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 /* Devices that shall get reset during open(). */
 115 static struct usbtmc_blacklist whitelist_usb_reset[] = {
 116         { 0xf4ec, 0xffff }, /* All Siglent SDS devices */
 117         ALL_ZERO
 118 };
 119
 120 static GSList *scpi_usbtmc_libusb_scan(struct drv_context *drvc)
 121 {
 122         struct libusb_device **devlist;
 123         struct libusb_device_descriptor des;
 124         struct libusb_config_descriptor *confdes;
 125         const struct libusb_interface_descriptor *intfdes;
 126         GSList *resources = NULL;
 127         int confidx, intfidx, ret, i;
 128         char *res;
 129
 130         ret = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
 131         if (ret < 0) {
 132                 sr_err("Failed to get device list: %s.",
 133                        libusb_error_name(ret));
 134                 return NULL;
 135         }
 136         for (i = 0; devlist[i]; i++) {
 137                 libusb_get_device_descriptor(devlist[i], &des);
 138
 139                 for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 140                         if ((ret = libusb_get_config_descriptor(devlist[i], confidx, &confdes)) < 0) {
 141                                 if (ret != LIBUSB_ERROR_NOT_FOUND)
 142                                         sr_dbg("Failed to get configuration descriptor: %s, "
 143                                                "ignoring device.", libusb_error_name(ret));
 144                                 break;
 145                         }
 146                         for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 147                                 intfdes = confdes->interface[intfidx].altsetting;
 148                                 if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 149                                     intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 150                                     intfdes->bInterfaceProtocol != USBTMC_USB488)
 151                                         continue;
 152                                 sr_dbg("Found USBTMC device (VID:PID = %04x:%04x, "
 153                                        "bus.address = %d.%d).", des.idVendor, des.idProduct,
 154                                        libusb_get_bus_number(devlist[i]),
 155                                        libusb_get_device_address(devlist[i]));
 156                                 res = g_strdup_printf("usbtmc/%d.%d",
 157                                                       libusb_get_bus_number(devlist[i]),
 158                                                       libusb_get_device_address(devlist[i]));
 159                                 resources = g_slist_append(resources, res);
 160                         }
 161                         libusb_free_config_descriptor(confdes);
 162                 }
 163         }
 164         libusb_free_device_list(devlist, 1);
 165
 166         /* No log message for #devices found (caller will log that). */
 167
 168         return resources;
 169 }
 170
 171 static int scpi_usbtmc_libusb_dev_inst_new(void *priv, struct drv_context *drvc,
 172                 const char *resource, char **params, const char *serialcomm)
 173 {
 174         struct scpi_usbtmc_libusb *uscpi = priv;
 175         GSList *devices;
 176
 177         (void)resource;
 178         (void)serialcomm;
 179
 180         if (!params || !params[1]) {
 181                 sr_err("Invalid parameters.");
 182                 return SR_ERR;
 183         }
 184
 185         uscpi->ctx = drvc->sr_ctx;
 186         devices = sr_usb_find(uscpi->ctx->libusb_ctx, params[1]);
 187         if (g_slist_length(devices) != 1) {
 188                 sr_err("Failed to find USB device '%s'.", params[1]);
 189                 g_slist_free_full(devices, (GDestroyNotify)sr_usb_dev_inst_free);
 190                 return SR_ERR;
 191         }
 192         uscpi->usb = devices->data;
 193         g_slist_free(devices);
 194
 195         return SR_OK;
 196 }
 197
 198 static int check_usbtmc_blacklist(struct usbtmc_blacklist *blacklist,
 199                 uint16_t vid, uint16_t pid)
 200 {
 201         int i;
 202
 203         for (i = 0; blacklist[i].vid; i++) {
 204                 if ((blacklist[i].vid == vid && blacklist[i].pid == 0xFFFF) ||
 205                         (blacklist[i].vid == vid && blacklist[i].pid == pid))
