-
/*
+ * Copyright (c) 2011-2012 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.
*
*
* 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/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, bool fix_partial_write)
- : Port(_name), bridge(_bridge), otherPort(_otherPort),
- delay(_delay), nackDelay(_nack_delay), fixPartialWrite(fix_partial_write),
- 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)
+ : SlavePort(_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)
+ : MasterPort(_name, _bridge), bridge(_bridge), slavePort(_slavePort),
+ delay(_delay), inRetry(false), reqQueueLimit(_req_limit),
+ sendEvent(*this)
{
}
Bridge::Bridge(Params *p)
- : MemObject(p->name),
- portA(p->name + "-portA", this, &portB, p->delay, p->nack_delay,
- p->req_size_a, p->resp_size_a, p->fix_partial_write_a),
- portB(p->name + "-portB", this, &portA, p->delay, p->nack_delay,
- p->req_size_b, p->resp_size_b, p->fix_partial_write_b),
+ : MemObject(p),
+ 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 *
-Bridge::getPort(const std::string &if_name, int idx)
+MasterPort&
+Bridge::getMasterPort(const std::string &if_name, int idx)
{
- BridgePort *port;
-
- if (if_name == "side_a")
- port = &portA;
- else if (if_name == "side_b")
- port = &portB;
+ if (if_name == "master")
+ return masterPort;
else
- return NULL;
-
- if (port->getPeer() != NULL)
- panic("bridge side %s already connected to.", if_name);
- return port;
+ // pass it along to our super class
+ return MemObject::getMasterPort(if_name, idx);
}
+SlavePort&
+Bridge::getSlavePort(const std::string &if_name, int idx)
+{
+ if (if_name == "slave")
+ return slavePort;
+ else
+ // pass it along to our super class
+ return MemObject::getSlavePort(if_name, idx);
+}
void
Bridge::init()
{
- // Make sure that both sides are connected to.
- if (portA.getPeer() == NULL || portB.getPeer() == NULL)
+ // 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("Busses don't have the same block size... Not supported.\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",
+ 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;
+}
+
+bool
+Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt)
+{
+ // 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: response %s addr 0x%x\n",
+ pkt->cmdString(), pkt->getAddr());
+
+ DPRINTF(BusBridge, "Request queue size: %d\n", requestQueue.size());
+
+ slavePort.queueForSendTiming(pkt);
+
+ return true;
}
-/** Function called by the port when the bus is receiving a Timing
- * transaction.*/
bool
-Bridge::BridgePort::recvTiming(PacketPtr pkt)
+Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt)
{
- DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
- pkt->getSrc(), pkt->getDest(), pkt->getAddr());
+ DPRINTF(BusBridge, "recvTiming: request %s addr 0x%x\n",
+ pkt->cmdString(), pkt->getAddr());
- DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n",
- sendQueue.size(), queuedRequests, outstandingResponses);
- DPRINTF(BusBridge, "Remove queue size: %d outreq: %d outresp: %d\n",
- otherPort->sendQueue.size(), otherPort->queuedRequests,
- otherPort->outstandingResponses);
+ DPRINTF(BusBridge, "Response queue size: %d outresp: %d\n",
+ responseQueue.size(), outstandingResponses);
- if (pkt->isRequest() && otherPort->reqQueueFull() && !pkt->wasNacked()) {
- DPRINTF(BusBridge, "Remote queue full, nacking\n");
+ if (masterPort.reqQueueFull()) {
+ DPRINTF(BusBridge, "Request queue full, nacking\n");
nackRequest(pkt);
return true;
}
- if (pkt->needsResponse() && !pkt->wasNacked())
+ 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();
- pkt->setDest(pkt->getSrc());
- //put it on the list to send
- Tick readyTime = curTick + nackDelay;
- PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true);
+ // 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;
+ DeferredResponse resp(pkt, readyTime, true);
// nothing on the list, add it and we're done
