev = bus_find_device_by_name(bus, NULL, buf);
 175         if (dev && dev->driver == drv) {
 176                 if (dev->parent)        /* Needed for USB */
 177                         device_lock(dev->parent);
 178                 device_release_driver(dev);
 179                 if (dev->parent)
 180                         device_unlock(dev->parent);
 181                 err = count;
 182         }
 183         put_device(dev);
 184         bus_put(bus);
 185         return err;
 186 }
 187 static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
 188
 189 /*
 190  * Manually attach a device to a driver.
 191  * Note: the driver must want to bind to the device,
 192  * it is not possible to override the driver's id table.
 193  */
 194 static ssize_t driver_bind(struct device_driver *drv,
 195                            const char *buf, size_t count)
 196 {
 197         struct bus_type *bus = bus_get(drv->bus);
 198         struct device *dev;
 199         int err = -ENODEV;
 200
 201         dev = bus_find_device_by_name(bus, NULL, buf);
 202         if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
 203                 if (dev->parent)        /* Needed for USB */
 204                         device_lock(dev->parent);
 205                 device_lock(dev);
 206                 err = driver_probe_device(drv, dev);
 207                 device_unlock(dev);
 208                 if (dev->parent)
 209                         device_unlock(dev->parent);
 210
 211                 if (err > 0) {
 212                         /* success */
 213                         err = count;
 214                 } else if (err == 0) {
 215                         /* driver didn't accept device */
 216                         err = -ENODEV;
 217                 }
 218         }
 219         put_device(dev);
 220         bus_put(bus);
 221         return err;
 222 }
 223 static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
 224
 225 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
 226 {
 227         return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
 228 }
 229
 230 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
 231                                        const char *buf, size_t count)
 232 {
 233         if (buf[0] == '0')
 234                 bus->p->drivers_autoprobe = 0;
 235         else
 236                 bus->p->drivers_autoprobe = 1;
 237         return count;
 238 }
 239
 240 static ssize_t store_drivers_probe(struct bus_type *bus,
 241                                    const char *buf, size_t count)
 242 {
 243         struct device *dev;
 244
 245         dev = bus_find_device_by_name(bus, NULL, buf);
 246         if (!dev)
 247                 return -ENODEV;
 248         if (bus_rescan_devices_helper(dev, NULL) != 0)
 249                 return -EINVAL;
 250         return count;
 251 }
 252 #endif
 253
 254 static struct device *next_device(struct klist_iter *i)
 255 {
 256         struct klist_node *n = klist_next(i);
 257         struct device *dev = NULL;
 258         struct device_private *dev_prv;
 259
 260         if (n) {
 261                 dev_prv = to_device_private_bus(n);
 262                 dev = dev_prv->device;
 263         }
 264         return dev;
 265 }
 266
 267 /**
 268  * bus_for_each_dev - device iterator.
 269  * @bus: bus type.
 270  * @start: device to start iterating from.
 271  * @data: data for the callback.
 272  * @fn: function to be called for each device.
 273  *
 274  * Iterate over @bus's list of devices, and call @fn for each,
 275  * passing it @data. If @start is not NULL, we use that device to
 276  * begin iterating from.
 277  *
 278  * We check the return of @fn each time. If it returns anything
 279  * other than 0, we break out and return that value.
 280  *
 281  * NOTE: The device that returns a non-zero value is not retained
 282  * in any way, nor is its refcount incremented. If the caller needs
 283  * to retain this data, it should do so, and increment the reference
 284  * count in the supplied callback.
 285  */
 286 int bus_for_each_dev(struct bus_type *bus, struct device *start,
 287                      void *data, int (*fn)(struct device *, void *))
 288 {
 289         struct klist_iter i;
 290         struct device *dev;
 291         int error = 0;
 292
 293         if (!bus)
 294                 return -EINVAL;
 295
 296         klist_iter_init_node(&bus->p->klist_devices, &i,
 297                              (start ? &start->p->knode_bus : NULL));
 298         while ((dev = next_device(&i)) && !error)
 299                 error = fn(dev, data);
 300         klist_iter_exit(&i);
 301         return error;
 302 }
 303 EXPORT_SYMBOL_GPL(bus_for_each_dev);
 304
 305 /**
 306  * bus_find_device - device iterator for locating a particular device.
