9 files changed, 581 insertions, 336 deletions

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 0cafe08919c9..1b223c32a8ae 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -294,20 +294,6 @@ config HW_RANDOM_POWERNV
 
 	  If unsure, say Y.
 
-config HW_RANDOM_EXYNOS
-	tristate "EXYNOS HW random number generator support"
-	depends on ARCH_EXYNOS || COMPILE_TEST
-	depends on HAS_IOMEM
-	default HW_RANDOM
-	---help---
-	  This driver provides kernel-side support for the Random Number
-	  Generator hardware found on EXYNOS SOCs.
-
-	  To compile this driver as a module, choose M here: the
-	  module will be called exynos-rng.
-
-	  If unsure, say Y.
-
 config HW_RANDOM_TPM
 	tristate "TPM HW Random Number Generator support"
 	depends on TCG_TPM
@@ -423,6 +409,34 @@ config HW_RANDOM_CAVIUM
 
          If unsure, say Y.
 
+config HW_RANDOM_MTK
+	tristate "Mediatek Random Number Generator support"
+	depends on HW_RANDOM
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	default y
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on Mediatek SoCs.
+
+	  To compile this driver as a module, choose M here. the
+	  module will be called mtk-rng.
+
+	  If unsure, say Y.
+
+config HW_RANDOM_S390
+	tristate "S390 True Random Number Generator support"
+	depends on S390
+	default HW_RANDOM
+	---help---
+	  This driver provides kernel-side support for the True
+	  Random Number Generator available as CPACF extension
+	  on modern s390 hardware platforms.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called s390-trng.
+
+	  If unsure, say Y.
+
 endif # HW_RANDOM
 
