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
 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                 operation->callback(operation);
 283
 284         gb_operation_put_active(operation);
 285         gb_operation_put(operation);
 286 }
 287
 288 static void gb_operation_message_init(struct gb_host_device *hd,
 289                                 struct gb_message *message, u16 operation_id,
 290                                 size_t payload_size, u8 type)
 291 {
 292         struct gb_operation_msg_hdr *header;
 293
 294         header = message->buffer;
 295
 296         message->header = header;
 297         message->payload = payload_size ? header + 1 : NULL;
 298         message->payload_size = payload_size;
 299
 300         /*
 301          * The type supplied for incoming message buffers will be
 302          * GB_REQUEST_TYPE_INVALID. Such buffers will be overwritten by
 303          * arriving data so there's no need to initialize the message header.
 304          */
 305         if (type != GB_REQUEST_TYPE_INVALID) {
 306                 u16 message_size = (u16)(sizeof(*header) + payload_size);
 307
 308                 /*
 309                  * For a request, the operation id gets filled in
 310                  * when the message is sent.  For a response, it
 311                  * will be copied from the request by the caller.
 312                  *
 313                  * The result field in a request message must be
 314                  * zero.  It will be set just prior to sending for
 315                  * a response.
 316                  */
 317                 header->size = cpu_to_le16(message_size);
 318                 header->operation_id = 0;
 319                 header->type = type;
 320                 header->result = 0;
 321         }
 322 }
 323
 324 /*
 325  * Allocate a message to be used for an operation request or response.
 326  * Both types of message contain a common header.  The request message
 327  * for an outgoing operation is outbound, as is the response message
 328  * for an incoming operation.  The message header for an outbound
 329  * message is partially initialized here.
 330  *
 331  * The headers for inbound messages don't need to be initialized;
 332  * they'll be filled in by arriving data.
 333  *
 334  * Our message buffers have the following layout:
 335  *      message header  \_ these combined are
 336  *      message payload /  the message size
 337  */
 338 static struct gb_message *
 339 gb_operation_message_alloc(struct gb_host_device *hd, u8 type,
 340                                 size_t payload_size, gfp_t gfp_flags)
 341 {
 342         struct gb_message *message;
 343         struct gb_operation_msg_hdr *header;
 344         size_t message_size = payload_size + sizeof(*header);
 345
 346         if (message_size > hd->buffer_size_max) {
 347                 dev_warn(&hd->dev, "requested message size too big (%zu > %zu)\n",
 348                                 message_size, hd->buffer_size_max);
 349                 return NULL;
 350         }
 351
 352         /* Allocate the message structure and buffer. */
 353         message = kmem_cache_zalloc(gb_message_cache, gfp_flags);
 354         if (!message)
 355                 return NULL;
 356
 357         message->buffer = kzalloc(message_size, gfp_flags);
 358         if (!message->buffer)
 359                 goto err_free_message;
 360
 361         /* Initialize the message.  Operation id is filled in later. */
 362         gb_operation_message_init(hd, message, 0, payload_size, type);
 363
 364         return message;
 365
 366 err_free_message:
 367         kmem_cache_free(gb_message_cache, message);
 368
 369         return NULL;
 370 }
 371
 372 static void gb_operation_message_free(struct gb_message *message)
 373 {
 374         kfree(message->buffer);
 375         kmem_cache_free(gb_message_cache, message);
 376 }
 377
 378 /*
 379  * Map an enum gb_operation_status value (which is represented in a
 380  * message as a single byte) to an appropriate Linux negative errno.
 381  */
 382 static int gb_operation_status_map(u8 status)
 383 {
 384         switch (status) {
 385         case GB_OP_SUCCESS:
 386                 return 0;
 387         case GB_OP_INTERRUPTED:
 388                 return -EINTR;
 389         case GB_OP_TIMEOUT:
 390                 return -ETIMEDOUT;
 391         case GB_OP_NO_MEMORY:
 392                 return -ENOMEM;
 393         case GB_OP_PROTOCOL_BAD:
 394                 return -EPROTONOSUPPORT;
 395         case GB_OP_OVERFLOW:
 396                 return -EMSGSIZE;
 397         case GB_OP_INVALID:
 398                 return -EINVAL;
 399         case GB_OP_RETRY:
 400                 return -EAGAIN;
 401         case GB_OP_NONEXISTENT:
 402                 return -ENODEV;
 403         case GB_OP_MALFUNCTION:
 404                 return -EILSEQ;
 405         case GB_OP_UNKNOWN_ERROR:
 406         default:
 407                 return -EIO;
 408         }
 409 }
 410
 411 /*
 412  * Map a Linux errno value (from operation->errno) into the value
 413  * that should represent it in a response message status sent
 414  * over the wire.  Returns an enum gb_operation_status value (which
 415  * is represented in a message as a single byte).
