[PATCH v2 0/3] True RNG driver for Samsung Exynos 5250+ SoCs

[PATCH v2 0/3] True RNG driver for Samsung Exynos 5250+ SoCs

[Łukasz Stelmach]

Hello.

The following patches add support for the true random number generator
found in Samsung Exynos 5250+ SoCs.

Patch #1 adds documentation for devicetree bindings.

Patch #2 introduces the driver and appropriate changes in Makefile and Kconfig.

Patch #3 adds nodes in devicetree files for Exynos SoCs.

Changes in v2:
- Fixed indentation in drivers/char/hw_random/Kconfig.
- Defined TRNG_CTRL_RGNEN.
- Removed global variable exynos_trng_dev.
- Removed exynos_trng_{set,get}_reg() functions.
- Used the min_t() macro instead of the ternary operator in
  exynos_trng_do_read().
- Moved trng initialisation to the variable declaration in
  exynos_trng_init().
- Fixed comment formating.
- Removed unnecessary "TODO" comments.
- Return ENOMEM, if devm_kzalloc() devm_kstrdup() fail.
- Rephrased and unified error messages in exynos_trng_probe().
- Removed nullification of trng->mem.
- Added err_pm_get label at the end of exynos_trng_probe().
- Removed double error message at the end of exynos_trng_probe().
- Implemented exynos_trng_remove().

Thank you, Krzysztof Kozlowski, Andrew F. Davis, PrasannaKumar
Muralidharan, Rob Herring.

v1 can be found:

https://www.spinics.net/lists/linux-samsung-soc/msg61253.html
https://patchwork.kernel.org/patch/10072967/
https://patchwork.kernel.org/patch/10072971/
https://patchwork.kernel.org/patch/10072963/

Łukasz Stelmach (3):
  dt-bindings: hwrng: Add Samsung Exynos 5250+ True RNG bindings
  hwrng: exynos - add Samsung Exynos True RNG driver
  ARM: dts: exynos: Add nodes for True Random Number Generator

 .../bindings/rng/samsung,exynos5250-trng.txt       |  17 ++
 MAINTAINERS                                        |   7 +
 arch/arm/boot/dts/exynos5.dtsi                     |   5 +
 arch/arm/boot/dts/exynos5250.dtsi                  |   5 +
 arch/arm/boot/dts/exynos5410.dtsi                  |   5 +
 arch/arm/boot/dts/exynos5420.dtsi                  |   5 +
 drivers/char/hw_random/Kconfig                     |  12 +
 drivers/char/hw_random/Makefile                    |   1 +
 drivers/char/hw_random/exynos-trng.c               | 245 +++++++++++++++++++++
 9 files changed, 302 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt
 create mode 100644 drivers/char/hw_random/exynos-trng.c

-- 
2.11.0

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[PATCH v2 1/3] dt-bindings: hwrng: Add Samsung Exynos 5250+ True RNG bindings

[Łukasz Stelmach]

Add binding documentation for the True Random Number Generator
found on Samsung Exynos 5250+ SoCs.

Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Reviewed-by: Krzysztof Kozlowski <krzk-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Signed-off-by: Łukasz Stelmach <l.stelmach-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
---
 .../devicetree/bindings/rng/samsung,exynos5250-trng.txt | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt

diff --git a/Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt b/Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt
new file mode 100644
index 000000000000..22dfe8cb21c0
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt
@@ -0,0 +1,17 @@
+Exynos True Random Number Generator
+
+Required properties:
+
+- compatible  : Should be "samsung,exynos5250-trng".
+- reg         : Specifies base physical address and size of the registers map.
+- clocks      : Phandle to clock-controller plus clock-specifier pair.
+- clock-names : "secss" as a clock name.
+
+Example:
+
+	trng@10830600 {
+		compatible = "samsung,exynos5250-trng";
+		reg = <0x10830600 0x100>;
+		clocks = <&clock CLK_SSS>;
+		clock-names = "secss";
+	};
-- 
2.11.0

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Re: [PATCH v2 1/3] dt-bindings: hwrng: Add Samsung Exynos 5250+ True RNG bindings

[Krzysztof Kozlowski]

On Mon, Nov 27, 2017 at 10:58 AM, Łukasz Stelmach
<l.stelmach@samsung.com> wrote:
> Add binding documentation for the True Random Number Generator
> found on Samsung Exynos 5250+ SoCs.
>
> Acked-by: Rob Herring <robh@kernel.org>
> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
> Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>

A minor nit: add new tags after your Signed-off-by, in same order you
received them.

