通过TCP/IP实现PC（客户端）远程控制开发板（服务器）上LED灯的实验

这篇我们来做个小实验，实现开发板上运行服务端，可以直接控制led灯，客户端通过socket连接到服务端，通过发送指令来远程控制服务端的led灯。

我们用平台总线的思想来编写驱动程序，这里分为LED平台驱动程序和LED平台设备程序。

先看看LED平台设备程序plat_led_pdev.c的代码:

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>

//led4、led5
#define GPF3_CON 0x114001e0
#define GPF3_SIZE 24
//led3
#define GPX1_CON 0x11000C20
#define GPX1_SIZE 24

struct resource	led_res[] = {
	//内存资源
	[0] = {
		.start = GPF3_CON,
		.end = GPF3_CON+GPF3_SIZE-1,
		.flags = IORESOURCE_MEM,
	},
	[1] = {
		.start = GPX1_CON,
		.end = GPX1_CON+GPX1_SIZE-1,
		.flags = IORESOURCE_MEM,
	},
	//中断资源,通过中断号去描述
	[2] = {
		.start = 67,//自定义的中断号
		.end = 67,
		.flags = IORESOURCE_IRQ,
	},
};

struct platform_device led_pdev = {
	.name = "exynos4412_led",
	.id= -1,
	.num_resources = ARRAY_SIZE(led_res),
	.resource = led_res,
};


static int __init plat_led_dev_init(void)
{
	return platform_device_register(&led_pdev);
}

static void __exit plat_led_dev_exit(void)
{
	platform_device_unregister(&led_pdev);
}

module_init(plat_led_dev_init);
module_exit(plat_led_dev_exit);
MODULE_LICENSE("GPL");

再看看LED平台驱动程序plat_led_pdrv.c的代码:

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/fs.h>
#include <linux/slab.h>

//封装设备信息
struct led_dev{
	int dev_major;
	struct class * cls;
	struct device *dev;
	struct resource * res;
	void *reg_base;
};
//定义设备信息
struct led_dev *samsung_led;

ssize_t led_pdrv_write(struct file *filp, const char __user *buf, size_t count, loff_t *fops)
{
	int ret;
	int value;
	
	ret = copy_from_user(&value, buf, count);
	if(ret){
		printk("copy_from_user error\n");
		return -EFAULT;
	}
	if(value){
		//数据寄存器置1
		writel(readl(samsung_led->reg_base+4) | (0x3<<4), samsung_led->reg_base+4);
	}else{
		writel(readl(samsung_led->reg_base+4) & ~(0x3<<4), samsung_led->reg_base+4);
	}
	
	return count;
}

int led_pdrv_open(struct inode *inode, struct file *filp)
{
	printk("---------%s---------\n",__FUNCTION__);

	return 0;
}

int led_pdrv_close(struct inode *inode, struct file *filp)
{
	printk("---------%s---------\n",__FUNCTION__);

	return 0;
}


const struct file_operations led_fops = {
	
.write = led_pdrv_write,
	.open = led_pdrv_open,
	.release = led_pdrv_close,
};
	
//实现初始化
int led_pdrv_probe(struct platform_device *pdev)
{
	printk("---------%s---------\n",__FUNCTION__);
	
	samsung_led = kzalloc(sizeof(struct led_dev),GFP_KERNEL);
	if(samsung_led == NULL){
		printk("kzalloc error\n");
		return -ENOMEM;
	}
	samsung_led->dev_major = register_chrdev(0,"led_drv", &led_fops);

	samsung_led->cls = class_create(THIS_MODULE,"led_cls");
	samsung_led->dev = device_create(samsung_led->cls, NULL, MKDEV(samsung_led->dev_major, 0), NULL,"led0");
	//获取资源
	samsung_led->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	//地址映射
	samsung_led->reg_base = ioremap(samsung_led->res->start, resource_size(samsung_led->res));

	//设置寄存器状态，这里时输出状态

	writel((readl(samsung_led->reg_base) & ~(0xff<<16))| (0x11<<16), samsung_led->reg_base);

	return 0;
}

int led_pdrv_remove(struct platform_device *pdev)
{
	iounmap(samsung_led->reg_base);
	device_destroy(samsung_led->cls, MKDEV(samsung_led->dev_major, 0));
	class_destroy(samsung_led->cls);
	unregister_chrdev(samsung_led->dev_major, "led_drv");	
	kfree(samsung_led);
	return 0;
}
//用于匹配
const struct platform_device_id led_id_table[] = {
	{"exynos4412_led",0x4444},
	{"s5pv210_led",0x3333},
	{"e3c6410_led",0x2222},
};

struct platform_driver led_pdrv = {
	.probe = led_pdrv_probe,
	.remove = led_pdrv_remove,
	.driver = {
		.name = "samsung_led_drv",//可以用于做匹配，也可以不用于做匹配
	},
	.id_table = led_id_table,
};

static int __init plat_led_drv_init(void)
{
	return platform_driver_register(&led_pdrv);
}

static void __exit plat_led_drv_exit(void)
{
	platform_driver_unregister(&led_pdrv);
}

module_init(plat_led_drv_init);
module_exit(plat_led_drv_exit);
MODULE_LICENSE("GPL");

