linux设备驱动模板

//linux 字符设备驱动的组成模板
struct xxx_dev_t{
struct cdev cdev;
…
};

/*设备驱动模块加载函数*/static int __init xxx_init(void){...cdev_init(&xxx_dev.cdev, &xxx_fpos);    /*初始化cdev*/xxx_dev.cdev.owner = THIS_MODULE;/*获取字符设备号*/if(xxx_major){    register_chrdev_region(xxx_dev_no,1,DEV_NAME);} else {    alloc_chrdev_region(&xxx_dev_no,0,1,DEV_NAME);}ret = cdev_add(&xxx_dev.cdev, xxx_dev_no, 1);  /*注册设备*/...} /*设备驱动模块卸载模块*/ static void __exit xxx_exit(void) { unregister_chrdev_region(xxx_dev_no, 1);   /*释放占用的设备号*/ cdev_del(&xxx_dev.cdev);                   /*注销设备*/ ... }  3. file_operations定义了字符设备驱动提供给虚拟文件系统的接口函数，常见的字符设备驱动的这三个函数的形式如下：  //读设备  ssize_t xxx_read(struct file *filp ,char __ user *buf, size_t count, loff_t *f_ops)  {        ...        copy_to_user(buf, ..., ...);        ...  }

//写设备
ssize_t xxx_write(struct file *filp , const char __user *buf , size_t count, loff_t *f_ops)
{
…
copy_from_user(…, buf, …);
…
}

//ioctl 函数
long xxx_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
…
switch(cmd){

case xxx_CMD1:     ...;     break;...default ://不支持的命令        return -ENOTTY;}return 0;

}