简单的Linux字符设备驱动

//---------------------------驱动程序的源程序---------------------------------#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <asm/uaccess.h>#define DATASIZE     1000MODULE_LICENSE（"GPL"）;int hello_major = 250;
int hello_minor = 0;
int number_of_devices = 1;
char data[DATASIZE] = "";
struct cdev cdev;
dev_t dev = 0;static int hello_open（struct inode *inode, struct file *file）{
    return 0;
}static int hello_release（struct inode *inode, struct file *file）{
    return 0;
}ssize_t hello_write（struct file *file, const char __user *buf, size_t count, loff_t *f_pos）{
    ssize_t ret = 0;
    printk（KERN_DEBUG"Writing %d bytes ", count）;
    if（count > DATASIZE） return -ENOMEM;
    if（count < 0） return -EINVAL;
    if（copy_from_user（data, buf, count）） {
        ret = -EFAULT;
    }
    else {
        data[DATASIZE]="";
        printk（KERN_DEBUG"Received:--- %s ---- ", data）;
        ret = count;
    }
    return ret;
}struct file_operations hello_fops = {
    .owner = THIS_MODULE,
    .open = hello_open,
    .release = hello_release,
    .write = hello_write
};static void char_reg_setup_cdev（void）{
    int error, devno = MKDEV（hello_major, hello_minor）;
    cdev_init（&cdev, &hello_fops）;
    cdev.owner = THIS_MODULE;
    cdev.ops   = &hello_fops;
    error = cdev_add（&cdev, devno, 1）;
    if（error）{
        printk（KERN_NOTICE"Error %d adding char_reg_setup_cdev", error）;
    }
}static int __init hello_init（void）{
    int result;
    dev = MKDEV（hello_major, hello_minor）;
    result = register_chrdev_region（dev, number_of_devices, "hello"）;
    if（result）{
        printk（KERN_WARNING"hello: can"t get major number %d ", hello_major）;
        return result;
    }
    char_reg_setup_cdev（）;
    return 0;
}static void __exit hello_exit（void）{
    dev_t devno = MKDEV（hello_major, hello_minor）;
    cdev_del（&cdev）;
    unregister_chrdev_region（devno, number_of_devices）;
}module_init（hello_init）;
module_exit（hello_exit）;