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48 lines
940 B
48 lines
940 B
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Derived from arch/powerpc/platforms/powernv/rng.c, which is: |
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* Copyright 2013, Michael Ellerman, IBM Corporation. |
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*/ |
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#define pr_fmt(fmt) "microwatt-rng: " fmt |
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#include <linux/kernel.h> |
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#include <linux/smp.h> |
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#include <asm/archrandom.h> |
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#include <asm/cputable.h> |
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#include <asm/machdep.h> |
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#define DARN_ERR 0xFFFFFFFFFFFFFFFFul |
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int microwatt_get_random_darn(unsigned long *v) |
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{ |
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unsigned long val; |
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/* Using DARN with L=1 - 64-bit conditioned random number */ |
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asm volatile(PPC_DARN(%0, 1) : "=r"(val)); |
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if (val == DARN_ERR) |
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return 0; |
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*v = val; |
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return 1; |
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} |
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static __init int rng_init(void) |
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{ |
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unsigned long val; |
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int i; |
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for (i = 0; i < 10; i++) { |
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if (microwatt_get_random_darn(&val)) { |
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ppc_md.get_random_seed = microwatt_get_random_darn; |
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return 0; |
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} |
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} |
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pr_warn("Unable to use DARN for get_random_seed()\n"); |
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return -EIO; |
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} |
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machine_subsys_initcall(, rng_init);
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