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

303 lines
13 KiB
Scala

// See LICENSE.SiFive for license details.
package freechips.rocketchip.tilelink
import Chisel._
import freechips.rocketchip.config.Parameters
import freechips.rocketchip.diplomacy._
import freechips.rocketchip.util._
import scala.math.{min,max}
// Ensures that all downstream RW managers support Atomic operationss.
// If !passthrough, intercept all Atomics. Otherwise, only intercept those unsupported downstream.
class TLAtomicAutomata(logical: Boolean = true, arithmetic: Boolean = true, concurrency: Int = 1, passthrough: Boolean = true)(implicit p: Parameters) extends LazyModule
{
require (concurrency >= 1)
val node = TLAdapterNode(
clientFn = { case cp => require (!cp.unsafeAtomics); cp.copy(unsafeAtomics = true) },
managerFn = { case mp => mp.copy(managers = mp.managers.map { m =>
val ourSupport = TransferSizes(1, mp.beatBytes)
def widen(x: TransferSizes) = if (passthrough && x.min <= 2*mp.beatBytes) TransferSizes(1, max(mp.beatBytes, x.max)) else ourSupport
val canDoit = m.supportsPutFull.contains(ourSupport) && m.supportsGet.contains(ourSupport)
// Blow up if there are devices to which we cannot add Atomics, because their R|W are too inflexible
require (!m.supportsPutFull || !m.supportsGet || canDoit, s"${m.name} has $ourSupport, needed PutFull(${m.supportsPutFull}) or Get(${m.supportsGet})")
m.copy(
supportsArithmetic = if (!arithmetic || !canDoit) m.supportsArithmetic else widen(m.supportsArithmetic),
supportsLogical = if (!logical || !canDoit) m.supportsLogical else widen(m.supportsLogical))
})})
lazy val module = new LazyModuleImp(this) {
(node.in zip node.out) foreach { case ((in, edgeIn), (out, edgeOut)) =>
val managers = edgeOut.manager.managers
val beatBytes = edgeOut.manager.beatBytes
// To which managers are we adding atomic support?
val ourSupport = TransferSizes(1, edgeOut.manager.beatBytes)
val managersNeedingHelp = managers.filter { m =>
m.supportsPutFull.contains(ourSupport) &&
m.supportsGet.contains(ourSupport) &&
((logical && !m.supportsLogical .contains(ourSupport)) ||
(arithmetic && !m.supportsArithmetic.contains(ourSupport)) ||
!passthrough) // we will do atomics for everyone we can
}
// We cannot add atomcis to a non-FIFO manager
managersNeedingHelp foreach { m => require (m.fifoId.isDefined) }
// We need to preserve FIFO semantics across FIFO domains, not managers
// Suppose you have Put(42) Atomic(+1) both inflight; valid results: 42 or 43
// If we allow Put(42) Get() Put(+1) concurrent; valid results: 42 43 OR undef
// Making non-FIFO work requires waiting for all Acks to come back (=> use FIFOFixer)
val domainsNeedingHelp = managersNeedingHelp.map(_.fifoId.get).distinct
// Don't overprovision the CAM
val camSize = min(domainsNeedingHelp.size, concurrency)
// Compact the fifoIds to only those we care about
def camFifoId(m: TLManagerParameters) = m.fifoId.map(id => max(0, domainsNeedingHelp.indexOf(id))).getOrElse(0)
// CAM entry state machine
val FREE = UInt(0) // unused waiting on Atomic from A
val GET = UInt(3) // Get sent down A waiting on AccessDataAck from D
val AMO = UInt(2) // AccessDataAck sent up D waiting for A availability
val ACK = UInt(1) // Put sent down A waiting for PutAck from D
val params = TLAtomicAutomata.CAMParams(out.a.bits.params, domainsNeedingHelp.size)
// Do we need to do anything at all?
if (camSize > 0) {
val initval = Wire(new TLAtomicAutomata.CAM_S(params))
initval.state := FREE
val cam_s = RegInit(Vec.fill(camSize)(initval))
val cam_a = Reg(Vec(camSize, new TLAtomicAutomata.CAM_A(params)))
val cam_d = Reg(Vec(camSize, new TLAtomicAutomata.CAM_D(params)))
val cam_free = cam_s.map(_.state === FREE)
val cam_amo = cam_s.map(_.state === AMO)
val cam_abusy = cam_s.map(e => e.state === GET || e.state === AMO) // A is blocked
val cam_dmatch = cam_s.map(e => e.state =/= FREE) // D should inspect these entries
// Can the manager already handle this message?
val a_address = edgeIn.address(in.a.bits)
val a_size = edgeIn.size(in.a.bits)
val a_canLogical = Bool(passthrough) && edgeOut.manager.supportsLogicalFast (a_address, a_size)
val a_canArithmetic = Bool(passthrough) && edgeOut.manager.supportsArithmeticFast(a_address, a_size)
val a_isLogical = in.a.bits.opcode === TLMessages.LogicalData
val a_isArithmetic = in.a.bits.opcode === TLMessages.ArithmeticData
val a_isSupported = Mux(a_isLogical, a_canLogical, Mux(a_isArithmetic, a_canArithmetic, Bool(true)))
// Must we do a Put?
