[PATCH 1/2] dt/bindings: Add bindings for the PIC32 random number generator

[PATCH 1/2] dt/bindings: Add bindings for the PIC32 random number generator

[Joshua Henderson]

Document the devicetree bindings for the random number generator found
on Microchip PIC32 class devices.

Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
---
 .../bindings/rng/microchip,pic32-rng.txt           |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt

diff --git a/Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt b/Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt
new file mode 100644
index 0000000..c6d1003
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt
@@ -0,0 +1,17 @@
+* Microchip PIC32 Random Number Generator
+
+The PIC32 RNG provides a pseudo random number generator which can be seeded by
+another true random number generator.
+
+Required properties:
+- compatible : should be "microchip,pic32mzda-rng"
+- reg : Specifies base physical address and size of the registers.
+- clocks: clock phandle.
+
+Example:
+
+	rng: rng@1f8e6000 {
+		compatible = "microchip,pic32mzda-rng";
+		reg = <0x1f8e6000 0x1000>;
+		clocks = <&PBCLK5>;
+	};
-- 
1.7.9.5

[PATCH 1/2] dt/bindings: Add bindings for the PIC32 random number generator

[Joshua Henderson]

Document the devicetree bindings for the random number generator found
on Microchip PIC32 class devices.

Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
---
 .../bindings/rng/microchip,pic32-rng.txt           |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt

diff --git a/Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt b/Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt
new file mode 100644
index 0000000..c6d1003
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt
@@ -0,0 +1,17 @@
+* Microchip PIC32 Random Number Generator
+
+The PIC32 RNG provides a pseudo random number generator which can be seeded by
+another true random number generator.
+
+Required properties:
+- compatible : should be "microchip,pic32mzda-rng"
+- reg : Specifies base physical address and size of the registers.
+- clocks: clock phandle.
+
+Example:
+
+	rng: rng@1f8e6000 {
+		compatible = "microchip,pic32mzda-rng";
+		reg = <0x1f8e6000 0x1000>;
+		clocks = <&PBCLK5>;
+	};
-- 
1.7.9.5

[PATCH 2/2] rng: pic32-rng: Add PIC32 RNG hardware driver

[Joshua Henderson]

Add support for the hardware pseudo and true random number generator
peripheral found on PIC32.

Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
---
 drivers/char/hw_random/Kconfig     |   13 +++
 drivers/char/hw_random/Makefile    |    1 +
 drivers/char/hw_random/pic32-rng.c |  152 ++++++++++++++++++++++++++++++++++++
 3 files changed, 166 insertions(+)
 create mode 100644 drivers/char/hw_random/pic32-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index dbf2271..3ab0c46 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -381,6 +381,19 @@ config HW_RANDOM_STM32
 
 	  If unsure, say N.
 
