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         ALL_ZERO
 111 };
 112
 113 static GSList *scpi_usbtmc_libusb_scan(struct drv_context *drvc)
 114 {
 115         struct libusb_device **devlist;
 116         struct libusb_device_descriptor des;
 117         struct libusb_config_descriptor *confdes;
 118         const struct libusb_interface_descriptor *intfdes;
 119         GSList *resources = NULL;
 120         int confidx, intfidx, ret, i;
 121         char *res;
 122
 123         ret = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
 124         if (ret < 0) {
 125                 sr_err("Failed to get device list: %s.",
 126                        libusb_error_name(ret));
 127                 return NULL;
 128         }
 129         for (i = 0; devlist[i]; i++) {
 130                 libusb_get_device_descriptor(devlist[i], &des);
 131
 132                 for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 133                         if ((ret = libusb_get_config_descriptor(devlist[i], confidx, &confdes)) < 0) {
 134                                 sr_dbg("Failed to get configuration descriptor: %s, "
 135                                        "ignoring device.", libusb_error_name(ret));
 136                                 break;
 137                         }
 138                         for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 139                                 intfdes = confdes->interface[intfidx].altsetting;
 140                                 if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 141                                     intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 142                                     intfdes->bInterfaceProtocol != USBTMC_USB488)
 143                                         continue;
 144                                 sr_dbg("Found USBTMC device (VID:PID = %04x:%04x, "
 145                                        "bus.address = %d.%d).", des.idVendor, des.idProduct,
 146                                        libusb_get_bus_number(devlist[i]),
 147                                        libusb_get_device_address(devlist[i]));
 148                                 res = g_strdup_printf("usbtmc/%d.%d",
 149                                                       libusb_get_bus_number(devlist[i]),
 150                                                       libusb_get_device_address(devlist[i]));
 151                                 resources = g_slist_append(resources, res);
 152                         }
 153                         libusb_free_config_descriptor(confdes);
 154                 }
 155         }
 156         libusb_free_device_list(devlist, 1);
 157
 158         sr_dbg("Found %d device(s).", g_slist_length(resources));
 159
 160         return resources;
 161 }
 162
 163 static int scpi_usbtmc_libusb_dev_inst_new(void *priv, struct drv_context *drvc,
 164                 const char *resource, char **params, const char *serialcomm)
 165 {
 166         struct scpi_usbtmc_libusb *uscpi = priv;
 167         GSList *devices;
 168
 169         (void)resource;
 170         (void)serialcomm;
 171
 172         if (!params || !params[1]) {
 173                 sr_err("Invalid parameters.");
 174                 return SR_ERR;
 175         }
 176
 177         uscpi->ctx = drvc->sr_ctx;
 178         devices = sr_usb_find(uscpi->ctx->libusb_ctx, params[1]);
 179         if (g_slist_length(devices) != 1) {
 180                 sr_err("Failed to find USB device '%s'.", params[1]);
 181                 g_slist_free_full(devices, (GDestroyNotify)sr_usb_dev_inst_free);
 182                 return SR_ERR;
 183         }
 184         uscpi->usb = devices->data;
 185         g_slist_free(devices);
 186
 187         return SR_OK;
 188 }
 189
 190 static int check_usbtmc_blacklist(struct usbtmc_blacklist *blacklist,
 191                 uint16_t vid, uint16_t pid)
 192 {
 193         int i;
 194
 195         for (i = 0; blacklist[i].vid; i++) {
 196                 if ((blacklist[i].vid == vid && blacklist[i].pid == 0xFFFF) ||
 197                         (blacklist[i].vid == vid && blacklist[i].pid == pid))
 198                         return TRUE;
 199         }
