drivers/thunderbolt/ctl.c

   1 /*
   2  * Thunderbolt Cactus Ridge driver - control channel and configuration commands
   3  *
   4  * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
   5  */
   6
   7 #include <linux/crc32.h>
   8 #include <linux/slab.h>
   9 #include <linux/pci.h>
  10 #include <linux/dmapool.h>
  11 #include <linux/workqueue.h>
  12 #include <linux/kfifo.h>
  13
  14 #include "ctl.h"
  15
  16
  17 struct ctl_pkg {
  18         struct tb_ctl *ctl;
  19         void *buffer;
  20         struct ring_frame frame;
  21 };
  22
  23 #define TB_CTL_RX_PKG_COUNT 10
  24
  25 /**
  26  * struct tb_cfg - thunderbolt control channel
  27  */
  28 struct tb_ctl {
  29         struct tb_nhi *nhi;
  30         struct tb_ring *tx;
  31         struct tb_ring *rx;
  32
  33         struct dma_pool *frame_pool;
  34         struct ctl_pkg *rx_packets[TB_CTL_RX_PKG_COUNT];
  35         DECLARE_KFIFO(response_fifo, struct ctl_pkg*, 16);
  36         struct completion response_ready;
  37
  38         hotplug_cb callback;
  39         void *callback_data;
  40 };
  41
  42
  43 #define tb_ctl_WARN(ctl, format, arg...) \
  44         dev_WARN(&(ctl)->nhi->pdev->dev, format, ## arg)
  45
  46 #define tb_ctl_err(ctl, format, arg...) \
  47         dev_err(&(ctl)->nhi->pdev->dev, format, ## arg)
  48
  49 #define tb_ctl_warn(ctl, format, arg...) \
  50         dev_warn(&(ctl)->nhi->pdev->dev, format, ## arg)
  51
  52 #define tb_ctl_info(ctl, format, arg...) \
  53         dev_info(&(ctl)->nhi->pdev->dev, format, ## arg)
  54
  55 /* utility functions */
  56
  57 static u64 get_route(struct tb_cfg_header header)
  58 {
  59         return (u64) header.route_hi << 32 | header.route_lo;
  60 }
  61
  62 static struct tb_cfg_header make_header(u64 route)
  63 {
  64         struct tb_cfg_header header = {
  65                 .route_hi = route >> 32,
  66                 .route_lo = route,
  67         };
  68         /* check for overflow, route_hi is not 32 bits! */
  69         WARN_ON(get_route(header) != route);
  70         return header;
  71 }
  72
  73 static int check_header(struct ctl_pkg *pkg, u32 len, enum tb_cfg_pkg_type type,
  74                         u64 route)
  75 {
  76         struct tb_cfg_header *header = pkg->buffer;
  77
  78         /* check frame, TODO: frame flags */
  79         if (WARN(len != pkg->frame.size,
  80                         "wrong framesize (expected %#x, got %#x)\n",
  81                         len, pkg->frame.size))
  82                 return -EIO;
  83         if (WARN(type != pkg->frame.eof, "wrong eof (expected %#x, got %#x)\n",
  84                         type, pkg->frame.eof))
  85                 return -EIO;
  86         if (WARN(pkg->frame.sof, "wrong sof (expected 0x0, got %#x)\n",
  87                         pkg->frame.sof))
  88                 return -EIO;
  89
  90         /* check header */
  91         if (WARN(header->unknown != 1 << 9,
  92                         "header->unknown is %#x\n", header->unknown))
  93                 return -EIO;
  94         if (WARN(route != get_route(*header),
  95                         "wrong route (expected %llx, got %llx)",
  96                         route, get_route(*header)))
  97                 return -EIO;
  98         return 0;
  99 }
 100
 101 static int check_config_address(struct tb_cfg_address addr,
 102                                 enum tb_cfg_space space, u32 offset,
 103                                 u32 length)
 104 {
 105         if (WARN(addr.zero, "addr.zero is %#x\n", addr.zero))
 106                 return -EIO;
 107         if (WARN(space != addr.space, "wrong space (expected %x, got %x\n)",
 108                         space, addr.space))
 109                 return -EIO;
 110         if (WARN(offset != addr.offset, "wrong offset (expected %x, got %x\n)",
 111                         offset, addr.offset))
 112                 return -EIO;
 113         if (WARN(length != addr.length, "wrong space (expected %x, got %x\n)",
 114                         length, addr.length))
 115                 return -EIO;
 116         if (WARN(addr.seq, "addr.seq is %#x\n", addr.seq))
 117                 return -EIO;
 118         /*
 119          * We cannot check addr->port as it is set to the upstream port of the
 120          * sender.
