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 };
  49
  50 /* Some USBTMC-specific enums, as defined in the USBTMC standard. */
  51 #define SUBCLASS_USBTMC 0x03
  52 #define USBTMC_USB488   0x01
  53
  54 enum {
  55         /* USBTMC control requests */
  56         INITIATE_ABORT_BULK_OUT     =   1,
  57         CHECK_ABORT_BULK_OUT_STATUS =   2,
  58         INITIATE_ABORT_BULK_IN      =   3,
  59         CHECK_ABORT_BULK_IN_STATUS  =   4,
  60         INITIATE_CLEAR              =   5,
  61         CHECK_CLEAR_STATUS          =   6,
  62         GET_CAPABILITIES            =   7,
  63         INDICATOR_PULSE             =  64,
  64
  65         /* USB488 control requests */
  66         READ_STATUS_BYTE            = 128,
  67         REN_CONTROL                 = 160,
  68         GO_TO_LOCAL                 = 161,
  69         LOCAL_LOCKOUT               = 162,
  70 };
  71
  72 /* USBTMC status codes */
  73 #define USBTMC_STATUS_SUCCESS      0x01
  74
  75 /* USBTMC capabilities */
  76 #define USBTMC_INT_CAP_LISTEN_ONLY 0x01
  77 #define USBTMC_INT_CAP_TALK_ONLY   0x02
  78 #define USBTMC_INT_CAP_INDICATOR   0x04
  79
  80 #define USBTMC_DEV_CAP_TERMCHAR    0x01
  81
  82 #define USB488_DEV_CAP_DT1         0x01
  83 #define USB488_DEV_CAP_RL1         0x02
  84 #define USB488_DEV_CAP_SR1         0x04
  85 #define USB488_DEV_CAP_SCPI        0x08
  86
  87 /* Bulk messages constants */
  88 #define USBTMC_BULK_HEADER_SIZE 12
  89
  90 /* Bulk MsgID values */
  91 #define DEV_DEP_MSG_OUT        1
  92 #define REQUEST_DEV_DEP_MSG_IN 2
  93 #define DEV_DEP_MSG_IN         2
  94
  95 /* bmTransferAttributes */
  96 #define EOM               0x01
  97 #define TERM_CHAR_ENABLED 0x02
  98
  99 struct usbtmc_blacklist {
 100         uint16_t vid;
 101         uint16_t pid;
 102 };
 103
 104 /* Devices that publish RL1 support, but don't support it. */
 105 static struct usbtmc_blacklist blacklist_remote[] = {
 106         { 0x1ab1, 0x0588 }, /* Rigol DS1000 series */
 107         { 0x1ab1, 0x04b0 }, /* Rigol DS2000 series */
 108         { 0x0957, 0x0588 }, /* Agilent DSO1000 series (rebadged Rigol DS1000) */
 109         { 0x0b21, 0xffff }, /* All Yokogawa devices */
 110         { 0xf4ec, 0xffff }, /* All Siglent SDS devices */
 111         ALL_ZERO
 112 };
 113
 114 static GSList *scpi_usbtmc_libusb_scan(struct drv_context *drvc)
 115 {
 116         struct libusb_device **devlist;
 117         struct libusb_device_descriptor des;
 118         struct libusb_config_descriptor *confdes;
 119         const struct libusb_interface_descriptor *intfdes;
 120         GSList *resources = NULL;
 121         int confidx, intfidx, ret, i;
 122         char *res;
 123
 124         ret = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
 125         if (ret < 0) {
 126                 sr_err("Failed to get device list: %s.",
 127                        libusb_error_name(ret));
 128                 return NULL;
 129         }
 130         for (i = 0; devlist[i]; i++) {
 131                 libusb_get_device_descriptor(devlist[i], &des);
 132
 133                 for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 134                         if ((ret = libusb_get_config_descriptor(devlist[i], confidx, &confdes)) < 0) {
 135                                 sr_dbg("Failed to get configuration descriptor: %s, "
 136                                        "ignoring device.", libusb_error_name(ret));
 137                                 break;
 138                         }
 139                         for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 140                                 intfdes = confdes->interface[intfidx].altsetting;
 141                                 if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 142                                     intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 143                                     intfdes->bInterfaceProtocol != USBTMC_USB488)
 144                                         continue;
 145                                 sr_dbg("Found USBTMC device (VID:PID = %04x:%04x, "
 146                                        "bus.address = %d.%d).", des.idVendor, des.idProduct,
 147                                        libusb_get_bus_number(devlist[i]),
 148                                        libusb_get_device_address(devlist[i]));
 149                                 res = g_strdup_printf("usbtmc/%d.%d",