接着看服务器led_server.c的代码：

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h>          
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/stat.h>
#include <fcntl.h>

#define SERVER_PORT 5001

int main(int argc,char **argv)
{
	int fd;
	int newfd;
	int len;
	int flag = 1;
	//设备节点的pfd
	int pfd;
	int value;
	struct sockaddr_in ipv4addr;
	struct sockaddr_in clientaddr;
	char ipaddr[16];

	fd = socket(AF_INET, SOCK_STREAM, 0);
	if(fd == -1){
		printf("server socket error\n");
		exit(1);
	}

	bzero(&ipv4addr,sizeof(ipv4addr));
	ipv4addr.sin_family = AF_INET;
	ipv4addr.sin_port = htons(SERVER_PORT);	
	ipv4addr.sin_addr.s_addr = htonl(INADDR_ANY);	
	if(bind(fd, (struct sockaddr*)&ipv4addr,sizeof(ipv4addr)) < 0){
		perror("bind");
		exit(1);
	}

	if(listen(fd,5) < 0){
		perror("listen");
		exit(1);
	}
	printf("server starting...\n");
	//地址复用
	if(setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&flag,sizeof(int))==-1)
	{
    	perror("setsockopt"); 
      	exit(1); 
	}
	
	len = sizeof(clientaddr);
	newfd = accept(fd, (struct sockaddr*)&clientaddr,&len);
	if(newfd == -1)
	{
		perror("accept");
		exit(1);
	}
	//打印客户端的ip和port
	if(!inet_ntop(AF_INET,(void*)&clientaddr.sin_addr.s_addr,ipaddr,sizeof(clientaddr))){
		perror("inet_ntop");
		exit(1);
	}
	printf("client ip:%s,port:%d is connected\n",ipaddr,ntohs(clientaddr.sin_port));

	pfd = open("/dev/led0",O_RDWR);
	if(pfd < 0){
		perror("open");
		exit(1);
	}

	while(1){
		//读取客户端通过socket发来的数据
		read(newfd,&value,4);
		if(value == 1 || value ==0)
			//间接控制设备
			write(pfd,&value,4);
		else{
			printf("client quiting...\n");
			break;
		}
	}

	close(newfd);
	close(fd);
	close(pfd);

	return 0;
}

最后看客户端led_client.c的代码:

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h>          
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/stat.h>
#include <fcntl.h>

#define SERVER_PORT 5001
//开发板ip地址
#define SERVER_IP "192.168.1.100"

int main(int argc,char **argv)
{
	int fd;
	int value;

	struct sockaddr_in ipv4addr;

	fd = socket(AF_INET, SOCK_STREAM, 0);
	if(fd == -1){
		printf("client socket error\n");
		exit(1);
	}

	bzero(&ipv4addr,sizeof(ipv4addr));
	ipv4addr.sin_family = AF_INET;
	ipv4addr.sin_port = htons(SERVER_PORT);
	if(inet_pton(AF_INET,SERVER_IP,(void *)&ipv4addr.sin_addr.s_addr) != 1){
		perror("client inet_pton");
		exit(1);
	}

	printf("client starting...\n");
	
 	if(connect(fd,(struct sockaddr *)&ipv4addr,sizeof(ipv4addr)) < 0){
		perror("connect");
		exit(1);
	}

	while(1){
		//1代表点亮led，0代表熄灭led，其他数字代表客户端退出程序
		printf("please select to led on/off(1:on/0:off/other:quit)");
		scanf("%d",&value);
		if(value == 1 || value == 0)
			write(fd,&value,4);
		else{
			write(fd,&value,4);
			printf("client quiting...\n");
			break;
		}
		//吸收垃圾字符
		getchar();
	}

	close(fd);

	return 0;
}

加载驱动并在开发板上运行服务器程序：

这里我直接在ubuntu上运行客户端，此时服务器已经连接上客户端，ubuntu上运行客户端如下：

我们在客户端上输入1，代表点亮led，输入0代表熄灭led，其他字符代表客户端退出。这里我们仅操作led4和led5

看看开发板的led情况，输入1时：

输入0时：