[PATCH Resend 0/5] hwrng: stm32 - Improvement for stm32-rng

[PATCH Resend 0/5] hwrng: stm32 - Improvement for stm32-rng

[Lionel Debieve]

This set of patches add extended functionalities for stm32 rng
driver.
Patch #1 includes a reset during probe to avoid any error status
which can occur during bootup process and keep safe rng integrity.

Patch #3 adds a new property to manage the clock error detection
feature which can be disabled on specific target.

Patch #5 rework the timeout calculation for read value that was
previously defined based on loop operation and is now based on
timer.

Lionel Debieve (5):
  hwrng: stm32 - add reset during probe
  dt-bindings: rng: add reset node for stm32
  hwrng: stm32 - allow disable clock error detection
  dt-bindings: rng: add clock detection error for stm32
  hwrng: stm32 - rework read timeout calculation

 .../devicetree/bindings/rng/st,stm32-rng.txt       |  4 ++
 drivers/char/hw_random/stm32-rng.c                 | 44 ++++++++++++++--------
 2 files changed, 32 insertions(+), 16 deletions(-)

-- 
2.15.1

[PATCH Resend 1/5] hwrng: stm32 - add reset during probe

[Lionel Debieve]

Avoid issue when probing the RNG without
reset if bad status has been detected previously

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
---
 drivers/char/hw_random/stm32-rng.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c
index 63d84e6f1891..83c695938a2d 100644
--- a/drivers/char/hw_random/stm32-rng.c
+++ b/drivers/char/hw_random/stm32-rng.c
@@ -21,6 +21,7 @@
 #include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 
 #define RNG_CR 0x00
@@ -46,6 +47,7 @@ struct stm32_rng_private {
 	struct hwrng rng;
 	void __iomem *base;
 	struct clk *clk;
+	struct reset_control *rst;
 };
 
 static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
@@ -140,6 +142,13 @@ static int stm32_rng_probe(struct platform_device *ofdev)
 	if (IS_ERR(priv->clk))
 		return PTR_ERR(priv->clk);
 
+	priv->rst = devm_reset_control_get(&ofdev->dev, NULL);
+	if (!IS_ERR(priv->rst)) {
+		reset_control_assert(priv->rst);
+		udelay(2);
+		reset_control_deassert(priv->rst);
+	}
+
 	dev_set_drvdata(dev, priv);
 
 	priv->rng.name = dev_driver_string(dev),
-- 
2.15.1

[PATCH Resend 2/5] dt-bindings: rng: add reset node for stm32

[Lionel Debieve]

Adding optional resets property for rng.

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
---
 Documentation/devicetree/bindings/rng/st,stm32-rng.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/rng/st,stm32-rng.txt b/Documentation/devicetree/bindings/rng/st,stm32-rng.txt
index 47f04176f93b..cb7ca78135ff 100644
--- a/Documentation/devicetree/bindings/rng/st,stm32-rng.txt
+++ b/Documentation/devicetree/bindings/rng/st,stm32-rng.txt
@@ -11,6 +11,9 @@ Required properties:
 - interrupts : The designated IRQ line for the RNG
 - clocks : The clock needed to enable the RNG
 
+Optional properties:
+- resets : The reset to properly start RNG
+
 Example:
 
 	rng: rng@50060800 {
-- 
2.15.1

[PATCH Resend 3/5] hwrng: stm32 - allow disable clock error detection

[Lionel Debieve]

Add a new property that allow to disable the clock error
detection which is required when the clock source selected
is out of specification (which is not mandatory).

