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/*
ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
/**
* @file hal_trng_lld.c
* @brief STM32 TRNG subsystem low level driver source.
*
* @addtogroup TRNG
* @{
*/
#include "hal.h"
#if (HAL_USE_TRNG == TRUE) || defined(__DOXYGEN__)
/*===========================================================================*/
/* Driver local definitions. */
/*===========================================================================*/
/*===========================================================================*/
/* Driver exported variables. */
/*===========================================================================*/
/**
* @brief TRNGD1 driver identifier.
*/
#if (STM32_TRNG_USE_RNG1 == TRUE) || defined(__DOXYGEN__)
TRNGDriver TRNGD1;
#endif
/*===========================================================================*/
/* Driver local variables and types. */
/*===========================================================================*/
static const TRNGConfig default_cfg = {0};
/*===========================================================================*/
/* Driver local functions. */
/*===========================================================================*/
/*===========================================================================*/
/* Driver interrupt handlers. */
/*===========================================================================*/
/*===========================================================================*/
/* Driver exported functions. */
/*===========================================================================*/
/**
* @brief Low level TRNG driver initialization.
*
* @notapi
*/
void trng_lld_init(void) {
#if STM32_TRNG_USE_RNG1 == TRUE
/* Driver initialization.*/
trngObjectInit(&TRNGD1);
TRNGD1.rng = RNG;
#endif
}
/**
* @brief Configures and activates the TRNG peripheral.
*
* @param[in] trngp pointer to the @p TRNGDriver object
*
* @notapi
*/
void trng_lld_start(TRNGDriver *trngp) {
/* There is no real configuration but setting up a valid pointer anyway.*/
if (trngp->config == NULL) {
trngp->config = &default_cfg;
}
if (trngp->state == TRNG_STOP) {
/* Enables the peripheral.*/
#if STM32_TRNG_USE_RNG1 == TRUE
if (&TRNGD1 == trngp) {
rccEnableRNG(false);
}
#endif
}
/* Configures the peripheral.*/
trngp->rng->CR |= RNG_CR_RNGEN;
}
/**
* @brief Deactivates the TRNG peripheral.
*
* @param[in] trngp pointer to the @p TRNGDriver object
*
* @notapi
*/
void trng_lld_stop(TRNGDriver *trngp) {
if (trngp->state == TRNG_READY) {
/* Resets the peripheral.*/
trngp->rng->CR &= ~RNG_CR_RNGEN;
/* Disables the peripheral.*/
#if STM32_TRNG_USE_RNG1 == TRUE
if (&TRNGD1 == trngp) {
rccDisableRNG();
}
#endif
}
}
/**
* @brief True random numbers generator.
* @note The function is blocking and likely performs polled waiting
* inside the low level implementation.
*
* @param[in] trngp pointer to the @p TRNGDriver object
* @param[in] size size of output buffer
* @param[out] out output buffer
* @return The operation status.
* @retval false if a random number has been generated.
* @retval true if an HW error occurred.
*
* @api
*/
bool trng_lld_generate(TRNGDriver *trngp, size_t size, uint8_t *out) {
while (true) {
uint32_t r, tmo;
size_t i;
/* Waiting for error conditions to be cleared.*/
tmo = STM32_TRNG_ERROR_CLEAR_ATTEMPTS;
while ((tmo > 0) && ((trngp->rng->SR & (RNG_SR_CECS | RNG_SR_SECS)) != 0)) {
tmo--;
if (tmo == 0) {
return true;
}
}
/* Waiting for a random number in data register.*/
tmo = STM32_DATA_FETCH_ATTEMPTS;
while ((tmo > 0) && ((trngp->rng->SR & RNG_SR_DRDY) == 0)) {
tmo--;
if (tmo == 0) {
return true;
}
}
/* Getting the generated random number.*/
r = trngp->rng->DR;
/* Writing in the output buffer.*/
for (i = 0; i < sizeof (uint32_t) / sizeof (uint8_t); i++) {
*out++ = (uint8_t)r;
r = r >> 8;
size--;
if (size == 0) {
return false;
}
}
}
}
#endif /* HAL_USE_TRNG == TRUE */
/** @} */
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