-
/*
+ * 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/Bridge.hh"
#include "mem/bridge.hh"
-#include "sim/builder.hh"
-
-Bridge::BridgePort::BridgePort(const std::string &_name,
- Bridge *_bridge, BridgePort *_otherPort,
- int _delay, int _queueLimit,
- bool fix_partial_write)
- : Port(_name), bridge(_bridge), otherPort(_otherPort),
- delay(_delay), fixPartialWrite(fix_partial_write),
- outstandingResponses(0), queuedRequests(0),
- queueLimit(_queueLimit), sendEvent(this)
+#include "params/Bridge.hh"
+
+Bridge::BridgeSlavePort::BridgeSlavePort(const std::string& _name,
+ Bridge& _bridge,
+ BridgeMasterPort& _masterPort,
+ Cycles _delay, int _resp_limit,
+ std::vector<AddrRange> _ranges)
+ : SlavePort(_name, &_bridge), bridge(_bridge), masterPort(_masterPort),
+ delay(_delay), ranges(_ranges.begin(), _ranges.end()),
+ outstandingResponses(0), retryReq(false),
+ respQueueLimit(_resp_limit), sendEvent(*this)
{
}
-Bridge::Bridge(const std::string &n, int qsa, int qsb,
- Tick _delay, int write_ack, bool fix_partial_write_a,
- bool fix_partial_write_b)
- : MemObject(n),
- portA(n + "-portA", this, &portB, _delay, qsa, fix_partial_write_a),
- portB(n + "-portB", this, &portA, _delay, qsa, fix_partial_write_b),
- ackWrites(write_ack)
+Bridge::BridgeMasterPort::BridgeMasterPort(const std::string& _name,
+ Bridge& _bridge,
+ BridgeSlavePort& _slavePort,
+ Cycles _delay, int _req_limit)
+ : MasterPort(_name, &_bridge), bridge(_bridge), slavePort(_slavePort),
+ delay(_delay), reqQueueLimit(_req_limit), sendEvent(*this)
{
- if (ackWrites)
- panic("No support for acknowledging writes\n");
}
-Port *
-Bridge::getPort(const std::string &if_name, int idx)
+Bridge::Bridge(Params *p)
+ : MemObject(p),
+ slavePort(p->name + ".slave", *this, masterPort,
+ ticksToCycles(p->delay), p->resp_size, p->ranges),
+ masterPort(p->name + ".master", *this, slavePort,
+ ticksToCycles(p->delay), p->req_size)
{
- BridgePort *port;
+}
- if (if_name == "side_a")
- port = &portA;
- else if (if_name == "side_b")
- port = &portB;
+BaseMasterPort&
+Bridge::getMasterPort(const std::string &if_name, PortID idx)
+{
+ 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);
}
+BaseSlavePort&
+Bridge::getSlavePort(const std::string &if_name, PortID 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::queueFull()
+Bridge::BridgeSlavePort::respQueueFull()
{
- // use >= here because sendQueue could get larger because of
- // nacks getting inserted
- return queuedRequests + outstandingResponses >= queueLimit;
+ return outstandingResponses == respQueueLimit;
}
-/** Function called by the port when the bus is receiving a Timing
- * transaction.*/
bool
-Bridge::BridgePort::recvTiming(PacketPtr pkt)
+Bridge::BridgeMasterPort::reqQueueFull()
{
- if (!(pkt->flags & SNOOP_COMMIT))
- return true;
+ return transmitList.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(Bridge, "recvTimingResp: %s addr 0x%x\n",
+ pkt->cmdString(), pkt->getAddr());
- DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
- pkt->getSrc(), pkt->getDest(), pkt->getAddr());
+ DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size());
- if (pkt->isRequest() && otherPort->queueFull()) {
- DPRINTF(BusBridge, "Remote queue full, nacking\n");
- nackRequest(pkt);
- return true;
- }
+ slavePort.schedTimingResp(pkt, bridge.clockEdge(delay));
- if (pkt->needsResponse() && pkt->result != Packet::Nacked)
- if (queueFull()) {
- 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;
+ return true;
+}
+
+bool
+Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt)
+{
+ DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n",
+ pkt->cmdString(), pkt->getAddr());
+
+ // ensure we do not have something waiting to retry
+ if(retryReq)
+ return false;
+
+ DPRINTF(Bridge, "Response queue size: %d outresp: %d\n",
