[PATCH 0/2] hwrng: bcm74110 - Add Broadcom BCM74110 RNG driver

[PATCH 0/2] hwrng: bcm74110 - Add Broadcom BCM74110 RNG driver

[Markus Mayer]

This series adds a driver for the random number generator found on the
BCM74110 SoC.

Markus Mayer (2):
  dt-bindings: rng: add binding for BCM74110 RNG
  hwrng: bcm74110 - Add Broadcom BCM74110 RNG driver

 .../bindings/rng/brcm,bcm74110.yaml           |  35 +++++
 drivers/char/hw_random/Kconfig                |  14 ++
 drivers/char/hw_random/Makefile               |   1 +
 drivers/char/hw_random/bcm74110-rng.c         | 125 ++++++++++++++++++
 4 files changed, 175 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
 create mode 100644 drivers/char/hw_random/bcm74110-rng.c

-- 
2.46.0

[PATCH 1/2] dt-bindings: rng: add binding for BCM74110 RNG

[Markus Mayer]

Add a binding for the random number generator used on the BCM74110.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
---
 .../bindings/rng/brcm,bcm74110.yaml           | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml

diff --git a/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml b/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
new file mode 100644
index 000000000000..acd0856cee72
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rng/brcm,bcm74110.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: BCM74110 Random number generator
+
+description: |
+  Random number generator used on the BCM74110.
+
+maintainers:
+  - Markus Mayer <mmayer@broadcom.com>
+  - Florian Fainelli <florian.fainelli@broadcom.com>
+
+properties:
+  compatible:
+    enum:
+      - brcm,bcm74110-rng
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    rng: rng@83ba000 {
+        compatible = "brcm,bcm74110-trng";
+        reg = <0x83ba000 0x14>;
+    };
-- 
2.46.0

Re: [PATCH 1/2] dt-bindings: rng: add binding for BCM74110 RNG

[Florian Fainelli]

On 10/30/24 14:33, Markus Mayer wrote:
> Add a binding for the random number generator used on the BCM74110.
> 
> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> ---
>   .../bindings/rng/brcm,bcm74110.yaml           | 35 +++++++++++++++++++
>   1 file changed, 35 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml

This file should be named, brcm,bcm74110-rng.yaml, I believe.
--
Florian

Re: [PATCH 1/2] dt-bindings: rng: add binding for BCM74110 RNG

[Rob Herring (Arm)]

On Wed, 30 Oct 2024 14:33:54 -0700, Markus Mayer wrote:
> Add a binding for the random number generator used on the BCM74110.
> 
> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> ---
>  .../bindings/rng/brcm,bcm74110.yaml           | 35 +++++++++++++++++++
>  1 file changed, 35 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
Documentation/devicetree/bindings/rng/brcm,bcm74110.example.dtb: /example-0/rng@83ba000: failed to match any schema with compatible: ['brcm,bcm74110-trng']

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20241030213400.802264-2-mmayer@broadcom.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

Re: [PATCH 1/2] dt-bindings: rng: add binding for BCM74110 RNG

[Krzysztof Kozlowski]

On 30/10/2024 22:33, Markus Mayer wrote:
> Add a binding for the random number generator used on the BCM74110.
> 
> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> ---
>  .../bindings/rng/brcm,bcm74110.yaml           | 35 +++++++++++++++++++
>  1 file changed, 35 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
> 
> diff --git a/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml b/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
> new file mode 100644
> index 000000000000..acd0856cee72
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml

Filename as compatible.

> @@ -0,0 +1,35 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/rng/brcm,bcm74110.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: BCM74110 Random number generator
> +
> +description: |

Do not need '|' unless you need to preserve formatting.

> +  Random number generator used on the BCM74110.
> +
> +maintainers:
> +  - Markus Mayer <mmayer@broadcom.com>
> +  - Florian Fainelli <florian.fainelli@broadcom.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - brcm,bcm74110-rng

That's not what you have in DTS.

> +
> +  reg:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    rng: rng@83ba000 {

Drop unused label.



