/*
* Copyright (c) 2011-2015, 2018 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 an abstract crossbar base class.
*/
#ifndef __MEM_XBAR_HH__
#define __MEM_XBAR_HH__
#include <deque>
#include <unordered_map>
#include "base/addr_range_map.hh"
#include "base/types.hh"
#include "mem/mem_object.hh"
#include "mem/qport.hh"
#include "params/BaseXBar.hh"
#include "sim/stats.hh"
/**
* The base crossbar contains the common elements of the non-coherent
* and coherent crossbar. It is an abstract class that does not have
* any of the functionality relating to the actual reception and
* transmission of packets, as this is left for the subclasses.
*
* The BaseXBar is responsible for the basic flow control (busy or
* not), the administration of retries, and the address decoding.
*/
class BaseXBar : public MemObject
{
protected:
/**
* A layer is an internal crossbar arbitration point with its own
* flow control. Each layer is a converging multiplexer tree. By
* instantiating one layer per destination port (and per packet
* type, i.e. request, response, snoop request and snoop
* response), we model full crossbar structures like AXI, ACE,
* PCIe, etc.
*
* The template parameter, PortClass, indicates the destination
* port type for the layer. The retry list holds either master
* ports or slave ports, depending on the direction of the
* layer. Thus, a request layer has a retry list containing slave
* ports, whereas a response layer holds master ports.
*/
template <typename SrcType, typename DstType>
class Layer : public Drainable
{
public:
/**
* Create a layer and give it a name. The layer uses
* the crossbar an event manager.
*
* @param _port destination port the layer converges at
* @param _xbar the crossbar this layer belongs to
* @param _name the layer's name
*/
Layer(DstType& _port, BaseXBar& _xbar, const std::string& _name);
/**
* Drain according to the normal semantics, so that the crossbar
* can tell the layer to drain, and pass an event to signal
* back when drained.
*
* @param de drain event to call once drained
*
* @return 1 if busy or waiting to retry, or 0 if idle
*/
DrainState drain() override;
const std::string name() const { return xbar.name() + _name; }
/**
* Determine if the layer accepts a packet from a specific
* port. If not, the port in question is also added to the
* retry list. In either case the state of the layer is
* updated accordingly.
*
* @param port Source port presenting the packet
*
* @return True if the layer accepts the packet
*/
bool tryTiming(SrcType* src_port);
/**
* Deal with a destination port accepting a packet by potentially
* removing the source port from the retry list (if retrying) and
* occupying the layer accordingly.
*
* @param busy_time Time to spend as a result of a successful send
*/
void succeededTiming(Tick busy_time);
/**
* Deal with a destination port not accepting a packet by
* potentially adding the source port to the retry list (if
* not already at the front) and occupying the layer
* accordingly.
*
* @param src_port Source port
* @param busy_time Time to spend as a result of a failed send
*/
void failedTiming(SrcType* src_port, Tick busy_time);
void occupyLayer(Tick until);
/**
* Send a retry to the port at the head of waitingForLayer. The
* caller must ensure that the list is not empty.
*/
void retryWaiting();
/**
* Handle a retry from a neighbouring module. This wraps
* retryWaiting by verifying that there are ports waiting
* before calling retryWaiting.
*/
void recvRetry();
void regStats();
protected:
/**
* Sending the actual retry, in a manner specific to the
* individual layers. Note that for a MasterPort, there is
* both a RequestLayer and a SnoopResponseLayer using the same
* port, but using different functions for the flow control.
*/
virtual void sendRetry(SrcType* retry_port) = 0;
private:
/** The destination port this layer converges at. */
DstType& port;
/** The crossbar this layer is a part of. */
BaseXBar& xbar;
std::string _name;
/**
* We declare an enum to track the state of the layer. The
* starting point is an idle state where the layer is waiting
* for a packet to arrive. Upon arrival, the layer
* transitions to the busy state, where it remains either
* until the packet transfer is done, or the header time is
* spent. Once the layer leaves the busy state, it can
* either go back to idle, if no packets have arrived while it
* was busy, or the layer goes on to retry the first port
* in waitingForLayer. A similar transition takes place from
* idle to retry if the layer receives a retry from one of
* its connected ports. The retry state lasts until the port
* in questions calls sendTiming and returns control to the
* layer, or goes to a busy state if the port does not
* immediately react to the retry by calling sendTiming.
*/
enum State { IDLE, BUSY, RETRY };
State state;
/**
* A deque of ports that retry should be called on because
* the original send was delayed due to a busy layer.
*/
std::deque<SrcType*> waitingForLayer;
/**
* Track who is waiting for the retry when receiving it from a
* peer. If no port is waiting NULL is stored.
*/
SrcType* waitingForPeer;
/**
* Release the layer after being occupied and return to an
* idle state where we proceed to send a retry to any
* potential waiting port, or drain if asked to do so.