+config HW_RANDOM_PIC32
+	tristate "Microchip PIC32 Random Number Generator support"
+	depends on HW_RANDOM && MACH_PIC32
+	default y
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on a PIC32.
+
+	  To compile this driver as a module, choose M here. the
+	  module will be called pic32-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 5ad3976..f5a6fa7 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -33,3 +33,4 @@ obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
 obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
 obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
 obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
+obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
diff --git a/drivers/char/hw_random/pic32-rng.c b/drivers/char/hw_random/pic32-rng.c
new file mode 100644
index 0000000..d2f32c4
--- /dev/null
+++ b/drivers/char/hw_random/pic32-rng.c
@@ -0,0 +1,152 @@
+/*
+ * PIC32 RNG driver
+ *
+ * Joshua Henderson <joshua.henderson@microchip.com>
+ * Copyright (C) 2016 Microchip Technology Inc.  All rights reserved.
+ *
+ * This program is free software; you can distribute it and/or modify it
+ * under the terms of the GNU General Public License (Version 2) as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/hw_random.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+
+#define RNGCON		0x04
+#define  TRNGEN		BIT(8)
+#define  PRNGEN		BIT(9)
+#define  PRNGCONT	BIT(10)
+#define  TRNGMOD	BIT(11)
+#define  SEEDLOAD	BIT(12)
+#define RNGPOLY1	0x08
+#define RNGPOLY2	0x0C
+#define RNGNUMGEN1	0x10
+#define RNGNUMGEN2	0x14
+#define RNGSEED1	0x18
+#define RNGSEED2	0x1C
+#define RNGRCNT		0x20
+#define  RCNT_MASK	0x7F
+
+struct pic32_rng {
+	void __iomem	*base;
+	struct hwrng	rng;
+	struct clk	*clk;
+};
+
+static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
+			  bool wait)
+{
+	struct pic32_rng *prng = container_of(rng, struct pic32_rng, rng);
+	u64 *data = buf;
+
+	*data = ((u64)readl(prng->base + RNGNUMGEN2) << 32) +
+		readl(prng->base + RNGNUMGEN1);
+	return 4;
+}
+
+static int pic32_rng_probe(struct platform_device *pdev)
+{
+	struct pic32_rng *prng;
+	struct resource *res;
+	u32 v, t;
+	int ret;
+
+	prng = devm_kzalloc(&pdev->dev, sizeof(*prng), GFP_KERNEL);
+	if (!prng)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	prng->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(prng->base))
+		return PTR_ERR(prng->base);
+
+	prng->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(prng->clk))
+		return PTR_ERR(prng->clk);
+
+	clk_prepare_enable(prng->clk);
+
+	/* enable TRNG in enhanced mode */
+	v = readl(prng->base + RNGCON);
+	v &= ~(TRNGEN | PRNGEN | 0xff);
+	v |= TRNGMOD;
+	writel(v | TRNGEN, prng->base + RNGCON);
+
+	/* wait for valid seed */
+	usleep_range(100, 200);
+	t = readl(prng->base + RNGRCNT) & RCNT_MASK;
+	if (t < 0x2A)
+		dev_warn(&pdev->dev, "seed not generated.\n");
+
+	/* load initial seed */
+	writel(v | SEEDLOAD, prng->base + RNGCON);
+
+	/* load initial polynomial: 42bit poly */
+	writel(0x00c00003, prng->base + RNGPOLY1);
+	writel(0x00000000, prng->base + RNGPOLY2);
+
+	/* start PRNG to generate 42bit random */
+	v |= 0x2A | PRNGCONT | PRNGEN;
+	writel(v, prng->base + RNGCON);
+
+	prng->rng.name = pdev->name;
+	prng->rng.read = pic32_rng_read;
+
+	ret = hwrng_register(&prng->rng);
+	if (ret)
+		goto err_register;
+
+	platform_set_drvdata(pdev, prng);
+
+	return 0;
+
+err_register:
+	return ret;
+}
+
+static int pic32_rng_remove(struct platform_device *pdev)
+{
+	struct pic32_rng *rng = platform_get_drvdata(pdev);
+
+	hwrng_unregister(&rng->rng);
+	writel(0, rng->base + RNGCON);
+	clk_disable_unprepare(rng->clk);
+	return 0;
+}
+
+static const struct of_device_id pic32_rng_of_match[] = {
+	{ .compatible	= "microchip,pic32mzda-rng", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
+
+static struct platform_driver pic32_rng_driver = {
+	.probe		= pic32_rng_probe,
+	.remove		= pic32_rng_remove,
+	.driver		= {
+		.name	= "pic32-rng",
+		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(pic32_rng_of_match),
+	},
+};
+
+module_platform_driver(pic32_rng_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
+MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");
-- 
1.7.9.5

[PATCH 2/2] rng: pic32-rng: Add PIC32 RNG hardware driver

[Joshua Henderson]

Add support for the hardware pseudo and true random number generator
peripheral found on PIC32.

Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
---
 drivers/char/hw_random/Kconfig     |   13 +++
 drivers/char/hw_random/Makefile    |    1 +
 drivers/char/hw_random/pic32-rng.c |  152 ++++++++++++++++++++++++++++++++++++
 3 files changed, 166 insertions(+)
 create mode 100644 drivers/char/hw_random/pic32-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index dbf2271..3ab0c46 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -381,6 +381,19 @@ config HW_RANDOM_STM32
 
 	  If unsure, say N.
 
