/*
- * Copyright (c) 2011-2012 ARM Limited
+ * Copyright (c) 2011-2013 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
/**
* @file
- * Declaration of a memory-mapped bus bridge that connects a master
+ * Declaration of a memory-mapped bridge that connects a master
* and a slave through a request and response queue.
*/
#ifndef __MEM_BRIDGE_HH__
#define __MEM_BRIDGE_HH__
-#include <list>
-#include <queue>
-#include <string>
+#include <deque>
#include "base/types.hh"
-#include "mem/mem_object.hh"
-#include "mem/packet.hh"
#include "mem/port.hh"
#include "params/Bridge.hh"
-#include "sim/eventq.hh"
+#include "sim/clocked_object.hh"
/**
- * A bridge is used to interface two different busses (or in general a
+ * A bridge is used to interface two different crossbars (or in general a
* memory-mapped master and slave), with buffering for requests and
* responses. The bridge has a fixed delay for packets passing through
* it and responds to a fixed set of address ranges.
* The bridge comprises a slave port and a master port, that buffer
* outgoing responses and requests respectively. Buffer space is
* reserved when a request arrives, also reserving response space
- * before forwarding the request. An incoming request is always
- * accepted (recvTiming returns true), but is potentially NACKed if
- * there is no request space or response space.
+ * before forwarding the request. If there is no space present, then
+ * the bridge will delay accepting the packet until space becomes
+ * available.
*/
-class Bridge : public MemObject
+class Bridge : public ClockedObject
{
protected:
/**
- * A bridge request state stores packets along with their sender
- * state and original source. It has enough information to also
- * restore the response once it comes back to the bridge.
+ * A deferred packet stores a packet along with its scheduled
+ * transmission time
*/
- class RequestState : public Packet::SenderState
+ class DeferredPacket
{
public:
- Packet::SenderState *origSenderState;
- PortID origSrc;
+ const Tick tick;
+ const PacketPtr pkt;
- RequestState(PacketPtr _pkt)
- : origSenderState(_pkt->senderState),
- origSrc(_pkt->getSrc())
- { }
-
- void fixResponse(PacketPtr pkt)
- {
- assert(pkt->senderState == this);
- pkt->setDest(origSrc);
- pkt->senderState = origSenderState;
- }
- };
-
- /**
- * A deferred request stores a packet along with its scheduled
- * transmission time, and whether we can expect to see a response
- * or not.
- */
- class DeferredRequest
- {
-
- public:
-
- Tick ready;
- PacketPtr pkt;
- bool expectResponse;
-
- DeferredRequest(PacketPtr _pkt, Tick t)
- : ready(t), pkt(_pkt), expectResponse(_pkt->needsResponse())
- { }
- };
-
- /**
- * A deferred response stores a packet along with its scheduled
- * transmission time. It also contains information of whether the
- * bridge NACKed the packet to be able to correctly maintain
- * counters of outstanding responses.
- */
- class DeferredResponse {
-
- public:
-
- Tick ready;
- PacketPtr pkt;
- bool nackedHere;
-
- DeferredResponse(PacketPtr _pkt, Tick t, bool nack = false)
- : ready(t), pkt(_pkt), nackedHere(nack)
+ DeferredPacket(PacketPtr _pkt, Tick _tick) : tick(_tick), pkt(_pkt)
{ }
};
private:
- /** A pointer to the bridge to which this port belongs. */
- Bridge *bridge;
+ /** The bridge to which this port belongs. */
+ Bridge& bridge;
/**
- * Master port on the other side of the bridge
- * (connected to the other bus).
+ * Master port on the other side of the bridge.
*/
BridgeMasterPort& masterPort;
/** Minimum request delay though this bridge. */
- Tick delay;
-
- /** Min delay to respond with a nack. */
- Tick nackDelay;
+ const Cycles delay;
/** Address ranges to pass through the bridge */
- AddrRangeList ranges;
+ const AddrRangeList ranges;
/**
* Response packet queue. Response packets are held in this
* queue for a specified delay to model the processing delay
- * of the bridge.
+ * of the bridge. We use a deque as we need to iterate over
+ * the items for functional accesses.
*/
- std::list<DeferredResponse> responseQueue;
+ std::deque<DeferredPacket> transmitList;
/** Counter to track the outstanding responses. */
unsigned int outstandingResponses;
- /** If we're waiting for a retry to happen. */
- bool inRetry;
+ /** If we should send a retry when space becomes available. */
+ bool retryReq;
/** Max queue size for reserved responses. */
unsigned int respQueueLimit;
/**
- * Is this side blocked from accepting new response packets.
- *
- * @return true if the reserved space has reached the set limit
+ * Upstream caches need this packet until true is returned, so
+ * hold it for deletion until a subsequent call
*/
- bool respQueueFull();
+ std::unique_ptr<Packet> pendingDelete;
/**
- * Turn the request packet into a NACK response and put it in
- * the response queue and schedule its transmission.
+ * Is this side blocked from accepting new response packets.
*
- * @param pkt the request packet to NACK
+ * @return true if the reserved space has reached the set limit
*/
- void nackRequest(PacketPtr pkt);
+ bool respQueueFull() const;
/**
* Handle send event, scheduled when the packet at the head of
* the response queue is ready to transmit (for timing
* accesses only).
