X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=src%2Fserial.c;h=aa8d4ddedf3b383fadbdf06bedbe062ba67f24c4;hb=7db9027985c2d59eccb0a20979bf5d7c699c8c8b;hp=4fe9b88fc0805e43b7716a4cdd1ace37501620a4;hpb=98edee7926b9827eec743bbfbfde9025089dc502;p=libsigrok.git

diff --git a/src/serial.c b/src/serial.c
index 4fe9b88f..aa8d4dde 100644
--- a/src/serial.c
+++ b/src/serial.c
@@ -4,6 +4,7 @@
  * 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>
+ * Copyright (C) 2014 Uffe Jakobsen <uffe@uffe.org>
  *
  * 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
@@ -19,28 +20,50 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
 #include <string.h>
 #include <stdlib.h>
 #include <glib.h>
 #include <glib/gstdio.h>
 #include <libserialport.h>
-#include "libsigrok.h"
+#include <libsigrok/libsigrok.h>
 #include "libsigrok-internal.h"
+#ifdef G_OS_WIN32
+#include <windows.h> /* for HANDLE */
+#endif
 
+/** @cond PRIVATE */
 #define LOG_PREFIX "serial"
+/** @endcond */
+
+/**
+ * @file
+ *
+ * Serial port handling.
+ */
+
+/**
+ * @defgroup grp_serial Serial port handling
+ *
+ * Serial port handling functions.
+ *
+ * @{
+ */
 
 /**
  * Open the specified serial port.
  *
  * @param serial Previously initialized serial port structure.
  * @param[in] flags Flags to use when opening the serial port. Possible flags
- *              include SERIAL_RDWR, SERIAL_RDONLY.
+ *                  include SERIAL_RDWR, SERIAL_RDONLY.
  *
  * If the serial structure contains a serialcomm string, it will be
  * passed to serial_set_paramstr() after the port is opened.
  *
  * @retval SR_OK Success.
  * @retval SR_ERR Failure.
+ *
+ * @private
  */
 SR_PRIV int serial_open(struct sr_serial_dev_inst *serial, int flags)
 {
@@ -89,6 +112,8 @@ SR_PRIV int serial_open(struct sr_serial_dev_inst *serial, int flags)
  *
  * @retval SR_OK Success.
  * @retval SR_ERR Failure.
+ *
+ * @private
  */
 SR_PRIV int serial_close(struct sr_serial_dev_inst *serial)
 {
@@ -134,6 +159,8 @@ SR_PRIV int serial_close(struct sr_serial_dev_inst *serial)
  *
  * @retval SR_OK Success.
  * @retval SR_ERR Failure.
+ *
+ * @private
  */
 SR_PRIV int serial_flush(struct sr_serial_dev_inst *serial)
 {
@@ -169,8 +196,48 @@ SR_PRIV int serial_flush(struct sr_serial_dev_inst *serial)
 	return SR_OK;
 }
 
+/**
+ * Drain serial port buffers.
+ *
+ * @param serial Previously initialized serial port structure.
+ *
+ * @retval SR_OK Success.
+ * @retval SR_ERR Failure.
+ *
+ * @private
+ */
+SR_PRIV int serial_drain(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 drain unopened serial port %s.", serial->port);
+		return SR_ERR;
+	}
+
+	sr_spew("Draining serial port %s.", serial->port);
+
+	ret = sp_drain(serial->data);
+
+	if (ret == SP_ERR_FAIL) {
+		error = sp_last_error_message();
+		sr_err("Error draining port (%d): %s.",
+			sp_last_error_code(), error);
+		sp_free_error_message(error);
+		return SR_ERR;
+	}
+
+	return SR_OK;
+}
+
 static int _serial_write(struct sr_serial_dev_inst *serial,
-		const void *buf, size_t count, int nonblocking)
+		const void *buf, size_t count, int nonblocking, unsigned int timeout_ms)
 {
 	ssize_t ret;
 	char *error;
@@ -188,7 +255,7 @@ static int _serial_write(struct sr_serial_dev_inst *serial,
 	if (nonblocking)
 		ret = sp_nonblocking_write(serial->data, buf, count);
 	else
-		ret = sp_blocking_write(serial->data, buf, count, 0);
+		ret = sp_blocking_write(serial->data, buf, count, timeout_ms);
 
 	switch (ret) {
 	case SP_ERR_ARG:
@@ -201,7 +268,7 @@ static int _serial_write(struct sr_serial_dev_inst *serial,
 		return SR_ERR;
 	}
 
