From: Martin Ling <redacted>
Date: Sun, 28 Sep 2014 12:05:33 +0000 (+0100)
Subject: Add a timeout parameter to blocking serial calls.
X-Git-Tag: libsigrok-0.4.0~893
X-Git-Url: https://sigrok.org/gitweb/?p=libsigrok.git;a=commitdiff_plain;h=eead2782427ee5da9b793527f9484ac827a7bec5

Add a timeout parameter to blocking serial calls.

Set this new parameter to 0 (no timeout) at every call site. This is
consistent with previous behaviour, so cannot cause any regressions.

Waiting forever for a serial operation is clearly always wrong. Without
specific knowledge of each device and driver however, I can't choose
appropriate timeouts for each call. The maintainers of these drivers
will need to do so, and also add appropriate handling of timeouts.

When this commit is merged, a bug should be entered for each driver
that is touched by it.
---

diff --git a/src/hardware/agilent-dmm/api.c b/src/hardware/agilent-dmm/api.c
index b7ae7fb2..96b10d41 100644
--- a/src/hardware/agilent-dmm/api.c
+++ b/src/hardware/agilent-dmm/api.c
@@ -116,7 +116,7 @@ static GSList *scan(GSList *options)
 		return NULL;
 
 	serial_flush(serial);
-	if (serial_write_blocking(serial, "*IDN?\r\n", 7) < 7) {
+	if (serial_write_blocking(serial, "*IDN?\r\n", 7, 0) < 7) {
 		sr_err("Unable to send identification string.");
 		return NULL;
 	}
diff --git a/src/hardware/agilent-dmm/sched.c b/src/hardware/agilent-dmm/sched.c
index 5e8a968b..cb50c88a 100644
--- a/src/hardware/agilent-dmm/sched.c
+++ b/src/hardware/agilent-dmm/sched.c
@@ -140,7 +140,7 @@ static int agdmm_send(const struct sr_dev_inst *sdi, const char *cmd)
 		strcat(buf, "\r\n");
 	else
 		strcat(buf, "\n\r\n");
-	if (serial_write_blocking(serial, buf, strlen(buf)) < (int)strlen(buf)) {
+	if (serial_write_blocking(serial, buf, strlen(buf), 0) < (int)strlen(buf)) {
 		sr_err("Failed to send.");
 		return SR_ERR;
 	}
diff --git a/src/hardware/atten-pps3xxx/api.c b/src/hardware/atten-pps3xxx/api.c
index a0f84152..24b392ee 100644
--- a/src/hardware/atten-pps3xxx/api.c
+++ b/src/hardware/atten-pps3xxx/api.c
@@ -130,7 +130,7 @@ static GSList *scan(GSList *options, int modelid)
 	memset(packet, 0, PACKET_SIZE);
 	packet[0] = 0xaa;
 	packet[1] = 0xaa;
-	if (serial_write_blocking(serial, packet, PACKET_SIZE) < PACKET_SIZE) {
+	if (serial_write_blocking(serial, packet, PACKET_SIZE, 0) < PACKET_SIZE) {
 		sr_err("Unable to write while probing for hardware.");
 		return NULL;
 	}
diff --git a/src/hardware/atten-pps3xxx/protocol.c b/src/hardware/atten-pps3xxx/protocol.c
index 95137d2e..0db7e232 100644
--- a/src/hardware/atten-pps3xxx/protocol.c
+++ b/src/hardware/atten-pps3xxx/protocol.c
@@ -86,7 +86,7 @@ SR_PRIV void send_packet(const struct sr_dev_inst *sdi, uint8_t *packet)
 	struct sr_serial_dev_inst *serial;
 
 	serial = sdi->conn;
-	if (serial_write_blocking(serial, packet, PACKET_SIZE) < PACKET_SIZE)
+	if (serial_write_blocking(serial, packet, PACKET_SIZE, 0) < PACKET_SIZE)
 		sr_dbg("Failed to send packet.");
 	dump_packet("sent", packet);
 }
diff --git a/src/hardware/brymen-dmm/parser.c b/src/hardware/brymen-dmm/parser.c
index cfde37bf..c6de81f7 100644
--- a/src/hardware/brymen-dmm/parser.c
+++ b/src/hardware/brymen-dmm/parser.c
@@ -78,7 +78,7 @@ static int bm_send_command(uint8_t command, uint8_t arg1, uint8_t arg2,
 	/* TODO: How to compute the checksum? Hardware seems to ignore it. */
 
