rfnoc: Add shutdown feature to blocks

On destruction, the rfnoc_graph will call shutdown() on all blocks. This
allows a safe de-initialization of blocks independent of the lifetime of
the noc_block_base::sptr.

Also adds the shutdown feature to null_block_control.

11 files changed, 91 insertions, 3 deletions

diff --git a/host/include/uhd/rfnoc/noc_block_base.hpp b/host/include/uhd/rfnoc/noc_block_base.hpp
index e951ffc72..45a1f5738 100644
--- a/host/include/uhd/rfnoc/noc_block_base.hpp
+++ b/host/include/uhd/rfnoc/noc_block_base.hpp
@@ -160,6 +160,25 @@ protected:
      */
     std::shared_ptr<mb_controller> get_mb_controller();
 
+    /*! Safely de-initialize the block
+     *
+     * This function is called by the framework when the RFNoC session is about
+     * to finish to allow blocks to safely perform actions to shut down a block.
+     * For example, if your block is producing samples, like a radio or signal
+     * generator, this is a good place to issue a "stop" command.
+     *
+     * After this function is called, register access is no more possible. So
+     * make sure not to interact with regs() after this was called. Future
+     * access to regs() won't throw, but will print error messages and do
+     * nothing.
+     *
+     * The rationale for having this separate from the destructor is because
+     * rfnoc_graph allows exporting references to blocks, and this function
+     * ensures that blocks are safely shut down when the rest of the device
+     * control goes away.
+     */
+    virtual void deinit();
+
 private:
     /*! Update the tick rate of this block
      *
@@ -168,6 +187,16 @@ private:
      */
     void _set_tick_rate(const double tick_rate);
 
+    /*! Perform a shutdown sequence.
+     *
+     * - Call deinit()
+     * - Invalidate regs()
+     */
+    void shutdown();
+
+    /**************************************************************************
+     * Attributes
+     **************************************************************************/
     //! This block's Noc-ID
     noc_id_t _noc_id;
 
diff --git a/host/include/uhd/rfnoc/node.hpp b/host/include/uhd/rfnoc/node.hpp
index f9a1272e1..04b3d863f 100644
--- a/host/include/uhd/rfnoc/node.hpp
+++ b/host/include/uhd/rfnoc/node.hpp
@@ -350,6 +350,13 @@ protected:
     virtual bool check_topology(const std::vector<size_t>& connected_inputs,
         const std::vector<size_t>& connected_outputs);
 
+    /*! Perform a shutdown sequence
+     *
+     * This is mostly relevant for noc_block_base implementations. See also
+     * noc_block_base::shutdown().
+     */
+    virtual void shutdown();
+
     /**************************************************************************
      * Attributes
      *************************************************************************/
diff --git a/host/lib/include/uhdlib/rfnoc/block_container.hpp b/host/lib/include/uhdlib/rfnoc/block_container.hpp
index e32feed52..b43a7bc61 100644
--- a/host/lib/include/uhdlib/rfnoc/block_container.hpp
+++ b/host/lib/include/uhdlib/rfnoc/block_container.hpp
@@ -43,6 +43,12 @@ public:
      */
     noc_block_base::sptr get_block(const block_id_t& block_id) const;
 
+    /*! Call shutdown() on all blocks
+     *
+     * After calling this, blocks won't be able to do anything anymore!
+     */
+    void shutdown();
+
 private:
     //! Lock access to the storage
     mutable std::mutex _mutex;
diff --git a/host/lib/include/uhdlib/rfnoc/node_accessor.hpp b/host/lib/include/uhdlib/rfnoc/node_accessor.hpp
index 3351c5531..93e2733cf 100644
--- a/host/lib/include/uhdlib/rfnoc/node_accessor.hpp
+++ b/host/lib/include/uhdlib/rfnoc/node_accessor.hpp
@@ -108,6 +108,15 @@ public:
     {
         return node->check_topology(connected_inputs, connected_outputs);
     }
+
+    /*! Put a node into shutdown
+     *
+     * See node_t::shutdown(), and also noc_block_base::shutdown() for details.
+     */
+    void shutdown(node_t* node)
+    {
+        node->shutdown();
+    }
 };
 
 
diff --git a/host/lib/rfnoc/block_container.cpp b/host/lib/rfnoc/block_container.cpp
index 0151b228b..6bbb3828b 100644
--- a/host/lib/rfnoc/block_container.cpp
+++ b/host/lib/rfnoc/block_container.cpp
@@ -6,6 +6,7 @@
 
 #include <uhd/utils/log.hpp>
 #include <uhdlib/rfnoc/block_container.hpp>
+#include <uhdlib/rfnoc/node_accessor.hpp>
 #include <boost/format.hpp>
 #include <algorithm>
 
@@ -72,3 +73,11 @@ noc_block_base::sptr block_container_t::get_block(const block_id_t& block_id) co
     return *block_itr;
 }
 
