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Bundles.md

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Rocket/tilelink/Bundles

TileLink channel definitions.

object TLMessages

Constants to define message types

Type of TileLink transactions

Type ID A B C D E Data Description Response
PutFullData 0 * * * Write a block AccessAck
PutPartialData 1 * * * Write a partial block AccessAck
ArithmeticData 2 * * * Arithmetic atomic (AMO) AccessAckData
LogicalData 3 * * * Logic AMO AccessAckData
Get 4 * * Get a block AccessAckData
Hint 5 * * Prefetch a block HintAck
Acquire 6 * Coherent request Grant[Data]
Probe 6 * Coherent enquiry ProbeAck[Data]
AccessAck 0 * * Ack to Put(write)
AccessAckData 1 * * Ack to Get/AMO
HintAck 2 * * Ack to Hint
ProbeAck 4 * Ack to Probe without data
ProbeAckData 5 * * Ack to Probe with data
Release 6 * Replace clean block ReleaseAck
ReleaseData 7 * * Writeback dirty block ReleaseAck
Grant 4 * Permission promotion GrantAck
GrantData 5 * * Fetch data GrantAck
ReleaseAck 6 * Ack to Release[Data]
GrantAck 0 * Ack to Grant (strong order)

TileLink channels

Name Direction Response Base classes Coherence
A downwards D TLChannel < TLDataChannel < TLAddrChannel U/C
B upwards C TLChannel < TLDataChannel < TLAddrChannel C
C downwards TLChannel < TLDataChannel < TLAddrChannel C
D upwards E TLChannel < TLDataChannel U/C
E downwards TLChannel C

Communication pattern:

  • client -> master: A -> D ( -> E if cached)
  • master -> client: B -> C

object TLPermissions

The three primary TileLink permissions are:

  • (T)runk: the agent is (or is on inwards path to) the global point of serialization.
  • (B)ranch: the agent is on an outwards path to
  • (N)one:

These permissions are permuted by transfer operations in various ways. Operations can cap permissions, request for them to be grown or shrunk, or for a report on their current status.

Cap types (Grant = new permissions, Probe = permisions <= target)

  • toT () => 0.U
  • toB () => 1.U
  • toN () => 2.U
  • isCap (x: UInt) => x <= toN

Grow types (Acquire = permissions >= target)

  • NtoB () => 0.U
  • NtoT () => 1.U
  • BtoT () => 2.U
  • isGrow (x: UInt) => x <= BtoT

Shrink types (ProbeAck, Release)

  • TtoB () => 0.U
  • TtoN () => 1.U
  • BtoN () => 2.U
  • isShrink (x: UInt) => x <= BtoN

Report types (ProbeAck)

  • TtoT () => 3.U
  • BtoB () => 4.U
  • NtoN () => 5.U
  • isReport (x: UInt) => x <= NtoN

object TLAtomics

Command for atomic operations

Arithmetic types

  • MIN () => 0.U
  • MAX () => 1.U
  • MINU () => 2.U
  • MAXU () => 3.U
  • ADD () => 4.U
  • isArithmetic (x: UInt) => x <= ADD

Logical types

  • XOR () => 0.U
  • OR () => 1.U
  • AND () => 2.U
  • SWAP () => 3.U
  • isLogical (x: UInt) => x <= SWAP

object TLHints

Type of prefetch hints

  • PREFETCH_READ () => 0.U
  • PREFETCH_WRITE () => 1.U

final class TLBundle{A,B,C,D,E}

Channel definitions

  • channelName: channel name.
  • opcode: message type.
  • param: command for either Atomic, Permission or Hint.
  • size: TODO number of beats?
  • source: to be used as a part of the target client id for B and D.
  • address: address to identify master.
  • mask: byte mask (assume 1-bit per byte!).
  • data: data (so must be integer number of bytes).
  • error: indicating error in response packets.
  • addr_lo: lower address in channel D (beat id).
  • sink: to be used as a part of the target manager id for E.

Assumption: TODO

  • The beats in a burst on channel A, B and C must be in order.
  • The beats in a burst on channel D can be out of order? TODO

class TLBundle

  • a,b,c,d,e DecoupledIO[TLBundleX] the tilelink sub-channels.

object TLBundle

  • apply () => TLBundle TLBundle generator.

class TLBundleSnoop

  • a,b,c,d,e DecoupledIO[TLBundleX] the tilelink sub-channel. All directionless.

object TLBundleSnoop

A snoop point for a monitor to passively monitor a bus

  • apply () => TLBundleSnoop TLBundleSnoop generator.

class TLAsyncBundle

Tilink channel for asynchronous crossing.

  • a,b,c,d,e AsyncBundle[TLBundleX] the tilelink sub-channels.

class TLRationalBundle

Tilink channel for rational crossing.

  • a,b,c,d,e RationalIO[TLBundleX] the tilelink sub-channels.




Last updated: 21/07/2017
CC BY-NC-SA 4.0, © (2017) Wei Song
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