 config UML_RANDOM
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 5f52b1e4e7be..b085975ec1d2 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -24,7 +24,6 @@ obj-$(CONFIG_HW_RANDOM_OCTEON) += octeon-rng.o
 obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o
 obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o
 obj-$(CONFIG_HW_RANDOM_POWERNV) += powernv-rng.o
-obj-$(CONFIG_HW_RANDOM_EXYNOS)	+= exynos-rng.o
 obj-$(CONFIG_HW_RANDOM_HISI)	+= hisi-rng.o
 obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
 obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
@@ -36,3 +35,5 @@ obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
 obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
 obj-$(CONFIG_HW_RANDOM_MESON) += meson-rng.o
 obj-$(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
diff --git a/drivers/char/hw_random/exynos-rng.c b/drivers/char/hw_random/exynos-rng.c
deleted file mode 100644
index 23d358553b21..000000000000
--- a/drivers/char/hw_random/exynos-rng.c
+++ /dev/null
@@ -1,231 +0,0 @@
-/*
- * exynos-rng.c - Random Number Generator driver for the exynos
- *
- * Copyright (C) 2012 Samsung Electronics
- * Jonghwa Lee <jonghwa3.lee@samsung.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation;
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- *
- */
-
-#include <linux/hw_random.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/io.h>
-#include <linux/platform_device.h>
-#include <linux/clk.h>
-#include <linux/pm_runtime.h>
-#include <linux/err.h>
-
-#define EXYNOS_PRNG_STATUS_OFFSET	0x10
-#define EXYNOS_PRNG_SEED_OFFSET		0x140
-#define EXYNOS_PRNG_OUT1_OFFSET		0x160
-#define SEED_SETTING_DONE		BIT(1)
-#define PRNG_START			0x18
-#define PRNG_DONE			BIT(5)
-#define EXYNOS_AUTOSUSPEND_DELAY	100
-
-struct exynos_rng {
-	struct device *dev;
-	struct hwrng rng;
-	void __iomem *mem;
-	struct clk *clk;
-};
-
-static u32 exynos_rng_readl(struct exynos_rng *rng, u32 offset)
-{
-	return	readl_relaxed(rng->mem + offset);
-}
-
-static void exynos_rng_writel(struct exynos_rng *rng, u32 val, u32 offset)
-{
-	writel_relaxed(val, rng->mem + offset);
-}
-
-static int exynos_rng_configure(struct exynos_rng *exynos_rng)
-{
-	int i;
-	int ret = 0;
-
-	for (i = 0 ; i < 5 ; i++)
-		exynos_rng_writel(exynos_rng, jiffies,
-				EXYNOS_PRNG_SEED_OFFSET + 4*i);
-
-	if (!(exynos_rng_readl(exynos_rng, EXYNOS_PRNG_STATUS_OFFSET)
-						 & SEED_SETTING_DONE))
-		ret = -EIO;
-
-	return ret;
-}
-
-static int exynos_init(struct hwrng *rng)
-{
-	struct exynos_rng *exynos_rng = container_of(rng,
-						struct exynos_rng, rng);
-	int ret = 0;
-
-	pm_runtime_get_sync(exynos_rng->dev);
-	ret = exynos_rng_configure(exynos_rng);
-	pm_runtime_mark_last_busy(exynos_rng->dev);
-	pm_runtime_put_autosuspend(exynos_rng->dev);
-
-	return ret;
-}
-
-static int exynos_read(struct hwrng *rng, void *buf,
-					size_t max, bool wait)
-{
-	struct exynos_rng *exynos_rng = container_of(rng,
-						struct exynos_rng, rng);
-	u32 *data = buf;
-	int retry = 100;
-	int ret = 4;
-
-	pm_runtime_get_sync(exynos_rng->dev);
-
-	exynos_rng_writel(exynos_rng, PRNG_START, 0);
-
-	while (!(exynos_rng_readl(exynos_rng,
-			EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE) && --retry)
-		cpu_relax();
-	if (!retry) {
-		ret = -ETIMEDOUT;
-		goto out;
-	}
-
-	exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);
-
-	*data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET);
-
-out:
