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), __FUNCTION__);
  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 int driver_helper(struct device *dev, void *data)
 167 {
 168         const char *name = data;
 169
 170         if (strcmp(name, dev->bus_id) == 0)
 171                 return 1;
 172         return 0;
 173 }
 174
 175 static ssize_t driver_unbind(struct device_driver *drv,
 176                              const char *buf, size_t count)
 177 {
 178         struct bus_type *bus = bus_get(drv->bus);
 179         struct device *dev;
 180         int err = -ENODEV;
 181
 182         dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
 183         if (dev && dev->driver == drv) {
 184                 if (dev->parent)        /* Needed for USB */
 185                         down(&dev->parent->sem);
 186                 device_release_driver(dev);
 187                 if (dev->parent)
 188                         up(&dev->parent->sem);
 189                 err = count;
 190         }
 191         put_device(dev);
 192         bus_put(bus);
 193         return err;
 194 }
 195 static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
 196
 197 /*
 198  * Manually attach a device to a driver.
 199  * Note: the driver must want to bind to the device,
 200  * it is not possible to override the driver's id table.
 201  */
 202 static ssize_t driver_bind(struct device_driver *drv,
 203                            const char *buf, size_t count)
 204 {
 205         struct bus_type *bus = bus_get(drv->bus);
 206         struct device *dev;
 207         int err = -ENODEV;
 208
 209         dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
 210         if (dev && dev->driver == NULL) {
 211                 if (dev->parent)        /* Needed for USB */
 212                         down(&dev->parent->sem);
 213                 down(&dev->sem);
 214                 err = driver_probe_device(drv, dev);
 215                 up(&dev->sem);
 216                 if (dev->parent)
 217                         up(&dev->parent->sem);
 218
 219                 if (err > 0) {
 220                         /* success */
 221                         err = count;
 222                 } else if (err == 0) {
 223                         /* driver didn't accept device */
 224                         err = -ENODEV;
 225                 }
 226         }
 227         put_device(dev);
 228         bus_put(bus);
 229         return err;
 230 }
 231 static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
 232
 233 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
 234 {
 235         return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
 236 }
 237
 238 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
 239                                        const char *buf, size_t count)
 240 {
 241         if (buf[0] == '0')
 242                 bus->p->drivers_autoprobe = 0;
 243         else
 244                 bus->p->drivers_autoprobe = 1;
 245         return count;
 246 }
 247
 248 static ssize_t store_drivers_probe(struct bus_type *bus,
 249                                    const char *buf, size_t count)
 250 {
 251         struct device *dev;
 252
 253         dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
 254         if (!dev)
 255                 return -ENODEV;
 256         if (bus_rescan_devices_helper(dev, NULL) != 0)
 257                 return -EINVAL;
 258         return count;
 259 }
 260 #endif
 261
 262 static struct device *next_device(struct klist_iter *i)
 263 {
 264         struct klist_node *n = klist_next(i);
 265         return n ? container_of(n, struct device, knode_bus) : NULL;
 266 }
 267
 268 /**
 269  * bus_for_each_dev - device iterator.
 270  * @bus: bus type.
 271  * @start: device to start iterating from.
 272  * @data: data for the callback.
 273  * @fn: function to be called for each device.
 274  *
 275  * Iterate over @bus's list of devices, and call @fn for each,
 276  * passing it @data. If @start is not NULL, we use that device to
 277  * begin iterating from.
 278  *
 279  * We check the return of @fn each time. If it returns anything
 280  * other than 0, we break out and return that value.
 281  *
 282  * NOTE: The device that returns a non-zero value is not retained
 283  * in any way, nor is its refcount incremented. If the caller needs
 284  * to retain this data, it should do, and increment the reference
 285  * count in the supplied callback.
 286  */
 287 int bus_for_each_dev(struct bus_type *bus, struct device *start,
 288                      void *data, int (*fn)(struct device *, void *))
 289 {
 290         struct klist_iter i;
 291         struct device *dev;
 292         int error = 0;
 293
 294         if (!bus)
 295                 return -EINVAL;
 296
 297         klist_iter_init_node(&bus->p->klist_devices, &i,
 298                              (start ? &start->knode_bus : NULL));
 299         while ((dev = next_device(&i)) && !error)
 300                 error = fn(dev, data);
 301         klist_iter_exit(&i);
 302         return error;
 303 }
 304 EXPORT_SYMBOL_GPL(bus_for_each_dev);
 305
 306 /**
 307  * bus_find_device - device iterator for locating a particular device.
