[PATCH 0/3] add entropy delay device tree property

[PATCH 0/3] add entropy delay device tree property

[Vabhav Sharma]

Add entropy delay device tree property,TRNG self test are run to determine         
the correct entropy delay.                                                         
Firmware test is executed with different voltage and temperature to                
identify the worst case value for entropy delay on imx6sx platform, after          
adding a margin value(1000),entropy delay should be at least 12000.                
- Add dt-bindings                                                                  
- updated imx6sx device tree                                                       
- modify caam driver to read the property

Vabhav Sharma (3):
  dt-bindings: crypto: fsl: add entropy delay property
  arm: dts: imx6sx: Add entropy delay property
  crypto: caam: read entropy delay from device tree

 .../devicetree/bindings/crypto/fsl-sec4.txt      |  6 ++++++
 arch/arm/boot/dts/imx6sx.dtsi                    |  1 +
 drivers/crypto/caam/ctrl.c                       | 16 ++++++++++++----
 3 files changed, 19 insertions(+), 4 deletions(-)

-- 
2.25.1

[PATCH 1/3] dt-bindings: crypto: fsl: add entropy delay property

[Vabhav Sharma]

Add entropy delay property which defines the length (in system clocks) of
each Entropy sample taken for TRNG configuration.

Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
Reviewed-by: Horia Geanta <horia.geanta@nxp.com>
Reviewed-by: Varun Sethi <v.sethi@nxp.com>
---
 Documentation/devicetree/bindings/crypto/fsl-sec4.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
index 8f359f473ada..1477294eda38 100644
--- a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
+++ b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
@@ -62,6 +62,12 @@ PROPERTIES
       Definition: A standard property. Define the 'ERA' of the SEC
           device.
 
+   - entropy-delay
+      Usage: optional
+      Value type: <u32>
+      Definition: A property which specifies the length (in system clocks)
+          of each Entropy sample taken.
+
    - #address-cells
        Usage: required
        Value type: <u32>
-- 
2.25.1

Re: [PATCH 1/3] dt-bindings: crypto: fsl: add entropy delay property

[Rob Herring]

On Mon, May 30, 2022 at 11:39:22PM +0530, Vabhav Sharma wrote:
> Add entropy delay property which defines the length (in system clocks) of
> each Entropy sample taken for TRNG configuration.
> 
> Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
> Reviewed-by: Horia Geanta <horia.geanta@nxp.com>
> Reviewed-by: Varun Sethi <v.sethi@nxp.com>
> ---
>  Documentation/devicetree/bindings/crypto/fsl-sec4.txt | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> index 8f359f473ada..1477294eda38 100644
> --- a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> +++ b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> @@ -62,6 +62,12 @@ PROPERTIES
>        Definition: A standard property. Define the 'ERA' of the SEC
>            device.
>  
> +   - entropy-delay
> +      Usage: optional
> +      Value type: <u32>
> +      Definition: A property which specifies the length (in system clocks)
> +          of each Entropy sample taken.
> +

Seems like this could be common, but should be a time value (with unit 
suffix) rather than clocks. If not common, then needs a vendor prefix. 
Is this time to read a value or time between values produced? Not really 
clear from the description.

Rob

RE: [EXT] Re: [PATCH 1/3] dt-bindings: crypto: fsl: add entropy delay property

[Vabhav Sharma]

