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-rw-r--r--src/mem/bridge.cc381
1 files changed, 262 insertions, 119 deletions
diff --git a/src/mem/bridge.cc b/src/mem/bridge.cc
index 71cbcb76c..b48662118 100644
--- a/src/mem/bridge.cc
+++ b/src/mem/bridge.cc
@@ -1,5 +1,16 @@
-
/*
+ * Copyright (c) 2011 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder. You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
* Copyright (c) 2006 The Regents of The University of Michigan
* All rights reserved.
*
@@ -28,54 +39,63 @@
*
* Authors: Ali Saidi
* Steve Reinhardt
+ * Andreas Hansson
*/
/**
* @file
- * Definition of a simple bus bridge without buffering.
+ * Implementation of a memory-mapped bus bridge that connects a master
+ * and a slave through a request and response queue.
*/
-#include <algorithm>
-
-#include "base/range_ops.hh"
#include "base/trace.hh"
#include "debug/BusBridge.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::BridgeSlavePort::BridgeSlavePort(const std::string &_name,
+ Bridge* _bridge,
+ BridgeMasterPort* _masterPort,
+ int _delay, int _nack_delay,
+ int _resp_limit,
+ std::vector<Range<Addr> > _ranges)
+ : Port(_name, _bridge), bridge(_bridge), masterPort(_masterPort),
+ delay(_delay), nackDelay(_nack_delay),
+ ranges(_ranges.begin(), _ranges.end()),
+ outstandingResponses(0), inRetry(false),
+ respQueueLimit(_resp_limit), sendEvent(this)
+{
+}
+
+Bridge::BridgeMasterPort::BridgeMasterPort(const std::string &_name,
+ Bridge* _bridge,
+ BridgeSlavePort* _slavePort,
+ int _delay, int _req_limit)
+ : Port(_name, _bridge), bridge(_bridge), slavePort(_slavePort),
+ delay(_delay), inRetry(false), reqQueueLimit(_req_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),
+ slavePort(p->name + "-slave", this, &masterPort, p->delay,
+ p->nack_delay, p->resp_size, p->ranges),
+ masterPort(p->name + "-master", this, &slavePort, p->delay, p->req_size),
ackWrites(p->write_ack), _params(p)
{
if (ackWrites)
panic("No support for acknowledging writes\n");
}
-Port *
+Port*
Bridge::getPort(const std::string &if_name, int idx)
{
- BridgePort *port;
+ Port* port;
- if (if_name == "side_a")
- port = &portA;
- else if (if_name == "side_b")
- port = &portB;
+ if (if_name == "slave")
+ port = &slavePort;
+ else if (if_name == "master")
+ port = &masterPort;
else
return NULL;
@@ -89,106 +109,133 @@ Bridge::getPort(const std::string &if_name, int idx)
void
Bridge::init()
{
- // Make sure that both sides are connected to.
- if (!portA.isConnected() || !portB.isConnected())
+ // make sure both sides are connected and have the same block size
+ if (!slavePort.isConnected() || !masterPort.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 " \
+ if (slavePort.peerBlockSize() != masterPort.peerBlockSize())
+ fatal("Slave port size %d, master port size %d \n " \
"Busses don't have the same block size... Not supported.\n",
- portA.peerBlockSize(), portB.peerBlockSize());
+ slavePort.peerBlockSize(), masterPort.peerBlockSize());
+
+ // notify the master side of our address ranges
+ slavePort.sendRangeChange();
}
bool
-Bridge::BridgePort::respQueueFull()
+Bridge::BridgeSlavePort::respQueueFull()
{
- assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit);
- return outstandingResponses >= respQueueLimit;
+ return outstandingResponses == respQueueLimit;
}
bool
-Bridge::BridgePort::reqQueueFull()
+Bridge::BridgeMasterPort::reqQueueFull()
{
- assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit);
- return queuedRequests >= reqQueueLimit;
+ return requestQueue.size() == reqQueueLimit;
}
-/** Function called by the port when the bus is receiving a Timing
- * transaction.*/
bool
-Bridge::BridgePort::recvTiming(PacketPtr pkt)
+Bridge::BridgeMasterPort::recvTiming(PacketPtr pkt)
{
+ // should only see responses on the master side
+ assert(pkt->isResponse());
+
+ // all checks are done when the request is accepted on the slave
+ // side, so we are guaranteed to have space for the response
+
DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
- pkt->getSrc(), pkt->getDest(), pkt->getAddr());
+ pkt->getSrc(), pkt->getDest(), pkt->getAddr());
+
+ DPRINTF(BusBridge, "Request queue size: %d\n", requestQueue.size());
- 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);
+ slavePort->queueForSendTiming(pkt);
+
+ return true;
+}
