radioDevice: Introduce getTxGain() API

It will be used in later commits by radioInterfaceMulti.

Change-Id: Ie3caca8971ed1e5370dfed6fb60716a24e7d82a5

Transceiver52M/device/common/radioDevice.h

@@ -131,6 +131,9 @@ class RadioDevice {
   /** sets the transmit chan gain, returns the gain setting **/
   virtual double setTxGain(double dB, size_t chan = 0) = 0;
 
+  /** get transmit gain */
+  virtual double getTxGain(size_t chan = 0) = 0;
+
   /** return maximum Tx Gain **/
   virtual double maxTxGain(void) = 0;
 

Transceiver52M/device/lms/LMSDevice.h

@@ -162,6 +162,11 @@ public:
 	/** sets the transmit chan gain, returns the gain setting **/
 	double setTxGain(double dB, size_t chan = 0);
 
+	/** get transmit gain */
+	double getTxGain(size_t chan = 0) {
+		return tx_gains[chan];
+	}
+
 	/** return maximum Tx Gain **/
 	double maxTxGain(void);
 

Transceiver52M/device/uhd/UHDDevice.cpp

@@ -310,6 +310,19 @@ double uhd_device::getRxGain(size_t chan)
 	return rx_gains[chan];
 }
 
+double uhd_device::getTxGain(size_t chan)
+{
+	if (iface == MULTI_ARFCN)
+		chan = 0;
+
+	if (chan >= tx_gains.size()) {
+		LOGC(DDEV, ALERT) << "Requested non-existent channel " << chan;
+		return 0.0f;
+	}
+
+	return tx_gains[chan];
+}
+
 /*
     Parse the UHD device tree and mboard name to find out what device we're
     dealing with. We need the window type so that the transceiver knows how to

Transceiver52M/device/uhd/UHDDevice.h

@@ -96,6 +96,7 @@ public:
 	double minRxGain(void) { return rx_gain_min; }
 
 	double setTxGain(double db, size_t chan);
+	double getTxGain(size_t chan = 0);
 	double maxTxGain(void) { return tx_gain_max; }
 	double minTxGain(void) { return tx_gain_min; }
 

Transceiver52M/device/usrp1/USRPDevice.h

@@ -171,6 +171,9 @@ private:
   /** sets the transmit chan gain, returns the gain setting **/
   double setTxGain(double dB, size_t chan = 0);
 
+  /** get transmit gain */
+  double getTxGain(size_t chan = 0) { return txGain; }
+
   /** return maximum Tx Gain **/
   double maxTxGain(void);