389 lines
12 KiB
C++
389 lines
12 KiB
C++
/*
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* Copyright (c) 2011-2013 ARM Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Copyright (c) 2006 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Ali Saidi
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* Steve Reinhardt
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* Andreas Hansson
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*/
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/**
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* @file
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* Implementation of a memory-mapped bridge that connects a master
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* and a slave through a request and response queue.
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*/
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#include "base/trace.hh"
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#include "debug/Bridge.hh"
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#include "mem/bridge.hh"
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#include "params/Bridge.hh"
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Bridge::BridgeSlavePort::BridgeSlavePort(const std::string& _name,
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Bridge& _bridge,
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BridgeMasterPort& _masterPort,
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Cycles _delay, int _resp_limit,
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std::vector<AddrRange> _ranges)
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: SlavePort(_name, &_bridge), bridge(_bridge), masterPort(_masterPort),
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delay(_delay), ranges(_ranges.begin(), _ranges.end()),
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outstandingResponses(0), retryReq(false),
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respQueueLimit(_resp_limit), sendEvent(*this)
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{
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}
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Bridge::BridgeMasterPort::BridgeMasterPort(const std::string& _name,
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Bridge& _bridge,
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BridgeSlavePort& _slavePort,
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Cycles _delay, int _req_limit)
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: MasterPort(_name, &_bridge), bridge(_bridge), slavePort(_slavePort),
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delay(_delay), reqQueueLimit(_req_limit), sendEvent(*this)
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{
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}
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Bridge::Bridge(Params *p)
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: MemObject(p),
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slavePort(p->name + ".slave", *this, masterPort,
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ticksToCycles(p->delay), p->resp_size, p->ranges),
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masterPort(p->name + ".master", *this, slavePort,
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ticksToCycles(p->delay), p->req_size)
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{
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}
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BaseMasterPort&
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Bridge::getMasterPort(const std::string &if_name, PortID idx)
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{
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if (if_name == "master")
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return masterPort;
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else
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// pass it along to our super class
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return MemObject::getMasterPort(if_name, idx);
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}
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BaseSlavePort&
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Bridge::getSlavePort(const std::string &if_name, PortID idx)
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{
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if (if_name == "slave")
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return slavePort;
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else
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// pass it along to our super class
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return MemObject::getSlavePort(if_name, idx);
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}
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void
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Bridge::init()
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{
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// make sure both sides are connected and have the same block size
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if (!slavePort.isConnected() || !masterPort.isConnected())
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fatal("Both ports of a bridge must be connected.\n");
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// notify the master side of our address ranges
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slavePort.sendRangeChange();
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}
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bool
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Bridge::BridgeSlavePort::respQueueFull() const
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{
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return outstandingResponses == respQueueLimit;
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}
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bool
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Bridge::BridgeMasterPort::reqQueueFull() const
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{
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return transmitList.size() == reqQueueLimit;
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}
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bool
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Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt)
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{
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// all checks are done when the request is accepted on the slave
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// side, so we are guaranteed to have space for the response
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DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n",
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pkt->cmdString(), pkt->getAddr());
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DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size());
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// @todo: We need to pay for this and not just zero it out
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pkt->headerDelay = pkt->payloadDelay = 0;
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slavePort.schedTimingResp(pkt, bridge.clockEdge(delay));
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return true;
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}
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bool
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Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt)
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{
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DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n",
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pkt->cmdString(), pkt->getAddr());
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// we should not see a timing request if we are already in a retry
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assert(!retryReq);
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DPRINTF(Bridge, "Response queue size: %d outresp: %d\n",
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transmitList.size(), outstandingResponses);
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// if the request queue is full then there is no hope
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if (masterPort.reqQueueFull()) {
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DPRINTF(Bridge, "Request queue full\n");
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retryReq = true;
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} else {
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// look at the response queue if we expect to see a response
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bool expects_response = pkt->needsResponse() &&
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!pkt->memInhibitAsserted();
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if (expects_response) {
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if (respQueueFull()) {
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DPRINTF(Bridge, "Response queue full\n");
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retryReq = true;
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} else {
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// ok to send the request with space for the response
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DPRINTF(Bridge, "Reserving space for response\n");
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assert(outstandingResponses != respQueueLimit);
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++outstandingResponses;
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// no need to set retryReq to false as this is already the
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// case
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}
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}
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if (!retryReq) {
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// @todo: We need to pay for this and not just zero it out
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pkt->headerDelay = pkt->payloadDelay = 0;
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masterPort.schedTimingReq(pkt, bridge.clockEdge(delay));
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}
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}
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// remember that we are now stalling a packet and that we have to
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// tell the sending master to retry once space becomes available,
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// we make no distinction whether the stalling is due to the
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// request queue or response queue being full
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return !retryReq;
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}
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void
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Bridge::BridgeSlavePort::retryStalledReq()
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{
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if (retryReq) {
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DPRINTF(Bridge, "Request waiting for retry, now retrying\n");
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retryReq = false;
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sendRetryReq();
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}
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}
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void
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Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when)
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{
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// If we're about to put this packet at the head of the queue, we
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// need to schedule an event to do the transmit. Otherwise there
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// should already be an event scheduled for sending the head
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// packet.
