UARTSerial.cpp

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2017 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00017 #if (DEVICE_SERIAL && DEVICE_INTERRUPTIN)
00018 
00019 #include <errno.h>
00020 #include "UARTSerial.h"
00021 #include "platform/mbed_poll.h"
00022 
00023 #if MBED_CONF_RTOS_PRESENT
00024 #include "rtos/Thread.h"
00025 #else
00026 #include "platform/mbed_wait_api.h"
00027 #endif
00028 
00029 namespace mbed {
00030 
00031 UARTSerial::UARTSerial(PinName tx, PinName rx, int baud) :
00032         SerialBase(tx, rx, baud),
00033         _blocking(true),
00034         _tx_irq_enabled(false),
00035         _rx_irq_enabled(true),
00036         _dcd_irq(NULL)
00037 {
00038     /* Attatch IRQ routines to the serial device. */
00039     SerialBase::attach(callback(this, &UARTSerial::rx_irq), RxIrq);
00040 }
00041 
00042 UARTSerial::~UARTSerial()
00043 {
00044     delete _dcd_irq;
00045 }
00046 
00047 void UARTSerial::dcd_irq()
00048 {
00049     wake();
00050 }
00051 
00052 void UARTSerial::set_baud(int baud)
00053 {
00054     SerialBase::baud(baud);
00055 }
00056 
00057 void UARTSerial::set_data_carrier_detect(PinName dcd_pin, bool active_high)
00058 {
00059      delete _dcd_irq;
00060     _dcd_irq = NULL;
00061 
00062     if (dcd_pin != NC) {
00063         _dcd_irq = new InterruptIn(dcd_pin);
00064         if (active_high) {
00065             _dcd_irq->fall(callback(this, &UARTSerial::dcd_irq));
00066         } else {
00067             _dcd_irq->rise(callback(this, &UARTSerial::dcd_irq));
00068         }
00069     }
00070 }
00071 
00072 void UARTSerial::set_format(int bits, Parity parity, int stop_bits)
00073 {
00074     api_lock();
00075     SerialBase::format(bits, parity, stop_bits);
00076     api_unlock();
00077 }
00078 
00079 #if DEVICE_SERIAL_FC
00080 void UARTSerial::set_flow_control(Flow type, PinName flow1, PinName flow2)
00081 {
00082     api_lock();
00083     SerialBase::set_flow_control(type, flow1, flow2);
00084     api_unlock();
00085 }
00086 #endif
00087 
00088 int UARTSerial::close()
00089 {
00090     /* Does not let us pass a file descriptor. So how to close ?
00091      * Also, does it make sense to close a device type file descriptor*/
00092     return 0;
00093 }
00094 
00095 int UARTSerial::isatty()
00096 {
00097     return 1;
00098 
00099 }
00100 
00101 off_t UARTSerial::seek(off_t offset, int whence)
00102 {
00103     /*XXX lseek can be done theoratically, but is it sane to mark positions on a dynamically growing/shrinking
00104      * buffer system (from an interrupt context) */
00105     return -ESPIPE;
00106 }
00107 
00108 int UARTSerial::sync()
00109 {
00110     api_lock();
00111 
00112     while (!_txbuf.empty()) {
00113         api_unlock();
00114         // Doing better than wait would require TxIRQ to also do wake() when becoming empty. Worth it?
00115         wait_ms(1);
00116         api_lock();
00117     }
00118 
00119     api_unlock();
00120 
00121     return 0;
00122 }
00123 
00124 void UARTSerial::sigio(Callback<void()> func) {
00125     core_util_critical_section_enter();
00126     _sigio_cb = func;
00127     if (_sigio_cb) {
00128         short current_events = poll(0x7FFF);
00129         if (current_events) {
00130             _sigio_cb();
00131         }
00132     }
00133     core_util_critical_section_exit();
00134 }
00135 
00136 ssize_t UARTSerial::write(const void* buffer, size_t length)
00137 {
00138     size_t data_written = 0;
00139     const char *buf_ptr = static_cast<const char *>(buffer);
00140 
00141     api_lock();
00142 
00143     while (_txbuf.full()) {
00144         if (!_blocking) {
00145             api_unlock();
00146             return -EAGAIN;
00147         }
00148         api_unlock();
00149         wait_ms(1); // XXX todo - proper wait, WFE for non-rtos ?