 200
 201         return FALSE;
 202 }
 203
 204 static int scpi_usbtmc_remote(struct scpi_usbtmc_libusb *uscpi)
 205 {
 206         struct sr_usb_dev_inst *usb = uscpi->usb;
 207         struct libusb_device *dev;
 208         struct libusb_device_descriptor des;
 209         int ret;
 210         uint8_t status;
 211
 212         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 213                 return SR_OK;
 214
 215         dev = libusb_get_device(usb->devhdl);
 216         libusb_get_device_descriptor(dev, &des);
 217         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 218                 return SR_OK;
 219
 220         sr_dbg("Locking out local control.");
 221         ret = libusb_control_transfer(usb->devhdl,
 222                         LIBUSB_ENDPOINT_IN         |
 223                         LIBUSB_REQUEST_TYPE_CLASS  |
 224                         LIBUSB_RECIPIENT_INTERFACE,
 225                         REN_CONTROL, 1,
 226                         uscpi->interface,
 227                         &status, 1,
 228                         TRANSFER_TIMEOUT);
 229         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 230                 if (ret < 0)
 231                         sr_dbg("Failed to enter REN state: %s.", libusb_error_name(ret));
 232                 else
 233                         sr_dbg("Failed to enter REN state: USBTMC status %d.", status);
 234                 return SR_ERR;
 235         }
 236
 237         ret = libusb_control_transfer(usb->devhdl,
 238                         LIBUSB_ENDPOINT_IN         |
 239                         LIBUSB_REQUEST_TYPE_CLASS  |
 240                         LIBUSB_RECIPIENT_INTERFACE,
 241                         LOCAL_LOCKOUT, 1,
 242                         uscpi->interface,
 243                         &status, 1,
 244                         TRANSFER_TIMEOUT);
 245         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 246                 if (ret < 0)
 247                         sr_dbg("Failed to enter local lockout state: %s.",
 248                                         libusb_error_name(ret));
 249                 else
 250                         sr_dbg("Failed to enter local lockout state: USBTMC "
 251                                         "status %d.", status);
 252                 return SR_ERR;
 253         }
 254
 255         return SR_OK;
 256 }
 257
 258 static void scpi_usbtmc_local(struct scpi_usbtmc_libusb *uscpi)
 259 {
 260         struct sr_usb_dev_inst *usb = uscpi->usb;
 261         struct libusb_device *dev;
 262         struct libusb_device_descriptor des;
 263         int ret;
 264         uint8_t status;
 265
 266         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 267                 return;
 268
 269         dev = libusb_get_device(usb->devhdl);
 270         libusb_get_device_descriptor(dev, &des);
 271         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 272                 return;
 273
 274         sr_dbg("Returning local control.");
 275         ret = libusb_control_transfer(usb->devhdl,
 276                         LIBUSB_ENDPOINT_IN         |
 277                         LIBUSB_REQUEST_TYPE_CLASS  |
 278                         LIBUSB_RECIPIENT_INTERFACE,
 279                         GO_TO_LOCAL, 1,
 280                         uscpi->interface,
 281                         &status, 1,
 282                         TRANSFER_TIMEOUT);
 283         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 284                 if (ret < 0)
 285                         sr_dbg("Failed to clear local lockout state: %s.",
 286                                         libusb_error_name(ret));
 287                 else
 288                         sr_dbg("Failed to clear local lockout state: USBTMC "
 289                                         "status %d.", status);
 290         }
 291
 292         return;
 293 }
 294
 295 static int scpi_usbtmc_libusb_open(struct sr_scpi_dev_inst *scpi)
 296 {
 297         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 298         struct sr_usb_dev_inst *usb = uscpi->usb;
 299         struct libusb_device *dev;
 300         struct libusb_device_descriptor des;
