嵌入式:驱动开发 Day7

作业:基于GPIO子系统,编写LED的驱动程序和应用程序

驱动程序:myled.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "head.h"

struct cdev *cdev;
unsigned int major = 0;
unsigned int minor = 0;
dev_t devno;
module_param(major, uint, 0664); //方便命令行传递major的值
struct class *cls;
struct device *dev;
struct device_node *dnode;
struct gpio_desc *gpiono[3];

//封装操作方法
int mycdev_open(struct inode *inode, struct file *file)
{
    int min = MINOR(inode->i_rdev); //根据打开的文件对应的设备号获取次设备号
    file->private_data = (void *)min;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}

long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    int min = (int)file->private_data; //传递次设备号

    //设备文件和设备的绑定,根据次设备号决定打开的设备文件,根据打开的设备文件,控制相应的设备
    switch (min)
    {
    case 0: //控制LED1
        switch (cmd)
        {
        case LED_ON: //开灯
            gpiod_set_value(gpiono[0], 1);
            break;
        case LED_OFF: //关灯
            gpiod_set_value(gpiono[0], 0);
            break;
        }
        break;
    case 1: //控制LED2
        switch (cmd)
        {
        case LED_ON: //开灯
            gpiod_set_value(gpiono[1], 1);
            break;
        case LED_OFF: //关灯
            gpiod_set_value(gpiono[1], 0);
            break;
        }
        break;
    case 2: //控制LED3
        switch (cmd)
        {
        case LED_ON: //开灯
            gpiod_set_value(gpiono[2], 1);
            break;
        case LED_OFF: //关灯
            gpiod_set_value(gpiono[2], 0);
            break;
        }
        break;
    }
    return 0;
}
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{

    return 0;
}

ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{

    return 0;
}

int mycdev_close(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}

//定义一个操作方法结构体对象并初始化
struct file_operations fops = {
    .open = mycdev_open,
    .unlocked_ioctl = mycdev_ioctl,
    .read = mycdev_read,
    .write = mycdev_write,
    .release = mycdev_close,
};

static int __init mycdev_init(void)
{
    //解析LED的设备树节点
    dnode = of_find_node_by_path("/myled");
    if (dnode == NULL)
    {
        printk("解析设备树节点失败\n");
        return -ENXIO;
    }

    //申请gpio对象
    int j;
    char nodename[20];
    for (j = 0; j < 3; j++)
    {
        sprintf(nodename, "led%d-gpio", j + 1);
        gpiono[j] = gpiod_get_from_of_node(dnode, nodename, 0, GPIOD_OUT_LOW, NULL);
        if (IS_ERR(gpiono[j]))
        {
            printk("申请gpiono%d失败\n", j);
            goto out0;
        }
    }

    int ret;
    //1.为字符设备驱动对象申请空间
    cdev = cdev_alloc();
    if (cdev == NULL)
    {
        printk("申请字符设备驱动对象空间失败\n");
        ret = -EFAULT;
        goto out1;
    }
    printk("申请字符设备驱动对象空间成功\n");

    //2.初始化字符设备驱动对象
    cdev_init(cdev, &fops);
    printk("初始化字符设备驱动对象成功\n");

    //3.申请设备号
    if (major > 0) //静态指定设备号
    {
        ret = register_chrdev_region(MKDEV(major, minor), 3, "myled");
        if (ret)
        {
            printk("静态申请设备号失败\n");
            goto out2;
        }
    }
    else if (major == 0)
    { //动态申请设备号
        ret = alloc_chrdev_region(&devno, minor, 3, "myled");
        if (ret)
        {
            printk("动态申请设备号失败\n");
            goto out2;
        }
        major = MAJOR(devno); //获取主设备号
        minor = MINOR(devno); //获取次设备号
    }
    printk("申请设备号成功 major= %d\n", major);

    //4.注册字符设备驱动对象
    ret = cdev_add(cdev, MKDEV(major, minor), 3);
    if (ret)
    {
        printk("注册字符设备驱动对象失败\n");
        goto out3;
    }
    printk("注册字符设备驱动对象成功\n");

