bus.c

linux 内核源代码

/**
 *	bus_attach_device - add device to bus
 *	@dev:	device tried to attach to a driver
 *
 *	- Add device to bus's list of devices.
 *	- Try to attach to driver.
 */
void bus_attach_device(struct device * dev)
{
	struct bus_type *bus = dev->bus;
	int ret = 0;

	if (bus) {
		dev->is_registered = 1;
		if (bus->drivers_autoprobe)
			ret = device_attach(dev);
		WARN_ON(ret < 0);
		if (ret >= 0)
			klist_add_tail(&dev->knode_bus, &bus->klist_devices);
		else
			dev->is_registered = 0;
	}
}

/**
 *	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, "subsystem");
		remove_deprecated_bus_links(dev);
		sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id);
		device_remove_attrs(dev->bus, dev);
		if (dev->is_registered) {
			dev->is_registered = 0;
			klist_del(&dev->knode_bus);
		}
		pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
		device_release_driver(dev);
		bus_put(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]);
	}
}

#ifdef CONFIG_HOTPLUG
/*
 * Thanks to drivers making their tables __devinit, we can't allow manual
 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
 */
static int __must_check add_bind_files(struct device_driver *drv)
{
	int ret;

	ret = driver_create_file(drv, &driver_attr_unbind);
	if (ret == 0) {
		ret = driver_create_file(drv, &driver_attr_bind);
		if (ret)
			driver_remove_file(drv, &driver_attr_unbind);
	}
	return ret;
}

static void remove_bind_files(struct device_driver *drv)
{
	driver_remove_file(drv, &driver_attr_bind);
	driver_remove_file(drv, &driver_attr_unbind);
}

static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
		show_drivers_autoprobe, store_drivers_autoprobe);

static int add_probe_files(struct bus_type *bus)
{
	int retval;

	retval = bus_create_file(bus, &bus_attr_drivers_probe);
	if (retval)
		goto out;

	retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
	if (retval)
		bus_remove_file(bus, &bus_attr_drivers_probe);
out:
	return retval;
}

static void remove_probe_files(struct bus_type *bus)
{
	bus_remove_file(bus, &bus_attr_drivers_autoprobe);
	bus_remove_file(bus, &bus_attr_drivers_probe);
}
#else
static inline int add_bind_files(struct device_driver *drv) { return 0; }
static inline void remove_bind_files(struct device_driver *drv) {}
static inline int add_probe_files(struct bus_type *bus) { return 0; }
static inline void remove_probe_files(struct bus_type *bus) {}
#endif

static ssize_t driver_uevent_store(struct device_driver *drv,
				   const char *buf, size_t count)
{
	enum kobject_action action;

	if (kobject_action_type(buf, count, &action) == 0)
		kobject_uevent(&drv->kobj, action);
	return count;
}
static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);

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

	if (!bus)
		return -EINVAL;

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

	if (drv->bus->drivers_autoprobe) {
		error = driver_attach(drv);
		if (error)
			goto out_unregister;
	}
	klist_add_tail(&drv->knode_bus, &bus->klist_drivers);
	module_add_driver(drv->owner, drv);

	error = driver_create_file(drv, &driver_attr_uevent);
	if (error) {
		printk(KERN_ERR "%s: uevent attr (%s) failed\n",
			__FUNCTION__, drv->name);
	}
	error = driver_add_attrs(bus, drv);
	if (error) {
		/* How the hell do we get out of this pickle? Give up */
		printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
			__FUNCTION__, drv->name);
	}
	error = add_bind_files(drv);
	if (error) {
		/* Ditto */
		printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
			__FUNCTION__, drv->name);
	}

	return error;
out_unregister:
	kobject_unregister(&drv->kobj);
out_put_bus:
	bus_put(bus);
	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)
		return;

	remove_bind_files(drv);
	driver_remove_attrs(drv->bus, drv);
	driver_remove_file(drv, &driver_attr_uevent);
	klist_remove(&drv->knode_bus);
	pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
	driver_detach(drv);
	module_remove_driver(drv);
	kobject_unregister(&drv->kobj);
	bus_put(drv->bus);
}