 150                                                       libusb_get_bus_number(devlist[i]),
 151                                                       libusb_get_device_address(devlist[i]));
 152                                 resources = g_slist_append(resources, res);
 153                         }
 154                         libusb_free_config_descriptor(confdes);
 155                 }
 156         }
 157         libusb_free_device_list(devlist, 1);
 158
 159         /* No log message for #devices found (caller will log that). */
 160
 161         return resources;
 162 }
 163
 164 static int scpi_usbtmc_libusb_dev_inst_new(void *priv, struct drv_context *drvc,
 165                 const char *resource, char **params, const char *serialcomm)
 166 {
 167         struct scpi_usbtmc_libusb *uscpi = priv;
 168         GSList *devices;
 169
 170         (void)resource;
 171         (void)serialcomm;
 172
 173         if (!params || !params[1]) {
 174                 sr_err("Invalid parameters.");
 175                 return SR_ERR;
 176         }
 177
 178         uscpi->ctx = drvc->sr_ctx;
 179         devices = sr_usb_find(uscpi->ctx->libusb_ctx, params[1]);
 180         if (g_slist_length(devices) != 1) {
 181                 sr_err("Failed to find USB device '%s'.", params[1]);
 182                 g_slist_free_full(devices, (GDestroyNotify)sr_usb_dev_inst_free);
 183                 return SR_ERR;
 184         }
 185         uscpi->usb = devices->data;
 186         g_slist_free(devices);
 187
 188         return SR_OK;
 189 }
 190
 191 static int check_usbtmc_blacklist(struct usbtmc_blacklist *blacklist,
 192                 uint16_t vid, uint16_t pid)
 193 {
 194         int i;
 195
 196         for (i = 0; blacklist[i].vid; i++) {
 197                 if ((blacklist[i].vid == vid && blacklist[i].pid == 0xFFFF) ||
 198                         (blacklist[i].vid == vid && blacklist[i].pid == pid))
 199                         return TRUE;
 200         }
 201
 202         return FALSE;
 203 }
 204
 205 static int scpi_usbtmc_remote(struct scpi_usbtmc_libusb *uscpi)
 206 {
 207         struct sr_usb_dev_inst *usb = uscpi->usb;
 208         struct libusb_device *dev;
 209         struct libusb_device_descriptor des;
 210         int ret;
 211         uint8_t status;
 212
 213         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 214                 return SR_OK;
 215
 216         dev = libusb_get_device(usb->devhdl);
 217         libusb_get_device_descriptor(dev, &des);
 218         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 219                 return SR_OK;
 220
 221         sr_dbg("Locking out local control.");
 222         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 223                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 224                 REN_CONTROL, 1, uscpi->interface, &status, 1, TRANSFER_TIMEOUT);
 225         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 226                 if (ret < 0)
 227                         sr_dbg("Failed to enter REN state: %s.", libusb_error_name(ret));
 228                 else
 229                         sr_dbg("Failed to enter REN state: USBTMC status %d.", status);
 230                 return SR_ERR;
 231         }
 232
 233         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 234                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 235                 LOCAL_LOCKOUT, 0, uscpi->interface, &status, 1,
 236                 TRANSFER_TIMEOUT);
 237         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 238                 if (ret < 0)
 239                         sr_dbg("Failed to enter local lockout state: %s.",
 240                                         libusb_error_name(ret));
 241                 else
 242                         sr_dbg("Failed to enter local lockout state: USBTMC "
 243                                         "status %d.", status);
 244                 return SR_ERR;
 245         }
 246
 247         return SR_OK;
 248 }
 249
 250 static void scpi_usbtmc_local(struct scpi_usbtmc_libusb *uscpi)
 251 {
 252         struct sr_usb_dev_inst *usb = uscpi->usb;
 253         struct libusb_device *dev;
 254         struct libusb_device_descriptor des;
 255         int ret;
 256         uint8_t status;
 257
 258         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 259                 return;
 260
 261         dev = libusb_get_device(usb->devhdl);
