powerpc: Implement arch_get_random_long/int() for powernv

Add the plumbing to implement arch_get_random_long/int(). It didn't seem
worth adding an extra ppc_md hook for int, so we reuse the one for long.

Add an implementation for powernv based on the hwrng found in power7+
systems. We whiten the output of the hwrng, and the result passes all
the dieharder tests.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Michael Ellerman 2013-10-11 14:07:57 +11:00 committed by Benjamin Herrenschmidt
parent f95dabef4c
commit a4da0d50b2
6 changed files with 163 additions and 1 deletions

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@ -1012,6 +1012,9 @@ config PHYSICAL_START
default "0x00000000"
endif
config ARCH_RANDOM
def_bool n
source "net/Kconfig"
source "drivers/Kconfig"

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@ -0,0 +1,32 @@
#ifndef _ASM_POWERPC_ARCHRANDOM_H
#define _ASM_POWERPC_ARCHRANDOM_H
#ifdef CONFIG_ARCH_RANDOM
#include <asm/machdep.h>
static inline int arch_get_random_long(unsigned long *v)
{
if (ppc_md.get_random_long)
return ppc_md.get_random_long(v);
return 0;
}
static inline int arch_get_random_int(unsigned int *v)
{
unsigned long val;
int rc;
rc = arch_get_random_long(&val);
if (rc)
*v = val;
return rc;
}
int powernv_get_random_long(unsigned long *v);
#endif /* CONFIG_ARCH_RANDOM */
#endif /* _ASM_POWERPC_ARCHRANDOM_H */

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@ -263,6 +263,10 @@ struct machdep_calls {
ssize_t (*cpu_probe)(const char *, size_t);
ssize_t (*cpu_release)(const char *, size_t);
#endif
#ifdef CONFIG_ARCH_RANDOM
int (*get_random_long)(unsigned long *v);
#endif
};
extern void e500_idle(void);

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@ -9,6 +9,7 @@ config PPC_POWERNV
select EPAPR_BOOT
select PPC_INDIRECT_PIO
select PPC_UDBG_16550
select ARCH_RANDOM
default y
config POWERNV_MSI

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@ -1,5 +1,5 @@
obj-y += setup.o opal-takeover.o opal-wrappers.o opal.o
obj-y += opal-rtc.o opal-nvram.o opal-lpc.o
obj-y += opal-rtc.o opal-nvram.o opal-lpc.o rng.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_PCI) += pci.o pci-p5ioc2.o pci-ioda.o

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@ -0,0 +1,122 @@
/*
* Copyright 2013, Michael Ellerman, IBM 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; either version
* 2 of the License, or (at your option) any later version.
*/
#define pr_fmt(fmt) "powernv-rng: " fmt
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/slab.h>
#include <asm/archrandom.h>
#include <asm/io.h>
#include <asm/machdep.h>
struct powernv_rng {
void __iomem *regs;
unsigned long mask;
};
static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
{
unsigned long parity;
/* Calculate the parity of the value */
asm ("popcntd %0,%1" : "=r" (parity) : "r" (val));
/* xor our value with the previous mask */
val ^= rng->mask;
/* update the mask based on the parity of this value */
rng->mask = (rng->mask << 1) | (parity & 1);
return val;
}
int powernv_get_random_long(unsigned long *v)
{
struct powernv_rng *rng;
rng = get_cpu_var(powernv_rng);
*v = rng_whiten(rng, in_be64(rng->regs));
put_cpu_var(rng);
return 1;
}
EXPORT_SYMBOL_GPL(powernv_get_random_long);
static __init void rng_init_per_cpu(struct powernv_rng *rng,
struct device_node *dn)
{
int chip_id, cpu;
chip_id = of_get_ibm_chip_id(dn);
if (chip_id == -1)
pr_warn("No ibm,chip-id found for %s.\n", dn->full_name);
for_each_possible_cpu(cpu) {
if (per_cpu(powernv_rng, cpu) == NULL ||
cpu_to_chip_id(cpu) == chip_id) {
per_cpu(powernv_rng, cpu) = rng;
}
}
}
static __init int rng_create(struct device_node *dn)
{
struct powernv_rng *rng;
unsigned long val;
rng = kzalloc(sizeof(*rng), GFP_KERNEL);
if (!rng)
return -ENOMEM;
rng->regs = of_iomap(dn, 0);
if (!rng->regs) {
kfree(rng);
return -ENXIO;
}
val = in_be64(rng->regs);
rng->mask = val;
rng_init_per_cpu(rng, dn);
pr_info_once("Registering arch random hook.\n");
ppc_md.get_random_long = powernv_get_random_long;
return 0;
}
static __init int rng_init(void)
{
struct device_node *dn;
int rc;
for_each_compatible_node(dn, NULL, "ibm,power-rng") {
rc = rng_create(dn);
if (rc) {
pr_err("Failed creating rng for %s (%d).\n",
dn->full_name, rc);
continue;
}
/* Create devices for hwrng driver */
of_platform_device_create(dn, NULL, NULL);
}
return 0;
}
subsys_initcall(rng_init);