-	sr_spew("Wrote %d/%d bytes.", ret, count);
+	sr_spew("Wrote %zd/%zu bytes.", ret, count);
 
 	return ret;
 }
@@ -212,15 +279,19 @@ static int _serial_write(struct sr_serial_dev_inst *serial,
  * @param serial Previously initialized serial port structure.
  * @param[in] buf Buffer containing the bytes to write.
  * @param[in] count Number of bytes to write.
+ * @param[in] timeout_ms Timeout in ms, or 0 for no timeout.
  *
  * @retval SR_ERR_ARG Invalid argument.
  * @retval SR_ERR Other error.
- * @retval other The number of bytes written.
+ * @retval other The number of bytes written. If this is less than the number
+ * specified in the call, the timeout was reached.
+ *
+ * @private
  */
 SR_PRIV int serial_write_blocking(struct sr_serial_dev_inst *serial,
-		const void *buf, size_t count)
+		const void *buf, size_t count, unsigned int timeout_ms)
 {
-	return _serial_write(serial, buf, count, 0);
+	return _serial_write(serial, buf, count, 0, timeout_ms);
 }
 
 /**
@@ -233,15 +304,17 @@ SR_PRIV int serial_write_blocking(struct sr_serial_dev_inst *serial,
  * @retval SR_ERR_ARG Invalid argument.
  * @retval SR_ERR Other error.
  * @retval other The number of bytes written.
-*/
+ *
+ * @private
+ */
 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);
+	return _serial_write(serial, buf, count, 1, 0);
 }
 
 static int _serial_read(struct sr_serial_dev_inst *serial, void *buf,
-		size_t count, int nonblocking)
+		size_t count, int nonblocking, unsigned int timeout_ms)
 {
 	ssize_t ret;
 	char *error;
@@ -259,7 +332,7 @@ static int _serial_read(struct sr_serial_dev_inst *serial, void *buf,
 	if (nonblocking)
 		ret = sp_nonblocking_read(serial->data, buf, count);
 	else
-		ret = sp_blocking_read(serial->data, buf, count, 0);
+		ret = sp_blocking_read(serial->data, buf, count, timeout_ms);
 
 	switch (ret) {
 	case SP_ERR_ARG:
@@ -273,7 +346,7 @@ static int _serial_read(struct sr_serial_dev_inst *serial, void *buf,
 	}
 
 	if (ret > 0)
-		sr_spew("Read %d/%d bytes.", ret, count);
+		sr_spew("Read %zd/%zu bytes.", ret, count);
 
 	return ret;
 }
@@ -284,15 +357,19 @@ static int _serial_read(struct sr_serial_dev_inst *serial, void *buf,
  * @param serial Previously initialized serial port structure.
  * @param buf Buffer where to store the bytes that are read.
  * @param[in] count The number of bytes to read.
+ * @param[in] timeout_ms Timeout in ms, or 0 for no timeout.
  *
  * @retval SR_ERR_ARG Invalid argument.
- * @retval SR_ERR     Other error.
- * @retval other      The number of bytes read.
+ * @retval SR_ERR Other error.
+ * @retval other The number of bytes read. If this is less than the number
+ * requested, the timeout was reached.
+ *
+ * @private
  */
 SR_PRIV int serial_read_blocking(struct sr_serial_dev_inst *serial, void *buf,
-		size_t count)
+		size_t count, unsigned int timeout_ms)
 {
-	return _serial_read(serial, buf, count, 0);
+	return _serial_read(serial, buf, count, 0, timeout_ms);
 }
 
 /**
@@ -304,13 +381,15 @@ SR_PRIV int serial_read_blocking(struct sr_serial_dev_inst *serial, void *buf,
  * @param[in] count The number of bytes to read.
  *
  * @retval SR_ERR_ARG Invalid argument.
- * @retval SR_ERR     Other error.
- * @retval other      The number of bytes read.
+ * @retval SR_ERR Other error.
+ * @retval other The number of bytes read.
+ *
+ * @private
  */
 SR_PRIV int serial_read_nonblocking(struct sr_serial_dev_inst *serial, void *buf,
 		size_t count)
 {
-	return _serial_read(serial, buf, count, 1);
+	return _serial_read(serial, buf, count, 1, 0);
 }
 
