GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / greybus / operation.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Greybus operations
4  *
5  * Copyright 2014-2015 Google Inc.
6  * Copyright 2014-2015 Linaro Ltd.
7  */
8
9 #include <linux/kernel.h>
10 #include <linux/slab.h>
11 #include <linux/module.h>
12 #include <linux/sched.h>
13 #include <linux/wait.h>
14 #include <linux/workqueue.h>
15 #include <linux/greybus.h>
16
17 #include "greybus_trace.h"
18
19 static struct kmem_cache *gb_operation_cache;
20 static struct kmem_cache *gb_message_cache;
21
22 /* Workqueue to handle Greybus operation completions. */
23 static struct workqueue_struct *gb_operation_completion_wq;
24
25 /* Wait queue for synchronous cancellations. */
26 static DECLARE_WAIT_QUEUE_HEAD(gb_operation_cancellation_queue);
27
28 /*
29  * Protects updates to operation->errno.
30  */
31 static DEFINE_SPINLOCK(gb_operations_lock);
32
33 static int gb_operation_response_send(struct gb_operation *operation,
34                                       int errno);
35
36 /*
37  * Increment operation active count and add to connection list unless the
38  * connection is going away.
39  *
40  * Caller holds operation reference.
41  */
42 static int gb_operation_get_active(struct gb_operation *operation)
43 {
44         struct gb_connection *connection = operation->connection;
45         unsigned long flags;
46
47         spin_lock_irqsave(&connection->lock, flags);
48         switch (connection->state) {
49         case GB_CONNECTION_STATE_ENABLED:
50                 break;
51         case GB_CONNECTION_STATE_ENABLED_TX:
52                 if (gb_operation_is_incoming(operation))
53                         goto err_unlock;
54                 break;
55         case GB_CONNECTION_STATE_DISCONNECTING:
56                 if (!gb_operation_is_core(operation))
57                         goto err_unlock;
58                 break;
59         default:
60                 goto err_unlock;
61         }
62
63         if (operation->active++ == 0)
64                 list_add_tail(&operation->links, &connection->operations);
65
66         trace_gb_operation_get_active(operation);
67
68         spin_unlock_irqrestore(&connection->lock, flags);
69
70         return 0;
71
72 err_unlock:
73         spin_unlock_irqrestore(&connection->lock, flags);
74
75         return -ENOTCONN;
76 }
77
78 /* Caller holds operation reference. */
79 static void gb_operation_put_active(struct gb_operation *operation)
80 {
81         struct gb_connection *connection = operation->connection;
82         unsigned long flags;
83
84         spin_lock_irqsave(&connection->lock, flags);
85
86         trace_gb_operation_put_active(operation);
87
88         if (--operation->active == 0) {
89                 list_del(&operation->links);
90                 if (atomic_read(&operation->waiters))
91                         wake_up(&gb_operation_cancellation_queue);
92         }
93         spin_unlock_irqrestore(&connection->lock, flags);
94 }
95
96 static bool gb_operation_is_active(struct gb_operation *operation)
97 {
98         struct gb_connection *connection = operation->connection;
99         unsigned long flags;
100         bool ret;
101
102         spin_lock_irqsave(&connection->lock, flags);
103         ret = operation->active;
104         spin_unlock_irqrestore(&connection->lock, flags);
105
106         return ret;
107 }
108
109 /*
110  * Set an operation's result.
111  *
112  * Initially an outgoing operation's errno value is -EBADR.
113  * If no error occurs before sending the request message the only
114  * valid value operation->errno can be set to is -EINPROGRESS,
115  * indicating the request has been (or rather is about to be) sent.
116  * At that point nobody should be looking at the result until the
117  * response arrives.
118  *
119  * The first time the result gets set after the request has been
120  * sent, that result "sticks."  That is, if two concurrent threads
121  * race to set the result, the first one wins.  The return value
122  * tells the caller whether its result was recorded; if not the
123  * caller has nothing more to do.
124  *
125  * The result value -EILSEQ is reserved to signal an implementation
126  * error; if it's ever observed, the code performing the request has
127  * done something fundamentally wrong.  It is an error to try to set
128  * the result to -EBADR, and attempts to do so result in a warning,
129  * and -EILSEQ is used instead.  Similarly, the only valid result
130  * value to set for an operation in initial state is -EINPROGRESS.
131  * Attempts to do otherwise will also record a (successful) -EILSEQ
132  * operation result.
133  */
134 static bool gb_operation_result_set(struct gb_operation *operation, int result)
135 {
136         unsigned long flags;
137         int prev;
138
139         if (result == -EINPROGRESS) {
140                 /*
141                  * -EINPROGRESS is used to indicate the request is
142                  * in flight.  It should be the first result value
143                  * set after the initial -EBADR.  Issue a warning
144                  * and record an implementation error if it's
145                  * set at any other time.
