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Rough draft of cache flush fsm enhancement.

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This commit is contained in:
Ross Thompson 2022-12-16 15:28:22 -06:00
parent bc907f3e2f
commit dacba855da
3 changed files with 39 additions and 16 deletions
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16
pipelined/src/cache/cache.sv vendored
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@ -85,6 +85,7 @@ module cache #(parameter LINELEN, NUMLINES, NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
logic [TAGLEN-1:0] TagWay [NUMWAYS-1:0];
logic [TAGLEN-1:0] Tag;
logic [SETLEN-1:0] FlushAdr;
logic [SETLEN-1:0] OldFlushAdr, NextFlushAdr, RawFlushAdr;
logic [SETLEN-1:0] FlushAdrP1;
logic FlushAdrCntEn;
logic FlushAdrCntRst;
@ -102,6 +103,8 @@ module cache #(parameter LINELEN, NUMLINES, NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
logic [$clog2(LINELEN/8) - $clog2(MUXINTERVAL/8) - 1:0] WordOffsetAddr;
logic SelFetchBuffer;
logic CacheEn;
logic SelOldFlushAdr;
localparam LOGLLENBYTES = $clog2(WORDLEN/8);
localparam CACHEWORDSPERLINE = `DCACHE_LINELENINBITS/WORDLEN;
@ -181,10 +184,15 @@ module cache #(parameter LINELEN, NUMLINES, NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
/////////////////////////////////////////////////////////////////////////////////////////////
assign ResetOrFlushAdr = reset | FlushAdrCntRst;
flopenr #(SETLEN) FlushAdrReg(.clk, .reset(ResetOrFlushAdr), .en(FlushAdrCntEn),
.d(FlushAdrP1), .q(FlushAdr));
assign FlushAdrP1 = FlushAdr + 1'b1;
assign FlushAdrFlag = (FlushAdr == FlushAdrThreshold[SETLEN-1:0]);
.d(FlushAdrP1), .q(RawFlushAdr));
assign NextFlushAdr = FlushAdrCntEn ? FlushAdrP1 : RawFlushAdr;
assign FlushAdrP1 = RawFlushAdr + 1'b1;
assign FlushAdrFlag = (RawFlushAdr == FlushAdrThreshold[SETLEN-1:0]);
assign ResetOrFlushWay = reset | FlushWayCntRst;
flopenr #(SETLEN) OldFlushAdrReg(.clk, .reset(ResetOrFlushAdr), .en(FlushAdrCntEn),
.d(NextFlushAdr), .q(OldFlushAdr));
mux2 #(SETLEN) FlushAdrMux(NextFlushAdr, OldFlushAdr, SelOldFlushAdr, FlushAdr);
flopenl #(NUMWAYS) FlushWayReg(.clk, .load(ResetOrFlushWay), .en(FlushWayCntEn),
.val({{NUMWAYS-1{1'b0}}, 1'b1}), .d(NextFlushWay), .q(FlushWay));
assign FlushWayFlag = FlushWay[NUMWAYS-1];
@ -200,7 +208,7 @@ module cache #(parameter LINELEN, NUMLINES, NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
.CacheMiss, .CacheAccess, .SelAdr,
.ClearValid, .ClearDirty, .SetDirty,
.SetValid, .SelWriteback, .SelFlush,
.FlushAdrCntEn, .FlushWayCntEn, .FlushAdrCntRst,
.FlushAdrCntEn, .FlushWayCntEn, .FlushAdrCntRst, .SelOldFlushAdr,
.FlushWayCntRst, .FlushAdrFlag, .FlushWayFlag, .FlushCache, .SelFetchBuffer,
.InvalidateCache,
.CacheEn,

35
pipelined/src/cache/cachefsm.sv vendored
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@ -72,6 +72,7 @@ module cachefsm
output logic FlushAdrCntRst,
output logic FlushWayCntRst,
output logic SelFetchBuffer,
output logic SelOldFlushAdr,
output logic CacheEn);
logic resetDelay;
@ -135,6 +136,14 @@ module cachefsm
STATE_MISS_EVICT_DIRTY: if(CacheBusAck) NextState = STATE_MISS_FETCH_WDV;
else NextState = STATE_MISS_EVICT_DIRTY;
// eviction needs a delay as the bus fsm does not correctly handle sending the write command at the same time as getting back the bus ack.
STATE_FLUSH: if(LineDirty) NextState = STATE_FLUSH_WRITE_BACK;
else if (FlushFlag & FlushWayFlag) NextState = STATE_READY;
else NextState = STATE_FLUSH;
STATE_FLUSH_WRITE_BACK: if(CacheBusAck & ~(FlushFlag & FlushWayFlag)) NextState = STATE_FLUSH;
else if(CacheBusAck) NextState = STATE_READY;
else NextState = STATE_FLUSH_WRITE_BACK;
/* -----\/----- EXCLUDED -----\/-----
STATE_FLUSH: NextState = STATE_FLUSH_CHECK;
STATE_FLUSH_CHECK: if(LineDirty) NextState = STATE_FLUSH_WRITE_BACK;
else if(FlushFlag) NextState = STATE_READY;
@ -146,6 +155,7 @@ module cachefsm
else if(FlushWayFlag) NextState = STATE_FLUSH_INCR;
else NextState = STATE_FLUSH_CHECK;
end else NextState = STATE_FLUSH_WRITE_BACK;
-----/\----- EXCLUDED -----/\----- */
default: NextState = STATE_READY;
endcase
end
@ -156,10 +166,10 @@ module cachefsm
(CurrState == STATE_MISS_FETCH_WDV) |
(CurrState == STATE_MISS_EVICT_DIRTY) |
(CurrState == STATE_MISS_WRITE_CACHE_LINE & ~(StoreAMO)) | // this cycle writes the sram, must keep stalling so the next cycle can read the next hit/miss unless its a write.
(CurrState == STATE_FLUSH) |
(CurrState == STATE_FLUSH_CHECK & ~(FlushFlag)) |
(CurrState == STATE_FLUSH_INCR) |
(CurrState == STATE_FLUSH_WRITE_BACK & ~(FlushFlag) & CacheBusAck);
(CurrState == STATE_FLUSH & ~(FlushFlag & ~LineDirty)) |
//(CurrState == STATE_FLUSH_CHECK & ~(FlushFlag)) |
//(CurrState == STATE_FLUSH_INCR) |
(CurrState == STATE_FLUSH_WRITE_BACK & ~(FlushFlag & CacheBusAck));
// write enables internal to cache
assign SetValid = CurrState == STATE_MISS_WRITE_CACHE_LINE;
assign SetDirty = (CurrState == STATE_READY & AnyUpdateHit) |
@ -175,12 +185,17 @@ module cachefsm
assign SelFlush = (CurrState == STATE_FLUSH) | (CurrState == STATE_FLUSH_CHECK) |
(CurrState == STATE_FLUSH_INCR) | (CurrState == STATE_FLUSH_WRITE_BACK);
assign FlushWayAndNotAdrFlag = FlushWayFlag & ~FlushAdrFlag;
assign FlushAdrCntEn = (CurrState == STATE_FLUSH_CHECK & ~LineDirty & FlushWayAndNotAdrFlag) |
(CurrState == STATE_FLUSH_WRITE_BACK & FlushWayAndNotAdrFlag & CacheBusAck);
assign FlushWayCntEn = (CurrState == STATE_FLUSH_CHECK & ~LineDirty & ~(FlushFlag)) |
(CurrState == STATE_FLUSH_WRITE_BACK & ~FlushFlag & CacheBusAck);
assign FlushAdrCntRst = (CurrState == STATE_READY);
assign FlushWayCntRst = (CurrState == STATE_READY) | (CurrState == STATE_FLUSH_INCR);
//assign FlushAdrCntEn = (CurrState == STATE_FLUSH_CHECK & ~LineDirty & FlushWayAndNotAdrFlag) |
// (CurrState == STATE_FLUSH_WRITE_BACK & FlushWayAndNotAdrFlag & CacheBusAck);
assign FlushAdrCntEn = (CurrState == STATE_FLUSH_WRITE_BACK & FlushWayFlag & CacheBusAck) |
(CurrState == STATE_FLUSH & FlushWayFlag & ~LineDirty);
assign FlushWayCntEn = (CurrState == STATE_FLUSH & ~LineDirty) |
(CurrState == STATE_FLUSH_WRITE_BACK & CacheBusAck);
assign FlushAdrCntRst = (CurrState == STATE_FLUSH & FlushFlag & FlushWayFlag & ~LineDirty) |
(CurrState == STATE_FLUSH_WRITE_BACK & FlushFlag & FlushWayFlag & CacheBusAck);
assign FlushWayCntRst = FlushAdrCntRst;
assign SelOldFlushAdr = (CurrState == STATE_FLUSH & LineDirty) |
(CurrState == STATE_FLUSH_WRITE_BACK & ~CacheBusAck);
// Bus interface controls
assign CacheBusRW[1] = (CurrState == STATE_READY & AnyMiss & ~LineDirty) |
(CurrState == STATE_MISS_FETCH_WDV & ~CacheBusAck) |

4
pipelined/src/ebu/buscachefsm.sv
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@ -131,8 +131,8 @@ module buscachefsm #(parameter integer BeatCountThreshold,
assign BusStall = (CurrState == ADR_PHASE & (|BusRW | |CacheBusRW)) |
//(CurrState == DATA_PHASE & ~BusRW[0]) | // replace the next line with this. Fails uart test but i think it's a test problem not a hardware problem.
(CurrState == DATA_PHASE) |
(CurrState == CACHE_FETCH) |
(CurrState == CACHE_WRITEBACK);
(CurrState == CACHE_FETCH & ~HREADY) |
(CurrState == CACHE_WRITEBACK & ~HREADY);
assign BusCommitted = CurrState != ADR_PHASE;
// AHB bus interface