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+
+/*
+ * 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)
+{
+ 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)
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