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) {
 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         return n ? container_of(n, struct device, knode_bus) : NULL;
 257 }
 258
 259 /**
 260  * bus_for_each_dev - device iterator.
 261  * @bus: bus type.
 262  * @start: device to start iterating from.
 263  * @data: data for the callback.
 264  * @fn: function to be called for each device.
 265  *
 266  * Iterate over @bus's list of devices, and call @fn for each,
 267  * passing it @data. If @start is not NULL, we use that device to
 268  * begin iterating from.
 269  *
 270  * We check the return of @fn each time. If it returns anything
 271  * other than 0, we break out and return that value.
 272  *
 273  * NOTE: The device that returns a non-zero value is not retained
 274  * in any way, nor is its refcount incremented. If the caller needs
 275  * to retain this data, it should do, and increment the reference
 276  * count in the supplied callback.
 277  */
 278 int bus_for_each_dev(struct bus_type *bus, struct device *start,
 279                      void *data, int (*fn)(struct device *, void *))
 280 {
 281         struct klist_iter i;
 282         struct device *dev;
 283         int error = 0;
 284
 285         if (!bus)
 286                 return -EINVAL;
 287
 288         klist_iter_init_node(&bus->p->klist_devices, &i,
 289                              (start ? &start->knode_bus : NULL));
 290         while ((dev = next_device(&i)) && !error)
 291                 error = fn(dev, data);
 292         klist_iter_exit(&i);
 293         return error;
 294 }
 295 EXPORT_SYMBOL_GPL(bus_for_each_dev);
 296
 297 /**
 298  * bus_find_device - device iterator for locating a particular device.
 299  * @bus: bus type
 300  * @start: Device to begin with
 301  * @data: Data to pass to match function
 302  * @match: Callback function to check device
 303  *
 304  * This is similar to the bus_for_each_dev() function above, but it
 305  * returns a reference to a device that is 'found' for later use, as
 306  * determined by the @match callback.
 307  *
 308  * The callback should return 0 if the device doesn't match and non-zero
 309  * if it does.  If the callback returns non-zero, this function will
 310  * return to the caller and not iterate over any more devices.
 311  */
 312 struct device *bus_find_device(struct bus_type *bus,
 313                                struct device *start, void *data,
 314                                int (*match)(struct device *dev, void *data))
 315 {
 316         struct klist_iter i;
 317         struct device *dev;
 318
 319         if (!bus)
 320                 return NULL;
 321
 322         klist_iter_init_node(&bus->p->klist_devices, &i,
 323                              (start ? &start->knode_bus : NULL));
 324         while ((dev = next_device(&i)))
 325                 if (match(dev, data) && get_device(dev))
 326                         break;
 327         klist_iter_exit(&i);
 328         return dev;
 329 }
 330 EXPORT_SYMBOL_GPL(bus_find_device);
 331
 332 static int match_name(struct device *dev, void *data)
 333 {
 334         const char *name = data;
 335
 336         return sysfs_streq(name, dev_name(dev));
 337 }
 338
 339 /**
 340  * bus_find_device_by_name - device iterator for locating a particular device of a specific name
 341  * @bus: bus type
 342  * @start: Device to begin with
 343  * @name: name of the device to match
 344  *
 345  * This is similar to the bus_find_device() function above, but it handles
 346  * searching by a name automatically, no need to write another strcmp matching
 347  * function.
 348  */
 349 struct device *bus_find_device_by_name(struct bus_type *bus,
 350                                        struct device *start, const char *name)
 351 {
 352         return bus_find_device(bus, start, (void *)name, match_name);
 353 }
 354 EXPORT_SYMBOL_GPL(bus_find_device_by_name);
 355
 356 static struct device_driver *next_driver(struct klist_iter *i)
 357 {
 358         struct klist_node *n = klist_next(i);
 359         struct driver_private *drv_priv;
 360
 361         if (n) {
 362                 drv_priv = container_of(n, struct driver_private, knode_bus);
 363                 return drv_priv->driver;
 364         }
 365         return NULL;
 366 }
 367
 368 /**
 369  * bus_for_each_drv - driver iterator
 370  * @bus: bus we're dealing with.
 371  * @start: driver to start iterating on.
 372  * @data: data to pass to the callback.
 373  * @fn: function to call for each driver.
 374  *
 375  * This is nearly identical to the device iterator above.
