src/scpi/scpi_usbtmc_libusb.c

   1 /*
   2  * This file is part of the libsigrok project.
   3  *
   4  * Copyright (C) 2014 Aurelien Jacobs <aurel@gnuage.org>
   5  *
   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.
  10  *
  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.
  15  *
  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/>.
  18  */
  19
  20 #include <string.h>
  21 #include <libsigrok/libsigrok.h>
  22 #include "libsigrok-internal.h"
  23
  24 #define LOG_PREFIX "scpi_usbtmc"
  25
  26 #define MAX_TRANSFER_LENGTH 2048
  27 #define TRANSFER_TIMEOUT 1000
  28
  29 struct scpi_usbtmc_libusb {
  30         struct sr_context *ctx;
  31         struct sr_usb_dev_inst *usb;
  32         int detached_kernel_driver;
  33         uint8_t interface;
  34         uint8_t bulk_in_ep;
  35         uint8_t bulk_out_ep;
  36         uint8_t interrupt_ep;
  37         uint8_t usbtmc_int_cap;
  38         uint8_t usbtmc_dev_cap;
  39         uint8_t usb488_dev_cap;
  40         uint8_t bTag;
  41         uint8_t bulkin_attributes;
  42         uint8_t buffer[MAX_TRANSFER_LENGTH];
  43         int response_length;
  44         int response_bytes_read;
  45         int remaining_length;
  46         int rigol_ds1000;
  47 };
  48
  49 /* Some USBTMC-specific enums, as defined in the USBTMC standard. */
  50 #define SUBCLASS_USBTMC  0x03
  51 #define USBTMC_USB488    0x01
  52
  53 enum {
  54         /* USBTMC control requests */
  55         INITIATE_ABORT_BULK_OUT     =   1,
  56         CHECK_ABORT_BULK_OUT_STATUS =   2,
  57         INITIATE_ABORT_BULK_IN      =   3,
  58         CHECK_ABORT_BULK_IN_STATUS  =   4,
  59         INITIATE_CLEAR              =   5,
  60         CHECK_CLEAR_STATUS          =   6,
  61         GET_CAPABILITIES            =   7,
  62         INDICATOR_PULSE             =  64,
  63
  64         /* USB488 control requests */
  65         READ_STATUS_BYTE            = 128,
  66         REN_CONTROL                 = 160,
  67         GO_TO_LOCAL                 = 161,
  68         LOCAL_LOCKOUT               = 162,
  69 };
  70
  71 /* USBTMC capabilities */
  72 #define USBTMC_INT_CAP_LISTEN_ONLY 0x01
  73 #define USBTMC_INT_CAP_TALK_ONLY   0x02
  74 #define USBTMC_INT_CAP_INDICATOR   0x04
  75
  76 #define USBTMC_DEV_CAP_TERMCHAR    0x01
  77
  78 #define USB488_DEV_CAP_DT1         0x01
  79 #define USB488_DEV_CAP_RL1         0x02
  80 #define USB488_DEV_CAP_SR1         0x04
  81 #define USB488_DEV_CAP_SCPI        0x08
  82
  83 /* Bulk messages constants */
  84 #define USBTMC_BULK_HEADER_SIZE  12
  85
  86 /* Bulk MsgID values */
  87 #define DEV_DEP_MSG_OUT         1
  88 #define REQUEST_DEV_DEP_MSG_IN  2
  89 #define DEV_DEP_MSG_IN          2
  90
  91 /* bmTransferAttributes */
  92 #define EOM                0x01
  93 #define TERM_CHAR_ENABLED  0x02
  94
  95 static GSList *scpi_usbtmc_libusb_scan(struct drv_context *drvc)
  96 {
  97         struct libusb_device **devlist;
  98         struct libusb_device_descriptor des;
  99         struct libusb_config_descriptor *confdes;
 100         const struct libusb_interface_descriptor *intfdes;
 101         GSList *resources = NULL;
 102         int confidx, intfidx, ret, i;
 103         char *res;
 104
 105         ret = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
 106         if (ret < 0) {
 107                 sr_err("Failed to get device list: %s.",
 108                        libusb_error_name(ret));
 109                 return NULL;
 110         }
 111         for (i = 0; devlist[i]; i++) {
 112                 if ((ret = libusb_get_device_descriptor(devlist[i], &des)) < 0) {
 113                         sr_err("Failed to get device descriptor: %s.",
 114                                libusb_error_name(ret));
 115                         continue;
 116                 }
 117
 118                 for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 119                         if ((ret = libusb_get_config_descriptor(devlist[i], confidx, &confdes)) < 0) {
 120                                 sr_dbg("Failed to get configuration descriptor: %s, "
 121                                        "ignoring device.", libusb_error_name(ret));
 122                                 break;
