/*
 * dht.c - driver for DHT11 Test
 *
 * Copyright (C) 2012 Loongson Corporation
 *
 * 2013-5-29
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/miscdevice.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/rcupdate.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/completion.h>
#include <asm/io.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <asm/uaccess.h>
#include <linux/gpio.h>
#include <linux/time.h>

#define GPIODHT   5
unsigned char str[5];
unsigned char send[4];
unsigned char temp;
unsigned char data;
unsigned char result;
int flag=10000;

static int dht_sensor_open(struct inode *inode, struct file *file) 
{
	printk(KERN_ALERT"########DHT11 sensor open succesful#############\n");
	gpio_request(GPIODHT,"DHT11");
//	gpio_direction_input(GPIOECHO);
	gpio_direction_output(GPIODHT,1);
	return 0;
}

static int dht_sensor_close(struct inode *inode, struct file *file)
{
	gpio_free(GPIODHT);
	printk(KERN_ALERT"########DHT11 sensor close succesful###########\n");
	return 0;
}

static ssize_t dht_sensor_read(struct file *file, char __user *buf, size_t count, loff_t *ptr)
{
/*
	unsigned int count=size;
	if(copy_to_user(buf,(void*)(dht),count));
	{
		return -EFAULT;
	}
*/
	return 0;
}

static ssize_t dht_sensor_write(struct file *file, const char __user *buf, size_t count, loff_t *ptr)
{
	return 0;
}

static char dht_read_8bit(void)
{
	char i;
	for(i=0;i<8;i++)
	{
		flag=10000;
		while(!(gpio_get_value(GPIODHT))&&(flag--));
		udelay(40);
		temp=0;
		if(gpio_get_value(GPIODHT))
		{
			temp=1;
		}
		while(gpio_get_value(GPIODHT)&&(flag--));
		if(flag<0)
		{
		//	printk(KERN_ALERT"###### overtime  error\n");
			break;
		}
		data<<=1;
		data|=temp;
	}
	return data;
}

static void  dht_start(void)
{
	gpio_direction_output(GPIODHT,0);	
	mdelay(20);
	gpio_direction_output(GPIODHT,1);
	udelay(40);
	gpio_direction_input(GPIODHT);
}

static int dht(void)
{
	unsigned char sum,checkdata;
	dht_start();
	if(!gpio_get_value(GPIODHT))       //dht respond
	{
		flag=10000;
		while((!gpio_get_value(GPIODHT))&&(flag--));	
		flag=10000;
		while((gpio_get_value(GPIODHT))&&(flag--));
		str[0]=dht_read_8bit();	
		str[1]=dht_read_8bit();
		str[2]=dht_read_8bit();
		str[3]=dht_read_8bit();	
		str[4]=dht_read_8bit();
		gpio_direction_output(GPIODHT,1);
		sum=str[0]+str[1]+str[2]+str[3];
		checkdata=str[4];
		if(sum==checkdata)
		{
			send[0]=str[0];
			send[1]=str[1];
			send[2]=str[2];
			send[3]=str[3];
		//	printk(KERN_ALERT"kernel temperature=%d,humidity=%d",send[2],send[0]);
		}

	}
	
	return 0;
}



static long dht_sensor_ioctl( struct file *file, unsigned int cmd, unsigned long arg)
{
	switch(cmd){
		case 0:
			printk(KERN_ALERT"in ioctl 0!\n");
			gpio_direction_output(GPIODHT,1);
			break;
		case 1:
		{
			void __user *p=(void __user *)arg;
			printk(KERN_ALERT"in ioctl 1!\n");
			dht();
			copy_to_user(p,send,sizeof(send));
			break;
		}
		case 2:
			printk(KERN_ALERT"in ioctl 2!\n");
			break;
		default:
			printk(KERN_ALERT"in ioctl default!\n");

	}
	return 0;
}

static const struct file_operations dht_sensor_ops = {
		.owner = THIS_MODULE,
		.open = dht_sensor_open,
		.release = dht_sensor_close,
		.read = dht_sensor_read,
		.write = dht_sensor_write,
		.unlocked_ioctl = dht_sensor_ioctl
};

static struct miscdevice dht_sensor_miscdev = {
		MISC_DYNAMIC_MINOR,
		"dht",
		&dht_sensor_ops,
};

static int __init dht_sensor_init(void)
{
	if(misc_register(&dht_sensor_miscdev))
	{
	  printk(KERN_ALERT"###############: Couldn't register device 0, %d.\n", 255);
	  return -EBUSY;
	}
	printk(KERN_ALERT"register succesful\n");
	return 0;
}

static void __exit dht_sensor_exit(void)
{
	misc_deregister(&dht_sensor_miscdev);
}

module_init(dht_sensor_init);
module_exit(dht_sensor_exit);
MODULE_LICENSE("GPL");