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 <inttypes.h>
  22 #include <string.h>
  23 #include <libsigrok/libsigrok.h>
  24 #include "libsigrok-internal.h"
  25 #include "scpi.h"
  26
  27 #define LOG_PREFIX "scpi_usbtmc"
  28
  29 #define MAX_TRANSFER_LENGTH 2048
  30 #define TRANSFER_TIMEOUT 1000
  31
  32 struct scpi_usbtmc_libusb {
  33         struct sr_context *ctx;
  34         struct sr_usb_dev_inst *usb;
  35         int detached_kernel_driver;
  36         uint8_t interface;
  37         uint8_t bulk_in_ep;
  38         uint8_t bulk_out_ep;
  39         uint8_t interrupt_ep;
  40         uint8_t usbtmc_int_cap;
  41         uint8_t usbtmc_dev_cap;
  42         uint8_t usb488_dev_cap;
  43         uint8_t bTag;
  44         uint8_t bulkin_attributes;
  45         uint8_t buffer[MAX_TRANSFER_LENGTH];
  46         int response_length;
  47         int response_bytes_read;
  48         int remaining_length;
  49 };
  50
  51 /* Some USBTMC-specific enums, as defined in the USBTMC standard. */
  52 #define SUBCLASS_USBTMC 0x03
  53 #define USBTMC_USB488   0x01
  54
  55 enum {
  56         /* USBTMC control requests */
  57         INITIATE_ABORT_BULK_OUT     =   1,
  58         CHECK_ABORT_BULK_OUT_STATUS =   2,
  59         INITIATE_ABORT_BULK_IN      =   3,
  60         CHECK_ABORT_BULK_IN_STATUS  =   4,
  61         INITIATE_CLEAR              =   5,
  62         CHECK_CLEAR_STATUS          =   6,
  63         GET_CAPABILITIES            =   7,
  64         INDICATOR_PULSE             =  64,
  65
  66         /* USB488 control requests */
  67         READ_STATUS_BYTE            = 128,
  68         REN_CONTROL                 = 160,
  69         GO_TO_LOCAL                 = 161,
  70         LOCAL_LOCKOUT               = 162,
  71 };
  72
  73 /* USBTMC status codes */
  74 #define USBTMC_STATUS_SUCCESS      0x01
  75
  76 /* USBTMC capabilities */
  77 #define USBTMC_INT_CAP_LISTEN_ONLY 0x01
  78 #define USBTMC_INT_CAP_TALK_ONLY   0x02
  79 #define USBTMC_INT_CAP_INDICATOR   0x04
  80
  81 #define USBTMC_DEV_CAP_TERMCHAR    0x01
  82
  83 #define USB488_DEV_CAP_DT1         0x01
  84 #define USB488_DEV_CAP_RL1         0x02
  85 #define USB488_DEV_CAP_SR1         0x04
  86 #define USB488_DEV_CAP_SCPI        0x08
  87
  88 /* Bulk messages constants */
  89 #define USBTMC_BULK_HEADER_SIZE 12
  90
  91 /* Bulk MsgID values */
  92 #define DEV_DEP_MSG_OUT        1
  93 #define REQUEST_DEV_DEP_MSG_IN 2
  94 #define DEV_DEP_MSG_IN         2
  95
  96 /* bmTransferAttributes */
  97 #define EOM               0x01
  98 #define TERM_CHAR_ENABLED 0x02
  99
 100 struct usbtmc_blacklist {
 101         uint16_t vid;
 102         uint16_t pid;
 103 };
 104
 105 /* Devices that publish RL1 support, but don't support it. */
 106 static struct usbtmc_blacklist blacklist_remote[] = {
 107         { 0x1ab1, 0x0588 }, /* Rigol DS1000 series */
 108         { 0x1ab1, 0x04b0 }, /* Rigol DS2000 series */
 109         { 0x1ab1, 0x04b1 }, /* Rigol DS4000 series */
 110         { 0x1ab1, 0x0515 }, /* Rigol MSO5000 series */
 111         { 0x0957, 0x0588 }, /* Agilent DSO1000 series (rebadged Rigol DS1000) */
 112         { 0x0b21, 0xffff }, /* All Yokogawa devices */
 113         { 0xf4ec, 0xffff }, /* All Siglent SDS devices */
 114         ALL_ZERO
 115 };
 116
 117 /* Devices that shall get reset during open(). */
 118 static struct usbtmc_blacklist whitelist_usb_reset[] = {
 119         { 0xf4ec, 0xffff }, /* All Siglent SDS devices */
 120         ALL_ZERO
 121 };
 122
 123 static GSList *scpi_usbtmc_libusb_scan(struct drv_context *drvc)
 124 {
 125         struct libusb_device **devlist;
 126         struct libusb_device_descriptor des;
 127         struct libusb_config_descriptor *confdes;
 128         const struct libusb_interface_descriptor *intfdes;
 129         GSList *resources = NULL;
 130         int confidx, intfidx, ret, i;
 131         char *res;
 132
 133         ret = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
 134         if (ret < 0) {
 135                 sr_err("Failed to get device list: %s.",
 136                        libusb_error_name(ret));
