Slower but correct implementation of flush.

pipelined/src/cache/cache.sv

@@ -32,7 +32,6 @@ module cache #(parameter integer LINELEN,
   (input logic clk,
    input logic				   reset,
    input logic				   CPUBusy,
-
    // cpu side
    input logic [1:0]		   RW,
    input logic [1:0]		   Atomic,
@@ -73,7 +72,7 @@ module cache #(parameter integer LINELEN,
   localparam integer 						LOGWPL = $clog2(WORDSPERLINE);
   localparam integer 						LOGXLENBYTES = $clog2(`XLEN/8);
 
-  localparam integer 						FlushAdrThreshold   = NUMLINES;
+  localparam integer 						FlushAdrThreshold   = NUMLINES - 1;
 
   logic [1:0] 								SelAdr;
   logic [INDEXLEN-1:0] 						RAdr;
@@ -103,12 +102,10 @@ module cache #(parameter integer LINELEN,
 
   logic [INDEXLEN-1:0] 						FlushAdr;
   logic [INDEXLEN-1:0] 						FlushAdrP1;
-  logic [INDEXLEN-1:0] 						FlushAdrQ;
-  logic [INDEXLEN-1:0] 						FlushAdrMux;
-  logic 									SelLastFlushAdr;
   logic 									FlushAdrCntEn;
   logic 									FlushAdrCntRst;
   logic 									FlushAdrFlag;
+    logic 									FlushWayFlag;
   
   logic [NUMWAYS-1:0] 						FlushWay;
   logic [NUMWAYS-1:0] 						NextFlushWay;
@@ -126,13 +123,11 @@ module cache #(parameter integer LINELEN,
   mux3 #(INDEXLEN)
   AdrSelMux(.d0(LsuAdrE[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
 			.d1(PreLsuPAdrM[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
-			.d2(FlushAdrMux),
+			.d2(FlushAdr),
 			.s(SelAdr),
 			.y(RAdr));
 
-  mux2 #(INDEXLEN)
+   
-  FlushAdrSelMux(.d0(FlushAdr), .d1(FlushAdrQ), .s(SelLastFlushAdr), 
-				 .y(FlushAdrMux));
 
   cacheway #(.NUMLINES(NUMLINES), .LINELEN(LINELEN), .TAGLEN(TAGLEN), 
 			 .OFFSETLEN(OFFSETLEN), .INDEXLEN(INDEXLEN))
@@ -218,7 +213,7 @@ module cache #(parameter integer LINELEN,
   
   mux3 #(`PA_BITS) BaseAdrMux(.d0({LsuPAdrM[`PA_BITS-1:OFFSETLEN], {{OFFSETLEN}{1'b0}}}),
 							  .d1({VictimTag, LsuPAdrM[INDEXLEN+OFFSETLEN-1:OFFSETLEN], {{OFFSETLEN}{1'b0}}}),
-							  .d2({VictimTag, FlushAdrQ, {{OFFSETLEN}{1'b0}}}),
+							  .d2({VictimTag, FlushAdr, {{OFFSETLEN}{1'b0}}}),
 							  .s({SelFlush, SelEvict}),
 							  .y(CacheBusAdr));
 
@@ -228,17 +223,11 @@ module cache #(parameter integer LINELEN,
   flopenr #(INDEXLEN)
   FlushAdrReg(.clk,
 			  .reset(reset | FlushAdrCntRst),
-			  .en(FlushAdrCntEn & FlushWay[NUMWAYS-2]),
+			  .en(FlushAdrCntEn),
 			  .d(FlushAdrP1),
 			  .q(FlushAdr));
   assign FlushAdrP1 = FlushAdr + 1'b1;
 
-  flopenr #(INDEXLEN)
-  FlushAdrQReg(.clk,
-			  .reset(reset | FlushAdrCntRst),
-			  .en(FlushAdrCntEn),
-			  .d(FlushAdr),
-			  .q(FlushAdrQ));
 
   flopenl #(NUMWAYS)
   FlushWayReg(.clk,
@@ -252,7 +241,9 @@ module cache #(parameter integer LINELEN,
 
   assign NextFlushWay = {FlushWay[NUMWAYS-2:0], FlushWay[NUMWAYS-1]};
 
-  assign FlushAdrFlag = FlushAdr == FlushAdrThreshold[INDEXLEN-1:0] & FlushWay[NUMWAYS-1];
+  //assign FlushAdrFlag = FlushAdr == FlushAdrThreshold[INDEXLEN-1:0] & FlushWay[NUMWAYS-1];
+  assign FlushAdrFlag = FlushAdr == FlushAdrThreshold[INDEXLEN-1:0];
+  assign FlushWayFlag = FlushWay[NUMWAYS-1];
 
   // controller
   // *** fixme
@@ -268,7 +259,7 @@ module cache #(parameter integer LINELEN,
 					.ClearValid, .SetDirty, .ClearDirty, .SRAMWordWriteEnableM,
 					.SRAMLineWriteEnableM, .SelEvict, .SelFlush,
 					.FlushAdrCntEn, .FlushWayCntEn, .FlushAdrCntRst,
-					.FlushWayCntRst, .FlushAdrFlag, .FlushCache, .SelLastFlushAdr,
+					.FlushWayCntRst, .FlushAdrFlag, .FlushWayFlag, .FlushCache,
 					.VDWriteEnable, .LRUWriteEn);
   
