riscv/rocket-chip
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ahb: allow no-ops to progress also when a slave is !hready

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This commit is contained in:
Wesley W. Terpstra 2016-06-08 13:11:12 -07:00 committed by Henry Cook
parent 7014eef339
commit 31b72625aa
1 changed files with 15 additions and 5 deletions
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18
uncore/src/main/scala/ahb.scala
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@ -270,6 +270,8 @@ class AHBBusMaster(supportAtomics: Boolean = false)(implicit val p: Parameters)
val respondTL1 = Reg(init = Bool(false))
val latchAtom0 = Reg(init = Bool(false))
val latchAtom1 = Reg(init = Bool(false))
val executeAHB0 = Reg(init = Bool(false))
val executeAHB1 = Reg(init = Bool(false))
val bubble = Reg(init = Bool(true)) // nothing useful in address phase
val cmd = Reg(Bits())
val g_type0 = Reg(UInt())
@ -281,8 +283,8 @@ class AHBBusMaster(supportAtomics: Boolean = false)(implicit val p: Parameters)
val grant1 = Reg(new Grant)
// It is allowed to progress from Idle/Busy during a wait state
val addrReady = io.ahb.hready || bubble
val dataReady = io.ahb.hready
val addrReady = io.ahb.hready || bubble || (!executeAHB1 && !executeAHB0)
val dataReady = io.ahb.hready || !executeAHB1
// Only accept a new AHBRequest if we have enough buffer space in the pad
// to accomodate a persistent drop in TileLink's grant.ready
@ -311,10 +313,12 @@ class AHBBusMaster(supportAtomics: Boolean = false)(implicit val p: Parameters)
when (io.request.fire()) {
respondTL0 := io.request.bits.respondTL
latchAtom0 := io.request.bits.latchAtom
executeAHB0:= io.request.bits.executeAHB
bubble := Bool(false)
} .otherwise {
respondTL0 := Bool(false)
latchAtom0 := Bool(false)
executeAHB0:= Bool(false)
bubble := Bool(true) // an atom-injected Idle is not a bubble!
}
}
@ -347,11 +351,17 @@ class AHBBusMaster(supportAtomics: Boolean = false)(implicit val p: Parameters)
alu.io.lhs := hrdata
// Transfer bulk data phase
// NOTE: this introduces no bubbles because addrReady is a superset of dataReady
when (dataReady) {
hwdata1 := Mux(Bool(supportAtomics), alu.io.out, hwdata0)
when (addrReady) {
respondTL1 := respondTL0
latchAtom1 := latchAtom0
executeAHB1 := executeAHB0
} .otherwise {
respondTL1 := Bool(false)
latchAtom1 := Bool(false)
executeAHB1 := Bool(false)
}
hwdata1 := Mux(Bool(supportAtomics), alu.io.out, hwdata0)
g_type1 := g_type0
client_xact_id1 := client_xact_id0
addr_beat1 := addr_beat0