gem5/src/mem/noncoherent_bus.hh

/*
 * Copyright (c) 2011-2013 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Copyright (c) 2002-2005 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Ron Dreslinski
 *          Ali Saidi
 *          Andreas Hansson
 *          William Wang
 */

/**
 * @file
 * Declaration of a non-coherent bus.
 */

#ifndef __MEM_NONCOHERENT_BUS_HH__
#define __MEM_NONCOHERENT_BUS_HH__

#include "mem/bus.hh"
#include "params/NoncoherentBus.hh"

/**
 * A non-coherent bus connects a number of non-snooping masters and
 * slaves, and routes the request and response packets based on the
 * address. The request packets issued by the master connected to a
 * non-coherent bus could still snoop in caches attached to a coherent
 * bus, as is the case with the I/O bus and memory bus in most system
 * configurations. No snoops will, however, reach any master on the
 * non-coherent bus itself.
 *
 * The non-coherent bus can be used as a template for modelling PCI,
 * PCIe, and non-coherent AMBA and OCP buses, and is typically used
 * for the I/O buses.
 */
class NoncoherentBus : public BaseBus
{

  protected:

    /**
     * Declare the layers of this bus, one vector for requests and one
     * for responses.
     */
    typedef Layer<SlavePort,MasterPort> ReqLayer;
    typedef Layer<MasterPort,SlavePort> RespLayer;
    std::vector<ReqLayer*> reqLayers;
    std::vector<RespLayer*> respLayers;

    /**
     * Declaration of the non-coherent bus slave port type, one will
     * be instantiated for each of the master ports connecting to the
     * bus.
     */
    class NoncoherentBusSlavePort : public SlavePort
    {
      private:

        /** A reference to the bus to which this port belongs. */
        NoncoherentBus &bus;

      public:

        NoncoherentBusSlavePort(const std::string &_name,
                                NoncoherentBus &_bus, PortID _id)
            : SlavePort(_name, &_bus, _id), bus(_bus)
        { }

      protected:

        /**
         * When receiving a timing request, pass it to the bus.
         */
        virtual bool recvTimingReq(PacketPtr pkt)
        { return bus.recvTimingReq(pkt, id); }

        /**
         * When receiving an atomic request, pass it to the bus.
         */
        virtual Tick recvAtomic(PacketPtr pkt)
        { return bus.recvAtomic(pkt, id); }

        /**
         * When receiving a functional request, pass it to the bus.
         */
        virtual void recvFunctional(PacketPtr pkt)
        { bus.recvFunctional(pkt, id); }

        /**
         * When receiving a retry, pass it to the bus.
         */
        virtual void recvRetry()
        { panic("Bus slave ports always succeed and should never retry.\n"); }

        /**
         * Return the union of all adress ranges seen by this bus.
         */
        virtual AddrRangeList getAddrRanges() const
        { return bus.getAddrRanges(); }

    };

    /**
     * Declaration of the bus master port type, one will be
     * instantiated for each of the slave ports connecting to the
     * bus.
     */
    class NoncoherentBusMasterPort : public MasterPort
    {
      private:

        /** A reference to the bus to which this port belongs. */
        NoncoherentBus &bus;

      public:

        NoncoherentBusMasterPort(const std::string &_name,
                                 NoncoherentBus &_bus, PortID _id)
            : MasterPort(_name, &_bus, _id), bus(_bus)
        { }

      protected:

        /**
         * When receiving a timing response, pass it to the bus.
         */
        virtual bool recvTimingResp(PacketPtr pkt)
        { return bus.recvTimingResp(pkt, id); }

        /** When reciving a range change from the peer port (at id),
            pass it to the bus. */
        virtual void recvRangeChange()
        { bus.recvRangeChange(id); }

        /** When reciving a retry from the peer port (at id),
            pass it to the bus. */
        virtual void recvRetry()
        { bus.recvRetry(id); }

    };

    /** Function called by the port when the bus is recieving a Timing
      request packet.*/
    virtual bool recvTimingReq(PacketPtr pkt, PortID slave_port_id);

    /** Function called by the port when the bus is recieving a Timing
      response packet.*/
    virtual bool recvTimingResp(PacketPtr pkt, PortID master_port_id);

    /** Timing function called by port when it is once again able to process
     * requests. */
    void recvRetry(PortID master_port_id);

    /** Function called by the port when the bus is recieving a Atomic
      transaction.*/
    Tick recvAtomic(PacketPtr pkt, PortID slave_port_id);

    /** Function called by the port when the bus is recieving a Functional
        transaction.*/
    void recvFunctional(PacketPtr pkt, PortID slave_port_id);

  public:

    NoncoherentBus(const NoncoherentBusParams *p);

    virtual ~NoncoherentBus();

    unsigned int drain(DrainManager *dm);

    /**
     * stats
     */
    virtual void regStats();
    Stats::Scalar dataThroughBus;
};

#endif //__MEM_NONCOHERENT_BUS_HH__