驱动day2 字符设备驱动 LED亮灯

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 
#include 
#include 
#include 
#include 
#include 
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 
#include 
#include 
#include 
#include 
#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
    //GPIOE
    vir_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;
    }
    //GPIOF
    vir_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;
    }
    //RCC
    vir_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