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 
#include
#include
#include
#include
#include
#include
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
#include
#include
#include
#include
#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");

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