 416  */
 417 static u8 gb_operation_errno_map(int errno)
 418 {
 419         switch (errno) {
 420         case 0:
 421                 return GB_OP_SUCCESS;
 422         case -EINTR:
 423                 return GB_OP_INTERRUPTED;
 424         case -ETIMEDOUT:
 425                 return GB_OP_TIMEOUT;
 426         case -ENOMEM:
 427                 return GB_OP_NO_MEMORY;
 428         case -EPROTONOSUPPORT:
 429                 return GB_OP_PROTOCOL_BAD;
 430         case -EMSGSIZE:
 431                 return GB_OP_OVERFLOW;  /* Could be underflow too */
 432         case -EINVAL:
 433                 return GB_OP_INVALID;
 434         case -EAGAIN:
 435                 return GB_OP_RETRY;
 436         case -EILSEQ:
 437                 return GB_OP_MALFUNCTION;
 438         case -ENODEV:
 439                 return GB_OP_NONEXISTENT;
 440         case -EIO:
 441         default:
 442                 return GB_OP_UNKNOWN_ERROR;
 443         }
 444 }
 445
 446 bool gb_operation_response_alloc(struct gb_operation *operation,
 447                                         size_t response_size, gfp_t gfp)
 448 {
 449         struct gb_host_device *hd = operation->connection->hd;
 450         struct gb_operation_msg_hdr *request_header;
 451         struct gb_message *response;
 452         u8 type;
 453
 454         type = operation->type | GB_MESSAGE_TYPE_RESPONSE;
 455         response = gb_operation_message_alloc(hd, type, response_size, gfp);
 456         if (!response)
 457                 return false;
 458         response->operation = operation;
 459
 460         /*
 461          * Size and type get initialized when the message is
 462          * allocated.  The errno will be set before sending.  All
 463          * that's left is the operation id, which we copy from the
 464          * request message header (as-is, in little-endian order).
 465          */
 466         request_header = operation->request->header;
 467         response->header->operation_id = request_header->operation_id;
 468         operation->response = response;
 469
 470         return true;
 471 }
 472 EXPORT_SYMBOL_GPL(gb_operation_response_alloc);
 473
 474 /*
 475  * Create a Greybus operation to be sent over the given connection.
 476  * The request buffer will be big enough for a payload of the given
 477  * size.
 478  *
 479  * For outgoing requests, the request message's header will be
 480  * initialized with the type of the request and the message size.
 481  * Outgoing operations must also specify the response buffer size,
 482  * which must be sufficient to hold all expected response data.  The
 483  * response message header will eventually be overwritten, so there's
 484  * no need to initialize it here.
 485  *
 486  * Request messages for incoming operations can arrive in interrupt
 487  * context, so they must be allocated with GFP_ATOMIC.  In this case
 488  * the request buffer will be immediately overwritten, so there is
 489  * no need to initialize the message header.  Responsibility for
 490  * allocating a response buffer lies with the incoming request
 491  * handler for a protocol.  So we don't allocate that here.
 492  *
 493  * Returns a pointer to the new operation or a null pointer if an
 494  * error occurs.
