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/SerialBase.cpp@641:be9b2017785a, 2016-07-13 (annotated)

Committer:
LancasterUniversity
Date:
Wed Jul 13 12:52:54 2016 +0100
Revision:
641:be9b2017785a
Parent:
563:536c9fb088a0 
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
mbed_official 36:ab3ee77451e7 1 /* mbed Microcontroller Library
mbed_official 36:ab3ee77451e7 2 * Copyright (c) 2006-2013 ARM Limited
mbed_official 36:ab3ee77451e7 3 *
mbed_official 36:ab3ee77451e7 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 36:ab3ee77451e7 5 * you may not use this file except in compliance with the License.
mbed_official 36:ab3ee77451e7 6 * You may obtain a copy of the License at
mbed_official 36:ab3ee77451e7 7 *
mbed_official 36:ab3ee77451e7 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 36:ab3ee77451e7 9 *
mbed_official 36:ab3ee77451e7 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 36:ab3ee77451e7 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 36:ab3ee77451e7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 36:ab3ee77451e7 13 * See the License for the specific language governing permissions and
mbed_official 36:ab3ee77451e7 14 * limitations under the License.
mbed_official 36:ab3ee77451e7 15 */
mbed_official 36:ab3ee77451e7 16 #include "SerialBase.h"
mbed_official 36:ab3ee77451e7 17 #include "wait_api.h"
mbed_official 36:ab3ee77451e7 18
mbed_official 36:ab3ee77451e7 19 #if DEVICE_SERIAL
mbed_official 36:ab3ee77451e7 20
mbed_official 36:ab3ee77451e7 21 namespace mbed {
mbed_official 36:ab3ee77451e7 22
mbed_official 525:c320967f86b9 23 SerialBase::SerialBase(PinName tx, PinName rx) :
mbed_official 525:c320967f86b9 24 #if DEVICE_SERIAL_ASYNCH
mbed_official 525:c320967f86b9 25 _thunk_irq(this), _tx_usage(DMA_USAGE_NEVER),
mbed_official 525:c320967f86b9 26 _rx_usage(DMA_USAGE_NEVER),
mbed_official 525:c320967f86b9 27 #endif
mbed_official 525:c320967f86b9 28 _serial(), _baud(9600) {
mbed_official 36:ab3ee77451e7 29 serial_init(&_serial, tx, rx);
mbed_official 36:ab3ee77451e7 30 serial_irq_handler(&_serial, SerialBase::_irq_handler, (uint32_t)this);
mbed_official 36:ab3ee77451e7 31 }
mbed_official 36:ab3ee77451e7 32
mbed_official 36:ab3ee77451e7 33 void SerialBase::baud(int baudrate) {
mbed_official 36:ab3ee77451e7 34 serial_baud(&_serial, baudrate);
mbed_official 36:ab3ee77451e7 35 _baud = baudrate;
mbed_official 36:ab3ee77451e7 36 }
mbed_official 36:ab3ee77451e7 37
mbed_official 36:ab3ee77451e7 38 void SerialBase::format(int bits, Parity parity, int stop_bits) {
mbed_official 36:ab3ee77451e7 39 serial_format(&_serial, bits, (SerialParity)parity, stop_bits);
mbed_official 36:ab3ee77451e7 40 }
mbed_official 36:ab3ee77451e7 41
mbed_official 36:ab3ee77451e7 42 int SerialBase::readable() {
mbed_official 36:ab3ee77451e7 43 return serial_readable(&_serial);
mbed_official 36:ab3ee77451e7 44 }
mbed_official 36:ab3ee77451e7 45
mbed_official 36:ab3ee77451e7 46
mbed_official 36:ab3ee77451e7 47 int SerialBase::writeable() {
mbed_official 36:ab3ee77451e7 48 return serial_writable(&_serial);
mbed_official 36:ab3ee77451e7 49 }
mbed_official 36:ab3ee77451e7 50
