通过字符设备驱动的分步实现编写LED驱动，另外实现特备文件和设备的绑定

text.c

#include
#include
#include 
#include 
#include 
#include
#include
#include"head.h"
 
#include 
 
 
int main(int argc, char const *argv[])
{
    
    int a,b;
    while(1)
    {
        char buf[128]="/dev/mycdev";
        //从终端读取
        printf("请输入两个字符\n");
        printf("第一个字符:0(LED1) 1(LED2) 2(LED3)\n");
        scanf("%d",&b);
        sprintf(buf,"%s%d",buf,b);
        int fd=open(buf,O_RDWR);
        if(fd<0)
        {
            printf("打开设备文件失败\n");
            exit(-1);
        }
        printf("第二个字符:0(关灯) 1(开灯)\n");
        printf("请输入>");
        scanf("%d",&a);
        switch(a)
        {
            case 1:
                ioctl(fd,LED_ON);
                break;
            case 0:
                ioctl(fd,LED_OFF);
                break;
        }
        close(fd);
    }
   
    return 0;
}

head.h

#ifndef __HEAD_H__
#define __HEAD_H__ 
typedef struct{
    unsigned int MODER;
    unsigned int OTYPER;
    unsigned int OSPEEDR;
    unsigned int PUPDR;
    unsigned int IDR;
    unsigned int ODR;
}gpio_t;
#define PHY_LED1_ADDR 0X50006000
#define PHY_LED2_ADDR    0X50007000
#define PHY_LED3_ADDR 0X50006000
#define PHY_RCC_ADDR    0X50000A28
 
 
#define LED_ON _IO('l', 1)      
#define LED_OFF _IO('l', 0)
#endif 

dome.c

#include <linux/init.h>
#include <linux/module.h>
#include<linux/fs.h>
#include<linux/io.h>
#include<linux/device.h>
#include"head.h"
#include<linux/cdev.h>
#include<linux/slab.h>
 
 
char kbuf[128]={0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
struct class *cls;
struct device *dev;
 
struct cdev *cdev;
unsigned int major=0;
unsigned int minor=0;
dev_t devno;
 
 
int mycdev_open(struct inode *inode, struct file *file)
{
	int min=MINOR(inode->i_rdev);
	file->private_data=(void*)min;
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
long mycdev_ioctl(struct file *file,unsigned int cmd,unsigned long arg)
{
	int min=(int)file->private_data;
	switch(min)
	{
	case 0:
		switch (cmd)
		{
		case LED_ON:
			vir_led1->ODR |= (0x1 << 10);
			break;
		case LED_OFF:
			vir_led1->ODR &= (~(0X1 << 10));
			break;
		}
		break;
	case 1:
		switch (cmd)
		{
		case LED_ON:
			vir_led2->ODR |= (0X1 << 10);
			break;
		case LED_OFF:
			vir_led2->ODR &= (~(0X1 << 10));
			break;
		}
		break;
	case 2:
		switch (cmd)
		{
		case LED_ON:
			vir_led3->ODR |= (0X1 << 8);
			break;
		case LED_OFF:
			vir_led3->ODR &= (~(0X1 << 8));
			break;
		}
		break;
    }
    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变量并赋值
struct file_operations fops = {
 
    .open = mycdev_open,
    .unlocked_ioctl = mycdev_ioctl,
    .release = mycdev_close,
};
 
