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         int rigol_ds1000;
  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 static GSList *scpi_usbtmc_libusb_scan(struct drv_context *drvc)
 101 {
 102         struct libusb_device **devlist;
 103         struct libusb_device_descriptor des;
 104         struct libusb_config_descriptor *confdes;
 105         const struct libusb_interface_descriptor *intfdes;
 106         GSList *resources = NULL;
 107         int confidx, intfidx, ret, i;
 108         char *res;
 109
 110         ret = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
 111         if (ret < 0) {
 112                 sr_err("Failed to get device list: %s.",
 113                        libusb_error_name(ret));
 114                 return NULL;
 115         }
 116         for (i = 0; devlist[i]; i++) {
 117                 if ((ret = libusb_get_device_descriptor(devlist[i], &des)) < 0) {
 118                         sr_err("Failed to get device descriptor: %s.",
 119                                libusb_error_name(ret));
 120                         continue;
 121                 }
 122
 123                 for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 124                         if ((ret = libusb_get_config_descriptor(devlist[i], confidx, &confdes)) < 0) {
 125                                 sr_dbg("Failed to get configuration descriptor: %s, "
 126                                        "ignoring device.", libusb_error_name(ret));
 127                                 break;
 128                         }
 129                         for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 130                                 intfdes = confdes->interface[intfidx].altsetting;
 131                                 if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 132                                     intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 133                                     intfdes->bInterfaceProtocol != USBTMC_USB488)
 134                                         continue;
 135                                 sr_dbg("Found USBTMC device (VID:PID = %04x:%04x, "
 136                                        "bus.address = %d.%d).", des.idVendor, des.idProduct,
 137                                        libusb_get_bus_number(devlist[i]),
 138                                        libusb_get_device_address(devlist[i]));
 139                                 res = g_strdup_printf("usbtmc/%d.%d",
 140                                                       libusb_get_bus_number(devlist[i]),
 141                                                       libusb_get_device_address(devlist[i]));
 142                                 resources = g_slist_append(resources, res);
 143                         }
 144                         libusb_free_config_descriptor(confdes);
 145                 }
 146         }
 147         libusb_free_device_list(devlist, 1);
 148
 149         sr_dbg("Found %d device(s).", g_slist_length(resources));
 150
 151         return resources;
 152 }
 153
 154 static int scpi_usbtmc_libusb_dev_inst_new(void *priv, struct drv_context *drvc,
 155                 const char *resource, char **params, const char *serialcomm)
 156 {
 157         struct scpi_usbtmc_libusb *uscpi = priv;
 158         GSList *devices;
 159
 160         (void)resource;
 161         (void)serialcomm;
 162
 163         if (!params || !params[1]) {
 164                 sr_err("Invalid parameters.");
 165                 return SR_ERR;
 166         }
 167
 168         uscpi->ctx = drvc->sr_ctx;
 169         devices = sr_usb_find(uscpi->ctx->libusb_ctx, params[1]);
 170         if (g_slist_length(devices) != 1) {
 171                 sr_err("Failed to find USB device '%s'.", params[1]);
 172                 g_slist_free_full(devices, (GDestroyNotify)sr_usb_dev_inst_free);
 173                 return SR_ERR;
 174         }
 175         uscpi->usb = devices->data;
 176         g_slist_free(devices);
 177
 178         return SR_OK;
 179 }
 180
 181 static int scpi_usbtmc_libusb_open(void *priv)
 182 {
 183         struct scpi_usbtmc_libusb *uscpi = priv;
 184         struct sr_usb_dev_inst *usb = uscpi->usb;