 206                         return TRUE;
 207         }
 208
 209         return FALSE;
 210 }
 211
 212 static int scpi_usbtmc_remote(struct scpi_usbtmc_libusb *uscpi)
 213 {
 214         struct sr_usb_dev_inst *usb = uscpi->usb;
 215         struct libusb_device *dev;
 216         struct libusb_device_descriptor des;
 217         int ret;
 218         uint8_t status;
 219
 220         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 221                 return SR_OK;
 222
 223         dev = libusb_get_device(usb->devhdl);
 224         libusb_get_device_descriptor(dev, &des);
 225         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 226                 return SR_OK;
 227
 228         sr_dbg("Locking out local control.");
 229         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 230                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 231                 REN_CONTROL, 1, uscpi->interface, &status, 1, TRANSFER_TIMEOUT);
 232         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 233                 if (ret < 0)
 234                         sr_dbg("Failed to enter REN state: %s.", libusb_error_name(ret));
 235                 else
 236                         sr_dbg("Failed to enter REN state: USBTMC status %d.", status);
 237                 return SR_ERR;
 238         }
 239
 240         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 241                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 242                 LOCAL_LOCKOUT, 0, uscpi->interface, &status, 1,
 243                 TRANSFER_TIMEOUT);
 244         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 245                 if (ret < 0)
 246                         sr_dbg("Failed to enter local lockout state: %s.",
 247                                         libusb_error_name(ret));
 248                 else
 249                         sr_dbg("Failed to enter local lockout state: USBTMC "
 250                                         "status %d.", status);
 251                 return SR_ERR;
 252         }
 253
 254         return SR_OK;
 255 }
 256
 257 static void scpi_usbtmc_local(struct scpi_usbtmc_libusb *uscpi)
 258 {
 259         struct sr_usb_dev_inst *usb = uscpi->usb;
 260         struct libusb_device *dev;
 261         struct libusb_device_descriptor des;
 262         int ret;
 263         uint8_t status;
 264
 265         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 266                 return;
 267
 268         dev = libusb_get_device(usb->devhdl);
 269         libusb_get_device_descriptor(dev, &des);
 270         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 271                 return;
 272
 273         sr_dbg("Returning local control.");
 274         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 275                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 276                 GO_TO_LOCAL, 0, uscpi->interface, &status, 1, TRANSFER_TIMEOUT);
 277         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 278                 if (ret < 0)
 279                         sr_dbg("Failed to clear local lockout state: %s.",
 280                                         libusb_error_name(ret));
 281                 else
 282                         sr_dbg("Failed to clear local lockout state: USBTMC "
 283                                         "status %d.", status);
 284         }
 285
 286         return;
 287 }
 288
 289 static int scpi_usbtmc_libusb_open(struct sr_scpi_dev_inst *scpi)
 290 {
 291         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 292         struct sr_usb_dev_inst *usb = uscpi->usb;
 293         struct libusb_device *dev;
 294         struct libusb_device_descriptor des;
 295         struct libusb_config_descriptor *confdes;
 296         const struct libusb_interface_descriptor *intfdes;
 297         const struct libusb_endpoint_descriptor *ep;
 298         int confidx, intfidx, epidx, config = 0, current_config;
 299         uint8_t capabilities[24];
 300         int ret, found = 0;
 301         int do_reset;
 302
 303         if (usb->devhdl)
 304                 return SR_OK;
 305
 306         if (sr_usb_open(uscpi->ctx->libusb_ctx, usb) != SR_OK)
 307                 return SR_ERR;
 308
 309         dev = libusb_get_device(usb->devhdl);
 310         libusb_get_device_descriptor(dev, &des);
 311
