Free serial resources if not needed anymore

Author: Sebastian Stockhammer

drivers/SerialBase.h

@@ -295,6 +295,30 @@ class SerialBase : private NonCopyable<SerialBase> {
 
     int _base_putc(int c);
 
+    /** Initialize serial port
+     */
+    void _init();
+
+    /** Deinitialize serial port
+     */
+    void _deinit();
+
+    /** Enable serial input
+     *
+     * If both serial input and serial output are disabled, the
+     * peripheral is freed. If either serial input or serial
+     * output is re-enabled, the peripheral is reinitialized.
+     */
+    void _enable_input(bool enable = true);
+
+    /** Enable serial output
+     *
+     * If both serial input and serial output are disabled, the
+     * peripheral is freed. If either serial input or serial
+     * output is re-enabled, the peripheral is reinitialized.
+     */
+    void _enable_output(bool enable = true);
+
 #if DEVICE_SERIAL_ASYNCH
     CThunk<SerialBase> _thunk_irq;
     DMAUsage _tx_usage;
@@ -308,6 +332,10 @@ class SerialBase : private NonCopyable<SerialBase> {
     serial_t         _serial;
     Callback<void()> _irq[IrqCnt];
     int              _baud;
+    bool             _rx_enabled;
+    bool             _tx_enabled;
+    const PinName    _tx_pin;
+    const PinName    _rx_pin;
 #endif
 };
 

drivers/source/SerialBase.cpp

@@ -30,17 +30,15 @@ SerialBase::SerialBase(PinName tx, PinName rx, int baud) :
     _rx_callback(NULL), _tx_asynch_set(false),
     _rx_asynch_set(false),
 #endif
-    _serial(), _baud(baud)
+    _serial(), _baud(baud), _rx_enabled(true), _tx_enabled(true), _tx_pin(tx), _rx_pin(rx)
 {
     // No lock needed in the constructor
 
     for (size_t i = 0; i < sizeof _irq / sizeof _irq[0]; i++) {
         _irq[i] = NULL;
     }
 
-    serial_init(&_serial, tx, rx);
-    serial_baud(&_serial, _baud);
-    serial_irq_handler(&_serial, SerialBase::_irq_handler, (uint32_t)this);
+    _init();
 }
 
 void SerialBase::baud(int baudrate)
@@ -120,6 +118,74 @@ int SerialBase::_base_putc(int c)
     return c;
 }
 
+void SerialBase::_init()
+{
+    serial_init(&_serial, _tx_pin, _rx_pin);
+    serial_baud(&_serial, _baud);
+    serial_irq_handler(&_serial, SerialBase::_irq_handler, (uint32_t)this);
+}
+
+void SerialBase::_deinit()
+{
+    serial_free(&_serial);
+}
+
+void SerialBase::_enable_input(bool enable)
+{
+    if (_rx_enabled != enable) {
+        if(enable && !_tx_enabled) {
+            _init();
+        }
+
+        core_util_critical_section_enter();
+        if (enable) {
+            // Enable rx IRQ if attached (indicated by rx IRQ callback not NULL)
+            if(_irq[RxIrq]) {
+                _irq[RxIrq].call();
+                serial_irq_set(&_serial, (SerialIrq)RxIrq, 1);
+            }
+        } else {
+            // Disable rx IRQ
+            serial_irq_set(&_serial, (SerialIrq)RxIrq, 0);
+        }
+        core_util_critical_section_exit();
+
+        _rx_enabled = enable;
+
+        if (!enable && !_tx_enabled) {
+            _deinit();
+        }
+    }
+}
+
+void SerialBase::_enable_output(bool enable)
+{
+    if (_tx_enabled != enable) {
+        if(enable && !_rx_enabled) {
+            _init();
+        }
+
+        core_util_critical_section_enter();
+        if (enable) {
+            // Enable tx IRQ if attached (indicated by tx IRQ callback not NULL)
+            if(_irq[TxIrq]) {
+                _irq[TxIrq].call();
+                serial_irq_set(&_serial, (SerialIrq)TxIrq, 1);
+            }
+        } else {
+            // Disable tx IRQ
+            serial_irq_set(&_serial, (SerialIrq)TxIrq, 0);
+        }
+        core_util_critical_section_exit();
+
+        _tx_enabled = enable;
+
+        if (!enable && !_rx_enabled) {
+            _deinit();
+        }
+    }
+}
+
 void SerialBase::set_break()
 {
     lock();

drivers/source/UARTSerial.cpp

@@ -366,38 +366,18 @@ void UARTSerial::disable_tx_irq()
 
 int UARTSerial::enable_input(bool enabled)
 {
-    core_util_critical_section_enter();
-    if (_rx_enabled != enabled) {
-        if (enabled) {
-            UARTSerial::rx_irq();
-            if (!_rxbuf.full()) {
-                enable_rx_irq();
-            }
-        } else {
-            disable_rx_irq();
-        }
-        _rx_enabled = enabled;
-    }
-    core_util_critical_section_exit();
+    api_lock();
+    _enable_input(enabled);
+    api_unlock();
 
     return 0;
 }
 
 int UARTSerial::enable_output(bool enabled)
 {
-    core_util_critical_section_enter();
-    if (_tx_enabled != enabled) {
-        if (enabled) {
-            UARTSerial::tx_irq();
-            if (!_txbuf.empty()) {
-                enable_tx_irq();
-            }
-        } else {
-            disable_tx_irq();
-        }
-        _tx_enabled = enabled;
-    }
-    core_util_critical_section_exit();
+    api_lock();
+    _enable_input(enabled);
+    api_unlock();
 
     return 0;
 }