/*********************************************************************************
 *      Copyright:  (C) 2023 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  at24c.c
 *    Description:  This file is AT24Cxx EEPROM 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:
 *                 AT24Cxx                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>

/*+----------------------+
 *|  EEPROM Information  |
 *+----------------------+*/

/* AT24Cxx 7-bit I2C slave address */
#define AT24C_CHIPADDR                  0x50

enum
{
    AT24C01  = 1,
    AT24C02  = 2,
    AT24C04  = 4,
    AT24C08  = 8,
    AT24C16  = 16,
    AT24C32  = 32,
    AT24C64  = 64,
    AT24C128 = 128,
    AT24C256 = 256,
    AT24C512 = 512,
} chipid_t;

typedef struct i2c_s
{
    char           *dev;    /* I2C master device, /dev/i2c-N */
    int             addr;   /* 7-bits slave address */
    int             fd;     /* File description */
} i2c_t;

typedef struct eeprom_s
{
    int             chip;       /* Chip ID */
    uint32_t        capacity;   /* Chip size in bytes */
    int             pagesize;   /* Page size in bytes */
} eeprom_t;

#define EEP_INFO(_chip, _capacity, _pagesize)       \
    .chip       = _chip,                            \
    .capacity   = _capacity,                        \
    .pagesize   = _pagesize,                        \

static eeprom_t at24c_ids[] = {
    { EEP_INFO(AT24C01,  128,   8)   },
    { EEP_INFO(AT24C02,  256,   8)   },
    { EEP_INFO(AT24C04,  512,   16)  },
    { EEP_INFO(AT24C08,  1024,  16)  },
    { EEP_INFO(AT24C16,  2048,  16)  },
    { EEP_INFO(AT24C32,  4096,  32)  },
    { EEP_INFO(AT24C64,  8192,  32)  },
    { EEP_INFO(AT24C128, 16384, 64)  },
    { EEP_INFO(AT24C256, 32768, 64)  },
    { EEP_INFO(AT24C512, 65536, 128) },
};

typedef struct at24c_s
{
    i2c_t            i2c;
    eeprom_t        *eeprom;
} at24c_t;

int at24c_init(at24c_t *at24c, int chip);
int at24c_read(at24c_t *at24c, int offset, uint8_t *buf, int size);
int at24c_write(at24c_t *at24c, int offset, uint8_t *data, int len);
int at24c_test(at24c_t *at24c);

int i2c_init(i2c_t *i2c, 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 dump_buf(const char *prompt, char *buf, size_t len);

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 AT24Cxx EEPROM test program. \n", progname);

    printf(" -c[chipid  ]  Specify EEPROM chipID: 1,2,4,8...512 \n");
    printf(" -d[device  ]  Specify I2C device, such as /dev/i2c-1\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           *progname=NULL;
    char           *dev="/dev/i2c-1";
    int             chipid = AT24C256; /* default */
    at24c_t         at24c;
    int             rv;

    struct option long_options[] = {
        {"chip", required_argument, NULL, 'c'},
        {"device", required_argument, NULL, 'd'},
        {"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, "c:d:vh", long_options, NULL)) != -1)
    {
        switch (rv)
        {
            case 'c': /*  Set chip ID: 1,2,4,8...512 */
                chipid = atoi(optarg);
                break;

            case 'd': /*  Set I2C device path: /dev/i2c-1 */
                dev = optarg;
                break;

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

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

            default:
                break;
        }
    }

    if( at24c_init(&at24c, chipid) < 0 )
    {
        printf("at24c initial failed!\n");
        return 1;
    }

    if( i2c_init(&at24c.i2c, dev, AT24C_CHIPADDR) < 0 )
    {
        printf("i2c initial failed!\n");
        return 2;
    }

    if( at24c_test(&at24c) < 0 )
    {
        return 3;
    }

    i2c_term(&at24c.i2c);
    return 0;
}

/*+----------------------+
 *| EEPROM API functions |
 *+----------------------+*/

int at24c_init(at24c_t *at24c, int chip)
{
    int             i;

