hwmon: (aspeed-pwm-tacho) mutex for tach reading
[platform/kernel/linux-rpi.git] / crypto / crypto_engine.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Handle async block request by crypto hardware engine.
4  *
5  * Copyright (C) 2016 Linaro, Inc.
6  *
7  * Author: Baolin Wang <baolin.wang@linaro.org>
8  */
9
10 #include <crypto/internal/aead.h>
11 #include <crypto/internal/akcipher.h>
12 #include <crypto/internal/engine.h>
13 #include <crypto/internal/hash.h>
14 #include <crypto/internal/kpp.h>
15 #include <crypto/internal/skcipher.h>
16 #include <linux/err.h>
17 #include <linux/delay.h>
18 #include <linux/device.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <uapi/linux/sched/types.h>
22 #include "internal.h"
23
24 #define CRYPTO_ENGINE_MAX_QLEN 10
25
26 /* Temporary algorithm flag used to indicate an updated driver. */
27 #define CRYPTO_ALG_ENGINE 0x200
28
29 struct crypto_engine_alg {
30         struct crypto_alg base;
31         struct crypto_engine_op op;
32 };
33
34 /**
35  * crypto_finalize_request - finalize one request if the request is done
36  * @engine: the hardware engine
37  * @req: the request need to be finalized
38  * @err: error number
39  */
40 static void crypto_finalize_request(struct crypto_engine *engine,
41                                     struct crypto_async_request *req, int err)
42 {
43         unsigned long flags;
44
45         /*
46          * If hardware cannot enqueue more requests
47          * and retry mechanism is not supported
48          * make sure we are completing the current request
49          */
50         if (!engine->retry_support) {
51                 spin_lock_irqsave(&engine->queue_lock, flags);
52                 if (engine->cur_req == req) {
53                         engine->cur_req = NULL;
54                 }
55                 spin_unlock_irqrestore(&engine->queue_lock, flags);
56         }
57
58         lockdep_assert_in_softirq();
59         crypto_request_complete(req, err);
60
61         kthread_queue_work(engine->kworker, &engine->pump_requests);
62 }
63
64 /**
65  * crypto_pump_requests - dequeue one request from engine queue to process
66  * @engine: the hardware engine
67  * @in_kthread: true if we are in the context of the request pump thread
68  *
69  * This function checks if there is any request in the engine queue that
70  * needs processing and if so call out to the driver to initialize hardware
71  * and handle each request.
72  */
73 static void crypto_pump_requests(struct crypto_engine *engine,
74                                  bool in_kthread)
75 {
76         struct crypto_async_request *async_req, *backlog;
77         struct crypto_engine_alg *alg;
78         struct crypto_engine_op *op;
79         unsigned long flags;
80         bool was_busy = false;
81         int ret;
82
83         spin_lock_irqsave(&engine->queue_lock, flags);
84
85         /* Make sure we are not already running a request */
86         if (!engine->retry_support && engine->cur_req)
87                 goto out;
88
89         /* If another context is idling then defer */
90         if (engine->idling) {
91                 kthread_queue_work(engine->kworker, &engine->pump_requests);
92                 goto out;
93         }
94
95         /* Check if the engine queue is idle */
96         if (!crypto_queue_len(&engine->queue) || !engine->running) {
97                 if (!engine->busy)
98                         goto out;
99
100                 /* Only do teardown in the thread */
101                 if (!in_kthread) {
102                         kthread_queue_work(engine->kworker,
103                                            &engine->pump_requests);
104                         goto out;
105                 }
106
107                 engine->busy = false;
108                 engine->idling = true;
109                 spin_unlock_irqrestore(&engine->queue_lock, flags);
110
111                 if (engine->unprepare_crypt_hardware &&
112                     engine->unprepare_crypt_hardware(engine))
113                         dev_err(engine->dev, "failed to unprepare crypt hardware\n");
114
115                 spin_lock_irqsave(&engine->queue_lock, flags);
116                 engine->idling = false;
117                 goto out;
118         }
119
120 start_request:
121         /* Get the fist request from the engine queue to handle */
122         backlog = crypto_get_backlog(&engine->queue);
123         async_req = crypto_dequeue_request(&engine->queue);
124         if (!async_req)
125                 goto out;
126
127         /*
128          * If hardware doesn't support the retry mechanism,
129          * keep track of the request we are processing now.
