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