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         ALL_ZERO
 110 };
 111
 112 static GSList *scpi_usbtmc_libusb_scan(struct drv_context *drvc)
 113 {
 114         struct libusb_device **devlist;
 115         struct libusb_device_descriptor des;
 116         struct libusb_config_descriptor *confdes;
 117         const struct libusb_interface_descriptor *intfdes;
 118         GSList *resources = NULL;
 119         int confidx, intfidx, ret, i;
 120         char *res;
 121
 122         ret = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
 123         if (ret < 0) {
 124                 sr_err("Failed to get device list: %s.",
 125                        libusb_error_name(ret));
 126                 return NULL;
 127         }
 128         for (i = 0; devlist[i]; i++) {
 129                 libusb_get_device_descriptor(devlist[i], &des);
 130
 131                 for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 132                         if ((ret = libusb_get_config_descriptor(devlist[i], confidx, &confdes)) < 0) {
 133                                 sr_dbg("Failed to get configuration descriptor: %s, "
 134                                        "ignoring device.", libusb_error_name(ret));
 135                                 break;
 136                         }
 137                         for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 138                                 intfdes = confdes->interface[intfidx].altsetting;
 139                                 if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 140                                     intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 141                                     intfdes->bInterfaceProtocol != USBTMC_USB488)
 142                                         continue;
 143                                 sr_dbg("Found USBTMC device (VID:PID = %04x:%04x, "
 144                                        "bus.address = %d.%d).", des.idVendor, des.idProduct,
 145                                        libusb_get_bus_number(devlist[i]),
 146                                        libusb_get_device_address(devlist[i]));
 147                                 res = g_strdup_printf("usbtmc/%d.%d",
 148                                                       libusb_get_bus_number(devlist[i]),
 149                                                       libusb_get_device_address(devlist[i]));
 150                                 resources = g_slist_append(resources, res);
 151                         }
 152                         libusb_free_config_descriptor(confdes);
 153                 }
 154         }
 155         libusb_free_device_list(devlist, 1);
 156
 157         sr_dbg("Found %d device(s).", g_slist_length(resources));
 158
 159         return resources;
 160 }
 161
 162 static int scpi_usbtmc_libusb_dev_inst_new(void *priv, struct drv_context *drvc,
 163                 const char *resource, char **params, const char *serialcomm)
 164 {
 165         struct scpi_usbtmc_libusb *uscpi = priv;
 166         GSList *devices;
 167
 168         (void)resource;
 169         (void)serialcomm;
 170
 171         if (!params || !params[1]) {
 172                 sr_err("Invalid parameters.");
 173                 return SR_ERR;
 174         }
 175
 176         uscpi->ctx = drvc->sr_ctx;
 177         devices = sr_usb_find(uscpi->ctx->libusb_ctx, params[1]);
 178         if (g_slist_length(devices) != 1) {
 179                 sr_err("Failed to find USB device '%s'.", params[1]);
 180                 g_slist_free_full(devices, (GDestroyNotify)sr_usb_dev_inst_free);
 181                 return SR_ERR;
 182         }
 183         uscpi->usb = devices->data;
 184         g_slist_free(devices);
 185
 186         return SR_OK;
 187 }
 188
 189 static int check_usbtmc_blacklist(struct usbtmc_blacklist *blacklist,
 190                 uint16_t vid, uint16_t pid)
 191 {
 192         int i;
 193
 194         for (i = 0; blacklist[i].vid; i++) {
 195                 if (blacklist[i].vid == vid && blacklist[i].pid == pid)
 196                         return TRUE;
 197         }
 198
 199         return FALSE;
 200 }
 201
