127 lines
2.5 KiB
C
127 lines
2.5 KiB
C
/*
|
|
* 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_address.h>
|
|
#include <linux/of_platform.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/smp.h>
|
|
#include <asm/archrandom.h>
|
|
#include <asm/io.h>
|
|
#include <asm/prom.h>
|
|
#include <asm/machdep.h>
|
|
#include <asm/smp.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;
|
|
}
|
|
machine_subsys_initcall(powernv, rng_init);
|