 /**
@@ -322,12 +401,14 @@ SR_PRIV int serial_read_nonblocking(struct sr_serial_dev_inst *serial, void *buf
  * @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).
+ *                        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.
+ *
+ * @private
  */
 SR_PRIV int serial_set_params(struct sr_serial_dev_inst *serial, int baudrate,
 			      int bits, int parity, int stopbits,
@@ -396,7 +477,7 @@ SR_PRIV int serial_set_params(struct sr_serial_dev_inst *serial, int baudrate,
  * @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
+ * 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
@@ -407,13 +488,18 @@ SR_PRIV int serial_set_params(struct sr_serial_dev_inst *serial, int baudrate,
  * 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.
+ *
+ * @private
  */
 SR_PRIV int serial_set_paramstr(struct sr_serial_dev_inst *serial,
 		const char *paramstr)
 {
+/** @cond PRIVATE */
 #define SERIAL_COMM_SPEC "^(\\d+)/([5678])([neo])([12])(.*)$"
+/** @endcond */
 
 	GRegex *reg;
 	GMatchInfo *match;
@@ -434,13 +520,13 @@ SR_PRIV int serial_set_paramstr(struct sr_serial_dev_inst *serial,
 		if ((mstr = g_match_info_fetch(match, 3))) {
 			switch (mstr[0]) {
 			case 'n':
-				parity = SERIAL_PARITY_NONE;
+				parity = SP_PARITY_NONE;
 				break;
 			case 'e':
-				parity = SERIAL_PARITY_EVEN;
+				parity = SP_PARITY_EVEN;
 				break;
 			case 'o':
-				parity = SERIAL_PARITY_ODD;
+				parity = SP_PARITY_ODD;
 				break;
 			}
 		}
@@ -518,6 +604,8 @@ SR_PRIV int serial_set_paramstr(struct sr_serial_dev_inst *serial,
  *
  * @retval SR_OK Success.
  * @retval SR_ERR Failure.
+ *
+ * @private
  */
 SR_PRIV int serial_readline(struct sr_serial_dev_inst *serial, char **buf,
 		int *buflen, gint64 timeout_ms)
@@ -540,7 +628,7 @@ SR_PRIV int serial_readline(struct sr_serial_dev_inst *serial, char **buf,
 
 	maxlen = *buflen;
 	*buflen = len = 0;
-	while(1) {
+	while (1) {
 		len = maxlen - *buflen - 1;
 		if (len < 1)
 			break;
@@ -578,13 +666,15 @@ SR_PRIV int serial_readline(struct sr_serial_dev_inst *serial, char **buf,
  * @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.
+ *                       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.
+ *                     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.
+ *
+ * @private
  */
 SR_PRIV int serial_stream_detect(struct sr_serial_dev_inst *serial,
 				 uint8_t *buf, size_t *buflen,
@@ -594,7 +684,7 @@ SR_PRIV int serial_stream_detect(struct sr_serial_dev_inst *serial,
 {
 	uint64_t start, time, byte_delay_us;
 	size_t ibuf, i, maxlen;
-	int len;
+	ssize_t len;
 
 	maxlen = *buflen;
 
@@ -607,7 +697,7 @@ SR_PRIV int serial_stream_detect(struct sr_serial_dev_inst *serial,
 	}
 
 	/* Assume 8n1 transmission. That is 10 bits for every byte. */
-	byte_delay_us = 10 * (1000000 / baudrate);
+	byte_delay_us = 10 * ((1000 * 1000) / baudrate);
 	start = g_get_monotonic_time();
 
 	i = ibuf = len = 0;
@@ -627,12 +717,12 @@ SR_PRIV int serial_stream_detect(struct sr_serial_dev_inst *serial,
 		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 "
+				sr_spew("Found valid %zu-byte packet after "
 					"%" PRIu64 "ms.", (ibuf - i), time);
 				*buflen = ibuf;
 				return SR_OK;
 			} else {
-				sr_spew("Got %d bytes, but not a valid "
+				sr_spew("Got %zu bytes, but not a valid "
 					"packet.", (ibuf - i));
 			}
 			/* Not a valid packet. Continue searching. */
@@ -640,7 +730,7 @@ SR_PRIV int serial_stream_detect(struct sr_serial_dev_inst *serial,
 		}
 		if (time >= timeout_ms) {
 			/* Timeout */
-			sr_dbg("Detection timed out after %dms.", time);
+			sr_dbg("Detection timed out after %" PRIu64 "ms.", time);
 			break;
 		}
 		if (len < 1)
@@ -649,7 +739,7 @@ SR_PRIV int serial_stream_detect(struct sr_serial_dev_inst *serial,
 
 	*buflen = ibuf;
 