 137                 return NULL;
 138         }
 139         for (i = 0; devlist[i]; i++) {
 140                 libusb_get_device_descriptor(devlist[i], &des);
 141
 142                 for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 143                         if ((ret = libusb_get_config_descriptor(devlist[i], confidx, &confdes)) < 0) {
 144                                 if (ret != LIBUSB_ERROR_NOT_FOUND)
 145                                         sr_dbg("Failed to get configuration descriptor: %s, "
 146                                                "ignoring device.", libusb_error_name(ret));
 147                                 break;
 148                         }
 149                         for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 150                                 intfdes = confdes->interface[intfidx].altsetting;
 151                                 if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 152                                     intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 153                                     intfdes->bInterfaceProtocol != USBTMC_USB488)
 154                                         continue;
 155                                 sr_dbg("Found USBTMC device (VID:PID = %04x:%04x, "
 156                                        "bus.address = %d.%d).", des.idVendor, des.idProduct,
 157                                        libusb_get_bus_number(devlist[i]),
 158                                        libusb_get_device_address(devlist[i]));
 159                                 res = g_strdup_printf("usbtmc/%d.%d",
 160                                                       libusb_get_bus_number(devlist[i]),
 161                                                       libusb_get_device_address(devlist[i]));
 162                                 resources = g_slist_append(resources, res);
 163                         }
 164                         libusb_free_config_descriptor(confdes);
 165                 }
 166         }
 167         libusb_free_device_list(devlist, 1);
 168
 169         /* No log message for #devices found (caller will log that). */
 170
 171         return resources;
 172 }
 173
 174 static int scpi_usbtmc_libusb_dev_inst_new(void *priv, struct drv_context *drvc,
 175                 const char *resource, char **params, const char *serialcomm)
 176 {
 177         struct scpi_usbtmc_libusb *uscpi = priv;
 178         GSList *devices;
 179
 180         (void)resource;
 181         (void)serialcomm;
 182
 183         if (!params || !params[1]) {
 184                 sr_err("Invalid parameters.");
 185                 return SR_ERR;
 186         }
 187
 188         uscpi->ctx = drvc->sr_ctx;
 189         devices = sr_usb_find(uscpi->ctx->libusb_ctx, params[1]);
 190         if (g_slist_length(devices) != 1) {
 191                 sr_err("Failed to find USB device '%s'.", params[1]);
 192                 g_slist_free_full(devices, (GDestroyNotify)sr_usb_dev_inst_free);
 193                 return SR_ERR;
 194         }
 195         uscpi->usb = devices->data;
 196         g_slist_free(devices);
 197
 198         return SR_OK;
 199 }
 200
 201 static int check_usbtmc_blacklist(struct usbtmc_blacklist *blacklist,
 202                 uint16_t vid, uint16_t pid)
 203 {
 204         int i;
 205
 206         for (i = 0; blacklist[i].vid; i++) {
 207                 if ((blacklist[i].vid == vid && blacklist[i].pid == 0xFFFF) ||
 208                         (blacklist[i].vid == vid && blacklist[i].pid == pid))
 209                         return TRUE;
 210         }
 211
 212         return FALSE;
 213 }
 214
 215 static int scpi_usbtmc_remote(struct scpi_usbtmc_libusb *uscpi)
 216 {
 217         struct sr_usb_dev_inst *usb = uscpi->usb;
 218         struct libusb_device *dev;
 219         struct libusb_device_descriptor des;
 220         int ret;
 221         uint8_t status;
 222
 223         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 224                 return SR_OK;
 225
 226         dev = libusb_get_device(usb->devhdl);
