| /* |
| * Copyright (c) 2019, The OpenThread Authors. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. Neither the name of the copyright holder nor the |
| * names of its contributors may be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
| * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| * POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /** |
| * @file |
| * This file implements an entropy source based on ADC. |
| * |
| */ |
| |
| #include <openthread/platform/entropy.h> |
| |
| #include <openthread/platform/radio.h> |
| |
| #include "platform-cc2538.h" |
| #include "utils/code_utils.h" |
| |
| static void generateRandom(uint8_t *aOutput, uint16_t aOutputLength) |
| { |
| uint32_t frmctrl0; |
| |
| HWREG(SOC_ADC_ADCCON1) &= ~(SOC_ADC_ADCCON1_RCTRL1 | SOC_ADC_ADCCON1_RCTRL0); |
| HWREG(SYS_CTRL_RCGCRFC) = SYS_CTRL_RCGCRFC_RFC0; |
| |
| while (HWREG(SYS_CTRL_RCGCRFC) != SYS_CTRL_RCGCRFC_RFC0) |
| ; |
| |
| frmctrl0 = HWREG(RFCORE_XREG_FRMCTRL0); |
| HWREG(RFCORE_XREG_FRMCTRL0) = RFCORE_XREG_FRMCTRL0_INFINITY_RX; |
| HWREG(RFCORE_SFR_RFST) = RFCORE_SFR_RFST_INSTR_RXON; |
| |
| while (!HWREG(RFCORE_XREG_RSSISTAT) & RFCORE_XREG_RSSISTAT_RSSI_VALID) |
| ; |
| |
| for (uint16_t index = 0; index < aOutputLength; index++) |
| { |
| aOutput[index] = 0; |
| |
| for (uint8_t offset = 0; offset < 8 * sizeof(uint8_t); offset++) |
| { |
| aOutput[index] <<= 1; |
| aOutput[index] |= (HWREG(RFCORE_XREG_RFRND) & RFCORE_XREG_RFRND_IRND); |
| } |
| } |
| |
| HWREG(RFCORE_SFR_RFST) = RFCORE_SFR_RFST_INSTR_RFOFF; |
| HWREG(RFCORE_XREG_FRMCTRL0) = frmctrl0; |
| } |
| |
| void cc2538RandomInit(void) |
| { |
| uint16_t seed = 0; |
| |
| while (seed == 0x0000 || seed == 0x8003) |
| { |
| generateRandom((uint8_t *)&seed, sizeof(seed)); |
| } |
| |
| HWREG(SOC_ADC_RNDL) = (seed >> 8) & 0xff; |
| HWREG(SOC_ADC_RNDL) = seed & 0xff; |
| } |
| |
| otError otPlatEntropyGet(uint8_t *aOutput, uint16_t aOutputLength) |
| { |
| otError error = OT_ERROR_NONE; |
| uint8_t channel = 0; |
| |
| otEXPECT_ACTION(aOutput, error = OT_ERROR_INVALID_ARGS); |
| |
| if (sInstance && otPlatRadioIsEnabled(sInstance)) |
| { |
| channel = 11 + (HWREG(RFCORE_XREG_FREQCTRL) - 11) / 5; |
| otPlatRadioSleep(sInstance); |
| otPlatRadioDisable(sInstance); |
| } |
| |
| generateRandom(aOutput, aOutputLength); |
| |
| if (channel) |
| { |
| cc2538RadioInit(); |
| otPlatRadioEnable(sInstance); |
| otPlatRadioReceive(sInstance, channel); |
| } |
| |
| exit: |
| return error; |
| } |