#include <linux/module.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <linux/io.h>
#include <linux/delay.h>

#include "gpioregs.h"

#define DEVICE_NAME "led"
#define CLASS_NAME "led_heartbeat_class"
#define led_heartbeat_MAJOR 56
#define led_heartbeat_MINOR 60


typedef enum
{
    LED_GREEN = 0,
    LED_RED = 1
} led_color_t;

static struct class *led_heartbeat_class = NULL;
static struct device *led_heartbeat_device = NULL;
static struct cdev led_heartbeat_cdev;

static int led_color  = 0;
static int led_blink_flag  = 0;
static int led_blink_speed = 0;
static unsigned char blink_count = 0;
static struct delayed_work delay_work1;

static int wait_ibf(void)
{
    int i = 0;
    while (inb(EC_CMD_PORT) & EC_IBF)
    {
        if (++i > TIMEOUT_LOOPS)
        {
            return -1;
        }
        udelay(1);
    }
    return 0;
}

static int wait_obf(void)
{
    int i = 0;
    while (!(inb(EC_CMD_PORT) & EC_OBF))
    {
        if (++i > TIMEOUT_LOOPS)
        {
            return -1;
        }
        udelay(1);
    }
    return 0;
}

static int ec_read_ram(uint8_t offset, uint8_t *data)
{
    if (wait_ibf() < 0)
        return -1;
    outb(CMD_READ_RAM, EC_CMD_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(offset, EC_DATA_PORT);

    if (wait_obf() < 0)
        return -1;
    *data = inb(EC_DATA_PORT);

    return 0;
}

static int ec_write_ram(uint8_t offset, uint8_t data)
{
    if (wait_ibf() < 0)
        return -1;
    outb(CMD_WRITE_RAM, EC_CMD_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(offset, EC_DATA_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(data, EC_DATA_PORT);

    return 0;
}

static int oem_ec_read_ram(uint8_t page, uint8_t offset, uint8_t *data)
{
    unsigned char WEC, REC;
    switch(page)
    {
        case 0:
        {
            WEC = 0x96;
            REC = 0x95;
            break;
        }
        
        case 1:
        {
            WEC = 0x98;
            REC = 0x97;
            break;
        }
        
        default:
        {
            WEC = 0x81;
            REC = 0x80;
            break;
        }
    }    
    if (wait_ibf() < 0)
        return -1;
    outb(REC, EC_CMD_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(offset, EC_DATA_PORT);

    if (wait_obf() < 0)
        return -1;
    *data = inb(EC_DATA_PORT);

    return 0;
}

static int oem_ec_write_ram(uint8_t page, uint8_t offset, uint8_t data)
{
    unsigned char WEC, REC;
    switch(page)
    {
        case 0:
        {
            WEC = 0x96;
            REC = 0x95;
            break;
        }
        
        case 1:
        {
            WEC = 0x98;
            REC = 0x97;
            break;
        }
        
        default:
        {
            WEC = 0x81;
            REC = 0x80;
            break;
        }
    }
    if (wait_ibf() < 0)
        return -1;
    outb(WEC, EC_CMD_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(offset, EC_DATA_PORT);

    if (wait_ibf() < 0)
        return -1;
    outb(data, EC_DATA_PORT);

    return 0;
}

static void heart_led_turn_on(void)
{
    oem_ec_write_ram(1, OFFSET_TURNOFF_CTL, 0x00);
}

static void heart_led_turn_off(void)
{
    oem_ec_write_ram(1, OFFSET_TURNOFF_CTL, 0x01);
}

static int led_set_color(led_color_t color)
{
    uint8_t val;
    if (ec_read_ram(OFFSET_COLOR_CTL, &val) < 0)
        return -1;

    if (color == LED_RED)
        val |= BIT0;
    else
        val &= ~BIT0;

    heart_led_turn_on();
    return ec_write_ram(OFFSET_COLOR_CTL, val);
}

static int led_set_blink(int enable, uint8_t interval_unit)
{
    uint8_t ctl;

    if (enable)
    {
        if (ec_write_ram(OFFSET_BLINK_TIME, interval_unit) < 0)
            return -1;
    }

    if (ec_read_ram(OFFSET_BLINK_CTL, &ctl) < 0)
        return -1;

    if (enable)
        ctl |= BIT0;
    else
        ctl &= ~BIT0;

    heart_led_turn_on();
    return ec_write_ram(OFFSET_BLINK_CTL, ctl);
}

static int led_heartbeat_open(struct inode *inode, struct file *filp)
{
    return 0;
}

static int led_heartbeat_release(struct inode *inode, struct file *filp)
{
    return 0;
}

static ssize_t led_heartbeat_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
    int ret = 0;
    return ret;
}

static ssize_t led_heartbeat_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos)
{
    unsigned char kbuff[3] = {0};
    if(count != sizeof(kbuff))
    {
        return -EINVAL;
    }
    if (copy_from_user(kbuff, buf, count) != 0)
    {
        return -EFAULT;
    }

    led_color = kbuff[0];
    led_blink_flag = kbuff[1];
    led_blink_speed = kbuff[2];

    if(led_color != 0x0 && led_color != 0x40 && led_color != 0x80)
    {
        return -EINVAL;
    }

    if(led_blink_flag != 0x0 && led_blink_flag != 0x1)
    {
        return -EINVAL;
    }

    if(led_color == 0x00)
    {
        // off
        heart_led_turn_off();
        return count;
    }
    else if(led_color == 0x40)
    {
        // set color to red
        led_set_color(LED_RED);
    }
    else if(led_color == 0x80)
    {
        // set color to green
        led_set_color(LED_GREEN);
    }

    // led_set_blink(led_blink_flag, kbuff[2]);
    // return count;

    // The following code is reserved because the blink cycle of EC is incorrect. If the EC cannot be changed, we have to delay the work queue.
    if(led_blink_flag)
    {
        // led_set_blink(1, led_blink_speed);
        blink_count = 0;
        schedule_delayed_work(&delay_work1, msecs_to_jiffies(1000*led_blink_speed));
    }
    return count;
}

static struct file_operations led_heartbeat_fops = {
    .owner = THIS_MODULE,
    .open = led_heartbeat_open,
    .release = led_heartbeat_release,
    .read = led_heartbeat_read,
    .write = led_heartbeat_write,
};

static void led_heartbeat_work_func(struct work_struct *work)
{

    if(led_blink_flag)
    {
        blink_count++;
        if(blink_count%2 == 0)
        {
            if(led_color == 0x40)
            {
                // set color to red
                led_set_color(LED_RED);
            }
            else if(led_color == 0x80)
            {
                // set color to green
                led_set_color(LED_GREEN);
            }
        }
        else
        {
            heart_led_turn_off();
        }
        schedule_delayed_work(&delay_work1, msecs_to_jiffies(1000*led_blink_speed));
    }
}

int led_heartbeat_init(void)
{
    dev_t dev_num;
    int ret;

    dev_num = MKDEV(led_heartbeat_MAJOR, led_heartbeat_MINOR);

    ret = register_chrdev_region(dev_num, 1, DEVICE_NAME);
    if (ret < 0) {
        pr_err("Failed_heartbeat to register device number %d:%d\n", led_heartbeat_MAJOR, led_heartbeat_MINOR);
        return ret;
    }

    cdev_init(&led_heartbeat_cdev, &led_heartbeat_fops);
    led_heartbeat_cdev.owner = THIS_MODULE;
    ret = cdev_add(&led_heartbeat_cdev, dev_num, 1);
    if (ret < 0) {
        pr_err("Failed_heartbeat to add cdev\n");
        unregister_chrdev_region(dev_num, 1);
        return ret;
    }

    led_heartbeat_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(led_heartbeat_class)) {
        pr_err("Failed_heartbeat to create class\n");
        cdev_del(&led_heartbeat_cdev);
        unregister_chrdev_region(dev_num, 1);
        return PTR_ERR(led_heartbeat_class);
    }

    led_heartbeat_device = device_create(led_heartbeat_class, NULL, dev_num, NULL, DEVICE_NAME);
    if (IS_ERR(led_heartbeat_device)) {
        pr_err("Failed_heartbeat to create device\n");
        class_destroy(led_heartbeat_class);
        cdev_del(&led_heartbeat_cdev);
        unregister_chrdev_region(dev_num, 1);
        return PTR_ERR(led_heartbeat_device);
    }

    INIT_DELAYED_WORK(&delay_work1, led_heartbeat_work_func);

    return 0;
}

void led_heartbeat_exit(void)
{
    dev_t dev_num = MKDEV(led_heartbeat_MAJOR, led_heartbeat_MINOR);
    cancel_delayed_work_sync(&delay_work1);

    device_destroy(led_heartbeat_class, dev_num);
    class_destroy(led_heartbeat_class);
    cdev_del(&led_heartbeat_cdev);
    unregister_chrdev_region(dev_num, 1);
    pr_info("led_heartbeat driver unloaded\n");
}