X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=hardware%2Fcommon%2Fserial.c;h=cebca29e418dd833007c37572a747d2c84d85cbc;hb=999f6730c66fafc76fe32f7090cc740d901a2226;hp=67a4ab73a2b259d4d8c268fc32f51156b7051886;hpb=d02a535e05513ba8d2d4a82b49180d60ef410e1c;p=libsigrok.git

diff --git a/hardware/common/serial.c b/hardware/common/serial.c
index 67a4ab73..32a6d23c 100644
--- a/hardware/common/serial.c
+++ b/hardware/common/serial.c
@@ -1,7 +1,9 @@
 /*
- * This file is part of the sigrok project.
+ * This file is part of the libsigrok project.
  *
- * Copyright (C) 2010 Bert Vermeulen <bert@biot.com>
+ * Copyright (C) 2010-2012 Bert Vermeulen <bert@biot.com>
+ * Copyright (C) 2010-2012 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
  *
  * 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
@@ -17,109 +19,866 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <glob.h>
 #include <string.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <termios.h>
 #include <stdlib.h>
 #include <glib.h>
+#include <glib/gstdio.h>
+#include <libserialport.h>
+#include "libsigrok.h"
+#include "libsigrok-internal.h"
 
-#include "sigrok.h"
+#define LOG_PREFIX "serial"
 
+/**
+ * Open the specified serial port.
+ *
+ * @param serial Previously initialized serial port structure.
+ * @param flags Flags to use when opening the serial port. Possible flags
+ *              include SERIAL_RDWR, SERIAL_RDONLY, SERIAL_NONBLOCK.
+ *
+ * If the serial structure contains a serialcomm string, it will be
+ * passed to serial_set_paramstr() after the port is opened.
+ *
+ * @return SR_OK on success, SR_ERR on failure.
+ */
+SR_PRIV int serial_open(struct sr_serial_dev_inst *serial, int flags)
+{
+	int ret;
+	char *error;
+	int sp_flags = 0;
+
+	if (!serial) {
+		sr_dbg("Invalid serial port.");
+		return SR_ERR;
+	}
 
+	sr_spew("Opening serial port '%s' (flags %d).", serial->port, flags);
 
-char *serial_port_glob[] = {
-	/* Linux */
-	"/dev/ttyS*",
-	"/dev/ttyUSB*",
-	"/dev/ttyACM*",
-	/* MacOS X */
-	"/dev/ttys*",
-	"/dev/tty.USB-*",
-	"/dev/tty.Modem-*",
-	NULL
-};
+	sp_get_port_by_name(serial->port, &serial->data);
 
+	if (flags & SERIAL_RDWR)
+		sp_flags = (SP_MODE_READ | SP_MODE_WRITE);
+	else if (flags & SERIAL_RDONLY)
+		sp_flags = SP_MODE_READ;
+
+	serial->nonblocking = (flags & SERIAL_NONBLOCK) ? 1 : 0;
+
+	ret = sp_open(serial->data, sp_flags);
+
+	switch (ret) {
+	case SP_ERR_ARG:
+		sr_err("Attempt to open serial port with invalid parameters.");
+		return SR_ERR_ARG;
+	case SP_ERR_FAIL:
+		error = sp_last_error_message();
+		sr_err("Error opening port (%d): %s.",
+			sp_last_error_code(), error);
+		sp_free_error_message(error);
+		return SR_ERR;
+	}
+
+	if (serial->serialcomm)
+		return serial_set_paramstr(serial, serial->serialcomm);
+	else
+		return SR_OK;
+}
 
-GSList *list_serial_ports(void)
+/**
+ * Close the specified serial port.
+ *
+ * @param serial Previously initialized serial port structure.
+ *
+ * @return SR_OK on success, SR_ERR on failure.
+ */
+SR_PRIV int serial_close(struct sr_serial_dev_inst *serial)
 {
-	glob_t g;
-	GSList *ports;
-	int i, j;
+	int ret;
+	char *error;
 