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if (transmitList.empty()) {
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bridge.schedule(sendEvent, when);
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}
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assert(transmitList.size() != reqQueueLimit);
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transmitList.emplace_back(pkt, when);
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}
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void
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Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when)
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{
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// If we're about to put this packet at the head of the queue, we
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// need to schedule an event to do the transmit. Otherwise there
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// should already be an event scheduled for sending the head
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// packet.
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if (transmitList.empty()) {
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bridge.schedule(sendEvent, when);
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}
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transmitList.emplace_back(pkt, when);
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}
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void
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Bridge::BridgeMasterPort::trySendTiming()
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{
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assert(!transmitList.empty());
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DeferredPacket req = transmitList.front();
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assert(req.tick <= curTick());
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PacketPtr pkt = req.pkt;
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DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n",
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pkt->getAddr(), transmitList.size());
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if (sendTimingReq(pkt)) {
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// send successful
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transmitList.pop_front();
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DPRINTF(Bridge, "trySend request successful\n");
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// If there are more packets to send, schedule event to try again.
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if (!transmitList.empty()) {
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DeferredPacket next_req = transmitList.front();
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DPRINTF(Bridge, "Scheduling next send\n");
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bridge.schedule(sendEvent, std::max(next_req.tick,
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bridge.clockEdge()));
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}
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// if we have stalled a request due to a full request queue,
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// then send a retry at this point, also note that if the
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// request we stalled was waiting for the response queue
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// rather than the request queue we might stall it again
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slavePort.retryStalledReq();
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}
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// if the send failed, then we try again once we receive a retry,
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// and therefore there is no need to take any action
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}
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void
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Bridge::BridgeSlavePort::trySendTiming()
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{
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assert(!transmitList.empty());
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DeferredPacket resp = transmitList.front();
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assert(resp.tick <= curTick());
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PacketPtr pkt = resp.pkt;
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DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n",
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pkt->getAddr(), outstandingResponses);
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if (sendTimingResp(pkt)) {
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// send successful
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transmitList.pop_front();
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DPRINTF(Bridge, "trySend response successful\n");
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assert(outstandingResponses != 0);
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--outstandingResponses;
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// If there are more packets to send, schedule event to try again.
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if (!transmitList.empty()) {
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DeferredPacket next_resp = transmitList.front();
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DPRINTF(Bridge, "Scheduling next send\n");
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bridge.schedule(sendEvent, std::max(next_resp.tick,
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bridge.clockEdge()));
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}
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// if there is space in the request queue and we were stalling
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// a request, it will definitely be possible to accept it now
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// since there is guaranteed space in the response queue
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if (!masterPort.reqQueueFull() && retryReq) {
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DPRINTF(Bridge, "Request waiting for retry, now retrying\n");
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retryReq = false;
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sendRetryReq();
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}
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}
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// if the send failed, then we try again once we receive a retry,
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// and therefore there is no need to take any action
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}
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void
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Bridge::BridgeMasterPort::recvReqRetry()
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{
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trySendTiming();
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}
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void
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Bridge::BridgeSlavePort::recvRespRetry()
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{
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trySendTiming();
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}
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Tick
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Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt)
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{
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return delay * bridge.clockPeriod() + masterPort.sendAtomic(pkt);
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}
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void
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Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt)
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{
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pkt->pushLabel(name());
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// check the response queue
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for (auto i = transmitList.begin(); i != transmitList.end(); ++i) {
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if (pkt->checkFunctional((*i).pkt)) {
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pkt->makeResponse();
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return;
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}
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}
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// also check the master port's request queue
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if (masterPort.checkFunctional(pkt)) {
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return;
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}
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pkt->popLabel();
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// fall through if pkt still not satisfied
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masterPort.sendFunctional(pkt);
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}
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bool
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Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt)
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{
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bool found = false;
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auto i = transmitList.begin();
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while(i != transmitList.end() && !found) {
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if (pkt->checkFunctional((*i).pkt)) {
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pkt->makeResponse();
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found = true;
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}
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++i;
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}
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return found;
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}
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AddrRangeList
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Bridge::BridgeSlavePort::getAddrRanges() const
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{
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return ranges;
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}
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Bridge *
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BridgeParams::create()
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{
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return new Bridge(this);
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}
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