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Subject[PATCH v3 0/3] crypto: hw_random - Add new Exynos RNG driver
Date
Hi,


This is a follow up of my questions around exynos-rng [1].

Changes since v2:
=================
1. Do not re-use random numbers for re-seed (neither for system resume
nor for periodic re-seed). Instead the driver will just generate new
random numbers (suggested by Stephan Müller).

Suspend path tested with suspend-to-freeze, not real suspend. Testing
on Trats2 would be welcomed.

Changes since v1:
=================
1. Re-work the code for seeding after system resume, following suggestions
and review by Stephan Müller.

2. Re-seed itself from time to time (every 100 ms), suggested by Stephan
Müller.

3. Use a define for retries (Bartlomiej Zolnierkiewicz).
4. Add some docs.


Description:
============
The existing exynos-rng has many issues. The most important one is that
it is a pseudo RNG device but uses hw_random interface which does not allow
proper seeding.

The RNG module on Exynos4 requires seeding. On newer SoCs (like Exynos5420)
it can seed itself from a true RNG. Converting the existing driver
to use TRNG would effectively drop support for Exynos4 and break
compatibility with existing users.

Instead I decided to convert it to crypto API. In the future I hope
to add support for seeding from TRNG module.

Tested with app [2].

Patches are independent. I will take the defconfig changes (2/3 and 3/3)
through samsung-soc tree.

Best regards,
Krzysztof

[1] https://www.spinics.net/lists/arm-kernel/msg569641.html
[2] https://www.spinics.net/lists/arm-kernel/msg571184.html


Krzysztof Kozlowski (3):
crypto: hw_random - Add new Exynos RNG driver
ARM: exynos_defconfig: Enable Exynos RNG and user-space crypto API
ARM: multi_v7_defconfig: Enable Exynos RNG and user-space crypto API

MAINTAINERS | 8 +
arch/arm/configs/exynos_defconfig | 6 +
arch/arm/configs/multi_v7_defconfig | 6 +
drivers/char/hw_random/Kconfig | 14 --
drivers/char/hw_random/Makefile | 1 -
drivers/char/hw_random/exynos-rng.c | 231 ---------------------
drivers/crypto/Kconfig | 15 ++
drivers/crypto/Makefile | 1 +
drivers/crypto/exynos-rng.c | 390 ++++++++++++++++++++++++++++++++++++
9 files changed, 426 insertions(+), 246 deletions(-)
delete mode 100644 drivers/char/hw_random/exynos-rng.c
create mode 100644 drivers/crypto/exynos-rng.c

--
2.9.3

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