 121          */
 122         return 0;
 123 }
 124
 125 static struct tb_cfg_result decode_error(struct ctl_pkg *response)
 126 {
 127         struct cfg_error_pkg *pkg = response->buffer;
 128         struct tb_cfg_result res = { 0 };
 129         res.response_route = get_route(pkg->header);
 130         res.response_port = 0;
 131         res.err = check_header(response, sizeof(*pkg), TB_CFG_PKG_ERROR,
 132                                get_route(pkg->header));
 133         if (res.err)
 134                 return res;
 135
 136         WARN(pkg->zero1, "pkg->zero1 is %#x\n", pkg->zero1);
 137         WARN(pkg->zero2, "pkg->zero1 is %#x\n", pkg->zero1);
 138         WARN(pkg->zero3, "pkg->zero1 is %#x\n", pkg->zero1);
 139         res.err = 1;
 140         res.tb_error = pkg->error;
 141         res.response_port = pkg->port;
 142         return res;
 143
 144 }
 145
 146 static struct tb_cfg_result parse_header(struct ctl_pkg *pkg, u32 len,
 147                                          enum tb_cfg_pkg_type type, u64 route)
 148 {
 149         struct tb_cfg_header *header = pkg->buffer;
 150         struct tb_cfg_result res = { 0 };
 151
 152         if (pkg->frame.eof == TB_CFG_PKG_ERROR)
 153                 return decode_error(pkg);
 154
 155         res.response_port = 0; /* will be updated later for cfg_read/write */
 156         res.response_route = get_route(*header);
 157         res.err = check_header(pkg, len, type, route);
 158         return res;
 159 }
 160
 161 static void tb_cfg_print_error(struct tb_ctl *ctl,
 162                                const struct tb_cfg_result *res)
 163 {
 164         WARN_ON(res->err != 1);
 165         switch (res->tb_error) {
 166         case TB_CFG_ERROR_PORT_NOT_CONNECTED:
 167                 /* Port is not connected. This can happen during surprise
 168                  * removal. Do not warn. */
 169                 return;
 170         case TB_CFG_ERROR_INVALID_CONFIG_SPACE:
 171                 /*
 172                  * Invalid cfg_space/offset/length combination in
 173                  * cfg_read/cfg_write.
 174                  */
 175                 tb_ctl_WARN(ctl,
 176                         "CFG_ERROR(%llx:%x): Invalid config space or offset\n",
 177                         res->response_route, res->response_port);
 178                 return;
 179         case TB_CFG_ERROR_NO_SUCH_PORT:
 180                 /*
 181                  * - The route contains a non-existent port.
 182                  * - The route contains a non-PHY port (e.g. PCIe).
 183                  * - The port in cfg_read/cfg_write does not exist.
 184                  */
 185                 tb_ctl_WARN(ctl, "CFG_ERROR(%llx:%x): Invalid port\n",
 186                         res->response_route, res->response_port);
 187                 return;
 188         case TB_CFG_ERROR_LOOP:
 189                 tb_ctl_WARN(ctl, "CFG_ERROR(%llx:%x): Route contains a loop\n",
 190                         res->response_route, res->response_port);
 191                 return;
 192         default:
 193                 /* 5,6,7,9 and 11 are also valid error codes */
 194                 tb_ctl_WARN(ctl, "CFG_ERROR(%llx:%x): Unknown error\n",
 195                         res->response_route, res->response_port);
 196                 return;
 197         }
 198 }
 199
 200 static void cpu_to_be32_array(__be32 *dst, const u32 *src, size_t len)
 201 {
 202         int i;
 203         for (i = 0; i < len; i++)
 204                 dst[i] = cpu_to_be32(src[i]);
 205 }
 206
 207 static void be32_to_cpu_array(u32 *dst, __be32 *src, size_t len)
 208 {
 209         int i;
 210         for (i = 0; i < len; i++)
 211                 dst[i] = be32_to_cpu(src[i]);
 212 }
 213
 214 static __be32 tb_crc(void *data, size_t len)
 215 {
 216         return cpu_to_be32(~__crc32c_le(~0, data, len));
 217 }
 218
 219 static void tb_ctl_pkg_free(struct ctl_pkg *pkg)
 220 {
 221         if (pkg) {
 222                 dma_pool_free(pkg->ctl->frame_pool,
 223                               pkg->buffer, pkg->frame.buffer_phy);
 224                 kfree(pkg);
 225         }
 226 }
 227
 228 static struct ctl_pkg *tb_ctl_pkg_alloc(struct tb_ctl *ctl)
 229 {
 230         struct ctl_pkg *pkg = kzalloc(sizeof(*pkg), GFP_KERNEL);
 231         if (!pkg)
 232                 return NULL;
 233         pkg->ctl = ctl;
 234         pkg->buffer = dma_pool_alloc(ctl->frame_pool, GFP_KERNEL,
 235                                      &pkg->frame.buffer_phy);
 236         if (!pkg->buffer) {
 237                 kfree(pkg);
 238                 return NULL;
 239         }
 240         return pkg;
 241 }
 242
 243
 244 /* RX/TX handling */
 245
 246 static void tb_ctl_tx_callback(struct tb_ring *ring, struct ring_frame *frame,
 247                                bool canceled)
 248 {
 249         struct ctl_pkg *pkg = container_of(frame, typeof(*pkg), frame);
 250         tb_ctl_pkg_free(pkg);
 251 }
 252
 253 /**
 254  * tb_cfg_tx() - transmit a packet on the control channel
 255  *
 256  * len must be a multiple of four.