-	pm_runtime_mark_last_busy(exynos_rng->dev);
-	pm_runtime_put_sync_autosuspend(exynos_rng->dev);
-
-	return ret;
-}
-
-static int exynos_rng_probe(struct platform_device *pdev)
-{
-	struct exynos_rng *exynos_rng;
-	struct resource *res;
-	int ret;
-
-	exynos_rng = devm_kzalloc(&pdev->dev, sizeof(struct exynos_rng),
-					GFP_KERNEL);
-	if (!exynos_rng)
-		return -ENOMEM;
-
-	exynos_rng->dev = &pdev->dev;
-	exynos_rng->rng.name = "exynos";
-	exynos_rng->rng.init =	exynos_init;
-	exynos_rng->rng.read = exynos_read;
-	exynos_rng->clk = devm_clk_get(&pdev->dev, "secss");
-	if (IS_ERR(exynos_rng->clk)) {
-		dev_err(&pdev->dev, "Couldn't get clock.\n");
-		return -ENOENT;
-	}
-
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	exynos_rng->mem = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(exynos_rng->mem))
-		return PTR_ERR(exynos_rng->mem);
-
-	platform_set_drvdata(pdev, exynos_rng);
-
-	pm_runtime_set_autosuspend_delay(&pdev->dev, EXYNOS_AUTOSUSPEND_DELAY);
-	pm_runtime_use_autosuspend(&pdev->dev);
-	pm_runtime_enable(&pdev->dev);
-
-	ret = devm_hwrng_register(&pdev->dev, &exynos_rng->rng);
-	if (ret) {
-		pm_runtime_dont_use_autosuspend(&pdev->dev);
-		pm_runtime_disable(&pdev->dev);
-	}
-
-	return ret;
-}
-
-static int exynos_rng_remove(struct platform_device *pdev)
-{
-	pm_runtime_dont_use_autosuspend(&pdev->dev);
-	pm_runtime_disable(&pdev->dev);
-
-	return 0;
-}
-
-static int __maybe_unused exynos_rng_runtime_suspend(struct device *dev)
-{
-	struct platform_device *pdev = to_platform_device(dev);
-	struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
-
-	clk_disable_unprepare(exynos_rng->clk);
-
-	return 0;
-}
-
-static int __maybe_unused exynos_rng_runtime_resume(struct device *dev)
-{
-	struct platform_device *pdev = to_platform_device(dev);
-	struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
-
-	return clk_prepare_enable(exynos_rng->clk);
-}
-
-static int __maybe_unused exynos_rng_suspend(struct device *dev)
-{
-	return pm_runtime_force_suspend(dev);
-}
-
-static int __maybe_unused exynos_rng_resume(struct device *dev)
-{
-	struct platform_device *pdev = to_platform_device(dev);
-	struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
-	int ret;
-
-	ret = pm_runtime_force_resume(dev);
-	if (ret)
-		return ret;
-
-	return exynos_rng_configure(exynos_rng);
-}
-
-static const struct dev_pm_ops exynos_rng_pm_ops = {
-	SET_SYSTEM_SLEEP_PM_OPS(exynos_rng_suspend, exynos_rng_resume)
-	SET_RUNTIME_PM_OPS(exynos_rng_runtime_suspend,
-			   exynos_rng_runtime_resume, NULL)
-};
-
-static const struct of_device_id exynos_rng_dt_match[] = {
-	{
-		.compatible = "samsung,exynos4-rng",
-	},
-	{ },
-};
-MODULE_DEVICE_TABLE(of, exynos_rng_dt_match);
-
-static struct platform_driver exynos_rng_driver = {
-	.driver		= {
-		.name	= "exynos-rng",
-		.pm	= &exynos_rng_pm_ops,
-		.of_match_table = exynos_rng_dt_match,
-	},
-	.probe		= exynos_rng_probe,
-	.remove		= exynos_rng_remove,
-};
-
-module_platform_driver(exynos_rng_driver);
-
-MODULE_DESCRIPTION("EXYNOS 4 H/W Random Number Generator driver");
-MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>");
-MODULE_LICENSE("GPL");
diff --git a/drivers/char/hw_random/meson-rng.c b/drivers/char/hw_random/meson-rng.c
index 119d698439ae..2e23be802a62 100644
--- a/drivers/char/hw_random/meson-rng.c
+++ b/drivers/char/hw_random/meson-rng.c
@@ -62,6 +62,7 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/of.h>
+#include <linux/clk.h>
 
