crypto: hisilicon/trng - add support for HiSTB TRNG

HiSTB TRNG are found on some HiSilicon STB SoCs.

Signed-off-by: David Yang <mmyangfl@gmail.com>

drivers/crypto/hisilicon/Kconfig

@@ -82,3 +82,10 @@ config CRYPTO_DEV_HISI_TRNG
 	select CRYPTO_RNG
 	help
 	  Support for HiSilicon TRNG Driver.
+
+config CRYPTO_DEV_HISTB_TRNG
+	tristate "Support for HiSTB TRNG Driver"
+	depends on ARCH_HISI || COMPILE_TEST
+	select HW_RANDOM
+	help
+	  Support for HiSTB TRNG Driver.

drivers/crypto/hisilicon/Makefile

@@ -5,4 +5,4 @@ obj-$(CONFIG_CRYPTO_DEV_HISI_SEC2) += sec2/
 obj-$(CONFIG_CRYPTO_DEV_HISI_QM) += hisi_qm.o
 hisi_qm-objs = qm.o sgl.o debugfs.o
 obj-$(CONFIG_CRYPTO_DEV_HISI_ZIP) += zip/
-obj-$(CONFIG_CRYPTO_DEV_HISI_TRNG) += trng/
+obj-y += trng/

drivers/crypto/hisilicon/trng/Makefile

@@ -1,2 +1,5 @@
 obj-$(CONFIG_CRYPTO_DEV_HISI_TRNG) += hisi-trng-v2.o
 hisi-trng-v2-objs = trng.o
+
+obj-$(CONFIG_CRYPTO_DEV_HISTB_TRNG) += histb-trng.o
+histb-trng-objs += trng-stb.o

drivers/crypto/hisilicon/trng/trng-stb.c

@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+/*
+ * Device driver for True RNG in HiSTB SoCs
+ *
+ * Copyright (c) 2023 David Yang
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+
+#define HISTB_TRNG_CTRL		0x0
+#define HISTB_TRNG_NUMBER	0x4
+#define HISTB_TRNG_STAT		0x8
+
+#define SLEEP_US		10
+#define TIMEOUT_US		10000
+
+static int histb_trng_wait(struct hwrng *rng)
+{
+	void __iomem *base = (void __iomem *) rng->priv;
+	u32 val;
+
+	return readl_relaxed_poll_timeout(base + HISTB_TRNG_STAT,
+					  val, val & 0x7, SLEEP_US, TIMEOUT_US);
+}
+
+static int histb_trng_init(struct hwrng *rng)
+{
+	void __iomem *base = (void __iomem *) rng->priv;
+	u32 val;
+
+	val = readl_relaxed(base + HISTB_TRNG_CTRL);
+
+	/* select rng source 2 */
+	val &= ~0x3;
+	val |= 2;
+	/* post_process_depth */
+	val &= ~(0xf << 8);
+	val |= 9 << 8;
+
+	val |= BIT(7);  /* post_process_enable */
+	val |= BIT(5);  /* drop_enable */
+
+	writel_relaxed(val, base + HISTB_TRNG_CTRL);
+
+	/* is device up? */
+	if (histb_trng_wait(rng)) {
+		pr_err("failed to init rng device\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int histb_trng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+	void __iomem *base = (void __iomem *) rng->priv;
+	size_t i;
+	int ret;
+
+	for (i = 0; i < max; i += sizeof(u32)) {
+		ret = histb_trng_wait(rng);
+		if (ret) {
+			pr_err("failed to generate random number, generated %d\n", i);
+			return i ? i : ret;
+		}
+
+		*((u32 *) data + i) = readl_relaxed(base + HISTB_TRNG_NUMBER);
+	}
+
+	return i;
+}
+
+static int histb_trng_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct hwrng *rng;
+	struct resource *res;
+	int ret;
+
+	rng = devm_kzalloc(dev, sizeof(*rng), GFP_KERNEL);
+	if (!rng)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	rng->priv = (unsigned long) devm_ioremap(dev, res->start, resource_size(res));
+	if (!rng->priv)
+		return -ENOMEM;
+
+	rng->name = KBUILD_MODNAME;
+	rng->init = histb_trng_init;
+	rng->read = histb_trng_read;
+
+	ret = devm_hwrng_register(dev, rng);
+	if (ret) {
+		dev_err(dev, "failed to register %s (%d)\n", rng->name, ret);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, rng);
+	return 0;
+}
+
+static const struct of_device_id histb_trng_of_match[] = {
+	{ .compatible = "hisilicon,histb-trng", },
+	{ }
+};
+
+static struct platform_driver histb_trng_driver = {
+	.probe = histb_trng_probe,
+	.driver = {
+		.name = "histb-trng",
+		.of_match_table = of_match_ptr(histb_trng_of_match),
+	},
+};
+
+module_platform_driver(histb_trng_driver);
+
+MODULE_DESCRIPTION("HiSTB True RNG");
+MODULE_LICENSE("Dual MIT/GPL");