 262         libusb_get_device_descriptor(dev, &des);
 263         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 264                 return;
 265
 266         sr_dbg("Returning local control.");
 267         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 268                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 269                 GO_TO_LOCAL, 0, uscpi->interface, &status, 1, TRANSFER_TIMEOUT);
 270         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 271                 if (ret < 0)
 272                         sr_dbg("Failed to clear local lockout state: %s.",
 273                                         libusb_error_name(ret));
 274                 else
 275                         sr_dbg("Failed to clear local lockout state: USBTMC "
 276                                         "status %d.", status);
 277         }
 278
 279         return;
 280 }
 281
 282 static int scpi_usbtmc_libusb_open(struct sr_scpi_dev_inst *scpi)
 283 {
 284         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 285         struct sr_usb_dev_inst *usb = uscpi->usb;
 286         struct libusb_device *dev;
 287         struct libusb_device_descriptor des;
 288         struct libusb_config_descriptor *confdes;
 289         const struct libusb_interface_descriptor *intfdes;
 290         const struct libusb_endpoint_descriptor *ep;
 291         int confidx, intfidx, epidx, config = 0, current_config;
 292         uint8_t capabilities[24];
 293         int ret, found = 0;
 294
 295         if (usb->devhdl)
 296                 return SR_OK;
 297
 298         if (sr_usb_open(uscpi->ctx->libusb_ctx, usb) != SR_OK)
 299                 return SR_ERR;
 300
 301         dev = libusb_get_device(usb->devhdl);
 302         libusb_get_device_descriptor(dev, &des);
 303
 304         for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 305                 if ((ret = libusb_get_config_descriptor(dev, confidx, &confdes)) < 0) {
 306                         sr_dbg("Failed to get configuration descriptor: %s, "
 307                                "ignoring device.", libusb_error_name(ret));
 308                         continue;
 309                 }
 310                 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 311                         intfdes = confdes->interface[intfidx].altsetting;
 312                         if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 313                             intfdes->bInterfaceSubClass != SUBCLASS_USBTMC ||
 314                             intfdes->bInterfaceProtocol != USBTMC_USB488)
 315                                 continue;
 316                         uscpi->interface = intfdes->bInterfaceNumber;
 317                         config = confdes->bConfigurationValue;
 318                         sr_dbg("Interface %d configuration %d.", uscpi->interface, config);
 319                         for (epidx = 0; epidx < intfdes->bNumEndpoints; epidx++) {
 320                                 ep = &intfdes->endpoint[epidx];
 321                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 322                                     !(ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK))) {
 323                                         uscpi->bulk_out_ep = ep->bEndpointAddress;
 324                                         sr_dbg("Bulk OUT EP %d", uscpi->bulk_out_ep);
 325                                 }
 326                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 327                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 328                                         uscpi->bulk_in_ep = ep->bEndpointAddress;
 329                                         sr_dbg("Bulk IN EP %d", uscpi->bulk_in_ep & 0x7f);
 330                                 }
 331                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_INTERRUPT &&
 332                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 333                                         uscpi->interrupt_ep = ep->bEndpointAddress;
 334                                         sr_dbg("Interrupt EP %d", uscpi->interrupt_ep & 0x7f);
 335                                 }
 336                         }
 337                         found = 1;
 338                 }
 339                 libusb_free_config_descriptor(confdes);
 340                 if (found)
 341                         break;
 342         }
 343
 344         if (!found) {
 345                 sr_err("Failed to find USBTMC interface.");