 227         libusb_get_device_descriptor(dev, &des);
 228         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 229                 return SR_OK;
 230
 231         sr_dbg("Locking out local control.");
 232         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 233                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 234                 REN_CONTROL, 1, uscpi->interface, &status, 1, TRANSFER_TIMEOUT);
 235         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 236                 if (ret < 0)
 237                         sr_dbg("Failed to enter REN state: %s.", libusb_error_name(ret));
 238                 else
 239                         sr_dbg("Failed to enter REN state: USBTMC status %d.", status);
 240                 return SR_ERR;
 241         }
 242
 243         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 244                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 245                 LOCAL_LOCKOUT, 0, uscpi->interface, &status, 1,
 246                 TRANSFER_TIMEOUT);
 247         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 248                 if (ret < 0)
 249                         sr_dbg("Failed to enter local lockout state: %s.",
 250                                         libusb_error_name(ret));
 251                 else
 252                         sr_dbg("Failed to enter local lockout state: USBTMC "
 253                                         "status %d.", status);
 254                 return SR_ERR;
 255         }
 256
 257         return SR_OK;
 258 }
 259
 260 static void scpi_usbtmc_local(struct scpi_usbtmc_libusb *uscpi)
 261 {
 262         struct sr_usb_dev_inst *usb = uscpi->usb;
 263         struct libusb_device *dev;
 264         struct libusb_device_descriptor des;
 265         int ret;
 266         uint8_t status;
 267
 268         if (!(uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1))
 269                 return;
 270
 271         dev = libusb_get_device(usb->devhdl);
 272         libusb_get_device_descriptor(dev, &des);
 273         if (check_usbtmc_blacklist(blacklist_remote, des.idVendor, des.idProduct))
 274                 return;
 275
 276         sr_dbg("Returning local control.");
 277         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 278                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 279                 GO_TO_LOCAL, 0, uscpi->interface, &status, 1, TRANSFER_TIMEOUT);
 280         if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 281                 if (ret < 0)
 282                         sr_dbg("Failed to clear local lockout state: %s.",
 283                                         libusb_error_name(ret));
 284                 else
 285                         sr_dbg("Failed to clear local lockout state: USBTMC "
 286                                         "status %d.", status);
 287         }
 288
 289         return;
 290 }
 291
 292 static int scpi_usbtmc_libusb_open(struct sr_scpi_dev_inst *scpi)
 293 {
 294         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 295         struct sr_usb_dev_inst *usb = uscpi->usb;
 296         struct libusb_device *dev;
 297         struct libusb_device_descriptor des;
 298         struct libusb_config_descriptor *confdes;
 299         const struct libusb_interface_descriptor *intfdes;
 300         const struct libusb_endpoint_descriptor *ep;
 301         int confidx, intfidx, epidx, config = 0, current_config;
 302         uint8_t capabilities[24];
 303         int ret, found = 0;
 304         int do_reset;
 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                         if (ret != LIBUSB_ERROR_NOT_FOUND)
 318                                 sr_dbg("Failed to get configuration descriptor: %s, "
 319                                        "ignoring device.", libusb_error_name(ret));
 320                         continue;
 321                 }
 322                 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 323                         intfdes = confdes->interface[intfidx].altsetting;
