字符设备驱动分步注册实现LED驱动的编写

头文件

#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 RCC            0x50000A28
#define LED1_ADDR      0x50006000
#define LED2_ADDR      0x50007000
#define LED3_ADDR      0x50006000

#define LED_ON  _IOW('l',1,int)
#define LED_OFF _IOW('l',0,int)
#endif

应用层文件

#include<stdlib.h>
#include<stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include<unistd.h>
#include<string.h>
#include<sys/ioctl.h>
#include"head.h"
int main(int argc, char const *argv[])
{
    int fd;
    fd=open("/dev/myled0",O_RDWR);
    if(fd<0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    int a,b;
    while (1)
    {
        printf("请输入要实现的功能\n");
        printf("0关灯，1开灯\n");
        printf("请输入>");
        scanf("%d",&a);
        printf("请输入控制的灯\n");
        printf("1(LED1)2(LED2)3(LED3)\n");
        scanf("%d",&b);
        switch (a)
        {
        case 1:
            ioctl(fd,LED_ON,&b);
            break;
        case 0:
            ioctl(fd,LED_OFF,&b);
            break;
        default:
            printf("输入错误\n");
            break;
        }
    }
    close(fd);
    
    return 0;
}

驱动文件

#include <linux/init.h>
#include <linux/module.h>
#include<linux/fs.h>
#include<linux/io.h>
#include<linux/device.h>

#include<linux/slab.h>
#include<linux/cdev.h>
#include<linux/uaccess.h>

#include"head.h"

struct cdev *cdev;
unsigned int major=0;//主设备号
unsigned int minor=0;//次设备号

char kbuf[128]={0};

struct class *cls;
struct device *dev;

unsigned int *vir_rcc;
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;


dev_t devno;

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__);
   unsigned long ret;
   if(size>sizeof(kbuf))
      size=sizeof(kbuf);
   ret=copy_to_user(ubuf,kbuf,size);
   if(ret)
   {
    printk("copy_to_user filed\n");
    return ret;
   }
     return 0;

}

ssize_t mycdev_write(struct file *file, const char  *ubuf, size_t size, loff_t *lof)
{
   unsigned long ret;
   if(size>sizeof(kbuf))
      size=sizeof(kbuf);
   ret=copy_from_user(kbuf,ubuf,size);
   if(ret)
   {
    printk("copy_to_user filed\n");
    return ret;
   }
     return 0;
}
long mycdev_ioctl(struct file *file,unsigned int cmd,unsigned long arg)
{
    int wh;
    int ret=copy_from_user(&wh,(void*)arg,4);
    if(ret)
    {
        printk("copy_from_user filed\n");
        return ret;
    }
    switch(cmd)
    {
        case LED_ON:
        switch(wh)
        {
            case 1:
             vir_led1->ODR |= (1<<10);
             break;
            case 2:
             vir_led2->ODR |= (1<<10);
             break;
            case 3:
             vir_led3->ODR |= (1<<8);
             break;
        } 
            break;
        case LED_OFF:
            switch(wh)
        {
            case 1:
              vir_led1->ODR &= (~(1<<10));
             break;
            case 2:
              vir_led2->ODR &= (~(1<<10));
             break;
            case 3:
              vir_led3->ODR &= (~(1<<8));
             break;
        } 
           
            break;
    }
    return 0;
}
int mycdev_close(struct inode *inode,struct file *file)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
int all_led_init(void)
{
    vir_led1=ioremap(LED1_ADDR,sizeof(gpio_t));
    if(vir_led1==NULL)
    {
        printk("led1内存映射失败");
        return -ENOMEM;
    }
    printk("led1内存映射成功");

    vir_led2=ioremap(LED2_ADDR,sizeof(gpio_t));
    if(vir_led2==NULL)
    {
        printk("led2内存映射失败");
        return -ENOMEM;
    }
    printk("led2内存映射成功");

    vir_led3=ioremap(LED3_ADDR,sizeof(gpio_t));
    if(vir_led3==NULL)
    {
        printk("led3内存映射失败");
    }
    printk("led3内存映射成功");

    
    vir_rcc=ioremap(RCC,4);
    if(vir_rcc==NULL)
    {
        printk("rcc内存映射失败");
    }
    printk("rcc内存映射成功");
  
