systemc: Generalize working with the systemc python module from C++.

This change pulls the systemc python module creation code out of
sc_main and puts it into a more general purpose python.hh and
python.cc which can be used by other code to add other entries into
that module without having to track that in a central place.

This change also adds a mechanism for notifying C++ code that the
embedded python interpretter is up and ready to interact with in case
it needs to call some python only functionality. An example of that is
the code which tracks and then fixes the timescale for the simulator.

Change-Id: I9afcd5a089b21d23ebc1b5fdb6f643ae2f7e5f11
Reviewed-on: https://gem5-review.googlesource.com/12069
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/systemc/core/python.cc

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2018 Google, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Gabe Black
+ */
+
+#include "systemc/core/python.hh"
+
+#include <vector>
+
+#include "python/pybind11/pybind.hh"
+#include "sim/init.hh"
+
+namespace sc_gem5
+{
+
+namespace
+{
+
+std::vector<PythonReadyFunc *> pythonReadyFuncs;
+std::vector<PythonInitFunc *> pythonInitFuncs;
+
+void
+python_ready(pybind11::args args)
+{
+    for (auto &func: pythonReadyFuncs)
+        func->run();
+}
+
+void
+systemc_pybind(pybind11::module &m_internal)
+{
+    pybind11::module m = m_internal.def_submodule("systemc");
+    m.def("python_ready", &python_ready);
+    for (auto &func: pythonInitFuncs)
+        func->run(m);
+}
+EmbeddedPyBind embed_("systemc", &systemc_pybind);
+
+} // anonymous namespace
+
+PythonReadyFunc::PythonReadyFunc()
+{
+    pythonReadyFuncs.push_back(this);
+}
+
+PythonInitFunc::PythonInitFunc()
+{
+    pythonInitFuncs.push_back(this);
+}
+
+} // namespace sc_gem5