drivers/staging/greybus/operation.c

   1 /*
   2  * Greybus operations
   3  *
   4  * Copyright 2014-2015 Google Inc.
   5  * Copyright 2014-2015 Linaro Ltd.
   6  *
   7  * Released under the GPLv2 only.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <linux/wait.h>
  15 #include <linux/workqueue.h>
  16
  17 #include "greybus.h"
  18 #include "greybus_trace.h"
  19
  20 static struct kmem_cache *gb_operation_cache;
  21 static struct kmem_cache *gb_message_cache;
  22
  23 /* Workqueue to handle Greybus operation completions. */
  24 static struct workqueue_struct *gb_operation_completion_wq;
  25
  26 /* Wait queue for synchronous cancellations. */
  27 static DECLARE_WAIT_QUEUE_HEAD(gb_operation_cancellation_queue);
  28
  29 /*
  30  * Protects updates to operation->errno.
  31  */
  32 static DEFINE_SPINLOCK(gb_operations_lock);
  33
  34 static int gb_operation_response_send(struct gb_operation *operation,
  35                                         int errno);
  36
  37 /*
  38  * Increment operation active count and add to connection list unless the
  39  * connection is going away.
  40  *
  41  * Caller holds operation reference.
  42  */
  43 static int gb_operation_get_active(struct gb_operation *operation)
  44 {
  45         struct gb_connection *connection = operation->connection;
  46         unsigned long flags;
  47
  48         spin_lock_irqsave(&connection->lock, flags);
  49         switch (connection->state) {
  50         case GB_CONNECTION_STATE_ENABLED:
  51                 break;
  52         case GB_CONNECTION_STATE_ENABLED_TX:
  53                 if (gb_operation_is_incoming(operation))
  54                         goto err_unlock;
  55                 break;
  56         case GB_CONNECTION_STATE_DISCONNECTING:
  57                 if (!gb_operation_is_core(operation))
  58                         goto err_unlock;
  59                 break;
  60         default:
  61                 goto err_unlock;
  62         }
  63
  64         if (operation->active++ == 0)
  65                 list_add_tail(&operation->links, &connection->operations);
  66
  67         trace_gb_operation_get_active(operation);
  68
  69         spin_unlock_irqrestore(&connection->lock, flags);
  70
  71         return 0;
  72
  73 err_unlock:
  74         spin_unlock_irqrestore(&connection->lock, flags);
  75
  76         return -ENOTCONN;
  77 }
  78
  79 /* Caller holds operation reference. */
  80 static void gb_operation_put_active(struct gb_operation *operation)
  81 {
  82         struct gb_connection *connection = operation->connection;
  83         unsigned long flags;
  84
  85         spin_lock_irqsave(&connection->lock, flags);
  86
  87         trace_gb_operation_put_active(operation);
  88
  89         if (--operation->active == 0) {
  90                 list_del(&operation->links);
  91                 if (atomic_read(&operation->waiters))
  92                         wake_up(&gb_operation_cancellation_queue);
  93         }
  94         spin_unlock_irqrestore(&connection->lock, flags);
  95 }
  96
  97 static bool gb_operation_is_active(struct gb_operation *operation)
  98 {
  99         struct gb_connection *connection = operation->connection;
 100         unsigned long flags;
 101         bool ret;
 102
 103         spin_lock_irqsave(&connection->lock, flags);
 104         ret = operation->active;
 105         spin_unlock_irqrestore(&connection->lock, flags);
 106
 107         return ret;
 108 }
 109
 110 /*
 111  * Set an operation's result.
 112  *
 113  * Initially an outgoing operation's errno value is -EBADR.
 114  * If no error occurs before sending the request message the only
 115  * valid value operation->errno can be set to is -EINPROGRESS,
 116  * indicating the request has been (or rather is about to be) sent.
 117  * At that point nobody should be looking at the result until the
 118  * response arrives.
 119  *
 120  * The first time the result gets set after the request has been
 121  * sent, that result "sticks."  That is, if two concurrent threads
 122  * race to set the result, the first one wins.  The return value
 123  * tells the caller whether its result was recorded; if not the
 124  * caller has nothing more to do.
 125  *
 126  * The result value -EILSEQ is reserved to signal an implementation
 127  * error; if it's ever observed, the code performing the request has
 128  * done something fundamentally wrong.  It is an error to try to set
 129  * the result to -EBADR, and attempts to do so result in a warning,
 130  * and -EILSEQ is used instead.  Similarly, the only valid result
 131  * value to set for an operation in initial state is -EINPROGRESS.
 132  * Attempts to do otherwise will also record a (successful) -EILSEQ
 133  * operation result.
 134  */
 135 static bool gb_operation_result_set(struct gb_operation *operation, int result)
 136 {
 137         unsigned long flags;
 138         int prev;
 139
 140         if (result == -EINPROGRESS) {
 141                 /*
 142                  * -EINPROGRESS is used to indicate the request is
 143                  * in flight.  It should be the first result value
 144                  * set after the initial -EBADR.  Issue a warning
 145                  * and record an implementation error if it's
 146                  * set at any other time.
 147                  */
 148                 spin_lock_irqsave(&gb_operations_lock, flags);
 149                 prev = operation->errno;
 150                 if (prev == -EBADR)
 151                         operation->errno = result;
 152                 else
 153                         operation->errno = -EILSEQ;
 154                 spin_unlock_irqrestore(&gb_operations_lock, flags);
 155                 WARN_ON(prev != -EBADR);
 156
 157                 return true;
 158         }
 159
 160         /*
 161          * The first result value set after a request has been sent
 162          * will be the final result of the operation.  Subsequent
 163          * attempts to set the result are ignored.