/* Helper for bus_rescan_devices's iter */
static int __must_check bus_rescan_devices_helper(struct device *dev,
						void *data)
{
	int ret = 0;

	if (!dev->driver) {
		if (dev->parent)	/* Needed for USB */
			down(&dev->parent->sem);
		ret = device_attach(dev);
		if (dev->parent)
			up(&dev->parent->sem);
	}
	return ret < 0 ? ret : 0;
}

/**
 * bus_rescan_devices - rescan devices on the bus for possible drivers
 * @bus: the bus to scan.
 *
 * 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.
 */
int bus_rescan_devices(struct bus_type * bus)
{
	return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
}

/**
 * device_reprobe - remove driver for a device and probe for a new driver
 * @dev: the device to reprobe
 *
 * This function detaches the attached driver (if any) for the given
 * device and restarts the driver probing process.  It is intended
 * to use if probing criteria changed during a devices lifetime and
 * driver attachment should change accordingly.
 */
int device_reprobe(struct device *dev)
{
	if (dev->driver) {
		if (dev->parent)        /* Needed for USB */
			down(&dev->parent->sem);
		device_release_driver(dev);
		if (dev->parent)
			up(&dev->parent->sem);
	}
	return bus_rescan_devices_helper(dev, NULL);
}
EXPORT_SYMBOL_GPL(device_reprobe);

/**
 *	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.
 */
#if 0
struct bus_type * find_bus(char * name)
{
	struct kobject * k = kset_find_obj(&bus_subsys.kset, name);
	return k ? to_bus(k) : NULL;
}
#endif  /*  0  */


/**
 *	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++) {
			error = bus_create_file(bus,&bus->bus_attrs[i]);
			if (error)
				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]);
	}
}

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 ssize_t bus_uevent_store(struct bus_type *bus,
				const char *buf, size_t count)
{
	enum kobject_action action;

	if (kobject_action_type(buf, count, &action) == 0)
		kobject_uevent(&bus->subsys.kobj, action);
	return count;
}
static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);

/**
 *	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;

	BLOCKING_INIT_NOTIFIER_HEAD(&bus->bus_notifier);

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

	bus->subsys.kobj.kset = &bus_subsys;

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

	retval = bus_create_file(bus, &bus_attr_uevent);
	if (retval)
		goto bus_uevent_fail;

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

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

	klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put);
	klist_init(&bus->klist_drivers, NULL, NULL);

	bus->drivers_autoprobe = 1;
	retval = add_probe_files(bus);
	if (retval)
		goto bus_probe_files_fail;

	retval = bus_add_attrs(bus);
	if (retval)
		goto bus_attrs_fail;

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

bus_attrs_fail:
	remove_probe_files(bus);
bus_probe_files_fail:
	kset_unregister(&bus->drivers);
bus_drivers_fail:
	kset_unregister(&bus->devices);
bus_devices_fail:
	bus_remove_file(bus, &bus_attr_uevent);
bus_uevent_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 bus_put() to release the refcount
 */
void bus_unregister(struct bus_type * bus)
{
	pr_debug("bus %s: unregistering\n", bus->name);
	bus_remove_attrs(bus);
	remove_probe_files(bus);
	kset_unregister(&bus->drivers);
	kset_unregister(&bus->devices);
	bus_remove_file(bus, &bus_attr_uevent);
	subsystem_unregister(&bus->subsys);
}

int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
{
	return blocking_notifier_chain_register(&bus->bus_notifier, nb);
}
EXPORT_SYMBOL_GPL(bus_register_notifier);

int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
{
	return blocking_notifier_chain_unregister(&bus->bus_notifier, nb);
}
EXPORT_SYMBOL_GPL(bus_unregister_notifier);

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


EXPORT_SYMBOL_GPL(bus_for_each_dev);
EXPORT_SYMBOL_GPL(bus_find_device);
EXPORT_SYMBOL_GPL(bus_for_each_drv);

EXPORT_SYMBOL_GPL(bus_register);
EXPORT_SYMBOL_GPL(bus_unregister);
EXPORT_SYMBOL_GPL(bus_rescan_devices);

EXPORT_SYMBOL_GPL(bus_create_file);
EXPORT_SYMBOL_GPL(bus_remove_file);