-	ports = NULL;
-	for(i = 0; serial_port_glob[i]; i++)
-	{
-		if(!glob(serial_port_glob[i], 0, NULL, &g))
-		{
-			for(j = 0; j < g.gl_pathc; j++)
-				ports = g_slist_append(ports, strdup(g.gl_pathv[j]));
-			globfree(&g);
-		}
+	if (!serial) {
+		sr_dbg("Invalid serial port.");
+		return SR_ERR;
+	}
+
+	if (!serial->data) {
+		sr_dbg("Cannot close unopened serial port %s.", serial->port);
+		return SR_ERR;
 	}
 
-	return ports;
+	sr_spew("Closing serial port %s.", serial->port);
+
+	ret = sp_close(serial->data);
+
+	switch (ret) {
+	case SP_ERR_ARG:
+		sr_err("Attempt to close an invalid serial port.");
+		return SR_ERR_ARG;
+	case SP_ERR_FAIL:
+		error = sp_last_error_message();
+		sr_err("Error closing port (%d): %s.",
+			sp_last_error_code(), error);
+		sp_free_error_message(error);
+		return SR_ERR;
+	}
+
+	sp_free_port(serial->data);
+	serial->data = NULL;
+
+	return SR_OK;
 }
 
+/**
+ * Flush serial port buffers.
+ *
+ * @param serial Previously initialized serial port structure.
+ *
+ * @return SR_OK on success, SR_ERR on failure.
+ */
+SR_PRIV int serial_flush(struct sr_serial_dev_inst *serial)
+{
+	int ret;
+	char *error;
+
+	if (!serial) {
+		sr_dbg("Invalid serial port.");
+		return SR_ERR;
+	}
+
+	if (!serial->data) {
+		sr_dbg("Cannot flush unopened serial port %s.", serial->port);
+		return SR_ERR;
+	}
+
+	sr_spew("Flushing serial port %s.", serial->port);
+
+	ret = sp_flush(serial->data, SP_BUF_BOTH);
+
+	switch (ret) {
+	case SP_ERR_ARG:
+		sr_err("Attempt to flush an invalid serial port.");
+		return SR_ERR_ARG;
+	case SP_ERR_FAIL:
+		error = sp_last_error_message();
+		sr_err("Error flushing port (%d): %s.",
+			sp_last_error_code(), error);
+		sp_free_error_message(error);
+		return SR_ERR;
+	}
+
+	return SR_OK;
+}
 
-int serial_open(const char *pathname, int flags)
+static int _serial_write(struct sr_serial_dev_inst *serial,
+		const void *buf, size_t count, int nonblocking)
 {
+	ssize_t ret;
+	char *error;
+
+	if (!serial) {
+		sr_dbg("Invalid serial port.");
+		return SR_ERR;
+	}
+
+	if (!serial->data) {
+		sr_dbg("Cannot use unopened serial port %s.", serial->port);
+		return SR_ERR;
+	}
+
+	if (nonblocking)
+		ret = sp_nonblocking_write(serial->data, buf, count);
+	else
+		ret = sp_blocking_write(serial->data, buf, count, 0);
 
-	return open(pathname, flags);
+	switch (ret) {
+	case SP_ERR_ARG:
+		sr_err("Attempted serial port write with invalid arguments.");
+		return SR_ERR_ARG;
+	case SP_ERR_FAIL:
+		error = sp_last_error_message();
+		sr_err("Write error (%d): %s.", sp_last_error_code(), error);
+		sp_free_error_message(error);
+		return SR_ERR;
+	}
+
+	sr_spew("Wrote %d/%d bytes.", ret, count);
+
+	return ret;
 }
 
+/**
+ * Write a number of bytes to the specified serial port.
+ *
+ * @param serial Previously initialized serial port structure.
+ * @param buf Buffer containing the bytes to write.
+ * @param count Number of bytes to write.
+ *
+ * @return The number of bytes written, or a negative error code upon failure.
+ */
+SR_PRIV int serial_write(struct sr_serial_dev_inst *serial,
+		const void *buf, size_t count)
+{
+	return _serial_write(serial, buf, count, serial->nonblocking);
+}
 
-int serial_close(int fd)
+SR_PRIV int serial_write_blocking(struct sr_serial_dev_inst *serial,
+		const void *buf, size_t count)
 {
+	return _serial_write(serial, buf, count, 0);
+}
 
