| /* |
| * Copyright (c) 2017 Intel Corporation |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| #include <sys/atomic.h> |
| #include <kernel.h> |
| #include <drivers/entropy.h> |
| #include <string.h> |
| |
| static const struct device *entropy_driver; |
| |
| #if defined(CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR) |
| uint32_t z_impl_sys_rand32_get(void) |
| { |
| const struct device *dev = entropy_driver; |
| uint32_t random_num; |
| int ret; |
| |
| if (unlikely(!dev)) { |
| /* Only one entropy device exists, so this is safe even |
| * if the whole operation isn't atomic. |
| */ |
| dev = device_get_binding(DT_CHOSEN_ZEPHYR_ENTROPY_LABEL); |
| __ASSERT((dev != NULL), |
| "Device driver for %s (DT_CHOSEN_ZEPHYR_ENTROPY_LABEL) not found. " |
| "Check your build configuration!", |
| DT_CHOSEN_ZEPHYR_ENTROPY_LABEL); |
| entropy_driver = dev; |
| } |
| |
| ret = entropy_get_entropy(dev, (uint8_t *)&random_num, |
| sizeof(random_num)); |
| if (unlikely(ret < 0)) { |
| /* Use system timer in case the entropy device couldn't deliver |
| * 32-bit of data. There's not much that can be done in this |
| * situation. An __ASSERT() isn't used here as the HWRNG might |
| * still be gathering entropy during early boot situations. |
| */ |
| |
| random_num = k_cycle_get_32(); |
| } |
| |
| return random_num; |
| } |
| #endif /* CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR */ |
| |
| static int rand_get(uint8_t *dst, size_t outlen, bool csrand) |
| { |
| const struct device *dev = entropy_driver; |
| uint32_t random_num; |
| int ret; |
| |
| if (unlikely(!dev)) { |
| /* Only one entropy device exists, so this is safe even |
| * if the whole operation isn't atomic. |
| */ |
| dev = device_get_binding(DT_CHOSEN_ZEPHYR_ENTROPY_LABEL); |
| __ASSERT((dev != NULL), |
| "Device driver for %s (DT_CHOSEN_ZEPHYR_ENTROPY_LABEL) not found. " |
| "Check your build configuration!", |
| DT_CHOSEN_ZEPHYR_ENTROPY_LABEL); |
| entropy_driver = dev; |
| } |
| |
| ret = entropy_get_entropy(dev, dst, outlen); |
| |
| if (unlikely(ret < 0)) { |
| /* Don't try to fill the buffer in case of |
| * cryptographically secure random numbers, just |
| * propagate the driver error. |
| */ |
| if (csrand) { |
| return ret; |
| } |
| |
| /* Use system timer in case the entropy device couldn't deliver |
| * 32-bit of data. There's not much that can be done in this |
| * situation. An __ASSERT() isn't used here as the HWRNG might |
| * still be gathering entropy during early boot situations. |
| */ |
| |
| uint32_t len = 0; |
| uint32_t blocksize = 4; |
| |
| while (len < outlen) { |
| size_t copylen = outlen - len; |
| |
| if (copylen > blocksize) { |
| copylen = blocksize; |
| } |
| |
| random_num = k_cycle_get_32(); |
| (void)memcpy(&(dst[len]), &random_num, copylen); |
| len += copylen; |
| } |
| } |
| |
| return 0; |
| } |
| |
| #if defined(CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR) |
| void z_impl_sys_rand_get(void *dst, size_t outlen) |
| { |
| rand_get(dst, outlen, false); |
| } |
| #endif /* CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR */ |
| |
| #if defined(CONFIG_HARDWARE_DEVICE_CS_GENERATOR) |
| |
| int z_impl_sys_csrand_get(void *dst, size_t outlen) |
| { |
| if (rand_get(dst, outlen, true) != 0) { |
| /* Is it the only error it should return ? entropy_sam |
| * can return -ETIMEDOUT for example |
| */ |
| return -EIO; |
| } |
| |
| return 0; |
| } |
| |
| #endif /* CONFIG_HARDWARE_DEVICE_CS_GENERATOR */ |