 123                         }
 124                         for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 125                                 intfdes = confdes->interface[intfidx].altsetting;
 126                                 if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 127                                     intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 128                                     intfdes->bInterfaceProtocol != USBTMC_USB488)
 129                                         continue;
 130                                 sr_dbg("Found USBTMC device (VID:PID = %04x:%04x, "
 131                                        "bus.address = %d.%d).", des.idVendor, des.idProduct,
 132                                        libusb_get_bus_number(devlist[i]),
 133                                        libusb_get_device_address(devlist[i]));
 134                                 res = g_strdup_printf("usbtmc/%d.%d",
 135                                                       libusb_get_bus_number(devlist[i]),
 136                                                       libusb_get_device_address(devlist[i]));
 137                                 resources = g_slist_append(resources, res);
 138                         }
 139                         libusb_free_config_descriptor(confdes);
 140                 }
 141         }
 142         libusb_free_device_list(devlist, 1);
 143
 144         sr_dbg("Found %d device(s).", g_slist_length(resources));
 145
 146         return resources;
 147 }
 148
 149 static int scpi_usbtmc_libusb_dev_inst_new(void *priv, struct drv_context *drvc,
 150                 const char *resource, char **params, const char *serialcomm)
 151 {
 152         struct scpi_usbtmc_libusb *uscpi = priv;
 153         GSList *devices;
 154
 155         (void)resource;
 156         (void)serialcomm;
 157
 158         if (!params || !params[1]) {
 159                 sr_err("Invalid parameters.");
 160                 return SR_ERR;
 161         }
 162
 163         uscpi->ctx = drvc->sr_ctx;
 164         devices = sr_usb_find(uscpi->ctx->libusb_ctx, params[1]);
 165         if (g_slist_length(devices) != 1) {
 166                 sr_err("Failed to find USB device '%s'.", params[1]);
 167                 g_slist_free_full(devices, (GDestroyNotify)sr_usb_dev_inst_free);
 168                 return SR_ERR;
 169         }
 170         uscpi->usb = devices->data;
 171         g_slist_free(devices);
 172
 173         return SR_OK;
 174 }
 175
 176 static int scpi_usbtmc_libusb_open(void *priv)
 177 {
 178         struct scpi_usbtmc_libusb *uscpi = priv;
 179         struct sr_usb_dev_inst *usb = uscpi->usb;
 180         struct libusb_device *dev;
 181         struct libusb_device_descriptor des;
 182         struct libusb_config_descriptor *confdes;
 183         const struct libusb_interface_descriptor *intfdes;
 184         const struct libusb_endpoint_descriptor *ep;
 185         int confidx, intfidx, epidx, config = 0;
 186         uint8_t capabilities[24];
 187         int ret, found = 0;
 188
 189         if (usb->devhdl)
 190                 return SR_OK;
 191
 192         if (sr_usb_open(uscpi->ctx->libusb_ctx, usb) != SR_OK)
 193                 return SR_ERR;
 194
 195         dev = libusb_get_device(usb->devhdl);
 196         if ((ret = libusb_get_device_descriptor(dev, &des)) < 0) {
 197                 sr_err("Failed to get device descriptor: %s.",
 198                        libusb_error_name(ret));
 199                 return SR_ERR;
 200         }
 201
 202         for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 203                 if ((ret = libusb_get_config_descriptor(dev, confidx, &confdes)) < 0) {
 204                         sr_dbg("Failed to get configuration descriptor: %s, "
 205                                "ignoring device.", libusb_error_name(ret));
 206                         continue;
 207                 }
 208                 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 209                         intfdes = confdes->interface[intfidx].altsetting;
 210                         if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 211                             intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 212                             intfdes->bInterfaceProtocol != USBTMC_USB488)
