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tilelink: split Acquire into Acquire{Block,Perm} (#1030)

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We had planned for a while to add an 'Overwrite' message which obtains
permissions without requiring retrieval of data. This is useful whenever
a master knows it will completely replace the contents of a cache block.

Instead of calling it Overwrite, we decided to split the Acquire type.

If you AcquirePerm, you MUST Release and ProbeAck with Data.
This commit is contained in:
Wesley W. Terpstra
2017-10-05 12:49:49 -07:00
committed by GitHub
parent 81b9ac42a3
commit bd045a3b95
9 changed files with 55 additions and 25 deletions
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15
src/main/scala/tilelink/Broadcast.scala
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@ -176,6 +176,11 @@ class TLBroadcast(lineBytes: Int, numTrackers: Int = 4, bufferless: Boolean = fa
t.probe := (if (caches.size == 0) UInt(0) else Mux(a_cache.orR(), UInt(caches.size-1), UInt(caches.size)))
}
val acq_perms = MuxLookup(in.a.bits.param, Wire(UInt(width = 2)), Array(
TLPermissions.NtoB -> TLPermissions.toB,
TLPermissions.NtoT -> TLPermissions.toN,
TLPermissions.BtoT -> TLPermissions.toN))
when (in.a.fire() && a_first) {
probe_todo := ~a_cache // probe all but the cache who poked us
probe_line := in.a.bits.address >> lineShift
@ -188,10 +193,8 @@ class TLBroadcast(lineBytes: Int, numTrackers: Int = 4, bufferless: Boolean = fa
TLMessages.Hint -> MuxLookup(in.a.bits.param, Wire(UInt(width = 2)), Array(
TLHints.PREFETCH_READ -> TLPermissions.toB,
TLHints.PREFETCH_WRITE -> TLPermissions.toN)),
TLMessages.Acquire -> MuxLookup(in.a.bits.param, Wire(UInt(width = 2)), Array(
TLPermissions.NtoB -> TLPermissions.toB,
TLPermissions.NtoT -> TLPermissions.toN,
TLPermissions.BtoT -> TLPermissions.toN))))
TLMessages.AcquireBlock -> acq_perms,
TLMessages.AcquirePerm -> acq_perms))
}
// The outer TL connections may not be cached
@ -236,7 +239,7 @@ class TLBroadcastTracker(id: Int, lineBytes: Int, probeCountBits: Int, bufferles
when (io.in_a.fire() && io.in_a_first) {
assert (idle)
sent_d := Bool(false)
got_e := io.in_a.bits.opcode =/= TLMessages.Acquire
got_e := io.in_a.bits.opcode =/= TLMessages.AcquireBlock && io.in_a.bits.opcode =/= TLMessages.AcquirePerm
opcode := io.in_a.bits.opcode
param := io.in_a.bits.param
size := io.in_a.bits.size
@ -271,7 +274,7 @@ class TLBroadcastTracker(id: Int, lineBytes: Int, probeCountBits: Int, bufferles
i_data.bits.data := io.in_a.bits.data
val probe_done = count === UInt(0)
val acquire = opcode === TLMessages.Acquire
val acquire = opcode === TLMessages.AcquireBlock || opcode === TLMessages.AcquirePerm
val transform = MuxLookup(param, Wire(UInt(width = 2)), Array(
TLPermissions.NtoB -> TRANSFORM_B,