字符设备驱动分步注册过程实现LED驱动的编写，编写应用程序测试-编程知识

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 PHY_LED1_ADDR 0X50006000
#define PHY_LED2_ADDR    0X50007000
#define PHY_LED3_ADDR 0X50006000
#define PHY_RCC_ADDR    0X50000A28//构建功能码
#define LED_ON _IOW('l',1,int)  
#define LED_OFF _IOW('l',0,int)
#endif

应用程序！！！

#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 a,b;int fd=open("/dev/myled0",O_RDWR);if(fd<0){printf("打开设备文件失败\n");exit(-1);}while(1){//从终端读取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("请输入要控制的灯\n");printf("1(LED1) 2(LED2) 3(LED3)\n");printf("请输入>");scanf("%d",&b);switch(a){case 1:ioctl(fd,LED_ON,&b);break;case 0:ioctl(fd,LED_OFF,&b);break;}}close(fd);return 0;
}

驱动代码！

#include <linux/init.h>
#include <linux/module.h>
#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"
char kbuf[128]="";  
struct cdev *cdev;//申请字符设备驱动对象 cdev
unsigned int major=0;//主设备号
unsigned int minor=0;//次设备号
dev_t devno;//设备号的起始值
struct class *cls;//向上提交目录
struct device *dev;//向上提交设备信息gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;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;// 向用户空间读取拷贝if (size > sizeof(kbuf)) // 用户空间期待读取的大小内核满足不了，那就给内核支持的最大大小size = sizeof(kbuf);ret = copy_to_user(ubuf, kbuf, size);if (ret) // 拷贝失败{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;// 从用户空间读取数据if (size > sizeof(kbuf)) // 用户空间期待读取的大小内核满足不了，那就给内核支持的最大大小size = sizeof(kbuf);ret = copy_from_user(kbuf, ubuf, size);if (ret) // 拷贝失败{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)//拷贝失败{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)
{//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);//led1vir_led1->MODER &= (~(3<<20));vir_led1->MODER |= (1<<20);vir_led1->ODR &= (~(1<<10));//led2vir_led2->MODER &= (~(3<<20));vir_led2->MODER |= (1<<20);vir_led2->ODR &= (~(1<<10));//led3vir_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;
}// 定义操作方法结构体变量并赋值
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;//1.申请字符设备驱动对象空间cdev=cdev_alloc();//无参函数字符设备驱动对象空间if(cdev==NULL){return -EFAULT;//根据EIO往下追，找到合适的那个返回值用}printk("字符设备驱动对象申请成功\n");//2.初始化字符设备驱动对象cdev_init(cdev,&fops);//cdev:驱动对象指针 fops:操作方法对象指针//3.申请设备号if(major==0)//动态申请{ret=alloc_chrdev_region(&devno,minor,3,"myled");if(ret){printk("动态申请设备号失败\n");goto out1;}//为了统一和静态申请设备号的操作major=MAJOR(devno);minor=MINOR(devno);}else//静态指定{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");//4.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");//5.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");//6.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;}}all_led_init();//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!注意调用led灯printk("向上提交设备信息成功\n");   return 0;out4:
//销毁提交成功的设备信息for(--i;i>=0;i--){device_destroy(cls,MKDEV(major,i));}//销毁目录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)
{//1.释放设备信息int i;for(i=0;i<3;i++){device_destroy(cls,MKDEV(major,i));}//2.销毁目录class_destroy(cls);//3.注销驱动对象cdev_del(cdev);//4.释放设备号unregister_chrdev_region(MKDEV(major,minor),3);//5.释放对象空间kfree(cdev);}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");