gem5/dev/io_device.hh

/*
 * Copyright (c) 2004-2005 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.
 */

#ifndef __DEV_IO_DEVICE_HH__
#define __DEV_IO_DEVICE_HH__

#include "base/chunk_generator.hh"
#include "mem/port.hh"
#include "sim/eventq.hh"
#include "sim/sim_object.hh"

class Platform;
class PioDevice;
class DmaDevice;

/**
 * The PioPort class is a programmed i/o port that all devices that are
 * sensitive to an address range use. The port takes all the memory
 * access types and roles them into one read() and write() call that the device
 * must respond to. The device must also provide the addressRanges() function
 * with which it returns the address ranges it is interested in. An extra
 * sendTiming() function is implemented which takes an delay. In this way the
 * device can immediatly call sendTiming(pkt, time) after processing a request
 * and the request will be handled by the port even if the port bus the device
 * connects to is blocked.
 */
class PioPort : public Port
{
  protected:
    /** The device that this port serves. */
    PioDevice *device;

    /** The platform that device/port are in. This is used to select which mode
     * we are currently operating in. */
    Platform *platform;

    /** A list of outgoing timing response packets that haven't been serviced
     * yet. */
    std::list<Packet*> transmitList;

    /** The current status of the peer(bus) that we are connected to. */
    Status peerStatus;

    virtual bool recvTiming(Packet &pkt);

    virtual Tick recvAtomic(Packet &pkt);

    virtual void recvFunctional(Packet &pkt) ;

    virtual void recvStatusChange(Status status)
    { peerStatus = status; }

    virtual void getDeviceAddressRanges(AddrRangeList &range_list, bool &owner);

    /**
     * This class is used to implemented sendTiming() with a delay. When a delay
     * is requested a new event is created. When the event time expires it
     * attempts to send the packet. If it cannot, the packet is pushed onto the
     * transmit list to be sent when recvRetry() is called. */
    class SendEvent : public Event
    {
        PioPort *port;
        Packet packet;

        SendEvent(PioPort *p, Packet &pkt, Tick t)
            : Event(&mainEventQueue), packet(pkt)
        { schedule(curTick + t); }

        virtual void process();

        virtual const char *description()
        { return "Future scheduled sendTiming event"; }

        friend class PioPort;
    };

    /** Schedule a sendTiming() event to be called in the future. */
    void sendTiming(Packet &pkt, Tick time)
    { new PioPort::SendEvent(this, pkt, time); }

    /** This function pops the last element off the transmit list and sends it.*/
    virtual Packet *recvRetry();

  public:
    PioPort(PioDevice *dev, Platform *p);

  friend class PioPort::SendEvent;
};

class DmaPort : public Port
{
  protected:
    PioDevice *device;
    std::list<Packet*> transmitList;
    Event *completionEvent;


    virtual bool recvTiming(Packet &pkt);
    virtual Tick recvAtomic(Packet &pkt)
    { panic("dma port shouldn't be used for pio access."); }
    virtual void recvFunctional(Packet &pkt)
    { panic("dma port shouldn't be used for pio access."); }

    virtual void recvStatusChange(Status status)
    { ; }

    virtual Packet *recvRetry() ;

    virtual void getDeviceAddressRanges(AddrRangeList &range_list, bool &owner)
    { range_list.clear(); owner = true; }

    class SendEvent : public Event
    {
        DmaPort *port;
        Packet packet;

        SendEvent(PioPort *p, Packet &pkt, Tick t)
            : Event(&mainEventQueue), packet(pkt)
        { schedule(curTick + t); }

        virtual void process();

        virtual const char *description()
        { return "Future scheduled sendTiming event"; }

        friend class DmaPort;
    };

    void dmaAction(Command cmd, DmaPort port, Addr addr, int size,
              Event *event, uint8_t *data = NULL);

    void sendDma(Packet &pkt);

  public:
    DmaPort(DmaDevice *dev);

  friend class DmaPort::SendEvent;

};

/**
 * This device is the base class which all devices senstive to an address range
 * inherit from. There are three pure virtual functions which all devices must
 * implement addressRanges(), read(), and write(). The magic do choose which
 * mode we are in, etc is handled by the PioPort so the device doesn't have to
 * bother.
 */

class PioDevice : public SimObject
{
  protected:

    /** The platform we are in. This is used to decide what type of memory
     * transaction we should perform. */
    Platform *platform;

    /** The pioPort that handles the requests for us and provides us requests
     * that it sees. */
    PioPort *pioPort;

    virtual void addressRanges(AddrRangeList &range_list, bool &owner) = 0;

    /** As far as the devices are concerned they only accept atomic transactions
     * which are converted to either a write or a read. */
    Tick recvAtomic(Packet &pkt)
    { return pkt.cmd == Read ? this->read(pkt) : this->write(pkt); }

    /** Pure virtual function that the device must implement. Called when a read
     * command is recieved by the port. */
    virtual bool read(Packet &pkt) = 0;

    /** Pure virtual function that the device must implement. Called when a
     * write command is recieved by the port. */
    virtual bool write(Packet &pkt) = 0;

  public:
    PioDevice(const std::string &name, Platform *p);

    virtual ~PioDevice();

    virtual Port *getPort(const std::string &if_name)
    {
        if (if_name == "pio")
            return pioPort;
        else
            return NULL;
    }
    friend class PioPort;

};

class DmaDevice : public PioDevice
{
  protected:
    DmaPort *dmaPort;

  public:
    DmaDevice(const std::string &name, Platform *p);
    virtual ~DmaDevice();

    virtual Port *getPort(const std::string &if_name)
    {
        if (if_name == "pio")
            return pioPort;
        else if (if_name == "dma")
            return dmaPort;
        else
            return NULL;
    }

    friend class DmaPort;
};


#endif // __DEV_IO_DEVICE_HH__