Add a driver for the random number generator present on the Broadcom
BCM74110 SoC.
Signed-off-by: Markus Mayer <mmayer@xxxxxxxxxxxx>
---
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@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("BCM 74110 Random Number Generator (RNG) driver");
+MODULE_LICENSE("GPL v2");
--
2.47.0