 #define RNG_DATA 0x00
 
@@ -69,6 +70,7 @@ struct meson_rng_data {
 	void __iomem *base;
 	struct platform_device *pdev;
 	struct hwrng rng;
+	struct clk *core_clk;
 };
 
 static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
@@ -81,11 +83,17 @@ static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 	return sizeof(u32);
 }
 
+static void meson_rng_clk_disable(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
 static int meson_rng_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct meson_rng_data *data;
 	struct resource *res;
+	int ret;
 
 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
@@ -98,6 +106,20 @@ static int meson_rng_probe(struct platform_device *pdev)
 	if (IS_ERR(data->base))
 		return PTR_ERR(data->base);
 
+	data->core_clk = devm_clk_get(dev, "core");
+	if (IS_ERR(data->core_clk))
+		data->core_clk = NULL;
+
+	if (data->core_clk) {
+		ret = clk_prepare_enable(data->core_clk);
+		if (ret)
+			return ret;
+		ret = devm_add_action_or_reset(dev, meson_rng_clk_disable,
+					       data->core_clk);
+		if (ret)
+			return ret;
+	}
+
 	data->rng.name = pdev->name;
 	data->rng.read = meson_rng_read;
 
diff --git a/drivers/char/hw_random/mtk-rng.c b/drivers/char/hw_random/mtk-rng.c
new file mode 100644
index 000000000000..df8eb54fd5a3
--- /dev/null
+++ b/drivers/char/hw_random/mtk-rng.c
@@ -0,0 +1,168 @@
+/*
+ * Driver for Mediatek Hardware Random Number Generator
+ *
+ * Copyright (C) 2017 Sean Wang <sean.wang@mediatek.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+#define MTK_RNG_DEV KBUILD_MODNAME
+
+#include <linux/clk.h>
+#include <linux/delay.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>
+
+#define USEC_POLL			2
+#define TIMEOUT_POLL			20
+
+#define RNG_CTRL			0x00
+#define RNG_EN				BIT(0)
+#define RNG_READY			BIT(31)
+
+#define RNG_DATA			0x08
+
+#define to_mtk_rng(p)	container_of(p, struct mtk_rng, rng)
+
+struct mtk_rng {
+	void __iomem *base;
+	struct clk *clk;
+	struct hwrng rng;
+};
+
+static int mtk_rng_init(struct hwrng *rng)
+{
+	struct mtk_rng *priv = to_mtk_rng(rng);
+	u32 val;
+	int err;
+
+	err = clk_prepare_enable(priv->clk);
+	if (err)
+		return err;
+
+	val = readl(priv->base + RNG_CTRL);
+	val |= RNG_EN;
+	writel(val, priv->base + RNG_CTRL);
+
+	return 0;
+}
+
+static void mtk_rng_cleanup(struct hwrng *rng)
+{
+	struct mtk_rng *priv = to_mtk_rng(rng);
+	u32 val;
+
+	val = readl(priv->base + RNG_CTRL);
+	val &= ~RNG_EN;
+	writel(val, priv->base + RNG_CTRL);
+
+	clk_disable_unprepare(priv->clk);
+}
+
+static bool mtk_rng_wait_ready(struct hwrng *rng, bool wait)
+{
+	struct mtk_rng *priv = to_mtk_rng(rng);
+	int ready;
+
+	ready = readl(priv->base + RNG_CTRL) & RNG_READY;
+	if (!ready && wait)
+		readl_poll_timeout_atomic(priv->base + RNG_CTRL, ready,
+					  ready & RNG_READY, USEC_POLL,
+					  TIMEOUT_POLL);
+	return !!ready;
+}
+
+static int mtk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	struct mtk_rng *priv = to_mtk_rng(rng);
+	int retval = 0;
+
+	while (max >= sizeof(u32)) {
+		if (!mtk_rng_wait_ready(rng, wait))
+			break;
+
+		*(u32 *)buf = readl(priv->base + RNG_DATA);
+		retval += sizeof(u32);
+		buf += sizeof(u32);
+		max -= sizeof(u32);
+	}
+
+	return retval || !wait ? retval : -EIO;
+}
+
+static int mtk_rng_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	int ret;
+	struct mtk_rng *priv;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "no iomem resource\n");
+		return -ENXIO;
+	}
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->rng.name = pdev->name;
+	priv->rng.init = mtk_rng_init;
+	priv->rng.cleanup = mtk_rng_cleanup;
+	priv->rng.read = mtk_rng_read;
+
+	priv->clk = devm_clk_get(&pdev->dev, "rng");
+	if (IS_ERR(priv->clk)) {
+		ret = PTR_ERR(priv->clk);
+		dev_err(&pdev->dev, "no clock for device: %d\n", ret);
+		return ret;
+	}
+
+	priv->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	ret = devm_hwrng_register(&pdev->dev, &priv->rng);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register rng device: %d\n",
+			ret);
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "registered RNG driver\n");
+
+	return 0;
+}
+
+static const struct of_device_id mtk_rng_match[] = {
+	{ .compatible = "mediatek,mt7623-rng" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mtk_rng_match);
+
+static struct platform_driver mtk_rng_driver = {
+	.probe          = mtk_rng_probe,
+	.driver = {
+		.name = MTK_RNG_DEV,
+		.of_match_table = mtk_rng_match,
+	},
+};
+
+module_platform_driver(mtk_rng_driver);
+
+MODULE_DESCRIPTION("Mediatek Random Number Generator Driver");
+MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/char/hw_random/n2-drv.c b/drivers/char/hw_random/n2-drv.c
index 31cbdbbaebfc..92dd4e925315 100644
--- a/drivers/char/hw_random/n2-drv.c
+++ b/drivers/char/hw_random/n2-drv.c
@@ -748,9 +748,7 @@ static int n2rng_probe(struct platform_device *op)
 
 	dev_info(&op->dev, "Registered RNG HVAPI major %lu minor %lu\n",
 		 np->hvapi_major, np->hvapi_minor);
-
-	np->units = devm_kzalloc(&op->dev,
-				 sizeof(struct n2rng_unit) * np->num_units,
+	np->units = devm_kcalloc(&op->dev, np->num_units, sizeof(*np->units),
 				 GFP_KERNEL);
 	err = -ENOMEM;
 	if (!np->units)
diff --git a/drivers/char/hw_random/omap-rng.c b/drivers/char/hw_random/omap-rng.c
index b1ad12552b56..74d11ae6abe9 100644
--- a/drivers/char/hw_random/omap-rng.c
+++ b/drivers/char/hw_random/omap-rng.c
@@ -398,16 +398,6 @@ static int of_get_omap_rng_device_details(struct omap_rng_dev *priv,
 			return err;
 		}
 
