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Diff: targets/TARGET_STM/trng_api.c
- Revision:
- 149:156823d33999
- Child:
- 178:d650f5d4c87a
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/targets/TARGET_STM/trng_api.c Fri Oct 28 11:17:30 2016 +0100 @@ -0,0 +1,88 @@ +/* + * Hardware entropy collector for the STM32 families + * + * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved + * 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. + * + */ + +#if defined(DEVICE_TRNG) + +#include <stdlib.h> +#include "cmsis.h" +#include "trng_api.h" + +/** trng_get_byte + * @brief Get one byte of entropy from the RNG, assuming it is up and running. + * @param obj TRNG obj + * @param pointer to the hardware generated random byte. + */ +static void trng_get_byte(trng_t *obj, unsigned char *byte ) +{ + *byte = (unsigned char)HAL_RNG_GetRandomNumber(&obj->handle); +} + +void trng_init(trng_t *obj) +{ +#if defined(TARGET_STM32L4) + RCC_PeriphCLKInitTypeDef PeriphClkInitStruct; + + /*Select PLLQ output as RNG clock source */ + PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RNG; + PeriphClkInitStruct.RngClockSelection = RCC_RNGCLKSOURCE_PLL; + HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct); +#endif + + /* RNG Peripheral clock enable */ + __HAL_RCC_RNG_CLK_ENABLE(); + + /* Initialize RNG instance */ + obj->handle.Instance = RNG; + HAL_RNG_Init(&obj->handle); + + /* first random number generated after setting the RNGEN bit should not be used */ + HAL_RNG_GetRandomNumber(&obj->handle); + +} + +void trng_free(trng_t *obj) +{ + /*Disable the RNG peripheral */ + HAL_RNG_DeInit(&obj->handle); + /* RNG Peripheral clock disable - assume we're the only users of RNG */ + __HAL_RCC_RNG_CLK_DISABLE(); +} + +int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length) +{ + int ret; + + /* Get Random byte */ + for( uint32_t i = 0; i < length; i++ ){ + trng_get_byte(obj, output + i ); + } + + *output_length = length; + /* Just be extra sure that we didn't do it wrong */ + if( ( __HAL_RNG_GET_FLAG(&obj->handle, (RNG_FLAG_CECS | RNG_FLAG_SECS)) ) != 0 ) { + ret = -1; + } else { + ret = 0; + } + + return( ret ); +} + +#endif