Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_Freescale/TARGET_KSDK2_MCUS/TARGET_MCU_K64F/entropy_hardware_poll.c@147:ba84b7dc41a7, 2016-09-10 (annotated)

Committer:
JojoS
Date:
Sat Sep 10 15:32:04 2016 +0000
Revision:
147:ba84b7dc41a7
Parent:
144:ef7eb2e8f9f7 
added prescaler for 16 bit timers (solution as in LPC11xx), default prescaler 31 for max 28 ms period time

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 144:ef7eb2e8f9f7 1 /*
<> 144:ef7eb2e8f9f7 2 * Hardware entropy collector for the K64F, using Freescale's RNGA
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
<> 144:ef7eb2e8f9f7 5 * SPDX-License-Identifier: Apache-2.0
<> 144:ef7eb2e8f9f7 6 *
<> 144:ef7eb2e8f9f7 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
<> 144:ef7eb2e8f9f7 8 * not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 9 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 10 *
<> 144:ef7eb2e8f9f7 11 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 12 *
<> 144:ef7eb2e8f9f7 13 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
<> 144:ef7eb2e8f9f7 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 16 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 17 * limitations under the License.
<> 144:ef7eb2e8f9f7 18 *
<> 144:ef7eb2e8f9f7 19 */
<> 144:ef7eb2e8f9f7 20
<> 144:ef7eb2e8f9f7 21 /*
<> 144:ef7eb2e8f9f7 22 * Reference: "K64 Sub-Family Reference Manual, Rev. 2", chapter 34
<> 144:ef7eb2e8f9f7 23 */
<> 144:ef7eb2e8f9f7 24
<> 144:ef7eb2e8f9f7 25 #include <stdlib.h>
<> 144:ef7eb2e8f9f7 26 #include "cmsis.h"
<> 144:ef7eb2e8f9f7 27 #include "fsl_common.h"
<> 144:ef7eb2e8f9f7 28 #include "fsl_clock.h"
<> 144:ef7eb2e8f9f7 29
<> 144:ef7eb2e8f9f7 30 /*
<> 144:ef7eb2e8f9f7 31 * Get one byte of entropy from the RNG, assuming it is up and running.
<> 144:ef7eb2e8f9f7 32 * As recommended (34.1.1), get only one bit of each output.
<> 144:ef7eb2e8f9f7 33 */
<> 144:ef7eb2e8f9f7 34 static void rng_get_byte( unsigned char *byte )
<> 144:ef7eb2e8f9f7 35 {
<> 144:ef7eb2e8f9f7 36 size_t bit;
<> 144:ef7eb2e8f9f7 37
<> 144:ef7eb2e8f9f7 38 /* 34.5 Steps 3-4-5: poll SR and read from OR when ready */
<> 144:ef7eb2e8f9f7 39 for( bit = 0; bit < 8; bit++ )
<> 144:ef7eb2e8f9f7 40 {
<> 144:ef7eb2e8f9f7 41 while( ( RNG->SR & RNG_SR_OREG_LVL_MASK ) == 0 );
<> 144:ef7eb2e8f9f7 42 *byte |= ( RNG->OR & 1 ) << bit;
<> 144:ef7eb2e8f9f7 43 }
<> 144:ef7eb2e8f9f7 44 }
<> 144:ef7eb2e8f9f7 45
<> 144:ef7eb2e8f9f7 46 /*
<> 144:ef7eb2e8f9f7 47 * Get len bytes of entropy from the hardware RNG.
<> 144:ef7eb2e8f9f7 48 */
<> 144:ef7eb2e8f9f7 49 int mbedtls_hardware_poll( void *data,
<> 144:ef7eb2e8f9f7 50 unsigned char *output, size_t len, size_t *olen )
<> 144:ef7eb2e8f9f7 51 {
<> 144:ef7eb2e8f9f7 52 size_t i;
<> 144:ef7eb2e8f9f7 53 int ret;
<> 144:ef7eb2e8f9f7 54 ((void) data);
<> 144:ef7eb2e8f9f7 55
<> 144:ef7eb2e8f9f7 56 CLOCK_EnableClock( kCLOCK_Rnga0 );
<> 144:ef7eb2e8f9f7 57 CLOCK_DisableClock( kCLOCK_Rnga0 );
<> 144:ef7eb2e8f9f7 58 CLOCK_EnableClock( kCLOCK_Rnga0 );
<> 144:ef7eb2e8f9f7 59
<> 144:ef7eb2e8f9f7 60 /* Set "Interrupt Mask", "High Assurance" and "Go",
<> 144:ef7eb2e8f9f7 61 * unset "Clear interrupt" and "Sleep" */
<> 144:ef7eb2e8f9f7 62 RNG->CR = RNG_CR_INTM_MASK | RNG_CR_HA_MASK | RNG_CR_GO_MASK;
<> 144:ef7eb2e8f9f7 63
<> 144:ef7eb2e8f9f7 64 for( i = 0; i < len; i++ )
<> 144:ef7eb2e8f9f7 65 rng_get_byte( output + i );
<> 144:ef7eb2e8f9f7 66
<> 144:ef7eb2e8f9f7 67 /* Just be extra sure that we didn't do it wrong */
<> 144:ef7eb2e8f9f7 68 if( ( RNG->SR & RNG_SR_SECV_MASK ) != 0 )
<> 144:ef7eb2e8f9f7 69 {
<> 144:ef7eb2e8f9f7 70 ret = -1;
<> 144:ef7eb2e8f9f7 71 goto cleanup;
<> 144:ef7eb2e8f9f7 72 }
<> 144:ef7eb2e8f9f7 73
<> 144:ef7eb2e8f9f7 74 *olen = len;
<> 144:ef7eb2e8f9f7 75 ret = 0;
<> 144:ef7eb2e8f9f7 76
<> 144:ef7eb2e8f9f7 77 cleanup:
<> 144:ef7eb2e8f9f7 78 /* Disable clock to save power - assume we're the only users of RNG */
<> 144:ef7eb2e8f9f7 79 CLOCK_DisableClock( kCLOCK_Rnga0 );
<> 144:ef7eb2e8f9f7 80
<> 144:ef7eb2e8f9f7 81 return( ret );
<> 144:ef7eb2e8f9f7 82 }
<> 144:ef7eb2e8f9f7 83