2.15作业

原创于 2024-02-15 20:02:01 发布 · 199 阅读

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本文详细描述了一个Linux内核中的字符设备驱动程序，涉及函数如打开/关闭设备、读写操作，以及使用ioremap映射GPIO寄存器进行LED控制。通过`mychardev_init`和`mychardev_exit`模块初始化和退出函数管理设备注册和资源释放。

驱动代码：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include "head.h"
#include <linux/io.h>
 
unsigned int major;
char kbuf[128] = {0};
unsigned int *mode_e;
unsigned int *rcc;
unsigned int *odr_e;
unsigned int *odr_f;
unsigned int *mode_f;
 
ssize_t mychardev_read(struct file *file, char __user *user, size_t size, loff_t *loff)
{
    unsigned int ret;
    ret = copy_to_user(user, kbuf, size);
    if (ret)
    {
        printk("error=%d\n", __LINE__);
        return -1;
    }
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
 
ssize_t mychardev_write(struct file *file, const char __user *user, size_t size, loff_t *loff)
{
    unsigned int ret;
    ret = copy_from_user(kbuf, user, size);
    if (ret)
    {
        printk("error=%d\n", __LINE__);
        return -1;
    }
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    if (kbuf[0] == '1')
    {
        (*odr_e) |= (0x1 << 10);
    }
    else if (kbuf[0] == '4')
    {
        (*odr_e) &= (~(0x1 << 10));
    }
    else if (kbuf[0] == '2')
    {
        (*odr_f) |= (0x1 << 10);
    }
    else if (kbuf[0] == '5')
    {
        (*odr_f) &= (~(0x1 << 10));
    }
    else if (kbuf[0] == '3')
    {
        (*odr_e) |= (0x1 << 8);
    }
    else if (kbuf[0] == '6')
    {
        (*odr_e) &= (~(0x1 << 8));
    }
    return 0;
}
 
int mychardev_open(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
 
int mychardev_release(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
struct file_operations fops = {
    .open = mychardev_open,
    .release = mychardev_release,
    .read = mychardev_read,
    .write = mychardev_write,
};
 
static int __init mycdev_init(void)
{
    major = register_chrdev(0, "mychar_dev", &fops);
    if (major < 0)
    {
        printk("%d\n", __LINE__);
        return 0;
    }
    printk("major=%d\n", major);
    //GPIOE映射虚拟空间
    mode_e = ioremap(GPIOE_MORE, 4);
    if (mode_e == NULL)
    {
        printk("mode_e error=%d\n", __LINE__);
        return 0;
    }
    rcc = ioremap(RCC_GPIO, 4);
    if (rcc == NULL)
    {
        printk("rcc error=%d\n", __LINE__);
        return 0;
    }
    odr_e = ioremap(GPIOE_ODR, 4);
    if (odr_e == NULL)
    {
        printk("odr_e error=%d\n", __LINE__);
        return 0;
    }
    //GPIOF映射虚拟空间
    mode_f = ioremap(GPIOF_MORE, 4);
    if (mode_f == NULL)
    {
        printk("mode_f error=%d\n", __LINE__);
        return 0;
    }
    odr_f = ioremap(GPIOF_ODR, 4);
    if (odr_f == NULL)
    {
        printk("odr_f error=%d\n", __LINE__);
        return 0;
    }
    printk("地址映射完成\n");
    //GPIOE和GPIOF时钟使能
    (*rcc) |= (0x3 << 4);
    //PE10初始化
    (*mode_e) &= (~(0x3 << 20));
    (*mode_e) |= (0x1 << 20);
    (*odr_e) &= (~(0x1 << 10));
    //PF10初始化
    (*mode_f) &= (~(0x3 << 20));
    (*mode_f) |= (0x1 << 20);
    (*odr_f) &= (~(0x1 << 10));
    //PE8初始化
    (*mode_e) &= (~(0x3 << 16));
    (*mode_e) |= (0x1 << 16);
    (*odr_e) &= (~(0x1 << 8));
    return 0;
}
 
static void __exit mycdev_exit(void)
{
    iounmap(mode_e);
    iounmap(odr_e);
    iounmap(rcc);
    iounmap(mode_f);
    iounmap(odr_f);
    unregister_chrdev(major, "mychar_dev");
}
 
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

head.h

#ifndef __HEAD_H__
#define __HEAD_H__
 
#define RCC_GPIO 0x50000A28
#define GPIOE_MORE 0x50006000
#define GPIOE_ODR 0x50006014
#define GPIOF_MORE 0x50007000
#define GPIOF_ODR 0x50007014
 
#endif

执行代码：

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
int main(int argc, const char *argv[])
{
    char buf[128] = {};
    int fd = open("/dev/mychar_dev", O_RDWR);
    if (fd < 0)
    {
        printf("error=%d\n", __LINE__);
        return -1;
    }
    while (1)
    {
 
        printf("请输入相关命令1,2,3(开灯),4,5,6(关灯);");
        fgets(buf, sizeof(buf), stdin);
        buf[strlen(buf) - 1] = '\0';
        if (buf[0] >= '7')
        {
            printf("输入有误，请重新输入！");
        }
        printf("%s\n", buf);
        write(fd, buf, sizeof(buf)); // 从驱动中传递数据
        // memset(buf,0,sizeof(buf));//清空数据
        // printf("%s\n",buf);
        // read(fd,buf,sizeof(buf));//从驱动中读取数据
        // printf("%s\n",buf);
    }
    close(fd);
    return 0;
}