 376  * We iterate over each driver that belongs to @bus, and call
 377  * @fn for each. If @fn returns anything but 0, we break out
 378  * and return it. If @start is not NULL, we use it as the head
 379  * of the list.
 380  *
 381  * NOTE: we don't return the driver that returns a non-zero
 382  * value, nor do we leave the reference count incremented for that
 383  * driver. If the caller needs to know that info, it must set it
 384  * in the callback. It must also be sure to increment the refcount
 385  * so it doesn't disappear before returning to the caller.
 386  */
 387 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
 388                      void *data, int (*fn)(struct device_driver *, void *))
 389 {
 390         struct klist_iter i;
 391         struct device_driver *drv;
 392         int error = 0;
 393
 394         if (!bus)
 395                 return -EINVAL;
 396
 397         klist_iter_init_node(&bus->p->klist_drivers, &i,
 398                              start ? &start->p->knode_bus : NULL);
 399         while ((drv = next_driver(&i)) && !error)
 400                 error = fn(drv, data);
 401         klist_iter_exit(&i);
 402         return error;
 403 }
 404 EXPORT_SYMBOL_GPL(bus_for_each_drv);
 405
 406 static int device_add_attrs(struct bus_type *bus, struct device *dev)
 407 {
 408         int error = 0;
 409         int i;
 410
 411         if (!bus->dev_attrs)
 412                 return 0;
 413
 414         for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
 415                 error = device_create_file(dev, &bus->dev_attrs[i]);
 416                 if (error) {
 417                         while (--i >= 0)
 418                                 device_remove_file(dev, &bus->dev_attrs[i]);
 419                         break;
 420                 }
 421         }
 422         return error;
 423 }
 424
 425 static void device_remove_attrs(struct bus_type *bus, struct device *dev)
 426 {
 427         int i;
 428
 429         if (bus->dev_attrs) {
 430                 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
 431                         device_remove_file(dev, &bus->dev_attrs[i]);
 432         }
 433 }
 434
 435 #ifdef CONFIG_SYSFS_DEPRECATED
 436 static int make_deprecated_bus_links(struct device *dev)
 437 {
 438         return sysfs_create_link(&dev->kobj,
 439                                  &dev->bus->p->subsys.kobj, "bus");
 440 }
 441
 442 static void remove_deprecated_bus_links(struct device *dev)
 443 {
 444         sysfs_remove_link(&dev->kobj, "bus");
 445 }
 446 #else
 447 static inline int make_deprecated_bus_links(struct device *dev) { return 0; }
 448 static inline void remove_deprecated_bus_links(struct device *dev) { }
 449 #endif
 450
 451 /**
 452  * bus_add_device - add device to bus
 453  * @dev: device being added
 454  *
 455  * - Add the device to its bus's list of devices.
 456  * - Create link to device's bus.
 457  */
 458 int bus_add_device(struct device *dev)
 459 {
 460         struct bus_type *bus = bus_get(dev->bus);
 461         int error = 0;
 462
 463         if (bus) {
 464                 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
 465                 error = device_add_attrs(bus, dev);
 466                 if (error)
 467                         goto out_put;
 468                 error = sysfs_create_link(&bus->p->devices_kset->kobj,
 469                                                 &dev->kobj, dev_name(dev));
 470                 if (error)
 471                         goto out_id;
 472                 error = sysfs_create_link(&dev->kobj,
 473                                 &dev->bus->p->subsys.kobj, "subsystem");
 474                 if (error)
 475                         goto out_subsys;
 476                 error = make_deprecated_bus_links(dev);
 477                 if (error)
 478                         goto out_deprecated;
 479         }
 480         return 0;
 481
 482 out_deprecated:
 483         sysfs_remove_link(&dev->kobj, "subsystem");
 484 out_subsys:
 485         sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
 486 out_id:
 487         device_remove_attrs(bus, dev);
 488 out_put:
 489         bus_put(dev->bus);
 490         return error;
 491 }
 492
 493 /**
 494  * bus_attach_device - add device to bus
 495  * @dev: device tried to attach to a driver
 496  *
 497  * - Add device to bus's list of devices.
 498  * - Try to attach to driver.