    //向上提交目录信息
    cls = class_create(THIS_MODULE, "myled");
    if (IS_ERR(cls))
    {
        printk("向上提交目录失败\n");
        ret = -PTR_ERR(cls);
        goto out4;
    }
    printk("向上提交目录成功\n");

    //向上提交设备节点信息
    int i;
    for (i = 0; i < 3; i++)
    {
        dev = device_create(cls, NULL, MKDEV(major, i), NULL, "myled%d", i);
        if (IS_ERR(dev))
        {
            printk("向上提交设备节点信息失败\n");
            ret = -PTR_ERR(dev);
            goto out5;
        }
    }
    printk("向上提交设备信息成功\n");
    return 0;

out5:
    //释放前一次提交成功的设备信息
    for (--i; i >= 0; i--)
    {
        device_destroy(cls, MKDEV(major, i));
    }
    class_destroy(cls); //释放目录
out4:
    //注销字符设备驱动对象
    cdev_del(cdev);
out3:
    //释放设备号
    unregister_chrdev_region(MKDEV(major, minor), 3);
out2:
    //释放设备驱动对象空间
    kfree(cdev);
out1:
    return ret;
out0:
    //释放前一次申请成功gpiono编号
    for (--j; j >= 0; j--)
    {
        gpiod_put(gpiono[j]);
    }
    return -1;
}

static void __exit mycdev_exit(void)
{
    int i;
    //释放设备节点信息
    for (i = 0; i < 3; i++)
    {
        device_destroy(cls, MKDEV(major, i));
    }
    //销毁目录
    class_destroy(cls);
    //注销字符设备驱动对象
    cdev_del(cdev);
    //释放设备号
    unregister_chrdev_region(MKDEV(major, minor), 3);
    //释放设备驱动对象空间
    kfree(cdev);
    //释放gpiono编号
    for (i = 0; i < 3; i++)
    {
        gpiod_put(gpiono[i]);
    }
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用程序:test.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "head.h"

int main()
{
	int a, b;
	char buf[128] = "";
	int fd1, fd2, fd3;
	while (1)
	{
		printf("请输入要控制的灯:0(LED1) 1(LED2) 2(LED3) >");
		scanf("%d", &a);
		switch (a)
		{
		case 0:
			fd1 = open("/dev/myled0", O_RDWR);
			if (fd1 < 0)
			{
				printf("设备文件打开失败\n");
				exit(-1);
			}
			printf("请输入对LED的控制命令:0(关灯) 1(开灯)  >");
			scanf("%d", &b);
			switch (b)
			{
			case 0:
				ioctl(fd1, LED_OFF); //关灯
				close(fd1);
				break;
			case 1:
				ioctl(fd1, LED_ON); //开灯
				close(fd1);
				break;
			}
			break;

		case 1:
			fd2 = open("/dev/myled1", O_RDWR);
			if (fd2 < 0)
			{
				printf("设备文件打开失败\n");
				exit(-1);
			}
			printf("请输入对LED的控制命令:0(关灯) 1(开灯)  >");
			scanf("%d", &b);
			switch (b)
			{
			case 0:
				ioctl(fd2, LED_OFF); //关灯
				close(fd2);
				break;
			case 1:
				ioctl(fd2, LED_ON); //开灯
				close(fd2);
				break;
			}
			break;

		case 2:
			fd3 = open("/dev/myled2", O_RDWR);
			if (fd3 < 0)
			{
				printf("设备文件打开失败\n");
				exit(-1);
			}
			printf("请输入对LED的控制命令:0(关灯) 1(开灯)  >");
			scanf("%d", &b);
			switch (b)
			{
			case 0:
				ioctl(fd3, LED_OFF); //关灯
				close(fd3);
				break;
			case 1:
				ioctl(fd3, LED_ON); //开灯
				close(fd3);
				break;
			}
			break;
		}
	}

	close(fd1);
	close(fd2);
	close(fd3);

	return 0;
}

头文件:head.h

#ifndef __HEAD_H__
#define __HEAD_H__

//构建LED开关的功能码,不添加ioctl第三个参数
#define LED_ON _IO('l', 1)
#define LED_OFF _IO('l', 0)

#endif

现象:

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