 	/* Request reading. */
-	written = serial_write_blocking(serial, &cmdout, sizeof(cmdout));
+	written = serial_write_blocking(serial, &cmdout, sizeof(cmdout), 0);
 	if (written != sizeof(cmdout))
 		return SR_ERR;
 
diff --git a/src/hardware/center-3xx/protocol.c b/src/hardware/center-3xx/protocol.c
index 82fa1909..e7af1039 100644
--- a/src/hardware/center-3xx/protocol.c
+++ b/src/hardware/center-3xx/protocol.c
@@ -31,7 +31,7 @@ static int center_send(struct sr_serial_dev_inst *serial, const char *cmd)
 {
 	int ret;
 
-	if ((ret = serial_write_blocking(serial, cmd, strlen(cmd))) < 0) {
+	if ((ret = serial_write_blocking(serial, cmd, strlen(cmd), 0)) < 0) {
 		sr_err("Error sending '%s' command: %d.", cmd, ret);
 		return SR_ERR;
 	}
diff --git a/src/hardware/colead-slm/protocol.c b/src/hardware/colead-slm/protocol.c
index 6864cb68..64ac12cb 100644
--- a/src/hardware/colead-slm/protocol.c
+++ b/src/hardware/colead-slm/protocol.c
@@ -207,7 +207,7 @@ SR_PRIV int colead_slm_receive_data(int fd, int revents, void *cb_data)
 			 * we don't want it. */
 			return TRUE;
 		/* Got 0x10, "measurement ready". */
-		if (serial_write_blocking(serial, "\x20", 1) < 1)
+		if (serial_write_blocking(serial, "\x20", 1, 0) < 1)
 			sr_err("unable to send command");
 		else {
 			devc->state = COMMAND_SENT;
diff --git a/src/hardware/conrad-digi-35-cpu/protocol.c b/src/hardware/conrad-digi-35-cpu/protocol.c
index 8068574a..caf1e85d 100644
--- a/src/hardware/conrad-digi-35-cpu/protocol.c
+++ b/src/hardware/conrad-digi-35-cpu/protocol.c
@@ -48,7 +48,7 @@ SR_PRIV int send_msg1(const struct sr_dev_inst *sdi, char cmd, int param)
 
 	sr_spew("send_msg1(): %c%c%c%c\\r", buf[0], buf[1], buf[2], buf[3]);
 
-	if (serial_write_blocking(serial, buf, sizeof(buf)) < (int)sizeof(buf)) {
+	if (serial_write_blocking(serial, buf, sizeof(buf), 0) < (int)sizeof(buf)) {
 		sr_err("Write error for cmd=%c", cmd);
 		return SR_ERR;
 	}
diff --git a/src/hardware/fluke-dmm/api.c b/src/hardware/fluke-dmm/api.c
index edd737e2..f7c39c85 100644
--- a/src/hardware/fluke-dmm/api.c
+++ b/src/hardware/fluke-dmm/api.c
@@ -90,7 +90,7 @@ static GSList *fluke_scan(const char *conn, const char *serialcomm)
 	while (!devices && retry < 3) {
 		retry++;
 		serial_flush(serial);
-		if (serial_write_blocking(serial, "ID\r", 3) < 0) {
+		if (serial_write_blocking(serial, "ID\r", 3, 0) < 0) {
 			sr_err("Unable to send ID string");
 			continue;
 		}
@@ -286,7 +286,7 @@ static int dev_acquisition_start(const struct sr_dev_inst *sdi, void *cb_data)
 	serial_source_add(sdi->session, serial, G_IO_IN, 50,
 			fluke_receive_data, (void *)sdi);
 
