bus.c 16.0 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
/*
 * bus.c - bus driver management
 *
 * Copyright (c) 2002-3 Patrick Mochel
 * Copyright (c) 2002-3 Open Source Development Labs
 *
 * This file is released under the GPLv2
 *
 */

#include <linux/config.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/string.h>
#include "base.h"
#include "power/power.h"

#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
#define to_bus(obj) container_of(obj, struct bus_type, subsys.kset.kobj)

/*
 * sysfs bindings for drivers
 */

#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
#define to_driver(obj) container_of(obj, struct device_driver, kobj)


static ssize_t
drv_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
{
	struct driver_attribute * drv_attr = to_drv_attr(attr);
	struct device_driver * drv = to_driver(kobj);
36
	ssize_t ret = -EIO;
L
Linus Torvalds 已提交
37 38 39 40 41 42 43 44 45 46 47 48

	if (drv_attr->show)
		ret = drv_attr->show(drv, buf);
	return ret;
}

static ssize_t
drv_attr_store(struct kobject * kobj, struct attribute * attr,
	       const char * buf, size_t count)
{
	struct driver_attribute * drv_attr = to_drv_attr(attr);
	struct device_driver * drv = to_driver(kobj);
49
	ssize_t ret = -EIO;
L
Linus Torvalds 已提交
50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135

	if (drv_attr->store)
		ret = drv_attr->store(drv, buf, count);
	return ret;
}

static struct sysfs_ops driver_sysfs_ops = {
	.show	= drv_attr_show,
	.store	= drv_attr_store,
};


static void driver_release(struct kobject * kobj)
{
	struct device_driver * drv = to_driver(kobj);
	complete(&drv->unloaded);
}

static struct kobj_type ktype_driver = {
	.sysfs_ops	= &driver_sysfs_ops,
	.release	= driver_release,
};


/*
 * sysfs bindings for buses
 */


static ssize_t
bus_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
{
	struct bus_attribute * bus_attr = to_bus_attr(attr);
	struct bus_type * bus = to_bus(kobj);
	ssize_t ret = 0;

	if (bus_attr->show)
		ret = bus_attr->show(bus, buf);
	return ret;
}

static ssize_t
bus_attr_store(struct kobject * kobj, struct attribute * attr,
	       const char * buf, size_t count)
{
	struct bus_attribute * bus_attr = to_bus_attr(attr);
	struct bus_type * bus = to_bus(kobj);
	ssize_t ret = 0;

	if (bus_attr->store)
		ret = bus_attr->store(bus, buf, count);
	return ret;
}

static struct sysfs_ops bus_sysfs_ops = {
	.show	= bus_attr_show,
	.store	= bus_attr_store,
};

int bus_create_file(struct bus_type * bus, struct bus_attribute * attr)
{
	int error;
	if (get_bus(bus)) {
		error = sysfs_create_file(&bus->subsys.kset.kobj, &attr->attr);
		put_bus(bus);
	} else
		error = -EINVAL;
	return error;
}

void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr)
{
	if (get_bus(bus)) {
		sysfs_remove_file(&bus->subsys.kset.kobj, &attr->attr);
		put_bus(bus);
	}
}

static struct kobj_type ktype_bus = {
	.sysfs_ops	= &bus_sysfs_ops,

};

decl_subsys(bus, &ktype_bus, NULL);


136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158
/* Manually detach a device from it's associated driver. */
static int driver_helper(struct device *dev, void *data)
{
	const char *name = data;

	if (strcmp(name, dev->bus_id) == 0)
		return 1;
	return 0;
}

static ssize_t driver_unbind(struct device_driver *drv,
			     const char *buf, size_t count)
{
	struct bus_type *bus = get_bus(drv->bus);
	struct device *dev;
	int err = -ENODEV;

	dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
	if ((dev) &&
	    (dev->driver == drv)) {
		device_release_driver(dev);
		err = count;
	}
159 160 161
	if (err)
		return err;
	return count;
162 163 164
}
static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);