-	return close(fd);
+SR_PRIV int serial_write_nonblocking(struct sr_serial_dev_inst *serial,
+		const void *buf, size_t count)
+{
+	return _serial_write(serial, buf, count, 1);
 }
 
+static int _serial_read(struct sr_serial_dev_inst *serial, void *buf,
+		size_t count, int nonblocking)
+{
+	ssize_t ret;
+	char *error;
+
+	if (!serial) {
+		sr_dbg("Invalid serial port.");
+		return SR_ERR;
+	}
+
+	if (!serial->data) {
+		sr_dbg("Cannot use unopened serial port %s.", serial->port);
+		return SR_ERR;
+	}
+
+	if (nonblocking)
+		ret = sp_nonblocking_read(serial->data, buf, count);
+	else
+		ret = sp_blocking_read(serial->data, buf, count, 0);
+
+	switch (ret) {
+	case SP_ERR_ARG:
+		sr_err("Attempted serial port read with invalid arguments.");
+		return SR_ERR_ARG;
+	case SP_ERR_FAIL:
+		error = sp_last_error_message();
+		sr_err("Read error (%d): %s.", sp_last_error_code(), error);
+		sp_free_error_message(error);
+		return SR_ERR;
+	}
+
+	if (ret > 0)
+		sr_spew("Read %d/%d bytes.", ret, count);
 
-void *serial_backup_params(int fd)
+	return ret;
+}
+
+/**
+ * Read a number of bytes from the specified serial port.
+ *
+ * @param serial Previously initialized serial port structure.
+ * @param buf Buffer where to store the bytes that are read.
+ * @param count The number of bytes to read.
+ *
+ * @return The number of bytes read, or a negative error code upon failure.
+ */
+SR_PRIV int serial_read(struct sr_serial_dev_inst *serial, void *buf,
+		size_t count)
 {
-	struct termios *term;
+	return _serial_read(serial, buf, count, serial->nonblocking);
+}
 
-	term = malloc(sizeof(struct termios));
-	tcgetattr(fd, term);
+SR_PRIV int serial_read_blocking(struct sr_serial_dev_inst *serial, void *buf,
+		size_t count)
+{
+	return _serial_read(serial, buf, count, 0);
+}
 
-	return term;
+SR_PRIV int serial_read_nonblocking(struct sr_serial_dev_inst *serial, void *buf,
+		size_t count)
+{
+	return _serial_read(serial, buf, count, 1);
 }
 
+/**
+ * Set serial parameters for the specified serial port.
+ *
+ * @param serial Previously initialized serial port structure.
+ * @param[in] baudrate The baudrate to set.
+ * @param[in] bits The number of data bits to use (5, 6, 7 or 8).
+ * @param[in] parity The parity setting to use (0 = none, 1 = even, 2 = odd).
+ * @param[in] stopbits The number of stop bits to use (1 or 2).
+ * @param[in] flowcontrol The flow control settings to use (0 = none,
+ *                      1 = RTS/CTS, 2 = XON/XOFF).
+ * @param[in] rts Status of RTS line (0 or 1; required by some interfaces).
+ * @param[in] dtr Status of DTR line (0 or 1; required by some interfaces).
+ *
+ * @retval SR_OK Success
+ * @retval SR_ERR Failure.
+ */
+SR_PRIV int serial_set_params(struct sr_serial_dev_inst *serial, int baudrate,
+			      int bits, int parity, int stopbits,
+			      int flowcontrol, int rts, int dtr)
+{
+	int ret;
+	char *error;
+	struct sp_port_config *config;
+
+	if (!serial) {
+		sr_dbg("Invalid serial port.");
+		return SR_ERR;
+	}
+
+	if (!serial->data) {
+		sr_dbg("Cannot configure unopened serial port %s.", serial->port);
+		return SR_ERR;
+	}
+
+	sr_spew("Setting serial parameters on port %s.", serial->port);
+
+	sp_new_config(&config);
+	sp_set_config_baudrate(config, baudrate);
+	sp_set_config_bits(config, bits);
+	switch (parity) {
+	case 0:
+		sp_set_config_parity(config, SP_PARITY_NONE);
+		break;
+	case 1:
+		sp_set_config_parity(config, SP_PARITY_EVEN);
+		break;
+	case 2:
+		sp_set_config_parity(config, SP_PARITY_ODD);
+		break;
+	default:
+		return SR_ERR_ARG;
+	}
+	sp_set_config_stopbits(config, stopbits);
+	sp_set_config_rts(config, flowcontrol == 1 ? SP_RTS_FLOW_CONTROL : rts);
+	sp_set_config_cts(config, flowcontrol == 1 ? SP_CTS_FLOW_CONTROL : SP_CTS_IGNORE);
+	sp_set_config_dtr(config, dtr);
+	sp_set_config_dsr(config, SP_DSR_IGNORE);
+	sp_set_config_xon_xoff(config, flowcontrol == 2 ? SP_XONXOFF_INOUT : SP_XONXOFF_DISABLED);
+
+	ret = sp_set_config(serial->data, config);
+	sp_free_config(config);
+
+	switch (ret) {
+	case SP_ERR_ARG:
+		sr_err("Invalid arguments for setting serial port parameters.");
+		return SR_ERR_ARG;
+	case SP_ERR_FAIL:
+		error = sp_last_error_message();
+		sr_err("Error setting serial port parameters (%d): %s.",
+			sp_last_error_code(), error);
+		sp_free_error_message(error);
+		return SR_ERR;
+	}
+
+	return SR_OK;
+}
 
