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 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#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;
dev_t devno;
struct cdev *cdev;
unsigned int major;
unsigned int minor;
 
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 min = (int)file->private_data;
    switch (min)
    {
    case 0: // 控制LED1
        switch (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LED2
        switch (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LED3
        switch (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);
    // 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)
{
    int ret;
    // 为字符设备驱动对象申请空间
    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("申请对象空间成功\n");
    // 初始化字符设备驱动对象
    cdev_init(cdev, &fops);
    // 申请设备号
    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);
    // 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);
    // 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, "mychrdev");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");