1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/core/src/DataCacheBlocking.bsv	Tue Apr 13 17:34:33 2010 -0400
     1.3 @@ -0,0 +1,295 @@
     1.4 +// The MIT License
     1.5 +
     1.6 +// Copyright (c) 2009 Massachusetts Institute of Technology
     1.7 +
     1.8 +// Permission is hereby granted, free of charge, to any person obtaining a copy
     1.9 +// of this software and associated documentation files (the "Software"), to deal
    1.10 +// in the Software without restriction, including without limitation the rights
    1.11 +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    1.12 +// copies of the Software, and to permit persons to whom the Software is
    1.13 +// furnished to do so, subject to the following conditions:
    1.14 +
    1.15 +// The above copyright notice and this permission notice shall be included in
    1.16 +// all copies or substantial portions of the Software.
    1.17 +
    1.18 +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    1.19 +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    1.20 +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    1.21 +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    1.22 +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    1.23 +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    1.24 +// THE SOFTWARE.
    1.25 +
    1.26 +import Connectable::*;
    1.27 +import GetPut::*;
    1.28 +import ClientServer::*;
    1.29 +import RegFile::*;
    1.30 +import FIFO::*;
    1.31 +import FIFOF::*;
    1.32 +
    1.33 +import BFIFO::*;
    1.34 +import MemTypes::*;
    1.35 +import ProcTypes::*;
    1.36 +import Trace::*;
    1.37 +
    1.38 +interface DCacheStats;
    1.39 +    interface Get#(Stat) num_accesses;
    1.40 +    interface Get#(Stat) num_misses;
    1.41 +    interface Get#(Stat) num_writebacks; 
    1.42 +endinterface
    1.43 +
    1.44 +interface DCache#( type req_t, type resp_t );
    1.45 +
    1.46 +  // Interface from processor to cache
    1.47 +  interface Server#(req_t,resp_t) proc_server;
    1.48 +
    1.49 +  // Interface from cache to main memory
    1.50 +  interface Client#(MainMemReq,MainMemResp) mmem_client;
    1.51 +
    1.52 +  // Interface for enabling/disabling statistics
    1.53 +  interface Put#(Bool) statsEn_put;
    1.54 +
    1.55 +  // Interface for collecting statistics
    1.56 +  interface DCacheStats stats;
    1.57 +
    1.58 +endinterface
    1.59 +
    1.60 +
    1.61 +//----------------------------------------------------------------------
    1.62 +// Cache Types
    1.63 +//----------------------------------------------------------------------
    1.64 +
    1.65 +typedef 10   CacheLineIndexSz;
    1.66 +typedef 20   CacheLineTagSz;
    1.67 +typedef 32   CacheLineSz;
    1.68 +
    1.69 +typedef Bit#(CacheLineIndexSz) CacheLineIndex;
    1.70 +typedef Bit#(CacheLineTagSz)   CacheLineTag;
    1.71 +typedef Bit#(CacheLineSz)      CacheLine;
    1.72 +
    1.73 +typedef enum 
    1.74 +{ 
    1.75 +  Init,
    1.76 +  Access, 
    1.77 +  RefillReq, 
    1.78 +  RefillResp 
    1.79 +} 
    1.80 +CacheStage 
    1.81 +deriving (Eq,Bits);
    1.82 +
    1.83 +//----------------------------------------------------------------------
    1.84 +// Helper functions
    1.85 +//----------------------------------------------------------------------
    1.86 +
    1.87 +function Bit#(AddrSz) getAddr( DataReq req );
    1.88 +
    1.89 +  Bit#(AddrSz) addr = ?;
    1.90 +  case ( req ) matches
    1.91 +    tagged LoadReq  .ld : addr = ld.addr;
    1.92 +    tagged StoreReq .st : addr = st.addr;
    1.93 +  endcase
    1.94 +
    1.95 +  return addr;
    1.96 +
    1.97 +endfunction
    1.98 +
    1.99 +function CacheLineIndex getCacheLineIndex( DataReq req );
   1.100 +  Bit#(AddrSz) addr = getAddr(req);
   1.101 +  Bit#(CacheLineIndexSz) index = truncate( addr >> 2 );