146                  */
147                 spin_lock_irqsave(&gb_operations_lock, flags);
148                 prev = operation->errno;
149                 if (prev == -EBADR)
150                         operation->errno = result;
151                 else
152                         operation->errno = -EILSEQ;
153                 spin_unlock_irqrestore(&gb_operations_lock, flags);
154                 WARN_ON(prev != -EBADR);
155
156                 return true;
157         }
158
159         /*
160          * The first result value set after a request has been sent
161          * will be the final result of the operation.  Subsequent
162          * attempts to set the result are ignored.
163          *
164          * Note that -EBADR is a reserved "initial state" result
165          * value.  Attempts to set this value result in a warning,
166          * and the result code is set to -EILSEQ instead.
167          */
168         if (WARN_ON(result == -EBADR))
169                 result = -EILSEQ; /* Nobody should be setting -EBADR */
170
171         spin_lock_irqsave(&gb_operations_lock, flags);
172         prev = operation->errno;
173         if (prev == -EINPROGRESS)
174                 operation->errno = result;      /* First and final result */
175         spin_unlock_irqrestore(&gb_operations_lock, flags);
176
177         return prev == -EINPROGRESS;
178 }
179
180 int gb_operation_result(struct gb_operation *operation)
181 {
182         int result = operation->errno;
183
184         WARN_ON(result == -EBADR);
185         WARN_ON(result == -EINPROGRESS);
186
187         return result;
188 }
189 EXPORT_SYMBOL_GPL(gb_operation_result);
190
191 /*
192  * Looks up an outgoing operation on a connection and returns a refcounted
193  * pointer if found, or NULL otherwise.
194  */
195 static struct gb_operation *
196 gb_operation_find_outgoing(struct gb_connection *connection, u16 operation_id)
197 {
198         struct gb_operation *operation;
199         unsigned long flags;
200         bool found = false;
201
202         spin_lock_irqsave(&connection->lock, flags);
203         list_for_each_entry(operation, &connection->operations, links)
204                 if (operation->id == operation_id &&
205                     !gb_operation_is_incoming(operation)) {
206                         gb_operation_get(operation);
207                         found = true;
208                         break;
209                 }
210         spin_unlock_irqrestore(&connection->lock, flags);
211
212         return found ? operation : NULL;
213 }
214
215 static int gb_message_send(struct gb_message *message, gfp_t gfp)
216 {
217         struct gb_connection *connection = message->operation->connection;
218
219         trace_gb_message_send(message);
220         return connection->hd->driver->message_send(connection->hd,
221                                         connection->hd_cport_id,
222                                         message,
223                                         gfp);
224 }
225
226 /*
227  * Cancel a message we have passed to the host device layer to be sent.
228  */
229 static void gb_message_cancel(struct gb_message *message)
230 {
231         struct gb_host_device *hd = message->operation->connection->hd;
232
233         hd->driver->message_cancel(message);
234 }
235
236 static void gb_operation_request_handle(struct gb_operation *operation)
237 {
238         struct gb_connection *connection = operation->connection;
239         int status;
240         int ret;
241
242         if (connection->handler) {
243                 status = connection->handler(operation);
244         } else {
245                 dev_err(&connection->hd->dev,
246                         "%s: unexpected incoming request of type 0x%02x\n",
247                         connection->name, operation->type);
248
249                 status = -EPROTONOSUPPORT;
250         }
251
252         ret = gb_operation_response_send(operation, status);
253         if (ret) {
254                 dev_err(&connection->hd->dev,
255                         "%s: failed to send response %d for type 0x%02x: %d\n",
256                         connection->name, status, operation->type, ret);
257                 return;
258         }
259 }
260
261 /*
262  * Process operation work.
263  *
264  * For incoming requests, call the protocol request handler. The operation
265  * result should be -EINPROGRESS at this point.
266  *
267  * For outgoing requests, the operation result value should have
268  * been set before queueing this.  The operation callback function
269  * allows the original requester to know the request has completed
270  * and its result is available.
271  */
272 static void gb_operation_work(struct work_struct *work)
273 {
274         struct gb_operation *operation;
275         int ret;
276
277         operation = container_of(work, struct gb_operation, work);
278
279         if (gb_operation_is_incoming(operation)) {
280                 gb_operation_request_handle(operation);
281         } else {
282                 ret = del_timer_sync(&operation->timer);
283                 if (!ret) {
284                         /* Cancel request message if scheduled by timeout. */
285                         if (gb_operation_result(operation) == -ETIMEDOUT)
286                                 gb_message_cancel(operation->request);
287                 }
288
289                 operation->callback(operation);
290         }
291
292         gb_operation_put_active(operation);
293         gb_operation_put(operation);
294 }
295
296 static void gb_operation_timeout(struct timer_list *t)
297 {
298         struct gb_operation *operation = from_timer(operation, t, timer);
299
300         if (gb_operation_result_set(operation, -ETIMEDOUT)) {
301                 /*
302                  * A stuck request message will be cancelled from the
303                  * workqueue.