+config HW_RANDOM_PIC32
+	tristate "Microchip PIC32 Random Number Generator support"
+	depends on HW_RANDOM && MACH_PIC32
+	default y
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on a PIC32.
+
+	  To compile this driver as a module, choose M here. the
+	  module will be called pic32-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 5ad3976..f5a6fa7 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -33,3 +33,4 @@ obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
 obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
 obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
 obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
+obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
diff --git a/drivers/char/hw_random/pic32-rng.c b/drivers/char/hw_random/pic32-rng.c
new file mode 100644
index 0000000..d2f32c4
--- /dev/null
+++ b/drivers/char/hw_random/pic32-rng.c
@@ -0,0 +1,152 @@
+/*
+ * PIC32 RNG driver
+ *
+ * Joshua Henderson <joshua.henderson@microchip.com>
+ * Copyright (C) 2016 Microchip Technology Inc.  All rights reserved.
+ *
+ * This program is free software; you can distribute it and/or modify it
+ * under the terms of the GNU General Public License (Version 2) as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/hw_random.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+
+#define RNGCON		0x04
+#define  TRNGEN		BIT(8)
+#define  PRNGEN		BIT(9)
+#define  PRNGCONT	BIT(10)
+#define  TRNGMOD	BIT(11)
+#define  SEEDLOAD	BIT(12)
+#define RNGPOLY1	0x08
+#define RNGPOLY2	0x0C
+#define RNGNUMGEN1	0x10
+#define RNGNUMGEN2	0x14
+#define RNGSEED1	0x18
+#define RNGSEED2	0x1C
+#define RNGRCNT		0x20
+#define  RCNT_MASK	0x7F
+
+struct pic32_rng {
+	void __iomem	*base;
+	struct hwrng	rng;
+	struct clk	*clk;
+};
+
+static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
+			  bool wait)
+{
+	struct pic32_rng *prng = container_of(rng, struct pic32_rng, rng);
+	u64 *data = buf;
+
+	*data = ((u64)readl(prng->base + RNGNUMGEN2) << 32) +
+		readl(prng->base + RNGNUMGEN1);
+	return 4;
+}
+
+static int pic32_rng_probe(struct platform_device *pdev)
+{
+	struct pic32_rng *prng;
+	struct resource *res;
+	u32 v, t;
+	int ret;
+
+	prng = devm_kzalloc(&pdev->dev, sizeof(*prng), GFP_KERNEL);
+	if (!prng)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	prng->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(prng->base))
+		return PTR_ERR(prng->base);
+
+	prng->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(prng->clk))
+		return PTR_ERR(prng->clk);
+
+	clk_prepare_enable(prng->clk);
+
+	/* enable TRNG in enhanced mode */
+	v = readl(prng->base + RNGCON);
+	v &= ~(TRNGEN | PRNGEN | 0xff);
+	v |= TRNGMOD;
+	writel(v | TRNGEN, prng->base + RNGCON);
+
+	/* wait for valid seed */
+	usleep_range(100, 200);
+	t = readl(prng->base + RNGRCNT) & RCNT_MASK;
+	if (t < 0x2A)
+		dev_warn(&pdev->dev, "seed not generated.\n");
+
+	/* load initial seed */
+	writel(v | SEEDLOAD, prng->base + RNGCON);
+
+	/* load initial polynomial: 42bit poly */
+	writel(0x00c00003, prng->base + RNGPOLY1);
+	writel(0x00000000, prng->base + RNGPOLY2);
+
+	/* start PRNG to generate 42bit random */
+	v |= 0x2A | PRNGCONT | PRNGEN;
+	writel(v, prng->base + RNGCON);
+
+	prng->rng.name = pdev->name;
+	prng->rng.read = pic32_rng_read;
+
+	ret = hwrng_register(&prng->rng);
+	if (ret)
+		goto err_register;
+
+	platform_set_drvdata(pdev, prng);
+
+	return 0;
+
+err_register:
+	return ret;
+}
+
+static int pic32_rng_remove(struct platform_device *pdev)
+{
+	struct pic32_rng *rng = platform_get_drvdata(pdev);
+
+	hwrng_unregister(&rng->rng);
+	writel(0, rng->base + RNGCON);
+	clk_disable_unprepare(rng->clk);
+	return 0;
+}
+
+static const struct of_device_id pic32_rng_of_match[] = {
+	{ .compatible	= "microchip,pic32mzda-rng", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
+
+static struct platform_driver pic32_rng_driver = {
+	.probe		= pic32_rng_probe,
+	.remove		= pic32_rng_remove,
+	.driver		= {
+		.name	= "pic32-rng",
+		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(pic32_rng_of_match),
+	},
+};
+
+module_platform_driver(pic32_rng_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
+MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");
-- 
1.7.9.5

Re: [PATCH 2/2] rng: pic32-rng: Add PIC32 RNG hardware driver

[Daniel Thompson]

