实验要求

 驱动代码

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/mod_devicetable.h>
#include <linux/of_gpio.h>
#include <linux/unistd.h>
#include <linux/interrupt.h>
#include <linux/of_irq.h>
#include <linux/of.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/string.h>
int i;
struct resource *res;
struct device_node *dnode;
unsigned int irqno[3];
unsigned int irqflag;
struct gpio_desc *gpiono[3];
unsigned char number;
struct cdev *cdev;
char kbuf[128] = {0};
unsigned int major = 0;
unsigned int minor = 0;
dev_t devno;
module_param(major, uint, 0664); // 方便在命令行传递major的值
struct class *cls;
struct device *dev;
unsigned int condition = 0;
// 定义一个等待队列头
wait_queue_head_t wq_head;
// 定义中断处理函数
irqreturn_t key_handler(int irq, void *dev)
{
    int which = (int)dev;
    if(number==0)
    {
        number=1;
        kbuf[0]='1';
    }else
    {
        number=0;
        kbuf[0]='0';
    }
    switch (which)
    {
    case 0:
        gpiod_set_value(gpiono[0], number);       
        break;
    case 1:
        gpiod_set_value(gpiono[1], number);
        break;
    case 2:
        gpiod_set_value(gpiono[2], number);
        break;
    }
     condition = 1; // 表示硬件数据就绪
      wake_up_interruptible(&wq_head);
    return IRQ_HANDLED;
}
// 封装probe函数
int pdrv_probe(struct platform_device *pdev)
{

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (res == NULL)
    {
        printk("获取men资源失败\n");
        return -ENXIO;
    }
    printk("mem资源%x\n", res->start);
    for (i = 0; i < 3; i++)
    {
        irqno[0] = platform_get_irq(pdev, 0);
    }
    if (irqno[0] < 0)
    {
        printk("获取中断类型资源失败\n");
        return -ENXIO;
    }
    printk("irq资源%d\n", irqno[0]);
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    // 设备树匹配成功后，设备树节点指针可以通过pdev->dev.of_node获取
    // 基于设备树节点信息获取gpio_desc对象指针
    gpiono[0] = gpiod_get_from_of_node(pdev->dev.of_node, "led1-gpio", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono))
    {
        printk("解析GPIO管脚信息失败\n");
        return -ENXIO;
    }
    gpiono[1] = gpiod_get_from_of_node(pdev->dev.of_node, "led2-gpio", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono))
    {
        printk("解析GPIO管脚信息失败\n");
        return -ENXIO;
    }
    gpiono[2] = gpiod_get_from_of_node(pdev->dev.of_node, "led3-gpio", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono))
    {
        printk("解析GPIO管脚信息失败\n");
        return -ENXIO;
    }

    return 0;
}
// 封装操作方法
int mycdev_open(struct inode *inode, struct file *file)
{

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

    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{
    int ret;
    // 判断IO方式
    if (file->f_flags & O_NONBLOCK) // 非阻塞
    {
    }
    else // 阻塞
    {
        wait_event_interruptible(wq_head, condition); // 先检查condition再将进程休眠
    }
    ret = copy_to_user(ubuf, kbuf, size);
    if (ret)
    {
        printk("copy_to_user err\n");
        return -EIO;
    }
    condition = 0; // 下一次硬件数据没有就绪
    return 0;
}
// 定义操作方法结构体变量并赋值
struct file_operations fops = {

    .open = mycdev_open,
    .release = mycdev_close,
    .read = mycdev_read,
};
// 封装remvoe函数
int pdrv_remove(struct platform_device *pdev)
{
    // 释放GPIO信息

    for (i = 0; i < 3; i++)
    {
        gpiod_put(gpiono[i]);
    }
    int i;
    for (i = 0; i < 3; i++)
    {
        free_irq(irqno[i], (void *)i);
    }
    // 销毁设备文件
    // 注销驱动
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
// 构建设备树匹配表
struct of_device_id oftable[] = {
    {.compatible = "hqyj,myplatform"},
    {},
};
// 定义驱动信息对象并初始化
struct platform_driver pdrv = {
    .probe = pdrv_probe,
    .remove = pdrv_remove,
    .driver = {
        .name = "ccccc",
        .of_match_table = oftable, // 用来设备树匹配
    },
};

static int __init mycdev_init(void)
{
    // 注册
    platform_driver_register(&pdrv);
    // 解析按键的设备树节点
    dnode = of_find_compatible_node(NULL, NULL, "hqyj,myirq");
    if (dnode == NULL)
    {
        printk("解析设备树节点失败\n");
        return -ENXIO;
    }
    printk("解析设备树节点成功\n");
    // 解析按键的软中断号
    int i;
    for (i = 0; i < 3; i++)
    {
        irqno[i] = irq_of_parse_and_map(dnode, i);
        if (!irqno[i])
        {
            printk("解析按键1软中断号失败\n");
            return -ENXIO;
        }
        printk("解析按键软中断号成功%d\n", irqno[i]);
        // 注册 按键中断
        int ret = request_irq(irqno[i], key_handler, IRQF_TRIGGER_FALLING, "key_int", (void *)i);
        if (ret < 0)
        {
            printk("注册按键中断失败\n");
            return ret;
        }
    }
    printk("注册按键中断成功\n");

    init_waitqueue_head(&wq_head);
    int ret;
    // 为字符设备驱动对象申请空间
    cdev = cdev_alloc();
    if (cdev == NULL)
    {
        printk("字符设备驱动对象申请空间失败\n");
        ret = -EFAULT;
        goto out1;
    }
    printk("申请对象空间成功\n");
    // 初始化字符设备驱动对象
    cdev_init(cdev, &fops);
    // 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\n");
    // 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

    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:
    cdev_del(cdev);
out3:
    unregister_chrdev_region(MKDEV(major, minor), 3);
out2:
    kfree(cdev);
out1:
    return ret;
    return 0;
}
static void __exit mycdev_exit(void)
{
    // 注册
    platform_driver_unregister(&pdrv);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

 应用程序代码

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>


int main(int argc, char const *argv[])
{
    
     char buf[128] = {0};
    int fd = open("/dev/myled0", O_RDWR);
    if (fd < 0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    while (1)
    {
        read(fd,buf,sizeof(buf));
        printf("%s\n",buf);
    }


    return 0;
}

实验现象