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, 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 the device to its bus's list of devices.
 463  * - Create link to device's bus.
 464  */
 465 int bus_add_device(struct device *dev)
 466 {
 467         struct bus_type *bus = bus_get(dev->bus);
 468         int error = 0;
 469
 470         if (bus) {
 471                 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
 472                 error = device_add_attrs(bus, dev);
 473                 if (error)
 474                         goto out_put;
 475                 error = sysfs_create_link(&bus->p->devices_kset->kobj,
 476                                                 &dev->kobj, dev_name(dev));
 477                 if (error)
 478                         goto out_id;
 479                 error = sysfs_create_link(&dev->kobj,
 480                                 &dev->bus->p->subsys.kobj, "subsystem");
 481                 if (error)
 482                         goto out_subsys;
 483                 error = make_deprecated_bus_links(dev);
 484                 if (error)
 485                         goto out_deprecated;
 486         }
 487         return 0;
 488
 489 out_deprecated:
 490         sysfs_remove_link(&dev->kobj, "subsystem");
 491 out_subsys:
 492         sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
 493 out_id:
 494         device_remove_attrs(bus, dev);
 495 out_put:
 496         bus_put(dev->bus);
 497         return error;
 498 }
 499
 500 /**
 501  * bus_attach_device - add device to bus
 502  * @dev: device tried to attach to a driver
 503  *
 504  * - Add device to bus's list of devices.
 505  * - Try to attach to driver.
 506  */
 507 void bus_attach_device(struct device *dev)
 508 {
 509         struct bus_type *bus = dev->bus;
 510         int ret = 0;
 511
 512         if (bus) {
 513                 if (bus->p->drivers_autoprobe)
 514                         ret = device_attach(dev);
 515                 WARN_ON(ret < 0);
 516                 if (ret >= 0)
 517                         klist_add_tail(&dev->p->knode_bus,
 518                                        &bus->p->klist_devices);
 519         }
 520 }
 521
 522 /**
 523  * bus_remove_device - remove device from bus
 524  * @dev: device to be removed
 525  *
 526  * - Remove symlink from bus's directory.
 527  * - Delete device from bus's list.
 528  * - Detach from its driver.
 529  * - Drop reference taken in bus_add_device().
 530  */
 531 void bus_remove_device(struct device *dev)
 532 {
 533         if (dev->bus) {
 534                 sysfs_remove_link(&dev->kobj, "subsystem");
 535                 remove_deprecated_bus_links(dev);
 536                 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
 537                                   dev_name(dev));
 538                 device_remove_attrs(dev->bus, dev);
 539                 if (klist_node_attached(&dev->p->knode_bus))
 540                         klist_del(&dev->p->knode_bus);
 541
 542                 pr_debug("bus: '%s': remove device %s\n",
 543                          dev->bus->name, dev_name(dev));
 544                 device_release_driver(dev);
 545                 bus_put(dev->bus);
 546         }
 547 }
 548
 549 static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
 550 {
 551         int error = 0;
 552         int i;
 553
 554         if (bus->drv_attrs) {
 555                 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
 556                         error = driver_create_file(drv, &bus->drv_attrs[i]);
 557                         if (error)
 558                                 goto err;
 559                 }
 560         }
 561 done:
 562         return error;
 563 err:
 564         while (--i >= 0)
 565                 driver_remove_file(drv, &bus->drv_attrs[i]);
 566         goto done;
 567 }
 568
 569 static void driver_remove_attrs(struct bus_type *bus,
 570                                 struct device_driver *drv)
 571 {
 572         int i;
 573
 574         if (bus->drv_attrs) {
 575                 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
 576                         driver_remove_file(drv, &bus->drv_attrs[i]);
 577         }
 578 }
 579
 580 #ifdef CONFIG_HOTPLUG
 581 /*
 582  * Thanks to drivers making their tables __devinit, we can't allow manual
 583  * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
 584  */
