2 * This file is part of the libsigrok project.
4 * Copyright (C) 2014 Aurelien Jacobs <aurel@gnuage.org>
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
23 #include <libsigrok/libsigrok.h>
24 #include "libsigrok-internal.h"
27 #define LOG_PREFIX "scpi_usbtmc"
29 #define MAX_TRANSFER_LENGTH 2048
30 #define TRANSFER_TIMEOUT 1000
32 struct scpi_usbtmc_libusb {
33 struct sr_context *ctx;
34 struct sr_usb_dev_inst *usb;
35 int detached_kernel_driver;
40 uint8_t usbtmc_int_cap;
41 uint8_t usbtmc_dev_cap;
42 uint8_t usb488_dev_cap;
44 uint8_t bulkin_attributes;
45 uint8_t buffer[MAX_TRANSFER_LENGTH];
47 int response_bytes_read;
51 /* Some USBTMC-specific enums, as defined in the USBTMC standard. */
52 #define SUBCLASS_USBTMC 0x03
53 #define USBTMC_USB488 0x01
56 /* USBTMC control requests */
57 INITIATE_ABORT_BULK_OUT = 1,
58 CHECK_ABORT_BULK_OUT_STATUS = 2,
59 INITIATE_ABORT_BULK_IN = 3,
60 CHECK_ABORT_BULK_IN_STATUS = 4,
62 CHECK_CLEAR_STATUS = 6,
66 /* USB488 control requests */
67 READ_STATUS_BYTE = 128,
73 /* USBTMC status codes */
74 #define USBTMC_STATUS_SUCCESS 0x01
76 /* USBTMC capabilities */
77 #define USBTMC_INT_CAP_LISTEN_ONLY 0x01
78 #define USBTMC_INT_CAP_TALK_ONLY 0x02
79 #define USBTMC_INT_CAP_INDICATOR 0x04
81 #define USBTMC_DEV_CAP_TERMCHAR 0x01
83 #define USB488_DEV_CAP_DT1 0x01
84 #define USB488_DEV_CAP_RL1 0x02
85 #define USB488_DEV_CAP_SR1 0x04
86 #define USB488_DEV_CAP_SCPI 0x08
88 /* Bulk messages constants */
89 #define USBTMC_BULK_HEADER_SIZE 12
91 /* Bulk MsgID values */
92 #define DEV_DEP_MSG_OUT 1
93 #define REQUEST_DEV_DEP_MSG_IN 2
94 #define DEV_DEP_MSG_IN 2
96 /* bmTransferAttributes */
98 #define TERM_CHAR_ENABLED 0x02
100 struct usbtmc_blacklist {
105 /* Devices that publish RL1 support, but don't support it. */
106 static struct usbtmc_blacklist blacklist_remote[] = {
107 { 0x1ab1, 0x0588 }, /* Rigol DS1000 series */
108 { 0x1ab1, 0x04b0 }, /* Rigol DS2000 series */
109 { 0x1ab1, 0x04b1 }, /* Rigol DS4000 series */
110 { 0x1ab1, 0x0515 }, /* Rigol MSO5000 series */
111 { 0x0957, 0x0588 }, /* Agilent DSO1000 series (rebadged Rigol DS1000) */
112 { 0x0b21, 0xffff }, /* All Yokogawa devices */
113 { 0xf4ec, 0xffff }, /* All Siglent SDS devices */
117 /* Devices that shall get reset during open(). */
118 static struct usbtmc_blacklist whitelist_usb_reset[] = {
119 { 0xf4ec, 0xffff }, /* All Siglent SDS devices */
123 static GSList *scpi_usbtmc_libusb_scan(struct drv_context *drvc)
125 struct libusb_device **devlist;
126 struct libusb_device_descriptor des;
127 struct libusb_config_descriptor *confdes;
128 const struct libusb_interface_descriptor *intfdes;
129 GSList *resources = NULL;
130 int confidx, intfidx, ret, i;
133 ret = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
135 sr_err("Failed to get device list: %s.",
136 libusb_error_name(ret));
139 for (i = 0; devlist[i]; i++) {
140 libusb_get_device_descriptor(devlist[i], &des);
142 for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
143 if ((ret = libusb_get_config_descriptor(devlist[i], confidx, &confdes)) < 0) {
144 if (ret != LIBUSB_ERROR_NOT_FOUND)
145 sr_dbg("Failed to get configuration descriptor: %s, "
146 "ignoring device.", libusb_error_name(ret));
149 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
150 intfdes = confdes->interface[intfidx].altsetting;
151 if (intfdes->bInterfaceClass != LIBUSB_CLASS_APPLICATION ||
152 intfdes->bInterfaceSubClass != SUBCLASS_USBTMC ||
153 intfdes->bInterfaceProtocol != USBTMC_USB488)
155 sr_dbg("Found USBTMC device (VID:PID = %04x:%04x, "
156 "bus.address = %d.%d).", des.idVendor, des.idProduct,