-	if (serial_write_blocking(serial, "QM\r", 3) < 0) {
+	if (serial_write_blocking(serial, "QM\r", 3, 0) < 0) {
 		sr_err("Unable to send QM.");
 		return SR_ERR;
 	}
diff --git a/src/hardware/fluke-dmm/fluke.c b/src/hardware/fluke-dmm/fluke.c
index 1110981b..4a1d5c82 100644
--- a/src/hardware/fluke-dmm/fluke.c
+++ b/src/hardware/fluke-dmm/fluke.c
@@ -456,7 +456,7 @@ static void handle_line(const struct sr_dev_inst *sdi)
 					/* Slip the request in now, before the main
 					 * timer loop asks for metadata again. */
 					n = sprintf(cmd, "QM %d\r", devc->meas_type);
-					if (serial_write_blocking(serial, cmd, n) < 0)
+					if (serial_write_blocking(serial, cmd, n, 0) < 0)
 						sr_err("Unable to send QM (measurement).");
 				}
 			} else {
@@ -525,7 +525,7 @@ SR_PRIV int fluke_receive_data(int fd, int revents, void *cb_data)
 	 * out-of-sync or temporary disconnect issues. */
 	if ((devc->expect_response == FALSE && elapsed > devc->profile->poll_period)
 			|| elapsed > devc->profile->timeout) {
-		if (serial_write_blocking(serial, "QM\r", 3) < 0)
+		if (serial_write_blocking(serial, "QM\r", 3, 0) < 0)
 			sr_err("Unable to send QM.");
 		devc->cmd_sent_at = now;
 		devc->expect_response = TRUE;
diff --git a/src/hardware/gmc-mh-1x-2x/protocol.c b/src/hardware/gmc-mh-1x-2x/protocol.c
index 53ff9b3b..11ca021e 100644
--- a/src/hardware/gmc-mh-1x-2x/protocol.c
+++ b/src/hardware/gmc-mh-1x-2x/protocol.c
@@ -1307,7 +1307,7 @@ int req_meas14(const struct sr_dev_inst *sdi)
 	devc->cmd_idx = 0;
 	create_cmd_14(devc->addr, 8, params, msg);
 	devc->req_sent_at = g_get_monotonic_time();
-	if (serial_write_blocking(serial, msg, sizeof(msg)) < (int)sizeof(msg)) {
+	if (serial_write_blocking(serial, msg, sizeof(msg), 0) < (int)sizeof(msg)) {
 		return SR_ERR;
 	}
 
@@ -1336,13 +1336,13 @@ int req_stat14(const struct sr_dev_inst *sdi, gboolean power_on)
 
 	if (power_on) {
 		sr_info("Write some data and wait 3s to turn on powered off device...");
-		if (serial_write_blocking(serial, msg, sizeof(msg)) < 0)
+		if (serial_write_blocking(serial, msg, sizeof(msg), 0) < 0)
 			return SR_ERR;
 		g_usleep(1*1000*1000);
-		if (serial_write_blocking(serial, msg, sizeof(msg)) < 0)
+		if (serial_write_blocking(serial, msg, sizeof(msg), 0) < 0)
 			return SR_ERR;
 		g_usleep(1*1000*1000);
-		if (serial_write_blocking(serial, msg, sizeof(msg)) < 0)
+		if (serial_write_blocking(serial, msg, sizeof(msg), 0) < 0)
 			return SR_ERR;
 		g_usleep(1*1000*1000);
 		serial_flush(serial);
@@ -1350,7 +1350,7 @@ int req_stat14(const struct sr_dev_inst *sdi, gboolean power_on)
 
 	/* Write message and wait for reply */
 	devc->req_sent_at = g_get_monotonic_time();
-	if (serial_write_blocking(serial, msg, sizeof(msg)) < (int)sizeof(msg)) {
+	if (serial_write_blocking(serial, msg, sizeof(msg), 0) < (int)sizeof(msg)) {
 		return SR_ERR;
 	}
 
