Lancaster University / mbed-src

Lancaster University's (short term!) clone of mbed-src for micro:bit. This is a copy of the github branch https://github.com/lancaster-university/mbed-classic

Fork of mbed-src by mbed official

common/rtc_time.c@641:be9b2017785a, 2016-07-13 (annotated)

Committer:
LancasterUniversity
Date:
Wed Jul 13 12:52:54 2016 +0100
Revision:
641:be9b2017785a
Parent:
489:119543c9f674 
Synchronized with git rev 1fb8ab4c

Author: James Devine

mbed-classic: BUGFIX for timer when using wait_ms from interrupt context



Previously if a user used wait[_ms,_us] in interrupt context the device would

hang indefinitely. This was due to incrementing overflowCount from

interrupt context only.



This meant that if a user used wait[_ms,_us] in an ISR with

the same or greater interrupt priority, it would result in an infinite

loop as the overflowCount variable would never be incremented, and

wait[_ms,_us] would never return.



This patch simply applies a better solution for the race condition

mentioned in the previous commit. It instead disables the timer1

interrupt and increments the overflowCount variable, preventing

the race condition whilst supporting wait[_ms,_us] in interrupt

context.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bogdanm 13:0645d8841f51 1 /* mbed Microcontroller Library
bogdanm 13:0645d8841f51 2 * Copyright (c) 2006-2013 ARM Limited
bogdanm 13:0645d8841f51 3 *
bogdanm 13:0645d8841f51 4 * Licensed under the Apache License, Version 2.0 (the "License");
bogdanm 13:0645d8841f51 5 * you may not use this file except in compliance with the License.
bogdanm 13:0645d8841f51 6 * You may obtain a copy of the License at
bogdanm 13:0645d8841f51 7 *
bogdanm 13:0645d8841f51 8 * http://www.apache.org/licenses/LICENSE-2.0
bogdanm 13:0645d8841f51 9 *
bogdanm 13:0645d8841f51 10 * Unless required by applicable law or agreed to in writing, software
bogdanm 13:0645d8841f51 11 * distributed under the License is distributed on an "AS IS" BASIS,
bogdanm 13:0645d8841f51 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
bogdanm 13:0645d8841f51 13 * See the License for the specific language governing permissions and
bogdanm 13:0645d8841f51 14 * limitations under the License.
bogdanm 13:0645d8841f51 15 */
bogdanm 13:0645d8841f51 16 #include "rtc_api.h"
bogdanm 13:0645d8841f51 17
bogdanm 13:0645d8841f51 18 #include <time.h>
bogdanm 13:0645d8841f51 19 #include "rtc_time.h"
bogdanm 13:0645d8841f51 20 #include "us_ticker_api.h"
bogdanm 13:0645d8841f51 21
mbed_official 489:119543c9f674 22 #if DEVICE_RTC
mbed_official 489:119543c9f674 23 static void (*_rtc_init)(void) = rtc_init;
mbed_official 489:119543c9f674 24 static int (*_rtc_isenabled)(void) = rtc_isenabled;
mbed_official 489:119543c9f674 25 static time_t (*_rtc_read)(void) = rtc_read;
mbed_official 489:119543c9f674 26 static void (*_rtc_write)(time_t t) = rtc_write;
mbed_official 489:119543c9f674 27 #else
mbed_official 489:119543c9f674 28 static void (*_rtc_init)(void) = NULL;
mbed_official 489:119543c9f674 29 static int (*_rtc_isenabled)(void) = NULL;
mbed_official 489:119543c9f674 30 static time_t (*_rtc_read)(void) = NULL;
mbed_official 489:119543c9f674 31 static void (*_rtc_write)(time_t t) = NULL;
mbed_official 489:119543c9f674 32 #endif
mbed_official 489:119543c9f674 33
mbed_official 85:e1a8e879a6a9 34 #ifdef __cplusplus
mbed_official 85:e1a8e879a6a9 35 extern "C" {
mbed_official 221:8276e3a4886f 36 #endif
bogdanm 13:0645d8841f51 37 #if defined (__ICCARM__)
bogdanm 13:0645d8841f51 38 time_t __time32(time_t *timer)
bogdanm 13:0645d8841f51 39 #else
bogdanm 13:0645d8841f51 40 time_t time(time_t *timer)
bogdanm 13:0645d8841f51 41 #endif
mbed_official 85:e1a8e879a6a9 42
bogdanm 13:0645d8841f51 43 {
mbed_official 489:119543c9f674 44 if (_rtc_isenabled != NULL) {
mbed_official 489:119543c9f674 45 if (!(_rtc_isenabled())) {
mbed_official 489:119543c9f674 46 set_time(0);
mbed_official 489:119543c9f674 47 }
bogdanm 13:0645d8841f51 48 }
mbed_official 489:119543c9f674 49
bogdanm 13:0645d8841f51 50 time_t t = 0;
mbed_official 489:119543c9f674 51 if (_rtc_read != NULL) {
mbed_official 489:119543c9f674 52 t = _rtc_read();
mbed_official 489:119543c9f674 53 }
bogdanm 13:0645d8841f51 54
bogdanm 13:0645d8841f51 55 if (timer != NULL) {
bogdanm 13:0645d8841f51 56 *timer = t;
bogdanm 13:0645d8841f51 57 }
bogdanm 13:0645d8841f51 58 return t;
bogdanm 13:0645d8841f51 59 }
bogdanm 13:0645d8841f51 60
bogdanm 13:0645d8841f51 61 void set_time(time_t t) {
mbed_official 489:119543c9f674 62 if (_rtc_init != NULL) {
mbed_official 489:119543c9f674 63 _rtc_init();
mbed_official 489:119543c9f674 64 }
mbed_official 489:119543c9f674 65 if (_rtc_write != NULL) {
mbed_official 489:119543c9f674 66 _rtc_write(t);
mbed_official 489:119543c9f674 67 }
bogdanm 13:0645d8841f51 68 }
bogdanm 13:0645d8841f51 69
bogdanm 13:0645d8841f51 70 clock_t clock() {
bogdanm 13:0645d8841f51 71 clock_t t = us_ticker_read();
bogdanm 13:0645d8841f51 72 t /= 1000000 / CLOCKS_PER_SEC; // convert to processor time
bogdanm 13:0645d8841f51 73 return t;
bogdanm 13:0645d8841f51 74 }
mbed_official 85:e1a8e879a6a9 75
mbed_official 489:119543c9f674 76 void attach_rtc(time_t (*read_rtc)(void), void (*write_rtc)(time_t), void (*init_rtc)(void), int (*isenabled_rtc)(void)) {
mbed_official 489:119543c9f674 77 __disable_irq();
mbed_official 489:119543c9f674 78 _rtc_read = read_rtc;
mbed_official 489:119543c9f674 79 _rtc_write = write_rtc;
mbed_official 489:119543c9f674 80 _rtc_init = init_rtc;
mbed_official 489:119543c9f674 81 _rtc_isenabled = isenabled_rtc;
mbed_official 489:119543c9f674 82 __enable_irq();
mbed_official 489:119543c9f674 83 }
mbed_official 489:119543c9f674 84
mbed_official 489:119543c9f674 85
mbed_official 489:119543c9f674 86
mbed_official 85:e1a8e879a6a9 87 #ifdef __cplusplus
mbed_official 85:e1a8e879a6a9 88 }
mbed_official 221:8276e3a4886f 89 #endif