[PATCH] hwrng: add support for picoxcell TRNG

[PATCH] hwrng: add support for picoxcell TRNG

[Jamie Iles]

This driver adds support for the True Random Number Generator in
the Picochip PC3X3 and later devices.

Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
---

ARCH_PICOXCELL machine support patches have been posted the ARM mailing
lists for review (with another revision to follow soon).

 drivers/char/hw_random/Kconfig         |   12 ++
 drivers/char/hw_random/Makefile        |    1 +
 drivers/char/hw_random/picoxcell-rng.c |  175 ++++++++++++++++++++++++++++++++
 3 files changed, 188 insertions(+), 0 deletions(-)
 create mode 100644 drivers/char/hw_random/picoxcell-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index d31483c..beecd1c 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -198,3 +198,15 @@ config HW_RANDOM_NOMADIK
 	  module will be called nomadik-rng.
 
 	  If unsure, say Y.
+
+config HW_RANDOM_PICOXCELL
+	tristate "Picochip picoXcell true random number generator support"
+	depends on HW_RANDOM && ARCH_PICOXCELL && PICOXCELL_PC3X3
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on Picochip PC3x3 and later devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called picoxcell-rng.
+
+	  If unsure, say Y.
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 4273308..3db4eb8 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -19,3 +19,4 @@ obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o
 obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o
 obj-$(CONFIG_HW_RANDOM_OCTEON) += octeon-rng.o
 obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o
+obj-$(CONFIG_HW_RANDOM_PICOXCELL) += picoxcell-rng.o
diff --git a/drivers/char/hw_random/picoxcell-rng.c b/drivers/char/hw_random/picoxcell-rng.c
new file mode 100644
index 0000000..e750056
--- /dev/null
+++ b/drivers/char/hw_random/picoxcell-rng.c
@@ -0,0 +1,175 @@
+/*
+ * Copyright (c) 2010-2011 Picochip Ltd., Jamie Iles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * All enquiries to support@picochip.com
+ */
+#include <linux/clk.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 DATA_REG_OFFSET			0x0200
+#define CSR_REG_OFFSET			0x0278
+#define		CSR_OUT_EMPTY_MASK	(1 << 24)
+#define TAI_REG_OFFSET			0x0380
+
+static void __iomem *rng_base;
+static struct clk *rng_clk;
+
+/*
+ * Get some random data from the random number generator. The hw_random core
+ * layer provides us with locking. We can't rely on data being word aligned
+ * though so we'll need to do a memcpy.
+ */
+static int picoxcell_trng_read(struct hwrng *rng, void *buf, size_t max,
+			       bool wait)
+{
+	u32 __iomem *csr = rng_base + CSR_REG_OFFSET;
+	int data_avail = !(__raw_readl(csr) & CSR_OUT_EMPTY_MASK);
+	u32 data;
+
+	if (!data_avail && !wait)
+		return 0;
+
+	/* Wait for some data to become available. */
+	while (!data_avail) {
+		data_avail = !(__raw_readl(csr) & CSR_OUT_EMPTY_MASK);
+		cpu_relax();
+	}
+
+	data = __raw_readl(rng_base + DATA_REG_OFFSET);
+	memcpy(buf, &data, min(max, sizeof(data)));
+
+	return sizeof(data);
+}
+
+static struct hwrng picoxcell_trng = {
+	.name		= "picoxcell",
+	.read		= picoxcell_trng_read,
+};
+
+/*
+ * Take the random number generator out of reset and make sure the interrupts
+ * are masked. We shouldn't need to get large amounts of random bytes so just
+ * poll the status register. The hardware generates 32 bits every 320ns so we
+ * shouldn't have to wait long enough to warrant waiting for an IRQ.
+ */
+static void picoxcell_trng_start(void)
+{
+	__raw_writel(0, rng_base + TAI_REG_OFFSET);
+	__raw_writel(0, rng_base + CSR_REG_OFFSET);
+}
+
+static int picoxcell_trng_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	if (!mem) {
+		dev_warn(&pdev->dev, "no memory resource\n");
+		return -ENOMEM;
+	}
+
+	if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
+				     "picoxcell_trng")) {
+		dev_warn(&pdev->dev, "unable to request io mem\n");
+		return -EBUSY;
+	}
+
+	rng_base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
+	if (!rng_base) {
+		dev_warn(&pdev->dev, "unable to remap io mem\n");
+		return -ENOMEM;
+	}
+
+	rng_clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(rng_clk)) {
+		dev_warn(&pdev->dev, "no clk\n");
+		return PTR_ERR(rng_clk);
+	}
+
+	ret = clk_enable(rng_clk);
+	if (ret) {
+		dev_warn(&pdev->dev, "unable to enable clk\n");
+		goto err_enable;
+	}
+
+	picoxcell_trng_start();
+	ret = hwrng_register(&picoxcell_trng);
+	if (ret)
+		goto err_register;
+
+	dev_info(&pdev->dev, "pixoxcell random number generator active\n");
+
+	return 0;
+
+err_register:
+	clk_disable(rng_clk);
+err_enable:
+	clk_put(rng_clk);
+
+	return ret;
+}
+
+static int __devexit picoxcell_trng_remove(struct platform_device *pdev)
+{
+	hwrng_unregister(&picoxcell_trng);
+	clk_disable(rng_clk);
+	clk_put(rng_clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int picoxcell_trng_suspend(struct device *dev)
+{
+	clk_disable(rng_clk);
+
+	return 0;
+}
+
+static int picoxcell_trng_resume(struct device *dev)
+{
+	return clk_enable(rng_clk);
+}
+
+static const struct dev_pm_ops picoxcell_trng_pm_ops = {
+	.suspend	= picoxcell_trng_suspend,
+	.resume		= picoxcell_trng_resume,
+};
+#endif /* CONFIG_PM */
+
+static struct platform_driver picoxcell_trng_driver = {
+	.probe		= picoxcell_trng_probe,
+	.remove		= __devexit_p(picoxcell_trng_remove),
+	.driver		= {
+		.name	= "picoxcell-trng",
+		.owner	= THIS_MODULE,
+#ifdef CONFIG_PM
+		.pm	= &picoxcell_trng_pm_ops,
+#endif /* CONFIG_PM */
+	},
+};
+
+static int __init picoxcell_trng_init(void)
+{
+	return platform_driver_register(&picoxcell_trng_driver);
+}
+module_init(picoxcell_trng_init);
+
+static void __exit picoxcell_trng_exit(void)
+{
+	platform_driver_unregister(&picoxcell_trng_driver);
+}
+module_exit(picoxcell_trng_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jamie Iles");
+MODULE_DESCRIPTION("Picochip picoXcell TRNG driver");
-- 
1.7.3.4