 164          *
 165          * Note that -EBADR is a reserved "initial state" result
 166          * value.  Attempts to set this value result in a warning,
 167          * and the result code is set to -EILSEQ instead.
 168          */
 169         if (WARN_ON(result == -EBADR))
 170                 result = -EILSEQ; /* Nobody should be setting -EBADR */
 171
 172         spin_lock_irqsave(&gb_operations_lock, flags);
 173         prev = operation->errno;
 174         if (prev == -EINPROGRESS)
 175                 operation->errno = result;      /* First and final result */
 176         spin_unlock_irqrestore(&gb_operations_lock, flags);
 177
 178         return prev == -EINPROGRESS;
 179 }
 180
 181 int gb_operation_result(struct gb_operation *operation)
 182 {
 183         int result = operation->errno;
 184
 185         WARN_ON(result == -EBADR);
 186         WARN_ON(result == -EINPROGRESS);
 187
 188         return result;
 189 }
 190 EXPORT_SYMBOL_GPL(gb_operation_result);
 191
 192 /*
 193  * Looks up an outgoing operation on a connection and returns a refcounted
 194  * pointer if found, or NULL otherwise.
 195  */
 196 static struct gb_operation *
 197 gb_operation_find_outgoing(struct gb_connection *connection, u16 operation_id)
 198 {
 199         struct gb_operation *operation;
 200         unsigned long flags;
 201         bool found = false;
 202
 203         spin_lock_irqsave(&connection->lock, flags);
 204         list_for_each_entry(operation, &connection->operations, links)
 205                 if (operation->id == operation_id &&
 206                                 !gb_operation_is_incoming(operation)) {
 207                         gb_operation_get(operation);
 208                         found = true;
 209                         break;
 210                 }
 211         spin_unlock_irqrestore(&connection->lock, flags);
 212
 213         return found ? operation : NULL;
 214 }
 215
 216 static int gb_message_send(struct gb_message *message, gfp_t gfp)
 217 {
 218         struct gb_connection *connection = message->operation->connection;
 219
 220         trace_gb_message_send(message);
 221         return connection->hd->driver->message_send(connection->hd,
 222                                         connection->hd_cport_id,
 223                                         message,
 224                                         gfp);
 225 }
 226
 227 /*
 228  * Cancel a message we have passed to the host device layer to be sent.
 229  */
 230 static void gb_message_cancel(struct gb_message *message)
 231 {
 232         struct gb_host_device *hd = message->operation->connection->hd;
 233
 234         hd->driver->message_cancel(message);
 235 }
 236
 237 static void gb_operation_request_handle(struct gb_operation *operation)
 238 {
 239         struct gb_connection *connection = operation->connection;
 240         int status;
 241         int ret;
 242
 243         if (connection->handler) {
 244                 status = connection->handler(operation);
 245         } else {
 246                 dev_err(&connection->hd->dev,
 247                         "%s: unexpected incoming request of type 0x%02x\n",
 248                         connection->name, operation->type);
 249
 250                 status = -EPROTONOSUPPORT;
 251         }
 252
 253         ret = gb_operation_response_send(operation, status);
 254         if (ret) {
 255                 dev_err(&connection->hd->dev,
 256                         "%s: failed to send response %d for type 0x%02x: %d\n",
 257                         connection->name, status, operation->type, ret);
 258                 return;
 259         }
 260 }
 261
 262 /*
 263  * Process operation work.
 264  *
 265  * For incoming requests, call the protocol request handler. The operation
 266  * result should be -EINPROGRESS at this point.
 267  *
 268  * For outgoing requests, the operation result value should have
 269  * been set before queueing this.  The operation callback function
 270  * allows the original requester to know the request has completed
 271  * and its result is available.
 272  */
 273 static void gb_operation_work(struct work_struct *work)
 274 {
 275         struct gb_operation *operation;
 276         int ret;
 277
 278         operation = container_of(work, struct gb_operation, work);
 279
 280         if (gb_operation_is_incoming(operation)) {
 281                 gb_operation_request_handle(operation);
 282         } else {
 283                 ret = del_timer_sync(&operation->timer);
 284                 if (!ret) {
 285                         /* Cancel request message if scheduled by timeout. */
 286                         if (gb_operation_result(operation) == -ETIMEDOUT)
 287                                 gb_message_cancel(operation->request);
 288                 }
 289
 290                 operation->callback(operation);
 291         }
 292
 293         gb_operation_put_active(operation);
 294         gb_operation_put(operation);
 295 }
 296
 297 static void gb_operation_timeout(unsigned long arg)
 298 {
 299         struct gb_operation *operation = (void *)arg;
 300
 301         if (gb_operation_result_set(operation, -ETIMEDOUT)) {
 302                 /*
 303                  * A stuck request message will be cancelled from the
 304                  * workqueue.
 305                  */
 306                 queue_work(gb_operation_completion_wq, &operation->work);
 307         }
 308 }
 309
 310 static void gb_operation_message_init(struct gb_host_device *hd,
 311                                 struct gb_message *message, u16 operation_id,
 312                                 size_t payload_size, u8 type)
 313 {
 314         struct gb_operation_msg_hdr *header;
 315
 316         header = message->buffer;
 317
 318         message->header = header;
 319         message->payload = payload_size ? header + 1 : NULL;
 320         message->payload_size = payload_size;
 321
 322         /*
 323          * The type supplied for incoming message buffers will be
 324          * GB_REQUEST_TYPE_INVALID. Such buffers will be overwritten by
 325          * arriving data so there's no need to initialize the message header.
