]> sigrok.org Git - libsigrok.git/blobdiff - src/scpi/scpi.c
SCPI: add sr_scpi_write_data()
[libsigrok.git] / src / scpi / scpi.c
index 38e322f5ffb7190e9998d81fa69c7e0ef80f441c..48e6a48495c9bfaba591147a12f715b67fe0b493 100644 (file)
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "libsigrok.h"
-#include "libsigrok-internal.h"
-
+#include <config.h>
 #include <glib.h>
 #include <string.h>
+#include <libsigrok/libsigrok.h>
+#include "libsigrok-internal.h"
+#include "scpi.h"
 
 #define LOG_PREFIX "scpi"
 
 #define SCPI_READ_RETRIES 100
-#define SCPI_READ_RETRY_TIMEOUT 10000
+#define SCPI_READ_RETRY_TIMEOUT_US (10 * 1000)
 
 /**
  * Parse a string representation of a boolean-like value into a gboolean.
@@ -89,7 +90,7 @@ static const struct sr_scpi_dev_inst *scpi_devs[] = {
        &scpi_libgpib_dev,
 #endif
 #ifdef HAVE_LIBSERIALPORT
-       &scpi_serial_dev,  /* must be last as it matches any resource */
+       &scpi_serial_dev, /* Must be last as it matches any resource. */
 #endif
 };
 
@@ -109,12 +110,16 @@ static struct sr_dev_inst *sr_scpi_scan_resource(struct drv_context *drvc,
                return NULL;
        };
 
-       if ((sdi = probe_device(scpi)))
-               return sdi;
+       sdi = probe_device(scpi);
 
        sr_scpi_close(scpi);
-       sr_scpi_free(scpi);
-       return NULL;
+
+       if (sdi)
+               sdi->status = SR_ST_INACTIVE;
+       else
+               sr_scpi_free(scpi);
+
+       return sdi;
 }
 
 SR_PRIV GSList *sr_scpi_scan(struct drv_context *drvc, GSList *options,
@@ -148,8 +153,10 @@ SR_PRIV GSList *sr_scpi_scan(struct drv_context *drvc, GSList *options,
                for (l = resources; l; l = l->next) {
                        res = g_strsplit(l->data, ":", 2);
                        if (res[0] && (sdi = sr_scpi_scan_resource(drvc, res[0],
-                                      serialcomm ? serialcomm : res[1], probe_device)))
+                                      serialcomm ? serialcomm : res[1], probe_device))) {
                                devices = g_slist_append(devices, sdi);
+                               sdi->connection_id = g_strdup(l->data);
+                       }
                        g_strfreev(res);
                }
                g_slist_free_full(resources, g_free);
@@ -157,7 +164,8 @@ SR_PRIV GSList *sr_scpi_scan(struct drv_context *drvc, GSList *options,
 
        if (!devices && resource) {
                sdi = sr_scpi_scan_resource(drvc, resource, serialcomm, probe_device);
-               devices = g_slist_append(NULL, sdi);
+               if (sdi)
+                       devices = g_slist_append(NULL, sdi);
        }
 
        /* Tack a copy of the newly found devices onto the driver list. */
@@ -182,6 +190,7 @@ SR_PRIV struct sr_scpi_dev_inst *scpi_dev_inst_new(struct drv_context *drvc,
                        scpi = g_malloc(sizeof(*scpi));
                        *scpi = *scpi_dev;
                        scpi->priv = g_malloc0(scpi->priv_size);
+                       scpi->read_timeout_us = 1000 * 1000;
                        params = g_strsplit(resource, "/", 0);
                        if (scpi->dev_inst_new(scpi->priv, drvc, resource,
                                               params, serialcomm) != SR_OK) {
@@ -205,7 +214,7 @@ SR_PRIV struct sr_scpi_dev_inst *scpi_dev_inst_new(struct drv_context *drvc,
  */
 SR_PRIV int sr_scpi_open(struct sr_scpi_dev_inst *scpi)
 {
-       return scpi->open(scpi->priv);
+       return scpi->open(scpi);
 }
 
