drivers/staging/greybus/operation.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Greybus operations
   4  *
   5  * Copyright 2014-2015 Google Inc.
   6  * Copyright 2014-2015 Linaro Ltd.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/slab.h>
  11 #include <linux/module.h>
  12 #include <linux/sched.h>
  13 #include <linux/wait.h>
  14 #include <linux/workqueue.h>
  15
  16 #include "greybus.h"
  17 #include "greybus_trace.h"
  18
  19 static struct kmem_cache *gb_operation_cache;
  20 static struct kmem_cache *gb_message_cache;
  21
  22 /* Workqueue to handle Greybus operation completions. */
  23 static struct workqueue_struct *gb_operation_completion_wq;
  24
  25 /* Wait queue for synchronous cancellations. */
  26 static DECLARE_WAIT_QUEUE_HEAD(gb_operation_cancellation_queue);
  27
  28 /*
  29  * Protects updates to operation->errno.
  30  */
  31 static DEFINE_SPINLOCK(gb_operations_lock);
  32
  33 static int gb_operation_response_send(struct gb_operation *operation,
  34                                         int errno);
  35
  36 /*
  37  * Increment operation active count and add to connection list unless the
  38  * connection is going away.
  39  *
  40  * Caller holds operation reference.
  41  */
  42 static int gb_operation_get_active(struct gb_operation *operation)
  43 {
  44         struct gb_connection *connection = operation->connection;
  45         unsigned long flags;
  46
  47         spin_lock_irqsave(&connection->lock, flags);
  48         switch (connection->state) {
  49         case GB_CONNECTION_STATE_ENABLED:
  50                 break;
  51         case GB_CONNECTION_STATE_ENABLED_TX:
  52                 if (gb_operation_is_incoming(operation))
  53                         goto err_unlock;
  54                 break;
  55         case GB_CONNECTION_STATE_DISCONNECTING:
  56                 if (!gb_operation_is_core(operation))
  57                         goto err_unlock;
  58                 break;
  59         default:
  60                 goto err_unlock;
  61         }
  62
  63         if (operation->active++ == 0)
  64                 list_add_tail(&operation->links, &connection->operations);
  65
  66         trace_gb_operation_get_active(operation);
  67
  68         spin_unlock_irqrestore(&connection->lock, flags);
  69
  70         return 0;
  71
  72 err_unlock:
  73         spin_unlock_irqrestore(&connection->lock, flags);
  74
  75         return -ENOTCONN;
  76 }
  77
  78 /* Caller holds operation reference. */
  79 static void gb_operation_put_active(struct gb_operation *operation)
  80 {
  81         struct gb_connection *connection = operation->connection;
  82         unsigned long flags;
  83
  84         spin_lock_irqsave(&connection->lock, flags);
  85
  86         trace_gb_operation_put_active(operation);
  87
  88         if (--operation->active == 0) {
  89                 list_del(&operation->links);
  90                 if (atomic_read(&operation->waiters))
  91                         wake_up(&gb_operation_cancellation_queue);
  92         }
  93         spin_unlock_irqrestore(&connection->lock, flags);
  94 }
  95
  96 static bool gb_operation_is_active(struct gb_operation *operation)
  97 {
  98         struct gb_connection *connection = operation->connection;
  99         unsigned long flags;
 100         bool ret;
 101
 102         spin_lock_irqsave(&connection->lock, flags);
 103         ret = operation->active;
 104         spin_unlock_irqrestore(&connection->lock, flags);
 105
 106         return ret;
 107 }
 108
 109 /*
 110  * Set an operation's result.
 111  *
 112  * Initially an outgoing operation's errno value is -EBADR.
 113  * If no error occurs before sending the request message the only
 114  * valid value operation->errno can be set to is -EINPROGRESS,
 115  * indicating the request has been (or rather is about to be) sent.
 116  * At that point nobody should be looking at the result until the
 117  * response arrives.
 118  *
 119  * The first time the result gets set after the request has been
 120  * sent, that result "sticks."  That is, if two concurrent threads
 121  * race to set the result, the first one wins.  The return value
 122  * tells the caller whether its result was recorded; if not the
 123  * caller has nothing more to do.
 124  *
 125  * The result value -EILSEQ is reserved to signal an implementation
 126  * error; if it's ever observed, the code performing the request has
 127  * done something fundamentally wrong.  It is an error to try to set
 128  * the result to -EBADR, and attempts to do so result in a warning,
 129  * and -EILSEQ is used instead.  Similarly, the only valid result
 130  * value to set for an operation in initial state is -EINPROGRESS.
 131  * Attempts to do otherwise will also record a (successful) -EILSEQ
 132  * operation result.
 133  */
 134 static bool gb_operation_result_set(struct gb_operation *operation, int result)
 135 {
 136         unsigned long flags;
 137         int prev;
 138
 139         if (result == -EINPROGRESS) {
 140                 /*
 141                  * -EINPROGRESS is used to indicate the request is
 142                  * in flight.  It should be the first result value
 143                  * set after the initial -EBADR.  Issue a warning
 144                  * and record an implementation error if it's
 145                  * set at any other time.
 146                  */
 147                 spin_lock_irqsave(&gb_operations_lock, flags);
 148                 prev = operation->errno;
 149                 if (prev == -EBADR)
 150                         operation->errno = result;
 151                 else
 152                         operation->errno = -EILSEQ;
 153                 spin_unlock_irqrestore(&gb_operations_lock, flags);
 154                 WARN_ON(prev != -EBADR);
 155
 156                 return true;
 157         }
 158
 159         /*
 160          * The first result value set after a request has been sent
 161          * will be the final result of the operation.  Subsequent
 162          * attempts to set the result are ignored.