 185         struct libusb_device *dev;
 186         struct libusb_device_descriptor des;
 187         struct libusb_config_descriptor *confdes;
 188         const struct libusb_interface_descriptor *intfdes;
 189         const struct libusb_endpoint_descriptor *ep;
 190         int confidx, intfidx, epidx, config = 0;
 191         uint8_t capabilities[24], status;
 192         int ret, found = 0;
 193
 194         if (usb->devhdl)
 195                 return SR_OK;
 196
 197         if (sr_usb_open(uscpi->ctx->libusb_ctx, usb) != SR_OK)
 198                 return SR_ERR;
 199
 200         dev = libusb_get_device(usb->devhdl);
 201         if ((ret = libusb_get_device_descriptor(dev, &des)) < 0) {
 202                 sr_err("Failed to get device descriptor: %s.",
 203                        libusb_error_name(ret));
 204                 return SR_ERR;
 205         }
 206
 207         for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
 208                 if ((ret = libusb_get_config_descriptor(dev, confidx, &confdes)) < 0) {
 209                         sr_dbg("Failed to get configuration descriptor: %s, "
 210                                "ignoring device.", libusb_error_name(ret));
 211                         continue;
 212                 }
 213                 for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
 214                         intfdes = confdes->interface[intfidx].altsetting;
 215                         if (intfdes->bInterfaceClass    != LIBUSB_CLASS_APPLICATION ||
 216                             intfdes->bInterfaceSubClass != SUBCLASS_USBTMC          ||
 217                             intfdes->bInterfaceProtocol != USBTMC_USB488)
 218                                 continue;
 219                         uscpi->interface = intfdes->bInterfaceNumber;
 220                         config = confdes->bConfigurationValue;
 221                         sr_dbg("Interface %d configuration %d.", uscpi->interface, config);
 222                         for (epidx = 0; epidx < intfdes->bNumEndpoints; epidx++) {
 223                                 ep = &intfdes->endpoint[epidx];
 224                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 225                                     !(ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK))) {
 226                                         uscpi->bulk_out_ep = ep->bEndpointAddress;
 227                                         sr_dbg("Bulk OUT EP %d", uscpi->bulk_out_ep);
 228                                 }
 229                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_BULK &&
 230                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 231                                         uscpi->bulk_in_ep = ep->bEndpointAddress;
 232                                         sr_dbg("Bulk IN EP %d", uscpi->bulk_in_ep & 0x7f);
 233                                 }
 234                                 if (ep->bmAttributes == LIBUSB_TRANSFER_TYPE_INTERRUPT &&
 235                                     ep->bEndpointAddress & (LIBUSB_ENDPOINT_DIR_MASK)) {
 236                                         uscpi->interrupt_ep = ep->bEndpointAddress;
 237                                         sr_dbg("Interrupt EP %d", uscpi->interrupt_ep & 0x7f);
 238                                 }
 239                         }
 240                         found = 1;
 241                         uscpi->rigol_ds1000 = des.idVendor  == 0x1ab1 &&
 242                                               des.idProduct == 0x0588;
 243                 }
 244                 libusb_free_config_descriptor(confdes);
 245                 if (found)
 246                         break;
 247         }
 248
 249         if (!found) {
 250                 sr_err("Failed to find USBTMC interface.");
 251                 return SR_ERR;
 252         }
 253
 254         if (libusb_kernel_driver_active(usb->devhdl, uscpi->interface) == 1) {
 255                 if ((ret = libusb_detach_kernel_driver(usb->devhdl,
 256                                                        uscpi->interface)) < 0) {
 257                         sr_err("Failed to detach kernel driver: %s.",
