113 lines
3.6 KiB
C
113 lines
3.6 KiB
C
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/*
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* Copyright (c) 2019, 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 an entropy source based on ADC.
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*
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*/
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#include <openthread/platform/entropy.h>
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#include <openthread/platform/radio.h>
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#include "platform-cc2538.h"
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#include "utils/code_utils.h"
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static void generateRandom(uint8_t *aOutput, uint16_t aOutputLength)
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{
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uint32_t frmctrl0;
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HWREG(SOC_ADC_ADCCON1) &= ~(SOC_ADC_ADCCON1_RCTRL1 | SOC_ADC_ADCCON1_RCTRL0);
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HWREG(SYS_CTRL_RCGCRFC) = SYS_CTRL_RCGCRFC_RFC0;
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while (HWREG(SYS_CTRL_RCGCRFC) != SYS_CTRL_RCGCRFC_RFC0)
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;
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frmctrl0 = HWREG(RFCORE_XREG_FRMCTRL0);
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HWREG(RFCORE_XREG_FRMCTRL0) = RFCORE_XREG_FRMCTRL0_INFINITY_RX;
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HWREG(RFCORE_SFR_RFST) = RFCORE_SFR_RFST_INSTR_RXON;
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while (!HWREG(RFCORE_XREG_RSSISTAT) & RFCORE_XREG_RSSISTAT_RSSI_VALID)
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;
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for (uint16_t index = 0; index < aOutputLength; index++)
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{
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aOutput[index] = 0;
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for (uint8_t offset = 0; offset < 8 * sizeof(uint8_t); offset++)
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{
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aOutput[index] <<= 1;
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aOutput[index] |= (HWREG(RFCORE_XREG_RFRND) & RFCORE_XREG_RFRND_IRND);
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}
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}
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HWREG(RFCORE_SFR_RFST) = RFCORE_SFR_RFST_INSTR_RFOFF;
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HWREG(RFCORE_XREG_FRMCTRL0) = frmctrl0;
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}
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void cc2538RandomInit(void)
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{
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uint16_t seed = 0;
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while (seed == 0x0000 || seed == 0x8003)
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{
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generateRandom((uint8_t *)&seed, sizeof(seed));
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}
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HWREG(SOC_ADC_RNDL) = (seed >> 8) & 0xff;
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HWREG(SOC_ADC_RNDL) = seed & 0xff;
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}
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otError otPlatEntropyGet(uint8_t *aOutput, uint16_t aOutputLength)
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{
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otError error = OT_ERROR_NONE;
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uint8_t channel = 0;
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otEXPECT_ACTION(aOutput, error = OT_ERROR_INVALID_ARGS);
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if (sInstance && otPlatRadioIsEnabled(sInstance))
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{
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channel = 11 + (HWREG(RFCORE_XREG_FREQCTRL) - 11) / 5;
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otPlatRadioSleep(sInstance);
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otPlatRadioDisable(sInstance);
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}
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generateRandom(aOutput, aOutputLength);
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if (channel)
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{
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cc2538RadioInit();
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otPlatRadioEnable(sInstance);
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otPlatRadioReceive(sInstance, channel);
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}
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exit:
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return error;
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}
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