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More cachefsm cache flush cleanup.

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This commit is contained in:
Ross Thompson 2022-12-16 16:32:21 -06:00
parent 731fbfc851
commit 9ebea891e2
1 changed files with 19 additions and 23 deletions
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42
pipelined/src/cache/cachefsm.sv vendored
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@ -115,30 +115,28 @@ module cachefsm
always_comb begin
NextState = STATE_READY;
case (CurrState)
STATE_READY: if(InvalidateCache) NextState = STATE_READY;
else if(FlushCache) NextState = STATE_FLUSH;
STATE_READY: if(InvalidateCache) NextState = STATE_READY;
else if(FlushCache) NextState = STATE_FLUSH;
// Delayed LRU update. Cannot check if victim line is dirty on this cycle.
// To optimize do the fetch first, then eviction if necessary.
else if(AnyMiss & ~LineDirty) NextState = STATE_MISS_FETCH_WDV;
else if(AnyMiss & LineDirty) NextState = STATE_MISS_EVICT_DIRTY;
else NextState = STATE_READY;
STATE_MISS_FETCH_WDV: if(CacheBusAck) NextState = STATE_MISS_WRITE_CACHE_LINE;
else NextState = STATE_MISS_FETCH_WDV;
//STATE_MISS_WRITE_CACHE_LINE: NextState = STATE_READY;
STATE_MISS_WRITE_CACHE_LINE: NextState = STATE_MISS_READ_DELAY;
//else NextState = STATE_READY;
STATE_MISS_READ_DELAY: if(Stall) NextState = STATE_MISS_READ_DELAY;
else NextState = STATE_READY;
STATE_MISS_EVICT_DIRTY: if(CacheBusAck) NextState = STATE_MISS_FETCH_WDV;
else NextState = STATE_MISS_EVICT_DIRTY;
else NextState = STATE_READY;
STATE_MISS_FETCH_WDV: if(CacheBusAck) NextState = STATE_MISS_WRITE_CACHE_LINE;
else NextState = STATE_MISS_FETCH_WDV;
STATE_MISS_WRITE_CACHE_LINE: NextState = STATE_MISS_READ_DELAY;
STATE_MISS_READ_DELAY: if(Stall) NextState = STATE_MISS_READ_DELAY;
else NextState = STATE_READY;
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;
default: NextState = STATE_READY;
STATE_FLUSH: if(LineDirty) NextState = STATE_FLUSH_WRITE_BACK;
else if (FlushFlag) NextState = STATE_READY;
else NextState = STATE_FLUSH;
STATE_FLUSH_WRITE_BACK: if(CacheBusAck & ~FlushFlag) NextState = STATE_FLUSH;
else if(CacheBusAck) NextState = STATE_READY;
else NextState = STATE_FLUSH_WRITE_BACK;
default: NextState = STATE_READY;
endcase
end
@ -149,8 +147,6 @@ module cachefsm
(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 & ~(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;
@ -172,8 +168,8 @@ module cachefsm
(CurrState == STATE_FLUSH & FlushWayFlag & ~LineDirty);
assign FlushWayCntEn = (CurrState == STATE_FLUSH & ~LineDirty) |
(CurrState == STATE_FLUSH_WRITE_BACK & CacheBusAck);
assign FlushCntRst = (CurrState == STATE_FLUSH & FlushFlag & FlushWayFlag & ~LineDirty) |
(CurrState == STATE_FLUSH_WRITE_BACK & FlushFlag & FlushWayFlag & CacheBusAck);
assign FlushCntRst = (CurrState == STATE_FLUSH & FlushFlag & ~LineDirty) |
(CurrState == STATE_FLUSH_WRITE_BACK & FlushFlag & CacheBusAck);
// Bus interface controls
assign CacheBusRW[1] = (CurrState == STATE_READY & AnyMiss & ~LineDirty) |
(CurrState == STATE_MISS_FETCH_WDV & ~CacheBusAck) |