130          * We'll need it on completion (crypto_finalize_request).
131          */
132         if (!engine->retry_support)
133                 engine->cur_req = async_req;
134
135         if (engine->busy)
136                 was_busy = true;
137         else
138                 engine->busy = true;
139
140         spin_unlock_irqrestore(&engine->queue_lock, flags);
141
142         /* Until here we get the request need to be encrypted successfully */
143         if (!was_busy && engine->prepare_crypt_hardware) {
144                 ret = engine->prepare_crypt_hardware(engine);
145                 if (ret) {
146                         dev_err(engine->dev, "failed to prepare crypt hardware\n");
147                         goto req_err_1;
148                 }
149         }
150
151         if (async_req->tfm->__crt_alg->cra_flags & CRYPTO_ALG_ENGINE) {
152                 alg = container_of(async_req->tfm->__crt_alg,
153                                    struct crypto_engine_alg, base);
154                 op = &alg->op;
155         } else {
156                 dev_err(engine->dev, "failed to do request\n");
157                 ret = -EINVAL;
158                 goto req_err_1;
159         }
160
161         ret = op->do_one_request(engine, async_req);
162
163         /* Request unsuccessfully executed by hardware */
164         if (ret < 0) {
165                 /*
166                  * If hardware queue is full (-ENOSPC), requeue request
167                  * regardless of backlog flag.
168                  * Otherwise, unprepare and complete the request.
169                  */
170                 if (!engine->retry_support ||
171                     (ret != -ENOSPC)) {
172                         dev_err(engine->dev,
173                                 "Failed to do one request from queue: %d\n",
174                                 ret);
175                         goto req_err_1;
176                 }
177                 spin_lock_irqsave(&engine->queue_lock, flags);
178                 /*
179                  * If hardware was unable to execute request, enqueue it
180                  * back in front of crypto-engine queue, to keep the order
181                  * of requests.
182                  */
183                 crypto_enqueue_request_head(&engine->queue, async_req);
184
185                 kthread_queue_work(engine->kworker, &engine->pump_requests);
186                 goto out;
187         }
188
189         goto retry;
190
191 req_err_1:
192         crypto_request_complete(async_req, ret);
193
194 retry:
195         if (backlog)
196                 crypto_request_complete(backlog, -EINPROGRESS);
197
198         /* If retry mechanism is supported, send new requests to engine */
199         if (engine->retry_support) {
200                 spin_lock_irqsave(&engine->queue_lock, flags);
201                 goto start_request;
202         }
203         return;
204
205 out:
206         spin_unlock_irqrestore(&engine->queue_lock, flags);
207
208         /*
209          * Batch requests is possible only if
210          * hardware can enqueue multiple requests
211          */
212         if (engine->do_batch_requests) {
213                 ret = engine->do_batch_requests(engine);
214                 if (ret)
215                         dev_err(engine->dev, "failed to do batch requests: %d\n",
216                                 ret);
217         }
218
219         return;
220 }
221
222 static void crypto_pump_work(struct kthread_work *work)
223 {
224         struct crypto_engine *engine =
225                 container_of(work, struct crypto_engine, pump_requests);
226
227         crypto_pump_requests(engine, true);
228 }
229
230 /**
231  * crypto_transfer_request - transfer the new request into the engine queue
232  * @engine: the hardware engine
233  * @req: the request need to be listed into the engine queue
234  * @need_pump: indicates whether queue the pump of request to kthread_work
235  */
236 static int crypto_transfer_request(struct crypto_engine *engine,
237                                    struct crypto_async_request *req,
238                                    bool need_pump)
239 {
240         unsigned long flags;
241         int ret;
242
243         spin_lock_irqsave(&engine->queue_lock, flags);
244
245         if (!engine->running) {
246                 spin_unlock_irqrestore(&engine->queue_lock, flags);
247                 return -ESHUTDOWN;
248         }
249
250         ret = crypto_enqueue_request(&engine->queue, req);
251
252         if (!engine->busy && need_pump)
253                 kthread_queue_work(engine->kworker, &engine->pump_requests);
254
255         spin_unlock_irqrestore(&engine->queue_lock, flags);
256         return ret;
257 }
258
259 /**
260  * crypto_transfer_request_to_engine - transfer one request to list
261  * into the engine queue
262  * @engine: the hardware engine
263  * @req: the request need to be listed into the engine queue
264  */
265 static int crypto_transfer_request_to_engine(struct crypto_engine *engine,
266                                              struct crypto_async_request *req)
267 {
268         return crypto_transfer_request(engine, req, true);
269 }
270
271 /**
272  * crypto_transfer_aead_request_to_engine - transfer one aead_request