 

pipelined/src/cache/cachefsm.sv

@@ -43,6 +43,7 @@ module cachefsm
    input logic 		  CacheHit,
    input logic 		  VictimDirty,
    input logic 		  FlushAdrFlag,
+   input logic 		  FlushWayFlag,   
   
    // hazard outputs
    output logic 	  CacheStall,
@@ -65,7 +66,6 @@ module cachefsm
    output logic 	  SelEvict,
    output logic 	  LRUWriteEn,
    output logic 	  SelFlush,
-   output logic 	  SelLastFlushAdr,
    output logic 	  FlushAdrCntEn,
    output logic 	  FlushWayCntEn, 
    output logic 	  FlushAdrCntRst,
@@ -90,6 +90,8 @@ module cachefsm
 					   STATE_CPU_BUSY_FINISH_AMO,
   
 					   STATE_FLUSH,
+					   STATE_FLUSH_CHECK,
+					   STATE_FLUSH_INCR,
 					   STATE_FLUSH_WRITE_BACK,
 					   STATE_FLUSH_CLEAR_DIRTY} statetype;
 
@@ -126,7 +128,6 @@ module cachefsm
     NextState = STATE_READY;
 	CacheFetchLine = 1'b0;
 	CacheWriteLine = 1'b0;
-	SelLastFlushAdr = 1'b0;
 
     case (CurrState)
       STATE_READY: begin
@@ -152,10 +153,9 @@ module cachefsm
 		// Flush dcache to next level of memory
 		else if(FlushCache) begin
 		  NextState = STATE_FLUSH;
-		  CacheStall = 1'b1;
-		  SelAdr = 2'b10;
 		  FlushAdrCntRst = 1'b1;
 		  FlushWayCntRst = 1'b1;	
+		  CacheStall = 1'b1;
 		end
 		
 		// amo hit
@@ -338,33 +338,49 @@ module cachefsm
       end
 
 	  STATE_FLUSH: begin
+		// intialize flush counters
+		SelFlush = 1'b1;
+		CacheStall = 1'b1;
+		SelAdr = 2'b10;
+		NextState = STATE_FLUSH_CHECK;
+	  end		
+
+      STATE_FLUSH_CHECK: begin
 		CacheStall = 1'b1;
 		SelAdr = 2'b10;
 		SelFlush = 1'b1;
-		FlushAdrCntEn = 1'b1;
-		FlushWayCntEn = 1'b1;
-		SelLastFlushAdr = 1'b0;
 		if(VictimDirty) begin
 		  NextState = STATE_FLUSH_WRITE_BACK;
-		  FlushAdrCntEn = 1'b0;
 		  FlushWayCntEn = 1'b0;
 		  CacheWriteLine = 1'b1;
-		  SelLastFlushAdr = 1'b1;
+		end else if (FlushAdrFlag & FlushWayFlag) begin
-		end else if (FlushAdrFlag) begin
 		  NextState = STATE_READY;
 		  CacheStall = 1'b0;
-		  FlushAdrCntEn = 1'b0;
+		  SelAdr = 2'b00;
 		  FlushWayCntEn = 1'b0;	
+		end else if(FlushWayFlag) begin
+		  NextState = STATE_FLUSH_INCR;
+		  FlushAdrCntEn = 1'b1;
+		  
+		  FlushWayCntEn = 1'b1;
 		end else begin
-		  NextState = STATE_FLUSH;
+		  FlushWayCntEn = 1'b1;
+		  NextState = STATE_FLUSH_CHECK;
 		end
       end
 	  
+	  STATE_FLUSH_INCR: begin
+		CacheStall = 1'b1;
+		SelAdr = 2'b10;
+		SelFlush = 1'b1;
+		FlushWayCntRst = 1'b1;
+		NextState = STATE_FLUSH_CHECK;
+	  end
+
       STATE_FLUSH_WRITE_BACK: begin
 		CacheStall = 1'b1;
 		SelAdr = 2'b10;
 		SelFlush = 1'b1;
-		SelLastFlushAdr = 1'b1;
 		if(CacheBusAck) begin
 		  NextState = STATE_FLUSH_CLEAR_DIRTY;
 		end else begin
@@ -378,16 +394,18 @@ module cachefsm
 		VDWriteEnable = 1'b1;
 		SelFlush = 1'b1;
 		SelAdr = 2'b10;
-		FlushAdrCntEn = 1'b0;
 		FlushWayCntEn = 1'b0;
-		SelLastFlushAdr = 1'b0;
+		if(FlushAdrFlag & FlushWayFlag) begin
-		if(FlushAdrFlag) begin
 		  NextState = STATE_READY;
 		  CacheStall = 1'b0;
 		  SelAdr = 2'b00;
-		end else begin
+		end else if (FlushWayFlag) begin
-		  NextState = STATE_FLUSH;
+		  NextState = STATE_FLUSH_INCR;
 		  FlushAdrCntEn = 1'b1;
+		  
+		  FlushWayCntEn = 1'b1;	
+		end else begin
+		  NextState = STATE_FLUSH_CHECK;
 		  FlushWayCntEn = 1'b1;	
 		end
       end

pipelined/src/cache/cacheway.sv

@@ -135,6 +135,8 @@ module cacheway #(parameter NUMLINES=512, parameter LINELEN = 256, TAGLEN = 26,
   end else begin:dirty
     assign Dirty = 1'b0;
   end
+
+  
 endmodule // DCacheMemWay