Linux字符设备驱动

/*Linux字符设备驱动源代码scdd.c*/

#include /*模块头文件*/

#include

#include /*dev_t头文件*/

#include /*MAJOR和MINOR宏头文件*/

#include /*register_chrdev_region等函数

file_operations结构体*/

#include /*struct cdev结构体*/

#include /*copy_to_user函数*/

#define DEVICE_NAME "scdd" /*定义设备名*/

#define DEVICE_MAJOR 250

struct cdev my_cdev;

int scdd_open(struct inode *inode,structfile *filp)

{

return0;

}

int scdd_close(struct inode *inode,structfile *filp)

{

return0;

}

ssize_t scdd_read(struct file *filp,char__user *buff,size_t size,loff_t *offp)

{

intleft;

chardata=1;

for(left=size;left>0;left--)

{

/*拷贝数据到用户空间*/

copy_to_user(buff,&data,1);

buff++;

}

returnsize;

}

ssize_t scdd_write(struct file *filp,char__user *buff,size_t size,loff_t *offp)

{

return0;

}

/*file_operations结构体*/

struct file_operations scdd_fops={

.owner=THIS_MODULE,

.read=scdd_read,

.write=scdd_write,

.open=scdd_open,

.release=scdd_close,

};

static int __init scdd_init(void)

{ /*模块初始化函数*/

intsmajor;

smajor=DEVICE_MAJOR;

dev_tdev_n=MKDEV(smajor,0);

/*申请设备号*/

if(!register_chrdev_region(dev_n,1,DEVICE_NAME))

{ /*静态申请*/

printk("registersuccess\n");

}else

{

gotoregister_error;

}

/*else

{ /*动态申请*/

/*alloc_chrdev_region(&dev_n,0,1,DEVICE_NAME);

smajor=MAJOR(dev_n);

}*/

/*初始化cdev结构体*/

cdev_init(&my_cdev,&scdd_fops);

my_cdev.owner=THIS_MODULE;

my_cdev.ops=&scdd_fops;

/*注册字符设备*/

cdev_add(&my_cdev,dev_n,1);

return0;

register_error:

unregister_chrdev_region(MKDEV(DEVICE_MAJOR,0),1);

return0;

}

static void __exit scdd_exit(void)

{ /*模块卸载函数*/

cdev_del(&my_cdev);

unregister_chrdev_region(MKDEV(DEVICE_MAJOR,0),1);

}

module_init(scdd_init);

module_exit(scdd_exit);

MODULE_LICENSE("Dual BSD/GPL");

这个程序只是简单演示字符注册的一个完整过程，并不带有复杂的操作，调用read时向用户空间写全1