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Diffstat (limited to 'src/mem/bridge.cc')
-rw-r--r-- | src/mem/bridge.cc | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/src/mem/bridge.cc b/src/mem/bridge.cc new file mode 100644 index 000000000..9c14e7ee2 --- /dev/null +++ b/src/mem/bridge.cc @@ -0,0 +1,262 @@ + +/* + * Copyright (c) 2006 The Regents of The University of Michigan + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer; + * redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution; + * neither the name of the copyright holders nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * Authors: Ali Saidi + * Steve Reinhardt + */ + +/** + * @file + * Definition of a simple bus bridge without buffering. + */ + +#include <algorithm> + +#include "base/trace.hh" +#include "mem/bridge.hh" +#include "sim/builder.hh" + +Bridge::BridgePort::BridgePort(const std::string &_name, + Bridge *_bridge, BridgePort *_otherPort, + int _delay, int _queueLimit) + : Port(_name), bridge(_bridge), otherPort(_otherPort), + delay(_delay), outstandingResponses(0), + queueLimit(_queueLimit), sendEvent(this) +{ +} + +Bridge::Bridge(const std::string &n, int qsa, int qsb, + Tick _delay, int write_ack) + : MemObject(n), + portA(n + "-portA", this, &portB, _delay, qsa), + portB(n + "-portB", this, &portA, _delay, qsa), + ackWrites(write_ack) +{ +} + +Port * +Bridge::getPort(const std::string &if_name, int idx) +{ + BridgePort *port; + + if (if_name == "side_a") + port = &portA; + else if (if_name == "side_b") + port = &portB; + else + return NULL; + + if (port->getPeer() != NULL) + panic("bridge side %s already connected to.", if_name); + return port; +} + + +void +Bridge::init() +{ + // Make sure that both sides are connected to. + if (portA.getPeer() == NULL || portB.getPeer() == NULL) + panic("Both ports of bus bridge are not connected to a bus.\n"); +} + + +/** Function called by the port when the bus is receiving a Timing + * transaction.*/ +bool +Bridge::BridgePort::recvTiming(Packet *pkt) +{ + DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", + pkt->getSrc(), pkt->getDest(), pkt->getAddr()); + + return otherPort->queueForSendTiming(pkt); +} + + +bool +Bridge::BridgePort::queueForSendTiming(Packet *pkt) +{ + if (queueFull()) + return false; + + if (pkt->isResponse()) { + // This is a response for a request we forwarded earlier. The + // corresponding PacketBuffer should be stored in the packet's + // senderState field. + PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState); + assert(buf != NULL); + // set up new packet dest & senderState based on values saved + // from original request + buf->fixResponse(pkt); + DPRINTF(BusBridge, "restoring sender state: %#X, from packet buffer: %#X\n", + pkt->senderState, buf); + DPRINTF(BusBridge, " is response, new dest %d\n", pkt->getDest()); + delete buf; + } + + Tick readyTime = curTick + delay; + PacketBuffer *buf = new PacketBuffer(pkt, readyTime); + DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n", + buf->origSenderState, buf); + + // If we're about to put this packet at the head of the queue, we + // need to schedule an event to do the transmit. Otherwise there + // should already be an event scheduled for sending the head + // packet. + if (sendQueue.empty()) { + sendEvent.schedule(readyTime); + } + + sendQueue.push_back(buf); + + return true; +} + +void +Bridge::BridgePort::trySend() +{ + assert(!sendQueue.empty()); + + bool was_full = queueFull(); + + PacketBuffer *buf = sendQueue.front(); + + assert(buf->ready <= curTick); + + Packet *pkt = buf->pkt; + + DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", + buf->origSrc, pkt->getDest(), pkt->getAddr()); + + if (sendTiming(pkt)) { + // send successful + sendQueue.pop_front(); + buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it + + if (buf->expectResponse) { + // Must wait for response. We just need to count outstanding + // responses (in case we want to cap them); PacketBuffer + // pointer will be recovered on response. + ++outstandingResponses; + DPRINTF(BusBridge, " successful: awaiting response (%d)\n", + outstandingResponses); + } else { + // no response expected... deallocate packet buffer now. + DPRINTF(BusBridge, " successful: no response expected\n"); + delete buf; + } + + // If there are more packets to send, schedule event to try again. + if (!sendQueue.empty()) { + buf = sendQueue.front(); + sendEvent.schedule(std::max(buf->ready, curTick + 1)); + } + // Let things start sending again + if (was_full) { + DPRINTF(BusBridge, "Queue was full, sending retry\n"); + otherPort->sendRetry(); + } + + } else { + DPRINTF(BusBridge, " unsuccessful\n"); + } +} + + +void +Bridge::BridgePort::recvRetry() +{ + trySend(); +} + +/** Function called by the port when the bus is receiving a Atomic + * transaction.*/ +Tick +Bridge::BridgePort::recvAtomic(Packet *pkt) +{ + return otherPort->sendAtomic(pkt) + delay; +} + +/** Function called by the port when the bus is receiving a Functional + * transaction.*/ +void +Bridge::BridgePort::recvFunctional(Packet *pkt) +{ + std::list<PacketBuffer*>::iterator i; + bool pktContinue = true; + + for (i = sendQueue.begin(); i != sendQueue.end(); ++i) { + if (pkt->intersect((*i)->pkt)) { + pktContinue &= fixPacket(pkt, (*i)->pkt); + } + } + + if (pktContinue) { + otherPort->sendFunctional(pkt); + } +} + +/** Function called by the port when the bus is receiving a status change.*/ +void +Bridge::BridgePort::recvStatusChange(Port::Status status) +{ + otherPort->sendStatusChange(status); +} + +void +Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp, + AddrRangeList &snoop) +{ + otherPort->getPeerAddressRanges(resp, snoop); +} + +BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge) + + Param<int> queue_size_a; + Param<int> queue_size_b; + Param<Tick> delay; + Param<bool> write_ack; + +END_DECLARE_SIM_OBJECT_PARAMS(Bridge) + +BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge) + + INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"), + INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"), + INIT_PARAM(delay, "The miminum delay to cross this bridge"), + INIT_PARAM(write_ack, "Acknowledge any writes that are received.") + +END_INIT_SIM_OBJECT_PARAMS(Bridge) + +CREATE_SIM_OBJECT(Bridge) +{ + return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay, + write_ack); +} + +REGISTER_SIM_OBJECT("Bridge", Bridge) |