Add support for Phytium SoC RNG

This patch adds the Phytium Random Number Generator (RNG) support.
Reviewed-by:maohongbo<maohongbo@phytium.com.cn>
Signed-off-by: Zhang Yiqun <zhangyiqun@phytium.com.cn>
Signed-off-by: Chen Baozi <chenbaozi@phytium.com.cn>

(cherry picked from commit 20b202182a)
Signed-off-by: Alex Shi <alexsshi@tencent.com>

drivers/char/hw_random/Kconfig

@@ -426,6 +426,18 @@ config HW_RANDOM_EXYNOS
 
 	  If unsure, say Y.
 
+config HW_RANDOM_PHYTIUM
+        tristate "Phytium Random Number Generator support"
+	depends on ARCH_PHYTIUM || COMPILE_TEST
+	help
+          This driver provides kernel-side support for the Random Number
+          Generator hardware found on Phytium SoCs.
+
+          To compile this driver as a module, choose M here: the
+          module will be called phytium-rng.
+
+          If unsure, say Y.
+
 config HW_RANDOM_OPTEE
 	tristate "OP-TEE based Random Number Generator support"
 	depends on OPTEE

drivers/char/hw_random/Makefile

@@ -38,4 +38,5 @@ obj-$(CONFIG_HW_RANDOM_CAVIUM) += cavium-rng.o cavium-rng-vf.o
 obj-$(CONFIG_HW_RANDOM_MTK)	+= mtk-rng.o
 obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o
 obj-$(CONFIG_HW_RANDOM_KEYSTONE) += ks-sa-rng.o
+obj-$(CONFIG_HW_RANDOM_PHYTIUM) += phytium-rng.o
 obj-$(CONFIG_HW_RANDOM_OPTEE) += optee-rng.o

drivers/char/hw_random/phytium-rng.c

@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Phytium SoC RNG Driver
+ *
+ * Copyright (C) 2021-2023, Phytium Technology Co., Ltd.
+ */
+
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/random.h>
+#include <linux/string.h>
+
+#define	TRNG_CR			0x00
+#define  TRNG_CR_RNGEN		BIT(0)
+#define  TRNG_CR_ROSEN_MASK	GENMASK(7, 4)
+#define  TRNG_CR_DIEN		BIT(16)
+#define  TRNG_CR_ERIEN		BIT(17)
+#define  TRNG_CR_IRQEN		BIT(24)
+#define TRNG_MSEL		0x04
+#define  TRNG_MSEL_MSEL		BIT(0)
+#define TRNG_SR			0x08
+#define  TRNG_SR_HTF		BIT(0)
+#define  TRNG_SR_DRDY		BIT(1)
+#define  TRNG_SR_ERERR		BIT(3)
+#define TRNG_DR			0x0C
+#define TRNG_RESEED		0x40
+#define  TRNG_RESEED_RSED	BIT(0)
+
+#define DELAY	10
+#define TIMEOUT	100
+
+static int msel;
+module_param(msel, int, 0444);
+MODULE_PARM_DESC(msel, "Phytium RNG mode selection: 0 - TRNG. 1 - PRNG.");
+
+struct phytium_rng {
+	struct hwrng rng;
+	void __iomem *base;
+};
+
+static int phytium_rng_init(struct hwrng *rng)
+{
+	struct phytium_rng *priv = container_of(rng, struct phytium_rng, rng);
+	u32 reg;
+
+	/* Mode Selection */
+	reg = msel ? TRNG_MSEL_MSEL : 0;
+	writel(reg, priv->base + TRNG_MSEL);
+
+	/* If PRGN mode is on, do reseed operations */
+	if (msel)
+		writel(TRNG_RESEED_RSED, priv->base + TRNG_RESEED);
+
+	/* Clear status */
+	writel(0x7, priv->base + TRNG_SR);
+
+	/* Enable TRNG */
+	reg = readl(priv->base + TRNG_CR) | TRNG_CR_ROSEN_MASK | TRNG_CR_RNGEN;
+	writel(reg, priv->base + TRNG_CR);
+
+	return 0;
+}
+
+static void phytium_rng_cleanup(struct hwrng *rng)
+{
+	struct phytium_rng *priv = container_of(rng, struct phytium_rng, rng);
+
+	writel(0x7, priv->base + TRNG_SR);
+}
+
+static int phytium_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	struct phytium_rng *priv = container_of(rng, struct phytium_rng, rng);
+	u32 reg;
+	int ret = 0;
+
+	/* TRNG can generate at most 8*32bit random number per time */
+	max = max > 8 ? 8 : max;
+
+	reg = readl(priv->base + TRNG_SR);
+	if (!(reg & TRNG_SR_DRDY) && wait) {
+		ret = readl_poll_timeout(priv->base + TRNG_SR, reg,
+					 reg & TRNG_SR_DRDY, DELAY, TIMEOUT);
+		if (ret) {
+			dev_err((struct device *)priv->rng.priv,
+				"%s: timeout %x!\n", __func__, reg);
+			return -EIO;
+		}
+	}
+
+	while (max > 4) {
+		*(u32 *)buf = readl(priv->base + TRNG_DR);
+
+		ret += sizeof(u32);
+		buf += sizeof(u32);
+		max -= sizeof(u32);
+	}
+
+	/* Clear DRDY by writing 1 */
+	writel(reg | TRNG_SR_DRDY, priv->base + TRNG_SR);
+
+	return ret;
+}
+
+static int scto_rng_probe(struct platform_device *pdev)
+{
+	struct phytium_rng *priv;
+	struct resource *mem;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	priv->rng.name = pdev->name;
+	priv->rng.init = phytium_rng_init;
+	priv->rng.cleanup = phytium_rng_cleanup;
+	priv->rng.read = phytium_rng_read;
+	priv->rng.priv = (unsigned long)&pdev->dev;
+
+	return devm_hwrng_register(&pdev->dev, &priv->rng);
+}
+
+static const struct of_device_id phytium_rng_dt_ids[] = {
+	{ .compatible = "phytium,rng" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, phytium_rng_dt_ids);
+
+static struct platform_driver phytium_rng_driver = {
+	.probe = scto_rng_probe,
+	.driver = {
+		.name = "phytium-rng",
+		.of_match_table = of_match_ptr(phytium_rng_dt_ids),
+	}
+};
+module_platform_driver(phytium_rng_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Phytium random number generator driver");
+MODULE_AUTHOR("Chen Baozi <chenbaozi@phytium.com.cn>");