 307  * @bus: bus type
 308  * @start: Device to begin with
 309  * @data: Data to pass to match function
 310  * @match: Callback function to check device
 311  *
 312  * This is similar to the bus_for_each_dev() function above, but it
 313  * returns a reference to a device that is 'found' for later use, as
 314  * determined by the @match callback.
 315  *
 316  * The callback should return 0 if the device doesn't match and non-zero
 317  * if it does.  If the callback returns non-zero, this function will
 318  * return to the caller and not iterate over any more devices.
 319  */
 320 struct device *bus_find_device(struct bus_type *bus,
 321                                struct device *start, void *data,
 322                                int (*match)(struct device *dev, void *data))
 323 {
 324         struct klist_iter i;
 325         struct device *dev;
 326
 327         if (!bus)
 328                 return NULL;
 329
 330         klist_iter_init_node(&bus->p->klist_devices, &i,
 331                              (start ? &start->p->knode_bus : NULL));
 332         while ((dev = next_device(&i)))
 333                 if (match(dev, data) && get_device(dev))
 334                         break;
 335         klist_iter_exit(&i);
 336         return dev;
 337 }
 338 EXPORT_SYMBOL_GPL(bus_find_device);
 339
 340 static int match_name(struct device *dev, void *data)
 341 {
 342         const char *name = data;
 343
 344         return sysfs_streq(name, dev_name(dev));
 345 }
 346
 347 /**
 348  * bus_find_device_by_name - device iterator for locating a particular device of a specific name
 349  * @bus: bus type
 350  * @start: Device to begin with
 351  * @name: name of the device to match
 352  *
 353  * This is similar to the bus_find_device() function above, but it handles
 354  * searching by a name automatically, no need to write another strcmp matching
 355  * function.
 356  */
 357 struct device *bus_find_device_by_name(struct bus_type *bus,
 358                                        struct device *start, const char *name)
 359 {
 360         return bus_find_device(bus, start, (void *)name, match_name);
 361 }
 362 EXPORT_SYMBOL_GPL(bus_find_device_by_name);
 363
 364 static struct device_driver *next_driver(struct klist_iter *i)
 365 {
 366         struct klist_node *n = klist_next(i);
 367         struct driver_private *drv_priv;
 368
 369         if (n) {
 370                 drv_priv = container_of(n, struct driver_private, knode_bus);
 371                 return drv_priv->driver;
 372         }
 373         return NULL;
 374 }
 375
 376 /**
 377  * bus_for_each_drv - driver iterator
 378  * @bus: bus we're dealing with.
 379  * @start: driver to start iterating on.
 380  * @data: data to pass to the callback.
 381  * @fn: function to call for each driver.
 382  *
 383  * This is nearly identical to the device iterator above.
 384  * We iterate over each driver that belongs to @bus, and call
 385  * @fn for each. If @fn returns anything but 0, we break out
 386  * and return it. If @start is not NULL, we use it as the head
 387  * of the list.
 388  *
 389  * NOTE: we don't return the driver that returns a non-zero
 390  * value, nor do we leave the reference count incremented for that
 391  * driver. If the caller needs to know that info, it must set it
 392  * in the callback. It must also be sure to increment the refcount
 393  * so it doesn't disappear before returning to the caller.