*/
void releaseLayer();
EventFunctionWrapper releaseEvent;
/**
* Stats for occupancy and utilization. These stats capture
* the time the layer spends in the busy state and are thus only
* relevant when the memory system is in timing mode.
*/
Stats::Scalar occupancy;
Stats::Formula utilization;
};
class ReqLayer : public Layer<SlavePort, MasterPort>
{
public:
/**
* Create a request layer and give it a name.
*
* @param _port destination port the layer converges at
* @param _xbar the crossbar this layer belongs to
* @param _name the layer's name
*/
ReqLayer(MasterPort& _port, BaseXBar& _xbar, const std::string& _name) :
Layer(_port, _xbar, _name)
{}
protected:
void
sendRetry(SlavePort* retry_port) override
{
retry_port->sendRetryReq();
}
};
class RespLayer : public Layer<MasterPort, SlavePort>
{
public:
/**
* Create a response layer and give it a name.
*
* @param _port destination port the layer converges at
* @param _xbar the crossbar this layer belongs to
* @param _name the layer's name
*/
RespLayer(SlavePort& _port, BaseXBar& _xbar,
const std::string& _name) :
Layer(_port, _xbar, _name)
{}
protected:
void
sendRetry(MasterPort* retry_port) override
{
retry_port->sendRetryResp();
}
};
class SnoopRespLayer : public Layer<SlavePort, MasterPort>
{
public:
/**
* Create a snoop response layer and give it a name.
*
* @param _port destination port the layer converges at
* @param _xbar the crossbar this layer belongs to
* @param _name the layer's name
*/
SnoopRespLayer(MasterPort& _port, BaseXBar& _xbar,
const std::string& _name) :
Layer(_port, _xbar, _name)
{}
protected:
void
sendRetry(SlavePort* retry_port) override
{
retry_port->sendRetrySnoopResp();
}
};
/**
* Cycles of front-end pipeline including the delay to accept the request
* and to decode the address.
*/
const Cycles frontendLatency;
const Cycles forwardLatency;
const Cycles responseLatency;
/** the width of the xbar in bytes */
const uint32_t width;
AddrRangeMap<PortID, 3> portMap;
/**
* Remember where request packets came from so that we can route
* responses to the appropriate port. This relies on the fact that
* the underlying Request pointer inside the Packet stays
* constant.
*/
std::unordered_map<RequestPtr, PortID> routeTo;
/** all contigous ranges seen by this crossbar */
AddrRangeList xbarRanges;
AddrRange defaultRange;
/**
* Function called by the port when the crossbar is recieving a
* range change.
*
* @param master_port_id id of the port that received the change
*/
virtual void recvRangeChange(PortID master_port_id);
/**
* Find which port connected to this crossbar (if any) should be
* given a packet with this address range.
*
* @param addr_range Address range to find port for.
* @return id of port that the packet should be sent out of.
*/
PortID findPort(AddrRange addr_range);
/**
* Return the address ranges the crossbar is responsible for.
*
* @return a list of non-overlapping address ranges
*/
AddrRangeList getAddrRanges() const;
/**
* Calculate the timing parameters for the packet. Updates the
* headerDelay and payloadDelay fields of the packet
* object with the relative number of ticks required to transmit
* the header and the payload, respectively.
*
* @param pkt Packet to populate with timings
* @param header_delay Header delay to be added
*/
void calcPacketTiming(PacketPtr pkt, Tick header_delay);
/**
* Remember for each of the master ports of the crossbar if we got
* an address range from the connected slave. For convenience,
* also keep track of if we got ranges from all the slave modules
* or not.
*/
std::vector<bool> gotAddrRanges;
bool gotAllAddrRanges;
/** The master and slave ports of the crossbar */
std::vector<QueuedSlavePort*> slavePorts;
std::vector<MasterPort*> masterPorts;
/** Port that handles requests that don't match any of the interfaces.*/
PortID defaultPortID;
/** If true, use address range provided by default device. Any
address not handled by another port and not in default device's
range will cause a fatal error. If false, just send all
addresses not handled by another port to default device. */
const bool useDefaultRange;
BaseXBar(const BaseXBarParams *p);
/**
* Stats for transaction distribution and data passing through the
* crossbar. The transaction distribution is globally counting
* different types of commands. The packet count and total packet
* size are two-dimensional vectors that are indexed by the
* slave port and master port id (thus the neighbouring master and
* neighbouring slave), summing up both directions (request and
* response).
*/
Stats::Vector transDist;
Stats::Vector2d pktCount;
Stats::Vector2d pktSize;
public:
virtual ~BaseXBar();
/** A function used to return the port associated with this object. */
Port &getPort(const std::string &if_name,
PortID idx=InvalidPortID) override;
void regStats() override;
};
#endif //__MEM_XBAR_HH__