Re: [PATCH] hwrng: add support for picoxcell TRNG

[Matt Mackall]

On Fri, 2011-01-14 at 16:10 +0000, Jamie Iles wrote:
> This driver adds support for the True Random Number Generator in
> the Picochip PC3X3 and later devices.
> 
> Cc: Matt Mackall <mpm@selenic.com>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> 
> Signed-off-by: Jamie Iles <jamie@jamieiles.com>
> ---
> 
> ARCH_PICOXCELL machine support patches have been posted the ARM mailing
> lists for review (with another revision to follow soon).
> 
>  drivers/char/hw_random/Kconfig         |   12 ++
>  drivers/char/hw_random/Makefile        |    1 +
>  drivers/char/hw_random/picoxcell-rng.c |  175 ++++++++++++++++++++++++++++++++
>  3 files changed, 188 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/char/hw_random/picoxcell-rng.c
> 
> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> index d31483c..beecd1c 100644
> --- a/drivers/char/hw_random/Kconfig
> +++ b/drivers/char/hw_random/Kconfig
> @@ -198,3 +198,15 @@ config HW_RANDOM_NOMADIK
>  	  module will be called nomadik-rng.
>  
>  	  If unsure, say Y.
> +
> +config HW_RANDOM_PICOXCELL
> +	tristate "Picochip picoXcell true random number generator support"
> +	depends on HW_RANDOM && ARCH_PICOXCELL && PICOXCELL_PC3X3
> +	---help---
> +	  This driver provides kernel-side support for the Random Number
> +	  Generator hardware found on Picochip PC3x3 and later devices.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called picoxcell-rng.
> +
> +	  If unsure, say Y.
> diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
> index 4273308..3db4eb8 100644
> --- a/drivers/char/hw_random/Makefile
> +++ b/drivers/char/hw_random/Makefile
> @@ -19,3 +19,4 @@ obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o
>  obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o
>  obj-$(CONFIG_HW_RANDOM_OCTEON) += octeon-rng.o
>  obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o
> +obj-$(CONFIG_HW_RANDOM_PICOXCELL) += picoxcell-rng.o
> diff --git a/drivers/char/hw_random/picoxcell-rng.c b/drivers/char/hw_random/picoxcell-rng.c
> new file mode 100644
> index 0000000..e750056
> --- /dev/null
> +++ b/drivers/char/hw_random/picoxcell-rng.c
> @@ -0,0 +1,175 @@
> +/*
> + * Copyright (c) 2010-2011 Picochip Ltd., Jamie Iles
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * All enquiries to support@picochip.com
> + */
> +#include <linux/clk.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 DATA_REG_OFFSET			0x0200
> +#define CSR_REG_OFFSET			0x0278
> +#define		CSR_OUT_EMPTY_MASK	(1 << 24)
> +#define TAI_REG_OFFSET			0x0380

