通过字符设备驱动分步注册方式编写LED驱动，完成设备文件和设备的绑定：

mychrdev.c:
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include "head.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;
module_param(major, uint, 0664);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 which;//获取arg对应的用户空间中到的值int ret=copy_from_user(&which,(void *)arg,4);if(ret){printk("从用户空间获取数据失败\n");return -EIO;}int min = (int)file->private_data;switch (min){case 0:switch(cmd){case LED_ON: // LED1//开灯vir_led1->ODR |= 1 << 10;break;case LED_OFF://关灯vir_led1->ODR &= (~(1 << 10));break;}case 1:switch(cmd){case LED_ON: // LED2//开灯vir_led2->ODR |= 1 << 10;break;case LED_OFF://关灯vir_led2->ODR &= (~(1 << 10));break;}case 2:switch(cmd){case LED_ON: // LED3//开灯vir_led3->ODR |= 1 << 8;break;case LED_OFF://关灯vir_led3->ODR &= (~(1 << 8));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) |= (0X3 << 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_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)
{int ret;// 字符设备驱动注册//字符设备驱动对象分配cdev = cdev_alloc();if(cdev == NULL){printk("字符设备驱动对象申请空间失败\n");ret = -EFAULT;goto out1;}printk("字符设备驱动对象申请成功\n");//字符设备驱动对象初始化cdev_init(cdev, &fops);//设备号申请if(major > 0){ret = register_chrdev_region(MKDEV(major,minor),3,"myled");if(ret){printk("静态申请设备号失败\n");goto out2;}}else 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 out2;}major = MAJOR(devno);minor = MINOR(devno);}printk("申请设备号成功\n");//注册驱动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("注册字符驱动对象成功\n");// 寄存器映射以及初始化all_led_init();// 向上提交目录cls = class_create(THIS_MODULE, "myled");if (IS_ERR(cls)){printk("向上提交目录失败\n");return -PTR_ERR(cls);goto out4;}printk("向上提交目录成功\n");// 向上提交设备节点信息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("向上提交设备节点信息失败\n");return -PTR_ERR(dev);goto out5;}}printk("向上提交设备节点信息成功\n");return 0;
out5://释放前一次提交成功的设备信息for(--i;i>=0;i--){device_destroy(cls,MKDEV(major,i));}class_destroy(cls);//释放目录
out4:cdev_del(cdev);
out3:unregister_chrdev_region(MKDEV(major,minor),3);
out2:kfree(cdev);
out1:return ret;
}static void __exit mycdev_exit(void)
{/*销毁设备节点信息*/int i;for (i = 0; i < 3; i++){device_destroy(cls, MKDEV(major, i));}// 销毁目录信息class_destroy(cls);// 取消地址映射iounmap(vir_led1);iounmap(vir_led2);iounmap(vir_rcc);// 注销字符设备驱动unregister_chrdev(major, "myled");//注销驱动对象cdev_del(cdev);//释放设备号unregister_chrdev_region(MKDEV(major,minor),3);//释放对象空间kfree(cdev);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

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//构建LED开关的功能码，添加ioctl第三个参数int
#define LED_ON _IOW('l',1,int)
#define LED_OFF _IOW('l',0,int)
#endif 

app.c:
#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;char buf[128] = {0};int fd = open("/dev/mychrdev0", 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("请输入对LED灯的控制：1(开灯)0(关灯)>");scanf("%d", &a);printf("请输入要控制的灯：1(LED1) 2(LED2) 3(LED3)>");scanf("%d",&b);switch (a){case 1:ioctl(fd, LED_ON,&b); // 开灯break;case 0:ioctl(fd, LED_OFF,&b); // 关灯}}close(fd);return 0;
}