core/serial: Add utilities to deal with serial ports

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

1 files changed, 209 insertions, 0 deletions

diff --git a/src/serial.c b/src/serial.c
new file mode 100644
index 00000000..26cf59d7
--- /dev/null
+++ b/src/serial.c
@@ -0,0 +1,209 @@
+/*
+ * serial.c
+ *
+ * Utility functions to deal with serial ports
+ *
+ * Copyright (C) 2011  Sylvain Munaut <tnt@246tNt.com>
+ *
+ * All Rights Reserved
+ *
+ * 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
+ *  @{
+ */
+
+/*! \file serial.c
+ *  \file Osmocom serial port helpers
+ */
+
+#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>
+#include <linux/serial.h>
+
+
+#include <osmocom/core/serial.h>
+
+
+#if 0
+# define dbg_perror(x) perror(x)
+#else
+# define dbg_perror(x) do { } while (0)
+#endif
+
+/*! \brief 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=0, v24;
+	struct termios tio;
+
+	/* Open device */
+	fd = open(dev, O_RDWR | O_NOCTTY | O_NDELAY);
+	if (fd < 0) {
+		dbg_perror("open");
+		return -errno;
+	}
+
+	/* 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 | ISTRIP);
+	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)");
+		rc = -errno;
+		goto error;
+	}
+
+	return fd;
+
+error:
+	if (fd)
+		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;
+}
+
+/*! \brief 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);
+}
+
+/*! \brief 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)
+{
+	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 ... */
+}
+
+/*! \brief 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)
+{
+	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;
+	}
+
+	return 0;
+}
+
+/*! }@ */