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Merge pull request #400 from ucb-bar/better-crossing-asserts

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Better crossing reset handling
This commit is contained in:
Wesley W. Terpstra 2016-10-14 19:19:37 -07:00 committed by GitHub
commit ee66fd28eb
5 changed files with 113 additions and 75 deletions
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9
src/main/scala/regmapper/RegisterCrossing.scala
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@ -41,7 +41,10 @@ class RegisterCrossingAssertion extends Module {
val slave_reset = Bool(INPUT)
}
assert (io.master_bypass || !io.slave_reset)
val up = RegInit(Bool(false))
up := !io.slave_reset
assert (io.master_bypass || !up || !io.slave_reset)
}
// RegField should support connecting to one of these
@ -88,7 +91,7 @@ class RegisterWriteCrossing[T <: Data](gen: T, sync: Int = 3) extends Module {
val io = new RegisterWriteCrossingIO(gen)
// The crossing must only allow one item inflight at a time
val control = Module(new BusyRegisterCrossing)
val crossing = Module(new AsyncQueue(gen, 1, sync))
val crossing = Module(new AsyncQueue(gen, 1, sync, safe=false))
control.clock := io.master_clock
control.reset := io.master_reset
@ -141,7 +144,7 @@ class RegisterReadCrossing[T <: Data](gen: T, sync: Int = 3) extends Module {
val io = new RegisterReadCrossingIO(gen)
// The crossing must only allow one item inflight at a time
val control = Module(new BusyRegisterCrossing)
val crossing = Module(new AsyncQueue(gen, 1, sync))
val crossing = Module(new AsyncQueue(gen, 1, sync, safe=false))
control.clock := io.master_clock
control.reset := io.master_reset

8
src/main/scala/uncore/tilelink2/Bundles.scala
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@ -222,9 +222,11 @@ object TLBundleSnoop
final class AsyncBundle[T <: Data](val depth: Int, gen: T) extends Bundle
{
require (isPow2(depth))
val mem = Vec(depth, gen)
val ridx = UInt(width = log2Up(depth)+1).flip
val widx = UInt(width = log2Up(depth)+1)
val mem = Vec(depth, gen)
val ridx_valid = Bool().flip
val widx_valid = Bool()
val source_reset_n = Bool()
val sink_reset_n = Bool().flip
@ -236,7 +238,9 @@ object FromAsyncBundle
def apply[T <: Data](x: AsyncBundle[T], sync: Int = 3): DecoupledIO[T] = {
val sink = Module(new AsyncQueueSink(x.mem(0), x.depth, sync))
x.ridx := sink.io.ridx
x.ridx_valid := sink.io.ridx_valid
sink.io.widx := x.widx
sink.io.widx_valid := x.widx_valid
sink.io.mem := x.mem
sink.io.source_reset_n := x.source_reset_n
x.sink_reset_n := !sink.reset
@ -257,8 +261,10 @@ object ToAsyncBundle
x.ready := source.io.enq.ready
val out = Wire(new AsyncBundle(depth, x.bits))
source.io.ridx := out.ridx
source.io.ridx_valid := out.ridx_valid
out.mem := source.io.mem
out.widx := source.io.widx
out.widx_valid := source.io.widx_valid
source.io.sink_reset_n := out.sink_reset_n
out.source_reset_n := !source.reset
out

9
src/main/scala/uncore/tilelink2/Crossing.scala
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@ -25,15 +25,10 @@ class TLAsyncCrossingSource(sync: Int = 3) extends LazyModule
out.a <> ToAsyncBundle(in.a, depth, sync)
in.d <> FromAsyncBundle(out.d, sync)
assert (!in.a.valid || sink_reset_n, "A channel request sent to a missing manager")