 258                                libusb_error_name(ret));
 259                         return SR_ERR;
 260                 }
 261                 uscpi->detached_kernel_driver = 1;
 262         }
 263
 264         if ((ret = libusb_set_configuration(usb->devhdl, config)) < 0) {
 265                 sr_err("Failed to set configuration: %s.",
 266                        libusb_error_name(ret));
 267                 return SR_ERR;
 268         }
 269
 270         if ((ret = libusb_claim_interface(usb->devhdl, uscpi->interface)) < 0) {
 271                 sr_err("Failed to claim interface: %s.",
 272                        libusb_error_name(ret));
 273                 return SR_ERR;
 274         }
 275
 276         if (!uscpi->rigol_ds1000) {
 277         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_in_ep)) < 0) {
 278                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 279                        uscpi->bulk_in_ep, libusb_error_name(ret));
 280                 return SR_ERR;
 281         }
 282         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_out_ep)) < 0) {
 283                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 284                        uscpi->bulk_out_ep, libusb_error_name(ret));
 285                 return SR_ERR;
 286         }
 287         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->interrupt_ep)) < 0) {
 288                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 289                        uscpi->interrupt_ep, libusb_error_name(ret));
 290                 return SR_ERR;
 291         }
 292         }
 293
 294         /* Get capabilities. */
 295         ret = libusb_control_transfer(usb->devhdl,
 296                                       LIBUSB_ENDPOINT_IN         |
 297                                       LIBUSB_REQUEST_TYPE_CLASS  |
 298                                       LIBUSB_RECIPIENT_INTERFACE,
 299                                       GET_CAPABILITIES, 0,
 300                                       uscpi->interface,
 301                                       capabilities, sizeof(capabilities),
 302                                       TRANSFER_TIMEOUT);
 303         if (ret == sizeof(capabilities)) {
 304                 uscpi->usbtmc_int_cap = capabilities[ 4];
 305                 uscpi->usbtmc_dev_cap = capabilities[ 5];
 306                 uscpi->usb488_dev_cap = capabilities[15];
 307         }
 308         sr_dbg("Device capabilities: %s%s%s%s%s, %s, %s",
 309                uscpi->usb488_dev_cap & USB488_DEV_CAP_SCPI       ? "SCPI, "    : "",
 310                uscpi->usbtmc_dev_cap & USBTMC_DEV_CAP_TERMCHAR   ? "TermChar, ": "",
 311                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? "L3, " :
 312                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? ""     : "L4, ",
 313                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_TALK_ONLY  ? "T5, " :
 314                uscpi->usbtmc_int_cap & USBTMC_INT_CAP_LISTEN_ONLY? ""     : "T6, ",
 315                uscpi->usb488_dev_cap & USB488_DEV_CAP_SR1        ? "SR1"  : "SR0",
 316                uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1        ? "RL1"  : "RL0",
 317                uscpi->usb488_dev_cap & USB488_DEV_CAP_DT1        ? "DT1"  : "DT0");
 318
 319         if (uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1) {
 320                 sr_dbg("Locking out local control.");
 321                 ret = libusb_control_transfer(usb->devhdl,
 322                                 LIBUSB_ENDPOINT_IN         |
 323                                 LIBUSB_REQUEST_TYPE_CLASS  |
 324                                 LIBUSB_RECIPIENT_INTERFACE,
 325                                 REN_CONTROL, 1,
 326                                 uscpi->interface,
 327                                 &status, 1,
 328                                 TRANSFER_TIMEOUT);
 329                 if (ret < 0 || status != USBTMC_STATUS_SUCCESS) {
 330                         sr_dbg("Failed to enter REN state.");
 331                         return SR_OK;
 332                 }
 333                 ret = libusb_control_transfer(usb->devhdl,
