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