hwrng_rngb.c
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/*
* Copyright (C) 2014-2016 Freie Universität Berlin
* Copyright (C) 2014 PHYTEC Messtechnik GmbH
* Copyright (C) 2015 Eistec AB
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_kinetis_common_rngb
* @{
*
* @file
* @brief HWRNG interface implementation
*
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se> (adaption for Freescale's RNGB)
* @author Johann Fischer <j.fischer@phytec.de> (adaption for Freescale's RNGA)
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*
* @}
*/
#include "cpu.h"
#include "periph/hwrng.h"
#include "periph_conf.h"
#ifdef KINETIS_RNGB
void hwrng_init(void)
{
/* nothing to be done here */
}
void hwrng_read(uint8_t *buf, unsigned int num)
{
unsigned int count = 0;
HWRNG_CLKEN();
if ((KINETIS_RNGB->VER & RNG_VER_TYPE_MASK) != 0b0001) {
/* Wrong type of RNG */
/* TODO: Handle */
}
/* Software reset, bit is self-clearing */
BITBAND_REG32(KINETIS_RNGB->CMD, RNG_CMD_SR_SHIFT) = 1;
/* Set up automatic reseed */
KINETIS_RNGB->CR = RNG_CR_AR_MASK | RNG_CR_MASKERR_MASK | RNG_CR_MASKDONE_MASK;
while (count < num) {
uint32_t tmp;
/* wait for random data to be ready to read */
while (!(KINETIS_RNGB->SR & RNG_SR_FIFO_LVL_MASK));
tmp = KINETIS_RNGB->OUT;
/* copy data into result vector */
for (int i = 0; i < 4 && count < num; i++) {
buf[count++] = (uint8_t)tmp;
tmp = tmp >> 8;
}
}
KINETIS_RNGB->CR = 0;
HWRNG_CLKDIS();
}
#endif /* KINETIS_RNGB */