-		priv->clk = devm_clk_get(&pdev->dev, NULL);
-		if (IS_ERR(priv->clk) && PTR_ERR(priv->clk) == -EPROBE_DEFER)
-			return -EPROBE_DEFER;
-		if (!IS_ERR(priv->clk)) {
-			err = clk_prepare_enable(priv->clk);
-			if (err)
-				dev_err(&pdev->dev, "unable to enable the clk, "
-						    "err = %d\n", err);
-		}
-
 		/*
 		 * On OMAP4, enabling the shutdown_oflo interrupt is
 		 * done in the interrupt mask register. There is no
@@ -478,6 +468,18 @@ static int omap_rng_probe(struct platform_device *pdev)
 		goto err_ioremap;
 	}
 
+	priv->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->clk) && PTR_ERR(priv->clk) == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+	if (!IS_ERR(priv->clk)) {
+		ret = clk_prepare_enable(priv->clk);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"Unable to enable the clk: %d\n", ret);
+			goto err_register;
+		}
+	}
+
 	ret = (dev->of_node) ? of_get_omap_rng_device_details(priv, pdev) :
 				get_omap_rng_device_details(priv);
 	if (ret)
diff --git a/drivers/char/hw_random/s390-trng.c b/drivers/char/hw_random/s390-trng.c
new file mode 100644
index 000000000000..aca48e893fca
--- /dev/null
+++ b/drivers/char/hw_random/s390-trng.c
@@ -0,0 +1,268 @@
+/*
+ * s390 TRNG device driver
+ *
+ * Driver for the TRNG (true random number generation) command
+ * available via CPACF extension MSA 7 on the s390 arch.
+
+ * Copyright IBM Corp. 2017
+ * Author(s): Harald Freudenberger <freude@de.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ *
+ */
+
+#define KMSG_COMPONENT "trng"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/hw_random.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/cpufeature.h>
+#include <linux/miscdevice.h>
+#include <linux/debugfs.h>
+#include <linux/atomic.h>
+#include <linux/random.h>
+#include <linux/sched/signal.h>
+#include <asm/debug.h>
+#include <asm/cpacf.h>
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("IBM Corporation");
+MODULE_DESCRIPTION("s390 CPACF TRNG device driver");
+
+
+/* trng related debug feature things */
+
+static debug_info_t *debug_info;
+
+#define DEBUG_DBG(...)	debug_sprintf_event(debug_info, 6, ##__VA_ARGS__)
+#define DEBUG_INFO(...) debug_sprintf_event(debug_info, 5, ##__VA_ARGS__)
+#define DEBUG_WARN(...) debug_sprintf_event(debug_info, 4, ##__VA_ARGS__)
+#define DEBUG_ERR(...)	debug_sprintf_event(debug_info, 3, ##__VA_ARGS__)
+
+
+/* trng helpers */
+
+static atomic64_t trng_dev_counter = ATOMIC64_INIT(0);
+static atomic64_t trng_hwrng_counter = ATOMIC64_INIT(0);
+
+
+/* file io functions */
+
+static int trng_open(struct inode *inode, struct file *file)
+{
+	return nonseekable_open(inode, file);
+}
+
+static ssize_t trng_read(struct file *file, char __user *ubuf,
+			 size_t nbytes, loff_t *ppos)
+{
+	u8 buf[32];
+	u8 *p = buf;
+	unsigned int n;
+	ssize_t ret = 0;
+
+	/*
+	 * use buf for requests <= sizeof(buf),
+	 * otherwise allocate one page and fetch
+	 * pagewise.
+	 */
+
+	if (nbytes > sizeof(buf)) {
+		p = (u8 *) __get_free_page(GFP_KERNEL);
+		if (!p)
+			return -ENOMEM;
+	}
+
+	while (nbytes) {
+		if (need_resched()) {
+			if (signal_pending(current)) {
+				if (ret == 0)
+					ret = -ERESTARTSYS;
+				break;
+			}
+			schedule();
+		}
+		n = nbytes > PAGE_SIZE ? PAGE_SIZE : nbytes;
+		cpacf_trng(NULL, 0, p, n);
+		atomic64_add(n, &trng_dev_counter);
+		if (copy_to_user(ubuf, p, n)) {
+			ret = -EFAULT;
+			break;
+		}
+		nbytes -= n;
+		ubuf += n;
+		ret += n;
+	}
+
+	if (p != buf)
+		free_page((unsigned long) p);
+
+	DEBUG_DBG("trng_read()=%zd\n", ret);
+	return ret;
+}
+
+
+/* sysfs */
+
+static ssize_t trng_counter_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	u64 dev_counter = atomic64_read(&trng_dev_counter);