165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184
/*
 * Manually attach a device to a driver.
 * Note: the driver must want to bind to the device,
 * it is not possible to override the driver's id table.
 */
static ssize_t driver_bind(struct device_driver *drv,
			   const char *buf, size_t count)
{
	struct bus_type *bus = get_bus(drv->bus);
	struct device *dev;
	int err = -ENODEV;

	dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
	if ((dev) &&
	    (dev->driver == NULL)) {
		down(&dev->sem);
		err = driver_probe_device(drv, dev);
		up(&dev->sem);
		put_device(dev);
	}
185 186 187
	if (err)
		return err;
	return count;
188 189 190
}
static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);

191

192 193 194 195 196 197
static struct device * next_device(struct klist_iter * i)
{
	struct klist_node * n = klist_next(i);
	return n ? container_of(n, struct device, knode_bus) : NULL;
}

L
Linus Torvalds 已提交
198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220
/**
 *	bus_for_each_dev - device iterator.
 *	@bus:	bus type.
 *	@start:	device to start iterating from.
 *	@data:	data for the callback.
 *	@fn:	function to be called for each device.
 *
 *	Iterate over @bus's list of devices, and call @fn for each,
 *	passing it @data. If @start is not NULL, we use that device to
 *	begin iterating from.
 *
 *	We check the return of @fn each time. If it returns anything
 *	other than 0, we break out and return that value.
 *
 *	NOTE: The device that returns a non-zero value is not retained
 *	in any way, nor is its refcount incremented. If the caller needs
 *	to retain this data, it should do, and increment the reference
 *	count in the supplied callback.
 */

int bus_for_each_dev(struct bus_type * bus, struct device * start,
		     void * data, int (*fn)(struct device *, void *))
{
221 222 223
	struct klist_iter i;
	struct device * dev;
	int error = 0;
L
Linus Torvalds 已提交
224

225 226 227 228 229 230 231 232 233
	if (!bus)
		return -EINVAL;

	klist_iter_init_node(&bus->klist_devices, &i,
			     (start ? &start->knode_bus : NULL));
	while ((dev = next_device(&i)) && !error)
		error = fn(dev, data);
	klist_iter_exit(&i);
	return error;
L
Linus Torvalds 已提交
234 235
}

236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268
/**
 * bus_find_device - device iterator for locating a particular device.
 * @bus: bus type
 * @start: Device to begin with
 * @data: Data to pass to match function
 * @match: Callback function to check device
 *
 * This is similar to the bus_for_each_dev() function above, but it
 * returns a reference to a device that is 'found' for later use, as
 * determined by the @match callback.
 *
 * The callback should return 0 if the device doesn't match and non-zero
 * if it does.  If the callback returns non-zero, this function will
 * return to the caller and not iterate over any more devices.
 */
struct device * bus_find_device(struct bus_type *bus,
				struct device *start, void *data,
				int (*match)(struct device *, void *))
{
	struct klist_iter i;
	struct device *dev;

	if (!bus)
		return NULL;

	klist_iter_init_node(&bus->klist_devices, &i,
			     (start ? &start->knode_bus : NULL));
	while ((dev = next_device(&i)))
		if (match(dev, data) && get_device(dev))
			break;
	klist_iter_exit(&i);
	return dev;
}
269 270 271 272 273 274 275 276


static struct device_driver * next_driver(struct klist_iter * i)
{
	struct klist_node * n = klist_next(i);
	return n ? container_of(n, struct device_driver, knode_bus) : NULL;
}