@@ -1529,7 +1529,7 @@ SR_PRIV int config_set(uint32_t key, GVariant *data, const struct sr_dev_inst *s
 		params[0] = 5;
 		params[1] = 5;
 		create_cmd_14(devc->addr, 6, params, msg);
-		if (serial_write_blocking(sdi->conn, msg, sizeof(msg)) < 0)
+		if (serial_write_blocking(sdi->conn, msg, sizeof(msg), 0) < 0)
 			return SR_ERR;
 		else
 			g_usleep(2000000); /* Wait to ensure transfer before interface switched off. */
diff --git a/src/hardware/manson-hcs-3xxx/protocol.c b/src/hardware/manson-hcs-3xxx/protocol.c
index a57c92d9..cb333149 100644
--- a/src/hardware/manson-hcs-3xxx/protocol.c
+++ b/src/hardware/manson-hcs-3xxx/protocol.c
@@ -43,7 +43,7 @@ SR_PRIV int hcs_send_cmd(struct sr_serial_dev_inst *serial, const char *cmd, ...
 	sr_dbg("Sending '%s'.", cmd_esc);
 	g_free(cmd_esc);
 
-	if ((ret = serial_write_blocking(serial, cmdbuf, strlen(cmdbuf))) < 0) {
+	if ((ret = serial_write_blocking(serial, cmdbuf, strlen(cmdbuf), 0)) < 0) {
 		sr_err("Error sending command: %d.", ret);
 		return ret;
 	}
@@ -72,7 +72,7 @@ SR_PRIV int hcs_read_reply(struct sr_serial_dev_inst *serial, int lines, char* b
 		return SR_ERR_ARG;
 
 	while ((l_recv < lines) && (bufpos < (buflen + 1))) {
-		retc = serial_read_blocking(serial, &buf[bufpos], 1);
+		retc = serial_read_blocking(serial, &buf[bufpos], 1, 0);
 		if (retc != 1)
 			return SR_ERR;
 		if (buf[bufpos] == '\r')
@@ -177,7 +177,7 @@ static int handle_new_data(struct sr_dev_inst *sdi)
 	devc = sdi->priv;
 	serial = sdi->conn;
 
-	len = serial_read_blocking(serial, devc->buf + devc->buflen, 1);
+	len = serial_read_blocking(serial, devc->buf + devc->buflen, 1, 0);
 	if (len < 1)
 		return SR_ERR;
 
diff --git a/src/hardware/mic-985xx/protocol.c b/src/hardware/mic-985xx/protocol.c
index 9d0e603b..6243db15 100644
--- a/src/hardware/mic-985xx/protocol.c
+++ b/src/hardware/mic-985xx/protocol.c
@@ -24,7 +24,7 @@ static int mic_send(struct sr_serial_dev_inst *serial, const char *cmd)
 {
 	int ret;
 
-	if ((ret = serial_write_blocking(serial, cmd, strlen(cmd))) < 0) {
+	if ((ret = serial_write_blocking(serial, cmd, strlen(cmd), 0)) < 0) {
 		sr_err("Error sending '%s' command: %d.", cmd, ret);
 		return SR_ERR;
 	}
diff --git a/src/hardware/motech-lps-30x/api.c b/src/hardware/motech-lps-30x/api.c
index 79a32aa4..81ae3ef6 100644
--- a/src/hardware/motech-lps-30x/api.c
+++ b/src/hardware/motech-lps-30x/api.c
@@ -146,7 +146,7 @@ SR_PRIV int lps_send_va(struct sr_serial_dev_inst *serial, const char* fmt, va_l
 
 	sr_spew("lps_send_va: \"%s\"", buf);
 
-	retc = serial_write_blocking(serial, buf, strlen(buf));
+	retc = serial_write_blocking(serial, buf, strlen(buf), 0);
 
 	if (retc < 0)
 		return SR_ERR;
diff --git a/src/hardware/norma-dmm/api.c b/src/hardware/norma-dmm/api.c
index 93c9a79d..f95e7398 100644
--- a/src/hardware/norma-dmm/api.c
+++ b/src/hardware/norma-dmm/api.c
@@ -129,7 +129,7 @@ static GSList *do_scan(struct sr_dev_driver* drv, GSList *options)
 		 nmadmm_requests[NMADMM_REQ_IDN].req_str);
 	g_usleep(150 * 1000); /* Wait a little to allow serial port to settle. */
 	for (cnt = 0; cnt < 7; cnt++) {
-		if (serial_write_blocking(serial, req, strlen(req)) < 0) {
+		if (serial_write_blocking(serial, req, strlen(req), 0) < 0) {
 			sr_err("Unable to send identification request.");
 			return NULL;
 		}
diff --git a/src/hardware/norma-dmm/protocol.c b/src/hardware/norma-dmm/protocol.c
index 035e991e..d6733b2f 100644
--- a/src/hardware/norma-dmm/protocol.c
+++ b/src/hardware/norma-dmm/protocol.c
@@ -48,7 +48,7 @@ static int nma_send_req(const struct sr_dev_inst *sdi, int req, char *params)
 	devc->last_req = req;
 	devc->last_req_pending = TRUE;
 
