hwrng: meson - add support for S4

For some Amlogic SOC's, mechanism to obtain random number
has been changed. For example, S4 now uses status bit waiting algo.

Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - remove not needed call to platform_set_drvdata

drvdata isn't used, therefore remove this call.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - use devm_clk_get_optional_enabled

Use devm_clk_get_optional_enabled() to simplify the code.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - remove unused member of struct meson_rng_data

Member pdev isn't used, remove it.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - Improve error handling for core clock

-ENOENT (ie. "there is no clock") is fine to ignore for an optional
clock, other values are not supposed to be ignored and should be
escalated to the caller (e.g. -EPROBE_DEFER). Ignore -ENOENT by using
devm_clk_get_optional().

While touching this code also add an error message for the fatal errors.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - use devm_platform_ioremap_resource() to simplify code

Use devm_platform_ioremap_resource() to simplify the code a bit.
This is detected by coccinelle.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - update with SPDX Licence identifier

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - add clock handling to driver

Add handling of RNG0 clock to the driver.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - Remove unneeded platform MODULE_ALIAS

The Amlogic Meson is a DT-only platform, which means the devices are
registered via OF and not using the legacy platform devices support.

So there's no need to have a MODULE_ALIAS("platform:meson-rng") since
the reported uevent MODALIAS to user-space will always be the OF one.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Kevin Hilman <khilman@baylibre.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - Fix module autoload for OF registration

If the driver is built as a module, autoload won't work because the module
alias information is not filled. So user-space can't match the registered
device with the corresponding module.

Export the module alias information using the MODULE_DEVICE_TABLE() macro.

Before this patch:

$ modinfo drivers/char/hw_random/meson-rng.ko | grep alias
alias: platform:meson-rng

After this patch:

$ modinfo drivers/char/hw_random/meson-rng.ko | grep alias
alias: platform:meson-rng
alias: of:N*T*Camlogic,meson-rngC*
alias: of:N*T*Camlogic,meson-rng

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: Remove check for max less than 4 bytes

HW RNG core never asks for data less than 4 bytes. The check whether max
is less than 4 bytes is unnecessary. Remove the check.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

hwrng: meson - Add Amlogic Meson Hardware Random Generator

Add support for the Amlogic Meson SoCs hardware random generator.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>