设备驱动号绑定文件描述符

最新推荐文章于 2025-11-30 14:17:11 发布

原创最新推荐文章于 2025-11-30 14:17:11 发布 · 243 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#linux

本文详细介绍了如何在Linux系统中使用C语言编写一个驱动程序，通过字符设备接口控制GPIO引脚驱动LED灯的开关。内容包括内存映射、设备驱动初始化、字符设备操作和模块加载/卸载过程。

K1.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include "head.h"

char kbuf[128] = {};
//定义三个指针指向映射后的虚拟内存
unsigned int *vir_rcc;
unsigned int *vir_moder_led1;
unsigned int *vir_odr_led1;
unsigned int *vir_moder_led2;
unsigned int *vir_odr_led2;
unsigned int *vir_moder_led3;
unsigned int *vir_odr_led3;

struct cdev *cdev;
unsigned int major=0;
unsigned int minor=0;
dev_t devno;
struct class *cls;
struct device *dev;

int mycdev_open(struct inode *inode, struct file *file)
{
    //获取打开的文件的次设备号
    int min = MINOR(inode->i_rdev);
    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)
{
    //获取打开文件的次设备号
    int min = (int)file->private_data;
    switch(min)
    {
        case 0:
            switch(cmd)
            {
                case LED_ON:
                    (*vir_odr_led1) |= (0x1 << 10);
                    break;
                case LED_OFF:
                    (*vir_odr_led1) &= (~(0x1 << 10));
                    break;
            }
            break;
        case 1:
             switch(cmd)
            {
                case LED_ON:
                    (*vir_odr_led2) |= (0x1 << 10);
                    break;
                case LED_OFF:
                    (*vir_odr_led2) &= (~(0x1 << 10));
                    break;
            }
            break;
        case 2:
              switch(cmd)
            {
                case LED_ON:
                    (*vir_odr_led3) |= (0x1 << 10);
                    break;
                case LED_OFF:
                    (*vir_odr_led3) &= (~(0x1 << 10));
                    break;
            }
            break;              
    }
    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;
}
//定义操作方法结构体变量并赋值
struct file_operations fops={
    .open=mycdev_open,
    .unlocked_ioctl=mycdev_ioctl,
    .release=mycdev_close,
};
int all_led_init(void)
{
    //进行寄存器的地址映射
    vir_rcc = ioremap(PHY_RCC,4);
    if(vir_rcc == NULL)
    {
        printk("物理内存映射filed! %d\n",__LINE__);
        return -EFAULT;
    }

    vir_moder_led1 = ioremap(PHY_LED1_MODER,sizeof(gpio_t));
    if(vir_moder_led1 == NULL)
    {
        printk("物理内存映射filed! %d\n",__LINE__);
        return -EFAULT;
    }
    vir_odr_led1 = ioremap(PHY_LED1_ODR,sizeof(gpio_t));
    if(vir_odr_led1 == NULL)
    {
        printk("物理内存映射filed! %d\n",__LINE__);
        return -EFAULT;
    }

    vir_moder_led2 = ioremap(PHY_LED2_MODER,sizeof(gpio_t));
    if(vir_moder_led2 == NULL)
    {
        printk("物理内存映射filed! %d\n",__LINE__);
        return -EFAULT;
    }
    vir_odr_led2 = ioremap(PHY_LED2_ODR,sizeof(gpio_t));
    if(vir_odr_led2 == NULL)
    {
        printk("物理内存映射filed! %d\n",__LINE__);
        return -EFAULT;
    }

    vir_moder_led3 = vir_moder_led1;
    if(vir_moder_led3 == NULL)
    {
        printk("物理内存映射filed! %d\n",__LINE__);
        return -EFAULT;
    }
    vir_odr_led3 = vir_odr_led1;
    if(vir_odr_led3 == NULL)
    {
        printk("物理内存映射filed! %d\n",__LINE__);
        return -EFAULT;
    }

    printk("物理内存映射成功!\n");

    //LED1寄存器初始化
    (*vir_rcc) |= (0x3 << 4);         //GPIOE控制器时钟使能

    (*vir_moder_led1) &= (~(0x3 << 20));   //MODER[21:20] => 00
    (*vir_moder_led1) |= (0x1 << 20);      //MODER[21:20] => 01
    (*vir_odr_led1) &= (~(0x1 << 10));     //默认为关灯

    (*vir_moder_led2) &= (~(0x3 << 20));   //MODER[21:20] => 00
    (*vir_moder_led2) |= (0x1 << 20);      //MODER[21:20] => 01
    (*vir_odr_led2) &= (~(0x1 << 10));     //默认为关灯

    (*vir_moder_led3) &= (~(0x3 << 16));   //MODER[17:16] => 00
    (*vir_moder_led3) |= (0x1 << 16);      //MODER[17:16] => 01
    (*vir_odr_led3) &= (~(0x1 << 8));     //默认为关灯

    printk("寄存器初始化成功!\n");

    return 0;
}
static int __init mycdev_init(void)
{
    all_led_init();

