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rocket-chip/src/main/scala/uncore/tilelink2/WidthWidget.scala

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Scala
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// See LICENSE for license details.
package uncore.tilelink2
import Chisel._
import chisel3.internal.sourceinfo.SourceInfo
import scala.math.{min,max}
// innBeatBytes => the new client-facing bus width
class TLWidthWidget(innerBeatBytes: Int) extends LazyModule
{
val node = TLAdapterNode(
clientFn = { case Seq(c) => c },
managerFn = { case Seq(m) => m.copy(beatBytes = innerBeatBytes) })
lazy val module = new LazyModuleImp(this) {
val io = new Bundle {
val in = node.bundleIn
val out = node.bundleOut
}
def merge[T <: TLDataChannel](edgeIn: TLEdge, in: DecoupledIO[T], edgeOut: TLEdge, out: DecoupledIO[T]) = {
val inBytes = edgeIn.manager.beatBytes
val outBytes = edgeOut.manager.beatBytes
val ratio = outBytes / inBytes
val rdata = Reg(UInt(width = (ratio-1)*inBytes*8))
val rmask = Reg(UInt(width = (ratio-1)*inBytes))
val data = Cat(edgeIn.data(in.bits), rdata)
val mask = Cat(edgeIn.mask(in.bits), rmask)
val size = edgeIn.size(in.bits)
val hasData = edgeIn.hasData(in.bits)
val addr_lo = in.bits match {
case x: TLAddrChannel => edgeIn.address(x)
case _ => UInt(0)
}
val addr = addr_lo >> log2Ceil(outBytes)
val count = RegInit(UInt(0, width = log2Ceil(ratio)))
val first = count === UInt(0)
val limit = UIntToOH1(size, log2Ceil(outBytes)) >> log2Ceil(inBytes)
val last = count === limit || !hasData
when (in.fire()) {
rdata := data >> inBytes*8
rmask := mask >> inBytes
count := count + UInt(1)
when (last) { count := UInt(0) }
}
val cases = Seq.tabulate(log2Ceil(ratio)+1) { i =>
val high = outBytes
val take = (1 << i)*inBytes
(Fill(1 << (log2Ceil(ratio)-i), data(high*8-1, (high-take)*8)),
Fill(1 << (log2Ceil(ratio)-i), mask(high -1, (high-take))))
}
val dataMux = Vec.tabulate(log2Ceil(edgeIn.maxTransfer)+1) { lgSize =>
cases(min(max(lgSize - log2Ceil(inBytes), 0), log2Ceil(ratio)))._1
}
val maskMux = Vec.tabulate(log2Ceil(edgeIn.maxTransfer)+1) { lgSize =>
cases(min(max(lgSize - log2Ceil(inBytes), 0), log2Ceil(ratio)))._2
}
val dataOut = if (edgeIn.staticHasData(in.bits) == Some(false)) UInt(0) else dataMux(size)
val maskOut = maskMux(size) & edgeOut.mask(addr_lo, size)
in.ready := out.ready || !last
out.valid := in.valid && last
out.bits := in.bits
edgeOut.data(out.bits) := dataOut
out.bits match {
case a: TLBundleA => a.addr_hi := addr; a.mask := maskOut
case b: TLBundleB => b.addr_hi := addr; b.mask := maskOut
case c: TLBundleC => c.addr_hi := addr; c.addr_lo := addr_lo
case d: TLBundleD => ()
// addr_lo gets padded with 0s on D channel, the only lossy transform in this core
// this should be safe, because we only care about addr_log on D to determine which
// piece of data to extract when the D data bus is narrowed. Since we duplicated the
// data to all locations, addr_lo still points at a valid copy.
