【驱动开发】创建设备节点、ioctl函数的使用

一、控制三盏灯的亮灭

头文件：

#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_led1_addr 0x50006000
#define phy_led2_addr    0x50007000
#define phy_led3_addr 0x50006000
#define phy_rcc_addr    0x50000a28
#endif 

驱动程序：

#include <linux/init.h>
#include <linux/module.h>
#include<linux/fs.h>
#include<linux/io.h>
#include"head.h"

int major;
char kbuf[128]={0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
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__);
     unsigned long ret;
    //向用户空间读取拷贝
    if(size>sizeof(kbuf))//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(kbuf);
    ret=copy_to_user(ubuf,kbuf,size);
    if(ret)//拷贝失败
    {
        printk("copy_to_user filed\n");
        return ret;
    }
    return 0;
}
ssize_t mycdev_write(struct file *file, const char  *ubuf, size_t size, loff_t *lof)
{
    unsigned long ret;
    //从用户空间读取数据
    if(size>sizeof(kbuf))//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(kbuf);
    ret=copy_from_user(kbuf,ubuf,size);
    if(ret)//拷贝失败
    {
        printk("copy_to_user filed\n");
        return ret;
    }
    switch(kbuf[0]){
        case '1'://led1
            if(kbuf[1]=='0')//关灯
                vir_led1->odr &= (~(1<<10));
            else//开灯
                vir_led1->odr |= 1<<10;
            break;
        case '2'://led2
            if(kbuf[1]=='0')//关灯
                vir_led2->odr &= (~(1<<10));
            else//开灯
                vir_led2->odr |= 1<<10;
            break;
        case '3'://led3
            if(kbuf[1]=='0')//关灯
                vir_led3->odr &= (~(1<<8));
            else//开灯
                vir_led3->odr |= 1<<8;
            break;
    }
    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,
    .write=mycdev_write,
    .release=mycdev_close,
};

int all_led_init(void)
{
    //寄存器地址的映射
    vir_led1=ioremap(phy_led1_addr,sizeof(gpio_t));
    if(vir_led1==null)
    {
        printk("ioremap filed：%d\n",__line__);
        return -enomem;
    }
     vir_led2=ioremap(phy_led2_addr,sizeof(gpio_t));
    if(vir_led2==null)
    {
        printk("ioremap filed：%d\n",__line__);
        return -enomem;
    }
     vir_led3=vir_led1;
    vir_rcc=ioremap(phy_rcc_addr,4);
    if(vir_rcc==null)
    {
        printk("ioremap filed：%d\n",__line__);
        return -enomem;
    }
    printk("物理地址映射成功\n");
    //寄存器的初始化
    //rcc
    (*vir_rcc) |= (3<<4);
    //led1
    vir_led1->moder &= (~(3<<20));
    vir_led1->moder |= (1<<20);
    vir_led1->odr &= (~(1<<10));
    //led2
    vir_led2->moder &= (~(3<<20));
    vir_led2->moder |= (1<<20);
    vir_led2->odr &= (~(1<<10));
    //led3
    vir_led3->moder &= (~(3<<16));
    vir_led1->moder |= (1<<16);
    vir_led1->odr &= (~(1<<8));
    printk("寄存器初始化成功\n");

    return 0;
}

static int __init mycdev_init(void)
{
    //字符设备驱动注册
    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:major=%d\n",major);

    //寄存器映射以及初始化
    all_led_init();

    return 0;
}
static void __exit mycdev_exit(void)
{
    //取消地址映射
    iounmap(vir_led1);
    iounmap(vir_led2);
    iounmap(vir_rcc);
    //注销字符设备驱动
    unregister_chrdev(major,"mychrdev");


}
module_init(mycdev_init);
module_exit(mycdev_exit);
module_license("gpl");