 334                                 LIBUSB_ENDPOINT_IN         |
 335                                 LIBUSB_REQUEST_TYPE_CLASS  |
 336                                 LIBUSB_RECIPIENT_INTERFACE,
 337                                 LOCAL_LOCKOUT, 1,
 338                                 uscpi->interface,
 339                                 &status, 1,
 340                                 TRANSFER_TIMEOUT);
 341                 if (ret < 0 || status != USBTMC_STATUS_SUCCESS)
 342                         sr_dbg("Failed to enter local lockout state.");
 343         }
 344
 345         return SR_OK;
 346 }
 347
 348 static int scpi_usbtmc_libusb_source_add(struct sr_session *session,
 349                 void *priv, int events, int timeout, sr_receive_data_callback cb,
 350                 void *cb_data)
 351 {
 352         struct scpi_usbtmc_libusb *uscpi = priv;
 353         (void)events;
 354         return usb_source_add(session, uscpi->ctx, timeout, cb, cb_data);
 355 }
 356
 357 static int scpi_usbtmc_libusb_source_remove(struct sr_session *session,
 358                 void *priv)
 359 {
 360         struct scpi_usbtmc_libusb *uscpi = priv;
 361         return usb_source_remove(session, uscpi->ctx);
 362 }
 363
 364 static void usbtmc_bulk_out_header_write(void *header, uint8_t MsgID,
 365                                          uint8_t bTag,
 366                                          uint32_t TransferSize,
 367                                          uint8_t bmTransferAttributes,
 368                                          char TermChar)
 369 {
 370           W8(header+ 0, MsgID);
 371           W8(header+ 1, bTag);
 372           W8(header+ 2, ~bTag);
 373           W8(header+ 3, 0);
 374         WL32(header+ 4, TransferSize);
 375           W8(header+ 8, bmTransferAttributes);
 376           W8(header+ 9, TermChar);
 377         WL16(header+10, 0);
 378 }
 379
 380 static int usbtmc_bulk_in_header_read(void *header, uint8_t MsgID,
 381                                       unsigned char bTag,
 382                                       int32_t *TransferSize,
 383                                       uint8_t *bmTransferAttributes)
 384 {
 385         if (R8(header+0) != MsgID ||
 386             R8(header+1) != bTag  ||
 387             R8(header+2) != (unsigned char)~bTag)
 388                 return SR_ERR;
 389         if (TransferSize)
 390                 *TransferSize = RL32(header+4);
 391         if (bmTransferAttributes)
 392                 *bmTransferAttributes = R8(header+8);
 393         return SR_OK;
 394 }
 395
 396 static int scpi_usbtmc_bulkout(struct scpi_usbtmc_libusb *uscpi,
 397                                uint8_t msg_id, const void *data, int32_t size,
 398                                uint8_t transfer_attributes)
 399 {
 400         struct sr_usb_dev_inst *usb = uscpi->usb;
 401         int padded_size, ret, transferred;
 402
 403         if (data && size+USBTMC_BULK_HEADER_SIZE+3 > (int)sizeof(uscpi->buffer)) {
 404                 sr_err("USBTMC bulk out transfer is too big.");
 405                 return SR_ERR;
 406         }
 407
 408         uscpi->bTag++;
 409         uscpi->bTag += !uscpi->bTag;  /* bTag == 0 is invalid so avoid it. */
 410
 411         usbtmc_bulk_out_header_write(uscpi->buffer, msg_id, uscpi->bTag,
 412                                      size, transfer_attributes, 0);
 413         if (data)
 414                 memcpy(uscpi->buffer+USBTMC_BULK_HEADER_SIZE, data, size);
 415         else
 416                 size = 0;
 417         size += USBTMC_BULK_HEADER_SIZE;
 418         padded_size = (size + 3) & ~0x3;
 419         memset(uscpi->buffer+size, 0, padded_size - size);
 420
 421         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_out_ep,
 422                                    uscpi->buffer, padded_size, &transferred,
 423                                    TRANSFER_TIMEOUT);
 424         if (ret < 0) {
 425                 sr_err("USBTMC bulk out transfer error: %s.",
 426                        libusb_error_name(ret));
 427                 return SR_ERR;
 428         }
 429
 430         if (transferred < padded_size) {
