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rocket-chip/src/main/scala/tilelink/Bus.scala

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Scala
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// See LICENSE.SiFive for license details.
package freechips.rocketchip.tilelink
import Chisel._
import freechips.rocketchip.config.{Field, Parameters}
import freechips.rocketchip.diplomacy._
case object TLBusDelayProbability extends Field[Double](0.0)
/** Specifies widths of various attachement points in the SoC */
trait TLBusParams {
val beatBytes: Int
val blockBytes: Int
val masterBuffering: BufferParams
val slaveBuffering: BufferParams
def beatBits: Int = beatBytes * 8
def blockBits: Int = blockBytes * 8
def blockBeats: Int = blockBytes / beatBytes
def blockOffset: Int = log2Up(blockBytes)
}
abstract class TLBusWrapper(params: TLBusParams, val busName: String)(implicit p: Parameters)
extends SimpleLazyModule with LazyScope with TLBusParams {
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val beatBytes = params.beatBytes
val blockBytes = params.blockBytes
val masterBuffering = params.masterBuffering
val slaveBuffering = params.slaveBuffering
require(blockBytes % beatBytes == 0)
private val delayProb = p(TLBusDelayProbability)
protected val xbar = LazyModule(new TLXbar)
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xbar.suggestName(busName)
private val master_buffer = LazyModule(new TLBuffer(masterBuffering))
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master_buffer.suggestName(s"${busName}_master_TLBuffer")
private val slave_buffer = LazyModule(new TLBuffer(slaveBuffering))
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slave_buffer.suggestName(s"${busName}_slave_TLBuffer")
private val slave_frag = LazyModule(new TLFragmenter(beatBytes, blockBytes))
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slave_frag.suggestName(s"${busName}_slave_TLFragmenter")
private val slave_ww = LazyModule(new TLWidthWidget(beatBytes))
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slave_ww.suggestName(s"${busName}_slave_TLWidthWidget")
private val delayedNode = if (delayProb > 0.0) {
val firstDelay = LazyModule(new TLDelayer(delayProb))
val flowDelay = LazyModule(new TLBuffer(BufferParams.flow))
val secondDelay = LazyModule(new TLDelayer(delayProb))
firstDelay.node :*= xbar.node
flowDelay.node :*= firstDelay.node
secondDelay.node :*= flowDelay.node
secondDelay.node
} else {
xbar.node
}
xbar.node :=* master_buffer.node
slave_buffer.node :*= delayedNode
slave_frag.node :*= slave_buffer.node
slave_ww.node :*= slave_buffer.node
protected def outwardNode: TLOutwardNode = delayedNode
protected def outwardBufNode: TLOutwardNode = slave_buffer.node
protected def outwardFragNode: TLOutwardNode = slave_frag.node
protected def outwardWWNode: TLOutwardNode = slave_ww.node
protected def inwardNode: TLInwardNode = xbar.node
protected def inwardBufNode: TLInwardNode = master_buffer.node
def bufferFromMasters: TLInwardNode = inwardBufNode
def bufferToSlaves: TLOutwardNode = outwardBufNode
def toSyncSlaves(name: Option[String] = None, addBuffers: Int = 0): TLOutwardNode = {
TLBuffer.chain(addBuffers).foldRight(outwardBufNode)(_ :*= _)
}
def toVariableWidthSlaves: TLOutwardNode = outwardFragNode
def toFixedWidthSlaves: TLOutwardNode = outwardWWNode
def toFixedWidthPorts: TLOutwardNode = outwardWWNode // TODO, do/don't buffer here; knowing we will after the necessary port conversions
}