411 lines
14 KiB
C++
411 lines
14 KiB
C++
/*
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* Copyright (c) 2011-2015 ARM Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Copyright (c) 2002-2005 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Ron Dreslinski
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* Ali Saidi
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* Andreas Hansson
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* William Wang
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*/
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/**
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* @file
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* Declaration of a coherent crossbar.
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*/
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#ifndef __MEM_COHERENT_XBAR_HH__
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#define __MEM_COHERENT_XBAR_HH__
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#include "mem/snoop_filter.hh"
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#include "mem/xbar.hh"
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#include "params/CoherentXBar.hh"
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/**
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* A coherent crossbar connects a number of (potentially) snooping
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* masters and slaves, and routes the request and response packets
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* based on the address, and also forwards all requests to the
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* snoopers and deals with the snoop responses.
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*
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* The coherent crossbar can be used as a template for modelling QPI,
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* HyperTransport, ACE and coherent OCP buses, and is typically used
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* for the L1-to-L2 buses and as the main system interconnect. @sa
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* \ref gem5MemorySystem "gem5 Memory System"
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*/
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class CoherentXBar : public BaseXBar
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{
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protected:
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/**
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* Declare the layers of this crossbar, one vector for requests,
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* one for responses, and one for snoop responses
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*/
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std::vector<ReqLayer*> reqLayers;
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std::vector<RespLayer*> respLayers;
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std::vector<SnoopRespLayer*> snoopLayers;
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/**
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* Declaration of the coherent crossbar slave port type, one will
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* be instantiated for each of the master ports connecting to the
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* crossbar.
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*/
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class CoherentXBarSlavePort : public QueuedSlavePort
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{
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private:
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/** A reference to the crossbar to which this port belongs. */
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CoherentXBar &xbar;
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/** A normal packet queue used to store responses. */
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RespPacketQueue queue;
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public:
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CoherentXBarSlavePort(const std::string &_name,
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CoherentXBar &_xbar, PortID _id)
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: QueuedSlavePort(_name, &_xbar, queue, _id), xbar(_xbar),
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queue(_xbar, *this)
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{ }
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protected:
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/**
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* When receiving a timing request, pass it to the crossbar.
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*/
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virtual bool recvTimingReq(PacketPtr pkt)
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{ return xbar.recvTimingReq(pkt, id); }
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/**
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* When receiving a timing snoop response, pass it to the crossbar.
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*/
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virtual bool recvTimingSnoopResp(PacketPtr pkt)
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{ return xbar.recvTimingSnoopResp(pkt, id); }
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/**
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* When receiving an atomic request, pass it to the crossbar.
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*/
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virtual Tick recvAtomic(PacketPtr pkt)
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{ return xbar.recvAtomic(pkt, id); }
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/**
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* When receiving a functional request, pass it to the crossbar.
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*/
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virtual void recvFunctional(PacketPtr pkt)
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{ xbar.recvFunctional(pkt, id); }
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/**
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* Return the union of all adress ranges seen by this crossbar.
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*/
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virtual AddrRangeList getAddrRanges() const
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{ return xbar.getAddrRanges(); }
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};
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/**
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* Declaration of the coherent crossbar master port type, one will be
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* instantiated for each of the slave interfaces connecting to the
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* crossbar.
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*/
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class CoherentXBarMasterPort : public MasterPort
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{
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private:
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/** A reference to the crossbar to which this port belongs. */
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CoherentXBar &xbar;
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public:
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CoherentXBarMasterPort(const std::string &_name,
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CoherentXBar &_xbar, PortID _id)
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: MasterPort(_name, &_xbar, _id), xbar(_xbar)
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{ }
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protected:
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/**
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* Determine if this port should be considered a snooper. For
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* a coherent crossbar master port this is always true.
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*
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* @return a boolean that is true if this port is snooping
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*/
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virtual bool isSnooping() const
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{ return true; }
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/**
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* When receiving a timing response, pass it to the crossbar.
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*/
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virtual bool recvTimingResp(PacketPtr pkt)
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{ return xbar.recvTimingResp(pkt, id); }
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/**
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* When receiving a timing snoop request, pass it to the crossbar.
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*/
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virtual void recvTimingSnoopReq(PacketPtr pkt)
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{ return xbar.recvTimingSnoopReq(pkt, id); }
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/**
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* When receiving an atomic snoop request, pass it to the crossbar.
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*/
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virtual Tick recvAtomicSnoop(PacketPtr pkt)
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{ return xbar.recvAtomicSnoop(pkt, id); }
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/**
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* When receiving a functional snoop request, pass it to the crossbar.
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*/
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virtual void recvFunctionalSnoop(PacketPtr pkt)
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{ xbar.recvFunctionalSnoop(pkt, id); }
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/** When reciving a range change from the peer port (at id),
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pass it to the crossbar. */
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virtual void recvRangeChange()
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{ xbar.recvRangeChange(id); }
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/** When reciving a retry from the peer port (at id),
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pass it to the crossbar. */
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virtual void recvReqRetry()
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{ xbar.recvReqRetry(id); }
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};
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/**
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* Internal class to bridge between an incoming snoop response
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* from a slave port and forwarding it through an outgoing slave
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* port. It is effectively a dangling master port.
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*/
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class SnoopRespPort : public MasterPort
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{
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private:
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/** The port which we mirror internally. */
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QueuedSlavePort& slavePort;
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public:
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/**
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* Create a snoop response port that mirrors a given slave port.