 346                 return SR_ERR;
 347         }
 348
 349         if (libusb_kernel_driver_active(usb->devhdl, uscpi->interface) == 1) {
 350                 if ((ret = libusb_detach_kernel_driver(usb->devhdl,
 351                                                        uscpi->interface)) < 0) {
 352                         sr_err("Failed to detach kernel driver: %s.",
 353                                libusb_error_name(ret));
 354                         return SR_ERR;
 355                 }
 356                 uscpi->detached_kernel_driver = 1;
 357         }
 358
 359         if (libusb_get_configuration(usb->devhdl, &current_config) == 0
 360             && current_config != config) {
 361                 if ((ret = libusb_set_configuration(usb->devhdl, config)) < 0) {
 362                         sr_err("Failed to set configuration: %s.",
 363                                libusb_error_name(ret));
 364                         return SR_ERR;
 365                 }
 366         }
 367
 368         if ((ret = libusb_claim_interface(usb->devhdl, uscpi->interface)) < 0) {
 369                 sr_err("Failed to claim interface: %s.",
 370                        libusb_error_name(ret));
 371                 return SR_ERR;
 372         }
 373
 374         libusb_reset_device(usb->devhdl);
 375
 376         /* Get capabilities. */
 377         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 378                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 379                 GET_CAPABILITIES, 0, uscpi->interface, capabilities,
 380                 sizeof(capabilities), TRANSFER_TIMEOUT);
 381         if (ret == sizeof(capabilities)) {
 382                 uscpi->usbtmc_int_cap = capabilities[ 4];
 383                 uscpi->usbtmc_dev_cap = capabilities[ 5];
 384                 uscpi->usb488_dev_cap = capabilities[15];
 385         }
 386         sr_dbg("Device capabilities: %s%s%s%s%s, %s, %s",
 387                uscpi->usb488_dev_cap & USB488_DEV_CAP_SCPI        ? "SCPI, "    : "",
 388                uscpi->usbtmc_dev_cap & USBTMC_DEV_CAP_TERMCHAR    ? "TermChar, ": "",
 389                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY ? "L3, " :
 390                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY   ? ""     : "L4, ",
 391                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY   ? "T5, " :
 392                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY ? ""     : "T6, ",
 393                uscpi->usb488_dev_cap & USB488_DEV_CAP_SR1         ? "SR1"  : "SR0",
 394                uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1         ? "RL1"  : "RL0",
 395                uscpi->usb488_dev_cap & USB488_DEV_CAP_DT1         ? "DT1"  : "DT0");
 396
 397         scpi_usbtmc_remote(uscpi);
 398
 399         return SR_OK;
 400 }
 401
 402 static int scpi_usbtmc_libusb_source_add(struct sr_session *session,
 403                 void *priv, int events, int timeout, sr_receive_data_callback cb,
 404                 void *cb_data)
 405 {
 406         struct scpi_usbtmc_libusb *uscpi = priv;
 407         (void)events;
 408         return usb_source_add(session, uscpi->ctx, timeout, cb, cb_data);
 409 }
 410
 411 static int scpi_usbtmc_libusb_source_remove(struct sr_session *session,
 412                 void *priv)
 413 {
 414         struct scpi_usbtmc_libusb *uscpi = priv;
 415         return usb_source_remove(session, uscpi->ctx);
 416 }
 417
 418 static void usbtmc_bulk_out_header_write(void *header, uint8_t MsgID,
 419                                          uint8_t bTag,
 420                                          uint32_t TransferSize,
 421                                          uint8_t bmTransferAttributes,
 422                                          char TermChar)
 423 {
 424           W8(header +  0, MsgID);
 425           W8(header +  1, bTag);
 426           W8(header +  2, ~bTag);
 427           W8(header +  3, 0);
 428         WL32(header +  4, TransferSize);
 429           W8(header +  8, bmTransferAttributes);
 430           W8(header +  9, TermChar);
 431         WL16(header + 10, 0);
 432 }
 433
 434 static int usbtmc_bulk_in_header_read(void *header, uint8_t MsgID,
 435                                       unsigned char bTag,
 436                                       int32_t *TransferSize,
 437                                       uint8_t *bmTransferAttributes)
 438 {
