Article 6GEXA How to execute linux userspace application any no.of times in the linux target board?

How to execute linux userspace application any no.of times in the linux target board?

by
imran patan
from LinuxQuestions.org on (#6GEXA)
The below code is used to test the uart driver on linux-jetson board which runs only one time,if needed to run multiple times on the board the device needs to be restarted.
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <termios.h>
#include <string.h>

#include <errno.h>
#include <limits.h>

#include <stdbool.h>
#include <unistd.h>

#define LOOPBACK_FORMAT "loopback: %s\r\n"
#define LOOPBACK_FORMAT_LEN strlen(LOOPBACK_FORMAT)
#define MAX_READ_SIZE 235
#define MAX_LOOPBACK_SIZE MAX_READ_SIZE + LOOPBACK_FORMAT_LEN

#define DEBUG

struct UartDevice {
char* filename;
int rate;

int fd;
struct termios *tty;
};

int uart_start(struct UartDevice* dev, bool canonical) {
struct termios *tty;
int fd;
int rc;

fd = open(dev->filename, O_RDWR | O_NOCTTY);
if (fd < 0) {
printf("%s: failed to open UART device\r\n", __func__);
return fd;
}

tty = malloc(sizeof(*tty));
if (!tty) {
printf("%s: failed to allocate UART TTY instance\r\n", __func__);

memset(tty, 0, sizeof(*tty));

/*
* Set baud-rate.
*/
tty->c_cflag |= dev->rate;

/* Ignore framing and parity errors in input. */
tty->c_iflag |= IGNPAR;

/* Use 8-bit characters. This too may affect standard streams,
* but any sane C library can deal with 8-bit characters. */
tty->c_cflag |= CS8;

/* Enable receiver. */
tty->c_cflag |= CREAD;

if (canonical) {
/* Enable canonical mode.
* This is the most important bit, as it enables line buffering etc. */
tty->c_lflag |= ICANON;
} else {
/* To maintain best compatibility with normal behaviour of terminals,
* we set TIME=0 and MAX=1 in noncanonical mode. This means that
* read() will block until at least one byte is available. */
tty->c_cc[VTIME] = 0;
tty->c_cc[VMIN] = 1;
}

/*
* Flush port.
*/
tcflush(fd, TCIFLUSH);

/*
* Apply attributes.
*/
rc = tcsetattr(fd, TCSANOW, tty);
if (rc) {
printf("%s: failed to set attributes\r\n", __func__);
return rc;
}

dev->fd = fd;
dev->tty = tty;

return 0;
}/*
* Read a string from the UART device.
*
* @param dev points to the UART device to be read from
* @param buf points to the start of buffer to be read into
* @param buf_len length of the buffer to be read
*
* @return - number of bytes read if the read procedure succeeded
* - negative if the read procedure failed
*/
int uart_reads(struct UartDevice* dev, char *buf, size_t buf_len) {
int rc;

rc = read(dev->fd, buf, buf_len - 1);
if (rc < 0) {
printf("%s: failed to read uart data\r\n", __func__);
return rc;
}

buf[rc] = '\0';
return rc;
}

/*
* Write data to the UART device.
*
* @param dev points to the UART device to be written to
* @param buf points to the start of buffer to be written from
* @param buf_len length of the buffer to be written
*
* @return - number of bytes written if the write procedure succeeded
* - negative if the write procedure failed
*/
int uart_writen(struct UartDevice* dev, char *buf, size_t buf_len) {
return write(dev->fd, buf, buf_len);
}

/*
* Write a string to the UART device.
*
* @param dev points to the UART device to be written to
* @param string points to the start of buffer to be written from
*
* @return - number of bytes written if the write procedure succeeded
* - negative if the write procedure failed
*/
int uart_writes(struct UartDevice* dev, char *string) {
size_t len = strlen(string);
return uart_writen(dev, string, len);
}

/*
* Stop the UART device.
*
* @param dev points to the UART device to be stopped
*/
void uart_stop(struct UartDevice* dev) {
close(dev->fd);
free(dev->tty);
}

int main()
{
struct UartDevice dev;
int rc;

dev.filename = "/dev/ttyTHS2";
dev.rate = B115200;

rc = uart_start(&dev, false);
if (rc) {
return rc;
}
char read_data[MAX_READ_SIZE];
char loopback_data[MAX_LOOPBACK_SIZE];
size_t read_data_len;

printf("UART DEMO\r\n");
uart_writes(&dev, "UART DEMO\r\n");

while (1)
{

read_data_len = uart_reads(&dev, read_data, MAX_READ_SIZE);

if (read_data_len > 0) {
printf("%s", read_data);
snprintf(loopback_data, MAX_LOOPBACK_SIZE, LOOPBACK_FORMAT, read_data);
uart_writes(&dev, loopback_data);
}

}

uart_stop(&dev);

return 0;
}

Could anyone please help me out what are the changes to be done to execute the above code infinite times?

Thanks and regards,
Imran patan,
India.
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