| /* |
| * Copyright (c) 2016 ARM Limited. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| * Licensed under the Apache License, Version 2.0 (the License); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include <drivers/rand32.h> |
| #include <drivers/system_timer.h> |
| #include <misc/sys_log.h> |
| |
| #include "fsl_rnga.h" |
| |
| |
| void sys_rand32_init(void) |
| { |
| uint32_t seed = sys_cycle_get_32(); |
| |
| 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); |
| } |
| |
| uint32_t sys_rand32_get(void) |
| { |
| uint32_t random; |
| uint32_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 we deliberately only use 1 bit per 32 bit |
| * word read. |
| */ |
| for (i = 0; i < 32; i++) { |
| status_t status; |
| |
| status = RNGA_GetRandomData(RNG, &random, sizeof(random)); |
| __ASSERT(!status, "RNGA_GetRandomData failed"); |
| if (status) { |
| SYS_LOG_ERR("RNGA_GetRandomData failed with %d", |
| status); |
| } |
| output <<= 1; |
| output |= random & 1; |
| } |
| RNGA_SetMode(RNG, kRNGA_ModeSleep); |
| |
| return output; |
| } |