val a_cam_any_put = cam_amo.reduce(_ || _)
val a_cam_por_put = cam_amo.scanLeft(Bool(false))(_||_).init
val a_cam_sel_put = (cam_amo zip a_cam_por_put) map { case (a, b) => a && !b }
val a_cam_a = PriorityMux(cam_amo, cam_a)
val a_cam_d = PriorityMux(cam_amo, cam_d)
val a_a = a_cam_a.bits.data
val a_d = a_cam_d.data
// Does the A request conflict with an inflight AMO?
val a_fifoId = edgeOut.manager.fastProperty(a_address, camFifoId _, (i:Int) => UInt(i))
val a_cam_busy = (cam_abusy zip cam_a.map(_.fifoId === a_fifoId)) map { case (a,b) => a&&b } reduce (_||_)
// (Where) are we are allocating in the CAM?
val a_cam_any_free = cam_free.reduce(_ || _)
val a_cam_por_free = cam_free.scanLeft(Bool(false))(_||_).init
val a_cam_sel_free = (cam_free zip a_cam_por_free) map { case (a,b) => a && !b }
// Logical AMO
val indexes = Seq.tabulate(beatBytes*8) { i => Cat(a_a(i,i), a_d(i,i)) }
val logic_out = Cat(indexes.map(x => a_cam_a.lut(x).asUInt).reverse)
// Arithmetic AMO
val unsigned = a_cam_a.bits.param(1)
val take_max = a_cam_a.bits.param(0)
val adder = a_cam_a.bits.param(2)
val mask = a_cam_a.bits.mask
val signSel = ~(~mask | (mask >> 1))
val signbits_a = Cat(Seq.tabulate(beatBytes) { i => a_a(8*i+7,8*i+7) } .reverse)
val signbits_d = Cat(Seq.tabulate(beatBytes) { i => a_d(8*i+7,8*i+7) } .reverse)
// Move the selected sign bit into the first byte position it will extend
val signbit_a = ((signbits_a & signSel) << 1)(beatBytes-1, 0)
val signbit_d = ((signbits_d & signSel) << 1)(beatBytes-1, 0)
val signext_a = FillInterleaved(8, leftOR(signbit_a))
val signext_d = FillInterleaved(8, leftOR(signbit_d))
// NOTE: sign-extension does not change the relative ordering in EITHER unsigned or signed arithmetic
val wide_mask = FillInterleaved(8, mask)
val a_a_ext = (a_a & wide_mask) | signext_a
val a_d_ext = (a_d & wide_mask) | signext_d
val a_d_inv = Mux(adder, a_d_ext, ~a_d_ext)
val adder_out = a_a_ext + a_d_inv
val h = 8*beatBytes-1 // now sign-extended; use biggest bit
val a_bigger_uneq = unsigned === a_a_ext(h) // result if high bits are unequal
val a_bigger = Mux(a_a_ext(h) === a_d_ext(h), !adder_out(h), a_bigger_uneq)
val pick_a = take_max === a_bigger
val arith_out = Mux(adder, adder_out, Mux(pick_a, a_a, a_d))
// AMO result data
val amo_data =
if (!logical) arith_out else
if (!arithmetic) logic_out else
Mux(a_cam_a.bits.opcode(0), logic_out, arith_out)
// Potentially mutate the message from inner
val source_i = Wire(in.a)
val a_allow = !a_cam_busy && (a_isSupported || a_cam_any_free)
in.a.ready := source_i.ready && a_allow
source_i.valid := in.a.valid && a_allow
source_i.bits := in.a.bits
when (!a_isSupported) { // minimal mux difference
source_i.bits.opcode := TLMessages.Get
source_i.bits.param := UInt(0)
}
// Potentially take the message from the CAM
val source_c = Wire(in.a)
source_c.valid := a_cam_any_put
source_c.bits := edgeOut.Put(a_cam_a.bits.source, edgeIn.address(a_cam_a.bits), a_cam_a.bits.size, amo_data)._2
// Finishing an AMO from the CAM has highest priority
TLArbiter(TLArbiter.lowestIndexFirst)(out.a, (UInt(0), source_c), (edgeOut.numBeats1(in.a.bits), source_i))
// Capture the A state into the CAM
when (source_i.fire() && !a_isSupported) {
(a_cam_sel_free zip cam_a) foreach { case (en, r) =>
when (en) {
r.fifoId := a_fifoId
r.bits := in.a.bits
r.lut := MuxLookup(in.a.bits.param(1, 0), UInt(0, width = 4), Array(
TLAtomics.AND -> UInt(0x8),
TLAtomics.OR -> UInt(0xe),
TLAtomics.XOR -> UInt(0x6),
TLAtomics.SWAP -> UInt(0xc)))
}
}
(a_cam_sel_free zip cam_s) foreach { case (en, r) =>
when (en) {
r.state := GET
}
}
}
// Advance the put state
