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84 lines
1.7 KiB
C
84 lines
1.7 KiB
C
/*
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* Copyright(C) 2017 Francois Berder <fberder@outlook.fr>
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*
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*/
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#include <string.h>
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#include "board.h"
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#include "periph/hwrng.h"
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#ifdef _RNG
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static void wait_plen_cycles(void)
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{
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unsigned int i;
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for (i = 0; i < (RNGCON & _RNGCON_PLEN_MASK); ++i)
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__asm volatile ("nop");
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}
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void hwrng_init(void)
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{
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RNGCON = _RNGCON_TRNGEN_MASK;
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/*
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* Wait to have at least 64 bits before setting the 64-bit seed
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* of the pseudo random generator.
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*/
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while (RNGCNT < 64) {}
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/* Load seed from the TRNG */
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RNGCON |= _RNGCON_LOAD_MASK;
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while (RNGCON & _RNGCON_LOAD_MASK) {}
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RNGCON &= ~_RNGCON_TRNGEN_MASK;
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RNGPOLY1 = 0x00C00003;
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RNGPOLY2 = 0x00000000;
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RNGCON |= 42; /* Set PLEN to 42 */
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RNGCON |= _RNGCON_CONT_MASK;
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}
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void hwrng_read(void *buf, unsigned int num)
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{
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unsigned int i = 0;
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uint8_t *buffer = (uint8_t *)buf;
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RNGCON |= _RNGCON_PRNGEN_MASK;
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for (i = 0; i < (num >> 3); ++i) {
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uint32_t rng1, rng2;
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wait_plen_cycles();
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rng1 = RNGNUMGEN1;
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rng2 = RNGNUMGEN2;
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memcpy(buffer, &rng1, sizeof(rng1));
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memcpy(buffer + 4, &rng2, sizeof(rng2));
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buffer += 8;
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}
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num &= 0x7;
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if (num) {
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uint32_t rng1, n = num & 0x3;
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wait_plen_cycles();
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rng1 = RNGNUMGEN1;
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memcpy(buffer, &rng1, n);
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num -= n;
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buffer += n;
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if (num) {
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uint32_t rng2 = RNGNUMGEN2;
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memcpy(buffer, &rng2, num);
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}
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}
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RNGCON &= ~_RNGCON_PRNGEN_MASK;
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}
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#endif /* _RNG */
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