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

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

[Rick Altherr]

Signed-off-by: Rick Altherr <raltherr@google.com>
---

 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

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

[Rick Altherr]

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 <raltherr@google.com>
---

 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

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

[PrasannaKumar Muralidharan]

Hi Rick,

Minor comment below.

On 18 May 2017 at 03:59, Rick Altherr <raltherr@google.com> 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 <raltherr@google.com>
> ---
>
>  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

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

[Rob Herring]

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

Acked-by: Rob Herring <robh@kernel.org>