#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/device.h>
#include <linux/stat.h>

#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/workqueue.h>

#include <linux/io.h>
#include "gpioregs.h"

#define DEVICE_NAME "ssegment"
#define CLASS_NAME "ssegment_class"
#define DRIVER_NAME     "port80_seg7"
#define BUFFER_SIZE 1024

// 可以通过模块参数指定主设备号和次设备号
static int major = 56; // 默认主设备号
static int minor = 40;   // 默认次设备号
module_param(major, int, S_IRUGO);
module_param(minor, int, S_IRUGO);
MODULE_PARM_DESC(major, "Major device number");
MODULE_PARM_DESC(minor, "Minor device number");

static struct class *char_class = NULL;
static struct device *char_device = NULL;
static struct cdev my_cdev;
static dev_t dev_num;

// 设备结构体
struct ssegment_dev
{
    char *buffer;
    size_t size;
    struct mutex lock;
    struct cdev cdev;
    struct delayed_work delay_work1;
};

static struct ssegment_dev *dev = NULL;


unsigned int readl_cust(unsigned int addr)
{
    void __iomem *reg_base;
    reg_base = ioremap(addr, 0x1000);
    return readl(reg_base);
}

int writel_cust(unsigned int addr, unsigned int val)
{
    void __iomem *reg_base;
    reg_base = ioremap(addr, 0x1000);
    writel(val, reg_base);
    return 0;
}

static void delay_work_func(struct work_struct *work)
{
    int ret = 0;
    unsigned int val = 0;
    if(dev->size != 0)
    {
        // 写数据
        outb(dev->buffer[0], PORT_80);
        if((dev->buffer[1] & 0x02))
        {
            val = readl_cust(SSEGMENT_POINT);
            val = val | 0x01;
            ret = writel_cust(SSEGMENT_POINT, val);
            // 显示小数点 待提供接口
            // 待实现
        }
        else
        {
            val = readl_cust(SSEGMENT_POINT);
            val = val & 0xFFFFFFFE;
            ret = writel_cust(SSEGMENT_POINT, val);
            // 不显示小数点
        }

        if((dev->buffer[1] & 0x80))
        {
            // 闪烁 LED
        }
        else
        {
            // 不闪烁 LED
        }
    }


    
    printk(KERN_INFO "delay_work_func\n");
}

// 文件打开操作
static int ssegment_open(struct inode *inode, struct file *filp)
{
    struct ssegment_dev *dev;

    // if (!request_region(PORT_80, 1, DRIVER_NAME))
    // {
    //     pr_err("Port 80 I/O region busy\n");
    //     return -EBUSY;
    // }

    dev = container_of(inode->i_cdev, struct ssegment_dev, cdev);
    filp->private_data = dev;

    printk(KERN_INFO "ssegment: Device opened (major=%d, minor=%d)\n",
           imajor(inode), iminor(inode));
    return 0;
}

// 文件释放操作
static int ssegment_release(struct inode *inode, struct file *filp)
{
    // release_region(PORT_80, 1);
    printk(KERN_INFO "ssegment: Device closed\n");
    return 0;
}

// 读操作 - 支持cat命令
static ssize_t ssegment_read(struct file *filp, char __user *buf,
                             size_t count, loff_t *f_pos)
{
    struct ssegment_dev *dev = filp->private_data;
    ssize_t retval = 0;
    size_t available;
    int read_count = 0;
    int ret = 0;

    if (mutex_lock_interruptible(&dev->lock))
        return -ERESTARTSYS;

    // 这里read_count没有固定为4个字节，是为了便于后续扩展
    if (count > dev->size)
    {
        read_count = dev->size;
    }
    else
    {
        read_count = count;
    }
    ret = copy_to_user(buf, dev->buffer, read_count);
    if (ret != 0)
    {
        printk(KERN_INFO "ssegment: copy_to_user failed\n");
        goto out;
    }

    printk(KERN_INFO "ssegment: Read %zu bytes\n", count);

out:
    mutex_unlock(&dev->lock);
    return ret;
}

// 写操作
static ssize_t ssegment_write(struct file *filp, const char __user *buf,
                              size_t count, loff_t *f_pos)
{
    struct ssegment_dev *dev = filp->private_data;
    ssize_t retval = 0;
    size_t available;
    int ret = 0;