 495  */
 496 static struct gb_operation *
 497 gb_operation_create_common(struct gb_connection *connection, u8 type,
 498                                 size_t request_size, size_t response_size,
 499                                 unsigned long op_flags, gfp_t gfp_flags)
 500 {
 501         struct gb_host_device *hd = connection->hd;
 502         struct gb_operation *operation;
 503
 504         operation = kmem_cache_zalloc(gb_operation_cache, gfp_flags);
 505         if (!operation)
 506                 return NULL;
 507         operation->connection = connection;
 508
 509         operation->request = gb_operation_message_alloc(hd, type, request_size,
 510                                                         gfp_flags);
 511         if (!operation->request)
 512                 goto err_cache;
 513         operation->request->operation = operation;
 514
 515         /* Allocate the response buffer for outgoing operations */
 516         if (!(op_flags & GB_OPERATION_FLAG_INCOMING)) {
 517                 if (!gb_operation_response_alloc(operation, response_size,
 518                                                  gfp_flags)) {
 519                         goto err_request;
 520                 }
 521         }
 522
 523         operation->flags = op_flags;
 524         operation->type = type;
 525         operation->errno = -EBADR;  /* Initial value--means "never set" */
 526
 527         INIT_WORK(&operation->work, gb_operation_work);
 528         init_completion(&operation->completion);
 529         kref_init(&operation->kref);
 530         atomic_set(&operation->waiters, 0);
 531
 532         return operation;
 533
 534 err_request:
 535         gb_operation_message_free(operation->request);
 536 err_cache:
 537         kmem_cache_free(gb_operation_cache, operation);
 538
 539         return NULL;
 540 }
 541
 542 /*
 543  * Create a new operation associated with the given connection.  The
 544  * request and response sizes provided are the number of bytes
 545  * required to hold the request/response payload only.  Both of
 546  * these are allowed to be 0.  Note that 0x00 is reserved as an
 547  * invalid operation type for all protocols, and this is enforced
 548  * here.
 549  */
 550 struct gb_operation *
 551 gb_operation_create_flags(struct gb_connection *connection,
 552                                 u8 type, size_t request_size,
 553                                 size_t response_size, unsigned long flags,
 554                                 gfp_t gfp)
 555 {
 556         struct gb_operation *operation;
 557
 558         if (WARN_ON_ONCE(type == GB_REQUEST_TYPE_INVALID))
 559                 return NULL;
 560         if (WARN_ON_ONCE(type & GB_MESSAGE_TYPE_RESPONSE))
 561                 type &= ~GB_MESSAGE_TYPE_RESPONSE;
 562
 563         if (WARN_ON_ONCE(flags & ~GB_OPERATION_FLAG_USER_MASK))
 564                 flags &= GB_OPERATION_FLAG_USER_MASK;
 565
 566         operation = gb_operation_create_common(connection, type,
 567                                                 request_size, response_size,
 568                                                 flags, gfp);
 569         if (operation)
 570                 trace_gb_operation_create(operation);
 571
 572         return operation;
 573 }
 574 EXPORT_SYMBOL_GPL(gb_operation_create_flags);
 575
 576 struct gb_operation *
 577 gb_operation_create_core(struct gb_connection *connection,
 578                                 u8 type, size_t request_size,
 579                                 size_t response_size, unsigned long flags,
 580                                 gfp_t gfp)
 581 {
 582         struct gb_operation *operation;
 583
 584         flags |= GB_OPERATION_FLAG_CORE;
 585
 586         operation = gb_operation_create_common(connection, type,
 587                                                 request_size, response_size,
 588                                                 flags, gfp);
 589         if (operation)
 590                 trace_gb_operation_create_core(operation);
 591
 592         return operation;
 593 }
 594 /* Do not export this function. */
 595
 596 size_t gb_operation_get_payload_size_max(struct gb_connection *connection)
 597 {
 598         struct gb_host_device *hd = connection->hd;
 599
 600         return hd->buffer_size_max - sizeof(struct gb_operation_msg_hdr);
 601 }
 602 EXPORT_SYMBOL_GPL(gb_operation_get_payload_size_max);
 603
 604 static struct gb_operation *
 605 gb_operation_create_incoming(struct gb_connection *connection, u16 id,
 606                                 u8 type, void *data, size_t size)
 607 {
 608         struct gb_operation *operation;
 609         size_t request_size;
 610         unsigned long flags = GB_OPERATION_FLAG_INCOMING;
 611
 612         /* Caller has made sure we at least have a message header. */
 613         request_size = size - sizeof(struct gb_operation_msg_hdr);
 614
 615         if (!id)
 616                 flags |= GB_OPERATION_FLAG_UNIDIRECTIONAL;
 617
 618         operation = gb_operation_create_common(connection, type,
 619                                                 request_size,
 620                                                 GB_REQUEST_TYPE_INVALID,
 621                                                 flags, GFP_ATOMIC);
 622         if (!operation)
 623                 return NULL;
 624
 625         operation->id = id;
 626         memcpy(operation->request->header, data, size);
 627         trace_gb_operation_create_incoming(operation);
 628
 629         return operation;
 630 }
 631
 632 /*
 633  * Get an additional reference on an operation.