 163          *
 164          * Note that -EBADR is a reserved "initial state" result
 165          * value.  Attempts to set this value result in a warning,
 166          * and the result code is set to -EILSEQ instead.
 167          */
 168         if (WARN_ON(result == -EBADR))
 169                 result = -EILSEQ; /* Nobody should be setting -EBADR */
 170
 171         spin_lock_irqsave(&gb_operations_lock, flags);
 172         prev = operation->errno;
 173         if (prev == -EINPROGRESS)
 174                 operation->errno = result;      /* First and final result */
 175         spin_unlock_irqrestore(&gb_operations_lock, flags);
 176
 177         return prev == -EINPROGRESS;
 178 }
 179
 180 int gb_operation_result(struct gb_operation *operation)
 181 {
 182         int result = operation->errno;
 183
 184         WARN_ON(result == -EBADR);
 185         WARN_ON(result == -EINPROGRESS);
 186
 187         return result;
 188 }
 189 EXPORT_SYMBOL_GPL(gb_operation_result);
 190
 191 /*
 192  * Looks up an outgoing operation on a connection and returns a refcounted
 193  * pointer if found, or NULL otherwise.
 194  */
 195 static struct gb_operation *
 196 gb_operation_find_outgoing(struct gb_connection *connection, u16 operation_id)
 197 {
 198         struct gb_operation *operation;
 199         unsigned long flags;
 200         bool found = false;
 201
 202         spin_lock_irqsave(&connection->lock, flags);
 203         list_for_each_entry(operation, &connection->operations, links)
 204                 if (operation->id == operation_id &&
 205                                 !gb_operation_is_incoming(operation)) {
 206                         gb_operation_get(operation);
 207                         found = true;
 208                         break;
 209                 }
 210         spin_unlock_irqrestore(&connection->lock, flags);
 211
 212         return found ? operation : NULL;
 213 }
 214
 215 static int gb_message_send(struct gb_message *message, gfp_t gfp)
 216 {
 217         struct gb_connection *connection = message->operation->connection;
 218
 219         trace_gb_message_send(message);
 220         return connection->hd->driver->message_send(connection->hd,
 221                                         connection->hd_cport_id,
 222                                         message,
 223                                         gfp);
 224 }
 225
 226 /*
 227  * Cancel a message we have passed to the host device layer to be sent.
 228  */
 229 static void gb_message_cancel(struct gb_message *message)
 230 {
 231         struct gb_host_device *hd = message->operation->connection->hd;
 232
 233         hd->driver->message_cancel(message);
 234 }
 235
 236 static void gb_operation_request_handle(struct gb_operation *operation)
 237 {
 238         struct gb_connection *connection = operation->connection;
 239         int status;
 240         int ret;
 241
 242         if (connection->handler) {
 243                 status = connection->handler(operation);
 244         } else {
 245                 dev_err(&connection->hd->dev,
 246                         "%s: unexpected incoming request of type 0x%02x\n",
 247                         connection->name, operation->type);
 248
 249                 status = -EPROTONOSUPPORT;
 250         }
 251
 252         ret = gb_operation_response_send(operation, status);
 253         if (ret) {
 254                 dev_err(&connection->hd->dev,
 255                         "%s: failed to send response %d for type 0x%02x: %d\n",
 256                         connection->name, status, operation->type, ret);
 257                 return;
 258         }
 259 }
 260
 261 /*
 262  * Process operation work.
 263  *
 264  * For incoming requests, call the protocol request handler. The operation
 265  * result should be -EINPROGRESS at this point.
 266  *
 267  * For outgoing requests, the operation result value should have
 268  * been set before queueing this.  The operation callback function
 269  * allows the original requester to know the request has completed
 270  * and its result is available.
 271  */
 272 static void gb_operation_work(struct work_struct *work)
 273 {
 274         struct gb_operation *operation;
 275         int ret;
 276
 277         operation = container_of(work, struct gb_operation, work);
 278
 279         if (gb_operation_is_incoming(operation)) {
 280                 gb_operation_request_handle(operation);
 281         } else {
 282                 ret = del_timer_sync(&operation->timer);
 283                 if (!ret) {
 284                         /* Cancel request message if scheduled by timeout. */
 285                         if (gb_operation_result(operation) == -ETIMEDOUT)
 286                                 gb_message_cancel(operation->request);
 287                 }
 288
 289                 operation->callback(operation);
 290         }
 291
 292         gb_operation_put_active(operation);
 293         gb_operation_put(operation);
 294 }
 295
 296 static void gb_operation_timeout(unsigned long arg)
 297 {
 298         struct gb_operation *operation = (void *)arg;
 299
 300         if (gb_operation_result_set(operation, -ETIMEDOUT)) {
 301                 /*
 302                  * A stuck request message will be cancelled from the
 303                  * workqueue.
 304                  */
 305                 queue_work(gb_operation_completion_wq, &operation->work);
 306         }
 307 }
 308
 309 static void gb_operation_message_init(struct gb_host_device *hd,
 310                                 struct gb_message *message, u16 operation_id,
 311                                 size_t payload_size, u8 type)
 312 {
 313         struct gb_operation_msg_hdr *header;
 314
 315         header = message->buffer;
 316
 317         message->header = header;
 318         message->payload = payload_size ? header + 1 : NULL;
 319         message->payload_size = payload_size;
 320
 321         /*
 322          * The type supplied for incoming message buffers will be
 323          * GB_REQUEST_TYPE_INVALID. Such buffers will be overwritten by
 324          * arriving data so there's no need to initialize the message header.