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
---
 drivers/char/hw_random/stm32-rng.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c
index 83c695938a2d..709a8d061be3 100644
--- a/drivers/char/hw_random/stm32-rng.c
+++ b/drivers/char/hw_random/stm32-rng.c
@@ -26,6 +26,7 @@
 
 #define RNG_CR 0x00
 #define RNG_CR_RNGEN BIT(2)
+#define RNG_CR_CED BIT(5)
 
 #define RNG_SR 0x04
 #define RNG_SR_SEIS BIT(6)
@@ -48,6 +49,7 @@ struct stm32_rng_private {
 	void __iomem *base;
 	struct clk *clk;
 	struct reset_control *rst;
+	bool ced;
 };
 
 static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
@@ -101,7 +103,11 @@ static int stm32_rng_init(struct hwrng *rng)
 	if (err)
 		return err;
 
-	writel_relaxed(RNG_CR_RNGEN, priv->base + RNG_CR);
+	if (priv->ced)
+		writel_relaxed(RNG_CR_RNGEN, priv->base + RNG_CR);
+	else
+		writel_relaxed(RNG_CR_RNGEN | RNG_CR_CED,
+			       priv->base + RNG_CR);
 
 	/* clear error indicators */
 	writel_relaxed(0, priv->base + RNG_SR);
@@ -149,6 +155,8 @@ static int stm32_rng_probe(struct platform_device *ofdev)
 		reset_control_deassert(priv->rst);
 	}
 
+	priv->ced = of_property_read_bool(np, "clock-error-detect");
+
 	dev_set_drvdata(dev, priv);
 
 	priv->rng.name = dev_driver_string(dev),
-- 
2.15.1

[PATCH Resend 4/5] dt-bindings: rng: add clock detection error for stm32

[Lionel Debieve]

Add optional property to enable the clock detection error
on rng block. It is used to allow slow clock source which
give correct entropy for rng.

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
---
 Documentation/devicetree/bindings/rng/st,stm32-rng.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/rng/st,stm32-rng.txt b/Documentation/devicetree/bindings/rng/st,stm32-rng.txt
index cb7ca78135ff..1dfa7d51e006 100644
--- a/Documentation/devicetree/bindings/rng/st,stm32-rng.txt
+++ b/Documentation/devicetree/bindings/rng/st,stm32-rng.txt
@@ -13,6 +13,7 @@ Required properties:
 
 Optional properties:
 - resets : The reset to properly start RNG
+- clock-error-detect : Enable the clock detection management
 
 Example:
 
-- 
2.15.1

[PATCH Resend 5/5] hwrng: stm32 - rework read timeout calculation

[Lionel Debieve]

Increase timeout delay to support longer timing linked
to rng initialization. Measurement is based on timer instead
of instructions per iteration which is not powerful on all
targets.

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
---
 drivers/char/hw_random/stm32-rng.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c
index 709a8d061be3..0d2328da3b76 100644
--- a/drivers/char/hw_random/stm32-rng.c
+++ b/drivers/char/hw_random/stm32-rng.c
@@ -16,6 +16,7 @@
 #include <linux/delay.h>
 #include <linux/hw_random.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
@@ -35,15 +36,6 @@
 
 #define RNG_DR 0x08
 
-/*
- * It takes 40 cycles @ 48MHz to generate each random number (e.g. <1us).
- * At the time of writing STM32 parts max out at ~200MHz meaning a timeout
- * of 500 leaves us a very comfortable margin for error. The loop to which
- * the timeout applies takes at least 4 instructions per iteration so the
- * timeout is enough to take us up to multi-GHz parts!
- */
-#define RNG_TIMEOUT 500
-
 struct stm32_rng_private {
 	struct hwrng rng;
 	void __iomem *base;
@@ -63,13 +55,16 @@ static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
 
 	while (max > sizeof(u32)) {
 		sr = readl_relaxed(priv->base + RNG_SR);
+		/* Manage timeout which is based on timer and take */
+		/* care of initial delay time when enabling rng	*/
 		if (!sr && wait) {
-			unsigned int timeout = RNG_TIMEOUT;
-
-			do {
-				cpu_relax();
-				sr = readl_relaxed(priv->base + RNG_SR);
-			} while (!sr && --timeout);
+			retval = readl_relaxed_poll_timeout_atomic(priv->base
+								   + RNG_SR,
+								   sr, sr,
+								   10, 50000);
+			if (retval)
+				dev_err((struct device *)priv->rng.priv,
+					"%s: timeout %x!\n", __func__, sr);
 		}
 