 634  */
 635 void gb_operation_get(struct gb_operation *operation)
 636 {
 637         kref_get(&operation->kref);
 638 }
 639 EXPORT_SYMBOL_GPL(gb_operation_get);
 640
 641 /*
 642  * Destroy a previously created operation.
 643  */
 644 static void _gb_operation_destroy(struct kref *kref)
 645 {
 646         struct gb_operation *operation;
 647
 648         operation = container_of(kref, struct gb_operation, kref);
 649
 650         trace_gb_operation_destroy(operation);
 651
 652         if (operation->response)
 653                 gb_operation_message_free(operation->response);
 654         gb_operation_message_free(operation->request);
 655
 656         kmem_cache_free(gb_operation_cache, operation);
 657 }
 658
 659 /*
 660  * Drop a reference on an operation, and destroy it when the last
 661  * one is gone.
 662  */
 663 void gb_operation_put(struct gb_operation *operation)
 664 {
 665         if (WARN_ON(!operation))
 666                 return;
 667
 668         kref_put(&operation->kref, _gb_operation_destroy);
 669 }
 670 EXPORT_SYMBOL_GPL(gb_operation_put);
 671
 672 /* Tell the requester we're done */
 673 static void gb_operation_sync_callback(struct gb_operation *operation)
 674 {
 675         complete(&operation->completion);
 676 }
 677
 678 /**
 679  * gb_operation_request_send() - send an operation request message
 680  * @operation:  the operation to initiate
 681  * @callback:   the operation completion callback
 682  * @gfp:        the memory flags to use for any allocations
 683  *
 684  * The caller has filled in any payload so the request message is ready to go.
 685  * The callback function supplied will be called when the response message has
 686  * arrived, a unidirectional request has been sent, or the operation is
 687  * cancelled, indicating that the operation is complete. The callback function
 688  * can fetch the result of the operation using gb_operation_result() if
 689  * desired.
 690  *
 691  * Return: 0 if the request was successfully queued in the host-driver queues,
 692  * or a negative errno.
 693  */
 694 int gb_operation_request_send(struct gb_operation *operation,
 695                                 gb_operation_callback callback,
 696                                 gfp_t gfp)
 697 {
 698         struct gb_connection *connection = operation->connection;
 699         struct gb_operation_msg_hdr *header;
 700         unsigned int cycle;
 701         int ret;
 702
 703         if (gb_connection_is_offloaded(connection))
 704                 return -EBUSY;
 705
 706         if (!callback)
 707                 return -EINVAL;
 708
 709         /*
 710          * Record the callback function, which is executed in
 711          * non-atomic (workqueue) context when the final result
 712          * of an operation has been set.
 713          */
 714         operation->callback = callback;
 715
 716         /*
 717          * Assign the operation's id, and store it in the request header.
 718          * Zero is a reserved operation id for unidirectional operations.
 719          */
 720         if (gb_operation_is_unidirectional(operation)) {
 721                 operation->id = 0;
 722         } else {
 723                 cycle = (unsigned int)atomic_inc_return(&connection->op_cycle);
 724                 operation->id = (u16)(cycle % U16_MAX + 1);
 725         }
 726
 727         header = operation->request->header;
 728         header->operation_id = cpu_to_le16(operation->id);
 729
 730         gb_operation_result_set(operation, -EINPROGRESS);
 731
 732         /*
 733          * Get an extra reference on the operation. It'll be dropped when the
 734          * operation completes.
 735          */
 736         gb_operation_get(operation);
 737         ret = gb_operation_get_active(operation);
 738         if (ret)
 739                 goto err_put;
 740
 741         ret = gb_message_send(operation->request, gfp);
 742         if (ret)
 743                 goto err_put_active;
 744
 745         return 0;
 746
 747 err_put_active:
 748         gb_operation_put_active(operation);
 749 err_put:
 750         gb_operation_put(operation);
 751
 752         return ret;
 753 }
 754 EXPORT_SYMBOL_GPL(gb_operation_request_send);
 755
 756 /*
 757  * Send a synchronous operation.  This function is expected to
 758  * block, returning only when the response has arrived, (or when an
 759  * error is detected.  The return value is the result of the
 760  * operation.
