[PATCH v2 0/4] hw_random: Add driver for Ingenic JZ4780 SoC RNG

[PATCH v2 0/4] hw_random: Add driver for Ingenic JZ4780 SoC RNG

[PrasannaKumar Muralidharan]

This is the v2 patch series that adds support for random number generator
present in Ingenic JZ4780 SoC.

Patch 1: Add device tree bindings for RNG in JZ4780 SoC.
Patch 2: Add Ingenic JZ4780 hardware RNG driver.
Patch 3: Add RNG to jz4780.dtsi.
Patch 4: Enable RNG in ci20_defconfig

PrasannaKumar Muralidharan (4):
  hw_random: jz4780-rng: Add devicetree bindings for RNG in JZ4780 SoC
  hw_random: jz4780-rng: Add Ingenic JZ4780 hardware RNG driver
  hw_random: jz4780-rng: Add RNG node to jz4780.dtsi
  hw_random: jz4780-rng: Enable hardware RNG in CI20 defconfig

 Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt |   12 +
 MAINTAINERS                                                  |    5 
 arch/mips/boot/dts/ingenic/jz4780.dtsi                       |    7 
 arch/mips/configs/ci20_defconfig                             |    4 
 drivers/char/hw_random/Kconfig                               |   14 +
 drivers/char/hw_random/Makefile                              |    1 
 drivers/char/hw_random/jz4780-rng.c                          |  102 +++++++++++
 7 files changed, 143 insertions(+), 2 deletions(-)

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[PATCH v2 1/4] hw_random: jz4780-rng: Add devicetree bindings for RNG in JZ4780 SoC

[PrasannaKumar Muralidharan]

Add devicetree bindings for hardware random number generator present in
Ingenic JZ4780 SoC.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt

diff --git a/Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt b/Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt
new file mode 100644
index 0000000..03abf56
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt
@@ -0,0 +1,12 @@
+Ingenic jz4780 RNG driver
+
+Required properties:
+- compatible : Should be "ingenic,jz4780-rng"
+- reg : Specifies base physical address and size of the registers.
+
+Example:
+
+rng: rng@100000D8 {
+	compatible = "ingenic,jz4780-rng";
+	reg = <0x100000D8 0x8>;
+};
-- 
2.5.0

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[PATCH v2 2/4] hw_random: jz4780-rng: Add Ingenic JZ4780 hardware RNG driver

[PrasannaKumar Muralidharan]

JZ4780 SoC random number generator driver.

Changes since v1:
* Use devm_ioremap_resource and devm_hwrng_register
* Add delay after enabling RNG, before reading data
* Disable RNG after reading data as per Ingenic JZ4780 PM
* Move Makefile and Kconfig entries to the bottom
* Arrange includes in alphabetical order

Adding a delay before reading RNG data and disabling RNG after reading
data was suggested by Jeffery Walton.

Suggested-by: Jeffrey Walton <noloader@gmail.com>
Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
---
 MAINTAINERS                         |   5 ++
 drivers/char/hw_random/Kconfig      |  14 +++++
 drivers/char/hw_random/Makefile     |   1 +
 drivers/char/hw_random/jz4780-rng.c | 101 ++++++++++++++++++++++++++++++++++++
 4 files changed, 121 insertions(+)
 create mode 100644 drivers/char/hw_random/jz4780-rng.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 320cce8..87a7505 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6008,6 +6008,11 @@ M:	Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
 S:	Maintained
 F:	drivers/dma/dma-jz4780.c
 
+INGENIC JZ4780 HW RNG Driver
+M:	PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
+S:	Maintained
+F:	drivers/char/hw_random/jz4780-rng.c
+
 INTEGRITY MEASUREMENT ARCHITECTURE (IMA)
 M:	Mimi Zohar <zohar@linux.vnet.ibm.com>
 M:	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 56ad5a59..662e415 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -410,6 +410,20 @@ config HW_RANDOM_MESON
 
 	  If unsure, say Y.
 
