On Fri, 2021-03-05 at 08:01 +0100, Álvaro Fernández Rojas wrote:
> BCM6368 devices need to reset the IPSEC controller in order to generate true
> random numbers.
>
> This is what BCM6368 produces without a reset:
> root@OpenWrt:/# cat /dev/hwrng | rngtest -c 1000
> rngtest 6.10
> Copyright (c) 2004 by Henrique de Moraes Holschuh
> This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>
> rngtest: starting FIPS tests...
> rngtest: bits received from input: 20000032
> rngtest: FIPS 140-2 successes: 0
> rngtest: FIPS 140-2 failures: 1000
> rngtest: FIPS 140-2(2001-10-10) Monobit: 2
> rngtest: FIPS 140-2(2001-10-10) Poker: 1000
> rngtest: FIPS 140-2(2001-10-10) Runs: 1000
> rngtest: FIPS 140-2(2001-10-10) Long run: 30
> rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
> rngtest: input channel speed: (min=37.253; avg=320.827; max=635.783)Mibits/s
> rngtest: FIPS tests speed: (min=12.141; avg=15.034; max=16.428)Mibits/s
> rngtest: Program run time: 1336176 microseconds
>
> Signed-off-by: Álvaro Fernández Rojas <noltari@xxxxxxxxx>
Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
regards
Philipp
> ---
> v6: fix commit description.
> v5: remove reset_control_rearm().
> v4: add reset_control_rearm().
> v3: no changes.
> v2: no changes.
>
> drivers/char/hw_random/bcm2835-rng.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c
> index be5be395b341..e7dd457e9b22 100644
> --- a/drivers/char/hw_random/bcm2835-rng.c
> +++ b/drivers/char/hw_random/bcm2835-rng.c
> @@ -13,6 +13,7 @@
> #include <linux/platform_device.h>
> #include <linux/printk.h>
> #include <linux/clk.h>
> +#include <linux/reset.h>
>
> #define RNG_CTRL 0x0
> #define RNG_STATUS 0x4
> @@ -32,6 +33,7 @@ struct bcm2835_rng_priv {
> void __iomem *base;
> bool mask_interrupts;
> struct clk *clk;
> + struct reset_control *reset;
> };
>
> static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng)
> @@ -92,6 +94,10 @@ static int bcm2835_rng_init(struct hwrng *rng)
> if (ret)
> return ret;
>
> + ret = reset_control_reset(priv->reset);
> + if (ret)
> + return ret;
> +
> if (priv->mask_interrupts) {
> /* mask the interrupt */
> val = rng_readl(priv, RNG_INT_MASK);
> @@ -156,6 +162,10 @@ static int bcm2835_rng_probe(struct platform_device *pdev)
> if (IS_ERR(priv->clk))
> return PTR_ERR(priv->clk);
>
> + priv->reset = devm_reset_control_get_optional_exclusive(dev, NULL);
> + if (IS_ERR(priv->reset))
> + return PTR_ERR(priv->reset);
> +
> priv->rng.name = pdev->name;
> priv->rng.init = bcm2835_rng_init;
> priv->rng.read = bcm2835_rng_read;
