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

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)_第1张图片

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)_第2张图片

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
#include
#include 
#include 
#include 
#include 
#include
#include
#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 
#include 
#include
#include
#include
#include
#include
#include
#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: // LED1
            vir_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: // LED1
            vir_led2->ODR |= (0X1 << 10);
            break;
        case LED_OFF:
            vir_led2->ODR &= (~(0X1 << 10));
            break;
        }
        break;
    case 2:
        switch (cmd)
        {
        case LED_ON: // LED1
            vir_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);
    // 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_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_alloc
    int 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_ini
    cdev_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_add
    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");

    //5.向上提交目录 class_create
    cls = 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_create
    int 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

效果实现

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)_第3张图片

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