Linux设备驱动模型(2)

Linux设备驱动模型包含三个关键部分：总线，设备和驱动。首先在内核中注册总线，该总线会有一个bus_type的结构需要填充，同时总线本身也是一个设备，还需向内核注册该总线设备；其次向内核注册设备的时候需要知道该设备挂载在哪条总线上，需设置该设备的父设备为刚才注册的总线设备，然后需设置该设备的设备名，该设备名是匹配驱动的关键，在2.6.32内核以后没有了bus_id，取而代之的是用dev_set_name来设置设备名，用dev_name(&dev)来获得设备名；最后是注册驱动，驱动的名字是匹配设备的关键。

内核版本：Linux2.6.32.2

文件：bus.c

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

MODULE_AUTHOR("David Xie");
MODULE_LICENSE("Dual BSD/GPL");

static char *Version = "$Revision: 1.9 $";
/*
dev_name(dev)返回的是dev的kobject；当有驱动和设备挂载到该总线的时候，会调用match函数，该函数若返回非0值则会调用驱动的probe方法。在match中具体比较的方法笔记多，不同的总线有不同的方法，在这里比较设备的名字和驱动的名字是否一致。

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

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

/*

总线的名字是my_bus，可以在/sys/bus在发现该文件夹的存在。*/
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;
		
	/*创建总线属性文件*/	
	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);

设备device.c

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

MODULE_AUTHOR("David Xie");
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;
        
        /* ³õÊŒ»¯Éè±ž */
	//strncpy(my_dev.init_name, "my_dev", BUS_ID_SIZE);
        dev_set_name(&my_dev,"my_dev");
	//modify by xie.
        /*×¢²áÉè±ž*/
	device_register(&my_dev);
		
	/*ŽŽœšÊôÐÔÎÄŒþ*/
	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);

驱动driver.c

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

MODULE_AUTHOR("David Xie");
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;
        
        /*×¢²áÇý¶¯*/
	driver_register(&my_driver);
		
	/*ŽŽœšÊôÐÔÎÄŒþ*/
	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);

Linux设备驱动模型(2)

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