hwrng.c
1.6 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
/*
* Copyright (C) 2014 Freie Universität Berlin
* Copyright (C) 2016 OTA keys S.A.
*
* 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_stm32f2
* @{
*
* @file
* @brief Low-level random number generator driver implementation
*
* @author Hauke Petersen <mail@haukepetersen.de>
* @author Aurelien Gonce <aurelien.gonce@altran.fr>
*
* @}
*/
#include "cpu.h"
#include "periph/hwrng.h"
#include "periph_conf.h"
/* ignore file in case no RNG device is defined */
#ifdef RNG
void hwrng_init(void)
{
/* enable RNG reset state */
periph_clk_en(AHB2, RCC_AHB2ENR_RNGEN);
/* release RNG from reset state */
periph_clk_dis(AHB2, RCC_AHB2ENR_RNGEN);
}
void hwrng_read(uint8_t *buf, unsigned int num)
{
/* cppcheck-suppress variableScope */
uint32_t tmp;
unsigned int count = 0;
/* enable RNG reset state */
periph_clk_en(AHB2, RCC_AHB2ENR_RNGEN);
/* enable the RNG */
RNG->CR |= RNG_CR_RNGEN;
while (count < num) {
/* wait for random data to be ready to read */
while (!(RNG->SR & RNG_SR_DRDY));
/* read next 4 bytes */
tmp = RNG->DR;
/* copy data into result vector */
for (int i = 0; i < 4 && count < num; i++) {
buf[count++] = (uint8_t)tmp;
tmp = tmp >> 8;
}
}
/* disable the RNG */
RNG->CR &= ~RNG_CR_RNGEN;
/* release RNG from reset state */
periph_clk_dis(AHB2, RCC_AHB2ENR_RNGEN);
}
#endif /* RANDOM_NUMOF */