On 01/02/16 22:41, Joshua Henderson wrote:
> Add support for the hardware pseudo and true random number generator
> peripheral found on PIC32.
>
> Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
> Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
> ---
>   drivers/char/hw_random/Kconfig     |   13 +++
>   drivers/char/hw_random/Makefile    |    1 +
>   drivers/char/hw_random/pic32-rng.c |  152 ++++++++++++++++++++++++++++++++++++
>   3 files changed, 166 insertions(+)
>   create mode 100644 drivers/char/hw_random/pic32-rng.c
>
> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> index dbf2271..3ab0c46 100644
> --- a/drivers/char/hw_random/Kconfig
> +++ b/drivers/char/hw_random/Kconfig
> @@ -381,6 +381,19 @@ config HW_RANDOM_STM32
>
>   	  If unsure, say N.
>
> +config HW_RANDOM_PIC32
> +	tristate "Microchip PIC32 Random Number Generator support"
> +	depends on HW_RANDOM && MACH_PIC32
> +	default y
> +	---help---
> +	  This driver provides kernel-side support for the Random Number
> +	  Generator hardware found on a PIC32.
> +
> +	  To compile this driver as a module, choose M here. the
> +	  module will be called pic32-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 5ad3976..f5a6fa7 100644
> --- a/drivers/char/hw_random/Makefile
> +++ b/drivers/char/hw_random/Makefile
> @@ -33,3 +33,4 @@ obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
>   obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
>   obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
>   obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
> +obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
> diff --git a/drivers/char/hw_random/pic32-rng.c b/drivers/char/hw_random/pic32-rng.c
> new file mode 100644
> index 0000000..d2f32c4
> --- /dev/null
> +++ b/drivers/char/hw_random/pic32-rng.c
> @@ -0,0 +1,152 @@
> +/*
> + * PIC32 RNG driver
> + *
> + * Joshua Henderson <joshua.henderson@microchip.com>
> + * Copyright (C) 2016 Microchip Technology Inc.  All rights reserved.
> + *
> + * This program is free software; you can distribute it and/or modify it
> + * under the terms of the GNU General Public License (Version 2) as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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/kernel.h>
> +#include <linux/module.h>
> +#include <linux/delay.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/hw_random.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/clk.h>
> +#include <linux/clkdev.h>
> +
> +#define RNGCON		0x04
> +#define  TRNGEN		BIT(8)
> +#define  PRNGEN		BIT(9)
> +#define  PRNGCONT	BIT(10)
> +#define  TRNGMOD	BIT(11)
> +#define  SEEDLOAD	BIT(12)
> +#define RNGPOLY1	0x08
> +#define RNGPOLY2	0x0C
> +#define RNGNUMGEN1	0x10
> +#define RNGNUMGEN2	0x14
> +#define RNGSEED1	0x18
> +#define RNGSEED2	0x1C
> +#define RNGRCNT		0x20
> +#define  RCNT_MASK	0x7F
> +
> +struct pic32_rng {
> +	void __iomem	*base;
> +	struct hwrng	rng;
> +	struct clk	*clk;
> +};
> +
> +static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
> +			  bool wait)
> +{
> +	struct pic32_rng *prng = container_of(rng, struct pic32_rng, rng);
> +	u64 *data = buf;
> +
> +	*data = ((u64)readl(prng->base + RNGNUMGEN2) << 32) +
> +		readl(prng->base + RNGNUMGEN1);
> +	return 4;
> +}

I have a number of questions at this point (although #3 is by far the 
most important).

1. If the random number of 42-bit shouldn't this be return 5; ?

2. If you really do mean return 4; then why mess about with all the
    shifting. You can just read and discard the upper 32-bits.

3. Why are you using the PRNG at all? The PRNG is a simple LSFR and
    I don't think it ever gets reseeded at any point (meaning we get
    almost no useful entropy from it at all).

    Far better to read directly from the TRNG.


> +
> +static int pic32_rng_probe(struct platform_device *pdev)
> +{
> +	struct pic32_rng *prng;
> +	struct resource *res;
> +	u32 v, t;
> +	int ret;
> +
> +	prng = devm_kzalloc(&pdev->dev, sizeof(*prng), GFP_KERNEL);
> +	if (!prng)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	prng->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(prng->base))
> +		return PTR_ERR(prng->base);
> +
> +	prng->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(prng->clk))
> +		return PTR_ERR(prng->clk);
> +
> +	clk_prepare_enable(prng->clk);
> +
> +	/* enable TRNG in enhanced mode */
> +	v = readl(prng->base + RNGCON);
> +	v &= ~(TRNGEN | PRNGEN | 0xff);
> +	v |= TRNGMOD;
> +	writel(v | TRNGEN, prng->base + RNGCON);
> +
> +	/* wait for valid seed */
> +	usleep_range(100, 200);
> +	t = readl(prng->base + RNGRCNT) & RCNT_MASK;
> +	if (t < 0x2A)
> +		dev_warn(&pdev->dev, "seed not generated.\n");
> +
> +	/* load initial seed */
> +	writel(v | SEEDLOAD, prng->base + RNGCON);
> +
> +	/* load initial polynomial: 42bit poly */
> +	writel(0x00c00003, prng->base + RNGPOLY1);
> +	writel(0x00000000, prng->base + RNGPOLY2);
> +
> +	/* start PRNG to generate 42bit random */
> +	v |= 0x2A | PRNGCONT | PRNGEN;
> +	writel(v, prng->base + RNGCON);
> +
> +	prng->rng.name = pdev->name;
> +	prng->rng.read = pic32_rng_read;
> +
> +	ret = hwrng_register(&prng->rng);
> +	if (ret)
> +		goto err_register;
> +
> +	platform_set_drvdata(pdev, prng);
> +
> +	return 0;
> +
> +err_register:
> +	return ret;

Looks like we leak clock references on this error path.