00150         api_lock();
00151     }
00152 
00153     while (data_written < length && !_txbuf.full()) {
00154         _txbuf.push(*buf_ptr++);
00155         data_written++;
00156     }
00157 
00158     core_util_critical_section_enter();
00159     if (!_tx_irq_enabled) {
00160         UARTSerial::tx_irq();                // only write to hardware in one place
00161         if (!_txbuf.empty()) {
00162             SerialBase::attach(callback(this, &UARTSerial::tx_irq), TxIrq);
00163             _tx_irq_enabled = true;
00164         }
00165     }
00166     core_util_critical_section_exit();
00167 
00168     api_unlock();
00169 
00170     return data_written;
00171 }
00172 
00173 ssize_t UARTSerial::read(void* buffer, size_t length)
00174 {
00175     size_t data_read = 0;
00176 
00177     char *ptr = static_cast<char *>(buffer);
00178 
00179     api_lock();
00180 
00181     while (_rxbuf.empty()) {
00182         if (!_blocking) {
00183             api_unlock();
00184             return -EAGAIN;
00185         }
00186         api_unlock();
00187         wait_ms(1);  // XXX todo - proper wait, WFE for non-rtos ?
00188         api_lock();
00189     }
00190 
00191     while (data_read < length && !_rxbuf.empty()) {
00192         _rxbuf.pop(*ptr++);
00193         data_read++;
00194     }
00195 
00196     core_util_critical_section_enter();
00197     if (!_rx_irq_enabled) {
00198         UARTSerial::rx_irq();               // only read from hardware in one place
00199         if (!_rxbuf.full()) {
00200             SerialBase::attach(callback(this, &UARTSerial::rx_irq), RxIrq);
00201             _rx_irq_enabled = true;
00202         }
00203     }
00204     core_util_critical_section_exit();
00205 
00206     api_unlock();
00207 
00208     return data_read;
00209 }
00210 
00211 bool UARTSerial::hup() const
00212 {
00213     return _dcd_irq && _dcd_irq->read() != 0;
00214 }
00215 
00216 void UARTSerial::wake()
00217 {
00218     if (_sigio_cb) {
00219         _sigio_cb();
00220     }
00221 }
00222 
00223 short UARTSerial::poll(short events) const {
00224 
00225     short revents = 0;
00226     /* Check the Circular Buffer if space available for writing out */
00227 
00228 
00229     if (!_rxbuf.empty()) {
00230         revents |= POLLIN;
00231     }
00232 
00233     /* POLLHUP and POLLOUT are mutually exclusive */
00234     if (hup()) {
00235         revents |= POLLHUP;
00236     } else if (!_txbuf.full()) {
00237         revents |= POLLOUT;
00238     }
00239 
00240     /*TODO Handle other event types */
00241 
00242     return revents;
00243 }
00244 
00245 void UARTSerial::lock()
00246 {
00247     // This is the override for SerialBase.
00248     // No lock required as we only use SerialBase from interrupt or from
00249     // inside our own critical section.
00250 }
00251 
00252 void UARTSerial::unlock()
00253 {
00254     // This is the override for SerialBase.
00255 }
00256 
00257 void UARTSerial::api_lock(void)
00258 {
00259     _mutex.lock();
00260 }
00261 
00262 void UARTSerial::api_unlock(void)
00263 {
00264     _mutex.unlock();
00265 }
00266 
00267 void UARTSerial::rx_irq(void)
00268 {
00269     bool was_empty = _rxbuf.empty();
00270 
00271     /* Fill in the receive buffer if the peripheral is readable
00272      * and receive buffer is not full. */
00273     while (!_rxbuf.full() && SerialBase::readable()) {
00274         char data = SerialBase::_base_getc();
00275         _rxbuf.push(data);
00276     }
00277 
00278     if (_rx_irq_enabled && _rxbuf.full()) {
00279         SerialBase::attach(NULL, RxIrq);
00280         _rx_irq_enabled = false;
00281     }
00282 
00283     /* Report the File handler that data is ready to be read from the buffer. */
00284     if (was_empty && !_rxbuf.empty()) {
00285         wake();
00286     }
00287 }
00288 
00289 // Also called from write to start transfer
00290 void UARTSerial::tx_irq(void)
00291 {
00292     bool was_full = _txbuf.full();
00293 
00294     /* Write to the peripheral if there is something to write
00295      * and if the peripheral is available to write. */
00296     while (!_txbuf.empty() && SerialBase::writeable()) {
00297         char data;
00298         _txbuf.pop(data);
00299         SerialBase::_base_putc(data);
00300     }
00301 
00302     if (_tx_irq_enabled && _txbuf.empty()) {
00303         SerialBase::attach(NULL, TxIrq);
00304         _tx_irq_enabled = false;
00305     }
00306 
00307     /* Report the File handler that data can be written to peripheral. */
00308     if (was_full && !_txbuf.full() && !hup()) {
00309         wake();
00310     }
00311 }
00312 
00313 void UARTSerial::wait_ms(uint32_t millisec)
00314 {
00315     /* wait_ms implementation for RTOS spins until exact microseconds - we
00316      * want to just sleep until next tick.
00317      */
00318 #if MBED_CONF_RTOS_PRESENT
00319     rtos::Thread::wait(millisec);
00320 #else
00321     ::wait_ms(millisec);
00322 #endif
00323 }
00324 } //namespace mbed
00325 
00326 #endif //(DEVICE_SERIAL && DEVICE_INTERRUPTIN)