 325          */
 326         if (type != GB_REQUEST_TYPE_INVALID) {
 327                 u16 message_size = (u16)(sizeof(*header) + payload_size);
 328
 329                 /*
 330                  * For a request, the operation id gets filled in
 331                  * when the message is sent.  For a response, it
 332                  * will be copied from the request by the caller.
 333                  *
 334                  * The result field in a request message must be
 335                  * zero.  It will be set just prior to sending for
 336                  * a response.
 337                  */
 338                 header->size = cpu_to_le16(message_size);
 339                 header->operation_id = 0;
 340                 header->type = type;
 341                 header->result = 0;
 342         }
 343 }
 344
 345 /*
 346  * Allocate a message to be used for an operation request or response.
 347  * Both types of message contain a common header.  The request message
 348  * for an outgoing operation is outbound, as is the response message
 349  * for an incoming operation.  The message header for an outbound
 350  * message is partially initialized here.
 351  *
 352  * The headers for inbound messages don't need to be initialized;
 353  * they'll be filled in by arriving data.
 354  *
 355  * Our message buffers have the following layout:
 356  *      message header  \_ these combined are
 357  *      message payload /  the message size
 358  */
 359 static struct gb_message *
 360 gb_operation_message_alloc(struct gb_host_device *hd, u8 type,
 361                                 size_t payload_size, gfp_t gfp_flags)
 362 {
 363         struct gb_message *message;
 364         struct gb_operation_msg_hdr *header;
 365         size_t message_size = payload_size + sizeof(*header);
 366
 367         if (message_size > hd->buffer_size_max) {
 368                 dev_warn(&hd->dev, "requested message size too big (%zu > %zu)\n",
 369                                 message_size, hd->buffer_size_max);
 370                 return NULL;
 371         }
 372
 373         /* Allocate the message structure and buffer. */
 374         message = kmem_cache_zalloc(gb_message_cache, gfp_flags);
 375         if (!message)
 376                 return NULL;
 377
 378         message->buffer = kzalloc(message_size, gfp_flags);
 379         if (!message->buffer)
 380                 goto err_free_message;
 381
 382         /* Initialize the message.  Operation id is filled in later. */
 383         gb_operation_message_init(hd, message, 0, payload_size, type);
 384
 385         return message;
 386
 387 err_free_message:
 388         kmem_cache_free(gb_message_cache, message);
 389
 390         return NULL;
 391 }
 392
 393 static void gb_operation_message_free(struct gb_message *message)
 394 {
 395         kfree(message->buffer);
 396         kmem_cache_free(gb_message_cache, message);
 397 }
 398
 399 /*
 400  * Map an enum gb_operation_status value (which is represented in a
 401  * message as a single byte) to an appropriate Linux negative errno.
 402  */
 403 static int gb_operation_status_map(u8 status)
 404 {
 405         switch (status) {
 406         case GB_OP_SUCCESS:
 407                 return 0;
 408         case GB_OP_INTERRUPTED:
 409                 return -EINTR;
 410         case GB_OP_TIMEOUT:
 411                 return -ETIMEDOUT;
 412         case GB_OP_NO_MEMORY:
 413                 return -ENOMEM;
 414         case GB_OP_PROTOCOL_BAD:
 415                 return -EPROTONOSUPPORT;
 416         case GB_OP_OVERFLOW:
 417                 return -EMSGSIZE;
 418         case GB_OP_INVALID:
 419                 return -EINVAL;
 420         case GB_OP_RETRY:
 421                 return -EAGAIN;
 422         case GB_OP_NONEXISTENT:
 423                 return -ENODEV;
 424         case GB_OP_MALFUNCTION:
 425                 return -EILSEQ;
 426         case GB_OP_UNKNOWN_ERROR:
 427         default:
 428                 return -EIO;
 429         }
 430 }
 431
 432 /*
 433  * Map a Linux errno value (from operation->errno) into the value
 434  * that should represent it in a response message status sent
 435  * over the wire.  Returns an enum gb_operation_status value (which
 436  * is represented in a message as a single byte).
 437  */
 438 static u8 gb_operation_errno_map(int errno)
 439 {
 440         switch (errno) {
 441         case 0:
 442                 return GB_OP_SUCCESS;
 443         case -EINTR:
 444                 return GB_OP_INTERRUPTED;
 445         case -ETIMEDOUT:
 446                 return GB_OP_TIMEOUT;
 447         case -ENOMEM:
 448                 return GB_OP_NO_MEMORY;
 449         case -EPROTONOSUPPORT:
 450                 return GB_OP_PROTOCOL_BAD;
 451         case -EMSGSIZE:
 452                 return GB_OP_OVERFLOW;  /* Could be underflow too */
 453         case -EINVAL:
 454                 return GB_OP_INVALID;
 455         case -EAGAIN:
 456                 return GB_OP_RETRY;
 457         case -EILSEQ:
 458                 return GB_OP_MALFUNCTION;
 459         case -ENODEV:
 460                 return GB_OP_NONEXISTENT;
 461         case -EIO:
 462         default:
 463                 return GB_OP_UNKNOWN_ERROR;
 464         }
 465 }
 466
 467 bool gb_operation_response_alloc(struct gb_operation *operation,
 468                                         size_t response_size, gfp_t gfp)
 469 {
 470         struct gb_host_device *hd = operation->connection->hd;
 471         struct gb_operation_msg_hdr *request_header;
 472         struct gb_message *response;
 473         u8 type;
 474
 475         type = operation->type | GB_MESSAGE_TYPE_RESPONSE;
 476         response = gb_operation_message_alloc(hd, type, response_size, gfp);
 477         if (!response)
 478                 return false;
 479         response->operation = operation;
 480
 481         /*
 482          * Size and type get initialized when the message is
 483          * allocated.  The errno will be set before sending.  All
 484          * that's left is the operation id, which we copy from the
 485          * request message header (as-is, in little-endian order).