L
Linus Torvalds 已提交
277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299
/**
 *	bus_for_each_drv - driver iterator
 *	@bus:	bus we're dealing with.
 *	@start:	driver to start iterating on.
 *	@data:	data to pass to the callback.
 *	@fn:	function to call for each driver.
 *
 *	This is nearly identical to the device iterator above.
 *	We iterate over each driver that belongs to @bus, and call
 *	@fn for each. If @fn returns anything but 0, we break out
 *	and return it. If @start is not NULL, we use it as the head
 *	of the list.
 *
 *	NOTE: we don't return the driver that returns a non-zero
 *	value, nor do we leave the reference count incremented for that
 *	driver. If the caller needs to know that info, it must set it
 *	in the callback. It must also be sure to increment the refcount
 *	so it doesn't disappear before returning to the caller.
 */

int bus_for_each_drv(struct bus_type * bus, struct device_driver * start,
		     void * data, int (*fn)(struct device_driver *, void *))
{
300 301 302
	struct klist_iter i;
	struct device_driver * drv;
	int error = 0;
L
Linus Torvalds 已提交
303

304 305 306 307 308 309 310 311 312
	if (!bus)
		return -EINVAL;

	klist_iter_init_node(&bus->klist_drivers, &i,
			     start ? &start->knode_bus : NULL);
	while ((drv = next_driver(&i)) && !error)
		error = fn(drv, data);
	klist_iter_exit(&i);
	return error;
L
Linus Torvalds 已提交
313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361
}

static int device_add_attrs(struct bus_type * bus, struct device * dev)
{
	int error = 0;
	int i;

	if (bus->dev_attrs) {
		for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
			error = device_create_file(dev,&bus->dev_attrs[i]);
			if (error)
				goto Err;
		}
	}
 Done:
	return error;
 Err:
	while (--i >= 0)
		device_remove_file(dev,&bus->dev_attrs[i]);
	goto Done;
}


static void device_remove_attrs(struct bus_type * bus, struct device * dev)
{
	int i;

	if (bus->dev_attrs) {
		for (i = 0; attr_name(bus->dev_attrs[i]); i++)
			device_remove_file(dev,&bus->dev_attrs[i]);
	}
}


/**
 *	bus_add_device - add device to bus
 *	@dev:	device being added
 *
 *	- Add the device to its bus's list of devices.
 *	- Try to attach to driver.
 *	- Create link to device's physical location.
 */
int bus_add_device(struct device * dev)
{
	struct bus_type * bus = get_bus(dev->bus);
	int error = 0;

	if (bus) {
		pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id);
362
		device_attach(dev);
363
		klist_add_tail(&dev->knode_bus, &bus->klist_devices);
364
		error = device_add_attrs(bus, dev);
365 366 367 368
		if (!error) {
			sysfs_create_link(&bus->devices.kobj, &dev->kobj, dev->bus_id);
			sysfs_create_link(&dev->kobj, &dev->bus->subsys.kset.kobj, "bus");
		}
L
Linus Torvalds 已提交
369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387
	}
	return error;
}

/**
 *	bus_remove_device - remove device from bus
 *	@dev:	device to be removed
 *
 *	- Remove symlink from bus's directory.
 *	- Delete device from bus's list.
 *	- Detach from its driver.
 *	- Drop reference taken in bus_add_device().
 */
void bus_remove_device(struct device * dev)
{
	if (dev->bus) {
		sysfs_remove_link(&dev->kobj, "bus");
		sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id);
		device_remove_attrs(dev->bus, dev);
388
		klist_remove(&dev->knode_bus);
L
Linus Torvalds 已提交
389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450
		pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
		device_release_driver(dev);
		put_bus(dev->bus);
	}
}

static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv)
{
	int error = 0;
	int i;

	if (bus->drv_attrs) {
		for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
			error = driver_create_file(drv, &bus->drv_attrs[i]);
			if (error)
				goto Err;
		}
	}
 Done:
	return error;
 Err:
	while (--i >= 0)
		driver_remove_file(drv, &bus->drv_attrs[i]);
	goto Done;
}


static void driver_remove_attrs(struct bus_type * bus, struct device_driver * drv)
{
	int i;

	if (bus->drv_attrs) {
		for (i = 0; attr_name(bus->drv_attrs[i]); i++)
			driver_remove_file(drv, &bus->drv_attrs[i]);
	}
}