}
}
def split[T <: TLDataChannel](edgeIn: TLEdge, in: DecoupledIO[T], edgeOut: TLEdge, out: DecoupledIO[T]) = {
val inBytes = edgeIn.manager.beatBytes
val outBytes = edgeOut.manager.beatBytes
val ratio = inBytes / outBytes
val hasData = edgeIn.hasData(in.bits)
val size = edgeIn.size(in.bits)
val data = edgeIn.data(in.bits)
val mask = edgeIn.mask(in.bits)
val addr = in.bits match {
case x: TLAddrChannel => edgeIn.address(x) >> log2Ceil(outBytes)
case _ => UInt(0)
}
val dataSlices = Vec.tabulate(ratio) { i => data((i+1)*outBytes*8-1, i*outBytes*8) }
val maskSlices = Vec.tabulate(ratio) { i => mask((i+1)*outBytes -1, i*outBytes) }
val filter = Reg(UInt(width = ratio), init = SInt(-1, width = ratio).asUInt)
val maskR = maskSlices.map(_.orR)
// decoded_size = 1111 (for smallest), 0101, 0001 (for largest)
val sizeOH1 = UIntToOH1(size, log2Ceil(inBytes)) >> log2Ceil(outBytes)
val decoded_size = Seq.tabulate(ratio) { i => trailingZeros(i).map(!sizeOH1(_)).getOrElse(Bool(true)) }
val first = filter(ratio-1)
val new_filter = Mux(first, Cat(decoded_size.reverse), filter << 1)
val last = new_filter(ratio-1) || !hasData
when (out.fire()) {
filter := new_filter
when (!hasData) { filter := SInt(-1, width = ratio).asUInt }
}
val select = Cat(maskR.reverse) & new_filter
val dataOut = if (edgeIn.staticHasData(in.bits) == Some(false)) UInt(0) else Mux1H(select, dataSlices)
val maskOut = Mux1H(select, maskSlices)
in.ready := out.ready && last
out.valid := in.valid
out.bits := in.bits
edgeOut.data(out.bits) := dataOut
out.bits match {
case a: TLBundleA => a.addr_hi := addr; a.mask := maskOut
case b: TLBundleB => b.addr_hi := addr; b.mask := maskOut
case c: TLBundleC => c.addr_hi := addr
case d: TLBundleD => ()
}
// addr_lo gets truncated automagically
}
def splice[T <: TLDataChannel](edgeIn: TLEdge, in: DecoupledIO[T], edgeOut: TLEdge, out: DecoupledIO[T]) = {
if (edgeIn.manager.beatBytes == edgeOut.manager.beatBytes) {
// nothing to do; pass it through
out <> in
} else if (edgeIn.manager.beatBytes > edgeOut.manager.beatBytes) {
// split input to output
split(edgeIn, in, edgeOut, out)
} else {
// merge input to output
merge(edgeIn, in, edgeOut, out)
}
}
val edgeOut = node.edgesOut(0)
val edgeIn = node.edgesIn(0)
val in = io.in(0)
val out = io.out(0)
splice(edgeIn, in.a, edgeOut, out.a)
splice(edgeOut, out.d, edgeIn, in.d)
if (edgeOut.manager.anySupportAcquire && edgeIn.client.anySupportProbe) {
splice(edgeOut, out.b, edgeIn, in.b)
splice(edgeIn, in.c, edgeOut, out.c)
in.e.ready := out.e.ready
out.e.valid := in.e.valid
out.e.bits := in.e.bits
} else {
in.b.valid := Bool(false)
in.c.ready := Bool(true)
in.e.ready := Bool(true)
out.b.ready := Bool(true)
out.c.valid := Bool(false)
out.e.valid := Bool(false)
}
}
}
object TLWidthWidget
{
// applied to the TL source node; connect (WidthWidget(x.node, 16) -> y.node)
def apply(x: TLBaseNode, innerBeatBytes: Int)(implicit lazyModule: LazyModule, sourceInfo: SourceInfo): TLBaseNode = {
val widget = LazyModule(new TLWidthWidget(innerBeatBytes))
lazyModule.connect(x -> widget.node)
widget.node
}
}