gem5/mem/port.hh

/*
 * 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
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * @file
 * Port Object Decleration. Ports are used to interface memory objects to
 * each other.  They will always come in pairs, and we refer to the other
 * port object as the peer.  These are used to make the design more
 * modular so that a specific interface between every type of objcet doesn't
 * have to be created.
 */

#ifndef __MEM_PORT_HH__
#define __MEM_PORT_HH__

#include <string>
#include <list>
#include <inttypes.h>

#include "base/misc.hh"
#include "base/range.hh"
#include "mem/packet.hh"
#include "mem/request.hh"

/** This typedef is used to clean up the parameter list of
 * getDeviceAddressRanges() and getPeerAddressRanges().  It's declared
 * outside the Port object since it's also used by some mem objects.
 * Eventually we should move this typedef to wherever Addr is
 * defined.
 */

typedef std::list<Range<Addr> > AddrRangeList;

/**
 * Ports are used to interface memory objects to
 * each other.  They will always come in pairs, and we refer to the other
 * port object as the peer.  These are used to make the design more
 * modular so that a specific interface between every type of objcet doesn't
 * have to be created.
 *
 * Recv accesor functions are being called from the peer interface.
 * Send accessor functions are being called from the device the port is
 * associated with, and it will call the peer recv. accessor function.
 */
class Port
{
  public:

    // mey be better to use subclasses & RTTI?
    /** Holds the ports status.  Keeps track if it is blocked, or has
        calculated a range change. */
    enum Status {
        Blocked,
        Unblocked,
        RangeChange
    };

  private:

    /** A pointer to the peer port.  Ports always come in pairs, that way they
        can use a standardized interface to communicate between different
        memory objects. */
    Port *peer;

  public:

    /** Function to set the pointer for the peer port.
        @todo should be called by the configuration stuff (python).
    */
    void setPeer(Port *port) { peer = port; }

        /** Function to set the pointer for the peer port.
        @todo should be called by the configuration stuff (python).
    */
    Port *getPeer() { return peer; }

  protected:

    /** These functions are protected because they should only be
     * called by a peer port, never directly by any outside object. */

    /** Called to recive a timing call from the peer port. */
    virtual bool recvTiming(Packet &pkt) = 0;

    /** Called to recive a atomic call from the peer port. */
    virtual Tick recvAtomic(Packet &pkt) = 0;

    /** Called to recive a functional call from the peer port. */
    virtual void recvFunctional(Packet &pkt) = 0;

    /** Called to recieve a status change from the peer port. */
    virtual void recvStatusChange(Status status) = 0;

    /** Called by a peer port if the send was unsuccesful, and had to
        wait.  This shouldn't be valid for response paths (IO Devices).
        so it is set to panic if it isn't already defined.
    */
    virtual Packet *recvRetry() { panic("??"); }

    /** Called by a peer port in order to determine the block size of the
        device connected to this port.  It sometimes doesn't make sense for
        this function to be called, a DMA interface doesn't really have a
        block size, so it is defaulted to a panic.
    */
    virtual int deviceBlockSize() { panic("??"); }

    /** The peer port is requesting us to reply with a list of the ranges we
        are responsible for.
        @param owner is an output param that, if set, indicates that the
        port is the owner of the specified ranges (i.e., slave, default
        responder, etc.).  If 'owner' is false, the interface is
        interested in the specified ranges for snooping purposes.  If
        an object wants to own some ranges and snoop on others, it will
        need to use two different ports.
    */
    virtual void getDeviceAddressRanges(AddrRangeList &range_list,
                                        bool &owner)
    { panic("??"); }

  public:

    /** Function called by associated memory device (cache, memory, iodevice)
        in order to send a timing request to the port.  Simply calls the peer
        port receive function.
        @return This function returns if the send was succesful in it's
        recieve. If it was a failure, then the port will wait for a recvRetry
        at which point it can issue a successful sendTiming.  This is used in
        case a cache has a higher priority request come in while waiting for
        the bus to arbitrate.
    */
    bool sendTiming(Packet &pkt) { return peer->recvTiming(pkt); }

    /** Function called by the associated device to send an atomic access,
        an access in which the data is moved and the state is updated in one
        cycle, without interleaving with other memory accesses.
    */
    Tick sendAtomic(Packet &pkt)
        { return peer->recvAtomic(pkt); }

    /** Function called by the associated device to send a functional access,
        an access in which the data is instantly updated everywhere in the
        memory system, without affecting the current state of any block
        or moving the block.
    */
    void sendFunctional(Packet &pkt)
        { return peer->recvFunctional(pkt); }

    /** Called by the associated device to send a status change to the device
        connected to the peer interface.
    */
    void sendStatusChange(Status status) {peer->recvStatusChange(status); }

    /** When a timing access doesn't return a success, some time later the
        Retry will be sent.
    */
    Packet *sendRetry() { return peer->recvRetry(); }

    /** Called by the associated device if it wishes to find out the blocksize
        of the device on attached to the peer port.
    */
    int peerBlockSize() { return peer->deviceBlockSize(); }

    /** Called by the associated device if it wishes to find out the address
        ranges connected to the peer ports devices.
    */
    void getPeerAddressRanges(AddrRangeList &range_list, bool &owner)
    { peer->getDeviceAddressRanges(range_list, owner); }

    /** This function is a wrapper around sendFunctional()
        that breaks a larger, arbitrarily aligned access into
        appropriate chunks.  The default implementation can use
        getBlockSize() to determine the block size and go from there.
    */
    void readBlob(Addr addr, uint8_t *p, int size);

    /** This function is a wrapper around sendFunctional()
        that breaks a larger, arbitrarily aligned access into
        appropriate chunks.  The default implementation can use
        getBlockSize() to determine the block size and go from there.
    */
    void writeBlob(Addr addr, uint8_t *p, int size);

    /** Fill size bytes starting at addr with byte value val.  This
        should not need to be virtual, since it can be implemented in
        terms of writeBlob().  However, it shouldn't be
        performance-critical either, so it could be if we wanted to.
    */
    void memsetBlob(Addr addr, uint8_t val, int size);

  private:

    /** Internal helper function for read/writeBlob().
     */
    void blobHelper(Addr addr, uint8_t *p, int size, Command cmd);
};

#endif //__MEM_PORT_HH__