 /**
@@ -287,8 +296,10 @@ SR_PRIV int sr_scpi_send_variadic(struct sr_scpi_dev_inst *scpi,
        va_end(args_copy);
 
        /* Allocate buffer and write out command. */
-       buf = g_malloc(len + 1);
+       buf = g_malloc0(len + 2);
        vsprintf(buf, format, args);
+       if (buf[len - 1] != '\n')
+               buf[len] = '\n';
 
        /* Send command. */
        ret = scpi->send(scpi->priv, buf);
@@ -326,6 +337,21 @@ SR_PRIV int sr_scpi_read_data(struct sr_scpi_dev_inst *scpi,
        return scpi->read_data(scpi->priv, buf, maxlen);
 }
 
+/**
+ * Send data to SCPI device.
+ *
+ * @param scpi Previously initialised SCPI device structure.
+ * @param buf Buffer with data to send.
+ * @param len Number of bytes to send.
+ *
+ * @return Number of bytes read, or SR_ERR upon failure.
+ */
+SR_PRIV int sr_scpi_write_data(struct sr_scpi_dev_inst *scpi,
+                       char *buf, int maxlen)
+{
+       return scpi->write_data(scpi->priv, buf, maxlen);
+}
+
 /**
  * Check whether a complete SCPI response has been received.
  *
@@ -347,18 +373,20 @@ SR_PRIV int sr_scpi_read_complete(struct sr_scpi_dev_inst *scpi)
  */
 SR_PRIV int sr_scpi_close(struct sr_scpi_dev_inst *scpi)
 {
-       return scpi->close(scpi->priv);
+       return scpi->close(scpi);
 }
 
 /**
  * Free SCPI device.
  *
- * @param scpi Previously initialized SCPI device structure.
- *
- * @return SR_OK on success, SR_ERR on failure.
+ * @param scpi Previously initialized SCPI device structure. If NULL,
+ *             this function does nothing.
  */
 SR_PRIV void sr_scpi_free(struct sr_scpi_dev_inst *scpi)
 {
+       if (!scpi)
+               return;
+
        scpi->free(scpi->priv);
        g_free(scpi->priv);
        g_free(scpi);
@@ -371,43 +399,112 @@ SR_PRIV void sr_scpi_free(struct sr_scpi_dev_inst *scpi)
  * @param command The SCPI command to send to the device (can be NULL).
  * @param scpi_response Pointer where to store the SCPI response.
  *
- * @return SR_OK on success, SR_ERR on failure.
+ * @return SR_OK on success, SR_ERR* on failure.
  */
 SR_PRIV int sr_scpi_get_string(struct sr_scpi_dev_inst *scpi,
                               const char *command, char **scpi_response)
 {
-       char buf[256];
-       int len;
        GString *response;
+       response = g_string_sized_new(1024);
 
-       if (command)
+       if (sr_scpi_get_data(scpi, command, &response) != SR_OK) {
+               if (response)
+                       g_string_free(response, TRUE);
+               return SR_ERR;
+       }
+
+       /* Get rid of trailing linefeed if present */
+       if (response->len >= 1 && response->str[response->len - 1] == '\n')
+               g_string_truncate(response, response->len - 1);
+
+       /* Get rid of trailing carriage return if present */
+       if (response->len >= 1 && response->str[response->len - 1] == '\r')
+               g_string_truncate(response, response->len - 1);
+
+       sr_spew("Got response: '%.70s', length %" G_GSIZE_FORMAT ".",
+               response->str, response->len);
+
+       *scpi_response = g_string_free(response, FALSE);
+
+       return SR_OK;
+}
+
+/**
+ * Do a non-blocking read of up to the allocated length, and
+ * check if a timeout has occured.
+ *
+ * @param scpi Previously initialised SCPI device structure.
+ * @param response Buffer to which the response is appended.
+ * @param abs_timeout_us Absolute timeout in microseconds
+ *
+ * @return read length on success, SR_ERR* on failure.
+ */
+SR_PRIV int sr_scpi_read_response(struct sr_scpi_dev_inst *scpi,
+                                 GString *response, gint64 abs_timeout_us)
+{
+       int len, space;
+
+       space = response->allocated_len - response->len;
+       len = sr_scpi_read_data(scpi, &response->str[response->len], space);
+
+       if (len < 0) {
+               sr_err("Incompletely read SCPI response.");
+               return SR_ERR;
+       }
+
+       if (len > 0) {
+               g_string_set_size(response, response->len + len);
+               return len;
+       }
+
+       if (g_get_monotonic_time() > abs_timeout_us) {
+               sr_err("Timed out waiting for SCPI response.");
+               return SR_ERR_TIMEOUT;
+       }
+
+       return 0;
+}
+
+SR_PRIV int sr_scpi_get_data(struct sr_scpi_dev_inst *scpi,
+                            const char *command, GString **scpi_response)
+{
+       int ret;
+       GString *response;
+       int space;
+       gint64 timeout;
+
+       /* Optionally send caller provided command. */
+       if (command) {
                if (sr_scpi_send(scpi, command) != SR_OK)
                        return SR_ERR;
+       }
 
