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Subject[PATCH v2 2/3] hwrng: exynos - add Samsung Exynos True RNG driver
Date
Add support for True Random Number Generator found in Samsung Exynos
5250+ SoCs.

Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
---
MAINTAINERS | 7 +
drivers/char/hw_random/Kconfig | 12 ++
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/exynos-trng.c | 245 +++++++++++++++++++++++++++++++++++
4 files changed, 265 insertions(+)
create mode 100644 drivers/char/hw_random/exynos-trng.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 2811a211632c..992074cca612 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11780,6 +11780,13 @@ S: Maintained
F: drivers/crypto/exynos-rng.c
F: Documentation/devicetree/bindings/rng/samsung,exynos-rng4.txt

+SAMSUNG EXYNOS TRUE RANDOM NUMBER GENERATOR (TRNG) DRIVER
+M: Łukasz Stelmach <l.stelmach@samsung.com>
+L: linux-samsung-soc@vger.kernel.org
+S: Maintained
+F: drivers/char/hw_random/exynos-trng.c
+F: Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt
+
SAMSUNG FRAMEBUFFER DRIVER
M: Jingoo Han <jingoohan1@gmail.com>
L: linux-fbdev@vger.kernel.org
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 95a031e9eced..292e6b36d493 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -449,6 +449,18 @@ config HW_RANDOM_S390

If unsure, say Y.