 486          */
 487         request_header = operation->request->header;
 488         response->header->operation_id = request_header->operation_id;
 489         operation->response = response;
 490
 491         return true;
 492 }
 493 EXPORT_SYMBOL_GPL(gb_operation_response_alloc);
 494
 495 /*
 496  * Create a Greybus operation to be sent over the given connection.
 497  * The request buffer will be big enough for a payload of the given
 498  * size.
 499  *
 500  * For outgoing requests, the request message's header will be
 501  * initialized with the type of the request and the message size.
 502  * Outgoing operations must also specify the response buffer size,
 503  * which must be sufficient to hold all expected response data.  The
 504  * response message header will eventually be overwritten, so there's
 505  * no need to initialize it here.
 506  *
 507  * Request messages for incoming operations can arrive in interrupt
 508  * context, so they must be allocated with GFP_ATOMIC.  In this case
 509  * the request buffer will be immediately overwritten, so there is
 510  * no need to initialize the message header.  Responsibility for
 511  * allocating a response buffer lies with the incoming request
 512  * handler for a protocol.  So we don't allocate that here.
 513  *
 514  * Returns a pointer to the new operation or a null pointer if an
 515  * error occurs.
 516  */
 517 static struct gb_operation *
 518 gb_operation_create_common(struct gb_connection *connection, u8 type,
 519                                 size_t request_size, size_t response_size,
 520                                 unsigned long op_flags, gfp_t gfp_flags)
 521 {
 522         struct gb_host_device *hd = connection->hd;
 523         struct gb_operation *operation;
 524
 525         operation = kmem_cache_zalloc(gb_operation_cache, gfp_flags);
 526         if (!operation)
 527                 return NULL;
 528         operation->connection = connection;
 529
 530         operation->request = gb_operation_message_alloc(hd, type, request_size,
 531                                                         gfp_flags);
 532         if (!operation->request)
 533                 goto err_cache;
 534         operation->request->operation = operation;
 535
 536         /* Allocate the response buffer for outgoing operations */
 537         if (!(op_flags & GB_OPERATION_FLAG_INCOMING)) {
 538                 if (!gb_operation_response_alloc(operation, response_size,
 539                                                  gfp_flags)) {
 540                         goto err_request;
 541                 }
 542
 543                 setup_timer(&operation->timer, gb_operation_timeout,
 544                             (unsigned long)operation);
 545         }
 546
 547         operation->flags = op_flags;
 548         operation->type = type;
 549         operation->errno = -EBADR;  /* Initial value--means "never set" */
 550
 551         INIT_WORK(&operation->work, gb_operation_work);
 552         init_completion(&operation->completion);
 553         kref_init(&operation->kref);
 554         atomic_set(&operation->waiters, 0);
 555
 556         return operation;
 557
 558 err_request:
 559         gb_operation_message_free(operation->request);
 560 err_cache:
 561         kmem_cache_free(gb_operation_cache, operation);
 562
 563         return NULL;
 564 }
 565
 566 /*
 567  * Create a new operation associated with the given connection.  The
 568  * request and response sizes provided are the number of bytes
 569  * required to hold the request/response payload only.  Both of
 570  * these are allowed to be 0.  Note that 0x00 is reserved as an
 571  * invalid operation type for all protocols, and this is enforced
 572  * here.
 573  */
 574 struct gb_operation *
 575 gb_operation_create_flags(struct gb_connection *connection,
 576                                 u8 type, size_t request_size,
 577                                 size_t response_size, unsigned long flags,
 578                                 gfp_t gfp)
 579 {
 580         struct gb_operation *operation;
 581
 582         if (WARN_ON_ONCE(type == GB_REQUEST_TYPE_INVALID))
 583                 return NULL;
 584         if (WARN_ON_ONCE(type & GB_MESSAGE_TYPE_RESPONSE))
 585                 type &= ~GB_MESSAGE_TYPE_RESPONSE;
 586
 587         if (WARN_ON_ONCE(flags & ~GB_OPERATION_FLAG_USER_MASK))
 588                 flags &= GB_OPERATION_FLAG_USER_MASK;
 589
 590         operation = gb_operation_create_common(connection, type,
 591                                                 request_size, response_size,
 592                                                 flags, gfp);
 593         if (operation)
 594                 trace_gb_operation_create(operation);
 595
 596         return operation;
 597 }
 598 EXPORT_SYMBOL_GPL(gb_operation_create_flags);
 599
 600 struct gb_operation *
 601 gb_operation_create_core(struct gb_connection *connection,
 602                                 u8 type, size_t request_size,
 603                                 size_t response_size, unsigned long flags,
 604                                 gfp_t gfp)
 605 {
 606         struct gb_operation *operation;
 607
 608         flags |= GB_OPERATION_FLAG_CORE;
 609
 610         operation = gb_operation_create_common(connection, type,
 611                                                 request_size, response_size,
 612                                                 flags, gfp);
 613         if (operation)
 614                 trace_gb_operation_create_core(operation);
 615
 616         return operation;
 617 }
 618 /* Do not export this function. */
 619
 620 size_t gb_operation_get_payload_size_max(struct gb_connection *connection)
 621 {
 622         struct gb_host_device *hd = connection->hd;
 623
 624         return hd->buffer_size_max - sizeof(struct gb_operation_msg_hdr);
 625 }
 626 EXPORT_SYMBOL_GPL(gb_operation_get_payload_size_max);
 627
 628 static struct gb_operation *
 629 gb_operation_create_incoming(struct gb_connection *connection, u16 id,
 630                                 u8 type, void *data, size_t size)
 631 {
 632         struct gb_operation *operation;
 633         size_t request_size;
 634         unsigned long flags = GB_OPERATION_FLAG_INCOMING;
 635
 636         /* Caller has made sure we at least have a message header. */
 637         request_size = size - sizeof(struct gb_operation_msg_hdr);
 638
 639         if (!id)
 640                 flags |= GB_OPERATION_FLAG_UNIDIRECTIONAL;
 641
 642         operation = gb_operation_create_common(connection, type,
 643                                                 request_size,
 644                                                 GB_REQUEST_TYPE_INVALID,
 645                                                 flags, GFP_ATOMIC);
 646         if (!operation)
 647                 return NULL;
 648
 649         operation->id = id;
 650         memcpy(operation->request->header, data, size);
 651         trace_gb_operation_create_incoming(operation);
 652
 653         return operation;
 654 }
 655
 656 /*
 657  * Get an additional reference on an operation.
