66 lines
1.8 KiB
C
66 lines
1.8 KiB
C
/*
|
|
* Temporary "entropy" collector for Cortex-M4
|
|
*
|
|
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
|
|
*
|
|
* This file is part of mbed TLS (https://tls.mbed.org)
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along
|
|
* with this program; if not, write to the Free Software Foundation, Inc.,
|
|
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*/
|
|
|
|
/*
|
|
* WARNING: this is a temporary hack!
|
|
* 1. Currently does not provide strong entropy, should be replaced to use the
|
|
* on-board hardware RNG (see IOTSSL-303)
|
|
* 2. This should be in a separete yotta module which would be a target
|
|
* dependency of mbedtls (see IOTSSL-313)
|
|
*/
|
|
|
|
#if defined(TARGET_LIKE_CORTEX_M4)
|
|
|
|
#include "MK64F12.h"
|
|
#include "core_cm4.h"
|
|
#include <string.h>
|
|
|
|
unsigned long hardclock( void )
|
|
{
|
|
static int dwt_started = 0;
|
|
|
|
if( dwt_started == 0 )
|
|
{
|
|
CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
|
|
DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
|
|
}
|
|
|
|
return( DWT->CYCCNT );
|
|
}
|
|
|
|
int mbedtls_hardware_poll( void *data,
|
|
unsigned char *output, size_t len, size_t *olen )
|
|
{
|
|
unsigned long timer = hardclock();
|
|
((void) data);
|
|
*olen = 0;
|
|
|
|
if( len < sizeof(unsigned long) )
|
|
return( 0 );
|
|
|
|
memcpy( output, &timer, sizeof(unsigned long) );
|
|
*olen = sizeof(unsigned long);
|
|
|
|
return( 0 );
|
|
}
|
|
|
|
#endif
|