Commit c83d45d5 authored by Scott Branden's avatar Scott Branden Committed by Herbert Xu
Browse files

hwrng: iproc-rng200 - Add Broadcom IPROC RNG driver 



This adds a driver for random number generator present on Broadcom
IPROC devices.

Reviewed-by: default avatarRay Jui <rjui@broadcom.com>
Signed-off-by: default avatarScott Branden <sbranden@broadcom.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 259d317f

drivers/char/hw_random/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -101,6 +101,19 @@ config HW_RANDOM_BCM2835 


	  If unsure, say Y.



config HW_RANDOM_IPROC_RNG200

	tristate "Broadcom iProc RNG200 support"

	depends on ARCH_BCM_IPROC

	default HW_RANDOM

	---help---

	  This driver provides kernel-side support for the RNG200

	  hardware found on the Broadcom iProc SoCs.



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

	  module will be called iproc-rng200



	  If unsure, say Y.



config HW_RANDOM_GEODE

	tristate "AMD Geode HW Random Number Generator support"

	depends on X86_32 && PCI

drivers/char/hw_random/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -28,5 +28,6 @@ obj-$(CONFIG_HW_RANDOM_POWERNV) += powernv-rng.o 
obj-$(CONFIG_HW_RANDOM_EXYNOS)	+= exynos-rng.o

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

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

obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o

obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o

obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o

drivers/char/hw_random/iproc-rng200.c

0 → 100644
+254 −0
Original line number Diff line number Diff line 
/*

* Copyright (C) 2015 Broadcom Corporation

*

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

* modify it under the terms of the GNU General Public License as

* published by the Free Software Foundation version 2.

*

* This program is distributed "as is" WITHOUT ANY WARRANTY of any

* kind, whether express or implied; without even the implied warranty

* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

* GNU General Public License for more details.

*/

/*

 * DESCRIPTION: The Broadcom iProc RNG200 Driver

 */



#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/delay.h>



/* Registers */

#define RNG_CTRL_OFFSET					0x00

#define RNG_CTRL_RNG_RBGEN_MASK				0x00001FFF

#define RNG_CTRL_RNG_RBGEN_ENABLE			0x00000001

#define RNG_CTRL_RNG_RBGEN_DISABLE			0x00000000



#define RNG_SOFT_RESET_OFFSET				0x04

#define RNG_SOFT_RESET					0x00000001



#define RBG_SOFT_RESET_OFFSET				0x08

#define RBG_SOFT_RESET					0x00000001



#define RNG_INT_STATUS_OFFSET				0x18

#define RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK	0x80000000

#define RNG_INT_STATUS_STARTUP_TRANSITIONS_MET_IRQ_MASK	0x00020000

#define RNG_INT_STATUS_NIST_FAIL_IRQ_MASK		0x00000020

#define RNG_INT_STATUS_TOTAL_BITS_COUNT_IRQ_MASK	0x00000001



#define RNG_FIFO_DATA_OFFSET				0x20



#define RNG_FIFO_COUNT_OFFSET				0x24

#define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK		0x000000FF



struct iproc_rng200_dev {

	void __iomem			*base;

};



static void iproc_rng200_restart(void __iomem *rng_base)

{

	uint32_t val;



	/* Disable RBG */

	val = ioread32(rng_base + RNG_CTRL_OFFSET);

	val &= ~RNG_CTRL_RNG_RBGEN_MASK;

	val |= RNG_CTRL_RNG_RBGEN_DISABLE;

	iowrite32(val, rng_base + RNG_CTRL_OFFSET);



	/* Clear all interrupt status */

	iowrite32(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET);



	/* Reset RNG and RBG */

	val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);

	val |= RBG_SOFT_RESET;

	iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);



	val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);

	val |= RNG_SOFT_RESET;

	iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);



	val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);

	val &= ~RNG_SOFT_RESET;

	iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);



	val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);

	val &= ~RBG_SOFT_RESET;

	iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);



	/* Enable RBG */

	val = ioread32(rng_base + RNG_CTRL_OFFSET);

	val &= ~RNG_CTRL_RNG_RBGEN_MASK;

	val |= RNG_CTRL_RNG_RBGEN_ENABLE;

	iowrite32(val, rng_base + RNG_CTRL_OFFSET);

}



static int iproc_rng200_read(struct hwrng *rng, void *buf, size_t max,

			       bool wait)

{

	uint32_t status;

	uint32_t num_remaining = max;

	struct iproc_rng200_dev *priv = (struct iproc_rng200_dev *)rng->priv;



	#define MAX_RESETS_PER_READ	1

	uint32_t num_resets = 0;



