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rocket-chip/src/main/scala/tilelink/CacheCork.scala
2017-10-28 11:34:16 -07:00

126 lines
4.9 KiB
Scala

// See LICENSE.SiFive for license details.
package freechips.rocketchip.tilelink
import Chisel._
import freechips.rocketchip.config.Parameters
import freechips.rocketchip.diplomacy._
import scala.math.{min,max}
import TLMessages._
class TLCacheCork(unsafe: Boolean = false)(implicit p: Parameters) extends LazyModule
{
val node = TLAdapterNode(
clientFn = { case cp =>
cp.copy(clients = cp.clients.map { c => c.copy(
supportsProbe = TransferSizes.none,
sourceId = IdRange(c.sourceId.start*2, c.sourceId.end*2))})},
managerFn = { case mp =>
mp.copy(
endSinkId = 1,
managers = mp.managers.map { m => m.copy(
supportsAcquireB = if (m.regionType == RegionType.UNCACHED) m.supportsGet else m.supportsAcquireB,
supportsAcquireT = if (m.regionType == RegionType.UNCACHED) m.supportsPutFull else m.supportsAcquireT)})})
lazy val module = new LazyModuleImp(this) {
(node.in zip node.out) foreach { case ((in, edgeIn), (out, edgeOut)) =>
val clients = edgeIn.client.clients
val caches = clients.filter(_.supportsProbe)
require (clients.size == 1 || caches.size == 0 || unsafe, "Only one client can safely use a TLCacheCork")
require (caches.size <= 1 || unsafe, "Only one caching client allowed")
edgeOut.manager.managers.foreach { case m =>
require (!m.supportsAcquireB || unsafe, "Cannot support caches beyond the Cork")
require (m.regionType <= RegionType.UNCACHED)
}
// The Cork turns [Acquire=>Get] => [AccessAckData=>GrantData]
// and [ReleaseData=>PutFullData] => [AccessAck=>ReleaseAck]
// We need to encode information sufficient to reverse the transformation in output.
// A caveat is that we get Acquire+Release with the same source and must keep the
// source unique after transformation onto the A channel.
// The coding scheme is:
// Put: 1, Release: 0 => AccessAck
// *: 0, Acquire: 1 => AccessAckData
// Take requests from A to A or D (if BtoT Acquire)
val a_a = Wire(out.a)
val a_d = Wire(in.d)
val isPut = in.a.bits.opcode === PutFullData || in.a.bits.opcode === PutPartialData
val toD = (in.a.bits.opcode === AcquireBlock && in.a.bits.param === TLPermissions.BtoT) ||
(in.a.bits.opcode === AcquirePerm)
in.a.ready := Mux(toD, a_d.ready, a_a.ready)
a_a.valid := in.a.valid && !toD
a_a.bits := in.a.bits
a_a.bits.source := in.a.bits.source << 1 | Mux(isPut, UInt(1), UInt(0))
// Transform Acquire into Get
when (in.a.bits.opcode === AcquireBlock || in.a.bits.opcode === AcquirePerm) {
a_a.bits.opcode := Get
a_a.bits.param := UInt(0)
a_a.bits.source := in.a.bits.source << 1 | UInt(1)
}
// Upgrades are instantly successful
a_d.valid := in.a.valid && toD
a_d.bits := edgeIn.Grant(
fromSink = UInt(0),
toSource = in.a.bits.source,
lgSize = in.a.bits.size,
capPermissions = TLPermissions.toT)
// Take ReleaseData from C to A; Release from C to D
val c_a = Wire(out.a)
c_a.valid := in.c.valid && in.c.bits.opcode === ReleaseData
c_a.bits := edgeOut.Put(
fromSource = in.c.bits.source << 1,
toAddress = in.c.bits.address,
lgSize = in.c.bits.size,
data = in.c.bits.data)._2
// Releases without Data succeed instantly
val c_d = Wire(in.d)
c_d.valid := in.c.valid && in.c.bits.opcode === Release
c_d.bits := edgeIn.ReleaseAck(in.c.bits)
assert (!in.c.valid || in.c.bits.opcode === Release || in.c.bits.opcode === ReleaseData)
in.c.ready := Mux(in.c.bits.opcode === Release, c_d.ready, c_a.ready)
// Discard E
in.e.ready := Bool(true)
// Block B; should never happen
out.b.ready := Bool(false)
assert (!out.b.valid)
// Take responses from D and transform them
val d_d = Wire(in.d)
d_d <> out.d
d_d.bits.source := out.d.bits.source >> 1
if (unsafe) { d_d.bits.sink := UInt(0) }
when (out.d.bits.opcode === AccessAckData && out.d.bits.source(0)) {
d_d.bits.opcode := GrantData
d_d.bits.param := TLPermissions.toT
}
when (out.d.bits.opcode === AccessAck && !out.d.bits.source(0)) {
d_d.bits.opcode := ReleaseAck
}
// Combine the sources of messages into the channels
TLArbiter(TLArbiter.lowestIndexFirst)(out.a, (edgeOut.numBeats1(c_a.bits), c_a), (edgeOut.numBeats1(a_a.bits), a_a))
TLArbiter(TLArbiter.lowestIndexFirst)(in.d, (edgeIn .numBeats1(d_d.bits), d_d), (UInt(0), Queue(c_d, 2)), (UInt(0), Queue(a_d, 2)))
// Tie off unused ports
in.b.valid := Bool(false)
out.c.valid := Bool(false)
out.e.valid := Bool(false)
}
}
}
object TLCacheCork
{
def apply(unsafe: Boolean = false)(implicit p: Parameters): TLNode = LazyModule(new TLCacheCork(unsafe)).node
}