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mbed-os/targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_MCU_K64F/trng_api.c
- Committer:
- kadonotakashi
- Date:
- 2018-10-10
- Revision:
- 0:8fdf9a60065b
File content as of revision 0:8fdf9a60065b:
/* * Hardware entropy collector for the K64F, using Freescale's RNGA * * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */ /* * Reference: "K64 Sub-Family Reference Manual, Rev. 2", chapter 34 */ #if defined(DEVICE_TRNG) #include <stdlib.h> #include "cmsis.h" #include "fsl_common.h" #include "fsl_clock.h" #include "trng_api.h" void trng_init(trng_t *obj) { (void)obj; CLOCK_EnableClock(kCLOCK_Rnga0); CLOCK_DisableClock(kCLOCK_Rnga0); CLOCK_EnableClock(kCLOCK_Rnga0); } void trng_free(trng_t *obj) { (void)obj; CLOCK_DisableClock(kCLOCK_Rnga0); } /* * Get one byte of entropy from the RNG, assuming it is up and running. * As recommended (34.1.1), get only one bit of each output. */ static void trng_get_byte(unsigned char *byte) { *byte = 0; size_t bit; /* 34.5 Steps 3-4-5: poll SR and read from OR when ready */ for( bit = 0; bit < 8; bit++ ) { while((RNG->SR & RNG_SR_OREG_LVL_MASK) == 0 ); *byte |= (RNG->OR & 1) << bit; } } int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length) { (void)obj; size_t i; /* Set "Interrupt Mask", "High Assurance" and "Go", * unset "Clear interrupt" and "Sleep" */ RNG->CR = RNG_CR_INTM_MASK | RNG_CR_HA_MASK | RNG_CR_GO_MASK; for (i = 0; i < length; i++) { trng_get_byte(output + i); } /* Just be extra sure that we didn't do it wrong */ if ((RNG->SR & RNG_SR_SECV_MASK) != 0) { return -1; } *output_length = length; return 0; } #endif