Linux: HSUART configuration

/*******************************************************************************
 * @file        : Zigbee_application.c
 * @brief       : Topic :
 *                  This program test for the zigbee application.
 * @author      : Venu (venu.kovelamudi@vvdntech.com)
 * @Copyright   : (c) 2017 , VVDN Technologies Pvt. Ltd.
 *                  Permission is hereby granted to everyone in VVDN Technologies
 *                  to use the Software without restriction, including without
 *                  limitation the rights to use, copy, modify, merge, publish,
 *                  distribute, distribute with modifications.
 ********************************************************************************/

/* Header files declarations */
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>


/**
 * @funtion : main
 * @brief   : This program sets the configuration of HSUART between MSM8909
 *            and QCA4024. To get the data and send the commands depending on the
 *            user prospective.
 **/
int main(int argc, char **argv)
{
    /* structure indicates HSUART configurations */
    struct termios tio, stdio, old_stdio;
    int tty_fd = 0, BAUDRATE = 0;
    unsigned char chp = '\0', cht = '\0';

    if (argc != 3) {
        printf("Error:Inavalid arguments\n");
        printf("Usage:./a.out /dev/ttyHS0 B115200\n");
        return EXIT_FAILURE;
    }

    /* Get the previous configurations of the terminal */
    tcgetattr(STDOUT_FILENO, &old_stdio);
    /* Clear the structure data for terminal*/
    memset(&stdio, 0, sizeof(stdio));
    /* input modes */
    stdio.c_iflag = 0;
    /* output modes */
    stdio.c_oflag = 0;
    /* control modes */
    stdio.c_cflag = 0;
    /* local modes */
    stdio.c_lflag = 0;
    /* Minimum number of characters for noncanonical read (MIN). */
    stdio.c_cc[VMIN] = 1;
    /* Timeout in deciseconds for noncanonical read (TIME). */
    stdio.c_cc[VTIME] = 0;
    /* TCSANOW -> The change occurs immediately. */
    /* TCSAFLUSH -> The change occurs after all output written to fd has been transmitted.
       This option should be used when changing parameters that affect output. */
    /* Sets the new attributes for terminal */
    tcsetattr(STDOUT_FILENO, TCSANOW, &stdio);
    tcsetattr(STDOUT_FILENO, TCSAFLUSH, &stdio);
    /* make the reads non-blocking */
    fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK);
    /* Clear the structure data for HSUART*/
    memset(&tio, 0, sizeof(tio));
    tio.c_iflag = 0;
    tio.c_oflag = 0;
    /* 8n1, see termios.h for more information */
    tio.c_cflag = CS8 | CREAD | CLOCAL | CRTSCTS;
    tio.c_lflag = 0;
    tio.c_cc[VMIN] = 1;
    tio.c_cc[VTIME] = 5;
    /* Open the HSUART port for read and write */
    if((tty_fd = open(argv[1], O_RDWR | O_NOCTTY | O_NONBLOCK)) == -1){
        printf("Error while opening\n");
        return EXIT_FAILURE;
    }
    BAUDRATE = atoi(argv[2]);
    /* If the input baud rate is set to zero, the input baud rate will be equal to the output baud rate. */
    cfsetospeed(&tio, BAUDRATE);
    /* sets the input baud rate */
    cfsetispeed(&tio, BAUDRATE);
    /* Sets the new attributes for HSUART */
    tcsetattr(tty_fd, TCSANOW, &tio);

    while (cht != 'e' && cht != 'E') {
        /* Read the data from the HSUART */
        if (read(tty_fd, &chp, 1) > 0){
            printf("p%c\n", chp);
            /* if new data is available on the serial port, print it out */
            write(STDOUT_FILENO, &chp, 1);
        }
        /* Read the data from the terminal */
        if (read(STDIN_FILENO, &cht, 1) > 0){
            printf("u%c\n", cht);
            /* if new data is available on the console, send it to serial port */
            write(tty_fd, &cht, 1);
        }
    }

    /* Close the file discriptor */
    close(tty_fd);
    /* Sets the old attributes for terminal */
    tcsetattr(STDOUT_FILENO, TCSANOW, &old_stdio);
    return EXIT_SUCCESS;
}