> +
> +static int pic32_rng_remove(struct platform_device *pdev)
> +{
> +	struct pic32_rng *rng = platform_get_drvdata(pdev);
> +
> +	hwrng_unregister(&rng->rng);
> +	writel(0, rng->base + RNGCON);
> +	clk_disable_unprepare(rng->clk);
> +	return 0;
> +}
> +
> +static const struct of_device_id pic32_rng_of_match[] = {
> +	{ .compatible	= "microchip,pic32mzda-rng", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
> +
> +static struct platform_driver pic32_rng_driver = {
> +	.probe		= pic32_rng_probe,
> +	.remove		= pic32_rng_remove,
> +	.driver		= {
> +		.name	= "pic32-rng",
> +		.owner	= THIS_MODULE,
> +		.of_match_table = of_match_ptr(pic32_rng_of_match),
> +	},
> +};
> +
> +module_platform_driver(pic32_rng_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
> +MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");
>

Re: [PATCH 2/2] rng: pic32-rng: Add PIC32 RNG hardware driver

[Joshua Henderson]

Daniel,

On 02/03/2016 04:22 AM, Daniel Thompson wrote:
> On 01/02/16 22:41, Joshua Henderson wrote:
>> Add support for the hardware pseudo and true random number generator
>> peripheral found on PIC32.
>>
>> Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
>> Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
>> ---
>>   drivers/char/hw_random/Kconfig     |   13 +++
>>   drivers/char/hw_random/Makefile    |    1 +
>>   drivers/char/hw_random/pic32-rng.c |  152 ++++++++++++++++++++++++++++++++++++
>>   3 files changed, 166 insertions(+)
>>   create mode 100644 drivers/char/hw_random/pic32-rng.c
>>
>> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
>> index dbf2271..3ab0c46 100644
>> --- a/drivers/char/hw_random/Kconfig
>> +++ b/drivers/char/hw_random/Kconfig
>> @@ -381,6 +381,19 @@ config HW_RANDOM_STM32
>>
>>         If unsure, say N.
>>
>> +config HW_RANDOM_PIC32
>> +    tristate "Microchip PIC32 Random Number Generator support"
>> +    depends on HW_RANDOM && MACH_PIC32
>> +    default y
>> +    ---help---
>> +      This driver provides kernel-side support for the Random Number
>> +      Generator hardware found on a PIC32.
>> +
>> +      To compile this driver as a module, choose M here. the
>> +      module will be called pic32-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 5ad3976..f5a6fa7 100644
>> --- a/drivers/char/hw_random/Makefile
>> +++ b/drivers/char/hw_random/Makefile
>> @@ -33,3 +33,4 @@ obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
>>   obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
>>   obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
>>   obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
>> +obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
>> diff --git a/drivers/char/hw_random/pic32-rng.c b/drivers/char/hw_random/pic32-rng.c
>> new file mode 100644
>> index 0000000..d2f32c4
>> --- /dev/null
>> +++ b/drivers/char/hw_random/pic32-rng.c
>> @@ -0,0 +1,152 @@
>> +/*
>> + * PIC32 RNG driver
>> + *
>> + * Joshua Henderson <joshua.henderson@microchip.com>
>> + * Copyright (C) 2016 Microchip Technology Inc.  All rights reserved.
>> + *
>> + * This program is free software; you can distribute it and/or modify it
>> + * under the terms of the GNU General Public License (Version 2) as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope 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/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/delay.h>
>> +#include <linux/slab.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/hw_random.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/clk.h>
>> +#include <linux/clkdev.h>
>> +
>> +#define RNGCON        0x04
>> +#define  TRNGEN        BIT(8)
>> +#define  PRNGEN        BIT(9)
>> +#define  PRNGCONT    BIT(10)
>> +#define  TRNGMOD    BIT(11)
>> +#define  SEEDLOAD    BIT(12)
>> +#define RNGPOLY1    0x08
>> +#define RNGPOLY2    0x0C
>> +#define RNGNUMGEN1    0x10
>> +#define RNGNUMGEN2    0x14
>> +#define RNGSEED1    0x18
>> +#define RNGSEED2    0x1C
>> +#define RNGRCNT        0x20
>> +#define  RCNT_MASK    0x7F
>> +
>> +struct pic32_rng {
>> +    void __iomem    *base;
>> +    struct hwrng    rng;
>> +    struct clk    *clk;
>> +};
>> +
>> +static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
>> +              bool wait)
>> +{
>> +    struct pic32_rng *prng = container_of(rng, struct pic32_rng, rng);
>> +    u64 *data = buf;
>> +
>> +    *data = ((u64)readl(prng->base + RNGNUMGEN2) << 32) +
>> +        readl(prng->base + RNGNUMGEN1);
>> +    return 4;
>> +}
> 
> I have a number of questions at this point (although #3 is by far the most important).
> 
> 1. If the random number of 42-bit shouldn't this be return 5; ?