Hello Rob,

> -----Original Message-----
> From: Rob Herring <robh@kernel.org>
> Sent: Monday, June 6, 2022 2:51 AM
> To: Vabhav Sharma <vabhav.sharma@nxp.com>
> Cc: Horia Geanta <horia.geanta@nxp.com>; Gaurav Jain
> <gaurav.jain@nxp.com>; Pankaj Gupta <pankaj.gupta@nxp.com>;
> herbert@gondor.apana.org.au; davem@davemloft.net;
> shawnguo@kernel.org; linux-crypto@vger.kernel.org; linux-
> kernel@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>;
> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; Silvano Di
> Ninno <silvano.dininno@nxp.com>; Varun Sethi <V.Sethi@nxp.com>
> Subject: [EXT] Re: [PATCH 1/3] dt-bindings: crypto: fsl: add entropy delay
> property
> 
> Caution: EXT Email
> 
> On Mon, May 30, 2022 at 11:39:22PM +0530, Vabhav Sharma wrote:
> > Add entropy delay property which defines the length (in system clocks)
> > of each Entropy sample taken for TRNG configuration.
> >
> > Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
> > Reviewed-by: Horia Geanta <horia.geanta@nxp.com>
> > Reviewed-by: Varun Sethi <v.sethi@nxp.com>
> > ---
> >  Documentation/devicetree/bindings/crypto/fsl-sec4.txt | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > index 8f359f473ada..1477294eda38 100644
> > --- a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > +++ b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > @@ -62,6 +62,12 @@ PROPERTIES
> >        Definition: A standard property. Define the 'ERA' of the SEC
> >            device.
> >
> > +   - entropy-delay
> > +      Usage: optional
> > +      Value type: <u32>
> > +      Definition: A property which specifies the length (in system clocks)
> > +          of each Entropy sample taken.
> > +
> 
> Seems like this could be common, but should be a time value (with unit
> suffix) rather than clocks. If not common, then needs a vendor prefix.
> Is this time to read a value or time between values produced? Not really clear
> from the description.
CAAM TRNG Configuration includes 16-bit field entropy-delay. This field specifies how long the oscillator is given to freely oscillate and generate a single bit of entropy.
It is specified as number of system clock cycles and this u32 type field already exist in the caam driver code with default value of 3200. However, on some platform this value can vary and support is added to read the value from device tree in order to override default value, Hope this helps to clarify.
> 
> Rob

Re: [EXT] Re: [PATCH 1/3] dt-bindings: crypto: fsl: add entropy delay property

[Rob Herring]

On Thu, Jun 16, 2022 at 05:49:30PM +0000, Vabhav Sharma wrote:
> Hello Rob,
> 
> > -----Original Message-----
> > From: Rob Herring <robh@kernel.org>
> > Sent: Monday, June 6, 2022 2:51 AM
> > To: Vabhav Sharma <vabhav.sharma@nxp.com>
> > Cc: Horia Geanta <horia.geanta@nxp.com>; Gaurav Jain
> > <gaurav.jain@nxp.com>; Pankaj Gupta <pankaj.gupta@nxp.com>;
> > herbert@gondor.apana.org.au; davem@davemloft.net;
> > shawnguo@kernel.org; linux-crypto@vger.kernel.org; linux-
> > kernel@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>;
> > devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; Silvano Di
> > Ninno <silvano.dininno@nxp.com>; Varun Sethi <V.Sethi@nxp.com>
> > Subject: [EXT] Re: [PATCH 1/3] dt-bindings: crypto: fsl: add entropy delay
> > property
> > 
> > Caution: EXT Email
> > 
> > On Mon, May 30, 2022 at 11:39:22PM +0530, Vabhav Sharma wrote:
> > > Add entropy delay property which defines the length (in system clocks)
> > > of each Entropy sample taken for TRNG configuration.
> > >
> > > Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
> > > Reviewed-by: Horia Geanta <horia.geanta@nxp.com>
> > > Reviewed-by: Varun Sethi <v.sethi@nxp.com>
> > > ---
> > >  Documentation/devicetree/bindings/crypto/fsl-sec4.txt | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > > b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > > index 8f359f473ada..1477294eda38 100644
> > > --- a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > > +++ b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > > @@ -62,6 +62,12 @@ PROPERTIES
> > >        Definition: A standard property. Define the 'ERA' of the SEC
> > >            device.
> > >
> > > +   - entropy-delay
> > > +      Usage: optional
> > > +      Value type: <u32>
> > > +      Definition: A property which specifies the length (in system clocks)
> > > +          of each Entropy sample taken.
> > > +
> > 
> > Seems like this could be common, but should be a time value (with unit
> > suffix) rather than clocks. If not common, then needs a vendor prefix.
> > Is this time to read a value or time between values produced? Not really clear
> > from the description.
> CAAM TRNG Configuration includes 16-bit field entropy-delay. This field specifies how long the oscillator is given to freely oscillate and generate a single bit of entropy.
> It is specified as number of system clock cycles and this u32 type field already exist in the caam driver code with default value of 3200. However, on some platform this value can vary and support is added to read the value from device tree in order to override default value, Hope this helps to clarify.

