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 <config.h>
  21 #include <string.h>
  22 #include <libsigrok/libsigrok.h>
  23 #include "libsigrok-internal.h"
  24 #include "scpi.h"
  25
  26 #define LOG_PREFIX "scpi_usbtmc"
  27
  28 #define MAX_TRANSFER_LENGTH 2048
  29 #define TRANSFER_TIMEOUT 1000
  30
  31 struct scpi_usbtmc_libusb {
  32         struct sr_context *ctx;
  33         struct sr_usb_dev_inst *usb;
  34         int detached_kernel_driver;
  35         uint8_t interface;
  36         uint8_t bulk_in_ep;
  37         uint8_t bulk_out_ep;
  38         uint8_t interrupt_ep;
  39         uint8_t usbtmc_int_cap;
  40         uint8_t usbtmc_dev_cap;
  41         uint8_t usb488_dev_cap;
  42         uint8_t bTag;
  43         uint8_t bulkin_attributes;
  44         uint8_t buffer[MAX_TRANSFER_LENGTH];
  45         int response_length;
  46         int response_bytes_read;
  47         int remaining_length;
  48         int rigol_ds1000;
  49 };
  50
  51 /* Some USBTMC-specific enums, as defined in the USBTMC standard. */
  52 #define SUBCLASS_USBTMC  0x03
  53 #define USBTMC_USB488    0x01
  54
  55 enum {
  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,
  61         INITIATE_CLEAR              =   5,
  62         CHECK_CLEAR_STATUS          =   6,
  63         GET_CAPABILITIES            =   7,
  64         INDICATOR_PULSE             =  64,
  65
  66         /* USB488 control requests */
  67         READ_STATUS_BYTE            = 128,
  68         REN_CONTROL                 = 160,
  69         GO_TO_LOCAL                 = 161,
  70         LOCAL_LOCKOUT               = 162,
  71 };
  72
  73 /* USBTMC status codes */
  74 #define USBTMC_STATUS_SUCCESS      0x01
  75
  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
  80
  81 #define USBTMC_DEV_CAP_TERMCHAR    0x01
  82
  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
  87
  88 /* Bulk messages constants */
  89 #define USBTMC_BULK_HEADER_SIZE  12
  90
  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
  95
  96 /* bmTransferAttributes */
  97 #define EOM                0x01
  98 #define TERM_CHAR_ENABLED  0x02
  99
 100 static GSList *scpi_usbtmc_libusb_scan(struct drv_context *drvc)
 101 {
 102         struct libusb_device **devlist;
 103         struct libusb_device_descriptor des;
 104         struct libusb_config_descriptor *confdes;
 105         const struct libusb_interface_descriptor *intfdes;
 106         GSList *resources = NULL;
 107         int confidx, intfidx, ret, i;
 108         char *res;
 109
 110         ret = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
 111         if (ret < 0) {
 112                 sr_err("Failed to get device list: %s.",
 113                        libusb_error_name(ret));
 114                 return NULL;
 115         }
 116         for (i = 0; devlist[i]; i++) {
 117                 libusb_get_device_descriptor(devlist[i], &des);
 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], status;
 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         libusb_get_device_descriptor(dev, &des);
 198
 199         for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 200                 if ((ret = libusb_get_config_descriptor(dev, confidx, &confdes)) < 0) {
 201                         sr_dbg("Failed to get configuration descriptor: %s, "
 202                                "ignoring device.", libusb_error_name(ret));
 203                         continue;
 204                 }
 205                 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 206                         intfdes = confdes->interface[intfidx].altsetting;
 207                         if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 208                             intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 209                             intfdes->bInterfaceProtocol != USBTMC_USB488)
 210                                 continue;
 211                         uscpi->interface = intfdes->bInterfaceNumber;
 212                         config = confdes->bConfigurationValue;
 213                         sr_dbg("Interface %d configuration %d.", uscpi->interface, config);
 214                         for (epidx = 0; epidx < intfdes->bNumEndpoints; epidx++) {
 215                                 ep = &intfdes->endpoint[epidx];
 216                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 217                                     !(ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK))) {
 218                                         uscpi->bulk_out_ep = ep->bEndpointAddress;