    // 加锁
    if (mutex_lock_interruptible(&dev->lock))
    {
        return -ERESTARTSYS;
    }

    // 计算可写数据量
    if (count > BUFFER_SIZE)
    {
        count = BUFFER_SIZE;
    }

    // 拷贝数据
    ret = copy_from_user(dev->buffer, buf, count);
    if (ret != 0)
    {
        printk(KERN_INFO "ssegment: copy_from_user failed\n");
        goto out;
    }

    dev->size = count;

    printk(KERN_INFO "ssegment: Written %zu bytes\n", count);

out:
    mutex_unlock(&dev->lock);

    // 调度延迟工作
    if (ret == 0)
    {
        schedule_delayed_work(&dev->delay_work1, msecs_to_jiffies(10));
    }
    return count;
}

// 文件操作结构体
static struct file_operations fops = {
    .owner = THIS_MODULE,
    .open = ssegment_open,
    .release = ssegment_release,
    .read = ssegment_read,
    .write = ssegment_write,
};

// 模块初始化
int ssegment_init(void)
{
    int result;

    printk(KERN_INFO "ssegment: Initializing driver with major=%d, minor=%d\n",
           major, minor);

    // 检查主设备号是否有效
    if (major <= 0)
    {
        printk(KERN_ALERT "ssegment: Invalid major number %d\n", major);
        return -EINVAL;
    }

    // 构建设备号
    dev_num = MKDEV(major, minor);

    // 注册设备号 - 使用指定的主设备号
    result = register_chrdev_region(dev_num, 1, DEVICE_NAME);
    if (result < 0)
    {
        printk(KERN_ALERT "ssegment: Failed to register major number %d\n", major);
        printk(KERN_ALERT "ssegment: Try using a different major number\n");
        return result;
    }

    printk(KERN_INFO "ssegment: Registered with major=%d, minor=%d\n",
           MAJOR(dev_num), MINOR(dev_num));

    // 分配设备结构体
    dev = kmalloc(sizeof(struct ssegment_dev), GFP_KERNEL);
    if (!dev)
    {
        result = -ENOMEM;
        goto fail_malloc;
    }
    memset(dev, 0, sizeof(struct ssegment_dev));

    // 分配缓冲区
    dev->buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
    if (!dev->buffer)
    {
        result = -ENOMEM;
        goto fail_buffer;
    }

    // 初始化互斥锁
    mutex_init(&dev->lock);

    INIT_DELAYED_WORK(&dev->delay_work1, delay_work_func);

    // 初始化字符设备
    cdev_init(&dev->cdev, &fops);
    dev->cdev.owner = THIS_MODULE;

    // 添加字符设备到系统
    result = cdev_add(&dev->cdev, dev_num, 1);
    if (result)
    {
        printk(KERN_ALERT "ssegment: Failed to add cdev\n");
        goto fail_cdev;
    }

    // 创建设备类
    char_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(char_class))
    {
        result = PTR_ERR(char_class);
        printk(KERN_ALERT "ssegment: Failed to create class\n");
        goto fail_class;
    }

    // 创建设备
    char_device = device_create(char_class, NULL, dev_num, NULL, DEVICE_NAME);
    if (IS_ERR(char_device))
    {
        result = PTR_ERR(char_device);
        printk(KERN_ALERT "ssegment: Failed to create device\n");
        goto fail_device;
    }

    printk(KERN_INFO "ssegment: Driver initialized successfully\n");
    printk(KERN_INFO "ssegment: Device node: /dev/%s (major=%d, minor=%d)\n",
           DEVICE_NAME, major, minor);
    return 0;

fail_device:
    class_destroy(char_class);
fail_class:
    cdev_del(&dev->cdev);
fail_cdev:
    kfree(dev->buffer);
fail_buffer:
    kfree(dev);
fail_malloc:
    unregister_chrdev_region(dev_num, 1);
    return result;
}

// 模块退出
void ssegment_exit(void)
{
    cancel_delayed_work_sync(&dev->delay_work1);
    device_destroy(char_class, dev_num);
    class_destroy(char_class);

    if (dev)
    {
        cdev_del(&dev->cdev);
        if (dev->buffer)
            kfree(dev->buffer);
        kfree(dev);
    }

    unregister_chrdev_region(dev_num, 1);
    printk(KERN_INFO "ssegment: Driver removed (major=%d, minor=%d)\n",
           major, minor);
}