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/*! \file serial.c
* Utility functions to deal with serial ports */
/*
* Copyright (C) 2011 Sylvain Munaut <tnt@246tNt.com>
*
* All Rights Reserved
*
* SPDX-License-Identifier: GPL-2.0+
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*! \addtogroup serial
* @{
* Osmocom serial port helpers
*
* \file serial.c */
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <termios.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifdef __linux__
#include <linux/serial.h>
#endif
#include <osmocom/core/serial.h>
#if 0
# define dbg_perror(x) perror(x)
#else
# define dbg_perror(x) do { } while (0)
#endif
/*! Open serial device and does base init
* \param[in] dev Path to the device node to open
* \param[in] baudrate Baudrate constant (speed_t: B9600, B...)
* \returns >=0 file descriptor in case of success or negative errno.
*/
int
osmo_serial_init(const char *dev, speed_t baudrate)
{
int rc, fd=-1, v24, flags;
struct termios tio;
/* Use nonblock as the device might block otherwise */
fd = open(dev, O_RDWR | O_NOCTTY | O_SYNC | O_NONBLOCK);
if (fd < 0) {
dbg_perror("open");
return -errno;
}
/* now put it into blcoking mode */
flags = fcntl(fd, F_GETFL, 0);
if (flags < 0) {
dbg_perror("fcntl get flags");
rc = -errno;
goto error;
}
flags &= ~O_NONBLOCK;
rc = fcntl(fd, F_SETFL, flags);
if (rc != 0) {
dbg_perror("fcntl set flags");
rc = -errno;
goto error;
}
/* Configure serial interface */
rc = tcgetattr(fd, &tio);
if (rc < 0) {
dbg_perror("tcgetattr()");
rc = -errno;
goto error;
}
cfsetispeed(&tio, baudrate);
cfsetospeed(&tio, baudrate);
tio.c_cflag &= ~(PARENB | CSTOPB | CSIZE | CRTSCTS);
tio.c_cflag |= (CREAD | CLOCAL | CS8);
tio.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
tio.c_iflag |= (INPCK);
tio.c_iflag &= ~(ISTRIP | IXON | IXOFF | IGNBRK | INLCR | ICRNL | IGNCR);
tio.c_oflag &= ~(OPOST | ONLCR);
rc = tcsetattr(fd, TCSANOW, &tio);
if (rc < 0) {
dbg_perror("tcsetattr()");
rc = -errno;
goto error;
}
/* Set ready to read/write */
v24 = TIOCM_DTR | TIOCM_RTS;
rc = ioctl(fd, TIOCMBIS, &v24);
if (rc < 0) {
dbg_perror("ioctl(TIOCMBIS)");
/* some serial porst don't support this, so let's not
* return an error here */
}
return fd;
error:
if (fd >= 0)
close(fd);
return rc;
}
static int
_osmo_serial_set_baudrate(int fd, speed_t baudrate)
{
int rc;
struct termios tio;
rc = tcgetattr(fd, &tio);
if (rc < 0) {
dbg_perror("tcgetattr()");
return -errno;
}
cfsetispeed(&tio, baudrate);
cfsetospeed(&tio, baudrate);
rc = tcsetattr(fd, TCSANOW, &tio);
if (rc < 0) {
dbg_perror("tcgetattr()");
return -errno;
}
return 0;
}
/*! Change current baudrate
* \param[in] fd File descriptor of the open device
* \param[in] baudrate Baudrate constant (speed_t: B9600, B...)
* \returns 0 for success or negative errno.
*/
int
osmo_serial_set_baudrate(int fd, speed_t baudrate)
{
osmo_serial_clear_custom_baudrate(fd);
return _osmo_serial_set_baudrate(fd, baudrate);
}
/*! Change current baudrate to a custom one using OS specific method
* \param[in] fd File descriptor of the open device
* \param[in] baudrate Baudrate as integer
* \returns 0 for success or negative errno.
*
* This function might not work on all OS or with all type of serial adapters
*/
int
osmo_serial_set_custom_baudrate(int fd, int baudrate)
{
#ifdef __linux__
int rc;
struct serial_struct ser_info;
rc = ioctl(fd, TIOCGSERIAL, &ser_info);
if (rc < 0) {
dbg_perror("ioctl(TIOCGSERIAL)");
return -errno;
}
ser_info.flags = ASYNC_SPD_CUST | ASYNC_LOW_LATENCY;
ser_info.custom_divisor = ser_info.baud_base / baudrate;
rc = ioctl(fd, TIOCSSERIAL, &ser_info);
if (rc < 0) {
dbg_perror("ioctl(TIOCSSERIAL)");
return -errno;
}
return _osmo_serial_set_baudrate(fd, B38400); /* 38400 is a kind of magic ... */
#elif defined(__APPLE__)
#ifndef IOSSIOSPEED
#define IOSSIOSPEED _IOW('T', 2, speed_t)
#endif
int rc;
unsigned int speed = baudrate;
rc = ioctl(fd, IOSSIOSPEED, &speed);
if (rc < 0) {
dbg_perror("ioctl(IOSSIOSPEED)");
return -errno;
}
return 0;
#else
#pragma message ("osmo_serial_set_custom_baudrate: unsupported platform")
return 0;
#endif
}
/*! Clear any custom baudrate
* \param[in] fd File descriptor of the open device
* \returns 0 for success or negative errno.
*
* This function might not work on all OS or with all type of serial adapters
*/
int
osmo_serial_clear_custom_baudrate(int fd)
{
#ifdef __linux__
int rc;
struct serial_struct ser_info;
rc = ioctl(fd, TIOCGSERIAL, &ser_info);
if (rc < 0) {
dbg_perror("ioctl(TIOCGSERIAL)");
return -errno;
}
ser_info.flags = ASYNC_LOW_LATENCY;
ser_info.custom_divisor = 0;
rc = ioctl(fd, TIOCSSERIAL, &ser_info);
if (rc < 0) {
dbg_perror("ioctl(TIOCSSERIAL)");
return -errno;
}
#endif
return 0;
}
/*! @} */
|