157 libusb_get_bus_number(devlist[i]),
158 libusb_get_device_address(devlist[i]));
159 res = g_strdup_printf("usbtmc/%d.%d",
160 libusb_get_bus_number(devlist[i]),
161 libusb_get_device_address(devlist[i]));
162 resources = g_slist_append(resources, res);
164 libusb_free_config_descriptor(confdes);
167 libusb_free_device_list(devlist, 1);
169 /* No log message for #devices found (caller will log that). */
174 static int scpi_usbtmc_libusb_dev_inst_new(void *priv, struct drv_context *drvc,
175 const char *resource, char **params, const char *serialcomm)
177 struct scpi_usbtmc_libusb *uscpi = priv;
183 if (!params || !params[1]) {
184 sr_err("Invalid parameters.");
188 uscpi->ctx = drvc->sr_ctx;
189 devices = sr_usb_find(uscpi->ctx->libusb_ctx, params[1]);
190 if (g_slist_length(devices) != 1) {
191 sr_err("Failed to find USB device '%s'.", params[1]);
192 g_slist_free_full(devices, (GDestroyNotify)sr_usb_dev_inst_free);
195 uscpi->usb = devices->data;
196 g_slist_free(devices);
201 static int check_usbtmc_blacklist(struct usbtmc_blacklist *blacklist,
202 uint16_t vid, uint16_t pid)
206 for (i = 0; blacklist[i].vid; i++) {
207 if ((blacklist[i].vid == vid && blacklist[i].pid == 0xFFFF) ||
208 (blacklist[i].vid == vid && blacklist[i].pid == pid))
215 static int scpi_usbtmc_remote(struct scpi_usbtmc_libusb *uscpi)
217 struct sr_usb_dev_inst *usb = uscpi->usb;
218 struct libusb_device *dev;
219 struct libusb_device_descriptor des;
223 if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
226 dev = libusb_get_device(usb->devhdl);
227 libusb_get_device_descriptor(dev, &des);
228 if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
231 sr_dbg("Locking out local control.");
232 ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
233 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
234 REN_CONTROL, 1, uscpi->interface, &status, 1, TRANSFER_TIMEOUT);
235 if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
237 sr_dbg("Failed to enter REN state: %s.", libusb_error_name(ret));
239 sr_dbg("Failed to enter REN state: USBTMC status %d.", status);
243 ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
244 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
245 LOCAL_LOCKOUT, 0, uscpi->interface, &status, 1,
247 if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
249 sr_dbg("Failed to enter local lockout state: %s.",
250 libusb_error_name(ret));
252 sr_dbg("Failed to enter local lockout state: USBTMC "
253 "status %d.", status);
260 static void scpi_usbtmc_local(struct scpi_usbtmc_libusb *uscpi)
262 struct sr_usb_dev_inst *usb = uscpi->usb;
263 struct libusb_device *dev;
264 struct libusb_device_descriptor des;
268 if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
271 dev = libusb_get_device(usb->devhdl);
272 libusb_get_device_descriptor(dev, &des);
273 if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
276 sr_dbg("Returning local control.");
277 ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
278 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
279 GO_TO_LOCAL, 0, uscpi->interface, &status, 1, TRANSFER_TIMEOUT);
280 if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
282 sr_dbg("Failed to clear local lockout state: %s.",
283 libusb_error_name(ret));
285 sr_dbg("Failed to clear local lockout state: USBTMC "
286 "status %d.", status);
292 static int scpi_usbtmc_libusb_open(struct sr_scpi_dev_inst *scpi)
294 struct scpi_usbtmc_libusb *uscpi = scpi->priv;
295 struct sr_usb_dev_inst *usb = uscpi->usb;
296 struct libusb_device *dev;
297 struct libusb_device_descriptor des;
298 struct libusb_config_descriptor *confdes;