+config HW_RANDOM_JZ4780
+	tristate "JZ4780 HW random number generator support"
+	depends on MACH_INGENIC
+	depends on HAS_IOMEM
+	default HW_RANDOM
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on JZ4780 SOCs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called jz4780-rng.
+
+	  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 04bb0b0..df1dbf6 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -35,3 +35,4 @@ obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
 obj-$(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_JZ4780) += jz4780-rng.o
diff --git a/drivers/char/hw_random/jz4780-rng.c b/drivers/char/hw_random/jz4780-rng.c
new file mode 100644
index 0000000..1c85ed0
--- /dev/null
+++ b/drivers/char/hw_random/jz4780-rng.c
@@ -0,0 +1,101 @@
+/*
+ * jz4780-rng.c - Random Number Generator driver for J4780
+ *
+ * Copyright 2016 (C) PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define REG_RNG_CTRL	0x0
+#define REG_RNG_DATA	0x4
+
+struct jz4780_rng {
+	struct device *dev;
+	struct hwrng rng;
+	void __iomem *mem;
+};
+
+static u32 jz4780_rng_readl(struct jz4780_rng *rng, u32 offset)
+{
+	return readl(rng->mem + offset);
+}
+
+static void jz4780_rng_writel(struct jz4780_rng *rng, u32 val, u32 offset)
+{
+	writel(val, rng->mem + offset);
+}
+
+static int jz4780_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	struct jz4780_rng *jz4780_rng = container_of(rng, struct jz4780_rng,
+							rng);
+	u32 *data = buf;
+	/*
+	 * JZ4780 Programmers manual says the RNG should not run continuously
+	 * for more than 1s. So enable RNG, read data and disable it.
+	 * NOTE: No issue was observed with MIPS creator CI20 board even when
+	 * RNG ran continuously for longer periods. This is just a precaution.
+	 *
+	 * A delay is required so that the current RNG data is not bit shifted
+	 * version of previous RNG data which could happen if random data is
+	 * read continuously from this device.
+	 */
+	jz4780_rng_writel(jz4780_rng, 1, REG_RNG_CTRL);
+	/* As the delay is small add it even if wait is false */
+	udelay(20);
+	*data = jz4780_rng_readl(jz4780_rng, REG_RNG_DATA);
+	jz4780_rng_writel(jz4780_rng, 0, REG_RNG_CTRL);
+
+	return 4;
+}
+
+static int jz4780_rng_probe(struct platform_device *pdev)
+{
+	struct jz4780_rng *jz4780_rng;
+	struct resource *res;
+
+	jz4780_rng = devm_kzalloc(&pdev->dev, sizeof(*jz4780_rng), GFP_KERNEL);
+	if (!jz4780_rng)
+		return -ENOMEM;
+
+	jz4780_rng->dev = &pdev->dev;
+	jz4780_rng->rng.name = "jz4780";
+	jz4780_rng->rng.read = jz4780_rng_read;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	jz4780_rng->mem = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(jz4780_rng->mem))
+		return PTR_ERR(jz4780_rng->mem);
+
+	return devm_hwrng_register(&pdev->dev, &jz4780_rng->rng);
+}
+
+static const struct of_device_id jz4780_rng_dt_match[] = {
+	{ .compatible = "ingenic,jz4780-rng", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, jz4780_rng_dt_match);
+
+static struct platform_driver jz4780_rng_driver = {
+	.driver		= {
+		.name	= "jz4780-rng",
+		.of_match_table = jz4780_rng_dt_match,
+	},
+	.probe		= jz4780_rng_probe,
+};
+module_platform_driver(jz4780_rng_driver);
+
+MODULE_DESCRIPTION("Ingenic JZ4780 H/W Random Number Generator driver");
+MODULE_AUTHOR("PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>");
+MODULE_LICENSE("GPL");
-- 
2.5.0

[PATCH v2 3/4] hw_random: jz4780-rng: Add RNG node to jz4780.dtsi

[PrasannaKumar Muralidharan]

This patch adds RNG node to jz4780.dtsi.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
---
 arch/mips/boot/dts/ingenic/jz4780.dtsi | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/mips/boot/dts/ingenic/jz4780.dtsi b/arch/mips/boot/dts/ingenic/jz4780.dtsi
index b868b42..f11d139 100644
--- a/arch/mips/boot/dts/ingenic/jz4780.dtsi
+++ b/arch/mips/boot/dts/ingenic/jz4780.dtsi
@@ -36,7 +36,7 @@
 
 	cgu: jz4780-cgu@10000000 {
 		compatible = "ingenic,jz4780-cgu";
-		reg = <0x10000000 0x100>;
+		reg = <0x10000000 0xD8>;
 
 		clocks = <&ext>, <&rtc>;
 		clock-names = "ext", "rtc";
@@ -44,6 +44,11 @@
 		#clock-cells = <1>;
 	};
 
+	rng: jz4780-rng@100000D8 {
+		compatible = "ingenic,jz4780-rng";
+		reg = <0x100000D8 0x8>;
+	};
+
 	uart0: serial@10030000 {
 		compatible = "ingenic,jz4780-uart";
 		reg = <0x10030000 0x100>;
-- 
2.5.0

[PATCH v2 4/4] hw_random: jz4780-rng: Enable hardware RNG in CI20 defconfig

[PrasannaKumar Muralidharan]

This patch enables the usage of RNG in MIPS Creator CI20 default config.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 arch/mips/configs/ci20_defconfig | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/mips/configs/ci20_defconfig b/arch/mips/configs/ci20_defconfig
index bf164fe..51a47a4 100644
--- a/arch/mips/configs/ci20_defconfig
+++ b/arch/mips/configs/ci20_defconfig
@@ -88,7 +88,9 @@ CONFIG_SERIAL_8250_NR_UARTS=5
 CONFIG_SERIAL_8250_RUNTIME_UARTS=5
 CONFIG_SERIAL_8250_INGENIC=y
 CONFIG_SERIAL_OF_PLATFORM=y
-# CONFIG_HW_RANDOM is not set
+CONFIG_HW_RANDOM=y
+# CONFIG_HW_RANDOM_TIMERIOMEM is not set
+CONFIG_HW_RANDOM_JZ4780=y
 CONFIG_I2C=y
 CONFIG_I2C_JZ4780=y
 CONFIG_GPIO_SYSFS=y
-- 
2.5.0

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Re: [PATCH v2 3/4] hw_random: jz4780-rng: Add RNG node to jz4780.dtsi

[Sergei Shtylyov]

Hello.