 431                 sr_dbg("USBTMC bulk out partial transfer (%d/%d bytes).",
 432                        transferred, padded_size);
 433                 return SR_ERR;
 434         }
 435
 436         return transferred - USBTMC_BULK_HEADER_SIZE;
 437 }
 438
 439 static int scpi_usbtmc_bulkin_start(struct scpi_usbtmc_libusb *uscpi,
 440                                     uint8_t msg_id, void *data, int32_t size,
 441                                     uint8_t *transfer_attributes)
 442 {
 443         struct sr_usb_dev_inst *usb = uscpi->usb;
 444         int ret, transferred, message_size;
 445
 446         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 447                                    &transferred, TRANSFER_TIMEOUT);
 448         if (ret < 0) {
 449                 sr_err("USBTMC bulk in transfer error: %s.",
 450                        libusb_error_name(ret));
 451                 return SR_ERR;
 452         }
 453
 454         if (usbtmc_bulk_in_header_read(data, msg_id, uscpi->bTag, &message_size,
 455                                        transfer_attributes) != SR_OK) {
 456                 sr_err("USBTMC invalid bulk in header.");
 457                 return SR_ERR;
 458         }
 459
 460         message_size += USBTMC_BULK_HEADER_SIZE;
 461         uscpi->response_length = MIN(transferred, message_size);
 462         uscpi->response_bytes_read = USBTMC_BULK_HEADER_SIZE;
 463         uscpi->remaining_length = message_size - uscpi->response_length;
 464
 465         return transferred - USBTMC_BULK_HEADER_SIZE;
 466 }
 467
 468 static int scpi_usbtmc_bulkin_continue(struct scpi_usbtmc_libusb *uscpi,
 469                                        void *data, int size)
 470 {
 471         struct sr_usb_dev_inst *usb = uscpi->usb;
 472         int ret, transferred;
 473
 474         ret = libusb_bulk_transfer(usb->devhdl, uscpi->bulk_in_ep, data, size,
 475                                    &transferred, TRANSFER_TIMEOUT);
 476         if (ret < 0) {
 477                 sr_err("USBTMC bulk in transfer error: %s.",
 478                        libusb_error_name(ret));
 479                 return SR_ERR;
 480         }
 481
 482         uscpi->response_length = MIN(transferred, uscpi->remaining_length);
 483         uscpi->response_bytes_read = 0;
 484         uscpi->remaining_length -= uscpi->response_length;
 485
 486         return transferred;
 487 }
 488
 489 static int scpi_usbtmc_libusb_send(void *priv, const char *command)
 490 {
 491         struct scpi_usbtmc_libusb *uscpi = priv;
 492
 493         if (scpi_usbtmc_bulkout(uscpi, DEV_DEP_MSG_OUT,
 494                                 command, strlen(command), EOM) <= 0)
 495                 return SR_ERR;
 496
 497         sr_spew("Successfully sent SCPI command: '%s'.", command);
 498
 499         return SR_OK;
 500 }
 501
 502 static int scpi_usbtmc_libusb_read_begin(void *priv)
 503 {
 504         struct scpi_usbtmc_libusb *uscpi = priv;
 505
 506         uscpi->remaining_length = 0;
 507
 508         if (scpi_usbtmc_bulkout(uscpi, REQUEST_DEV_DEP_MSG_IN,
 509             NULL, INT32_MAX, 0) < 0)
 510                 return SR_ERR;
 511         if (scpi_usbtmc_bulkin_start(uscpi, DEV_DEP_MSG_IN,
 512                                      uscpi->buffer, sizeof(uscpi->buffer),
 513                                      &uscpi->bulkin_attributes) < 0)
 514                 return SR_ERR;
 515
 516         return SR_OK;
 517 }
 518
 519 static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
 520 {
 521         struct scpi_usbtmc_libusb *uscpi = priv;
 522         int read_length;
 523
 524         if (uscpi->response_bytes_read >= uscpi->response_length) {
 525                 if (uscpi->remaining_length > 0) {
 526                         if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
 527                                                         sizeof(uscpi->buffer)) <= 0)
 528                                 return SR_ERR;
 529                 } else {
 530                         if (uscpi->bulkin_attributes & EOM)
 531                                 return SR_ERR;
 532                         if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