 394  */
 395 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
 396                      void *data, int (*fn)(struct device_driver *, void *))
 397 {
 398         struct klist_iter i;
 399         struct device_driver *drv;
 400         int error = 0;
 401
 402         if (!bus)
 403                 return -EINVAL;
 404
 405         klist_iter_init_node(&bus->p->klist_drivers, &i,
 406                              start ? &start->p->knode_bus : NULL);
 407         while ((drv = next_driver(&i)) && !error)
 408                 error = fn(drv, data);
 409         klist_iter_exit(&i);
 410         return error;
 411 }
 412 EXPORT_SYMBOL_GPL(bus_for_each_drv);
 413
 414 static int device_add_attrs(struct bus_type *bus, struct device *dev)
 415 {
 416         int error = 0;
 417         int i;
 418
 419         if (!bus->dev_attrs)
 420                 return 0;
 421
 422         for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
 423                 error = device_create_file(dev, &bus->dev_attrs[i]);
 424                 if (error) {
 425                         while (--i >= 0)
 426                                 device_remove_file(dev, &bus->dev_attrs[i]);
 427                         break;
 428                 }
 429         }
 430         return error;
 431 }
 432
 433 static void device_remove_attrs(struct bus_type *bus, struct device *dev)
 434 {
 435         int i;
 436
 437         if (bus->dev_attrs) {
 438                 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
 439                         device_remove_file(dev, &bus->dev_attrs[i]);
 440         }
 441 }
 442
 443 #ifdef CONFIG_SYSFS_DEPRECATED
 444 static int make_deprecated_bus_links(struct device *dev)
 445 {
 446         return sysfs_create_link(&dev->kobj,
 447                                  &dev->bus->p->subsys.kobj, "bus");
 448 }
 449
 450 static void remove_deprecated_bus_links(struct device *dev)
 451 {
 452         sysfs_remove_link(&dev->kobj, "bus");
 453 }
 454 #else
 455 static inline int make_deprecated_bus_links(struct device *dev) { return 0; }
 456 static inline void remove_deprecated_bus_links(struct device *dev) { }
 457 #endif
 458
 459 /**
 460  * bus_add_device - add device to bus
 461  * @dev: device being added
 462  *
 463  * - Add device's bus attributes.
 464  * - Create links to device's bus.
 465  * - Add the device to its bus's list of devices.
 466  */
 467 int bus_add_device(struct device *dev)
 468 {
 469         struct bus_type *bus = bus_get(dev->bus);
 470         int error = 0;
 471
 472         if (bus) {
 473                 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
 474                 error = device_add_attrs(bus, dev);
 475                 if (error)
 476                         goto out_put;
 477                 error = sysfs_create_link(&bus->p->devices_kset->kobj,
 478                                                 &dev->kobj, dev_name(dev));
 479                 if (error)
 480                         goto out_id;
 481                 error = sysfs_create_link(&dev->kobj,
 482                                 &dev->bus->p->subsys.kobj, "subsystem");
 483                 if (error)
 484                         goto out_subsys;
 485                 error = make_deprecated_bus_links(dev);
 486                 if (error)
 487                         goto out_deprecated;
 488                 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
 489         }
 490         return 0;
 491
 492 out_deprecated:
 493         sysfs_remove_link(&dev->kobj, "subsystem");
 494 out_subsys:
 495         sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
 496 out_id:
 497         device_remove_attrs(bus, dev);
 498 out_put:
 499         bus_put(dev->bus);
 500         return error;
 501 }
 502
 503 /**
 504  * bus_probe_device - probe drivers for a new device
 505  * @dev: device to probe
 506  *
 507  * - Automatically probe for a driver if the bus allows it.
 508  */
 509 void bus_probe_device(struct device *dev)
 510 {
 511         struct bus_type *bus = dev->bus;
 512         int ret;
 513
 514         if (bus && bus->p->drivers_autoprobe) {
 515                 ret = device_attach(dev);
 516                 WARN_ON(ret < 0);
 517         }
 518 }
 519
 520 /**
 521  * bus_remove_device - remove device from bus
 522  * @dev: device to be removed
 523  *
 524  * - Remove symlink from bus's directory.
 525  * - Delete device from bus's list.
 526  * - Detach from its driver.
 527  * - Drop reference taken in bus_add_device().
