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tilelink2: Fragmenter now supports early Ack

This commit is contained in:
Wesley W. Terpstra 2017-04-26 17:39:57 -07:00
parent e09fa866b7
commit 6ee69454c3
1 changed files with 17 additions and 9 deletions
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26
src/main/scala/uncore/tilelink2/Fragmenter.scala
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@ -14,7 +14,7 @@ import scala.math.{min,max}
// Fragmenter modifies: PutFull, PutPartial, LogicalData, Get, Hint
// Fragmenter passes: ArithmeticData (truncated to minSize if alwaysMin)
// Fragmenter cannot modify acquire (could livelock); thus it is unsafe to put caches on both sides
class TLFragmenter(val minSize: Int, val maxSize: Int, val alwaysMin: Boolean = false)(implicit p: Parameters) extends LazyModule
class TLFragmenter(val minSize: Int, val maxSize: Int, val alwaysMin: Boolean = false, val earlyAck: Boolean = false)(implicit p: Parameters) extends LazyModule
{
require (isPow2 (maxSize))
require (isPow2 (minSize))
@ -137,6 +137,7 @@ class TLFragmenter(val minSize: Int, val maxSize: Int, val alwaysMin: Boolean =
val dOrig = Reg(UInt())
val dFragnum = out.d.bits.source(fragmentBits-1, 0)
val dFirst = acknum === UInt(0)
val dLast = dFragnum === UInt(0)
val dsizeOH = UIntToOH (out.d.bits.size, log2Ceil(maxDownSize)+1)
val dsizeOH1 = UIntToOH1(out.d.bits.size, log2Up(maxDownSize))
val dHasData = edgeOut.hasData(out.d.bits)
@ -156,7 +157,7 @@ class TLFragmenter(val minSize: Int, val maxSize: Int, val alwaysMin: Boolean =
}
// Swallow up non-data ack fragments
val drop = !dHasData && (dFragnum =/= UInt(0))
val drop = !dHasData && !(if (earlyAck) dFirst else dLast)
out.d.ready := in.d.ready || drop
in.d.valid := out.d.valid && !drop
in.d.bits := out.d.bits // pass most stuff unchanged
@ -164,11 +165,18 @@ class TLFragmenter(val minSize: Int, val maxSize: Int, val alwaysMin: Boolean =
in.d.bits.source := out.d.bits.source >> fragmentBits
in.d.bits.size := Mux(dFirst, dFirst_size, dOrig)
// Combine the error flag
val r_error = RegInit(Bool(false))
val d_error = r_error | out.d.bits.error
when (out.d.fire()) { r_error := Mux(drop, d_error, UInt(0)) }
in.d.bits.error := d_error
if (earlyAck) {
// If you do early Ack, errors may not be dropped
// ... which roughly means: Puts may not fail
assert (!out.d.bits.error || !drop)
in.d.bits.error := out.d.bits.error
} else {
// Combine the error flag
val r_error = RegInit(Bool(false))
val d_error = r_error | out.d.bits.error
when (out.d.fire()) { r_error := Mux(drop, d_error, UInt(0)) }
in.d.bits.error := d_error
}
// What maximum transfer sizes do downstream devices support?
val maxArithmetics = managers.map(_.supportsArithmetic.max)
@ -252,8 +260,8 @@ class TLFragmenter(val minSize: Int, val maxSize: Int, val alwaysMin: Boolean =
object TLFragmenter
{
// applied to the TL source node; y.node := TLFragmenter(x.node, 256, 4)
def apply(minSize: Int, maxSize: Int, alwaysMin: Boolean = false)(x: TLOutwardNode)(implicit p: Parameters, sourceInfo: SourceInfo): TLOutwardNode = {
val fragmenter = LazyModule(new TLFragmenter(minSize, maxSize, alwaysMin))
def apply(minSize: Int, maxSize: Int, alwaysMin: Boolean = false, earlyAck: Boolean = false)(x: TLOutwardNode)(implicit p: Parameters, sourceInfo: SourceInfo): TLOutwardNode = {
val fragmenter = LazyModule(new TLFragmenter(minSize, maxSize, alwaysMin, earlyAck))
fragmenter.node := x
fragmenter.node
}