mbed_official 36:ab3ee77451e7 51 void SerialBase::attach(void (*fptr)(void), IrqType type) {
mbed_official 36:ab3ee77451e7 52 if (fptr) {
mbed_official 36:ab3ee77451e7 53 _irq[type].attach(fptr);
mbed_official 36:ab3ee77451e7 54 serial_irq_set(&_serial, (SerialIrq)type, 1);
mbed_official 36:ab3ee77451e7 55 } else {
mbed_official 36:ab3ee77451e7 56 serial_irq_set(&_serial, (SerialIrq)type, 0);
mbed_official 36:ab3ee77451e7 57 }
mbed_official 36:ab3ee77451e7 58 }
mbed_official 36:ab3ee77451e7 59
mbed_official 36:ab3ee77451e7 60 void SerialBase::_irq_handler(uint32_t id, SerialIrq irq_type) {
mbed_official 36:ab3ee77451e7 61 SerialBase *handler = (SerialBase*)id;
mbed_official 36:ab3ee77451e7 62 handler->_irq[irq_type].call();
mbed_official 36:ab3ee77451e7 63 }
mbed_official 36:ab3ee77451e7 64
mbed_official 36:ab3ee77451e7 65 int SerialBase::_base_getc() {
mbed_official 36:ab3ee77451e7 66 return serial_getc(&_serial);
mbed_official 36:ab3ee77451e7 67 }
mbed_official 36:ab3ee77451e7 68
mbed_official 36:ab3ee77451e7 69 int SerialBase::_base_putc(int c) {
mbed_official 36:ab3ee77451e7 70 serial_putc(&_serial, c);
mbed_official 36:ab3ee77451e7 71 return c;
mbed_official 36:ab3ee77451e7 72 }
mbed_official 36:ab3ee77451e7 73
mbed_official 36:ab3ee77451e7 74 void SerialBase::send_break() {
mbed_official 36:ab3ee77451e7 75 // Wait for 1.5 frames before clearing the break condition
mbed_official 36:ab3ee77451e7 76 // This will have different effects on our platforms, but should
mbed_official 36:ab3ee77451e7 77 // ensure that we keep the break active for at least one frame.
mbed_official 212:34d62c0b2af6 78 // We consider a full frame (1 start bit + 8 data bits bits +
mbed_official 36:ab3ee77451e7 79 // 1 parity bit + 2 stop bits = 12 bits) for computation.
mbed_official 36:ab3ee77451e7 80 // One bit time (in us) = 1000000/_baud
mbed_official 36:ab3ee77451e7 81 // Twelve bits: 12000000/baud delay
mbed_official 36:ab3ee77451e7 82 // 1.5 frames: 18000000/baud delay
mbed_official 36:ab3ee77451e7 83 serial_break_set(&_serial);
mbed_official 36:ab3ee77451e7 84 wait_us(18000000/_baud);
mbed_official 36:ab3ee77451e7 85 serial_break_clear(&_serial);
mbed_official 36:ab3ee77451e7 86 }
mbed_official 36:ab3ee77451e7 87
mbed_official 192:42b1a45e48aa 88 #if DEVICE_SERIAL_FC
mbed_official 64:7b352733b00a 89 void SerialBase::set_flow_control(Flow type, PinName flow1, PinName flow2) {
mbed_official 64:7b352733b00a 90 FlowControl flow_type = (FlowControl)type;
mbed_official 64:7b352733b00a 91 switch(type) {
mbed_official 64:7b352733b00a 92 case RTS:
mbed_official 64:7b352733b00a 93 serial_set_flow_control(&_serial, flow_type, flow1, NC);
mbed_official 64:7b352733b00a 94 break;
mbed_official 212:34d62c0b2af6 95
mbed_official 64:7b352733b00a 96 case CTS:
mbed_official 64:7b352733b00a 97 serial_set_flow_control(&_serial, flow_type, NC, flow1);
mbed_official 64:7b352733b00a 98 break;
mbed_official 212:34d62c0b2af6 99
mbed_official 64:7b352733b00a 100 case RTSCTS:
mbed_official 65:46be7cdf873f 101 case Disabled:
mbed_official 64:7b352733b00a 102 serial_set_flow_control(&_serial, flow_type, flow1, flow2);
mbed_official 64:7b352733b00a 103 break;