    if( !at24c )
        return -1;

    for(i=0; i<sizeof(at24c_ids)/sizeof(at24c_ids[0]); i++)
    {
        if( at24c_ids[i].chip == chip )
        {
            at24c->eeprom = &at24c_ids[i];
            printf("Detect EEPROM AT24C%02d capacity %d bytes, pagesize %d bytes.\r\n",
                    chip, at24c->eeprom->capacity, at24c->eeprom->pagesize);
            return 0;
        }
    }

    printf("EEPROM: Can not found EEPROM by chip ID[%d]\r\n", chip);
    return -2;
}

int at24c_test(at24c_t *at24c)
{
    eeprom_t       *eeprom;
    uint8_t         buf[128];
    int             i;
    int             addr = 0;

    if( !at24c )
        return -1;

    eeprom = at24c->eeprom;

    /* Read data before write */
    memset(buf, 0, sizeof(buf));
    if( at24c_read(at24c, addr, buf, sizeof(buf)) < 0 )
    {
        return -2;
    }
    dump_buf("<<<EEPROM read data:\n", (char *)buf, sizeof(buf));

    /* fill a page data */
    for(i=0; i<eeprom->pagesize; i++)
    {
        buf[i] = i;
    }

    /* write a page data from the address not page alignment */
    if( at24c_write(at24c, addr+8, buf, eeprom->pagesize) < 0 )
    {
        return -3;
    }

    /* Read data after write */
    memset(buf, 0, sizeof(buf));
    if( at24c_read(at24c, addr, buf, sizeof(buf)) < 0 )
    {
        return -2;
    }
    dump_buf("<<<EEPROM read data:\n", (char *)buf, sizeof(buf));

    return 0;
}

/* Figure 9. Page Write */
int at24c_write_page(at24c_t *at24c, int offset, uint8_t *data, int len)
{
    uint8_t         buf[256];
    int             bytes, rv;
    int             addrlen;
    eeprom_t       *eeprom;

    if(!at24c || offset<0 || !data || !len)
        return -1;

    eeprom = at24c->eeprom;

    /* exceeding EEPROM size  */
    if( offset+len > eeprom->capacity )
        return -1;

    if( len > eeprom->pagesize )
        len = eeprom->pagesize;

    /*
     * A temporary write buffer must be used which contains both the address
     * and the data to be written, put the address in first based upon the
     * size of the address for the EEPROM.
     */
    if( eeprom->chip >= AT24C16)
    {
        buf[0]=(uint8_t)(offset>>8);
        buf[1]=(uint8_t)(offset);
        addrlen = 2;
    }
    else
    {
        buf[0]=(uint8_t)(offset);
        addrlen = 1;
    }

    /* Put the data in the write buffer following the address */
    memcpy(&buf[addrlen], data, len);

    /* Write a page of data at the specified address to the EEPROM. */
    rv = i2c_write(&at24c->i2c, buf, len+addrlen);
    if( rv < 0 )
        printf("%s() write data failed\n", __func__);

    /* Must give a delay here to wait page write finish */
    msleep(5);

    return rv;
}

int at24c_write(at24c_t *at24c, int offset, uint8_t *data, int len)
{
    int             bytes;
    eeprom_t       *eeprom;

    if(!at24c || offset<0 || !data || len<0)
        return -1;

    eeprom = at24c->eeprom;

    /* exceeding EEPROM size  */
    if( offset+len > eeprom->capacity )
        return -1;

    /* The offset + write bytes shouldn't overflow that page,
     * or it will over write the start bytes of this page  */
    if( offset%eeprom->pagesize )
        bytes = eeprom->pagesize - offset%eeprom->pagesize;
    else
        bytes = len>eeprom->pagesize? eeprom->pagesize : len;