299 const struct libusb_interface_descriptor *intfdes;
300 const struct libusb_endpoint_descriptor *ep;
301 int confidx, intfidx, epidx, config = 0, current_config;
302 uint8_t capabilities[24];
309 if (sr_usb_open(uscpi->ctx->libusb_ctx, usb) != SR_OK)
312 dev = libusb_get_device(usb->devhdl);
313 libusb_get_device_descriptor(dev, &des);
315 for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
316 if ((ret = libusb_get_config_descriptor(dev, confidx, &confdes)) < 0) {
317 if (ret != LIBUSB_ERROR_NOT_FOUND)
318 sr_dbg("Failed to get configuration descriptor: %s, "
319 "ignoring device.", libusb_error_name(ret));
322 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
323 intfdes = confdes->interface[intfidx].altsetting;
324 if (intfdes->bInterfaceClass != LIBUSB_CLASS_APPLICATION ||
325 intfdes->bInterfaceSubClass != SUBCLASS_USBTMC ||
326 intfdes->bInterfaceProtocol != USBTMC_USB488)
328 uscpi->interface = intfdes->bInterfaceNumber;
329 config = confdes->bConfigurationValue;
330 sr_dbg("Interface %d configuration %d.", uscpi->interface, config);
331 for (epidx = 0; epidx < intfdes->bNumEndpoints; epidx++) {
332 ep = &intfdes->endpoint[epidx];
333 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
334 !(ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK))) {
335 uscpi->bulk_out_ep = ep->bEndpointAddress;
336 sr_dbg("Bulk OUT EP %d", uscpi->bulk_out_ep);
338 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
339 ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
340 uscpi->bulk_in_ep = ep->bEndpointAddress;
341 sr_dbg("Bulk IN EP %d", uscpi->bulk_in_ep & 0x7f);
343 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_INTERRUPT &&
344 ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
345 uscpi->interrupt_ep = ep->bEndpointAddress;
346 sr_dbg("Interrupt EP %d", uscpi->interrupt_ep & 0x7f);
351 libusb_free_config_descriptor(confdes);
357 sr_err("Failed to find USBTMC interface.");
361 if (libusb_kernel_driver_active(usb->devhdl, uscpi->interface) == 1) {
362 if ((ret = libusb_detach_kernel_driver(usb->devhdl,
363 uscpi->interface)) < 0) {
364 sr_err("Failed to detach kernel driver: %s.",
365 libusb_error_name(ret));
368 uscpi->detached_kernel_driver = 1;
371 if (libusb_get_configuration(usb->devhdl, ¤t_config) == 0
372 && current_config != config) {
373 if ((ret = libusb_set_configuration(usb->devhdl, config)) < 0) {
374 sr_err("Failed to set configuration: %s.",
375 libusb_error_name(ret));
380 if ((ret = libusb_claim_interface(usb->devhdl, uscpi->interface)) < 0) {
381 sr_err("Failed to claim interface: %s.",
382 libusb_error_name(ret));
386 /* Optionally reset the USB device. */
387 do_reset = check_usbtmc_blacklist(whitelist_usb_reset,
388 des.idVendor, des.idProduct);
390 libusb_reset_device(usb->devhdl);
392 /* Get capabilities. */
393 ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
394 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
395 GET_CAPABILITIES, 0, uscpi->interface, capabilities,
396 sizeof(capabilities), TRANSFER_TIMEOUT);
397 if (ret == sizeof(capabilities)) {
398 uscpi->usbtmc_int_cap = capabilities[ 4];
399 uscpi->usbtmc_dev_cap = capabilities[ 5];
400 uscpi->usb488_dev_cap = capabilities[15];
402 sr_dbg("Device capabilities: %s%s%s%s%s, %s, %s",
403 uscpi->usb488_dev_cap & USB488_DEV_CAP_SCPI ? "SCPI, " : "",
404 uscpi->usbtmc_dev_cap & USBTMC_DEV_CAP_TERMCHAR ? "TermChar, ": "",
405 uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY ? "L3, " :
406 uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY ? "" : "L4, ",
407 uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY ? "T5, " :