/**
 *	bus_add_driver - Add a driver to the bus.
 *	@drv:	driver.
 *
 */
int bus_add_driver(struct device_driver * drv)
{
	struct bus_type * bus = get_bus(drv->bus);
	int error = 0;

	if (bus) {
		pr_debug("bus %s: add driver %s\n", bus->name, drv->name);
		error = kobject_set_name(&drv->kobj, "%s", drv->name);
		if (error) {
			put_bus(bus);
			return error;
		}
		drv->kobj.kset = &bus->drivers;
		if ((error = kobject_register(&drv->kobj))) {
			put_bus(bus);
			return error;
		}

		driver_attach(drv);
451
		klist_add_tail(&drv->knode_bus, &bus->klist_drivers);
L
Linus Torvalds 已提交
452 453 454
		module_add_driver(drv->owner, drv);

		driver_add_attrs(bus, drv);
455
		driver_create_file(drv, &driver_attr_unbind);
456
		driver_create_file(drv, &driver_attr_bind);
L
Linus Torvalds 已提交
457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473
	}
	return error;
}


/**
 *	bus_remove_driver - delete driver from bus's knowledge.
 *	@drv:	driver.
 *
 *	Detach the driver from the devices it controls, and remove
 *	it from its bus's list of drivers. Finally, we drop the reference
 *	to the bus we took in bus_add_driver().
 */

void bus_remove_driver(struct device_driver * drv)
{
	if (drv->bus) {
474
		driver_remove_file(drv, &driver_attr_bind);
475
		driver_remove_file(drv, &driver_attr_unbind);
L
Linus Torvalds 已提交
476
		driver_remove_attrs(drv->bus, drv);
477
		klist_remove(&drv->knode_bus);
L
Linus Torvalds 已提交
478 479 480 481 482 483 484 485 486 487 488 489
		pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
		driver_detach(drv);
		module_remove_driver(drv);
		kobject_unregister(&drv->kobj);
		put_bus(drv->bus);
	}
}


/* Helper for bus_rescan_devices's iter */
static int bus_rescan_devices_helper(struct device *dev, void *data)
{
490 491
	if (!dev->driver)
		device_attach(dev);
L
Linus Torvalds 已提交
492 493 494 495
	return 0;
}

/**
496 497
 * bus_rescan_devices - rescan devices on the bus for possible drivers
 * @bus: the bus to scan.
L
Linus Torvalds 已提交
498
 *
499 500 501
 * This function will look for devices on the bus with no driver
 * attached and rescan it against existing drivers to see if it matches
 * any by calling device_attach() for the unbound devices.
L
Linus Torvalds 已提交
502
 */
503
void bus_rescan_devices(struct bus_type * bus)
L
Linus Torvalds 已提交
504
{
505
	bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
L
Linus Torvalds 已提交
506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570
}


struct bus_type * get_bus(struct bus_type * bus)
{
	return bus ? container_of(subsys_get(&bus->subsys), struct bus_type, subsys) : NULL;
}

void put_bus(struct bus_type * bus)
{
	subsys_put(&bus->subsys);
}


/**
 *	find_bus - locate bus by name.
 *	@name:	name of bus.
 *
 *	Call kset_find_obj() to iterate over list of buses to
 *	find a bus by name. Return bus if found.
 *
 *	Note that kset_find_obj increments bus' reference count.
 */

struct bus_type * find_bus(char * name)
{
	struct kobject * k = kset_find_obj(&bus_subsys.kset, name);
	return k ? to_bus(k) : NULL;
}


/**
 *	bus_add_attrs - Add default attributes for this bus.
 *	@bus:	Bus that has just been registered.
 */

static int bus_add_attrs(struct bus_type * bus)
{
	int error = 0;
	int i;

	if (bus->bus_attrs) {
		for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
			if ((error = bus_create_file(bus,&bus->bus_attrs[i])))
				goto Err;
		}
	}
 Done:
	return error;
 Err:
	while (--i >= 0)
		bus_remove_file(bus,&bus->bus_attrs[i]);
	goto Done;
}

static void bus_remove_attrs(struct bus_type * bus)
{
	int i;

	if (bus->bus_attrs) {
		for (i = 0; attr_name(bus->bus_attrs[i]); i++)
			bus_remove_file(bus,&bus->bus_attrs[i]);
	}
}