 202 static int scpi_usbtmc_remote(struct scpi_usbtmc_libusb *uscpi)
 203 {
 204         struct sr_usb_dev_inst *usb = uscpi->usb;
 205         struct libusb_device *dev;
 206         struct libusb_device_descriptor des;
 207         int ret;
 208         uint8_t status;
 209
 210         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 211                 return SR_OK;
 212
 213         dev = libusb_get_device(usb->devhdl);
 214         libusb_get_device_descriptor(dev, &des);
 215         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 216                 return SR_OK;
 217
 218         sr_dbg("Locking out local control.");
 219         ret = libusb_control_transfer(usb->devhdl,
 220                         LIBUSB_ENDPOINT_IN         |
 221                         LIBUSB_REQUEST_TYPE_CLASS  |
 222                         LIBUSB_RECIPIENT_INTERFACE,
 223                         REN_CONTROL, 1,
 224                         uscpi->interface,
 225                         &status, 1,
 226                         TRANSFER_TIMEOUT);
 227         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 228                 if (ret < 0)
 229                         sr_dbg("Failed to enter REN state: %s.", libusb_error_name(ret));
 230                 else
 231                         sr_dbg("Failed to enter REN state: USBTMC status %d.", status);
 232                 return SR_ERR;
 233         }
 234
 235         ret = libusb_control_transfer(usb->devhdl,
 236                         LIBUSB_ENDPOINT_IN         |
 237                         LIBUSB_REQUEST_TYPE_CLASS  |
 238                         LIBUSB_RECIPIENT_INTERFACE,
 239                         LOCAL_LOCKOUT, 1,
 240                         uscpi->interface,
 241                         &status, 1,
 242                         TRANSFER_TIMEOUT);
 243         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 244                 if (ret < 0)
 245                         sr_dbg("Failed to enter local lockout state: %s.",
 246                                         libusb_error_name(ret));
 247                 else
 248                         sr_dbg("Failed to enter local lockout state: USBTMC "
 249                                         "status %d.", status);
 250                 return SR_ERR;
 251         }
 252
 253         return SR_OK;
 254 }
 255
 256 static void scpi_usbtmc_local(struct scpi_usbtmc_libusb *uscpi)
 257 {
 258         struct sr_usb_dev_inst *usb = uscpi->usb;
 259         struct libusb_device *dev;
 260         struct libusb_device_descriptor des;
 261         int ret;
 262         uint8_t status;
 263
 264         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 265                 return;
 266
 267         dev = libusb_get_device(usb->devhdl);
 268         libusb_get_device_descriptor(dev, &des);
 269         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 270                 return;
 271
 272         sr_dbg("Returning local control.");
 273         ret = libusb_control_transfer(usb->devhdl,
 274                         LIBUSB_ENDPOINT_IN         |
 275                         LIBUSB_REQUEST_TYPE_CLASS  |
 276                         LIBUSB_RECIPIENT_INTERFACE,
 277                         GO_TO_LOCAL, 1,
 278                         uscpi->interface,
 279                         &status, 1,
 280                         TRANSFER_TIMEOUT);
 281         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 282                 if (ret < 0)
 283                         sr_dbg("Failed to clear local lockout state: %s.",
 284                                         libusb_error_name(ret));
 285                 else
 286                         sr_dbg("Failed to clear local lockout state: USBTMC "
 287                                         "status %d.", status);
 288         }
 289
 290         return;
 291 }
 292
 293 static int scpi_usbtmc_libusb_open(struct sr_scpi_dev_inst *scpi)
 294 {
 295         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 296         struct sr_usb_dev_inst *usb = uscpi->usb;
 297         struct libusb_device *dev;
 298         struct libusb_device_descriptor des;
 299         struct libusb_config_descriptor *confdes;