 326          */
 327         if (type != GB_REQUEST_TYPE_INVALID) {
 328                 u16 message_size = (u16)(sizeof(*header) + payload_size);
 329
 330                 /*
 331                  * For a request, the operation id gets filled in
 332                  * when the message is sent.  For a response, it
 333                  * will be copied from the request by the caller.
 334                  *
 335                  * The result field in a request message must be
 336                  * zero.  It will be set just prior to sending for
 337                  * a response.
 338                  */
 339                 header->size = cpu_to_le16(message_size);
 340                 header->operation_id = 0;
 341                 header->type = type;
 342                 header->result = 0;
 343         }
 344 }
 345
 346 /*
 347  * Allocate a message to be used for an operation request or response.
 348  * Both types of message contain a common header.  The request message
 349  * for an outgoing operation is outbound, as is the response message
 350  * for an incoming operation.  The message header for an outbound
 351  * message is partially initialized here.
 352  *
 353  * The headers for inbound messages don't need to be initialized;
 354  * they'll be filled in by arriving data.
 355  *
 356  * Our message buffers have the following layout:
 357  *      message header  \_ these combined are
 358  *      message payload /  the message size
 359  */
 360 static struct gb_message *
 361 gb_operation_message_alloc(struct gb_host_device *hd, u8 type,
 362                                 size_t payload_size, gfp_t gfp_flags)
 363 {
 364         struct gb_message *message;
 365         struct gb_operation_msg_hdr *header;
 366         size_t message_size = payload_size + sizeof(*header);
 367
 368         if (message_size > hd->buffer_size_max) {
 369                 dev_warn(&hd->dev, "requested message size too big (%zu > %zu)\n",
 370                                 message_size, hd->buffer_size_max);
 371                 return NULL;
 372         }
 373
 374         /* Allocate the message structure and buffer. */
 375         message = kmem_cache_zalloc(gb_message_cache, gfp_flags);
 376         if (!message)
 377                 return NULL;
 378
 379         message->buffer = kzalloc(message_size, gfp_flags);
 380         if (!message->buffer)
 381                 goto err_free_message;
 382
 383         /* Initialize the message.  Operation id is filled in later. */
 384         gb_operation_message_init(hd, message, 0, payload_size, type);
 385
 386         return message;
 387
 388 err_free_message:
 389         kmem_cache_free(gb_message_cache, message);
 390
 391         return NULL;
 392 }
 393
 394 static void gb_operation_message_free(struct gb_message *message)
 395 {
 396         kfree(message->buffer);
 397         kmem_cache_free(gb_message_cache, message);
 398 }
 399
 400 /*
 401  * Map an enum gb_operation_status value (which is represented in a
 402  * message as a single byte) to an appropriate Linux negative errno.
 403  */
 404 static int gb_operation_status_map(u8 status)
 405 {
 406         switch (status) {
 407         case GB_OP_SUCCESS:
 408                 return 0;
 409         case GB_OP_INTERRUPTED:
 410                 return -EINTR;
 411         case GB_OP_TIMEOUT:
 412                 return -ETIMEDOUT;
 413         case GB_OP_NO_MEMORY:
 414                 return -ENOMEM;
 415         case GB_OP_PROTOCOL_BAD:
 416                 return -EPROTONOSUPPORT;
 417         case GB_OP_OVERFLOW:
 418                 return -EMSGSIZE;
 419         case GB_OP_INVALID:
 420                 return -EINVAL;
 421         case GB_OP_RETRY:
 422                 return -EAGAIN;
 423         case GB_OP_NONEXISTENT:
 424                 return -ENODEV;
 425         case GB_OP_MALFUNCTION:
 426                 return -EILSEQ;
 427         case GB_OP_UNKNOWN_ERROR:
 428         default:
 429                 return -EIO;
 430         }
 431 }
 432
 433 /*
 434  * Map a Linux errno value (from operation->errno) into the value
 435  * that should represent it in a response message status sent
 436  * over the wire.  Returns an enum gb_operation_status value (which
 437  * is represented in a message as a single byte).
 438  */
 439 static u8 gb_operation_errno_map(int errno)
 440 {
 441         switch (errno) {
 442         case 0:
 443                 return GB_OP_SUCCESS;
 444         case -EINTR:
 445                 return GB_OP_INTERRUPTED;
 446         case -ETIMEDOUT:
 447                 return GB_OP_TIMEOUT;
 448         case -ENOMEM:
 449                 return GB_OP_NO_MEMORY;
 450         case -EPROTONOSUPPORT:
 451                 return GB_OP_PROTOCOL_BAD;
 452         case -EMSGSIZE:
 453                 return GB_OP_OVERFLOW;  /* Could be underflow too */
 454         case -EINVAL:
 455                 return GB_OP_INVALID;
 456         case -EAGAIN:
 457                 return GB_OP_RETRY;
 458         case -EILSEQ:
 459                 return GB_OP_MALFUNCTION;
 460         case -ENODEV:
 461                 return GB_OP_NONEXISTENT;
 462         case -EIO:
 463         default:
 464                 return GB_OP_UNKNOWN_ERROR;
 465         }
 466 }
 467
 468 bool gb_operation_response_alloc(struct gb_operation *operation,
 469                                         size_t response_size, gfp_t gfp)
 470 {
 471         struct gb_host_device *hd = operation->connection->hd;
 472         struct gb_operation_msg_hdr *request_header;
 473         struct gb_message *response;
 474         u8 type;
 475
 476         type = operation->type | GB_MESSAGE_TYPE_RESPONSE;
 477         response = gb_operation_message_alloc(hd, type, response_size, gfp);
 478         if (!response)
 479                 return false;
 480         response->operation = operation;
 481
 482         /*
 483          * Size and type get initialized when the message is
 484          * allocated.  The errno will be set before sending.  All
 485          * that's left is the operation id, which we copy from the
 486          * request message header (as-is, in little-endian order).