 301         struct libusb_config_descriptor *confdes;
 302         const struct libusb_interface_descriptor *intfdes;
 303         const struct libusb_endpoint_descriptor *ep;
 304         int confidx, intfidx, epidx, config = 0, current_config;
 305         uint8_t capabilities[24];
 306         int ret, found = 0;
 307
 308         if (usb->devhdl)
 309                 return SR_OK;
 310
 311         if (sr_usb_open(uscpi->ctx->libusb_ctx, usb) != SR_OK)
 312                 return SR_ERR;
 313
 314         dev = libusb_get_device(usb->devhdl);
 315         libusb_get_device_descriptor(dev, &des);
 316
 317         for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 318                 if ((ret = libusb_get_config_descriptor(dev, confidx, &confdes)) < 0) {
 319                         sr_dbg("Failed to get configuration descriptor: %s, "
 320                                "ignoring device.", libusb_error_name(ret));
 321                         continue;
 322                 }
 323                 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 324                         intfdes = confdes->interface[intfidx].altsetting;
 325                         if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 326                             intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 327                             intfdes->bInterfaceProtocol != USBTMC_USB488)
 328                                 continue;
 329                         uscpi->interface = intfdes->bInterfaceNumber;
 330                         config = confdes->bConfigurationValue;
 331                         sr_dbg("Interface %d configuration %d.", uscpi->interface, config);
 332                         for (epidx = 0; epidx < intfdes->bNumEndpoints; epidx++) {
 333                                 ep = &intfdes->endpoint[epidx];
 334                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 335                                     !(ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK))) {
 336                                         uscpi->bulk_out_ep = ep->bEndpointAddress;
 337                                         sr_dbg("Bulk OUT EP %d", uscpi->bulk_out_ep);
 338                                 }
 339                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 340                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 341                                         uscpi->bulk_in_ep = ep->bEndpointAddress;
 342                                         sr_dbg("Bulk IN EP %d", uscpi->bulk_in_ep & 0x7f);
 343                                 }
 344                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_INTERRUPT &&
 345                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 346                                         uscpi->interrupt_ep = ep->bEndpointAddress;
 347                                         sr_dbg("Interrupt EP %d", uscpi->interrupt_ep & 0x7f);
 348                                 }
 349                         }
 350                         found = 1;
 351                 }
 352                 libusb_free_config_descriptor(confdes);
 353                 if (found)
 354                         break;
 355         }
 356
 357         if (!found) {
 358                 sr_err("Failed to find USBTMC interface.");
 359                 return SR_ERR;
 360         }
 361
 362         if (libusb_kernel_driver_active(usb->devhdl, uscpi->interface) == 1) {
 363                 if ((ret = libusb_detach_kernel_driver(usb->devhdl,
 364                                                        uscpi->interface)) < 0) {
 365                         sr_err("Failed to detach kernel driver: %s.",
 366                                libusb_error_name(ret));
 367                         return SR_ERR;
 368                 }
 369                 uscpi->detached_kernel_driver = 1;
 370         }
 371
 372         if (libusb_get_configuration(usb->devhdl, &current_config) == 0
 373             && current_config != config) {
 374                 if ((ret = libusb_set_configuration(usb->devhdl, config)) < 0) {
 375                         sr_err("Failed to set configuration: %s.",
