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：

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，不添加ioctl第三个参数
#define  LED_ON _IO('l',1)
#define  LED_OFF _IO('l',0)
#endif 

Makefile:

modname?=mychrdev
arch?=armifeq ($(arch),arm)
KERNELDIR:=/home/ubuntu/FSMP1A/linux-stm32mp-5.10.61-stm32mp-r2-r0/linux-5.10.61 #用于编译生成ARM架构的模块
else
KERNELDIR :=/lib/modules/$(shell uname -r )/build #用于生产x86架构的模块
endif#定义变量保存模块化编译的文件路径
PWD:=$(shell pwd)all:#M=$(PWD)指定模块化编译的路径make -C $(KERNELDIR) M=$(PWD) modules
clean: #编译清除make -C $(KERNELDIR) M=$(PWD) cleanobj-m:=$(modname).o #指定将demo.o独立连接生产内核模块文件

LED.c:

#include <linux/init.h>
#include <linux/module.h>
#include<linux/fs.h>
#include<linux/io.h>
#include<linux/device.h>
#include<linux/uaccess.h>
#include<linux/slab.h>
#include"head.h"
struct cdev *cdev;
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
char kbuf[128]={0};
unsigned int major=0;
unsigned int minor=0;
dev_t devno;
module_param(major,uint,0664); //方便在命令行传递major值
struct class *cls;
struct device *dev;int mycdev_open(struct inode *inode, struct file *file)
{int min=MINOR(inode->i_rdev); //根据打开的文件对应的设备号获取次设备号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:  //控制LED1switch(cmd){case LED_ON://开灯vir_led1->ODR |= 1 << 10;break;case LED_OFF://关灯vir_led1->ODR &= (~(1 << 10));break;}break;case 1:  //控制LED2switch(cmd){case LED_ON://开灯vir_led2->ODR |= 1 << 10;break;case LED_OFF://关灯vir_led2->ODR &= (~(1 << 10));break;                                }break;case 2:  //控制LED3switch(cmd){case LED_ON://开灯vir_led3->ODR |= 1 << 8;break;case LED_OFF://关灯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;
}//定义一个操作方法结构体对象并且初始化
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_led3->MODER |= (1 << 16);vir_led3->ODR &= (~(1 << 8));printk("寄存器初始化成功\n");return 0;
}static int __init mycdev_init(void)
{int ret;cdev = cdev_alloc(); //申请一个字符设备驱动对象空间if(cdev==NULL){printk("字符设备驱动对象申请空间失败\n");ret = -EFAULT;goto out1;}printk("申请对象空间成功\n");cdev_init(cdev, &fops); //字符设备驱动对象初始化if(major>0) //静态指定设备号{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) //动态申请设备号{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); //获取主设备号minor=MINOR(devno); //获取次设备号}printk("申请设备号成功\n");//注册字符设备驱动对象 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");//向上提交目录信息cls=class_create(THIS_MODULE,"myled");if(IS_ERR(cls)){printk("向上提交目录失败\n");ret=-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");ret=-PTR_ERR(dev);goto out5;}}printk("向上提交设备信息成功\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)
{//释放节点信息int i;for(i=0;i<3;i++){device_destroy(cls,MKDEV(major,i));}//销毁目录class_destroy(cls);//取消地址映射iounmap(vir_led1);iounmap(vir_led2);iounmap(vir_rcc);//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");