Added comments to dtim and ahbcacheinterface.

pipelined/src/ebu/ahbcacheinterface.sv

@@ -33,37 +33,38 @@
 module ahbcacheinterface #(parameter BEATSPERLINE, LINELEN, LOGWPL, CACHE_ENABLED) (
   input  logic                 HCLK, HRESETn,
   // bus interface
-  input  logic                 HREADY,
+  input logic                 HREADY,                  // AHB peripheral ready
-  input  logic [`AHBW-1:0]     HRDATA,
+  input logic [`AHBW-1:0]     HRDATA,                  // AHB read data
-  output logic [2:0]           HSIZE,
+  output logic [2:0]          HSIZE,                   // AHB transaction width
-  output logic [2:0]           HBURST,
+  output logic [2:0]          HBURST,                  // AHB burst length
-  output logic [1:0]           HTRANS,
+  output logic [1:0]          HTRANS,                  // AHB transaction type, 00: IDLE, 10 NON_SEQ, 11 SEQ
-  output logic                 HWRITE,
+  output logic                HWRITE,                  // AHB 0: Read operation 1: Write operation 
-  output logic [`PA_BITS-1:0]  HADDR,
+  output logic [`PA_BITS-1:0] HADDR,                   // AHB address
-  output logic [`AHBW-1:0]     HWDATA,
+  output logic [`AHBW-1:0]    HWDATA,                  // AHB write data
-  output logic [`AHBW/8-1:0]   HWSTRB,
+  output logic [`AHBW/8-1:0]  HWSTRB,                  // AHB byte mask
-  output logic [LOGWPL-1:0]    BeatCount,
   
   // cache interface
-  input  logic [`PA_BITS-1:0]  CacheBusAdr,
+  input logic [`PA_BITS-1:0]  CacheBusAdr,             // Address of cache line
-  input  logic [`LLEN-1:0]     CacheReadDataWordM,
+  input logic [`LLEN-1:0]     CacheReadDataWordM,      // one word of cache line during a writeback
-  input  logic [`LLEN-1:0]     WriteDataM,
+  input logic                 CacheableOrFlushCacheM,  // Memory operation is cacheable or flushing D$
-  input  logic                 CacheableOrFlushCacheM,
+  input logic [1:0]           CacheBusRW,              // Cache bus operation, 01: writeback, 10: fetch
-  input  logic [1:0]           CacheBusRW,
+  output logic                CacheBusAck,             // Handshack to $ indicating bus transaction completed
-  output logic                 CacheBusAck,
+  output logic [LINELEN-1:0]  FetchBuffer,             // Register to hold beats of cache line as the arrive from bus
-  output logic [LINELEN-1:0]   FetchBuffer, 
+  output logic [LOGWPL-1:0]   BeatCount,               // Beat position within the cache line
-  input  logic                 Cacheable,
+  input logic                 Cacheable,               // Memory operation is cachable
+
+  // uncached interface 
+  input logic [`LLEN-1:0]     WriteDataM,              // IEU write data for uncached store
 
   // lsu/ifu interface
-  input  logic                 Flush,
+  input logic                 Flush,                   // Pipeline stage flush. Prevents bus transaction from starting
-  input  logic [`PA_BITS-1:0]  PAdr,
+  input logic [`PA_BITS-1:0]  PAdr,                    // Physical address of uncached memory operation
-  input  logic [1:0]           BusRW,
+  input logic [1:0]           BusRW,                   // 
   input logic                 Stall,
   input logic [2:0]           Funct3,
   output logic                SelBusBeat,
   output logic                BusStall,
-  output logic                 BusCommitted
+  output logic                BusCommitted);
-);
   
   localparam integer           LLENPOVERAHBW = `LLEN / `AHBW; // *** fix me duplciated in lsu.
 

pipelined/src/lsu/dtim.sv

@@ -26,14 +26,15 @@
 `include "wally-config.vh"
 
 module dtim(
-  input logic                clk, ce,
+  input logic 				 clk, 
-  input logic [1:0]          MemRWM,
+  input logic 				 ce,            // Chip Enable
-  input logic [`PA_BITS-1:0] Adr,
+  input logic [1:0] 		 MemRWM,        // Read/Write control
+  input logic [`PA_BITS-1:0] AdrM,          // Execution stage memory address
   input logic 				 FlushW, 
-  input logic [`LLEN-1:0]    WriteDataM,
+  input logic [`LLEN-1:0] 	 WriteDataM,    // Write data from IEU
-  input logic [`LLEN/8-1:0]  ByteMaskM,
+  input logic [`LLEN/8-1:0]  ByteMaskM,     // Selects which bytes within a word to write
-  output logic [`LLEN-1:0]   ReadDataWordM
+  output logic [`LLEN-1:0] 	 ReadDataWordM  // Read data before subword selection
-);
+  );
 
   logic                      we;
  
@@ -43,6 +44,6 @@ module dtim(
   assign we = MemRWM[0]  & ~FlushW;  // have to ignore write if Trap.
 
   ram1p1rwbe #(.DEPTH(`DTIM_RANGE/8), .WIDTH(`LLEN)) 
-    ram(.clk, .ce, .we, .bwe(ByteMaskM), .addr(Adr[ADDR_WDITH+OFFSET-1:OFFSET]), .dout(ReadDataWordM), .din(WriteDataM));
+    ram(.clk, .ce, .we, .bwe(ByteMaskM), .addr(AdrM[ADDR_WDITH+OFFSET-1:OFFSET]), .dout(ReadDataWordM), .din(WriteDataM));
 endmodule  
   

pipelined/src/lsu/lsu.sv

@@ -232,7 +232,7 @@ module lsu (
     // **** fix ReadDataWordM to be LLEN. ByteMask is wrong length.
     // **** create config to support DTIM with floating point.
     dtim dtim(.clk, .ce(~GatedStallW), .MemRWM(DTIMMemRWM),
-              .Adr(DTIMAdr), .FlushW, .WriteDataM(LSUWriteDataM), 
+              .AdrM(DTIMAdr), .FlushW, .WriteDataM(LSUWriteDataM), 
               .ReadDataWordM(DTIMReadDataWordM[`XLEN-1:0]), .ByteMaskM(ByteMaskM[`XLEN/8-1:0]));
   end else begin
   end