驱动开发4 使用字符设备驱动的分步实现编写LED驱动（LED亮灯）

一、思维导图

二、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

应用程序 test.c

#include<stdlib.h>
#include<stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include<unistd.h>
#include<string.h>
#include "head.h"int main(int argc, char const *argv[])
{char buf[128]={0};int a;int fd=open("/dev/mycdev0",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 ");printf("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;
}

头文件 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
// 构建开灯关灯的功能码
#define LED_ON _IO('l', 1)
#define LED_OFF _IO('l', 0)
#endif

驱动程序 mycdev.c

#include <linux/init.h>
#include <linux/module.h>
#include<linux/fs.h>
#include<linux/device.h>
#include<linux/cdev.h>
#include<linux/slab.h>
#include<linux/io.h>
#include<linux/uaccess.h>
#include "head.h"struct cdev *cdev;
unsigned int major=0;
unsigned int minor=0;
dev_t devno;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;int mycdev_open(struct inode *inode, struct file *file)
{//获取打开的文件的次设备号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)
{//获取文件的次设备号int min = (int)file->private_data;switch (min){case 0: // 开灯switch (cmd){case LED_ON: // LED1vir_led1->ODR |= (0X1 << 10); //LED开break;case LED_OFF:vir_led1->ODR &= (~(0X1 << 10));break;}break;case 1: // 关灯switch (cmd){case LED_ON: // LED1vir_led2->ODR |= (0X1 << 10);break;case LED_OFF:vir_led2->ODR &= (~(0X1 << 10));break;}break;case 2:switch (cmd){case LED_ON: // LED1vir_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);// 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)
{//1.申请一个对象空间cdev_allocint ret;cdev = cdev_alloc();if (NULL == cdev){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_inicdev_init(cdev,&fops);//3.申请设备号register_chrdev_region()/alloc_chrdev_region()if(0 == major){ret = alloc_chrdev_region(&devno,minor,3,"mychrdev");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 //静态制定设备号{ret=register_chrdev_region(MKDEV(major,minor),3,"mychrdev");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_addret = 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_createcls = class_create(THIS_MODULE,"mychrdev");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_createint 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://奖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");

Makefile

modname ?= demo
arch ?= arm
ifeq ($(arch),arm)  #通过命令行传过来的架构决定怎么编译
#KERBELDIR保存开发板内核源码路径
KERNELDIR := /home/ubuntu/FSMP1A/linux-stm32mp-5.10.61-stm32mp-r2-r0/linux-5.10.61
else
#保存UBUNTU内核源码路径
KERNELDIR := /lib/modules/$(shell uname -r)/build
endif#PWD保存当前内核模块的路径
PWD := $(shell pwd)
all:
#make modules是模块化编译命令
#make -C $(KERNLEDIR) 执行make之前先切换到KERNELDIR对应的路径
#M=$(PWD)表示进行模块化编译的路径是PWD保存的路径make -C $(KERNELDIR) M=$(PWD) modules
clean:
#编译清除make -C $(KERNELDIR) M=$(PWD) clean
#将obj-m保存的文件单独链接为内核模块
obj-m :=  $(modname).o