137 lines
4.5 KiB
C
137 lines
4.5 KiB
C
/*
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* Copyright (c) 2012, Texas Instruments Incorporated - http://www.ti.com/
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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
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* 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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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* 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
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* 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
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \addtogroup cc2538
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* @{
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*
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* \defgroup cc2538-random cc2538 Random Number Generator
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*
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* Driver for the cc2538 Hardware Random Number Generator
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* @{
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*
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* \file
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* Random number generator routines exploiting the cc2538 hardware
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* capabilities.
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*
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* This file overrides os/lib/random.c.
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*/
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#include "contiki.h"
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#include "dev/rfcore.h"
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#include "dev/cc2538-rf.h"
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#include "dev/soc-adc.h"
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#include "dev/sys-ctrl.h"
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#include "reg.h"
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Generates a new random number using the cc2538 RNG.
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* \return The random number.
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*/
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unsigned short
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random_rand(void)
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{
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uint32_t rv;
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/* Clock the RNG LSFR once */
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REG(SOC_ADC_ADCCON1) |= SOC_ADC_ADCCON1_RCTRL0;
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rv = REG(SOC_ADC_RNDL) | (REG(SOC_ADC_RNDH) << 8);
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return ((unsigned short)rv);
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Seed the cc2538 random number generator.
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* \param seed Ignored. It's here because the function prototype is in core.
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*
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* We form a seed for the RNG by sampling IF_ADC as
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* discussed in the user guide.
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* Seeding with this method should not be done during
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* normal radio operation. Thus, use this function before
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* initialising the network.
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*
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* \note Must not be called after the RF driver has been initialised and is
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* in normal operation. If it is absolutely necessary to do so, the
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* radio will need re-initialised.
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*/
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void
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random_init(unsigned short seed)
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{
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int i;
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unsigned short s = 0;
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/* Make sure the RNG is on */
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REG(SOC_ADC_ADCCON1) &= ~(SOC_ADC_ADCCON1_RCTRL1 | SOC_ADC_ADCCON1_RCTRL0);
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/* Enable clock for the RF Core */
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REG(SYS_CTRL_RCGCRFC) = 1;
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/* Wait for the clock ungating to take effect */
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while(REG(SYS_CTRL_RCGCRFC) != 1);
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/* Infinite RX - FRMCTRL0[3:2] = 10
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* This will mess with radio operation - see note above */
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REG(RFCORE_XREG_FRMCTRL0) = 0x00000008;
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/* Turn RF on */
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CC2538_RF_CSP_ISRXON();
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/*
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* Wait until "the chip has been in RX long enough for the transients to
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* have died out. A convenient way to do this is to wait for the RSSI-valid
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* signal to go high."
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*/
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while(!(REG(RFCORE_XREG_RSSISTAT) & RFCORE_XREG_RSSISTAT_RSSI_VALID));
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/*
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* Form the seed by concatenating bits from IF_ADC in the RF receive path.
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* Keep sampling until we have read at least 16 bits AND the seed is valid
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*
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* Invalid seeds are 0x0000 and 0x8003 and should not be used.
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*/
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while(s == 0x0000 || s == 0x8003) {
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for(i = 0; i < 16; i++) {
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s |= (REG(RFCORE_XREG_RFRND) & RFCORE_XREG_RFRND_IRND);
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s <<= 1;
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}
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}
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/* High byte first */
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REG(SOC_ADC_RNDL) = (s >> 8) & 0x00FF;
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REG(SOC_ADC_RNDL) = s & 0xFF;
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/* RF Off. NETSTACK_RADIO.init() will sort out normal RF operation */
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CC2538_RF_CSP_ISRFOFF();
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}
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/**
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* @}
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* @}
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*/
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