/* SPDX-License-Identifier: BSD-2-Clause */
/*
* Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de)
*
* 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.
*
* 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 OWNER 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.
*/
#include <stm32h7/hal.h>
#include <rtems.h>
#include <rtems/sysinit.h>
#include <sys/param.h>
#include <unistd.h>
#include <string.h>
static RNG_HandleTypeDef stm32h7_rng_instance = {
.Instance = RNG,
.Init.ClockErrorDetection = RNG_CED_DISABLE
};
static void stm32h7_rng_enable(void)
{
stm32h7_clk_enable(STM32H7_MODULE_RNG);
HAL_RNG_Init(&stm32h7_rng_instance);
}
int getentropy(void *ptr, size_t n)
{
while (n > 0) {
rtems_interrupt_level level;
uint32_t random;
bool ok;
size_t copy;
do {
rtems_interrupt_disable(level);
ok = (RNG->SR & RNG_FLAG_DRDY) != 0;
if (ok) {
random = RNG->DR;
}
rtems_interrupt_enable(level);
} while (!ok);
copy = MIN(sizeof(random), n);
ptr = memcpy(ptr, &random, copy);
n -= copy;
ptr += copy;
}
return 0;
}
RTEMS_SYSINIT_ITEM(
stm32h7_rng_enable,
RTEMS_SYSINIT_DEVICE_DRIVERS,
RTEMS_SYSINIT_ORDER_LAST_BUT_5
);