gem5/src/mem/bridge.cc
2009-11-18 13:55:57 -08:00

359 lines
11 KiB
C++

/*
* 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/range_ops.hh"
#include "base/trace.hh"
#include "mem/bridge.hh"
#include "params/Bridge.hh"
Bridge::BridgePort::BridgePort(const std::string &_name,
Bridge *_bridge, BridgePort *_otherPort,
int _delay, int _nack_delay, int _req_limit,
int _resp_limit,
std::vector<Range<Addr> > filter_ranges)
: Port(_name, _bridge), bridge(_bridge), otherPort(_otherPort),
delay(_delay), nackDelay(_nack_delay), filterRanges(filter_ranges),
outstandingResponses(0), queuedRequests(0), inRetry(false),
reqQueueLimit(_req_limit), respQueueLimit(_resp_limit), sendEvent(this)
{
}
Bridge::Bridge(Params *p)
: MemObject(p),
portA(p->name + "-portA", this, &portB, p->delay, p->nack_delay,
p->req_size_a, p->resp_size_a, p->filter_ranges_a),
portB(p->name + "-portB", this, &portA, p->delay, p->nack_delay,
p->req_size_b, p->resp_size_b, p->filter_ranges_b),
ackWrites(p->write_ack), _params(p)
{
if (ackWrites)
panic("No support for acknowledging writes\n");
}
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 && !port->getPeer()->isDefaultPort())
panic("bridge side %s already connected to %s.",
if_name, port->getPeer()->name());
return port;
}
void
Bridge::init()
{
// Make sure that both sides are connected to.
if (!portA.isConnected() || !portB.isConnected())
fatal("Both ports of bus bridge are not connected to a bus.\n");
if (portA.peerBlockSize() != portB.peerBlockSize())
fatal("port A size %d, port B size %d \n " \
"Busses don't have the same block size... Not supported.\n",
portA.peerBlockSize(), portB.peerBlockSize());
}
bool
Bridge::BridgePort::respQueueFull()
{
assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit);
return outstandingResponses >= respQueueLimit;
}
bool
Bridge::BridgePort::reqQueueFull()
{
assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit);
return queuedRequests >= reqQueueLimit;
}
/** Function called by the port when the bus is receiving a Timing
* transaction.*/
bool
Bridge::BridgePort::recvTiming(PacketPtr pkt)
{
DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr());
DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n",
sendQueue.size(), queuedRequests, outstandingResponses);
DPRINTF(BusBridge, "Remote queue size: %d outreq: %d outresp: %d\n",
otherPort->sendQueue.size(), otherPort->queuedRequests,
otherPort->outstandingResponses);
if (pkt->isRequest() && otherPort->reqQueueFull()) {
DPRINTF(BusBridge, "Remote queue full, nacking\n");
nackRequest(pkt);
return true;
}
if (pkt->needsResponse()) {
if (respQueueFull()) {
DPRINTF(BusBridge, "Local queue full, no space for response, nacking\n");
DPRINTF(BusBridge, "queue size: %d outreq: %d outstanding resp: %d\n",
sendQueue.size(), queuedRequests, outstandingResponses);
nackRequest(pkt);
return true;
} else {
DPRINTF(BusBridge, "Request Needs response, reserving space\n");
++outstandingResponses;
}
}
otherPort->queueForSendTiming(pkt);
return true;
}
void
Bridge::BridgePort::nackRequest(PacketPtr pkt)
{
// Nack the packet
pkt->makeTimingResponse();
pkt->setNacked();
//put it on the list to send
Tick readyTime = curTick + nackDelay;
PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true);
// nothing on the list, add it and we're done
if (sendQueue.empty()) {
assert(!sendEvent.scheduled());
schedule(sendEvent, readyTime);
sendQueue.push_back(buf);
return;
}
assert(sendEvent.scheduled() || inRetry);
// does it go at the end?
if (readyTime >= sendQueue.back()->ready) {
sendQueue.push_back(buf);
return;
}
// ok, somewhere in the middle, fun
std::list<PacketBuffer*>::iterator i = sendQueue.begin();
std::list<PacketBuffer*>::iterator end = sendQueue.end();
std::list<PacketBuffer*>::iterator begin = sendQueue.begin();
bool done = false;
while (i != end && !done) {
if (readyTime < (*i)->ready) {
if (i == begin)
reschedule(sendEvent, readyTime);
sendQueue.insert(i,buf);
done = true;
}
i++;
}
assert(done);
}
void
Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
{
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, "response, new dest %d\n", pkt->getDest());
delete buf;
}
if (pkt->isRequest()) {
++queuedRequests;
}
Tick readyTime = curTick + delay;
PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
// 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()) {
schedule(sendEvent, readyTime);
}
sendQueue.push_back(buf);
}
void
Bridge::BridgePort::trySend()
{
assert(!sendQueue.empty());
PacketBuffer *buf = sendQueue.front();
assert(buf->ready <= curTick);
PacketPtr pkt = buf->pkt;
DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
buf->origSrc, pkt->getDest(), pkt->getAddr());
bool wasReq = pkt->isRequest();
bool was_nacked_here = buf->nackedHere;
// If the send was successful, make sure sender state was set to NULL
// otherwise we could get a NACK back of a packet that didn't expect a
// response and we would try to use freed memory.
Packet::SenderState *old_sender_state = pkt->senderState;
if (pkt->isRequest() && !buf->expectResponse)
pkt->senderState = NULL;
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
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 (wasReq)
--queuedRequests;
else if (!was_nacked_here)
--outstandingResponses;
// If there are more packets to send, schedule event to try again.
if (!sendQueue.empty()) {
buf = sendQueue.front();
DPRINTF(BusBridge, "Scheduling next send\n");
schedule(sendEvent, std::max(buf->ready, curTick + 1));
}
} else {
DPRINTF(BusBridge, " unsuccessful\n");
pkt->senderState = old_sender_state;
inRetry = true;
}
DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n",
sendQueue.size(), queuedRequests, outstandingResponses);
}
void
Bridge::BridgePort::recvRetry()
{
inRetry = false;
Tick nextReady = sendQueue.front()->ready;
if (nextReady <= curTick)
trySend();
else
schedule(sendEvent, nextReady);
}
/** Function called by the port when the bus is receiving a Atomic
* transaction.*/
Tick
Bridge::BridgePort::recvAtomic(PacketPtr pkt)
{
return delay + otherPort->sendAtomic(pkt);
}
/** Function called by the port when the bus is receiving a Functional
* transaction.*/
void
Bridge::BridgePort::recvFunctional(PacketPtr pkt)
{
std::list<PacketBuffer*>::iterator i;
pkt->pushLabel(name());
for (i = sendQueue.begin(); i != sendQueue.end(); ++i) {
if (pkt->checkFunctional((*i)->pkt))
return;
}
pkt->popLabel();
// fall through if pkt still not satisfied
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,
bool &snoop)
{
otherPort->getPeerAddressRanges(resp, snoop);
FilterRangeList(filterRanges, resp);
// we don't allow snooping across bridges
snoop = false;
}
Bridge *
BridgeParams::create()
{
return new Bridge(this);
}