273  * to list into the engine queue
274  * @engine: the hardware engine
275  * @req: the request need to be listed into the engine queue
276  */
277 int crypto_transfer_aead_request_to_engine(struct crypto_engine *engine,
278                                            struct aead_request *req)
279 {
280         return crypto_transfer_request_to_engine(engine, &req->base);
281 }
282 EXPORT_SYMBOL_GPL(crypto_transfer_aead_request_to_engine);
283
284 /**
285  * crypto_transfer_akcipher_request_to_engine - transfer one akcipher_request
286  * to list into the engine queue
287  * @engine: the hardware engine
288  * @req: the request need to be listed into the engine queue
289  */
290 int crypto_transfer_akcipher_request_to_engine(struct crypto_engine *engine,
291                                                struct akcipher_request *req)
292 {
293         return crypto_transfer_request_to_engine(engine, &req->base);
294 }
295 EXPORT_SYMBOL_GPL(crypto_transfer_akcipher_request_to_engine);
296
297 /**
298  * crypto_transfer_hash_request_to_engine - transfer one ahash_request
299  * to list into the engine queue
300  * @engine: the hardware engine
301  * @req: the request need to be listed into the engine queue
302  */
303 int crypto_transfer_hash_request_to_engine(struct crypto_engine *engine,
304                                            struct ahash_request *req)
305 {
306         return crypto_transfer_request_to_engine(engine, &req->base);
307 }
308 EXPORT_SYMBOL_GPL(crypto_transfer_hash_request_to_engine);
309
310 /**
311  * crypto_transfer_kpp_request_to_engine - transfer one kpp_request to list
312  * into the engine queue
313  * @engine: the hardware engine
314  * @req: the request need to be listed into the engine queue
315  */
316 int crypto_transfer_kpp_request_to_engine(struct crypto_engine *engine,
317                                           struct kpp_request *req)
318 {
319         return crypto_transfer_request_to_engine(engine, &req->base);
320 }
321 EXPORT_SYMBOL_GPL(crypto_transfer_kpp_request_to_engine);
322
323 /**
324  * crypto_transfer_skcipher_request_to_engine - transfer one skcipher_request
325  * to list into the engine queue
326  * @engine: the hardware engine
327  * @req: the request need to be listed into the engine queue
328  */
329 int crypto_transfer_skcipher_request_to_engine(struct crypto_engine *engine,
330                                                struct skcipher_request *req)
331 {
332         return crypto_transfer_request_to_engine(engine, &req->base);
333 }
334 EXPORT_SYMBOL_GPL(crypto_transfer_skcipher_request_to_engine);
335
336 /**
337  * crypto_finalize_aead_request - finalize one aead_request if
338  * the request is done
339  * @engine: the hardware engine
340  * @req: the request need to be finalized
341  * @err: error number
342  */
343 void crypto_finalize_aead_request(struct crypto_engine *engine,
344                                   struct aead_request *req, int err)
345 {
346         return crypto_finalize_request(engine, &req->base, err);
347 }
348 EXPORT_SYMBOL_GPL(crypto_finalize_aead_request);
349
350 /**
351  * crypto_finalize_akcipher_request - finalize one akcipher_request if
352  * the request is done
353  * @engine: the hardware engine
354  * @req: the request need to be finalized
355  * @err: error number
356  */
357 void crypto_finalize_akcipher_request(struct crypto_engine *engine,
358                                       struct akcipher_request *req, int err)
359 {
360         return crypto_finalize_request(engine, &req->base, err);
361 }
362 EXPORT_SYMBOL_GPL(crypto_finalize_akcipher_request);
363
364 /**
365  * crypto_finalize_hash_request - finalize one ahash_request if
366  * the request is done
367  * @engine: the hardware engine
368  * @req: the request need to be finalized
369  * @err: error number
370  */
371 void crypto_finalize_hash_request(struct crypto_engine *engine,
372                                   struct ahash_request *req, int err)
373 {
374         return crypto_finalize_request(engine, &req->base, err);
375 }
376 EXPORT_SYMBOL_GPL(crypto_finalize_hash_request);
377
378 /**
379  * crypto_finalize_kpp_request - finalize one kpp_request if the request is done
380  * @engine: the hardware engine
381  * @req: the request need to be finalized
382  * @err: error number
383  */
384 void crypto_finalize_kpp_request(struct crypto_engine *engine,
385                                  struct kpp_request *req, int err)
386 {
387         return crypto_finalize_request(engine, &req->base, err);
388 }
389 EXPORT_SYMBOL_GPL(crypto_finalize_kpp_request);
390
391 /**
392  * crypto_finalize_skcipher_request - finalize one skcipher_request if
393  * the request is done
394  * @engine: the hardware engine
395  * @req: the request need to be finalized
396  * @err: error number
397  */
398 void crypto_finalize_skcipher_request(struct crypto_engine *engine,
399                                       struct skcipher_request *req, int err)
400 {
401         return crypto_finalize_request(engine, &req->base, err);
402 }
403 EXPORT_SYMBOL_GPL(crypto_finalize_skcipher_request);
404
405 /**
406  * crypto_engine_start - start the hardware engine
407  * @engine: the hardware engine need to be started
408  *
409  * Return 0 on success, else on fail.