应用程序：

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

int main(int argc, char const *argv[])
{
    char buf[128]={0};
    int fd=open("/dev/mychrdev",o_rdwr);
    if(fd<0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    while(1)
    {
        //从终端读取
        printf("请输入两个字符\n");
        printf("第一个字符:1(led1) 2(led2) 3(led3)\n");
        printf("第二个字符:0(关灯) 1(开灯)\n");
        printf("请输入>");
        fgets(buf,sizeof(buf),stdin);
        buf[strlen(buf)-1]='\0';
        //向设备文件中写
        write(fd,buf,sizeof(buf));
    }

    close(fd);
    return 0;
}

二、自动创建设备节点

1.创建设备节点的机制

2.udev创建设备节点的原理

3.创建设备节点的相关api

**************创建设备文件相关**********
#include<linux/device.h>
1.向上提交目录
struct class *class_create(struct module *owner, const char *name)
功能：向上提交目录信息，申请了一个struct class对象并初始化
参数：
    owner:指向当前模块自身的一个指针，填写this_module
    name:向上提交的目录名
返回值：成功返回申请到的class对象的首地址，失败返回一个指向内核顶层4k空间的指针
    /* 
        关关于返回值判断问题：
        只要判断指针的数值>4k预留空间起始值就说明函数调用失败
        bool __must_check is_err(__force const void *ptr)
                //#define is_err_value(x) (unsigned long)(void *)(x) >= 0xfffffff-4095
    功能：判断指针是否指向内核4k预留空间，如果指针指向4k预留空间返回真，否则返回假
        long __must_check ptr_err(__force const void *ptr)
           功能：将一个指针转换成long类型错误码返回
    */
    
ex:
        struct class *cls=class_create(this_module,"mychrdev");
        if(is_err(cls))
        {
            printk("向上提交目录失败\n");
            return -ptr_err(cls);        
        }

2.向上提交设备节点信息
struct device *device_create(struct class *class, struct device *parent,
                 dev_t devt, void *drvdata, const char *fmt, ...)
功能：向上提交设备节点信息，申请一个struct  device对象并初始化
参数：
    class:class_create()得到的对象指针
    parent:父节点指针，不知道就填null
    devt:设备号    主设备号<<20|次设备号
        /*
            mkdev(主设备号，次设备号)：根据主设备号和次设备号得到设备号
            major(dev)：根据设备号得到主设备号
            minor(dev)：根据设备号得到次设备号
        */
        drvdata:当前对象的一个私有数据，填null
        fmt:填要创建的设备节点名  video%d
        ...:不定长参数       i
返回值：成功返回创建成功的struct device对象指针，失败返回指针指向4k预留空间
************删除设备文件相关**********
销毁节点信息：
void device_destroy(struct class *class, dev_t devt)
功能：销毁节点信息
参数：
    class:class_create()得到的对象指针
    devt:向上提交设备节点是填写的设备号
销毁目录
void class_destroy(struct class *cls)
参数：class_create()得到的对象指针
返回值：无

4.实例

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

int major;
char kbuf[128]={0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
struct class *cls;
struct device *dev;
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__);
     unsigned long ret;
    //向用户空间读取拷贝
    if(size>sizeof(kbuf))//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(kbuf);
    ret=copy_to_user(ubuf,kbuf,size);
    if(ret)//拷贝失败
    {
        printk("copy_to_user filed\n");
        return ret;
    }
    return 0;
}
ssize_t mycdev_write(struct file *file, const char  *ubuf, size_t size, loff_t *lof)
{
    unsigned long ret;
    //从用户空间读取数据
    if(size>sizeof(kbuf))//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(kbuf);
    ret=copy_from_user(kbuf,ubuf,size);
    if(ret)//拷贝失败
    {
        printk("copy_to_user filed\n");
        return ret;
    }
    switch(kbuf[0]){
        case '1'://led1
            if(kbuf[1]=='0')//关灯
                vir_led1->odr &= (~(1<<10));
            else//开灯
                vir_led1->odr |= 1<<10;
            break;
        case '2'://led2
            if(kbuf[1]=='0')//关灯
                vir_led2->odr &= (~(1<<10));
            else//开灯
                vir_led2->odr |= 1<<10;
            break;
        case '3'://led3
            if(kbuf[1]=='0')//关灯
                vir_led3->odr &= (~(1<<8));
            else//开灯
                vir_led3->odr |= 1<<8;
            break;
    }
    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,
    .write=mycdev_write,
    .release=mycdev_close,
};

