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crypto: doc - document crypto engine API

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Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Corentin LABBE 2018-01-26 20:15:29 +01:00 committed by Herbert Xu
parent 9a69b7ae79
commit ce09a6c042
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Documentation/crypto/crypto_engine.rst Normal file
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=============
CRYPTO ENGINE
=============
Overview
--------
The crypto engine API (CE), is a crypto queue manager.
Requirement
-----------
You have to put at start of your tfm_ctx the struct crypto_engine_ctx
struct your_tfm_ctx {
struct crypto_engine_ctx enginectx;
...
};
Why: Since CE manage only crypto_async_request, it cannot know the underlying
request_type and so have access only on the TFM.
So using container_of for accessing __ctx is impossible.
Furthermore, the crypto engine cannot know the "struct your_tfm_ctx",
so it must assume that crypto_engine_ctx is at start of it.
Order of operations
-------------------
You have to obtain a struct crypto_engine via crypto_engine_alloc_init().
And start it via crypto_engine_start().
Before transferring any request, you have to fill the enginectx.
- prepare_request: (taking a function pointer) If you need to do some processing before doing the request
- unprepare_request: (taking a function pointer) Undoing what's done in prepare_request
- do_one_request: (taking a function pointer) Do encryption for current request
Note: that those three functions get the crypto_async_request associated with the received request.
So your need to get the original request via container_of(areq, struct yourrequesttype_request, base);
When your driver receive a crypto_request, you have to transfer it to
the cryptoengine via one of:
- crypto_transfer_ablkcipher_request_to_engine()
- crypto_transfer_aead_request_to_engine()
- crypto_transfer_akcipher_request_to_engine()
- crypto_transfer_hash_request_to_engine()
- crypto_transfer_skcipher_request_to_engine()
At the end of the request process, a call to one of the following function is needed:
- crypto_finalize_ablkcipher_request
- crypto_finalize_aead_request
- crypto_finalize_akcipher_request
- crypto_finalize_hash_request
- crypto_finalize_skcipher_request