 585 static int __must_check add_bind_files(struct device_driver *drv)
 586 {
 587         int ret;
 588
 589         ret = driver_create_file(drv, &driver_attr_unbind);
 590         if (ret == 0) {
 591                 ret = driver_create_file(drv, &driver_attr_bind);
 592                 if (ret)
 593                         driver_remove_file(drv, &driver_attr_unbind);
 594         }
 595         return ret;
 596 }
 597
 598 static void remove_bind_files(struct device_driver *drv)
 599 {
 600         driver_remove_file(drv, &driver_attr_bind);
 601         driver_remove_file(drv, &driver_attr_unbind);
 602 }
 603
 604 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
 605 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
 606                 show_drivers_autoprobe, store_drivers_autoprobe);
 607
 608 static int add_probe_files(struct bus_type *bus)
 609 {
 610         int retval;
 611
 612         retval = bus_create_file(bus, &bus_attr_drivers_probe);
 613         if (retval)
 614                 goto out;
 615
 616         retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
 617         if (retval)
 618                 bus_remove_file(bus, &bus_attr_drivers_probe);
 619 out:
 620         return retval;
 621 }
 622
 623 static void remove_probe_files(struct bus_type *bus)
 624 {
 625         bus_remove_file(bus, &bus_attr_drivers_autoprobe);
 626         bus_remove_file(bus, &bus_attr_drivers_probe);
 627 }
 628 #else
 629 static inline int add_bind_files(struct device_driver *drv) { return 0; }
 630 static inline void remove_bind_files(struct device_driver *drv) {}
 631 static inline int add_probe_files(struct bus_type *bus) { return 0; }
 632 static inline void remove_probe_files(struct bus_type *bus) {}
 633 #endif
 634
 635 static ssize_t driver_uevent_store(struct device_driver *drv,
 636                                    const char *buf, size_t count)
 637 {
 638         enum kobject_action action;
 639
 640         if (kobject_action_type(buf, count, &action) == 0)
 641                 kobject_uevent(&drv->p->kobj, action);
 642         return count;
 643 }
 644 static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
 645
 646 /**
 647  * bus_add_driver - Add a driver to the bus.
 648  * @drv: driver.
 649  */
 650 int bus_add_driver(struct device_driver *drv)
 651 {
 652         struct bus_type *bus;
 653         struct driver_private *priv;
 654         int error = 0;
 655
 656         bus = bus_get(drv->bus);
 657         if (!bus)
 658                 return -EINVAL;
 659
 660         pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
 661
 662         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 663         if (!priv) {
 664                 error = -ENOMEM;
 665                 goto out_put_bus;
 666         }
 667         klist_init(&priv->klist_devices, NULL, NULL);
 668         priv->driver = drv;
 669         drv->p = priv;
 670         priv->kobj.kset = bus->p->drivers_kset;
 671         error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
 672                                      "%s", drv->name);
 673         if (error)
 674                 goto out_unregister;
 675
 676         if (drv->bus->p->drivers_autoprobe) {
 677                 error = driver_attach(drv);
 678                 if (error)
 679                         goto out_unregister;
 680         }
 681         klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
 682         module_add_driver(drv->owner, drv);
 683
 684         error = driver_create_file(drv, &driver_attr_uevent);
 685         if (error) {
 686                 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
 687                         __func__, drv->name);
 688         }
 689         error = driver_add_attrs(bus, drv);
 690         if (error) {
 691                 /* How the hell do we get out of this pickle? Give up */
 692                 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
 693                         __func__, drv->name);
 694         }
 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         kobject_uevent(&priv->kobj, KOBJ_ADD);
 703         return 0;
 704 out_unregister:
 705         kfree(drv->p);
 706         drv->p = NULL;
 707         kobject_put(&priv->kobj);
 708 out_put_bus:
 709         bus_put(bus);
 710         return error;
 711 }
 712
 713 /**
 714  * bus_remove_driver - delete driver from bus's knowledge.
