通过platform实现

drv.c

#include 
#include 
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#include 
 
//获取资源结构体
struct resource *res;
//中断号
unsigned int irqno;
//gpio信息结构体
struct gpio_desc *gpiono;
//字符设备驱动对象空间首地址
struct cdev *cdev;
char kbuf[128] = {0};
//主设备号
unsigned int major = 0;
//次设备号
unsigned int minor = 0;
//设备号
dev_t devno;
module_param(major,uint,0664);  //方便在命令行传递major的值
//用于保存目录信息
struct class *cls;
//用于保存设备节点信息
struct device *dev;
int number = 0;
unsigned int condition = 0;
wait_queue_head_t wq_head;
 
//中断处理函数
irqreturn_t key_handler(int irq,void *dev)
{
    gpiod_set_value(gpiono,!(gpiod_get_value(gpiono)));
    number = !number;
    condition = 1;
    wake_up_interruptible(&wq_head);
    return IRQ_HANDLED;
}
 
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)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    int ret;
    //向用户空间读取拷贝
    if(size>sizeof(number))//用户空间期待读取的大小内核满足不了，那就给内核支持的最大大小
        size=sizeof(number);
    //切换进程为休眠态
    wait_event_interruptible(wq_head,condition);
    ret=copy_to_user(ubuf,&number,size);
    if(ret)//拷贝失败
    {
        printk("copy_to_user filed\n");
        return ret;
    }
    condition = 0;
    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变量并赋值
struct file_operations fops={
 
    .open=mycdev_open,
    .read=mycdev_read,
    .release=mycdev_close,
};
//封装probe函数
int pdrv_probe(struct platform_device *pdev)
{
    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, "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, minor, 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, "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");
    // 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, "myplatform%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");
 
    //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;
    }
    //获取中断类型的资源
    irqno = platform_get_irq(pdev,0);
    if(irqno < 0)
    {
        printk("获取中断类型资源失败\n");
        return -ENXIO;
    }
    //注册中断
    int ret1 = request_irq(irqno,key_handler,IRQF_TRIGGER_FALLING,"key_int",NULL);
    if(ret1<0)
    {
        printk("注册按键1中断失败\n");
        return ret1;
    }
    printk("注册按键1中断成功\n");
    printk("mem资源%llx\n",res->start);
    printk("irq资源%d\n",irqno);
    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 = 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;
        }
    printk("解析GPIO管脚信息成功\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;
}
//封装remove函数
int pdrv_remove(struct platform_device *pdev)
{
    //关灯
    gpiod_set_value(gpiono,0);
    //释放GPIO信息
    gpiod_put(gpiono);
    //注销中断
    free_irq(irqno,NULL);
    // 释放节点信息
    int i;
    for (i = 0; i < 3; i++)
    {
        device_destroy(cls, MKDEV(major, i));
    }
    // 销毁目录
    class_destroy(cls);
    // 注销驱动对象
    cdev_del(cdev);
    // 释放设备号
    unregister_chrdev_region(MKDEV(major, minor), 3);
    // 释放对象空间
    kfree(cdev);
    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"},
    { /* 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 = "bbbbb",
        .of_match_table=oftable,//用于设备树匹配 
    },
};
 
//一键注册宏
module_platform_driver(pdrv);
 
MODULE_LICENSE("GPL");

app.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main(int argc, const char *argv[])
{
	int buf[128] = {0};
	int fd;
	    // 打开设备节点
    fd = open("/dev/myplatform0", O_RDWR);
    if (fd < 0) 
	{
        printf("设备文件打开失败\n");
		exit(-1);
    }
	while(1)
	{
		read(fd,buf,sizeof(buf));
		printf("number=%d\n",buf);
	}

    close(fd);
	return 0;
}