-void serial_restore_params(int fd, void *backup)
+/**
+ * Set serial parameters for the specified serial port from parameter string.
+ *
+ * @param serial Previously initialized serial port structure.
+ * @param[in] paramstr A serial communication parameters string of the form
+ * "<baudrate>/<bits><parity><stopbits>{/<option>}".\n
+ *  Examples: "9600/8n1", "600/7o2/dtr=1/rts=0" or "460800/8n1/flow=2".\n
+ * \<baudrate\>=integer Baud rate.\n
+ * \<bits\>=5|6|7|8 Number of data bits.\n
+ * \<parity\>=n|e|o None, even, odd.\n
+ * \<stopbits\>=1|2 One or two stop bits.\n
+ * Options:\n
+ * dtr=0|1 Set DTR off resp. on.\n
+ * flow=0|1|2 Flow control. 0 for none, 1 for RTS/CTS, 2 for XON/XOFF.\n
+ * rts=0|1 Set RTS off resp. on.\n
+ * Please note that values and combinations of these parameters must be
+ * supported by the concrete serial interface hardware and the drivers for it.
+ * @retval SR_OK Success.
+ * @retval SR_ERR Failure.
+ */
+SR_PRIV int serial_set_paramstr(struct sr_serial_dev_inst *serial,
+		const char *paramstr)
 {
+#define SERIAL_COMM_SPEC "^(\\d+)/([5678])([neo])([12])(.*)$"
 