 308  * @bus: bus type
 309  * @start: Device to begin with
 310  * @data: Data to pass to match function
 311  * @match: Callback function to check device
 312  *
 313  * This is similar to the bus_for_each_dev() function above, but it
 314  * returns a reference to a device that is 'found' for later use, as
 315  * determined by the @match callback.
 316  *
 317  * The callback should return 0 if the device doesn't match and non-zero
 318  * if it does.  If the callback returns non-zero, this function will
 319  * return to the caller and not iterate over any more devices.
 320  */
 321 struct device *bus_find_device(struct bus_type *bus,
 322                                struct device *start, void *data,
 323                                int (*match)(struct device *dev, void *data))
 324 {
 325         struct klist_iter i;
 326         struct device *dev;
 327
 328         if (!bus)
 329                 return NULL;
 330
 331         klist_iter_init_node(&bus->p->klist_devices, &i,
 332                              (start ? &start->knode_bus : NULL));
 333         while ((dev = next_device(&i)))
 334                 if (match(dev, data) && get_device(dev))
 335                         break;
 336         klist_iter_exit(&i);
 337         return dev;
 338 }
 339 EXPORT_SYMBOL_GPL(bus_find_device);
 340
 341 static struct device_driver *next_driver(struct klist_iter *i)
 342 {
 343         struct klist_node *n = klist_next(i);
 344         struct driver_private *drv_priv;
 345
 346         if (n) {
 347                 drv_priv = container_of(n, struct driver_private, knode_bus);
 348                 return drv_priv->driver;
 349         }
 350         return NULL;
 351 }
 352
 353 /**
 354  * bus_for_each_drv - driver iterator
 355  * @bus: bus we're dealing with.
 356  * @start: driver to start iterating on.
 357  * @data: data to pass to the callback.
 358  * @fn: function to call for each driver.
 359  *
 360  * This is nearly identical to the device iterator above.
 361  * We iterate over each driver that belongs to @bus, and call
 362  * @fn for each. If @fn returns anything but 0, we break out
 363  * and return it. If @start is not NULL, we use it as the head
 364  * of the list.
 365  *
 366  * NOTE: we don't return the driver that returns a non-zero
 367  * value, nor do we leave the reference count incremented for that
 368  * driver. If the caller needs to know that info, it must set it
 369  * in the callback. It must also be sure to increment the refcount
 370  * so it doesn't disappear before returning to the caller.
 371  */
 372 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
 373                      void *data, int (*fn)(struct device_driver *, void *))
 374 {
 375         struct klist_iter i;
 376         struct device_driver *drv;
 377         int error = 0;
 378
 379         if (!bus)
 380                 return -EINVAL;
 381
 382         klist_iter_init_node(&bus->p->klist_drivers, &i,
 383                              start ? &start->p->knode_bus : NULL);
 384         while ((drv = next_driver(&i)) && !error)
 385                 error = fn(drv, data);
 386         klist_iter_exit(&i);
 387         return error;
 388 }
 389 EXPORT_SYMBOL_GPL(bus_for_each_drv);
 390
 391 static int device_add_attrs(struct bus_type *bus, struct device *dev)
 392 {
 393         int error = 0;
 394         int i;
 395
 396         if (!bus->dev_attrs)
 397                 return 0;
 398
 399         for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
 400                 error = device_create_file(dev, &bus->dev_attrs[i]);
 401                 if (error) {
 402                         while (--i >= 0)
 403                                 device_remove_file(dev, &bus->dev_attrs[i]);
 404                         break;
 405                 }
 406         }
 407         return error;
 408 }
 409
 410 static void device_remove_attrs(struct bus_type *bus, struct device *dev)
 411 {
 412         int i;
 413
 414         if (bus->dev_attrs) {
 415                 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
 416                         device_remove_file(dev, &bus->dev_attrs[i]);
 417         }
 418 }
 419
 420 #ifdef CONFIG_SYSFS_DEPRECATED
 421 static int make_deprecated_bus_links(struct device *dev)
 422 {
 423         return sysfs_create_link(&dev->kobj,
 424                                  &dev->bus->p->subsys.kobj, "bus");
 425 }
 426
 427 static void remove_deprecated_bus_links(struct device *dev)
 428 {
 429         sysfs_remove_link(&dev->kobj, "bus");
 430 }
 431 #else
 432 static inline int make_deprecated_bus_links(struct device *dev) { return 0; }
 433 static inline void remove_deprecated_bus_links(struct device *dev) { }
 434 #endif
 435
 436 /**
 437  * bus_add_device - add device to bus
 438  * @dev: device being added
 439  *
 440  * - Add the device to its bus's list of devices.
