hello 驱动模块

#include <linux/kernel.h>#include <linux/module.h>#include <linux/init.h>#include <linux/fcntl.h>#include <linux/device.h>#include <linux/fs.h>#include <linux/cdev.h>#include <asm/uaccess.h>#define    DEVICE_NAME  "hello" #define    HELLO_MAJOR 249static int hello_major = HELLO_MAJOR;static struct cdev hello_dev;MODULE_LICENSE("GPL");static int  hello_open(struct inode *inode, struct file *file){    return 0;}static int  hello_release(struct inode *inode, struct file *file){    return 0;}static ssize_t hello_read(struct file *file, char  *buf, size_t cnt, loff_t *offset){return 0;}static ssize_t hello_write(struct file *file, const char *buf, size_t cnt, loff_t *offset){return 0;}static int  hello_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg){return 0;}static struct file_operations hello_fops = {    .owner      =      THIS_MODULE,    .read       =      hello_read,    .write      =      hello_write,          .release    =      hello_release,    .open=      hello_open,    .ioctl      =      hello_ioctl,  // 新版本内核使用 .unlocked_ioctl = };static int __init my_hello_module_init(void){int res = -1;int err;dev_t dev = MKDEV(hello_major,0);if(hello_major)res = register_chrdev_region(dev,1,DEVICE_NAME);else{res = alloc_chrdev_region(&dev,0,1,DEVICE_NAME);}if(res < 0){printk("Can't allocate major number for hello device\r\n");return res;}memset(&hello_dev,0,sizeof(hello_dev));/*初始化并添加cdev结构体*/cdev_init(&hello_dev,&hello_fops);hello_dev.owner = THIS_MODULE;hello_dev.ops= &hello_fops;err = cdev_add(&hello_dev,dev,1);if(err){printk("Add hello device error %d\n",err);}printk("Hello, my module is installed !\n");return 0;}static void __exit my_hello_module_cleanup(void){    dev_t dev;    cdev_del(&hello_dev);       dev = MKDEV(hello_major, 0);       unregister_chrdev_region(dev, 1);printk("Good-bye, my module was removed!\n");}module_init(my_hello_module_init);module_exit(my_hello_module_cleanup);