-	tcsetattr(fd, TCSADRAIN, (struct termios *) backup);
+	GRegex *reg;
+	GMatchInfo *match;
+	int speed, databits, parity, stopbits, flow, rts, dtr, i;
+	char *mstr, **opts, **kv;
+
+	speed = databits = parity = stopbits = flow = 0;
+	rts = dtr = -1;
+	sr_spew("Parsing parameters from \"%s\".", paramstr);
+	reg = g_regex_new(SERIAL_COMM_SPEC, 0, 0, NULL);
+	if (g_regex_match(reg, paramstr, 0, &match)) {
+		if ((mstr = g_match_info_fetch(match, 1)))
+			speed = strtoul(mstr, NULL, 10);
+		g_free(mstr);
+		if ((mstr = g_match_info_fetch(match, 2)))
+			databits = strtoul(mstr, NULL, 10);
+		g_free(mstr);
+		if ((mstr = g_match_info_fetch(match, 3))) {
+			switch (mstr[0]) {
+			case 'n':
+				parity = SERIAL_PARITY_NONE;
+				break;
+			case 'e':
+				parity = SERIAL_PARITY_EVEN;
+				break;
+			case 'o':
+				parity = SERIAL_PARITY_ODD;
+				break;
+			}
+		}
+		g_free(mstr);
+		if ((mstr = g_match_info_fetch(match, 4)))
+			stopbits = strtoul(mstr, NULL, 10);
+		g_free(mstr);
+		if ((mstr = g_match_info_fetch(match, 5)) && mstr[0] != '\0') {
+			if (mstr[0] != '/') {
+				sr_dbg("missing separator before extra options");
+				speed = 0;
+			} else {
+				/* A set of "key=value" options separated by / */
+				opts = g_strsplit(mstr + 1, "/", 0);
+				for (i = 0; opts[i]; i++) {
+					kv = g_strsplit(opts[i], "=", 2);
+					if (!strncmp(kv[0], "rts", 3)) {
+						if (kv[1][0] == '1')
+							rts = 1;
+						else if (kv[1][0] == '0')
+							rts = 0;
+						else {
+							sr_dbg("invalid value for rts: %c", kv[1][0]);
+							speed = 0;
+						}
+					} else if (!strncmp(kv[0], "dtr", 3)) {
+						if (kv[1][0] == '1')
+							dtr = 1;
+						else if (kv[1][0] == '0')
+							dtr = 0;
+						else {
+							sr_dbg("invalid value for dtr: %c", kv[1][0]);
+							speed = 0;
+						}
+					} else if (!strncmp(kv[0], "flow", 4)) {
+						if (kv[1][0] == '0')
+							flow = 0;
+						else if (kv[1][0] == '1')
+							flow = 1;
+						else if (kv[1][0] == '2')
+							flow = 2;
+						else {
+							sr_dbg("invalid value for flow: %c", kv[1][0]);
+							speed = 0;
+						}
+					}
+					g_strfreev(kv);
+				}
+				g_strfreev(opts);
+			}
+		}
+		g_free(mstr);
+	}
+	g_match_info_unref(match);
+	g_regex_unref(reg);
 
+	if (speed) {
+		return serial_set_params(serial, speed, databits, parity,
+					 stopbits, flow, rts, dtr);
+	} else {
+		sr_dbg("Could not infer speed from parameter string.");
+		return SR_ERR_ARG;
+	}
 }
 
+/**
+ * Read a line from the specified serial port.
+ *
+ * @param serial Previously initialized serial port structure.
+ * @param buf Buffer where to store the bytes that are read.
+ * @param buflen Size of the buffer.
+ * @param[in] timeout_ms How long to wait for a line to come in.
+ *
+ * Reading stops when CR of LR is found, which is stripped from the buffer.
+ *
+ * @retval SR_OK Success.
+ * @retval SR_ERR Failure.
+ */
+SR_PRIV int serial_readline(struct sr_serial_dev_inst *serial, char **buf,
+		int *buflen, gint64 timeout_ms)
+{
+	gint64 start;
+	int maxlen, len;
+
+	if (!serial) {
+		sr_dbg("Invalid serial port.");
+		return SR_ERR;
+	}
 