 219                                         sr_dbg("Bulk OUT EP %d", uscpi->bulk_out_ep);
 220                                 }
 221                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 222                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 223                                         uscpi->bulk_in_ep = ep->bEndpointAddress;
 224                                         sr_dbg("Bulk IN EP %d", uscpi->bulk_in_ep & 0x7f);
 225                                 }
 226                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_INTERRUPT &&
 227                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 228                                         uscpi->interrupt_ep = ep->bEndpointAddress;
 229                                         sr_dbg("Interrupt EP %d", uscpi->interrupt_ep & 0x7f);
 230                                 }
 231                         }
 232                         found = 1;
 233                         uscpi->rigol_ds1000 = des.idVendor  == 0x1ab1 &&
 234                                               des.idProduct == 0x0588;
 235                 }
 236                 libusb_free_config_descriptor(confdes);
 237                 if (found)
 238                         break;
 239         }
 240
 241         if (!found) {
 242                 sr_err("Failed to find USBTMC interface.");
 243                 return SR_ERR;
 244         }
 245
 246         if (libusb_kernel_driver_active(usb->devhdl, uscpi->interface) == 1) {
 247                 if ((ret = libusb_detach_kernel_driver(usb->devhdl,
 248                                                        uscpi->interface)) < 0) {
 249                         sr_err("Failed to detach kernel driver: %s.",
 250                                libusb_error_name(ret));
 251                         return SR_ERR;
 252                 }
 253                 uscpi->detached_kernel_driver = 1;
 254         }
 255
 256         if ((ret = libusb_set_configuration(usb->devhdl, config)) < 0) {
 257                 sr_err("Failed to set configuration: %s.",
 258                        libusb_error_name(ret));
 259                 return SR_ERR;
 260         }
 261
 262         if ((ret = libusb_claim_interface(usb->devhdl, uscpi->interface)) < 0) {
 263                 sr_err("Failed to claim interface: %s.",
 264                        libusb_error_name(ret));
 265                 return SR_ERR;
 266         }
 267
 268         if (!uscpi->rigol_ds1000) {
 269         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_in_ep)) < 0) {
 270                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 271                        uscpi->bulk_in_ep, libusb_error_name(ret));
 272                 return SR_ERR;
 273         }
 274         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_out_ep)) < 0) {
 275                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 276                        uscpi->bulk_out_ep, libusb_error_name(ret));
 277                 return SR_ERR;
 278         }
 279         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->interrupt_ep)) < 0) {
 280                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 281                        uscpi->interrupt_ep, libusb_error_name(ret));
 282                 return SR_ERR;
 283         }
 284         }
 285
 286         /* Get capabilities. */
 287         ret = libusb_control_transfer(usb->devhdl,
 288                                       LIBUSB_ENDPOINT_IN         |
 289                                       LIBUSB_REQUEST_TYPE_CLASS  |
 290                                       LIBUSB_RECIPIENT_INTERFACE,
 291                                       GET_CAPABILITIES, 0,
 292                                       uscpi->interface,
 293                                       capabilities, sizeof(capabilities),
 294                                       TRANSFER_TIMEOUT);
 295         if (ret == sizeof(capabilities)) {
 296                 uscpi->usbtmc_int_cap = capabilities[ 4];
 297                 uscpi->usbtmc_dev_cap = capabilities[ 5];
 298                 uscpi->usb488_dev_cap = capabilities[15];
 299         }
 300         sr_dbg("Device capabilities: %s%s%s%s%s, %s, %s",
 301                uscpi->usb488_dev_cap & USB488_DEV_CAP_SCPI       ? "SCPI, "    : "",
 302                uscpi->usbtmc_dev_cap & USBTMC_DEV_CAP_TERMCHAR   ? "TermChar, ": "",
 303                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? "L3, " :
 304                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? ""     : "L4, ",
 305                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? "T5, " :
