2017-05-17 22:29:10

by Rick Altherr

Subject: [PATCH v1 1/2] dt-bindings: timeriomem_rng: Add entropy quality property

Signed-off-by: Rick Altherr <[email protected]>
---

Documentation/devicetree/bindings/rng/timeriomem_rng.txt | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/rng/timeriomem_rng.txt b/Documentation/devicetree/bindings/rng/timeriomem_rng.txt
index 6616d15866a3..214940093b55 100644
--- a/Documentation/devicetree/bindings/rng/timeriomem_rng.txt
+++ b/Documentation/devicetree/bindings/rng/timeriomem_rng.txt
@@ -5,6 +5,13 @@ Required properties:
- reg : base address to sample from
- period : wait time in microseconds to use between samples

+Optional properties:
+- quality : estimated number of bits of true entropy per 1024 bits read from the
+ rng. Defaults to zero which causes the kernel's default quality to
+ be used instead. Note that the default quality is usually zero
+ which disables using this rng to automatically fill the kernel's
+ entropy pool.
+
N.B. currently 'reg' must be four bytes wide and aligned

Example:
--
2.13.0.303.g4ebf302169-goog

2017-05-17 22:29:11

by Rick Altherr

Subject: [PATCH v1 2/2] hw_random: timeriomem_rng: Allow setting RNG quality from platform data

When a hw_random device's quality is non-zero, it will automatically be
used to fill the kernel's entropy pool. Since timeriomem_rng is used by
many different devices, the quality needs to be provided by platform
data or device tree.

Signed-off-by: Rick Altherr <[email protected]>
---

drivers/char/hw_random/timeriomem-rng.c | 7 +++++++
include/linux/timeriomem-rng.h | 3 +++
2 files changed, 10 insertions(+)

diff --git a/drivers/char/hw_random/timeriomem-rng.c b/drivers/char/hw_random/timeriomem-rng.c
index a0faa5f05deb..03ff5483d865 100644
--- a/drivers/char/hw_random/timeriomem-rng.c
+++ b/drivers/char/hw_random/timeriomem-rng.c
@@ -151,8 +151,15 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
dev_err(&pdev->dev, "missing period\n");
return -EINVAL;
}
+
+ if (!of_property_read_u32(pdev->dev.of_node,
+ "quality", &i))
+ priv->rng_ops.quality = i;
+ else
+ priv->rng_ops.quality = 0;
} else {
period = pdata->period;
+ priv->rng_ops.quality = pdata->quality;
}

priv->period = ns_to_ktime(period * NSEC_PER_USEC);
diff --git a/include/linux/timeriomem-rng.h b/include/linux/timeriomem-rng.h
index 46eb27ddbfab..320f743bf06b 100644
--- a/include/linux/timeriomem-rng.h
+++ b/include/linux/timeriomem-rng.h
@@ -13,4 +13,7 @@ struct timeriomem_rng_data {

/* measures in usecs */
unsigned int period;
+
+ /* bits of entropy per 1000 bits read */
+ unsigned int quality;
};
--
2.13.0.303.g4ebf302169-goog

2017-05-18 05:43:30

by PrasannaKumar Muralidharan

Subject: Re: [PATCH v1 2/2] hw_random: timeriomem_rng: Allow setting RNG quality from platform data

Hi Rick,

Minor comment below.

On 18 May 2017 at 03:59, Rick Altherr <[email protected]> wrote:
> When a hw_random device's quality is non-zero, it will automatically be
> used to fill the kernel's entropy pool. Since timeriomem_rng is used by
> many different devices, the quality needs to be provided by platform
> data or device tree.
>
> Signed-off-by: Rick Altherr <[email protected]>
> ---
>
> drivers/char/hw_random/timeriomem-rng.c | 7 +++++++
> include/linux/timeriomem-rng.h | 3 +++
> 2 files changed, 10 insertions(+)
>
> diff --git a/drivers/char/hw_random/timeriomem-rng.c b/drivers/char/hw_random/timeriomem-rng.c
> index a0faa5f05deb..03ff5483d865 100644
> --- a/drivers/char/hw_random/timeriomem-rng.c
> +++ b/drivers/char/hw_random/timeriomem-rng.c
> @@ -151,8 +151,15 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
> dev_err(&pdev->dev, "missing period\n");
> return -EINVAL;
> }
> +
> + if (!of_property_read_u32(pdev->dev.of_node,
> + "quality", &i))
> + priv->rng_ops.quality = i;
> + else
> + priv->rng_ops.quality = 0;
> } else {
> period = pdata->period;
> + priv->rng_ops.quality = pdata->quality;
> }
>
> priv->period = ns_to_ktime(period * NSEC_PER_USEC);
> diff --git a/include/linux/timeriomem-rng.h b/include/linux/timeriomem-rng.h
> index 46eb27ddbfab..320f743bf06b 100644
> --- a/include/linux/timeriomem-rng.h
> +++ b/include/linux/timeriomem-rng.h
> @@ -13,4 +13,7 @@ struct timeriomem_rng_data {
>
> /* measures in usecs */
> unsigned int period;
> +
> + /* bits of entropy per 1000 bits read */

Your dt-bindings patch says 'entropy per 1024 bits'. Please be consistent.

> + unsigned int quality;
> };
> --
> 2.13.0.303.g4ebf302169-goog
>

Regards,
PrasannaKumar

2017-05-23 14:06:18

by Rob Herring (Arm)

Subject: Re: [PATCH v1 1/2] dt-bindings: timeriomem_rng: Add entropy quality property

On Wed, May 17, 2017 at 03:29:10PM -0700, Rick Altherr wrote:
> Signed-off-by: Rick Altherr <[email protected]>
> ---
>
> Documentation/devicetree/bindings/rng/timeriomem_rng.txt | 7 +++++++
> 1 file changed, 7 insertions(+)

Acked-by: Rob Herring <[email protected]>