 324                         if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 325                             intfdes->bInterfaceSubClass != SUBCLASS_USBTMC ||
 326                             intfdes->bInterfaceProtocol != USBTMC_USB488)
 327                                 continue;
 328                         uscpi->interface = intfdes->bInterfaceNumber;
 329                         config = confdes->bConfigurationValue;
 330                         sr_dbg("Interface %d configuration %d.", uscpi->interface, config);
 331                         for (epidx = 0; epidx < intfdes->bNumEndpoints; epidx++) {
 332                                 ep = &intfdes->endpoint[epidx];
 333                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 334                                     !(ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK))) {
 335                                         uscpi->bulk_out_ep = ep->bEndpointAddress;
 336                                         sr_dbg("Bulk OUT EP %d", uscpi->bulk_out_ep);
 337                                 }
 338                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 339                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 340                                         uscpi->bulk_in_ep = ep->bEndpointAddress;
 341                                         sr_dbg("Bulk IN EP %d", uscpi->bulk_in_ep & 0x7f);
 342                                 }
 343                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_INTERRUPT &&
 344                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 345                                         uscpi->interrupt_ep = ep->bEndpointAddress;
 346                                         sr_dbg("Interrupt EP %d", uscpi->interrupt_ep & 0x7f);
 347                                 }
 348                         }
 349                         found = 1;
 350                 }
 351                 libusb_free_config_descriptor(confdes);
 352                 if (found)
 353                         break;
 354         }
 355
 356         if (!found) {
 357                 sr_err("Failed to find USBTMC interface.");
 358                 return SR_ERR;
 359         }
 360
 361         if (libusb_kernel_driver_active(usb->devhdl, uscpi->interface) == 1) {
 362                 if ((ret = libusb_detach_kernel_driver(usb->devhdl,
 363                                                        uscpi->interface)) < 0) {
 364                         sr_err("Failed to detach kernel driver: %s.",
 365                                libusb_error_name(ret));
 366                         return SR_ERR;
 367                 }
 368                 uscpi->detached_kernel_driver = 1;
 369         }
 370
 371         if (libusb_get_configuration(usb->devhdl, &current_config) == 0
 372             && current_config != config) {
 373                 if ((ret = libusb_set_configuration(usb->devhdl, config)) < 0) {
 374                         sr_err("Failed to set configuration: %s.",
 375                                libusb_error_name(ret));
 376                         return SR_ERR;
 377                 }
 378         }
 379
 380         if ((ret = libusb_claim_interface(usb->devhdl, uscpi->interface)) < 0) {
 381                 sr_err("Failed to claim interface: %s.",
 382                        libusb_error_name(ret));
 383                 return SR_ERR;
 384         }
 385
 386         /* Optionally reset the USB device. */
 387         do_reset = check_usbtmc_blacklist(whitelist_usb_reset,
 388                 des.idVendor, des.idProduct);
 389         if (do_reset)
 390                 libusb_reset_device(usb->devhdl);
 391
 392         /* Get capabilities. */
 393         ret = libusb_control_transfer(usb->devhdl, LIBUSB_ENDPOINT_IN |
 394                 LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE,
 395                 GET_CAPABILITIES, 0, uscpi->interface, capabilities,
 396                 sizeof(capabilities), TRANSFER_TIMEOUT);
 397         if (ret == sizeof(capabilities)) {
 398                 uscpi->usbtmc_int_cap = capabilities[ 4];
 399                 uscpi->usbtmc_dev_cap = capabilities[ 5];
