f9d403a7b9
This patch introduces the notion of a master and slave port in the C++ code, thus bringing the previous classification from the Python classes into the corresponding simulation objects and memory objects. The patch enables us to classify behaviours into the two bins and add assumptions and enfore compliance, also simplifying the two interfaces. As a starting point, isSnooping is confined to a master port, and getAddrRanges to slave ports. More of these specilisations are to come in later patches. The getPort function is not getMasterPort and getSlavePort, and returns a port reference rather than a pointer as NULL would never be a valid return value. The default implementation of these two functions is placed in MemObject, and calls fatal. The one drawback with this specific patch is that it requires some code duplication, e.g. QueuedPort becomes QueuedMasterPort and QueuedSlavePort, and BusPort becomes BusMasterPort and BusSlavePort (avoiding multiple inheritance). With the later introduction of the port interfaces, moving the functionality outside the port itself, a lot of the duplicated code will disappear again.
492 lines
15 KiB
C++
492 lines
15 KiB
C++
/*
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* Copyright (c) 2011-2012 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 bus 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/BusBridge.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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int _delay, int _nack_delay,
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int _resp_limit,
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std::vector<Range<Addr> > _ranges)
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: SlavePort(_name, _bridge), bridge(_bridge), masterPort(_masterPort),
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delay(_delay), nackDelay(_nack_delay),
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ranges(_ranges.begin(), _ranges.end()),
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outstandingResponses(0), inRetry(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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int _delay, int _req_limit)
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: MasterPort(_name, _bridge), bridge(_bridge), slavePort(_slavePort),
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delay(_delay), inRetry(false), reqQueueLimit(_req_limit),
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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, p->delay,
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p->nack_delay, p->resp_size, p->ranges),
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masterPort(p->name + "-master", this, slavePort, p->delay, p->req_size),
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ackWrites(p->write_ack), _params(p)
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{
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if (ackWrites)
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panic("No support for acknowledging writes\n");
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}
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MasterPort&
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Bridge::getMasterPort(const std::string &if_name, int 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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SlavePort&
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Bridge::getSlavePort(const std::string &if_name, int 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 bus bridge are not connected to a bus.\n");
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if (slavePort.peerBlockSize() != masterPort.peerBlockSize())
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fatal("Slave port size %d, master port size %d \n " \
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"Busses don't have the same block size... Not supported.\n",
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slavePort.peerBlockSize(), masterPort.peerBlockSize());
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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()
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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()
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{
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return requestQueue.size() == reqQueueLimit;
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}
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bool
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Bridge::BridgeMasterPort::recvTiming(PacketPtr pkt)
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{
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// should only see responses on the master side
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assert(pkt->isResponse());
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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(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
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pkt->getSrc(), pkt->getDest(), pkt->getAddr());
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DPRINTF(BusBridge, "Request queue size: %d\n", requestQueue.size());
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slavePort.queueForSendTiming(pkt);
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return true;
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}
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bool
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Bridge::BridgeSlavePort::recvTiming(PacketPtr pkt)
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{
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// should only see requests on the slave side
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assert(pkt->isRequest());
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DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
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pkt->getSrc(), pkt->getDest(), pkt->getAddr());
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DPRINTF(BusBridge, "Response queue size: %d outresp: %d\n",
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responseQueue.size(), outstandingResponses);
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if (masterPort.reqQueueFull()) {
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DPRINTF(BusBridge, "Request queue full, nacking\n");
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nackRequest(pkt);
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return true;
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}
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if (pkt->needsResponse()) {
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if (respQueueFull()) {
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DPRINTF(BusBridge,
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"Response queue full, no space for response, nacking\n");
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DPRINTF(BusBridge,
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"queue size: %d outstanding resp: %d\n",
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responseQueue.size(), outstandingResponses);
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nackRequest(pkt);
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return true;
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} else {
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DPRINTF(BusBridge, "Request Needs response, reserving space\n");
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assert(outstandingResponses != respQueueLimit);
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++outstandingResponses;
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}
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}
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masterPort.queueForSendTiming(pkt);
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return true;
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}
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void
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Bridge::BridgeSlavePort::nackRequest(PacketPtr pkt)
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{
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// Nack the packet
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pkt->makeTimingResponse();
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pkt->setNacked();
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// The Nack packets are stored in the response queue just like any
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// other response, but they do not occupy any space as this is
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// tracked by the outstandingResponses, this guarantees space for
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// the Nack packets, but implicitly means we have an (unrealistic)
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// unbounded Nack queue.
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// put it on the list to send
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Tick readyTime = curTick() + nackDelay;
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PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true);
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// nothing on the list, add it and we're done
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if (responseQueue.empty()) {
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assert(!sendEvent.scheduled());
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bridge->schedule(sendEvent, readyTime);
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responseQueue.push_back(buf);
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return;
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}
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assert(sendEvent.scheduled() || inRetry);
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// does it go at the end?