if (bce) {
in.b <> FromAsyncBundle(out.b, sync)
out.c <> ToAsyncBundle(in.c, depth, sync)
out.e <> ToAsyncBundle(in.e, depth, sync)
assert (!in.c.valid || sink_reset_n, "C channel response sent to a missing manager")
assert (!in.e.valid || sink_reset_n, "E channel response sent to a missing manager")
} else {
in.b.valid := Bool(false)
in.c.ready := Bool(true)
@ -63,14 +58,10 @@ class TLAsyncCrossingSink(depth: Int = 8, sync: Int = 3) extends LazyModule
out.a <> FromAsyncBundle(in.a, sync)
in.d <> ToAsyncBundle(out.d, depth, sync)
assert (!out.d.valid || source_reset_n, "D channel respose sent to missing client")
if (bce) {
in.b <> ToAsyncBundle(out.b, depth, sync)
out.c <> FromAsyncBundle(in.c, sync)
out.e <> FromAsyncBundle(in.e, sync)
assert (!out.b.valid || source_reset_n, "B channel request sent to missing client")
} else {
in.b.widx := UInt(0)
in.c.ridx := UInt(0)

71
src/main/scala/uncore/tilelink2/Isolation.scala
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@ -22,44 +22,47 @@ class TLIsolation(fOut: (Bool, UInt) => UInt, fIn: (Bool, UInt) => UInt) extends
def ISOo[T <: Data](x: T): T = x.fromBits(fOut(io.iso_out, x.asUInt))
def ISOi[T <: Data](x: T): T = x.fromBits(fIn (io.iso_in, x.asUInt))
def ABo[T <: Data](x: AsyncBundle[T], y: AsyncBundle[T]) {
x.mem := ISOo(y.mem)
x.widx := ISOo(y.widx)
x.widx_valid := ISOo(y.widx_valid)
x.source_reset_n := ISOo(y.source_reset_n)
y.ridx := ISOi(x.ridx)
y.ridx_valid := ISOi(x.ridx_valid)
y.sink_reset_n := ISOi(x.sink_reset_n)
}
def ABi[T <: Data](x: AsyncBundle[T], y: AsyncBundle[T]) {
x.mem := ISOi(y.mem)
x.widx := ISOi(y.widx)
x.widx_valid := ISOi(y.widx_valid)
x.source_reset_n := ISOi(y.source_reset_n)
y.ridx := ISOo(x.ridx)
y.ridx_valid := ISOo(x.ridx_valid)
y.sink_reset_n := ISOo(x.sink_reset_n)
}
def ABz[T <: Data](x: AsyncBundle[T], y: AsyncBundle[T]) {
x.widx := UInt(0)
x.widx_valid := Bool(false)
x.source_reset_n := Bool(false)
y.ridx := UInt(0)
y.ridx_valid := Bool(false)
y.sink_reset_n := Bool(false)
}
((io.in zip io.out) zip (node.edgesIn zip node.edgesOut)) foreach { case ((in, out), (edgeIn, edgeOut)) =>
out.a.mem := ISOo(in .a.mem)
out.a.widx := ISOo(in .a.widx)
in .a.ridx := ISOi(out.a.ridx)
out.d.ridx := ISOo(in .d.ridx)
in .d.widx := ISOi(out.d.widx)
in .d.mem := ISOi(out.d.mem)
out.a.source_reset_n := ISOo(in .a.source_reset_n)
in .a.sink_reset_n := ISOi(out.a.sink_reset_n)
out.d.sink_reset_n := ISOo(in .d.sink_reset_n)
in .d.source_reset_n := ISOi(out.d.source_reset_n)
ABo(out.a, in .a)
ABi(in .d, out.d)
if (edgeOut.manager.base.anySupportAcquire && edgeOut.client.base.anySupportProbe) {
in .b.widx := ISOi(out.b.widx)
in .c.ridx := ISOi(out.c.ridx)
in .e.ridx := ISOi(out.e.ridx)
out.b.ridx := ISOo(in .b.ridx)
out.c.widx := ISOo(in .c.widx)
out.e.widx := ISOo(in .e.widx)
in .b.mem := ISOi(out.b.mem)
out.c.mem := ISOo(in .c.mem)
out.e.mem := ISOo(in .e.mem)
out.b.sink_reset_n := ISOo(in .b.sink_reset_n)
in .b.source_reset_n := ISOi(out.b.source_reset_n)
out.c.source_reset_n := ISOo(in .c.source_reset_n)
in .c.sink_reset_n := ISOi(out.c.sink_reset_n)
out.e.source_reset_n := ISOo(in .e.source_reset_n)
in .e.sink_reset_n := ISOi(out.e.sink_reset_n)
ABi(in .b, out.b)