*/
- void trySend();
+ void trySendTiming();
/** Send event for the response queue. */
- EventWrapper<BridgeSlavePort, &BridgeSlavePort::trySend> sendEvent;
+ EventFunctionWrapper sendEvent;
public:
* @param _name the port name including the owner
* @param _bridge the structural owner
* @param _masterPort the master port on the other side of the bridge
- * @param _delay the delay from seeing a response to sending it
- * @param _nack_delay the delay from a NACK to sending the response
+ * @param _delay the delay in cycles from receiving to sending
* @param _resp_limit the size of the response queue
* @param _ranges a number of address ranges to forward
*/
- BridgeSlavePort(const std::string &_name, Bridge *_bridge,
- BridgeMasterPort& _masterPort, int _delay,
- int _nack_delay, int _resp_limit,
- std::vector<Range<Addr> > _ranges);
+ BridgeSlavePort(const std::string& _name, Bridge& _bridge,
+ BridgeMasterPort& _masterPort, Cycles _delay,
+ int _resp_limit, std::vector<AddrRange> _ranges);
/**
* Queue a response packet to be sent out later and also schedule
* a send if necessary.
*
* @param pkt a response to send out after a delay
+ * @param when tick when response packet should be sent
+ */
+ void schedTimingResp(PacketPtr pkt, Tick when);
+
+ /**
+ * Retry any stalled request that we have failed to accept at
+ * an earlier point in time. This call will do nothing if no
+ * request is waiting.
*/
- void queueForSendTiming(PacketPtr pkt);
+ void retryStalledReq();
protected:
/** When receiving a timing request from the peer port,
pass it to the bridge. */
- virtual bool recvTimingReq(PacketPtr pkt);
+ bool recvTimingReq(PacketPtr pkt);
/** When receiving a retry request from the peer port,
pass it to the bridge. */
- virtual void recvRetry();
+ void recvRespRetry();
/** When receiving a Atomic requestfrom the peer port,
pass it to the bridge. */
- virtual Tick recvAtomic(PacketPtr pkt);
+ Tick recvAtomic(PacketPtr pkt);
/** When receiving a Functional request from the peer port,
pass it to the bridge. */
- virtual void recvFunctional(PacketPtr pkt);
+ void recvFunctional(PacketPtr pkt);
/** When receiving a address range request the peer port,
pass it to the bridge. */
- virtual AddrRangeList getAddrRanges() const;
+ AddrRangeList getAddrRanges() const;
};
private:
- /** A pointer to the bridge to which this port belongs. */
- Bridge* bridge;
+ /** The bridge to which this port belongs. */
+ Bridge& bridge;
/**
- * Pointer to the slave port on the other side of the bridge
- * (connected to the other bus).
+ * The slave port on the other side of the bridge.
*/
BridgeSlavePort& slavePort;
/** Minimum delay though this bridge. */
- Tick delay;
+ const Cycles delay;
/**
* Request packet queue. Request packets are held in this
* queue for a specified delay to model the processing delay
- * of the bridge.
+ * of the bridge. We use a deque as we need to iterate over
+ * the items for functional accesses.
*/
- std::list<DeferredRequest> requestQueue;
-
- /** If we're waiting for a retry to happen. */
- bool inRetry;
+ std::deque<DeferredPacket> transmitList;
/** Max queue size for request packets */
- unsigned int reqQueueLimit;
+ const unsigned int reqQueueLimit;
/**
* Handle send event, scheduled when the packet at the head of
* the outbound queue is ready to transmit (for timing
* accesses only).
*/
- void trySend();
+ void trySendTiming();
/** Send event for the request queue. */
- EventWrapper<BridgeMasterPort, &BridgeMasterPort::trySend> sendEvent;
+ EventFunctionWrapper sendEvent;
public:
* @param _name the port name including the owner
* @param _bridge the structural owner
* @param _slavePort the slave port on the other side of the bridge
- * @param _delay the delay from seeing a request to sending it
+ * @param _delay the delay in cycles from receiving to sending
* @param _req_limit the size of the request queue
*/
- BridgeMasterPort(const std::string &_name, Bridge *_bridge,
- BridgeSlavePort& _slavePort, int _delay,
+ BridgeMasterPort(const std::string& _name, Bridge& _bridge,
+ BridgeSlavePort& _slavePort, Cycles _delay,
int _req_limit);
/**
*
* @return true if the occupied space has reached the set limit
*/
- bool reqQueueFull();
+ bool reqQueueFull() const;
/**
* Queue a request packet to be sent out later and also schedule
* a send if necessary.
*
* @param pkt a request to send out after a delay
+ * @param when tick when response packet should be sent
*/
- void queueForSendTiming(PacketPtr pkt);
+ void schedTimingReq(PacketPtr pkt, Tick when);
/**
* Check a functional request against the packets in our
*
* @return true if we find a match
*/
- bool checkFunctional(PacketPtr pkt);
+ bool trySatisfyFunctional(PacketPtr pkt);
protected:
/** When receiving a timing request from the peer port,
pass it to the bridge. */
- virtual bool recvTimingResp(PacketPtr pkt);
+ bool recvTimingResp(PacketPtr pkt);
/** When receiving a retry request from the peer port,
pass it to the bridge. */
- virtual void recvRetry();
+ void recvReqRetry();
};
/** Slave port of the bridge. */
/** Master port of the bridge. */
BridgeMasterPort masterPort;
- /** If this bridge should acknowledge writes. */
- bool ackWrites;
-
public:
- typedef BridgeParams Params;
- protected:
- Params *_params;
-
- public:
- const Params *params() const { return _params; }
+ Port &getPort(const std::string &if_name,
+ PortID idx=InvalidPortID) override;
- virtual MasterPort& getMasterPort(const std::string& if_name,
- int idx = -1);
- virtual SlavePort& getSlavePort(const std::string& if_name, int idx = -1);
+ void init() override;
- virtual void init();
+ typedef BridgeParams Params;
Bridge(Params *p);
};
-#endif //__MEM_BUS_HH__
+#endif //__MEM_BRIDGE_HH__
projects / gem5.git / blobdiff