 		/* If error detected or data not ready... */
-- 
2.15.1

Re: [PATCH Resend 0/5] hwrng: stm32 - Improvement for stm32-rng

[Herbert Xu]

On Thu, Feb 15, 2018 at 02:03:07PM +0100, Lionel Debieve wrote:
> This set of patches add extended functionalities for stm32 rng
> driver.
> Patch #1 includes a reset during probe to avoid any error status
> which can occur during bootup process and keep safe rng integrity.
> 
> Patch #3 adds a new property to manage the clock error detection
> feature which can be disabled on specific target.
> 
> Patch #5 rework the timeout calculation for read value that was
> previously defined based on loop operation and is now based on
> timer.

I should take only patches 1/3/5, right?

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH Resend 0/5] hwrng: stm32 - Improvement for stm32-rng

[Alexandre Torgue]

Hi

On 02/22/2018 03:03 PM, Herbert Xu wrote:
> On Thu, Feb 15, 2018 at 02:03:07PM +0100, Lionel Debieve wrote:
>> This set of patches add extended functionalities for stm32 rng
>> driver.
>> Patch #1 includes a reset during probe to avoid any error status
>> which can occur during bootup process and keep safe rng integrity.
>>
>> Patch #3 adds a new property to manage the clock error detection
>> feature which can be disabled on specific target.
>>
>> Patch #5 rework the timeout calculation for read value that was
>> previously defined based on loop operation and is now based on
>> timer.
> 
> I should take only patches 1/3/5, right?

You could take all (dt-bindings + drivers part).

regards
alex

> 
> Cheers,
> 

Re: [PATCH Resend 0/5] hwrng: stm32 - Improvement for stm32-rng

[Herbert Xu]

On Thu, Feb 22, 2018 at 04:25:46PM +0100, Alexandre Torgue wrote:
> Hi
> 
> On 02/22/2018 03:03 PM, Herbert Xu wrote:
> >On Thu, Feb 15, 2018 at 02:03:07PM +0100, Lionel Debieve wrote:
> >>This set of patches add extended functionalities for stm32 rng
> >>driver.
> >>Patch #1 includes a reset during probe to avoid any error status
> >>which can occur during bootup process and keep safe rng integrity.
> >>
> >>Patch #3 adds a new property to manage the clock error detection
> >>feature which can be disabled on specific target.
> >>
> >>Patch #5 rework the timeout calculation for read value that was
> >>previously defined based on loop operation and is now based on
> >>timer.
> >
> >I should take only patches 1/3/5, right?
> 
> You could take all (dt-bindings + drivers part).

Thanks!
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH Resend 0/5] hwrng: stm32 - Improvement for stm32-rng

[Herbert Xu]

On Thu, Feb 15, 2018 at 02:03:07PM +0100, Lionel Debieve wrote:
> This set of patches add extended functionalities for stm32 rng
> driver.
> Patch #1 includes a reset during probe to avoid any error status
> which can occur during bootup process and keep safe rng integrity.
> 
> Patch #3 adds a new property to manage the clock error detection
> feature which can be disabled on specific target.
> 
> Patch #5 rework the timeout calculation for read value that was
> previously defined based on loop operation and is now based on
> timer.
> 
> Lionel Debieve (5):
>   hwrng: stm32 - add reset during probe
>   dt-bindings: rng: add reset node for stm32
>   hwrng: stm32 - allow disable clock error detection
>   dt-bindings: rng: add clock detection error for stm32
>   hwrng: stm32 - rework read timeout calculation
> 
>  .../devicetree/bindings/rng/st,stm32-rng.txt       |  4 ++
>  drivers/char/hw_random/stm32-rng.c                 | 44 ++++++++++++++--------
>  2 files changed, 32 insertions(+), 16 deletions(-)

All applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt