华清远见（上海中心）

日期：11月24日             

一、题目

1. .应用层写程序控制6盏灯的亮灭，要求使用GPIO子系统

代码实现：

#include 
#include 
#include 
#include 
#include 
#include 
#include "device.h"
int main(int argc,const char * argv[])
{
	int i;
	int fd[6]={0};
	char *p[6]={"/dev/myled0","/dev/myled1","/dev/myled2","/dev/myled3","/dev/myled4","/dev/myled5"};
	for(i=0;i<6;i++)
	{
		fd[i] = open(p[i],O_RDWR);
		if(-1 == fd[i])
		{
			printf("open is error\n");
			return -1;
		}
	}
		while(1)
		{
			ioctl(fd[0],LED0_ON);
			sleep(1);
			ioctl(fd[0],LED0_OFF);
			ioctl(fd[1],LED3_ON);
			sleep(1);
			ioctl(fd[1],LED3_OFF);
			ioctl(fd[2],LED5_ON);
			sleep(1);
			ioctl(fd[2],LED5_OFF);
			ioctl(fd[3],LED4_ON);
			sleep(1);
			ioctl(fd[3],LED4_OFF);
			ioctl(fd[4],LED2_ON);
			sleep(1);
			ioctl(fd[4],LED2_OFF);
			ioctl(fd[5],LED1_ON);
			sleep(1);
			ioctl(fd[5],LED1_OFF);
		}
	return 0;
}

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "device.h"
#define CNAME "myleds"
struct device_node *node;
struct gpio_desc *gpio[6];
int ret,i;
struct cdev *cdev;
dev_t dev;
int minor=0;
int major;
int count=6;
struct device* device;
struct class* cls;
char *p[6]={"myled0","myled1","myled2","myled3","myled4","myled5"};
int myc_open(struct inode *node, struct file *file)
{
	return 0;
}
long myc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	if(cmd == LED0_ON)
	{
		gpiod_set_value(gpio[0],1);
	}else if(cmd == LED0_OFF)
	{
		gpiod_set_value(gpio[0],0);
	}
	if(cmd == LED1_ON)
	{
		gpiod_set_value(gpio[1],1);
	}else if(cmd == LED1_OFF)
	{
		gpiod_set_value(gpio[1],0);
	}
	if(cmd == LED2_ON)
	{
		gpiod_set_value(gpio[2],1);
	}else if(cmd == LED2_OFF)
	{
		gpiod_set_value(gpio[2],0);
	}
	if(cmd == LED3_ON)
	{
		gpiod_set_value(gpio[3],1);
	}else if(cmd == LED3_OFF)
	{
		gpiod_set_value(gpio[3],0);
	}
	if(cmd == LED4_ON)
	{
		gpiod_set_value(gpio[4],1);
	}else if(cmd == LED4_OFF)
	{
		gpiod_set_value(gpio[4],0);
	}
	if(cmd == LED5_ON)
	{
		gpiod_set_value(gpio[5],1);
	}else if(cmd == LED5_OFF)
	{
		gpiod_set_value(gpio[5],0);
	}
	return 0;
}
int myc_close(struct inode *node, struct file *file)
{
	return 0;
}
const struct file_operations fops = {
	.open = myc_open,
	.release = myc_close,
	.unlocked_ioctl = myc_ioctl,
};
static int __init mycdev_init(void)
{
	//分配字符设备驱动
	cdev = cdev_alloc();
	if(cdev == NULL)
	{
		printk("内存分配失败\n");
		goto ERR1;
	}
	printk("内存分配成功\n");
	//初始化设备驱动
	cdev_init(cdev,&fops);
	//动态申请设备号
	ret = alloc_chrdev_region(&dev,minor,count,CNAME);
	if(ret<0)
	{
		printk("动态申请设备号失败\n");
		goto ERR2;
	}
	printk("动态申请设备号成功\n");
	//注册字符设备驱动
	ret = cdev_add(cdev,dev,count);
	if(ret<0)
	{
		printk("注册字符设备驱动失败\n");
		goto ERR3;
	}
	printk("注册字符设备驱动成功\n");
	  //5.自动创建设备节点
	//向上层提交目录信息
	cls = class_create(THIS_MODULE,CNAME);
	if(IS_ERR(cls))
	{
		printk("class create is failed\n");
		ret = PTR_ERR(cls);
		goto ERR4;
	}
	//向上层提交设备节点
	//自动申请
	major = MAJOR(dev);
	for(i=0;i
	{
		device = device_create(cls,NULL,MKDEV(major,i),NULL,"myled%d",i);
		if(IS_ERR(device))
		{
			printk("device create is error\n");
			ret = PTR_ERR(device);
			goto ERR5;
		}
	}
	node = of_find_node_by_path("/myleds");
	if(node == NULL)
	{
		printk("通过路径解析设备树节点失败\n");
		return -EFAULT;
	}
	printk("成功解析到设备树节点\n");
	
	for(i=0;i<6;i++)
	{
		gpio[i] = gpiod_get_from_of_node(node,p[i],0,GPIOD_OUT_LOW,NULL);
		if(IS_ERR(gpio[i]))
		{
			printk("gpio编号获取失败\n");
			return PTR_ERR(gpio[i]);
		}
		printk("gipo[%d]编号获取成功\n",i);
	
		//设置引脚为输出模式
		ret = gpiod_direction_output(gpio[i],0);
		if(ret<0)
		{
			printk("输出模式设置成功\n");
			return ret;
		}
		//初始化
		gpiod_set_value(gpio[i],0);
	}
	return 0;
ERR5:
	for(--i;i>=0;i--)
		{
			device_destroy(cls,MKDEV(major,i));
		}
		class_destroy(cls);
ERR4:
	cdev_del(cdev);
ERR3:
	unregister_chrdev_region(dev,count);
ERR2:
	kfree(cdev);
ERR1:
	return -EIO;
}
static void __exit mycdev_exit(void)
{
	for(i=0;i<6;i++)
	{
		gpiod_set_value(gpio[i],0);
		//释放
		gpiod_put(gpio[i]);
	}
	for(i=0;i
	{
		device_destroy(cls,MKDEV(major,i));
	}
    //2.销毁目录信息
	class_destroy(cls);
    //3.驱动的注销
	cdev_del(cdev);
    //4.销毁设备号
	unregister_chrdev_region(dev,count);
    //5.释放cdev结构体
	kfree(cdev);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

 
#ifndef __DEVICE_H__
#define __DEVICE_H__
#define LED0_ON _IOW('a',1,int)
#define LED0_OFF _IOW('a',0,int)
#define LED1_ON _IOW('a',1,int)
#define LED1_OFF _IOW('a',0,int)
#define LED2_ON _IOW('a',1,int)
#define LED2_OFF _IOW('a',0,int)
#define LED3_ON _IOW('a',1,int)
#define LED3_OFF _IOW('a',0,int)
#define LED4_ON _IOW('a',1,int)
#define LED4_OFF _IOW('a',0,int)
#define LED5_ON _IOW('a',1,int)
#define LED5_OFF _IOW('a',0,int)
#endif

现象实现：