 658  */
 659 void gb_operation_get(struct gb_operation *operation)
 660 {
 661         kref_get(&operation->kref);
 662 }
 663 EXPORT_SYMBOL_GPL(gb_operation_get);
 664
 665 /*
 666  * Destroy a previously created operation.
 667  */
 668 static void _gb_operation_destroy(struct kref *kref)
 669 {
 670         struct gb_operation *operation;
 671
 672         operation = container_of(kref, struct gb_operation, kref);
 673
 674         trace_gb_operation_destroy(operation);
 675
 676         if (operation->response)
 677                 gb_operation_message_free(operation->response);
 678         gb_operation_message_free(operation->request);
 679
 680         kmem_cache_free(gb_operation_cache, operation);
 681 }
 682
 683 /*
 684  * Drop a reference on an operation, and destroy it when the last
 685  * one is gone.
 686  */
 687 void gb_operation_put(struct gb_operation *operation)
 688 {
 689         if (WARN_ON(!operation))
 690                 return;
 691
 692         kref_put(&operation->kref, _gb_operation_destroy);
 693 }
 694 EXPORT_SYMBOL_GPL(gb_operation_put);
 695
 696 /* Tell the requester we're done */
 697 static void gb_operation_sync_callback(struct gb_operation *operation)
 698 {
 699         complete(&operation->completion);
 700 }
 701
 702 /**
 703  * gb_operation_request_send() - send an operation request message
 704  * @operation:  the operation to initiate
 705  * @callback:   the operation completion callback
 706  * @timeout:    operation timeout in milliseconds, or zero for no timeout
 707  * @gfp:        the memory flags to use for any allocations
 708  *
 709  * The caller has filled in any payload so the request message is ready to go.
 710  * The callback function supplied will be called when the response message has
 711  * arrived, a unidirectional request has been sent, or the operation is
 712  * cancelled, indicating that the operation is complete. The callback function
 713  * can fetch the result of the operation using gb_operation_result() if
 714  * desired.
 715  *
 716  * Return: 0 if the request was successfully queued in the host-driver queues,
 717  * or a negative errno.
 718  */
 719 int gb_operation_request_send(struct gb_operation *operation,
 720                                 gb_operation_callback callback,
 721                                 unsigned int timeout,
 722                                 gfp_t gfp)
 723 {
 724         struct gb_connection *connection = operation->connection;
 725         struct gb_operation_msg_hdr *header;
 726         unsigned int cycle;
 727         int ret;
 728
 729         if (gb_connection_is_offloaded(connection))
 730                 return -EBUSY;
 731
 732         if (!callback)
 733                 return -EINVAL;
 734
 735         /*
 736          * Record the callback function, which is executed in
 737          * non-atomic (workqueue) context when the final result
 738          * of an operation has been set.
 739          */
 740         operation->callback = callback;
 741
 742         /*
 743          * Assign the operation's id, and store it in the request header.
 744          * Zero is a reserved operation id for unidirectional operations.
 745          */
 746         if (gb_operation_is_unidirectional(operation)) {
 747                 operation->id = 0;
 748         } else {
 749                 cycle = (unsigned int)atomic_inc_return(&connection->op_cycle);
 750                 operation->id = (u16)(cycle % U16_MAX + 1);
 751         }
 752
 753         header = operation->request->header;
 754         header->operation_id = cpu_to_le16(operation->id);
 755
 756         gb_operation_result_set(operation, -EINPROGRESS);
 757
 758         /*
 759          * Get an extra reference on the operation. It'll be dropped when the
 760          * operation completes.
 761          */
 762         gb_operation_get(operation);
 763         ret = gb_operation_get_active(operation);
 764         if (ret)
 765                 goto err_put;
 766
 767         ret = gb_message_send(operation->request, gfp);
 768         if (ret)
 769                 goto err_put_active;
 770
 771         if (timeout) {
 772                 operation->timer.expires = jiffies + msecs_to_jiffies(timeout);
 773                 add_timer(&operation->timer);
 774         }
 775
 776         return 0;
 777
 778 err_put_active:
 779         gb_operation_put_active(operation);
 780 err_put:
 781         gb_operation_put(operation);
 782
 783         return ret;
 784 }
 785 EXPORT_SYMBOL_GPL(gb_operation_request_send);
 786
 787 /*
 788  * Send a synchronous operation.  This function is expected to
 789  * block, returning only when the response has arrived, (or when an
 790  * error is detected.  The return value is the result of the
 791  * operation.