410  */
411 int crypto_engine_start(struct crypto_engine *engine)
412 {
413         unsigned long flags;
414
415         spin_lock_irqsave(&engine->queue_lock, flags);
416
417         if (engine->running || engine->busy) {
418                 spin_unlock_irqrestore(&engine->queue_lock, flags);
419                 return -EBUSY;
420         }
421
422         engine->running = true;
423         spin_unlock_irqrestore(&engine->queue_lock, flags);
424
425         kthread_queue_work(engine->kworker, &engine->pump_requests);
426
427         return 0;
428 }
429 EXPORT_SYMBOL_GPL(crypto_engine_start);
430
431 /**
432  * crypto_engine_stop - stop the hardware engine
433  * @engine: the hardware engine need to be stopped
434  *
435  * Return 0 on success, else on fail.
436  */
437 int crypto_engine_stop(struct crypto_engine *engine)
438 {
439         unsigned long flags;
440         unsigned int limit = 500;
441         int ret = 0;
442
443         spin_lock_irqsave(&engine->queue_lock, flags);
444
445         /*
446          * If the engine queue is not empty or the engine is on busy state,
447          * we need to wait for a while to pump the requests of engine queue.
448          */
449         while ((crypto_queue_len(&engine->queue) || engine->busy) && limit--) {
450                 spin_unlock_irqrestore(&engine->queue_lock, flags);
451                 msleep(20);
452                 spin_lock_irqsave(&engine->queue_lock, flags);
453         }
454
455         if (crypto_queue_len(&engine->queue) || engine->busy)
456                 ret = -EBUSY;
457         else
458                 engine->running = false;
459
460         spin_unlock_irqrestore(&engine->queue_lock, flags);
461
462         if (ret)
463                 dev_warn(engine->dev, "could not stop engine\n");
464
465         return ret;
466 }
467 EXPORT_SYMBOL_GPL(crypto_engine_stop);
468
469 /**
470  * crypto_engine_alloc_init_and_set - allocate crypto hardware engine structure
471  * and initialize it by setting the maximum number of entries in the software
472  * crypto-engine queue.
473  * @dev: the device attached with one hardware engine
474  * @retry_support: whether hardware has support for retry mechanism
475  * @cbk_do_batch: pointer to a callback function to be invoked when executing
476  *                a batch of requests.
477  *                This has the form:
478  *                callback(struct crypto_engine *engine)
479  *                where:
480  *                engine: the crypto engine structure.
481  * @rt: whether this queue is set to run as a realtime task
482  * @qlen: maximum size of the crypto-engine queue
483  *
484  * This must be called from context that can sleep.
485  * Return: the crypto engine structure on success, else NULL.