+ transmitList.size(), outstandingResponses);
+
+ if (masterPort.reqQueueFull()) {
+ DPRINTF(Bridge, "Request queue full\n");
+ retryReq = true;
+ } else if (pkt->needsResponse()) {
+ if (respQueueFull()) {
+ DPRINTF(Bridge, "Response queue full\n");
+ retryReq = true;
} else {
- DPRINTF(BusBridge, "Request Needs response, reserving space\n");
+ DPRINTF(Bridge, "Reserving space for response\n");
+ assert(outstandingResponses != respQueueLimit);
++outstandingResponses;
+ retryReq = false;
+ masterPort.schedTimingReq(pkt, bridge.clockEdge(delay));
}
+ }
- otherPort->queueForSendTiming(pkt);
-
- return true;
+ // remember that we are now stalling a packet and that we have to
+ // tell the sending master to retry once space becomes available,
+ // we make no distinction whether the stalling is due to the
+ // request queue or response queue being full
+ return !retryReq;
}
void
-Bridge::BridgePort::nackRequest(PacketPtr pkt)
+Bridge::BridgeSlavePort::retryStalledReq()
{
- // Nack the packet
- pkt->result = Packet::Nacked;
- pkt->setDest(pkt->getSrc());
-
- //put it on the list to send
- Tick readyTime = curTick + delay;
- PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true);
- if (sendQueue.empty()) {
- sendEvent.schedule(readyTime);
+ if (retryReq) {
+ DPRINTF(Bridge, "Request waiting for retry, now retrying\n");
+ retryReq = false;
+ sendRetry();
}
- sendQueue.push_back(buf);
}
-
void
-Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
+Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when)
{
- if (pkt->isResponse() || pkt->result == Packet::Nacked) {
- // 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 (this is either it or
- // its a nacked packet and we won't be seeing that response)
- if (buf->expectResponse)
- --outstandingResponses;
-
-
- 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;
+ // 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 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 (transmitList.empty()) {
+ bridge.schedule(sendEvent, when);
}
- Tick readyTime = curTick + delay;
- PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
- DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
- buf->origSenderState, buf);
+ assert(transmitList.size() != reqQueueLimit);
+
+ transmitList.push_back(DeferredPacket(pkt, when));
+}
+
+
+void
+Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when)
+{
+ // 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);
+ delete req_state;
+
+ // the bridge assumes that at least one bus has set the
+ // destination field of the packet
+ assert(pkt->isDestValid());
+ DPRINTF(Bridge, "response, new dest %d\n", pkt->getDest());
// 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 (transmitList.empty()) {
+ bridge.schedule(sendEvent, when);
}
- ++queuedRequests;
- sendQueue.push_back(buf);
+
+ transmitList.push_back(DeferredPacket(pkt, when));
}
void
-Bridge::BridgePort::trySend()
+Bridge::BridgeMasterPort::trySendTiming()
{
- assert(!sendQueue.empty());
+ assert(!transmitList.empty());
- bool was_full = queueFull();
- int pbs = peerBlockSize();
+ DeferredPacket req = transmitList.front();
- PacketBuffer *buf = sendQueue.front();
+ assert(req.tick <= curTick());
- assert(buf->ready <= curTick);
+ PacketPtr pkt = req.pkt;
- PacketPtr pkt = buf->pkt;
+ DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n",
+ pkt->getAddr(), transmitList.size());
- pkt->flags &= ~SNOOP_COMMIT; //CLear it if it was set
+ if (sendTimingReq(pkt)) {
+ // send successful
+ transmitList.pop_front();
+ DPRINTF(Bridge, "trySend request successful\n");
- if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite &&
- pkt->result != Packet::Nacked && pkt->getOffset(pbs) &&
- pkt->getSize() != pbs) {
- buf->partialWriteFix(this);
- pkt = buf->pkt;
+ // If there are more packets to send, schedule event to try again.
