122 lines
3.2 KiB
C
122 lines
3.2 KiB
C
/** @addtogroup rng_file RNG peripheral API
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* @ingroup peripheral_apis
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*
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* This library supports "version 1" of the random number generator
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* peripheral (RNG) in the STM32 series of ARM Cortex Microcontrollers
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* by ST Microelectronics. This is a common peripheral available on multiple
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* devices in the family.
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*
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* LGPL License Terms @ref lgpl_license
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*/
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/*
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* This file is part of the libopencm3 project.
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <libopencm3/stm32/rng.h>
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/**@{*/
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/** Disable the Random Number Generator peripheral.
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*/
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void rng_disable(void)
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{
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RNG_CR &= ~RNG_CR_RNGEN;
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}
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/** Enable the Random Number Generator peripheral.
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*/
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void rng_enable(void)
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{
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RNG_CR |= RNG_CR_RNGEN;
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}
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/** Enable the Random Number Generator error interrupt.
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*/
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void rng_interrupt_enable(void)
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{
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RNG_CR |= RNG_CR_IE;
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}
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/** Disable the Random Number Generator error interrupt.
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*/
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void rng_interrupt_disable(void)
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{
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RNG_CR &= ~RNG_CR_IE;
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}
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/** Randomizes a number (non-blocking).
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* Can fail if a clock error or seed error is detected. Consult the Reference
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* Manual, but "try again", potentially after resetting the peripheral
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* @param rand_nr pointer to a uint32_t that will be randomized.
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* @returns true on success, pointer is only written to on success
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* @sa rng_get_random_blocking
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*/
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bool rng_get_random(uint32_t *rand_nr)
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{
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/* Check for errors */
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if (RNG_SR & (RNG_SR_CECS | RNG_SR_SECS)) {
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return false;
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}
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/* data ready */
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if (!(RNG_SR & RNG_SR_DRDY)) {
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return false;
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}
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*rand_nr = RNG_DR;
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return true;
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}
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/**
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* Get a random number and block until it works.
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* Unless you have a clock problem, this should always return "promptly"
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* If you have a clock problem, you will wait here forever!
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* Check device RM for clock requirements (usually fRNGCLK > fHCLK/16 or
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* fRNGCLK > fHCLK/32
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* @returns a random 32bit number
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*/
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uint32_t rng_get_random_blocking(void)
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{
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uint32_t rv;
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bool done;
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do {
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if (RNG_SR & RNG_SR_SEIS) {
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RNG_SR = RNG_SR & ~RNG_SR_SEIS;
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for (int i = 12; i != 0; i--) {
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rv = RNG_DR;
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}
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RNG_CR &= ~RNG_CR_RNGEN;
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RNG_CR |= RNG_CR_RNGEN;
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}
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if (RNG_SR & RNG_SR_CEIS) {
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RNG_SR = RNG_SR & ~RNG_SR_CEIS;
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}
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done = rng_get_random(&rv);
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} while (!done);
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return rv;
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}
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/**@}*/
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