+	u64 hwrng_counter = atomic64_read(&trng_hwrng_counter);
+#if IS_ENABLED(CONFIG_ARCH_RANDOM)
+	u64 arch_counter = atomic64_read(&s390_arch_random_counter);
+
+	return snprintf(buf, PAGE_SIZE,
+			"trng:  %llu\n"
+			"hwrng: %llu\n"
+			"arch:  %llu\n"
+			"total: %llu\n",
+			dev_counter, hwrng_counter, arch_counter,
+			dev_counter + hwrng_counter + arch_counter);
+#else
+	return snprintf(buf, PAGE_SIZE,
+			"trng:  %llu\n"
+			"hwrng: %llu\n"
+			"total: %llu\n",
+			dev_counter, hwrng_counter,
+			dev_counter + hwrng_counter);
+#endif
+}
+static DEVICE_ATTR(byte_counter, 0444, trng_counter_show, NULL);
+
+static struct attribute *trng_dev_attrs[] = {
+	&dev_attr_byte_counter.attr,
+	NULL
+};
+
+static const struct attribute_group trng_dev_attr_group = {
+	.attrs = trng_dev_attrs
+};
+
+static const struct attribute_group *trng_dev_attr_groups[] = {
+	&trng_dev_attr_group,
+	NULL
+};
+
+static const struct file_operations trng_fops = {
+	.owner		= THIS_MODULE,
+	.open		= &trng_open,
+	.release	= NULL,
+	.read		= &trng_read,
+	.llseek		= noop_llseek,
+};
+
+static struct miscdevice trng_dev = {
+	.name	= "trng",
+	.minor	= MISC_DYNAMIC_MINOR,
+	.mode	= 0444,
+	.fops	= &trng_fops,
+	.groups = trng_dev_attr_groups,
+};
+
+
+/* hwrng_register */
+
+static inline void _trng_hwrng_read(u8 *buf, size_t len)
+{
+	cpacf_trng(NULL, 0, buf, len);
+	atomic64_add(len, &trng_hwrng_counter);
+}
+
+static int trng_hwrng_data_read(struct hwrng *rng, u32 *data)
+{
+	size_t len = sizeof(*data);
+
+	_trng_hwrng_read((u8 *) data, len);
+
+	DEBUG_DBG("trng_hwrng_data_read()=%zu\n", len);
+
+	return len;
+}
+
+static int trng_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+	size_t len = max <= PAGE_SIZE ? max : PAGE_SIZE;
+
+	_trng_hwrng_read((u8 *) data, len);
+
+	DEBUG_DBG("trng_hwrng_read()=%zu\n", len);
+
+	return len;
+}
+
+/*
+ * hwrng register struct
+ * The trng is suppost to have 100% entropy, and thus
+ * we register with a very high quality value.
+ */
+static struct hwrng trng_hwrng_dev = {
+	.name		= "s390-trng",
+	.data_read	= trng_hwrng_data_read,
+	.read		= trng_hwrng_read,
+	.quality	= 999,
+};
+
+
+/* init and exit */
+
+static void __init trng_debug_init(void)
+{
+	debug_info = debug_register("trng", 1, 1, 4 * sizeof(long));
+	debug_register_view(debug_info, &debug_sprintf_view);
+	debug_set_level(debug_info, 3);
+}
+
+static void trng_debug_exit(void)
+{
+	debug_unregister(debug_info);
+}
+
+static int __init trng_init(void)
+{
+	int ret;
+
+	trng_debug_init();
+
+	/* check if subfunction CPACF_PRNO_TRNG is available */
+	if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG)) {
+		DEBUG_INFO("trng_init CPACF_PRNO_TRNG not available\n");
+		ret = -ENODEV;
+		goto out_dbg;
+	}
+
+	ret = misc_register(&trng_dev);
+	if (ret) {
+		DEBUG_WARN("trng_init misc_register() failed rc=%d\n", ret);
+		goto out_dbg;
+	}
+
+	ret = hwrng_register(&trng_hwrng_dev);
+	if (ret) {
+		DEBUG_WARN("trng_init hwrng_register() failed rc=%d\n", ret);
+		goto out_misc;
+	}
+
+	DEBUG_DBG("trng_init successful\n");
+
+	return 0;
+
+out_misc:
+	misc_deregister(&trng_dev);
+out_dbg:
+	trng_debug_exit();
+	return ret;
+}
+
+static void __exit trng_exit(void)
+{
+	hwrng_unregister(&trng_hwrng_dev);
+	misc_deregister(&trng_dev);
+	trng_debug_exit();
+}
+
+module_cpu_feature_match(MSA, trng_init);
+module_exit(trng_exit);
diff --git a/drivers/char/hw_random/timeriomem-rng.c b/drivers/char/hw_random/timeriomem-rng.c
index cf37db263ecd..a0faa5f05deb 100644
--- a/drivers/char/hw_random/timeriomem-rng.c
+++ b/drivers/char/hw_random/timeriomem-rng.c
@@ -20,84 +20,100 @@
  * TODO: add support for reading sizes other than 32bits and masking
  */
 