 499  */
 500 void bus_attach_device(struct device *dev)
 501 {
 502         struct bus_type *bus = dev->bus;
 503         int ret = 0;
 504
 505         if (bus) {
 506                 if (bus->p->drivers_autoprobe)
 507                         ret = device_attach(dev);
 508                 WARN_ON(ret < 0);
 509                 if (ret >= 0)
 510                         klist_add_tail(&dev->knode_bus, &bus->p->klist_devices);
 511         }
 512 }
 513
 514 /**
 515  * bus_remove_device - remove device from bus
 516  * @dev: device to be removed
 517  *
 518  * - Remove symlink from bus's directory.
 519  * - Delete device from bus's list.
 520  * - Detach from its driver.
 521  * - Drop reference taken in bus_add_device().
 522  */
 523 void bus_remove_device(struct device *dev)
 524 {
 525         if (dev->bus) {
 526                 sysfs_remove_link(&dev->kobj, "subsystem");
 527                 remove_deprecated_bus_links(dev);
 528                 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
 529                                   dev_name(dev));
 530                 device_remove_attrs(dev->bus, dev);
 531                 if (klist_node_attached(&dev->knode_bus))
 532                         klist_del(&dev->knode_bus);
 533
 534                 pr_debug("bus: '%s': remove device %s\n",
 535                          dev->bus->name, dev_name(dev));
 536                 device_release_driver(dev);
 537                 bus_put(dev->bus);
 538         }
 539 }
 540
 541 static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
 542 {
 543         int error = 0;
 544         int i;
 545
 546         if (bus->drv_attrs) {
 547                 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
 548                         error = driver_create_file(drv, &bus->drv_attrs[i]);
 549                         if (error)
 550                                 goto err;
 551                 }
 552         }
 553 done:
 554         return error;
 555 err:
 556         while (--i >= 0)
 557                 driver_remove_file(drv, &bus->drv_attrs[i]);
 558         goto done;
 559 }
 560
 561 static void driver_remove_attrs(struct bus_type *bus,
 562                                 struct device_driver *drv)
 563 {
 564         int i;
 565
 566         if (bus->drv_attrs) {
 567                 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
 568                         driver_remove_file(drv, &bus->drv_attrs[i]);
 569         }
 570 }
 571
 572 #ifdef CONFIG_HOTPLUG
 573 /*
 574  * Thanks to drivers making their tables __devinit, we can't allow manual
 575  * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
 576  */
 577 static int __must_check add_bind_files(struct device_driver *drv)
 578 {
 579         int ret;
 580
 581         ret = driver_create_file(drv, &driver_attr_unbind);
 582         if (ret == 0) {
 583                 ret = driver_create_file(drv, &driver_attr_bind);
 584                 if (ret)
 585                         driver_remove_file(drv, &driver_attr_unbind);
 586         }
 587         return ret;
 588 }
 589
 590 static void remove_bind_files(struct device_driver *drv)
 591 {
 592         driver_remove_file(drv, &driver_attr_bind);
 593         driver_remove_file(drv, &driver_attr_unbind);
 594 }
 595
 596 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
 597 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
 598                 show_drivers_autoprobe, store_drivers_autoprobe);
 599
 600 static int add_probe_files(struct bus_type *bus)
 601 {
 602         int retval;
 603
 604         retval = bus_create_file(bus, &bus_attr_drivers_probe);
 605         if (retval)
 606                 goto out;
 607
 608         retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
 609         if (retval)
 610                 bus_remove_file(bus, &bus_attr_drivers_probe);
 611 out:
 612         return retval;
 613 }
 614
 615 static void remove_probe_files(struct bus_type *bus)
 616 {
 617         bus_remove_file(bus, &bus_attr_drivers_autoprobe);
 618         bus_remove_file(bus, &bus_attr_drivers_probe);
 619 }
 620 #else
 621 static inline int add_bind_files(struct device_driver *drv) { return 0; }
 622 static inline void remove_bind_files(struct device_driver *drv) {}
 623 static inline int add_probe_files(struct bus_type *bus) { return 0; }
 624 static inline void remove_probe_files(struct bus_type *bus) {}
 625 #endif
 626
 627 static ssize_t driver_uevent_store(struct device_driver *drv,
 628                                    const char *buf, size_t count)
 629 {
 630         enum kobject_action action;
 631
 632         if (kobject_action_type(buf, count, &action) == 0)
 633                 kobject_uevent(&drv->p->kobj, action);
 634         return count;
 635 }
 636 static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
 637
 638 /**
 639  * bus_add_driver - Add a driver to the bus.