 400                 uscpi->usb488_dev_cap = capabilities[15];
 401         }
 402         sr_dbg("Device capabilities: %s%s%s%s%s, %s, %s",
 403                uscpi->usb488_dev_cap & USB488_DEV_CAP_SCPI        ? "SCPI, "    : "",
 404                uscpi->usbtmc_dev_cap & USBTMC_DEV_CAP_TERMCHAR    ? "TermChar, ": "",
 405                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY ? "L3, " :
 406                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY   ? ""     : "L4, ",
 407                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY   ? "T5, " :
 408                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY ? ""     : "T6, ",
 409                uscpi->usb488_dev_cap & USB488_DEV_CAP_SR1         ? "SR1"  : "SR0",
 410                uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1         ? "RL1"  : "RL0",
 411                uscpi->usb488_dev_cap & USB488_DEV_CAP_DT1         ? "DT1"  : "DT0");
 412
 413         scpi_usbtmc_remote(uscpi);
 414
 415         return SR_OK;
 416 }
 417
 418 static int scpi_usbtmc_libusb_connection_id(struct sr_scpi_dev_inst *scpi,
 419                 char **connection_id)
 420 {
 421         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 422         struct sr_usb_dev_inst *usb = uscpi->usb;
 423
 424         *connection_id = g_strdup_printf("%s/%" PRIu8 ".%" PRIu8 "",
 425                 scpi->prefix, usb->bus, usb->address);
 426
 427         return SR_OK;
 428 }
 429
 430 static int scpi_usbtmc_libusb_source_add(struct sr_session *session,
 431                 void *priv, int events, int timeout, sr_receive_data_callback cb,
 432                 void *cb_data)
 433 {
 434         struct scpi_usbtmc_libusb *uscpi = priv;
 435         (void)events;
 436         return usb_source_add(session, uscpi->ctx, timeout, cb, cb_data);
 437 }
 438
 439 static int scpi_usbtmc_libusb_source_remove(struct sr_session *session,
 440                 void *priv)
 441 {
 442         struct scpi_usbtmc_libusb *uscpi = priv;
 443         return usb_source_remove(session, uscpi->ctx);
 444 }
 445
 446 static void usbtmc_bulk_out_header_write(void *header, uint8_t MsgID,
 447                                          uint8_t bTag,
 448                                          uint32_t TransferSize,
 449                                          uint8_t bmTransferAttributes,
 450                                          char TermChar)
 451 {
 452           W8(header +  0, MsgID);
 453           W8(header +  1, bTag);
 454           W8(header +  2, ~bTag);
 455           W8(header +  3, 0);
 456         WL32(header +  4, TransferSize);
 457           W8(header +  8, bmTransferAttributes);
 458           W8(header +  9, TermChar);
 459         WL16(header + 10, 0);
 460 }
 461
 462 static int usbtmc_bulk_in_header_read(void *header, uint8_t MsgID,
 463                                       unsigned char bTag,
 464                                       int32_t *TransferSize,
 465                                       uint8_t *bmTransferAttributes)
 466 {
 467         if (R8(header + 0) != MsgID ||
 468             R8(header + 1) != bTag  ||
 469             R8(header + 2) != (unsigned char)~bTag)
 470                 return SR_ERR;
 471         if (TransferSize)
 472                 *TransferSize = RL32(header + 4);
 473         if (bmTransferAttributes)
 474                 *bmTransferAttributes = R8(header + 8);
 475
 476         return SR_OK;
 477 }
 478
 479 static int scpi_usbtmc_bulkout(struct scpi_usbtmc_libusb *uscpi,
 480                                uint8_t msg_id, const void *data, int32_t size,
 481                                uint8_t transfer_attributes)
 482 {
 483         struct sr_usb_dev_inst *usb = uscpi->usb;
 484         int padded_size, ret, transferred;
 485
 486         if (data && (size + USBTMC_BULK_HEADER_SIZE + 3) > (int)sizeof(uscpi->buffer)) {
 487                 sr_err("USBTMC bulk out transfer is too big.");
 488                 return SR_ERR;
 489         }
 490
 491         uscpi->bTag++;