 376                                libusb_error_name(ret));
 377                         return SR_ERR;
 378                 }
 379         }
 380
 381         if ((ret = libusb_claim_interface(usb->devhdl, uscpi->interface)) < 0) {
 382                 sr_err("Failed to claim interface: %s.",
 383                        libusb_error_name(ret));
 384                 return SR_ERR;
 385         }
 386
 387         /* Get capabilities. */
 388         ret = libusb_control_transfer(usb->devhdl,
 389                                       LIBUSB_ENDPOINT_IN         |
 390                                       LIBUSB_REQUEST_TYPE_CLASS  |
 391                                       LIBUSB_RECIPIENT_INTERFACE,
 392                                       GET_CAPABILITIES, 0,
 393                                       uscpi->interface,
 394                                       capabilities, sizeof(capabilities),
 395                                       TRANSFER_TIMEOUT);
 396         if (ret == sizeof(capabilities)) {
 397                 uscpi->usbtmc_int_cap = capabilities[ 4];
 398                 uscpi->usbtmc_dev_cap = capabilities[ 5];
 399                 uscpi->usb488_dev_cap = capabilities[15];
 400         }
 401         sr_dbg("Device capabilities: %s%s%s%s%s, %s, %s",
 402                uscpi->usb488_dev_cap & USB488_DEV_CAP_SCPI       ? "SCPI, "    : "",
 403                uscpi->usbtmc_dev_cap & USBTMC_DEV_CAP_TERMCHAR   ? "TermChar, ": "",
 404                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? "L3, " :
 405                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? ""     : "L4, ",
 406                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? "T5, " :
 407                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? ""     : "T6, ",
 408                uscpi->usb488_dev_cap & USB488_DEV_CAP_SR1        ? "SR1"  : "SR0",
 409                uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1        ? "RL1"  : "RL0",
 410                uscpi->usb488_dev_cap & USB488_DEV_CAP_DT1        ? "DT1"  : "DT0");
 411
 412         scpi_usbtmc_remote(uscpi);
 413
 414         return SR_OK;
 415 }
 416
 417 static int scpi_usbtmc_libusb_source_add(struct sr_session *session,
 418                 void *priv, int events, int timeout, sr_receive_data_callback cb,
 419                 void *cb_data)
 420 {
 421         struct scpi_usbtmc_libusb *uscpi = priv;
 422         (void)events;
 423         return usb_source_add(session, uscpi->ctx, timeout, cb, cb_data);
 424 }
 425
 426 static int scpi_usbtmc_libusb_source_remove(struct sr_session *session,
 427                 void *priv)
 428 {
 429         struct scpi_usbtmc_libusb *uscpi = priv;
 430         return usb_source_remove(session, uscpi->ctx);
 431 }
 432
 433 static void usbtmc_bulk_out_header_write(void *header, uint8_t MsgID,
 434                                          uint8_t bTag,
 435                                          uint32_t TransferSize,
 436                                          uint8_t bmTransferAttributes,
 437                                          char TermChar)
 438 {
 439           W8(header+ 0, MsgID);
 440           W8(header+ 1, bTag);
 441           W8(header+ 2, ~bTag);
 442           W8(header+ 3, 0);
 443         WL32(header+ 4, TransferSize);
 444           W8(header+ 8, bmTransferAttributes);
 445           W8(header+ 9, TermChar);
 446         WL16(header+10, 0);
 447 }
 448
 449 static int usbtmc_bulk_in_header_read(void *header, uint8_t MsgID,
 450                                       unsigned char bTag,
 451                                       int32_t *TransferSize,
 452                                       uint8_t *bmTransferAttributes)
 453 {
 454         if (R8(header+0) != MsgID ||
 455             R8(header+1) != bTag  ||
 456             R8(header+2) != (unsigned char)~bTag)
 457                 return SR_ERR;
 458         if (TransferSize)
 459                 *TransferSize = RL32(header+4);
 460         if (bmTransferAttributes)
 461                 *bmTransferAttributes = R8(header+8);
 462         return SR_OK;
 463 }
 464
 465 static int scpi_usbtmc_bulkout(struct scpi_usbtmc_libusb *uscpi,