-	if (serial_write_blocking(serial, buf, len) < 0) {
+	if (serial_write_blocking(serial, buf, len, 0) < 0) {
 		sr_err("Unable to send request.");
 		devc->last_req_pending = FALSE;
 		return SR_ERR;
diff --git a/src/hardware/openbench-logic-sniffer/api.c b/src/hardware/openbench-logic-sniffer/api.c
index 8ed13d00..9753d0b6 100644
--- a/src/hardware/openbench-logic-sniffer/api.c
+++ b/src/hardware/openbench-logic-sniffer/api.c
@@ -161,7 +161,7 @@ static GSList *scan(GSList *options)
 
 	if (probefd.revents != G_IO_IN)
 		return NULL;
-	if (serial_read_blocking(serial, buf, 4) != 4)
+	if (serial_read_blocking(serial, buf, 4, 0) != 4)
 		return NULL;
 	if (strncmp(buf, "1SLO", 4) && strncmp(buf, "1ALS", 4))
 		return NULL;
diff --git a/src/hardware/openbench-logic-sniffer/protocol.c b/src/hardware/openbench-logic-sniffer/protocol.c
index a20d674b..3d5ee6e2 100644
--- a/src/hardware/openbench-logic-sniffer/protocol.c
+++ b/src/hardware/openbench-logic-sniffer/protocol.c
@@ -30,7 +30,7 @@ SR_PRIV int send_shortcommand(struct sr_serial_dev_inst *serial,
 
 	sr_dbg("Sending cmd 0x%.2x.", command);
 	buf[0] = command;
-	if (serial_write_blocking(serial, buf, 1) != 1)
+	if (serial_write_blocking(serial, buf, 1, 0) != 1)
 		return SR_ERR;
 
 	return SR_OK;
@@ -48,7 +48,7 @@ SR_PRIV int send_longcommand(struct sr_serial_dev_inst *serial,
 	buf[2] = data[1];
 	buf[3] = data[2];
 	buf[4] = data[3];
-	if (serial_write_blocking(serial, buf, 5) != 5)
+	if (serial_write_blocking(serial, buf, 5, 0) != 5)
 		return SR_ERR;
 
 	return SR_OK;
@@ -155,7 +155,7 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
 