 306                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? ""     : "T6, ",
 307                uscpi->usb488_dev_cap & USB488_DEV_CAP_SR1        ? "SR1"  : "SR0",
 308                uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1        ? "RL1"  : "RL0",
 309                uscpi->usb488_dev_cap & USB488_DEV_CAP_DT1        ? "DT1"  : "DT0");
 310
 311         if (uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1) {
 312                 sr_dbg("Locking out local control.");
 313                 ret = libusb_control_transfer(usb->devhdl,
 314                                 LIBUSB_ENDPOINT_IN         |
 315                                 LIBUSB_REQUEST_TYPE_CLASS  |
 316                                 LIBUSB_RECIPIENT_INTERFACE,
 317                                 REN_CONTROL, 1,
 318                                 uscpi->interface,
 319                                 &status, 1,
 320                                 TRANSFER_TIMEOUT);
 321                 if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 322                         sr_dbg("Failed to enter REN state.");
 323                         return SR_OK;
 324                 }
 325                 ret = libusb_control_transfer(usb->devhdl,
 326                                 LIBUSB_ENDPOINT_IN         |
 327                                 LIBUSB_REQUEST_TYPE_CLASS  |
 328                                 LIBUSB_RECIPIENT_INTERFACE,
 329                                 LOCAL_LOCKOUT, 1,
 330                                 uscpi->interface,
 331                                 &status, 1,
 332                                 TRANSFER_TIMEOUT);
 333                 if (ret < 0 || status != USBTMC_STATUS_SUCCESS)
 334                         sr_dbg("Failed to enter local lockout state.");
 335         }
 336
 337         return SR_OK;
 338 }
 339
 340 static int scpi_usbtmc_libusb_source_add(struct sr_session *session,
 341                 void *priv, int events, int timeout, sr_receive_data_callback cb,
 342                 void *cb_data)
 343 {
 344         struct scpi_usbtmc_libusb *uscpi = priv;
 345         (void)events;
 346         return usb_source_add(session, uscpi->ctx, timeout, cb, cb_data);
 347 }
 348
 349 static int scpi_usbtmc_libusb_source_remove(struct sr_session *session,
 350                 void *priv)
 351 {
 352         struct scpi_usbtmc_libusb *uscpi = priv;
 353         return usb_source_remove(session, uscpi->ctx);
 354 }
 355
 356 static void usbtmc_bulk_out_header_write(void *header, uint8_t MsgID,
 357                                          uint8_t bTag,
 358                                          uint32_t TransferSize,
 359                                          uint8_t bmTransferAttributes,
 360                                          char TermChar)
 361 {
 362           W8(header+ 0, MsgID);
 363           W8(header+ 1, bTag);
 364           W8(header+ 2, ~bTag);
 365           W8(header+ 3, 0);
 366         WL32(header+ 4, TransferSize);
 367           W8(header+ 8, bmTransferAttributes);
 368           W8(header+ 9, TermChar);
 369         WL16(header+10, 0);
 370 }
 371
 372 static int usbtmc_bulk_in_header_read(void *header, uint8_t MsgID,
 373                                       unsigned char bTag,
 374                                       int32_t *TransferSize,
 375                                       uint8_t *bmTransferAttributes)
 376 {
 377         if (R8(header+0) != MsgID ||
 378             R8(header+1) != bTag  ||
 379             R8(header+2) != (unsigned char)~bTag)
 380                 return SR_ERR;
 381         if (TransferSize)
 382                 *TransferSize = RL32(header+4);
 383         if (bmTransferAttributes)
 384                 *bmTransferAttributes = R8(header+8);
 385         return SR_OK;
 386 }
 387
 388 static int scpi_usbtmc_bulkout(struct scpi_usbtmc_libusb *uscpi,
 389                                uint8_t msg_id, const void *data, int32_t size,
 390                                uint8_t transfer_attributes)
 391 {
 392         struct sr_usb_dev_inst *usb = uscpi->usb;
 393         int padded_size, ret, transferred;
 394
 395         if (data && size+USBTMC_BULK_HEADER_SIZE+3 > (int)sizeof(uscpi->buffer)) {
 396                 sr_err("USBTMC bulk out transfer is too big.");
 397                 return SR_ERR;
 398         }
 399
 400         uscpi->bTag++;
 401         uscpi->bTag += !uscpi->bTag;  /* bTag == 0 is invalid so avoid it. */
 402
 403         usbtmc_bulk_out_header_write(uscpi->buffer, msg_id, uscpi->bTag,
