Subject: [PATCHv2] hw_random: add driver for atmel true hardware random number generator

From: [email-masked] (Nicolas Ferre)
Date: Fri, 07 Oct 2011 11:53:25 +0200

On 10/06/2011 07:56 PM, Peter Korsgaard :
> For the IP block on 9g45/9g46/9m10/9m11.
> 
> Signed-off-by: Peter Korsgaard <[email-masked]>

Thanks, I am delighted to see this driver!

Acked-by: Nicolas Ferre <[email-masked]>

Herbert,
I will handle the board specific part but should the driver part go
through the Crypto API tree?
Will you expect that I resend the patch with Jamie's and my signatures?

> ---
>  Changes since v1:
>  - Embed struct hwrng in struct atmel_trng as suggested by Jamie Iles.
> 
>  drivers/char/hw_random/Kconfig     |   13 +++
>  drivers/char/hw_random/Makefile    |    1 +
>  drivers/char/hw_random/atmel-rng.c |  158 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 172 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/char/hw_random/atmel-rng.c
> 
> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> index 1d2ebc7..e013587 100644
> --- a/drivers/char/hw_random/Kconfig
> +++ b/drivers/char/hw_random/Kconfig
> @@ -60,6 +60,19 @@ config HW_RANDOM_AMD
>  
>  	  If unsure, say Y.
>  
> +config HW_RANDOM_ATMEL
> +	tristate "Atmel Random Number Generator support"
> +	depends on HW_RANDOM && ARCH_AT91SAM9G45
> +	default HW_RANDOM
> +	---help---
> +	  This driver provides kernel-side support for the Random Number
> +	  Generator hardware found on Atmel AT91 devices.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called atmel-rng.
> +
> +	  If unsure, say Y.
> +
>  config HW_RANDOM_GEODE
>  	tristate "AMD Geode HW Random Number Generator support"
>  	depends on HW_RANDOM && X86_32 && PCI
> diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
> index c88f244..b2ff526 100644
> --- a/drivers/char/hw_random/Makefile
> +++ b/drivers/char/hw_random/Makefile
> @@ -7,6 +7,7 @@ rng-core-y := core.o
>  obj-$(CONFIG_HW_RANDOM_TIMERIOMEM) += timeriomem-rng.o
>  obj-$(CONFIG_HW_RANDOM_INTEL) += intel-rng.o
>  obj-$(CONFIG_HW_RANDOM_AMD) += amd-rng.o
> +obj-$(CONFIG_HW_RANDOM_ATMEL) += atmel-rng.o
>  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
> diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
> new file mode 100644
> index 0000000..241df2e
> --- /dev/null
> +++ b/drivers/char/hw_random/atmel-rng.c
> @@ -0,0 +1,158 @@
> +/*
> + * Copyright (c) 2011 Peter Korsgaard <[email-masked]>
> + *
> + * 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/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +#include <linux/hw_random.h>
> +#include <linux/platform_device.h>
> +
> +#define TRNG_CR		0x00
> +#define TRNG_ISR	0x1c
> +#define TRNG_ODATA	0x50
> +
> +#define TRNG_KEY	0x524e4700 /* RNG */
> +
> +struct atmel_trng {
> +	struct clk *clk;
> +	void __iomem *base;
> +	struct hwrng rng;
> +};
> +
> +static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
> +			   bool wait)
> +{
> +	struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
> +	u32 *data = buf;
> +
> +	/* data ready? */
> +	if (readl(trng->base + TRNG_ODATA) & 1) {
> +		*data = readl(trng->base + TRNG_ODATA);
> +		return 4;
> +	} else
> +		return 0;
> +}
> +
> +static int atmel_trng_probe(struct platform_device *pdev)
> +{
> +	struct atmel_trng *trng;
> +	struct resource *res;
> +	int ret;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -EINVAL;
> +
> +	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
> +	if (!trng)
> +		return -ENOMEM;
> +
> +	if (!devm_request_mem_region(&pdev->dev, res->start,
> +				     resource_size(res), pdev->name))
> +		return -EBUSY;
> +
> +	trng->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> +	if (!trng->base)
> +		return -EBUSY;
> +
> +	trng->clk = clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(trng->clk))
> +		return PTR_ERR(trng->clk);
> +
> +	ret = clk_enable(trng->clk);
> +	if (ret)
> +		goto err_enable;
> +
> +	writel(TRNG_KEY | 1, trng->base + TRNG_CR);
> +	trng->rng.name = pdev->name;
> +	trng->rng.read = atmel_trng_read;
> +
> +	ret = hwrng_register(&trng->rng);
> +	if (ret)
> +		goto err_register;
> +
> +	platform_set_drvdata(pdev, trng);
> +
> +	return 0;
> +
> +err_register:
> +	clk_disable(trng->clk);
> +err_enable:
> +	clk_put(trng->clk);
> +
> +	return ret;
> +}
> +
> +static int __devexit atmel_trng_remove(struct platform_device *pdev)
> +{
> +	struct atmel_trng *trng = platform_get_drvdata(pdev);
> +
> +	hwrng_unregister(&trng->rng);
> +
> +	writel(TRNG_KEY, trng->base + TRNG_CR);
> +	clk_disable(trng->clk);
> +	clk_put(trng->clk);
> +
> +	platform_set_drvdata(pdev, NULL);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int atmel_trng_suspend(struct device *dev)
> +{
> +	struct atmel_trng *trng = dev_get_drvdata(dev);
> +
> +	clk_disable(trng->clk);
> +
> +	return 0;
> +}
> +
> +static int atmel_trng_resume(struct device *dev)
> +{
> +	struct atmel_trng *trng = dev_get_drvdata(dev);
> +
> +	return clk_enable(trng->clk);
> +}
> +
> +static const struct dev_pm_ops atmel_trng_pm_ops = {
> +	.suspend	= atmel_trng_suspend,
> +	.resume		= atmel_trng_resume,
> +};
> +#endif /* CONFIG_PM */
> +
> +static struct platform_driver atmel_trng_driver = {
> +	.probe		= atmel_trng_probe,
> +	.remove		= __devexit_p(atmel_trng_remove),
> +	.driver		= {
> +		.name	= "atmel-trng",
> +		.owner	= THIS_MODULE,
> +#ifdef CONFIG_PM
> +		.pm	= &atmel_trng_pm_ops,
> +#endif /* CONFIG_PM */
> +	},
> +};
> +
> +static int __init atmel_trng_init(void)
> +{
> +	return platform_driver_register(&atmel_trng_driver);
> +}
> +module_init(atmel_trng_init);
> +
> +static void __exit atmel_trng_exit(void)
> +{
> +	platform_driver_unregister(&atmel_trng_driver);
> +}
> +module_exit(atmel_trng_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Peter Korsgaard <[email-masked]>");
> +MODULE_DESCRIPTION("Atmel true random number generator driver");

Best regards,
-- 
Nicolas Ferre