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Signed-off-by: Markus Mayer --- 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 +#include +#include +#include +#include +#include +#include +#include + +#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 "); +MODULE_DESCRIPTION("BCM 74110 Random Number Generator (RNG) driver"); +MODULE_LICENSE("GPL v2");