144 lines
6.3 KiB
C
144 lines
6.3 KiB
C
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// #################################################################################################
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// # << NEORV32: neorv32_trng.c - True Random Number Generator (TRNG) HW Driver >> #
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// # ********************************************************************************************* #
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// # BSD 3-Clause License #
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// # #
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// # Copyright (c) 2023, Stephan Nolting. All rights reserved. #
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// # #
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// # Redistribution and use in source and binary forms, with or without modification, are #
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// # permitted provided that the following conditions are met: #
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// # #
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// # 1. Redistributions of source code must retain the above copyright notice, this list of #
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// # conditions and the following disclaimer. #
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// # #
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// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
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// # conditions and the following disclaimer in the documentation and/or other materials #
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// # 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 contributors may be used to #
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// # endorse or promote products derived from this software without specific prior written #
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// # permission. #
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// # #
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// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
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// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
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// # MERCHANTABILITY AND FITNESS 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, INCIDENTAL, SPECIAL, #
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// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
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// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
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// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
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// # NEGLIGENCE OR OTHERWISE) 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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// # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting #
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// #################################################################################################
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/**********************************************************************//**
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* @file neorv32_trng.c
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* @brief True Random Number Generator (TRNG) HW driver source file.
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*
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* @note These functions should only be used if the TRNG unit was synthesized (IO_TRNG_EN = true).
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**************************************************************************/
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#include "neorv32.h"
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#include "neorv32_trng.h"
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/**********************************************************************//**
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* Check if TRNG unit was synthesized.
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*
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* @return 0 if TRNG was not synthesized, 1 if TRNG is available.
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**************************************************************************/
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int neorv32_trng_available(void) {
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if (NEORV32_SYSINFO.SOC & (1 << SYSINFO_SOC_IO_TRNG)) {
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return 1;
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}
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else {
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return 0;
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}
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}
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/**********************************************************************//**
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* Reset and enable TRNG.
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* @note This will take a while.
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**************************************************************************/
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void neorv32_trng_enable(void) {
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int i;
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NEORV32_TRNG.CTRL = 0; // reset
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// wait for all internal components to reset
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for (i=0; i<512; i++) {
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asm volatile ("nop");
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}
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NEORV32_TRNG.CTRL = 1 << TRNG_CTRL_EN; // activate
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// "warm-up"
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for (i=0; i<512; i++) {
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asm volatile ("nop");
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}
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// flush random data "pool"
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neorv32_trng_fifo_clear();
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}
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/**********************************************************************//**
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* Reset and disable TRNG.
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**************************************************************************/
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void neorv32_trng_disable(void) {
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NEORV32_TRNG.CTRL = 0;
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}
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/**********************************************************************//**
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* Flush TRNG random data FIFO.
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**************************************************************************/
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void neorv32_trng_fifo_clear(void) {
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NEORV32_TRNG.CTRL |= 1 << TRNG_CTRL_FIFO_CLR; // bit auto clears
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}
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/**********************************************************************//**
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* Get random data byte from TRNG.
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*
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* @param[in,out] data uint8_t pointer for storing random data byte. Will be set to zero if no valid data available.
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* @return Data is valid when 0 and invalid otherwise.
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**************************************************************************/
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int neorv32_trng_get(uint8_t *data) {
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uint32_t tmp = NEORV32_TRNG.CTRL;
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*data = (uint8_t)(tmp >> TRNG_CTRL_DATA_LSB);
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if (tmp & (1<<TRNG_CTRL_VALID)) { // output data valid?
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return 0; // valid data
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}
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else {
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return -1;
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}
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}
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/**********************************************************************//**
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* Check if TRNG is implemented using SIMULATION mode.
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*
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* @warning In simulation mode the physical entropy source is replaced by a PRNG (LFSR) with very bad random quality.
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*
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* @return Simulation mode active when not zero.
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**************************************************************************/
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int neorv32_trng_check_sim_mode(void) {
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if (NEORV32_TRNG.CTRL & (1<<TRNG_CTRL_SIM_MODE)) {
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return -1; // simulation mode (PRNG)
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}
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else {
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return 0; // real TRUE random number generator mode
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}
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}
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