 312         for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 313                 if ((ret = libusb_get_config_descriptor(dev, confidx, &confdes)) < 0) {
 314                         if (ret != LIBUSB_ERROR_NOT_FOUND)
 315                                 sr_dbg("Failed to get configuration descriptor: %s, "
 316                                        "ignoring device.", libusb_error_name(ret));
 317                         continue;
 318                 }
 319                 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 320                         intfdes = confdes->interface[intfidx].altsetting;
 321                         if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 322                             intfdes->bInterfaceSubClass != SUBCLASS_USBTMC ||
 323                             intfdes->bInterfaceProtocol != USBTMC_USB488)
 324                                 continue;
 325                         uscpi->interface = intfdes->bInterfaceNumber;
 326                         config = confdes->bConfigurationValue;
 327                         sr_dbg("Interface %d configuration %d.", uscpi->interface, config);
 328                         for (epidx = 0; epidx < intfdes->bNumEndpoints; epidx++) {
 329                                 ep = &intfdes->endpoint[epidx];
 330                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 331                                     !(ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK))) {
 332                                         uscpi->bulk_out_ep = ep->bEndpointAddress;
 333                                         sr_dbg("Bulk OUT EP %d", uscpi->bulk_out_ep);
 334                                 }
 335                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 336                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 337                                         uscpi->bulk_in_ep = ep->bEndpointAddress;
 338                                         sr_dbg("Bulk IN EP %d", uscpi->bulk_in_ep & 0x7f);
 339                                 }
 340                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_INTERRUPT &&
 341                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 342                                         uscpi->interrupt_ep = ep->bEndpointAddress;
 343                                         sr_dbg("Interrupt EP %d", uscpi->interrupt_ep & 0x7f);
 344                                 }
 345                         }
 346                         found = 1;
 347                 }
 348                 libusb_free_config_descriptor(confdes);
 349                 if (found)
 350                         break;
 351         }
 352
 353         if (!found) {
 354                 sr_err("Failed to find USBTMC interface.");
 355                 return SR_ERR;
 356         }
 357
 358         if (libusb_kernel_driver_active(usb->devhdl, uscpi->interface) == 1) {
 359                 if ((ret = libusb_detach_kernel_driver(usb->devhdl,
 360                                                        uscpi->interface)) < 0) {
 361                         sr_err("Failed to detach kernel driver: %s.",
 362                                libusb_error_name(ret));
 363                         return SR_ERR;
 364                 }
 365                 uscpi->detached_kernel_driver = 1;
 366         }
 367
 368         if (libusb_get_configuration(usb->devhdl, &current_config) == 0
 369             && current_config != config) {
 370                 if ((ret = libusb_set_configuration(usb->devhdl, config)) < 0) {
 371                         sr_err("Failed to set configuration: %s.",
 372                                libusb_error_name(ret));
 373                         return SR_ERR;
 374                 }
 375         }
 376
 377         if ((ret = libusb_claim_interface(usb->devhdl, uscpi->interface)) < 0) {
 378                 sr_err("Failed to claim interface: %s.",
 379                        libusb_error_name(ret));
 380                 return SR_ERR;
 381         }
 382
 383         /* Optionally reset the USB device. */
 384         do_reset = check_usbtmc_blacklist(whitelist_usb_reset,
 385                 des.idVendor, des.idProduct);
 386         if (do_reset)
 387                 libusb_reset_device(usb->devhdl);
 388
 389         /* Get capabilities. */
