scpi: Add enum scpi_transport_layer.

src/scpi.h

@@ -65,6 +65,16 @@ enum {
 	SCPI_CMD_GET_DIG_CHAN_NAME,
 };
 
+enum scpi_transport_layer {
+	SCPI_TRANSPORT_LIBGPIB,
+	SCPI_TRANSPORT_SERIAL,
+	SCPI_TRANSPORT_RAW_TCP,
+	SCPI_TRANSPORT_RIGOL_TCP,
+	SCPI_TRANSPORT_USBTMC,
+	SCPI_TRANSPORT_VISA,
+	SCPI_TRANSPORT_VXI,
+};
+
 struct scpi_command {
 	int command;
 	const char *string;
@@ -80,6 +90,7 @@ struct sr_scpi_hw_info {
 struct sr_scpi_dev_inst {
 	const char *name;
 	const char *prefix;
+	enum scpi_transport_layer transport;
 	int priv_size;
 	GSList *(*scan)(struct drv_context *drvc);
 	int (*dev_inst_new)(void *priv, struct drv_context *drvc,

src/scpi/scpi_libgpib.c

@@ -184,6 +184,7 @@ SR_PRIV int sr_scpi_gpib_spoll(struct sr_scpi_dev_inst *scpi, char *buf)
 SR_PRIV const struct sr_scpi_dev_inst scpi_libgpib_dev = {
 	.name          = "GPIB",
 	.prefix        = "libgpib",
+	.transport     = SCPI_TRANSPORT_LIBGPIB,
 	.priv_size     = sizeof(struct scpi_gpib),
 	.dev_inst_new  = scpi_gpib_dev_inst_new,
 	.open          = scpi_gpib_open,

src/scpi/scpi_serial.c

@@ -199,6 +199,7 @@ static void scpi_serial_free(void *priv)
 SR_PRIV const struct sr_scpi_dev_inst scpi_serial_dev = {
 	.name          = "serial",
 	.prefix        = "",
+	.transport     = SCPI_TRANSPORT_SERIAL,
 	.priv_size     = sizeof(struct scpi_serial),
 	.scan          = scpi_serial_scan,
 	.dev_inst_new  = scpi_serial_dev_inst_new,

src/scpi/scpi_tcp.c

@@ -274,6 +274,7 @@ static void scpi_tcp_free(void *priv)
 SR_PRIV const struct sr_scpi_dev_inst scpi_tcp_raw_dev = {
 	.name          = "RAW TCP",
 	.prefix        = "tcp-raw",
+	.transport     = SCPI_TRANSPORT_RAW_TCP,
 	.priv_size     = sizeof(struct scpi_tcp),
 	.dev_inst_new  = scpi_tcp_dev_inst_new,
 	.open          = scpi_tcp_open,
@@ -292,6 +293,7 @@ SR_PRIV const struct sr_scpi_dev_inst scpi_tcp_raw_dev = {
 SR_PRIV const struct sr_scpi_dev_inst scpi_tcp_rigol_dev = {
 	.name          = "RIGOL TCP",
 	.prefix        = "tcp-rigol",
+	.transport     = SCPI_TRANSPORT_RIGOL_TCP,
 	.priv_size     = sizeof(struct scpi_tcp),
 	.dev_inst_new  = scpi_tcp_dev_inst_new,
 	.open          = scpi_tcp_open,

src/scpi/scpi_usbtmc_libusb.c

@@ -670,6 +670,7 @@ static void scpi_usbtmc_libusb_free(void *priv)
 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
 	.name          = "USBTMC",
 	.prefix        = "usbtmc",
+	.transport     = SCPI_TRANSPORT_USBTMC,
 	.priv_size     = sizeof(struct scpi_usbtmc_libusb),
 	.scan          = scpi_usbtmc_libusb_scan,
 	.dev_inst_new  = scpi_usbtmc_libusb_dev_inst_new,

src/scpi/scpi_visa.c

@@ -166,6 +166,7 @@ static void scpi_visa_free(void *priv)
 SR_PRIV const struct sr_scpi_dev_inst scpi_visa_dev = {
 	.name          = "VISA",
 	.prefix        = "visa",
+	.transport     = SCPI_TRANSPORT_VISA,
 	.priv_size     = sizeof(struct scpi_visa),
 	.dev_inst_new  = scpi_visa_dev_inst_new,
 	.open          = scpi_visa_open,

src/scpi/scpi_vxi.c

@@ -231,6 +231,7 @@ static void scpi_vxi_free(void *priv)
 SR_PRIV const struct sr_scpi_dev_inst scpi_vxi_dev = {
 	.name          = "VXI",
 	.prefix        = "vxi",
+	.transport     = SCPI_TRANSPORT_VXI,
 	.priv_size     = sizeof(struct scpi_vxi),
 	.dev_inst_new  = scpi_vxi_dev_inst_new,
 	.open          = scpi_vxi_open,