 761  */
 762 int gb_operation_request_send_sync_timeout(struct gb_operation *operation,
 763                                                 unsigned int timeout)
 764 {
 765         int ret;
 766         unsigned long timeout_jiffies;
 767
 768         ret = gb_operation_request_send(operation, gb_operation_sync_callback,
 769                                         GFP_KERNEL);
 770         if (ret)
 771                 return ret;
 772
 773         if (timeout)
 774                 timeout_jiffies = msecs_to_jiffies(timeout);
 775         else
 776                 timeout_jiffies = MAX_SCHEDULE_TIMEOUT;
 777
 778         ret = wait_for_completion_interruptible_timeout(&operation->completion,
 779                                                         timeout_jiffies);
 780         if (ret < 0) {
 781                 /* Cancel the operation if interrupted */
 782                 gb_operation_cancel(operation, -ECANCELED);
 783         } else if (ret == 0) {
 784                 /* Cancel the operation if op timed out */
 785                 gb_operation_cancel(operation, -ETIMEDOUT);
 786         }
 787
 788         return gb_operation_result(operation);
 789 }
 790 EXPORT_SYMBOL_GPL(gb_operation_request_send_sync_timeout);
 791
 792 /*
 793  * Send a response for an incoming operation request.  A non-zero
 794  * errno indicates a failed operation.
 795  *
 796  * If there is any response payload, the incoming request handler is
 797  * responsible for allocating the response message.  Otherwise the
 798  * it can simply supply the result errno; this function will
 799  * allocate the response message if necessary.
 800  */
 801 static int gb_operation_response_send(struct gb_operation *operation,
 802                                         int errno)
 803 {
 804         struct gb_connection *connection = operation->connection;
 805         int ret;
 806
 807         if (!operation->response &&
 808                         !gb_operation_is_unidirectional(operation)) {
 809                 if (!gb_operation_response_alloc(operation, 0, GFP_KERNEL))
 810                         return -ENOMEM;
 811         }
 812
 813         /* Record the result */
 814         if (!gb_operation_result_set(operation, errno)) {
 815                 dev_err(&connection->hd->dev, "request result already set\n");
 816                 return -EIO;    /* Shouldn't happen */
 817         }
 818
 819         /* Sender of request does not care about response. */
 820         if (gb_operation_is_unidirectional(operation))
 821                 return 0;
 822
 823         /* Reference will be dropped when message has been sent. */
 824         gb_operation_get(operation);
 825         ret = gb_operation_get_active(operation);
 826         if (ret)
 827                 goto err_put;
 828
 829         /* Fill in the response header and send it */
 830         operation->response->header->result = gb_operation_errno_map(errno);
 831
 832         ret = gb_message_send(operation->response, GFP_KERNEL);
 833         if (ret)
 834                 goto err_put_active;
 835
 836         return 0;
 837
 838 err_put_active:
 839         gb_operation_put_active(operation);
 840 err_put:
 841         gb_operation_put(operation);
 842
 843         return ret;
 844 }
 845
 846 /*
 847  * This function is called when a message send request has completed.
 848  */
 849 void greybus_message_sent(struct gb_host_device *hd,
 850                                         struct gb_message *message, int status)
 851 {
 852         struct gb_operation *operation = message->operation;
 853         struct gb_connection *connection = operation->connection;
 854
 855         /*
 856          * If the message was a response, we just need to drop our
 857          * reference to the operation.  If an error occurred, report
 858          * it.
 859          *
 860          * For requests, if there's no error and the operation in not
 861          * unidirectional, there's nothing more to do until the response
 862          * arrives. If an error occurred attempting to send it, or if the
 863          * operation is unidrectional, record the result of the operation and
 864          * schedule its completion.
 865          */
 866         if (message == operation->response) {
 867                 if (status) {
 868                         dev_err(&connection->hd->dev,
 869                                 "%s: error sending response 0x%02x: %d\n",
 870                                 connection->name, operation->type, status);
 871                 }
 872
 873                 gb_operation_put_active(operation);
 874                 gb_operation_put(operation);
 875         } else if (status || gb_operation_is_unidirectional(operation)) {
 876                 if (gb_operation_result_set(operation, status)) {
 877                         queue_work(gb_operation_completion_wq,
 878                                         &operation->work);
 879                 }
 880         }
 881 }
 882 EXPORT_SYMBOL_GPL(greybus_message_sent);
 883
 884 /*
 885  * We've received data on a connection, and it doesn't look like a
 886  * response, so we assume it's a request.
