// cashd.c - 双节点字符设备驱动
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/poll.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/io.h>

#define DEVICE_NAME "cashd"
#define CLASS_NAME "cashd_class"
#define MINOR_BASE 0
#define MINOR_COUNT 2
#define BUFFER_SIZE PAGE_SIZE

#define GPIO0_CTL 0xFD6D0B50
#define GPIO0_STATUS 0xFD6D0940

#define GPIO1_CTL 0xFD6D0B60
#define GPIO1_STATUS 0xFD6D0950

// 每个设备节点的私有数据结构
struct cashd_device {
    unsigned char *buffer;
    size_t data_size;
    size_t buffer_size;
    wait_queue_head_t read_wait;
    wait_queue_head_t write_wait;
    struct mutex lock;
    struct cdev cdev;
    int dev_major;
    int dev_minor;
    bool can_read;
    bool can_write;
    unsigned int ctl_status;
    unsigned int in_status;
};

static int cashd_major = 0;
static struct class *cashd_class = NULL;
static struct cashd_device *cashd_devices[MINOR_COUNT];

// 文件打开操作
static int cashd_open(struct inode *inode, struct file *filp)
{
    struct cashd_device *dev;
    unsigned int minor = iminor(inode);
    
    if (minor >= MINOR_COUNT) {
        pr_err("cashd: Invalid minor number %d\n", minor);
        return -ENODEV;
    }
    
    dev = cashd_devices[minor];
    if (!dev) {
        pr_err("cashd: Device not initialized for minor %d\n", minor);
        return -ENODEV;
    }
    
    // 将私有数据保存在file结构中
    filp->private_data = dev;
    pr_info("cashd: Device /dev/cashd%d opened\n", minor);
    
    return 0;
}

// 文件释放操作
static int cashd_release(struct inode *inode, struct file *filp)
{
    unsigned int minor = iminor(inode);
    pr_info("cashd: Device /dev/cashd%d closed\n", minor);
    return 0;
}

// 读操作
static ssize_t cashd_read(struct file *filp, char __user *buf, 
                          size_t count, loff_t *f_pos)
{
    struct cashd_device *dev = filp->private_data;
    ssize_t bytes_read = 0;
    size_t available;
    int ret;

    void __iomem *reg_base;

    if(*f_pos > 0)
        return 0;
    
    
    if (!dev)
        return -EINVAL;
    
    if (!buf || count == 0)
        return -EINVAL;
    
    if(dev->dev_minor == 0)
    {
        reg_base = ioremap(GPIO0_STATUS, 0x1000);
        dev->in_status = readl(reg_base);
        printk(KERN_INFO "cashd: GPIO0 Status: 0x%x\n", dev->in_status);
    }
    else if(dev->dev_minor == 1)
    {
        reg_base = ioremap(GPIO1_STATUS, 0x1000);
        dev->in_status = readl(reg_base);
        printk(KERN_INFO "cashd: GPIO1 Status: 0x%x\n", dev->in_status);
    }

    if(dev->in_status & 0x1)
    {
        copy_to_user(buf, "o", 1);
    }
    else
    {
        copy_to_user(buf, "c", 1);
    }

    bytes_read = 1;
    *f_pos += bytes_read;
    
    return bytes_read;
}

// 写操作
static ssize_t cashd_write(struct file *filp, const char __user *buf,
                           size_t count, loff_t *f_pos)
{
    struct cashd_device *dev = filp->private_data;
    ssize_t bytes_written = 0;
    size_t space;
    int ret;
    unsigned int value = 0;
    void __iomem *reg_base;
    
    if (!dev)
        return -EINVAL;
    
    if(count > BUFFER_SIZE)
    {
        count = BUFFER_SIZE;
    }
    ret = copy_from_user(dev->buffer, buf, count);
    if(dev->buffer[0] == 'o' || dev->buffer[0] == 'O')
    {
        if(dev->dev_minor == 0)
        {
            reg_base = ioremap(GPIO0_CTL, 0x1000);
        }
        else if(dev->dev_minor == 1)
        {
            reg_base = ioremap(GPIO1_CTL, 0x1000);
        }
        value = readl(reg_base);
        value |= 0x1;
        writel(value, reg_base);
    }
    else
    {
        printk(KERN_INFO "cashd: Invalid input\n");
    }
    return count;
}

// poll操作 - 支持select/poll/epoll
static unsigned int cashd_poll(struct file *filp, poll_table *wait)
{
    struct cashd_device *dev = filp->private_data;
    unsigned int mask = 0;
    
    if (!dev)
        return POLLERR;
    
    // 添加等待队列
    poll_wait(filp, &dev->read_wait, wait);
    // poll_wait(filp, &dev->write_wait, wait);
    
    mutex_lock(&dev->lock);
    
    // 可读条件：缓冲区有数据
    if (dev->data_size > 0)
        mask |= POLLIN | POLLRDNORM;
    
    // // 可写条件：缓冲区有空间
    // if (dev->data_size < dev->buffer_size)
    //     mask |= POLLOUT | POLLWRNORM;
    
    mutex_unlock(&dev->lock);
    
    return mask;
}

// 文件操作结构体
static const struct file_operations cashd_fops = {
    .owner = THIS_MODULE,
    .open = cashd_open,
    .release = cashd_release,
    .read = cashd_read,
    .write = cashd_write,
    // .poll = cashd_poll,
};