+       /* Initiate SCPI read operation. */
        if (sr_scpi_read_begin(scpi) != SR_OK)
                return SR_ERR;
 
-       response = g_string_new("");
+       /* Keep reading until completion or until timeout. */
+       timeout = g_get_monotonic_time() + scpi->read_timeout_us;
 
-       *scpi_response = NULL;
+       response = *scpi_response;
 
        while (!sr_scpi_read_complete(scpi)) {
-               len = sr_scpi_read_data(scpi, buf, sizeof(buf));
-               if (len < 0) {
-                       g_string_free(response, TRUE);
-                       return SR_ERR;
+               /* Resize the buffer when free space drops below a threshold. */
+               space = response->allocated_len - response->len;
+               if (space < 128) {
+                       int oldlen = response->len;
+                       g_string_set_size(response, oldlen + 1024);
+                       g_string_set_size(response, oldlen);
                }
-               g_string_append_len(response, buf, len);
-       }
 
-       /* Get rid of trailing linefeed if present */
-       if (response->len >= 1 && response->str[response->len - 1] == '\n')
-               g_string_truncate(response, response->len - 1);
+               /* Read another chunk of the response. */
+               ret = sr_scpi_read_response(scpi, response, timeout);
 
-       *scpi_response = response->str;
-       g_string_free(response, FALSE);
-
-       sr_spew("Got response: '%.70s'.", *scpi_response);
+               if (ret < 0)
+                       return ret;
+               if (ret > 0)
+                       timeout = g_get_monotonic_time() + scpi->read_timeout_us;
+       }
 
        return SR_OK;
 }
@@ -420,7 +517,7 @@ SR_PRIV int sr_scpi_get_string(struct sr_scpi_dev_inst *scpi,
  * @param command The SCPI command to send to the device (can be NULL).
  * @param scpi_response Pointer where to store the parsed result.
  *
- * @return SR_OK on success, SR_ERR on failure.
+ * @return SR_OK on success, SR_ERR* on failure.
  */
 SR_PRIV int sr_scpi_get_bool(struct sr_scpi_dev_inst *scpi,
                             const char *command, gboolean *scpi_response)
@@ -430,14 +527,14 @@ SR_PRIV int sr_scpi_get_bool(struct sr_scpi_dev_inst *scpi,
 
        response = NULL;
 
-       if (sr_scpi_get_string(scpi, command, &response) != SR_OK)
-               if (!response)
-                       return SR_ERR;
+       ret = sr_scpi_get_string(scpi, command, &response);
+       if (ret != SR_OK && !response)
+               return ret;
 
        if (parse_strict_bool(response, scpi_response) == SR_OK)
                ret = SR_OK;
        else
-               ret = SR_ERR;
+               ret = SR_ERR_DATA;
 
        g_free(response);
 