You are right. However, this will essentially be changed to 8 in response to moving to just the TRNG in comments below.

> 
> 2. If you really do mean return 4; then why mess about with all the
>    shifting. You can just read and discard the upper 32-bits.
> 
> 3. Why are you using the PRNG at all? The PRNG is a simple LSFR and
>    I don't think it ever gets reseeded at any point (meaning we get
>    almost no useful entropy from it at all).
> 
>    Far better to read directly from the TRNG.

Makes sense.  Typically we just use the TRNG to seed the LSFR, but I suppose there is no real reason to do this if max speed is not a concern (above 24Mbps which is max TRNG speed).  I'll convert the driver to just drop usage of the PRNG and only use the TRNG.

> 
> 
>> +
>> +static int pic32_rng_probe(struct platform_device *pdev)
>> +{
>> +    struct pic32_rng *prng;
>> +    struct resource *res;
>> +    u32 v, t;
>> +    int ret;
>> +
>> +    prng = devm_kzalloc(&pdev->dev, sizeof(*prng), GFP_KERNEL);
>> +    if (!prng)
>> +        return -ENOMEM;
>> +
>> +    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +    prng->base = devm_ioremap_resource(&pdev->dev, res);
>> +    if (IS_ERR(prng->base))
>> +        return PTR_ERR(prng->base);
>> +
>> +    prng->clk = devm_clk_get(&pdev->dev, NULL);
>> +    if (IS_ERR(prng->clk))
>> +        return PTR_ERR(prng->clk);
>> +
>> +    clk_prepare_enable(prng->clk);
>> +
>> +    /* enable TRNG in enhanced mode */
>> +    v = readl(prng->base + RNGCON);
>> +    v &= ~(TRNGEN | PRNGEN | 0xff);
>> +    v |= TRNGMOD;
>> +    writel(v | TRNGEN, prng->base + RNGCON);
>> +
>> +    /* wait for valid seed */
>> +    usleep_range(100, 200);
>> +    t = readl(prng->base + RNGRCNT) & RCNT_MASK;
>> +    if (t < 0x2A)
>> +        dev_warn(&pdev->dev, "seed not generated.\n");
>> +
>> +    /* load initial seed */
>> +    writel(v | SEEDLOAD, prng->base + RNGCON);
>> +
>> +    /* load initial polynomial: 42bit poly */
>> +    writel(0x00c00003, prng->base + RNGPOLY1);
>> +    writel(0x00000000, prng->base + RNGPOLY2);
>> +
>> +    /* start PRNG to generate 42bit random */
>> +    v |= 0x2A | PRNGCONT | PRNGEN;
>> +    writel(v, prng->base + RNGCON);
>> +
>> +    prng->rng.name = pdev->name;
>> +    prng->rng.read = pic32_rng_read;
>> +
>> +    ret = hwrng_register(&prng->rng);
>> +    if (ret)
>> +        goto err_register;
>> +
>> +    platform_set_drvdata(pdev, prng);
>> +
>> +    return 0;
>> +
>> +err_register:
>> +    return ret;
> 
> Looks like we leak clock references on this error path.

Good catch.  Will fix.

> 
> 
>> +
>> +static int pic32_rng_remove(struct platform_device *pdev)
>> +{
>> +    struct pic32_rng *rng = platform_get_drvdata(pdev);
>> +
>> +    hwrng_unregister(&rng->rng);
>> +    writel(0, rng->base + RNGCON);
>> +    clk_disable_unprepare(rng->clk);
>> +    return 0;
>> +}
>> +
>> +static const struct of_device_id pic32_rng_of_match[] = {
>> +    { .compatible    = "microchip,pic32mzda-rng", },
>> +    { /* sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
>> +
>> +static struct platform_driver pic32_rng_driver = {
>> +    .probe        = pic32_rng_probe,
>> +    .remove        = pic32_rng_remove,
>> +    .driver        = {
>> +        .name    = "pic32-rng",
>> +        .owner    = THIS_MODULE,
>> +        .of_match_table = of_match_ptr(pic32_rng_of_match),
>> +    },
>> +};
>> +
>> +module_platform_driver(pic32_rng_driver);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
>> +MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");
>>
> 

After a bit of testing, converting the driver to be pure TRNG does give good results with rngtest. Good call.  Will submit an update.