Some whitespace weirdness here. Recommend never using tabs except at the
beginning of a line.

> +static void __iomem *rng_base;
> +static struct clk *rng_clk;
> +
> +/*
> + * Get some random data from the random number generator. The hw_random core
> + * layer provides us with locking. We can't rely on data being word aligned
> + * though so we'll need to do a memcpy.
> + */
> +static int picoxcell_trng_read(struct hwrng *rng, void *buf, size_t max,
> +			       bool wait)
> +{
> +	u32 __iomem *csr = rng_base + CSR_REG_OFFSET;
> +	int data_avail = !(__raw_readl(csr) & CSR_OUT_EMPTY_MASK);
> +	u32 data;
> +
> +	if (!data_avail && !wait)
> +		return 0;
> +
> +	/* Wait for some data to become available. */
> +	while (!data_avail) {
> +		data_avail = !(__raw_readl(csr) & CSR_OUT_EMPTY_MASK);
> +		cpu_relax();
> +	}

This could be simplified a bit:

- deduplicate avail check
- only relax when data's not available
- drop some one use vars

while (!__raw_read(rng_base + ...) {
	if (!wait)
		return;
	cpu_relax();
}	
	
> +	data = __raw_readl(rng_base + DATA_REG_OFFSET);
> +	memcpy(buf, &data, min(max, sizeof(data)));

The buffer passed in is guaranteed aligned:

static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]
	__cacheline_aligned;
...
		return rng->read(rng, (void *)buffer, size, wait);

-- 
Mathematics is the supreme nostalgia of our time.

Re: [PATCH] hwrng: add support for picoxcell TRNG

[Jamie Iles]

Hi Matt,

Many thanks for the quick feedback!

On Fri, Jan 14, 2011 at 11:49:13AM -0600, Matt Mackall wrote:
> On Fri, 2011-01-14 at 16:10 +0000, Jamie Iles wrote:
> > This driver adds support for the True Random Number Generator in
> > diff --git a/drivers/char/hw_random/Makefile 
> > b/drivers/char/hw_random/Makefile
> > index 4273308..3db4eb8 100644
> > --- a/drivers/char/hw_random/Makefile
> > +++ b/drivers/char/hw_random/Makefile
> > @@ -19,3 +19,4 @@ obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o
> >  obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o
> >  obj-$(CONFIG_HW_RANDOM_OCTEON) += octeon-rng.o
> >  obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o
> > +obj-$(CONFIG_HW_RANDOM_PICOXCELL) += picoxcell-rng.o
> > diff --git a/drivers/char/hw_random/picoxcell-rng.c b/drivers/char/hw_random/picoxcell-rng.c
> > new file mode 100644
> > index 0000000..e750056
> > --- /dev/null
> > +++ b/drivers/char/hw_random/picoxcell-rng.c
> > @@ -0,0 +1,175 @@
> > +/*
> > + * Copyright (c) 2010-2011 Picochip Ltd., Jamie Iles
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * All enquiries to support@picochip.com
> > + */
> > +#include <linux/clk.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 DATA_REG_OFFSET			0x0200
> > +#define CSR_REG_OFFSET			0x0278
> > +#define		CSR_OUT_EMPTY_MASK	(1 << 24)
> > +#define TAI_REG_OFFSET			0x0380
> 
> Some whitespace weirdness here. Recommend never using tabs except at the
> beginning of a line.