-	sr_err("Didn't find a valid packet (read %d bytes).", *buflen);
+	sr_err("Didn't find a valid packet (read %zu bytes).", *buflen);
 
 	return SR_ERR;
 }
@@ -658,12 +748,14 @@ SR_PRIV int serial_stream_detect(struct sr_serial_dev_inst *serial,
  * 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_device Pointer where to store the extracted 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.
+ *
+ * @private
  */
 SR_PRIV int sr_serial_extract_options(GSList *options, const char **serial_device,
 				      const char **serial_options)
@@ -678,38 +770,47 @@ SR_PRIV int sr_serial_extract_options(GSList *options, const char **serial_devic
 		switch (src->key) {
 		case SR_CONF_CONN:
 			*serial_device = g_variant_get_string(src->data, NULL);
-			sr_dbg("Parsed serial device: %s", *serial_device);
+			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);
+			sr_dbg("Parsed serial options: %s.", *serial_options);
 			break;
 		}
 	}
 
 	if (!*serial_device) {
-		sr_dbg("No serial device specified");
+		sr_dbg("No serial device specified.");
 		return SR_ERR;
 	}
 
 	return SR_OK;
 }
 
-#ifdef _WIN32
+/** @cond PRIVATE */
+#ifdef G_OS_WIN32
 typedef HANDLE event_handle;
 #else
 typedef int event_handle;
 #endif
+/** @endcond */
 
+/** @private */
 SR_PRIV int serial_source_add(struct sr_session *session,
 		struct sr_serial_dev_inst *serial, int events, int timeout,
 		sr_receive_data_callback cb, void *cb_data)
 {
+	struct sp_event_set *event_set;
+	gintptr poll_fd;
+	unsigned int poll_events;
 	enum sp_event mask = 0;
-	unsigned int i;
 
-	if (sp_new_event_set(&serial->event_set) != SP_OK)
+	if ((events & (G_IO_IN|G_IO_ERR)) && (events & G_IO_OUT)) {
+		sr_err("Cannot poll input/error and output simultaneously.");
+		return SR_ERR_ARG;
+	}
+
+	if (sp_new_event_set(&event_set) != SP_OK)
 		return SR_ERR;
 
 	if (events & G_IO_IN)
@@ -719,50 +820,114 @@ SR_PRIV int serial_source_add(struct sr_session *session,
 	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);
+	if (sp_add_port_events(event_set, serial->data, mask) != SP_OK) {
+		sp_free_event_set(event_set);
+		return SR_ERR;
+	}
+	if (event_set->count != 1) {
+		sr_err("Unexpected number (%u) of event handles to poll.",
+			event_set->count);
+		sp_free_event_set(event_set);
 		return SR_ERR;
 	}
 
-	serial->pollfds = (GPollFD *) g_malloc0(sizeof(GPollFD) * serial->event_set->count);
+	poll_fd = (gintptr) ((event_handle *)event_set->handles)[0];
+	mask = event_set->masks[0];
+
+	sp_free_event_set(event_set);
+
+	poll_events = 0;
+	if (mask & SP_EVENT_RX_READY)
+		poll_events |= G_IO_IN;
+	if (mask & SP_EVENT_TX_READY)
+		poll_events |= G_IO_OUT;
+	if (mask & SP_EVENT_ERROR)
+		poll_events |= G_IO_ERR;
+	/*
+	 * Using serial->data as the key for the event source is not quite
+	 * proper, as it makes it impossible to create another event source
+	 * for the same serial port. However, these fixed keys will soon be
+	 * removed from the API anyway, so this is OK for now.
+	 */
+	return sr_session_fd_source_add(session, serial->data,
+			poll_fd, poll_events, timeout, cb, cb_data);
+}
 
-	for (i = 0; i < serial->event_set->count; i++) {
+/** @private */
+SR_PRIV int serial_source_remove(struct sr_session *session,
+		struct sr_serial_dev_inst *serial)
+{
+	return sr_session_source_remove_internal(session, serial->data);
+}
 
-		serial->pollfds[i].fd = ((event_handle *) serial->event_set->handles)[i];
+/**
+ * Create/allocate a new sr_serial_port structure.
+ *
+ * @param name The OS dependent name of the serial port. Must not be NULL.
+ * @param description An end user friendly description for the serial port.
+ *                    Can be NULL (in that case the empty string is used
+ *                    as description).
+ *
+ * @return The newly allocated sr_serial_port struct.
+ */
+static struct sr_serial_port *sr_serial_new(const char *name,
+		const char *description)
+{
+	struct sr_serial_port *serial;
 
-		mask = serial->event_set->masks[i];
+	if (!name)
+		return NULL;
 
