/*********************************************************************************
 *      Copyright:  (C) 2023 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  tsl2561.c
 *    Description:  This file is the Lux sensor TSL2561 code
 *
 *        Version:  1.0.0(10/08/23)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "10/08/23 17:52:00"
 *
 * Pin connection:
 *               STH20 Module            Raspberry Pi Board
 *                   VCC      <----->      #Pin1(3.3V)
 *                   SDA0     <----->      #Pin27(SDA, BCM GPIO0)
 *                   SCL0     <----->      #Pin28(SCL, BCM GPIO1)
 *                   GND      <----->      GND
 *
 * /boot/config.txt:
 *                  dtoverlay=i2c0,pins_0_1
 *
 ********************************************************************************/


#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>
#include <time.h>
#include <errno.h>
#include <libgen.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "util_proc.h"
#include "logger.h"
#include "tsl2561.h"


#define CONTROL_REG                     0x80
#define REG_COUNT                       4

#define POWER_UP                        0x03
#define POWER_DOWN                      0x00

#define OFF                             0
#define ON                              1

/* Register Address  */
enum
{
    /* Channel_0 = DATA0HIGH<<8 + DATA0LOW */
    DATA0LOW = 0x8C,
    DATA0HIGH,

    /* Channel_1 = DATA1HIGH<<8 + DATA1LOW */
    DATA1LOW,
    DATA1HIGH,
};

static const int  regs_addr[REG_COUNT]={DATA0LOW, DATA0HIGH, DATA1LOW, DATA1HIGH};

void tsl2561_power(int fd, int cmd)
{
    struct i2c_msg               msg;
    struct i2c_rdwr_ioctl_data   data;
    unsigned char                buf[2];

    msg.addr= TSL2561_I2CADDR;
    msg.flags=0;  /* write */
    msg.len= 1;
    msg.buf= buf;

    data.nmsgs= 1;
    data.msgs= &msg;

    msg.buf[0]=CONTROL_REG;
    if( ioctl(fd, I2C_RDWR, &data) < 0 )
    {
        log_error("%s() ioctl failure: %s\n", __func__, strerror(errno));
        return ;
    }


    if( cmd )
        msg.buf[0]=POWER_UP;
    else
        msg.buf[0]=POWER_DOWN;

    if( ioctl(fd, I2C_RDWR, &data) < 0 )
    {
        log_error("%s() ioctl failure: %s\n", __func__, strerror(errno));
        return ;
    }

    return ;
}

int tsl2561_readreg(int fd, unsigned char regaddr, unsigned char *regval)
{
    struct i2c_msg               msg;
    struct i2c_rdwr_ioctl_data   data;
    unsigned char                buf[2];

    msg.addr= TSL2561_I2CADDR;
    msg.flags=0;  /* write */
    msg.len= 1;
    msg.buf= buf;
    msg.buf[0] = regaddr;

    data.nmsgs= 1;
    data.msgs= &msg;

    if( ioctl(fd, I2C_RDWR, &data) < 0 )
    {
        log_error("%s() ioctl failure: %s\n", __func__, strerror(errno));
        return -1;
    }

    memset(buf, 0, sizeof(buf));

    msg.addr= TSL2561_I2CADDR;
    msg.flags=I2C_M_RD;  /* read */
    msg.len= 1;
    msg.buf= buf;

    data.nmsgs= 1;
    data.msgs= &msg;

    if( ioctl(fd, I2C_RDWR, &data) < 0 )
    {
        log_error("%s() ioctl failure: %s\n", __func__, strerror(errno));
        return -1;
    }

    *regval = msg.buf[0];
    return 0;
}

int tsl2561_get_lux(float *lux)
{
    int                 i, fd;
	int                 rv = 0;
    char               *dev = TSL2561_I2CDEV;
    float               div = 0.0;

    unsigned char       reg_data[REG_COUNT];
    unsigned char       buf;
    int                 chn0_data = 0;
    int                 chn1_data = 0;

	if( !lux )
	{
		log_error("Invalid input arguments\n");
		return -1;
	}

    if( (fd=open(dev, O_RDWR)) < 0)
    {
        log_error("i2c device '%s' open failed: %s\n", dev, strerror(errno));
        return -2;
    }

    tsl2561_power(fd, ON);

    msleep(410);  /* t(CONV) MAX 400ms */

    /* Read register Channel0 and channel1 data from register */
    for(i=0; i<REG_COUNT; i++)
    {
        tsl2561_readreg(fd, regs_addr[i], &reg_data[i]);
    }

    chn0_data = reg_data[1]*256 + reg_data[0]; /* Channel0 = DATA0HIGH<<8 + DATA0LOW  */
    chn1_data = reg_data[3]*256 + reg_data[2]; /* channel1 = DATA1HIGH<<8 +  DATA1LOW */

    if( chn0_data<=0 || chn1_data<0 )
    {
		rv = -2;
        goto OUT;
    }

    div = (float)chn1_data / (float)chn0_data;

    if( div>0 && div<=0.5 )
        *lux = 0.304*chn0_data-0.062*chn0_data*pow(div,1.4);

    else if( div>0.5 && div<=0.61 )
        *lux = 0.0224*chn0_data-0.031*chn1_data;

    else if( div>0.61 && div<=0.8 )
        *lux = 0.0128*chn0_data-0.0153*chn1_data;

    else if( div>0.8 && div<=1.3 )
        *lux = 0.00146*chn0_data-0.00112*chn1_data;

    else if( div>1.3 )
        *lux = 0.0;

OUT:
    tsl2561_power(fd, OFF);
    return rv;
}