练习

基于platform实现

在根节点下，增加设备树

	myplatform {
		compatible="hqyj,myplatform";
		interrupts-extended=<&gpiof 9 0>, <&gpiof 7 0>, <&gpiof 8 0>;
		led1-gpio=<&gpioe 10 0>;
		reg=<0x12345678 59>;
	};

驱动代码

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/poll.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include <linux/timer.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/mod_devicetable.h>

// 中断
struct device_node *dnode;
unsigned int key_irqno;
struct gpio_desc *gpiono;
// 字符设备驱动
int major;
// 自动创建设备节点
struct class *cls;
struct device *dev;

struct resource *res;

int number = 0;
unsigned int condition = 0;
wait_queue_head_t wq_head; // 等待队列头

// 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;
}
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{
    int ret;
    char kbuf[128] = {0};
    sprintf(kbuf, "number = %d", number);
    if (file->f_flags & O_NONBLOCK)
    {
        // 非阻塞
        return -EINVAL;
    }
    else
    {
        // 阻塞
        ret = wait_event_interruptible(wq_head, condition);
        if (ret < 0)
        {
            printk("receive signal.... \n");
            return ret;
        }
    }
    // 拷贝数据到用户空间
    ret = copy_to_user(ubuf, kbuf, size);
    if (ret)
    {
        printk("copy_to_user err \n");
        return -EIO;
    }

    // condition清零
    condition = 0;
    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;
}

// 定义操作方法结构体遍历并且初始化
struct file_operations fops = {
    .open = mycdev_open,
    .read = mycdev_read,
    .write = mycdev_write,
    .release = mycdev_close,
};

irqreturn_t key_handler(int irq, void *dev)
{
    if (number == 0)
    {
        number = 1;
    }
    else
    {
        number = 0;
    }
    gpiod_set_value(gpiono, number);
    condition = 1;
    wake_up_interruptible(&wq_head);

    return IRQ_HANDLED;
}

// 封装probe函数和remove函数
int pdrv_probe(struct platform_device *pdev)
{
    printk("pdrv_probe --------------------------- \n");
    int ret;

    /**
     * 1. 注册设备驱动
     */
    major = register_chrdev(0, "mychrdev", &fops);
    if (major < 0)
    {
        printk("字符设备驱动注册失败 \n");
        return major;
    }
    printk("字符设备驱动注册成功\n");

    /**
     * 2. 自动创建设备节点
     */
    // 向上提交目录信息
    cls = class_create(THIS_MODULE, "mycdev");
    if (IS_ERR(cls))
    {
        printk("向上提交目录信息失败\n");
        return -PTR_ERR(cls);
    }
    printk("向上提交目录信息成功\n");

    // 向上提交设备信息
    dev = device_create(cls, NULL, MKDEV(major, 0), NULL, "mycdev0");
    if (IS_ERR(dev))
    {
        printk("向上提交设备节点失败\n");
        return -PTR_ERR(cls);
    }

    // 3. 初始化等待队列头
    init_waitqueue_head(&wq_head);

    // 获取MEM类型的资源
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (res == NULL)
    {
        printk("获取MEM类型资源失败\n");
        return -ENXIO;
    }

    /**
     * 中断
     */
    // 获取软中断号
    key_irqno = platform_get_irq(pdev, 0);
    if (key_irqno < 0) {
        printk("获取软中断号失败 \n");
        return -ENXIO;
    }
    printk("获取软中断号成功 \n");

    // 注册中断
    ret = request_irq(key_irqno, key_handler, IRQF_TRIGGER_FALLING, "key1", NULL);
    if (ret < 0)
    {
        printk("注册中断失败\n");
        return -1;
    }
    printk("注册中断成功\n");

    /**
     * LED灯
     */
    // 获取gpio编号
    gpiono=gpiod_get_from_of_node(pdev->dev.of_node,"led1-gpio",0,GPIOD_OUT_HIGH,NULL);
    if(IS_ERR(gpiono))
    {
        printk("解析gpio信息失败\n");
        return -PTR_ERR(gpiono);
    }
    printk("解析gpio编号成功\n");

    return 0;
}
int pdrv_remove(struct platform_device *pdev)
{
    free_irq(key_irqno, NULL);
    gpiod_set_value(gpiono, 0);
    gpiod_put(gpiono);

    device_destroy(cls, MKDEV(major, 0));
    class_destroy(cls);
    unregister_chrdev(major, "mychrdev");
    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",
    },
    {},
};

// 分配驱动信息对象并初始化
struct platform_driver pdrv = {
    .probe = pdrv_probe,
    .remove = pdrv_remove,
    .driver = {
        .name="aaaaa",
        .of_match_table = oftable,
    },
};

module_platform_driver(pdrv);

MODULE_LICENSE("GPL");

应用层代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sys/wait.h>
#include <pthread.h>
#include <signal.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <sys/epoll.h>

int main(int argc, const char* argv[])
{
    int fd;
	char buf[128];

    if ((fd = open("/dev/mycdev0", O_RDWR)) == -1) {
        perror("open error");
        exit(EXIT_FAILURE);
    }

    while (1) {
		bzero(buf, sizeof(buf));
        read(fd, buf, sizeof(buf));
        printf("status = %s\n", buf);
    }
    close(fd);
    return 0;
}

效果展示