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