    //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_led3->MODER |= (1<<16);
    vir_led3->ODR   &= (~(1<<8));

    printk("寄存器初始化成功\n");
    return 0;
}
struct file_operations fops=
{
  .open=mycdev_open,
  .read=mycdev_read,
  .write=mycdev_write,
  .unlocked_ioctl=mycdev_ioctl,
  .release=mycdev_close,
};
static int __init mycdev_init(void)
{
    int ret;
    //申请字符设备的驱动空间
    cdev = cdev_alloc();
   if (cdev == NULL)
    {
        return -EFAULT;
    }
    printk("字符设备驱动对象申请成功\n");
    //初始化驱动对象
    cdev_init(cdev,&fops);

    
    //动态申请
    if(major==0)
    {
        ret=alloc_chrdev_region(&devno,minor, 3,"myled");
        if(ret)
        {
            printk("动态申请设备号失败\n");
            goto out1;
        }
        major=MAJOR(devno);
        minor=MAJOR(devno);
    }
    //静态指定
    else
    {
      ret=register_chrdev_region(MKDEV(major,minor), 3,"myled");
      if(ret)
      {
        printk("静态申请设备号失败\n");
        goto out1;
      }
    }
    printk("设备号申请成功\n");
    
    //注册驱动
    ret=cdev_add(cdev,MKDEV(major,minor),3);
    if(ret)
    {
        printk("注册驱动失败\n");
        goto out2;
    }
    printk("注册驱动成功\n");
   
    //向上提交目录
    cls=class_create(THIS_MODULE,"led");
    if(IS_ERR(cls))
    {
        printk("向上提交目录失败\n");
        ret=-PTR_ERR(cls);
        goto out3;
    }
    printk("向上提交目录成功\n");
   
   //向上提交设备节点

 int i;
 for(i=0;i<3;i++)
 {
   dev = device_create(cls, NULL, MKDEV(major, i), NULL, "myled%d", i);
    if(IS_ERR(dev))
  {
    printk("向上提交设备信息失败\n");
    ret=-PTR_ERR(dev);
    goto out4;
  }
 }
 printk("向上提交设备信息成功\n");
   //寄存器映射以及初始化
   all_led_init();
    return 0;
out4:
//销毁提交设备成功的设备信息
   for ( --i; i>=0; i--)
   {
     device_destroy(cls,MKDEV(major,i));
    /* code */
   }
    class_destroy(cls);
out3:
   cdev_del(cdev);
out2:
   unregister_chrdev_region(MKDEV(major,minor),3);
out1:
   kfree(cdev);
   return ret;
   
}
static void __exit mycdev_exit(void)
{
    
  //取消地址映射
  iounmap(vir_rcc); 
  iounmap(vir_led1);
  iounmap(vir_led2);
  iounmap(vir_led3);

  //销毁设备节点
  int i;
  for ( i = 0; i < 3; i++)
  {
    device_destroy(cls,MKDEV(major,i));
  }
  //销毁目录
  class_destroy(cls);
  //注销驱动对象
   cdev_del(cdev); 
   //释放设备号
    unregister_chrdev_region(MKDEV(major,minor),3);
  //释放空间
  kfree(cdev);

}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

makefile

arch?=arm
modname?=register_dev_c
ifeq ($(arch),arm)
KERNELDIR:=/home/ubuntu/linux-5.10.61
else
KERNELDIR:=/lib/modules/$(shell uname -r)/build
endif
PWD:=$(shell pwd)

all:
	make -C $(KERNELDIR) M=$(PWD) modules
clean:
	make -C $(KERNELDIR) M=$(PWD) clean 
obj-m:= $(modname).o

执行效果