ABo(out.c, in .c)
ABo(out.e, in .e)
} else {
in .b.widx := UInt(0)
in .c.ridx := UInt(0)
in .e.ridx := UInt(0)
out.b.ridx := UInt(0)
out.c.widx := UInt(0)
out.e.widx := UInt(0)
ABz(in .b, out.b)
ABz(out.c, in .c)
ABz(out.e, in .e)
}
}
}

91
src/main/scala/util/AsyncQueue.scala
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@ -27,7 +27,15 @@ object UIntSyncChain {
}
}
class AsyncQueueSource[T <: Data](gen: T, depth: Int, sync: Int) extends Module {
class AsyncValidSync(sync: Int, desc: String) extends Module {
val io = new Bundle {
val in = Bool(INPUT)
val out = Bool(OUTPUT)
}
io.out := UIntSyncChain(io.in.asUInt, sync, desc)(0)
}
class AsyncQueueSource[T <: Data](gen: T, depth: Int, sync: Int, safe: Boolean = true) extends Module {
val bits = log2Ceil(depth)
val io = new Bundle {
// These come from the source domain
@ -36,17 +44,15 @@ class AsyncQueueSource[T <: Data](gen: T, depth: Int, sync: Int) extends Module
val ridx = UInt(INPUT, width = bits+1)
val widx = UInt(OUTPUT, width = bits+1)
val mem = Vec(depth, gen).asOutput
// Reset for the other side
val sink_reset_n = Bool().flip
// Signals used to self-stabilize a safe AsyncQueue
val sink_reset_n = Bool(INPUT)
val ridx_valid = Bool(INPUT)
val widx_valid = Bool(OUTPUT)
}
// extend the sink reset to a full cycle (assertion latency <= 1 cycle)
val catch_sink_reset_n = AsyncResetReg(Bool(true), clock, !io.sink_reset_n, "catch_sink_reset_n")
// reset_n has a 1 cycle shorter path to ready than ridx does
val sink_reset_n = UIntSyncChain(catch_sink_reset_n.asUInt, sync, "sink_reset_n")(0)
val mem = Reg(Vec(depth, gen)) //This does NOT need to be asynchronously reset.
val widx = GrayCounter(bits+1, io.enq.fire(), !sink_reset_n, "widx_bin")
val sink_ready = Wire(init = Bool(true))
val mem = Reg(Vec(depth, gen)) // This does NOT need to be reset at all.
val widx = GrayCounter(bits+1, io.enq.fire(), !sink_ready, "widx_bin")
val ridx = UIntSyncChain(io.ridx, sync, "ridx_gray")
val ready = widx =/= (ridx ^ UInt(depth | depth >> 1))
@ -54,18 +60,33 @@ class AsyncQueueSource[T <: Data](gen: T, depth: Int, sync: Int) extends Module
when (io.enq.fire()) { mem(index) := io.enq.bits }
val ready_reg = AsyncResetReg(ready.asUInt, "ready_reg")(0)
io.enq.ready := ready_reg && sink_reset_n
io.enq.ready := ready_reg && sink_ready
val widx_reg = AsyncResetReg(widx, "widx_gray")
io.widx := widx_reg
io.mem := mem
// It is a fatal error to reset half a Queue while it still has data
assert (sink_reset_n || widx === ridx)
io.widx_valid := Bool(true)
if (safe) {
val source_valid = Module(new AsyncValidSync(sync+1, "source_valid"))
val sink_extend = Module(new AsyncValidSync(1, "sink_extend"))
val sink_valid = Module(new AsyncValidSync(sync, "sink_valid"))
source_valid.reset := reset || !io.sink_reset_n
sink_extend .reset := reset || !io.sink_reset_n
source_valid.io.in := Bool(true)
io.widx_valid := source_valid.io.out
sink_extend.io.in := io.ridx_valid
sink_valid.io.in := sink_extend.io.out
sink_ready := sink_valid.io.out
assert (io.sink_reset_n || !sink_ready || !io.enq.valid, "Enque while sink is reset and AsyncQueueSource is unprotected")
assert (io.sink_reset_n || widx === ridx, "Sink reset while AsyncQueueSource not empty")
}
}