 792  */
 793 int gb_operation_request_send_sync_timeout(struct gb_operation *operation,
 794                                                 unsigned int timeout)
 795 {
 796         int ret;
 797
 798         ret = gb_operation_request_send(operation, gb_operation_sync_callback,
 799                                         timeout, GFP_KERNEL);
 800         if (ret)
 801                 return ret;
 802
 803         ret = wait_for_completion_interruptible(&operation->completion);
 804         if (ret < 0) {
 805                 /* Cancel the operation if interrupted */
 806                 gb_operation_cancel(operation, -ECANCELED);
 807         }
 808
 809         return gb_operation_result(operation);
 810 }
 811 EXPORT_SYMBOL_GPL(gb_operation_request_send_sync_timeout);
 812
 813 /*
 814  * Send a response for an incoming operation request.  A non-zero
 815  * errno indicates a failed operation.
 816  *
 817  * If there is any response payload, the incoming request handler is
 818  * responsible for allocating the response message.  Otherwise the
 819  * it can simply supply the result errno; this function will
 820  * allocate the response message if necessary.
 821  */
 822 static int gb_operation_response_send(struct gb_operation *operation,
 823                                         int errno)
 824 {
 825         struct gb_connection *connection = operation->connection;
 826         int ret;
 827
 828         if (!operation->response &&
 829                         !gb_operation_is_unidirectional(operation)) {
 830                 if (!gb_operation_response_alloc(operation, 0, GFP_KERNEL))
 831                         return -ENOMEM;
 832         }
 833
 834         /* Record the result */
 835         if (!gb_operation_result_set(operation, errno)) {
 836                 dev_err(&connection->hd->dev, "request result already set\n");
 837                 return -EIO;    /* Shouldn't happen */
 838         }
 839
 840         /* Sender of request does not care about response. */
 841         if (gb_operation_is_unidirectional(operation))
 842                 return 0;
 843
 844         /* Reference will be dropped when message has been sent. */
 845         gb_operation_get(operation);
 846         ret = gb_operation_get_active(operation);
 847         if (ret)
 848                 goto err_put;
 849
 850         /* Fill in the response header and send it */
 851         operation->response->header->result = gb_operation_errno_map(errno);
 852
 853         ret = gb_message_send(operation->response, GFP_KERNEL);
 854         if (ret)
 855                 goto err_put_active;
 856
 857         return 0;
 858
 859 err_put_active:
 860         gb_operation_put_active(operation);
 861 err_put:
 862         gb_operation_put(operation);
 863
 864         return ret;
 865 }
 866
 867 /*
 868  * This function is called when a message send request has completed.
 869  */
 870 void greybus_message_sent(struct gb_host_device *hd,
 871                                         struct gb_message *message, int status)
 872 {
 873         struct gb_operation *operation = message->operation;
 874         struct gb_connection *connection = operation->connection;
 875
 876         /*
 877          * If the message was a response, we just need to drop our
 878          * reference to the operation.  If an error occurred, report
 879          * it.
 880          *
 881          * For requests, if there's no error and the operation in not
 882          * unidirectional, there's nothing more to do until the response
 883          * arrives. If an error occurred attempting to send it, or if the
 884          * operation is unidrectional, record the result of the operation and
 885          * schedule its completion.
 886          */
 887         if (message == operation->response) {
 888                 if (status) {
 889                         dev_err(&connection->hd->dev,
 890                                 "%s: error sending response 0x%02x: %d\n",
 891                                 connection->name, operation->type, status);
 892                 }
 893
 894                 gb_operation_put_active(operation);
 895                 gb_operation_put(operation);
 896         } else if (status || gb_operation_is_unidirectional(operation)) {
 897                 if (gb_operation_result_set(operation, status)) {
 898                         queue_work(gb_operation_completion_wq,
 899                                         &operation->work);
 900                 }
 901         }
 902 }
 903 EXPORT_SYMBOL_GPL(greybus_message_sent);
 904
 905 /*
 906  * We've received data on a connection, and it doesn't look like a
 907  * response, so we assume it's a request.
 908  *
 909  * This is called in interrupt context, so just copy the incoming
 910  * data into the request buffer and handle the rest via workqueue.
 911  */
 912 static void gb_connection_recv_request(struct gb_connection *connection,
 913                                 const struct gb_operation_msg_hdr *header,
 914                                 void *data, size_t size)
 915 {
 916         struct gb_operation *operation;
 917         u16 operation_id;
 918         u8 type;
 919         int ret;
 920
 921         operation_id = le16_to_cpu(header->operation_id);
 922         type = header->type;
 923
 924         operation = gb_operation_create_incoming(connection, operation_id,
 925                                                 type, data, size);
 926         if (!operation) {
 927                 dev_err(&connection->hd->dev,
 928                         "%s: can't create incoming operation\n",
 929                         connection->name);
 930                 return;
 931         }
 932
 933         ret = gb_operation_get_active(operation);
 934         if (ret) {
 935                 gb_operation_put(operation);
 936                 return;
 937         }
 938         trace_gb_message_recv_request(operation->request);
 939
 940         /*
 941          * The initial reference to the operation will be dropped when the
 942          * request handler returns.
 943          */
 944         if (gb_operation_result_set(operation, -EINPROGRESS))
 945                 queue_work(connection->wq, &operation->work);
 946 }
 947
 948 /*
 949  * We've received data that appears to be an operation response
 950  * message.  Look up the operation, and record that we've received
 951  * its response.
 952  *
 953  * This is called in interrupt context, so just copy the incoming
 954  * data into the response buffer and handle the rest via workqueue.