- if (pkt->isRequest() && otherPort->reqQueueFull()) {
- DPRINTF(BusBridge, "Remote queue full, nacking\n");
+bool
+Bridge::BridgeSlavePort::recvTiming(PacketPtr pkt)
+{
+ // should only see requests on the slave side
+ assert(pkt->isRequest());
+
+ DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
+ pkt->getSrc(), pkt->getDest(), pkt->getAddr());
+
+ DPRINTF(BusBridge, "Response queue size: %d outresp: %d\n",
+ responseQueue.size(), outstandingResponses);
+
+ if (masterPort->reqQueueFull()) {
+ DPRINTF(BusBridge, "Request 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);
+ DPRINTF(BusBridge,
+ "Response queue full, no space for response, nacking\n");
+ DPRINTF(BusBridge,
+ "queue size: %d outstanding resp: %d\n",
+ responseQueue.size(), outstandingResponses);
nackRequest(pkt);
return true;
} else {
DPRINTF(BusBridge, "Request Needs response, reserving space\n");
+ assert(outstandingResponses != respQueueLimit);
++outstandingResponses;
}
}
- otherPort->queueForSendTiming(pkt);
+ masterPort->queueForSendTiming(pkt);
return true;
}
void
-Bridge::BridgePort::nackRequest(PacketPtr pkt)
+Bridge::BridgeSlavePort::nackRequest(PacketPtr pkt)
{
// Nack the packet
pkt->makeTimingResponse();
pkt->setNacked();
- //put it on the list to send
+ // The Nack packets are stored in the response queue just like any
+ // other response, but they do not occupy any space as this is
+ // tracked by the outstandingResponses, this guarantees space for
+ // the Nack packets, but implicitly means we have an (unrealistic)
+ // unbounded Nack queue.
+
+ // 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()) {
+ if (responseQueue.empty()) {
assert(!sendEvent.scheduled());
bridge->schedule(sendEvent, readyTime);
- sendQueue.push_back(buf);
+ responseQueue.push_back(buf);
return;
}
assert(sendEvent.scheduled() || inRetry);
// does it go at the end?
- if (readyTime >= sendQueue.back()->ready) {
- sendQueue.push_back(buf);
+ if (readyTime >= responseQueue.back()->ready) {
+ responseQueue.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();
+ std::list<PacketBuffer*>::iterator i = responseQueue.begin();
+ std::list<PacketBuffer*>::iterator end = responseQueue.end();
+ std::list<PacketBuffer*>::iterator begin = responseQueue.begin();
bool done = false;
while (i != end && !done) {
if (readyTime < (*i)->ready) {
if (i == begin)
bridge->reschedule(sendEvent, readyTime);
- sendQueue.insert(i,buf);
+ responseQueue.insert(i,buf);
done = true;
}
i++;
@@ -196,51 +243,60 @@ Bridge::BridgePort::nackRequest(PacketPtr pkt)
assert(done);
}
-
void
-Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
+Bridge::BridgeMasterPort::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;
+ 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 (requestQueue.empty()) {
+ bridge->schedule(sendEvent, readyTime);
}
+ assert(requestQueue.size() != reqQueueLimit);
- if (pkt->isRequest()) {
- ++queuedRequests;
- }
+ requestQueue.push_back(buf);
+}
+void
+Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt)
+{
+ // 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;
Tick readyTime = curTick() + delay;
- PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
+ 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()) {
+ if (responseQueue.empty()) {
bridge->schedule(sendEvent, readyTime);
}
- sendQueue.push_back(buf);
+ responseQueue.push_back(buf);
}
void
-Bridge::BridgePort::trySend()
+Bridge::BridgeMasterPort::trySend()
{
- assert(!sendQueue.empty());
+ assert(!requestQueue.empty());
- PacketBuffer *buf = sendQueue.front();
+ PacketBuffer *buf = requestQueue.front();
assert(buf->ready <= curTick());
@@ -249,107 +305,194 @@ Bridge::BridgePort::trySend()
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)
+ if (!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
+ requestQueue.pop_front();
+ // we no longer own packet, so it's not safe to look at it
+ buf->pkt = NULL;
- if (buf->expectResponse) {
- // Must wait for response
- DPRINTF(BusBridge, " successful: awaiting response (%d)\n",
- outstandingResponses);
- } else {
+ if (!buf->expectResponse) {
// no response expected... deallocate packet buffer now.
DPRINTF(BusBridge, " successful: no response expected\n");
delete buf;
}
- if (wasReq)
- --queuedRequests;
- else if (!was_nacked_here)
+ // If there are more packets to send, schedule event to try again.