mbed_official 212:34d62c0b2af6 104
mbed_official 64:7b352733b00a 105 default:
mbed_official 64:7b352733b00a 106 break;
mbed_official 64:7b352733b00a 107 }
mbed_official 64:7b352733b00a 108 }
mbed_official 64:7b352733b00a 109 #endif
mbed_official 64:7b352733b00a 110
mbed_official 525:c320967f86b9 111 #if DEVICE_SERIAL_ASYNCH
mbed_official 525:c320967f86b9 112
mbed_official 563:536c9fb088a0 113 int SerialBase::write(const uint8_t *buffer, int length, const event_callback_t& callback, int event)
mbed_official 525:c320967f86b9 114 {
mbed_official 525:c320967f86b9 115 if (serial_tx_active(&_serial)) {
mbed_official 525:c320967f86b9 116 return -1; // transaction ongoing
mbed_official 525:c320967f86b9 117 }
mbed_official 525:c320967f86b9 118 start_write((void *)buffer, length, 8, callback, event);
mbed_official 525:c320967f86b9 119 return 0;
mbed_official 525:c320967f86b9 120 }
mbed_official 525:c320967f86b9 121
mbed_official 563:536c9fb088a0 122 int SerialBase::write(const uint16_t *buffer, int length, const event_callback_t& callback, int event)
mbed_official 525:c320967f86b9 123 {
mbed_official 525:c320967f86b9 124 if (serial_tx_active(&_serial)) {
mbed_official 525:c320967f86b9 125 return -1; // transaction ongoing
mbed_official 525:c320967f86b9 126 }
mbed_official 525:c320967f86b9 127 start_write((void *)buffer, length, 16, callback, event);
mbed_official 525:c320967f86b9 128 return 0;
mbed_official 525:c320967f86b9 129 }
mbed_official 525:c320967f86b9 130
mbed_official 563:536c9fb088a0 131 void SerialBase::start_write(const void *buffer, int buffer_size, char buffer_width, const event_callback_t& callback, int event)
mbed_official 525:c320967f86b9 132 {
mbed_official 525:c320967f86b9 133 _tx_callback = callback;
mbed_official 525:c320967f86b9 134
mbed_official 525:c320967f86b9 135 _thunk_irq.callback(&SerialBase::interrupt_handler_asynch);
mbed_official 525:c320967f86b9 136 serial_tx_asynch(&_serial, buffer, buffer_size, buffer_width, _thunk_irq.entry(), event, _tx_usage);
mbed_official 525:c320967f86b9 137 }
mbed_official 525:c320967f86b9 138
mbed_official 525:c320967f86b9 139 void SerialBase::abort_write(void)
mbed_official 525:c320967f86b9 140 {
mbed_official 525:c320967f86b9 141 serial_tx_abort_asynch(&_serial);
mbed_official 525:c320967f86b9 142 }
mbed_official 525:c320967f86b9 143
mbed_official 525:c320967f86b9 144 void SerialBase::abort_read(void)
mbed_official 525:c320967f86b9 145 {
mbed_official 525:c320967f86b9 146 serial_rx_abort_asynch(&_serial);
mbed_official 525:c320967f86b9 147 }
mbed_official 525:c320967f86b9 148
mbed_official 525:c320967f86b9 149 int SerialBase::set_dma_usage_tx(DMAUsage usage)
mbed_official 525:c320967f86b9 150 {
mbed_official 525:c320967f86b9 151 if (serial_tx_active(&_serial)) {
mbed_official 525:c320967f86b9 152 return -1;
mbed_official 525:c320967f86b9 153 }
mbed_official 525:c320967f86b9 154 _tx_usage = usage;
mbed_official 525:c320967f86b9 155 return 0;
mbed_official 525:c320967f86b9 156 }
mbed_official 525:c320967f86b9 157
mbed_official 525:c320967f86b9 158 int SerialBase::set_dma_usage_rx(DMAUsage usage)
mbed_official 525:c320967f86b9 159 {
