/*********************************************************************************
 *      Copyright:  (C) 2023 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  sht20.c
 *    Description:  This file is temperature and relative humidity sensor SHT20 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:
 *                  SHT20                 Raspberry Pi 40Pin
 *                   VCC      <----->      #Pin1(3.3V)
 *                   SDA      <----->      #Pin3(SDA, BCM GPIO2)
 *                   SCL      <----->      #Pin5(SCL, BCM GPIO3)
 *                   GND      <----->      GND
 *
 * /boot/config.txt:
 *                  dtoverlay=i2c1,pins_2_3
 *
 ********************************************************************************/

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

/* SHT2X 7-bit I2C slave address */
#define SHT2X_CHIPADDR                  0x40

/* SHT2X trigger command */
#define SOFTRESET                       0xFE
#define TRIGGER_TEMPERATURE_NO_HOLD     0xF3
#define TRIGGER_HUMIDITY_NO_HOLD        0xF5

/* Linux /dev/i2c-x device program API mode */
enum
{
    MODE_IOCTL, /* I2C device API use ioctl() */
    MODE_RDWR,  /* I2C device API use read()/write() */
};

typedef struct i2c_s
{
    char           *dev;    /* I2C master device, /dev/i2c-N */
    int             addr;   /* 7-bits slave address */
    int             fd;     /* File description */
    int             mode;   /* I2C device API use read/write or ioctl mode */
} i2c_t;

int sht2x_softreset(i2c_t *i2c);
int sht2x_get_serialnumber(i2c_t *i2c, uint8_t *serialnumber, int size);
int sht2x_get_temp_humidity(i2c_t *i2c, float *temp, float *rh);

int i2c_init(i2c_t *i2c, int mode, char *i2cdev, int addr);
int i2c_write(i2c_t *i2c, uint8_t *data, int len);
int i2c_read(i2c_t *i2c, uint8_t *buf, int size);
void i2c_term(i2c_t *i2c);

static inline void msleep(unsigned long ms);
void print_buf(const char *prompt, uint8_t *buf, int size);
void dump_buf(const char *prompt, char *buffer, size_t length);

static inline void banner(const char *progname)
{
    printf("%s program Version v1.0.0\n", progname);
    printf("Copyright (C) 2023 LingYun IoT System Studio.\n");
}

static void program_usage(const char *progname)
{

    printf("Usage: %s [OPTION]...\n", progname);
    printf(" %s is SHT20 temperature and humidity sensor program. \n", progname);

    printf(" -d[device  ]  Specify I2C device, such as /dev/i2c-1\n");
    printf(" -m[mode    ]  Specify API mode, 0 for ioctl and 1 for read()/write()\n");
    printf(" -h[help    ]  Display this help information\n");
    printf(" -v[version ]  Display the program version\n");

    printf("\n");
    banner(progname);
    return;
}

int main(int argc, char **argv)
{
    char           *dev="/dev/i2c-1";
    char           *progname=NULL;
    int             mode = MODE_IOCTL;
    int             rv;
    float           temp, rh;
    uint8_t         serialnumber[8];
    i2c_t           i2c;

    struct option long_options[] = {
        {"device", required_argument, NULL, 'd'},
        {"mode", required_argument, NULL, 'm'},
        {"version", no_argument, NULL, 'v'},
        {"help", no_argument, NULL, 'h'},
        {NULL, 0, NULL, 0}
    };

    progname = basename(argv[0]);

    /* Parser the command line parameters */
    while ((rv = getopt_long(argc, argv, "d:m:vh", long_options, NULL)) != -1)
    {
        switch (rv)
        {
            case 'd': /*  Set I2C device path: /dev/i2c-1 */
                dev = optarg;
                break;

            case 'm': /*  Set I2C API mode: 0,1 */
                mode = atoi(optarg) ? MODE_RDWR : MODE_IOCTL;
                break;

            case 'v':  /*  Get software version */
                banner(progname);
                return EXIT_SUCCESS;

            case 'h':  /*  Get help information */
                program_usage(progname);
                return 0;

            default:
                break;
        }
    }

    if( i2c_init(&i2c, mode, dev, SHT2X_CHIPADDR) < 0 )
    {
        printf("I2C master device initial failed.\n");
        return 1;
    }

    if( sht2x_softreset(&i2c) < 0 )
    {
        printf("SHT2x initialize failure, maybe device not present!\n");
        return 1;
    }

    if( sht2x_get_serialnumber(&i2c, serialnumber, 8) < 0)
    {
        printf("SHT2x get serial number failure\n");
        return 3;
    }

    if( sht2x_get_temp_humidity(&i2c, &temp, &rh) < 0 )
    {
        printf("SHT2x get get temperature and relative humidity failure\n");
        return 3;
    }

    printf("Temperature=%lf ℃ relative humidity=%lf.\n", temp, rh);

    i2c_term(&i2c);

    return 0;
}

int sht2x_softreset(i2c_t *i2c)
{
    uint8_t           buf[1];

    if( !i2c || i2c->fd<0 )
    {
        printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
        return -1;
    }