 441  * - Create link to device's bus.
 442  */
 443 int bus_add_device(struct device *dev)
 444 {
 445         struct bus_type *bus = bus_get(dev->bus);
 446         int error = 0;
 447
 448         if (bus) {
 449                 pr_debug("bus: '%s': add device %s\n", bus->name, dev->bus_id);
 450                 error = device_add_attrs(bus, dev);
 451                 if (error)
 452                         goto out_put;
 453                 error = sysfs_create_link(&bus->p->devices_kset->kobj,
 454                                                 &dev->kobj, dev->bus_id);
 455                 if (error)
 456                         goto out_id;
 457                 error = sysfs_create_link(&dev->kobj,
 458                                 &dev->bus->p->subsys.kobj, "subsystem");
 459                 if (error)
 460                         goto out_subsys;
 461                 error = make_deprecated_bus_links(dev);
 462                 if (error)
 463                         goto out_deprecated;
 464         }
 465         return 0;
 466
 467 out_deprecated:
 468         sysfs_remove_link(&dev->kobj, "subsystem");
 469 out_subsys:
 470         sysfs_remove_link(&bus->p->devices_kset->kobj, dev->bus_id);
 471 out_id:
 472         device_remove_attrs(bus, dev);
 473 out_put:
 474         bus_put(dev->bus);
 475         return error;
 476 }
 477
 478 /**
 479  * bus_attach_device - add device to bus
 480  * @dev: device tried to attach to a driver
 481  *
 482  * - Add device to bus's list of devices.
 483  * - Try to attach to driver.
 484  */
 485 void bus_attach_device(struct device *dev)
 486 {
 487         struct bus_type *bus = dev->bus;
 488         int ret = 0;
 489
 490         if (bus) {
 491                 dev->is_registered = 1;
 492                 if (bus->p->drivers_autoprobe)
 493                         ret = device_attach(dev);
 494                 WARN_ON(ret < 0);
 495                 if (ret >= 0)
 496                         klist_add_tail(&dev->knode_bus, &bus->p->klist_devices);
 497                 else
 498                         dev->is_registered = 0;
 499         }
 500 }
 501
 502 /**
 503  * bus_remove_device - remove device from bus
 504  * @dev: device to be removed
 505  *
 506  * - Remove symlink from bus's directory.
 507  * - Delete device from bus's list.
 508  * - Detach from its driver.
 509  * - Drop reference taken in bus_add_device().
 510  */
 511 void bus_remove_device(struct device *dev)
 512 {
 513         if (dev->bus) {
 514                 sysfs_remove_link(&dev->kobj, "subsystem");
 515                 remove_deprecated_bus_links(dev);
 516                 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
 517                                   dev->bus_id);
 518                 device_remove_attrs(dev->bus, dev);
 519                 if (dev->is_registered) {
 520                         dev->is_registered = 0;
 521                         klist_del(&dev->knode_bus);
 522                 }
 523                 pr_debug("bus: '%s': remove device %s\n",
 524                          dev->bus->name, dev->bus_id);
 525                 device_release_driver(dev);
 526                 bus_put(dev->bus);
 527         }
 528 }
 529
 530 static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
 531 {
 532         int error = 0;
 533         int i;
 534
 535         if (bus->drv_attrs) {
 536                 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
 537                         error = driver_create_file(drv, &bus->drv_attrs[i]);
 538                         if (error)
 539                                 goto err;
 540                 }
 541         }
 542 done:
 543         return error;
 544 err:
 545         while (--i >= 0)
 546                 driver_remove_file(drv, &bus->drv_attrs[i]);
 547         goto done;
 548 }
 549
 550 static void driver_remove_attrs(struct bus_type *bus,
 551                                 struct device_driver *drv)
 552 {
 553         int i;
 554
 555         if (bus->drv_attrs) {
 556                 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
 557                         driver_remove_file(drv, &bus->drv_attrs[i]);
 558         }
 559 }
 560
 561 #ifdef CONFIG_HOTPLUG
 562 /*
 563  * Thanks to drivers making their tables __devinit, we can't allow manual
 564  * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
 565  */
 566 static int __must_check add_bind_files(struct device_driver *drv)
 567 {
 568         int ret;
 569
 570         ret = driver_create_file(drv, &driver_attr_unbind);
