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Moved all remaining bus logic from the LSU into ahbcacheinterface.

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This commit is contained in:
Ross Thompson 2022-11-11 14:30:32 -06:00
parent c2e3bad3f5
commit 90697ef888
3 changed files with 41 additions and 35 deletions
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40
pipelined/src/ebu/ahbcacheinterface.sv
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@ -40,16 +40,21 @@ module ahbcacheinterface #(parameter BEATSPERLINE, LINELEN, LOGWPL, CACHE_ENABLE
// bus interface
input logic HREADY,
input logic [`XLEN-1:0] HRDATA,
input logic [`AHBW-1:0] HRDATA,
output logic [2:0] HSIZE,
output logic [2:0] HBURST,
output logic [1:0] HTRANS,
output logic HWRITE,
output logic [`PA_BITS-1:0] HADDR,
output logic [`AHBW-1:0] HWDATA,
output logic [`AHBW/8-1:0] HWSTRB,
output logic [LOGWPL-1:0] BeatCount,
// cache interface
input logic [`PA_BITS-1:0] CacheBusAdr,
input logic [`LLEN-1:0] CacheReadDataWordM,
input logic [`LLEN-1:0] WriteDataM,
input logic CacheableOrFlushCacheM,
input logic [1:0] CacheBusRW,
output logic CacheBusAck,
output logic [LINELEN-1:0] FetchBuffer,
@ -65,23 +70,48 @@ module ahbcacheinterface #(parameter BEATSPERLINE, LINELEN, LOGWPL, CACHE_ENABLE
output logic BusStall,
output logic BusCommitted);
localparam integer LLENPOVERAHBW = `LLEN / `AHBW; // *** fix me duplciated in lsu.
localparam integer BeatCountThreshold = CACHE_ENABLED ? BEATSPERLINE - 1 : 0;
logic [`PA_BITS-1:0] LocalHADDR;
logic [LOGWPL-1:0] BeatCountDelayed;
logic CaptureEn;
logic [`AHBW-1:0] PreHWDATA;
genvar index;
for (index = 0; index < BEATSPERLINE; index++) begin:fetchbuffer
logic [BEATSPERLINE-1:0] CaptureBeat;
assign CaptureBeat[index] = CaptureEn & (index == BeatCountDelayed);
flopen #(`XLEN) fb(.clk(HCLK), .en(CaptureBeat[index]), .d(HRDATA),
.q(FetchBuffer[(index+1)*`XLEN-1:index*`XLEN]));
flopen #(`AHBW) fb(.clk(HCLK), .en(CaptureBeat[index]), .d(HRDATA),
.q(FetchBuffer[(index+1)*`AHBW-1:index*`AHBW]));
end
mux2 #(`PA_BITS) localadrmux(PAdr, CacheBusAdr, Cacheable, LocalHADDR);
assign HADDR = ({{`PA_BITS-LOGWPL{1'b0}}, BeatCount} << $clog2(`XLEN/8)) + LocalHADDR;
assign HADDR = ({{`PA_BITS-LOGWPL{1'b0}}, BeatCount} << $clog2(`AHBW/8)) + LocalHADDR;
mux2 #(3) sizemux(.d0(Funct3), .d1(`XLEN == 32 ? 3'b010 : 3'b011), .s(Cacheable), .y(HSIZE));
mux2 #(3) sizemux(.d0(Funct3), .d1(`AHBW == 32 ? 3'b010 : 3'b011), .s(Cacheable), .y(HSIZE));
// When AHBW is less than LLEN need extra muxes to select the subword from cache's read data.
logic [`AHBW-1:0] CacheReadDataWordAHB;
if(LLENPOVERAHBW > 1) begin
logic [`AHBW-1:0] AHBWordSets [(LLENPOVERAHBW)-1:0];
genvar index;
for (index = 0; index < LLENPOVERAHBW; index++) begin:readdatalinesetsmux
assign AHBWordSets[index] = CacheReadDataWordM[(index*`AHBW)+`AHBW-1: (index*`AHBW)];
end
assign CacheReadDataWordAHB = AHBWordSets[BeatCount[$clog2(LLENPOVERAHBW)-1:0]];
end else assign CacheReadDataWordAHB = CacheReadDataWordM[`AHBW-1:0];
mux2 #(`AHBW) HWDATAMux(.d0(CacheReadDataWordAHB), .d1(WriteDataM[`AHBW-1:0]),
.s(~(CacheableOrFlushCacheM)), .y(PreHWDATA));
flopen #(`AHBW) wdreg(HCLK, HREADY, PreHWDATA, HWDATA); // delay HWDATA by 1 cycle per spec
// *** bummer need a second byte mask for bus as it is AHBW rather than LLEN.
// probably can merge by muxing PAdrM's LLEN/8-1 index bit based on HTRANS being != 0.
logic [`AHBW/8-1:0] BusByteMaskM;
swbytemask #(`AHBW) busswbytemask(.Size(HSIZE), .Adr(HADDR[$clog2(`AHBW/8)-1:0]), .ByteMask(BusByteMaskM));
flopen #(`AHBW/8) HWSTRBReg(HCLK, HREADY, BusByteMaskM[`AHBW/8-1:0], HWSTRB);
buscachefsm #(BeatCountThreshold, LOGWPL, CACHE_ENABLED) AHBBuscachefsm(
.HCLK, .HRESETn, .Flush, .BusRW, .CPUBusy, .BusCommitted, .BusStall, .CaptureEn, .SelBusBeat,

6
pipelined/src/ifu/ifu.sv
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@ -238,10 +238,10 @@ module ifu (
ahbcacheinterface #(WORDSPERLINE, LINELEN, LOGBWPL, `ICACHE)
ahbcacheinterface(.HCLK(clk), .HRESETn(~reset),
.HRDATA,
.Flush(FlushW), .CacheBusRW, .HSIZE(IFUHSIZE), .HBURST(IFUHBURST), .HTRANS(IFUHTRANS),
.Flush(FlushW), .CacheBusRW, .HSIZE(IFUHSIZE), .HBURST(IFUHBURST), .HTRANS(IFUHTRANS), .HWSTRB(),
.Funct3(3'b010), .HADDR(IFUHADDR), .HREADY(IFUHREADY), .HWRITE(IFUHWRITE), .CacheBusAdr(ICacheBusAdr),
.BeatCount(), .Cacheable(CacheableF), .SelBusBeat(),
.CacheBusAck(ICacheBusAck),
.BeatCount(), .Cacheable(CacheableF), .SelBusBeat(), .WriteDataM('0),
.CacheBusAck(ICacheBusAck), .HWDATA(), .CacheableOrFlushCacheM(1'b0), .CacheReadDataWordM('0),
.FetchBuffer, .PAdr(PCPF),
.BusRW, .CPUBusy,
.BusStall, .BusCommitted(BusCommittedF));

30
pipelined/src/lsu/lsu.sv
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@ -233,7 +233,6 @@ module lsu (
logic [AHBWLOGBWPL-1:0] BeatCount;
logic DCacheBusAck;
logic SelBusBeat;
logic [`XLEN-1:0] PreHWDATA; //*** change name
logic [`XLEN/8-1:0] ByteMaskMDelay;
logic [1:0] CacheBusRW, BusRW;
localparam integer LLENPOVERAHBW = `LLEN / `AHBW;
@ -260,10 +259,10 @@ module lsu (
.CacheBusAck(DCacheBusAck), .InvalidateCache(1'b0));
ahbcacheinterface #(.BEATSPERLINE(BEATSPERLINE), .LINELEN(LINELEN), .LOGWPL(AHBWLOGBWPL), .CACHE_ENABLED(`DCACHE)) ahbcacheinterface(
.HCLK(clk), .HRESETn(~reset), .Flush(FlushW),
.HRDATA,
.HRDATA, .HWDATA(LSUHWDATA), .HWSTRB(LSUHWSTRB),
.HSIZE(LSUHSIZE), .HBURST(LSUHBURST), .HTRANS(LSUHTRANS), .HWRITE(LSUHWRITE), .HREADY(LSUHREADY),
.BeatCount, .SelBusBeat,
.Funct3(LSUFunct3M), .HADDR(LSUHADDR), .CacheBusAdr(DCacheBusAdr), .CacheBusRW,
.BeatCount, .SelBusBeat, .CacheReadDataWordM(DCacheReadDataWordM), .WriteDataM(LSUWriteDataM),
.Funct3(LSUFunct3M), .HADDR(LSUHADDR), .CacheBusAdr(DCacheBusAdr), .CacheBusRW, .CacheableOrFlushCacheM,
.CacheBusAck(DCacheBusAck), .FetchBuffer, .PAdr(PAdrM),
.Cacheable(CacheableOrFlushCacheM), .BusRW, .CPUBusy,
.BusStall, .BusCommitted(BusCommittedM));
@ -275,29 +274,6 @@ module lsu (
mux3 #(`LLEN) UnCachedDataMux(.d0(DCacheReadDataWordM), .d1({LLENPOVERAHBW{FetchBuffer[`XLEN-1:0]}}),
.d2({{`LLEN-`XLEN{1'b0}}, DTIMReadDataWordM[`XLEN-1:0]}),
.s({SelDTIM, ~(CacheableOrFlushCacheM)}), .y(ReadDataWordMuxM));
// When AHBW is less than LLEN need extra muxes to select the subword from cache's read data.
logic [`AHBW-1:0] DCacheReadDataWordAHB;
if(LLENPOVERAHBW > 1) begin
logic [`AHBW-1:0] AHBWordSets [(LLENPOVERAHBW)-1:0];
genvar index;
for (index = 0; index < LLENPOVERAHBW; index++) begin:readdatalinesetsmux
assign AHBWordSets[index] = DCacheReadDataWordM[(index*`AHBW)+`AHBW-1: (index*`AHBW)];
end
assign DCacheReadDataWordAHB = AHBWordSets[BeatCount[$clog2(LLENPOVERAHBW)-1:0]];
end else assign DCacheReadDataWordAHB = DCacheReadDataWordM[`AHBW-1:0];
mux2 #(`XLEN) LSUHWDATAMux(.d0(DCacheReadDataWordAHB), .d1(LSUWriteDataM[`AHBW-1:0]),
.s(~(CacheableOrFlushCacheM)), .y(PreHWDATA));
flopen #(`AHBW) wdreg(clk, LSUHREADY, PreHWDATA, LSUHWDATA); // delay HWDATA by 1 cycle per spec
// *** bummer need a second byte mask for bus as it is AHBW rather than LLEN.
// probably can merge by muxing PAdrM's LLEN/8-1 index bit based on HTRANS being != 0.
logic [`AHBW/8-1:0] BusByteMaskM;
swbytemask #(`AHBW) busswbytemask(.Size(LSUHSIZE), .Adr(PAdrM[$clog2(`AHBW/8)-1:0]), .ByteMask(BusByteMaskM));
flop #(`AHBW/8) HWSTRBReg(clk, BusByteMaskM[`AHBW/8-1:0], LSUHWSTRB);
end else begin : passthrough // just needs a register to hold the value from the bus
logic CaptureEn;
logic [1:0] BusRW;