 439         if (R8(header + 0) != MsgID ||
 440             R8(header + 1) != bTag  ||
 441             R8(header + 2) != (unsigned char)~bTag)
 442                 return SR_ERR;
 443         if (TransferSize)
 444                 *TransferSize = RL32(header + 4);
 445         if (bmTransferAttributes)
 446                 *bmTransferAttributes = R8(header + 8);
 447
 448         return SR_OK;
 449 }
 450
 451 static int scpi_usbtmc_bulkout(struct scpi_usbtmc_libusb *uscpi,
 452                                uint8_t msg_id, const void *data, int32_t size,
 453                                uint8_t transfer_attributes)
 454 {
 455         struct sr_usb_dev_inst *usb = uscpi->usb;
 456         int padded_size, ret, transferred;
 457
 458         if (data && (size + USBTMC_BULK_HEADER_SIZE + 3) > (int)sizeof(uscpi->buffer)) {
 459                 sr_err("USBTMC bulk out transfer is too big.");
 460                 return SR_ERR;
 461         }
 462
 463         uscpi->bTag++;
 464         uscpi->bTag += !uscpi->bTag; /* bTag == 0 is invalid so avoid it. */
 465
 466         usbtmc_bulk_out_header_write(uscpi->buffer, msg_id, uscpi->bTag,
 467                                      size, transfer_attributes, 0);
 468         if (data)
 469                 memcpy(uscpi->buffer + USBTMC_BULK_HEADER_SIZE, data, size);
 470         else
 471                 size = 0;
 472         size += USBTMC_BULK_HEADER_SIZE;
 473         padded_size = (size + 3) & ~0x3;
 474         memset(uscpi->buffer + size, 0, padded_size - size);
 475
 476         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_out_ep,
 477                                    uscpi->buffer, padded_size, &transferred,
 478                                    TRANSFER_TIMEOUT);
 479         if (ret < 0) {
 480                 sr_err("USBTMC bulk out transfer error: %s.",
 481                        libusb_error_name(ret));
 482                 return SR_ERR;
 483         }
 484
 485         if (transferred < padded_size) {
 486                 sr_dbg("USBTMC bulk out partial transfer (%d/%d bytes).",
 487                        transferred, padded_size);
 488                 return SR_ERR;
 489         }
 490
 491         return transferred - USBTMC_BULK_HEADER_SIZE;
 492 }
 493
 494 static int scpi_usbtmc_bulkin_start(struct scpi_usbtmc_libusb *uscpi,
 495                                     uint8_t msg_id, void *data, int32_t size,
 496                                     uint8_t *transfer_attributes)
 497 {
 498         struct sr_usb_dev_inst *usb = uscpi->usb;
 499         int ret, transferred, message_size;
 500
 501         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 502                                    &transferred, TRANSFER_TIMEOUT);
 503         if (ret < 0) {
 504                 sr_err("USBTMC bulk in transfer error: %s.",
 505                        libusb_error_name(ret));
 506                 return SR_ERR;
 507         }
 508
 509         if (usbtmc_bulk_in_header_read(data, msg_id, uscpi->bTag, &message_size,
 510                                        transfer_attributes) != SR_OK) {
 511                 sr_err("USBTMC invalid bulk in header.");
 512                 return SR_ERR;
 513         }
 514
 515         message_size += USBTMC_BULK_HEADER_SIZE;
 516         uscpi->response_length = MIN(transferred, message_size);
 517         uscpi->response_bytes_read = USBTMC_BULK_HEADER_SIZE;
 518         uscpi->remaining_length = message_size - uscpi->response_length;
 519
 520         return transferred - USBTMC_BULK_HEADER_SIZE;
 521 }
 522
 523 static int scpi_usbtmc_bulkin_continue(struct scpi_usbtmc_libusb *uscpi,
 524                                        void *data, int size)
 525 {
 526         struct sr_usb_dev_inst *usb = uscpi->usb;
 527         int ret, transferred;
 528
 529         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 530                                    &transferred, TRANSFER_TIMEOUT);
 531         if (ret < 0) {
 532                 sr_err("USBTMC bulk in transfer error: %s.",
 533                        libusb_error_name(ret));
 534                 return SR_ERR;
 535         }
 536
 537         uscpi->response_length = MIN(transferred, uscpi->remaining_length);
 538         uscpi->response_bytes_read = 0;
 539         uscpi->remaining_length -= uscpi->response_length;
 540
 541         return transferred;
 542 }
 543
 544 static int scpi_usbtmc_libusb_send(void *priv, const char *command)