Thanks,
Josh

Re: [PATCH 2/2] rng: pic32-rng: Add PIC32 RNG hardware driver

[Joshua Henderson]

Daniel,

On 02/03/2016 04:22 AM, Daniel Thompson wrote:
> On 01/02/16 22:41, Joshua Henderson wrote:
>> Add support for the hardware pseudo and true random number generator
>> peripheral found on PIC32.
>>
>> Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
>> Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
>> ---
>>   drivers/char/hw_random/Kconfig     |   13 +++
>>   drivers/char/hw_random/Makefile    |    1 +
>>   drivers/char/hw_random/pic32-rng.c |  152 ++++++++++++++++++++++++++++++++++++
>>   3 files changed, 166 insertions(+)
>>   create mode 100644 drivers/char/hw_random/pic32-rng.c
>>
>> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
>> index dbf2271..3ab0c46 100644
>> --- a/drivers/char/hw_random/Kconfig
>> +++ b/drivers/char/hw_random/Kconfig
>> @@ -381,6 +381,19 @@ config HW_RANDOM_STM32
>>
>>         If unsure, say N.
>>
>> +config HW_RANDOM_PIC32
>> +    tristate "Microchip PIC32 Random Number Generator support"
>> +    depends on HW_RANDOM && MACH_PIC32
>> +    default y
>> +    ---help---
>> +      This driver provides kernel-side support for the Random Number
>> +      Generator hardware found on a PIC32.
>> +
>> +      To compile this driver as a module, choose M here. the
>> +      module will be called pic32-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 5ad3976..f5a6fa7 100644
>> --- a/drivers/char/hw_random/Makefile
>> +++ b/drivers/char/hw_random/Makefile
>> @@ -33,3 +33,4 @@ obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
>>   obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
>>   obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
>>   obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
>> +obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
>> diff --git a/drivers/char/hw_random/pic32-rng.c b/drivers/char/hw_random/pic32-rng.c
>> new file mode 100644
>> index 0000000..d2f32c4
>> --- /dev/null
>> +++ b/drivers/char/hw_random/pic32-rng.c
>> @@ -0,0 +1,152 @@
>> +/*
>> + * PIC32 RNG driver
>> + *
>> + * Joshua Henderson <joshua.henderson@microchip.com>
>> + * Copyright (C) 2016 Microchip Technology Inc.  All rights reserved.
>> + *
>> + * This program is free software; you can distribute it and/or modify it
>> + * under the terms of the GNU General Public License (Version 2) as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope 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/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/delay.h>
>> +#include <linux/slab.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/hw_random.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/clk.h>
>> +#include <linux/clkdev.h>
>> +
>> +#define RNGCON        0x04
>> +#define  TRNGEN        BIT(8)
>> +#define  PRNGEN        BIT(9)
>> +#define  PRNGCONT    BIT(10)
>> +#define  TRNGMOD    BIT(11)
>> +#define  SEEDLOAD    BIT(12)
>> +#define RNGPOLY1    0x08
>> +#define RNGPOLY2    0x0C
>> +#define RNGNUMGEN1    0x10
>> +#define RNGNUMGEN2    0x14
>> +#define RNGSEED1    0x18
>> +#define RNGSEED2    0x1C
>> +#define RNGRCNT        0x20
>> +#define  RCNT_MASK    0x7F
>> +
>> +struct pic32_rng {
>> +    void __iomem    *base;
>> +    struct hwrng    rng;
>> +    struct clk    *clk;
>> +};
>> +
>> +static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
>> +              bool wait)
>> +{
>> +    struct pic32_rng *prng = container_of(rng, struct pic32_rng, rng);
>> +    u64 *data = buf;
>> +
>> +    *data = ((u64)readl(prng->base + RNGNUMGEN2) << 32) +
>> +        readl(prng->base + RNGNUMGEN1);
>> +    return 4;
>> +}
> 
> I have a number of questions at this point (although #3 is by far the most important).
> 
> 1. If the random number of 42-bit shouldn't this be return 5; ?

You are right. However, this will essentially be changed to 8 in response to moving to just the TRNG in comments below.

> 
> 2. If you really do mean return 4; then why mess about with all the
>    shifting. You can just read and discard the upper 32-bits.
> 
> 3. Why are you using the PRNG at all? The PRNG is a simple LSFR and
>    I don't think it ever gets reseeded at any point (meaning we get
>    almost no useful entropy from it at all).
> 
>    Far better to read directly from the TRNG.

