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 {
00126     core_util_critical_section_enter();
00127     _sigio_cb = func;
00128     if (_sigio_cb) {
00129         short current_events = poll(0x7FFF);
00130         if (current_events) {
00131             _sigio_cb();
00132         }
00133     }
00134     core_util_critical_section_exit();
00135 }
00136 
00137 ssize_t UARTSerial::write(const void *buffer, size_t length)
00138 {
00139     size_t data_written = 0;
00140     const char *buf_ptr = static_cast<const char *>(buffer);
00141 
00142     if (length == 0) {
00143         return 0;
00144     }
00145 
00146     api_lock();
00147 
00148     // Unlike read, we should write the whole thing if blocking. POSIX only
00149     // allows partial as a side-effect of signal handling; it normally tries to
00150     // write everything if blocking. Without signals we can always write all.
00151     while (data_written < length) {
00152 
00153         if (_txbuf.full()) {
00154             if (!_blocking) {
00155                 break;
00156             }
00157             do {
00158                 api_unlock();
00159                 wait_ms(1); // XXX todo - proper wait, WFE for non-rtos ?
00160                 api_lock();
00161             } while (_txbuf.full());
00162         }
00163 
00164         while (data_written < length && !_txbuf.full()) {
00165             _txbuf.push(*buf_ptr++);
00166             data_written++;
00167         }
00168 
00169         core_util_critical_section_enter();
00170         if (!_tx_irq_enabled) {
00171             UARTSerial::tx_irq();                // only write to hardware in one place
00172             if (!_txbuf.empty()) {
00173                 SerialBase::attach(callback(this, &UARTSerial::tx_irq), TxIrq);
00174                 _tx_irq_enabled = true;
00175             }
00176         }
00177         core_util_critical_section_exit();
00178     }
00179 
00180     api_unlock();
00181 
00182     return data_written != 0 ? (ssize_t) data_written : (ssize_t) - EAGAIN;
00183 }
00184 
00185 ssize_t UARTSerial::read(void *buffer, size_t length)
00186 {
00187     size_t data_read = 0;
00188 
00189     char *ptr = static_cast<char *>(buffer);
00190 
00191     if (length == 0) {
00192         return 0;
00193     }
00194 
00195     api_lock();
00196 
00197     while (_rxbuf.empty()) {
00198         if (!_blocking) {
00199             api_unlock();
00200             return -EAGAIN;
00201         }
00202         api_unlock();
00203         wait_ms(1);  // XXX todo - proper wait, WFE for non-rtos ?
00204         api_lock();
00205     }
00206 
00207     while (data_read < length && !_rxbuf.empty()) {
00208         _rxbuf.pop(*ptr++);
00209         data_read++;
00210     }
00211 
00212     core_util_critical_section_enter();
00213     if (!_rx_irq_enabled) {
00214         UARTSerial::rx_irq();               // only read from hardware in one place
00215         if (!_rxbuf.full()) {
00216             SerialBase::attach(callback(this, &UARTSerial::rx_irq), RxIrq);
00217             _rx_irq_enabled = true;
00218         }
00219     }
00220     core_util_critical_section_exit();
00221 
00222     api_unlock();
00223 
00224     return data_read;
00225 }
00226 
00227 bool UARTSerial::hup() const
00228 {
00229     return _dcd_irq && _dcd_irq->read() != 0;
00230 }
00231 
00232 void UARTSerial::wake()
00233 {
00234     if (_sigio_cb) {
00235         _sigio_cb();
00236     }
00237 }
00238 
00239 short UARTSerial::poll(short events) const
00240 {
00241 
00242     short revents = 0;
00243     /* Check the Circular Buffer if space available for writing out */
00244 
00245 
00246     if (!_rxbuf.empty()) {
00247         revents |= POLLIN;
00248     }
00249 
00250     /* POLLHUP and POLLOUT are mutually exclusive */
00251     if (hup()) {
00252         revents |= POLLHUP;
00253     } else if (!_txbuf.full()) {
00254         revents |= POLLOUT;
00255     }
00256 
00257     /*TODO Handle other event types */
00258 
00259     return revents;
00260 }
00261 
00262 void UARTSerial::lock()
00263 {
00264     // This is the override for SerialBase.
00265     // No lock required as we only use SerialBase from interrupt or from
00266     // inside our own critical section.
00267 }
00268 
00269 void UARTSerial::unlock()
00270 {
00271     // This is the override for SerialBase.
00272 }
00273 
00274 void UARTSerial::api_lock(void)
00275 {
00276     _mutex.lock();
00277 }
00278 
00279 void UARTSerial::api_unlock(void)
00280 {
00281     _mutex.unlock();
00282 }
00283 
00284 void UARTSerial::rx_irq(void)
00285 {
00286     bool was_empty = _rxbuf.empty();
00287 
00288     /* Fill in the receive buffer if the peripheral is readable
00289      * and receive buffer is not full. */
00290     while (!_rxbuf.full() && SerialBase::readable()) {
00291         char data = SerialBase::_base_getc();
00292         _rxbuf.push(data);
00293     }
00294 
00295     if (_rx_irq_enabled && _rxbuf.full()) {
00296         SerialBase::attach(NULL, RxIrq);
00297         _rx_irq_enabled = false;
00298     }
00299 
00300     /* Report the File handler that data is ready to be read from the buffer. */
00301     if (was_empty && !_rxbuf.empty()) {
00302         wake();
00303     }
00304 }
00305 
00306 // Also called from write to start transfer
00307 void UARTSerial::tx_irq(void)
00308 {
00309     bool was_full = _txbuf.full();
00310     char data;
00311 
00312     /* Write to the peripheral if there is something to write
00313      * and if the peripheral is available to write. */
00314     while (SerialBase::writeable() && _txbuf.pop(data)) {
00315         SerialBase::_base_putc(data);
00316     }
00317 
00318     if (_tx_irq_enabled && _txbuf.empty()) {
00319         SerialBase::attach(NULL, TxIrq);
00320         _tx_irq_enabled = false;
00321     }
00322 
00323     /* Report the File handler that data can be written to peripheral. */
00324     if (was_full && !_txbuf.full() && !hup()) {
00325         wake();
00326     }
00327 }
00328 
00329 void UARTSerial::wait_ms(uint32_t millisec)
00330 {
00331     /* wait_ms implementation for RTOS spins until exact microseconds - we
00332      * want to just sleep until next tick.
00333      */
00334 #if MBED_CONF_RTOS_PRESENT
00335     rtos::Thread::wait(millisec);
00336 #else
00337     ::wait_ms(millisec);
00338 #endif
00339 }
00340 } //namespace mbed
00341 
00342 #endif //(DEVICE_SERIAL && DEVICE_INTERRUPTIN)