linux-kernel - [PATCH v3 0/4] Assorted changes for Exynos PRNG driver

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Date:   Tue, 12 Dec 2017 17:36:03 +0100
From:   Łukasz Stelmach <l.stelmach@...sung.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>, robh+dt@...nel.org,
        Stephan Mueller <smueller@...onox.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>,
        Kukjin Kim <kgene@...nel.org>, linux-crypto@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Łukasz Stelmach <l.stelmach@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: [PATCH v3 0/4] Assorted changes for Exynos PRNG driver

Hello,

This is a series of patches for exynos-rng driver I've decided to
create after adding support for Exynos5250+ chips. They do not
strictly depend on each other, but I think it is better to send them
as a single patch-set.

The driver requires appropriate DT configuration introduced in

    https://patchwork.kernel.org/patch/10106797/

Patch #1 Add support for PRNG in Exynos5250+ SoCs

Patch #2 Improve output performance by using memcpy() rather than a
custom function to retrieve random bytes from registers. Rearrange
the loop for polling the hardware.

Patch #3 Reseed the PRNG after reading 2^16 bytes. Simmilar approach
is implemented in DRBG. (Thanks Stephan Mueller)

Patch #4 Introduce locking to prevent simultaneous access to the
hardware from more than one thread/process.

Changes since v2:

- Remove changes in the loop polling the status register in
  exynos_rng_get_random(). Thanks Krzysztof Kozłowski.
- Remove the check for valid values of rng->type from
  exynos_rng_probe(). The function wouldn't be called with values other
  than mentioned in exynos_rng_dt_match array.
- Applied changes to the commit message of patch #3 requested by Stephan
  Mueller.

Changes since v1:

- Added Patch #4.
- Extended commit message for patch #3.
- Changed exynos_prng_type enum and a define according to Krzysztof Kozłowski's
  recommendations.
- Brought back cpu_relax() in a rearranged loop in
  exynos_rng_get_random().
- Moved an assignment of the read valuea away from an error path.
- Removed dev_info() reporting hardware presence from
  exynos_rng_probe().

Łukasz Stelmach (4):
  crypto: exynos - Support Exynos5250+ SoCs
  crypto: exynos - Improve performance of PRNG
  crypto: exynos - Reseed PRNG after generating 2^16 random bytes
  crypto: exynos - Introduce mutex to prevent concurrent access to
    hardware

 .../bindings/crypto/samsung,exynos-rng4.txt        |  4 +-
 drivers/crypto/exynos-rng.c                        | 94 ++++++++++++++--------
 2 files changed, 62 insertions(+), 36 deletions(-)

-- 
2.11.0