 487          */
 488         request_header = operation->request->header;
 489         response->header->operation_id = request_header->operation_id;
 490         operation->response = response;
 491
 492         return true;
 493 }
 494 EXPORT_SYMBOL_GPL(gb_operation_response_alloc);
 495
 496 /*
 497  * Create a Greybus operation to be sent over the given connection.
 498  * The request buffer will be big enough for a payload of the given
 499  * size.
 500  *
 501  * For outgoing requests, the request message's header will be
 502  * initialized with the type of the request and the message size.
 503  * Outgoing operations must also specify the response buffer size,
 504  * which must be sufficient to hold all expected response data.  The
 505  * response message header will eventually be overwritten, so there's
 506  * no need to initialize it here.
 507  *
 508  * Request messages for incoming operations can arrive in interrupt
 509  * context, so they must be allocated with GFP_ATOMIC.  In this case
 510  * the request buffer will be immediately overwritten, so there is
 511  * no need to initialize the message header.  Responsibility for
 512  * allocating a response buffer lies with the incoming request
 513  * handler for a protocol.  So we don't allocate that here.
 514  *
 515  * Returns a pointer to the new operation or a null pointer if an
 516  * error occurs.
 517  */
 518 static struct gb_operation *
 519 gb_operation_create_common(struct gb_connection *connection, u8 type,
 520                                 size_t request_size, size_t response_size,
 521                                 unsigned long op_flags, gfp_t gfp_flags)
 522 {
 523         struct gb_host_device *hd = connection->hd;
 524         struct gb_operation *operation;
 525
 526         operation = kmem_cache_zalloc(gb_operation_cache, gfp_flags);
 527         if (!operation)
 528                 return NULL;
 529         operation->connection = connection;
 530
 531         operation->request = gb_operation_message_alloc(hd, type, request_size,
 532                                                         gfp_flags);
 533         if (!operation->request)
 534                 goto err_cache;
 535         operation->request->operation = operation;
 536
 537         /* Allocate the response buffer for outgoing operations */
 538         if (!(op_flags & GB_OPERATION_FLAG_INCOMING)) {
 539                 if (!gb_operation_response_alloc(operation, response_size,
 540                                                  gfp_flags)) {
 541                         goto err_request;
 542                 }
 543
 544                 setup_timer(&operation->timer, gb_operation_timeout,
 545                             (unsigned long)operation);
 546         }
 547
 548         operation->flags = op_flags;
 549         operation->type = type;
 550         operation->errno = -EBADR;  /* Initial value--means "never set" */
 551
 552         INIT_WORK(&operation->work, gb_operation_work);
 553         init_completion(&operation->completion);
 554         kref_init(&operation->kref);
 555         atomic_set(&operation->waiters, 0);
 556
 557         return operation;
 558
 559 err_request:
 560         gb_operation_message_free(operation->request);
 561 err_cache:
 562         kmem_cache_free(gb_operation_cache, operation);
 563
 564         return NULL;
 565 }
 566
 567 /*
 568  * Create a new operation associated with the given connection.  The
 569  * request and response sizes provided are the number of bytes
 570  * required to hold the request/response payload only.  Both of
 571  * these are allowed to be 0.  Note that 0x00 is reserved as an
 572  * invalid operation type for all protocols, and this is enforced
 573  * here.
 574  */
 575 struct gb_operation *
 576 gb_operation_create_flags(struct gb_connection *connection,
 577                                 u8 type, size_t request_size,
 578                                 size_t response_size, unsigned long flags,
 579                                 gfp_t gfp)
 580 {
 581         struct gb_operation *operation;
 582
 583         if (WARN_ON_ONCE(type == GB_REQUEST_TYPE_INVALID))
 584                 return NULL;
 585         if (WARN_ON_ONCE(type & GB_MESSAGE_TYPE_RESPONSE))
 586                 type &= ~GB_MESSAGE_TYPE_RESPONSE;
 587
 588         if (WARN_ON_ONCE(flags & ~GB_OPERATION_FLAG_USER_MASK))
 589                 flags &= GB_OPERATION_FLAG_USER_MASK;
 590
 591         operation = gb_operation_create_common(connection, type,
 592                                                 request_size, response_size,
 593                                                 flags, gfp);
 594         if (operation)
 595                 trace_gb_operation_create(operation);
 596
 597         return operation;
 598 }
 599 EXPORT_SYMBOL_GPL(gb_operation_create_flags);
 600
 601 struct gb_operation *
 602 gb_operation_create_core(struct gb_connection *connection,
 603                                 u8 type, size_t request_size,
 604                                 size_t response_size, unsigned long flags,
 605                                 gfp_t gfp)
 606 {
 607         struct gb_operation *operation;
 608
 609         flags |= GB_OPERATION_FLAG_CORE;
 610
 611         operation = gb_operation_create_common(connection, type,
 612                                                 request_size, response_size,
 613                                                 flags, gfp);
 614         if (operation)
 615                 trace_gb_operation_create_core(operation);
 616
 617         return operation;
 618 }
 619 /* Do not export this function. */
 620
 621 size_t gb_operation_get_payload_size_max(struct gb_connection *connection)
 622 {
 623         struct gb_host_device *hd = connection->hd;
 624
 625         return hd->buffer_size_max - sizeof(struct gb_operation_msg_hdr);
 626 }
 627 EXPORT_SYMBOL_GPL(gb_operation_get_payload_size_max);
 628
 629 static struct gb_operation *
 630 gb_operation_create_incoming(struct gb_connection *connection, u16 id,
 631                                 u8 type, void *data, size_t size)
 632 {
 633         struct gb_operation *operation;
 634         size_t request_size;
 635         unsigned long flags = GB_OPERATION_FLAG_INCOMING;
 636
 637         /* Caller has made sure we at least have a message header. */
 638         request_size = size - sizeof(struct gb_operation_msg_hdr);
 639
 640         if (!id)
 641                 flags |= GB_OPERATION_FLAG_UNIDIRECTIONAL;
 642
 643         operation = gb_operation_create_common(connection, type,
 644                                                 request_size,
 645                                                 GB_REQUEST_TYPE_INVALID,
 646                                                 flags, GFP_ATOMIC);
 647         if (!operation)
 648                 return NULL;
 649
 650         operation->id = id;
 651         memcpy(operation->request->header, data, size);
 652         trace_gb_operation_create_incoming(operation);
 653
 654         return operation;
 655 }
 656
 657 /*
 658  * Get an additional reference on an operation.
