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Commit 8c4196a2 authored by Lubomir Rintel's avatar Lubomir Rintel Committed by Herbert Xu
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hwrng: bcm2835 - Add Broadcom BCM2835 RNG driver 



This adds a driver for random number generator present on Broadcom BCM2835 SoC,
used in Raspberry Pi and Roku 2 devices.

Signed-off-by: default avatarDom Cobley <popcornmix@gmail.com>
Signed-off-by: default avatarLubomir Rintel <lkundrak@v3.sk>
Tested-by: default avatarStephen Warren <swarren@wwwdotorg.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: linux-rpi-kernel@lists.infradead.org
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 96aef9a8

Documentation/devicetree/bindings/rng/brcm,bcm2835.txt

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BCM2835 Random number generator



Required properties:



- compatible : should be "brcm,bcm2835-rng"

- reg : Specifies base physical address and size of the registers.



Example:



rng {

        compatible = "brcm,bcm2835-rng";

        reg = <0x7e104000 0x10>;

};

drivers/char/hw_random/Kconfig

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@@ -86,6 +86,18 @@ config HW_RANDOM_BCM63XX 


	  If unusure, say Y.



config HW_RANDOM_BCM2835

	tristate "Broadcom BCM2835 Random Number Generator support"

	depends on HW_RANDOM && ARCH_BCM2835

	default HW_RANDOM

	---help---

	  This driver provides kernel-side support for the Random Number

	  Generator hardware found on the Broadcom BCM2835 SoCs.



	  To compile this driver as a module, choose M here: the

	  module will be called bcm2835-rng



	  If unsure, say Y.



config HW_RANDOM_GEODE

	tristate "AMD Geode HW Random Number Generator support"

drivers/char/hw_random/Makefile

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@@ -26,3 +26,4 @@ obj-$(CONFIG_HW_RANDOM_PPC4XX) += ppc4xx-rng.o 
obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o

obj-$(CONFIG_HW_RANDOM_EXYNOS)	+= exynos-rng.o

obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o

obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o

drivers/char/hw_random/bcm2835-rng.c

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/**

 * Copyright (c) 2010-2012 Broadcom. All rights reserved.

 * Copyright (c) 2013 Lubomir Rintel

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License ("GPL")

 * version 2, as published by the Free Software Foundation.

 */



#include <linux/hw_random.h>

#include <linux/init.h>

#include <linux/io.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/of_address.h>

#include <linux/of_platform.h>

#include <linux/platform_device.h>

#include <linux/printk.h>



#define RNG_CTRL	0x0

#define RNG_STATUS	0x4

#define RNG_DATA	0x8



/* enable rng */

#define RNG_RBGEN	0x1



/* the initial numbers generated are "less random" so will be discarded */

#define RNG_WARMUP_COUNT 0x40000



static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,

			       bool wait)

{

	void __iomem *rng_base = (void __iomem *)rng->priv;



	while ((__raw_readl(rng_base + RNG_STATUS) >> 24) == 0) {

		if (!wait)

			return 0;

		cpu_relax();

	}



	*(u32 *)buf = __raw_readl(rng_base + RNG_DATA);

	return sizeof(u32);

}



static struct hwrng bcm2835_rng_ops = {

	.name	= "bcm2835",

	.read	= bcm2835_rng_read,

};



static int bcm2835_rng_probe(struct platform_device *pdev)

{

	struct device *dev = &pdev->dev;

	struct device_node *np = dev->of_node;

	void __iomem *rng_base;

	int err;



	/* map peripheral */

	rng_base = of_iomap(np, 0);

	if (!rng_base) {

		dev_err(dev, "failed to remap rng regs");

		return -ENODEV;

	}

	bcm2835_rng_ops.priv = (unsigned long)rng_base;



	/* register driver */

	err = hwrng_register(&bcm2835_rng_ops);

	if (err) {

		dev_err(dev, "hwrng registration failed\n");

		iounmap(rng_base);

	} else {

		dev_info(dev, "hwrng registered\n");



		/* set warm-up count & enable */

		__raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS);

		__raw_writel(RNG_RBGEN, rng_base + RNG_CTRL);

	}

	return err;

}



static int bcm2835_rng_remove(struct platform_device *pdev)

{

	void __iomem *rng_base = (void __iomem *)bcm2835_rng_ops.priv;



	/* disable rng hardware */

	__raw_writel(0, rng_base + RNG_CTRL);



	/* unregister driver */

	hwrng_unregister(&bcm2835_rng_ops);

	iounmap(rng_base);



	return 0;

}



static const struct of_device_id bcm2835_rng_of_match[] = {

	{ .compatible = "brcm,bcm2835-rng", },

	{},

};

MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match);



static struct platform_driver bcm2835_rng_driver = {

	.driver = {

		.name = "bcm2835-rng",

		.owner = THIS_MODULE,

		.of_match_table = bcm2835_rng_of_match,

	},

	.probe		= bcm2835_rng_probe,

	.remove		= bcm2835_rng_remove,

};

module_platform_driver(bcm2835_rng_driver);



MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");

MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver");

MODULE_LICENSE("GPLv2");