// 初始化设备
static int __init cashd_init_device(struct cashd_device *dev, int minor)
{
    int ret;
    
    // 分配缓冲区
    dev->buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
    if (!dev->buffer) {
        pr_err("cashd: Failed to allocate buffer for minor %d\n", minor);
        return -ENOMEM;
    }
    
    // 初始化字段
    memset(dev->buffer, 0, BUFFER_SIZE);
    dev->data_size = 0;
    dev->buffer_size = BUFFER_SIZE;
    dev->dev_major = cashd_major;
    dev->dev_minor = minor;
    dev->can_read = false;
    dev->can_write = true;
    
    // 初始化等待队列
    init_waitqueue_head(&dev->read_wait);
    init_waitqueue_head(&dev->write_wait);
    
    // 初始化互斥锁
    mutex_init(&dev->lock);
    
    // 初始化cdev
    cdev_init(&dev->cdev, &cashd_fops);
    dev->cdev.owner = THIS_MODULE;
    
    // 添加字符设备到系统
    ret = cdev_add(&dev->cdev, MKDEV(cashd_major, minor), 1);
    if (ret) {
        pr_err("cashd: Failed to add cdev for minor %d\n", minor);
        kfree(dev->buffer);
        return ret;
    }
    
    return 0;
}

// 模块初始化
int cashd_init(void)
{
    int ret;
    int i;
    dev_t dev_num;
    struct device *device;
    
    pr_info("cashd: Initializing driver\n");
    
    // 动态分配主设备号
    ret = alloc_chrdev_region(&dev_num, MINOR_BASE, MINOR_COUNT, DEVICE_NAME);
    if (ret < 0) {
        pr_err("cashd: Failed to allocate device numbers\n");
        return ret;
    }
    
    cashd_major = MAJOR(dev_num);
    pr_info("cashd: Allocated major number %d\n", cashd_major);
    
    // 创建设备类
    cashd_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(cashd_class)) {
        ret = PTR_ERR(cashd_class);
        pr_err("cashd: Failed to create class\n");
        goto fail_class;
    }
    
    // 为每个次设备号创建设备
    for (i = 0; i < MINOR_COUNT; i++) {
        // 分配设备结构体
        cashd_devices[i] = kzalloc(sizeof(struct cashd_device), GFP_KERNEL);
        if (!cashd_devices[i]) {
            pr_err("cashd: Failed to allocate device for minor %d\n", i);
            ret = -ENOMEM;
            goto fail_devices;
        }
        
        // 初始化设备
        ret = cashd_init_device(cashd_devices[i], i);
        if (ret) {
            pr_err("cashd: Failed to init device for minor %d\n", i);
            kfree(cashd_devices[i]);
            cashd_devices[i] = NULL;
            goto fail_devices;
        }
        
        // 创建设备节点
        device = device_create(cashd_class, NULL, 
                               MKDEV(cashd_major, i), NULL,
                               "cashd%d", i);
        if (IS_ERR(device)) {
            ret = PTR_ERR(device);
            pr_err("cashd: Failed to create device for minor %d\n", i);
            cdev_del(&cashd_devices[i]->cdev);
            kfree(cashd_devices[i]);
            cashd_devices[i] = NULL;
            goto fail_devices;
        }
        
        pr_info("cashd: Created /dev/cashd%d\n", i);
    }
    
    pr_info("cashd: Driver initialized successfully\n");
    return 0;

fail_devices:
    // 清理已初始化的设备
    for (i = 0; i < MINOR_COUNT; i++) {
        if (cashd_devices[i]) {
            device_destroy(cashd_class, MKDEV(cashd_major, i));
            cdev_del(&cashd_devices[i]->cdev);
            if (cashd_devices[i]->buffer)
                kfree(cashd_devices[i]->buffer);
            kfree(cashd_devices[i]);
        }
    }
    class_destroy(cashd_class);

fail_class:
    unregister_chrdev_region(MKDEV(cashd_major, MINOR_BASE), MINOR_COUNT);
    return ret;
}

// 模块清理
void cashd_exit(void)
{
    int i;
    
    pr_info("cashd: Cleaning up driver\n");
    
    // 销毁设备和释放资源
    for (i = 0; i < MINOR_COUNT; i++) {
        if (cashd_devices[i]) {
            // 销毁设备节点
            device_destroy(cashd_class, MKDEV(cashd_major, i));
            
            // 删除字符设备
            cdev_del(&cashd_devices[i]->cdev);
            
            // 释放缓冲区
            if (cashd_devices[i]->buffer)
                kfree(cashd_devices[i]->buffer);
            
            // 释放设备结构体
            kfree(cashd_devices[i]);
            
            pr_info("cashd: Removed /dev/cashd%d\n", i);
        }
    }
    
    // 销毁设备类
    if (cashd_class)
        class_destroy(cashd_class);
    
    // 注销设备号
    unregister_chrdev_region(MKDEV(cashd_major, MINOR_BASE), MINOR_COUNT);
    
    pr_info("cashd: Driver cleaned up\n");
}