class AsyncQueueSink[T <: Data](gen: T, depth: Int, sync: Int) extends Module {
class AsyncQueueSink[T <: Data](gen: T, depth: Int, sync: Int, safe: Boolean = true) extends Module {
val bits = log2Ceil(depth)
val io = new Bundle {
// These come from the sink domain
@ -74,16 +95,14 @@ class AsyncQueueSink[T <: Data](gen: T, depth: Int, sync: Int) extends Module {
val ridx = UInt(OUTPUT, width = bits+1)
val widx = UInt(INPUT, width = bits+1)
val mem = Vec(depth, gen).asInput
// Reset for the other side
val source_reset_n = Bool().flip
// Signals used to self-stabilize a safe AsyncQueue
val source_reset_n = Bool(INPUT)
val ridx_valid = Bool(OUTPUT)
val widx_valid = Bool(INPUT)
}
// extend the source reset to a full cycle (assertion latency <= 1 cycle)
val catch_source_reset_n = AsyncResetReg(Bool(true), clock, !io.source_reset_n, "catch_source_reset_n")
// reset_n has a 1 cycle shorter path to valid than widx does
val source_reset_n = UIntSyncChain(catch_source_reset_n.asUInt, sync, "source_reset_n")(0)
val ridx = GrayCounter(bits+1, io.deq.fire(), !source_reset_n, "ridx_bin")
val source_ready = Wire(init = Bool(true))
val ridx = GrayCounter(bits+1, io.deq.fire(), !source_ready, "ridx_bin")
val widx = UIntSyncChain(io.widx, sync, "widx_gray")
val valid = ridx =/= widx
@ -99,22 +118,36 @@ class AsyncQueueSink[T <: Data](gen: T, depth: Int, sync: Int) extends Module {
io.deq.bits := RegEnable(io.mem(index), valid)
val valid_reg = AsyncResetReg(valid.asUInt, "valid_reg")(0)
io.deq.valid := valid_reg && source_reset_n
io.deq.valid := valid_reg && source_ready
val ridx_reg = AsyncResetReg(ridx, "ridx_gray")
io.ridx := ridx_reg
// It is a fatal error to reset half a Queue while it still has data
assert (source_reset_n || widx === ridx)
io.ridx_valid := Bool(true)
if (safe) {
val sink_valid = Module(new AsyncValidSync(sync+1, "sink_valid"))
val source_extend = Module(new AsyncValidSync(1, "source_extend"))
val source_valid = Module(new AsyncValidSync(sync, "source_valid"))
sink_valid .reset := reset || !io.source_reset_n
source_extend.reset := reset || !io.source_reset_n
sink_valid.io.in := Bool(true)
io.ridx_valid := sink_valid.io.out
source_extend.io.in := io.widx_valid
source_valid.io.in := source_extend.io.out
source_ready := source_valid.io.out
assert (io.source_reset_n || widx === ridx, "Source reset while AsyncQueueSink not empty")
}
}
class AsyncQueue[T <: Data](gen: T, depth: Int = 8, sync: Int = 3) extends Crossing[T] {
class AsyncQueue[T <: Data](gen: T, depth: Int = 8, sync: Int = 3, safe: Boolean = true) extends Crossing[T] {
require (sync >= 2)
require (depth > 0 && isPow2(depth))
val io = new CrossingIO(gen)
val source = Module(new AsyncQueueSource(gen, depth, sync))
val sink = Module(new AsyncQueueSink (gen, depth, sync))
val source = Module(new AsyncQueueSource(gen, depth, sync, safe))
val sink = Module(new AsyncQueueSink (gen, depth, sync, safe))
source.clock := io.enq_clock
source.reset := io.enq_reset
@ -130,4 +163,6 @@ class AsyncQueue[T <: Data](gen: T, depth: Int = 8, sync: Int = 3) extends Cross
sink.io.mem := source.io.mem
sink.io.widx := source.io.widx
source.io.ridx := sink.io.ridx
sink.io.widx_valid := source.io.widx_valid
source.io.ridx_valid := sink.io.ridx_valid
}