I'll fix that up, not sure what happened there.

> > +static void __iomem *rng_base;
> > +static struct clk *rng_clk;
> > +
> > +/*
> > + * Get some random data from the random number generator. The hw_random core
> > + * layer provides us with locking. We can't rely on data being word aligned
> > + * though so we'll need to do a memcpy.
> > + */
> > +static int picoxcell_trng_read(struct hwrng *rng, void *buf, size_t max,
> > +			       bool wait)
> > +{
> > +	u32 __iomem *csr = rng_base + CSR_REG_OFFSET;
> > +	int data_avail = !(__raw_readl(csr) & CSR_OUT_EMPTY_MASK);
> > +	u32 data;
> > +
> > +	if (!data_avail && !wait)
> > +		return 0;
> > +
> > +	/* Wait for some data to become available. */
> > +	while (!data_avail) {
> > +		data_avail = !(__raw_readl(csr) & CSR_OUT_EMPTY_MASK);
> > +		cpu_relax();
> > +	}
> 
> This could be simplified a bit:
> 
> - deduplicate avail check
> - only relax when data's not available
> - drop some one use vars
> 
> while (!__raw_read(rng_base + ...) {
> 	if (!wait)
> 		return;
> 	cpu_relax();
> }	

Yes, that's much neater.

> > +	data = __raw_readl(rng_base + DATA_REG_OFFSET);
> > +	memcpy(buf, &data, min(max, sizeof(data)));
> 
> The buffer passed in is guaranteed aligned:
> 
> static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]
> 	__cacheline_aligned;
> ...
> 		return rng->read(rng, (void *)buffer, size, wait);

Ok, that makes sense.  I must have confused myself with the __user 
buffer which doesn't have any alignment guarantees.

Thanks again for the review, I'll get a respin out early next week.

Jamie

[PATCHv2] hwrng: add support for picoxcell TRNG

[Jamie Iles]

This driver adds support for the True Random Number Generator in
the Picochip PC3X3 and later devices.

v2: fix indentation and cleanup read function to remove single use
variables and to take advantage of the rng buffer being aligned.

Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
---
 drivers/char/hw_random/Kconfig         |   12 +++
 drivers/char/hw_random/Makefile        |    1 +
 drivers/char/hw_random/picoxcell-rng.c |  169 ++++++++++++++++++++++++++++++++
 3 files changed, 182 insertions(+), 0 deletions(-)
 create mode 100644 drivers/char/hw_random/picoxcell-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index d31483c..beecd1c 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -198,3 +198,15 @@ config HW_RANDOM_NOMADIK
 	  module will be called nomadik-rng.
 