+void block_container_t::shutdown()
+{
+    node_accessor_t node_accessor{};
+    for (auto it = _blocks.begin(); it != _blocks.end(); ++it) {
+        node_accessor.shutdown(it->get());
+    }
+
+}
diff --git a/host/lib/rfnoc/noc_block_base.cpp b/host/lib/rfnoc/noc_block_base.cpp
index 6e72decfe..c0d8cf2a9 100644
--- a/host/lib/rfnoc/noc_block_base.cpp
+++ b/host/lib/rfnoc/noc_block_base.cpp
@@ -113,7 +113,20 @@ void noc_block_base::_set_tick_rate(const double tick_rate)
     _tick_rate = tick_rate;
 }
 
+void noc_block_base::shutdown()
+{
+    RFNOC_LOG_TRACE("Calling deinit()");
+    deinit();
+    RFNOC_LOG_DEBUG("Invalidating register interface");
+    update_reg_iface();
+}
+
 std::shared_ptr<mb_controller> noc_block_base::get_mb_controller()
 {
     return _mb_controller;
 }
+
+void noc_block_base::deinit()
+{
+    RFNOC_LOG_DEBUG("deinit() called, but not implemented.");
+}
diff --git a/host/lib/rfnoc/node.cpp b/host/lib/rfnoc/node.cpp
index 7eff22eab..b3ad2b380 100644
--- a/host/lib/rfnoc/node.cpp
+++ b/host/lib/rfnoc/node.cpp
@@ -540,6 +540,11 @@ void node_t::receive_action(const res_source_info& src_info, action_info::sptr a
     }
 }
 
+void node_t::shutdown()
+{
+    RFNOC_LOG_DEBUG("shutdown() not implemented.");
+}
+
 bool node_t::_has_port(const res_source_info& port_info) const
 {
     return (port_info.type == res_source_info::INPUT_EDGE
diff --git a/host/lib/rfnoc/null_block_control.cpp b/host/lib/rfnoc/null_block_control.cpp
index be0738b76..21042453d 100644
--- a/host/lib/rfnoc/null_block_control.cpp
+++ b/host/lib/rfnoc/null_block_control.cpp
@@ -162,9 +162,11 @@ private:
             });
     }
 
-    /**************************************************************************
-     * FPGA communication (register IO)
-     *************************************************************************/
+    void deinit()
+    {
+        issue_stream_cmd(stream_cmd_t::STREAM_MODE_STOP_CONTINUOUS);
+    }
+
 
     /**************************************************************************
      * Attributes
diff --git a/host/lib/rfnoc/rfnoc_graph.cpp b/host/lib/rfnoc/rfnoc_graph.cpp
index 201920366..5b2277284 100644
--- a/host/lib/rfnoc/rfnoc_graph.cpp
+++ b/host/lib/rfnoc/rfnoc_graph.cpp
@@ -38,6 +38,7 @@ public:
     ~rfnoc_graph_impl()
     {
         _graph.reset();
+        _block_registry->shutdown();
     }
 
     /**************************************************************************
diff --git a/host/tests/CMakeLists.txt b/host/tests/CMakeLists.txt
index df891b7e2..d6ad6d777 100644
--- a/host/tests/CMakeLists.txt
+++ b/host/tests/CMakeLists.txt
@@ -252,6 +252,7 @@ UHD_ADD_NONAPI_TEST(
     ${CMAKE_SOURCE_DIR}/lib/rfnoc/ddc_block_control.cpp
     ${CMAKE_SOURCE_DIR}/lib/rfnoc/null_block_control.cpp
     ${CMAKE_SOURCE_DIR}/lib/rfnoc/radio_control_impl.cpp
+    ${CMAKE_SOURCE_DIR}/lib/rfnoc/register_iface_holder.cpp
     ${CMAKE_SOURCE_DIR}/lib/usrp/cores/dsp_core_utils.cpp
 )
 
diff --git a/host/tests/rfnoc_blocks_test.cpp b/host/tests/rfnoc_blocks_test.cpp
index 1832fc6ae..b69b6f9f8 100644
--- a/host/tests/rfnoc_blocks_test.cpp
+++ b/host/tests/rfnoc_blocks_test.cpp
@@ -125,6 +125,12 @@ BOOST_AUTO_TEST_CASE(test_null_block)
     stream_cmd.stream_mode = stream_cmd_t::STREAM_MODE_START_CONTINUOUS;
     test_null->issue_stream_cmd(stream_cmd);
     BOOST_CHECK_EQUAL(get_mem(null_block_control::REG_CTRL_STATUS) & 0x2, 0x2);
+    node_accessor.shutdown(test_null.get());
+    BOOST_CHECK_EQUAL(get_mem(null_block_control::REG_CTRL_STATUS) & 0x2, 0x0);
+    test_null->issue_stream_cmd(stream_cmd);
+    UHD_LOG_INFO("TEST", "Expected error message here ^^^");
+    // The last issue_stream_cmd should do nothing b/c we called shutdown
+    BOOST_CHECK_EQUAL(get_mem(null_block_control::REG_CTRL_STATUS) & 0x2, 0x0);
 }
 
 BOOST_AUTO_TEST_CASE(test_ddc_block)