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Separated busdp for cache from simpler logic for no cache

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This commit is contained in:
David Harris 2022-08-25 17:54:04 -07:00
parent 5c1934208a
commit 0b918d6916
2 changed files with 38 additions and 16 deletions
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2
pipelined/src/ebu/ahblite.sv
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@ -127,7 +127,7 @@ module ahblite (
// Byte mask for HWSTRB based on delayed signals
flop #(ADRBITS) adrreg(HCLK, HADDR[ADRBITS-1:0], HADDRD);
flop #(2) sizereg(HCLK, HSIZE[1:0], HSIZED);
swbytemask swbytemask(.Size({1'b0, HSIZED}), .Adr(HADDRD), .ByteMask(HWSTRB));
swbytemask swbytemask(.Size({1'b0, HSIZED}), .Adr(HADDRD), .ByteMask(HWSTRB));
// Send control back to IFU and LSU
assign IFUBusInit = (BusState != INSTRREAD) & (NextBusState == INSTRREAD);

52
pipelined/src/lsu/lsu.sv
View File

@ -224,20 +224,6 @@ module lsu (
logic DCacheBusAck;
logic [LOGBWPL-1:0] WordCount;
busdp #(WORDSPERLINE, LINELEN, LOGBWPL, `DCACHE) busdp(
.clk, .reset,
.HRDATA, .BusAck(LSUBusAck), .BusInit(LSUBusInit), .BusWrite(LSUBusWrite),
.BusRead(LSUBusRead), .HSIZE(LSUHSIZE), .HBURST(LSUHBURST), .HTRANS(LSUHTRANS), .BusTransComplete(LSUTransComplete),
.WordCount, .SelBusWord,
.Funct3(LSUFunct3M), .HADDR(LSUHADDR), .CacheBusAdr(DCacheBusAdr), .CacheFetchLine(DCacheFetchLine),
.CacheWriteLine(DCacheWriteLine), .CacheBusAck(DCacheBusAck), .FetchBuffer, .PAdr(LSUPAdrM),
.SelUncachedAdr, .IgnoreRequest, .RW(LSURWM), .CPUBusy, .Cacheable(CacheableM),
.BusStall, .BusCommitted(BusCommittedM));
mux2 #(`LLEN) UnCachedDataMux(.d0(LittleEndianReadDataWordM), .d1({{`LLEN-`XLEN{1'b0}}, FetchBuffer[`XLEN-1:0]}),
.s(SelUncachedAdr), .y(ReadDataWordMuxM));
mux2 #(`XLEN) LSUHWDATAMux(.d0(ReadDataWordM[`XLEN-1:0]), .d1(LSUWriteDataM[`XLEN-1:0]),
.s(SelUncachedAdr), .y(LSUHWDATA));
if(`DCACHE) begin : dcache
cache #(.LINELEN(`DCACHE_LINELENINBITS), .NUMLINES(`DCACHE_WAYSIZEINBYTES*8/LINELEN),
.NUMWAYS(`DCACHE_NUMWAYS), .LOGBWPL(LOGBWPL), .WORDLEN(`LLEN), .MUXINTERVAL(`XLEN), .DCACHE(1)) dcache(
@ -250,8 +236,44 @@ module lsu (
.CacheBusAdr(DCacheBusAdr), .ReadDataWord(ReadDataWordM),
.FetchBuffer, .CacheFetchLine(DCacheFetchLine),
.CacheWriteLine(DCacheWriteLine), .CacheBusAck(DCacheBusAck), .InvalidateCache(1'b0));
busdp #(WORDSPERLINE, LINELEN, LOGBWPL, `DCACHE) busdp(
.clk, .reset,
.HRDATA, .BusAck(LSUBusAck), .BusInit(LSUBusInit), .BusWrite(LSUBusWrite),
.BusRead(LSUBusRead), .HSIZE(LSUHSIZE), .HBURST(LSUHBURST), .HTRANS(LSUHTRANS), .BusTransComplete(LSUTransComplete),
.WordCount, .SelBusWord,
.Funct3(LSUFunct3M), .HADDR(LSUHADDR), .CacheBusAdr(DCacheBusAdr), .CacheFetchLine(DCacheFetchLine),
.CacheWriteLine(DCacheWriteLine), .CacheBusAck(DCacheBusAck), .FetchBuffer, .PAdr(LSUPAdrM),
.SelUncachedAdr, .IgnoreRequest, .RW(LSURWM), .CPUBusy, .Cacheable(CacheableM),
.BusStall, .BusCommitted(BusCommittedM));
end else begin : passthrough
mux2 #(`LLEN) UnCachedDataMux(.d0(LittleEndianReadDataWordM), .d1({{`LLEN-`XLEN{1'b0}}, FetchBuffer[`XLEN-1:0]}),
.s(SelUncachedAdr), .y(ReadDataWordMuxM));
mux2 #(`XLEN) LSUHWDATAMux(.d0(ReadDataWordM[`XLEN-1:0]), .d1(LSUWriteDataM[`XLEN-1:0]),
.s(SelUncachedAdr), .y(LSUHWDATA));
end else begin : passthrough // just needs a register to hold the value from the bus
logic BufferCaptureEn;
flopen #(`XLEN) fb(.clk, .en(BufferCaptureEn), .d(HRDATA), .q(ReadDataWordMuxM));
assign LSUHWDATA = LSUWriteDataM[`XLEN-1:0];
busfsm #(0, LOGBWPL, `DCACHE) busfsm(
.clk, .reset, .IgnoreRequest, .RW(LSURWM), .CacheFetchLine(DCacheFetchLine), .CacheWriteLine(DCacheWriteLine),
.BusAck(LSUBusAck), .BusInit(LSUBusInit), .CPUBusy, .Cacheable(1'b0), .BusStall, .BusWrite(LSUBusWrite),
.SelBusWord, .BusRead(LSUBusRead), .BufferCaptureEn,
.HBURST(LSUHBURST), .HTRANS(LSUHTRANS), .BusTransComplete(LSUTransComplete),
.CacheBusAck(DCacheBusAck), .BusCommitted(BusCommittedM), .SelUncachedAdr, .WordCount(), .WordCountDelayed());
/* busdp #(WORDSPERLINE, LINELEN, LOGBWPL, `DCACHE) busdp(
.clk, .reset,
.HRDATA, .BusAck(LSUBusAck), .BusInit(LSUBusInit), .BusWrite(LSUBusWrite),
.BusRead(LSUBusRead), .HSIZE(LSUHSIZE), .HBURST(LSUHBURST), .HTRANS(LSUHTRANS), .BusTransComplete(LSUTransComplete),
.WordCount, .SelBusWord,
.Funct3(LSUFunct3M), .HADDR(LSUHADDR), .CacheBusAdr(DCacheBusAdr), .CacheFetchLine(DCacheFetchLine),
.CacheWriteLine(DCacheWriteLine), .CacheBusAck(DCacheBusAck), .FetchBuffer, .PAdr(LSUPAdrM),
.SelUncachedAdr, .IgnoreRequest, .RW(LSURWM), .CPUBusy, .Cacheable(CacheableM),
.BusStall, .BusCommitted(BusCommittedM)); */
// *** possible bug - ReadDatWordM vs. ReadDataWordMuxW - is byte swapping needed for endian
assign {ReadDataWordM, DCacheStallM, DCacheCommittedM, DCacheFetchLine, DCacheWriteLine} = '0;
assign DCacheMiss = CacheableM; assign DCacheAccess = CacheableM;
end