mg: Enable variable master clock rates

The master_clock_rate argument is passed to init() during
initialization; this change allows to query the correct MCR at
initialization time. It does not allow changing the MCR while a session
is active.

The MCR also affects the LO settings; it is the reference clock for the
lowband LOs.

4 files changed, 50 insertions, 9 deletions

diff --git a/host/lib/usrp/dboard/magnesium/magnesium_constants.hpp b/host/lib/usrp/dboard/magnesium/magnesium_constants.hpp
index 933866d92..581b1cc97 100644
--- a/host/lib/usrp/dboard/magnesium/magnesium_constants.hpp
+++ b/host/lib/usrp/dboard/magnesium/magnesium_constants.hpp
@@ -13,7 +13,6 @@
 
 static const size_t FPGPIO_MASTER_RADIO = 0;
 
-static const double MAGNESIUM_TICK_RATE = 125e6; // Hz
 static const double MAGNESIUM_RADIO_RATE = 125e6; // Hz
 static const double MAGNESIUM_MIN_FREQ = 1e6; // Hz
 static const double MAGNESIUM_MAX_FREQ = 6e9; // Hz
diff --git a/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_impl.cpp b/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_impl.cpp
index 8b722e725..3efe61676 100644
--- a/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_impl.cpp
+++ b/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_impl.cpp
@@ -27,6 +27,13 @@ namespace {
     /**************************************************************************
      * ADF4351 Controls
      *************************************************************************/
+    /*!
+     * \param lo_iface Reference to the LO object
+     * \param freq Frequency (in Hz) of the tone to be generated from the LO
+     * \param ref_clock_freq Frequency (in Hz) of the reference clock at the
+     *                       PLL input of the LO
+     * \param int_n_mode Integer-N mode on or off
+     */
     double _lo_set_frequency(
         adf435x_iface::sptr lo_iface,
         const double freq,
@@ -53,6 +60,17 @@ namespace {
         return actual_freq;
     }
 
+    /*! Configure and enable LO
+     *
+     * Will tune it to requested frequency and enable outputs.
+     *
+     * \param lo_iface Reference to the LO object
+     * \param lo_freq Frequency (in Hz) of the tone to be generated from the LO
+     * \param ref_clock_freq Frequency (in Hz) of the reference clock at the
+     *                       PLL input of the LO
+     * \param int_n_mode Integer-N mode on or off
+     * \returns the actual frequency the LO is running at
+     */
     double _lo_enable(
         adf435x_iface::sptr lo_iface,
         const double lo_freq,
@@ -67,6 +85,8 @@ namespace {
         return actual_lo_freq;
     }
 
+    /*! Disable LO
+     */
     void _lo_disable(adf435x_iface::sptr lo_iface)
     {
         lo_iface->set_output_enable(adf435x_iface::RF_OUTPUT_A, false);
@@ -192,9 +212,8 @@ double magnesium_radio_ctrl_impl::set_tx_frequency(
         if_freq = MAGNESIUM_TX_IF_FREQ ;
         const double lo_freq = if_freq - freq;
         const bool int_n_mode = false; // FIXME no hardcode
-        const double ref_clk_freq = 100e6; // FIXME no hardcode
         //const double actual_lo_freq =
-            _lo_enable(lo_iface, lo_freq, ref_clk_freq, int_n_mode);
+            _lo_enable(lo_iface, lo_freq, _master_clock_rate, int_n_mode);
         //ad9371_freq = actual_lo_freq - freq;
     } else {
         _lo_disable(lo_iface);
@@ -233,9 +252,8 @@ double magnesium_radio_ctrl_impl::set_rx_frequency(
         if_freq = MAGNESIUM_RX_IF_FREQ ;
         const double lo_freq = if_freq - freq;
         const bool int_n_mode = false; // FIXME no hardcode
-        const double ref_clk_freq = 100e6; // FIXME no hardcode
         //const double actual_lo_freq =
-            _lo_enable(lo_iface, lo_freq, ref_clk_freq, int_n_mode);
+            _lo_enable(lo_iface, lo_freq, _master_clock_rate, int_n_mode);
         //ad9371_freq = actual_lo_freq - freq;
     } else {
         _lo_disable(lo_iface);
@@ -401,6 +419,26 @@ void magnesium_radio_ctrl_impl::set_rpc_client(
         )
     );
 
+    // Note: MCR gets set during the init() call (prior to this), which takes
+    // in arguments from the device args. So if block_args contains a
+    // master_clock_rate key, then it should better be whatever the device is
+    // configured to do.
+    _master_clock_rate = _rpcc->request_with_token<double>(
+            _rpc_prefix + "get_master_clock_rate");
+    if (block_args.cast<double>("master_clock_rate", _master_clock_rate)
+            != _master_clock_rate) {
+        throw uhd::runtime_error(str(
+            boost::format("Master clock rate mismatch. Device returns %f MHz, "
+                          "but should have been %f MHz.")
+            % (_master_clock_rate / 1e6)
+            % (block_args.cast<double>(
+                    "master_clock_rate", _master_clock_rate) / 1e6)
+        ));
+    }
+    UHD_LOG_DEBUG(unique_id(),
+        "Master Clock Rate is: " << (_master_clock_rate / 1e6) << " MHz.");
+    radio_ctrl_impl::set_rate(_master_clock_rate);
+
     // EEPROM paths subject to change FIXME
     const size_t db_idx = get_block_id().get_block_count();
     _tree->access<eeprom_map_t>(_root_path / "eeprom")
diff --git a/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_impl.hpp b/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_impl.hpp
index e32c2d5c9..f1543077c 100644
--- a/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_impl.hpp
+++ b/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_impl.hpp
@@ -235,6 +235,9 @@ private:
     //  module can be the FP-GPIO master.
     usrp::gpio_atr::gpio_atr_3000::sptr _fp_gpio;
 
+    //! Sampling rate, and also ref clock frequency for the lowband LOs.
+    double _master_clock_rate = 1.0;
+
     //! AD9371 gain
     double _ad9371_rx_gain = 0.0;
     double _ad9371_tx_gain = 0.0;
diff --git a/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_init.cpp b/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_init.cpp
index 27cf926a2..191218133 100644
--- a/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_init.cpp
+++ b/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_init.cpp
@@ -37,9 +37,8 @@ void magnesium_radio_ctrl_impl::_init_defaults()
     UHD_LOG_TRACE(unique_id(),
             "Num TX chans: " << num_tx_chans
             << " Num RX chans: " << num_rx_chans);
-    UHD_LOG_TRACE(unique_id(),
-            "Setting tick rate to " << MAGNESIUM_TICK_RATE / 1e6 << " MHz");
-    radio_ctrl_impl::set_rate(MAGNESIUM_TICK_RATE);
+    // get_rate() is useless until we can ask MPM for the actual rate
+    radio_ctrl_impl::set_rate(1.0);
 
     for (size_t chan = 0; chan < num_rx_chans; chan++) {
         radio_ctrl_impl::set_rx_frequency(MAGNESIUM_CENTER_FREQ, chan);
@@ -397,7 +396,9 @@ void magnesium_radio_ctrl_impl::_init_prop_tree()
     // TODO remove this dirty hack
     if (not _tree->exists("tick_rate"))
     {
-        _tree->create<double>("tick_rate").set(MAGNESIUM_TICK_RATE);
+        _tree->create<double>("tick_rate")
+            .set_publisher([this](){ return this->get_rate(); })
+        ;
     }
 }