 404                                      size, transfer_attributes, 0);
 405         if (data)
 406                 memcpy(uscpi->buffer+USBTMC_BULK_HEADER_SIZE, data, size);
 407         else
 408                 size = 0;
 409         size += USBTMC_BULK_HEADER_SIZE;
 410         padded_size = (size + 3) & ~0x3;
 411         memset(uscpi->buffer+size, 0, padded_size - size);
 412
 413         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_out_ep,
 414                                    uscpi->buffer, padded_size, &transferred,
 415                                    TRANSFER_TIMEOUT);
 416         if (ret < 0) {
 417                 sr_err("USBTMC bulk out transfer error: %s.",
 418                        libusb_error_name(ret));
 419                 return SR_ERR;
 420         }
 421
 422         if (transferred < padded_size) {
 423                 sr_dbg("USBTMC bulk out partial transfer (%d/%d bytes).",
 424                        transferred, padded_size);
 425                 return SR_ERR;
 426         }
 427
 428         return transferred - USBTMC_BULK_HEADER_SIZE;
 429 }
 430
 431 static int scpi_usbtmc_bulkin_start(struct scpi_usbtmc_libusb *uscpi,
 432                                     uint8_t msg_id, void *data, int32_t size,
 433                                     uint8_t *transfer_attributes)
 434 {
 435         struct sr_usb_dev_inst *usb = uscpi->usb;
 436         int ret, transferred, message_size;
 437
 438         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 439                                    &transferred, TRANSFER_TIMEOUT);
 440         if (ret < 0) {
 441                 sr_err("USBTMC bulk in transfer error: %s.",
 442                        libusb_error_name(ret));
 443                 return SR_ERR;
 444         }
 445
 446         if (usbtmc_bulk_in_header_read(data, msg_id, uscpi->bTag, &message_size,
 447                                        transfer_attributes) != SR_OK) {
 448                 sr_err("USBTMC invalid bulk in header.");
 449                 return SR_ERR;
 450         }
 451
 452         message_size += USBTMC_BULK_HEADER_SIZE;
 453         uscpi->response_length = MIN(transferred, message_size);
 454         uscpi->response_bytes_read = USBTMC_BULK_HEADER_SIZE;
 455         uscpi->remaining_length = message_size - uscpi->response_length;
 456
 457         return transferred - USBTMC_BULK_HEADER_SIZE;
 458 }
 459
 460 static int scpi_usbtmc_bulkin_continue(struct scpi_usbtmc_libusb *uscpi,
 461                                        void *data, int size)
 462 {
 463         struct sr_usb_dev_inst *usb = uscpi->usb;
 464         int ret, transferred;
 465
 466         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 467                                    &transferred, TRANSFER_TIMEOUT);
 468         if (ret < 0) {
 469                 sr_err("USBTMC bulk in transfer error: %s.",
 470                        libusb_error_name(ret));
 471                 return SR_ERR;
 472         }
 473
 474         uscpi->response_length = MIN(transferred, uscpi->remaining_length);
 475         uscpi->response_bytes_read = 0;
 476         uscpi->remaining_length -= uscpi->response_length;
 477
 478         return transferred;
 479 }
 480
 481 static int scpi_usbtmc_libusb_send(void *priv, const char *command)
 482 {
 483         struct scpi_usbtmc_libusb *uscpi = priv;
 484
 485         if (scpi_usbtmc_bulkout(uscpi, DEV_DEP_MSG_OUT,
 486                                 command, strlen(command), EOM) <= 0)
 487                 return SR_ERR;
 488
 489         sr_spew("Successfully sent SCPI command: '%s'.", command);
 490
 491         return SR_OK;
 492 }
 493
 494 static int scpi_usbtmc_libusb_read_begin(void *priv)
 495 {
 496         struct scpi_usbtmc_libusb *uscpi = priv;
 497
 498         uscpi->remaining_length = 0;
 499
 500         if (scpi_usbtmc_bulkout(uscpi, REQUEST_DEV_DEP_MSG_IN,
 501             NULL, INT32_MAX, 0) < 0)
 502                 return SR_ERR;
 503         if (scpi_usbtmc_bulkin_start(uscpi, DEV_DEP_MSG_IN,
 504                                      uscpi->buffer, sizeof(uscpi->buffer),
 505                                      &uscpi->bulkin_attributes) < 0)
 506                 return SR_ERR;
 507
 508         return SR_OK;
 509 }
 510
 511 static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
 512 {
 513         struct scpi_usbtmc_libusb *uscpi = priv;
 514         int read_length;
 515
 516         if (uscpi->response_bytes_read >= uscpi->response_length) {
 517                 if (uscpi->remaining_length > 0) {
 518                         if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