Best regards,
Krzysztof

Re: [PATCH 1/2] dt-bindings: rng: add binding for BCM74110 RNG

[Markus Mayer]

On Thu, 31 Oct 2024 at 00:29, Krzysztof Kozlowski
<krzysztof.kozlowski@linaro.org> wrote:
>
> On 30/10/2024 22:33, Markus Mayer wrote:
> > Add a binding for the random number generator used on the BCM74110.
> >
> > Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> > ---
> >  .../bindings/rng/brcm,bcm74110.yaml           | 35 +++++++++++++++++++
> >  1 file changed, 35 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml b/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
> > new file mode 100644
> > index 000000000000..acd0856cee72
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
>
> Filename as compatible.

I am not sure what you mean by this. That the filename should match
the compatible string? I did change the filename to
brcm,bcm74110-rng.yaml the ID to
http://devicetree.org/schemas/rng/brcm,bcm74110-rng.yaml# in response
to Florian's comment from yesterday.

> > @@ -0,0 +1,35 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/rng/brcm,bcm74110.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: BCM74110 Random number generator
> > +
> > +description: |
>
> Do not need '|' unless you need to preserve formatting.

Removed.

> > +  Random number generator used on the BCM74110.
> > +
> > +maintainers:
> > +  - Markus Mayer <mmayer@broadcom.com>
> > +  - Florian Fainelli <florian.fainelli@broadcom.com>
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - brcm,bcm74110-rng
>
> That's not what you have in DTS.

Fixed in the DTS to be "brcm,bcm74110-rng" everywhere.

> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    rng: rng@83ba000 {
>
> Drop unused label.

Done.

I am giving it a bit more time for additional feedback (on the driver
and the binding) and will send v2 in a few days. Meanwhile, the
generated DTS (with the changes incorporated) is now looking like
this:

$ cat ./Documentation/devicetree/bindings/rng/brcm,bcm74110-rng.example.dts
/dts-v1/;
/plugin/; // silence any missing phandle references

/{
    compatible = "foo";
    model = "foo";
    #address-cells = <1>;
    #size-cells = <1>;

    example-0 {
        #address-cells = <1>;
        #size-cells = <1>;

        rng@83ba000 {
            compatible = "brcm,bcm74110-rng";
            reg = <0x83ba000 0x14>;
        };
    };
};

Thanks,
-Markus

Re: [PATCH 1/2] dt-bindings: rng: add binding for BCM74110 RNG

[Krzysztof Kozlowski]

On 31/10/2024 19:55, Markus Mayer wrote:
> On Thu, 31 Oct 2024 at 00:29, Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org> wrote:
>>
>> On 30/10/2024 22:33, Markus Mayer wrote:
>>> Add a binding for the random number generator used on the BCM74110.
>>>
>>> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
>>> ---
>>>  .../bindings/rng/brcm,bcm74110.yaml           | 35 +++++++++++++++++++
>>>  1 file changed, 35 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml b/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
>>> new file mode 100644
>>> index 000000000000..acd0856cee72
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/rng/brcm,bcm74110.yaml
>>
>> Filename as compatible.
> 
> I am not sure what you mean by this. That the filename should match
> the compatible string? I did change the filename to

Yes.

Best regards,
Krzysztof

[PATCH 2/2] hwrng: bcm74110 - Add Broadcom BCM74110 RNG driver

[Markus Mayer]

Add a driver for the random number generator present on the Broadcom
BCM74110 SoC.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
---
 drivers/char/hw_random/Kconfig        |  14 +++
 drivers/char/hw_random/Makefile       |   1 +
 drivers/char/hw_random/bcm74110-rng.c | 125 ++++++++++++++++++++++++++
 3 files changed, 140 insertions(+)
 create mode 100644 drivers/char/hw_random/bcm74110-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index b51d9e243f35..90ae35aeb23a 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -99,6 +99,20 @@ config HW_RANDOM_BCM2835
 
 	  If unsure, say Y.
 