 466                                uint8_t msg_id, const void *data, int32_t size,
 467                                uint8_t transfer_attributes)
 468 {
 469         struct sr_usb_dev_inst *usb = uscpi->usb;
 470         int padded_size, ret, transferred;
 471
 472         if (data && size+USBTMC_BULK_HEADER_SIZE+3 > (int)sizeof(uscpi->buffer)) {
 473                 sr_err("USBTMC bulk out transfer is too big.");
 474                 return SR_ERR;
 475         }
 476
 477         uscpi->bTag++;
 478         uscpi->bTag += !uscpi->bTag;  /* bTag == 0 is invalid so avoid it. */
 479
 480         usbtmc_bulk_out_header_write(uscpi->buffer, msg_id, uscpi->bTag,
 481                                      size, transfer_attributes, 0);
 482         if (data)
 483                 memcpy(uscpi->buffer+USBTMC_BULK_HEADER_SIZE, data, size);
 484         else
 485                 size = 0;
 486         size += USBTMC_BULK_HEADER_SIZE;
 487         padded_size = (size + 3) & ~0x3;
 488         memset(uscpi->buffer+size, 0, padded_size - size);
 489
 490         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_out_ep,
 491                                    uscpi->buffer, padded_size, &transferred,
 492                                    TRANSFER_TIMEOUT);
 493         if (ret < 0) {
 494                 sr_err("USBTMC bulk out transfer error: %s.",
 495                        libusb_error_name(ret));
 496                 return SR_ERR;
 497         }
 498
 499         if (transferred < padded_size) {
 500                 sr_dbg("USBTMC bulk out partial transfer (%d/%d bytes).",
 501                        transferred, padded_size);
 502                 return SR_ERR;
 503         }
 504
 505         return transferred - USBTMC_BULK_HEADER_SIZE;
 506 }
 507
 508 static int scpi_usbtmc_bulkin_start(struct scpi_usbtmc_libusb *uscpi,
 509                                     uint8_t msg_id, void *data, int32_t size,
 510                                     uint8_t *transfer_attributes)
 511 {
 512         struct sr_usb_dev_inst *usb = uscpi->usb;
 513         int ret, transferred, message_size;
 514
 515         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 516                                    &transferred, TRANSFER_TIMEOUT);
 517         if (ret < 0) {
 518                 sr_err("USBTMC bulk in transfer error: %s.",
 519                        libusb_error_name(ret));
 520                 return SR_ERR;
 521         }
 522
 523         if (usbtmc_bulk_in_header_read(data, msg_id, uscpi->bTag, &message_size,
 524                                        transfer_attributes) != SR_OK) {
 525                 sr_err("USBTMC invalid bulk in header.");
 526                 return SR_ERR;
 527         }
 528
 529         message_size += USBTMC_BULK_HEADER_SIZE;
 530         uscpi->response_length = MIN(transferred, message_size);
 531         uscpi->response_bytes_read = USBTMC_BULK_HEADER_SIZE;
 532         uscpi->remaining_length = message_size - uscpi->response_length;
 533
 534         return transferred - USBTMC_BULK_HEADER_SIZE;
 535 }
 536
 537 static int scpi_usbtmc_bulkin_continue(struct scpi_usbtmc_libusb *uscpi,
 538                                        void *data, int size)
 539 {
 540         struct sr_usb_dev_inst *usb = uscpi->usb;
 541         int ret, transferred;
 542
 543         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 544                                    &transferred, TRANSFER_TIMEOUT);
 545         if (ret < 0) {
 546                 sr_err("USBTMC bulk in transfer error: %s.",
 547                        libusb_error_name(ret));
 548                 return SR_ERR;
 549         }
 550
 551         uscpi->response_length = MIN(transferred, uscpi->remaining_length);
 552         uscpi->response_bytes_read = 0;
 553         uscpi->remaining_length -= uscpi->response_length;
 554
 555         return transferred;
 556 }
 557
 558 static int scpi_usbtmc_libusb_send(void *priv, const char *command)
 559 {
 560         struct scpi_usbtmc_libusb *uscpi = priv;
 561
 562         if (scpi_usbtmc_bulkout(uscpi, DEV_DEP_MSG_OUT,
 563                                 command, strlen(command), EOM) <= 0)
 564                 return SR_ERR;
 565
 566         sr_spew("Successfully sent SCPI command: '%s'.", command);
 567
 568         return SR_OK;
 569 }
 570
 571 static int scpi_usbtmc_libusb_read_begin(void *priv)
 572 {
 573         struct scpi_usbtmc_libusb *uscpi = priv;
 574
 575         uscpi->remaining_length = 0;
 576
 577         if (scpi_usbtmc_bulkout(uscpi, REQUEST_DEV_DEP_MSG_IN,
 578             NULL, INT32_MAX, 0) < 0)
 579                 return SR_ERR;
 580         if (scpi_usbtmc_bulkin_start(uscpi, DEV_DEP_MSG_IN,
 581                                      uscpi->buffer, sizeof(uscpi->buffer),
 582                                      &uscpi->bulkin_attributes) < 0)
 583                 return SR_ERR;
 584
 585         return SR_OK;
 586 }
 587
 588 static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
 589 {
 590         struct scpi_usbtmc_libusb *uscpi = priv;
 591         int read_length;
 592
 593         if (uscpi->response_bytes_read >= uscpi->response_length) {
 594                 if (uscpi->remaining_length > 0) {
 595                         if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
 596                                                         sizeof(uscpi->buffer)) <= 0)
 597                                 return SR_ERR;
 598                 } else {
 599                         if (uscpi->bulkin_attributes & EOM)
 600                                 return SR_ERR;
 601                         if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
 602                                 return SR_ERR;
 603                 }
 604         }
 605
 606         read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
 607
 608         memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
 609
 610         uscpi->response_bytes_read += read_length;
 611
 612         return read_length;
 613 }
 614
 615 static int scpi_usbtmc_libusb_read_complete(void *priv)
 616 {
 617         struct scpi_usbtmc_libusb *uscpi = priv;
 618         return uscpi->response_bytes_read >= uscpi->response_length &&
 619                uscpi->remaining_length <= 0 &&
 620                uscpi->bulkin_attributes & EOM;
 621 }
 622
 623 static int scpi_usbtmc_libusb_close(struct sr_scpi_dev_inst *scpi)
 624 {
 625         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 626         struct sr_usb_dev_inst *usb = uscpi->usb;
 627         int ret;
 628
 629         if (!usb->devhdl)
 630                 return SR_ERR;
 631
 632         scpi_usbtmc_local(uscpi);
 633
 634         if ((ret = libusb_release_interface(usb->devhdl, uscpi->interface)) < 0)
 635                 sr_err("Failed to release interface: %s.",
 636                        libusb_error_name(ret));
 637
 638         if (uscpi->detached_kernel_driver) {
 639                 if ((ret = libusb_attach_kernel_driver(usb->devhdl,
 640                                                 uscpi->interface)) < 0)
 641                         sr_err("Failed to re-attach kernel driver: %s.",
 642                                libusb_error_name(ret));
 643
 644                 uscpi->detached_kernel_driver = 0;
 645         }
 646         sr_usb_close(usb);
 647
 648         return SR_OK;
 649 }
 650
 651 static void scpi_usbtmc_libusb_free(void *priv)
 652 {
 653         struct scpi_usbtmc_libusb *uscpi = priv;
 654         sr_usb_dev_inst_free(uscpi->usb);
 655 }
 656
 657 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
 658         .name          = "USBTMC",
 659         .prefix        = "usbtmc",
 660         .priv_size     = sizeof(struct scpi_usbtmc_libusb),
 661         .scan          = scpi_usbtmc_libusb_scan,
 662         .dev_inst_new  = scpi_usbtmc_libusb_dev_inst_new,
 663         .open          = scpi_usbtmc_libusb_open,
 664         .source_add    = scpi_usbtmc_libusb_source_add,
 665         .source_remove = scpi_usbtmc_libusb_source_remove,
 666         .send          = scpi_usbtmc_libusb_send,
 667         .read_begin    = scpi_usbtmc_libusb_read_begin,
 668         .read_data     = scpi_usbtmc_libusb_read_data,
 669         .read_complete = scpi_usbtmc_libusb_read_complete,
 670         .close         = scpi_usbtmc_libusb_close,
 671         .free          = scpi_usbtmc_libusb_free,
 672 };