+config HW_RANDOM_EXYNOS
+ tristate "Samsung Exynos True Random Number Generator support"
+ depends on ARCH_EXYNOS || COMPILE_TEST
+ default HW_RANDOM
+ ---help---
+ This driver provides support for the True Random Number
+ Generator available in Exynos SoCs.
+
+ To compile this driver as a module, choose M here: the module
+ will be called exynos-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 f3728d008fff..5595df97da7a 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_HW_RANDOM_GEODE) += geode-rng.o
obj-$(CONFIG_HW_RANDOM_N2RNG) += n2-rng.o
n2-rng-y := n2-drv.o n2-asm.o
obj-$(CONFIG_HW_RANDOM_VIA) += via-rng.o
+obj-$(CONFIG_HW_RANDOM_EXYNOS) += exynos-trng.o
obj-$(CONFIG_HW_RANDOM_IXP4XX) += ixp4xx-rng.o
obj-$(CONFIG_HW_RANDOM_OMAP) += omap-rng.o
obj-$(CONFIG_HW_RANDOM_OMAP3_ROM) += omap3-rom-rng.o
diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
new file mode 100644
index 000000000000..91b2ddb249fa
--- /dev/null
+++ b/drivers/char/hw_random/exynos-trng.c
@@ -0,0 +1,245 @@
+/*
+ * RNG driver for Exynos TRNGs
+ *
+ * Author: Łukasz Stelmach <l.stelmach@samsung.com>
+ *
+ * Copyright 2017 (c) Samsung Electronics Software, Inc.
+ *
+ * Based on the Exynos PRNG driver drivers/crypto/exynos-rng by
+ * Krzysztof Kozłowski <krzk@kernel.org>
+ *
+ * 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.
+ */
+
+#include <linux/clk.h>
+#include <linux/crypto.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/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#define EXYNOS_TRNG_CLKDIV (0x0)
+#define EXYNOS_TRNG_CTRL (0x20)
+#define EXYNOS_TRNG_POST_CTRL (0x30)
+#define EXYNOS_TRNG_ONLINE_CTRL (0x40)
+#define EXYNOS_TRNG_ONLINE_STAT (0x44)
+#define EXYNOS_TRNG_ONLINE_MAXCHI2 (0x48)
+#define EXYNOS_TRNG_FIFO_CTRL (0x50)
+#define EXYNOS_TRNG_FIFO_0 (0x80)
+#define EXYNOS_TRNG_FIFO_1 (0x84)
+#define EXYNOS_TRNG_FIFO_2 (0x88)
+#define EXYNOS_TRNG_FIFO_3 (0x8c)
+#define EXYNOS_TRNG_FIFO_4 (0x90)
+#define EXYNOS_TRNG_FIFO_5 (0x94)
+#define EXYNOS_TRNG_FIFO_6 (0x98)
+#define EXYNOS_TRNG_FIFO_7 (0x9c)
+#define EXYNOS_TRNG_FIFO_LEN (8)
+#define EXYNOS_TRNG_CLOCK_RATE (500000)
+
+#define TRNG_CTRL_RGNEN BIT(31)
+
+struct exynos_trng_dev {
+ struct device *dev;
+ void __iomem *mem;
+ struct clk *clk;
+ struct hwrng rng;
+};
+
+static int exynos_trng_do_read(struct hwrng *rng, void *data, size_t max,
+ bool wait)
+{
+ struct exynos_trng_dev *trng;
+ u32 val;
+
+ max = min_t(size_t, max, (EXYNOS_TRNG_FIFO_LEN * 4));
+
+ trng = (struct exynos_trng_dev *)rng->priv;
+
+ __raw_writel(max * 8, trng->mem + EXYNOS_TRNG_FIFO_CTRL);
+ val = readl_poll_timeout(trng->mem + EXYNOS_TRNG_FIFO_CTRL, val,
+ val == 0, 200, 1000000);
+ if (val < 0)
+ return val;
+
+ memcpy_fromio(data, trng->mem + EXYNOS_TRNG_FIFO_0, max);
+
+ return max;
+}
+
+static int exynos_trng_init(struct hwrng *rng)
+{
+ struct exynos_trng_dev *trng = (struct exynos_trng_dev *)rng->priv;
+ unsigned long sss_rate;
+ u32 val;
+
+ sss_rate = clk_get_rate(trng->clk);
+
+ /*
+ * For most TRNG circuits the clock frequency of under 500 kHz
+ * is safe.
+ */
+ val = sss_rate / (EXYNOS_TRNG_CLOCK_RATE * 2);
+ if (val > 0x7fff) {
+ dev_err(trng->dev, "clock divider too large: %d", val);
+ return -ERANGE;
+ }
+ val = val << 1;
+ __raw_writel(val, trng->mem + EXYNOS_TRNG_CLKDIV);
+
+ /* Enable the generator. */
+ val = TRNG_CTRL_RGNEN;
+ __raw_writel(val, trng->mem + EXYNOS_TRNG_CTRL);
+
+ /*
+ * Disable post-processing. /dev/hwrng is supposed to deliver
+ * unprocessed data.
+ */
+ __raw_writel(0, trng->mem + EXYNOS_TRNG_POST_CTRL);
+
+ return 0;
+}
+
+static int exynos_trng_probe(struct platform_device *pdev)
+{
+ struct exynos_trng_dev *trng;
+ struct resource *res;
+ int ret = -ENOMEM;
+
+ trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
+ if (!trng)
+ return ret;
+
+ trng->rng.name = devm_kstrdup(&pdev->dev, dev_name(&pdev->dev),
+ GFP_KERNEL);
+ if (!trng->rng.name)
+ return ret;
+
+ trng->rng.init = exynos_trng_init;
+ trng->rng.read = exynos_trng_do_read;
+ trng->rng.priv = (unsigned long) trng;
+
+ platform_set_drvdata(pdev, trng);
+ trng->dev = &pdev->dev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ trng->mem = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(trng->mem)) {
+ ret = PTR_ERR(trng->mem);
+ dev_err(&pdev->dev, "Could not map IO resources.\n");
+ goto err_ioremap;
+ }
+
+ pm_runtime_enable(&pdev->dev);
+ ret = pm_runtime_get_sync(&pdev->dev);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Could not get runtime PM.\n");
+ goto err_pm_get;
+ }
+
+ trng->clk = devm_clk_get(&pdev->dev, "secss");
+ if (IS_ERR(trng->clk)) {
+ ret = PTR_ERR(trng->clk);
+ dev_err(&pdev->dev, "Could not get clock.\n");
+ goto err_clock;
+ }
+
+ ret = clk_prepare_enable(trng->clk);
+ if (ret) {
+ dev_err(&pdev->dev, "Could not enable the clk.\n");
+ goto err_clock;
+ }
+
+ ret = hwrng_register(&trng->rng);
+ if (ret) {
+ dev_err(&pdev->dev, "Could not register hwrng device.\n");
+ goto err_register;
+ }
+
+ dev_info(&pdev->dev, "Exynos True Random Number Generator.\n");
+
+ return 0;
+
+err_register:
+ clk_disable_unprepare(trng->clk);
+
+err_clock:
+ pm_runtime_put_sync(&pdev->dev);
+
+err_pm_get:
+ pm_runtime_disable(&pdev->dev);
+
+err_ioremap:
+ return ret;
+}
+
+static int exynos_trng_remove(struct platform_device *pdev)
+{
+ struct exynos_trng_dev *trng = platform_get_drvdata(pdev);
+
+ hwrng_unregister(&trng->rng);
+ clk_disable_unprepare(trng->clk);
+
+ pm_runtime_put_sync(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
+
+ return 0;
+}
+
+static int __maybe_unused exynos_trng_suspend(struct device *dev)
+{
+ pm_runtime_put_sync(dev);
+
+ return 0;
+}
+
+static int __maybe_unused exynos_trng_resume(struct device *dev)
+{
+ int ret;
+
+ ret = pm_runtime_get_sync(dev);
+ if (ret < 0) {
+ dev_err(dev, "Could not get runtime PM.\n");
+ pm_runtime_put_noidle(dev);
+ return ret;
+ }
+
+ return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(exynos_trng_pm_ops, exynos_trng_suspend,
+ exynos_trng_resume);
+
+static const struct of_device_id exynos_trng_dt_match[] = {
+ {
+ .compatible = "samsung,exynos5250-trng",
+ },
+ { },
+};
+MODULE_DEVICE_TABLE(of, exynos_rng_dt_match);
+
+static struct platform_driver exynos_trng_driver = {
+ .driver = {
+ .name = "exynos-trng",
+ .pm = &exynos_trng_pm_ops,
+ .of_match_table = exynos_trng_dt_match,
+ },
+ .probe = exynos_trng_probe,
+ .remove = exynos_trng_remove,
+};
+
+module_platform_driver(exynos_trng_driver);
+MODULE_AUTHOR("Łukasz Stelmach");
+MODULE_DESCRIPTION("H/W TRNG driver for Exynos chips");
+MODULE_LICENSE("GPL");
--
2.11.0
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