mbed_official 525:c320967f86b9 160 if (serial_tx_active(&_serial)) {
mbed_official 525:c320967f86b9 161 return -1;
mbed_official 525:c320967f86b9 162 }
mbed_official 525:c320967f86b9 163 _rx_usage = usage;
mbed_official 525:c320967f86b9 164 return 0;
mbed_official 525:c320967f86b9 165 }
mbed_official 525:c320967f86b9 166
mbed_official 525:c320967f86b9 167 int SerialBase::read(uint8_t *buffer, int length, const event_callback_t& callback, int event, unsigned char char_match)
mbed_official 525:c320967f86b9 168 {
mbed_official 525:c320967f86b9 169 if (serial_rx_active(&_serial)) {
mbed_official 525:c320967f86b9 170 return -1; // transaction ongoing
mbed_official 525:c320967f86b9 171 }
mbed_official 525:c320967f86b9 172 start_read((void*)buffer, length, 8, callback, event, char_match);
mbed_official 525:c320967f86b9 173 return 0;
mbed_official 525:c320967f86b9 174 }
mbed_official 525:c320967f86b9 175
mbed_official 525:c320967f86b9 176
mbed_official 525:c320967f86b9 177 int SerialBase::read(uint16_t *buffer, int length, const event_callback_t& callback, int event, unsigned char char_match)
mbed_official 525:c320967f86b9 178 {
mbed_official 525:c320967f86b9 179 if (serial_rx_active(&_serial)) {
mbed_official 525:c320967f86b9 180 return -1; // transaction ongoing
mbed_official 525:c320967f86b9 181 }
mbed_official 525:c320967f86b9 182 start_read((void*)buffer, length, 16, callback, event, char_match);
mbed_official 525:c320967f86b9 183 return 0;
mbed_official 525:c320967f86b9 184 }
mbed_official 525:c320967f86b9 185
mbed_official 525:c320967f86b9 186
mbed_official 525:c320967f86b9 187 void SerialBase::start_read(void *buffer, int buffer_size, char buffer_width, const event_callback_t& callback, int event, unsigned char char_match)
mbed_official 525:c320967f86b9 188 {
mbed_official 525:c320967f86b9 189 _rx_callback = callback;
mbed_official 525:c320967f86b9 190 _thunk_irq.callback(&SerialBase::interrupt_handler_asynch);
mbed_official 525:c320967f86b9 191 serial_rx_asynch(&_serial, buffer, buffer_size, buffer_width, _thunk_irq.entry(), event, char_match, _rx_usage);
mbed_official 525:c320967f86b9 192 }
mbed_official 525:c320967f86b9 193
mbed_official 525:c320967f86b9 194 void SerialBase::interrupt_handler_asynch(void)
mbed_official 525:c320967f86b9 195 {
mbed_official 525:c320967f86b9 196 int event = serial_irq_handler_asynch(&_serial);
mbed_official 525:c320967f86b9 197 int rx_event = event & SERIAL_EVENT_RX_MASK;
mbed_official 525:c320967f86b9 198 if (_rx_callback && rx_event) {
mbed_official 525:c320967f86b9 199 _rx_callback.call(rx_event);
mbed_official 525:c320967f86b9 200 }
mbed_official 525:c320967f86b9 201
mbed_official 525:c320967f86b9 202 int tx_event = event & SERIAL_EVENT_TX_MASK;
mbed_official 525:c320967f86b9 203 if (_tx_callback && tx_event) {
mbed_official 525:c320967f86b9 204 _tx_callback.call(tx_event);
mbed_official 525:c320967f86b9 205 }
mbed_official 525:c320967f86b9 206 }
mbed_official 525:c320967f86b9 207
mbed_official 525:c320967f86b9 208 #endif
mbed_official 525:c320967f86b9 209
mbed_official 36:ab3ee77451e7 210 } // namespace mbed
mbed_official 36:ab3ee77451e7 211
mbed_official 36:ab3ee77451e7 212 #endif