 528  */
 529 void bus_remove_device(struct device *dev)
 530 {
 531         if (dev->bus) {
 532                 sysfs_remove_link(&dev->kobj, "subsystem");
 533                 remove_deprecated_bus_links(dev);
 534                 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
 535                                   dev_name(dev));
 536                 device_remove_attrs(dev->bus, dev);
 537                 if (klist_node_attached(&dev->p->knode_bus))
 538                         klist_del(&dev->p->knode_bus);
 539
 540                 pr_debug("bus: '%s': remove device %s\n",
 541                          dev->bus->name, dev_name(dev));
 542                 device_release_driver(dev);
 543                 bus_put(dev->bus);
 544         }
 545 }
 546
 547 static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
 548 {
 549         int error = 0;
 550         int i;
 551
 552         if (bus->drv_attrs) {
 553                 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
 554                         error = driver_create_file(drv, &bus->drv_attrs[i]);
 555                         if (error)
 556                                 goto err;
 557                 }
 558         }
 559 done:
 560         return error;
 561 err:
 562         while (--i >= 0)
 563                 driver_remove_file(drv, &bus->drv_attrs[i]);
 564         goto done;
 565 }
 566
 567 static void driver_remove_attrs(struct bus_type *bus,
 568                                 struct device_driver *drv)
 569 {
 570         int i;
 571
 572         if (bus->drv_attrs) {
 573                 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
 574                         driver_remove_file(drv, &bus->drv_attrs[i]);
 575         }
 576 }
 577
 578 #ifdef CONFIG_HOTPLUG
 579 /*
 580  * Thanks to drivers making their tables __devinit, we can't allow manual
 581  * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
 582  */
 583 static int __must_check add_bind_files(struct device_driver *drv)
 584 {
 585         int ret;
 586
 587         ret = driver_create_file(drv, &driver_attr_unbind);
 588         if (ret == 0) {
 589                 ret = driver_create_file(drv, &driver_attr_bind);
 590                 if (ret)
 591                         driver_remove_file(drv, &driver_attr_unbind);
 592         }
 593         return ret;
 594 }
 595
 596 static void remove_bind_files(struct device_driver *drv)
 597 {
 598         driver_remove_file(drv, &driver_attr_bind);
 599         driver_remove_file(drv, &driver_attr_unbind);
 600 }
 601
 602 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
 603 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
 604                 show_drivers_autoprobe, store_drivers_autoprobe);
 605
 606 static int add_probe_files(struct bus_type *bus)
 607 {
 608         int retval;
 609
 610         retval = bus_create_file(bus, &bus_attr_drivers_probe);
 611         if (retval)
 612                 goto out;
 613
 614         retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
 615         if (retval)
 616                 bus_remove_file(bus, &bus_attr_drivers_probe);
 617 out:
 618         return retval;
 619 }
 620
 621 static void remove_probe_files(struct bus_type *bus)
 622 {
 623         bus_remove_file(bus, &bus_attr_drivers_autoprobe);
 624         bus_remove_file(bus, &bus_attr_drivers_probe);
 625 }
 626 #else
 627 static inline int add_bind_files(struct device_driver *drv) { return 0; }
 628 static inline void remove_bind_files(struct device_driver *drv) {}
 629 static inline int add_probe_files(struct bus_type *bus) { return 0; }
 630 static inline void remove_probe_files(struct bus_type *bus) {}
 631 #endif
 632
 633 static ssize_t driver_uevent_store(struct device_driver *drv,
 634                                    const char *buf, size_t count)
 635 {
 636         enum kobject_action action;
 637
 638         if (kobject_action_type(buf, count, &action) == 0)
 639                 kobject_uevent(&drv->p->kobj, action);
 640         return count;
 641 }
 642 static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
 643
 644 /**
 645  * bus_add_driver - Add a driver to the bus.
 646  * @drv: driver.
 647  */
 648 int bus_add_driver(struct device_driver *drv)
 649 {
 650         struct bus_type *bus;
 651         struct driver_private *priv;
 652         int error = 0;
 653
 654         bus = bus_get(drv->bus);
 655         if (!bus)
 656                 return -EINVAL;
 657
 658         pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
 659
 660         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 661         if (!priv) {
 662                 error = -ENOMEM;
 663                 goto out_put_bus;
 664         }
 665         klist_init(&priv->klist_devices, NULL, NULL);
 666         priv->driver = drv;
 667         drv->p = priv;
 668         priv->kobj.kset = bus->p->drivers_kset;
 669         error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
 670                                      "%s", drv->name);
 671         if (error)
 672                 goto out_unregister;
 673
 674         if (drv->bus->p->drivers_autoprobe) {
 675                 error = driver_attach(drv);
 676                 if (error)
 677                         goto out_unregister;
 678         }
 679         klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
 680         module_add_driver(drv->owner, drv);
 681
 682         error = driver_create_file(drv, &driver_attr_uevent);
 683         if (error) {
 684                 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
 685                         __func__, drv->name);
 686         }
 687         error = driver_add_attrs(bus, drv);
 688         if (error) {
 689                 /* How the hell do we get out of this pickle? Give up */
 690                 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
 691                         __func__, drv->name);
 692         }
 693
 694         if (!drv->suppress_bind_attrs) {
 695                 error = add_bind_files(drv);
 696                 if (error) {
 697                         /* Ditto */
 698                         printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
 699                                 __func__, drv->name);
 700                 }
 701         }
 702
 703         kobject_uevent(&priv->kobj, KOBJ_ADD);
 704         return 0;
 705
 706 out_unregister:
 707         kobject_put(&priv->kobj);
 708         kfree(drv->p);
 709         drv->p = NULL;
 710 out_put_bus:
 711         bus_put(bus);
 712         return error;
 713 }
 714
 715 /**
 716  * bus_remove_driver - delete driver from bus's knowledge.