 659  */
 660 void gb_operation_get(struct gb_operation *operation)
 661 {
 662         kref_get(&operation->kref);
 663 }
 664 EXPORT_SYMBOL_GPL(gb_operation_get);
 665
 666 /*
 667  * Destroy a previously created operation.
 668  */
 669 static void _gb_operation_destroy(struct kref *kref)
 670 {
 671         struct gb_operation *operation;
 672
 673         operation = container_of(kref, struct gb_operation, kref);
 674
 675         trace_gb_operation_destroy(operation);
 676
 677         if (operation->response)
 678                 gb_operation_message_free(operation->response);
 679         gb_operation_message_free(operation->request);
 680
 681         kmem_cache_free(gb_operation_cache, operation);
 682 }
 683
 684 /*
 685  * Drop a reference on an operation, and destroy it when the last
 686  * one is gone.
 687  */
 688 void gb_operation_put(struct gb_operation *operation)
 689 {
 690         if (WARN_ON(!operation))
 691                 return;
 692
 693         kref_put(&operation->kref, _gb_operation_destroy);
 694 }
 695 EXPORT_SYMBOL_GPL(gb_operation_put);
 696
 697 /* Tell the requester we're done */
 698 static void gb_operation_sync_callback(struct gb_operation *operation)
 699 {
 700         complete(&operation->completion);
 701 }
 702
 703 /**
 704  * gb_operation_request_send() - send an operation request message
 705  * @operation:  the operation to initiate
 706  * @callback:   the operation completion callback
 707  * @timeout:    operation timeout in milliseconds, or zero for no timeout
 708  * @gfp:        the memory flags to use for any allocations
 709  *
 710  * The caller has filled in any payload so the request message is ready to go.
 711  * The callback function supplied will be called when the response message has
 712  * arrived, a unidirectional request has been sent, or the operation is
 713  * cancelled, indicating that the operation is complete. The callback function
 714  * can fetch the result of the operation using gb_operation_result() if
 715  * desired.
 716  *
 717  * Return: 0 if the request was successfully queued in the host-driver queues,
 718  * or a negative errno.
 719  */
 720 int gb_operation_request_send(struct gb_operation *operation,
 721                                 gb_operation_callback callback,
 722                                 unsigned int timeout,
 723                                 gfp_t gfp)
 724 {
 725         struct gb_connection *connection = operation->connection;
 726         struct gb_operation_msg_hdr *header;
 727         unsigned int cycle;
 728         int ret;
 729
 730         if (gb_connection_is_offloaded(connection))
 731                 return -EBUSY;
 732
 733         if (!callback)
 734                 return -EINVAL;
 735
 736         /*
 737          * Record the callback function, which is executed in
 738          * non-atomic (workqueue) context when the final result
 739          * of an operation has been set.
 740          */
 741         operation->callback = callback;
 742
 743         /*
 744          * Assign the operation's id, and store it in the request header.
 745          * Zero is a reserved operation id for unidirectional operations.
 746          */
 747         if (gb_operation_is_unidirectional(operation)) {
 748                 operation->id = 0;
 749         } else {
 750                 cycle = (unsigned int)atomic_inc_return(&connection->op_cycle);
 751                 operation->id = (u16)(cycle % U16_MAX + 1);
 752         }
 753
 754         header = operation->request->header;
 755         header->operation_id = cpu_to_le16(operation->id);
 756
 757         gb_operation_result_set(operation, -EINPROGRESS);
 758
 759         /*
 760          * Get an extra reference on the operation. It'll be dropped when the
 761          * operation completes.
 762          */
 763         gb_operation_get(operation);
 764         ret = gb_operation_get_active(operation);
 765         if (ret)
 766                 goto err_put;
 767
 768         ret = gb_message_send(operation->request, gfp);
 769         if (ret)
 770                 goto err_put_active;
 771
 772         if (timeout) {
 773                 operation->timer.expires = jiffies + msecs_to_jiffies(timeout);
 774                 add_timer(&operation->timer);
 775         }
 776
 777         return 0;
 778
 779 err_put_active:
 780         gb_operation_put_active(operation);
 781 err_put:
 782         gb_operation_put(operation);
 783
 784         return ret;
 785 }
 786 EXPORT_SYMBOL_GPL(gb_operation_request_send);
 787
 788 /*
 789  * Send a synchronous operation.  This function is expected to
 790  * block, returning only when the response has arrived, (or when an
 791  * error is detected.  The return value is the result of the
 792  * operation.
