MEM: Introduce the master/slave port roles in the Python classes

This patch classifies all ports in Python as either Master or Slave
and enforces a binding of master to slave. Conceptually, a master (such
as a CPU or DMA port) issues requests, and receives responses, and
conversely, a slave (such as a memory or a PIO device) receives
requests and sends back responses. Currently there is no
differentiation between coherent and non-coherent masters and slaves.

The classification as master/slave also involves splitting the dual
role port of the bus into a master and slave port and updating all the
system assembly scripts to use the appropriate port. Similarly, the
interrupt devices have to have their int_port split into a master and
slave port. The intdev and its children have minimal changes to
facilitate the extra port.

Note that this patch does not enforce any port typing in the C++
world, it merely ensures that the Python objects have a notion of the
port roles and are connected in an appropriate manner. This check is
carried when two ports are connected, e.g. bus.master =
memory.port. The following patches will make use of the
classifications and specialise the C++ ports into masters and slaves.

1 files changed, 13 insertions, 2 deletions

diff --git a/src/mem/ruby/system/RubyPort.cc b/src/mem/ruby/system/RubyPort.cc
index ab3e6e3b7..2ef65a13a 100644
--- a/src/mem/ruby/system/RubyPort.cc
+++ b/src/mem/ruby/system/RubyPort.cc
@@ -68,13 +68,24 @@ RubyPort::init()
 Port *
 RubyPort::getPort(const std::string &if_name, int idx)
 {
-    if (if_name == "port") {
-        M5Port* cpuPort = new M5Port(csprintf("%s-port%d", name(), idx),
+    // used by the CPUs to connect the caches to the interconnect, and
+    // for the x86 case also the interrupt master
+    if (if_name == "slave") {
+        M5Port* cpuPort = new M5Port(csprintf("%s-slave%d", name(), idx),
                                      this, ruby_system, access_phys_mem);
         cpu_ports.push_back(cpuPort);
         return cpuPort;
     }
 
+    // used by the x86 CPUs to connect the interrupt PIO and interrupt slave
+    // port
+    if (if_name == "master") {
+        PioPort* masterPort = new PioPort(csprintf("%s-master%d", name(), idx),
+                                          this);
+
+        return masterPort;
+    }
+
     if (if_name == "pio_port") {
         // ensure there is only one pio port
         assert(pio_port == NULL);