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