#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 4

#define GPIO1_CTL 0xFD6D0B50
#define GPIO1_STATUS 0xFD6D0940

#define GPIO0_CTL 0xFD6D0B60
#define GPIO0_STATUS 0xFD6D0950

struct cashd_device {
    unsigned char *buffer;
    size_t buffer_size;
    wait_queue_head_t read_wait;
    struct mutex lock;
    struct cdev cdev;
    int dev_major;
    int dev_minor;
    unsigned int in_status;
    unsigned int status_changed;
    int last_status;
    int first_read;
    struct delayed_work delay_work1;
    struct delayed_work delay_work2;
    void __iomem *gpio_ctl_reg_base;
    void __iomem *gpio_status_reg_base;
    int count; // debug code
};

static int cashd_major = 0;
static struct class *cashd_class = NULL;
static struct cashd_device *cashd_devices[MINOR_COUNT];
static unsigned int minors[MINOR_COUNT] = {10, 11};

static void gpio_ctl_delay_work_func(struct work_struct *work)
{
    unsigned int value = 0;
    struct delayed_work *dwork = to_delayed_work(work);
    struct cashd_device *dev = container_of(dwork, struct cashd_device, delay_work1);

    value = readl(dev->gpio_ctl_reg_base);
    value &= 0xfffffffe;
    writel(value, dev->gpio_ctl_reg_base);
}

static void gpio_status_delay_work_func(struct work_struct *work)
{
    unsigned int value = 0;
    struct delayed_work *dwork = to_delayed_work(work);
    struct cashd_device *dev = container_of(dwork, struct cashd_device, delay_work2);

    value = readl(dev->gpio_status_reg_base);
    value = value & 0x2;
    if(value != dev->last_status)
    {
        dev->last_status = value;
        dev->status_changed = 1;
        wake_up_interruptible(&dev->read_wait);
    }

    // debug code
    // dev->count++;
    // if(dev->count >= 50)
    // {
    //     dev->count = 0;
    //     dev->status_changed = 1;
    //     printk("%s %s %d\n", __FILE__, __func__, __LINE__);
    //     wake_up_interruptible(&dev->read_wait);
    // }
    schedule_delayed_work(&dev->delay_work2, msecs_to_jiffies(100));
}

static int cashd_open(struct inode *inode, struct file *filp)
{
    struct cashd_device *dev = NULL;
    unsigned int minor = iminor(inode);
    int i = 0;
    for(i = 0; i < MINOR_COUNT; i++)
    {
        if(minor == minors[i])
        {
            dev = cashd_devices[i];
            break;
        }
    }
    
    if (!dev) {
        pr_err("cashd: Device not initialized for minor %d\n", minor);
        return -ENODEV;
    }

    filp->private_data = dev;
    dev->first_read = 0;
    pr_info("cashd: Device /dev/cashd%d opened\n", minor);
    
    return 0;
}

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;
}

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;
    int ret = 0;
    int nonblock = filp->f_flags & O_NONBLOCK;

    if (!dev)
        return -EINVAL;
    
    if (!buf || count == 0)
        return -EINVAL;
    if(dev->first_read == 0)
    {
        dev->first_read = 1;
    }
    else if (wait_event_interruptible(dev->read_wait, dev->status_changed))
    {
            // 被信号中断
            printk(KERN_INFO "gpio_monitor: wait interrupted by signal\n");
            return -ERESTARTSYS;
    }
    dev->in_status = readl(dev->gpio_status_reg_base);

    if(dev->in_status & 0x2)
    {
        ret = copy_to_user(buf, "o", 1);
        if(ret != 0)
        {
            return -EFAULT;
        }
    }
    else
    {
        ret = copy_to_user(buf, "c", 1);
        if(ret != 0)
        {
            return -EFAULT;
        }
    }

    dev->status_changed = 0;

    bytes_read = 1;
    
    return bytes_read;
}

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;
    int ret;
    unsigned int value = 0;
    
    if (!dev)
        return -EINVAL;
    
    if(count > BUFFER_SIZE)
    {
        count = BUFFER_SIZE;
    }
    ret = copy_from_user(dev->buffer, buf, count);
    if(ret != 0)
    {
        return -EFAULT;
    }
    if(dev->buffer[0] == 'o' || dev->buffer[0] == 'O')
    {
        // printk("%s %s %d minor=%d\n", __FILE__, __func__, __LINE__, dev->dev_minor);

        value = readl(dev->gpio_ctl_reg_base);
        value |= 0x1;
        writel(value, dev->gpio_ctl_reg_base);
        schedule_delayed_work(&dev->delay_work1, msecs_to_jiffies(300));
    }
    else
    {
        printk(KERN_INFO "cashd: Invalid input\n");
    }
    return count;
}

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;
    
    poll_wait(filp, &dev->read_wait, wait);
    
    mutex_lock(&dev->lock);
    if(dev->status_changed)
        mask |= POLLIN | POLLRDNORM;
    
    mutex_unlock(&dev->lock);
    
    return mask;
}

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,
};

static int __init cashd_init_device(struct cashd_device *dev, int minor)
{
    int ret;
    
    dev->buffer = kmalloc(BUFFER_SIZE, GFP_KERNEL);
    if (!dev->buffer) {
        pr_err("cashd: Failed to allocate buffer for minor %d\n", minor);
        return -ENOMEM;
    }
    
    memset(dev->buffer, 0, BUFFER_SIZE);
    dev->buffer_size = BUFFER_SIZE;
    dev->dev_major = cashd_major;
    dev->dev_minor = minor;
    dev->last_status = -1;
    
    init_waitqueue_head(&dev->read_wait);
    
    mutex_init(&dev->lock);
    INIT_DELAYED_WORK(&dev->delay_work1, gpio_ctl_delay_work_func);
    INIT_DELAYED_WORK(&dev->delay_work2, gpio_status_delay_work_func);
    
    cdev_init(&dev->cdev, &cashd_fops);
    dev->cdev.owner = THIS_MODULE;
    
    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;
}

static char *my_devnode(struct device *dev, umode_t *mode) {
    if (mode) {
        *mode = 0666;
    }
    return NULL;
}

int cashd_init(void)
{
    int ret;
    int i;
    struct device *device;
    cashd_major = 56;

    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;
    }
	cashd_class->devnode = my_devnode;
    
    for (i = 0; i < MINOR_COUNT; i++) {
        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;
        }
        
        ret = cashd_init_device(cashd_devices[i], minors[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;
        }
        
        device = device_create(cashd_class, NULL, 
                               MKDEV(cashd_major, minors[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;
        }

        if(i == 0)
        {
            cashd_devices[i]->gpio_ctl_reg_base = ioremap(GPIO0_CTL, 4);
            cashd_devices[i]->gpio_status_reg_base = ioremap(GPIO0_STATUS, 4);
        }
        else if(i == 1)
        {
            cashd_devices[i]->gpio_ctl_reg_base = ioremap(GPIO1_CTL, 4);
            cashd_devices[i]->gpio_status_reg_base = ioremap(GPIO1_STATUS, 4);            
        }
        schedule_delayed_work(&cashd_devices[i]->delay_work2, msecs_to_jiffies(100));
        
        pr_info("cashd: Created /dev/cashd%d\n", i);
    }
    
    
    pr_info("cashd: Driver initialized successfully\n");
    return 0;

fail_devices:
    for (i = 0; i < MINOR_COUNT; i++) {
        if (cashd_devices[i]) {
            device_destroy(cashd_class, MKDEV(cashd_major, minors[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;
}

void cashd_exit(void)
{
    int i;
    
    pr_info("cashd: Cleaning up driver\n");
    
    for (i = 0; i < MINOR_COUNT; i++) {
        if (cashd_devices[i]) {
            cancel_delayed_work_sync(&cashd_devices[i]->delay_work1);
            cancel_delayed_work_sync(&cashd_devices[i]->delay_work2);
            device_destroy(cashd_class, MKDEV(cashd_major, minors[i]));
            
            cdev_del(&cashd_devices[i]->cdev);
            
            if (cashd_devices[i]->buffer)
                kfree(cashd_devices[i]->buffer);
            iounmap(cashd_devices[i]->gpio_ctl_reg_base);
            iounmap(cashd_devices[i]->gpio_status_reg_base);
            kfree(cashd_devices[i]);
            
            pr_info("cashd: Removed /dev/cashd%d\n", i);
        }
    }
    
    if (cashd_class)
        class_destroy(cashd_class);
    
    unregister_chrdev_region(MKDEV(cashd_major, MINOR_BASE), MINOR_COUNT);
    
    pr_info("cashd: Driver cleaned up\n");
}