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