diff options
Diffstat (limited to 'bsps/arm/stm32h7/start/getentropy-rng.c')
-rw-r--r-- | bsps/arm/stm32h7/start/getentropy-rng.c | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/bsps/arm/stm32h7/start/getentropy-rng.c b/bsps/arm/stm32h7/start/getentropy-rng.c new file mode 100644 index 0000000000..7f75c2e915 --- /dev/null +++ b/bsps/arm/stm32h7/start/getentropy-rng.c @@ -0,0 +1,80 @@ +/* SPDX-License-Identifier: BSD-2-Clause */ + +/* + * Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de) + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include <stm32h7/hal.h> + +#include <rtems.h> +#include <rtems/sysinit.h> + +#include <sys/param.h> +#include <unistd.h> +#include <string.h> + +static RNG_HandleTypeDef stm32h7_rng_instance = { + .Instance = RNG, + .Init.ClockErrorDetection = RNG_CED_DISABLE +}; + +static void stm32h7_rng_enable(void) +{ + stm32h7_clk_enable(STM32H7_MODULE_RNG); + HAL_RNG_Init(&stm32h7_rng_instance); +} + +int getentropy(void *ptr, size_t n) +{ + while (n > 0) { + rtems_interrupt_level level; + uint32_t random; + bool ok; + size_t copy; + + do { + rtems_interrupt_disable(level); + + ok = (RNG->SR & RNG_FLAG_DRDY) != 0; + if (ok) { + random = RNG->DR; + } + + rtems_interrupt_enable(level); + } while (!ok); + + copy = MIN(sizeof(random), n); + ptr = memcpy(ptr, &random, copy); + n -= copy; + ptr += copy; + } + + return 0; +} + +RTEMS_SYSINIT_ITEM( + stm32h7_rng_enable, + RTEMS_SYSINIT_DEVICE_DRIVERS, + RTEMS_SYSINIT_ORDER_LAST_BUT_5 +); |