 257  *
 258  * Return: Returns 0 on success or an error code on failure.
 259  */
 260 static int tb_ctl_tx(struct tb_ctl *ctl, const void *data, size_t len,
 261                      enum tb_cfg_pkg_type type)
 262 {
 263         int res;
 264         struct ctl_pkg *pkg;
 265         if (len % 4 != 0) { /* required for le->be conversion */
 266                 tb_ctl_WARN(ctl, "TX: invalid size: %zu\n", len);
 267                 return -EINVAL;
 268         }
 269         if (len > TB_FRAME_SIZE - 4) { /* checksum is 4 bytes */
 270                 tb_ctl_WARN(ctl, "TX: packet too large: %zu/%d\n",
 271                             len, TB_FRAME_SIZE - 4);
 272                 return -EINVAL;
 273         }
 274         pkg = tb_ctl_pkg_alloc(ctl);
 275         if (!pkg)
 276                 return -ENOMEM;
 277         pkg->frame.callback = tb_ctl_tx_callback;
 278         pkg->frame.size = len + 4;
 279         pkg->frame.sof = type;
 280         pkg->frame.eof = type;
 281         cpu_to_be32_array(pkg->buffer, data, len / 4);
 282         *(__be32 *) (pkg->buffer + len) = tb_crc(pkg->buffer, len);
 283
 284         res = ring_tx(ctl->tx, &pkg->frame);
 285         if (res) /* ring is stopped */
 286                 tb_ctl_pkg_free(pkg);
 287         return res;
 288 }
 289
 290 /**
 291  * tb_ctl_handle_plug_event() - acknowledge a plug event, invoke ctl->callback
 292  */
 293 static void tb_ctl_handle_plug_event(struct tb_ctl *ctl,
 294                                      struct ctl_pkg *response)
 295 {
 296         struct cfg_event_pkg *pkg = response->buffer;
 297         u64 route = get_route(pkg->header);
 298
 299         if (check_header(response, sizeof(*pkg), TB_CFG_PKG_EVENT, route)) {
 300                 tb_ctl_warn(ctl, "malformed TB_CFG_PKG_EVENT\n");
 301                 return;
 302         }
 303
 304         if (tb_cfg_error(ctl, route, pkg->port, TB_CFG_ERROR_ACK_PLUG_EVENT))
 305                 tb_ctl_warn(ctl, "could not ack plug event on %llx:%x\n",
 306                             route, pkg->port);
 307         WARN(pkg->zero, "pkg->zero is %#x\n", pkg->zero);
 308         ctl->callback(ctl->callback_data, route, pkg->port, pkg->unplug);
 309 }
 310
 311 static void tb_ctl_rx_submit(struct ctl_pkg *pkg)
 312 {
 313         ring_rx(pkg->ctl->rx, &pkg->frame); /*
 314                                              * We ignore failures during stop.
 315                                              * All rx packets are referenced
 316                                              * from ctl->rx_packets, so we do
 317                                              * not loose them.
