【驱动开发】LED灯的亮灭——通过字符设备驱动的分步实现编写LED驱动，实现设备文件和设备的绑定

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;

//LED灯的寄存器地址
#define LED1_ADDR 0X50006000
#define LED2_ADDR 0X50007000
#define LED3_ADDR 0X50006000
#define RCC_ADDR 0X50000A28

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

#endif

驱动程序：

#include 
#include 
#include 
#include 
#include 
#include "head.h"
#include 
#include 
#include 

struct cdev *cdev = NULL;
unsigned major = 0;
unsigned minor = 0;
module_param(major, uint, 0664);
dev_t devno;
char kbuf[128] = {0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
// 定义指针指向映射后的虚拟内存
unsigned int *vir_rcc;
struct class *cls;
struct device *dev;

// 封装操作方法
int mycdev_open(struct inode *inode, struct file *file)
{
    // 设备文件和设备绑定
    // 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)

{
    int min = (int)file->private_data;
    switch (min)
    {
    case 0: // 控制LED1
        switch (cmd)
        {
        case LED_ON: // 开灯
            vir_led1->ODR |= (0x1 << 10);
            break;
        case LED_OFF: // 关灯
            vir_led1->ODR &= (~(0x1 << 10));
            break;
        }
        break;

    case 1: // 控制LED2
        switch (cmd)
        {
        case LED_ON: // 开灯
            vir_led2->ODR |= (0x1 << 10);
            break;
        case LED_OFF: // 关灯
            vir_led2->ODR &= (~(0x1 << 10));
            break;
        }
        break;

    case 2: // 控制LED3
        switch (cmd)
        {
        case LED_ON: // 开灯
            vir_led3->ODR |= (0x1 << 8);
            break;
        case LED_OFF: // 关灯
            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(LED1_ADDR, sizeof(gpio_t));
    if (vir_led1 == NULL)
    {
        printk("ioremap filed：%d\n", __LINE__);
        return -ENOMEM;
    }
    vir_led2 = ioremap(LED2_ADDR, sizeof(gpio_t));
    if (vir_led2 == NULL)
    {
        printk("ioremap filed：%d\n", __LINE__);
        return -ENOMEM;
    }
    vir_led3 = vir_led1;
    vir_rcc = ioremap(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 (cdev == NULL)
    {
        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_init
    cdev_init(cdev, &fops);

    // 3.申请设备号  register_chrdev_region()/alloc_chrdev_region()
    if (major == 0) // 动态申请
    {
        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
    {
        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");

    // 相关寄存器地址映射及初始化
    all_led_init();

    // 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");
    return 0;
out5:
    // 将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)
{
    // 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);

    // 取消物理内存的映射
    iounmap(vir_led1);
    iounmap(vir_led2);
    iounmap(vir_rcc);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用程序： 

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "head.h"
#include 
int main(int argc, char const *argv[])
{
    int a;
    char buf[128] = {0};
    int fd = open("/dev/mycdev0", O_RDWR);
    if (fd < 0)
    {
        printf("打开设备文件失败\n");
        return -1;
    }
    printf("打开设备文件成功\n");
    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);
        getchar();
        switch (a)
        {
        case 1:
            ioctl(fd, LED_ON); // 第三个参数为指针
            break;
        case 0:
            ioctl(fd, LED_OFF);
            break;
        }
    }
    close(fd);
    return 0;
}