    /* software reset SHT2x */
    buf[0] = SOFTRESET;
    if( i2c_write(i2c, buf, 1) < 0 )
    {
        return -2;
    }

    msleep(50);

    return 0;
}

int sht2x_get_temp_humidity(i2c_t *i2c, float *temp, float *rh)
{
    uint8_t           buf[4];

    if( !i2c || !temp || !rh || i2c->fd<0 )
    {
        printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
        return -1;
    }

    /* send trigger temperature measure command and read the data */
    memset(buf, 0, sizeof(buf));
    buf[0]=TRIGGER_TEMPERATURE_NO_HOLD;
    i2c_write(i2c, buf, 1);

    msleep(85); /* datasheet: typ=66, max=85 */

    memset(buf, 0, sizeof(buf));
    i2c_read(i2c, buf, 3);
    print_buf("Temperature sample data: ", buf, 3);
    *temp = 175.72 * (((((int) buf[0]) << 8) + buf[1]) / 65536.0) - 46.85;

    /* send trigger humidity measure command and read the data */
    memset(buf, 0, sizeof(buf));
    buf[0] = TRIGGER_HUMIDITY_NO_HOLD;
    i2c_write(i2c, buf, 1);

    msleep(29); /* datasheet: typ=22, max=29 */
    memset(buf, 0, sizeof(buf));

    i2c_read(i2c, buf, 3);
    print_buf("Relative humidity sample data: ", buf, 3);
    *rh = 125 * (((((int) buf[0]) << 8) + buf[1]) / 65536.0) - 6;

    return 0;
}

int sht2x_get_serialnumber(i2c_t *i2c, uint8_t *serialnumber, int size)
{
    uint8_t           buf[4]={0x0};

    if( !i2c || i2c->fd<0 || !serialnumber || size!=8 )
    {
        printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
        return -1;
    }

    /* Read SerialNumber from Location 1 */
    memset(buf, 0, sizeof(buf));
    buf[0] = 0xfa;  /* command for readout on-chip memory */
    buf[1] = 0x0f;  /* on-chip memory address */
    i2c_write(i2c, buf, 2);

    memset(buf, 0, sizeof(buf));
    i2c_read(i2c, buf, 4);

    if( !buf[0] && !buf[1] && !buf[2] && !buf[3] )
    {
        printf("ERROR: SHT2X device not detected!\n");
        return -2;
    }

    serialnumber[5]=buf[0]; /* Read SNB_3 */
    serialnumber[4]=buf[1]; /* Read SNB_2 */
    serialnumber[3]=buf[2]; /* Read SNB_1 */
    serialnumber[2]=buf[3]; /* Read SNB_0 */

    /* Read SerialNumber from Location 2 */
    memset(buf, 0, sizeof(buf) );
    buf[0]=0xfc;  /* command for readout on-chip memory */
    buf[1]=0xc9;  /* on-chip memory address */
    i2c_write(i2c, buf, 2);

    memset(buf, 0, sizeof(buf) );
    i2c_read(i2c, buf, 4);

    serialnumber[1]=buf[0]; /* Read SNC_1 */
    serialnumber[0]=buf[1]; /* Read SNC_0 */
    serialnumber[7]=buf[2]; /* Read SNA_1 */
    serialnumber[6]=buf[3]; /* Read SNA_0 */

    print_buf("SHT2x Serial number: ", serialnumber, 8);

    return 0;
}

/*+----------------------+
 *|   I2C API functions  |
 *+----------------------+*/

int i2c_init(i2c_t *i2c, int mode, char *i2cdev, int addr)
{
    if( !i2c || !i2cdev || !addr )
        return -1;

    memset(i2c, 0, sizeof(*i2c));
    i2c->addr = addr;
    i2c->dev = i2cdev;
    i2c->mode = mode;

    if( (i2c->fd=open(i2cdev, O_RDWR)) < 0)
    {
        printf("open i2c device %s failed: %s\n", i2cdev, strerror(errno));
        return -1;
    }

    if( MODE_RDWR == i2c->mode )
    {
        /* set I2C mode and SHT2x slave address */
        ioctl(i2c->fd, I2C_TENBIT, 0);          /* Not 10-bit but 7-bit mode */
        ioctl(i2c->fd, I2C_SLAVE, i2c->addr);   /* set SHT2x slave address */
    }

    return 0;
}

void i2c_term(i2c_t *i2c)
{
    if( !i2c )
        return;

    if( i2c->fd > 0)
        close(i2c->fd);

    return ;
}

int i2c_write(i2c_t *i2c, uint8_t *data, int len)
{
    struct i2c_rdwr_ioctl_data      tr;
    int                             rv = 0;

    if( !data || len<= 0)
    {
        printf("%s() invalid input arguments!\n", __func__);
        return -1;
    }