486  */
487 struct crypto_engine *crypto_engine_alloc_init_and_set(struct device *dev,
488                                                        bool retry_support,
489                                                        int (*cbk_do_batch)(struct crypto_engine *engine),
490                                                        bool rt, int qlen)
491 {
492         struct crypto_engine *engine;
493
494         if (!dev)
495                 return NULL;
496
497         engine = devm_kzalloc(dev, sizeof(*engine), GFP_KERNEL);
498         if (!engine)
499                 return NULL;
500
501         engine->dev = dev;
502         engine->rt = rt;
503         engine->running = false;
504         engine->busy = false;
505         engine->idling = false;
506         engine->retry_support = retry_support;
507         engine->priv_data = dev;
508         /*
509          * Batch requests is possible only if
510          * hardware has support for retry mechanism.
511          */
512         engine->do_batch_requests = retry_support ? cbk_do_batch : NULL;
513
514         snprintf(engine->name, sizeof(engine->name),
515                  "%s-engine", dev_name(dev));
516
517         crypto_init_queue(&engine->queue, qlen);
518         spin_lock_init(&engine->queue_lock);
519
520         engine->kworker = kthread_create_worker(0, "%s", engine->name);
521         if (IS_ERR(engine->kworker)) {
522                 dev_err(dev, "failed to create crypto request pump task\n");
523                 return NULL;
524         }
525         kthread_init_work(&engine->pump_requests, crypto_pump_work);
526
527         if (engine->rt) {
528                 dev_info(dev, "will run requests pump with realtime priority\n");
529                 sched_set_fifo(engine->kworker->task);
530         }
531
532         return engine;
533 }
534 EXPORT_SYMBOL_GPL(crypto_engine_alloc_init_and_set);
535
536 /**
537  * crypto_engine_alloc_init - allocate crypto hardware engine structure and
538  * initialize it.
539  * @dev: the device attached with one hardware engine
540  * @rt: whether this queue is set to run as a realtime task
541  *
542  * This must be called from context that can sleep.
543  * Return: the crypto engine structure on success, else NULL.
544  */
545 struct crypto_engine *crypto_engine_alloc_init(struct device *dev, bool rt)
546 {
547         return crypto_engine_alloc_init_and_set(dev, false, NULL, rt,
548                                                 CRYPTO_ENGINE_MAX_QLEN);
549 }
550 EXPORT_SYMBOL_GPL(crypto_engine_alloc_init);
551
552 /**
553  * crypto_engine_exit - free the resources of hardware engine when exit
554  * @engine: the hardware engine need to be freed
555  *
556  * Return 0 for success.
557  */
558 int crypto_engine_exit(struct crypto_engine *engine)
559 {
560         int ret;
561
562         ret = crypto_engine_stop(engine);
563         if (ret)
564                 return ret;
565
566         kthread_destroy_worker(engine->kworker);
567
568         return 0;
569 }
570 EXPORT_SYMBOL_GPL(crypto_engine_exit);
571
572 int crypto_engine_register_aead(struct aead_engine_alg *alg)
573 {
574         if (!alg->op.do_one_request)
575                 return -EINVAL;
576
577         alg->base.base.cra_flags |= CRYPTO_ALG_ENGINE;
578
579         return crypto_register_aead(&alg->base);
580 }
581 EXPORT_SYMBOL_GPL(crypto_engine_register_aead);
582
583 void crypto_engine_unregister_aead(struct aead_engine_alg *alg)
584 {
585         crypto_unregister_aead(&alg->base);
586 }
587 EXPORT_SYMBOL_GPL(crypto_engine_unregister_aead);
588
589 int crypto_engine_register_aeads(struct aead_engine_alg *algs, int count)
590 {
591         int i, ret;
592
593         for (i = 0; i < count; i++) {
594                 ret = crypto_engine_register_aead(&algs[i]);
595                 if (ret)
596                         goto err;
597         }
598
599         return 0;
600
601 err:
602         crypto_engine_unregister_aeads(algs, i);
603
604         return ret;
605 }
606 EXPORT_SYMBOL_GPL(crypto_engine_register_aeads);
607
608 void crypto_engine_unregister_aeads(struct aead_engine_alg *algs, int count)