+ if (!transmitList.empty()) {
+ req = transmitList.front();
+ DPRINTF(Bridge, "Scheduling next send\n");
+ bridge.schedule(sendEvent, std::max(req.tick,
+ bridge.nextCycle()));
+ }
+
+ // if we have stalled a request due to a full request queue,
+ // then send a retry at this point, also note that if the
+ // request we stalled was waiting for the response queue
+ // rather than the request queue we might stall it again
+ slavePort.retryStalledReq();
}
- DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
- buf->origSrc, pkt->getDest(), pkt->getAddr());
+ // if the send failed, then we try again once we receive a retry,
+ // and therefore there is no need to take any action
+}
+
+void
+Bridge::BridgeSlavePort::trySendTiming()
+{
+ assert(!transmitList.empty());
+ DeferredPacket resp = transmitList.front();
- 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
+ assert(resp.tick <= curTick());
- 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;
- }
+ PacketPtr pkt = resp.pkt;
- if (!buf->nacked)
- --queuedRequests;
+ DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n",
+ pkt->getAddr(), outstandingResponses);
+
+ if (sendTimingResp(pkt)) {
+ // send successful
+ transmitList.pop_front();
+ DPRINTF(Bridge, "trySend response successful\n");
+
+ assert(outstandingResponses != 0);
+ --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");
- sendEvent.schedule(std::max(buf->ready, curTick + 1));
- }
- // Let things start sending again
- if (was_full && !queueFull()) {
- DPRINTF(BusBridge, "Queue was full, sending retry\n");
- otherPort->sendRetry();
+ if (!transmitList.empty()) {
+ resp = transmitList.front();
+ DPRINTF(Bridge, "Scheduling next send\n");
+ bridge.schedule(sendEvent, std::max(resp.tick,
+ bridge.nextCycle()));
}
- } else {
- DPRINTF(BusBridge, " unsuccessful\n");
- buf->undoPartialWriteFix();
+ // if there is space in the request queue and we were stalling
+ // a request, it will definitely be possible to accept it now
+ // since there is guaranteed space in the response queue
+ if (!masterPort.reqQueueFull() && retryReq) {
+ DPRINTF(Bridge, "Request waiting for retry, now retrying\n");
+ retryReq = false;
+ sendRetry();
+ }
}
- DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n",
- sendQueue.size(), queuedRequests, outstandingResponses);
+
+ // if the send failed, then we try again once we receive a retry,
+ // and therefore there is no need to take any action
}
+void
+Bridge::BridgeMasterPort::recvRetry()
+{
+ Tick nextReady = transmitList.front().tick;
+ if (nextReady <= curTick())
+ trySendTiming();
+ else
+ bridge.schedule(sendEvent, nextReady);
+}
void
-Bridge::BridgePort::recvRetry()
+Bridge::BridgeSlavePort::recvRetry()
{
- trySend();
+ Tick nextReady = transmitList.front().tick;
+ if (nextReady <= curTick())
+ trySendTiming();
+ 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::BridgeSlavePort::recvAtomic(PacketPtr pkt)
{
- return otherPort->sendAtomic(pkt) + delay;
+ return delay * bridge.clockPeriod() + 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;
- bool pktContinue = true;
+ std::list<DeferredPacket>::iterator i;
+
+ pkt->pushLabel(name());
- for (i = sendQueue.begin(); i != sendQueue.end(); ++i) {
- if (pkt->intersect((*i)->pkt)) {
- pktContinue &= fixPacket(pkt, (*i)->pkt);
+ // check the response queue
+ for (i = transmitList.begin(); i != transmitList.end(); ++i) {
+ if (pkt->checkFunctional((*i).pkt)) {
+ pkt->makeResponse();
+ return;
}
}
- if (pktContinue) {
- otherPort->sendFunctional(pkt);
+ // also check the master port's request queue
+ if (masterPort.checkFunctional(pkt)) {
+ return;
}
-}
-/** Function called by the port when the bus is receiving a status change.*/
-void
-Bridge::BridgePort::recvStatusChange(Port::Status status)
-{
- otherPort->sendStatusChange(status);
-}
+ pkt->popLabel();
-void
-Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
- AddrRangeList &snoop)
-{
- otherPort->getPeerAddressRanges(resp, snoop);
+ // fall through if pkt still not satisfied
+ masterPort.sendFunctional(pkt);
}
-BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)
-
- Param<int> queue_size_a;
- Param<int> queue_size_b;
- Param<Tick> delay;
- Param<bool> write_ack;
- Param<bool> fix_partial_write_a;
- Param<bool> fix_partial_write_b;
-
-END_DECLARE_SIM_OBJECT_PARAMS(Bridge)
-
-BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)
+bool
+Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt)
+{
+ bool found = false;
+ std::list<DeferredPacket>::iterator i = transmitList.begin();
- 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."),
- INIT_PARAM(fix_partial_write_a, "Fixup any partial block writes that are received"),
- INIT_PARAM(fix_partial_write_b, "Fixup any partial block writes that are received")
+ while(i != transmitList.end() && !found) {
+ if (pkt->checkFunctional((*i).pkt)) {
+ pkt->makeResponse();
+ found = true;
+ }
+ ++i;
+ }
-END_INIT_SIM_OBJECT_PARAMS(Bridge)
+ return found;
+}
-CREATE_SIM_OBJECT(Bridge)
+AddrRangeList
+Bridge::BridgeSlavePort::getAddrRanges() const
{
- return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
- write_ack, fix_partial_write_a, fix_partial_write_b);
+ return ranges;
}
-REGISTER_SIM_OBJECT("Bridge", Bridge)
-
+Bridge *
+BridgeParams::create()
+{
+ return new Bridge(this);
+}
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