/* * 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 #include #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 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; /** * Get the crossbar layer's name */ 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); /** Occupy the layer until until */ 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(); /** * Register stats for the layer */ 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; /** A name for this layer. */ 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 }; /** track the state of the layer */ 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 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(); /** event used to schedule a release of the layer */ 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 { 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) { retry_port->sendRetryReq(); } }; class RespLayer : public Layer { 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) { retry_port->sendRetryResp(); } }; class SnoopRespLayer : public Layer { 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) { retry_port->sendRetrySnoopResp(); } }; /** * Cycles of front-end pipeline including the delay to accept the request * and to decode the address. */ const Cycles frontendLatency; /** Cycles of forward latency */ const Cycles forwardLatency; /** Cycles of response latency */ const Cycles responseLatency; /** the width of the xbar in bytes */ const uint32_t width; AddrRangeMap 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 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 gotAddrRanges; bool gotAllAddrRanges; /** The master and slave ports of the crossbar */ std::vector slavePorts; std::vector 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(); virtual void init(); /** A function used to return the port associated with this object. */ BaseMasterPort& getMasterPort(const std::string& if_name, PortID idx = InvalidPortID); BaseSlavePort& getSlavePort(const std::string& if_name, PortID idx = InvalidPortID); virtual void regStats(); }; #endif //__MEM_XBAR_HH__