- if (sendQueue.empty()) {
+ if (responseQueue.empty()) {
assert(!sendEvent.scheduled());
- sendEvent.schedule(readyTime);
- sendQueue.push_back(buf);
+ bridge->schedule(sendEvent, readyTime);
+ responseQueue.push_back(resp);
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(resp);
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<DeferredResponse>::iterator i = responseQueue.begin();
+ std::list<DeferredResponse>::iterator end = responseQueue.end();
+ std::list<DeferredResponse>::iterator begin = responseQueue.begin();
bool done = false;
while (i != end && !done) {
- if (readyTime < (*i)->ready) {
+ if (readyTime < (*i).ready) {
if (i == begin)
- sendEvent.reschedule(readyTime);
- sendQueue.insert(i,buf);
+ bridge->reschedule(sendEvent, readyTime);
+ responseQueue.insert(i, resp);
done = true;
}
i++;
assert(done);
}
-
void
-Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
+Bridge::BridgeMasterPort::queueForSendTiming(PacketPtr pkt)
{
- if (pkt->isResponse() || pkt->wasNacked()) {
- // 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);
-
- // Check if this packet was expecting a response and it's a nacked
- // packet, in which case we will never being seeing it
- if (buf->expectResponse && pkt->wasNacked())
- --outstandingResponses;
-
- DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest());
- delete buf;
+ Tick readyTime = curTick() + delay;
+
+ // If we expect to see a response, we need to restore the source
+ // and destination field that is potentially changed by a second
+ // bus
+ if (!pkt->memInhibitAsserted() && pkt->needsResponse()) {
+ // Update the sender state so we can deal with the response
+ // appropriately
+ RequestState *req_state = new RequestState(pkt);
+ pkt->senderState = req_state;
}
-
- if (pkt->isRequest() && !pkt->wasNacked()) {
- ++queuedRequests;
+ // 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);
+ requestQueue.push_back(DeferredRequest(pkt, readyTime));
+}
- Tick readyTime = curTick + delay;
- PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
+
+void
+Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt)
+{
+ // This is a response for a request we forwarded earlier. The
+ // corresponding request state should be stored in the packet's
+ // senderState field.
+ RequestState *req_state = dynamic_cast<RequestState*>(pkt->senderState);
+ assert(req_state != NULL);
+ // set up new packet dest & senderState based on values saved
+ // from original request
+ req_state->fixResponse(pkt);
+
+ // the bridge assumes that at least one bus has set the
+ // destination field of the packet
+ assert(pkt->isDestValid());
+ DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest());
+ delete req_state;
+
+ Tick readyTime = curTick() + delay;
// 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);
+ if (responseQueue.empty()) {
+ bridge->schedule(sendEvent, readyTime);
}
- sendQueue.push_back(buf);
+ responseQueue.push_back(DeferredResponse(pkt, readyTime));
}
void
-Bridge::BridgePort::trySend()
+Bridge::BridgeMasterPort::trySend()
{
- assert(!sendQueue.empty());
+ assert(!requestQueue.empty());
+
+ DeferredRequest req = requestQueue.front();
- PacketBuffer *buf = sendQueue.front();
+ assert(req.ready <= curTick());
- assert(buf->ready <= curTick);
+ PacketPtr pkt = req.pkt;
- PacketPtr pkt = buf->pkt;
+ DPRINTF(BusBridge, "trySend request: addr 0x%x\n", pkt->getAddr());
+
+ if (sendTimingReq(pkt)) {
+ // send successful
+ requestQueue.pop_front();
- // Ugly! @todo When multilevel coherence works this will be removed
- if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite &&
- !pkt->wasNacked()) {
- PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq,
- Packet::Broadcast);
- funcPkt->dataStatic(pkt->getPtr<uint8_t>());
- sendFunctional(funcPkt);
- pkt->cmd = MemCmd::WriteReq;
- delete funcPkt;
+ // If there are more packets to send, schedule event to try again.