408 uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY ? "" : "T6, ",
409 uscpi->usb488_dev_cap & USB488_DEV_CAP_SR1 ? "SR1" : "SR0",
410 uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1 ? "RL1" : "RL0",
411 uscpi->usb488_dev_cap & USB488_DEV_CAP_DT1 ? "DT1" : "DT0");
413 scpi_usbtmc_remote(uscpi);
418 static int scpi_usbtmc_libusb_connection_id(struct sr_scpi_dev_inst *scpi,
419 char **connection_id)
421 struct scpi_usbtmc_libusb *uscpi = scpi->priv;
422 struct sr_usb_dev_inst *usb = uscpi->usb;
424 *connection_id = g_strdup_printf("%s/%" PRIu8 ".%" PRIu8 "",
425 scpi->prefix, usb->bus, usb->address);
430 static int scpi_usbtmc_libusb_source_add(struct sr_session *session,
431 void *priv, int events, int timeout, sr_receive_data_callback cb,
434 struct scpi_usbtmc_libusb *uscpi = priv;
436 return usb_source_add(session, uscpi->ctx, timeout, cb, cb_data);
439 static int scpi_usbtmc_libusb_source_remove(struct sr_session *session,
442 struct scpi_usbtmc_libusb *uscpi = priv;
443 return usb_source_remove(session, uscpi->ctx);
446 static void usbtmc_bulk_out_header_write(void *header, uint8_t MsgID,
448 uint32_t TransferSize,
449 uint8_t bmTransferAttributes,
452 W8(header + 0, MsgID);
453 W8(header + 1, bTag);
454 W8(header + 2, ~bTag);
456 WL32(header + 4, TransferSize);
457 W8(header + 8, bmTransferAttributes);
458 W8(header + 9, TermChar);
459 WL16(header + 10, 0);
462 static int usbtmc_bulk_in_header_read(void *header, uint8_t MsgID,
464 int32_t *TransferSize,
465 uint8_t *bmTransferAttributes)
467 if (R8(header + 0) != MsgID ||
468 R8(header + 1) != bTag ||
469 R8(header + 2) != (unsigned char)~bTag)
472 *TransferSize = RL32(header + 4);
473 if (bmTransferAttributes)
474 *bmTransferAttributes = R8(header + 8);
479 static int scpi_usbtmc_bulkout(struct scpi_usbtmc_libusb *uscpi,
480 uint8_t msg_id, const void *data, int32_t size,
481 uint8_t transfer_attributes)
483 struct sr_usb_dev_inst *usb = uscpi->usb;
484 int padded_size, ret, transferred;
486 if (data && (size + USBTMC_BULK_HEADER_SIZE + 3) > (int)sizeof(uscpi->buffer)) {
487 sr_err("USBTMC bulk out transfer is too big.");
492 uscpi->bTag += !uscpi->bTag; /* bTag == 0 is invalid so avoid it. */
494 usbtmc_bulk_out_header_write(uscpi->buffer, msg_id, uscpi->bTag,
495 size, transfer_attributes, 0);
497 memcpy(uscpi->buffer + USBTMC_BULK_HEADER_SIZE, data, size);
500 size += USBTMC_BULK_HEADER_SIZE;
501 padded_size = (size + 3) & ~0x3;
502 memset(uscpi->buffer + size, 0, padded_size - size);
504 ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_out_ep,
505 uscpi->buffer, padded_size, &transferred,
508 sr_err("USBTMC bulk out transfer error: %s.",
509 libusb_error_name(ret));
513 if (transferred < padded_size) {
514 sr_dbg("USBTMC bulk out partial transfer (%d/%d bytes).",
515 transferred, padded_size);
519 return transferred - USBTMC_BULK_HEADER_SIZE;
522 static int scpi_usbtmc_bulkin_start(struct scpi_usbtmc_libusb *uscpi,
523 uint8_t msg_id, void *data, int32_t size,
524 uint8_t *transfer_attributes)
526 struct sr_usb_dev_inst *usb = uscpi->usb;
527 int ret, transferred, message_size;
529 ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
530 &transferred, TRANSFER_TIMEOUT);
532 sr_err("USBTMC bulk in transfer error: %s.",
533 libusb_error_name(ret));
537 if (transferred < USBTMC_BULK_HEADER_SIZE) {
538 sr_err("USBTMC bulk in returned too little data: %d/%d bytes\n", transferred, size);
542 if (usbtmc_bulk_in_header_read(data, msg_id, uscpi->bTag, &message_size,
543 transfer_attributes) != SR_OK) {
544 sr_err("USBTMC invalid bulk in header.");
548 message_size += USBTMC_BULK_HEADER_SIZE;
