Commit 66548e40 authored by Michael Ellerman's avatar Michael Ellerman Committed by Benjamin Herrenschmidt

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
...@@ -290,6 +290,19 @@ config HW_RANDOM_PSERIES ...@@ -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
......
...@@ -24,6 +24,7 @@ obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o ...@@ -24,6 +24,7 @@ obj-$(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
/*
* 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");
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