-		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;
+	serial = g_malloc(sizeof(struct sr_serial_port));
+	serial->name = g_strdup(name);
+	serial->description = g_strdup(description ? description : "");
 
-		if (sr_session_source_add_pollfd(session, &serial->pollfds[i],
-					timeout, cb, cb_data) != SR_OK)
-			return SR_ERR;
-	}
+	return serial;
+}
 
-	return SR_OK;
+/**
+ * Free a previously allocated sr_serial_port structure.
+ *
+ * @param serial The sr_serial_port struct to free. Must not be NULL.
+ */
+SR_API void sr_serial_free(struct sr_serial_port *serial)
+{
+	if (!serial)
+		return;
+	g_free(serial->name);
+	g_free(serial->description);
+	g_free(serial);
 }
 
-SR_PRIV int serial_source_remove(struct sr_session *session,
-		struct sr_serial_dev_inst *serial)
+/**
+ * List available serial devices.
+ *
+ * @return A GSList of strings containing the path of the serial devices or
+ *         NULL if no serial device is found. The returned list must be freed
+ *         by the caller.
+ */
+SR_API GSList *sr_serial_list(const struct sr_dev_driver *driver)
 {
-	unsigned int i;
+	GSList *tty_devs = NULL;
+	struct sp_port **ports;
+	struct sr_serial_port *port;
+	int i;
 
-	for (i = 0; i < serial->event_set->count; i++)
-		if (sr_session_source_remove_pollfd(session, &serial->pollfds[i]) != SR_OK)
-			return SR_ERR;
+	/* Currently unused, but will be used by some drivers later on. */
+	(void)driver;
+
+	if (sp_list_ports(&ports) != SP_OK)
+		return NULL;
 
-	g_free(serial->pollfds);
-	sp_free_event_set(serial->event_set);
+	for (i = 0; ports[i]; i++) {
+		port = sr_serial_new(sp_get_port_name(ports[i]),
+				     sp_get_port_description(ports[i]));
+		tty_devs = g_slist_append(tty_devs, port);
+	}
 
-	serial->pollfds = NULL;
-	serial->event_set = NULL;
+	sp_free_port_list(ports);
 
-	return SR_OK;
+	return tty_devs;
 }
 
 /**
@@ -774,6 +939,8 @@ SR_PRIV int serial_source_remove(struct sr_session *session,
  * @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.
+ *
+ * @private
  */
 SR_PRIV GSList *sr_serial_find_usb(uint16_t vendor_id, uint16_t product_id)
 {
@@ -784,13 +951,58 @@ SR_PRIV GSList *sr_serial_find_usb(uint16_t vendor_id, uint16_t product_id)
 	if (sp_list_ports(&ports) != SP_OK)
 		return NULL;
 
-	for (i=0; ports[i]; i++)
+	for (i = 0; ports[i]; i++)
 		if (sp_get_port_transport(ports[i]) == SP_TRANSPORT_USB &&
 		    sp_get_port_usb_vid_pid(ports[i], &vid, &pid) == SP_OK &&
-		    vid == vendor_id && pid == product_id)
+		    vid == vendor_id && pid == product_id) {
 			tty_devs = g_slist_prepend(tty_devs,
-			                           g_strdup(sp_get_port_name(ports[i])));
+					g_strdup(sp_get_port_name(ports[i])));
+		}
 
 	sp_free_port_list(ports);
+
 	return tty_devs;
 }
+
+/** @private */
+SR_PRIV int serial_timeout(struct sr_serial_dev_inst *port, int num_bytes)
+{
+	struct sp_port_config *config;
+	int timeout_ms, bits, baud, tmp;
+
+	/* Default to 1s. */
+	timeout_ms = 1000;
+
+	if (sp_new_config(&config) < 0)
+		return timeout_ms;
+
+	bits = baud = 0;
+	do {
+		if (sp_get_config(port->data, config) < 0)
+			break;
+
+		/* Start bit. */
+		bits = 1;
+		if (sp_get_config_bits(config, &tmp) < 0)
+			break;
+		bits += tmp;
+		if (sp_get_config_stopbits(config, &tmp) < 0)
+			break;
+		bits += tmp;
+		if (sp_get_config_baudrate(config, &tmp) < 0)
+			break;
+		baud = tmp;
+	} while (FALSE);
+
+	if (bits && baud) {
+		/* Throw in 10ms for misc OS overhead. */
+		timeout_ms = 10;
+		timeout_ms += ((1000.0 / baud) * bits) * num_bytes;
+	}
+
+	sp_free_config(config);
+
+	return timeout_ms;
+}
+
+/** @} */