167 lines
6.3 KiB
Scala
167 lines
6.3 KiB
Scala
// See LICENSE.SiFive for license details.
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// See LICENSE.Berkeley for license details.
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package freechips.rocketchip.tilelink
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import Chisel._
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import chisel3.internal.sourceinfo.SourceInfo
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import freechips.rocketchip.rocket.constants.MemoryOpConstants
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import freechips.rocketchip.util._
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object ClientStates {
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val width = 2
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def Nothing = UInt(0, width)
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def Branch = UInt(1, width)
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def Trunk = UInt(2, width)
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def Dirty = UInt(3, width)
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def hasReadPermission(state: UInt): Bool = state > Nothing
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def hasWritePermission(state: UInt): Bool = state > Branch
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}
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object MemoryOpCategories extends MemoryOpConstants {
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def wr = Cat(Bool(true), Bool(true)) // Op actually writes
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def wi = Cat(Bool(false), Bool(true)) // Future op will write
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def rd = Cat(Bool(false), Bool(false)) // Op only reads
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def categorize(cmd: UInt): UInt = {
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val cat = Cat(isWrite(cmd), isWriteIntent(cmd))
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//assert(cat.isOneOf(wr,wi,rd), "Could not categorize command.")
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cat
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}
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}
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/** Stores the client-side coherence information,
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* such as permissions on the data and whether the data is dirty.
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* Its API can be used to make TileLink messages in response to
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* memory operations, cache control oeprations, or Probe messages.
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*/
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class ClientMetadata extends Bundle {
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/** Actual state information stored in this bundle */
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val state = UInt(width = ClientStates.width)
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/** Metadata equality */
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def ===(rhs: UInt): Bool = state === rhs
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def ===(rhs: ClientMetadata): Bool = state === rhs.state
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def =/=(rhs: ClientMetadata): Bool = !this.===(rhs)
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/** Is the block's data present in this cache */
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def isValid(dummy: Int = 0): Bool = state > ClientStates.Nothing
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/** Determine whether this cmd misses, and the new state (on hit) or param to be sent (on miss) */
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private def growStarter(cmd: UInt): (Bool, UInt) = {
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import MemoryOpCategories._
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import TLPermissions._
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import ClientStates._
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val c = categorize(cmd)
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MuxTLookup(Cat(c, state), (Bool(false), UInt(0)), Seq(
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//(effect, am now) -> (was a hit, next)
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Cat(rd, Dirty) -> (Bool(true), Dirty),
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Cat(rd, Trunk) -> (Bool(true), Trunk),
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Cat(rd, Branch) -> (Bool(true), Branch),
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Cat(wi, Dirty) -> (Bool(true), Dirty),
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Cat(wi, Trunk) -> (Bool(true), Trunk),
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Cat(wr, Dirty) -> (Bool(true), Dirty),
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Cat(wr, Trunk) -> (Bool(true), Dirty),
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//(effect, am now) -> (was a miss, param)
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Cat(rd, Nothing) -> (Bool(false), NtoB),
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Cat(wi, Branch) -> (Bool(false), BtoT),
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Cat(wi, Nothing) -> (Bool(false), NtoT),
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Cat(wr, Branch) -> (Bool(false), BtoT),
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Cat(wr, Nothing) -> (Bool(false), NtoT)))
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}
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/** Determine what state to go to after miss based on Grant param
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* For now, doesn't depend on state (which may have been Probed).
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*/
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private def growFinisher(cmd: UInt, param: UInt): UInt = {
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import MemoryOpCategories._
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import TLPermissions._
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import ClientStates._
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val c = categorize(cmd)
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//assert(c === rd || param === toT, "Client was expecting trunk permissions.")
