/*
 * distance_sensor.c - driver for distance_sensor
 *						   8bits out, 4bits in
 *
 * Copyright (C) 2012 Loongson Corporation
 *
 * 2013-03-15
 */
#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 GPIOTRI    16
//#define GPIOECHO   17
#define GPIOTRI    3
#define GPIOECHO   2


#define SOUND_SPEED 340
static int distance_sensor_open(struct inode *inode, struct file *file) 
{
	//printk(KERN_ALERT"#####################sensor open ok!!!\n");

	gpio_request(GPIOTRI,"TRIGGER");
	gpio_request(GPIOECHO, "ECHO");

	gpio_direction_input(GPIOECHO);
	gpio_direction_output(GPIOTRI,0);
	return 0;
}

static int distance_sensor_close(struct inode *inode, struct file *file)
{
	gpio_free(GPIOTRI);
	gpio_free(GPIOECHO);
	//printk(KERN_ALERT"sensor close ok!!!\n");
	return 0;
}

static ssize_t distance_sensor_read(struct file *file, char __user *buf, size_t count, loff_t *ptr)
{

	return 0;
}

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

#if 0
static int  get_time(void)
{
	printk(KERN_ALERT"recive ok!");
	struct timeval timeval1, timeval2;
	int count = 0;
	//int s;
	int us;

	while(!gpio_get_value(GPIOECHO)){
		count ++;	
		if(count > 0xf0000)
			break;
	};
	printk(KERN_ALERT"step 1, count is 0x%x\n",count);
	do_gettimeofday(&timeval1);
	
	count = 0;
	while(gpio_get_value(GPIOECHO)){
		count ++;	
		if(count > 0xf00000)
			break;
	};
	do_gettimeofday(&timeval2);
	printk(KERN_ALERT"step 2, count is 0x%x\n",count);
	//int s = (float)(timeval2.tv_sec-timeval1.tv_sec);

	us = (timeval2.tv_usec-timeval1.tv_usec) * SOUND_SPEED;
	printk(KERN_ALERT"distance is %d /1000000 m\n",  us );

	return us;
}
#endif

static int  get_time(void)
{
	return gpio_get_value(GPIOECHO);
}

static long distance_sensor_ioctl( struct file *file, unsigned int cmd, unsigned long arg)
{
	int ret;
//	printk(KERN_ALERT"in ioctl func!");
	switch(cmd){
		case 0:
			gpio_set_value(GPIOTRI, 1);
			break;
		case 1:
			{
			void __user *p = (void __user *)arg;
			ret = get_time();
			copy_to_user(p, &ret, sizeof(ret));
			}
			break;
		case 2:
			gpio_set_value(GPIOTRI, 0);

			break;
		default:
			printk(KERN_ALERT"in ioctl default!\n");

	}

	return 0;
}

static const struct file_operations distance_sensor_ops = {
		.owner = THIS_MODULE,
		.open = distance_sensor_open,
		.release = distance_sensor_close,
		.read = distance_sensor_read,
		.write = distance_sensor_write,
		.unlocked_ioctl = distance_sensor_ioctl
};

static struct miscdevice distance_sensor_miscdev = {
		MISC_DYNAMIC_MINOR,
		"d_s",
		&distance_sensor_ops,
};

static int __init distance_sensor_init(void)
{

	if (misc_register(&distance_sensor_miscdev))
	{
	  printk(KERN_ALERT"###############: Couldn't register device 0, %d.\n", 255);
	  return -EBUSY;
	}

	return 0;
}

static void __exit distance_sensor_exit(void)
{
	misc_deregister(&distance_sensor_miscdev);
}

module_init(distance_sensor_init);
module_exit(distance_sensor_exit);
MODULE_LICENSE("GPL");