/* SPDX-License-Identifier: BSD-2-Clause */
/*
* Copyright (c) 2017 embedded brains GmbH & Co. KG
*
* 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 <libchip/chip.h>
#include <unistd.h>
#include <string.h>
#include <rtems/sysinit.h>
static void atsam_trng_enable(void)
{
PMC_EnablePeripheral(ID_TRNG);
TRNG_Enable();
}
int getentropy(void *ptr, size_t n)
{
while (n > 0) {
uint32_t random;
size_t copy;
while ((TRNG_GetStatus() & TRNG_ISR_DATRDY) == 0) {
/* wait */
}
random = TRNG_GetRandData();
/*
* Read TRNG status one more time to avoid race condition.
* Otherwise we can read (and clear) an old ready status but get
* a new value. The ready status for this value wouldn't be
* reset.
*/
TRNG_GetStatus();
copy = sizeof(random);
if (n < copy ) {
copy = n;
}
memcpy(ptr, &random, copy);
n -= copy;
ptr += copy;
}
return 0;
}
RTEMS_SYSINIT_ITEM(
atsam_trng_enable,
RTEMS_SYSINIT_DEVICE_DRIVERS,
RTEMS_SYSINIT_ORDER_LAST_BUT_5
);