linux2.6 总线设备驱动模型

总线设备驱动模型：其中的设备，驱动是什么关系？与真实的物理设备是如何对应的？    欢迎留言讨论。

总线由bus_type描述：

struct bus_type my_bus_type = {
    .name = "my_bus",
    .match = my_match,         // 当一个新设备或者驱动被添加到这个总线时，该方法被调用，用于判断指定的驱动程序与指定的设备是否匹配，可以则返回非零值
};

总线也是设备：

struct device my_bus = {
    .bus_id   = "my_bus0",
    .release  = my_bus_release
};

总线上的设备：struct device my_dev = {
    .bus = &my_bus_type,              // 所属的总线
    .parent = &my_bus,                    // 父设备，即总线设备
    .release = my_dev_release,
};

总线上的驱动：

struct device_driver my_driver = {
    .name = "my_dev",                            // 与设备的bus_id相比较来判断是否匹配
    .bus = &my_bus_type,
    .probe = my_probe,                           // 匹配成功后会执行(包括系统引导、设备插入)，先有设备后有驱动(如引导启动时)，先有驱动后有设备(如热插拔)
    .remove    = my_remove,                  // 设备拔出时调用
};

会在sysfs文件系统中创建相应的bus目录和属性文件。

相关结构：

struct bus_type {
	const char		* name;
	struct module		* owner;

	struct kset		subsys;
	struct kset		drivers;
	struct kset		devices;
	struct klist		klist_devices;
	struct klist		klist_drivers;

	struct blocking_notifier_head bus_notifier;

	struct bus_attribute	* bus_attrs;
	struct device_attribute	* dev_attrs;
	struct driver_attribute	* drv_attrs;

	int		(*match)(struct device * dev, struct device_driver * drv);
	int		(*uevent)(struct device *dev, struct kobj_uevent_env *env);    // 在为用户空间产生热插拔事件之前，这个方法允许总线添加环境变量
	int		(*probe)(struct device * dev);
	int		(*remove)(struct device * dev);
	void		(*shutdown)(struct device * dev);

	int (*suspend)(struct device * dev, pm_message_t state);
	int (*suspend_late)(struct device * dev, pm_message_t state);
	int (*resume_early)(struct device * dev);
	int (*resume)(struct device * dev);

	unsigned int drivers_autoprobe:1;
};

struct device {
	struct klist		klist_children;
	struct klist_node	knode_parent;		/* node in sibling list */
	struct klist_node	knode_driver;
	struct klist_node	knode_bus;
	struct device		*parent;

	struct kobject kobj;
	char	bus_id[BUS_ID_SIZE];	/* position on parent bus */
	struct device_type	*type;
	unsigned		is_registered:1;
	unsigned		uevent_suppress:1;

	struct semaphore	sem;	/* semaphore to synchronize calls to
					 * its driver.
					 */

	struct bus_type	* bus;		/* type of bus device is on */
	struct device_driver *driver;	/* which driver has allocated this
					   device */
	void		*driver_data;	/* data private to the driver */
	void		*platform_data;	/* Platform specific data, device
					   core doesn't touch it */
	struct dev_pm_info	power;

#ifdef CONFIG_NUMA
	int		numa_node;	/* NUMA node this device is close to */
#endif
	u64		*dma_mask;	/* dma mask (if dma'able device) */
	u64		coherent_dma_mask;/* Like dma_mask, but for
					     alloc_coherent mappings as
					     not all hardware supports
					     64 bit addresses for consistent
					     allocations such descriptors. */

	struct list_head	dma_pools;	/* dma pools (if dma'ble) */

	struct dma_coherent_mem	*dma_mem; /* internal for coherent mem
					     override */
	/* arch specific additions */
	struct dev_archdata	archdata;

	spinlock_t		devres_lock;
	struct list_head	devres_head;

	/* class_device migration path */
	struct list_head	node;
	struct class		*class;
	dev_t			devt;		/* dev_t, creates the sysfs "dev" */
	struct attribute_group	**groups;	/* optional groups */

	void	(*release)(struct device * dev);
};

struct device_driver {
	const char		* name;
	struct bus_type		* bus;

	struct kobject		kobj;
	struct klist		klist_devices;
	struct klist_node	knode_bus;

	struct module		* owner;
	const char 		* mod_name;	/* used for built-in modules */
	struct module_kobject	* mkobj;

	int	(*probe)	(struct device * dev);
	int	(*remove)	(struct device * dev);
	void	(*shutdown)	(struct device * dev);
	int	(*suspend)	(struct device * dev, pm_message_t state);
	int	(*resume)	(struct device * dev);
};

struct bus_attribute {
	struct attribute	attr;
	ssize_t (*show)(struct bus_type *, char * buf);
	ssize_t (*store)(struct bus_type *, const char * buf, size_t count);
};