 213                                 continue;
 214                         uscpi->interface = intfdes->bInterfaceNumber;
 215                         config = confdes->bConfigurationValue;
 216                         sr_dbg("Interface %d configuration %d.", uscpi->interface, config);
 217                         for (epidx = 0; epidx < intfdes->bNumEndpoints; epidx++) {
 218                                 ep = &intfdes->endpoint[epidx];
 219                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 220                                     !(ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK))) {
 221                                         uscpi->bulk_out_ep = ep->bEndpointAddress;
 222                                         sr_dbg("Bulk OUT EP %d", uscpi->bulk_out_ep);
 223                                 }
 224                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 225                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 226                                         uscpi->bulk_in_ep = ep->bEndpointAddress;
 227                                         sr_dbg("Bulk IN EP %d", uscpi->bulk_in_ep & 0x7f);
 228                                 }
 229                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_INTERRUPT &&
 230                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 231                                         uscpi->interrupt_ep = ep->bEndpointAddress;
 232                                         sr_dbg("Interrupt EP %d", uscpi->interrupt_ep & 0x7f);
 233                                 }
 234                         }
 235                         found = 1;
 236                         uscpi->rigol_ds1000 = des.idVendor  == 0x1ab1 &&
 237                                               des.idProduct == 0x0588;
 238                 }
 239                 libusb_free_config_descriptor(confdes);
 240                 if (found)
 241                         break;
 242         }
 243
 244         if (!found) {
 245                 sr_err("Failed to find USBTMC interface.");
 246                 return SR_ERR;
 247         }
 248
 249         if (libusb_kernel_driver_active(usb->devhdl, uscpi->interface) == 1) {
 250                 if ((ret = libusb_detach_kernel_driver(usb->devhdl,
 251                                                        uscpi->interface)) < 0) {
 252                         sr_err("Failed to detach kernel driver: %s.",
 253                                libusb_error_name(ret));
 254                         return SR_ERR;
 255                 }
 256                 uscpi->detached_kernel_driver = 1;
 257         }
 258
 259         if ((ret = libusb_set_configuration(usb->devhdl, config)) < 0) {
 260                 sr_err("Failed to set configuration: %s.",
 261                        libusb_error_name(ret));
 262                 return SR_ERR;
 263         }
 264
 265         if ((ret = libusb_claim_interface(usb->devhdl, uscpi->interface)) < 0) {
 266                 sr_err("Failed to claim interface: %s.",
 267                        libusb_error_name(ret));
 268                 return SR_ERR;
 269         }
 270
 271         if (!uscpi->rigol_ds1000) {
 272         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_in_ep)) < 0) {
 273                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 274                        uscpi->bulk_in_ep, libusb_error_name(ret));
 275                 return SR_ERR;
 276         }
 277         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_out_ep)) < 0) {
 278                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 279                        uscpi->bulk_out_ep, libusb_error_name(ret));
 280                 return SR_ERR;
 281         }
 282         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->interrupt_ep)) < 0) {
 283                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 284                        uscpi->interrupt_ep, libusb_error_name(ret));
 285                 return SR_ERR;
 286         }
 287         }
 288
 289         /* Get capabilities. */
 290         ret = libusb_control_transfer(usb->devhdl,
 291                                       LIBUSB_ENDPOINT_IN         |