	#define MAX_IDLE_TIME	(1 * HZ)

	unsigned long idle_endtime = jiffies + MAX_IDLE_TIME;



	while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) {



		/* Is RNG sane? If not, reset it. */

		status = ioread32(priv->base + RNG_INT_STATUS_OFFSET);

		if ((status & (RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK |

			RNG_INT_STATUS_NIST_FAIL_IRQ_MASK)) != 0) {



			if (num_resets >= MAX_RESETS_PER_READ)

				return max - num_remaining;



			iproc_rng200_restart(priv->base);

			num_resets++;

		}



		/* Are there any random numbers available? */

		if ((ioread32(priv->base + RNG_FIFO_COUNT_OFFSET) &

				RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {



			if (num_remaining >= sizeof(uint32_t)) {

				/* Buffer has room to store entire word */

				*(uint32_t *)buf = ioread32(priv->base +

							RNG_FIFO_DATA_OFFSET);

				buf += sizeof(uint32_t);

				num_remaining -= sizeof(uint32_t);

			} else {

				/* Buffer can only store partial word */

				uint32_t rnd_number = ioread32(priv->base +

							RNG_FIFO_DATA_OFFSET);

				memcpy(buf, &rnd_number, num_remaining);

				buf += num_remaining;

				num_remaining = 0;

			}



			/* Reset the IDLE timeout */

			idle_endtime = jiffies + MAX_IDLE_TIME;

		} else {

			if (!wait)

				/* Cannot wait, return immediately */

				return max - num_remaining;



			/* Can wait, give others chance to run */

			usleep_range(min(num_remaining * 10, 500U), 500);

		}

	}



	return max - num_remaining;

}



static int iproc_rng200_init(struct hwrng *rng)

{

	uint32_t val;

	struct iproc_rng200_dev *priv;



	priv = (struct iproc_rng200_dev *)rng->priv;



	/* Setup RNG. */

	val = ioread32(priv->base + RNG_CTRL_OFFSET);

	val &= ~RNG_CTRL_RNG_RBGEN_MASK;

	val |= RNG_CTRL_RNG_RBGEN_ENABLE;

	iowrite32(val, priv->base + RNG_CTRL_OFFSET);



	return 0;

}



static void iproc_rng200_cleanup(struct hwrng *rng)

{

	uint32_t val;

	struct iproc_rng200_dev *priv;



	priv = (struct iproc_rng200_dev *)rng->priv;



	/* Disable RNG hardware */

	val = ioread32(priv->base + RNG_CTRL_OFFSET);

	val &= ~RNG_CTRL_RNG_RBGEN_MASK;

	val |= RNG_CTRL_RNG_RBGEN_DISABLE;

	iowrite32(val, priv->base + RNG_CTRL_OFFSET);

}



static struct hwrng iproc_rng200_ops = {

	.name		= "iproc-rng200",

	.read		= iproc_rng200_read,

	.init		= iproc_rng200_init,

	.cleanup	= iproc_rng200_cleanup,

};



static int iproc_rng200_probe(struct platform_device *pdev)

{

	struct iproc_rng200_dev *priv;

	struct resource *res;

	struct device *dev = &pdev->dev;

	int ret;



	priv = devm_kzalloc(dev, sizeof(struct iproc_rng200_dev), GFP_KERNEL);

	if (!priv)

		return -ENOMEM;



	iproc_rng200_ops.priv = (unsigned long)priv;

	platform_set_drvdata(pdev, priv);



	/* Map peripheral */

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (!res) {

		dev_err(dev, "failed to get rng resources\n");

		return -EINVAL;

	}



	priv->base = devm_ioremap_resource(dev, res);

	if (IS_ERR(priv->base)) {

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

		return PTR_ERR(priv->base);

	}



	/* Register driver */

	ret = hwrng_register(&iproc_rng200_ops);

	if (ret) {

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

		return ret;

	}



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



	return 0;

}



static int iproc_rng200_remove(struct platform_device *pdev)

{

	/* Unregister driver */

	hwrng_unregister(&iproc_rng200_ops);



	return 0;

}



static const struct of_device_id iproc_rng200_of_match[] = {

	{ .compatible = "brcm,iproc-rng200", },

	{},

};

MODULE_DEVICE_TABLE(of, iproc_rng200_of_match);



static struct platform_driver iproc_rng200_driver = {

	.driver = {

		.name		= "iproc-rng200",

		.of_match_table = iproc_rng200_of_match,

	},

	.probe		= iproc_rng200_probe,

	.remove		= iproc_rng200_remove,

};

module_platform_driver(iproc_rng200_driver);



MODULE_AUTHOR("Broadcom");

MODULE_DESCRIPTION("iProc RNG200 Random Number Generator driver");

MODULE_LICENSE("GPL v2");