 887  *
 888  * This is called in interrupt context, so just copy the incoming
 889  * data into the request buffer and handle the rest via workqueue.
 890  */
 891 static void gb_connection_recv_request(struct gb_connection *connection,
 892                                 const struct gb_operation_msg_hdr *header,
 893                                 void *data, size_t size)
 894 {
 895         struct gb_operation *operation;
 896         u16 operation_id;
 897         u8 type;
 898         int ret;
 899
 900         operation_id = le16_to_cpu(header->operation_id);
 901         type = header->type;
 902
 903         operation = gb_operation_create_incoming(connection, operation_id,
 904                                                 type, data, size);
 905         if (!operation) {
 906                 dev_err(&connection->hd->dev,
 907                         "%s: can't create incoming operation\n",
 908                         connection->name);
 909                 return;
 910         }
 911
 912         ret = gb_operation_get_active(operation);
 913         if (ret) {
 914                 gb_operation_put(operation);
 915                 return;
 916         }
 917         trace_gb_message_recv_request(operation->request);
 918
 919         /*
 920          * The initial reference to the operation will be dropped when the
 921          * request handler returns.
 922          */
 923         if (gb_operation_result_set(operation, -EINPROGRESS))
 924                 queue_work(connection->wq, &operation->work);
 925 }
 926
 927 /*
 928  * We've received data that appears to be an operation response
 929  * message.  Look up the operation, and record that we've received
 930  * its response.
 931  *
 932  * This is called in interrupt context, so just copy the incoming
 933  * data into the response buffer and handle the rest via workqueue.
 934  */
 935 static void gb_connection_recv_response(struct gb_connection *connection,
 936                                 const struct gb_operation_msg_hdr *header,
 937                                 void *data, size_t size)
 938 {
 939         struct gb_operation *operation;
 940         struct gb_message *message;
 941         size_t message_size;
 942         u16 operation_id;
 943         int errno;
 944
 945         operation_id = le16_to_cpu(header->operation_id);
 946
 947         if (!operation_id) {
 948                 dev_err_ratelimited(&connection->hd->dev,
 949                                 "%s: invalid response id 0 received\n",
 950                                 connection->name);
 951                 return;
 952         }
 953
 954         operation = gb_operation_find_outgoing(connection, operation_id);
 955         if (!operation) {
 956                 dev_err_ratelimited(&connection->hd->dev,
 957                                 "%s: unexpected response id 0x%04x received\n",
 958                                 connection->name, operation_id);
 959                 return;
 960         }
 961
 962         errno = gb_operation_status_map(header->result);
 963         message = operation->response;
 964         message_size = sizeof(*header) + message->payload_size;
 965         if (!errno && size > message_size) {
 966                 dev_err_ratelimited(&connection->hd->dev,
 967                                 "%s: malformed response 0x%02x received (%zu > %zu)\n",
 968                                 connection->name, header->type,
 969                                 size, message_size);
 970                 errno = -EMSGSIZE;
 971         } else if (!errno && size < message_size) {
 972                 if (gb_operation_short_response_allowed(operation)) {
 973                         message->payload_size = size - sizeof(*header);
 974                 } else {
 975                         dev_err_ratelimited(&connection->hd->dev,
 976                                         "%s: short response 0x%02x received (%zu < %zu)\n",
 977                                         connection->name, header->type,
 978                                         size, message_size);
 979                         errno = -EMSGSIZE;
 980                 }
 981         }
 982
 983         /* We must ignore the payload if a bad status is returned */
 984         if (errno)
 985                 size = sizeof(*header);
 986
 987         /* The rest will be handled in work queue context */
 988         if (gb_operation_result_set(operation, errno)) {
 989                 memcpy(message->buffer, data, size);
 990
 991                 trace_gb_message_recv_response(message);
 992
 993                 queue_work(gb_operation_completion_wq, &operation->work);
 994         }
 995
 996         gb_operation_put(operation);
 997 }
 998
 999 /*
1000  * Handle data arriving on a connection.  As soon as we return the
1001  * supplied data buffer will be reused (so unless we do something
1002  * with, it's effectively dropped).
