基于platform实现

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 

test.c

#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>
#include "head.h"


int main(int argc, char const *argv[])
{
    int a;
    char buf[128] = {0};
    int fd = open("/dev/myplatform0", O_RDWR);
    if (fd < 0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    while (1)
    {
        read(fd, buf, 1);  
        switch (buf[0])
        {
        case 1:
            ioctl(fd, LED_ON); // 开灯
            break;
        case 0:
            ioctl(fd, LED_OFF); // 关灯
        }
    }

    close(fd);

    return 0;
}

pdr.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/platform_device.h>
#include <linux/mod_devicetable.h>
#include <linux/of_gpio.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include "head.h"

char number = 0;

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 irqno[3];       // 软中断号
struct gpio_desc *gpiono[3]; // gpio对象

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;
    switch (which)
    {
    case 0:
        printk("KEY1\n");
        number ^= 1;
        condition = 1; // 表示硬件数据就绪
        wake_up_interruptible(&wq_head);
        break;
    case 1:
        
        break;
    case 2:
        
        break;
    default:
        break;
    }
    return IRQ_HANDLED;
}

// 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;
}

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, &number, 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;
}

long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{

    int min = (int)file->private_data;
    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;
}

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

struct file_operations fops = {
    .open = mycdev_open,
    .read = mycdev_read,
    .unlocked_ioctl = mycdev_ioctl,
    .release = mycdev_close,
};

// 封装probe函数
int pdrv_probe(struct platform_device *pdev)
{
    int ret;
    // 初始化等待队列
    init_waitqueue_head(&wq_head);
    // 字符设备注册
    // 1.申请驱动对象
    cdev = cdev_alloc();
    if (cdev == NULL)
    {
        printk("申请对象空间失败！\n");
        ret = -EFAULT;
        goto out1;
    }
    printk("申请对象成功！\n");
    // 2.初始化驱动对象
    cdev_init(cdev, &fops);
    printk("初始化对象成功！\n");

    // 3.申请主设备号和一定数量设备资源
    if (major > 0) // 静态指定设备号
    {
        ret = register_chrdev_region(MKDEV(major, minor), 3, "myplatform");
        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, 0, 3, "myplatform");
        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); // 获取此设备号
    }
    printk("申请设备号成功！\n");

    // 4.根据申请的设备号和驱动对象注册驱动
    ret = cdev_add(cdev, MKDEV(major, minor), 3);
    if (ret)
    {
        printk("驱动注册失败！\n");
        goto out3;
    }
    printk("注册驱动成功！\n");

    // 5.向上提交目录信息
    cls = class_create(THIS_MODULE, "myplatform");
    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");

    // 6.向上提交设备信息文件
    int i;
    for (i = 0; i < 3; i++)
    {
        dev = device_create(cls, NULL, MKDEV(major, i), NULL, "myplatform%d", i);
        if (IS_ERR(dev))
        {
            printk("向上提交设备信息失败！\n");
            ret = -PTR_ERR(dev);
            goto out5;
        }
    }
    printk("向上提交设备信息文件成功！\n");

    // 获取中断类型的资源

    for (i = 0; i < 3; i++)
    {
        // 根据节点解析软中断号
        irqno[i] = platform_get_irq(pdev, i);
        if (!irqno[i])
        {
            printk("获取软中断号失败！\n");
            return -ENXIO;
        }
        printk("获取软中断号成功！%d\n", irqno[i]);

        // 注册软中断号
        ret = request_irq(irqno[i], key_handler, IRQF_TRIGGER_FALLING, "key_int", (void *)i);
        if (ret < 0)
        {
            printk("注册软中断号失败！\n");
            return ret;
        }
        printk("注册软中断号成功！\n");

        gpiono[i] = gpiod_get_from_of_node(pdev->dev.of_node, "led-gpios", i, GPIOD_OUT_LOW, NULL);
        if (IS_ERR(gpiono[i]))
        {
            printk("解析GPIO管脚信息失败\n");
            return -ENXIO;
        }
        printk("解析GPIO管脚信息成功\n");
    }
    return 0;
out5:
    for (--i; i > -1; i--)
    {
        device_destroy(cls, MKDEV(major, i));
    }
    class_destroy(cls);
out4:
    cdev_del(cdev);
out3:
    unregister_chrdev_region(MKDEV(major, minor), 3);
out2:
    kfree(cdev);
out1:
    return ret;
}
// 封装remove函数
int pdrv_remove(struct platform_device *pdev)
{
    // 销毁设备信息文件
    int i;
    for (i = 0; i < 3; i++)
    {
        device_destroy(cls, MKDEV(major, i));
    }
    // 销毁设备类目录
    class_destroy(cls);
    // 注销驱动
    cdev_del(cdev);
    // 注销设备号
    unregister_chrdev_region(MKDEV(major, minor), 3);
    // 释放cdev对象
    kfree(cdev);

    for (i = 0; i < 3; i++)
    {
        // 注销中断
        free_irq(irqno[i], (void *)i);

        // 熄灭led灯
        gpiod_set_value(gpiono[i], 0);

        // 释放gpio对象
        gpiod_put(gpiono[i]);
    }
    printk("注销中断成功！\n");
    return 0;
}

// 构建设备树匹配表
struct of_device_id oftable[] = {
    {.compatible = "hqyj,myplatform"},
    {/* end node */}, // 防止数组越界
};

// 定义驱动信息对象并初始化
struct platform_driver pdrv = {
    .probe = pdrv_probe,
    .remove = pdrv_remove,
    .driver = {
        .name = "aaa",
        .of_match_table = oftable, // 用于设备树匹配
    },
};

// 一键注册宏
module_platform_driver(pdrv);
MODULE_LICENSE("GPL");