 292                                       LIBUSB_REQUEST_TYPE_CLASS  |
 293                                       LIBUSB_RECIPIENT_INTERFACE,
 294                                       GET_CAPABILITIES, 0,
 295                                       uscpi->interface,
 296                                       capabilities, sizeof(capabilities),
 297                                       TRANSFER_TIMEOUT);
 298         if (ret == sizeof(capabilities)) {
 299                 uscpi->usbtmc_int_cap = capabilities[ 4];
 300                 uscpi->usbtmc_dev_cap = capabilities[ 5];
 301                 uscpi->usb488_dev_cap = capabilities[15];
 302         }
 303         sr_dbg("Device capabilities: %s%s%s%s%s, %s, %s",
 304                uscpi->usb488_dev_cap & USB488_DEV_CAP_SCPI       ? "SCPI, "    : "",
 305                uscpi->usbtmc_dev_cap & USBTMC_DEV_CAP_TERMCHAR   ? "TermChar, ": "",
 306                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? "L3, " :
 307                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? ""     : "L4, ",
 308                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? "T5, " :
 309                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? ""     : "T6, ",
 310                uscpi->usb488_dev_cap & USB488_DEV_CAP_SR1        ? "SR1"  : "SR0",
 311                uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1        ? "RL1"  : "RL0",
 312                uscpi->usb488_dev_cap & USB488_DEV_CAP_DT1        ? "DT1"  : "DT0");
 313
 314         return SR_OK;
 315 }
 316
 317 static int scpi_usbtmc_libusb_source_add(struct sr_session *session,
 318                 void *priv, int events, int timeout, sr_receive_data_callback cb,
 319                 void *cb_data)
 320 {
 321         struct scpi_usbtmc_libusb *uscpi = priv;
 322         (void)events;
 323         return usb_source_add(session, uscpi->ctx, timeout, cb, cb_data);
 324 }
 325
 326 static int scpi_usbtmc_libusb_source_remove(struct sr_session *session,
 327                 void *priv)
 328 {
 329         struct scpi_usbtmc_libusb *uscpi = priv;
 330         return usb_source_remove(session, uscpi->ctx);
 331 }
 332
 333 static void usbtmc_bulk_out_header_write(void *header, uint8_t MsgID,
 334                                          uint8_t bTag,
 335                                          uint32_t TransferSize,
 336                                          uint8_t bmTransferAttributes,
 337                                          char TermChar)
 338 {
 339           W8(header+ 0, MsgID);
 340           W8(header+ 1, bTag);
 341           W8(header+ 2, ~bTag);
 342           W8(header+ 3, 0);
 343         WL32(header+ 4, TransferSize);
 344           W8(header+ 8, bmTransferAttributes);
 345           W8(header+ 9, TermChar);
 346         WL16(header+10, 0);
 347 }
 348
 349 static int usbtmc_bulk_in_header_read(void *header, uint8_t MsgID,
 350                                       unsigned char bTag,
 351                                       int32_t *TransferSize,
 352                                       uint8_t *bmTransferAttributes)
 353 {
 354         if (R8(header+0) != MsgID ||
 355             R8(header+1) != bTag  ||
 356             R8(header+2) != (unsigned char)~bTag)
 357                 return SR_ERR;
 358         if (TransferSize)
 359                 *TransferSize = RL32(header+4);
 360         if (bmTransferAttributes)
 361                 *bmTransferAttributes = R8(header+8);
 362         return SR_OK;
 363 }
 364
 365 static int scpi_usbtmc_bulkout(struct scpi_usbtmc_libusb *uscpi,
 366                                uint8_t msg_id, const void *data, int32_t size,
 367                                uint8_t transfer_attributes)
 368 {
 369         struct sr_usb_dev_inst *usb = uscpi->usb;
 370         int padded_size, ret, transferred;
 371
 372         if (data && size+USBTMC_BULK_HEADER_SIZE+3 > (int)sizeof(uscpi->buffer)) {
 373                 sr_err("USBTMC bulk out transfer is too big.");
 374                 return SR_ERR;
 375         }
 376
 377         uscpi->bTag++;
 378         uscpi->bTag += !uscpi->bTag;  /* bTag == 0 is invalid so avoid it. */
 379