 955  */
 956 static void gb_connection_recv_response(struct gb_connection *connection,
 957                                 const struct gb_operation_msg_hdr *header,
 958                                 void *data, size_t size)
 959 {
 960         struct gb_operation *operation;
 961         struct gb_message *message;
 962         size_t message_size;
 963         u16 operation_id;
 964         int errno;
 965
 966         operation_id = le16_to_cpu(header->operation_id);
 967
 968         if (!operation_id) {
 969                 dev_err_ratelimited(&connection->hd->dev,
 970                                 "%s: invalid response id 0 received\n",
 971                                 connection->name);
 972                 return;
 973         }
 974
 975         operation = gb_operation_find_outgoing(connection, operation_id);
 976         if (!operation) {
 977                 dev_err_ratelimited(&connection->hd->dev,
 978                                 "%s: unexpected response id 0x%04x received\n",
 979                                 connection->name, operation_id);
 980                 return;
 981         }
 982
 983         errno = gb_operation_status_map(header->result);
 984         message = operation->response;
 985         message_size = sizeof(*header) + message->payload_size;
 986         if (!errno && size > message_size) {
 987                 dev_err_ratelimited(&connection->hd->dev,
 988                                 "%s: malformed response 0x%02x received (%zu > %zu)\n",
 989                                 connection->name, header->type,
 990                                 size, message_size);
 991                 errno = -EMSGSIZE;
 992         } else if (!errno && size < message_size) {
 993                 if (gb_operation_short_response_allowed(operation)) {
 994                         message->payload_size = size - sizeof(*header);
 995                 } else {
 996                         dev_err_ratelimited(&connection->hd->dev,
 997                                         "%s: short response 0x%02x received (%zu < %zu)\n",
 998                                         connection->name, header->type,
 999                                         size, message_size);
1000                         errno = -EMSGSIZE;
1001                 }
1002         }
1003
1004         /* We must ignore the payload if a bad status is returned */
1005         if (errno)
1006                 size = sizeof(*header);
1007
1008         /* The rest will be handled in work queue context */
1009         if (gb_operation_result_set(operation, errno)) {
1010                 memcpy(message->buffer, data, size);
1011
1012                 trace_gb_message_recv_response(message);
1013
1014                 queue_work(gb_operation_completion_wq, &operation->work);
1015         }
1016
1017         gb_operation_put(operation);
1018 }
1019
1020 /*
1021  * Handle data arriving on a connection.  As soon as we return the
1022  * supplied data buffer will be reused (so unless we do something
1023  * with, it's effectively dropped).
1024  */
1025 void gb_connection_recv(struct gb_connection *connection,
1026                                 void *data, size_t size)
1027 {
1028         struct gb_operation_msg_hdr header;
1029         struct device *dev = &connection->hd->dev;
1030         size_t msg_size;
1031
1032         if (connection->state == GB_CONNECTION_STATE_DISABLED ||
1033                         gb_connection_is_offloaded(connection)) {
1034                 dev_warn_ratelimited(dev, "%s: dropping %zu received bytes\n",
1035                                 connection->name, size);
1036                 return;
1037         }
1038
1039         if (size < sizeof(header)) {
1040                 dev_err_ratelimited(dev, "%s: short message received\n",
1041                                 connection->name);
1042                 return;
1043         }
1044
1045         /* Use memcpy as data may be unaligned */
1046         memcpy(&header, data, sizeof(header));
1047         msg_size = le16_to_cpu(header.size);
1048         if (size < msg_size) {
1049                 dev_err_ratelimited(dev,
1050                                 "%s: incomplete message 0x%04x of type 0x%02x received (%zu < %zu)\n",
1051                                 connection->name,
1052                                 le16_to_cpu(header.operation_id),
1053                                 header.type, size, msg_size);
1054                 return;         /* XXX Should still complete operation */
1055         }
1056
1057         if (header.type & GB_MESSAGE_TYPE_RESPONSE) {
1058                 gb_connection_recv_response(connection, &header, data,
1059                                                 msg_size);
1060         } else {
1061                 gb_connection_recv_request(connection, &header, data,
1062                                                 msg_size);
1063         }
1064 }
1065
1066 /*
1067  * Cancel an outgoing operation synchronously, and record the given error to
1068  * indicate why.
1069  */
1070 void gb_operation_cancel(struct gb_operation *operation, int errno)
1071 {
1072         if (WARN_ON(gb_operation_is_incoming(operation)))
1073                 return;
1074
1075         if (gb_operation_result_set(operation, errno)) {
1076                 gb_message_cancel(operation->request);
1077                 queue_work(gb_operation_completion_wq, &operation->work);
1078         }
1079         trace_gb_message_cancel_outgoing(operation->request);
1080
1081         atomic_inc(&operation->waiters);
1082         wait_event(gb_operation_cancellation_queue,
1083                         !gb_operation_is_active(operation));
1084         atomic_dec(&operation->waiters);
1085 }
1086 EXPORT_SYMBOL_GPL(gb_operation_cancel);
1087
1088 /*
1089  * Cancel an incoming operation synchronously. Called during connection tear
1090  * down.
1091  */
1092 void gb_operation_cancel_incoming(struct gb_operation *operation, int errno)
1093 {
1094         if (WARN_ON(!gb_operation_is_incoming(operation)))
1095                 return;
1096
1097         if (!gb_operation_is_unidirectional(operation)) {
1098                 /*
1099                  * Make sure the request handler has submitted the response
1100                  * before cancelling it.
