【嵌入式】字符驱动开发框架

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");