   1.102 +  return index;
   1.103 +endfunction
   1.104 +
   1.105 +function CacheLineTag getCacheLineTag( DataReq req );
   1.106 +  Bit#(AddrSz)         addr = getAddr(req);
   1.107 +  Bit#(CacheLineTagSz) tag  = truncate( addr >> fromInteger(valueOf(CacheLineIndexSz)) >> 2 );
   1.108 +  return tag;
   1.109 +endfunction
   1.110 +
   1.111 +function Bit#(AddrSz) getCacheLineAddr( DataReq req );
   1.112 +  Bit#(AddrSz) addr = getAddr(req);
   1.113 +  return ((addr >> 2) << 2);
   1.114 +endfunction
   1.115 +
   1.116 +//----------------------------------------------------------------------
   1.117 +// Main module
   1.118 +//----------------------------------------------------------------------
   1.119 +
   1.120 +(* doc = "synthesis attribute ram_style mkDataCache distributed;" *)
   1.121 +(* synthesize *)
   1.122 +module mkDataCache( DCache#(DataReq,DataResp) );
   1.123 +
   1.124 +  //-----------------------------------------------------------
   1.125 +  // State
   1.126 +
   1.127 +  Reg#(CacheStage) stage <- mkReg(Init);
   1.128 +
   1.129 +  RegFile#(CacheLineIndex,Maybe#(CacheLineTag)) cacheTagRam  <- mkRegFileFull();
   1.130 +  RegFile#(CacheLineIndex,CacheLine)            cacheDataRam <- mkRegFileFull();
   1.131 +
   1.132 +  FIFO#(DataReq)   reqQ  <- mkFIFO();
   1.133 +  FIFOF#(DataResp) respQ <- mkBFIFOF1();
   1.134 +
   1.135 +  FIFO#(MainMemReq)  mainMemReqQ  <- mkBFIFO1();
   1.136 +  FIFO#(MainMemResp) mainMemRespQ <- mkFIFO();
   1.137 +
   1.138 +  Reg#(CacheLineIndex) initCounter <- mkReg(1);
   1.139 +
   1.140 +  // Statistics state
   1.141 +
   1.142 +  Reg#(Bool)     statsEn        <- mkReg(False);
   1.143 +
   1.144 +  Reg#(Stat) num_accesses <- mkReg(0);
   1.145 +  Reg#(Stat) num_misses <- mkReg(0);
   1.146 +  Reg#(Stat) num_writebacks <- mkReg(0);
   1.147 +
   1.148 +  //-----------------------------------------------------------
   1.149 +  // Name some wires
   1.150 +
   1.151 +  let req              = reqQ.first();
   1.152 +  let reqIndex         = getCacheLineIndex(req);
   1.153 +  let reqTag           = getCacheLineTag(req);
   1.154 +  let reqCacheLineAddr = getCacheLineAddr(req);
   1.155 +
   1.156 +  //-----------------------------------------------------------
   1.157 +  // Initialize
   1.158 +
   1.159 +  rule init ( stage == Init );
   1.160 +    traceTiny("mkDataCacheBlocking", "stage","i");
   1.161 +    initCounter <= initCounter + 1;
   1.162 +    cacheTagRam.upd(initCounter,Invalid);
   1.163 +    if ( initCounter == 0 )
   1.164 +      stage <= Access;
   1.165 +  endrule
   1.166 +   
   1.167 +  //-----------------------------------------------------------
   1.168 +  // Access cache rule
   1.169 +
   1.170 +  rule access ( (stage == Access) && respQ.notFull() );
   1.171 +
   1.172 +    // Statistics
   1.173 +
   1.174 +    if ( statsEn )
   1.175 +       num_accesses <= num_accesses + 1;
   1.176 + 
   1.177 +
   1.178 +    // Get the corresponding tag from the rams
   1.179 +
   1.180 +    Maybe#(CacheLineTag) cacheLineTag = cacheTagRam.sub(reqIndex);
   1.181 +  
   1.182 +    // Handle cache hits ...
   1.183 +
   1.184 +    if ( isValid(cacheLineTag) && ( unJust(cacheLineTag) == reqTag ) )
   1.185 +      begin
   1.186 +        traceTiny("mkDataCacheBlocking", "hitMiss","h");	 
   1.187 +        reqQ.deq();
   1.188 +
   1.189 +        case ( req ) matches
   1.190 +          
   1.191 +          tagged LoadReq .ld :
   1.192 +           respQ.enq( LoadResp { tag: ld.tag, data: cacheDataRam.sub(reqIndex) } );
   1.193 +
   1.194 +          tagged StoreReq .st :
   1.195 +	   begin
   1.196 +	     respQ.enq( StoreResp { tag : st.tag } );
   1.197 +             cacheDataRam.upd(reqIndex,st.data);
   1.198 +           end 
   1.199 +
   1.200 +        endcase
   1.201 +
   1.202 +      end
   1.203 +
   1.204 +    // Handle cache misses ...
