Simplified FPU-LSU interface to skip IEU

pipelined/src/fpu/fpu.sv

@@ -42,10 +42,9 @@ module fpu (
   input logic  [1:0]       STATUS_FS,  // Is floating-point enabled? (From privileged unit)
   output logic 		      FRegWriteM, // FP register write enable (to privileged unit)
   output logic 		      FpLoadStoreM,  // Fp load instruction? (to LSU)
-  output logic             FStore2,       // store two words into memory (to LSU)
   output logic 		      FStallD,       // Stall the decode stage (To HZU)
   output logic 		      FWriteIntE,    // integer register write enable (to IEU)
-  output logic [`XLEN-1:0] FWriteDataE,   // Data to be written to memory (to IEU) - only used if `XLEN >`FLEN
+  output logic [`XLEN-1:0] FWriteDataE,   // Data to be written to memory (to IEU) - only used if `XLEN >`FLEN  *** delete this
   output logic [`FLEN-1:0] FWriteDataM,   // Data to be written to memory (to IEU) - only used if `XLEN <`FLEN
   output logic [`XLEN-1:0] FIntResM,      // data to be written to integer register (to IEU)
   output logic [`XLEN-1:0] FCvtIntResW,   // convert result to to be written to integer register (to IEU)
@@ -290,22 +289,18 @@ module fpu (
    //    - FP uses NaN-blocking format
    //        - if there are any unsused bits the most significant bits are filled with 1s
    
-   if(`LLEN==`XLEN)
+   logic [`FLEN-1:0] WriteDataE;
-      assign FWriteDataE = {{`XLEN-`FLEN{1'b1}}, YE};
+   if(`FPSIZES == 1) assign WriteDataE = YE;
-   else begin
+   else if(`FPSIZES == 2) assign WriteDataE = FmtE ? YE : {`FLEN/`LEN1{YE[`LEN1-1:0]}};
-      logic [`FLEN-1:0] WriteDataE;
+   else 
-      if(`FPSIZES == 1) assign WriteDataE = YE;
+      always_comb
-      else if(`FPSIZES == 2) assign WriteDataE = FmtE ? YE : {`FLEN/`LEN1{YE[`LEN1-1:0]}};
+            case(FmtE)
-      else 
+               `Q_FMT: WriteDataE = YE;
-         always_comb
+               `D_FMT: WriteDataE = {`FLEN/`D_LEN{YE[`D_LEN-1:0]}};
-               case(FmtE)
+               `S_FMT: WriteDataE = {`FLEN/`S_LEN{YE[`S_LEN-1:0]}};
-                  `Q_FMT: WriteDataE = YE;
+               `H_FMT: WriteDataE = {`FLEN/`H_LEN{YE[`H_LEN-1:0]}};
-                  `D_FMT: WriteDataE = {`FLEN/`D_LEN{YE[`D_LEN-1:0]}};
+            endcase
-                  `S_FMT: WriteDataE = {`FLEN/`S_LEN{YE[`S_LEN-1:0]}};
+   flopenrc #(`FLEN) EMWriteDataReg (clk, reset, FlushM, ~StallM, WriteDataE, FWriteDataM);
-                  `H_FMT: WriteDataE = {`FLEN/`H_LEN{YE[`H_LEN-1:0]}};
-               endcase
-      flopenrc #(`FLEN) EMWriteDataReg (clk, reset, FlushM, ~StallM, WriteDataE, FWriteDataM);
-   end
 
    // NaN Block SrcA
    generate

pipelined/src/hazard/hazard.sv

@@ -64,8 +64,10 @@ module hazard(
   assign StallFCause = CSRWriteFencePendingDEM & ~(TrapM | RetM | BPPredWrongE);
   // stall in decode if instruction is a load/mul/csr dependent on previous
   assign StallDCause = (LoadStallD | StoreStallD | MDUStallD | CSRRdStallD | FPUStallD | FStallD) & ~(TrapM | RetM | BPPredWrongE);    
+//  assign StallECause = (DivBusyE | FDivBusyE) & ~(TrapM);  // *** can we move to decode stage (KP?)
   assign StallECause = (DivBusyE) & ~(TrapM);  // *** can we move to decode stage (KP?)
   // WFI terminates if any enabled interrupt is pending, even if global interrupts are disabled.  It could also terminate with TW trap
+//  assign StallMCause = (wfiM & (~TrapM & ~IntPendingM)); // | FDivBusyE;  
   assign StallMCause = (wfiM & (~TrapM & ~IntPendingM)) | FDivBusyE;  
   assign StallWCause = LSUStallM | IFUStallF;
 

pipelined/src/ieu/datapath.sv

@@ -123,25 +123,18 @@ module datapath (
   flopenrc #(`XLEN) IFResultWReg(clk, reset, FlushW, ~StallW, IFResultM, IFResultW);
   flopenrc #(5)     RdWReg(clk, reset, FlushW, ~StallW, RdM, RdW);
 
-  // *** simplify WriteDataE in this merge
   // floating point interactions: fcvt, fp stores
-  if (`F_SUPPORTED&(`LLEN>`XLEN)) begin:fpmux
+  if (`F_SUPPORTED) begin:fpmux
     logic [`XLEN-1:0] IFCvtResultW;
     mux2  #(`XLEN)  resultmuxM(IEUResultM, FIntResM, FWriteIntM, IFResultM);
-    assign WriteDataE = ForwardedSrcBE;
-    mux2  #(`XLEN)  cvtresultmuxW(IFResultW, FCvtIntResW, ~FResSelW[1]&FResSelW[0], IFCvtResultW);
-    mux5  #(`XLEN)  resultmuxW(IFCvtResultW, ReadDataW, CSRReadValW, MDUResultW, SCResultW, ResultSrcW, ResultW); 
-  end else if (`F_SUPPORTED) begin:fpmux
-    logic [`XLEN-1:0] IFCvtResultW;
-    mux2  #(`XLEN)  resultmuxM(IEUResultM, FIntResM, FWriteIntM, IFResultM);
-    mux2  #(`XLEN)  writedatamux(ForwardedSrcBE, FWriteDataE, ~IllegalFPUInstrE, WriteDataE);
     mux2  #(`XLEN)  cvtresultmuxW(IFResultW, FCvtIntResW, ~FResSelW[1]&FResSelW[0], IFCvtResultW);
     mux5  #(`XLEN)  resultmuxW(IFCvtResultW, ReadDataW, CSRReadValW, MDUResultW, SCResultW, ResultSrcW, ResultW); 
   end else begin:fpmux
-    assign IFResultM = IEUResultM; assign WriteDataE = ForwardedSrcBE;
+    assign IFResultM = IEUResultM; 
     mux5  #(`XLEN)    resultmuxW(IFResultW, ReadDataW, CSRReadValW, MDUResultW, SCResultW, ResultSrcW, ResultW);	 
   end
-
+  assign WriteDataE = ForwardedSrcBE;
+ 
   // handle Store Conditional result if atomic extension supported
   if (`A_SUPPORTED) assign SCResultW = {{(`XLEN-1){1'b0}}, SquashSCW};
   else              assign SCResultW = 0;