The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.
To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().
Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
'type' is an enum, thus cast of pointer on 64-bit compile test with W=1
causes:
exynos-rng.c:280:14: error: cast to smaller integer type 'enum exynos_prng_type' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use devm_platform_ioremap_resource() to simplify the code a bit.
This is detected by coccinelle.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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>
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>
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>
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>
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>
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>
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>
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>
