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Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +02001/*
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +02002 * Hardware entropy collector for the K64F, using Freescale's RNGA
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +02003 *
4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
Manuel Pégourié-Gonnard37ff1402015-09-04 14:21:07 +02005 * SPDX-License-Identifier: Apache-2.0
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020018 *
19 * This file is part of mbed TLS (https://tls.mbed.org)
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020020 */
21
22/*
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020023 * WARNING: this is temporary!
24 * This should be in a separate yotta module which would be a target
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020025 * dependency of mbedtls (see IOTSSL-313)
26 */
27
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020028#if defined(TARGET_LIKE_K64F)
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020029
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020030/*
31 * Reference: "K64 Sub-Family Reference Manual, Rev. 2", chapter 34
32 */
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020033
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020034#include "fsl_clock_manager.h"
35
36/*
37 * Get one byte of entropy from the RNG, assuming it is up and running.
38 * As recommended (34.1.1), get only one bit of each output.
39 */
40static void rng_get_byte( unsigned char *byte )
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020041{
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020042 size_t bit;
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020043
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020044 /* 34.5 Steps 3-4-5: poll SR and read from OR when ready */
45 for( bit = 0; bit < 8; bit++ )
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020046 {
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020047 while( ( RNG->SR & RNG_SR_OREG_LVL_MASK ) == 0 );
48 *byte |= ( RNG->OR & 1 ) << bit;
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020049 }
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020050}
51
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020052/*
53 * Get len bytes of entropy from the hardware RNG.
54 */
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020055int mbedtls_hardware_poll( void *data,
56 unsigned char *output, size_t len, size_t *olen )
57{
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020058 size_t i;
59 int ret;
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020060 ((void) data);
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020061
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020062 CLOCK_SYS_EnableRngaClock( 0 );
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020063
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020064 /* Set "Interrupt Mask", "High Assurance" and "Go",
65 * unset "Clear interrupt" and "Sleep" */
66 RNG->CR = RNG_CR_INTM_MASK | RNG_CR_HA_MASK | RNG_CR_GO_MASK;
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020067
Manuel Pégourié-Gonnard0e4d9af2015-08-18 13:33:14 +020068 for( i = 0; i < len; i++ )
69 rng_get_byte( output + i );
70
71 /* Just be extra sure that we didn't do it wrong */
72 if( ( RNG->SR & RNG_SR_SECV_MASK ) != 0 )
73 {
74 ret = -1;
75 goto cleanup;
76 }
77
78 *olen = len;
79 ret = 0;
80
81cleanup:
82 /* Disable clock to save power - assume we're the only users of RNG */
83 CLOCK_SYS_DisableRngaClock( 0 );
84
85 return( ret );
Manuel Pégourié-Gonnard63e7eba2015-07-28 14:17:48 +020086}
87
88#endif