 793  */
 794 int gb_operation_request_send_sync_timeout(struct gb_operation *operation,
 795                                                 unsigned int timeout)
 796 {
 797         int ret;
 798
 799         ret = gb_operation_request_send(operation, gb_operation_sync_callback,
 800                                         timeout, GFP_KERNEL);
 801         if (ret)
 802                 return ret;
 803
 804         ret = wait_for_completion_interruptible(&operation->completion);
 805         if (ret < 0) {
 806                 /* Cancel the operation if interrupted */
 807                 gb_operation_cancel(operation, -ECANCELED);
 808         }
 809
 810         return gb_operation_result(operation);
 811 }
 812 EXPORT_SYMBOL_GPL(gb_operation_request_send_sync_timeout);
 813
 814 /*
 815  * Send a response for an incoming operation request.  A non-zero
 816  * errno indicates a failed operation.
 817  *
 818  * If there is any response payload, the incoming request handler is
 819  * responsible for allocating the response message.  Otherwise the
 820  * it can simply supply the result errno; this function will
 821  * allocate the response message if necessary.
 822  */
 823 static int gb_operation_response_send(struct gb_operation *operation,
 824                                         int errno)
 825 {
 826         struct gb_connection *connection = operation->connection;
 827         int ret;
 828
 829         if (!operation->response &&
 830                         !gb_operation_is_unidirectional(operation)) {
 831                 if (!gb_operation_response_alloc(operation, 0, GFP_KERNEL))
 832                         return -ENOMEM;
 833         }
 834
 835         /* Record the result */
 836         if (!gb_operation_result_set(operation, errno)) {
 837                 dev_err(&connection->hd->dev, "request result already set\n");
 838                 return -EIO;    /* Shouldn't happen */
 839         }
 840
 841         /* Sender of request does not care about response. */
 842         if (gb_operation_is_unidirectional(operation))
 843                 return 0;
 844
 845         /* Reference will be dropped when message has been sent. */
 846         gb_operation_get(operation);
 847         ret = gb_operation_get_active(operation);
 848         if (ret)
 849                 goto err_put;
 850
 851         /* Fill in the response header and send it */
 852         operation->response->header->result = gb_operation_errno_map(errno);
 853
 854         ret = gb_message_send(operation->response, GFP_KERNEL);
 855         if (ret)
 856                 goto err_put_active;
 857
 858         return 0;
 859
 860 err_put_active:
 861         gb_operation_put_active(operation);
 862 err_put:
 863         gb_operation_put(operation);
 864
 865         return ret;
 866 }
 867
 868 /*
 869  * This function is called when a message send request has completed.
 870  */
 871 void greybus_message_sent(struct gb_host_device *hd,
 872                                         struct gb_message *message, int status)
 873 {
 874         struct gb_operation *operation = message->operation;
 875         struct gb_connection *connection = operation->connection;
 876
 877         /*
 878          * If the message was a response, we just need to drop our
 879          * reference to the operation.  If an error occurred, report
 880          * it.
 881          *
 882          * For requests, if there's no error and the operation in not
 883          * unidirectional, there's nothing more to do until the response
 884          * arrives. If an error occurred attempting to send it, or if the
 885          * operation is unidrectional, record the result of the operation and
 886          * schedule its completion.
 887          */
 888         if (message == operation->response) {
 889                 if (status) {
 890                         dev_err(&connection->hd->dev,
 891                                 "%s: error sending response 0x%02x: %d\n",
 892                                 connection->name, operation->type, status);
 893                 }
 894
 895                 gb_operation_put_active(operation);
 896                 gb_operation_put(operation);
 897         } else if (status || gb_operation_is_unidirectional(operation)) {
 898                 if (gb_operation_result_set(operation, status)) {
 899                         queue_work(gb_operation_completion_wq,
 900                                         &operation->work);
 901                 }
 902         }
 903 }
 904 EXPORT_SYMBOL_GPL(greybus_message_sent);
 905
 906 /*
 907  * We've received data on a connection, and it doesn't look like a
 908  * response, so we assume it's a request.
 909  *
 910  * This is called in interrupt context, so just copy the incoming
 911  * data into the request buffer and handle the rest via workqueue.
 912  */
 913 static void gb_connection_recv_request(struct gb_connection *connection,
 914                                 const struct gb_operation_msg_hdr *header,
 915                                 void *data, size_t size)
 916 {
 917         struct gb_operation *operation;
 918         u16 operation_id;
 919         u8 type;
 920         int ret;
 921
 922         operation_id = le16_to_cpu(header->operation_id);
 923         type = header->type;
 924
 925         operation = gb_operation_create_incoming(connection, operation_id,
 926                                                 type, data, size);
 927         if (!operation) {
 928                 dev_err(&connection->hd->dev,
 929                         "%s: can't create incoming operation\n",
 930                         connection->name);
 931                 return;
 932         }
 933
 934         ret = gb_operation_get_active(operation);
 935         if (ret) {
 936                 gb_operation_put(operation);
 937                 return;
 938         }
 939         trace_gb_message_recv_request(operation->request);
 940
 941         /*
 942          * The initial reference to the operation will be dropped when the
 943          * request handler returns.
 944          */
 945         if (gb_operation_result_set(operation, -EINPROGRESS))
 946                 queue_work(connection->wq, &operation->work);
 947 }
 948
 949 /*
 950  * We've received data that appears to be an operation response
 951  * message.  Look up the operation, and record that we've received
 952  * its response.
 953  *
 954  * This is called in interrupt context, so just copy the incoming
 955  * data into the response buffer and handle the rest via workqueue.