 640  * @drv: driver.
 641  */
 642 int bus_add_driver(struct device_driver *drv)
 643 {
 644         struct bus_type *bus;
 645         struct driver_private *priv;
 646         int error = 0;
 647
 648         bus = bus_get(drv->bus);
 649         if (!bus)
 650                 return -EINVAL;
 651
 652         pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
 653
 654         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 655         if (!priv) {
 656                 error = -ENOMEM;
 657                 goto out_put_bus;
 658         }
 659         klist_init(&priv->klist_devices, NULL, NULL);
 660         priv->driver = drv;
 661         drv->p = priv;
 662         priv->kobj.kset = bus->p->drivers_kset;
 663         error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
 664                                      "%s", drv->name);
 665         if (error)
 666                 goto out_unregister;
 667
 668         if (drv->bus->p->drivers_autoprobe) {
 669                 error = driver_attach(drv);
 670                 if (error)
 671                         goto out_unregister;
 672         }
 673         klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
 674         module_add_driver(drv->owner, drv);
 675
 676         error = driver_create_file(drv, &driver_attr_uevent);
 677         if (error) {
 678                 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
 679                         __func__, drv->name);
 680         }
 681         error = driver_add_attrs(bus, drv);
 682         if (error) {
 683                 /* How the hell do we get out of this pickle? Give up */
 684                 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
 685                         __func__, drv->name);
 686         }
 687         error = add_bind_files(drv);
 688         if (error) {
 689                 /* Ditto */
 690                 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
 691                         __func__, drv->name);
 692         }
 693
 694         kobject_uevent(&priv->kobj, KOBJ_ADD);
 695         return error;
 696 out_unregister:
 697         kobject_put(&priv->kobj);
 698 out_put_bus:
 699         bus_put(bus);
 700         return error;
 701 }
 702
 703 /**
 704  * bus_remove_driver - delete driver from bus's knowledge.
 705  * @drv: driver.
 706  *
 707  * Detach the driver from the devices it controls, and remove
 708  * it from its bus's list of drivers. Finally, we drop the reference
 709  * to the bus we took in bus_add_driver().
 710  */
 711 void bus_remove_driver(struct device_driver *drv)
 712 {
 713         if (!drv->bus)
 714                 return;
 715
 716         remove_bind_files(drv);
 717         driver_remove_attrs(drv->bus, drv);
 718         driver_remove_file(drv, &driver_attr_uevent);
 719         klist_remove(&drv->p->knode_bus);
 720         pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
 721         driver_detach(drv);
 722         module_remove_driver(drv);
 723         kobject_put(&drv->p->kobj);
 724         bus_put(drv->bus);
 725 }
 726
 727 /* Helper for bus_rescan_devices's iter */
 728 static int __must_check bus_rescan_devices_helper(struct device *dev,
 729                                                   void *data)
 730 {
 731         int ret = 0;
 732
 733         if (!dev->driver) {
 734                 if (dev->parent)        /* Needed for USB */
 735                         down(&dev->parent->sem);
 736                 ret = device_attach(dev);
 737                 if (dev->parent)
 738                         up(&dev->parent->sem);
 739         }
 740         return ret < 0 ? ret : 0;
 741 }
 742
 743 /**
 744  * bus_rescan_devices - rescan devices on the bus for possible drivers
 745  * @bus: the bus to scan.
 746  *
 747  * This function will look for devices on the bus with no driver
 748  * attached and rescan it against existing drivers to see if it matches
 749  * any by calling device_attach() for the unbound devices.
 750  */
 751 int bus_rescan_devices(struct bus_type *bus)
 752 {
 753         return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
 754 }
 755 EXPORT_SYMBOL_GPL(bus_rescan_devices);
 756
 757 /**
 758  * device_reprobe - remove driver for a device and probe for a new driver
 759  * @dev: the device to reprobe
 760  *
 761  * This function detaches the attached driver (if any) for the given
 762  * device and restarts the driver probing process.  It is intended
 763  * to use if probing criteria changed during a devices lifetime and
 764  * driver attachment should change accordingly.
 765  */
 766 int device_reprobe(struct device *dev)
 767 {
 768         if (dev->driver) {
 769                 if (dev->parent)        /* Needed for USB */
 770                         down(&dev->parent->sem);
 771                 device_release_driver(dev);
 772                 if (dev->parent)
 773                         up(&dev->parent->sem);
 774         }
 775         return bus_rescan_devices_helper(dev, NULL);
 776 }
 777 EXPORT_SYMBOL_GPL(device_reprobe);
 778
 779 /**
 780  * find_bus - locate bus by name.
