Lee Kai Xuan / mbed-os

mbed-os

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targets/TARGET_STM/trng_api.c@0:f269e3021894, 2016-10-23 (annotated)

Committer:
elessair
Date:
Sun Oct 23 15:10:02 2016 +0000
Revision:
0:f269e3021894
Initial commit

Who changed what in which revision?

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elessair 0:f269e3021894 1 /*
elessair 0:f269e3021894 2 * Hardware entropy collector for the STM32 families
elessair 0:f269e3021894 3 *
elessair 0:f269e3021894 4 * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
elessair 0:f269e3021894 5 * SPDX-License-Identifier: Apache-2.0
elessair 0:f269e3021894 6 *
elessair 0:f269e3021894 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
elessair 0:f269e3021894 8 * not use this file except in compliance with the License.
elessair 0:f269e3021894 9 * You may obtain a copy of the License at
elessair 0:f269e3021894 10 *
elessair 0:f269e3021894 11 * http://www.apache.org/licenses/LICENSE-2.0
elessair 0:f269e3021894 12 *
elessair 0:f269e3021894 13 * Unless required by applicable law or agreed to in writing, software
elessair 0:f269e3021894 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
elessair 0:f269e3021894 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
elessair 0:f269e3021894 16 * See the License for the specific language governing permissions and
elessair 0:f269e3021894 17 * limitations under the License.
elessair 0:f269e3021894 18 *
elessair 0:f269e3021894 19 */
elessair 0:f269e3021894 20
elessair 0:f269e3021894 21 #if defined(DEVICE_TRNG)
elessair 0:f269e3021894 22
elessair 0:f269e3021894 23 #include <stdlib.h>
elessair 0:f269e3021894 24 #include "cmsis.h"
elessair 0:f269e3021894 25 #include "trng_api.h"
elessair 0:f269e3021894 26
elessair 0:f269e3021894 27 /** trng_get_byte
elessair 0:f269e3021894 28 * @brief Get one byte of entropy from the RNG, assuming it is up and running.
elessair 0:f269e3021894 29 * @param obj TRNG obj
elessair 0:f269e3021894 30 * @param pointer to the hardware generated random byte.
elessair 0:f269e3021894 31 */
elessair 0:f269e3021894 32 static void trng_get_byte(trng_t *obj, unsigned char *byte )
elessair 0:f269e3021894 33 {
elessair 0:f269e3021894 34 *byte = (unsigned char)HAL_RNG_GetRandomNumber(&obj->handle);
elessair 0:f269e3021894 35 }
elessair 0:f269e3021894 36
elessair 0:f269e3021894 37 void trng_init(trng_t *obj)
elessair 0:f269e3021894 38 {
elessair 0:f269e3021894 39 #if defined(TARGET_STM32L4)
elessair 0:f269e3021894 40 RCC_PeriphCLKInitTypeDef PeriphClkInitStruct;
elessair 0:f269e3021894 41
elessair 0:f269e3021894 42 /*Select PLLQ output as RNG clock source */
elessair 0:f269e3021894 43 PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RNG;
elessair 0:f269e3021894 44 PeriphClkInitStruct.RngClockSelection = RCC_RNGCLKSOURCE_PLL;
elessair 0:f269e3021894 45 HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct);
elessair 0:f269e3021894 46 #endif
elessair 0:f269e3021894 47
elessair 0:f269e3021894 48 /* RNG Peripheral clock enable */
elessair 0:f269e3021894 49 __HAL_RCC_RNG_CLK_ENABLE();
elessair 0:f269e3021894 50
elessair 0:f269e3021894 51 /* Initialize RNG instance */
elessair 0:f269e3021894 52 obj->handle.Instance = RNG;
elessair 0:f269e3021894 53 HAL_RNG_Init(&obj->handle);
elessair 0:f269e3021894 54
elessair 0:f269e3021894 55 /* first random number generated after setting the RNGEN bit should not be used */
elessair 0:f269e3021894 56 HAL_RNG_GetRandomNumber(&obj->handle);
elessair 0:f269e3021894 57
elessair 0:f269e3021894 58 }
elessair 0:f269e3021894 59
elessair 0:f269e3021894 60 void trng_free(trng_t *obj)
elessair 0:f269e3021894 61 {
elessair 0:f269e3021894 62 /*Disable the RNG peripheral */
elessair 0:f269e3021894 63 HAL_RNG_DeInit(&obj->handle);
elessair 0:f269e3021894 64 /* RNG Peripheral clock disable - assume we're the only users of RNG */
elessair 0:f269e3021894 65 __HAL_RCC_RNG_CLK_DISABLE();
elessair 0:f269e3021894 66 }
elessair 0:f269e3021894 67
elessair 0:f269e3021894 68 int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
elessair 0:f269e3021894 69 {
elessair 0:f269e3021894 70 int ret;
elessair 0:f269e3021894 71
elessair 0:f269e3021894 72 /* Get Random byte */
elessair 0:f269e3021894 73 for( uint32_t i = 0; i < length; i++ ){
elessair 0:f269e3021894 74 trng_get_byte(obj, output + i );
elessair 0:f269e3021894 75 }
elessair 0:f269e3021894 76
elessair 0:f269e3021894 77 *output_length = length;
elessair 0:f269e3021894 78 /* Just be extra sure that we didn't do it wrong */
elessair 0:f269e3021894 79 if( ( __HAL_RNG_GET_FLAG(&obj->handle, (RNG_FLAG_CECS | RNG_FLAG_SECS)) ) != 0 ) {
elessair 0:f269e3021894 80 ret = -1;
elessair 0:f269e3021894 81 } else {
elessair 0:f269e3021894 82 ret = 0;
elessair 0:f269e3021894 83 }
elessair 0:f269e3021894 84
elessair 0:f269e3021894 85 return( ret );
elessair 0:f269e3021894 86 }
elessair 0:f269e3021894 87
elessair 0:f269e3021894 88 #endif