 717  * @drv: driver.
 718  *
 719  * Detach the driver from the devices it controls, and remove
 720  * it from its bus's list of drivers. Finally, we drop the reference
 721  * to the bus we took in bus_add_driver().
 722  */
 723 void bus_remove_driver(struct device_driver *drv)
 724 {
 725         if (!drv->bus)
 726                 return;
 727
 728         if (!drv->suppress_bind_attrs)
 729                 remove_bind_files(drv);
 730         driver_remove_attrs(drv->bus, drv);
 731         driver_remove_file(drv, &driver_attr_uevent);
 732         klist_remove(&drv->p->knode_bus);
 733         pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
 734         driver_detach(drv);
 735         module_remove_driver(drv);
 736         kobject_put(&drv->p->kobj);
 737         bus_put(drv->bus);
 738 }
 739
 740 /* Helper for bus_rescan_devices's iter */
 741 static int __must_check bus_rescan_devices_helper(struct device *dev,
 742                                                   void *data)
 743 {
 744         int ret = 0;
 745
 746         if (!dev->driver) {
 747                 if (dev->parent)        /* Needed for USB */
 748                         device_lock(dev->parent);
 749                 ret = device_attach(dev);
 750                 if (dev->parent)
 751                         device_unlock(dev->parent);
 752         }
 753         return ret < 0 ? ret : 0;
 754 }
 755
 756 /**
 757  * bus_rescan_devices - rescan devices on the bus for possible drivers
 758  * @bus: the bus to scan.
 759  *
 760  * This function will look for devices on the bus with no driver
 761  * attached and rescan it against existing drivers to see if it matches
 762  * any by calling device_attach() for the unbound devices.
 763  */
 764 int bus_rescan_devices(struct bus_type *bus)
 765 {
 766         return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
 767 }
 768 EXPORT_SYMBOL_GPL(bus_rescan_devices);
 769
 770 /**
 771  * device_reprobe - remove driver for a device and probe for a new driver
 772  * @dev: the device to reprobe
 773  *
 774  * This function detaches the attached driver (if any) for the given
 775  * device and restarts the driver probing process.  It is intended
 776  * to use if probing criteria changed during a devices lifetime and
 777  * driver attachment should change accordingly.
 778  */
 779 int device_reprobe(struct device *dev)
 780 {
 781         if (dev->driver) {
 782                 if (dev->parent)        /* Needed for USB */
 783                         device_lock(dev->parent);
 784                 device_release_driver(dev);
 785                 if (dev->parent)
 786                         device_unlock(dev->parent);
 787         }
 788         return bus_rescan_devices_helper(dev, NULL);
 789 }
 790 EXPORT_SYMBOL_GPL(device_reprobe);
 791
 792 /**
 793  * find_bus - locate bus by name.
 794  * @name: name of bus.
 795  *
 796  * Call kset_find_obj() to iterate over list of buses to
 797  * find a bus by name. Return bus if found.
 798  *
 799  * Note that kset_find_obj increments bus' reference count.
 800  */
 801 #if 0
 802 struct bus_type *find_bus(char *name)
 803 {
 804         struct kobject *k = kset_find_obj(bus_kset, name);
 805         return k ? to_bus(k) : NULL;
 806 }
 807 #endif  /*  0  */
 808
 809
 810 /**
 811  * bus_add_attrs - Add default attributes for this bus.