 519                                                         sizeof(uscpi->buffer)) <= 0)
 520                                 return SR_ERR;
 521                 } else {
 522                         if (uscpi->bulkin_attributes & EOM)
 523                                 return SR_ERR;
 524                         if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
 525                                 return SR_ERR;
 526                 }
 527         }
 528
 529         read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
 530
 531         memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
 532
 533         uscpi->response_bytes_read += read_length;
 534
 535         return read_length;
 536 }
 537
 538 static int scpi_usbtmc_libusb_read_complete(void *priv)
 539 {
 540         struct scpi_usbtmc_libusb *uscpi = priv;
 541         return uscpi->response_bytes_read >= uscpi->response_length &&
 542                uscpi->remaining_length <= 0 &&
 543                uscpi->bulkin_attributes & EOM;
 544 }
 545
 546 static int scpi_usbtmc_libusb_close(void *priv)
 547 {
 548         int ret;
 549         struct scpi_usbtmc_libusb *uscpi = priv;
 550         struct sr_usb_dev_inst *usb = uscpi->usb;
 551         uint8_t status;
 552
 553         if (!usb->devhdl)
 554                 return SR_ERR;
 555
 556         if (!uscpi->rigol_ds1000) {
 557         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_in_ep)) < 0)
 558                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 559                        uscpi->bulk_in_ep, libusb_error_name(ret));
 560         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_out_ep)) < 0)
 561                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 562                        uscpi->bulk_out_ep, libusb_error_name(ret));
 563         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->interrupt_ep)) < 0)
 564                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 565                        uscpi->interrupt_ep, libusb_error_name(ret));
 566         }
 567
 568         if (uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1) {
 569                 sr_dbg("Returning local control.");
 570                 ret = libusb_control_transfer(usb->devhdl,
 571                                 LIBUSB_ENDPOINT_IN         |
 572                                 LIBUSB_REQUEST_TYPE_CLASS  |
 573                                 LIBUSB_RECIPIENT_INTERFACE,
 574                                 GO_TO_LOCAL, 1,
 575                                 uscpi->interface,
 576                                 &status, 1,
 577                                 TRANSFER_TIMEOUT);
 578                 if (ret < 0 || status != USBTMC_STATUS_SUCCESS)
 579                         sr_dbg("Failed to clear local lockout state.");
 580         }
 581
 582         if ((ret = libusb_release_interface(usb->devhdl, uscpi->interface)) < 0)
 583                 sr_err("Failed to release interface: %s.",
 584                        libusb_error_name(ret));
 585
 586         if (uscpi->detached_kernel_driver) {
 587                 if ((ret = libusb_attach_kernel_driver(usb->devhdl,
 588                                                 uscpi->interface)) < 0)
 589                         sr_err("Failed to re-attach kernel driver: %s.",
 590                                libusb_error_name(ret));
 591
 592                 uscpi->detached_kernel_driver = 0;
 593         }
 594         sr_usb_close(usb);
 595
 596         return SR_OK;
 597 }
 598
 599 static void scpi_usbtmc_libusb_free(void *priv)
 600 {
 601         struct scpi_usbtmc_libusb *uscpi = priv;
 602         sr_usb_dev_inst_free(uscpi->usb);
 603 }
 604
 605 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
 606         .name          = "USBTMC",
 607         .prefix        = "usbtmc",
 608         .priv_size     = sizeof(struct scpi_usbtmc_libusb),
 609         .scan          = scpi_usbtmc_libusb_scan,
 610         .dev_inst_new  = scpi_usbtmc_libusb_dev_inst_new,
 611         .open          = scpi_usbtmc_libusb_open,
 612         .source_add    = scpi_usbtmc_libusb_source_add,
 613         .source_remove = scpi_usbtmc_libusb_source_remove,
 614         .send          = scpi_usbtmc_libusb_send,
 615         .read_begin    = scpi_usbtmc_libusb_read_begin,
 616         .read_data     = scpi_usbtmc_libusb_read_data,
 617         .read_complete = scpi_usbtmc_libusb_read_complete,
 618         .close         = scpi_usbtmc_libusb_close,
 619         .free          = scpi_usbtmc_libusb_free,
 620 };