 380         usbtmc_bulk_out_header_write(uscpi->buffer, msg_id, uscpi->bTag,
 381                                      size, transfer_attributes, 0);
 382         if (data)
 383                 memcpy(uscpi->buffer+USBTMC_BULK_HEADER_SIZE, data, size);
 384         else
 385                 size = 0;
 386         size += USBTMC_BULK_HEADER_SIZE;
 387         padded_size = (size + 3) & ~0x3;
 388         memset(uscpi->buffer+size, 0, padded_size - size);
 389
 390         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_out_ep,
 391                                    uscpi->buffer, padded_size, &transferred,
 392                                    TRANSFER_TIMEOUT);
 393         if (ret < 0) {
 394                 sr_err("USBTMC bulk out transfer error: %s.",
 395                        libusb_error_name(ret));
 396                 return SR_ERR;
 397         }
 398
 399         if (transferred < padded_size) {
 400                 sr_dbg("USBTMC bulk out partial transfer (%d/%d bytes).",
 401                        transferred, padded_size);
 402                 return SR_ERR;
 403         }
 404
 405         return transferred - USBTMC_BULK_HEADER_SIZE;
 406 }
 407
 408 static int scpi_usbtmc_bulkin_start(struct scpi_usbtmc_libusb *uscpi,
 409                                     uint8_t msg_id, void *data, int32_t size,
 410                                     uint8_t *transfer_attributes)
 411 {
 412         struct sr_usb_dev_inst *usb = uscpi->usb;
 413         int ret, transferred, message_size;
 414
 415         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 416                                    &transferred, TRANSFER_TIMEOUT);
 417         if (ret < 0) {
 418                 sr_err("USBTMC bulk in transfer error: %s.",
 419                        libusb_error_name(ret));
 420                 return SR_ERR;
 421         }
 422
 423         if (usbtmc_bulk_in_header_read(data, msg_id, uscpi->bTag, &message_size,
 424                                        transfer_attributes) != SR_OK) {
 425                 sr_err("USBTMC invalid bulk in header.");
 426                 return SR_ERR;
 427         }
 428
 429         message_size += USBTMC_BULK_HEADER_SIZE;
 430         uscpi->response_length = MIN(transferred, message_size);
 431         uscpi->response_bytes_read = USBTMC_BULK_HEADER_SIZE;
 432         uscpi->remaining_length = message_size - uscpi->response_length;
 433
 434         return transferred - USBTMC_BULK_HEADER_SIZE;
 435 }
 436
 437 static int scpi_usbtmc_bulkin_continue(struct scpi_usbtmc_libusb *uscpi,
 438                                        void *data, int size)
 439 {
 440         struct sr_usb_dev_inst *usb = uscpi->usb;
 441         int ret, transferred;
 442
 443         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 444                                    &transferred, TRANSFER_TIMEOUT);
 445         if (ret < 0) {
 446                 sr_err("USBTMC bulk in transfer error: %s.",
 447                        libusb_error_name(ret));
 448                 return SR_ERR;
 449         }
 450
 451         uscpi->response_length = MIN(transferred, uscpi->remaining_length);
 452         uscpi->response_bytes_read = 0;
 453         uscpi->remaining_length -= uscpi->response_length;
 454
 455         return transferred;
 456 }
 457
 458 static int scpi_usbtmc_libusb_send(void *priv, const char *command)
 459 {
 460         struct scpi_usbtmc_libusb *uscpi = priv;
 461
 462         if (scpi_usbtmc_bulkout(uscpi, DEV_DEP_MSG_OUT,
 463                                 command, strlen(command), EOM) <= 0)
 464                 return SR_ERR;
 465
 466         sr_spew("Successfully sent SCPI command: '%s'.", command);
 467
 468         return SR_OK;
 469 }
 470
 471 static int scpi_usbtmc_libusb_read_begin(void *priv)
 472 {
 473         struct scpi_usbtmc_libusb *uscpi = priv;
 474
 475         uscpi->remaining_length = 0;
 476
 477         if (scpi_usbtmc_bulkout(uscpi, REQUEST_DEV_DEP_MSG_IN,
 478             NULL, INT32_MAX, 0) < 0)
 479                 return SR_ERR;
 480         if (scpi_usbtmc_bulkin_start(uscpi, DEV_DEP_MSG_IN,
 481                                      uscpi->buffer, sizeof(uscpi->buffer),
 482                                      &uscpi->bulkin_attributes) < 0)