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/platform_device.h>
-#include <linux/of.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/hrtimer.h>
 #include <linux/hw_random.h>
 #include <linux/io.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/time.h>
 #include <linux/timeriomem-rng.h>
-#include <linux/jiffies.h>
-#include <linux/sched.h>
-#include <linux/timer.h>
-#include <linux/completion.h>
 
-struct timeriomem_rng_private_data {
+struct timeriomem_rng_private {
 	void __iomem		*io_base;
-	unsigned int		expires;
-	unsigned int		period;
+	ktime_t			period;
 	unsigned int		present:1;
 
-	struct timer_list	timer;
+	struct hrtimer		timer;
 	struct completion	completion;
 
-	struct hwrng		timeriomem_rng_ops;
+	struct hwrng		rng_ops;
 };
 
-#define to_rng_priv(rng) \
-		((struct timeriomem_rng_private_data *)rng->priv)
-
-/*
- * have data return 1, however return 0 if we have nothing
- */
-static int timeriomem_rng_data_present(struct hwrng *rng, int wait)
+static int timeriomem_rng_read(struct hwrng *hwrng, void *data,
+				size_t max, bool wait)
 {
-	struct timeriomem_rng_private_data *priv = to_rng_priv(rng);
-
-	if (!wait || priv->present)
-		return priv->present;
+	struct timeriomem_rng_private *priv =
+		container_of(hwrng, struct timeriomem_rng_private, rng_ops);
+	int retval = 0;
+	int period_us = ktime_to_us(priv->period);
+
+	/*
+	 * The RNG provides 32-bits per read.  Ensure there is enough space for
+	 * at minimum one read.
+	 */
+	if (max < sizeof(u32))
+		return 0;
+
+	/*
+	 * There may not have been enough time for new data to be generated
+	 * since the last request.  If the caller doesn't want to wait, let them
+	 * bail out.  Otherwise, wait for the completion.  If the new data has
+	 * already been generated, the completion should already be available.
+	 */
+	if (!wait && !priv->present)
+		return 0;
 
 	wait_for_completion(&priv->completion);
 
-	return 1;
-}
-
-static int timeriomem_rng_data_read(struct hwrng *rng, u32 *data)
-{
-	struct timeriomem_rng_private_data *priv = to_rng_priv(rng);
-	unsigned long cur;
-	s32 delay;
-
-	*data = readl(priv->io_base);
-
-	cur = jiffies;
-
-	delay = cur - priv->expires;
-	delay = priv->period - (delay % priv->period);
-
-	priv->expires = cur + delay;
+	do {
+		/*
+		 * After the first read, all additional reads will need to wait
+		 * for the RNG to generate new data.  Since the period can have
+		 * a wide range of values (1us to 1s have been observed), allow
+		 * for 1% tolerance in the sleep time rather than a fixed value.
+		 */
+		if (retval > 0)
+			usleep_range(period_us,
+					period_us + min(1, period_us / 100));
+
+		*(u32 *)data = readl(priv->io_base);
+		retval += sizeof(u32);
+		data += sizeof(u32);
+		max -= sizeof(u32);
+	} while (wait && max > sizeof(u32));
+
+	/*
+	 * Block any new callers until the RNG has had time to generate new
+	 * data.
+	 */
 	priv->present = 0;
-
 	reinit_completion(&priv->completion);
-	mod_timer(&priv->timer, priv->expires);
+	hrtimer_forward_now(&priv->timer, priv->period);
+	hrtimer_restart(&priv->timer);
 