 318                                              */
 319 }
 320
 321 static void tb_ctl_rx_callback(struct tb_ring *ring, struct ring_frame *frame,
 322                                bool canceled)
 323 {
 324         struct ctl_pkg *pkg = container_of(frame, typeof(*pkg), frame);
 325
 326         if (canceled)
 327                 return; /*
 328                          * ring is stopped, packet is referenced from
 329                          * ctl->rx_packets.
 330                          */
 331
 332         if (frame->size < 4 || frame->size % 4 != 0) {
 333                 tb_ctl_err(pkg->ctl, "RX: invalid size %#x, dropping packet\n",
 334                            frame->size);
 335                 goto rx;
 336         }
 337
 338         frame->size -= 4; /* remove checksum */
 339         if (*(__be32 *) (pkg->buffer + frame->size)
 340                         != tb_crc(pkg->buffer, frame->size)) {
 341                 tb_ctl_err(pkg->ctl,
 342                            "RX: checksum mismatch, dropping packet\n");
 343                 goto rx;
 344         }
 345         be32_to_cpu_array(pkg->buffer, pkg->buffer, frame->size / 4);
 346
 347         if (frame->eof == TB_CFG_PKG_EVENT) {
 348                 tb_ctl_handle_plug_event(pkg->ctl, pkg);
 349                 goto rx;
 350         }
 351         if (!kfifo_put(&pkg->ctl->response_fifo, pkg)) {
 352                 tb_ctl_err(pkg->ctl, "RX: fifo is full\n");
 353                 goto rx;
 354         }
 355         complete(&pkg->ctl->response_ready);
 356         return;
 357 rx:
 358         tb_ctl_rx_submit(pkg);
 359 }
 360
 361 /**
 362  * tb_ctl_rx() - receive a packet from the control channel
 363  */
 364 static struct tb_cfg_result tb_ctl_rx(struct tb_ctl *ctl, void *buffer,
 365                                       size_t length, int timeout_msec,
 366                                       u64 route, enum tb_cfg_pkg_type type)
 367 {
 368         struct tb_cfg_result res;
 369         struct ctl_pkg *pkg;
 370
 371         if (!wait_for_completion_timeout(&ctl->response_ready,
 372                                          msecs_to_jiffies(timeout_msec))) {
 373                 tb_ctl_WARN(ctl, "RX: timeout\n");
 374                 return (struct tb_cfg_result) { .err = -ETIMEDOUT };
 375         }
 376         if (!kfifo_get(&ctl->response_fifo, &pkg)) {
 377                 tb_ctl_WARN(ctl, "empty kfifo\n");
 378                 return (struct tb_cfg_result) { .err = -EIO };
 379         }
 380
 381         res = parse_header(pkg, length, type, route);
 382         if (!res.err)
 383                 memcpy(buffer, pkg->buffer, length);
 384         tb_ctl_rx_submit(pkg);
 385         return res;
 386 }
 387
 388
 389 /* public interface, alloc/start/stop/free */
 390
 391 /**
 392  * tb_ctl_alloc() - allocate a control channel
 393  *
 394  * cb will be invoked once for every hot plug event.
 395  *
 396  * Return: Returns a pointer on success or NULL on failure.
 397  */
 398 struct tb_ctl *tb_ctl_alloc(struct tb_nhi *nhi, hotplug_cb cb, void *cb_data)
 399 {
 400         int i;
 401         struct tb_ctl *ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
 402         if (!ctl)
 403                 return NULL;
 404         ctl->nhi = nhi;
 405         ctl->callback = cb;
 406         ctl->callback_data = cb_data;
 407
 408         init_completion(&ctl->response_ready);
 409         INIT_KFIFO(ctl->response_fifo);
 410         ctl->frame_pool = dma_pool_create("thunderbolt_ctl", &nhi->pdev->dev,
 411                                          TB_FRAME_SIZE, 4, 0);
 412         if (!ctl->frame_pool)
 413                 goto err;
 414
 415         ctl->tx = ring_alloc_tx(nhi, 0, 10, RING_FLAG_NO_SUSPEND);
 416         if (!ctl->tx)
 417                 goto err;
 418
 419         ctl->rx = ring_alloc_rx(nhi, 0, 10, RING_FLAG_NO_SUSPEND);
 420         if (!ctl->rx)
 421                 goto err;
 422
 423         for (i = 0; i < TB_CTL_RX_PKG_COUNT; i++) {
 424                 ctl->rx_packets[i] = tb_ctl_pkg_alloc(ctl);
 425                 if (!ctl->rx_packets[i])
 426                         goto err;
 427                 ctl->rx_packets[i]->frame.callback = tb_ctl_rx_callback;
 428         }
 429
 430         tb_ctl_info(ctl, "control channel created\n");
 431         return ctl;
 432 err:
 433         tb_ctl_free(ctl);
 434         return NULL;
 435 }
 436
 437 /**
 438  * tb_ctl_free() - free a control channel
 439  *
 440  * Must be called after tb_ctl_stop.
 441  *
 442  * Must NOT be called from ctl->callback.
 443  */
 444 void tb_ctl_free(struct tb_ctl *ctl)
 445 {
 446         int i;
 447
 448         if (!ctl)
 449                 return;
 450
 451         if (ctl->rx)
 452                 ring_free(ctl->rx);
 453         if (ctl->tx)
 454                 ring_free(ctl->tx);
 455
 456         /* free RX packets */
 457         for (i = 0; i < TB_CTL_RX_PKG_COUNT; i++)
 458                 tb_ctl_pkg_free(ctl->rx_packets[i]);
 459
 460
 461         if (ctl->frame_pool)
 462                 dma_pool_destroy(ctl->frame_pool);
 463         kfree(ctl);
 464 }
 465
 466 /**
 467  * tb_cfg_start() - start/resume the control channel
 468  */
 469 void tb_ctl_start(struct tb_ctl *ctl)
 470 {
 471         int i;
 472         tb_ctl_info(ctl, "control channel starting...\n");
 473         ring_start(ctl->tx); /* is used to ack hotplug packets, start first */
 474         ring_start(ctl->rx);
 475         for (i = 0; i < TB_CTL_RX_PKG_COUNT; i++)
 476                 tb_ctl_rx_submit(ctl->rx_packets[i]);
 477 }
 478
 479 /**
 480  * control() - pause the control channel
 481  *
 482  * All invocations of ctl->callback will have finished after this method
 483  * returns.
 484  *
 485  * Must NOT be called from ctl->callback.
 486  */
 487 void tb_ctl_stop(struct tb_ctl *ctl)
 488 {
 489         ring_stop(ctl->rx);
 490         ring_stop(ctl->tx);
 491
 492         if (!kfifo_is_empty(&ctl->response_fifo))
 493                 tb_ctl_WARN(ctl, "dangling response in response_fifo\n");
 494         kfifo_reset(&ctl->response_fifo);
 495         tb_ctl_info(ctl, "control channel stopped\n");
 496 }
 497
 498 /* public interface, commands */
 499
 500 /**
 501  * tb_cfg_error() - send error packet
 502  *
 503  * Return: Returns 0 on success or an error code on failure.
 504  */
 505 int tb_cfg_error(struct tb_ctl *ctl, u64 route, u32 port,
 506                  enum tb_cfg_error error)
 507 {
 508         struct cfg_error_pkg pkg = {
 509                 .header = make_header(route),
 510                 .port = port,
 511                 .error = error,
 512         };
 513         tb_ctl_info(ctl, "resetting error on %llx:%x.\n", route, port);
 514         return tb_ctl_tx(ctl, &pkg, sizeof(pkg), TB_CFG_PKG_ERROR);
 515 }
 516
 517 /**
 518  * tb_cfg_reset() - send a reset packet and wait for a response
 519  *
 520  * If the switch at route is incorrectly configured then we will not receive a
 521  * reply (even though the switch will reset). The caller should check for
 522  * -ETIMEDOUT and attempt to reconfigure the switch.
 523  */
 524 struct tb_cfg_result tb_cfg_reset(struct tb_ctl *ctl, u64 route,
 525                                   int timeout_msec)
 526 {
 527         int err;
 528         struct cfg_reset_pkg request = { .header = make_header(route) };
 529         struct tb_cfg_header reply;
 530
 531         err = tb_ctl_tx(ctl, &request, sizeof(request), TB_CFG_PKG_RESET);
 532         if (err)
 533                 return (struct tb_cfg_result) { .err = err };
 534
 535         return tb_ctl_rx(ctl, &reply, sizeof(reply), timeout_msec, route,
 536                          TB_CFG_PKG_RESET);
 537 }
 538
 539 /**
 540  * tb_cfg_read() - read from config space into buffer
 541  *
 542  * Offset and length are in dwords.
 543  */
 544 struct tb_cfg_result tb_cfg_read_raw(struct tb_ctl *ctl, void *buffer,
 545                 u64 route, u32 port, enum tb_cfg_space space,
 546                 u32 offset, u32 length, int timeout_msec)
 547 {
 548         struct tb_cfg_result res = { 0 };
 549         struct cfg_read_pkg request = {
 550                 .header = make_header(route),
 551                 .addr = {
 552                         .port = port,
 553                         .space = space,
 554                         .offset = offset,
 555                         .length = length,
 556                 },
 557         };
 558         struct cfg_write_pkg reply;
 559
 560         res.err = tb_ctl_tx(ctl, &request, sizeof(request), TB_CFG_PKG_READ);
 561         if (res.err)
 562                 return res;
 563
 564         res = tb_ctl_rx(ctl, &reply, 12 + 4 * length, timeout_msec, route,
 565                         TB_CFG_PKG_READ);
 566         if (res.err)
 567                 return res;
 568
 569         res.response_port = reply.addr.port;
 570         res.err = check_config_address(reply.addr, space, offset, length);
 571         if (!res.err)
 572                 memcpy(buffer, &reply.data, 4 * length);
 573         return res;
 574 }
 575
 576 /**
 577  * tb_cfg_write() - write from buffer into config space
 578  *
 579  * Offset and length are in dwords.
 580  */
 581 struct tb_cfg_result tb_cfg_write_raw(struct tb_ctl *ctl, const void *buffer,
 582                 u64 route, u32 port, enum tb_cfg_space space,
 583                 u32 offset, u32 length, int timeout_msec)
 584 {
 585         struct tb_cfg_result res = { 0 };
 586         struct cfg_write_pkg request = {
 587                 .header = make_header(route),
 588                 .addr = {
 589                         .port = port,
 590                         .space = space,
 591                         .offset = offset,
 592                         .length = length,
 593                 },
 594         };
 595         struct cfg_read_pkg reply;
 596
 597         memcpy(&request.data, buffer, length * 4);
 598
 599         res.err = tb_ctl_tx(ctl, &request, 12 + 4 * length, TB_CFG_PKG_WRITE);
 600         if (res.err)
 601                 return res;
 602
 603         res = tb_ctl_rx(ctl, &reply, sizeof(reply), timeout_msec, route,
 604                         TB_CFG_PKG_WRITE);
 605         if (res.err)
 606                 return res;
 607
 608         res.response_port = reply.addr.port;
 609         res.err = check_config_address(reply.addr, space, offset, length);
 610         return res;
 611 }
 612
 613 int tb_cfg_read(struct tb_ctl *ctl, void *buffer, u64 route, u32 port,
 614                 enum tb_cfg_space space, u32 offset, u32 length)
 615 {
 616         struct tb_cfg_result res = tb_cfg_read_raw(ctl, buffer, route, port,
 617                         space, offset, length, TB_CFG_DEFAULT_TIMEOUT);
 618         if (res.err == 1) {
 619                 tb_cfg_print_error(ctl, &res);
 620                 return -EIO;
 621         }
 622         WARN(res.err, "tb_cfg_read: %d\n", res.err);
 623         return res.err;
 624 }
 625
 626 int tb_cfg_write(struct tb_ctl *ctl, const void *buffer, u64 route, u32 port,
 627                  enum tb_cfg_space space, u32 offset, u32 length)
 628 {
 629         struct tb_cfg_result res = tb_cfg_write_raw(ctl, buffer, route, port,
 630                         space, offset, length, TB_CFG_DEFAULT_TIMEOUT);
 631         if (res.err == 1) {
 632                 tb_cfg_print_error(ctl, &res);
 633                 return -EIO;
 634         }
 635         WARN(res.err, "tb_cfg_write: %d\n", res.err);
 636         return res.err;
 637 }
 638
 639 /**
 640  * tb_cfg_get_upstream_port() - get upstream port number of switch at route
 641  *
 642  * Reads the first dword from the switches TB_CFG_SWITCH config area and
 643  * returns the port number from which the reply originated.
 644  *
 645  * Return: Returns the upstream port number on success or an error code on
 646  * failure.
 647  */
 648 int tb_cfg_get_upstream_port(struct tb_ctl *ctl, u64 route)
 649 {
 650         u32 dummy;
 651         struct tb_cfg_result res = tb_cfg_read_raw(ctl, &dummy, route, 0,
 652                                                    TB_CFG_SWITCH, 0, 1,
 653                                                    TB_CFG_DEFAULT_TIMEOUT);
 654         if (res.err == 1)
 655                 return -EIO;
 656         if (res.err)
 657                 return res.err;
 658         return res.response_port;
 659 }