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Slower but correct implementation of flush.

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This commit is contained in:
Ross Thompson 2022-01-05 16:57:22 -06:00
parent 0310df96a4
commit da585b30f9
3 changed files with 70 additions and 59 deletions
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29
pipelined/src/cache/cache.sv vendored
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@ -32,7 +32,6 @@ module cache #(parameter integer LINELEN,
(input logic clk,
input logic reset,
input logic CPUBusy,
// cpu side
input logic [1:0] RW,
input logic [1:0] Atomic,
@ -73,7 +72,7 @@ module cache #(parameter integer LINELEN,
localparam integer LOGWPL = $clog2(WORDSPERLINE);
localparam integer LOGXLENBYTES = $clog2(`XLEN/8);
localparam integer FlushAdrThreshold = NUMLINES;
localparam integer FlushAdrThreshold = NUMLINES - 1;
logic [1:0] SelAdr;
logic [INDEXLEN-1:0] RAdr;
@ -103,12 +102,10 @@ module cache #(parameter integer LINELEN,
logic [INDEXLEN-1:0] FlushAdr;
logic [INDEXLEN-1:0] FlushAdrP1;
logic [INDEXLEN-1:0] FlushAdrQ;
logic [INDEXLEN-1:0] FlushAdrMux;
logic SelLastFlushAdr;
logic FlushAdrCntEn;
logic FlushAdrCntRst;
logic FlushAdrFlag;
logic FlushWayFlag;
logic [NUMWAYS-1:0] FlushWay;
logic [NUMWAYS-1:0] NextFlushWay;
@ -126,13 +123,11 @@ module cache #(parameter integer LINELEN,
mux3 #(INDEXLEN)
AdrSelMux(.d0(LsuAdrE[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
.d1(PreLsuPAdrM[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
.d2(FlushAdrMux),
.d2(FlushAdr),
.s(SelAdr),
.y(RAdr));
mux2 #(INDEXLEN)
FlushAdrSelMux(.d0(FlushAdr), .d1(FlushAdrQ), .s(SelLastFlushAdr),
.y(FlushAdrMux));
cacheway #(.NUMLINES(NUMLINES), .LINELEN(LINELEN), .TAGLEN(TAGLEN),
.OFFSETLEN(OFFSETLEN), .INDEXLEN(INDEXLEN))
@ -218,7 +213,7 @@ module cache #(parameter integer LINELEN,
mux3 #(`PA_BITS) BaseAdrMux(.d0({LsuPAdrM[`PA_BITS-1:OFFSETLEN], {{OFFSETLEN}{1'b0}}}),
.d1({VictimTag, LsuPAdrM[INDEXLEN+OFFSETLEN-1:OFFSETLEN], {{OFFSETLEN}{1'b0}}}),
.d2({VictimTag, FlushAdrQ, {{OFFSETLEN}{1'b0}}}),
.d2({VictimTag, FlushAdr, {{OFFSETLEN}{1'b0}}}),
.s({SelFlush, SelEvict}),
.y(CacheBusAdr));
@ -228,17 +223,11 @@ module cache #(parameter integer LINELEN,
flopenr #(INDEXLEN)
FlushAdrReg(.clk,
.reset(reset | FlushAdrCntRst),
.en(FlushAdrCntEn & FlushWay[NUMWAYS-2]),
.en(FlushAdrCntEn),
.d(FlushAdrP1),
.q(FlushAdr));
assign FlushAdrP1 = FlushAdr + 1'b1;
flopenr #(INDEXLEN)
FlushAdrQReg(.clk,
.reset(reset | FlushAdrCntRst),
.en(FlushAdrCntEn),
.d(FlushAdr),
.q(FlushAdrQ));
flopenl #(NUMWAYS)
FlushWayReg(.clk,
@ -252,7 +241,9 @@ module cache #(parameter integer LINELEN,
assign NextFlushWay = {FlushWay[NUMWAYS-2:0], FlushWay[NUMWAYS-1]};
assign FlushAdrFlag = FlushAdr == FlushAdrThreshold[INDEXLEN-1:0] & FlushWay[NUMWAYS-1];
//assign FlushAdrFlag = FlushAdr == FlushAdrThreshold[INDEXLEN-1:0] & FlushWay[NUMWAYS-1];
assign FlushAdrFlag = FlushAdr == FlushAdrThreshold[INDEXLEN-1:0];
assign FlushWayFlag = FlushWay[NUMWAYS-1];
// controller
// *** fixme
@ -268,7 +259,7 @@ module cache #(parameter integer LINELEN,
.ClearValid, .SetDirty, .ClearDirty, .SRAMWordWriteEnableM,
.SRAMLineWriteEnableM, .SelEvict, .SelFlush,
.FlushAdrCntEn, .FlushWayCntEn, .FlushAdrCntRst,
.FlushWayCntRst, .FlushAdrFlag, .FlushCache, .SelLastFlushAdr,
.FlushWayCntRst, .FlushAdrFlag, .FlushWayFlag, .FlushCache,
.VDWriteEnable, .LRUWriteEn);

54
pipelined/src/cache/cachefsm.sv vendored
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@ -43,6 +43,7 @@ module cachefsm
input logic CacheHit,
input logic VictimDirty,
input logic FlushAdrFlag,
input logic FlushWayFlag,
// hazard outputs
output logic CacheStall,
@ -65,7 +66,6 @@ module cachefsm
output logic SelEvict,
output logic LRUWriteEn,
output logic SelFlush,
output logic SelLastFlushAdr,
output logic FlushAdrCntEn,
output logic FlushWayCntEn,
output logic FlushAdrCntRst,
@ -90,6 +90,8 @@ module cachefsm
STATE_CPU_BUSY_FINISH_AMO,
STATE_FLUSH,
STATE_FLUSH_CHECK,
STATE_FLUSH_INCR,
STATE_FLUSH_WRITE_BACK,
STATE_FLUSH_CLEAR_DIRTY} statetype;
@ -126,7 +128,6 @@ module cachefsm
NextState = STATE_READY;
CacheFetchLine = 1'b0;
CacheWriteLine = 1'b0;
SelLastFlushAdr = 1'b0;
case (CurrState)
STATE_READY: begin
@ -152,10 +153,9 @@ module cachefsm
// Flush dcache to next level of memory
else if(FlushCache) begin
NextState = STATE_FLUSH;
CacheStall = 1'b1;
SelAdr = 2'b10;
FlushAdrCntRst = 1'b1;
FlushWayCntRst = 1'b1;
CacheStall = 1'b1;
end
// amo hit
@ -338,33 +338,49 @@ module cachefsm
end
STATE_FLUSH: begin
// intialize flush counters
SelFlush = 1'b1;
CacheStall = 1'b1;
SelAdr = 2'b10;
NextState = STATE_FLUSH_CHECK;
end
STATE_FLUSH_CHECK: begin
CacheStall = 1'b1;
SelAdr = 2'b10;
SelFlush = 1'b1;
FlushAdrCntEn = 1'b1;
FlushWayCntEn = 1'b1;
SelLastFlushAdr = 1'b0;
if(VictimDirty) begin
NextState = STATE_FLUSH_WRITE_BACK;
FlushAdrCntEn = 1'b0;
FlushWayCntEn = 1'b0;
CacheWriteLine = 1'b1;
SelLastFlushAdr = 1'b1;
end else if (FlushAdrFlag) begin
end else if (FlushAdrFlag & FlushWayFlag) begin
NextState = STATE_READY;
CacheStall = 1'b0;
FlushAdrCntEn = 1'b0;
SelAdr = 2'b00;
FlushWayCntEn = 1'b0;
end else if(FlushWayFlag) begin
NextState = STATE_FLUSH_INCR;
FlushAdrCntEn = 1'b1;
FlushWayCntEn = 1'b1;
end else begin
NextState = STATE_FLUSH;
FlushWayCntEn = 1'b1;
NextState = STATE_FLUSH_CHECK;
end
end
STATE_FLUSH_INCR: begin
CacheStall = 1'b1;
SelAdr = 2'b10;
SelFlush = 1'b1;
FlushWayCntRst = 1'b1;
NextState = STATE_FLUSH_CHECK;
end
STATE_FLUSH_WRITE_BACK: begin
CacheStall = 1'b1;
SelAdr = 2'b10;
SelFlush = 1'b1;
SelLastFlushAdr = 1'b1;
if(CacheBusAck) begin
NextState = STATE_FLUSH_CLEAR_DIRTY;
end else begin
@ -378,16 +394,18 @@ module cachefsm
VDWriteEnable = 1'b1;
SelFlush = 1'b1;
SelAdr = 2'b10;
FlushAdrCntEn = 1'b0;
FlushWayCntEn = 1'b0;
SelLastFlushAdr = 1'b0;
if(FlushAdrFlag) begin
if(FlushAdrFlag & FlushWayFlag) begin
NextState = STATE_READY;
CacheStall = 1'b0;
SelAdr = 2'b00;
end else begin
NextState = STATE_FLUSH;
end else if (FlushWayFlag) begin
NextState = STATE_FLUSH_INCR;
FlushAdrCntEn = 1'b1;
FlushWayCntEn = 1'b1;
end else begin
NextState = STATE_FLUSH_CHECK;
FlushWayCntEn = 1'b1;
end
end

2
pipelined/src/cache/cacheway.sv vendored
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@ -135,6 +135,8 @@ module cacheway #(parameter NUMLINES=512, parameter LINELEN = 256, TAGLEN = 26,
end else begin:dirty
assign Dirty = 1'b0;
end
endmodule // DCacheMemWay