MEM: Make the bus bridge unidirectional and fixed address range

This patch makes the bus bridge uni-directional and specialises the
bus ports to be a master port and a slave port. This greatly
simplifies the assumptions on both sides as either port only has to
deal with requests or responses. The following patches introduce the
notion of master and slave ports, and would not be possible without
this split of responsibilities.

In making the bridge unidirectional, the address range mechanism of
the bridge is also changed. For the cases where communication is
taking place both ways, an additional bridge is needed. This causes
issues with the existing mechanism, as the busses cannot determine
when to stop iterating the address updates from the two bridges. To
avoid this issue, and also greatly simplify the specification, the
bridge now has a fixed set of address ranges, specified at creation
time.

1 files changed, 6 insertions, 10 deletions

diff --git a/src/mem/Bridge.py b/src/mem/Bridge.py
index b48e1684d..38b344613 100644
--- a/src/mem/Bridge.py
+++ b/src/mem/Bridge.py
@@ -31,16 +31,12 @@ from MemObject import MemObject
 
 class Bridge(MemObject):
     type = 'Bridge'
-    side_a = Port('Side A port')
-    side_b = Port('Side B port')
-    req_size_a = Param.Int(16, "The number of requests to buffer")
-    req_size_b = Param.Int(16, "The number of requests to buffer")
-    resp_size_a = Param.Int(16, "The number of requests to buffer")
-    resp_size_b = Param.Int(16, "The number of requests to buffer")
+    slave = Port('Slave port')
+    master = Port('Master port')
+    req_size = Param.Int(16, "The number of requests to buffer")
+    resp_size = Param.Int(16, "The number of requests to buffer")
     delay = Param.Latency('0ns', "The latency of this bridge")
     nack_delay = Param.Latency('0ns', "The latency of this bridge")
     write_ack = Param.Bool(False, "Should this bridge ack writes")
-    filter_ranges_a = VectorParam.AddrRange([],
-            "What addresses shouldn't be passed through the side of the bridge")
-    filter_ranges_b = VectorParam.AddrRange([],
-            "What addresses shouldn't be passed through the side of the bridge")
+    ranges = VectorParam.AddrRange([AllMemory],
+                                   "Address ranges to pass through the bridge")