| /* |
| * Copyright (c) 2016 ARM Limited. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| #include <device.h> |
| #include <entropy.h> |
| #include <random/rand32.h> |
| #include <init.h> |
| |
| #include "fsl_rnga.h" |
| |
| static u8_t entropy_mcux_rnga_get_uint8(void) |
| { |
| u32_t random; |
| u8_t output = 0; |
| int i; |
| |
| RNGA_SetMode(RNG, kRNGA_ModeNormal); |
| /* The Reference manual states that back to back reads from |
| * the RNGA deliver one or two bits of entropy per 32-bit |
| * word, therefore to deliver 8 bits of entropy we need |
| * between 4 and 8 samples. Conservatively, we take 8. |
| */ |
| for (i = 0; i < 8; i++) { |
| status_t status; |
| |
| status = RNGA_GetRandomData(RNG, &random, sizeof(random)); |
| __ASSERT_NO_MSG(!status); |
| output ^= random; |
| } |
| |
| RNGA_SetMode(RNG, kRNGA_ModeSleep); |
| |
| return output; |
| } |
| |
| static int entropy_mcux_rnga_get_entropy(struct device *dev, u8_t *buffer, |
| u16_t length) |
| { |
| int i; |
| |
| ARG_UNUSED(dev); |
| |
| for (i = 0; i < length; i++) { |
| buffer[i] = entropy_mcux_rnga_get_uint8(); |
| } |
| |
| return 0; |
| } |
| |
| static const struct entropy_driver_api entropy_mcux_rnga_api_funcs = { |
| .get_entropy = entropy_mcux_rnga_get_entropy |
| }; |
| |
| static int entropy_mcux_rnga_init(struct device *); |
| |
| DEVICE_AND_API_INIT(entropy_mcux_rnga, CONFIG_ENTROPY_NAME, |
| entropy_mcux_rnga_init, NULL, NULL, |
| PRE_KERNEL_2, CONFIG_KERNEL_INIT_PRIORITY_DEVICE, |
| &entropy_mcux_rnga_api_funcs); |
| |
| static int entropy_mcux_rnga_init(struct device *dev) |
| { |
| u32_t seed = k_cycle_get_32(); |
| |
| ARG_UNUSED(dev); |
| |
| RNGA_Init(RNG); |
| |
| /* The range of seed values acquired by this method is likely |
| * to be relatively small. The RNGA hardware uses two free |
| * running oscillators to add entropy to the seed value, we |
| * take care below to ensure the read rate is lower than the |
| * rate at which the hardware can add entropy. |
| */ |
| RNGA_Seed(RNG, seed); |
| RNGA_SetMode(RNG, kRNGA_ModeSleep); |
| return 0; |
| } |