add fabric compatibility mode

[soc.git] / src / soc / minerva / wishbone.py

diff --git a/src/soc/minerva/wishbone.py b/src/soc/minerva/wishbone.py
index ba08531e84965f785b154674875627c0a3053ffb..f249d5547330b632d0499f7917edca5dc15e259b 100644 (file)
--- a/src/soc/minerva/wishbone.py
+++ b/src/soc/minerva/wishbone.py
@@ -14,12 +14,18 @@ class Cycle:
     END       = 7
 
 
-def make_wb_layout(spec):
+def make_wb_layout(spec, cti=True):
     addr_wid, mask_wid, data_wid = spec.addr_wid, spec.mask_wid, spec.reg_wid
     adr_lsbs = log2_int(mask_wid) # LSBs of addr covered by mask
     badwid = spec.addr_wid-adr_lsbs    # MSBs (not covered by mask)
-
-    return [
+    # test if microwatt compatibility is to be enabled
+    microwatt_compat = (hasattr(spec, "microwatt_compat") and
+                               (spec.microwatt_compat == True))
+    # test if fabric compatibility is to be enabled
+    fabric_compat = (hasattr(spec, "fabric_compat") and
+                               (spec.fabric_compat == True))
+
+    res = [
     ("adr",   badwid  , DIR_FANOUT),
     ("dat_w", data_wid, DIR_FANOUT),
     ("dat_r", data_wid, DIR_FANIN),
@@ -28,10 +34,17 @@ def make_wb_layout(spec):
     ("stb",           1, DIR_FANOUT),
     ("ack",           1, DIR_FANIN),
     ("we",            1, DIR_FANOUT),
-    ("cti",           3, DIR_FANOUT),
-    ("bte",           2, DIR_FANOUT),
     ("err",           1, DIR_FANIN)
     ]
+    # microwatt needs a stall signal (operates in pipeline mode)
+    if microwatt_compat or fabric_compat:
+        res.append(("stall", 1, DIR_FANIN))
+    if not cti:
+        return res
+    return res + [
+        ("cti",           3, DIR_FANOUT),
+        ("bte",           2, DIR_FANOUT),
+    ]
 
 
 class WishboneArbiter(Elaboratable):