So that is how often a sample can be read? Or what happens if you read a 
sample too quick (in less than this delay time)?

Look at other h/w and drivers see if something common makes sense here.

Rob

RE: [EXT] Re: [PATCH 1/3] dt-bindings: crypto: fsl: add entropy delay property

[Vabhav Sharma]

Hello Rob,

> -----Original Message-----
> From: Rob Herring <robh@kernel.org>
> Sent: Thursday, June 30, 2022 2:56 AM
> To: Vabhav Sharma <vabhav.sharma@nxp.com>
> Cc: Horia Geanta <horia.geanta@nxp.com>; Gaurav Jain
> <gaurav.jain@nxp.com>; Pankaj Gupta <pankaj.gupta@nxp.com>;
> herbert@gondor.apana.org.au; davem@davemloft.net;
> shawnguo@kernel.org; linux-crypto@vger.kernel.org; linux-
> kernel@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>;
> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; Silvano Di
> Ninno <silvano.dininno@nxp.com>; Varun Sethi <V.Sethi@nxp.com>
> Subject: Re: [EXT] Re: [PATCH 1/3] dt-bindings: crypto: fsl: add entropy delay
> property
> 
> Caution: EXT Email
> 
> On Thu, Jun 16, 2022 at 05:49:30PM +0000, Vabhav Sharma wrote:
> > Hello Rob,
> >
> > > -----Original Message-----
> > > From: Rob Herring <robh@kernel.org>
> > > Sent: Monday, June 6, 2022 2:51 AM
> > > To: Vabhav Sharma <vabhav.sharma@nxp.com>
> > > Cc: Horia Geanta <horia.geanta@nxp.com>; Gaurav Jain
> > > <gaurav.jain@nxp.com>; Pankaj Gupta <pankaj.gupta@nxp.com>;
> > > herbert@gondor.apana.org.au; davem@davemloft.net;
> > > shawnguo@kernel.org; linux-crypto@vger.kernel.org; linux-
> > > kernel@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>;
> > > devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> > > Silvano Di Ninno <silvano.dininno@nxp.com>; Varun Sethi
> > > <V.Sethi@nxp.com>
> > > Subject: [EXT] Re: [PATCH 1/3] dt-bindings: crypto: fsl: add entropy
> > > delay property
> > >
> > > Caution: EXT Email
> > >
> > > On Mon, May 30, 2022 at 11:39:22PM +0530, Vabhav Sharma wrote:
> > > > Add entropy delay property which defines the length (in system
> > > > clocks) of each Entropy sample taken for TRNG configuration.
> > > >
> > > > Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
> > > > Reviewed-by: Horia Geanta <horia.geanta@nxp.com>
> > > > Reviewed-by: Varun Sethi <v.sethi@nxp.com>
> > > > ---
> > > >  Documentation/devicetree/bindings/crypto/fsl-sec4.txt | 6 ++++++
> > > >  1 file changed, 6 insertions(+)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > > > b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > > > index 8f359f473ada..1477294eda38 100644
> > > > --- a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > > > +++ b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
> > > > @@ -62,6 +62,12 @@ PROPERTIES
> > > >        Definition: A standard property. Define the 'ERA' of the SEC
> > > >            device.
> > > >
> > > > +   - entropy-delay
> > > > +      Usage: optional
> > > > +      Value type: <u32>
> > > > +      Definition: A property which specifies the length (in system clocks)
> > > > +          of each Entropy sample taken.
> > > > +
> > >
> > > Seems like this could be common, but should be a time value (with
> > > unit
> > > suffix) rather than clocks. If not common, then needs a vendor prefix.
> > > Is this time to read a value or time between values produced? Not
> > > really clear from the description.
> > CAAM TRNG Configuration includes 16-bit field entropy-delay. This field
> specifies how long the oscillator is given to freely oscillate and generate a
> single bit of entropy.
> > It is specified as number of system clock cycles and this u32 type field
> already exist in the caam driver code with default value of 3200. However, on
> some platform this value can vary and support is added to read the value
> from device tree in order to override default value, Hope this helps to clarify.
> 	
> So that is how often a sample can be read? Or what happens if you read a
> sample too quick (in less than this delay time)?
This is the fixed value that will work always profiled while offline per SoC or SoC family.
Value will work during initialization and run time.