1101                  */
1102                 flush_work(&operation->work);
1103                 if (!gb_operation_result_set(operation, errno))
1104                         gb_message_cancel(operation->response);
1105         }
1106         trace_gb_message_cancel_incoming(operation->response);
1107
1108         atomic_inc(&operation->waiters);
1109         wait_event(gb_operation_cancellation_queue,
1110                         !gb_operation_is_active(operation));
1111         atomic_dec(&operation->waiters);
1112 }
1113
1114 /**
1115  * gb_operation_sync_timeout() - implement a "simple" synchronous operation
1116  * @connection: the Greybus connection to send this to
1117  * @type: the type of operation to send
1118  * @request: pointer to a memory buffer to copy the request from
1119  * @request_size: size of @request
1120  * @response: pointer to a memory buffer to copy the response to
1121  * @response_size: the size of @response.
1122  * @timeout: operation timeout in milliseconds
1123  *
1124  * This function implements a simple synchronous Greybus operation.  It sends
1125  * the provided operation request and waits (sleeps) until the corresponding
1126  * operation response message has been successfully received, or an error
1127  * occurs.  @request and @response are buffers to hold the request and response
1128  * data respectively, and if they are not NULL, their size must be specified in
1129  * @request_size and @response_size.
1130  *
1131  * If a response payload is to come back, and @response is not NULL,
1132  * @response_size number of bytes will be copied into @response if the operation
1133  * is successful.
1134  *
1135  * If there is an error, the response buffer is left alone.
1136  */
1137 int gb_operation_sync_timeout(struct gb_connection *connection, int type,
1138                                 void *request, int request_size,
1139                                 void *response, int response_size,
1140                                 unsigned int timeout)
1141 {
1142         struct gb_operation *operation;
1143         int ret;
1144
1145         if ((response_size && !response) ||
1146             (request_size && !request))
1147                 return -EINVAL;
1148
1149         operation = gb_operation_create(connection, type,
1150                                         request_size, response_size,
1151                                         GFP_KERNEL);
1152         if (!operation)
1153                 return -ENOMEM;
1154
1155         if (request_size)
1156                 memcpy(operation->request->payload, request, request_size);
1157
1158         ret = gb_operation_request_send_sync_timeout(operation, timeout);
1159         if (ret) {
1160                 dev_err(&connection->hd->dev,
1161                         "%s: synchronous operation id 0x%04x of type 0x%02x failed: %d\n",
1162                         connection->name, operation->id, type, ret);
1163         } else {
1164                 if (response_size) {
1165                         memcpy(response, operation->response->payload,
1166                                response_size);
1167                 }
1168         }
1169
1170         gb_operation_put(operation);
1171
1172         return ret;
1173 }
1174 EXPORT_SYMBOL_GPL(gb_operation_sync_timeout);
1175
1176 /**
1177  * gb_operation_unidirectional_timeout() - initiate a unidirectional operation
1178  * @connection:         connection to use
1179  * @type:               type of operation to send
1180  * @request:            memory buffer to copy the request from
1181  * @request_size:       size of @request
1182  * @timeout:            send timeout in milliseconds
1183  *
1184  * Initiate a unidirectional operation by sending a request message and
1185  * waiting for it to be acknowledged as sent by the host device.
1186  *
1187  * Note that successful send of a unidirectional operation does not imply that
1188  * the request as actually reached the remote end of the connection.
1189  */
1190 int gb_operation_unidirectional_timeout(struct gb_connection *connection,
1191                                 int type, void *request, int request_size,
1192                                 unsigned int timeout)
1193 {
1194         struct gb_operation *operation;
1195         int ret;
1196
1197         if (request_size && !request)
1198                 return -EINVAL;
1199
1200         operation = gb_operation_create_flags(connection, type,
1201                                         request_size, 0,
1202                                         GB_OPERATION_FLAG_UNIDIRECTIONAL,
1203                                         GFP_KERNEL);
1204         if (!operation)
1205                 return -ENOMEM;
1206
1207         if (request_size)
1208                 memcpy(operation->request->payload, request, request_size);
1209
1210         ret = gb_operation_request_send_sync_timeout(operation, timeout);
1211         if (ret) {
1212                 dev_err(&connection->hd->dev,
1213                         "%s: unidirectional operation of type 0x%02x failed: %d\n",
1214                         connection->name, type, ret);
1215         }
1216
1217         gb_operation_put(operation);
1218
1219         return ret;
1220 }
1221 EXPORT_SYMBOL_GPL(gb_operation_unidirectional_timeout);
1222
1223 int __init gb_operation_init(void)
1224 {
1225         gb_message_cache = kmem_cache_create("gb_message_cache",
1226                                 sizeof(struct gb_message), 0, 0, NULL);
1227         if (!gb_message_cache)
1228                 return -ENOMEM;
1229
1230         gb_operation_cache = kmem_cache_create("gb_operation_cache",
1231                                 sizeof(struct gb_operation), 0, 0, NULL);
1232         if (!gb_operation_cache)
1233                 goto err_destroy_message_cache;
1234
1235         gb_operation_completion_wq = alloc_workqueue("greybus_completion",
1236                                 0, 0);
1237         if (!gb_operation_completion_wq)
1238                 goto err_destroy_operation_cache;
1239
1240         return 0;
1241
1242 err_destroy_operation_cache:
1243         kmem_cache_destroy(gb_operation_cache);
1244         gb_operation_cache = NULL;
1245 err_destroy_message_cache:
1246         kmem_cache_destroy(gb_message_cache);
1247         gb_message_cache = NULL;
1248
1249         return -ENOMEM;
1250 }
1251
1252 void gb_operation_exit(void)
1253 {
1254         destroy_workqueue(gb_operation_completion_wq);
1255         gb_operation_completion_wq = NULL;
1256         kmem_cache_destroy(gb_operation_cache);
1257         gb_operation_cache = NULL;
1258         kmem_cache_destroy(gb_message_cache);
1259         gb_message_cache = NULL;
1260 }