-/* flowcontrol 1 = rts/cts  2 = xon/xoff */
-int serial_set_params(int fd, int speed, int bits, int parity, int stopbits, int flowcontrol)
+	if (!serial->data) {
+		sr_dbg("Cannot use unopened serial port %s.", serial->port);
+		return -1;
+	}
+
+	timeout_ms *= 1000;
+	start = g_get_monotonic_time();
+
+	maxlen = *buflen;
+	*buflen = len = 0;
+	while(1) {
+		len = maxlen - *buflen - 1;
+		if (len < 1)
+			break;
+		len = serial_read(serial, *buf + *buflen, 1);
+		if (len > 0) {
+			*buflen += len;
+			*(*buf + *buflen) = '\0';
+			if (*buflen > 0 && (*(*buf + *buflen - 1) == '\r'
+					|| *(*buf + *buflen - 1) == '\n')) {
+				/* Strip CR/LF and terminate. */
+				*(*buf + --*buflen) = '\0';
+				break;
+			}
+		}
+		if (g_get_monotonic_time() - start > timeout_ms)
+			/* Timeout */
+			break;
+		if (len < 1)
+			g_usleep(2000);
+	}
+	if (*buflen)
+		sr_dbg("Received %d: '%s'.", *buflen, *buf);
+
+	return SR_OK;
+}
+
+/**
+ * Try to find a valid packet in a serial data stream.
+ *
+ * @param serial Previously initialized serial port structure.
+ * @param buf Buffer containing the bytes to write.
+ * @param buflen Size of the buffer.
+ * @param[in] packet_size Size, in bytes, of a valid packet.
+ * @param is_valid Callback that assesses whether the packet is valid or not.
+ * @param[in] timeout_ms The timeout after which, if no packet is detected, to
+ *                   abort scanning.
+ * @param[in] baudrate The baudrate of the serial port. This parameter is not
+ *                 critical, but it helps fine tune the serial port polling
+ *                 delay.
+ *
+ * @retval SR_OK Valid packet was found within the given timeout
+ * @retval SR_ERR Failure.
+ */
+SR_PRIV int serial_stream_detect(struct sr_serial_dev_inst *serial,
+				 uint8_t *buf, size_t *buflen,
+				 size_t packet_size, packet_valid_t is_valid,
+				 uint64_t timeout_ms, int baudrate)
 {
-	struct termios term;
+	uint64_t start, time, byte_delay_us;
+	size_t ibuf, i, maxlen;
+	int len;
+
+	maxlen = *buflen;
+
+	sr_dbg("Detecting packets on %s (timeout = %" PRIu64
+	       "ms, baudrate = %d).", serial->port, timeout_ms, baudrate);
+
+	if (maxlen < (packet_size / 2) ) {
+		sr_err("Buffer size must be at least twice the packet size.");
+		return SR_ERR;
+	}
+
+	/* Assume 8n1 transmission. That is 10 bits for every byte. */
+	byte_delay_us = 10 * (1000000 / baudrate);
+	start = g_get_monotonic_time();
 
-	/* only supporting what we need really -- currently just the OLS driver */
-	if(speed != 115200 || bits != 8 || parity != 0 || stopbits != 1 || flowcontrol != 2)
-		return SIGROK_ERR;
+	i = ibuf = len = 0;
+	while (ibuf < maxlen) {
+		len = serial_read(serial, &buf[ibuf], 1);
+		if (len > 0) {
+			ibuf += len;
+		} else if (len == 0) {
+			/* No logging, already done in serial_read(). */
+		} else {
+			/* Error reading byte, but continuing anyway. */
+		}
+
+		time = g_get_monotonic_time() - start;
+		time /= 1000;
+
+		if ((ibuf - i) >= packet_size) {
+			/* We have at least a packet's worth of data. */
+			if (is_valid(&buf[i])) {
+				sr_spew("Found valid %d-byte packet after "
+					"%" PRIu64 "ms.", (ibuf - i), time);
+				*buflen = ibuf;
+				return SR_OK;
+			} else {
+				sr_spew("Got %d bytes, but not a valid "
+					"packet.", (ibuf - i));
+			}
+			/* Not a valid packet. Continue searching. */
+			i++;
+		}
+		if (time >= timeout_ms) {
+			/* Timeout */
+			sr_dbg("Detection timed out after %dms.", time);
+			break;
+		}
+		if (len < 1)
+			g_usleep(byte_delay_us);
+	}
 
-	if(tcgetattr(fd, &term) < 0)
-		return SIGROK_ERR;
-	if(cfsetispeed(&term, B115200) < 0)
-		return SIGROK_ERR;
-	term.c_cflag &= ~CSIZE;
-	term.c_cflag |= CS8;
-	term.c_cflag &= ~CSTOPB;
-	term.c_cflag |= IXON | IXOFF;
-	term.c_iflag |= IGNPAR;
-	if(tcsetattr(fd, TCSADRAIN, &term) < 0)
-		return SIGROK_ERR;
+	*buflen = ibuf;
 