304                  */
305                 queue_work(gb_operation_completion_wq, &operation->work);
306         }
307 }
308
309 static void gb_operation_message_init(struct gb_host_device *hd,
310                                       struct gb_message *message,
311                                       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                 timer_setup(&operation->timer, gb_operation_timeout, 0);
545         }
546
547         operation->flags = op_flags;
548         operation->type = type;
549         operation->errno = -EBADR;  /* Initial value--means "never set" */
550
551         INIT_WORK(&operation->work, gb_operation_work);
552         init_completion(&operation->completion);
553         kref_init(&operation->kref);
554         atomic_set(&operation->waiters, 0);
555
556         return operation;
557
558 err_request:
559         gb_operation_message_free(operation->request);
560 err_cache:
561         kmem_cache_free(gb_operation_cache, operation);
562
563         return NULL;
564 }
565
566 /*
567  * Create a new operation associated with the given connection.  The
568  * request and response sizes provided are the number of bytes
569  * required to hold the request/response payload only.  Both of
570  * these are allowed to be 0.  Note that 0x00 is reserved as an
571  * invalid operation type for all protocols, and this is enforced
572  * here.
573  */
574 struct gb_operation *
575 gb_operation_create_flags(struct gb_connection *connection,
576                           u8 type, size_t request_size,
577                           size_t response_size, unsigned long flags,
578                           gfp_t gfp)
579 {
580         struct gb_operation *operation;
581
582         if (WARN_ON_ONCE(type == GB_REQUEST_TYPE_INVALID))
583                 return NULL;
584         if (WARN_ON_ONCE(type & GB_MESSAGE_TYPE_RESPONSE))
585                 type &= ~GB_MESSAGE_TYPE_RESPONSE;
586
587         if (WARN_ON_ONCE(flags & ~GB_OPERATION_FLAG_USER_MASK))
588                 flags &= GB_OPERATION_FLAG_USER_MASK;
589
590         operation = gb_operation_create_common(connection, type,
591                                                request_size, response_size,
592                                                flags, gfp);
593         if (operation)
594                 trace_gb_operation_create(operation);
595
596         return operation;
597 }
598 EXPORT_SYMBOL_GPL(gb_operation_create_flags);
599
600 struct gb_operation *
601 gb_operation_create_core(struct gb_connection *connection,
602                          u8 type, size_t request_size,
603                          size_t response_size, unsigned long flags,
604                          gfp_t gfp)
605 {
606         struct gb_operation *operation;
607
608         flags |= GB_OPERATION_FLAG_CORE;
609
610         operation = gb_operation_create_common(connection, type,
611                                                request_size, response_size,
612                                                flags, gfp);
613         if (operation)
614                 trace_gb_operation_create_core(operation);
615
616         return operation;
617 }
618
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,
1193                                         int request_size,
1194                                         unsigned int timeout)
1195 {
1196         struct gb_operation *operation;
1197         int ret;
1198
1199         if (request_size && !request)
1200                 return -EINVAL;
1201
1202         operation = gb_operation_create_flags(connection, type,
1203                                               request_size, 0,
1204                                               GB_OPERATION_FLAG_UNIDIRECTIONAL,
1205                                               GFP_KERNEL);
1206         if (!operation)
1207                 return -ENOMEM;
1208
1209         if (request_size)
1210                 memcpy(operation->request->payload, request, request_size);
1211
1212         ret = gb_operation_request_send_sync_timeout(operation, timeout);
1213         if (ret) {
1214                 dev_err(&connection->hd->dev,
1215                         "%s: unidirectional operation of type 0x%02x failed: %d\n",
1216                         connection->name, type, ret);
1217         }
1218
1219         gb_operation_put(operation);
1220
1221         return ret;
1222 }
1223 EXPORT_SYMBOL_GPL(gb_operation_unidirectional_timeout);
1224
1225 int __init gb_operation_init(void)
1226 {
1227         gb_message_cache = kmem_cache_create("gb_message_cache",
1228                                              sizeof(struct gb_message), 0, 0,
1229                                              NULL);
1230         if (!gb_message_cache)
1231                 return -ENOMEM;
1232
1233         gb_operation_cache = kmem_cache_create("gb_operation_cache",
1234                                                sizeof(struct gb_operation), 0,
1235                                                0, NULL);
1236         if (!gb_operation_cache)
1237                 goto err_destroy_message_cache;
1238
1239         gb_operation_completion_wq = alloc_workqueue("greybus_completion",
1240                                                      0, 0);
1241         if (!gb_operation_completion_wq)
1242                 goto err_destroy_operation_cache;
1243
1244         return 0;
1245
1246 err_destroy_operation_cache:
1247         kmem_cache_destroy(gb_operation_cache);
1248         gb_operation_cache = NULL;
1249 err_destroy_message_cache:
1250         kmem_cache_destroy(gb_message_cache);
1251         gb_message_cache = NULL;
1252
1253         return -ENOMEM;
1254 }
1255
1256 void gb_operation_exit(void)
1257 {
1258         destroy_workqueue(gb_operation_completion_wq);
1259         gb_operation_completion_wq = NULL;
1260         kmem_cache_destroy(gb_operation_cache);
1261         gb_operation_cache = NULL;
1262         kmem_cache_destroy(gb_message_cache);
1263         gb_message_cache = NULL;
1264 }