[PATCH 0/4] hw rng support for NSP SoC

[PATCH 0/4] hw rng support for NSP SoC

[Yendapally Reddy Dhananjaya Reddy]

This patchset contains the hw random number generator support for the
Broadcom's NSP SoC. The block is similar to the block available in
bcm2835 with different default interrupt mask value. Due to lack of
documentation, I cannot confirm the interrupt mask register details
in bcm2835. In an effort to not break the existing functionality of
bcm2835, I used a different compatible string to mask the interrupt
for NSP SoC. Please let me know. Also supported providing requested
number of random numbers instead of static size of four bytes.

The first patch contains the documentation changes and the second patch
contains the support for rng available in NSP SoC. The third patch
contains the device tree changes for NSP SoC. The fourth patch contains
the support for reading requested number of random numbers.

This patch set has been tested on NSP bcm958625HR board.
This patch set is based on v4.6.0-rc1 and is available from github
repo: https://github.com/Broadcom/cygnus-linux.git
branch: nsp-rng-v1

Yendapally Reddy Dhananjaya Reddy (4):
  dt-bindings: rng: Northstar Plus SoC rng bindings
  hwrng: bcm2835: Support Broadcom NSP SoC rng
  ARM: dts: nsp: Add rng device tree entry
  hwrng: bcm2835: Read as much data as available

 .../devicetree/bindings/rng/brcm,bcm2835.txt       |  7 +++-
 arch/arm/boot/dts/bcm-nsp.dtsi                     |  5 +++
 drivers/char/hw_random/Kconfig                     |  2 +-
 drivers/char/hw_random/bcm2835-rng.c               | 46 +++++++++++++++++++---
 4 files changed, 52 insertions(+), 8 deletions(-)

-- 
2.1.0

[PATCH 1/4] dt-bindings: rng: Northstar Plus SoC rng bindings

[Yendapally Reddy Dhananjaya Reddy]

Document the bindings used by Northstar Plus(NSP) SoC random number
generator.

Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
---
 Documentation/devicetree/bindings/rng/brcm,bcm2835.txt | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/rng/brcm,bcm2835.txt b/Documentation/devicetree/bindings/rng/brcm,bcm2835.txt
index 07ccdaa..aa304d4 100644
--- a/Documentation/devicetree/bindings/rng/brcm,bcm2835.txt
+++ b/Documentation/devicetree/bindings/rng/brcm,bcm2835.txt
@@ -2,7 +2,7 @@ BCM2835 Random number generator
 
 Required properties:
 
-- compatible : should be "brcm,bcm2835-rng"
+- compatible : should be "brcm,bcm2835-rng"  or "brcm,bcm-nsp-rng"
 - reg : Specifies base physical address and size of the registers.
 
 Example:
@@ -11,3 +11,8 @@ rng {
         compatible = "brcm,bcm2835-rng";
         reg = <0x7e104000 0x10>;
 };
+
+rng@18033000 {
+	compatible = "brcm,bcm-nsp-rng";
+	reg = <0x18033000 0x14>;
+};
-- 
2.1.0

Re: [PATCH 1/4] dt-bindings: rng: Northstar Plus SoC rng bindings

[Rob Herring]

On Mon, May 23, 2016 at 12:20:48PM -0400, Yendapally Reddy Dhananjaya Reddy wrote:
> Document the bindings used by Northstar Plus(NSP) SoC random number
> generator.
> 
> Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
> ---
>  Documentation/devicetree/bindings/rng/brcm,bcm2835.txt | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

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

Re: [PATCH 1/4] dt-bindings: rng: Northstar Plus SoC rng bindings

[Eric Anholt]

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Yendapally Reddy Dhananjaya Reddy <yendapally.reddy-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
writes:

> Document the bindings used by Northstar Plus(NSP) SoC random number
> generator.
>
> Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>

Acked-by: Eric Anholt <eric-WhKQ6XTQaPysTnJN9+BGXg@public.gmane.org>

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[PATCH 2/4] hwrng: bcm2835: Support Broadcom NSP SoC rng

[Yendapally Reddy Dhananjaya Reddy]

This supports the random number generator available in NSP SoC.
Masks the rng interrupt for NSP.

Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
---
 drivers/char/hw_random/Kconfig       |  2 +-
 drivers/char/hw_random/bcm2835-rng.c | 34 ++++++++++++++++++++++++++++++----
 2 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 67ee8b0..f8d1a2b 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -90,7 +90,7 @@ config HW_RANDOM_BCM63XX
 
 config HW_RANDOM_BCM2835
 	tristate "Broadcom BCM2835 Random Number Generator support"
-	depends on ARCH_BCM2835
+	depends on ARCH_BCM2835 || ARCH_BCM_NSP
 	default HW_RANDOM
 	---help---
 	  This driver provides kernel-side support for the Random Number
diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c
index 7192ec2..b1e8b78 100644
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -19,6 +19,7 @@
 #define RNG_CTRL	0x0
 #define RNG_STATUS	0x4
 #define RNG_DATA	0x8
+#define RNG_INT_MASK	0x10
 
 /* enable rng */
 #define RNG_RBGEN	0x1
@@ -26,6 +27,18 @@
 /* the initial numbers generated are "less random" so will be discarded */
 #define RNG_WARMUP_COUNT 0x40000
 
+#define RNG_INT_OFF	0x1
+
+static void __init nsp_rng_init(void __iomem *base)
+{
+	u32 val;
+
+	/* mask the interrupt */
+	val = readl(base + RNG_INT_MASK);
+	val |= RNG_INT_OFF;
+	writel(val, base + RNG_INT_MASK);
+}
+
 static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
 			       bool wait)
 {
@@ -46,10 +59,18 @@ static struct hwrng bcm2835_rng_ops = {
 	.read	= bcm2835_rng_read,
 };
 