-	return SIGROK_OK;
+	sr_err("Didn't find a valid packet (read %d bytes).", *buflen);
+
+	return SR_ERR;
+}
+
+/**
+ * Extract the serial device and options from the options linked list.
+ *
+ * @param options List of options passed from the command line.
+ * @param serial_device Pointer where to store the exctracted serial device.
+ * @param serial_options Pointer where to store the optional extracted serial
+ * options.
+ *
+ * @return SR_OK if a serial_device is found, SR_ERR if no device is found. The
+ * returned string should not be freed by the caller.
+ */
+SR_PRIV int sr_serial_extract_options(GSList *options, const char **serial_device,
+				      const char **serial_options)
+{
+	GSList *l;
+	struct sr_config *src;
+
+	*serial_device = NULL;
+
+	for (l = options; l; l = l->next) {
+		src = l->data;
+		switch (src->key) {
+		case SR_CONF_CONN:
+			*serial_device = g_variant_get_string(src->data, NULL);
+			sr_dbg("Parsed serial device: %s", *serial_device);
+			break;
+
+		case SR_CONF_SERIALCOMM:
+			*serial_options = g_variant_get_string(src->data, NULL);
+			sr_dbg("Parsed serial options: %s", *serial_options);
+			break;
+		}
+	}
+
+	if (!*serial_device) {
+		sr_dbg("No serial device specified");
+		return SR_ERR;
+	}
+
+	return SR_OK;
 }
 
+#ifdef _WIN32
+typedef HANDLE event_handle;
+#else
+typedef int event_handle;
+#endif
+
+SR_PRIV int serial_source_add(struct sr_serial_dev_inst *serial, int events,
+		int timeout, sr_receive_data_callback_t cb, void *cb_data)
+{
+	enum sp_event mask = 0;
+	unsigned int i;
+
+	if (sp_new_event_set(&serial->event_set) != SP_OK)
+		return SR_ERR;
+
+	if (events & G_IO_IN)
+		mask |= SP_EVENT_RX_READY;
+	if (events & G_IO_OUT)
+		mask |= SP_EVENT_TX_READY;
+	if (events & G_IO_ERR)
+		mask |= SP_EVENT_ERROR;
+
+	if (sp_add_port_events(serial->event_set, serial->data, mask) != SP_OK) {
+		sp_free_event_set(serial->event_set);
+		return SR_ERR;
+	}
+
+	serial->pollfds = (GPollFD *) g_malloc0(sizeof(GPollFD) * serial->event_set->count);
+
+	for (i = 0; i < serial->event_set->count; i++) {
+
+		serial->pollfds[i].fd = ((event_handle *) serial->event_set->handles)[i];
 