+config HW_RANDOM_BCM74110
+	tristate "Broadcom BCM74110 Random Number Generator support"
+	depends on ARCH_BCM2835 || ARCH_BCM_NSP || ARCH_BCM_5301X || \
+		   ARCH_BCMBCA || BCM63XX || ARCH_BRCMSTB || COMPILE_TEST
+	default HW_RANDOM
+	help
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on the Broadcom BCM74110 SoCs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called bcm74110-rng
+
+	  If unsure, say Y.
+
 config HW_RANDOM_IPROC_RNG200
 	tristate "Broadcom iProc/STB RNG200 support"
 	depends on ARCH_BCM_IPROC || ARCH_BCM2835 || ARCH_BRCMSTB || COMPILE_TEST
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 01f012eab440..283791f5462d 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -31,6 +31,7 @@ obj-$(CONFIG_HW_RANDOM_POWERNV) += powernv-rng.o
 obj-$(CONFIG_HW_RANDOM_HISI)	+= hisi-rng.o
 obj-$(CONFIG_HW_RANDOM_HISTB) += histb-rng.o
 obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
+obj-$(CONFIG_HW_RANDOM_BCM74110) += bcm74110-rng.o
 obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
 obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
 obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
diff --git a/drivers/char/hw_random/bcm74110-rng.c b/drivers/char/hw_random/bcm74110-rng.c
new file mode 100644
index 000000000000..5c64148e91f1
--- /dev/null
+++ b/drivers/char/hw_random/bcm74110-rng.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2024 Broadcom
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/random.h>
+#include <linux/hw_random.h>
+
+#define HOST_REV_ID		0x00
+#define HOST_FIFO_DEPTH		0x04
+#define HOST_FIFO_COUNT		0x08
+#define HOST_FIFO_THRESHOLD	0x0c
+#define HOST_FIFO_DATA		0x10
+
+#define HOST_FIFO_COUNT_MASK		0xffff
+
+/* Delay range in microseconds */
+#define FIFO_DELAY_MIN_US		3
+#define FIFO_DELAY_MAX_US		7
+#define FIFO_DELAY_MAX_COUNT		10
+
+struct bcm74110_priv {
+	void __iomem *base;
+};
+
+static inline int bcm74110_rng_fifo_count(void __iomem *mem)
+{
+	return readl_relaxed(mem) & HOST_FIFO_COUNT_MASK;
+}
+
+static int bcm74110_rng_read(struct hwrng *rng, void *buf, size_t max,
+			bool wait)
+{
+	struct bcm74110_priv *priv = (struct bcm74110_priv *)rng->priv;
+	void __iomem *fc_addr = priv->base + HOST_FIFO_COUNT;
+	void __iomem *fd_addr = priv->base + HOST_FIFO_DATA;
+	unsigned underrun_count = 0;
+	u32 max_words = max / sizeof(u32);
+	u32 num_words;
+	unsigned i;
+
+	/*
+	 * We need to check how many words are available in the RNG FIFO. If
+	 * there aren't any, we need to wait for some to become available.
+	 */
+	while ((num_words = bcm74110_rng_fifo_count(fc_addr)) == 0) {
+		if (!wait)
+			return 0;
+		/*
+		 * As a precaution, limit how long we wait. If the FIFO doesn't
+		 * refill within the allotted time, return 0 (=no data) to the
+		 * caller.
+		 */
+		if (likely(underrun_count < FIFO_DELAY_MAX_COUNT))
+			usleep_range(FIFO_DELAY_MIN_US, FIFO_DELAY_MAX_US);
+		else
+			return 0;
+		underrun_count++;
+	}
+	if (num_words > max_words)
+		num_words = max_words;
+
+	/* Bail early if we run out of random numbers unexpectedly */
+	for (i = 0; i < num_words && bcm74110_rng_fifo_count(fc_addr) > 0; i++)
+		((u32 *)buf)[i] = readl_relaxed(fd_addr);
+
+	return i * sizeof(u32);
+}
+
+static struct hwrng bcm74110_hwrng = {
+	.read = bcm74110_rng_read,
+};
+
+static int bcm74110_rng_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bcm74110_priv *priv;
+	int rc;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	bcm74110_hwrng.name = pdev->name;
+	bcm74110_hwrng.priv = (unsigned long)priv;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	rc = devm_hwrng_register(dev, &bcm74110_hwrng);
+	if (rc)
+		dev_err(dev, "hwrng registration failed (%d)\n", rc);
+	else
+		dev_info(dev, "hwrng registered\n");
+
+	return rc;
+}
+
+static const struct of_device_id bcm74110_rng_match[] = {
+	{ .compatible	= "brcm,bcm74110-rng", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bcm74110_rng_match);
+
+static struct platform_driver bcm74110_rng_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = bcm74110_rng_match,
+	},
+	.probe	= bcm74110_rng_probe,
+};
+module_platform_driver(bcm74110_rng_driver);
+
+MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
+MODULE_DESCRIPTION("BCM 74110 Random Number Generator (RNG) driver");
+MODULE_LICENSE("GPL v2");
-- 
2.46.0