    /* I2C device program API: read()/write() */
    if( MODE_RDWR == i2c->mode )
    {
        write(i2c->fd, data, len);
        return 0;
    }

    /* I2C device program API: ioctl() */
    tr.nmsgs = 1;
    tr.msgs = malloc( sizeof(struct i2c_msg)*tr.nmsgs );
    if ( !tr.msgs )
    {
        printf("%s() msgs malloc failed!\n", __func__);
        return -2;
    }

    tr.msgs[0].addr = i2c->addr;
    tr.msgs[0].flags = 0; //write
    tr.msgs[0].len = len;
    tr.msgs[0].buf = malloc(len);
    if( !tr.msgs[0].buf )
    {
        printf("%s() msgs malloc failed!\n", __func__);
        rv = -3;
        goto cleanup;
    }
    memcpy(tr.msgs[0].buf, data, len);


    if( ioctl(i2c->fd, I2C_RDWR, &tr)<0 )
    {
        printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
        rv = -4;
        goto cleanup;
    }

cleanup:
    if( tr.msgs[0].buf )
        free(tr.msgs[0].buf);

    if( tr.msgs )
        free(tr.msgs);

    return rv;
}

int i2c_read(i2c_t *i2c, uint8_t *buf, int size)
{
    struct i2c_rdwr_ioctl_data      tr;
    int                             rv = 0;

    if( !buf || size<= 0)
    {
        printf("%s() invalid input arguments!\n", __func__);
        return -1;
    }

    /* I2C device program API: read()/write() */
    if( MODE_RDWR == i2c->mode )
    {
        read(i2c->fd, buf, size);
        return 0;
    }

    /* I2C device program API: ioctl() */
    tr.nmsgs = 1;
    tr.msgs = malloc( sizeof(struct i2c_msg)*tr.nmsgs );
    if ( !tr.msgs )
    {
        printf("%s() msgs malloc failed!\n", __func__);
        return -2;
    }

    tr.msgs[0].addr = i2c->addr;
    tr.msgs[0].flags = I2C_M_RD; //read
    tr.msgs[0].len = size;
    tr.msgs[0].buf = buf;
    memset(buf, 0, size);

    if( ioctl(i2c->fd, I2C_RDWR, &tr)<0 )
    {
        printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
        rv = -4;
    }

    free( tr.msgs );
    return rv;
}

/*+----------------------+
 *|    Misc functions    |
 *+----------------------+*/

static inline void msleep(unsigned long ms)
{
    struct timespec cSleep;
    unsigned long ulTmp;

    cSleep.tv_sec = ms / 1000;
    if (cSleep.tv_sec == 0)
    {
        ulTmp = ms * 10000;
        cSleep.tv_nsec = ulTmp * 100;
    }
    else
    {
        cSleep.tv_nsec = 0;
    }

    nanosleep(&cSleep, 0);
}

void print_buf(const char *prompt, uint8_t *buf, int size)
{
    int          i;

    if( !buf )
    {
        return ;
    }

    if( prompt )
    {
        printf("%s ", prompt);
    }

    for(i=0; i<size; i++)
    {
        printf("%02x ", buf[i]);
    }
    printf("\n");

    return ;
}

void dump_buf(const char *prompt, char *buffer, size_t length)
{
    size_t i, j;

    if (prompt)
    {
        printf("%s\n", prompt);
    }

    for (i = 0; i < length; i += 16)
    {
        printf("%08zx: ", i);

        for (j = 0; j < 16; j++)
        {
            if (i + j < length)
            {
                printf("%02x ", buffer[i + j]);
            }
            else
            {
                printf("   ");
            }
        }

        printf(" ");

        for (j = 0; j < 16; j++)
        {
            if (i + j < length)
            {
                unsigned char c = buffer[i + j];
                printf("%c", (c >= 32 && c <= 126) ? c : '.');
            }
            else
            {
                printf(" ");
            }
        }

        printf("\n");
    }
}