systemc: Hook up gem5_getPort to the gem5 getPort mechanism.

Change-Id: I771607c4436f4c1ca9d355d1da52924308cfc3b3
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17229
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Remove _m5.systemc passthroughs from SystemC_Kernel.

These functions are now exposed through m5.systemc and m5.tlm.

Change-Id: I9f519debbe7380ee38594badcc1146e66e15f8a8
Reviewed-on: https://gem5-review.googlesource.com/c/16570
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

systemc: Export the tlm::tlm_global_quantum class to python.

This way the python code can set up the global quantum without having
an sc_main function to do it.

Change-Id: I96df4dea0f1bfe9e3e86d4784bbda8f5b6b74d0b
Reviewed-on: https://gem5-review.googlesource.com/c/16503
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

systemc: Export the sc_core::sc_time class to python.

This class isn't incredibly useful in python, but it's needed to call
some other functions which are more useful.

Change-Id: I5c23cca0b50f0455423399db8b009bdf86a6ec41
Reviewed-on: https://gem5-review.googlesource.com/c/16502
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Add a python config class for sc_modules.

This class doesn't really add anything, but it provides a consistent
base class for sc_modules vs. generic sc_objects.

Change-Id: I3fbd4f6b5d1be0b5419f5cbd304aec61d404a341
Reviewed-on: https://gem5-review.googlesource.com/c/13355
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Keep track of how sc_main completes and expose that to python.

That makes it possible for the config script to retrieve the result of
running sc_main. sc_main (or at least the python front end for it)
can't return results directly since it usually doesn't run to
completion when it's first called.

Change-Id: I9740e9688571e2ca824a684be70480f1eadddcdb
Reviewed-on: https://gem5-review.googlesource.com/12253
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

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>

systemc: Implement the various sc_module stage callbacks.

This change also gets rid of the SystemC namespace which was
deprecated in favor of sc_gem5.

A few utility functions which check whether certain callbacks have
finished were also implemented. status tracking moved from a global
variable in sc_main.cc to a member of the kernel simobject.

Change-Id: I50967fae9c576fbe45b1faff587aaa824857a289
Reviewed-on: https://gem5-review.googlesource.com/12033
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Seperate the "external" header interface.

Most (but not all) of the SystemC headers are part of the "external"
interface that an existing, standard compliant module would include
through <systemc.h> or <systemc>. Since those follow slightly different
rules (relative includes, no gem5 includes), this change separates them
out so that they're easier to identify.

Also, this change moves the other files into a "core" subdirectory,
with the intention to add a "dt", aka data type, directory some time in
the future when those standard defined types are implemented.

Change-Id: Ida63f9cc0bc0431024d4dd691cc5b22b944a99a8
Reviewed-on: https://gem5-review.googlesource.com/10835
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>