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targets/TARGET_STM/trng_api.c@182:57724642e740, 2018-02-16 (annotated)

Committer:
AnnaBridge
Date:
Fri Feb 16 16:09:33 2018 +0000
Revision:
182:57724642e740
Parent:
178:d650f5d4c87a 
mbed-dev library. Release version 159.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 149:156823d33999 1 /*
<> 149:156823d33999 2 * Hardware entropy collector for the STM32 families
<> 149:156823d33999 3 *
<> 149:156823d33999 4 * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
<> 149:156823d33999 5 * SPDX-License-Identifier: Apache-2.0
<> 149:156823d33999 6 *
<> 149:156823d33999 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
<> 149:156823d33999 8 * not use this file except in compliance with the License.
<> 149:156823d33999 9 * You may obtain a copy of the License at
<> 149:156823d33999 10 *
<> 149:156823d33999 11 * http://www.apache.org/licenses/LICENSE-2.0
<> 149:156823d33999 12 *
<> 149:156823d33999 13 * Unless required by applicable law or agreed to in writing, software
<> 149:156823d33999 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
<> 149:156823d33999 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 149:156823d33999 16 * See the License for the specific language governing permissions and
<> 149:156823d33999 17 * limitations under the License.
<> 149:156823d33999 18 *
<> 149:156823d33999 19 */
<> 149:156823d33999 20
<> 149:156823d33999 21 #if defined(DEVICE_TRNG)
<> 149:156823d33999 22
<> 149:156823d33999 23 #include <stdlib.h>
<> 149:156823d33999 24 #include "cmsis.h"
<> 149:156823d33999 25 #include "trng_api.h"
AnnaBridge 178:d650f5d4c87a 26 #include "mbed_error.h"
AnnaBridge 178:d650f5d4c87a 27 #include "mbed_critical.h"
<> 149:156823d33999 28
AnnaBridge 178:d650f5d4c87a 29 static uint8_t users = 0;
<> 149:156823d33999 30
<> 149:156823d33999 31 void trng_init(trng_t *obj)
<> 149:156823d33999 32 {
AnnaBridge 178:d650f5d4c87a 33 uint32_t dummy;
AnnaBridge 178:d650f5d4c87a 34
AnnaBridge 178:d650f5d4c87a 35 /* We're only supporting a single user of RNG */
AnnaBridge 178:d650f5d4c87a 36 if (core_util_atomic_incr_u8(&users, 1) > 1 ) {
AnnaBridge 178:d650f5d4c87a 37 error("Only 1 RNG instance supported\r\n");
AnnaBridge 178:d650f5d4c87a 38 }
AnnaBridge 178:d650f5d4c87a 39
<> 149:156823d33999 40 #if defined(TARGET_STM32L4)
<> 149:156823d33999 41 RCC_PeriphCLKInitTypeDef PeriphClkInitStruct;
<> 149:156823d33999 42
<> 149:156823d33999 43 /*Select PLLQ output as RNG clock source */
<> 149:156823d33999 44 PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RNG;
<> 149:156823d33999 45 PeriphClkInitStruct.RngClockSelection = RCC_RNGCLKSOURCE_PLL;
<> 149:156823d33999 46 HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct);
<> 149:156823d33999 47 #endif
<> 149:156823d33999 48
<> 149:156823d33999 49 /* RNG Peripheral clock enable */
<> 149:156823d33999 50 __HAL_RCC_RNG_CLK_ENABLE();
<> 149:156823d33999 51
<> 149:156823d33999 52 /* Initialize RNG instance */
<> 149:156823d33999 53 obj->handle.Instance = RNG;
AnnaBridge 178:d650f5d4c87a 54 obj->handle.State = HAL_RNG_STATE_RESET;
AnnaBridge 178:d650f5d4c87a 55 obj->handle.Lock = HAL_UNLOCKED;
AnnaBridge 178:d650f5d4c87a 56
<> 149:156823d33999 57 HAL_RNG_Init(&obj->handle);
<> 149:156823d33999 58
<> 149:156823d33999 59 /* first random number generated after setting the RNGEN bit should not be used */
AnnaBridge 178:d650f5d4c87a 60 HAL_RNG_GenerateRandomNumber(&obj->handle, &dummy);
<> 149:156823d33999 61 }
<> 149:156823d33999 62
<> 149:156823d33999 63 void trng_free(trng_t *obj)
<> 149:156823d33999 64 {
<> 149:156823d33999 65 /*Disable the RNG peripheral */
<> 149:156823d33999 66 HAL_RNG_DeInit(&obj->handle);
<> 149:156823d33999 67 /* RNG Peripheral clock disable - assume we're the only users of RNG */
<> 149:156823d33999 68 __HAL_RCC_RNG_CLK_DISABLE();
AnnaBridge 178:d650f5d4c87a 69
AnnaBridge 178:d650f5d4c87a 70 users = 0;
<> 149:156823d33999 71 }
<> 149:156823d33999 72
<> 149:156823d33999 73 int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
<> 149:156823d33999 74 {
AnnaBridge 178:d650f5d4c87a 75 int ret = 0;
AnnaBridge 178:d650f5d4c87a 76 volatile uint8_t random[4];
AnnaBridge 178:d650f5d4c87a 77 *output_length = 0;
<> 149:156823d33999 78
<> 149:156823d33999 79 /* Get Random byte */
AnnaBridge 178:d650f5d4c87a 80 while ((*output_length < length) && (ret ==0)) {
AnnaBridge 178:d650f5d4c87a 81 if ( HAL_RNG_GenerateRandomNumber(&obj->handle, (uint32_t *)random ) != HAL_OK) {
AnnaBridge 178:d650f5d4c87a 82 ret = -1;
AnnaBridge 178:d650f5d4c87a 83 } else {
AnnaBridge 178:d650f5d4c87a 84 for (uint8_t i =0; (i < 4) && (*output_length < length) ; i++) {
AnnaBridge 178:d650f5d4c87a 85 *output++ = random[i];
AnnaBridge 178:d650f5d4c87a 86 *output_length += 1;
AnnaBridge 178:d650f5d4c87a 87 random[i] = 0;
AnnaBridge 178:d650f5d4c87a 88 }
AnnaBridge 178:d650f5d4c87a 89 }
<> 149:156823d33999 90 }
<> 149:156823d33999 91
<> 149:156823d33999 92 /* Just be extra sure that we didn't do it wrong */
<> 149:156823d33999 93 if( ( __HAL_RNG_GET_FLAG(&obj->handle, (RNG_FLAG_CECS | RNG_FLAG_SECS)) ) != 0 ) {
<> 149:156823d33999 94 ret = -1;
<> 149:156823d33999 95 }
<> 149:156823d33999 96
<> 149:156823d33999 97 return( ret );
<> 149:156823d33999 98 }
<> 149:156823d33999 99
<> 149:156823d33999 100 #endif