int all_led_init(void)
{
    //寄存器地址的映射
    vir_led1=ioremap(phy_led1_addr,sizeof(gpio_t));
    if(vir_led1==null)
    {
        printk("ioremap filed：%d\n",__line__);
        return -enomem;
    }
     vir_led2=ioremap(phy_led2_addr,sizeof(gpio_t));
    if(vir_led2==null)
    {
        printk("ioremap filed：%d\n",__line__);
        return -enomem;
    }
     vir_led3=vir_led1;
    vir_rcc=ioremap(phy_rcc_addr,4);
    if(vir_rcc==null)
    {
        printk("ioremap filed：%d\n",__line__);
        return -enomem;
    }
    printk("物理地址映射成功\n");
    //寄存器的初始化
    //rcc
    (*vir_rcc) |= (3<<4);
    //led1
    vir_led1->moder &= (~(3<<20));
    vir_led1->moder |= (1<<20);
    vir_led1->odr &= (~(1<<10));
    //led2
    vir_led2->moder &= (~(3<<20));
    vir_led2->moder |= (1<<20);
    vir_led2->odr &= (~(1<<10));
    //led3
    vir_led3->moder &= (~(3<<16));
    vir_led1->moder |= (1<<16);
    vir_led1->odr &= (~(1<<8));
    printk("寄存器初始化成功\n");

    return 0;
}

static int __init mycdev_init(void)
{
    //字符设备驱动注册
    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:major=%d\n",major);
    //向上提交目录
    cls=class_create(this_module,"mychrdev");
    if(is_err(cls))
    {
        printk("向上提交目录失败\n");
        return -ptr_err(cls);
    }
    printk("向上提交目录成功\n");
    //向上提交设备节点信息
    int i;//向上提交三次设备节点信息
    for(i=0;i<3;i++)
    {
        dev=device_create(cls,null,mkdev(major,i),null,"myled%d",i);
        if(is_err(dev))
        {
            printk("向上提交设备节点失败\n");
            return -ptr_err(dev);
        }
    }
    printk("向上提交设备节点成功\n");

    //寄存器映射以及初始化
    all_led_init();

    return 0;
}
static void __exit mycdev_exit(void)
{
    //取消地址映射
    iounmap(vir_led1);
    iounmap(vir_led2);
    iounmap(vir_rcc);
    //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);
    //注销字符设备驱动
    unregister_chrdev(major,"mychrdev");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
module_license("gpl");

三、ioctl函数的使用

1.引入ioctl函数的意义

2.ioctl函数的分析

*********系统调用函数的分析**********
#include <sys/ioctl.h>
int ioctl(int fd, unsigned long request, ...);
功能：进行io功能的设置   
参数：
fd:文件描述符
request:io控制的功能码
...:可以加，也可以不加。如果第三个参数传递数值，只能传递整型数据和指针
返回值：成功返回0，失败返回错误码

*********驱动中操作方法的分析********
long (*unlocked_ioctl) (struct file *file, unsigned int cmd, unsigned long arg)
{
    参数分析：
        file:文件指针
        cmd:应用程序中的ioctl第二个参数传递过来
        arg:应用程序中的ioctl第三个参数传递过来
}

3.ioctl功能码的构建

====== ==================================
 bits   meaning
 ====== ==================================
 31-30    00 - no parameters: uses _io macro
    10 - read: _ior
    01 - write: _iow
    11 - read/write: _iowr

 29-16    size of arguments

 15-8    ascii character supposedly
    unique to each driver

 7-0    function #
 ====== ==================================

#define _io(type,nr)        _ioc(_ioc_none,(type),(nr),0)
#define _ior(type,nr,size)    _ioc(_ioc_read,(type),(nr),sizeof(size))
#define _iow(type,nr,size)    _ioc(_ioc_write,(type),(nr),sizeof(size))
#define _iowr(type,nr,size)    _ioc(_ioc_read|_ioc_write,(type),(nr),sizeof(size)

#define _ioc(dir,type,nr,size)          \
    ((unsigned int)             \
     (((dir)  << _ioc_dirshift) |       \
      ((type) << _ioc_typeshift) |      \
      ((nr)   << _ioc_nrshift) |        \
      ((size) << _ioc_sizeshift)))
      
    ex：构建led开关的功能码：ioctl函数无第三个参数
    开灯  #define  led_on  _io('l',1)
    关灯  #define  led_off  _io('l',0)
    
        ex：构建led开关的功能码：ioctl函数有第三个参数
    开灯  #define  led_on  _iow('l',1,int)
    关灯  #define  led_off  _iow('l',0,int)

4.ioctl实例----不传递第三个参数

头文件:

