开发字符驱动时,应该有如下框架:
1.构建file_operation,
static struct file_operations second_drv_fops = {
.owner = THIS_MODULE,
.open = second_drv_open,
.read = second_drv_write,
};
2.在结构体之前加入操作函数
static int first_drv_open(struct inode *inode, struct file *file)
{
return 0;
}
ssize_t second_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
return 0;
}
3.写入入口和出口函数,入口函数的主要功能是注册结构体,出口函数反之。在这里,我们为了使系统自动注册,加入一些代码。
static struct class *seconddrv_class;
static struct class_device *seconddrv_class_dev;
static int second_drv_init(void)
{
major = register_chrdev(0, "key_drv", &second_drv_fops);
seconddrv_class = class_create(THIS_MODULE, "seconddrv");
seconddrv_class_dev = class_device_create(seconddrv_class, NULL, MKDEV(major, 0), NULL, "xyz1"); /* /dev/xyz */
printk("register a char device: key_drv !\n");
return 0;
}
static int second_drv_exit(void)
{
unregister_chrdev(major, "key_drv");
class_device_unregister(seconddrv_class_dev);
class_destroy(seconddrv_class);
printk("unregister a char device: key_drv !\n");
return 0;
}
module_init(second_drv_init);
module_exit(second_drv_exit);
MODULE_LICENSE("GPL");