Re: [PATCH 2/2] hwrng: bcm74110 - Add Broadcom BCM74110 RNG driver

[Florian Fainelli]

On 10/30/24 14:33, Markus Mayer wrote:
> Add a driver for the random number generator present on the Broadcom
> BCM74110 SoC.
> 
> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> ---
>   drivers/char/hw_random/Kconfig        |  14 +++
>   drivers/char/hw_random/Makefile       |   1 +
>   drivers/char/hw_random/bcm74110-rng.c | 125 ++++++++++++++++++++++++++
>   3 files changed, 140 insertions(+)
>   create mode 100644 drivers/char/hw_random/bcm74110-rng.c
> 
> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> index b51d9e243f35..90ae35aeb23a 100644
> --- a/drivers/char/hw_random/Kconfig
> +++ b/drivers/char/hw_random/Kconfig
> @@ -99,6 +99,20 @@ config HW_RANDOM_BCM2835
>   
>   	  If unsure, say Y.
>   
> +config HW_RANDOM_BCM74110
> +	tristate "Broadcom BCM74110 Random Number Generator support"
> +	depends on ARCH_BCM2835 || ARCH_BCM_NSP || ARCH_BCM_5301X || \
> +		   ARCH_BCMBCA || BCM63XX || ARCH_BRCMSTB || COMPILE_TEST

AFAICT this driver is only present on STB chips so limiting to 
ARCH_BRCMSTB || COMPILE_TEST should suffice for now.
-- 
Florian

Re: [PATCH 2/2] hwrng: bcm74110 - Add Broadcom BCM74110 RNG driver

[Markus Mayer]

On Wed, 30 Oct 2024 at 14:41, Florian Fainelli
<florian.fainelli@broadcom.com> wrote:
>
> On 10/30/24 14:33, Markus Mayer wrote:
> > Add a driver for the random number generator present on the Broadcom
> > BCM74110 SoC.
> >
> > Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> > ---
> >   drivers/char/hw_random/Kconfig        |  14 +++
> >   drivers/char/hw_random/Makefile       |   1 +
> >   drivers/char/hw_random/bcm74110-rng.c | 125 ++++++++++++++++++++++++++
> >   3 files changed, 140 insertions(+)
> >   create mode 100644 drivers/char/hw_random/bcm74110-rng.c
> >
> > diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> > index b51d9e243f35..90ae35aeb23a 100644
> > --- a/drivers/char/hw_random/Kconfig
> > +++ b/drivers/char/hw_random/Kconfig
> > @@ -99,6 +99,20 @@ config HW_RANDOM_BCM2835
> >
> >         If unsure, say Y.
> >
> > +config HW_RANDOM_BCM74110
> > +     tristate "Broadcom BCM74110 Random Number Generator support"
> > +     depends on ARCH_BCM2835 || ARCH_BCM_NSP || ARCH_BCM_5301X || \
> > +                ARCH_BCMBCA || BCM63XX || ARCH_BRCMSTB || COMPILE_TEST
>
> AFAICT this driver is only present on STB chips so limiting to
> ARCH_BRCMSTB || COMPILE_TEST should suffice for now.

This is now fixed in my tree. I will resend in a few days.

Regards,
-Markus