#define BUS_ATTR(_name,_mode,_show,_store)    \
struct bus_attribute bus_attr_##_name = __ATTR(_name,_mode,_show,_store)

/* sysfs interface for exporting driver attributes */

struct driver_attribute {
	struct attribute	attr;
	ssize_t (*show)(struct device_driver *, char * buf);
	ssize_t (*store)(struct device_driver *, const char * buf, size_t count);
};

#define DRIVER_ATTR(_name,_mode,_show,_store)    \
struct driver_attribute driver_attr_##_name = __ATTR(_name,_mode,_show,_store)

/* interface for exporting device attributes */
struct device_attribute {
	struct attribute	attr;
	ssize_t (*show)(struct device *dev, struct device_attribute *attr,
			char *buf);
	ssize_t (*store)(struct device *dev, struct device_attribute *attr,
			 const char *buf, size_t count);
};

#define DEVICE_ATTR(_name,_mode,_show,_store) \
struct device_attribute dev_attr_##_name = __ATTR(_name,_mode,_show,_store)

/**
 * Use these macros to make defining attributes easier. See include/linux/device.h
 * for examples..
 */

#define __ATTR(_name,_mode,_show,_store) { \
	.attr = {.name = __stringify(_name), .mode = _mode },	\
	.show	= _show,					\
	.store	= _store,					\
}

/* FIXME
 * The *owner field is no longer used, but leave around
 * until the tree gets cleaned up fully.
 */
struct attribute {
	const char		*name;
	struct module		*owner;
	mode_t			mode;
};

函数：

/**
 *	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_create_file(struct bus_type * bus, struct bus_attribute * attr)
{
	int error;
	if (bus_get(bus)) {
		error = sysfs_create_file(&bus->subsys.kobj, &attr->attr);
		bus_put(bus);
	} else
		error = -EINVAL;
	return error;
}

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

static struct bus_type *bus_get(struct bus_type *bus)
{
	return bus ? container_of(kset_get(&bus->subsys),
				struct bus_type, subsys) : NULL;
}

static void bus_put(struct bus_type *bus)
{
	kset_put(&bus->subsys);
}

static inline void kset_put(struct kset * k)
{
    kobject_put(&k->kobj);
}

/**
 *	device_register - register a device with the system.
 *	@dev:	pointer to the device structure
 *
 *	This happens in two clean steps - initialize the device
 *	and add it to the system. The two steps can be called
 *	separately, but this is the easiest and most common.
 *	I.e. you should only call the two helpers separately if
 *	have a clearly defined need to use and refcount the device
 *	before it is added to the hierarchy.
 */

int device_register(struct device *dev)
{
	device_initialize(dev);
	return device_add(dev);
}

/**
 *	device_initialize - init device structure.
 *	@dev:	device.
 *
 *	This prepares the device for use by other layers,
 *	including adding it to the device hierarchy.
 *	It is the first half of device_register(), if called by
 *	that, though it can also be called separately, so one
 *	may use @dev's fields (e.g. the refcount).
 */

void device_initialize(struct device *dev)
{
	kobj_set_kset_s(dev, devices_subsys);
	kobject_init(&dev->kobj);
	klist_init(&dev->klist_children, klist_children_get,
		   klist_children_put);
	INIT_LIST_HEAD(&dev->dma_pools);
	INIT_LIST_HEAD(&dev->node);
	init_MUTEX(&dev->sem);
	spin_lock_init(&dev->devres_lock);
	INIT_LIST_HEAD(&dev->devres_head);
	device_init_wakeup(dev, 0);
	set_dev_node(dev, -1);
}

/**
 *	device_add - add device to device hierarchy.
 *	@dev:	device.
 *
 *	This is part 2 of device_register(), though may be called
 *	separately _iff_ device_initialize() has been called separately.
 *
 *	This adds it to the kobject hierarchy via kobject_add(), adds it
 *	to the global and sibling lists for the device, then
 *	adds it to the other relevant subsystems of the driver model.
 */
int device_add(struct device *dev)
{
	struct device *parent = NULL;
	struct class_interface *class_intf;
	int error = -EINVAL;

	dev = get_device(dev);
	if (!dev || !strlen(dev->bus_id))
		goto Error;

	pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);

	parent = get_device(dev->parent);
	error = setup_parent(dev, parent);
	if (error)
		goto Error;