 545 {
 546         struct scpi_usbtmc_libusb *uscpi = priv;
 547
 548         if (scpi_usbtmc_bulkout(uscpi, DEV_DEP_MSG_OUT,
 549                                 command, strlen(command), EOM) <= 0)
 550                 return SR_ERR;
 551
 552         sr_spew("Successfully sent SCPI command: '%s'.", command);
 553
 554         return SR_OK;
 555 }
 556
 557 static int scpi_usbtmc_libusb_read_begin(void *priv)
 558 {
 559         struct scpi_usbtmc_libusb *uscpi = priv;
 560
 561         uscpi->remaining_length = 0;
 562
 563         if (scpi_usbtmc_bulkout(uscpi, REQUEST_DEV_DEP_MSG_IN,
 564             NULL, INT32_MAX, 0) < 0)
 565                 return SR_ERR;
 566         if (scpi_usbtmc_bulkin_start(uscpi, DEV_DEP_MSG_IN,
 567                                      uscpi->buffer, sizeof(uscpi->buffer),
 568                                      &uscpi->bulkin_attributes) < 0)
 569                 return SR_ERR;
 570
 571         return SR_OK;
 572 }
 573
 574 static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
 575 {
 576         struct scpi_usbtmc_libusb *uscpi = priv;
 577         int read_length;
 578
 579         if (uscpi->response_bytes_read >= uscpi->response_length) {
 580                 if (uscpi->remaining_length > 0) {
 581                         if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
 582                                                         sizeof(uscpi->buffer)) <= 0)
 583                                 return SR_ERR;
 584                 } else {
 585                         if (uscpi->bulkin_attributes & EOM)
 586                                 return SR_ERR;
 587                         if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
 588                                 return SR_ERR;
 589                 }
 590         }
 591
 592         read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
 593
 594         memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
 595
 596         uscpi->response_bytes_read += read_length;
 597
 598         return read_length;
 599 }
 600
 601 static int scpi_usbtmc_libusb_read_complete(void *priv)
 602 {
 603         struct scpi_usbtmc_libusb *uscpi = priv;
 604         return uscpi->response_bytes_read >= uscpi->response_length &&
 605                uscpi->remaining_length <= 0 &&
 606                uscpi->bulkin_attributes & EOM;
 607 }
 608
 609 static int scpi_usbtmc_libusb_close(struct sr_scpi_dev_inst *scpi)
 610 {
 611         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 612         struct sr_usb_dev_inst *usb = uscpi->usb;
 613         int ret;
 614
 615         if (!usb->devhdl)
 616                 return SR_ERR;
 617
 618         scpi_usbtmc_local(uscpi);
 619
 620         if ((ret = libusb_release_interface(usb->devhdl, uscpi->interface)) < 0)
 621                 sr_err("Failed to release interface: %s.",
 622                        libusb_error_name(ret));
 623
 624         if (uscpi->detached_kernel_driver) {
 625                 if ((ret = libusb_attach_kernel_driver(usb->devhdl,
 626                                                 uscpi->interface)) < 0)
 627                         sr_err("Failed to re-attach kernel driver: %s.",
 628                                libusb_error_name(ret));
 629
 630                 uscpi->detached_kernel_driver = 0;
 631         }
 632         sr_usb_close(usb);
 633
 634         return SR_OK;
 635 }
 636
 637 static void scpi_usbtmc_libusb_free(void *priv)
 638 {
 639         struct scpi_usbtmc_libusb *uscpi = priv;
 640         sr_usb_dev_inst_free(uscpi->usb);
 641 }
 642
 643 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
 644         .name          = "USBTMC",
 645         .prefix        = "usbtmc",
 646         .priv_size     = sizeof(struct scpi_usbtmc_libusb),
 647         .scan          = scpi_usbtmc_libusb_scan,
 648         .dev_inst_new  = scpi_usbtmc_libusb_dev_inst_new,
 649         .open          = scpi_usbtmc_libusb_open,
 650         .source_add    = scpi_usbtmc_libusb_source_add,
 651         .source_remove = scpi_usbtmc_libusb_source_remove,
 652         .send          = scpi_usbtmc_libusb_send,
 653         .read_begin    = scpi_usbtmc_libusb_read_begin,
 654         .read_data     = scpi_usbtmc_libusb_read_data,
 655         .read_complete = scpi_usbtmc_libusb_read_complete,
 656         .close         = scpi_usbtmc_libusb_close,
 657         .free          = scpi_usbtmc_libusb_free,
 658 };