mirror of
https://github.com/espressif/openthread.git
synced 2026-07-09 22:00:19 +00:00
Jeffrey Hayes
110 lines
3.4 KiB
C
110 lines
3.4 KiB
C
/*
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* Copyright (c) 2017, The OpenThread Authors.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the copyright holder nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* @file
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* This file implements the OpenThread platform abstraction for random number generator.
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*
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*/
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#include <openthread/platform/random.h>
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#include "utils/code_utils.h"
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#include "em_adc.h"
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#include "em_cmu.h"
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enum
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{
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EFR32_ADC_REF_CLOCK = 7000000,
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};
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void efr32RandomInit(void)
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{
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/* Enable ADC Clock */
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CMU_ClockEnable(cmuClock_ADC0, true);
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ADC_Init_TypeDef init = ADC_INIT_DEFAULT;
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ADC_InitSingle_TypeDef singleInit = ADC_INITSINGLE_DEFAULT;
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/* Initialize the ADC with the required values */
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init.timebase = ADC_TimebaseCalc(0);
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init.prescale = ADC_PrescaleCalc(EFR32_ADC_REF_CLOCK, 0);
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ADC_Init(ADC0, &init);
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/* Initialize for single conversion specific to RNG */
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singleInit.reference = adcRefVEntropy;
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singleInit.diff = true;
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singleInit.posSel = adcPosSelVSS;
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singleInit.negSel = adcNegSelVSS;
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ADC_InitSingle(ADC0, &singleInit);
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/* Set VINATT to maximum value and clear FIFO */
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ADC0->SINGLECTRLX |= _ADC_SINGLECTRLX_VINATT_MASK;
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ADC0->SINGLEFIFOCLEAR = ADC_SINGLEFIFOCLEAR_SINGLEFIFOCLEAR;
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}
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uint32_t otPlatRandomGet(void)
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{
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uint8_t tmp;
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uint32_t random = 0;
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for (int i = 0; i < 4; i++)
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{
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tmp = 0;
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for (int j = 0; j < 3; j++)
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{
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ADC_Start(ADC0, adcStartSingle);
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while ((ADC0->IF & ADC_IF_SINGLE) == 0)
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;
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tmp |= ((ADC_DataSingleGet(ADC0) & 0x07) << (j * 3));
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}
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random |= (tmp & 0xff) << (i * 8);
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}
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return random;
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}
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otError otPlatRandomGetTrue(uint8_t *aOutput, uint16_t aOutputLength)
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{
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otError error = OT_ERROR_NONE;
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otEXPECT_ACTION(aOutput, error = OT_ERROR_INVALID_ARGS);
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for (uint16_t length = 0; length < aOutputLength; length++)
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{
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aOutput[length] = (uint8_t)otPlatRandomGet();
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}
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exit:
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return error;
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}
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