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