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MuxLookup(Cat(c, param), Nothing, Seq(
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//(effect param) -> (next)
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Cat(rd, toB) -> Branch,
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Cat(rd, toT) -> Trunk,
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Cat(wi, toT) -> Trunk,
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Cat(wr, toT) -> Dirty))
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}
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/** Does this cache have permissions on this block sufficient to perform op,
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* and what to do next (Acquire message param or updated metadata). */
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def onAccess(cmd: UInt): (Bool, UInt, ClientMetadata) = {
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val r = growStarter(cmd)
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(r._1, r._2, ClientMetadata(r._2))
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}
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/** Does a secondary miss on the block require another Acquire message */
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def onSecondaryAccess(first_cmd: UInt, second_cmd: UInt): (Bool, Bool, UInt, ClientMetadata, UInt) = {
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import MemoryOpCategories._
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val r1 = growStarter(first_cmd)
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val r2 = growStarter(second_cmd)
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val needs_second_acq = isWriteIntent(second_cmd) && !isWriteIntent(first_cmd)
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val hit_again = r1._1 && r2._1
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val dirties = categorize(second_cmd) === wr
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val biggest_grow_param = Mux(dirties, r2._2, r1._2)
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val dirtiest_state = ClientMetadata(biggest_grow_param)
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val dirtiest_cmd = Mux(dirties, second_cmd, first_cmd)
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(needs_second_acq, hit_again, biggest_grow_param, dirtiest_state, dirtiest_cmd)
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}
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/** Metadata change on a returned Grant */
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def onGrant(cmd: UInt, param: UInt): ClientMetadata = ClientMetadata(growFinisher(cmd, param))
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/** Determine what state to go to based on Probe param */
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private def shrinkHelper(param: UInt): (Bool, UInt, UInt) = {
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import ClientStates._
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import TLPermissions._
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MuxTLookup(Cat(param, state), (Bool(false), UInt(0), UInt(0)), Seq(
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//(wanted, am now) -> (hasDirtyData resp, next)
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Cat(toT, Dirty) -> (Bool(true), TtoT, Trunk),
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Cat(toT, Trunk) -> (Bool(false), TtoT, Trunk),
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Cat(toT, Branch) -> (Bool(false), BtoB, Branch),
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Cat(toT, Nothing) -> (Bool(false), NtoN, Nothing),
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Cat(toB, Dirty) -> (Bool(true), TtoB, Branch),
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Cat(toB, Trunk) -> (Bool(false), TtoB, Branch), // Policy: Don't notify on clean downgrade
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Cat(toB, Branch) -> (Bool(false), BtoB, Branch),
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Cat(toB, Nothing) -> (Bool(false), BtoN, Nothing),
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Cat(toN, Dirty) -> (Bool(true), TtoN, Nothing),
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Cat(toN, Trunk) -> (Bool(false), TtoN, Nothing), // Policy: Don't notify on clean downgrade
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Cat(toN, Branch) -> (Bool(false), BtoN, Nothing), // Policy: Don't notify on clean downgrade
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Cat(toN, Nothing) -> (Bool(false), NtoN, Nothing)))
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}
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/** Translate cache control cmds into Probe param */
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private def cmdToPermCap(cmd: UInt): UInt = {
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import MemoryOpCategories._
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import TLPermissions._
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MuxLookup(cmd, toN, Seq(
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M_FLUSH -> toN,
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M_PRODUCE -> toB,
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M_CLEAN -> toT))
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}
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def onCacheControl(cmd: UInt): (Bool, UInt, ClientMetadata) = {
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val r = shrinkHelper(cmdToPermCap(cmd))
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(r._1, r._2, ClientMetadata(r._3))
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}
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def onProbe(param: UInt): (Bool, UInt, ClientMetadata) = {
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val r = shrinkHelper(param)
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(r._1, r._2, ClientMetadata(r._3))
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}
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}
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/** Factories for ClientMetadata, including on reset */
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object ClientMetadata {
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def apply(perm: UInt) = {
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val meta = Wire(new ClientMetadata)
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meta.state := perm
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meta
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}
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def onReset = ClientMetadata(ClientStates.Nothing)
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def maximum = ClientMetadata(ClientStates.Dirty)
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}
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