 483                 return SR_ERR;
 484
 485         return SR_OK;
 486 }
 487
 488 static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
 489 {
 490         struct scpi_usbtmc_libusb *uscpi = priv;
 491         int read_length;
 492
 493         if (uscpi->response_bytes_read >= uscpi->response_length) {
 494                 if (uscpi->remaining_length > 0) {
 495                         if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
 496                                                         sizeof(uscpi->buffer)) <= 0)
 497                                 return SR_ERR;
 498                 } else {
 499                         if (uscpi->bulkin_attributes & EOM)
 500                                 return SR_ERR;
 501                         if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
 502                                 return SR_ERR;
 503                 }
 504         }
 505
 506         read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
 507
 508         memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
 509
 510         uscpi->response_bytes_read += read_length;
 511
 512         return read_length;
 513 }
 514
 515 static int scpi_usbtmc_libusb_read_complete(void *priv)
 516 {
 517         struct scpi_usbtmc_libusb *uscpi = priv;
 518         return uscpi->response_bytes_read >= uscpi->response_length &&
 519                uscpi->remaining_length <= 0 &&
 520                uscpi->bulkin_attributes & EOM;
 521 }
 522
 523 static int scpi_usbtmc_libusb_close(void *priv)
 524 {
 525         int ret;
 526         struct scpi_usbtmc_libusb *uscpi = priv;
 527         struct sr_usb_dev_inst *usb = uscpi->usb;
 528
 529         if (!usb->devhdl)
 530                 return SR_ERR;
 531
 532         if (!uscpi->rigol_ds1000) {
 533         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_in_ep)) < 0)
 534                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 535                        uscpi->bulk_in_ep, libusb_error_name(ret));
 536         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_out_ep)) < 0)
 537                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 538                        uscpi->bulk_out_ep, libusb_error_name(ret));
 539         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->interrupt_ep)) < 0)
 540                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 541                        uscpi->interrupt_ep, libusb_error_name(ret));
 542         }
 543
 544         if ((ret = libusb_release_interface(usb->devhdl, uscpi->interface)) < 0)
 545                 sr_err("Failed to release interface: %s.",
 546                        libusb_error_name(ret));
 547
 548         if (uscpi->detached_kernel_driver) {
 549                 if ((ret = libusb_attach_kernel_driver(usb->devhdl,
 550                                                 uscpi->interface)) < 0)
 551                         sr_err("Failed to re-attach kernel driver: %s.",
 552                                libusb_error_name(ret));
 553
 554                 uscpi->detached_kernel_driver = 0;
 555         }
 556         libusb_close(usb->devhdl);
 557         usb->devhdl = NULL;
 558
 559         return SR_OK;
 560 }
 561
 562 static void scpi_usbtmc_libusb_free(void *priv)
 563 {
 564         struct scpi_usbtmc_libusb *uscpi = priv;
 565         sr_usb_dev_inst_free(uscpi->usb);
 566 }
 567
 568 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
 569         .name          = "USBTMC",
 570         .prefix        = "usbtmc",
 571         .priv_size     = sizeof(struct scpi_usbtmc_libusb),
 572         .scan          = scpi_usbtmc_libusb_scan,
 573         .dev_inst_new  = scpi_usbtmc_libusb_dev_inst_new,
 574         .open          = scpi_usbtmc_libusb_open,
 575         .source_add    = scpi_usbtmc_libusb_source_add,
 576         .source_remove = scpi_usbtmc_libusb_source_remove,
 577         .send          = scpi_usbtmc_libusb_send,
 578         .read_begin    = scpi_usbtmc_libusb_read_begin,
 579         .read_data     = scpi_usbtmc_libusb_read_data,
 580         .read_complete = scpi_usbtmc_libusb_read_complete,
 581         .close         = scpi_usbtmc_libusb_close,
 582         .free          = scpi_usbtmc_libusb_free,
 583 };