-	return 4;
+	return retval;
 }
 
-static void timeriomem_rng_trigger(unsigned long data)
+static enum hrtimer_restart timeriomem_rng_trigger(struct hrtimer *timer)
 {
-	struct timeriomem_rng_private_data *priv
-			= (struct timeriomem_rng_private_data *)data;
+	struct timeriomem_rng_private *priv
+		= container_of(timer, struct timeriomem_rng_private, timer);
 
 	priv->present = 1;
 	complete(&priv->completion);
+
+	return HRTIMER_NORESTART;
 }
 
 static int timeriomem_rng_probe(struct platform_device *pdev)
 {
 	struct timeriomem_rng_data *pdata = pdev->dev.platform_data;
-	struct timeriomem_rng_private_data *priv;
+	struct timeriomem_rng_private *priv;
 	struct resource *res;
 	int err = 0;
 	int period;
@@ -119,7 +135,7 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 
 	/* Allocate memory for the device structure (and zero it) */
 	priv = devm_kzalloc(&pdev->dev,
-			sizeof(struct timeriomem_rng_private_data), GFP_KERNEL);
+			sizeof(struct timeriomem_rng_private), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 
@@ -139,54 +155,41 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 		period = pdata->period;
 	}
 
-	priv->period = usecs_to_jiffies(period);
-	if (priv->period < 1) {
-		dev_err(&pdev->dev, "period is less than one jiffy\n");
-		return -EINVAL;
-	}
-
-	priv->expires	= jiffies;
-	priv->present	= 1;
-
+	priv->period = ns_to_ktime(period * NSEC_PER_USEC);
 	init_completion(&priv->completion);
-	complete(&priv->completion);
+	hrtimer_init(&priv->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	priv->timer.function = timeriomem_rng_trigger;
 
-	setup_timer(&priv->timer, timeriomem_rng_trigger, (unsigned long)priv);
-
-	priv->timeriomem_rng_ops.name		= dev_name(&pdev->dev);
-	priv->timeriomem_rng_ops.data_present	= timeriomem_rng_data_present;
-	priv->timeriomem_rng_ops.data_read	= timeriomem_rng_data_read;
-	priv->timeriomem_rng_ops.priv		= (unsigned long)priv;
+	priv->rng_ops.name = dev_name(&pdev->dev);
+	priv->rng_ops.read = timeriomem_rng_read;
 
 	priv->io_base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(priv->io_base)) {
-		err = PTR_ERR(priv->io_base);
-		goto out_timer;
+		return PTR_ERR(priv->io_base);
 	}
 
-	err = hwrng_register(&priv->timeriomem_rng_ops);
+	/* Assume random data is already available. */
+	priv->present = 1;
+	complete(&priv->completion);
+
+	err = hwrng_register(&priv->rng_ops);
 	if (err) {
 		dev_err(&pdev->dev, "problem registering\n");
-		goto out_timer;
+		return err;
 	}
 
 	dev_info(&pdev->dev, "32bits from 0x%p @ %dus\n",
 			priv->io_base, period);
 
 	return 0;
-
-out_timer:
-	del_timer_sync(&priv->timer);
-	return err;
 }
 
 static int timeriomem_rng_remove(struct platform_device *pdev)
 {
-	struct timeriomem_rng_private_data *priv = platform_get_drvdata(pdev);
-
-	hwrng_unregister(&priv->timeriomem_rng_ops);
+	struct timeriomem_rng_private *priv = platform_get_drvdata(pdev);
 
-	del_timer_sync(&priv->timer);
+	hwrng_unregister(&priv->rng_ops);
+	hrtimer_cancel(&priv->timer);
 
 	return 0;
 }