[PATCH v2 0/2] hwrng: bcm74110 - Add Broadcom BCM74110 RNG driver

[PATCH v2 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.

Binding changes from v1:
  - renamed binding file to brcm,bcm74110-rng.yaml
  - ensure "brcm,bcm74110-rng" is being used instead of "...-trng"
  - removed "|" after "description:"
  - removed label "rng:"

Code-related changes from v1:
  - only enable the driver for ARCH_BRCMSTB || COMPILE_TEST

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

 .../bindings/rng/brcm,bcm74110-rng.yaml       |  35 +++++
 drivers/char/hw_random/Kconfig                |  13 ++
 drivers/char/hw_random/Makefile               |   1 +
 drivers/char/hw_random/bcm74110-rng.c         | 125 ++++++++++++++++++
 4 files changed, 174 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110-rng.yaml
 create mode 100644 drivers/char/hw_random/bcm74110-rng.c

-- 
2.47.0

[PATCH v2 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-rng.yaml       | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110-rng.yaml

diff --git a/Documentation/devicetree/bindings/rng/brcm,bcm74110-rng.yaml b/Documentation/devicetree/bindings/rng/brcm,bcm74110-rng.yaml
new file mode 100644
index 000000000000..8e89d4a70b53
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/brcm,bcm74110-rng.yaml
@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rng/brcm,bcm74110-rng.yaml#
+$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@83ba000 {
+        compatible = "brcm,bcm74110-rng";
+        reg = <0x83ba000 0x14>;
+    };
-- 
2.47.0

Re: [PATCH v2 1/2] dt-bindings: rng: add binding for BCM74110 RNG

[Krzysztof Kozlowski]

On Fri, Nov 01, 2024 at 02:13:14PM -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-rng.yaml       | 35 +++++++++++++++++++
>  1 file changed, 35 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110-rng.yaml

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

[PATCH v2 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        |  13 +++
 drivers/char/hw_random/Makefile       |   1 +
 drivers/char/hw_random/bcm74110-rng.c | 125 ++++++++++++++++++++++++++
 3 files changed, 139 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..e665581e2324 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -99,6 +99,19 @@ config HW_RANDOM_BCM2835
 
 	  If unsure, say Y.
 
+config HW_RANDOM_BCM74110
+	tristate "Broadcom BCM74110 Random Number Generator support"
+	depends on 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");
-- 
2.47.0

Re: [PATCH v2 0/2] hwrng: bcm74110 - Add Broadcom BCM74110 RNG driver

[Herbert Xu]

On Fri, Nov 01, 2024 at 02:13:13PM -0700, Markus Mayer wrote:
> This series adds a driver for the random number generator found on the
> BCM74110 SoC.
> 
> Binding changes from v1:
>   - renamed binding file to brcm,bcm74110-rng.yaml
>   - ensure "brcm,bcm74110-rng" is being used instead of "...-trng"
>   - removed "|" after "description:"
>   - removed label "rng:"
> 
> Code-related changes from v1:
>   - only enable the driver for ARCH_BRCMSTB || COMPILE_TEST
> 
> Markus Mayer (2):
>   dt-bindings: rng: add binding for BCM74110 RNG
>   hwrng: bcm74110 - Add Broadcom BCM74110 RNG driver
> 
>  .../bindings/rng/brcm,bcm74110-rng.yaml       |  35 +++++
>  drivers/char/hw_random/Kconfig                |  13 ++
>  drivers/char/hw_random/Makefile               |   1 +
>  drivers/char/hw_random/bcm74110-rng.c         | 125 ++++++++++++++++++
>  4 files changed, 174 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rng/brcm,bcm74110-rng.yaml
>  create mode 100644 drivers/char/hw_random/bcm74110-rng.c
> 
> -- 
> 2.47.0

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