/*
 *  bh1750fvi.c
 *
 *  Copyright (C) 2012 Computex Co.,Ltd.
 *
 *  Sample to test CM-3G main board using CM-3G CHECK BOARD
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>

#define I2C_DEVICE		"/dev/i2c-3"
#define DEV_ADDRESS		0x23

void usage(char *app_name)
{
	printf("%s - Displays the H-Resolution Mode, H-Resolution Mode2 and L-Resolution mode values for BH1750FVI sensor\n", app_name);
	printf("Usage: %s -d [device path]\n", app_name);
	printf("\t\t-d - i2c device path (Default: "I2C_DEVICE")\n");
	printf("Eg: %s\n", app_name);
	exit(0);
}

/****************************************************************
 * Main
 ****************************************************************/
int main(int argc, char* argv[])
{
	unsigned char buf[10];
	int d;
	char shortoptions[] = "d:h";
	char input_device[16];
	float hres, hres2, lres;

	input_device[0] = 0;
	for (;;) {
		d = getopt_long(argc, argv, shortoptions, (void *)NULL, &index);
		if (-1 == d)
		{
			break;
		}
		switch (d) {
		case 'd':
			strcpy(input_device, optarg);
			break;
		default:
			usage(argv[0]);
		}
	}
	if(input_device[0] == 0)
		strcpy(input_device, I2C_DEVICE);

	int file = open(input_device, O_RDWR);
	if(file < 0) {
		printf("Error: "I2C_DEVICE " open failed\n");
		exit(1);
	}
	
	if(ioctl(file, I2C_SLAVE, DEV_ADDRESS) < 0) {
		printf("Error: %s setting device address to 0x%xfailed\n", input_device, DEV_ADDRESS);
		goto out;
	}
	/* power on the device */
	buf[0] = 0x01;
	if (write(file, buf,1) != 1) {
err_write:
		printf("Failed to write to i2c bus\n");
		goto out;
	}
	/* reset the device */
	buf[0] = 0x07;
	if (write(file, buf,1) != 1) {
		goto err_write;
	}

	printf("H-RES       H-RES2      L-RES\n");     

	/* measure one time values */
	while(1)
	{
		/* power on the device */
		buf[0] = 0x01;
		if (write(file, buf,1) != 1) {
			goto err_write;
		}
		/* H-Resolution Mode */
		buf[0] = 0x20;
		if (write(file, buf,1) != 1) {
			goto err_write;
		}
		usleep(120000);			/* 120 ms wait */
		buf[0] = 0x0;
		if (read(file, buf, 2) != 2) {
			printf("Failed to read from i2c bus\n");
			goto out;
		}
		hres = ((float)(buf[1] | (buf[0]<<8)))/1.2;

		/* power on the device */
		buf[0] = 0x01;
		if (write(file, buf,1) != 1) {
			goto err_write;
		}
		/* H-Resolution Mode2 */
		buf[0] = 0x21;
		if (write(file, buf,1) != 1) {
			goto err_write;
		}
		usleep(120000);			/* 120 ms wait */
		buf[0] = 0x0;
		if (read(file, buf, 2) != 2) {
			printf("Failed to read from the i2c bus.\n");
			goto out;
		}
		hres2 = ((float)(buf[1] | (buf[0]<<8)))/1.2;
	
		/* power on the device */
		buf[0] = 0x01;
		if (write(file, buf,1) != 1) {
			goto err_write;
		}
		/* L-Resolution Mode */
		buf[0] = 0x23;
		if (write(file, buf,1) != 1) {
			goto err_write;
		}
		usleep(120000);			/* 120 ms wait */
		buf[0] = 0x0;
		if (read(file, buf, 2) != 2) {
			printf("Failed to read from the i2c bus.\n");
			goto out;
		}
		lres = ((float)(buf[1] | (buf[0]<<8)))/1.2;

		printf("%-11.3f %-11.3f %-11.3f\n", hres, hres2, lres);
	}

out:
	close(file);
	return 0;
}