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80 lines
1.8 KiB
80 lines
1.8 KiB
/* |
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* Copyright (c) 2017 Intel Corporation |
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* |
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* SPDX-License-Identifier: Apache-2.0 |
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*/ |
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#include <zephyr/sys/atomic.h> |
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#include <zephyr/kernel.h> |
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#include <zephyr/drivers/entropy.h> |
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#include <string.h> |
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static const struct device *const entropy_dev = |
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DEVICE_DT_GET(DT_CHOSEN(zephyr_entropy)); |
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static int rand_get(uint8_t *dst, size_t outlen, bool csrand) |
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{ |
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uint32_t random_num; |
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int ret; |
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__ASSERT(device_is_ready(entropy_dev), "Entropy device %s not ready", |
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entropy_dev->name); |
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ret = entropy_get_entropy(entropy_dev, dst, outlen); |
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if (unlikely(ret < 0)) { |
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/* Don't try to fill the buffer in case of |
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* cryptographically secure random numbers, just |
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* propagate the driver error. |
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*/ |
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if (csrand) { |
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return ret; |
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} |
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/* Use system timer in case the entropy device couldn't deliver |
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* 32-bit of data. There's not much that can be done in this |
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* situation. An __ASSERT() isn't used here as the HWRNG might |
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* still be gathering entropy during early boot situations. |
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*/ |
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uint32_t len = 0; |
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uint32_t blocksize = 4; |
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while (len < outlen) { |
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size_t copylen = outlen - len; |
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if (copylen > blocksize) { |
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copylen = blocksize; |
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} |
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random_num = k_cycle_get_32(); |
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(void)memcpy(&(dst[len]), &random_num, copylen); |
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len += copylen; |
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} |
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} |
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return 0; |
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} |
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#if defined(CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR) |
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void z_impl_sys_rand_get(void *dst, size_t outlen) |
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{ |
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rand_get(dst, outlen, false); |
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} |
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#endif /* CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR */ |
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#if defined(CONFIG_HARDWARE_DEVICE_CS_GENERATOR) |
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int z_impl_sys_csrand_get(void *dst, size_t outlen) |
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{ |
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if (rand_get(dst, outlen, true) != 0) { |
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/* Is it the only error it should return ? entropy_sam |
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* can return -ETIMEDOUT for example |
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*/ |
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return -EIO; |
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} |
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return 0; |
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} |
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#endif /* CONFIG_HARDWARE_DEVICE_CS_GENERATOR */
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