1003  */
1004 void gb_connection_recv(struct gb_connection *connection,
1005                                 void *data, size_t size)
1006 {
1007         struct gb_operation_msg_hdr header;
1008         struct device *dev = &connection->hd->dev;
1009         size_t msg_size;
1010
1011         if (connection->state == GB_CONNECTION_STATE_DISABLED ||
1012                         gb_connection_is_offloaded(connection)) {
1013                 dev_warn_ratelimited(dev, "%s: dropping %zu received bytes\n",
1014                                 connection->name, size);
1015                 return;
1016         }
1017
1018         if (size < sizeof(header)) {
1019                 dev_err_ratelimited(dev, "%s: short message received\n",
1020                                 connection->name);
1021                 return;
1022         }
1023
1024         /* Use memcpy as data may be unaligned */
1025         memcpy(&header, data, sizeof(header));
1026         msg_size = le16_to_cpu(header.size);
1027         if (size < msg_size) {
1028                 dev_err_ratelimited(dev,
1029                                 "%s: incomplete message 0x%04x of type 0x%02x received (%zu < %zu)\n",
1030                                 connection->name,
1031                                 le16_to_cpu(header.operation_id),
1032                                 header.type, size, msg_size);
1033                 return;         /* XXX Should still complete operation */
1034         }
1035
1036         if (header.type & GB_MESSAGE_TYPE_RESPONSE) {
1037                 gb_connection_recv_response(connection, &header, data,
1038                                                 msg_size);
1039         } else {
1040                 gb_connection_recv_request(connection, &header, data,
1041                                                 msg_size);
1042         }
1043 }
1044
1045 /*
1046  * Cancel an outgoing operation synchronously, and record the given error to
1047  * indicate why.
1048  */
1049 void gb_operation_cancel(struct gb_operation *operation, int errno)
1050 {
1051         if (WARN_ON(gb_operation_is_incoming(operation)))
1052                 return;
1053
1054         if (gb_operation_result_set(operation, errno)) {
1055                 gb_message_cancel(operation->request);
1056                 queue_work(gb_operation_completion_wq, &operation->work);
1057         }
1058         trace_gb_message_cancel_outgoing(operation->request);
1059
1060         atomic_inc(&operation->waiters);
1061         wait_event(gb_operation_cancellation_queue,
1062                         !gb_operation_is_active(operation));
1063         atomic_dec(&operation->waiters);
1064 }
1065 EXPORT_SYMBOL_GPL(gb_operation_cancel);
1066
1067 /*
1068  * Cancel an incoming operation synchronously. Called during connection tear
1069  * down.
1070  */
1071 void gb_operation_cancel_incoming(struct gb_operation *operation, int errno)
1072 {
1073         if (WARN_ON(!gb_operation_is_incoming(operation)))
1074                 return;
1075
1076         if (!gb_operation_is_unidirectional(operation)) {
1077                 /*
1078                  * Make sure the request handler has submitted the response
1079                  * before cancelling it.
1080                  */
1081                 flush_work(&operation->work);
1082                 if (!gb_operation_result_set(operation, errno))
1083                         gb_message_cancel(operation->response);
1084         }
1085         trace_gb_message_cancel_incoming(operation->response);
1086
1087         atomic_inc(&operation->waiters);
1088         wait_event(gb_operation_cancellation_queue,
1089                         !gb_operation_is_active(operation));
1090         atomic_dec(&operation->waiters);
1091 }
1092
1093 /**
1094  * gb_operation_sync_timeout() - implement a "simple" synchronous operation
1095  * @connection: the Greybus connection to send this to
1096  * @type: the type of operation to send
1097  * @request: pointer to a memory buffer to copy the request from
1098  * @request_size: size of @request
1099  * @response: pointer to a memory buffer to copy the response to
1100  * @response_size: the size of @response.
1101  * @timeout: operation timeout in milliseconds
1102  *
1103  * This function implements a simple synchronous Greybus operation.  It sends
1104  * the provided operation request and waits (sleeps) until the corresponding
1105  * operation response message has been successfully received, or an error
1106  * occurs.  @request and @response are buffers to hold the request and response
1107  * data respectively, and if they are not NULL, their size must be specified in
1108  * @request_size and @response_size.
1109  *
1110  * If a response payload is to come back, and @response is not NULL,
1111  * @response_size number of bytes will be copied into @response if the operation
1112  * is successful.
1113  *
1114  * If there is an error, the response buffer is left alone.
