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