   1.205 +    
   1.206 +    else 
   1.207 +      begin
   1.208 +        traceTiny("mkDataCacheBlocking", "hitMiss","m");
   1.209 +        if ( statsEn )
   1.210 +          num_misses <= num_misses + 1;
   1.211 +
   1.212 +        // Currently we don't use dirty bits so we always writeback the data if it is valid
   1.213 +
   1.214 +        if ( isValid(cacheLineTag) )
   1.215 +         begin
   1.216 +
   1.217 +           if ( statsEn )
   1.218 +             num_writebacks <= num_writebacks + 1;
   1.219 +
   1.220 +	   MainMemReq wbReq 
   1.221 +	    = StoreReq { tag  : 0, 
   1.222 +                         addr : { unJust(cacheLineTag), reqIndex, 2'b0 },
   1.223 +                         data : cacheDataRam.sub(reqIndex) };
   1.224 +	    
   1.225 +           mainMemReqQ.enq(wbReq);
   1.226 +           stage <= RefillReq;    
   1.227 +         end
   1.228 +
   1.229 +        // Otherwise we can issue the refill request now
   1.230 +
   1.231 +        else
   1.232 +         begin	    
   1.233 +           mainMemReqQ.enq( LoadReq { tag: 0, addr: reqCacheLineAddr } );
   1.234 +           stage <= RefillResp;    
   1.235 +         end
   1.236 +
   1.237 +      end
   1.238 +
   1.239 +  endrule
   1.240 +
   1.241 +  //-----------------------------------------------------------
   1.242 +  // Refill request rule
   1.243 +  
   1.244 +  rule refillReq ( stage == RefillReq );
   1.245 +    traceTiny("mkDataCacheBlocking", "stage","r");
   1.246 +    mainMemReqQ.enq( LoadReq { tag: 0, addr: reqCacheLineAddr } );
   1.247 +    stage <= RefillResp;
   1.248 +  endrule
   1.249 +
   1.250 +  //-----------------------------------------------------------
   1.251 +  // Refill response rule
   1.252 +  
   1.253 +  rule refillResp ( stage == RefillResp );
   1.254 +    traceTiny("mkDataCacheBlocking", "stage","R");
   1.255 +    traceTiny("mkDataCacheBlocking", "refill",mainMemRespQ.first());
   1.256 +
   1.257 +    // Write the new data into the cache and update the tag
   1.258 +
   1.259 +    mainMemRespQ.deq();
   1.260 +    case ( mainMemRespQ.first() ) matches
   1.261 +
   1.262 +      tagged LoadResp .ld :
   1.263 +       begin
   1.264 +	 cacheTagRam.upd(reqIndex,Valid(reqTag));
   1.265 +	 cacheDataRam.upd(reqIndex,ld.data);	
   1.266 +       end
   1.267 +       
   1.268 +      tagged StoreResp .st :
   1.269 +	noAction;
   1.270 +     
   1.271 +    endcase
   1.272 +
   1.273 +    stage <= Access;
   1.274 +  endrule
   1.275 +
   1.276 +  //-----------------------------------------------------------
   1.277 +  // Methods
   1.278 +
   1.279 +  interface Client mmem_client;
   1.280 +    interface Get request  = toGet(mainMemReqQ);
   1.281 +    interface Put response = toPut(mainMemRespQ);
   1.282 +  endinterface
   1.283 +
   1.284 +  interface Server proc_server;
   1.285 +    interface Put request  = tracePut("mkDataCacheBlocking", "reqTiny",toPut(reqQ));
   1.286 +    interface Get response = traceGet("mkDataCacheBlocking", "respTiny",toGet(respQ));
   1.287 +  endinterface
   1.288 +
   1.289 +  interface Put statsEn_put = toPut(asReg(statsEn));
   1.290 +
   1.291 +  interface DCacheStats stats;
   1.292 +    interface Get num_accesses = toGet(asReg(num_accesses));
   1.293 +    interface Get num_misses = toGet(asReg(num_misses));
   1.294 +    interface Get num_writebacks = toGet(asReg(num_writebacks));
   1.295 +  endinterface
   1.296 +
   1.297 +endmodule
   1.298 +