 571         if (ret == 0) {
 572                 ret = driver_create_file(drv, &driver_attr_bind);
 573                 if (ret)
 574                         driver_remove_file(drv, &driver_attr_unbind);
 575         }
 576         return ret;
 577 }
 578
 579 static void remove_bind_files(struct device_driver *drv)
 580 {
 581         driver_remove_file(drv, &driver_attr_bind);
 582         driver_remove_file(drv, &driver_attr_unbind);
 583 }
 584
 585 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
 586 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
 587                 show_drivers_autoprobe, store_drivers_autoprobe);
 588
 589 static int add_probe_files(struct bus_type *bus)
 590 {
 591         int retval;
 592
 593         retval = bus_create_file(bus, &bus_attr_drivers_probe);
 594         if (retval)
 595                 goto out;
 596
 597         retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
 598         if (retval)
 599                 bus_remove_file(bus, &bus_attr_drivers_probe);
 600 out:
 601         return retval;
 602 }
 603
 604 static void remove_probe_files(struct bus_type *bus)
 605 {
 606         bus_remove_file(bus, &bus_attr_drivers_autoprobe);
 607         bus_remove_file(bus, &bus_attr_drivers_probe);
 608 }
 609 #else
 610 static inline int add_bind_files(struct device_driver *drv) { return 0; }
 611 static inline void remove_bind_files(struct device_driver *drv) {}
 612 static inline int add_probe_files(struct bus_type *bus) { return 0; }
 613 static inline void remove_probe_files(struct bus_type *bus) {}
 614 #endif
 615
 616 static ssize_t driver_uevent_store(struct device_driver *drv,
 617                                    const char *buf, size_t count)
 618 {
 619         enum kobject_action action;
 620
 621         if (kobject_action_type(buf, count, &action) == 0)
 622                 kobject_uevent(&drv->p->kobj, action);
 623         return count;
 624 }
 625 static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
 626
 627 /**
 628  * bus_add_driver - Add a driver to the bus.
 629  * @drv: driver.
 630  */
 631 int bus_add_driver(struct device_driver *drv)
 632 {
 633         struct bus_type *bus;
 634         struct driver_private *priv;
 635         int error = 0;
 636
 637         bus = bus_get(drv->bus);
 638         if (!bus)
 639                 return -EINVAL;
 640
 641         pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
 642
 643         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 644         if (!priv)
 645                 return -ENOMEM;
 646
 647         klist_init(&priv->klist_devices, NULL, NULL);
 648         priv->driver = drv;
 649         drv->p = priv;
 650         priv->kobj.kset = bus->p->drivers_kset;
 651         error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
 652                                      "%s", drv->name);
 653         if (error)
 654                 goto out_put_bus;
 655
 656         if (drv->bus->p->drivers_autoprobe) {
 657                 error = driver_attach(drv);
 658                 if (error)
 659                         goto out_unregister;
 660         }
 661         klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
 662         module_add_driver(drv->owner, drv);
 663
 664         error = driver_create_file(drv, &driver_attr_uevent);
 665         if (error) {
 666                 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
 667                         __FUNCTION__, drv->name);
 668         }
 669         error = driver_add_attrs(bus, drv);
 670         if (error) {
 671                 /* How the hell do we get out of this pickle? Give up */
 672                 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
 673                         __FUNCTION__, drv->name);
 674         }
 675         error = add_bind_files(drv);
 676         if (error) {
 677                 /* Ditto */
 678                 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
 679                         __FUNCTION__, drv->name);
 680         }
 681
 682         kobject_uevent(&priv->kobj, KOBJ_ADD);
 683         return error;
 684 out_unregister:
 685         kobject_put(&priv->kobj);
 686 out_put_bus:
 687         bus_put(bus);
 688         return error;
 689 }
 690
 691 /**
 692  * bus_remove_driver - delete driver from bus's knowledge.
 693  * @drv: driver.
 694  *
 695  * Detach the driver from the devices it controls, and remove
 696  * it from its bus's list of drivers. Finally, we drop the reference
 697  * to the bus we took in bus_add_driver().