 812  * @bus: Bus that has just been registered.
 813  */
 814
 815 static int bus_add_attrs(struct bus_type *bus)
 816 {
 817         int error = 0;
 818         int i;
 819
 820         if (bus->bus_attrs) {
 821                 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
 822                         error = bus_create_file(bus, &bus->bus_attrs[i]);
 823                         if (error)
 824                                 goto err;
 825                 }
 826         }
 827 done:
 828         return error;
 829 err:
 830         while (--i >= 0)
 831                 bus_remove_file(bus, &bus->bus_attrs[i]);
 832         goto done;
 833 }
 834
 835 static void bus_remove_attrs(struct bus_type *bus)
 836 {
 837         int i;
 838
 839         if (bus->bus_attrs) {
 840                 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
 841                         bus_remove_file(bus, &bus->bus_attrs[i]);
 842         }
 843 }
 844
 845 static void klist_devices_get(struct klist_node *n)
 846 {
 847         struct device_private *dev_prv = to_device_private_bus(n);
 848         struct device *dev = dev_prv->device;
 849
 850         get_device(dev);
 851 }
 852
 853 static void klist_devices_put(struct klist_node *n)
 854 {
 855         struct device_private *dev_prv = to_device_private_bus(n);
 856         struct device *dev = dev_prv->device;
 857
 858         put_device(dev);
 859 }
 860
 861 static ssize_t bus_uevent_store(struct bus_type *bus,
 862                                 const char *buf, size_t count)
 863 {
 864         enum kobject_action action;
 865
 866         if (kobject_action_type(buf, count, &action) == 0)
 867                 kobject_uevent(&bus->p->subsys.kobj, action);
 868         return count;
 869 }
 870 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
 871
 872 /**
 873  * bus_register - register a bus with the system.
 874  * @bus: bus.
 875  *
 876  * Once we have that, we registered the bus with the kobject
 877  * infrastructure, then register the children subsystems it has:
 878  * the devices and drivers that belong to the bus.
 879  */
 880 int bus_register(struct bus_type *bus)
 881 {
 882         int retval;
 883         struct bus_type_private *priv;
 884
 885         priv = kzalloc(sizeof(struct bus_type_private), GFP_KERNEL);
 886         if (!priv)
 887                 return -ENOMEM;
 888
 889         priv->bus = bus;
 890         bus->p = priv;
 891
 892         BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
 893
 894         retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
 895         if (retval)
 896                 goto out;
 897
 898         priv->subsys.kobj.kset = bus_kset;
 899         priv->subsys.kobj.ktype = &bus_ktype;
 900         priv->drivers_autoprobe = 1;
 901
 902         retval = kset_register(&priv->subsys);
 903         if (retval)
 904                 goto out;
 905
 906         retval = bus_create_file(bus, &bus_attr_uevent);
 907         if (retval)
 908                 goto bus_uevent_fail;
 909
 910         priv->devices_kset = kset_create_and_add("devices", NULL,
 911                                                  &priv->subsys.kobj);
 912         if (!priv->devices_kset) {
 913                 retval = -ENOMEM;
 914                 goto bus_devices_fail;
 915         }
 916
 917         priv->drivers_kset = kset_create_and_add("drivers", NULL,
 918                                                  &priv->subsys.kobj);
 919         if (!priv->drivers_kset) {
 920                 retval = -ENOMEM;
 921                 goto bus_drivers_fail;
 922         }
 923
 924         klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
 925         klist_init(&priv->klist_drivers, NULL, NULL);
 926
 927         retval = add_probe_files(bus);
 928         if (retval)
 929                 goto bus_probe_files_fail;
 930
 931         retval = bus_add_attrs(bus);
 932         if (retval)
 933                 goto bus_attrs_fail;
 934
 935         pr_debug("bus: '%s': registered\n", bus->name);
 936         return 0;
 937
 938 bus_attrs_fail:
 939         remove_probe_files(bus);
 940 bus_probe_files_fail:
 941         kset_unregister(bus->p->drivers_kset);
 942 bus_drivers_fail:
 943         kset_unregister(bus->p->devices_kset);
 944 bus_devices_fail:
 945         bus_remove_file(bus, &bus_attr_uevent);
 946 bus_uevent_fail:
 947         kset_unregister(&bus->p->subsys);
 948 out:
 949         kfree(bus->p);
 950         bus->p = NULL;
 951         return retval;
 952 }
 953 EXPORT_SYMBOL_GPL(bus_register);
 954
 955 /**
 956  * bus_unregister - remove a bus from the system
 957  * @bus: bus.
