coherent_xbar.hh

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 * to a hardware implementation of the functionality of the software
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 * Authors: Ron Dreslinski
 *          Ali Saidi
 *          Andreas Hansson
 *          William Wang
 */

#ifndef __MEM_COHERENT_XBAR_HH__
#define __MEM_COHERENT_XBAR_HH__

#include <unordered_set>

#include "mem/snoop_filter.hh"
#include "mem/xbar.hh"
#include "params/CoherentXBar.hh"

class CoherentXBar : public BaseXBar
{

  protected:

    std::vector<ReqLayer*> reqLayers;
    std::vector<RespLayer*> respLayers;
    std::vector<SnoopRespLayer*> snoopLayers;

    class CoherentXBarSlavePort : public QueuedSlavePort
    {

      private:

        CoherentXBar &xbar;

        RespPacketQueue queue;

      public:

        CoherentXBarSlavePort(const std::string &_name,
                             CoherentXBar &_xbar, PortID _id)
            : QueuedSlavePort(_name, &_xbar, queue, _id), xbar(_xbar),
              queue(_xbar, *this)
        { }

      protected:

        virtual bool recvTimingReq(PacketPtr pkt)
        { return xbar.recvTimingReq(pkt, id); }

        virtual bool recvTimingSnoopResp(PacketPtr pkt)
        { return xbar.recvTimingSnoopResp(pkt, id); }

        virtual Tick recvAtomic(PacketPtr pkt)
        { return xbar.recvAtomic(pkt, id); }

        virtual void recvFunctional(PacketPtr pkt)
        { xbar.recvFunctional(pkt, id); }

        virtual AddrRangeList getAddrRanges() const
        { return xbar.getAddrRanges(); }

    };

    class CoherentXBarMasterPort : public MasterPort
    {
      private:
        CoherentXBar &xbar;

      public:

        CoherentXBarMasterPort(const std::string &_name,
                              CoherentXBar &_xbar, PortID _id)
            : MasterPort(_name, &_xbar, _id), xbar(_xbar)
        { }

      protected:

        virtual bool isSnooping() const
        { return true; }

        virtual bool recvTimingResp(PacketPtr pkt)
        { return xbar.recvTimingResp(pkt, id); }

        virtual void recvTimingSnoopReq(PacketPtr pkt)
        { return xbar.recvTimingSnoopReq(pkt, id); }

        virtual Tick recvAtomicSnoop(PacketPtr pkt)
        { return xbar.recvAtomicSnoop(pkt, id); }

        virtual void recvFunctionalSnoop(PacketPtr pkt)
        { xbar.recvFunctionalSnoop(pkt, id); }

        virtual void recvRangeChange()
        { xbar.recvRangeChange(id); }

        virtual void recvReqRetry()
        { xbar.recvReqRetry(id); }

    };

    class SnoopRespPort : public MasterPort
    {

      private:

        QueuedSlavePort& slavePort;

      public:

        SnoopRespPort(QueuedSlavePort& slave_port, CoherentXBar& _xbar) :
            MasterPort(slave_port.name() + ".snoopRespPort", &_xbar),
            slavePort(slave_port) { }

        void sendRetryResp() {
            // forward it as a snoop response retry
            slavePort.sendRetrySnoopResp();
        }

        void recvReqRetry() { panic("SnoopRespPort should never see retry\n"); }

        bool recvTimingResp(PacketPtr pkt)
        {
            panic("SnoopRespPort should never see timing response\n");
            return false;
        }

    };

    std::vector<SnoopRespPort*> snoopRespPorts;

    std::vector<QueuedSlavePort*> snoopPorts;

    std::unordered_set<RequestPtr> outstandingSnoop;

    System *system;

    SnoopFilter *snoopFilter;

    const Cycles snoopResponseLatency;

    const bool pointOfCoherency;

    std::unique_ptr<Packet> pendingDelete;

    bool recvTimingReq(PacketPtr pkt, PortID slave_port_id);

    bool recvTimingResp(PacketPtr pkt, PortID master_port_id);

    void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id);

    bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id);

    void recvReqRetry(PortID master_port_id);

    void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id) {
        forwardTiming(pkt, exclude_slave_port_id, snoopPorts);
    }

    void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id,
                       const std::vector<QueuedSlavePort*>& dests);

    Tick recvAtomic(PacketPtr pkt, PortID slave_port_id);

    Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id);

    std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
                                          PortID exclude_slave_port_id)
    {
        return forwardAtomic(pkt, exclude_slave_port_id, InvalidPortID,
                             snoopPorts);
    }

    std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
                                          PortID exclude_slave_port_id,
                                          PortID source_master_port_id,
                                          const std::vector<QueuedSlavePort*>&
                                          dests);

    void recvFunctional(PacketPtr pkt, PortID slave_port_id);

    void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id);

    void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id);

    bool sinkPacket(const PacketPtr pkt) const;

    Stats::Scalar snoops;
    Stats::Scalar snoopTraffic;
    Stats::Distribution snoopFanout;

  public:

    virtual void init();

    CoherentXBar(const CoherentXBarParams *p);

    virtual ~CoherentXBar();

    virtual void regStats();
};

#endif //__MEM_COHERENT_XBAR_HH__