549 uscpi->response_length = MIN(transferred, message_size);
550 uscpi->response_bytes_read = USBTMC_BULK_HEADER_SIZE;
551 uscpi->remaining_length = message_size - uscpi->response_length;
553 return transferred - USBTMC_BULK_HEADER_SIZE;
556 static int scpi_usbtmc_bulkin_continue(struct scpi_usbtmc_libusb *uscpi,
557 void *data, int size)
559 struct sr_usb_dev_inst *usb = uscpi->usb;
560 int ret, transferred;
562 ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
563 &transferred, TRANSFER_TIMEOUT);
565 sr_err("USBTMC bulk in transfer error: %s.",
566 libusb_error_name(ret));
570 uscpi->response_length = MIN(transferred, uscpi->remaining_length);
571 uscpi->response_bytes_read = 0;
572 uscpi->remaining_length -= uscpi->response_length;
577 static int scpi_usbtmc_libusb_send(void *priv, const char *command)
579 struct scpi_usbtmc_libusb *uscpi = priv;
581 if (scpi_usbtmc_bulkout(uscpi, DEV_DEP_MSG_OUT,
582 command, strlen(command), EOM) <= 0)
585 sr_spew("Successfully sent SCPI command: '%s'.", command);
590 static int scpi_usbtmc_libusb_read_begin(void *priv)
592 struct scpi_usbtmc_libusb *uscpi = priv;
594 uscpi->remaining_length = 0;
596 if (scpi_usbtmc_bulkout(uscpi, REQUEST_DEV_DEP_MSG_IN,
597 NULL, INT32_MAX, 0) < 0)
599 if (scpi_usbtmc_bulkin_start(uscpi, DEV_DEP_MSG_IN,
600 uscpi->buffer, sizeof(uscpi->buffer),
601 &uscpi->bulkin_attributes) < 0)
607 static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
609 struct scpi_usbtmc_libusb *uscpi = priv;
612 if (uscpi->response_bytes_read >= uscpi->response_length) {
613 if (uscpi->remaining_length > 0) {
614 if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
615 sizeof(uscpi->buffer)) <= 0)
618 if (uscpi->bulkin_attributes & EOM)
620 if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
625 read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
627 memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
629 uscpi->response_bytes_read += read_length;
634 static int scpi_usbtmc_libusb_read_complete(void *priv)
636 struct scpi_usbtmc_libusb *uscpi = priv;
637 return uscpi->response_bytes_read >= uscpi->response_length &&
638 uscpi->remaining_length <= 0 &&
639 uscpi->bulkin_attributes & EOM;
642 static int scpi_usbtmc_libusb_close(struct sr_scpi_dev_inst *scpi)
644 struct scpi_usbtmc_libusb *uscpi = scpi->priv;
645 struct sr_usb_dev_inst *usb = uscpi->usb;
651 scpi_usbtmc_local(uscpi);
653 if ((ret = libusb_release_interface(usb->devhdl, uscpi->interface)) < 0)
654 sr_err("Failed to release interface: %s.",
655 libusb_error_name(ret));
657 if (uscpi->detached_kernel_driver) {
658 if ((ret = libusb_attach_kernel_driver(usb->devhdl,
659 uscpi->interface)) < 0)
660 sr_err("Failed to re-attach kernel driver: %s.",
661 libusb_error_name(ret));
663 uscpi->detached_kernel_driver = 0;
670 static void scpi_usbtmc_libusb_free(void *priv)
672 struct scpi_usbtmc_libusb *uscpi = priv;
673 sr_usb_dev_inst_free(uscpi->usb);
676 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
679 .transport = SCPI_TRANSPORT_USBTMC,
680 .priv_size = sizeof(struct scpi_usbtmc_libusb),
681 .scan = scpi_usbtmc_libusb_scan,
682 .dev_inst_new = scpi_usbtmc_libusb_dev_inst_new,
683 .open = scpi_usbtmc_libusb_open,
684 .connection_id = scpi_usbtmc_libusb_connection_id,
685 .source_add = scpi_usbtmc_libusb_source_add,
686 .source_remove = scpi_usbtmc_libusb_source_remove,
687 .send = scpi_usbtmc_libusb_send,
688 .read_begin = scpi_usbtmc_libusb_read_begin,
689 .read_data = scpi_usbtmc_libusb_read_data,
690 .read_complete = scpi_usbtmc_libusb_read_complete,
691 .close = scpi_usbtmc_libusb_close,
692 .free = scpi_usbtmc_libusb_free,