 715  * @drv: driver.
 716  *
 717  * Detach the driver from the devices it controls, and remove
 718  * it from its bus's list of drivers. Finally, we drop the reference
 719  * to the bus we took in bus_add_driver().
 720  */
 721 void bus_remove_driver(struct device_driver *drv)
 722 {
 723         if (!drv->bus)
 724                 return;
 725
 726         remove_bind_files(drv);
 727         driver_remove_attrs(drv->bus, drv);
 728         driver_remove_file(drv, &driver_attr_uevent);
 729         klist_remove(&drv->p->knode_bus);
 730         pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
 731         driver_detach(drv);
 732         module_remove_driver(drv);
 733         kobject_put(&drv->p->kobj);
 734         bus_put(drv->bus);
 735 }
 736
 737 /* Helper for bus_rescan_devices's iter */
 738 static int __must_check bus_rescan_devices_helper(struct device *dev,
 739                                                   void *data)
 740 {
 741         int ret = 0;
 742
 743         if (!dev->driver) {
 744                 if (dev->parent)        /* Needed for USB */
 745                         down(&dev->parent->sem);
 746                 ret = device_attach(dev);
 747                 if (dev->parent)
 748                         up(&dev->parent->sem);
 749         }
 750         return ret < 0 ? ret : 0;
 751 }
 752
 753 /**
 754  * bus_rescan_devices - rescan devices on the bus for possible drivers
 755  * @bus: the bus to scan.
 756  *
 757  * This function will look for devices on the bus with no driver
 758  * attached and rescan it against existing drivers to see if it matches
 759  * any by calling device_attach() for the unbound devices.
 760  */
 761 int bus_rescan_devices(struct bus_type *bus)
 762 {
 763         return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
 764 }
 765 EXPORT_SYMBOL_GPL(bus_rescan_devices);
 766
 767 /**
 768  * device_reprobe - remove driver for a device and probe for a new driver
 769  * @dev: the device to reprobe
 770  *
 771  * This function detaches the attached driver (if any) for the given
 772  * device and restarts the driver probing process.  It is intended
 773  * to use if probing criteria changed during a devices lifetime and
 774  * driver attachment should change accordingly.
 775  */
 776 int device_reprobe(struct device *dev)
 777 {
 778         if (dev->driver) {
 779                 if (dev->parent)        /* Needed for USB */
 780                         down(&dev->parent->sem);
 781                 device_release_driver(dev);
 782                 if (dev->parent)
 783                         up(&dev->parent->sem);
 784         }
 785         return bus_rescan_devices_helper(dev, NULL);
 786 }
 787 EXPORT_SYMBOL_GPL(device_reprobe);
 788
 789 /**
 790  * find_bus - locate bus by name.
 791  * @name: name of bus.
 792  *
 793  * Call kset_find_obj() to iterate over list of buses to
 794  * find a bus by name. Return bus if found.
 795  *
 796  * Note that kset_find_obj increments bus' reference count.
 797  */
 798 #if 0
 799 struct bus_type *find_bus(char *name)
 800 {
 801         struct kobject *k = kset_find_obj(bus_kset, name);
 802         return k ? to_bus(k) : NULL;
 803 }
 804 #endif  /*  0  */
 805
 806
 807 /**
 808  * bus_add_attrs - Add default attributes for this bus.
 809  * @bus: Bus that has just been registered.
