【迅为iTop4412学习笔记】21.补全字符驱动，编写应用（未完成）

声明

以下都是我刚开始看驱动视频的个人强行解读，如果有误请指出，共同进步。

本节目标

注册字符类设备

仅上代码，此处以后再写。

#include 
#include 
#include 
#include 
#include 
#include 
#include 

MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("MrYang");

#define DEV_MAJOR		0				/* 默认主设备号（为0则linux自动分配可用号码） */
#define DEV_MINOR		0				/* 默认次设备号（为0则linux自动分配可用号码） */
#define DEV_MINOR_NUM	2				/* 要注册的次设备的数量 */
#define DEV_NAME		"mryang_ascdev"	/* 设备名 */

// 初始化主次设备号
int device_major = DEV_MAJOR;
int device_minor = DEV_MINOR;

/*打开操作*/
static int chardevnode_open(struct inode *inode, struct file *file){
	printk(KERN_EMERG "chardevnode_open is success!\n");
	
	return 0;
}
/*关闭操作*/
static int chardevnode_release(struct inode *inode, struct file *file){
	printk(KERN_EMERG "chardevnode_release is success!\n");
	
	return 0;
}
/*IO操作*/
static long chardevnode_ioctl(struct file *file, unsigned int cmd, unsigned long arg){
	printk(KERN_EMERG "chardevnode_ioctl is success! cmd is %u,arg is %lu!\n",cmd,arg);
	return 0;
}

ssize_t chardevnode_read(struct file *file, char __user *buf, size_t count, loff_t *f_ops){
	return 0;
}

ssize_t chardevnode_write(struct file *file, const char __user *buf, size_t count, loff_t *f_ops){
	return 0;
}

loff_t chardevnode_llseek(struct file *file, loff_t offset, int ence){
	return 0;
}

// cdev结构体
struct cdev *my_cdev_ptr;

// 文件操作结构体
struct file_operations my_fops = {
	.owner = THIS_MODULE,
	
	.open = chardevnode_open,
	.release = chardevnode_release,
	.unlocked_ioctl = chardevnode_ioctl,
	.read = chardevnode_read,
	.write = chardevnode_write,
	.llseek = chardevnode_llseek,
};

struct class *myclass;

static int mryang_init(void)
{
	int ret, i;
	dev_t mryang_dev;
	
	printk(KERN_EMERG "HELLO MrYang\n");
	
	// 动态申请设备号
	ret = alloc_chrdev_region(&mryang_dev, device_minor, DEV_MINOR_NUM, DEV_NAME);
	if(ret < 0)
		printk(KERN_EMERG "failed!\n");
	else
		printk(KERN_EMERG "success!\n");
	
	// 提取主、次设备号
	device_major = MAJOR(mryang_dev);
	device_minor = MINOR(mryang_dev);
	printk(KERN_EMERG "major: %d, minor: %d\n", device_major, device_minor);
	
	// 注册设备类
	myclass = class_create(THIS_MODULE, DEV_NAME);
	
	
	// 静态申请内存大小（设备数*结构体就是大小）
	my_cdev_ptr = kmalloc( DEV_MINOR_NUM * sizeof(struct cdev), GFP_KERNEL);
	if(my_cdev_ptr==NULL)
	{
		printk(KERN_EMERG "kmalloc failed!\n");
		return -1;
	}
	
	memset(my_cdev_ptr, 0, DEV_MINOR_NUM * sizeof( struct cdev ) );		// 可省略，init会自动memset，看源码
	
	for(i=0;i<DEV_MINOR_NUM;i++)
	{
		// 初始化cdev，并绑定文件操作函数
		cdev_init(&my_cdev_ptr[i], &my_fops);
		// 赋值
		my_cdev_ptr[i].owner = THIS_MODULE;
		my_cdev_ptr[i].ops = &my_fops;
		// 注册到系统
		ret = cdev_add(&my_cdev_ptr[i], MKDEV(device_major, device_minor+i), 1);
		if( ret < 0 )
			printk(KERN_EMERG "cdev_add %d failed!\n", i);
		else
			printk(KERN_EMERG "cdev_add %d success!\n", i);
		/* 创建设备节点 */
		device_create(myclass,NULL, MKDEV(device_major, device_minor+i), NULL, DEV_NAME"%d",i);
	}
	
	return 0;
}

static void mryang_exit(void)
{
	int i;
	dev_t mryang_dev;
	// 设备号
	mryang_dev = MKDEV(device_major, device_minor);

	for(i=0;i<DEV_MINOR_NUM;i++)
	{	// 注销字符设备
		cdev_del(&my_cdev_ptr[i]);
		device_destroy(myclass,MKDEV(device_major, device_minor+i));
	}
	// 注销内存
	kfree(my_cdev_ptr);
	// 注销设备号
	unregister_chrdev_region(mryang_dev, DEV_MINOR_NUM);
	
	printk(KERN_EMERG "Bye MrYang\n");
}

module_init(mryang_init);
module_exit(mryang_exit);

#include 
#include 
#include 
#include 
#include 
#include 

int main(int argc, char* argv[])
{
	int fd;
	char *mryang_node0 = "/dev/mryang_ascdev0";
	char *mryang_node1 = "/dev/mryang_ascdev1";
	
	// 次设备 0
	fd = open(mryang_node0, O_RDWR|O_NDELAY);
	if(fd < 0)
	{
		printf("open %s failed!\n", mryang_node0);
	}
	else
	{
		printf("open %s success! fd=%d\n", mryang_node0, fd);
		ioctl(fd, 1, 2);
	}
	close(fd);	
	
	// 次设备 1
	fd = open(mryang_node1, O_RDWR|O_NDELAY);
	if(fd < 0)
	{
		printf("open %s failed!\n", mryang_node1);
	}
	else
	{
		printf("open %s success! fd=%d\n", mryang_node1, fd);
		ioctl(fd, 3, 4);
	}
	close(fd);
	
	return 0;
}