diff options
Diffstat (limited to 'thirdparty/nRF5_SDK_15.0.0_a53641a/external/mbedtls/yotta/data/entropy_hardware_poll.c')
-rw-r--r-- | thirdparty/nRF5_SDK_15.0.0_a53641a/external/mbedtls/yotta/data/entropy_hardware_poll.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/thirdparty/nRF5_SDK_15.0.0_a53641a/external/mbedtls/yotta/data/entropy_hardware_poll.c b/thirdparty/nRF5_SDK_15.0.0_a53641a/external/mbedtls/yotta/data/entropy_hardware_poll.c new file mode 100644 index 0000000..3a61e22 --- /dev/null +++ b/thirdparty/nRF5_SDK_15.0.0_a53641a/external/mbedtls/yotta/data/entropy_hardware_poll.c @@ -0,0 +1,88 @@ +/* + * 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. + * + * This file is part of mbed TLS (https://tls.mbed.org) + */ + +/* + * WARNING: this is temporary! + * This should be in a separate yotta module which would be a target + * dependency of mbedtls (see IOTSSL-313) + */ + +#if defined(TARGET_LIKE_K64F) + +/* + * Reference: "K64 Sub-Family Reference Manual, Rev. 2", chapter 34 + */ + +#include "fsl_clock_manager.h" + +/* + * 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 rng_get_byte( unsigned char *byte ) +{ + 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; + } +} + +/* + * Get len bytes of entropy from the hardware RNG. + */ +int mbedtls_hardware_poll( void *data, + unsigned char *output, size_t len, size_t *olen ) +{ + size_t i; + int ret; + ((void) data); + + CLOCK_SYS_EnableRngaClock( 0 ); + + /* 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 < len; i++ ) + rng_get_byte( output + i ); + + /* Just be extra sure that we didn't do it wrong */ + if( ( RNG->SR & RNG_SR_SECV_MASK ) != 0 ) + { + ret = -1; + goto cleanup; + } + + *olen = len; + ret = 0; + +cleanup: + /* Disable clock to save power - assume we're the only users of RNG */ + CLOCK_SYS_DisableRngaClock( 0 ); + + return( ret ); +} + +#endif |