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