 810  */
 811
 812 static int bus_add_attrs(struct bus_type *bus)
 813 {
 814         int error = 0;
 815         int i;
 816
 817         if (bus->bus_attrs) {
 818                 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
 819                         error = bus_create_file(bus, &bus->bus_attrs[i]);
 820                         if (error)
 821                                 goto err;
 822                 }
 823         }
 824 done:
 825         return error;
 826 err:
 827         while (--i >= 0)
 828                 bus_remove_file(bus, &bus->bus_attrs[i]);
 829         goto done;
 830 }
 831
 832 static void bus_remove_attrs(struct bus_type *bus)
 833 {
 834         int i;
 835
 836         if (bus->bus_attrs) {
 837                 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
 838                         bus_remove_file(bus, &bus->bus_attrs[i]);
 839         }
 840 }
 841
 842 static void klist_devices_get(struct klist_node *n)
 843 {
 844         struct device_private *dev_prv = to_device_private_bus(n);
 845         struct device *dev = dev_prv->device;
 846
 847         get_device(dev);
 848 }
 849
 850 static void klist_devices_put(struct klist_node *n)
 851 {
 852         struct device_private *dev_prv = to_device_private_bus(n);
 853         struct device *dev = dev_prv->device;
 854
 855         put_device(dev);
 856 }
 857
 858 static ssize_t bus_uevent_store(struct bus_type *bus,
 859                                 const char *buf, size_t count)
 860 {
 861         enum kobject_action action;
 862
 863         if (kobject_action_type(buf, count, &action) == 0)
 864                 kobject_uevent(&bus->p->subsys.kobj, action);
 865         return count;
 866 }
 867 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
 868
 869 /**
 870  * bus_register - register a bus with the system.
 871  * @bus: bus.
 872  *
 873  * Once we have that, we registered the bus with the kobject
 874  * infrastructure, then register the children subsystems it has:
 875  * the devices and drivers that belong to the bus.
 876  */
 877 int bus_register(struct bus_type *bus)
 878 {
 879         int retval;
 880         struct bus_type_private *priv;
 881
 882         priv = kzalloc(sizeof(struct bus_type_private), GFP_KERNEL);
 883         if (!priv)
 884                 return -ENOMEM;
 885
 886         priv->bus = bus;
 887         bus->p = priv;
 888
 889         BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
 890
 891         retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
 892         if (retval)
 893                 goto out;
 894
 895         priv->subsys.kobj.kset = bus_kset;
 896         priv->subsys.kobj.ktype = &bus_ktype;
 897         priv->drivers_autoprobe = 1;
 898
 899         retval = kset_register(&priv->subsys);
 900         if (retval)
 901                 goto out;
 902
 903         retval = bus_create_file(bus, &bus_attr_uevent);
 904         if (retval)
 905                 goto bus_uevent_fail;
 906
 907         priv->devices_kset = kset_create_and_add("devices", NULL,
 908                                                  &priv->subsys.kobj);
 909         if (!priv->devices_kset) {
 910                 retval = -ENOMEM;
 911                 goto bus_devices_fail;
 912         }
 913
 914         priv->drivers_kset = kset_create_and_add("drivers", NULL,
 915                                                  &priv->subsys.kobj);
 916         if (!priv->drivers_kset) {
 917                 retval = -ENOMEM;
 918                 goto bus_drivers_fail;
 919         }
 920
 921         klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
 922         klist_init(&priv->klist_drivers, NULL, NULL);
 923
 924         retval = add_probe_files(bus);
 925         if (retval)
 926                 goto bus_probe_files_fail;
 927
 928         retval = bus_add_attrs(bus);
 929         if (retval)
 930                 goto bus_attrs_fail;
 931
 932         pr_debug("bus: '%s': registered\n", bus->name);
 933         return 0;
 934
 935 bus_attrs_fail:
 936         remove_probe_files(bus);
 937 bus_probe_files_fail:
 938         kset_unregister(bus->p->drivers_kset);
 939 bus_drivers_fail:
 940         kset_unregister(bus->p->devices_kset);
 941 bus_devices_fail:
 942         bus_remove_file(bus, &bus_attr_uevent);
 943 bus_uevent_fail:
 944         kset_unregister(&bus->p->subsys);
 945         kfree(bus->p);
 946 out:
 947         bus->p = NULL;
 948         return retval;
 949 }
 950 EXPORT_SYMBOL_GPL(bus_register);
 951
 952 /**
 953  * bus_unregister - remove a bus from the system
 954  * @bus: bus.