    /* Write max one page at a time */
    while(len > 0)
    {
        if( at24c_write_page(at24c, offset, data, bytes) )
        {
            return -2;
        }

        len    -= bytes;
        data   += bytes;
        offset += bytes;

        bytes = len>eeprom->pagesize? eeprom->pagesize : len;
    }

    return 0;
}

/* Figure 12. Sequential Read */
int at24c_read(at24c_t *at24c, int offset, uint8_t *buf, int size)
{
    struct i2c_rdwr_ioctl_data      tr;
    eeprom_t                       *eeprom;
    uint8_t                         addr[2];
    int                             addrlen;
    int                             bytes;
    int                             rv = 0;

    if(!at24c || offset<0 || !buf || size<=0)
        return -1;

    eeprom = at24c->eeprom;

    /* exceeding EEPROM size  */
    if( offset+size > eeprom->capacity )
        return -1;

    memset(buf, 0, size);

    if( eeprom->chip >= AT24C16)
    {
        addr[0]=(uint8_t)(offset>>8);
        addr[1]=(uint8_t)(offset);
        addrlen = 2;
    }
    else
    {
        addr[0]=(uint8_t)(offset);
        addrlen = 1;
    }

    /* We can't call i2c_write() and i2c_read() because it will generate a
     * stop condition after send the offset address, it doesn't compatible
     * with EEPROM sequential read sequence;
     */


    /* use I2C userspace API to send two message without stop condition */

    tr.nmsgs = 2;
    tr.msgs = malloc( sizeof(struct i2c_msg)*tr.nmsgs );
    if ( !tr.msgs )
    {
        printf("%s() msgs malloc failed!\n", __func__);
        return -2;
    }

    /* Create the I2C message for writing the EEPROM offset address */
    tr.msgs[0].addr = at24c->i2c.addr;
    tr.msgs[0].flags = 0; //write
    tr.msgs[0].len = addrlen;
    tr.msgs[0].buf = addr;

    /* Create the I2C message for reading data from EEPROM */
    memset(buf, 0, size);
    tr.msgs[1].addr = at24c->i2c.addr;
    tr.msgs[1].flags = I2C_M_RD; //read
    tr.msgs[1].len = size;
    tr.msgs[1].buf = buf;

    if( ioctl(at24c->i2c.fd, I2C_RDWR, &tr)<0 )
    {
        printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
        rv = -4;
    }

    free( tr.msgs );
    return rv;
}


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

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

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

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

    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: 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;
    }

    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);
}

#define LINELEN 81
#define CHARS_PER_LINE 16
static char *print_char =
"                "
"                "
" !\"#$%&'()*+,-./"
"0123456789:;<=>?"
"@ABCDEFGHIJKLMNO"
"PQRSTUVWXYZ[\\]^_"
"`abcdefghijklmno"
"pqrstuvwxyz{|}~ "
"                "
"                "
" ???????????????"
"????????????????"
"????????????????"
"????????????????"
"????????????????"
"????????????????";

void dump_buf(const char *prompt, char *buf, size_t len)
{
    int rc;
    int idx;
    char prn[LINELEN];
    char lit[CHARS_PER_LINE + 2];
    char hc[4];
    short line_done = 1;

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

    rc = len;
    idx = 0;
    lit[CHARS_PER_LINE] = '\0';

    while (rc > 0)
    {
        if (line_done)
            snprintf(prn, LINELEN, "%08X: ", idx);

        do
        {
            unsigned char c = buf[idx];
            snprintf(hc, 4, "%02X ", c);
            strncat(prn, hc, LINELEN);

            lit[idx % CHARS_PER_LINE] = print_char[c];
        }
        while (--rc > 0 && (++idx % CHARS_PER_LINE != 0));

        line_done = (idx % CHARS_PER_LINE) == 0;
        if (line_done)
        {
            printf("%s  %s\r\n", prn, lit);
        }
    }

    if (!line_done)
    {
        int ldx = idx % CHARS_PER_LINE;
        lit[ldx++] = print_char[(int)buf[idx]];
        lit[ldx] = '\0';

        while ((++idx % CHARS_PER_LINE) != 0)
            strncat(prn, "   ", sizeof(prn)-strlen(prn));

        printf("%s  %s\r\n", prn, lit);

    }
}