#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_led1_addr 0x50006000
#define phy_led2_addr 0x50007000
#define phy_led3_addr 0x50006000
#define phy_rcc_addr 0x50000a28
// 构建开灯关灯的功能码
#define led_on _io('l', 1)
#define led_off _io('l', 0)
#endif

驱动程序：

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

int major;
char kbuf[128] = {0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
struct class *cls;
struct device *dev;
int mycdev_open(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __file__, __func__, __line__);
    return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    switch (cmd)
    {
    case led_on: // 开灯
        vir_led1->odr |= (0x1 << 10);
        vir_led2->odr |= (0x1 << 10);
        vir_led3->odr |= (0x1 << 8);
        break;
    case led_off: // 关灯
        vir_led1->odr &= (~(0x1 << 10));
        vir_led2->odr &= (~(0x1 << 10));
        vir_led3->odr &= (~(0x1 << 8));
        break;
    }
    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)
{
    // 寄存器地址的映射
    vir_led1 = ioremap(phy_led1_addr, sizeof(gpio_t));
    if (vir_led1 == null)
    {
        printk("ioremap filed：%d\n", __line__);
        return -enomem;
    }
    vir_led2 = ioremap(phy_led2_addr, sizeof(gpio_t));
    if (vir_led2 == null)
    {
        printk("ioremap filed：%d\n", __line__);
        return -enomem;
    }
    vir_led3 = vir_led1;
    vir_rcc = ioremap(phy_rcc_addr, 4);
    if (vir_rcc == null)
    {
        printk("ioremap filed：%d\n", __line__);
        return -enomem;
    }
    printk("物理地址映射成功\n");
    // 寄存器的初始化
    // rcc
    (*vir_rcc) |= (3 << 4);
    // led1
    vir_led1->moder &= (~(3 << 20));
    vir_led1->moder |= (1 << 20);
    vir_led1->odr &= (~(1 << 10));
    // led2
    vir_led2->moder &= (~(3 << 20));
    vir_led2->moder |= (1 << 20);
    vir_led2->odr &= (~(1 << 10));
    // led3
    vir_led3->moder &= (~(3 << 16));
    vir_led1->moder |= (1 << 16);
    vir_led1->odr &= (~(1 << 8));
    printk("寄存器初始化成功\n");

    return 0;
}

static int __init mycdev_init(void)
{
    // 字符设备驱动注册
    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:major=%d\n", major);
    // 向上提交目录
    cls = class_create(this_module, "mychrdev");
    if (is_err(cls))
    {
        printk("向上提交目录失败\n");
        return -ptr_err(cls);
    }
    printk("向上提交目录成功\n");
    // 向上提交设备节点信息
    int i; // 向上提交三次设备节点信息
    for (i = 0; i < 3; i++)
    {
        dev = device_create(cls, null, mkdev(major, i), null, "myled%d", i);
        if (is_err(dev))
        {
            printk("向上提交设备节点失败\n");
            return -ptr_err(dev);
        }
    }
    printk("向上提交设备节点成功\n");

    // 寄存器映射以及初始化
    all_led_init();

    return 0;
}
static void __exit mycdev_exit(void)
{
    // 取消地址映射
    iounmap(vir_led1);
    iounmap(vir_led2);
    iounmap(vir_rcc);
    // 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);
    // 注销字符设备驱动
    unregister_chrdev(major, "mychrdev");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
module_license("gpl");

应用程序：

#include <stdlib.h>
#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, char const *argv[])
{
    char buf[128] = {0};
    int a;
    int fd = open("/dev/myled0", o_rdwr);
    if (fd < 0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    while (1)
    {
        // 从终端读取
        printf("请输入要实现的功能 ");
        printf("0(关灯) 1(开灯)\n");
        printf("请输入>>>");
        scanf("%d", &a);
        switch (a)
        {
        case 1:
            ioctl(fd, led_on);
            break;
        case 0:
            ioctl(fd, led_off);
            break;
        }
    }
    close(fd);
    return 0;
}

5.ioctl实例----传递第三个参数（传递整型）

头文件：

#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_led1_addr 0x50006000
#define phy_led2_addr 0x50007000
#define phy_led3_addr 0x50006000
#define phy_rcc_addr 0x50000a28
// 构建开灯关灯的功能码
#define led_on _iow('l', 1, int)
#define led_off _iow('l', 0, int)