 492         uscpi->bTag += !uscpi->bTag; /* bTag == 0 is invalid so avoid it. */
 493
 494         usbtmc_bulk_out_header_write(uscpi->buffer, msg_id, uscpi->bTag,
 495                                      size, transfer_attributes, 0);
 496         if (data)
 497                 memcpy(uscpi->buffer + USBTMC_BULK_HEADER_SIZE, data, size);
 498         else
 499                 size = 0;
 500         size += USBTMC_BULK_HEADER_SIZE;
 501         padded_size = (size + 3) & ~0x3;
 502         memset(uscpi->buffer + size, 0, padded_size - size);
 503
 504         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_out_ep,
 505                                    uscpi->buffer, padded_size, &transferred,
 506                                    TRANSFER_TIMEOUT);
 507         if (ret < 0) {
 508                 sr_err("USBTMC bulk out transfer error: %s.",
 509                        libusb_error_name(ret));
 510                 return SR_ERR;
 511         }
 512
 513         if (transferred < padded_size) {
 514                 sr_dbg("USBTMC bulk out partial transfer (%d/%d bytes).",
 515                        transferred, padded_size);
 516                 return SR_ERR;
 517         }
 518
 519         return transferred - USBTMC_BULK_HEADER_SIZE;
 520 }
 521
 522 static int scpi_usbtmc_bulkin_start(struct scpi_usbtmc_libusb *uscpi,
 523                                     uint8_t msg_id, void *data, int32_t size,
 524                                     uint8_t *transfer_attributes)
 525 {
 526         struct sr_usb_dev_inst *usb = uscpi->usb;
 527         int ret, transferred, message_size;
 528
 529         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 530                                    &transferred, TRANSFER_TIMEOUT);
 531         if (ret < 0) {
 532                 sr_err("USBTMC bulk in transfer error: %s.",
 533                        libusb_error_name(ret));
 534                 return SR_ERR;
 535         }
 536
 537         if (transferred < USBTMC_BULK_HEADER_SIZE) {
 538                 sr_err("USBTMC bulk in returned too little data: %d/%d bytes\n", transferred, size);
 539                 return SR_ERR;
 540         }
 541
 542         if (usbtmc_bulk_in_header_read(data, msg_id, uscpi->bTag, &message_size,
 543                                        transfer_attributes) != SR_OK) {
 544                 sr_err("USBTMC invalid bulk in header.");
 545                 return SR_ERR;
 546         }
 547
 548         message_size += USBTMC_BULK_HEADER_SIZE;
 549         uscpi->response_length = MIN(transferred, message_size);
 550         uscpi->response_bytes_read = USBTMC_BULK_HEADER_SIZE;
 551         uscpi->remaining_length = message_size - uscpi->response_length;
 552
 553         return transferred - USBTMC_BULK_HEADER_SIZE;
 554 }
 555
 556 static int scpi_usbtmc_bulkin_continue(struct scpi_usbtmc_libusb *uscpi,
 557                                        void *data, int size)
 558 {
 559         struct sr_usb_dev_inst *usb = uscpi->usb;
 560         int ret, transferred;
 561
 562         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 563                                    &transferred, TRANSFER_TIMEOUT);
 564         if (ret < 0) {
 565                 sr_err("USBTMC bulk in transfer error: %s.",
 566                        libusb_error_name(ret));
 567                 return SR_ERR;
 568         }
 569
 570         uscpi->response_length = MIN(transferred, uscpi->remaining_length);
 571         uscpi->response_bytes_read = 0;
 572         uscpi->remaining_length -= uscpi->response_length;
 573
 574         return transferred;
 575 }
 576
 577 static int scpi_usbtmc_libusb_send(void *priv, const char *command)
 578 {
 579         struct scpi_usbtmc_libusb *uscpi = priv;
 580
 581         if (scpi_usbtmc_bulkout(uscpi, DEV_DEP_MSG_OUT,
 582                                 command, strlen(command), EOM) <= 0)
 583                 return SR_ERR;
 584
 585         sr_spew("Successfully sent SCPI command: '%s'.", command);
 586
 587         return SR_OK;
 588 }
 589
 590 static int scpi_usbtmc_libusb_read_begin(void *priv)
 591 {