    //1.申请一个驱动对象空间
    int retu;
    cdev=cdev_alloc();
    if(cdev == NULL)
    {
        printk("申请驱动对象空间失败!\n");
        retu = -EFAULT;
        goto out1;
    }
    printk("申请驱动对象空间成功!\n");
    //2.初始化设备对象
    cdev_init(cdev,&fops);
    //3.申请设备号
    int ret=0;
    if(major==0)
    {
        ret=alloc_chrdev_region(&devno,minor,3,"mycdev");
        if(ret!=0)
        {
        printk("(动态)申请设备号失败，错误码 => %d \n",ret);
        goto out2; 
        }
        major=MAJOR(devno);
        minor=MINOR(devno);
    }
    else
    {
        ret=register_chrdev_region(MKDEV(major,minor),3,"mycdev");
        if(ret!=0)
        {
        printk("(静态)申请设备号失败，错误码 => %d \n",ret);
        goto out2; 
        }
    }

    printk("申请设备号成功!\n");
    //4.注册设备驱动对象
    int ret1;
    ret1=cdev_add(cdev,MKDEV(major,minor),3);
    if(ret1!=0)
    {
        printk("注册设备驱动对象失败，错误码 => %d \n",ret1);
        goto out3;         
    }
    printk("注册设备驱动对象成功!\n");
    //5.向上提交目录
    cls=class_create(THIS_MODULE,"mycdev");
    if(IS_ERR(cls))
    {
        printk("向上提交目录失败!\n");
        goto out4;
    }
    printk("向上提交目录成功!\n");
    //6.向上提交节点信息
    int i;
    for(i=0;i<3;i++)
    {
        dev=device_create(cls,NULL,MKDEV(major,i),NULL,"mycdev%d",i);
        if(IS_ERR(dev))
        {
            printk("向上提交设备节点失败!\n");
           goto out5;
        }
    }
    printk("向上提交设备节点成功!\n");
    return 0;
out5:
    for(--i;i>=0;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 retu;
}
static void __exit mycdev_exit(void)
{
    //取消内存映射
    iounmap(vir_rcc);

    iounmap(vir_moder_led1);
    iounmap(vir_odr_led1);

    iounmap(vir_moder_led2);
    iounmap(vir_odr_led2);

    iounmap(vir_moder_led3);
    iounmap(vir_odr_led3);
    //销毁设备节点信息
    int i;
    for(i=0;i>3;i++)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    //销毁目录
    class_destroy(cls);
    //1.注销设备驱动
    cdev_del(cdev);
    //2.释放注册的设备号
    unregister_chrdev_region(MKDEV(major,minor),3);
    //释放对象空间
    kfree(cdev);

}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

test.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include "head.h"
int main(int argc,const char * argv[])
{
    char buf[128] = {0};
    int fd0 = open("/dev/mycdev0",O_RDWR);
    if(fd0 < 0)
    {
        printf("文件/dev/mycdev0打开失败\n");
        return -1;
    }
    printf("文件/dev/mycdev0打开成功\n");
    int fd1 = open("/dev/mycdev1",O_RDWR);
    if(fd1 < 0)
    {
        printf("文件/dev/mycdev1打开失败\n");
        return -1;
    }
    printf("文件/dev/mycdev1打开成功\n");
    int fd2 = open("/dev/mycdev2",O_RDWR);
    if(fd2 < 0)
    {
        printf("文件/dev/mycdev2打开失败\n");
        return -1;
    }
    printf("文件/dev/mycdev2打开成功\n");
    int a=0;
    int b=0;
    while(1)
    {
        printf("输入要进行的操作：");
        printf("0(关灯)1(开灯) >>  ");
        scanf("%d",&a);
        printf("请选择要控制的灯：1（LED1）2(LED2) 3(LED3) >> ");
        scanf("%d",&b);
        switch(a)
        {
            case 0://关灯
                switch(b)//哪个灯
                {
                    case 0:
                        ioctl(fd0,LED_OFF);
                        break;
                    case 1:
                        ioctl(fd1,LED_OFF);
                        break;
                    case 2:
                        ioctl(fd2,LED_OFF);
                        break;                   
                }
            break;
            case 1://开灯
                switch(b)//哪个灯
                {
                    case 0:
                        ioctl(fd0,LED_ON);
                        break;
                    case 1:
                        ioctl(fd1,LED_ON);
                        break;
                    case 2:
                        ioctl(fd2,LED_ON);
                        break;                   
                }
            break;             
        }

    }


    close(fd0);
    close(fd1);
    close(fd2);
    return 0;
}

head.h

#ifndef __HEAD_H__
#define __HEAD_H__
typedef struct{
    unsigned int MODER;
    unsigned int OTYPER;
    unsigned int OSPEEDR;
    unsigned int PUPDR;
    unsigned int IDR;
    unsigned int ODR;
}gpio_t;
#define PHY_RCC        0x50000A28

#define PHY_LED1_MODER 0x50006000
#define PHY_LED1_ODR   0x50006014

#define PHY_LED2_MODER 0x50007000
#define PHY_LED2_ODR   0x50007014
//构建功能码
#define LED_ON _IO('l', 1)  //开灯
#define LED_OFF _IO('l', 0)  //关灯

#endif