 300         const struct libusb_interface_descriptor *intfdes;
 301         const struct libusb_endpoint_descriptor *ep;
 302         int confidx, intfidx, epidx, config = 0, current_config;
 303         uint8_t capabilities[24];
 304         int ret, found = 0;
 305
 306         if (usb->devhdl)
 307                 return SR_OK;
 308
 309         if (sr_usb_open(uscpi->ctx->libusb_ctx, usb) != SR_OK)
 310                 return SR_ERR;
 311
 312         dev = libusb_get_device(usb->devhdl);
 313         libusb_get_device_descriptor(dev, &des);
 314
 315         for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 316                 if ((ret = libusb_get_config_descriptor(dev, confidx, &confdes)) < 0) {
 317                         sr_dbg("Failed to get configuration descriptor: %s, "
 318                                "ignoring device.", libusb_error_name(ret));
 319                         continue;
 320                 }
 321                 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 322                         intfdes = confdes->interface[intfidx].altsetting;
 323                         if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 324                             intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 325                             intfdes->bInterfaceProtocol != USBTMC_USB488)
 326                                 continue;
 327                         uscpi->interface = intfdes->bInterfaceNumber;
 328                         config = confdes->bConfigurationValue;
 329                         sr_dbg("Interface %d configuration %d.", uscpi->interface, config);
 330                         for (epidx = 0; epidx < intfdes->bNumEndpoints; epidx++) {
 331                                 ep = &intfdes->endpoint[epidx];
 332                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 333                                     !(ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK))) {
 334                                         uscpi->bulk_out_ep = ep->bEndpointAddress;
 335                                         sr_dbg("Bulk OUT EP %d", uscpi->bulk_out_ep);
 336                                 }
 337                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 338                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 339                                         uscpi->bulk_in_ep = ep->bEndpointAddress;
 340                                         sr_dbg("Bulk IN EP %d", uscpi->bulk_in_ep & 0x7f);
 341                                 }
 342                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_INTERRUPT &&
 343                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 344                                         uscpi->interrupt_ep = ep->bEndpointAddress;
 345                                         sr_dbg("Interrupt EP %d", uscpi->interrupt_ep & 0x7f);
 346                                 }
 347                         }
 348                         found = 1;
 349                 }
 350                 libusb_free_config_descriptor(confdes);
 351                 if (found)
 352                         break;
 353         }
 354
 355         if (!found) {
 356                 sr_err("Failed to find USBTMC interface.");
 357                 return SR_ERR;
 358         }
 359
 360         if (libusb_kernel_driver_active(usb->devhdl, uscpi->interface) == 1) {
 361                 if ((ret = libusb_detach_kernel_driver(usb->devhdl,
 362                                                        uscpi->interface)) < 0) {
 363                         sr_err("Failed to detach kernel driver: %s.",
 364                                libusb_error_name(ret));
 365                         return SR_ERR;
 366                 }
 367                 uscpi->detached_kernel_driver = 1;
 368         }
 369
 370         if (libusb_get_configuration(usb->devhdl, &current_config) == 0
 371             && current_config != config) {
 372                 if ((ret = libusb_set_configuration(usb->devhdl, config)) < 0) {
 373                         sr_err("Failed to set configuration: %s.",
 374                                libusb_error_name(ret));
 375                         return SR_ERR;
 376                 }
 377         }
 378
 379         if ((ret = libusb_claim_interface(usb->devhdl, uscpi->interface)) < 0) {
 380                 sr_err("Failed to claim interface: %s.",
 381                        libusb_error_name(ret));
 382                 return SR_ERR;
 383         }
 384
 385         /* Get capabilities. */
 386         ret = libusb_control_transfer(usb->devhdl,
 387                                       LIBUSB_ENDPOINT_IN         |
 388                                       LIBUSB_REQUEST_TYPE_CLASS  |
 389                                       LIBUSB_RECIPIENT_INTERFACE,
 390                                       GET_CAPABILITIES, 0,
 391                                       uscpi->interface,
 392                                       capabilities, sizeof(capabilities),
 393                                       TRANSFER_TIMEOUT);
 394         if (ret == sizeof(capabilities)) {
 395                 uscpi->usbtmc_int_cap = capabilities[ 4];
 396                 uscpi->usbtmc_dev_cap = capabilities[ 5];
 397                 uscpi->usb488_dev_cap = capabilities[15];
 398         }
 399         sr_dbg("Device capabilities: %s%s%s%s%s, %s, %s",
 400                uscpi->usb488_dev_cap & USB488_DEV_CAP_SCPI       ? "SCPI, "    : "",
 401                uscpi->usbtmc_dev_cap & USBTMC_DEV_CAP_TERMCHAR   ? "TermChar, ": "",
 402                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? "L3, " :
 403                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? ""     : "L4, ",
 404                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? "T5, " :
 405                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? ""     : "T6, ",
 406                uscpi->usb488_dev_cap & USB488_DEV_CAP_SR1        ? "SR1"  : "SR0",
 407                uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1        ? "RL1"  : "RL0",
 408                uscpi->usb488_dev_cap & USB488_DEV_CAP_DT1        ? "DT1"  : "DT0");
 409
 410         scpi_usbtmc_remote(uscpi);
 411
 412         return SR_OK;
 413 }
 414
 415 static int scpi_usbtmc_libusb_source_add(struct sr_session *session,
 416                 void *priv, int events, int timeout, sr_receive_data_callback cb,
 417                 void *cb_data)
 418 {
 419         struct scpi_usbtmc_libusb *uscpi = priv;
 420         (void)events;
 421         return usb_source_add(session, uscpi->ctx, timeout, cb, cb_data);
 422 }
 423
 424 static int scpi_usbtmc_libusb_source_remove(struct sr_session *session,
 425                 void *priv)
 426 {
 427         struct scpi_usbtmc_libusb *uscpi = priv;
 428         return usb_source_remove(session, uscpi->ctx);
 429 }
 430
 431 static void usbtmc_bulk_out_header_write(void *header, uint8_t MsgID,
 432                                          uint8_t bTag,
 433                                          uint32_t TransferSize,
 434                                          uint8_t bmTransferAttributes,
 435                                          char TermChar)
 436 {
 437           W8(header+ 0, MsgID);
 438           W8(header+ 1, bTag);
 439           W8(header+ 2, ~bTag);
 440           W8(header+ 3, 0);
 441         WL32(header+ 4, TransferSize);
 442           W8(header+ 8, bmTransferAttributes);
 443           W8(header+ 9, TermChar);
 444         WL16(header+10, 0);
 445 }
 446
 447 static int usbtmc_bulk_in_header_read(void *header, uint8_t MsgID,
 448                                       unsigned char bTag,
 449                                       int32_t *TransferSize,
 450                                       uint8_t *bmTransferAttributes)
 451 {
 452         if (R8(header+0) != MsgID ||
 453             R8(header+1) != bTag  ||
 454             R8(header+2) != (unsigned char)~bTag)
 455                 return SR_ERR;
 456         if (TransferSize)
 457                 *TransferSize = RL32(header+4);
 458         if (bmTransferAttributes)
 459                 *bmTransferAttributes = R8(header+8);
 460         return SR_OK;
 461 }
 462
 463 static int scpi_usbtmc_bulkout(struct scpi_usbtmc_libusb *uscpi,
 464                                uint8_t msg_id, const void *data, int32_t size,
 465                                uint8_t transfer_attributes)
 466 {
 467         struct sr_usb_dev_inst *usb = uscpi->usb;
 468         int padded_size, ret, transferred;
 469
 470         if (data && size+USBTMC_BULK_HEADER_SIZE+3 > (int)sizeof(uscpi->buffer)) {
 471                 sr_err("USBTMC bulk out transfer is too big.");
 472                 return SR_ERR;
 473         }
 474
 475         uscpi->bTag++;
 476         uscpi->bTag += !uscpi->bTag;  /* bTag == 0 is invalid so avoid it. */
 477
 478         usbtmc_bulk_out_header_write(uscpi->buffer, msg_id, uscpi->bTag,
 479                                      size, transfer_attributes, 0);
 480         if (data)
 481                 memcpy(uscpi->buffer+USBTMC_BULK_HEADER_SIZE, data, size);
 482         else
 483                 size = 0;
 484         size += USBTMC_BULK_HEADER_SIZE;
 485         padded_size = (size + 3) & ~0x3;
 486         memset(uscpi->buffer+size, 0, padded_size - size);
 487
 488         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_out_ep,
 489                                    uscpi->buffer, padded_size, &transferred,
 490                                    TRANSFER_TIMEOUT);
 491         if (ret < 0) {
 492                 sr_err("USBTMC bulk out transfer error: %s.",
 493                        libusb_error_name(ret));
 494                 return SR_ERR;
 495         }
 496
 497         if (transferred < padded_size) {
 498                 sr_dbg("USBTMC bulk out partial transfer (%d/%d bytes).",
 499                        transferred, padded_size);
 500                 return SR_ERR;
 501         }
 502
 503         return transferred - USBTMC_BULK_HEADER_SIZE;
 504 }
 505
 506 static int scpi_usbtmc_bulkin_start(struct scpi_usbtmc_libusb *uscpi,
 507                                     uint8_t msg_id, void *data, int32_t size,
 508                                     uint8_t *transfer_attributes)
 509 {
 510         struct sr_usb_dev_inst *usb = uscpi->usb;
 511         int ret, transferred, message_size;
 512
 513         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 514                                    &transferred, TRANSFER_TIMEOUT);
 515         if (ret < 0) {
 516                 sr_err("USBTMC bulk in transfer error: %s.",
 517                        libusb_error_name(ret));
 518                 return SR_ERR;
 519         }
 520
 521         if (usbtmc_bulk_in_header_read(data, msg_id, uscpi->bTag, &message_size,
 522                                        transfer_attributes) != SR_OK) {
 523                 sr_err("USBTMC invalid bulk in header.");
 524                 return SR_ERR;
 525         }
 526
 527         message_size += USBTMC_BULK_HEADER_SIZE;
 528         uscpi->response_length = MIN(transferred, message_size);
 529         uscpi->response_bytes_read = USBTMC_BULK_HEADER_SIZE;
 530         uscpi->remaining_length = message_size - uscpi->response_length;
 531
 532         return transferred - USBTMC_BULK_HEADER_SIZE;
 533 }
 534
 535 static int scpi_usbtmc_bulkin_continue(struct scpi_usbtmc_libusb *uscpi,
 536                                        void *data, int size)
 537 {
 538         struct sr_usb_dev_inst *usb = uscpi->usb;
 539         int ret, transferred;
 540
 541         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 542                                    &transferred, TRANSFER_TIMEOUT);
 543         if (ret < 0) {
 544                 sr_err("USBTMC bulk in transfer error: %s.",
 545                        libusb_error_name(ret));
 546                 return SR_ERR;
 547         }
 548
 549         uscpi->response_length = MIN(transferred, uscpi->remaining_length);
 550         uscpi->response_bytes_read = 0;
 551         uscpi->remaining_length -= uscpi->response_length;
 552
 553         return transferred;
 554 }
 555
 556 static int scpi_usbtmc_libusb_send(void *priv, const char *command)
 557 {
 558         struct scpi_usbtmc_libusb *uscpi = priv;
 559
 560         if (scpi_usbtmc_bulkout(uscpi, DEV_DEP_MSG_OUT,
 561                                 command, strlen(command), EOM) <= 0)
 562                 return SR_ERR;
 563
 564         sr_spew("Successfully sent SCPI command: '%s'.", command);
 565
 566         return SR_OK;
 567 }
 568
 569 static int scpi_usbtmc_libusb_read_begin(void *priv)
 570 {
 571         struct scpi_usbtmc_libusb *uscpi = priv;
 572
 573         uscpi->remaining_length = 0;
 574
 575         if (scpi_usbtmc_bulkout(uscpi, REQUEST_DEV_DEP_MSG_IN,
 576             NULL, INT32_MAX, 0) < 0)
 577                 return SR_ERR;
 578         if (scpi_usbtmc_bulkin_start(uscpi, DEV_DEP_MSG_IN,
 579                                      uscpi->buffer, sizeof(uscpi->buffer),
 580                                      &uscpi->bulkin_attributes) < 0)
 581                 return SR_ERR;
 582
 583         return SR_OK;
 584 }
 585
 586 static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
 587 {
 588         struct scpi_usbtmc_libusb *uscpi = priv;
 589         int read_length;
 590
 591         if (uscpi->response_bytes_read >= uscpi->response_length) {
 592                 if (uscpi->remaining_length > 0) {
 593                         if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
 594                                                         sizeof(uscpi->buffer)) <= 0)
 595                                 return SR_ERR;
 596                 } else {
 597                         if (uscpi->bulkin_attributes & EOM)
 598                                 return SR_ERR;
 599                         if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
 600                                 return SR_ERR;
 601                 }
 602         }
 603
 604         read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
 605
 606         memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
 607
 608         uscpi->response_bytes_read += read_length;
 609
 610         return read_length;
 611 }
 612
 613 static int scpi_usbtmc_libusb_read_complete(void *priv)
 614 {
 615         struct scpi_usbtmc_libusb *uscpi = priv;
 616         return uscpi->response_bytes_read >= uscpi->response_length &&
 617                uscpi->remaining_length <= 0 &&
 618                uscpi->bulkin_attributes & EOM;
 619 }
 620
 621 static int scpi_usbtmc_libusb_close(struct sr_scpi_dev_inst *scpi)
 622 {
 623         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 624         struct sr_usb_dev_inst *usb = uscpi->usb;
 625         int ret;
 626
 627         if (!usb->devhdl)
 628                 return SR_ERR;
 629
 630         scpi_usbtmc_local(uscpi);
 631
 632         if ((ret = libusb_release_interface(usb->devhdl, uscpi->interface)) < 0)
 633                 sr_err("Failed to release interface: %s.",
 634                        libusb_error_name(ret));
 635
 636         if (uscpi->detached_kernel_driver) {
 637                 if ((ret = libusb_attach_kernel_driver(usb->devhdl,
 638                                                 uscpi->interface)) < 0)
 639                         sr_err("Failed to re-attach kernel driver: %s.",
 640                                libusb_error_name(ret));
 641
 642                 uscpi->detached_kernel_driver = 0;
 643         }
 644         sr_usb_close(usb);
 645
 646         return SR_OK;
 647 }
 648
 649 static void scpi_usbtmc_libusb_free(void *priv)
 650 {
 651         struct scpi_usbtmc_libusb *uscpi = priv;
 652         sr_usb_dev_inst_free(uscpi->usb);
 653 }
 654
 655 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
 656         .name          = "USBTMC",
 657         .prefix        = "usbtmc",
 658         .priv_size     = sizeof(struct scpi_usbtmc_libusb),
 659         .scan          = scpi_usbtmc_libusb_scan,
 660         .dev_inst_new  = scpi_usbtmc_libusb_dev_inst_new,
 661         .open          = scpi_usbtmc_libusb_open,
 662         .source_add    = scpi_usbtmc_libusb_source_add,
 663         .source_remove = scpi_usbtmc_libusb_source_remove,
 664         .send          = scpi_usbtmc_libusb_send,
 665         .read_begin    = scpi_usbtmc_libusb_read_begin,
 666         .read_data     = scpi_usbtmc_libusb_read_data,
 667         .read_complete = scpi_usbtmc_libusb_read_complete,
 668         .close         = scpi_usbtmc_libusb_close,
 669         .free          = scpi_usbtmc_libusb_free,
 670 };