int all_led_init(void)
{
    //寄存器地址的映射
    vir_led1=ioremap(PHY_LED1_ADDR,sizeof(gpio_t));
    if(vir_led1==NULL)
    {
        printk("ioremap filed：%d\n",__LINE__);
        return -ENOMEM;
    }
     vir_led2=ioremap(PHY_LED2_ADDR,sizeof(gpio_t));
    if(vir_led2==NULL)
    {
        printk("ioremap filed：%d\n",__LINE__);
        return -ENOMEM;
    }
     vir_led3=vir_led1;
    vir_rcc=ioremap(PHY_RCC_ADDR,4);
    if(vir_rcc==NULL)
    {
        printk("ioremap filed：%d\n",__LINE__);
        return -ENOMEM;
    }
    printk("物理地址映射成功\n");
    //寄存器的初始化
    //rcc
    (*vir_rcc) |= (3<<4);
    //led1
    vir_led1->MODER &= (~(3<<20));
    vir_led1->MODER |= (1<<20);
    vir_led1->ODR &= (~(1<<10));
    //led2
    vir_led2->MODER &= (~(3<<20));
    vir_led2->MODER |= (1<<20);
    vir_led2->ODR &= (~(1<<10));
    //led3
    vir_led3->MODER &= (~(3<<16));
    vir_led1->MODER |= (1<<16);
    vir_led1->ODR &= (~(1<<8));
    printk("寄存器初始化成功\n");
 
    return 0;
}
 
static int __init mycdev_init(void)
{
    //1.申请一个对象空间cdev_alloc
    int ret;
    cdev= cdev_alloc();
    if(cdev==NULL)
    {
        printk("申请字符设备驱动对象失败\n");
        ret=-EFAULT;
        goto out1;
 
    }
    printk("字符设备驱动对象申请成功\n");
    //2.初始化对象cdev_init
    cdev_init(cdev,&fops);
    //3.申请设备号  register_chrdev_region()/alloc_chrdev_region()
    if(major==0)//动态申请
    {
        ret=alloc_chrdev_region(&devno,minor,3,"mycdev");
        if(ret)
        {
            printk("动态申请设备号失败\n");
            goto out2;
        }
        major=MAJOR(devno);//根据设备号获取主设备号
        minor=MINOR(devno);//根据设备号获取次设备号
    }
    else
    {
        ret=register_chrdev_region(MKDEV(major,minor),3,"mycdev");
        if(ret)
        {
            printk("静态指定设备号失败\n");
            goto out2;
        }
    }
    printk("设备号申请成功\n");
    //4.注册驱动对象  cdev_add
    ret=cdev_add(cdev,MKDEV(major,minor),3);
    if(ret)
    {
        printk("注册字符设备驱动对象失败\n");
        goto out3;
    }
    printk("注册字符设备驱动对象成功\n");
    //5.向上提交目录  class_create
    cls=class_create(THIS_MODULE,"mycdev");
    if(IS_ERR(cls))
    {
        printk("向上提交目录失败\n");
        goto out4;
    }
    printk("向上提交目录成功\n");
    //6.向上提交设备节点信息  device_create
    int i;
    for(i=0;i<3;i++)
    {
        dev=device_create(cls,NULL,MKDEV(major,i),NULL,"mycdev%d",i);
        if(IS_ERR(dev))
        {
            printk("向上提交设备节点失败\n");
            goto out5;
        }
    }
    printk("向上提交设备节点信息成功\n");
 
    //寄存器映射以及初始化
    all_led_init();
 
    return 0;
out5:
//将提交成功的节点信息释放
    for(--i;i>=0;i--)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    //销毁目录
    class_destroy(cls);
out4:
    cdev_del(cdev);
out3:
    unregister_chrdev_region(MKDEV(major,minor),3);
out2:
    kfree(cdev);
out1:
    return ret;
}
static void __exit mycdev_exit(void)
{
    //取消地址映射
    iounmap(vir_led1);
    iounmap(vir_led2);
    iounmap(vir_rcc);
 
    //1.销毁设备节点信息
    int i;
    for(i=0;i<3;i++)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    //2.销毁目录
    class_destroy(cls);
    //3.注销字符设备驱动对象
    cdev_del(cdev);
    //4.释放设备号
    unregister_chrdev_region(MKDEV(major,minor),3);
    //5.释放申请到的字符设备驱动对象空间
    kfree(cdev);
}
 
 
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");