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/*
* Copyright (c) 2017 embedded brains GmbH. All rights reserved.
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#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
);
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