when (source_c.fire()) {
(a_cam_sel_put zip cam_s) foreach { case (en, r) =>
when (en) {
r.state := ACK
}
}
}
// We need to deal with a potential D response in the same cycle as the A request
val d_first = edgeOut.first(out.d)
val d_cam_sel_raw = cam_a.map(_.bits.source === in.d.bits.source)
val d_cam_sel_match = (d_cam_sel_raw zip cam_dmatch) map { case (a,b) => a&&b }
val d_cam_data = Mux1H(d_cam_sel_match, cam_d.map(_.data))
val d_cam_sel_bypass = if (edgeOut.manager.minLatency > 0) Bool(false) else
out.d.bits.source === in.a.bits.source && in.a.valid && !a_isSupported
val d_cam_sel = (a_cam_sel_free zip d_cam_sel_match) map { case (a,d) => Mux(d_cam_sel_bypass, a, d) }
val d_cam_sel_any = d_cam_sel_bypass || d_cam_sel_match.reduce(_ || _)
val d_ackd = out.d.bits.opcode === TLMessages.AccessAckData
val d_ack = out.d.bits.opcode === TLMessages.AccessAck
when (out.d.fire() && d_first) {
(d_cam_sel zip cam_d) foreach { case (en, r) =>
when (en && d_ackd) {
r.data := out.d.bits.data
}
}
(d_cam_sel zip cam_s) foreach { case (en, r) =>
when (en) {
// Note: it is important that this comes AFTER the := GET, so we can go FREE=>GET=>AMO in one cycle
r.state := Mux(d_ackd, AMO, FREE)
}
}
}
val d_drop = d_first && d_ackd && d_cam_sel_any
val d_replace = d_first && d_ack && d_cam_sel_match.reduce(_ || _)
in.d.valid := out.d.valid && !d_drop
out.d.ready := in.d.ready || d_drop
in.d.bits := out.d.bits
when (d_replace) { // minimal muxes
in.d.bits.opcode := TLMessages.AccessAckData
in.d.bits.data := d_cam_data
}
} else {
out.a.valid := in.a.valid
in.a.ready := out.a.ready
out.a.bits := in.a.bits
in.d.valid := out.d.valid
out.d.ready := in.d.ready
in.d.bits := out.d.bits
}
if (edgeOut.manager.anySupportAcquireB && edgeIn.client.anySupportProbe) {
in.b.valid := out.b.valid
out.b.ready := in.b.ready
in.b.bits := out.b.bits
out.c.valid := in.c.valid
in.c.ready := out.c.ready
out.c.bits := in.c.bits
out.e.valid := in.e.valid
in.e.ready := out.e.ready
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 TLAtomicAutomata
{
def apply(logical: Boolean = true, arithmetic: Boolean = true, concurrency: Int = 1, passthrough: Boolean = true)(implicit p: Parameters): TLNode =
LazyModule(new TLAtomicAutomata(logical, arithmetic, concurrency, passthrough)).node
case class CAMParams(a: TLBundleParameters, domainsNeedingHelp: Int)
class CAM_S(params: CAMParams) extends GenericParameterizedBundle(params) {
val state = UInt(width = 2)
}
class CAM_A(params: CAMParams) extends GenericParameterizedBundle(params) {
val bits = new TLBundleA(params.a)
val fifoId = UInt(width = log2Up(params.domainsNeedingHelp))
val lut = UInt(width = 4)
}
class CAM_D(params: CAMParams) extends GenericParameterizedBundle(params) {
val data = UInt(width = params.a.dataBits)
}
}
/** Synthesizeable unit tests */
import freechips.rocketchip.unittest._
//TODO ensure handler will pass through operations to clients that can handle them themselves
class TLRAMAtomicAutomata(txns: Int)(implicit p: Parameters) extends LazyModule {
val fuzz = LazyModule(new TLFuzzer(txns))
val model = LazyModule(new TLRAMModel("AtomicAutomata"))
val ram = LazyModule(new TLRAM(AddressSet(0x0, 0x3ff)))
(ram.node
:= TLFragmenter(4, 256)
:= TLDelayer(0.1)
:= TLAtomicAutomata()
:= TLDelayer(0.1)
:= model.node
:= fuzz.node)
lazy val module = new LazyModuleImp(this) with UnitTestModule {
io.finished := fuzz.module.io.finished
}
}
class TLRAMAtomicAutomataTest(txns: Int = 5000, timeout: Int = 500000)(implicit p: Parameters) extends UnitTest(timeout) {
io.finished := Module(LazyModule(new TLRAMAtomicAutomata(txns)).module).io.finished
}