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From:   David Gstir <david@sigma-star.at>
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Subject: Can an ahash driver be used through shash API?
Message-Id: <729A4150-93A0-456B-B7AB-6D3A446E600E@sigma-star.at>
Date:   Wed, 29 May 2019 16:04:47 +0200
Cc:     linux-kernel@vger.kernel.org, Richard Weinberger <richard@nod.at>
To:     Linux Crypto Mailing List <linux-crypto@vger.kernel.org>
Sender: linux-crypto-owner@vger.kernel.org
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Hi!

I've done some testing with hardware acceleration of hash functions
and noticed that, when using the synchronous message digest API (shash),
some drivers are not usable. In my case the CAAM driver for SHA256.
Using the asynchronous interface (ahash), everything works as expected.
Looking at the driver source, the CAAM driver only implements the ahash
interface. 

I'm wondering if there a way to use an ahash driver through the shash interface?

I've seen that it does actually work the other way around, since 
crypto_init_shash_ops_async() in crypto/shash.c takes care of translating calls
from ahash to shash and that's how the *-generic drivers are usable through the
ahash API.

Thanks!
David