 	  If unsure, say Y.
+
+config HW_RANDOM_PICOXCELL
+	tristate "Picochip picoXcell true random number generator support"
+	depends on HW_RANDOM && ARCH_PICOXCELL && PICOXCELL_PC3X3
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on Picochip PC3x3 and later devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called picoxcell-rng.
+
+	  If unsure, say Y.
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 4273308..3db4eb8 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -19,3 +19,4 @@ obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o
 obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o
 obj-$(CONFIG_HW_RANDOM_OCTEON) += octeon-rng.o
 obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o
+obj-$(CONFIG_HW_RANDOM_PICOXCELL) += picoxcell-rng.o
diff --git a/drivers/char/hw_random/picoxcell-rng.c b/drivers/char/hw_random/picoxcell-rng.c
new file mode 100644
index 0000000..9f32760
--- /dev/null
+++ b/drivers/char/hw_random/picoxcell-rng.c
@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2010-2011 Picochip Ltd., Jamie Iles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * All enquiries to support@picochip.com
+ */
+#include <linux/clk.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 DATA_REG_OFFSET		0x0200
+#define CSR_REG_OFFSET		0x0278
+#define CSR_OUT_EMPTY_MASK	(1 << 24)
+#define TAI_REG_OFFSET		0x0380
+
+static void __iomem *rng_base;
+static struct clk *rng_clk;
+
+/*
+ * Get some random data from the random number generator. The hw_random core
+ * layer provides us with locking.
+ */
+static int picoxcell_trng_read(struct hwrng *rng, void *buf, size_t max,
+			       bool wait)
+{
+	u32 __iomem *csr = rng_base + CSR_REG_OFFSET;
+
+	/* Wait for some data to become available. */
+	while (__raw_readl(csr) & CSR_OUT_EMPTY_MASK) {
+		if (!wait)
+			return 0;
+		cpu_relax();
+	}
+
+	*(u32 *)buf = __raw_readl(rng_base + DATA_REG_OFFSET);
+
+	return sizeof(u32);
+}
+
+static struct hwrng picoxcell_trng = {
+	.name		= "picoxcell",
+	.read		= picoxcell_trng_read,
+};
+
+/*
+ * Take the random number generator out of reset and make sure the interrupts
+ * are masked. We shouldn't need to get large amounts of random bytes so just
+ * poll the status register. The hardware generates 32 bits every 320ns so we
+ * shouldn't have to wait long enough to warrant waiting for an IRQ.
+ */
+static void picoxcell_trng_start(void)
+{
+	__raw_writel(0, rng_base + TAI_REG_OFFSET);
+	__raw_writel(0, rng_base + CSR_REG_OFFSET);
+}
+
+static int picoxcell_trng_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	if (!mem) {
+		dev_warn(&pdev->dev, "no memory resource\n");
+		return -ENOMEM;
+	}
+
+	if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
+				     "picoxcell_trng")) {
+		dev_warn(&pdev->dev, "unable to request io mem\n");
+		return -EBUSY;
+	}
+
+	rng_base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
+	if (!rng_base) {
+		dev_warn(&pdev->dev, "unable to remap io mem\n");
+		return -ENOMEM;
+	}
+
+	rng_clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(rng_clk)) {
+		dev_warn(&pdev->dev, "no clk\n");
+		return PTR_ERR(rng_clk);
+	}
+
+	ret = clk_enable(rng_clk);
+	if (ret) {
+		dev_warn(&pdev->dev, "unable to enable clk\n");
+		goto err_enable;
+	}
+
+	picoxcell_trng_start();
+	ret = hwrng_register(&picoxcell_trng);
+	if (ret)
+		goto err_register;
+
+	dev_info(&pdev->dev, "pixoxcell random number generator active\n");
+
+	return 0;
+
+err_register:
+	clk_disable(rng_clk);
+err_enable:
+	clk_put(rng_clk);
+
+	return ret;
+}
+
+static int __devexit picoxcell_trng_remove(struct platform_device *pdev)
+{
+	hwrng_unregister(&picoxcell_trng);
+	clk_disable(rng_clk);
+	clk_put(rng_clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int picoxcell_trng_suspend(struct device *dev)
+{
+	clk_disable(rng_clk);
+
+	return 0;
+}
+
+static int picoxcell_trng_resume(struct device *dev)
+{
+	return clk_enable(rng_clk);
+}
+
+static const struct dev_pm_ops picoxcell_trng_pm_ops = {
+	.suspend	= picoxcell_trng_suspend,
+	.resume		= picoxcell_trng_resume,
+};
+#endif /* CONFIG_PM */
+
+static struct platform_driver picoxcell_trng_driver = {
+	.probe		= picoxcell_trng_probe,
+	.remove		= __devexit_p(picoxcell_trng_remove),
+	.driver		= {
+		.name	= "picoxcell-trng",
+		.owner	= THIS_MODULE,
+#ifdef CONFIG_PM
+		.pm	= &picoxcell_trng_pm_ops,
+#endif /* CONFIG_PM */
+	},
+};
+
+static int __init picoxcell_trng_init(void)
+{
+	return platform_driver_register(&picoxcell_trng_driver);
+}
+module_init(picoxcell_trng_init);
+
+static void __exit picoxcell_trng_exit(void)
+{
+	platform_driver_unregister(&picoxcell_trng_driver);
+}
+module_exit(picoxcell_trng_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jamie Iles");
+MODULE_DESCRIPTION("Picochip picoXcell TRNG driver");
-- 
1.7.3.4

Re: [PATCHv2] hwrng: add support for picoxcell TRNG

[Matt Mackall]

On Fri, 2011-01-14 at 18:44 +0000, Jamie Iles wrote:
> This driver adds support for the True Random Number Generator in
> the Picochip PC3X3 and later devices.
> 
> v2: fix indentation and cleanup read function to remove single use
> variables and to take advantage of the rng buffer being aligned.
> 
> Cc: Matt Mackall <mpm@selenic.com>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>

Acked-by: Matt Mackall <mpm@selenic.com>

-- 
Mathematics is the supreme nostalgia of our time.

