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Commit 66548e40 authored by Michael Ellerman's avatar Michael Ellerman Committed by Benjamin Herrenschmidt
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hwrng: Add a driver for the hwrng found in power7+ systems 



Add a driver for the hwrng found in power7+ systems, based on the
existing code for the arch_get_random_long() hook.

We only register a single instance of the driver, not one per device,
because we use the existing per_cpu array of devices in the arch code.
This means we always read from the "closest" device, avoiding inter-chip
memory traffic.

Signed-off-by: default avatarGuo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent a4da0d50

drivers/char/hw_random/Kconfig

+13 −0
Original line number Original line Diff line number Diff line
@@ -290,6 +290,19 @@ config HW_RANDOM_PSERIES 




	  If unsure, say Y.

	  If unsure, say Y.





config HW_RANDOM_POWERNV

	tristate "PowerNV Random Number Generator support"

	depends on HW_RANDOM && PPC_POWERNV

	default HW_RANDOM

	---help---

	  This is the driver for Random Number Generator hardware found

	  in POWER7+ and above machines for PowerNV platform.



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

	  module will be called powernv-rng.



	  If unsure, say Y.



config HW_RANDOM_EXYNOS

config HW_RANDOM_EXYNOS

	tristate "EXYNOS HW random number generator support"

	tristate "EXYNOS HW random number generator support"

	depends on HW_RANDOM && HAS_IOMEM && HAVE_CLK

	depends on HW_RANDOM && HAS_IOMEM && HAVE_CLK

drivers/char/hw_random/Makefile

+1 −0
Original line number Original line Diff line number Diff line
@@ -24,6 +24,7 @@ obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o 
obj-$(CONFIG_HW_RANDOM_PICOXCELL) += picoxcell-rng.o

obj-$(CONFIG_HW_RANDOM_PICOXCELL) += picoxcell-rng.o

obj-$(CONFIG_HW_RANDOM_PPC4XX) += ppc4xx-rng.o

obj-$(CONFIG_HW_RANDOM_PPC4XX) += ppc4xx-rng.o

obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o

obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o

obj-$(CONFIG_HW_RANDOM_POWERNV) += powernv-rng.o

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

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

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

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

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

drivers/char/hw_random/powernv-rng.c

0 → 100644
+81 −0
Original line number Original line Diff line number Diff line 
/*

 * Copyright 2013 Michael Ellerman, Guo Chao, IBM Corp.

 *

 * 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; either version

 * 2 of the License, or (at your option) any later version.

 */



#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt



#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/platform_device.h>

#include <linux/random.h>

#include <linux/hw_random.h>



static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)

{

	unsigned long *buf;

	int i, len;



	/* We rely on rng_buffer_size() being >= sizeof(unsigned long) */

	len = max / sizeof(unsigned long);



	buf = (unsigned long *)data;



	for (i = 0; i < len; i++)

		powernv_get_random_long(buf++);



	return len * sizeof(unsigned long);

}



static struct hwrng powernv_hwrng = {

	.name = "powernv-rng",

	.read = powernv_rng_read,

};



static int powernv_rng_remove(struct platform_device *pdev)

{

	hwrng_unregister(&powernv_hwrng);



	return 0;

}



static int powernv_rng_probe(struct platform_device *pdev)

{

	int rc;



	rc = hwrng_register(&powernv_hwrng);

	if (rc) {

		/* We only register one device, ignore any others */

		if (rc == -EEXIST)

			rc = -ENODEV;



		return rc;

	}



	pr_info("Registered powernv hwrng.\n");



	return 0;

}



static struct of_device_id powernv_rng_match[] = {

	{ .compatible	= "ibm,power-rng",},

	{},

};

MODULE_DEVICE_TABLE(of, powernv_rng_match);



static struct platform_driver powernv_rng_driver = {

	.driver = {

		.name = "powernv_rng",

		.of_match_table = powernv_rng_match,

	},

	.probe	= powernv_rng_probe,

	.remove = powernv_rng_remove,

};

module_platform_driver(powernv_rng_driver);



MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("Bare metal HWRNG driver for POWER7+ and above");