571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600
static void klist_devices_get(struct klist_node *n)
{
	struct device *dev = container_of(n, struct device, knode_bus);

	get_device(dev);
}

static void klist_devices_put(struct klist_node *n)
{
	struct device *dev = container_of(n, struct device, knode_bus);

	put_device(dev);
}

static void klist_drivers_get(struct klist_node *n)
{
	struct device_driver *drv = container_of(n, struct device_driver,
						 knode_bus);

	get_driver(drv);
}

static void klist_drivers_put(struct klist_node *n)
{
	struct device_driver *drv = container_of(n, struct device_driver,
						 knode_bus);

	put_driver(drv);
}

L
Linus Torvalds 已提交
601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633
/**
 *	bus_register - register a bus with the system.
 *	@bus:	bus.
 *
 *	Once we have that, we registered the bus with the kobject
 *	infrastructure, then register the children subsystems it has:
 *	the devices and drivers that belong to the bus.
 */
int bus_register(struct bus_type * bus)
{
	int retval;

	retval = kobject_set_name(&bus->subsys.kset.kobj, "%s", bus->name);
	if (retval)
		goto out;

	subsys_set_kset(bus, bus_subsys);
	retval = subsystem_register(&bus->subsys);
	if (retval)
		goto out;

	kobject_set_name(&bus->devices.kobj, "devices");
	bus->devices.subsys = &bus->subsys;
	retval = kset_register(&bus->devices);
	if (retval)
		goto bus_devices_fail;

	kobject_set_name(&bus->drivers.kobj, "drivers");
	bus->drivers.subsys = &bus->subsys;
	bus->drivers.ktype = &ktype_driver;
	retval = kset_register(&bus->drivers);
	if (retval)
		goto bus_drivers_fail;
634

635 636
	klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put);
	klist_init(&bus->klist_drivers, klist_drivers_get, klist_drivers_put);
L
Linus Torvalds 已提交
637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673
	bus_add_attrs(bus);

	pr_debug("bus type '%s' registered\n", bus->name);
	return 0;

bus_drivers_fail:
	kset_unregister(&bus->devices);
bus_devices_fail:
	subsystem_unregister(&bus->subsys);
out:
	return retval;
}


/**
 *	bus_unregister - remove a bus from the system
 *	@bus:	bus.
 *
 *	Unregister the child subsystems and the bus itself.
 *	Finally, we call put_bus() to release the refcount
 */
void bus_unregister(struct bus_type * bus)
{
	pr_debug("bus %s: unregistering\n", bus->name);
	bus_remove_attrs(bus);
	kset_unregister(&bus->drivers);
	kset_unregister(&bus->devices);
	subsystem_unregister(&bus->subsys);
}

int __init buses_init(void)
{
	return subsystem_register(&bus_subsys);
}


EXPORT_SYMBOL_GPL(bus_for_each_dev);
674
EXPORT_SYMBOL_GPL(bus_find_device);
L
Linus Torvalds 已提交
675 676 677 678 679 680 681 682 683 684 685 686 687
EXPORT_SYMBOL_GPL(bus_for_each_drv);

EXPORT_SYMBOL_GPL(bus_add_device);
EXPORT_SYMBOL_GPL(bus_remove_device);
EXPORT_SYMBOL_GPL(bus_register);
EXPORT_SYMBOL_GPL(bus_unregister);
EXPORT_SYMBOL_GPL(bus_rescan_devices);
EXPORT_SYMBOL_GPL(get_bus);
EXPORT_SYMBOL_GPL(put_bus);
EXPORT_SYMBOL_GPL(find_bus);

EXPORT_SYMBOL_GPL(bus_create_file);
EXPORT_SYMBOL_GPL(bus_remove_file);