Re: [PATCHv2] hwrng: add support for picoxcell TRNG

[Alexander Clouter]

In gmane.linux.ports.arm.kernel Jamie Iles <jamie@jamieiles.com> wrote:
>
> This driver adds support for the True Random Number Generator in
> the Picochip PC3X3 and later devices.
> 
> [snipped]
>
> +/*
> + * Take the random number generator out of reset and make sure the interrupts
> + * are masked. We shouldn't need to get large amounts of random bytes so just
> + * poll the status register. The hardware generates 32 bits every 320ns so we
> + * shouldn't have to wait long enough to warrant waiting for an IRQ.
> + */
>
timeriomem-rng?  Example of usage in 
arch/arm/mach-orion5x/ts78xx-setup.c.

Cheers

-- 
Alexander Clouter
.sigmonster says: The more I know men the more I like my horse.

Re: [PATCHv2] hwrng: add support for picoxcell TRNG

[Jamie Iles]

On Fri, Jan 14, 2011 at 08:45:19PM +0000, Alexander Clouter wrote:
> In gmane.linux.ports.arm.kernel Jamie Iles <jamie@jamieiles.com> wrote:
> >
> > This driver adds support for the True Random Number Generator in
> > the Picochip PC3X3 and later devices.
> > 
> > [snipped]
> >
> > +/*
> > + * Take the random number generator out of reset and make sure the interrupts
> > + * are masked. We shouldn't need to get large amounts of random bytes so just
> > + * poll the status register. The hardware generates 32 bits every 320ns so we
> > + * shouldn't have to wait long enough to warrant waiting for an IRQ.
> > + */
> >
> timeriomem-rng?  Example of usage in 
> arch/arm/mach-orion5x/ts78xx-setup.c.

No, that's not quite suitable for our hardware.  Although the hardware 
generates the data every 320ns, it also performs self test of the data 
in hardware to make sure it satisfies certain random qualities.  If the 
data doesn't pass the tests then it's rejected and not placed into the 
FIFO so we'd have the possibility of an underflow with the 
timeriomem-rng driver.

Jamie

Re: [PATCHv2] hwrng: add support for picoxcell TRNG

[Herbert Xu]

On Fri, Jan 14, 2011 at 06:44:21PM +0000, Jamie Iles wrote:
>
> +	/* Wait for some data to become available. */
> +	while (__raw_readl(csr) & CSR_OUT_EMPTY_MASK) {
> +		if (!wait)
> +			return 0;
> +		cpu_relax();
> +	}

This has the potential to loop indefinitely.  Please add a time-out
to prevent that (see existing RNG drivers for example).

Thanks!
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCHv2] hwrng: add support for picoxcell TRNG

[Jamie Iles]

On Sat, Jan 15, 2011 at 11:44:16AM +1100, Herbert Xu wrote:
> On Fri, Jan 14, 2011 at 06:44:21PM +0000, Jamie Iles wrote:
> >
> > +	/* Wait for some data to become available. */
> > +	while (__raw_readl(csr) & CSR_OUT_EMPTY_MASK) {
> > +		if (!wait)
> > +			return 0;
> > +		cpu_relax();
> > +	}
> 
> This has the potential to loop indefinitely.  Please add a time-out
> to prevent that (see existing RNG drivers for example).

Ok, that's a fair point!  Here's an updated version with a timeout.  
I've also added in support for the fault detection which I previously 
overlooked.