 781  * @name: name of bus.
 782  *
 783  * Call kset_find_obj() to iterate over list of buses to
 784  * find a bus by name. Return bus if found.
 785  *
 786  * Note that kset_find_obj increments bus' reference count.
 787  */
 788 #if 0
 789 struct bus_type *find_bus(char *name)
 790 {
 791         struct kobject *k = kset_find_obj(bus_kset, name);
 792         return k ? to_bus(k) : NULL;
 793 }
 794 #endif  /*  0  */
 795
 796
 797 /**
 798  * bus_add_attrs - Add default attributes for this bus.
 799  * @bus: Bus that has just been registered.
 800  */
 801
 802 static int bus_add_attrs(struct bus_type *bus)
 803 {
 804         int error = 0;
 805         int i;
 806
 807         if (bus->bus_attrs) {
 808                 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
 809                         error = bus_create_file(bus, &bus->bus_attrs[i]);
 810                         if (error)
 811                                 goto err;
 812                 }
 813         }
 814 done:
 815         return error;
 816 err:
 817         while (--i >= 0)
 818                 bus_remove_file(bus, &bus->bus_attrs[i]);
 819         goto done;
 820 }
 821
 822 static void bus_remove_attrs(struct bus_type *bus)
 823 {
 824         int i;
 825
 826         if (bus->bus_attrs) {
 827                 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
 828                         bus_remove_file(bus, &bus->bus_attrs[i]);
 829         }
 830 }
 831
 832 static void klist_devices_get(struct klist_node *n)
 833 {
 834         struct device *dev = container_of(n, struct device, knode_bus);
 835
 836         get_device(dev);
 837 }
 838
 839 static void klist_devices_put(struct klist_node *n)
 840 {
 841         struct device *dev = container_of(n, struct device, knode_bus);
 842
 843         put_device(dev);
 844 }
 845
 846 static ssize_t bus_uevent_store(struct bus_type *bus,
 847                                 const char *buf, size_t count)
 848 {
 849         enum kobject_action action;
 850
 851         if (kobject_action_type(buf, count, &action) == 0)
 852                 kobject_uevent(&bus->p->subsys.kobj, action);
 853         return count;
 854 }
 855 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
 856
 857 /**
 858  * bus_register - register a bus with the system.
 859  * @bus: bus.
 860  *
 861  * Once we have that, we registered the bus with the kobject
 862  * infrastructure, then register the children subsystems it has:
 863  * the devices and drivers that belong to the bus.
 864  */
 865 int bus_register(struct bus_type *bus)
 866 {
 867         int retval;
 868         struct bus_type_private *priv;
 869
 870         priv = kzalloc(sizeof(struct bus_type_private), GFP_KERNEL);
 871         if (!priv)
 872                 return -ENOMEM;
 873
 874         priv->bus = bus;
 875         bus->p = priv;
 876
 877         BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
 878
 879         retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
 880         if (retval)
 881                 goto out;
 882
 883         priv->subsys.kobj.kset = bus_kset;
 884         priv->subsys.kobj.ktype = &bus_ktype;
 885         priv->drivers_autoprobe = 1;
 886
 887         retval = kset_register(&priv->subsys);
 888         if (retval)
 889                 goto out;
 890
 891         retval = bus_create_file(bus, &bus_attr_uevent);
 892         if (retval)
 893                 goto bus_uevent_fail;
 894
 895         priv->devices_kset = kset_create_and_add("devices", NULL,
 896                                                  &priv->subsys.kobj);
 897         if (!priv->devices_kset) {
 898                 retval = -ENOMEM;
 899                 goto bus_devices_fail;
 900         }
 901
 902         priv->drivers_kset = kset_create_and_add("drivers", NULL,
 903                                                  &priv->subsys.kobj);
 904         if (!priv->drivers_kset) {
 905                 retval = -ENOMEM;
 906                 goto bus_drivers_fail;
 907         }
 908
 909         klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
 910         klist_init(&priv->klist_drivers, NULL, NULL);
 911
 912         retval = add_probe_files(bus);
 913         if (retval)
 914                 goto bus_probe_files_fail;
 915
 916         retval = bus_add_attrs(bus);
 917         if (retval)
 918                 goto bus_attrs_fail;
 919
 920         pr_debug("bus: '%s': registered\n", bus->name);
 921         return 0;
 922
 923 bus_attrs_fail:
 924         remove_probe_files(bus);
 925 bus_probe_files_fail:
 926         kset_unregister(bus->p->drivers_kset);
 927 bus_drivers_fail:
 928         kset_unregister(bus->p->devices_kset);
 929 bus_devices_fail:
 930         bus_remove_file(bus, &bus_attr_uevent);
 931 bus_uevent_fail:
 932         kset_unregister(&bus->p->subsys);
 933         kfree(bus->p);
 934 out:
 935         return retval;
 936 }
 937 EXPORT_SYMBOL_GPL(bus_register);
 938
 939 /**
 940  * bus_unregister - remove a bus from the system
 941  * @bus: bus.
