| /* |
| * Copyright (c) 2011-2015, 2018-2020 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. |
| */ |
| |
| /** |
| * @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/qport.hh" |
| #include "params/BaseXBar.hh" |
| #include "sim/clocked_object.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 ClockedObject |
| { |
| |
| 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 memory-side ports |
| * or CPU-side ports, depending on the direction of the |
| * layer. Thus, a request layer has a retry list containing |
| * CPU-side ports, whereas a response layer holds memory-side ports. |
| */ |
| template <typename SrcType, typename DstType> |
| class Layer : public Drainable, public Stats::Group |
| { |
| |
| 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 _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(); |
| |
| protected: |
| |
| /** |
| * Sending the actual retry, in a manner specific to the |
| * individual layers. Note that for a RequestPort, 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<ResponsePort, RequestPort> |
| { |
| 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(RequestPort& _port, BaseXBar& _xbar, |
| const std::string& _name) : |
| Layer(_port, _xbar, _name) |
| {} |
| |
| protected: |
| void |
| sendRetry(ResponsePort* retry_port) override |
| { |
| retry_port->sendRetryReq(); |
| } |
| }; |
| |
| class RespLayer : public Layer<RequestPort, ResponsePort> |
| { |
| 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(ResponsePort& _port, BaseXBar& _xbar, |
| const std::string& _name) : |
| Layer(_port, _xbar, _name) |
| {} |
| |
| protected: |
| void |
| sendRetry(RequestPort* retry_port) override |
| { |
| retry_port->sendRetryResp(); |
| } |
| }; |
| |
| class SnoopRespLayer : public Layer<ResponsePort, RequestPort> |
| { |
| 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(RequestPort& _port, BaseXBar& _xbar, |
| const std::string& _name) : |
| Layer(_port, _xbar, _name) |
| {} |
| |
| protected: |
| |
| void |
| sendRetry(ResponsePort* 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; |
| /** Cycles the layer is occupied processing the packet header */ |
| const Cycles headerLatency; |
| /** 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 mem_side_port_id id of the port that received the change |
| */ |
| virtual void recvRangeChange(PortID mem_side_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 memory-side ports of the crossbar if we got |
| * an address range from the connected CPU-side ports. For convenience, |
| * also keep track of if we got ranges from all the CPU-side-port modules |
| * or not. |
| */ |
| std::vector<bool> gotAddrRanges; |
| bool gotAllAddrRanges; |
| |
| /** The memory-side ports and CPU-side ports of the crossbar */ |
| std::vector<QueuedResponsePort*> cpuSidePorts; |
| std::vector<RequestPort*> memSidePorts; |
| |
| /** 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 |
| * CPU-side port and memory-side port id (thus the neighbouring memory-side |
| * ports and neighbouring CPU-side ports), 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__ |