On 8/27/2016 9:14 PM, PrasannaKumar Muralidharan wrote:

> This patch adds RNG node to jz4780.dtsi.
>
> Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  arch/mips/boot/dts/ingenic/jz4780.dtsi | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/mips/boot/dts/ingenic/jz4780.dtsi b/arch/mips/boot/dts/ingenic/jz4780.dtsi
> index b868b42..f11d139 100644
> --- a/arch/mips/boot/dts/ingenic/jz4780.dtsi
> +++ b/arch/mips/boot/dts/ingenic/jz4780.dtsi
> @@ -36,7 +36,7 @@
>
>  	cgu: jz4780-cgu@10000000 {
>  		compatible = "ingenic,jz4780-cgu";
> -		reg = <0x10000000 0x100>;
> +		reg = <0x10000000 0xD8>;

    I think lower case is preferred here.

>
>  		clocks = <&ext>, <&rtc>;
>  		clock-names = "ext", "rtc";
> @@ -44,6 +44,11 @@
>  		#clock-cells = <1>;
>  	};
>
> +	rng: jz4780-rng@100000D8 {

    All in lower case, please.

> +		compatible = "ingenic,jz4780-rng";
> +		reg = <0x100000D8 0x8>;

    Likewise.

[...]

MBR, Sergei

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Re: [PATCH v2 3/4] hw_random: jz4780-rng: Add RNG node to jz4780.dtsi

[PrasannaKumar Muralidharan]

>>         cgu: jz4780-cgu@10000000 {
>>                 compatible = "ingenic,jz4780-cgu";
>> -               reg = <0x10000000 0x100>;
>> +               reg = <0x10000000 0xD8>;
>
>
>    I think lower case is preferred here.

Sure, will change.

Re: [PATCH v2 3/4] hw_random: jz4780-rng: Add RNG node to jz4780.dtsi

[Paul Burton]

On 27/08/16 19:14, PrasannaKumar Muralidharan wrote:
> This patch adds RNG node to jz4780.dtsi.
> 
> Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
> ---
>  arch/mips/boot/dts/ingenic/jz4780.dtsi | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/mips/boot/dts/ingenic/jz4780.dtsi b/arch/mips/boot/dts/ingenic/jz4780.dtsi
> index b868b42..f11d139 100644
> --- a/arch/mips/boot/dts/ingenic/jz4780.dtsi
> +++ b/arch/mips/boot/dts/ingenic/jz4780.dtsi
> @@ -36,7 +36,7 @@
>  
>  	cgu: jz4780-cgu@10000000 {
>  		compatible = "ingenic,jz4780-cgu";
> -		reg = <0x10000000 0x100>;
> +		reg = <0x10000000 0xD8>;

Hi PrasannaKumar,

I don't like this change. The RNG registers are documented as a part of
the same hardware block as the clock & power stuff which the CGU driver
handles, and indeed in the M200 SoC there is a power-related register
after the RNG registers. So shortening the range covered by the CGU
driver is not the right way to go.

Perhaps you could instead have the CGU driver make use of the syscon
infrastructure to expose a regmap which your RNG driver could pick up & use?

Thanks,
    Paul

>  
>  		clocks = <&ext>, <&rtc>;
>  		clock-names = "ext", "rtc";
> @@ -44,6 +44,11 @@
>  		#clock-cells = <1>;
>  	};
>  
> +	rng: jz4780-rng@100000D8 {
> +		compatible = "ingenic,jz4780-rng";
> +		reg = <0x100000D8 0x8>;
> +	};
> +
>  	uart0: serial@10030000 {
>  		compatible = "ingenic,jz4780-uart";
>  		reg = <0x10030000 0x100>;
> 

Re: [PATCH v2 3/4] hw_random: jz4780-rng: Add RNG node to jz4780.dtsi

[PrasannaKumar Muralidharan]

> I don't like this change. The RNG registers are documented as a part of
> the same hardware block as the clock & power stuff which the CGU driver
> handles, and indeed in the M200 SoC there is a power-related register
> after the RNG registers. So shortening the range covered by the CGU
> driver is not the right way to go.

Could not find M200 SoC PM in ingenic's website or ftp. So did not notice this.

> Perhaps you could instead have the CGU driver make use of the syscon
> infrastructure to expose a regmap which your RNG driver could pick up & use?

I will see how to use syscon and provide an updated patch.
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