 698  */
 699 void bus_remove_driver(struct device_driver *drv)
 700 {
 701         if (!drv->bus)
 702                 return;
 703
 704         remove_bind_files(drv);
 705         driver_remove_attrs(drv->bus, drv);
 706         driver_remove_file(drv, &driver_attr_uevent);
 707         klist_remove(&drv->p->knode_bus);
 708         pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
 709         driver_detach(drv);
 710         module_remove_driver(drv);
 711         kobject_put(&drv->p->kobj);
 712         bus_put(drv->bus);
 713 }
 714
 715 /* Helper for bus_rescan_devices's iter */
 716 static int __must_check bus_rescan_devices_helper(struct device *dev,
 717                                                   void *data)
 718 {
 719         int ret = 0;
 720
 721         if (!dev->driver) {
 722                 if (dev->parent)        /* Needed for USB */
 723                         down(&dev->parent->sem);
 724                 ret = device_attach(dev);
 725                 if (dev->parent)
 726                         up(&dev->parent->sem);
 727         }
 728         return ret < 0 ? ret : 0;
 729 }
 730
 731 /**
 732  * bus_rescan_devices - rescan devices on the bus for possible drivers
 733  * @bus: the bus to scan.
 734  *
 735  * This function will look for devices on the bus with no driver
 736  * attached and rescan it against existing drivers to see if it matches
 737  * any by calling device_attach() for the unbound devices.
 738  */
 739 int bus_rescan_devices(struct bus_type *bus)
 740 {
 741         return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
 742 }
 743 EXPORT_SYMBOL_GPL(bus_rescan_devices);
 744
 745 /**
 746  * device_reprobe - remove driver for a device and probe for a new driver
 747  * @dev: the device to reprobe
 748  *
 749  * This function detaches the attached driver (if any) for the given
 750  * device and restarts the driver probing process.  It is intended
 751  * to use if probing criteria changed during a devices lifetime and
 752  * driver attachment should change accordingly.
 753  */
 754 int device_reprobe(struct device *dev)
 755 {
 756         if (dev->driver) {
 757                 if (dev->parent)        /* Needed for USB */
 758                         down(&dev->parent->sem);
 759                 device_release_driver(dev);
 760                 if (dev->parent)
 761                         up(&dev->parent->sem);
 762         }
 763         return bus_rescan_devices_helper(dev, NULL);
 764 }
 765 EXPORT_SYMBOL_GPL(device_reprobe);
 766
 767 /**
 768  * find_bus - locate bus by name.
 769  * @name: name of bus.
 770  *
 771  * Call kset_find_obj() to iterate over list of buses to
 772  * find a bus by name. Return bus if found.
 773  *
 774  * Note that kset_find_obj increments bus' reference count.
 775  */
 776 #if 0
 777 struct bus_type *find_bus(char *name)
 778 {
 779         struct kobject *k = kset_find_obj(bus_kset, name);
 780         return k ? to_bus(k) : NULL;
 781 }
 782 #endif  /*  0  */
 783
 784
 785 /**
 786  * bus_add_attrs - Add default attributes for this bus.
 787  * @bus: Bus that has just been registered.
 788  */
 789
 790 static int bus_add_attrs(struct bus_type *bus)
 791 {
 792         int error = 0;
 793         int i;
 794
 795         if (bus->bus_attrs) {
 796                 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
 797                         error = bus_create_file(bus, &bus->bus_attrs[i]);
 798                         if (error)
 799                                 goto err;
 800                 }
 801         }
 802 done:
 803         return error;
 804 err:
 805         while (--i >= 0)
 806                 bus_remove_file(bus, &bus->bus_attrs[i]);
 807         goto done;
 808 }
 809
 810 static void bus_remove_attrs(struct bus_type *bus)
 811 {
 812         int i;
 813
 814         if (bus->bus_attrs) {
 815                 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
 816                         bus_remove_file(bus, &bus->bus_attrs[i]);
 817         }
 818 }
 819
 820 static void klist_devices_get(struct klist_node *n)
 821 {
 822         struct device *dev = container_of(n, struct device, knode_bus);
 823
 824         get_device(dev);
 825 }
 826
 827 static void klist_devices_put(struct klist_node *n)
 828 {
 829         struct device *dev = container_of(n, struct device, knode_bus);
 830
 831         put_device(dev);
 832 }
 833
 834 static ssize_t bus_uevent_store(struct bus_type *bus,
 835                                 const char *buf, size_t count)
 836 {
 837         enum kobject_action action;
 838
 839         if (kobject_action_type(buf, count, &action) == 0)
 840                 kobject_uevent(&bus->p->subsys.kobj, action);
 841         return count;
 842 }
 843 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
 844
 845 /**
 846  * bus_register - register a bus with the system.
 847  * @bus: bus.
 848  *
 849  * Once we have that, we registered the bus with the kobject
 850  * infrastructure, then register the children subsystems it has:
 851  * the devices and drivers that belong to the bus.
 852  */
 853 int bus_register(struct bus_type *bus)
 854 {
 855         int retval;
 856         struct bus_type_private *priv;
 857
 858         priv = kzalloc(sizeof(struct bus_type_private), GFP_KERNEL);
 859         if (!priv)
 860                 return -ENOMEM;
 861
 862         priv->bus = bus;
 863         bus->p = priv;
 864
 865         BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
 866
 867         retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
 868         if (retval)
 869                 goto out;
 870
 871         priv->subsys.kobj.kset = bus_kset;
 872         priv->subsys.kobj.ktype = &bus_ktype;
 873         priv->drivers_autoprobe = 1;
 874
 875         retval = kset_register(&priv->subsys);
 876         if (retval)
 877                 goto out;
 878
 879         retval = bus_create_file(bus, &bus_attr_uevent);
 880         if (retval)
 881                 goto bus_uevent_fail;
 882
 883         priv->devices_kset = kset_create_and_add("devices", NULL,
 884                                                  &priv->subsys.kobj);
 885         if (!priv->devices_kset) {
 886                 retval = -ENOMEM;
 887                 goto bus_devices_fail;
 888         }
 889
 890         priv->drivers_kset = kset_create_and_add("drivers", NULL,
 891                                                  &priv->subsys.kobj);
 892         if (!priv->drivers_kset) {
 893                 retval = -ENOMEM;
 894                 goto bus_drivers_fail;
 895         }
 896
 897         klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
 898         klist_init(&priv->klist_drivers, NULL, NULL);
 899
 900         retval = add_probe_files(bus);
 901         if (retval)
 902                 goto bus_probe_files_fail;
 903
 904         retval = bus_add_attrs(bus);
 905         if (retval)
 906                 goto bus_attrs_fail;
 907
 908         pr_debug("bus: '%s': registered\n", bus->name);
 909         return 0;
 910
 911 bus_attrs_fail:
 912         remove_probe_files(bus);
 913 bus_probe_files_fail:
 914         kset_unregister(bus->p->drivers_kset);
 915 bus_drivers_fail:
 916         kset_unregister(bus->p->devices_kset);
 917 bus_devices_fail:
 918         bus_remove_file(bus, &bus_attr_uevent);
 919 bus_uevent_fail:
 920         kset_unregister(&bus->p->subsys);
 921         kfree(bus->p);
 922 out:
 923         return retval;
 924 }
 925 EXPORT_SYMBOL_GPL(bus_register);
 926
 927 /**
 928  * bus_unregister - remove a bus from the system
 929  * @bus: bus.
 930  *
 931  * Unregister the child subsystems and the bus itself.
 932  * Finally, we call bus_put() to release the refcount
 933  */
 934 void bus_unregister(struct bus_type *bus)
 935 {
 936         pr_debug("bus: '%s': unregistering\n", bus->name);
 937         bus_remove_attrs(bus);
 938         remove_probe_files(bus);
 939         kset_unregister(bus->p->drivers_kset);
 940         kset_unregister(bus->p->devices_kset);
 941         bus_remove_file(bus, &bus_attr_uevent);
 942         kset_unregister(&bus->p->subsys);
 943         kfree(bus->p);
 944 }
 945 EXPORT_SYMBOL_GPL(bus_unregister);
 946
 947 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
 948 {
 949         return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
 950 }
 951 EXPORT_SYMBOL_GPL(bus_register_notifier);
 952
 953 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
 954 {
 955         return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
 956 }
 957 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
 958
 959 struct kset *bus_get_kset(struct bus_type *bus)
 960 {
 961         return &bus->p->subsys;
 962 }
 963 EXPORT_SYMBOL_GPL(bus_get_kset);
 964
 965 struct klist *bus_get_device_klist(struct bus_type *bus)
 966 {
 967         return &bus->p->klist_devices;
 968 }
 969 EXPORT_SYMBOL_GPL(bus_get_device_klist);
 970
 971 int __init buses_init(void)
 972 {
 973         bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
 974         if (!bus_kset)
 975                 return -ENOMEM;
 976         return 0;
 977 }