[PATCH v4 2/2] hwrng: hisi: Add support for Hisilicon SoC RNG

[Kefeng Wang <wangkefeng.wang@huawei.com>]

This adds the Hisilicon Random Number Generator(RNG) support,
which is found in Hip04 and Hip05 soc.

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 drivers/char/hw_random/Kconfig    |  13 ++++
 drivers/char/hw_random/Makefile   |   1 +
 drivers/char/hw_random/hisi-rng.c | 126 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 140 insertions(+)
 create mode 100644 drivers/char/hw_random/hisi-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 67ee8b0..088b1bf 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -333,6 +333,19 @@ config HW_RANDOM_TPM
 
 	  If unsure, say Y.
 
+config HW_RANDOM_HISI
+	tristate "Hisilicon Random Number Generator support"
+	depends on HW_RANDOM && ARCH_HISI
+	default HW_RANDOM
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on Hisilicon Hip04 and Hip05 SoC.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hisi-rng.
+
+	  If unsure, say Y.
+
 config HW_RANDOM_MSM
 	tristate "Qualcomm SoCs Random Number Generator support"
 	depends on HW_RANDOM && ARCH_QCOM
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index f5a6fa7..e09305b 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_HW_RANDOM_PPC4XX) += ppc4xx-rng.o
 obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o
 obj-$(CONFIG_HW_RANDOM_POWERNV) += powernv-rng.o
 obj-$(CONFIG_HW_RANDOM_EXYNOS)	+= exynos-rng.o
+obj-$(CONFIG_HW_RANDOM_HISI)	+= hisi-rng.o
 obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
 obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
 obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
diff --git a/drivers/char/hw_random/hisi-rng.c b/drivers/char/hw_random/hisi-rng.c
new file mode 100644
index 0000000..40d9657
--- /dev/null
+++ b/drivers/char/hw_random/hisi-rng.c
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2016 HiSilicon Co., Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/random.h>
+
+#define RNG_SEED	0x0
+#define RNG_CTRL	0x4
+  #define RNG_SEED_SEL	BIT(2)
+  #define RNG_RING_EN	BIT(1)
+  #define RNG_EN	BIT(0)
+#define RNG_RAN_NUM	0x10
+#define RNG_PHY_SEED	0x14
+
+#define to_hisi_rng(p)	container_of(p, struct hisi_rng, rng)
+
+static int seed_sel;
+module_param(seed_sel, int, S_IRUGO);
+MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator.");
+
+struct hisi_rng {
+	void __iomem *base;
+	struct hwrng rng;
+};
+
+static int hisi_rng_init(struct hwrng *rng)
+{
+	struct hisi_rng *hrng = to_hisi_rng(rng);
+	int val = RNG_EN;
+	u32 seed;
+
+	/* get a random number as initial seed */
+	get_random_bytes(&seed, sizeof(seed));
+
+	writel_relaxed(seed, hrng->base + RNG_SEED);
+
+	/**
+	 * The seed is reload periodically, there are two choice
+	 * of seeds, default seed using the value from LFSR, or
+	 * will use seed generated by ring oscillator.
+	 */
+	if (seed_sel == 1)
+		val |= RNG_RING_EN | RNG_SEED_SEL;
+
+	writel_relaxed(val, hrng->base + RNG_CTRL);
+	return 0;
+}
+
+static void hisi_rng_cleanup(struct hwrng *rng)
+{
+	struct hisi_rng *hrng = to_hisi_rng(rng);
+
+	writel_relaxed(0, hrng->base + RNG_CTRL);
+}
+
+static int hisi_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	struct hisi_rng *hrng = to_hisi_rng(rng);
+	u32 *data = buf;
+
+	*data = readl_relaxed(hrng->base + RNG_RAN_NUM);
+	return 4;
+}
+
+static int hisi_rng_probe(struct platform_device *pdev)
+{
+	struct hisi_rng *rng;
+	struct resource *res;
+	int ret;
+
+	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
+	if (!rng)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, rng);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	rng->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(rng->base))
+		return PTR_ERR(rng->base);
+
+	rng->rng.name = pdev->name;
+	rng->rng.init = hisi_rng_init;
+	rng->rng.cleanup = hisi_rng_cleanup;
+	rng->rng.read = hisi_rng_read;
+
+	ret = devm_hwrng_register(&pdev->dev, &rng->rng);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register hwrng\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id hisi_rng_dt_ids[] = {
+	{ .compatible = "hisilicon,hip04-rng" },
+	{ .compatible = "hisilicon,hip05-rng" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids);
+
+static struct platform_driver hisi_rng_driver = {
+	.probe		= hisi_rng_probe,
+	.driver		= {
+		.name	= "hisi-rng",
+		.of_match_table = of_match_ptr(hisi_rng_dt_ids),
+	},
+};
+
+module_platform_driver(hisi_rng_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>");
+MODULE_DESCRIPTION("Hisilicon random number generator driver");
-- 
1.7.12.4