Makes sense.  Typically we just use the TRNG to seed the LSFR, but I suppose there is no real reason to do this if max speed is not a concern (above 24Mbps which is max TRNG speed).  I'll convert the driver to just drop usage of the PRNG and only use the TRNG.

> 
> 
>> +
>> +static int pic32_rng_probe(struct platform_device *pdev)
>> +{
>> +    struct pic32_rng *prng;
>> +    struct resource *res;
>> +    u32 v, t;
>> +    int ret;
>> +
>> +    prng = devm_kzalloc(&pdev->dev, sizeof(*prng), GFP_KERNEL);
>> +    if (!prng)
>> +        return -ENOMEM;
>> +
>> +    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +    prng->base = devm_ioremap_resource(&pdev->dev, res);
>> +    if (IS_ERR(prng->base))
>> +        return PTR_ERR(prng->base);
>> +
>> +    prng->clk = devm_clk_get(&pdev->dev, NULL);
>> +    if (IS_ERR(prng->clk))
>> +        return PTR_ERR(prng->clk);
>> +
>> +    clk_prepare_enable(prng->clk);
>> +
>> +    /* enable TRNG in enhanced mode */
>> +    v = readl(prng->base + RNGCON);
>> +    v &= ~(TRNGEN | PRNGEN | 0xff);
>> +    v |= TRNGMOD;
>> +    writel(v | TRNGEN, prng->base + RNGCON);
>> +
>> +    /* wait for valid seed */
>> +    usleep_range(100, 200);
>> +    t = readl(prng->base + RNGRCNT) & RCNT_MASK;
>> +    if (t < 0x2A)
>> +        dev_warn(&pdev->dev, "seed not generated.\n");
>> +
>> +    /* load initial seed */
>> +    writel(v | SEEDLOAD, prng->base + RNGCON);
>> +
>> +    /* load initial polynomial: 42bit poly */
>> +    writel(0x00c00003, prng->base + RNGPOLY1);
>> +    writel(0x00000000, prng->base + RNGPOLY2);
>> +
>> +    /* start PRNG to generate 42bit random */
>> +    v |= 0x2A | PRNGCONT | PRNGEN;
>> +    writel(v, prng->base + RNGCON);
>> +
>> +    prng->rng.name = pdev->name;
>> +    prng->rng.read = pic32_rng_read;
>> +
>> +    ret = hwrng_register(&prng->rng);
>> +    if (ret)
>> +        goto err_register;
>> +
>> +    platform_set_drvdata(pdev, prng);
>> +
>> +    return 0;
>> +
>> +err_register:
>> +    return ret;
> 
> Looks like we leak clock references on this error path.

Good catch.  Will fix.

> 
> 
>> +
>> +static int pic32_rng_remove(struct platform_device *pdev)
>> +{
>> +    struct pic32_rng *rng = platform_get_drvdata(pdev);
>> +
>> +    hwrng_unregister(&rng->rng);
>> +    writel(0, rng->base + RNGCON);
>> +    clk_disable_unprepare(rng->clk);
>> +    return 0;
>> +}
>> +
>> +static const struct of_device_id pic32_rng_of_match[] = {
>> +    { .compatible    = "microchip,pic32mzda-rng", },
>> +    { /* sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
>> +
>> +static struct platform_driver pic32_rng_driver = {
>> +    .probe        = pic32_rng_probe,
>> +    .remove        = pic32_rng_remove,
>> +    .driver        = {
>> +        .name    = "pic32-rng",
>> +        .owner    = THIS_MODULE,
>> +        .of_match_table = of_match_ptr(pic32_rng_of_match),
>> +    },
>> +};
>> +
>> +module_platform_driver(pic32_rng_driver);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
>> +MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");
>>
> 

After a bit of testing, converting the driver to be pure TRNG does give good results with rngtest. Good call.  Will submit an update.

Thanks,
Josh

Re: [PATCH 1/2] dt/bindings: Add bindings for the PIC32 random number generator

[Rob Herring]

On Mon, Feb 01, 2016 at 03:41:41PM -0700, Joshua Henderson wrote:
> Document the devicetree bindings for the random number generator found
> on Microchip PIC32 class devices.
> 
> Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
> ---
>  .../bindings/rng/microchip,pic32-rng.txt           |   17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH 1/2] dt/bindings: Add bindings for the PIC32 random number generator

[Rob Herring]

On Mon, Feb 01, 2016 at 03:41:41PM -0700, Joshua Henderson wrote:
> Document the devicetree bindings for the random number generator found
> on Microchip PIC32 class devices.
> 
> Signed-off-by: Joshua Henderson <joshua.henderson-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org>
> ---
>  .../bindings/rng/microchip,pic32-rng.txt           |   17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rng/microchip,pic32-rng.txt

Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html