 533                                 return SR_ERR;
 534                 }
 535         }
 536
 537         read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
 538
 539         memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
 540
 541         uscpi->response_bytes_read += read_length;
 542
 543         return read_length;
 544 }
 545
 546 static int scpi_usbtmc_libusb_read_complete(void *priv)
 547 {
 548         struct scpi_usbtmc_libusb *uscpi = priv;
 549         return uscpi->response_bytes_read >= uscpi->response_length &&
 550                uscpi->remaining_length <= 0 &&
 551                uscpi->bulkin_attributes & EOM;
 552 }
 553
 554 static int scpi_usbtmc_libusb_close(void *priv)
 555 {
 556         int ret;
 557         struct scpi_usbtmc_libusb *uscpi = priv;
 558         struct sr_usb_dev_inst *usb = uscpi->usb;
 559         uint8_t status;
 560
 561         if (!usb->devhdl)
 562                 return SR_ERR;
 563
 564         if (!uscpi->rigol_ds1000) {
 565         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_in_ep)) < 0)
 566                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 567                        uscpi->bulk_in_ep, libusb_error_name(ret));
 568         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->bulk_out_ep)) < 0)
 569                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 570                        uscpi->bulk_out_ep, libusb_error_name(ret));
 571         if ((ret = libusb_clear_halt(usb->devhdl, uscpi->interrupt_ep)) < 0)
 572                 sr_err("Failed to clear halt/stall condition for EP %d: %s.",
 573                        uscpi->interrupt_ep, libusb_error_name(ret));
 574         }
 575
 576         if (uscpi->usb488_dev_cap & USB488_DEV_CAP_RL1) {
 577                 sr_dbg("Returning local control.");
 578                 ret = libusb_control_transfer(usb->devhdl,
 579                                 LIBUSB_ENDPOINT_IN         |
 580                                 LIBUSB_REQUEST_TYPE_CLASS  |
 581                                 LIBUSB_RECIPIENT_INTERFACE,
 582                                 GO_TO_LOCAL, 1,
 583                                 uscpi->interface,
 584                                 &status, 1,
 585                                 TRANSFER_TIMEOUT);
 586                 if (ret < 0 || status != USBTMC_STATUS_SUCCESS)
 587                         sr_dbg("Failed to clear local lockout state.");
 588         }
 589
 590         if ((ret = libusb_release_interface(usb->devhdl, uscpi->interface)) < 0)
 591                 sr_err("Failed to release interface: %s.",
 592                        libusb_error_name(ret));
 593
 594         if (uscpi->detached_kernel_driver) {
 595                 if ((ret = libusb_attach_kernel_driver(usb->devhdl,
 596                                                 uscpi->interface)) < 0)
 597                         sr_err("Failed to re-attach kernel driver: %s.",
 598                                libusb_error_name(ret));
 599
 600                 uscpi->detached_kernel_driver = 0;
 601         }
 602         sr_usb_close(usb);
 603
 604         return SR_OK;
 605 }
 606
 607 static void scpi_usbtmc_libusb_free(void *priv)
 608 {
 609         struct scpi_usbtmc_libusb *uscpi = priv;
 610         sr_usb_dev_inst_free(uscpi->usb);
 611 }
 612
 613 SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_libusb_dev = {
 614         .name          = "USBTMC",
 615         .prefix        = "usbtmc",
 616         .priv_size     = sizeof(struct scpi_usbtmc_libusb),
 617         .scan          = scpi_usbtmc_libusb_scan,
 618         .dev_inst_new  = scpi_usbtmc_libusb_dev_inst_new,
 619         .open          = scpi_usbtmc_libusb_open,
 620         .source_add    = scpi_usbtmc_libusb_source_add,
 621         .source_remove = scpi_usbtmc_libusb_source_remove,
 622         .send          = scpi_usbtmc_libusb_send,
 623         .read_begin    = scpi_usbtmc_libusb_read_begin,
 624         .read_data     = scpi_usbtmc_libusb_read_data,
 625         .read_complete = scpi_usbtmc_libusb_read_complete,
 626         .close         = scpi_usbtmc_libusb_close,
 627         .free          = scpi_usbtmc_libusb_free,
 628 };