+static const struct of_device_id bcm2835_rng_of_match[] = {
+	{ .compatible = "brcm,bcm2835-rng"},
+	{ .compatible = "brcm,bcm-nsp-rng", .data = nsp_rng_init},
+	{},
+};
+
 static int bcm2835_rng_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
+	void (*rng_setup)(void __iomem *base);
+	const struct of_device_id *rng_id;
 	void __iomem *rng_base;
 	int err;
 
@@ -61,6 +82,15 @@ static int bcm2835_rng_probe(struct platform_device *pdev)
 	}
 	bcm2835_rng_ops.priv = (unsigned long)rng_base;
 
+	rng_id = of_match_node(bcm2835_rng_of_match, np);
+	if (!rng_id)
+		return -EINVAL;
+
+	/* Check for rng init function, execute it */
+	rng_setup = rng_id->data;
+	if (rng_setup)
+		rng_setup(rng_base);
+
 	/* set warm-up count & enable */
 	__raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS);
 	__raw_writel(RNG_RBGEN, rng_base + RNG_CTRL);
@@ -90,10 +120,6 @@ static int bcm2835_rng_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static const struct of_device_id bcm2835_rng_of_match[] = {
-	{ .compatible = "brcm,bcm2835-rng", },
-	{},
-};
 MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match);
 
 static struct platform_driver bcm2835_rng_driver = {
-- 
2.1.0

Re: [PATCH 2/4] hwrng: bcm2835: Support Broadcom NSP SoC rng

[Eric Anholt]

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Yendapally Reddy Dhananjaya Reddy <yendapally.reddy-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
writes:

> This supports the random number generator available in NSP SoC.
> Masks the rng interrupt for NSP.

The interrupt reg is also present on the 2835.  I would prefer for
simplicity if you also initialized the register to the same value on the
Pi, even though the firmware has presumably been setting it for us
already.

However, this patch is still correct and I'm fine with it, so it's:

Acked-by: Eric Anholt <eric-WhKQ6XTQaPysTnJN9+BGXg@public.gmane.org>

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[PATCH 3/4] ARM: dts: nsp: Add rng device tree entry

[Yendapally Reddy Dhananjaya Reddy]

Add support for the random number generator to the Northstar Plus
SoC device tree.

Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
---
 arch/arm/boot/dts/bcm-nsp.dtsi | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm/boot/dts/bcm-nsp.dtsi b/arch/arm/boot/dts/bcm-nsp.dtsi
index def9e78..1ed829e 100644
--- a/arch/arm/boot/dts/bcm-nsp.dtsi
+++ b/arch/arm/boot/dts/bcm-nsp.dtsi
@@ -206,6 +206,11 @@
 			brcm,nand-has-wp;
 		};
 
+		rng: rng@33000 {
+			compatible = "brcm,bcm-nsp-rng";
+			reg = <0x33000 0x14>;
+		};
+
 		ccbtimer0: timer@34000 {
 			compatible = "arm,sp804";
 			reg = <0x34000 0x1000>;
-- 
2.1.0

[PATCH 4/4] hwrng: bcm2835: Read as much data as available

[Yendapally Reddy Dhananjaya Reddy]

Read the requested number of data from the fifo

Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
---
 drivers/char/hw_random/bcm2835-rng.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c
index b1e8b78..9bbdc07 100644
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -43,6 +43,8 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
 			       bool wait)
 {
 	void __iomem *rng_base = (void __iomem *)rng->priv;
+	u32 max_words = max/sizeof(u32);
+	u32 num_words, count;
 
 	while ((__raw_readl(rng_base + RNG_STATUS) >> 24) == 0) {
 		if (!wait)
@@ -50,8 +52,14 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
 		cpu_relax();
 	}
 
-	*(u32 *)buf = __raw_readl(rng_base + RNG_DATA);
-	return sizeof(u32);
+	num_words = (readl(rng_base + RNG_STATUS) >> 24);
+	if (num_words > max_words)
+		num_words = max_words;
+
+	for (count = 0; count < num_words; count++)
+		((u32 *)buf)[count] = readl(rng_base + RNG_DATA);
+
+	return (num_words * sizeof(u32));
 }
 
 static struct hwrng bcm2835_rng_ops = {
-- 
2.1.0

Re: [PATCH 4/4] hwrng: bcm2835: Read as much data as available

[Eric Anholt]

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Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
writes:

> Read the requested number of data from the fifo
>
> Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
> ---
>  drivers/char/hw_random/bcm2835-rng.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c
> index b1e8b78..9bbdc07 100644
> --- a/drivers/char/hw_random/bcm2835-rng.c
> +++ b/drivers/char/hw_random/bcm2835-rng.c
> @@ -43,6 +43,8 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
>  			       bool wait)
>  {
>  	void __iomem *rng_base = (void __iomem *)rng->priv;
> +	u32 max_words = max/sizeof(u32);

Style fix: Binary operators get a space on each side, so
"max / sizeof(u32);"

> @@ -50,8 +52,14 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
>  		cpu_relax();
>  	}
>  
> -	*(u32 *)buf = __raw_readl(rng_base + RNG_DATA);
> -	return sizeof(u32);
> +	num_words = (readl(rng_base + RNG_STATUS) >> 24);

Optional cleanup: here and in the return statement, drop the extra
parenthesis.

Functionality-wise, this patch looks great to me, and should make the
driver more efficient.  With at least the binary operators change done,
it will be:

Reviewed-by: Eric Anholt <eric@anholt.net>

Thanks!

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