@@ -452,7 +549,7 @@ SR_PRIV int sr_scpi_get_bool(struct sr_scpi_dev_inst *scpi,
  * @param command The SCPI command to send to the device (can be NULL).
  * @param scpi_response Pointer where to store the parsed result.
  *
- * @return SR_OK on success, SR_ERR on failure.
+ * @return SR_OK on success, SR_ERR* on failure.
  */
 SR_PRIV int sr_scpi_get_int(struct sr_scpi_dev_inst *scpi,
                            const char *command, int *scpi_response)
@@ -462,14 +559,14 @@ SR_PRIV int sr_scpi_get_int(struct sr_scpi_dev_inst *scpi,
 
        response = NULL;
 
-       if (sr_scpi_get_string(scpi, command, &response) != SR_OK)
-               if (!response)
-                       return SR_ERR;
+       ret = sr_scpi_get_string(scpi, command, &response);
+       if (ret != SR_OK && !response)
+               return ret;
 
        if (sr_atoi(response, scpi_response) == SR_OK)
                ret = SR_OK;
        else
-               ret = SR_ERR;
+               ret = SR_ERR_DATA;
 
        g_free(response);
 
@@ -484,7 +581,7 @@ SR_PRIV int sr_scpi_get_int(struct sr_scpi_dev_inst *scpi,
  * @param command The SCPI command to send to the device (can be NULL).
  * @param scpi_response Pointer where to store the parsed result.
  *
- * @return SR_OK on success, SR_ERR on failure.
+ * @return SR_OK on success, SR_ERR* on failure.
  */
 SR_PRIV int sr_scpi_get_float(struct sr_scpi_dev_inst *scpi,
                              const char *command, float *scpi_response)
@@ -494,14 +591,14 @@ SR_PRIV int sr_scpi_get_float(struct sr_scpi_dev_inst *scpi,
 
        response = NULL;
 
-       if (sr_scpi_get_string(scpi, command, &response) != SR_OK)
-               if (!response)
-                       return SR_ERR;
+       ret = sr_scpi_get_string(scpi, command, &response);
+       if (ret != SR_OK && !response)
+               return ret;
 
        if (sr_atof_ascii(response, scpi_response) == SR_OK)
                ret = SR_OK;
        else
-               ret = SR_ERR;
+               ret = SR_ERR_DATA;
 
        g_free(response);
 
@@ -516,7 +613,7 @@ SR_PRIV int sr_scpi_get_float(struct sr_scpi_dev_inst *scpi,
  * @param command The SCPI command to send to the device (can be NULL).
  * @param scpi_response Pointer where to store the parsed result.
  *
- * @return SR_OK on success, SR_ERR on failure.
+ * @return SR_OK on success, SR_ERR* on failure.
  */
 SR_PRIV int sr_scpi_get_double(struct sr_scpi_dev_inst *scpi,
                               const char *command, double *scpi_response)
@@ -526,14 +623,14 @@ SR_PRIV int sr_scpi_get_double(struct sr_scpi_dev_inst *scpi,
 
        response = NULL;
 
-       if (sr_scpi_get_string(scpi, command, &response) != SR_OK)
-               if (!response)
-                       return SR_ERR;
+       ret = sr_scpi_get_string(scpi, command, &response);
+       if (ret != SR_OK && !response)
+               return ret;
 
        if (sr_atod(response, scpi_response) == SR_OK)
                ret = SR_OK;
        else
-               ret = SR_ERR;
+               ret = SR_ERR_DATA;
 
        g_free(response);
 
@@ -546,18 +643,18 @@ SR_PRIV int sr_scpi_get_double(struct sr_scpi_dev_inst *scpi,
  *
  * @param scpi Previously initialised SCPI device structure.
  *
- * @return SR_OK on success, SR_ERR on failure.
+ * @return SR_OK on success, SR_ERR* on failure.
  */
 SR_PRIV int sr_scpi_get_opc(struct sr_scpi_dev_inst *scpi)
 {
        unsigned int i;
        gboolean opc;
 
-       for (i = 0; i < SCPI_READ_RETRIES; ++i) {
+       for (i = 0; i < SCPI_READ_RETRIES; i++) {
                sr_scpi_get_bool(scpi, SCPI_CMD_OPC, &opc);
                if (opc)
                        return SR_OK;
-               g_usleep(SCPI_READ_RETRY_TIMEOUT);
+               g_usleep(SCPI_READ_RETRY_TIMEOUT_US);
        }
 
        return SR_ERR;
@@ -571,7 +668,7 @@ SR_PRIV int sr_scpi_get_opc(struct sr_scpi_dev_inst *scpi)
  * @param command The SCPI command to send to the device (can be NULL).
  * @param scpi_response Pointer where to store the parsed result.
  *
- * @return SR_OK upon successfully parsing all values, SR_ERR upon a parsing
+ * @return SR_OK upon successfully parsing all values, SR_ERR* upon a parsing
  *         error or upon no response. The allocated response must be freed by
  *         the caller in the case of an SR_OK as well as in the case of
  *         parsing error.
@@ -585,13 +682,12 @@ SR_PRIV int sr_scpi_get_floatv(struct sr_scpi_dev_inst *scpi,
        gchar **ptr, **tokens;
        GArray *response_array;
 
-       ret = SR_OK;
        response = NULL;
        tokens = NULL;
 
-       if (sr_scpi_get_string(scpi, command, &response) != SR_OK)
-               if (!response)
-                       return SR_ERR;
+       ret = sr_scpi_get_string(scpi, command, &response);
+       if (ret != SR_OK && !response)
+               return ret;
 
        tokens = g_strsplit(response, ",", 0);
        ptr = tokens;
@@ -603,17 +699,17 @@ SR_PRIV int sr_scpi_get_floatv(struct sr_scpi_dev_inst *scpi,
                        response_array = g_array_append_val(response_array,
                                                            tmp);
                else
-                       ret = SR_ERR;
+                       ret = SR_ERR_DATA;
 
                ptr++;
        }
        g_strfreev(tokens);
        g_free(response);
 
-       if (ret == SR_ERR && response_array->len == 0) {
+       if (ret != SR_OK && response_array->len == 0) {
                g_array_free(response_array, TRUE);
                *scpi_response = NULL;
-               return SR_ERR;
+               return SR_ERR_DATA;
        }
 
        *scpi_response = response_array;
@@ -629,7 +725,7 @@ SR_PRIV int sr_scpi_get_floatv(struct sr_scpi_dev_inst *scpi,
  * @param command The SCPI command to send to the device (can be NULL).
  * @param scpi_response Pointer where to store the parsed result.
  *
- * @return SR_OK upon successfully parsing all values, SR_ERR upon a parsing
+ * @return SR_OK upon successfully parsing all values, SR_ERR* upon a parsing
  *         error or upon no response. The allocated response must be freed by
  *         the caller in the case of an SR_OK as well as in the case of
  *         parsing error.
@@ -642,13 +738,12 @@ SR_PRIV int sr_scpi_get_uint8v(struct sr_scpi_dev_inst *scpi,
        gchar **ptr, **tokens;
        GArray *response_array;
 
-       ret = SR_OK;
        response = NULL;
        tokens = NULL;
 
-       if (sr_scpi_get_string(scpi, command, &response) != SR_OK)
-               if (!response)
-                       return SR_ERR;
+       ret = sr_scpi_get_string(scpi, command, &response);
+       if (ret != SR_OK && !response)
+               return ret;
 
        tokens = g_strsplit(response, ",", 0);
        ptr = tokens;
@@ -660,7 +755,7 @@ SR_PRIV int sr_scpi_get_uint8v(struct sr_scpi_dev_inst *scpi,
                        response_array = g_array_append_val(response_array,
                                                            tmp);
                else
-                       ret = SR_ERR;
+                       ret = SR_ERR_DATA;
 
                ptr++;
        }
@@ -670,7 +765,7 @@ SR_PRIV int sr_scpi_get_uint8v(struct sr_scpi_dev_inst *scpi,
        if (response_array->len == 0) {
                g_array_free(response_array, TRUE);
                *scpi_response = NULL;
-               return SR_ERR;
+               return SR_ERR_DATA;
        }
 
        *scpi_response = response_array;
@@ -678,6 +773,123 @@ SR_PRIV int sr_scpi_get_uint8v(struct sr_scpi_dev_inst *scpi,
        return ret;
 }
 
+/**
+ * Send a SCPI command, read the reply, parse it as binary data with a
+ * "definite length block" header and store the as an result in scpi_response.
+ *
+ * @param scpi Previously initialised SCPI device structure.
+ * @param command The SCPI command to send to the device (can be NULL).
+ * @param scpi_response Pointer where to store the parsed result.
+ *
+ * @return SR_OK upon successfully parsing all values, SR_ERR* upon a parsing
+ *         error or upon no response. The allocated response must be freed by
+ *         the caller in the case of an SR_OK as well as in the case of
+ *         parsing error.
+ */
+SR_PRIV int sr_scpi_get_block(struct sr_scpi_dev_inst *scpi,
+                              const char *command, GByteArray **scpi_response)
+{
+       int ret;
+       GString* response;
+       char buf[10];
+       long llen;
+       long datalen;
+       gint64 timeout;
+
+       if (command)
+               if (sr_scpi_send(scpi, command) != SR_OK)
+                       return SR_ERR;
+
+       if (sr_scpi_read_begin(scpi) != SR_OK)
+               return SR_ERR;
+
+       /*
+        * Assume an initial maximum length, optionally gets adjusted below.
+        * Prepare a NULL return value for when error paths will be taken.
+        */
+       response = g_string_sized_new(1024);
+
+       timeout = g_get_monotonic_time() + scpi->read_timeout_us;
+
+       *scpi_response = NULL;
+
+       /* Get (the first chunk of) the response. */
+       while (response->len < 2) {
+               ret = sr_scpi_read_response(scpi, response, timeout);
+               if (ret < 0) {
+                       g_string_free(response, TRUE);
+                       return ret;
+               }
+       }
+
+       /*
+        * SCPI protocol data blocks are preceeded with a length spec.
+        * The length spec consists of a '#' marker, one digit which
+        * specifies the character count of the length spec, and the
+        * respective number of characters which specify the data block's
+        * length. Raw data bytes follow (thus one must no longer assume
+        * that the received input stream would be an ASCIIZ string).
+        *
+        * Get the data block length, and strip off the length spec from
+        * the input buffer, leaving just the data bytes.
+        */
+       if (response->str[0] != '#') {
+               g_string_free(response, TRUE);
+               return SR_ERR_DATA;
+       }
+       buf[0] = response->str[1];
+       buf[1] = '\0';
+       ret = sr_atol(buf, &llen);
+       if ((ret != SR_OK) || (llen == 0)) {
+               g_string_free(response, TRUE);
+               return ret;
+       }
+
+       while (response->len < (unsigned long)(2 + llen)) {
+               ret = sr_scpi_read_response(scpi, response, timeout);
+               if (ret < 0) {
+                       g_string_free(response, TRUE);
+                       return ret;
+               }
+       }
+
+       memcpy(buf, &response->str[2], llen);
+       buf[llen] = '\0';
+       ret = sr_atol(buf, &datalen);
+       if ((ret != SR_OK) || (datalen == 0)) {
+               g_string_free(response, TRUE);
+               return ret;
+       }
+       g_string_erase(response, 0, 2 + llen);
+
+       /*
+        * If the initially assumed length does not cover the data block
+        * length, then re-allocate the buffer size to the now known
+        * length, and keep reading more chunks of response data.
+        */
+       if (response->len < (unsigned long)(datalen)) {
+               int oldlen = response->len;
+               g_string_set_size(response, datalen);
+               g_string_set_size(response, oldlen);
+       }
+
+       while (response->len < (unsigned long)(datalen)) {
+               ret = sr_scpi_read_response(scpi, response, timeout);
+               if (ret < 0) {
+                       g_string_free(response, TRUE);
+                       return ret;
+               }
+               if (ret > 0)
+                       timeout = g_get_monotonic_time() + scpi->read_timeout_us;
+       }
+
+       /* Convert received data to byte array. */
+       *scpi_response = g_byte_array_new_take(
+               (guint8*)g_string_free(response, FALSE), datalen);
+
+       return SR_OK;
+}
+
 /**
  * Send the *IDN? SCPI command, receive the reply, parse it and store the
  * reply as a sr_scpi_hw_info structure in the supplied scpi_response pointer.
@@ -687,12 +899,12 @@ SR_PRIV int sr_scpi_get_uint8v(struct sr_scpi_dev_inst *scpi,
  * @param scpi Previously initialised SCPI device structure.
  * @param scpi_response Pointer where to store the hw_info structure.
  *
- * @return SR_OK upon success, SR_ERR on failure.
+ * @return SR_OK upon success, SR_ERR* on failure.
  */
 SR_PRIV int sr_scpi_get_hw_id(struct sr_scpi_dev_inst *scpi,
                              struct sr_scpi_hw_info **scpi_response)
 {
-       int num_tokens;
+       int num_tokens, ret;
        char *response;
        gchar **tokens;
        struct sr_scpi_hw_info *hw_info;
@@ -700,9 +912,9 @@ SR_PRIV int sr_scpi_get_hw_id(struct sr_scpi_dev_inst *scpi,
        response = NULL;
        tokens = NULL;
 
-       if (sr_scpi_get_string(scpi, SCPI_CMD_IDN, &response) != SR_OK)
-               if (!response)
-                       return SR_ERR;
+       ret = sr_scpi_get_string(scpi, SCPI_CMD_IDN, &response);
+       if (ret != SR_OK && !response)
+               return ret;
 
        sr_info("Got IDN string: '%s'", response);
 
@@ -715,24 +927,19 @@ SR_PRIV int sr_scpi_get_hw_id(struct sr_scpi_dev_inst *scpi,
 
        for (num_tokens = 0; tokens[num_tokens] != NULL; num_tokens++);
 
-       if (num_tokens != 4) {
+       if (num_tokens < 4) {
                sr_dbg("IDN response not according to spec: %80.s.", response);
                g_strfreev(tokens);
                g_free(response);
-               return SR_ERR;
+               return SR_ERR_DATA;
        }
        g_free(response);
 
-       hw_info = g_try_malloc(sizeof(struct sr_scpi_hw_info));
-       if (!hw_info) {
-               g_strfreev(tokens);
-               return SR_ERR_MALLOC;
-       }
-
-       hw_info->manufacturer = g_strdup(tokens[0]);
-       hw_info->model = g_strdup(tokens[1]);
-       hw_info->serial_number = g_strdup(tokens[2]);
-       hw_info->firmware_version = g_strdup(tokens[3]);
+       hw_info = g_malloc0(sizeof(struct sr_scpi_hw_info));
+       hw_info->manufacturer = g_strstrip(g_strdup(tokens[0]));
+       hw_info->model = g_strstrip(g_strdup(tokens[1]));
+       hw_info->serial_number = g_strstrip(g_strdup(tokens[2]));
+       hw_info->firmware_version = g_strstrip(g_strdup(tokens[3]));
 
        g_strfreev(tokens);
 
@@ -744,17 +951,17 @@ SR_PRIV int sr_scpi_get_hw_id(struct sr_scpi_dev_inst *scpi,
 /**
  * Free a sr_scpi_hw_info struct.
  *
- * @param hw_info Pointer to the struct to free.
- *
- * This function is safe to call with a NULL pointer.
+ * @param hw_info Pointer to the struct to free. If NULL, this
+ *                function does nothing.
  */
 SR_PRIV void sr_scpi_hw_info_free(struct sr_scpi_hw_info *hw_info)
 {
-       if (hw_info) {
-               g_free(hw_info->manufacturer);
-               g_free(hw_info->model);
-               g_free(hw_info->serial_number);
-               g_free(hw_info->firmware_version);
-               g_free(hw_info);
-       }
+       if (!hw_info)
+               return;
+
+       g_free(hw_info->manufacturer);
+       g_free(hw_info->model);
+       g_free(hw_info->serial_number);
+       g_free(hw_info->firmware_version);
+       g_free(hw_info);
 }