Jamie

8<--------

>From f58efb08a99a5d82a86fefd97e4adf5cab3595a8 Mon Sep 17 00:00:00 2001
From: Jamie Iles <jamie@jamieiles.com>
Date: Fri, 14 Jan 2011 12:16:50 +0000
Subject: [PATCHv3] hwrng: add support for picoxcell TRNG

This driver adds support for the True Random Number Generator in
the Picochip PC3X3 and later devices.

v3: add a timeout of 20us to the read() method and add fault detection
and reset.

v2: fix indentation and cleanup read function to remove single use
variables and to take advantage of the rng buffer being aligned.

Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
---
 drivers/char/hw_random/Kconfig         |   12 ++
 drivers/char/hw_random/Makefile        |    1 +
 drivers/char/hw_random/picoxcell-rng.c |  208 ++++++++++++++++++++++++++++++++
 3 files changed, 221 insertions(+), 0 deletions(-)
 create mode 100644 drivers/char/hw_random/picoxcell-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index d31483c..beecd1c 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -198,3 +198,15 @@ config HW_RANDOM_NOMADIK
 	  module will be called nomadik-rng.
 
 	  If unsure, say Y.
+
+config HW_RANDOM_PICOXCELL
+	tristate "Picochip picoXcell true random number generator support"
+	depends on HW_RANDOM && ARCH_PICOXCELL && PICOXCELL_PC3X3
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on Picochip PC3x3 and later devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called picoxcell-rng.
+
+	  If unsure, say Y.
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 4273308..3db4eb8 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -19,3 +19,4 @@ obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o
 obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o
 obj-$(CONFIG_HW_RANDOM_OCTEON) += octeon-rng.o
 obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o
+obj-$(CONFIG_HW_RANDOM_PICOXCELL) += picoxcell-rng.o
diff --git a/drivers/char/hw_random/picoxcell-rng.c b/drivers/char/hw_random/picoxcell-rng.c
new file mode 100644
index 0000000..990d55a
--- /dev/null
+++ b/drivers/char/hw_random/picoxcell-rng.c
@@ -0,0 +1,208 @@
+/*
+ * Copyright (c) 2010-2011 Picochip Ltd., Jamie Iles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * All enquiries to support@picochip.com
+ */
+#include <linux/clk.h>
+#include <linux/delay.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 DATA_REG_OFFSET		0x0200
+#define CSR_REG_OFFSET		0x0278
+#define CSR_OUT_EMPTY_MASK	(1 << 24)
+#define CSR_FAULT_MASK		(1 << 1)
+#define TRNG_BLOCK_RESET_MASK	(1 << 0)
+#define TAI_REG_OFFSET		0x0380
+
+/*
+ * The maximum amount of time in microseconds to spend waiting for data if the
+ * core wants us to wait.  The TRNG should generate 32 bits every 320ns so a
+ * timeout of 20us seems reasonable.  The TRNG does builtin tests of the data
+ * for randomness so we can't always assume there is data present.
+ */
+#define PICO_TRNG_TIMEOUT		20
+
+static void __iomem *rng_base;
+static struct clk *rng_clk;
+struct device *rng_dev;
+
+static inline u32 picoxcell_trng_read_csr(void)
+{
+	return __raw_readl(rng_base + CSR_REG_OFFSET);
+}
+
+static inline bool picoxcell_trng_is_empty(void)
+{
+	return picoxcell_trng_read_csr() & CSR_OUT_EMPTY_MASK;
+}
+
+/*
+ * Take the random number generator out of reset and make sure the interrupts
+ * are masked. We shouldn't need to get large amounts of random bytes so just
+ * poll the status register. The hardware generates 32 bits every 320ns so we
+ * shouldn't have to wait long enough to warrant waiting for an IRQ.
+ */
+static void picoxcell_trng_start(void)
+{
+	__raw_writel(0, rng_base + TAI_REG_OFFSET);
+	__raw_writel(0, rng_base + CSR_REG_OFFSET);
+}
+
