add option to set small cache sizes in

[soc.git] / src / soc / experiment / dcache.py

diff --git a/src/soc/experiment/dcache.py b/src/soc/experiment/dcache.py
index ce1967bd771461f9c2d75c733953d140a37daded..82b983bd3fd0166235395a3a33d011049e4ab801 100644 (file)
--- a/src/soc/experiment/dcache.py
+++ b/src/soc/experiment/dcache.py
@@ -741,18 +741,36 @@ class DCache(Elaboratable, DCacheConfig):
 
         self.log_out   = Signal(20)
 
+        # test if small cache to be enabled
+        self.small_cache = (hasattr(pspec, "small_cache") and
+                                 (pspec.small_cache == True))
         # test if microwatt compatibility is to be enabled
         self.microwatt_compat = (hasattr(pspec, "microwatt_compat") and
                                  (pspec.microwatt_compat == True))
 
+        XLEN = pspec.XLEN
+        TLB_SET_SIZE = 16
+        TLB_NUM_WAYS = 2
+        NUM_LINES = 16
+        NUM_WAYS = 2
+
+        if self.small_cache:
+            # reduce way sizes and num lines to ridiculously small
+            TLB_SET_SIZE = 2
+            TLB_NUM_WAYS = 1
+            NUM_LINES = 2
+            NUM_WAYS = 1
         if self.microwatt_compat:
-            # reduce way sizes and num lines
-            super().__init__(NUM_LINES = 8,
-                              NUM_WAYS = 1,
-                              TLB_NUM_WAYS = 1,
-                              TLB_SET_SIZE=16) # XXX needs device-tree entry
-        else:
-            super().__init__()
+            # reduce way sizes
+            NUM_WAYS = 1
+            TLB_NUM_WAYS = 1
+
+        super().__init__(TLB_SET_SIZE=TLB_SET_SIZE,
+                         # XLEN=XLEN, # TODO
+                         TLB_NUM_WAYS = TLB_NUM_WAYS,
+                         NUM_LINES = NUM_LINES,
+                         NUM_WAYS = NUM_WAYS
+                        )
 
     def stage_0(self, m, r0, r1, r0_full):
         """Latch the request in r0.req as long as we're not stalling
@@ -847,7 +865,7 @@ class DCache(Elaboratable, DCacheConfig):
             return
 
         # suite of PLRUs with a selection and output mechanism
-        tlb_plrus = PLRUs(self.TLB_SET_SIZE, self.TLB_WAY_BITS)
+        tlb_plrus = PLRUs("d_tlb", self.TLB_SET_SIZE, self.TLB_WAY_BITS)
         m.submodules.tlb_plrus = tlb_plrus
         comb += tlb_plrus.way.eq(r1.tlb_hit.way)
         comb += tlb_plrus.valid.eq(r1.tlb_hit.valid)
@@ -953,7 +971,8 @@ class DCache(Elaboratable, DCacheConfig):
             return
 
         # suite of PLRUs with a selection and output mechanism
-        m.submodules.plrus = plrus = PLRUs(self.NUM_LINES, self.WAY_BITS)
+        m.submodules.plrus = plrus = PLRUs("dtag", self.NUM_LINES,
+                                                   self.WAY_BITS)
         comb += plrus.way.eq(r1.hit_way)
         comb += plrus.valid.eq(r1.cache_hit)
         comb += plrus.index.eq(r1.hit_index)
@@ -1589,20 +1608,14 @@ class DCache(Elaboratable, DCacheConfig):
                         pass
 
             with m.Case(State.RELOAD_WAIT_ACK):
-                ld_stbs_done = Signal()
-                # Requests are all sent if stb is 0
-                comb += ld_stbs_done.eq(~r1.wb.stb)
 
                 # If we are still sending requests, was one accepted?
                 with m.If((~bus.stall) & r1.wb.stb):
-                    # That was the last word?  We are done sending.
-                    # Clear stb and set ld_stbs_done so we can handle an
-                    # eventual last ack on the same cycle.
+                    # That was the last word?  We are done sending.  Clear stb
                     # sigh - reconstruct wb adr with 3 extra 0s at front
                     wb_adr = Cat(Const(0, self.ROW_OFF_BITS), r1.wb.adr)
                     with m.If(self.is_last_row_addr(wb_adr, r1.end_row_ix)):
                         sync += r1.wb.stb.eq(0)
-                        comb += ld_stbs_done.eq(1)
 
                     # Calculate the next row address in the current cache line
                     rlen = self.LINE_OFF_BITS-self.ROW_OFF_BITS
@@ -1641,7 +1654,7 @@ class DCache(Elaboratable, DCacheConfig):
                         sync += r1.use_forward1.eq(1)
 
                     # Check for completion
-                    with m.If(ld_stbs_done & lastrow):
+                    with m.If(lastrow):
                         # Complete wishbone cycle
                         sync += r1.wb.cyc.eq(0)