	/* first, register with generic layer. */
	kobject_set_name(&dev->kobj, "%s", dev->bus_id);
	error = kobject_add(&dev->kobj);
	if (error)
		goto Error;

	/* notify platform of device entry */
	if (platform_notify)
		platform_notify(dev);

	/* notify clients of device entry (new way) */
	if (dev->bus)
		blocking_notifier_call_chain(&dev->bus->bus_notifier,
					     BUS_NOTIFY_ADD_DEVICE, dev);

	error = device_create_file(dev, &uevent_attr);
	if (error)
		goto attrError;

	if (MAJOR(dev->devt)) {
		error = device_create_file(dev, &devt_attr);
		if (error)
			goto ueventattrError;
	}

	error = device_add_class_symlinks(dev);
	if (error)
		goto SymlinkError;
	error = device_add_attrs(dev);
	if (error)
		goto AttrsError;
	error = dpm_sysfs_add(dev);
	if (error)
		goto PMError;
	device_pm_add(dev);
	error = bus_add_device(dev);
	if (error)
		goto BusError;
	kobject_uevent(&dev->kobj, KOBJ_ADD);
	bus_attach_device(dev);
	if (parent)
		klist_add_tail(&dev->knode_parent, &parent->klist_children);

	if (dev->class) {
		down(&dev->class->sem);
		/* tie the class to the device */
		list_add_tail(&dev->node, &dev->class->devices);

		/* notify any interfaces that the device is here */
		list_for_each_entry(class_intf, &dev->class->interfaces, node)
			if (class_intf->add_dev)
				class_intf->add_dev(dev, class_intf);
		up(&dev->class->sem);
	}
 Done:
	put_device(dev);
	return error;
 BusError:
	device_pm_remove(dev);
	dpm_sysfs_remove(dev);
 PMError:
	if (dev->bus)
		blocking_notifier_call_chain(&dev->bus->bus_notifier,
					     BUS_NOTIFY_DEL_DEVICE, dev);
	device_remove_attrs(dev);
 AttrsError:
	device_remove_class_symlinks(dev);
 SymlinkError:
	if (MAJOR(dev->devt))
		device_remove_file(dev, &devt_attr);

	if (dev->class) {
		sysfs_remove_link(&dev->kobj, "subsystem");
		/* If this is not a "fake" compatible device, remove the
		 * symlink from the class to the device. */
		if (dev->kobj.parent != &dev->class->subsys.kobj)
			sysfs_remove_link(&dev->class->subsys.kobj,
					  dev->bus_id);
		if (parent) {
#ifdef CONFIG_SYSFS_DEPRECATED
			char *class_name = make_class_name(dev->class->name,
							   &dev->kobj);
			if (class_name)
				sysfs_remove_link(&dev->parent->kobj,
						  class_name);
			kfree(class_name);
#endif
			sysfs_remove_link(&dev->kobj, "device");
		}
	}
 ueventattrError:
	device_remove_file(dev, &uevent_attr);
 attrError:
	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
	kobject_del(&dev->kobj);
 Error:
	if (parent)
		put_device(parent);
	goto Done;
}

/**
 *	device_create_file - create sysfs attribute file for device.
 *	@dev:	device.
 *	@attr:	device attribute descriptor.
 */

int device_create_file(struct device * dev, struct device_attribute * attr)
{
	int error = 0;
	if (get_device(dev)) {
		error = sysfs_create_file(&dev->kobj, &attr->attr);
		put_device(dev);
	}
	return error;
}

/**
 *	device_remove_file - remove sysfs attribute file.
 *	@dev:	device.
 *	@attr:	device attribute descriptor.
 */

void device_remove_file(struct device * dev, struct device_attribute * attr)
{
	if (get_device(dev)) {
		sysfs_remove_file(&dev->kobj, &attr->attr);
		put_device(dev);
	}
}

int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
{
	BUG_ON(!kobj || !kobj->sd || !attr);

	return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);

}

int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr, int type){umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;struct sysfs_addrm_cxt acxt;struct sysfs_dirent *sd;int rc;sd = sysfs_new_dirent(attr->name, mode, type);if (!sd)return -ENOMEM;sd->s_attr.attr = (void *)attr;sysfs_addrm_start(&acxt, dir_sd);rc = sysfs_add_one(&acxt, sd);sysfs_addrm_finish(&acxt);if (rc)sysfs_put(sd);return rc;}/** * sysfs_create_file - create an attribute file for an object. * @kobj: object we're creating for. * @attr: attribute descriptor. */

/**
 *	sysfs_remove_file - remove an object attribute.
 *	@kobj:	object we're acting for.
 *	@attr:	attribute descriptor.
 *
 *	Hash the attribute name and kill the victim.
 */

void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
{
	sysfs_hash_and_remove(kobj->sd, attr->name);
}
int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
{
	struct sysfs_addrm_cxt acxt;
	struct sysfs_dirent *sd;

	if (!dir_sd)
		return -ENOENT;

	sysfs_addrm_start(&acxt, dir_sd);

	sd = sysfs_find_dirent(dir_sd, name);
	if (sd)
		sysfs_remove_one(&acxt, sd);

	sysfs_addrm_finish(&acxt);

	if (sd)
		return 0;
	else
		return -ENOENT;
}

/**
 *	get_device - increment reference count for device.
 *	@dev:	device.
 *
 *	This simply forwards the call to kobject_get(), though
 *	we do take care to provide for the case that we get a NULL
 *	pointer passed in.
 */

struct device * get_device(struct device * dev)
{
	return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
}


/**
 *	put_device - decrement reference count.
 *	@dev:	device in question.
 */
void put_device(struct device * dev)
{
	if (dev)
		kobject_put(&dev->kobj);
}

/**
 *	driver_register - register driver with bus
 *	@drv:	driver to register
 *
 *	We pass off most of the work to the bus_add_driver() call,
 *	since most of the things we have to do deal with the bus
 *	structures.
 */
int driver_register(struct device_driver * drv)
{
	if ((drv->bus->probe && drv->probe) ||
	    (drv->bus->remove && drv->remove) ||
	    (drv->bus->shutdown && drv->shutdown)) {
		printk(KERN_WARNING "Driver '%s' needs updating - please use bus_type methods\n", drv->name);
	}
	klist_init(&drv->klist_devices, NULL, NULL);
	return bus_add_driver(drv);
}

/**
 *	driver_unregister - remove driver from system.
 *	@drv:	driver.
 *
 *	Again, we pass off most of the work to the bus-level call.
 */

void driver_unregister(struct device_driver * drv)
{
	bus_remove_driver(drv);
}

/**
 *	klist_init - Initialize a klist structure. 
 *	@k:	The klist we're initializing.
 *	@get:	The get function for the embedding object (NULL if none)
 *	@put:	The put function for the embedding object (NULL if none)
 *
 * Initialises the klist structure.  If the klist_node structures are
 * going to be embedded in refcounted objects (necessary for safe
 * deletion) then the get/put arguments are used to initialise
 * functions that take and release references on the embedding
 * objects.
 */

void klist_init(struct klist * k, void (*get)(struct klist_node *),
		void (*put)(struct klist_node *))
{
	INIT_LIST_HEAD(&k->k_list);
	spin_lock_init(&k->k_lock);
	k->get = get;
	k->put = put;
}

/**
 *	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);
}

/**
 *	driver_create_file - create sysfs file for driver.
 *	@drv:	driver.
 *	@attr:	driver attribute descriptor.
 */

int driver_create_file(struct device_driver * drv, struct driver_attribute * attr)
{
	int error;
	if (get_driver(drv)) {
		error = sysfs_create_file(&drv->kobj, &attr->attr);
		put_driver(drv);
	} else
		error = -EINVAL;
	return error;
}


/**
 *	driver_remove_file - remove sysfs file for driver.
 *	@drv:	driver.
 *	@attr:	driver attribute descriptor.
 */

void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr)
{
	if (get_driver(drv)) {
		sysfs_remove_file(&drv->kobj, &attr->attr);
		put_driver(drv);
	}
}

/**
 *	get_driver - increment driver reference count.
 *	@drv:	driver.
 */
struct device_driver * get_driver(struct device_driver * drv)
{
	return drv ? to_drv(kobject_get(&drv->kobj)) : NULL;
}


/**
 *	put_driver - decrement driver's refcount.
 *	@drv:	driver.
 */
void put_driver(struct device_driver * drv)
{
	kobject_put(&drv->kobj);
}

实例：

bus_basic.c

创建目录：/sys/bus/my_bus

#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>

MODULE_AUTHOR("gzliu");
MODULE_LICENSE("Dual BSD/GPL");

static char *Version = "$Revision: 1.0$"
static int my_match(struct device *dev, struct device_driver *driver)
{
	return !strncmp(dev->bus_id, driver->name, strlen(driver->name));
}

struct bus_type my_bus_type = {
	.name = "my_bus",
	.match = my_match,
};

static ssize_t show_bus_version(struct bus_type *bus, char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%s\n", Version);
}

static BUS_ATTR(version, S_IRUGO, show_bus_version, NULL);


static int __init my_bus_init(void)
{
	int ret;
        
        /*注册总线*/
	ret = bus_register(&my_bus_type);
	if (ret)
		return ret;
		
	/*创建属性文件*/	
	if (bus_create_file(&my_bus_type, &bus_attr_version))
		printk(KERN_NOTICE "Fail to create version attribute!\n");
		
	return ret;
}

static void my_bus_exit(void)
{
	bus_unregister(&my_bus_type);
}

module_init(my_bus_init);
module_exit(my_bus_exit);

bus.c

创建目录：/sys/bus/my_bus

创建目录：/sys/devices/my_bus0

#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>

MODULE_AUTHOR("gzliu");
MODULE_LICENSE("Dual BSD/GPL");

static char *Version = "$Revision: 1.9 {1}quot;;

static int my_match(struct device *dev, struct device_driver *driver)
{
	return !strncmp(dev->bus_id, driver->name, strlen(driver->name));
}

static void my_bus_release(struct device *dev)
{
	printk(KERN_DEBUG "my bus release\n");
}
	
struct device my_bus = {
	.bus_id   = "my_bus0",
	.release  = my_bus_release
};


struct bus_type my_bus_type = {
	.name = "my_bus",
	.match = my_match,
};

EXPORT_SYMBOL(my_bus);
EXPORT_SYMBOL(my_bus_type);


/*
 * Export a simple attribute.
 */
static ssize_t show_bus_version(struct bus_type *bus, char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%s\n", Version);
}

static BUS_ATTR(version, S_IRUGO, show_bus_version, NULL);


static int __init my_bus_init(void)
{
	int ret;
        
        /*注册总线*/
	ret = bus_register(&my_bus_type);
	if (ret)
		return ret;
		
	/*创建属性文件*/	
	if (bus_create_file(&my_bus_type, &bus_attr_version))
		printk(KERN_NOTICE "Fail to create version attribute!\n");
	
	/*注册总线设备*/
	ret = device_register(&my_bus);
	if (ret)
		printk(KERN_NOTICE "Fail to register device:my_bus!\n");
		
	return ret;
}

static void my_bus_exit(void)
{
	device_unregister(&my_bus);
	bus_unregister(&my_bus_type);
}

module_init(my_bus_init);
module_exit(my_bus_exit);

driver.c

#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>

MODULE_AUTHOR("gzliu");
MODULE_LICENSE("Dual BSD/GPL");

extern struct bus_type my_bus_type;

static int my_probe(struct device *dev)
{
    printk("Driver found device which my driver can handle!\n");
    return 0;
}

static int my_remove(struct device *dev)
{
    printk("Driver found device unpluged!\n");
    return 0;
}

struct device_driver my_driver = {
	.name = "my_dev",
	.bus = &my_bus_type,
	.probe = my_probe,
        .remove	= my_remove,
};

/*
 * Export a simple attribute.
 */
static ssize_t mydriver_show(struct device_driver *driver, char *buf)
{
	return sprintf(buf, "%s\n", "This is my driver!");
}

static DRIVER_ATTR(drv, S_IRUGO, mydriver_show, NULL);

static int __init my_driver_init(void)
{
	int ret = 0;
        
        /*注册驱动*/
	driver_register(&my_driver);
		
	/*创建属性文件*/
	driver_create_file(&my_driver, &driver_attr_drv);
	
	return ret;	

}

static void my_driver_exit(void)
{
	driver_unregister(&my_driver);
}

module_init(my_driver_init);
module_exit(my_driver_exit);

device.c

创建文件：/sys/bus/my_bus/my_dev

#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>

MODULE_AUTHOR("gzliu");
MODULE_LICENSE("Dual BSD/GPL");

extern struct device my_bus; 
extern struct bus_type my_bus_type;

/* Why need this ?*/
static void my_dev_release(struct device *dev)
{ 
	
}

struct device my_dev = {
	.bus = &my_bus_type,
	.parent = &my_bus,
	.release = my_dev_release,
};

/*
 * Export a simple attribute.
 */
static ssize_t mydev_show(struct device *dev, char *buf)
{
	return sprintf(buf, "%s\n", "This is my device!");
}

static DEVICE_ATTR(dev, S_IRUGO, mydev_show, NULL);

static int __init my_device_init(void)
{
	int ret = 0;
        
        /* 初始化设备 */
	strncpy(my_dev.bus_id, "my_dev", BUS_ID_SIZE);
        
        /*注册设备*/
	device_register(&my_dev);
		
	/*创建属性文件*/
	device_create_file(&my_dev, &dev_attr_dev);
	
	return ret;	

}

static void my_device_exit(void)
{
	device_unregister(&my_dev);
}

module_init(my_device_init);
module_exit(my_device_exit);