#endif

驱动程序：

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

int major;
char kbuf[128] = {0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
struct class *cls;
struct device *dev;
int mycdev_open(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __file__, __func__, __line__);
    return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    switch (cmd)
    {
    case led_on: // 开灯
        switch (arg)
        {
        case 1: // led1
            vir_led1->odr |= (0x1 << 10);
            break;
        case 2:
            vir_led2->odr |= (0x1 << 10);
            break;
        case 3:
            vir_led3->odr |= (0x1 << 8);
            break;
        }
        break;
    case led_off: // 关灯
        switch (arg)
        {
        case 1: // led1
            vir_led1->odr &= (~(0x1 << 10));
            break;
        case 2:
            vir_led2->odr &= (~(0x1 << 10));
            break;
        case 3:
            vir_led3->odr &= (~(0x1 << 8));
            break;
        }
        break;
    }
    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)
{
    // 寄存器地址的映射
    vir_led1 = ioremap(phy_led1_addr, sizeof(gpio_t));
    if (vir_led1 == null)
    {
        printk("ioremap filed：%d\n", __line__);
        return -enomem;
    }
    vir_led2 = ioremap(phy_led2_addr, sizeof(gpio_t));
    if (vir_led2 == null)
    {
        printk("ioremap filed：%d\n", __line__);
        return -enomem;
    }
    vir_led3 = vir_led1;
    vir_rcc = ioremap(phy_rcc_addr, 4);
    if (vir_rcc == null)
    {
        printk("ioremap filed：%d\n", __line__);
        return -enomem;
    }
    printk("物理地址映射成功\n");
    // 寄存器的初始化
    // rcc
    (*vir_rcc) |= (3 << 4);
    // led1
    vir_led1->moder &= (~(3 << 20));
    vir_led1->moder |= (1 << 20);
    vir_led1->odr &= (~(1 << 10));
    // led2
    vir_led2->moder &= (~(3 << 20));
    vir_led2->moder |= (1 << 20);
    vir_led2->odr &= (~(1 << 10));
    // led3
    vir_led3->moder &= (~(3 << 16));
    vir_led1->moder |= (1 << 16);
    vir_led1->odr &= (~(1 << 8));
    printk("寄存器初始化成功\n");

    return 0;
}

static int __init mycdev_init(void)
{
    // 字符设备驱动注册
    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:major=%d\n", major);
    // 向上提交目录
    cls = class_create(this_module, "mychrdev");
    if (is_err(cls))
    {
        printk("向上提交目录失败\n");
        return -ptr_err(cls);
    }
    printk("向上提交目录成功\n");
    // 向上提交设备节点信息
    int i; // 向上提交三次设备节点信息
    for (i = 0; i < 3; i++)
    {
        dev = device_create(cls, null, mkdev(major, i), null, "myled%d", i);
        if (is_err(dev))
        {
            printk("向上提交设备节点失败\n");
            return -ptr_err(dev);
        }
    }
    printk("向上提交设备节点成功\n");

    // 寄存器映射以及初始化
    all_led_init();

    return 0;
}
static void __exit mycdev_exit(void)
{
    // 取消地址映射
    iounmap(vir_led1);
    iounmap(vir_led2);
    iounmap(vir_rcc);
    // 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);
    // 注销字符设备驱动
    unregister_chrdev(major, "mychrdev");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
module_license("gpl");

应用程序：

#include <stdlib.h>
#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, char const *argv[])
{
    char buf[128] = {0};
    int a, b;
    int fd = open("/dev/myled0", o_rdwr);
    if (fd < 0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    while (1)
    {
        // 从终端读取
        printf("请输入要实现的功能 ");
        printf("0(关灯) 1(开灯)\n");
        printf("请输入>>>");
        scanf("%d", &a);
        printf("请选择要控制的灯：1（led1）2(led2) 3(led3)\n");
        printf("请输入>>>");
        scanf("%d", &b);
        switch (a)
        {
        case 1:
            ioctl(fd, led_on, b);
            break;
        case 0:
            ioctl(fd, led_off, b);
            break;
        }
    }

    close(fd);
    return 0;
}

6.ioctl实例----传递第三个参数（传递地址）

头文件：

#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_led1_addr 0x50006000
#define phy_led2_addr 0x50007000
#define phy_led3_addr 0x50006000
#define phy_rcc_addr 0x50000a28
// 构建开灯关灯的功能码
#define led_on _iow('l', 1,int)
#define led_off _iow('l', 0,int)

