/*********************************************************************************
 *      Copyright:  (C) 2019 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  at91_sysGpio.c
 *    Description:  This file si GPIO API operatore on /sys/class/gpio/xxx
 *                 
 *        Version:  1.0.0(2019年08月26日)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "2019年08月26日 22时28分19秒"
 *                 
 ********************************************************************************/

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>

#include "at91_sysGpio.h"


/*  export $port in /sys/class/gpio/export */
int gpio_export(const char *port)
{
    char          fpath[SYSFILE_LEN];
    FILE          *fp;
    int           pin;

    if(!port)
    {
        gpio_print("invalid input arguments\n");
        return -1;
    }

    snprintf(fpath, SYSFILE_LEN, "%s/%s", SYSGPIO_PATH, port);

    /* GPIO port already export */
    if( !access(fpath, F_OK) )
    {
        gpio_print("%s already export\n", port);
        return 0;
    }
    
    if( !(fp=fopen(SYSGPIO_EXPORT_PATH, "w")) )
    {
        gpio_print("open '%s' failure: %s\n", SYSGPIO_EXPORT_PATH, strerror(errno));
        return -2;
    }

    pin = at91_port2pin(port);
    fprintf(fp, "%d", pin);

    fclose(fp);

    return 0;
}


/*  unexport $port in /sys/class/gpio/unexport */
int gpio_unexport(const char *port)
{
    char          fpath[SYSFILE_LEN];
    FILE          *fp;
    int           pin;

    if(!port)
    {
        gpio_print("invalid input arguments\n");
        return -1;
    }

    snprintf(fpath, SYSFILE_LEN, "%s/%s", SYSGPIO_PATH, port);

    /* GPIO port not export */
    if( access(fpath, F_OK) )
    {
        gpio_print("%s not export\n", port);
        return 0;
    }
    
    if( !(fp=fopen(SYSGPIO_UNEXPORT_PATH, "w")) )
    {
        gpio_print("open '%s' failure: %s\n", SYSGPIO_EXPORT_PATH, strerror(errno));
        return -2;
    }

    pin = at91_port2pin(port);
    fprintf(fp, "%d", pin);

    fclose(fp);

    return 0;
}


/*  configure $port direction as $mode */
int gpio_config(const char *port, const char *mode)
{
    char          fpath[SYSFILE_LEN];
    FILE          *fp;
    int           size;

    if(!port)
    {
        gpio_print("invalid input arguments\n");
        return 0;
    }

    snprintf(fpath, SYSFILE_LEN, "%s/%s", SYSGPIO_PATH, port);

    if( access(fpath, F_OK) ) /* GPIO port not export */
    {
        if( gpio_export(port) < 0 )
            return -1;
    }
    
    size = SYSFILE_LEN-strlen(fpath);
    strncat(fpath, "/direction", size);
    if( !(fp=fopen(fpath, "w")) )
    {
        gpio_print("open '%s' failure: %s\n", fpath, strerror(errno));
        return -1;
    }

    fputs(mode, fp);

    fclose(fp);

    return 0;
}



/*  write $value into GPIO $port */
int gpio_write(const char *port, const char *value)
{
    char          fpath[SYSFILE_LEN];
    FILE          *fp;
    int           size;

    if(!port)
    {
        gpio_print("invalid input arguments\n");
        return 0;
    }

    snprintf(fpath, SYSFILE_LEN, "%s/%s", SYSGPIO_PATH, port);

    if( access(fpath, F_OK) ) /* GPIO port not export */
    {
        if( gpio_export(port) < 0 )
            return -1;
    }
    
    size = SYSFILE_LEN-strlen(fpath);
    strncat(fpath, "/value", size);
    if( !(fp=fopen(fpath, "w")) )
    {
        gpio_print("open '%s' failure: %s\n", fpath, strerror(errno));
        return -1;
    }

    fputs(value, fp);

    fclose(fp);

    return 0;
}


/*  read gpio value from $port  */
int gpio_read(const char *port)
{
    char          fpath[SYSFILE_LEN];
    FILE          *fp;
    int           size;
    char          v_str[32];

    if(!port)
    {
        gpio_print("invalid input arguments\n");
        return 0;
    }

    snprintf(fpath, SYSFILE_LEN, "%s/%s", SYSGPIO_PATH, port);

    if( access(fpath, F_OK) ) /* GPIO port not export */
    {
        return -1;
    }
    
    size = SYSFILE_LEN-strlen(fpath);
    strncat(fpath, "/value", size);
    if( !(fp=fopen(fpath, "r")) )
    {
        gpio_print("open '%s' failure: %s\n", fpath, strerror(errno));
        return -1;
    }

    memset(v_str, 0, sizeof(v_str));
    fgets(v_str, sizeof(v_str), fp);

    fclose(fp);

    return atoi(v_str);
}