609 {
610         int i;
611
612         for (i = count - 1; i >= 0; --i)
613                 crypto_engine_unregister_aead(&algs[i]);
614 }
615 EXPORT_SYMBOL_GPL(crypto_engine_unregister_aeads);
616
617 int crypto_engine_register_ahash(struct ahash_engine_alg *alg)
618 {
619         if (!alg->op.do_one_request)
620                 return -EINVAL;
621
622         alg->base.halg.base.cra_flags |= CRYPTO_ALG_ENGINE;
623
624         return crypto_register_ahash(&alg->base);
625 }
626 EXPORT_SYMBOL_GPL(crypto_engine_register_ahash);
627
628 void crypto_engine_unregister_ahash(struct ahash_engine_alg *alg)
629 {
630         crypto_unregister_ahash(&alg->base);
631 }
632 EXPORT_SYMBOL_GPL(crypto_engine_unregister_ahash);
633
634 int crypto_engine_register_ahashes(struct ahash_engine_alg *algs, int count)
635 {
636         int i, ret;
637
638         for (i = 0; i < count; i++) {
639                 ret = crypto_engine_register_ahash(&algs[i]);
640                 if (ret)
641                         goto err;
642         }
643
644         return 0;
645
646 err:
647         crypto_engine_unregister_ahashes(algs, i);
648
649         return ret;
650 }
651 EXPORT_SYMBOL_GPL(crypto_engine_register_ahashes);
652
653 void crypto_engine_unregister_ahashes(struct ahash_engine_alg *algs,
654                                       int count)
655 {
656         int i;
657
658         for (i = count - 1; i >= 0; --i)
659                 crypto_engine_unregister_ahash(&algs[i]);
660 }
661 EXPORT_SYMBOL_GPL(crypto_engine_unregister_ahashes);
662
663 int crypto_engine_register_akcipher(struct akcipher_engine_alg *alg)
664 {
665         if (!alg->op.do_one_request)
666                 return -EINVAL;
667
668         alg->base.base.cra_flags |= CRYPTO_ALG_ENGINE;
669
670         return crypto_register_akcipher(&alg->base);
671 }
672 EXPORT_SYMBOL_GPL(crypto_engine_register_akcipher);
673
674 void crypto_engine_unregister_akcipher(struct akcipher_engine_alg *alg)
675 {
676         crypto_unregister_akcipher(&alg->base);
677 }
678 EXPORT_SYMBOL_GPL(crypto_engine_unregister_akcipher);
679
680 int crypto_engine_register_kpp(struct kpp_engine_alg *alg)
681 {
682         if (!alg->op.do_one_request)
683                 return -EINVAL;
684
685         alg->base.base.cra_flags |= CRYPTO_ALG_ENGINE;
686
687         return crypto_register_kpp(&alg->base);
688 }
689 EXPORT_SYMBOL_GPL(crypto_engine_register_kpp);
690
691 void crypto_engine_unregister_kpp(struct kpp_engine_alg *alg)
692 {
693         crypto_unregister_kpp(&alg->base);
694 }
695 EXPORT_SYMBOL_GPL(crypto_engine_unregister_kpp);
696
697 int crypto_engine_register_skcipher(struct skcipher_engine_alg *alg)
698 {
699         if (!alg->op.do_one_request)
700                 return -EINVAL;
701
702         alg->base.base.cra_flags |= CRYPTO_ALG_ENGINE;
703
704         return crypto_register_skcipher(&alg->base);
705 }
706 EXPORT_SYMBOL_GPL(crypto_engine_register_skcipher);
707
708 void crypto_engine_unregister_skcipher(struct skcipher_engine_alg *alg)
709 {
710         return crypto_unregister_skcipher(&alg->base);
711 }
712 EXPORT_SYMBOL_GPL(crypto_engine_unregister_skcipher);
713
714 int crypto_engine_register_skciphers(struct skcipher_engine_alg *algs,
715                                      int count)
716 {
717         int i, ret;
718
719         for (i = 0; i < count; i++) {
720                 ret = crypto_engine_register_skcipher(&algs[i]);
721                 if (ret)
722                         goto err;
723         }
724
725         return 0;
726
727 err:
728         crypto_engine_unregister_skciphers(algs, i);
729
730         return ret;
731 }
732 EXPORT_SYMBOL_GPL(crypto_engine_register_skciphers);
733
734 void crypto_engine_unregister_skciphers(struct skcipher_engine_alg *algs,
735                                         int count)
736 {
737         int i;
738
739         for (i = count - 1; i >= 0; --i)
740                 crypto_engine_unregister_skcipher(&algs[i]);
741 }
742 EXPORT_SYMBOL_GPL(crypto_engine_unregister_skciphers);
743
744 MODULE_LICENSE("GPL");
745 MODULE_DESCRIPTION("Crypto hardware engine framework");