 956  */
 957 static void gb_connection_recv_response(struct gb_connection *connection,
 958                                 const struct gb_operation_msg_hdr *header,
 959                                 void *data, size_t size)
 960 {
 961         struct gb_operation *operation;
 962         struct gb_message *message;
 963         size_t message_size;
 964         u16 operation_id;
 965         int errno;
 966
 967         operation_id = le16_to_cpu(header->operation_id);
 968
 969         if (!operation_id) {
 970                 dev_err_ratelimited(&connection->hd->dev,
 971                                 "%s: invalid response id 0 received\n",
 972                                 connection->name);
 973                 return;
 974         }
 975
 976         operation = gb_operation_find_outgoing(connection, operation_id);
 977         if (!operation) {
 978                 dev_err_ratelimited(&connection->hd->dev,
 979                                 "%s: unexpected response id 0x%04x received\n",
 980                                 connection->name, operation_id);
 981                 return;
 982         }
 983
 984         errno = gb_operation_status_map(header->result);
 985         message = operation->response;
 986         message_size = sizeof(*header) + message->payload_size;
 987         if (!errno && size > message_size) {
 988                 dev_err_ratelimited(&connection->hd->dev,
 989                                 "%s: malformed response 0x%02x received (%zu > %zu)\n",
 990                                 connection->name, header->type,
 991                                 size, message_size);
 992                 errno = -EMSGSIZE;
 993         } else if (!errno && size < message_size) {
 994                 if (gb_operation_short_response_allowed(operation)) {
 995                         message->payload_size = size - sizeof(*header);
 996                 } else {
 997                         dev_err_ratelimited(&connection->hd->dev,
 998                                         "%s: short response 0x%02x received (%zu < %zu)\n",
 999                                         connection->name, header->type,
1000                                         size, message_size);
1001                         errno = -EMSGSIZE;
1002                 }
1003         }
1004
1005         /* We must ignore the payload if a bad status is returned */
1006         if (errno)
1007                 size = sizeof(*header);
1008
1009         /* The rest will be handled in work queue context */
1010         if (gb_operation_result_set(operation, errno)) {
1011                 memcpy(message->buffer, data, size);
1012
1013                 trace_gb_message_recv_response(message);
1014
1015                 queue_work(gb_operation_completion_wq, &operation->work);
1016         }
1017
1018         gb_operation_put(operation);
1019 }
1020
1021 /*
1022  * Handle data arriving on a connection.  As soon as we return the
1023  * supplied data buffer will be reused (so unless we do something
1024  * with, it's effectively dropped).
1025  */
1026 void gb_connection_recv(struct gb_connection *connection,
1027                                 void *data, size_t size)
1028 {
1029         struct gb_operation_msg_hdr header;
1030         struct device *dev = &connection->hd->dev;
1031         size_t msg_size;
1032
1033         if (connection->state == GB_CONNECTION_STATE_DISABLED ||
1034                         gb_connection_is_offloaded(connection)) {
1035                 dev_warn_ratelimited(dev, "%s: dropping %zu received bytes\n",
1036                                 connection->name, size);
1037                 return;
1038         }
1039
1040         if (size < sizeof(header)) {
1041                 dev_err_ratelimited(dev, "%s: short message received\n",
1042                                 connection->name);
1043                 return;
1044         }
1045
1046         /* Use memcpy as data may be unaligned */
1047         memcpy(&header, data, sizeof(header));
1048         msg_size = le16_to_cpu(header.size);
1049         if (size < msg_size) {
1050                 dev_err_ratelimited(dev,
1051                                 "%s: incomplete message 0x%04x of type 0x%02x received (%zu < %zu)\n",
1052                                 connection->name,
1053                                 le16_to_cpu(header.operation_id),
1054                                 header.type, size, msg_size);
1055                 return;         /* XXX Should still complete operation */
1056         }
1057
1058         if (header.type & GB_MESSAGE_TYPE_RESPONSE) {
1059                 gb_connection_recv_response(connection, &header, data,
1060                                                 msg_size);
1061         } else {
1062                 gb_connection_recv_request(connection, &header, data,
1063                                                 msg_size);
1064         }
1065 }
1066
1067 /*
1068  * Cancel an outgoing operation synchronously, and record the given error to
1069  * indicate why.
1070  */
1071 void gb_operation_cancel(struct gb_operation *operation, int errno)
1072 {
1073         if (WARN_ON(gb_operation_is_incoming(operation)))
1074                 return;
1075
1076         if (gb_operation_result_set(operation, errno)) {
1077                 gb_message_cancel(operation->request);
1078                 queue_work(gb_operation_completion_wq, &operation->work);
1079         }
1080         trace_gb_message_cancel_outgoing(operation->request);
1081
1082         atomic_inc(&operation->waiters);
1083         wait_event(gb_operation_cancellation_queue,
1084                         !gb_operation_is_active(operation));
1085         atomic_dec(&operation->waiters);
1086 }
1087 EXPORT_SYMBOL_GPL(gb_operation_cancel);
1088
1089 /*
1090  * Cancel an incoming operation synchronously. Called during connection tear
1091  * down.
1092  */
1093 void gb_operation_cancel_incoming(struct gb_operation *operation, int errno)
1094 {
1095         if (WARN_ON(!gb_operation_is_incoming(operation)))
1096                 return;
1097
1098         if (!gb_operation_is_unidirectional(operation)) {
1099                 /*
1100                  * Make sure the request handler has submitted the response
1101                  * before cancelling it.