 390         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 391                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 392                 GET_CAPABILITIES, 0, uscpi->interface, capabilities,
 393                 sizeof(capabilities), 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
 461         return SR_OK;
 462 }
 463
 464 static int scpi_usbtmc_bulkout(struct scpi_usbtmc_libusb *uscpi,
 465                                uint8_t msg_id, const void *data, int32_t size,
 466                                uint8_t transfer_attributes)
 467 {
 468         struct sr_usb_dev_inst *usb = uscpi->usb;
 469         int padded_size, ret, transferred;
 470
 471         if (data && (size + USBTMC_BULK_HEADER_SIZE + 3) > (int)sizeof(uscpi->buffer)) {
 472                 sr_err("USBTMC bulk out transfer is too big.");
 473                 return SR_ERR;
 474         }
 475
 476         uscpi->bTag++;
 477         uscpi->bTag += !uscpi->bTag; /* bTag == 0 is invalid so avoid it. */
 478
 479         usbtmc_bulk_out_header_write(uscpi->buffer, msg_id, uscpi->bTag,
 480                                      size, transfer_attributes, 0);
 481         if (data)
 482                 memcpy(uscpi->buffer + USBTMC_BULK_HEADER_SIZE, data, size);
 483         else
 484                 size = 0;
 485         size += USBTMC_BULK_HEADER_SIZE;
 486         padded_size = (size + 3) & ~0x3;
 487         memset(uscpi->buffer + size, 0, padded_size - size);
 488
 489         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_out_ep,
 490                                    uscpi->buffer, padded_size, &transferred,
 491                                    TRANSFER_TIMEOUT);
 492         if (ret < 0) {
 493                 sr_err("USBTMC bulk out transfer error: %s.",
 494                        libusb_error_name(ret));
 495                 return SR_ERR;
 496         }
 497
 498         if (transferred < padded_size) {
 499                 sr_dbg("USBTMC bulk out partial transfer (%d/%d bytes).",
 500                        transferred, padded_size);
 501                 return SR_ERR;
 502         }
 503
 504         return transferred - USBTMC_BULK_HEADER_SIZE;
 505 }
 506
 507 static int scpi_usbtmc_bulkin_start(struct scpi_usbtmc_libusb *uscpi,
 508                                     uint8_t msg_id, void *data, int32_t size,
 509                                     uint8_t *transfer_attributes)
 510 {
 511         struct sr_usb_dev_inst *usb = uscpi->usb;
 512         int ret, transferred, message_size;
 513
 514         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 515                                    &transferred, TRANSFER_TIMEOUT);
 516         if (ret < 0) {
 517                 sr_err("USBTMC bulk in transfer error: %s.",
 518                        libusb_error_name(ret));
 519                 return SR_ERR;
 520         }
 521
 522         if (usbtmc_bulk_in_header_read(data, msg_id, uscpi->bTag, &message_size,
 523                                        transfer_attributes) != SR_OK) {
 524                 sr_err("USBTMC invalid bulk in header.");
 525                 return SR_ERR;
 526         }
 527
 528         message_size += USBTMC_BULK_HEADER_SIZE;
 529         uscpi->response_length = MIN(transferred, message_size);
 530         uscpi->response_bytes_read = USBTMC_BULK_HEADER_SIZE;
 531         uscpi->remaining_length = message_size - uscpi->response_length;
 532
 533         return transferred - USBTMC_BULK_HEADER_SIZE;
 534 }
 535
 536 static int scpi_usbtmc_bulkin_continue(struct scpi_usbtmc_libusb *uscpi,
 537                                        void *data, int size)
 538 {
 539         struct sr_usb_dev_inst *usb = uscpi->usb;
 540         int ret, transferred;
 541
 542         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 543                                    &transferred, TRANSFER_TIMEOUT);
 544         if (ret < 0) {
 545                 sr_err("USBTMC bulk in transfer error: %s.",
 546                        libusb_error_name(ret));
 547                 return SR_ERR;
 548         }
 549
 550         uscpi->response_length = MIN(transferred, uscpi->remaining_length);
 551         uscpi->response_bytes_read = 0;
 552         uscpi->remaining_length -= uscpi->response_length;
 553
 554         return transferred;
 555 }
 556
 557 static int scpi_usbtmc_libusb_send(void *priv, const char *command)
 558 {
 559         struct scpi_usbtmc_libusb *uscpi = priv;
