/*
* Copyright (c) 2011-2014 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 coherent crossbar.
*/
#ifndef __MEM_COHERENT_XBAR_HH__
#define __MEM_COHERENT_XBAR_HH__
#include "base/hashmap.hh"
#include "mem/snoop_filter.hh"
#include "mem/xbar.hh"
#include "params/CoherentXBar.hh"
/**
* A coherent crossbar connects a number of (potentially) snooping
* masters and slaves, and routes the request and response packets
* based on the address, and also forwards all requests to the
* snoopers and deals with the snoop responses.
*
* The coherent crossbar can be used as a template for modelling QPI,
* HyperTransport, ACE and coherent OCP buses, and is typically used
* for the L1-to-L2 buses and as the main system interconnect. @sa
* \ref gem5MemorySystem "gem5 Memory System"
*/
class CoherentXBar : public BaseXBar
{
protected:
/**
* Declare the layers of this crossbar, one vector for requests,
* one for responses, and one for snoop responses
*/
typedef Layer<SlavePort,MasterPort> ReqLayer;
typedef Layer<MasterPort,SlavePort> RespLayer;
typedef Layer<SlavePort,MasterPort> SnoopLayer;
std::vector<ReqLayer*> reqLayers;
std::vector<RespLayer*> respLayers;
std::vector<SnoopLayer*> snoopLayers;
/**
* Declaration of the coherent crossbar slave port type, one will
* be instantiated for each of the master ports connecting to the
* crossbar.
*/
class CoherentXBarSlavePort : public SlavePort
{
private:
/** A reference to the crossbar to which this port belongs. */
CoherentXBar &xbar;
public:
CoherentXBarSlavePort(const std::string &_name,
CoherentXBar &_xbar, PortID _id)
: SlavePort(_name, &_xbar, _id), xbar(_xbar)
{ }
protected:
/**
* When receiving a timing request, pass it to the crossbar.
*/
virtual bool recvTimingReq(PacketPtr pkt)
{ return xbar.recvTimingReq(pkt, id); }
/**
* When receiving a timing snoop response, pass it to the crossbar.
*/
virtual bool recvTimingSnoopResp(PacketPtr pkt)
{ return xbar.recvTimingSnoopResp(pkt, id); }
/**
* When receiving an atomic request, pass it to the crossbar.
*/
virtual Tick recvAtomic(PacketPtr pkt)
{ return xbar.recvAtomic(pkt, id); }
/**
* When receiving a functional request, pass it to the crossbar.
*/
virtual void recvFunctional(PacketPtr pkt)
{ xbar.recvFunctional(pkt, id); }
/**
* When receiving a retry, pass it to the crossbar.
*/
virtual void recvRetry()
{ panic("Crossbar slave ports should never retry.\n"); }
/**
* Return the union of all adress ranges seen by this crossbar.
*/
virtual AddrRangeList getAddrRanges() const
{ return xbar.getAddrRanges(); }
};
/**
* Declaration of the coherent crossbar master port type, one will be
* instantiated for each of the slave interfaces connecting to the
* crossbar.
*/
class CoherentXBarMasterPort : public MasterPort
{
private:
/** A reference to the crossbar to which this port belongs. */
CoherentXBar &xbar;
public:
CoherentXBarMasterPort(const std::string &_name,
CoherentXBar &_xbar, PortID _id)
: MasterPort(_name, &_xbar, _id), xbar(_xbar)
{ }
protected:
/**
* Determine if this port should be considered a snooper. For
* a coherent crossbar master port this is always true.
*
* @return a boolean that is true if this port is snooping
*/
virtual bool isSnooping() const
{ return true; }
/**
* When receiving a timing response, pass it to the crossbar.
*/
virtual bool recvTimingResp(PacketPtr pkt)
{ return xbar.recvTimingResp(pkt, id); }
/**
* When receiving a timing snoop request, pass it to the crossbar.
*/
virtual void recvTimingSnoopReq(PacketPtr pkt)
{ return xbar.recvTimingSnoopReq(pkt, id); }
/**
* When receiving an atomic snoop request, pass it to the crossbar.
*/
virtual Tick recvAtomicSnoop(PacketPtr pkt)
{ return xbar.recvAtomicSnoop(pkt, id); }
/**
* When receiving a functional snoop request, pass it to the crossbar.
*/
virtual void recvFunctionalSnoop(PacketPtr pkt)
{ xbar.recvFunctionalSnoop(pkt, id); }
/** When reciving a range change from the peer port (at id),
pass it to the crossbar. */
virtual void recvRangeChange()
{ xbar.recvRangeChange(id); }
/** When reciving a retry from the peer port (at id),
pass it to the crossbar. */
virtual void recvRetry()
{ xbar.recvRetry(id); }
};
/**
* Internal class to bridge between an incoming snoop response
* from a slave port and forwarding it through an outgoing slave
* port. It is effectively a dangling master port.