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*/
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SnoopRespPort(QueuedSlavePort& slave_port, CoherentXBar& _xbar) :
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MasterPort(slave_port.name() + ".snoopRespPort", &_xbar),
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slavePort(slave_port) { }
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/**
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* Override the sending of retries and pass them on through
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* the mirrored slave port.
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*/
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void sendRetryResp() {
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// forward it as a snoop response retry
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slavePort.sendRetrySnoopResp();
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}
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/**
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* Provided as necessary.
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*/
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void recvReqRetry() { panic("SnoopRespPort should never see retry\n"); }
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/**
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* Provided as necessary.
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*/
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bool recvTimingResp(PacketPtr pkt)
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{
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panic("SnoopRespPort should never see timing response\n");
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return false;
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}
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};
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std::vector<SnoopRespPort*> snoopRespPorts;
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std::vector<QueuedSlavePort*> snoopPorts;
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/**
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* Store the outstanding requests that we are expecting snoop
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* responses from so we can determine which snoop responses we
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* generated and which ones were merely forwarded.
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*/
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std::unordered_set<RequestPtr> outstandingSnoop;
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/**
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* Keep a pointer to the system to be allow to querying memory system
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* properties.
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*/
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System *system;
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/** A snoop filter that tracks cache line residency and can restrict the
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* broadcast needed for probes. NULL denotes an absent filter. */
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SnoopFilter *snoopFilter;
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/** Cycles of snoop response latency.*/
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const Cycles snoopResponseLatency;
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/** Is this crossbar the point of coherency? **/
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const bool pointOfCoherency;
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/**
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* Upstream caches need this packet until true is returned, so
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* hold it for deletion until a subsequent call
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*/
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std::unique_ptr<Packet> pendingDelete;
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/** Function called by the port when the crossbar is recieving a Timing
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request packet.*/
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bool recvTimingReq(PacketPtr pkt, PortID slave_port_id);
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/** Function called by the port when the crossbar is recieving a Timing
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response packet.*/
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bool recvTimingResp(PacketPtr pkt, PortID master_port_id);
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/** Function called by the port when the crossbar is recieving a timing
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snoop request.*/
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void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id);
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/** Function called by the port when the crossbar is recieving a timing
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snoop response.*/
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bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id);
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/** Timing function called by port when it is once again able to process
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* requests. */
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void recvReqRetry(PortID master_port_id);
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/**
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* Forward a timing packet to our snoopers, potentially excluding
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* one of the connected coherent masters to avoid sending a packet
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* back to where it came from.
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*
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* @param pkt Packet to forward
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* @param exclude_slave_port_id Id of slave port to exclude
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*/
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void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id) {
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forwardTiming(pkt, exclude_slave_port_id, snoopPorts);
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}
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/**
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* Forward a timing packet to a selected list of snoopers, potentially
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* excluding one of the connected coherent masters to avoid sending a packet
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* back to where it came from.
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*
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* @param pkt Packet to forward
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* @param exclude_slave_port_id Id of slave port to exclude
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* @param dests Vector of destination ports for the forwarded pkt
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*/
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void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id,
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const std::vector<QueuedSlavePort*>& dests);
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/** Function called by the port when the crossbar is recieving a Atomic
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transaction.*/
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Tick recvAtomic(PacketPtr pkt, PortID slave_port_id);
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/** Function called by the port when the crossbar is recieving an
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atomic snoop transaction.*/
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Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id);
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/**
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* Forward an atomic packet to our snoopers, potentially excluding
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* one of the connected coherent masters to avoid sending a packet
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* back to where it came from.
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*
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* @param pkt Packet to forward
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* @param exclude_slave_port_id Id of slave port to exclude
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*
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* @return a pair containing the snoop response and snoop latency
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*/
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std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
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PortID exclude_slave_port_id)
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{
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return forwardAtomic(pkt, exclude_slave_port_id, InvalidPortID,
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snoopPorts);
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}
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/**
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* Forward an atomic packet to a selected list of snoopers, potentially
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* excluding one of the connected coherent masters to avoid sending a packet
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* back to where it came from.
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*
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* @param pkt Packet to forward
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* @param exclude_slave_port_id Id of slave port to exclude
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* @param source_master_port_id Id of the master port for snoops from below
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* @param dests Vector of destination ports for the forwarded pkt
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*
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* @return a pair containing the snoop response and snoop latency
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*/
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std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
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PortID exclude_slave_port_id,
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PortID source_master_port_id,
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const std::vector<QueuedSlavePort*>&
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dests);
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/** Function called by the port when the crossbar is recieving a Functional
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transaction.*/
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void recvFunctional(PacketPtr pkt, PortID slave_port_id);
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/** Function called by the port when the crossbar is recieving a functional
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snoop transaction.*/
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void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id);
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/**
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* Forward a functional packet to our snoopers, potentially
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* excluding one of the connected coherent masters to avoid
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* sending a packet back to where it came from.
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*
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* @param pkt Packet to forward
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* @param exclude_slave_port_id Id of slave port to exclude
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*/
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void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id);
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/**
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* Determine if the crossbar should sink the packet, as opposed to
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* forwarding it, or responding.
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*/
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bool sinkPacket(const PacketPtr pkt) const;
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Stats::Scalar snoops;
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Stats::Scalar snoopTraffic;
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Stats::Distribution snoopFanout;
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public:
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virtual void init();
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CoherentXBar(const CoherentXBarParams *p);
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virtual ~CoherentXBar();
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virtual void regStats();
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};
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#endif //__MEM_COHERENT_XBAR_HH__
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