+static void picoxcell_trng_reset(void)
+{
+	__raw_writel(TRNG_BLOCK_RESET_MASK, rng_base + CSR_REG_OFFSET);
+	__raw_writel(TRNG_BLOCK_RESET_MASK, rng_base + TAI_REG_OFFSET);
+	picoxcell_trng_start();
+}
+
+/*
+ * Get some random data from the random number generator. The hw_random core
+ * layer provides us with locking.
+ */
+static int picoxcell_trng_read(struct hwrng *rng, void *buf, size_t max,
+			       bool wait)
+{
+	int i;
+
+	/* Wait for some data to become available. */
+	for (i = 0; i < PICO_TRNG_TIMEOUT && picoxcell_trng_is_empty(); ++i) {
+		if (!wait)
+			return 0;
+
+		udelay(1);
+	}
+
+	if (picoxcell_trng_read_csr() & CSR_FAULT_MASK) {
+		dev_err(rng_dev, "fault detected, resetting TRNG\n");
+		picoxcell_trng_reset();
+		return -EIO;
+	}
+
+	if (i == PICO_TRNG_TIMEOUT)
+		return 0;
+
+	*(u32 *)buf = __raw_readl(rng_base + DATA_REG_OFFSET);
+	return sizeof(u32);
+}
+
+static struct hwrng picoxcell_trng = {
+	.name		= "picoxcell",
+	.read		= picoxcell_trng_read,
+};
+
+static int picoxcell_trng_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	if (!mem) {
+		dev_warn(&pdev->dev, "no memory resource\n");
+		return -ENOMEM;
+	}
+
+	if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
+				     "picoxcell_trng")) {
+		dev_warn(&pdev->dev, "unable to request io mem\n");
+		return -EBUSY;
+	}
+
+	rng_base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
+	if (!rng_base) {
+		dev_warn(&pdev->dev, "unable to remap io mem\n");
+		return -ENOMEM;
+	}
+
+	rng_clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(rng_clk)) {
+		dev_warn(&pdev->dev, "no clk\n");
+		return PTR_ERR(rng_clk);
+	}
+
+	ret = clk_enable(rng_clk);
+	if (ret) {
+		dev_warn(&pdev->dev, "unable to enable clk\n");
+		goto err_enable;
+	}
+
+	picoxcell_trng_start();
+	ret = hwrng_register(&picoxcell_trng);
+	if (ret)
+		goto err_register;
+
+	rng_dev = &pdev->dev;
+	dev_info(&pdev->dev, "pixoxcell random number generator active\n");
+
+	return 0;
+
+err_register:
+	clk_disable(rng_clk);
+err_enable:
+	clk_put(rng_clk);
+
+	return ret;
+}
+
+static int __devexit picoxcell_trng_remove(struct platform_device *pdev)
+{
+	hwrng_unregister(&picoxcell_trng);
+	clk_disable(rng_clk);
+	clk_put(rng_clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int picoxcell_trng_suspend(struct device *dev)
+{
+	clk_disable(rng_clk);
+
+	return 0;
+}
+
+static int picoxcell_trng_resume(struct device *dev)
+{
+	return clk_enable(rng_clk);
+}
+
+static const struct dev_pm_ops picoxcell_trng_pm_ops = {
+	.suspend	= picoxcell_trng_suspend,
+	.resume		= picoxcell_trng_resume,
+};
+#endif /* CONFIG_PM */
+
+static struct platform_driver picoxcell_trng_driver = {
+	.probe		= picoxcell_trng_probe,
+	.remove		= __devexit_p(picoxcell_trng_remove),
+	.driver		= {
+		.name	= "picoxcell-trng",
+		.owner	= THIS_MODULE,
+#ifdef CONFIG_PM
+		.pm	= &picoxcell_trng_pm_ops,
+#endif /* CONFIG_PM */
+	},
+};
+
+static int __init picoxcell_trng_init(void)
+{
+	return platform_driver_register(&picoxcell_trng_driver);
+}
+module_init(picoxcell_trng_init);
+
+static void __exit picoxcell_trng_exit(void)
+{
+	platform_driver_unregister(&picoxcell_trng_driver);
+}
+module_exit(picoxcell_trng_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jamie Iles");
+MODULE_DESCRIPTION("Picochip picoXcell TRNG driver");
-- 
1.7.3.4

Re: [PATCHv2] hwrng: add support for picoxcell TRNG

[Herbert Xu]

On Mon, Jan 17, 2011 at 10:23:30AM +0000, Jamie Iles wrote:
>
> Ok, that's a fair point!  Here's an updated version with a timeout.  
> I've also added in support for the fault detection which I previously 
> overlooked.

Patch applied.  Thanks!
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt