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Add documentation to DCache about datapath of meta/data arbiter #3510

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Oct 17, 2023
+17 −0
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Add documentation to DCache about datapath of meta/data arbiter #3510

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17 changes: 17 additions & 0 deletions src/main/scala/rocket/DCache.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -115,6 +115,17 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {

// tags
val replacer = ReplacementPolicy.fromString(cacheParams.replacementPolicy, nWays)

/** Metadata Arbiter:
* 0: Tag update on reset
* 1: Tag update on ECC error
* 2: Tag update on hit
* 3: Tag update on refill
* 4: Tag update on release
* 5: Tag update on flush
* 6: Tag update on probe
* 7: Tag update on CPU request
*/
val metaArb = Module(new Arbiter(new DCacheMetadataReq, 8) with InlineInstance)

val tag_array = DescribedSRAM(
Expand All @@ -126,6 +137,12 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {

// data
val data = Module(new DCacheDataArray)
/** Data Arbiter
* 0: data from pending store buffer
* 1: data from TL-D refill
* 2: release to TL-A
* 3: hit path to CPU
*/
val dataArb = Module(new Arbiter(new DCacheDataReq, 4) with InlineInstance)
dataArb.io.in.tail.foreach(_.bits.wdata := dataArb.io.in.head.bits.wdata) // tie off write ports by default
data.io.req.bits <> dataArb.io.out.bits
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