+		mask = serial->event_set->masks[i];
+
+		if (mask & SP_EVENT_RX_READY)
+			serial->pollfds[i].events |= G_IO_IN;
+		if (mask & SP_EVENT_TX_READY)
+			serial->pollfds[i].events |= G_IO_OUT;
+		if (mask & SP_EVENT_ERROR)
+			serial->pollfds[i].events |= G_IO_ERR;
+
+		if (sr_session_source_add_pollfd(&serial->pollfds[i],
+				timeout, cb, cb_data) != SR_OK)
+			return SR_ERR;
+	}
+
+	return SR_OK;
+}
+
+SR_PRIV int serial_source_remove(struct sr_serial_dev_inst *serial)
+{
+	unsigned int i;
+
+	for (i = 0; i < serial->event_set->count; i++)
+		if (sr_session_source_remove_pollfd(&serial->pollfds[i]) != SR_OK)
+			return SR_ERR;
+
+	g_free(serial->pollfds);
+	sp_free_event_set(serial->event_set);
+
+	serial->pollfds = NULL;
+	serial->event_set = NULL;
+
+	return SR_OK;
+}
+
+/**
+ * Find USB serial devices via the USB vendor ID and product ID.
+ *
+ * @param vendor_id Vendor ID of the USB device.
+ * @param product_id Product ID of the USB device.
+ *
+ * @return A GSList of strings containing the path of the serial device or
+ *         NULL if no serial device is found. The returned list must be freed
+ *         by the caller.
+ */
+SR_PRIV GSList *sr_serial_find_usb(uint16_t vendor_id, uint16_t product_id)
+{
+#ifdef __linux__
+	const gchar *usb_dev;
+	const char device_tree[] = "/sys/bus/usb/devices/";
+	GDir *devices_dir, *device_dir;
+	GSList *l = NULL;
+	GSList *tty_devs;
+	GSList *matched_paths;
+	FILE *fd;
+	char tmp[5];
+	gchar *vendor_path, *product_path, *path_copy;
+	gchar *prefix, *subdir_path, *device_path, *tty_path;
+	unsigned long read_vendor_id, read_product_id;
+	const char *file;
+
+	l = NULL;
+	tty_devs = NULL;
+	matched_paths = NULL;
+
+	if (!(devices_dir = g_dir_open(device_tree, 0, NULL)))
+		return NULL;
+
+	/*
+	 * Find potential candidates using the vendor ID and product ID
+	 * and store them in matched_paths.
+	 */
+	while ((usb_dev = g_dir_read_name(devices_dir))) {
+		vendor_path = g_strconcat(device_tree,
+					  usb_dev, "/idVendor", NULL);
+		product_path = g_strconcat(device_tree,
+					   usb_dev, "/idProduct", NULL);
+
+		if (!g_file_test(vendor_path, G_FILE_TEST_EXISTS) ||
+		    !g_file_test(product_path, G_FILE_TEST_EXISTS))
+			goto skip_device;
+
+		if ((fd = g_fopen(vendor_path, "r")) == NULL)
+			goto skip_device;
+
+		if (fgets(tmp, sizeof(tmp), fd) == NULL) {
+			fclose(fd);
+			goto skip_device;
+		}
+		read_vendor_id = strtoul(tmp, NULL, 16);
+
+		fclose(fd);
+
+		if ((fd = g_fopen(product_path, "r")) == NULL)
+			goto skip_device;
+
+		if (fgets(tmp, sizeof(tmp), fd) == NULL) {
+			fclose(fd);
+			goto skip_device;
+		}
+		read_product_id = strtoul(tmp, NULL, 16);
+
+		fclose(fd);
+
+		if (vendor_id == read_vendor_id &&
+		    product_id == read_product_id) {
+			path_copy = g_strdup(usb_dev);
+			matched_paths = g_slist_prepend(matched_paths,
+							path_copy);
+		}
+
+skip_device:
+		g_free(vendor_path);
+		g_free(product_path);
+	}
+	g_dir_close(devices_dir);
+
+	/* For every matched device try to find a ttyUSBX subfolder. */
+	for (l = matched_paths; l; l = l->next) {
+		subdir_path = NULL;
+
+		device_path = g_strconcat(device_tree, l->data, NULL);
+
+		if (!(device_dir = g_dir_open(device_path, 0, NULL))) {
+			g_free(device_path);
+			continue;
+		}
+
+		prefix = g_strconcat(l->data, ":", NULL);
+
+		while ((file = g_dir_read_name(device_dir))) {
+			if (g_str_has_prefix(file, prefix)) {
+				subdir_path = g_strconcat(device_path,
+						"/", file, NULL);
+				break;
+			}
+		}
+		g_dir_close(device_dir);
+
+		g_free(prefix);
+		g_free(device_path);
+
+		if (subdir_path) {
+			if (!(device_dir = g_dir_open(subdir_path, 0, NULL))) {
+				g_free(subdir_path);
+				continue;
+			}
+			g_free(subdir_path);
+
+			while ((file = g_dir_read_name(device_dir))) {
+				if (g_str_has_prefix(file, "ttyUSB")) {
+					tty_path = g_strconcat("/dev/",
+							       file, NULL);
+					sr_dbg("Found USB device %04x:%04x attached to %s.",
+					       vendor_id, product_id, tty_path);
+					tty_devs = g_slist_prepend(tty_devs,
+							tty_path);
+					break;
+				}
+			}
+			g_dir_close(device_dir);
+		}
+	}
+	g_slist_free_full(matched_paths, g_free);
+
+	return tty_devs;
+#else
+	(void)vendor_id;
+	(void)product_id;
+
+	return NULL;
+#endif
+}