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可参考arm点灯C语言 cortex-A7核 点LED灯 （附 汇编实现、使用C语言 循环实现、使用C语言 封装函数实现【重要、常用】）-CSDN博客

1 应用程序 test.c

#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");return -1;}printf("打开设备文件成功\n");   while(1){printf("请输入要进行的操作：0(关灯) 1(开灯) >>> ");fgets(buf,sizeof(buf),stdin);//在终端读一个字符串buf[strlen(buf) - 1] = '\0';write(fd, buf, sizeof(buf));//将数据传递给内核}close(fd);return 0;
}

2 头文件head.h

#ifndef __HEAD_H__
#define __HEAD_H__
//GPIOE
#define PHY_LED1_MODER 0X50006000
#define PHY_LED1_ODR 0x50006014
//GPIOF
#define PHY_LED2_MODER 0X50007000
#define PHY_LED2_ODR 0x50007014
//RCC
#define PHY_RCC 0x50000A28#endif

3 驱动程序 demo.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include "head.h"
unsigned int major;
char kbuf[128] = {};
//定义三个指针指向映射后的虚拟内存
unsigned int *vir_moder_E;
unsigned int *vir_odr_E;
unsigned int *vir_moder_F;
unsigned int *vir_odr_F;
unsigned int *vir_rcc;
//封装操作方法
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;ret = copy_to_user(ubuf,kbuf,size);if (ret){printk("copy_to_user filed\n");return -EIO;}return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size,loff_t *lof)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);int ret;ret = copy_from_user(kbuf,ubuf,size);if (ret){printk("copy_from_user filed\n");return -EIO;}if(kbuf[0] == '0') //关灯{//关灯逻辑(*vir_odr_E) &= (~(0x1 << 10)); //LED1默认关灯(*vir_odr_F) &= (~(0x1 << 10)); //LED2默认关灯(*vir_odr_E) &= (~(0x1 << 8)); //LED3默认关灯}else if(kbuf[0] == '1') //开灯{//开灯逻辑(*vir_odr_E) |= (0x1 << 10); //LED1(*vir_odr_F) |= (0x1 << 10); //LED2(*vir_odr_E) |= (0x1 << 8); //LED3}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对象
struct file_operations fops = {.open = mycdev_open,.read = mycdev_read,.write = mycdev_write,.release = mycdev_close,
};
static int __init mycdev_init(void)
{//注册字符设备驱动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);//进行寄存器的地址映射//GPIOEvir_moder_E = ioremap(PHY_LED1_MODER,4);if(vir_moder_E == NULL){printk("物理内存地址映射失败%d\n",__LINE__);return -EFAULT;}vir_odr_E = ioremap(PHY_LED1_ODR,4);if(vir_odr_E == NULL){printk("物理内存地址映射失败%d\n",__LINE__);return -EFAULT;}//GPIOFvir_moder_F = ioremap(PHY_LED2_MODER,4);if(vir_moder_F == NULL){printk("物理内存地址映射失败%d\n",__LINE__);return -EFAULT;}vir_odr_F = ioremap(PHY_LED2_ODR,4);if(vir_odr_F == NULL){printk("物理内存地址映射失败%d\n",__LINE__);return -EFAULT;}//RCCvir_rcc = ioremap(PHY_RCC,4);if(vir_rcc == NULL){printk("物理内存地址映射失败%d\n",__LINE__);return -EFAULT;}printk("寄存器内存映射成功\n");//LED1寄存器初始化(*vir_rcc) |= (0x1 << 4); //GPIOE控制器时钟使能(*vir_moder_E) &= (~(0x3 << 20)); //MODER[21:20]->00(*vir_moder_E) |= (0x1 << 20); //MODER[21:20]->01(*vir_odr_E) &= (~(0x1 << 10)); //默认关灯//LED2寄存器初始化(*vir_rcc) |= (0x1 << 5); //GPIOF控制器时钟使能(*vir_moder_F) &= (~(0x3 << 20)); //MODER[21:20]->00(*vir_moder_F) |= (0x1 << 20); //MODER[21:20]->01(*vir_odr_F) &= (~(0x1 << 10)); //默认关灯//LED3寄存器初始化(*vir_rcc) |= (0x1 << 4); //GPIOE控制器时钟使能(*vir_moder_E) &= (~(0x3 << 16)); //MODER[17:16]->00(*vir_moder_E) |= (0x1 << 16); //MODER[17:16]->01(*vir_odr_E) &= (~(0x1 << 8)); //默认关灯return 0;
}
static void __exit mycdev_exit(void)
{//取消内存映射iounmap(vir_moder_E);iounmap(vir_odr_E);iounmap(vir_moder_F);iounmap(vir_odr_F);iounmap(vir_rcc);//注册字符设备驱动unregister_chrdev(major,"mychrdev");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

编写好代码后，make成arm架构

make arch=arm modname=demo

使用交叉编译工具链

arm-linux-gnueabihf-gcc test.c 

将文件通过tftp传输到开发板中

cp demo.ko ~/nfs/rootfs/
cp a.out ~/nfs/rootfs/

4 效果呈现