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path: root/drivers/crypto/exynos-rng.c
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2018-04-28crypto: drivers - simplify getting .drvdataWolfram Sang
We should get drvdata from struct device directly. Going via platform_device is an unneeded step back and forth. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-01-18crypto: exynos-rng - Add SPDX license identifier and correct module licenseKrzysztof Kozlowski
Replace GPL license statement with SPDX GPL-2.0 license identifier and correct the module license to GPLv2. The license itself was a generic GPL because of copy-and-paste from old drivers/char/hw_random/exynos-rng.c driver (on which this was based on). However the module license indicated GPL-2.0 or later. GPL-2.0 was intended by author so fix up this mess. Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-12-22crypto: exynos - Introduce mutex to prevent concurrent access to hardwareŁukasz Stelmach
Hardware operations like reading random numbers and setting a seed need to be conducted in a single thread. Therefore a mutex is required to prevent multiple threads (processes) from accessing the hardware at the same time. The sequence of mutex_lock() and mutex_unlock() in the exynos_rng_reseed() function enables switching between different threads waiting for the driver to generate random numbers for them. Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-12-22crypto: exynos - Reseed PRNG after generating 2^16 random bytesŁukasz Stelmach
Reseed PRNG after reading 65 kB of randomness. Although this may reduce performance, in most cases the loss is not noticeable. Also the time based threshold for reseeding is changed to one second. Reseeding is performed whenever either limit is exceeded. Reseeding of a PRNG does not increase entropy, but it helps preventing backtracking the internal state of the device from its output sequence, and hence, prevents potential attacker from predicting numbers to be generated. Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com> Reviewed-by: Stephan Mueller <smueller@chronox.de> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-12-22crypto: exynos - Improve performance of PRNGŁukasz Stelmach
Use memcpy_fromio() instead of custom exynos_rng_copy_random() function to retrieve generated numbers from the registers of PRNG. Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-12-22crypto: exynos - Support Exynos5250+ SoCsŁukasz Stelmach
Add support for PRNG in Exynos5250+ SoCs. Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-12-22crypto: exynos - Icrease the priority of the driverŁukasz Stelmach
exynos-rng is one of many implementations of stdrng. With priority as low as 100 it isn't selected, if software implementations (DRBG) are available. The value 300 was selected to give the PRNG priority before software implementations, but allow them to be selected in FIPS-mode (fips=1 in the kernel command line). Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com> Reviewed-by: Stephan Mueller <smueller@chronox.de> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-04-21crypto: exynos - Add new Exynos RNG driverKrzysztof Kozlowski
Replace existing hw_ranndom/exynos-rng driver with a new, reworked one. This is a driver for pseudo random number generator block which on Exynos4 chipsets must be seeded with some value. On newer Exynos5420 chipsets it might seed itself from true random number generator block but this is not implemented yet. New driver is a complete rework to use the crypto ALGAPI instead of hw_random API. Rationale for the change: 1. hw_random interface is for true RNG devices. 2. The old driver was seeding itself with jiffies which is not a reliable source for randomness. 3. Device generates five random 32-bit numbers in each pass but old driver was returning only one 32-bit number thus its performance was reduced. Compatibility with DeviceTree bindings is preserved. New driver does not use runtime power management but manually enables and disables the clock when needed. This is preferred approach because using runtime PM just to toggle clock is huge overhead. Another difference is reseeding itself with generated random data periodically and during resuming from system suspend (previously driver was re-seeding itself again with jiffies). Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> Reviewed-by: Stephan Müller <smueller@chronox.de> Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>