Best regards,
Krzysztof

[PATCH v2 2/3] hwrng: exynos - add Samsung Exynos True RNG driver

[Łukasz Stelmach]

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

Re: [PATCH v2 2/3] hwrng: exynos - add Samsung Exynos True RNG driver

[Krzysztof Kozlowski]

On Mon, Nov 27, 2017 at 10:58 AM, Łukasz Stelmach
<l.stelmach@samsung.com> wrote:
> 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)

Add a EXYNOS prefix and please put it after the register where it is
used (CTRL).

> +
> +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;

Just return PTR_ERR(trng->mem)? Less lines and goto labels.

Best regards,
Krzysztof

Re: [PATCH v2 2/3] hwrng: exynos - add Samsung Exynos True RNG driver

[PrasannaKumar Muralidharan]

Hi Lukasz,

On 27 November 2017 at 15:28, Łukasz Stelmach <l.stelmach@samsung.com> wrote:
> 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
>

Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>

Regards,
PrasannaKumar

[PATCH v2 3/3] ARM: dts: exynos: Add nodes for True Random Number Generator

[Łukasz Stelmach]

Add nodes for the True Random Number Generator found in Samsung Exynos
5250+ SoCs.

Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
---
 arch/arm/boot/dts/exynos5.dtsi    | 5 +++++
 arch/arm/boot/dts/exynos5250.dtsi | 5 +++++
 arch/arm/boot/dts/exynos5410.dtsi | 5 +++++
 arch/arm/boot/dts/exynos5420.dtsi | 5 +++++
 4 files changed, 20 insertions(+)

diff --git a/arch/arm/boot/dts/exynos5.dtsi b/arch/arm/boot/dts/exynos5.dtsi
index 7da4a4285b24..6a298b536e1c 100644
--- a/arch/arm/boot/dts/exynos5.dtsi
+++ b/arch/arm/boot/dts/exynos5.dtsi
@@ -210,5 +210,10 @@
 			reg = <0x10830000 0x300>;
 			interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
 		};
+
+		trng: trng@10830600 {
+		      compatible = "samsung,exynos5250-trng";
+		      reg = <0x10830600 0x100>;
+		};
 	};
 };
diff --git a/arch/arm/boot/dts/exynos5250.dtsi b/arch/arm/boot/dts/exynos5250.dtsi
index 8032d7e567fc..332fe04b772b 100644
--- a/arch/arm/boot/dts/exynos5250.dtsi
+++ b/arch/arm/boot/dts/exynos5250.dtsi
@@ -1081,4 +1081,9 @@
 	clock-names = "secss";
 };
 
+&trng {
+	clocks = <&clock CLK_SSS>;
+	clock-names = "secss";
+};
+
 #include "exynos5250-pinctrl.dtsi"
diff --git a/arch/arm/boot/dts/exynos5410.dtsi b/arch/arm/boot/dts/exynos5410.dtsi
index 7eab4bc07cec..f3991206a562 100644
--- a/arch/arm/boot/dts/exynos5410.dtsi
+++ b/arch/arm/boot/dts/exynos5410.dtsi
@@ -379,6 +379,11 @@
 		  3 0 0x07000000 0x20000>;
 };
 
+&trng {
+	clocks = <&clock CLK_SSS>;
+	clock-names = "secss";
+};
+
 &usbdrd3_0 {
 	clocks = <&clock CLK_USBD300>;
 	clock-names = "usbdrd30";
diff --git a/arch/arm/boot/dts/exynos5420.dtsi b/arch/arm/boot/dts/exynos5420.dtsi
index 02d2f898efa6..2f4e5542f354 100644
--- a/arch/arm/boot/dts/exynos5420.dtsi
+++ b/arch/arm/boot/dts/exynos5420.dtsi
@@ -1454,6 +1454,11 @@
 	clock-names = "secss";
 };
 
+&trng {
+	clocks = <&clock CLK_SSS>;
+	clock-names = "secss";
+};
+
 &usbdrd3_0 {
 	clocks = <&clock CLK_USBD300>;
 	clock-names = "usbdrd30";
-- 
2.11.0