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tilelink2: clarify ready-valid use of RegisterRouter

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This commit is contained in:
Wesley W. Terpstra 2016-09-04 16:17:20 -07:00
parent e3b3543841
commit 68e64a9859
1 changed files with 8 additions and 8 deletions
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16
src/main/scala/uncore/tilelink2/RegField.scala
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@ -10,16 +10,17 @@ object RegReadFn
// (ivalid: Bool, oready: Bool) => (iready: Bool, ovalid: Bool, data: UInt)
// iready may combinationally depend on oready
// all other combinational dependencies forbidden (e.g. ovalid <= ivalid)
// iready must eventually go high without requiring ivalid to go high
// ovalid must eventually go high without requiring oready to go high
// effects must become visible on the cycle after ovalid && oready
implicit def apply(x: (Bool, Bool) => (Bool, Bool, UInt)) =
new RegReadFn(false, x)
// (ready: Bool) => (valid: Bool, data: UInt)
// valid must not combinationally depend on ready
// valid must eventually go high without requiring ready to go high
// => this means that reading cannot trigger creation of the output data
// if you need this, use the more general i&o ready-valid method above
// effects must become visible on the cycle after valid && ready
// ready is only guaranteed to stay high if fed by an Irrevocable (eg: TL2 or concurrency > 0)
// ... which is irrelevant if you can service the read immediately
// ... if irrevocable, you may start reading on rising ready and raise valid when done
// ... otherwise, use the more general in&out ready-valid method above
implicit def apply(x: Bool => (Bool, UInt)) =
new RegReadFn(true, { case (_, oready) =>
val (ovalid, data) = x(oready)
@ -39,16 +40,15 @@ object RegWriteFn
// (ivalid: Bool, oready: Bool, data: UInt) => (iready: Bool, ovalid: Bool)
// iready may combinationally depend on both oready and data
// all other combinational dependencies forbidden (e.g. ovalid <= ivalid)
// iready must eventually go high without requiring ivalid to go high
// ovalid must eventually go high without requiring oready to go high
// effects must become visible on the cycle after ovalid && oready
implicit def apply(x: (Bool, Bool, UInt) => (Bool, Bool)) =
new RegWriteFn(false, x)
// (valid: Bool, data: UInt) => (ready: Bool)
// ready may combinationally depend on data (but not valid)
// ready must eventually go high without requiring valid to go high
// effects must become visible on the cycle after valid && ready
// valid is only guaranteed to stay high if fed by an Irrevocable (eg: TL2 or concurrency > 0)
// ... which is irrelevant if you can service the write immediately
// ... if irrevocable, you may start writing on rising valid and raise ready when done
// ... otherwise, use the more general in&out ready-valid method above
implicit def apply(x: (Bool, UInt) => Bool) =
// combinational => data valid on oready
new RegWriteFn(true, { case (_, oready, data) =>