*/
class SnoopRespPort : public MasterPort
{
private:
/** The port which we mirror internally. */
SlavePort& slavePort;
public:
/**
* Create a snoop response port that mirrors a given slave port.
*/
SnoopRespPort(SlavePort& slave_port, CoherentXBar& _xbar) :
MasterPort(slave_port.name() + ".snoopRespPort", &_xbar),
slavePort(slave_port) { }
/**
* Override the sending of retries and pass them on through
* the mirrored slave port.
*/
void sendRetry() {
slavePort.sendRetry();
}
/**
* Provided as necessary.
*/
void recvRetry() { panic("SnoopRespPort should never see retry\n"); }
/**
* Provided as necessary.
*/
bool recvTimingResp(PacketPtr pkt)
{
panic("SnoopRespPort should never see timing response\n");
return false;
}
};
std::vector<SnoopRespPort*> snoopRespPorts;
std::vector<SlavePort*> snoopPorts;
/**
* Store the outstanding requests so we can determine which ones
* we generated and which ones were merely forwarded. This is used
* in the coherent crossbar when coherency responses come back.
*/
m5::hash_set<RequestPtr> outstandingReq;
/**
* Keep a pointer to the system to be allow to querying memory system
* properties.
*/
System *system;
/** A snoop filter that tracks cache line residency and can restrict the
* broadcast needed for probes. NULL denotes an absent filter. */
SnoopFilter *snoopFilter;
/** Function called by the port when the crossbar is recieving a Timing
request packet.*/
bool recvTimingReq(PacketPtr pkt, PortID slave_port_id);
/** Function called by the port when the crossbar is recieving a Timing
response packet.*/
bool recvTimingResp(PacketPtr pkt, PortID master_port_id);
/** Function called by the port when the crossbar is recieving a timing
snoop request.*/
void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id);
/** Function called by the port when the crossbar is recieving a timing
snoop response.*/
bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id);
/** Timing function called by port when it is once again able to process
* requests. */
void recvRetry(PortID master_port_id);
/**
* Forward a timing packet to our snoopers, potentially excluding
* one of the connected coherent masters to avoid sending a packet
* back to where it came from.
*
* @param pkt Packet to forward
* @param exclude_slave_port_id Id of slave port to exclude
*/
void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id) {
forwardTiming(pkt, exclude_slave_port_id, snoopPorts);
}
/**
* Forward a timing packet to a selected list of snoopers, potentially
* excluding one of the connected coherent masters to avoid sending a packet
* back to where it came from.
*
* @param pkt Packet to forward
* @param exclude_slave_port_id Id of slave port to exclude
* @param dests Vector of destination ports for the forwarded pkt
*/
void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id,
const std::vector<SlavePort*>& dests);
/** Function called by the port when the crossbar is recieving a Atomic
transaction.*/
Tick recvAtomic(PacketPtr pkt, PortID slave_port_id);
/** Function called by the port when the crossbar is recieving an
atomic snoop transaction.*/
Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id);
/**
* Forward an atomic packet to our snoopers, potentially excluding
* one of the connected coherent masters to avoid sending a packet
* back to where it came from.
*
* @param pkt Packet to forward
* @param exclude_slave_port_id Id of slave port to exclude
*
* @return a pair containing the snoop response and snoop latency
*/
std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
PortID exclude_slave_port_id)
{
return forwardAtomic(pkt, exclude_slave_port_id, InvalidPortID, snoopPorts);
}
/**
* Forward an atomic packet to a selected list of snoopers, potentially
* excluding one of the connected coherent masters to avoid sending a packet
* back to where it came from.
*
* @param pkt Packet to forward
* @param exclude_slave_port_id Id of slave port to exclude
* @param source_master_port_id Id of the master port for snoops from below
* @param dests Vector of destination ports for the forwarded pkt
*
* @return a pair containing the snoop response and snoop latency
*/
std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
PortID exclude_slave_port_id,
PortID source_master_port_id,
const std::vector<SlavePort*>& dests);
/** Function called by the port when the crossbar is recieving a Functional
transaction.*/
void recvFunctional(PacketPtr pkt, PortID slave_port_id);
/** Function called by the port when the crossbar is recieving a functional
snoop transaction.*/
void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id);
/**
* Forward a functional packet to our snoopers, potentially
* excluding one of the connected coherent masters to avoid
* sending a packet back to where it came from.
*
* @param pkt Packet to forward
* @param exclude_slave_port_id Id of slave port to exclude
*/
void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id);
Stats::Scalar snoops;
Stats::Distribution snoopFanout;
public:
virtual void init();
CoherentXBar(const CoherentXBarParams *p);
virtual ~CoherentXBar();
unsigned int drain(DrainManager *dm);
virtual void regStats();
};
#endif //__MEM_COHERENT_XBAR_HH__