1115  */
1116 int gb_operation_sync_timeout(struct gb_connection *connection, int type,
1117                                 void *request, int request_size,
1118                                 void *response, int response_size,
1119                                 unsigned int timeout)
1120 {
1121         struct gb_operation *operation;
1122         int ret;
1123
1124         if ((response_size && !response) ||
1125             (request_size && !request))
1126                 return -EINVAL;
1127
1128         operation = gb_operation_create(connection, type,
1129                                         request_size, response_size,
1130                                         GFP_KERNEL);
1131         if (!operation)
1132                 return -ENOMEM;
1133
1134         if (request_size)
1135                 memcpy(operation->request->payload, request, request_size);
1136
1137         ret = gb_operation_request_send_sync_timeout(operation, timeout);
1138         if (ret) {
1139                 dev_err(&connection->hd->dev,
1140                         "%s: synchronous operation id 0x%04x of type 0x%02x failed: %d\n",
1141                         connection->name, operation->id, type, ret);
1142         } else {
1143                 if (response_size) {
1144                         memcpy(response, operation->response->payload,
1145                                response_size);
1146                 }
1147         }
1148
1149         gb_operation_put(operation);
1150
1151         return ret;
1152 }
1153 EXPORT_SYMBOL_GPL(gb_operation_sync_timeout);
1154
1155 /**
1156  * gb_operation_unidirectional_timeout() - initiate a unidirectional operation
1157  * @connection:         connection to use
1158  * @type:               type of operation to send
1159  * @request:            memory buffer to copy the request from
1160  * @request_size:       size of @request
1161  * @timeout:            send timeout in milliseconds
1162  *
1163  * Initiate a unidirectional operation by sending a request message and
1164  * waiting for it to be acknowledged as sent by the host device.
1165  *
1166  * Note that successful send of a unidirectional operation does not imply that
1167  * the request as actually reached the remote end of the connection.
1168  */
1169 int gb_operation_unidirectional_timeout(struct gb_connection *connection,
1170                                 int type, void *request, int request_size,
1171                                 unsigned int timeout)
1172 {
1173         struct gb_operation *operation;
1174         int ret;
1175
1176         if (request_size && !request)
1177                 return -EINVAL;
1178
1179         operation = gb_operation_create_flags(connection, type,
1180                                         request_size, 0,
1181                                         GB_OPERATION_FLAG_UNIDIRECTIONAL,
1182                                         GFP_KERNEL);
1183         if (!operation)
1184                 return -ENOMEM;
1185
1186         if (request_size)
1187                 memcpy(operation->request->payload, request, request_size);
1188
1189         ret = gb_operation_request_send_sync_timeout(operation, timeout);
1190         if (ret) {
1191                 dev_err(&connection->hd->dev,
1192                         "%s: unidirectional operation of type 0x%02x failed: %d\n",
1193                         connection->name, type, ret);
1194         }
1195
1196         gb_operation_put(operation);
1197
1198         return ret;
1199 }
1200 EXPORT_SYMBOL_GPL(gb_operation_unidirectional_timeout);
1201
1202 int __init gb_operation_init(void)
1203 {
1204         gb_message_cache = kmem_cache_create("gb_message_cache",
1205                                 sizeof(struct gb_message), 0, 0, NULL);
1206         if (!gb_message_cache)
1207                 return -ENOMEM;
1208
1209         gb_operation_cache = kmem_cache_create("gb_operation_cache",
1210                                 sizeof(struct gb_operation), 0, 0, NULL);
1211         if (!gb_operation_cache)
1212                 goto err_destroy_message_cache;
1213
1214         gb_operation_completion_wq = alloc_workqueue("greybus_completion",
1215                                 0, 0);
1216         if (!gb_operation_completion_wq)
1217                 goto err_destroy_operation_cache;
1218
1219         return 0;
1220
1221 err_destroy_operation_cache:
1222         kmem_cache_destroy(gb_operation_cache);
1223         gb_operation_cache = NULL;
1224 err_destroy_message_cache:
1225         kmem_cache_destroy(gb_message_cache);
1226         gb_message_cache = NULL;
1227
1228         return -ENOMEM;
1229 }
1230
1231 void gb_operation_exit(void)
1232 {
1233         destroy_workqueue(gb_operation_completion_wq);
1234         gb_operation_completion_wq = NULL;
1235         kmem_cache_destroy(gb_operation_cache);
1236         gb_operation_cache = NULL;
1237         kmem_cache_destroy(gb_message_cache);
1238         gb_message_cache = NULL;
1239 }