 	key = 0xff;
 	while (key) {
-		if (serial_read_blocking(serial, &key, 1) != 1)
+		if (serial_read_blocking(serial, &key, 1, 0) != 1)
 			break;
 		if (key == 0x00) {
 			sr_dbg("Got metadata key 0x00, metadata ends.");
@@ -167,7 +167,7 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
 		case 0:
 			/* NULL-terminated string */
 			tmp_str = g_string_new("");
-			while (serial_read_blocking(serial, &tmp_c, 1) == 1 && tmp_c != '\0')
+			while (serial_read_blocking(serial, &tmp_c, 1, 0) == 1 && tmp_c != '\0')
 				g_string_append_c(tmp_str, tmp_c);
 			sr_dbg("Got metadata key 0x%.2x value '%s'.",
 			       key, tmp_str->str);
@@ -199,7 +199,7 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
 			break;
 		case 1:
 			/* 32-bit unsigned integer */
-			if (serial_read_blocking(serial, &tmp_int, 4) != 4)
+			if (serial_read_blocking(serial, &tmp_int, 4, 0) != 4)
 				break;
 			tmp_int = RB32(&tmp_int);
 			sr_dbg("Got metadata key 0x%.2x value 0x%.8x.",
@@ -238,7 +238,7 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
 			break;
 		case 2:
 			/* 8-bit unsigned integer */
-			if (serial_read_blocking(serial, &tmp_c, 1) != 1)
+			if (serial_read_blocking(serial, &tmp_c, 1, 0) != 1)
 				break;
 			sr_dbg("Got metadata key 0x%.2x value 0x%.2x.",
 			       key, tmp_c);
diff --git a/src/hardware/tondaj-sl-814/protocol.c b/src/hardware/tondaj-sl-814/protocol.c
index d4f89b7f..b27388d1 100644
--- a/src/hardware/tondaj-sl-814/protocol.c
+++ b/src/hardware/tondaj-sl-814/protocol.c
@@ -133,14 +133,14 @@ int tondaj_sl_814_receive_data(int fd, int revents, void *cb_data)
 		buf[2] = 0x0d;
 		sr_spew("Sending init command: %02x %02x %02x.",
 			buf[0], buf[1], buf[2]);
-		if ((ret = serial_write_blocking(serial, buf, 3)) < 0) {
+		if ((ret = serial_write_blocking(serial, buf, 3, 0)) < 0) {
 			sr_err("Error sending init command: %d.", ret);
 			return FALSE;
 		}
 		devc->state = GET_INIT_REPLY;
 	} else if (devc->state == GET_INIT_REPLY) {
 		/* If we just sent the "init" command, get its reply. */
-		if ((ret = serial_read_blocking(serial, buf, 2)) < 0) {
+		if ((ret = serial_read_blocking(serial, buf, 2, 0)) < 0) {
 			sr_err("Error reading init reply: %d.", ret);
 			return FALSE;
 		}
@@ -159,7 +159,7 @@ int tondaj_sl_814_receive_data(int fd, int revents, void *cb_data)
 		buf[2] = 0x0d;
 		sr_spew("Sending data request command: %02x %02x %02x.",
 			buf[0], buf[1], buf[2]);
-		if ((ret = serial_write_blocking(serial, buf, 3)) < 0) {
+		if ((ret = serial_write_blocking(serial, buf, 3, 0)) < 0) {
 			sr_err("Error sending request command: %d.", ret);
 			return FALSE;
 		}
diff --git a/src/libsigrok-internal.h b/src/libsigrok-internal.h
index 655fdeb6..d5b6504a 100644
--- a/src/libsigrok-internal.h
+++ b/src/libsigrok-internal.h
@@ -630,11 +630,11 @@ SR_PRIV int serial_open(struct sr_serial_dev_inst *serial, int flags);
 SR_PRIV int serial_close(struct sr_serial_dev_inst *serial);
 SR_PRIV int serial_flush(struct sr_serial_dev_inst *serial);
 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);
 SR_PRIV int serial_write_nonblocking(struct sr_serial_dev_inst *serial,
 		const void *buf, size_t count);
 SR_PRIV int serial_read_blocking(struct sr_serial_dev_inst *serial, void *buf,
-		size_t count);
+		size_t count, unsigned int timeout_ms);
 SR_PRIV int serial_read_nonblocking(struct sr_serial_dev_inst *serial, void *buf,
 		size_t count);
 SR_PRIV int serial_set_params(struct sr_serial_dev_inst *serial, int baudrate,
diff --git a/src/serial.c b/src/serial.c
index 4fe9b88f..63ffbe22 100644
--- a/src/serial.c
+++ b/src/serial.c
@@ -170,7 +170,7 @@ SR_PRIV int serial_flush(struct sr_serial_dev_inst *serial)
 }
 
 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 +188,7 @@ 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:
@@ -212,15 +212,17 @@ 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.
  */
 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);
 }
 
 /**
@@ -237,11 +239,11 @@ SR_PRIV int serial_write_blocking(struct sr_serial_dev_inst *serial,
 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 +261,7 @@ 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:
@@ -284,15 +286,17 @@ 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 other      The number of bytes read. If this is less than the number
+ * requested, the timeout was reached.
  */
 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);
 }
 
 /**
@@ -310,7 +314,7 @@ SR_PRIV int serial_read_blocking(struct sr_serial_dev_inst *serial, void *buf,
 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);
 }
 
 /**