 592         struct scpi_usbtmc_libusb *uscpi = priv;
 593
 594         uscpi->remaining_length = 0;
 595
 596         if (scpi_usbtmc_bulkout(uscpi, REQUEST_DEV_DEP_MSG_IN,
 597             NULL, INT32_MAX, 0) < 0)
 598                 return SR_ERR;
 599         if (scpi_usbtmc_bulkin_start(uscpi, DEV_DEP_MSG_IN,
 600                                      uscpi->buffer, sizeof(uscpi->buffer),
 601                                      &uscpi->bulkin_attributes) < 0)
 602                 return SR_ERR;
 603
 604         return SR_OK;
 605 }
 606
 607 static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
 608 {
 609         struct scpi_usbtmc_libusb *uscpi = priv;
 610         int read_length;
 611
 612         if (uscpi->response_bytes_read >= uscpi->response_length) {
 613                 if (uscpi->remaining_length > 0) {
 614                         if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
 615                                                         sizeof(uscpi->buffer)) <= 0)
 616                                 return SR_ERR;
 617                 } else {
 618                         if (uscpi->bulkin_attributes & EOM)
 619                                 return SR_ERR;
 620                         if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
 621                                 return SR_ERR;
 622                 }
 623         }
 624
 625         read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
 626
 627         memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
 628
 629         uscpi->response_bytes_read += read_length;
 630
 631         return read_length;
 632 }
 633
 634 static int scpi_usbtmc_libusb_read_complete(void *priv)
 635 {
 636         struct scpi_usbtmc_libusb *uscpi = priv;
 637         return uscpi->response_bytes_read >= uscpi->response_length &&
 638                uscpi->remaining_length <= 0 &&
 639                uscpi->bulkin_attributes & EOM;
 640 }
 641
 642 static int scpi_usbtmc_libusb_close(struct sr_scpi_dev_inst *scpi)
 643 {
 644         struct scpi_usbtmc_libusb *uscpi = scpi->priv;
 645         struct sr_usb_dev_inst *usb = uscpi->usb;
 646         int ret;
 647
 648         if (!usb->devhdl)
 649                 return SR_ERR;
 650
 651         scpi_usbtmc_local(uscpi);
 652
 653         if ((ret = libusb_release_interface(usb->devhdl, uscpi->interface)) < 0)
 654                 sr_err("Failed to release interface: %s.",
 655                        libusb_error_name(ret));
 656
 657         if (uscpi->detached_kernel_driver) {
 658                 if ((ret = libusb_attach_kernel_driver(usb->devhdl,
 659                                                 uscpi->interface)) < 0)
 660                         sr_err("Failed to re-attach kernel driver: %s.",
 661                                libusb_error_name(ret));
 662
 663                 uscpi->detached_kernel_driver = 0;
 664         }
 665         sr_usb_close(usb);
 666
 667         return SR_OK;
 668 }
 669
 670 static void scpi_usbtmc_libusb_free(void *priv)
 671 {
 672         struct scpi_usbtmc_libusb *uscpi = priv;
 673         sr_usb_dev_inst_free(uscpi->usb);
 674 }
 675
 676 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
 677         .name          = "USBTMC",
 678         .prefix        = "usbtmc",
 679         .transport     = SCPI_TRANSPORT_USBTMC,
 680         .priv_size     = sizeof(struct scpi_usbtmc_libusb),
 681         .scan          = scpi_usbtmc_libusb_scan,
 682         .dev_inst_new  = scpi_usbtmc_libusb_dev_inst_new,
 683         .open          = scpi_usbtmc_libusb_open,
 684         .connection_id = scpi_usbtmc_libusb_connection_id,
 685         .source_add    = scpi_usbtmc_libusb_source_add,
 686         .source_remove = scpi_usbtmc_libusb_source_remove,
 687         .send          = scpi_usbtmc_libusb_send,
 688         .read_begin    = scpi_usbtmc_libusb_read_begin,
 689         .read_data     = scpi_usbtmc_libusb_read_data,
 690         .read_complete = scpi_usbtmc_libusb_read_complete,
 691         .close         = scpi_usbtmc_libusb_close,
 692         .free          = scpi_usbtmc_libusb_free,
 693 };