3b367db42c
This patch splits the PacketBuffer class into a RequestState and a DeferredRequest and DeferredResponse. Only the requests need a SenderState, and the deferred requests and responses only need an associated point in time for the request and the response queue. Besides the cleaning up, the goal is to simplify the transition to a new port handshake, and with these changes, the two packet queues are starting to look very similar to the generic packet queue, but currently they do a few unique things relating to the NACK and counting of requests/responses that the packet queue cannot be conveniently used. This will be addressed in a later patch.
456 lines
14 KiB
C++
456 lines
14 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::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(BusBridge, "recvTiming: response %s addr 0x%x\n",
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pkt->cmdString(), 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::recvTimingReq(PacketPtr pkt)
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{
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DPRINTF(BusBridge, "recvTiming: request %s addr 0x%x\n",
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pkt->cmdString(), 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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DeferredResponse resp(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(resp);
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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(resp);
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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<DeferredResponse>::iterator i = responseQueue.begin();
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std::list<DeferredResponse>::iterator end = responseQueue.end();
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std::list<DeferredResponse>::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, resp);
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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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// If we expect to see a response, we need to restore the source
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// and destination field that is potentially changed by a second
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// bus
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if (!pkt->memInhibitAsserted() && pkt->needsResponse()) {
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// Update the sender state so we can deal with the response
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// appropriately
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RequestState *req_state = new RequestState(pkt);
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pkt->senderState = req_state;
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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 (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(DeferredRequest(pkt, readyTime));
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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 request state should be stored in the packet's
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// senderState field.
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RequestState *req_state = dynamic_cast<RequestState*>(pkt->senderState);
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assert(req_state != 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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req_state->fixResponse(pkt);
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// the bridge assumes that at least one bus has set the
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// destination field of the packet
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assert(pkt->isDestValid());
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DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest());
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delete req_state;
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Tick readyTime = curTick() + delay;
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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(DeferredResponse(pkt, readyTime));
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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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DeferredRequest req = requestQueue.front();
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assert(req.ready <= curTick());
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PacketPtr pkt = req.pkt;
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DPRINTF(BusBridge, "trySend request: addr 0x%x\n", pkt->getAddr());
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if (sendTimingReq(pkt)) {
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// send successful
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requestQueue.pop_front();
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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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req = requestQueue.front();
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DPRINTF(BusBridge, "Scheduling next send\n");
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bridge->schedule(sendEvent,
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std::max(req.ready, curTick() + 1));
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}
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} else {
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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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DeferredResponse resp = responseQueue.front();
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assert(resp.ready <= curTick());
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PacketPtr pkt = resp.pkt;
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DPRINTF(BusBridge, "trySend response: dest %d addr 0x%x\n",
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pkt->getDest(), pkt->getAddr());
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bool was_nacked_here = resp.nackedHere;
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if (sendTimingResp(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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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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resp = responseQueue.front();
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DPRINTF(BusBridge, "Scheduling next send\n");
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bridge->schedule(sendEvent,
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std::max(resp.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::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::BridgeSlavePort::recvFunctional(PacketPtr pkt)
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{
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std::list<DeferredResponse>::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<DeferredRequest>::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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