 942  *
 943  * Unregister the child subsystems and the bus itself.
 944  * Finally, we call bus_put() to release the refcount
 945  */
 946 void bus_unregister(struct bus_type *bus)
 947 {
 948         pr_debug("bus: '%s': unregistering\n", bus->name);
 949         bus_remove_attrs(bus);
 950         remove_probe_files(bus);
 951         kset_unregister(bus->p->drivers_kset);
 952         kset_unregister(bus->p->devices_kset);
 953         bus_remove_file(bus, &bus_attr_uevent);
 954         kset_unregister(&bus->p->subsys);
 955         kfree(bus->p);
 956 }
 957 EXPORT_SYMBOL_GPL(bus_unregister);
 958
 959 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
 960 {
 961         return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
 962 }
 963 EXPORT_SYMBOL_GPL(bus_register_notifier);
 964
 965 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
 966 {
 967         return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
 968 }
 969 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
 970
 971 struct kset *bus_get_kset(struct bus_type *bus)
 972 {
 973         return &bus->p->subsys;
 974 }
 975 EXPORT_SYMBOL_GPL(bus_get_kset);
 976
 977 struct klist *bus_get_device_klist(struct bus_type *bus)
 978 {
 979         return &bus->p->klist_devices;
 980 }
 981 EXPORT_SYMBOL_GPL(bus_get_device_klist);
 982
 983 /*
 984  * Yes, this forcably breaks the klist abstraction temporarily.  It
 985  * just wants to sort the klist, not change reference counts and
 986  * take/drop locks rapidly in the process.  It does all this while
 987  * holding the lock for the list, so objects can't otherwise be
 988  * added/removed while we're swizzling.
 989  */
 990 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
 991                                         int (*compare)(const struct device *a,
 992                                                         const struct device *b))
 993 {
 994         struct list_head *pos;
 995         struct klist_node *n;
 996         struct device *b;
 997
 998         list_for_each(pos, list) {
 999                 n = container_of(pos, struct klist_node, n_node);
1000                 b = container_of(n, struct device, knode_bus);
1001                 if (compare(a, b) <= 0) {
1002                         list_move_tail(&a->knode_bus.n_node,
1003                                        &b->knode_bus.n_node);
1004                         return;
1005                 }
1006         }
1007         list_move_tail(&a->knode_bus.n_node, list);
1008 }
1009
1010 void bus_sort_breadthfirst(struct bus_type *bus,
1011                            int (*compare)(const struct device *a,
1012                                           const struct device *b))
1013 {
1014         LIST_HEAD(sorted_devices);
1015         struct list_head *pos, *tmp;
1016         struct klist_node *n;
1017         struct device *dev;
1018         struct klist *device_klist;
1019
1020         device_klist = bus_get_device_klist(bus);
1021
1022         spin_lock(&device_klist->k_lock);
1023         list_for_each_safe(pos, tmp, &device_klist->k_list) {
1024                 n = container_of(pos, struct klist_node, n_node);
1025                 dev = container_of(n, struct device, knode_bus);
1026                 device_insertion_sort_klist(dev, &sorted_devices, compare);
1027         }
1028         list_splice(&sorted_devices, &device_klist->k_list);
1029         spin_unlock(&device_klist->k_lock);
1030 }
1031 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1032
1033 int __init buses_init(void)
1034 {
1035         bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1036         if (!bus_kset)
1037                 return -ENOMEM;
1038         return 0;
1039 }