使用结构体形式对寄存器地址进行映射，实现3盏LED灯的循环点亮

1、创建LED灯点亮所需要的GPIO寄存器的结构体，并对寄存器地址进行宏定义

 2、①通过ioremap函数将物理地址映射为虚拟地址

void* ioremap(phys_addr_t offset, size_t size)

函数功能：将物理地址映射为虚拟地址

参数：

@offset：物理地址

@size：映射大小，单位字节

返回值： 成功返回虚拟地址，失败返回NULL

②通过映射的虚拟地址对寄存器进行初始化

3、通过copy_from_user函数从用户空间读取信息，对要进行操作的灯进行判断，并对相应寄存器进行操作

int copy_from_user(void *to, const void __user volatile *from, unsigned long n)

函数功能:将数据从用户空间拷贝到内核空间

参数：

@to:内核空间首地址

@from：用户空间首地址

@ n：拷贝数据大小(以字节为单位)

返回值： 成功返回0 失败返回未拷贝的字节数

 4、通过iounmap取消对寄存器的映射

void iounmap(void __iomem *addr)

函数功能：取消映射

参数：

 

@offset：映射之后的虚拟地址

返回值： 无

附实现代码

测试代码：

#include <stdio.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<unistd.h>
#include<stdlib.h>
#include<string.h>
char buf[128] = {0};

int main(int argc, const char *argv[])
{
    int fd = -1;
    int i=0;
    fd = open("/dev/led",O_RDWR);
    if(-1 == fd)
    {
        perror("open is error");
        exit(1);
    }
    while(1)
    {
        buf[0]='1';
        buf[1]='1';
        write(fd,buf,sizeof(buf));
        sleep(1);
        buf[1]='0';
        write(fd,buf,sizeof(buf));
        sleep(1);

        buf[0]='2';
        buf[1]='1';
        write(fd,buf,sizeof(buf));
        sleep(1);
        buf[1]='0';
        write(fd,buf,sizeof(buf));
        sleep(1);

        buf[0]='3';
        buf[1]='1';
        write(fd,buf,sizeof(buf));
        sleep(1);
        buf[1]='0';
        write(fd,buf,sizeof(buf));
    }
    close(fd);
	
	return 0;
}

#ifndef __LED_H__
#define __LED_H__

typedef struct{
    volatile unsigned int MODER;
    volatile unsigned int OTYPER;
    volatile unsigned int OSPEEDR;
    volatile unsigned int PUPDR;
    volatile unsigned int IDR;
    volatile unsigned int ODR;
}gpio_t;

#define GPIOE_ADDR 0x50006000
#define GPIOF_ADDR 0x50007000
#define RCC_ADDR 0x50000A28



#endif

 功能代码

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

#define GNAME "mydev"
volatile gpio_t* VIRT_GPIOE;
volatile gpio_t* VIRT_GPIOF;
volatile unsigned int* VIRT_RCC;
int major;
char kbuf[128]={0};
int mydev_open(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
ssize_t mydev_read(struct file *file, char __user *ubuf, size_t size, loff_t *loff)
{ 
    int set;
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    if(size > sizeof(kbuf)) size = sizeof(kbuf);
    set = copy_to_user(ubuf,kbuf,size);
    if(set)
    {
        printk("copy to user is error\n");
        return -EIO;
    }
    return size;
}
ssize_t mydev_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff)
{
    int ret;
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    if(size > sizeof(kbuf)) size = sizeof(kbuf);
    ret = copy_from_user(kbuf,ubuf,size);
    if(ret)
    {
        printk("copy from user is error\n");
        return -EIO;
    }
    printk("copy from user kbuf = %s\n",kbuf);
    switch(kbuf[0])
    {
        case '1':
                if(kbuf[1]=='1')
                {
                    VIRT_GPIOE->ODR |= (0x1<<10);
                }
                else if(kbuf[1]=='0')
                {
                    VIRT_GPIOE->ODR &= (~(0x1<<10));
                }
                break;
        case '3':
                if(kbuf[1]=='1')
                {
                    VIRT_GPIOE->ODR |= (0x1<<8);
                }
                else if(kbuf[1]=='0')
                {
                    VIRT_GPIOE->ODR &= (~(0x1<<8));
                }
                break;
        case '2':
                if(kbuf[1]=='1')
                {
                    VIRT_GPIOF->ODR |= (0x1<<10);
                }
                else if(kbuf[1]=='0')
                {
                    VIRT_GPIOF->ODR &= (~(0x1<<10));
                }
                break;
    }

    return size;
}
int mydev_close(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
struct file_operations fops={
    .open=mydev_open,
    .read=mydev_read,
    .write=mydev_write,
    .release=mydev_close,
};

static int __init mydev_init(void)
{
    major=register_chrdev(0,GNAME,&fops);
    if(major<0)
    {
        printk("register file\n");
        return major;
    }
    printk("major=%d\n",major);
    VIRT_RCC = ioremap(RCC_ADDR,4);
    if(NULL == VIRT_RCC)
    {
        printk("VIRT_RCC error\n");
        return -ENXIO;
    }
    VIRT_GPIOE = ioremap(GPIOE_ADDR,4);
    if(NULL == VIRT_GPIOE)
    {
        printk("VIRT_GPIOE error\n");
        return -ENXIO;
    }
    VIRT_GPIOF = ioremap(GPIOF_ADDR,4);
    if(NULL == VIRT_GPIOF)
    {
        printk("VIRT_GPIOF error\n");
        return -ENXIO;
    }
    *VIRT_RCC |= (0x3<<4);

    VIRT_GPIOE->MODER &= (~(0x3<<20));
    VIRT_GPIOE->MODER |= (0x1<<20);
    VIRT_GPIOE->ODR &= (~(0x1<<10));

    VIRT_GPIOE->MODER &= (~(0x3<<16));
    VIRT_GPIOE->MODER |= (0x1<<16);
    VIRT_GPIOE->ODR &= (~(0x1<<8));

    VIRT_GPIOF->MODER &= (~(0x3<<20));
    VIRT_GPIOF->MODER |= (0x1<<20);
    VIRT_GPIOF->ODR &= (~(0x1<<10));
    return 0;
}

static void __exit mydev_exit(void)
{
    unregister_chrdev(major,GNAME);
    iounmap(VIRT_GPIOE);
    iounmap(VIRT_GPIOF);
    iounmap(VIRT_RCC);
}

module_init(mydev_init);
module_exit(mydev_exit);

MODULE_LICENSE("GPL");