Apologize to miss the email and delayed reply.
> 
> Look at other h/w and drivers see if something common makes sense here.
> 
> Rob

[PATCH 2/3] arm: dts: imx6sx: Add entropy delay property

[Vabhav Sharma]

Add imx6sx entropy-delay property.

TRNG self test are run to determine the correct entropy delay.
firmware test is executed with different voltage and temperature to
identify the worst case value for entropy delay. after adding a margin
value(1000),entropy delay should be at least 12000.

Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
Reviewed-by: Horia Geanta <horia.geanta@nxp.com>
Reviewed-by: Gaurav Jain <gaurav.jain@nxp.com>
---
 arch/arm/boot/dts/imx6sx.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/boot/dts/imx6sx.dtsi b/arch/arm/boot/dts/imx6sx.dtsi
index fc6334336b3d..305fad35f5c4 100644
--- a/arch/arm/boot/dts/imx6sx.dtsi
+++ b/arch/arm/boot/dts/imx6sx.dtsi
@@ -864,6 +864,7 @@ aips2: bus@2100000 {
 
 			crypto: crypto@2100000 {
 				compatible = "fsl,sec-v4.0";
+				entropy-delay = <12000>;
 				#address-cells = <1>;
 				#size-cells = <1>;
 				reg = <0x2100000 0x10000>;
-- 
2.25.1

[PATCH 3/3] crypto: caam: read entropy delay from device tree

[Vabhav Sharma]

Read entropy-delay property from device tree for
TRNG configuration.

update the value if entry is missing in DT.

Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
Reviewed-by: Gaurav Jain <gaurav.jain@nxp.com>
Reviewed-by: Horia Geanta <horia.geanta@nxp.com>
---
 drivers/crypto/caam/ctrl.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
index 32253a064d0f..5ffab99d831c 100644
--- a/drivers/crypto/caam/ctrl.c
+++ b/drivers/crypto/caam/ctrl.c
@@ -619,7 +619,7 @@ static bool needs_entropy_delay_adjustment(void)
 /* Probe routine for CAAM top (controller) level */
 static int caam_probe(struct platform_device *pdev)
 {
-	int ret, ring, gen_sk, ent_delay = RTSDCTL_ENT_DLY_MIN;
+	int ret, ring, gen_sk;
 	u64 caam_id;
 	const struct soc_device_attribute *imx_soc_match;
 	struct device *dev;
@@ -627,7 +627,7 @@ static int caam_probe(struct platform_device *pdev)
 	struct caam_ctrl __iomem *ctrl;
 	struct caam_drv_private *ctrlpriv;
 	struct dentry *dfs_root;
-	u32 scfgr, comp_params;
+	u32 scfgr, comp_params, ent_delay = RTSDCTL_ENT_DLY_MIN;
 	u8 rng_vid;
 	int pg_size;
 	int BLOCK_OFFSET = 0;
@@ -847,6 +847,16 @@ static int caam_probe(struct platform_device *pdev)
 			(rd_reg32(&ctrl->vreg.aesa) & CHA_VER_MISC_AES_NUM_MASK);
 	}
 
+	/*
+	 * Read entropy-delay property from device tree. If property is not
+	 * available or missing, update the entropy delay value only for imx6sx.
+	 */
+	if (device_property_read_u32(dev, "entropy-delay", &ent_delay)) {
+		dev_dbg(dev, "entropy-delay property missing in DT\n");
+		if (needs_entropy_delay_adjustment())
+			ent_delay = 12000;
+	}
+
 	/*
 	 * If SEC has RNG version >= 4 and RNG state handle has not been
 	 * already instantiated, do RNG instantiation
@@ -875,8 +885,6 @@ static int caam_probe(struct platform_device *pdev)
 			 * Also, if a handle was instantiated, do not change
 			 * the TRNG parameters.
 			 */
-			if (needs_entropy_delay_adjustment())
-				ent_delay = 12000;
 			if (!(ctrlpriv->rng4_sh_init || inst_handles)) {
 				dev_info(dev,
 					 "Entropy delay = %u\n",
-- 
2.25.1