+ if (!requestQueue.empty()) {
+ req = requestQueue.front();
+ DPRINTF(BusBridge, "Scheduling next send\n");
+ bridge->schedule(sendEvent,
+ std::max(req.ready, curTick() + 1));
+ }
+ } else {
+ inRetry = true;
}
- DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
- buf->origSrc, pkt->getDest(), pkt->getAddr());
+ DPRINTF(BusBridge, "trySend: request queue size: %d\n",
+ requestQueue.size());
+}
- bool wasReq = pkt->isRequest();
- bool wasNacked = pkt->wasNacked();
+void
+Bridge::BridgeSlavePort::trySend()
+{
+ assert(!responseQueue.empty());
- 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
+ DeferredResponse resp = responseQueue.front();
- 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;
- }
+ assert(resp.ready <= curTick());
+
+ PacketPtr pkt = resp.pkt;
+
+ DPRINTF(BusBridge, "trySend response: dest %d addr 0x%x\n",
+ pkt->getDest(), pkt->getAddr());
- if (!wasNacked) {
- if (wasReq)
- --queuedRequests;
- else
- --outstandingResponses;
+ bool was_nacked_here = resp.nackedHere;
+
+ if (sendTimingResp(pkt)) {
+ DPRINTF(BusBridge, " successful\n");
+ // send successful
+ responseQueue.pop_front();
+
+ 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()) {
+ resp = responseQueue.front();
DPRINTF(BusBridge, "Scheduling next send\n");
- sendEvent.schedule(std::max(buf->ready, curTick + 1));
+ bridge->schedule(sendEvent,
+ std::max(resp.ready, curTick() + 1));
}
} else {
DPRINTF(BusBridge, " unsuccessful\n");
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;
- if (nextReady <= curTick)
+ Tick nextReady = responseQueue.front().ready;
+ if (nextReady <= curTick())
trySend();
else
- sendEvent.schedule(nextReady);
+ bridge->schedule(sendEvent, nextReady);
}
-/** Function called by the port when the bus is receiving a Atomic
- * transaction.*/
Tick
-Bridge::BridgePort::recvAtomic(PacketPtr pkt)
+Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt)
{
- // fix partial atomic writes... similar to the timing code that does the
- // same... will be removed once our code gets this right
- if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite) {
-
- PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq,
- Packet::Broadcast);
- funcPkt->dataStatic(pkt->getPtr<uint8_t>());
- otherPort->sendFunctional(funcPkt);
- delete funcPkt;
- pkt->cmd = MemCmd::WriteReq;
- }
- return delay + otherPort->sendAtomic(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::BridgeSlavePort::recvFunctional(PacketPtr pkt)
{
- std::list<PacketBuffer*>::iterator i;
+ std::list<DeferredResponse>::iterator i;
+
+ pkt->pushLabel(name());
- for (i = sendQueue.begin(); i != sendQueue.end(); ++i) {
- if (pkt->checkFunctional((*i)->pkt))
+ // 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);
}
-/** Function called by the port when the bus is receiving a status change.*/
-void
-Bridge::BridgePort::recvStatusChange(Port::Status status)
+bool
+Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt)
{
- otherPort->sendStatusChange(status);
+ bool found = false;
+ std::list<DeferredRequest>::iterator i = requestQueue.begin();
+
+ while(i != requestQueue.end() && !found) {
+ if (pkt->checkFunctional((*i).pkt)) {
+ pkt->makeResponse();
+ found = true;
+ }
+ ++i;
+ }
+
+ return found;
}
-void
-Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
- bool &snoop)
+AddrRangeList
+Bridge::BridgeSlavePort::getAddrRanges() const
{
- otherPort->getPeerAddressRanges(resp, snoop);
- // we don't allow snooping across bridges
- snoop = false;
+ return ranges;
}
Bridge *
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