#endif

驱动程序：

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

int major;
char kbuf[128] = {0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
struct class *cls;
struct device *dev;
int mycdev_open(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __file__, __func__, __line__);
    return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    int which;
    //获取应用程序中b的值
    int ret= copy_from_user(&which,(void *)arg,4);
    if(ret)
    {
        printk("copy_from_user filed\n");
        return-eio;
    }
    switch (cmd)
    {
    case led_on: // 开灯
        switch (which)
        {
        case 1: // led1
            vir_led1->odr |= (0x1 << 10);
            break;
        case 2:
            vir_led2->odr |= (0x1 << 10);
            break;
        case 3:
            vir_led3->odr |= (0x1 << 8);
            break;
        }
        break;
    case led_off: // 关灯
          switch (which)
        {
        case 1: // led1
            vir_led1->odr &= (~(0x1 << 10));
            break;
        case 2:
            vir_led2->odr &= (~(0x1 << 10));
            break;
        case 3:
            vir_led3->odr &= (~(0x1 << 8));
            break;
        } 
        break;
    }
    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)
{
    // 寄存器地址的映射
    vir_led1 = ioremap(phy_led1_addr, sizeof(gpio_t));
    if (vir_led1 == null)
    {
        printk("ioremap filed：%d\n", __line__);
        return -enomem;
    }
    vir_led2 = ioremap(phy_led2_addr, sizeof(gpio_t));
    if (vir_led2 == null)
    {
        printk("ioremap filed：%d\n", __line__);
        return -enomem;
    }
    vir_led3 = vir_led1;
    vir_rcc = ioremap(phy_rcc_addr, 4);
    if (vir_rcc == null)
    {
        printk("ioremap filed：%d\n", __line__);
        return -enomem;
    }
    printk("物理地址映射成功\n");
    // 寄存器的初始化
    // rcc
    (*vir_rcc) |= (3 << 4);
    // led1
    vir_led1->moder &= (~(3 << 20));
    vir_led1->moder |= (1 << 20);
    vir_led1->odr &= (~(1 << 10));
    // led2
    vir_led2->moder &= (~(3 << 20));
    vir_led2->moder |= (1 << 20);
    vir_led2->odr &= (~(1 << 10));
    // led3
    vir_led3->moder &= (~(3 << 16));
    vir_led1->moder |= (1 << 16);
    vir_led1->odr &= (~(1 << 8));
    printk("寄存器初始化成功\n");

    return 0;
}

static int __init mycdev_init(void)
{
    // 字符设备驱动注册
    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:major=%d\n", major);
    // 向上提交目录
    cls = class_create(this_module, "mychrdev");
    if (is_err(cls))
    {
        printk("向上提交目录失败\n");
        return -ptr_err(cls);
    }
    printk("向上提交目录成功\n");
    // 向上提交设备节点信息
    int i; // 向上提交三次设备节点信息
    for (i = 0; i < 3; i++)
    {
        dev = device_create(cls, null, mkdev(major, i), null, "myled%d", i);
        if (is_err(dev))
        {
            printk("向上提交设备节点失败\n");
            return -ptr_err(dev);
        }
    }
    printk("向上提交设备节点成功\n");

    // 寄存器映射以及初始化
    all_led_init();

    return 0;
}
static void __exit mycdev_exit(void)
{
    // 取消地址映射
    iounmap(vir_led1);
    iounmap(vir_led2);
    iounmap(vir_rcc);
    // 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);
    // 注销字符设备驱动
    unregister_chrdev(major, "mychrdev");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
module_license("gpl");

应用程序：

#include<stdlib.h>
#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, char const *argv[])
{
    char buf[128]={0};
    int a,b;
    int fd=open("/dev/myled0",o_rdwr);
    if(fd<0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    while(1)
    {
        //从终端读取
        printf("请输入要实现的功能 ");
        printf("0(关灯) 1(开灯)\n");
        printf("请输入>");
        scanf("%d",&a);
        printf("请选择要控制的灯：1（led1）2(led2) 3(led3)\n");
        printf("请输入>");
        scanf("%d",&b);
        switch(a)
        {
            case 1:
                ioctl(fd,led_on,&b);
                break;
            case 0:
                ioctl(fd,led_off,&b);
                break;
        }
    }

    close(fd);
    return 0;
}