+ if (!requestQueue.empty()) {
+ buf = requestQueue.front();
+ DPRINTF(BusBridge, "Scheduling next send\n");
+ bridge->schedule(sendEvent, std::max(buf->ready, curTick() + 1));
+ }
+ } else {
+ DPRINTF(BusBridge, " unsuccessful\n");
+ pkt->senderState = old_sender_state;
+ inRetry = true;
+ }
+
+ DPRINTF(BusBridge, "trySend: request queue size: %d\n",
+ requestQueue.size());
+}
+
+void
+Bridge::BridgeSlavePort::trySend()
+{
+ assert(!responseQueue.empty());
+
+ PacketBuffer *buf = responseQueue.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 was_nacked_here = buf->nackedHere;
+
+ // no need to worry about the sender state since we are not
+ // modifying it
+
+ if (sendTiming(pkt)) {
+ DPRINTF(BusBridge, " successful\n");
+ // send successful
+ responseQueue.pop_front();
+ // this is a response... deallocate packet buffer now.
+ delete buf;
+
+ if (!was_nacked_here) {
+ assert(outstandingResponses != 0);
--outstandingResponses;
+ }
// If there are more packets to send, schedule event to try again.
- if (!sendQueue.empty()) {
- buf = sendQueue.front();
+ if (!responseQueue.empty()) {
+ buf = responseQueue.front();
DPRINTF(BusBridge, "Scheduling next send\n");
bridge->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);
+ DPRINTF(BusBridge, "trySend: queue size: %d outstanding resp: %d\n",
+ responseQueue.size(), outstandingResponses);
}
+void
+Bridge::BridgeMasterPort::recvRetry()
+{
+ inRetry = false;
+ Tick nextReady = requestQueue.front()->ready;
+ if (nextReady <= curTick())
+ trySend();
+ else
+ bridge->schedule(sendEvent, nextReady);
+}
void
-Bridge::BridgePort::recvRetry()
+Bridge::BridgeSlavePort::recvRetry()
{
inRetry = false;
- Tick nextReady = sendQueue.front()->ready;
+ Tick nextReady = responseQueue.front()->ready;
if (nextReady <= curTick())
trySend();
else
bridge->schedule(sendEvent, nextReady);
}
-/** Function called by the port when the bus is receiving a Atomic
- * transaction.*/
Tick
-Bridge::BridgePort::recvAtomic(PacketPtr pkt)
+Bridge::BridgeMasterPort::recvAtomic(PacketPtr pkt)
{
- return delay + otherPort->sendAtomic(pkt);
+ // master port should never receive any atomic access (panic only
+ // works once the other side, i.e. the busses, respects this)
+ //
+ //panic("Master port on %s got a recvAtomic\n", bridge->name());
+ return 0;
+}
+
+Tick
+Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt)
+{
+ return delay + masterPort->sendAtomic(pkt);
}
-/** Function called by the port when the bus is receiving a Functional
- * transaction.*/
void
-Bridge::BridgePort::recvFunctional(PacketPtr pkt)
+Bridge::BridgeMasterPort::recvFunctional(PacketPtr pkt)
+{
+ // master port should never receive any functional access (panic
+ // only works once the other side, i.e. the busses, respect this)
+
+ // panic("Master port on %s got a recvFunctional\n", bridge->name());
+}
+
+void
+Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt)
{
std::list<PacketBuffer*>::iterator i;
pkt->pushLabel(name());
- for (i = sendQueue.begin(); i != sendQueue.end(); ++i) {
+ // check the response queue
+ for (i = responseQueue.begin(); i != responseQueue.end(); ++i) {
if (pkt->checkFunctional((*i)->pkt)) {
pkt->makeResponse();
return;
}
}
+ // also check the master port's request queue
+ if (masterPort->checkFunctional(pkt)) {
+ return;
+ }
+
pkt->popLabel();
// fall through if pkt still not satisfied
- otherPort->sendFunctional(pkt);
+ masterPort->sendFunctional(pkt);
+}
+
+bool
+Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt)
+{
+ bool found = false;
+ std::list<PacketBuffer*>::iterator i = requestQueue.begin();
+
+ while(i != requestQueue.end() && !found) {
+ if (pkt->checkFunctional((*i)->pkt)) {
+ pkt->makeResponse();
+ found = true;
+ }
+ ++i;
+ }
+
+ return found;
}
/** Function called by the port when the bridge is receiving a range change.*/
void
-Bridge::BridgePort::recvRangeChange()
+Bridge::BridgeMasterPort::recvRangeChange()
+{
+ // no need to forward as the bridge has a fixed set of ranges
+}
+
+void
+Bridge::BridgeSlavePort::recvRangeChange()
{
- otherPort->sendRangeChange();
+ // is a slave port so do nothing
}
AddrRangeList
-Bridge::BridgePort::getAddrRanges()
+Bridge::BridgeSlavePort::getAddrRanges()
{
- AddrRangeList ranges = otherPort->getPeer()->getAddrRanges();
- FilterRangeList(filterRanges, ranges);
return ranges;
}
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