 958  *
 959  * Unregister the child subsystems and the bus itself.
 960  * Finally, we call bus_put() to release the refcount
 961  */
 962 void bus_unregister(struct bus_type *bus)
 963 {
 964         pr_debug("bus: '%s': unregistering\n", bus->name);
 965         bus_remove_attrs(bus);
 966         remove_probe_files(bus);
 967         kset_unregister(bus->p->drivers_kset);
 968         kset_unregister(bus->p->devices_kset);
 969         bus_remove_file(bus, &bus_attr_uevent);
 970         kset_unregister(&bus->p->subsys);
 971         kfree(bus->p);
 972         bus->p = NULL;
 973 }
 974 EXPORT_SYMBOL_GPL(bus_unregister);
 975
 976 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
 977 {
 978         return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
 979 }
 980 EXPORT_SYMBOL_GPL(bus_register_notifier);
 981
 982 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
 983 {
 984         return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
 985 }
 986 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
 987
 988 struct kset *bus_get_kset(struct bus_type *bus)
 989 {
 990         return &bus->p->subsys;
 991 }
 992 EXPORT_SYMBOL_GPL(bus_get_kset);
 993
 994 struct klist *bus_get_device_klist(struct bus_type *bus)
 995 {
 996         return &bus->p->klist_devices;
 997 }
 998 EXPORT_SYMBOL_GPL(bus_get_device_klist);
 999
1000 /*
1001  * Yes, this forcably breaks the klist abstraction temporarily.  It
1002  * just wants to sort the klist, not change reference counts and
1003  * take/drop locks rapidly in the process.  It does all this while
1004  * holding the lock for the list, so objects can't otherwise be
1005  * added/removed while we're swizzling.
1006  */
1007 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1008                                         int (*compare)(const struct device *a,
1009                                                         const struct device *b))
1010 {
1011         struct list_head *pos;
1012         struct klist_node *n;
1013         struct device_private *dev_prv;
1014         struct device *b;
1015
1016         list_for_each(pos, list) {
1017                 n = container_of(pos, struct klist_node, n_node);
1018                 dev_prv = to_device_private_bus(n);
1019                 b = dev_prv->device;
1020                 if (compare(a, b) <= 0) {
1021                         list_move_tail(&a->p->knode_bus.n_node,
1022                                        &b->p->knode_bus.n_node);
1023                         return;
1024                 }
1025         }
1026         list_move_tail(&a->p->knode_bus.n_node, list);
1027 }
1028
1029 void bus_sort_breadthfirst(struct bus_type *bus,
1030                            int (*compare)(const struct device *a,
1031                                           const struct device *b))
1032 {
1033         LIST_HEAD(sorted_devices);
1034         struct list_head *pos, *tmp;
1035         struct klist_node *n;
1036         struct device_private *dev_prv;
1037         struct device *dev;
1038         struct klist *device_klist;
1039
1040         device_klist = bus_get_device_klist(bus);
1041
1042         spin_lock(&device_klist->k_lock);
1043         list_for_each_safe(pos, tmp, &device_klist->k_list) {
1044                 n = container_of(pos, struct klist_node, n_node);
1045                 dev_prv = to_device_private_bus(n);
1046                 dev = dev_prv->device;
1047                 device_insertion_sort_klist(dev, &sorted_devices, compare);
1048         }
1049         list_splice(&sorted_devices, &device_klist->k_list);
1050         spin_unlock(&device_klist->k_lock);
1051 }
1052 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1053
1054 int __init buses_init(void)
1055 {
1056         bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1057         if (!bus_kset)
1058                 return -ENOMEM;
1059         return 0;
1060 }