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if (readyTime >= responseQueue.back()->ready) {
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responseQueue.push_back(buf);
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return;
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}
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// ok, somewhere in the middle, fun
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std::list<PacketBuffer*>::iterator i = responseQueue.begin();
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std::list<PacketBuffer*>::iterator end = responseQueue.end();
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std::list<PacketBuffer*>::iterator begin = responseQueue.begin();
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bool done = false;
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while (i != end && !done) {
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if (readyTime < (*i)->ready) {
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if (i == begin)
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bridge->reschedule(sendEvent, readyTime);
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responseQueue.insert(i,buf);
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done = true;
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}
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i++;
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}
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assert(done);
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}
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void
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Bridge::BridgeMasterPort::queueForSendTiming(PacketPtr pkt)
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{
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Tick readyTime = curTick() + delay;
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PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
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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 (requestQueue.empty()) {
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bridge->schedule(sendEvent, readyTime);
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}
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assert(requestQueue.size() != reqQueueLimit);
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requestQueue.push_back(buf);
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}
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void
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Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt)
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{
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// This is a response for a request we forwarded earlier. The
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// corresponding PacketBuffer should be stored in the packet's
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// senderState field.
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PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
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assert(buf != NULL);
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// set up new packet dest & senderState based on values saved
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// from original request
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buf->fixResponse(pkt);
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DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest());
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delete buf;
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Tick readyTime = curTick() + delay;
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buf = new PacketBuffer(pkt, readyTime);
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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 (responseQueue.empty()) {
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bridge->schedule(sendEvent, readyTime);
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}
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responseQueue.push_back(buf);
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}
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void
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Bridge::BridgeMasterPort::trySend()
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{
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assert(!requestQueue.empty());
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PacketBuffer *buf = requestQueue.front();
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assert(buf->ready <= curTick());
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PacketPtr pkt = buf->pkt;
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DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
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buf->origSrc, pkt->getDest(), pkt->getAddr());
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// If the send was successful, make sure sender state was set to NULL
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// otherwise we could get a NACK back of a packet that didn't expect a
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// response and we would try to use freed memory.
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Packet::SenderState *old_sender_state = pkt->senderState;
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if (!buf->expectResponse)
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pkt->senderState = NULL;
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if (sendTiming(pkt)) {
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// send successful
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requestQueue.pop_front();
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// we no longer own packet, so it's not safe to look at it
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buf->pkt = NULL;
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if (!buf->expectResponse) {
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// no response expected... deallocate packet buffer now.
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DPRINTF(BusBridge, " successful: no response expected\n");
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delete buf;
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}
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// If there are more packets to send, schedule event to try again.
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if (!requestQueue.empty()) {
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buf = requestQueue.front();
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DPRINTF(BusBridge, "Scheduling next send\n");
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bridge->schedule(sendEvent, std::max(buf->ready, curTick() + 1));
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}
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} else {
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DPRINTF(BusBridge, " unsuccessful\n");
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pkt->senderState = old_sender_state;
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inRetry = true;
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}
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DPRINTF(BusBridge, "trySend: request queue size: %d\n",
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requestQueue.size());
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}
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void
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Bridge::BridgeSlavePort::trySend()
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{
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assert(!responseQueue.empty());
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PacketBuffer *buf = responseQueue.front();
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assert(buf->ready <= curTick());
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PacketPtr pkt = buf->pkt;
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DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
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buf->origSrc, pkt->getDest(), pkt->getAddr());
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bool was_nacked_here = buf->nackedHere;
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// no need to worry about the sender state since we are not
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// modifying it
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if (sendTiming(pkt)) {
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DPRINTF(BusBridge, " successful\n");
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// send successful
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responseQueue.pop_front();
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// this is a response... deallocate packet buffer now.
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delete buf;
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if (!was_nacked_here) {
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assert(outstandingResponses != 0);
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--outstandingResponses;
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}
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// If there are more packets to send, schedule event to try again.
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if (!responseQueue.empty()) {
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buf = responseQueue.front();
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DPRINTF(BusBridge, "Scheduling next send\n");
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bridge->schedule(sendEvent, std::max(buf->ready, curTick() + 1));
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}
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} else {
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DPRINTF(BusBridge, " unsuccessful\n");
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inRetry = true;
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}
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DPRINTF(BusBridge, "trySend: queue size: %d outstanding resp: %d\n",
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responseQueue.size(), outstandingResponses);
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}
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void
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Bridge::BridgeMasterPort::recvRetry()
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{
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inRetry = false;
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Tick nextReady = requestQueue.front()->ready;
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if (nextReady <= curTick())
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trySend();
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else
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bridge->schedule(sendEvent, nextReady);
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}
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void
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Bridge::BridgeSlavePort::recvRetry()
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{
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inRetry = false;
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Tick nextReady = responseQueue.front()->ready;
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if (nextReady <= curTick())
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trySend();
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else
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bridge->schedule(sendEvent, nextReady);
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}
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Tick
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Bridge::BridgeMasterPort::recvAtomic(PacketPtr pkt)
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{
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// master port should never receive any atomic access (panic only
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// works once the other side, i.e. the busses, respects this)
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//
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//panic("Master port on %s got a recvAtomic\n", bridge->name());
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return 0;
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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 + masterPort.sendAtomic(pkt);
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}
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void
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Bridge::BridgeMasterPort::recvFunctional(PacketPtr pkt)
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{
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// master port should never receive any functional access (panic
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// only works once the other side, i.e. the busses, respect this)
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// panic("Master port on %s got a recvFunctional\n", bridge->name());
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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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std::list<PacketBuffer*>::iterator i;
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pkt->pushLabel(name());
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// check the response queue
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for (i = responseQueue.begin(); i != responseQueue.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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std::list<PacketBuffer*>::iterator i = requestQueue.begin();
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while(i != requestQueue.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()
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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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