 955  *
 956  * Unregister the child subsystems and the bus itself.
 957  * Finally, we call bus_put() to release the refcount
 958  */
 959 void bus_unregister(struct bus_type *bus)
 960 {
 961         pr_debug("bus: '%s': unregistering\n", bus->name);
 962         bus_remove_attrs(bus);
 963         remove_probe_files(bus);
 964         kset_unregister(bus->p->drivers_kset);
 965         kset_unregister(bus->p->devices_kset);
 966         bus_remove_file(bus, &bus_attr_uevent);
 967         kset_unregister(&bus->p->subsys);
 968         kfree(bus->p);
 969         bus->p = NULL;
 970 }
 971 EXPORT_SYMBOL_GPL(bus_unregister);
 972
 973 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
 974 {
 975         return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
 976 }
 977 EXPORT_SYMBOL_GPL(bus_register_notifier);
 978
 979 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
 980 {
 981         return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
 982 }
 983 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
 984
 985 struct kset *bus_get_kset(struct bus_type *bus)
 986 {
 987         return &bus->p->subsys;
 988 }
 989 EXPORT_SYMBOL_GPL(bus_get_kset);
 990
 991 struct klist *bus_get_device_klist(struct bus_type *bus)
 992 {
 993         return &bus->p->klist_devices;
 994 }
 995 EXPORT_SYMBOL_GPL(bus_get_device_klist);
 996
 997 /*
 998  * Yes, this forcably breaks the klist abstraction temporarily.  It
 999  * just wants to sort the klist, not change reference counts and
1000  * take/drop locks rapidly in the process.  It does all this while
1001  * holding the lock for the list, so objects can't otherwise be
1002  * added/removed while we're swizzling.
1003  */
1004 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1005                                         int (*compare)(const struct device *a,
1006                                                         const struct device *b))
1007 {
1008         struct list_head *pos;
1009         struct klist_node *n;
1010         struct device_private *dev_prv;
1011         struct device *b;
1012
1013         list_for_each(pos, list) {
1014                 n = container_of(pos, struct klist_node, n_node);
1015                 dev_prv = to_device_private_bus(n);
1016                 b = dev_prv->device;
1017                 if (compare(a, b) <= 0) {
1018                         list_move_tail(&a->p->knode_bus.n_node,
1019                                        &b->p->knode_bus.n_node);
1020                         return;
1021                 }
1022         }
1023         list_move_tail(&a->p->knode_bus.n_node, list);
1024 }
1025
1026 void bus_sort_breadthfirst(struct bus_type *bus,
1027                            int (*compare)(const struct device *a,
1028                                           const struct device *b))
1029 {
1030         LIST_HEAD(sorted_devices);
1031         struct list_head *pos, *tmp;
1032         struct klist_node *n;
1033         struct device_private *dev_prv;
1034         struct device *dev;
1035         struct klist *device_klist;
1036
1037         device_klist = bus_get_device_klist(bus);
1038
1039         spin_lock(&device_klist->k_lock);
1040         list_for_each_safe(pos, tmp, &device_klist->k_list) {
1041                 n = container_of(pos, struct klist_node, n_node);
1042                 dev_prv = to_device_private_bus(n);
1043                 dev = dev_prv->device;
1044                 device_insertion_sort_klist(dev, &sorted_devices, compare);
1045         }
1046         list_splice(&sorted_devices, &device_klist->k_list);
1047         spin_unlock(&device_klist->k_lock);
1048 }
1049 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1050
1051 int __init buses_init(void)
1052 {
1053         bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1054         if (!bus_kset)
1055                 return -ENOMEM;
1056         return 0;
1057 }