mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-14 06:35:12 +00:00
c25769fdda
Microwatt's hardware RNG is accessed using the DARN instruction. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/YMwXPHlV/ZleiQUY@thinks.paulus.ozlabs.org
48 lines
940 B
C
48 lines
940 B
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* Derived from arch/powerpc/platforms/powernv/rng.c, which is:
|
|
* Copyright 2013, Michael Ellerman, IBM Corporation.
|
|
*/
|
|
|
|
#define pr_fmt(fmt) "microwatt-rng: " fmt
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/smp.h>
|
|
#include <asm/archrandom.h>
|
|
#include <asm/cputable.h>
|
|
#include <asm/machdep.h>
|
|
|
|
#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
|
|
|
|
int microwatt_get_random_darn(unsigned long *v)
|
|
{
|
|
unsigned long val;
|
|
|
|
/* Using DARN with L=1 - 64-bit conditioned random number */
|
|
asm volatile(PPC_DARN(%0, 1) : "=r"(val));
|
|
|
|
if (val == DARN_ERR)
|
|
return 0;
|
|
|
|
*v = val;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static __init int rng_init(void)
|
|
{
|
|
unsigned long val;
|
|
int i;
|
|
|
|
for (i = 0; i < 10; i++) {
|
|
if (microwatt_get_random_darn(&val)) {
|
|
ppc_md.get_random_seed = microwatt_get_random_darn;
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
pr_warn("Unable to use DARN for get_random_seed()\n");
|
|
|
|
return -EIO;
|
|
}
|
|
machine_subsys_initcall(, rng_init);
|