 560
 561         if (scpi_usbtmc_bulkout(uscpi, DEV_DEP_MSG_OUT,
 562                                 command, strlen(command), EOM) <= 0)
 563                 return SR_ERR;
 564
 565         sr_spew("Successfully sent SCPI command: '%s'.", command);
 566
 567         return SR_OK;
 568 }
 569
 570 static int scpi_usbtmc_libusb_read_begin(void *priv)
 571 {
 572         struct scpi_usbtmc_libusb *uscpi = priv;
 573
 574         uscpi->remaining_length = 0;
 575
 576         if (scpi_usbtmc_bulkout(uscpi, REQUEST_DEV_DEP_MSG_IN,
 577             NULL, INT32_MAX, 0) < 0)
 578                 return SR_ERR;
 579         if (scpi_usbtmc_bulkin_start(uscpi, DEV_DEP_MSG_IN,
 580                                      uscpi->buffer, sizeof(uscpi->buffer),
 581                                      &uscpi->bulkin_attributes) < 0)
 582                 return SR_ERR;
 583
 584         return SR_OK;
 585 }
 586
 587 static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
 588 {
 589         struct scpi_usbtmc_libusb *uscpi = priv;
 590         int read_length;
 591
 592         if (uscpi->response_bytes_read >= uscpi->response_length) {
 593                 if (uscpi->remaining_length > 0) {
 594                         if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
 595                                                         sizeof(uscpi->buffer)) <= 0)
 596                                 return SR_ERR;
 597                 } else {
 598                         if (uscpi->bulkin_attributes & EOM)
 599                                 return SR_ERR;
 600                         if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
 601                                 return SR_ERR;
 602                 }
 603         }
 604
 605         read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
 606
 607         memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
 608
 609         uscpi->response_bytes_read += read_length;
 610
 611         return read_length;
 612 }
 613
 614 static int scpi_usbtmc_libusb_read_complete(void *priv)
 615 {
 616         struct scpi_usbtmc_libusb *uscpi = priv;
 617         return uscpi->response_bytes_read >= uscpi->response_length &&
 618                uscpi->remaining_length <= 0 &&
 619                uscpi->bulkin_attributes & EOM;
 620 }
 621
 622 static int scpi_usbtmc_libusb_close(struct sr_scpi_dev_inst *scpi)
 623 {
 624         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 625         struct sr_usb_dev_inst *usb = uscpi->usb;
 626         int ret;
 627
 628         if (!usb->devhdl)
 629                 return SR_ERR;
 630
 631         scpi_usbtmc_local(uscpi);
 632
 633         if ((ret = libusb_release_interface(usb->devhdl, uscpi->interface)) < 0)
 634                 sr_err("Failed to release interface: %s.",
 635                        libusb_error_name(ret));
 636
 637         if (uscpi->detached_kernel_driver) {
 638                 if ((ret = libusb_attach_kernel_driver(usb->devhdl,
 639                                                 uscpi->interface)) < 0)
 640                         sr_err("Failed to re-attach kernel driver: %s.",
 641                                libusb_error_name(ret));
 642
 643                 uscpi->detached_kernel_driver = 0;
 644         }
 645         sr_usb_close(usb);
 646
 647         return SR_OK;
 648 }
 649
 650 static void scpi_usbtmc_libusb_free(void *priv)
 651 {
 652         struct scpi_usbtmc_libusb *uscpi = priv;
 653         sr_usb_dev_inst_free(uscpi->usb);
 654 }
 655
 656 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
 657         .name          = "USBTMC",
 658         .prefix        = "usbtmc",
 659         .priv_size     = sizeof(struct scpi_usbtmc_libusb),
 660         .scan          = scpi_usbtmc_libusb_scan,
 661         .dev_inst_new  = scpi_usbtmc_libusb_dev_inst_new,
 662         .open          = scpi_usbtmc_libusb_open,
 663         .source_add    = scpi_usbtmc_libusb_source_add,
 664         .source_remove = scpi_usbtmc_libusb_source_remove,
 665         .send          = scpi_usbtmc_libusb_send,
 666         .read_begin    = scpi_usbtmc_libusb_read_begin,
 667         .read_data     = scpi_usbtmc_libusb_read_data,
 668         .read_complete = scpi_usbtmc_libusb_read_complete,
 669         .close         = scpi_usbtmc_libusb_close,
 670         .free          = scpi_usbtmc_libusb_free,
 671 };