hwrng: hisi - add HiSilicon TRNG driver support

This series adds HiSilicon true random number generator(TRNG)
driver in hw_random subsystem.

Signed-off-by: Zaibo Xu <xuzaibo@huawei.com>
Signed-off-by: Weili Qian <qianweili@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/Kconfig

@@ -308,6 +308,19 @@ config HW_RANDOM_HISI
 
 	  If unsure, say Y.
 
+config HW_RANDOM_HISI_V2
+	tristate "HiSilicon True Random Number Generator V2 support"
+	depends on HW_RANDOM && ARM64 && ACPI
+	default HW_RANDOM
+	help
+	  This driver provides kernel-side support for the True Random Number
+	  Generator V2 hardware found on HiSilicon Hi1620 SoC.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hisi-trng-v2.
+
+	  If unsure, say Y.
+
 config HW_RANDOM_ST
 	tristate "ST Microelectronics HW Random Number Generator support"
 	depends on HW_RANDOM && ARCH_STI

drivers/char/hw_random/Makefile

@@ -27,6 +27,7 @@ obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o
 obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o
 obj-$(CONFIG_HW_RANDOM_POWERNV) += powernv-rng.o
 obj-$(CONFIG_HW_RANDOM_HISI)	+= hisi-rng.o
+obj-$(CONFIG_HW_RANDOM_HISI_V2) += hisi-trng-v2.o
 obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
 obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
 obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o

drivers/char/hw_random/hisi-trng-v2.c

@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 HiSilicon Limited. */
+
+#include <linux/acpi.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/platform_device.h>
+#include <linux/random.h>
+
+#define HISI_TRNG_REG		0x00F0
+#define HISI_TRNG_BYTES		4
+#define HISI_TRNG_QUALITY	512
+#define SLEEP_US		10
+#define TIMEOUT_US		10000
+
+struct hisi_trng {
+	void __iomem *base;
+	struct hwrng rng;
+};
+
+static int hisi_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	struct hisi_trng *trng;
+	int currsize = 0;
+	u32 val = 0;
+	u32 ret;
+
+	trng = container_of(rng, struct hisi_trng, rng);
+
+	do {
+		ret = readl_poll_timeout(trng->base + HISI_TRNG_REG, val,
+					 val, SLEEP_US, TIMEOUT_US);
+		if (ret)
+			return currsize;
+
+		if (max - currsize >= HISI_TRNG_BYTES) {
+			memcpy(buf + currsize, &val, HISI_TRNG_BYTES);
+			currsize += HISI_TRNG_BYTES;
+			if (currsize == max)
+				return currsize;
+			continue;
+		}
+
+		/* copy remaining bytes */
+		memcpy(buf + currsize, &val, max - currsize);
+		currsize = max;
+	} while (currsize < max);
+
+	return currsize;
+}
+
+static int hisi_trng_probe(struct platform_device *pdev)
+{
+	struct hisi_trng *trng;
+	int ret;
+
+	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
+	if (!trng)
+		return -ENOMEM;
+
+	trng->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(trng->base))
+		return PTR_ERR(trng->base);
+
+	trng->rng.name = pdev->name;
+	trng->rng.read = hisi_trng_read;
+	trng->rng.quality = HISI_TRNG_QUALITY;
+
+	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
+	if (ret)
+		dev_err(&pdev->dev, "failed to register hwrng!\n");
+
+	return ret;
+}
+
+static const struct acpi_device_id hisi_trng_acpi_match[] = {
+	{ "HISI02B3", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, hisi_trng_acpi_match);
+
+static struct platform_driver hisi_trng_driver = {
+	.probe		= hisi_trng_probe,
+	.driver		= {
+		.name	= "hisi-trng-v2",
+		.acpi_match_table = ACPI_PTR(hisi_trng_acpi_match),
+	},
+};
+
+module_platform_driver(hisi_trng_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Weili Qian <qianweili@huawei.com>");
+MODULE_AUTHOR("Zaibo Xu <xuzaibo@huawei.com>");
+MODULE_DESCRIPTION("HiSilicon true random number generator V2 driver");