1102                  */
1103                 flush_work(&operation->work);
1104                 if (!gb_operation_result_set(operation, errno))
1105                         gb_message_cancel(operation->response);
1106         }
1107         trace_gb_message_cancel_incoming(operation->response);
1108
1109         atomic_inc(&operation->waiters);
1110         wait_event(gb_operation_cancellation_queue,
1111                         !gb_operation_is_active(operation));
1112         atomic_dec(&operation->waiters);
1113 }
1114
1115 /**
1116  * gb_operation_sync_timeout() - implement a "simple" synchronous operation
1117  * @connection: the Greybus connection to send this to
1118  * @type: the type of operation to send
1119  * @request: pointer to a memory buffer to copy the request from
1120  * @request_size: size of @request
1121  * @response: pointer to a memory buffer to copy the response to
1122  * @response_size: the size of @response.
1123  * @timeout: operation timeout in milliseconds
1124  *
1125  * This function implements a simple synchronous Greybus operation.  It sends
1126  * the provided operation request and waits (sleeps) until the corresponding
1127  * operation response message has been successfully received, or an error
1128  * occurs.  @request and @response are buffers to hold the request and response
1129  * data respectively, and if they are not NULL, their size must be specified in
1130  * @request_size and @response_size.
1131  *
1132  * If a response payload is to come back, and @response is not NULL,
1133  * @response_size number of bytes will be copied into @response if the operation
1134  * is successful.
1135  *
1136  * If there is an error, the response buffer is left alone.
1137  */
1138 int gb_operation_sync_timeout(struct gb_connection *connection, int type,
1139                                 void *request, int request_size,
1140                                 void *response, int response_size,
1141                                 unsigned int timeout)
1142 {
1143         struct gb_operation *operation;
1144         int ret;
1145
1146         if ((response_size && !response) ||
1147             (request_size && !request))
1148                 return -EINVAL;
1149
1150         operation = gb_operation_create(connection, type,
1151                                         request_size, response_size,
1152                                         GFP_KERNEL);
1153         if (!operation)
1154                 return -ENOMEM;
1155
1156         if (request_size)
1157                 memcpy(operation->request->payload, request, request_size);
1158
1159         ret = gb_operation_request_send_sync_timeout(operation, timeout);
1160         if (ret) {
1161                 dev_err(&connection->hd->dev,
1162                         "%s: synchronous operation id 0x%04x of type 0x%02x failed: %d\n",
1163                         connection->name, operation->id, type, ret);
1164         } else {
1165                 if (response_size) {
1166                         memcpy(response, operation->response->payload,
1167                                response_size);
1168                 }
1169         }
1170
1171         gb_operation_put(operation);
1172
1173         return ret;
1174 }
1175 EXPORT_SYMBOL_GPL(gb_operation_sync_timeout);
1176
1177 /**
1178  * gb_operation_unidirectional_timeout() - initiate a unidirectional operation
1179  * @connection:         connection to use
1180  * @type:               type of operation to send
1181  * @request:            memory buffer to copy the request from
1182  * @request_size:       size of @request
1183  * @timeout:            send timeout in milliseconds
1184  *
1185  * Initiate a unidirectional operation by sending a request message and
1186  * waiting for it to be acknowledged as sent by the host device.
1187  *
1188  * Note that successful send of a unidirectional operation does not imply that
1189  * the request as actually reached the remote end of the connection.
1190  */
1191 int gb_operation_unidirectional_timeout(struct gb_connection *connection,
1192                                 int type, void *request, int request_size,
1193                                 unsigned int timeout)
1194 {
1195         struct gb_operation *operation;
1196         int ret;
1197
1198         if (request_size && !request)
1199                 return -EINVAL;
1200
1201         operation = gb_operation_create_flags(connection, type,
1202                                         request_size, 0,
1203                                         GB_OPERATION_FLAG_UNIDIRECTIONAL,
1204                                         GFP_KERNEL);
1205         if (!operation)
1206                 return -ENOMEM;
1207
1208         if (request_size)
1209                 memcpy(operation->request->payload, request, request_size);
1210
1211         ret = gb_operation_request_send_sync_timeout(operation, timeout);
1212         if (ret) {
1213                 dev_err(&connection->hd->dev,
1214                         "%s: unidirectional operation of type 0x%02x failed: %d\n",
1215                         connection->name, type, ret);
1216         }
1217
1218         gb_operation_put(operation);
1219
1220         return ret;
1221 }
1222 EXPORT_SYMBOL_GPL(gb_operation_unidirectional_timeout);
1223
1224 int __init gb_operation_init(void)
1225 {
1226         gb_message_cache = kmem_cache_create("gb_message_cache",
1227                                 sizeof(struct gb_message), 0, 0, NULL);
1228         if (!gb_message_cache)
1229                 return -ENOMEM;
1230
1231         gb_operation_cache = kmem_cache_create("gb_operation_cache",
1232                                 sizeof(struct gb_operation), 0, 0, NULL);
1233         if (!gb_operation_cache)
1234                 goto err_destroy_message_cache;
1235
1236         gb_operation_completion_wq = alloc_workqueue("greybus_completion",
1237                                 0, 0);
1238         if (!gb_operation_completion_wq)
1239                 goto err_destroy_operation_cache;
1240
1241         return 0;
1242
1243 err_destroy_operation_cache:
1244         kmem_cache_destroy(gb_operation_cache);
1245         gb_operation_cache = NULL;
1246 err_destroy_message_cache:
1247         kmem_cache_destroy(gb_message_cache);
1248         gb_message_cache = NULL;
1249
1250         return -ENOMEM;
1251 }
1252
1253 void gb_operation_exit(void)
1254 {
1255         destroy_workqueue(gb_operation_completion_wq);
1256         gb_operation_completion_wq = NULL;
1257         kmem_cache_destroy(gb_operation_cache);
1258         gb_operation_cache = NULL;
1259         kmem_cache_destroy(gb_message_cache);
1260         gb_message_cache = NULL;
1261 }