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47 * Implementation of a memory-mapped bus bridge that connects a master
48 * and a slave through a request and response queue.
51 #include "base/trace.hh"
52 #include "debug/Bridge.hh"
53 #include "mem/bridge.hh"
54 #include "params/Bridge.hh"
56 Bridge::BridgeSlavePort::BridgeSlavePort(const std::string
& _name
,
58 BridgeMasterPort
& _masterPort
,
59 Cycles _delay
, int _resp_limit
,
60 std::vector
<Range
<Addr
> > _ranges
)
61 : SlavePort(_name
, &_bridge
), bridge(_bridge
), masterPort(_masterPort
),
62 delay(_delay
), ranges(_ranges
.begin(), _ranges
.end()),
63 outstandingResponses(0), retryReq(false),
64 respQueueLimit(_resp_limit
), sendEvent(*this)
68 Bridge::BridgeMasterPort::BridgeMasterPort(const std::string
& _name
,
70 BridgeSlavePort
& _slavePort
,
71 Cycles _delay
, int _req_limit
)
72 : MasterPort(_name
, &_bridge
), bridge(_bridge
), slavePort(_slavePort
),
73 delay(_delay
), reqQueueLimit(_req_limit
), sendEvent(*this)
77 Bridge::Bridge(Params
*p
)
79 slavePort(p
->name
+ ".slave", *this, masterPort
,
80 ticksToCycles(p
->delay
), p
->resp_size
, p
->ranges
),
81 masterPort(p
->name
+ ".master", *this, slavePort
,
82 ticksToCycles(p
->delay
), p
->req_size
)
87 Bridge::getMasterPort(const std::string
&if_name
, int idx
)
89 if (if_name
== "master")
92 // pass it along to our super class
93 return MemObject::getMasterPort(if_name
, idx
);
97 Bridge::getSlavePort(const std::string
&if_name
, int idx
)
99 if (if_name
== "slave")
102 // pass it along to our super class
103 return MemObject::getSlavePort(if_name
, idx
);
109 // make sure both sides are connected and have the same block size
110 if (!slavePort
.isConnected() || !masterPort
.isConnected())
111 fatal("Both ports of bus bridge are not connected to a bus.\n");
113 if (slavePort
.peerBlockSize() != masterPort
.peerBlockSize())
114 fatal("Slave port size %d, master port size %d \n " \
115 "Busses don't have the same block size... Not supported.\n",
116 slavePort
.peerBlockSize(), masterPort
.peerBlockSize());
118 // notify the master side of our address ranges
119 slavePort
.sendRangeChange();
123 Bridge::BridgeSlavePort::respQueueFull()
125 return outstandingResponses
== respQueueLimit
;
129 Bridge::BridgeMasterPort::reqQueueFull()
131 return transmitList
.size() == reqQueueLimit
;
135 Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt
)
137 // all checks are done when the request is accepted on the slave
138 // side, so we are guaranteed to have space for the response
139 DPRINTF(Bridge
, "recvTimingResp: %s addr 0x%x\n",
140 pkt
->cmdString(), pkt
->getAddr());
142 DPRINTF(Bridge
, "Request queue size: %d\n", transmitList
.size());
144 slavePort
.schedTimingResp(pkt
, bridge
.clockEdge(delay
));
150 Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt
)
152 DPRINTF(Bridge
, "recvTimingReq: %s addr 0x%x\n",
153 pkt
->cmdString(), pkt
->getAddr());
155 // ensure we do not have something waiting to retry
159 DPRINTF(Bridge
, "Response queue size: %d outresp: %d\n",
160 transmitList
.size(), outstandingResponses
);
162 if (masterPort
.reqQueueFull()) {
163 DPRINTF(Bridge
, "Request queue full\n");
165 } else if (pkt
->needsResponse()) {
166 if (respQueueFull()) {
167 DPRINTF(Bridge
, "Response queue full\n");
170 DPRINTF(Bridge
, "Reserving space for response\n");
171 assert(outstandingResponses
!= respQueueLimit
);
172 ++outstandingResponses
;
174 masterPort
.schedTimingReq(pkt
, bridge
.clockEdge(delay
));
178 // remember that we are now stalling a packet and that we have to
179 // tell the sending master to retry once space becomes available,
180 // we make no distinction whether the stalling is due to the
181 // request queue or response queue being full
186 Bridge::BridgeSlavePort::retryStalledReq()
189 DPRINTF(Bridge
, "Request waiting for retry, now retrying\n");
196 Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt
, Tick when
)
198 // If we expect to see a response, we need to restore the source
199 // and destination field that is potentially changed by a second
201 if (!pkt
->memInhibitAsserted() && pkt
->needsResponse()) {
202 // Update the sender state so we can deal with the response
204 RequestState
*req_state
= new RequestState(pkt
);
205 pkt
->senderState
= req_state
;
208 // If we're about to put this packet at the head of the queue, we
209 // need to schedule an event to do the transmit. Otherwise there
210 // should already be an event scheduled for sending the head
212 if (transmitList
.empty()) {
213 bridge
.schedule(sendEvent
, when
);
216 assert(transmitList
.size() != reqQueueLimit
);
218 transmitList
.push_back(DeferredPacket(pkt
, when
));
223 Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt
, Tick when
)
225 // This is a response for a request we forwarded earlier. The
226 // corresponding request state should be stored in the packet's
227 // senderState field.
228 RequestState
*req_state
= dynamic_cast<RequestState
*>(pkt
->senderState
);
229 assert(req_state
!= NULL
);
230 // set up new packet dest & senderState based on values saved
231 // from original request
232 req_state
->fixResponse(pkt
);
235 // the bridge assumes that at least one bus has set the
236 // destination field of the packet
237 assert(pkt
->isDestValid());
238 DPRINTF(Bridge
, "response, new dest %d\n", pkt
->getDest());
240 // If we're about to put this packet at the head of the queue, we
241 // need to schedule an event to do the transmit. Otherwise there
242 // should already be an event scheduled for sending the head
244 if (transmitList
.empty()) {
245 bridge
.schedule(sendEvent
, when
);
248 transmitList
.push_back(DeferredPacket(pkt
, when
));
252 Bridge::BridgeMasterPort::trySendTiming()
254 assert(!transmitList
.empty());
256 DeferredPacket req
= transmitList
.front();
258 assert(req
.tick
<= curTick());
260 PacketPtr pkt
= req
.pkt
;
262 DPRINTF(Bridge
, "trySend request addr 0x%x, queue size %d\n",
263 pkt
->getAddr(), transmitList
.size());
265 if (sendTimingReq(pkt
)) {
267 transmitList
.pop_front();
268 DPRINTF(Bridge
, "trySend request successful\n");
270 // If there are more packets to send, schedule event to try again.
271 if (!transmitList
.empty()) {
272 req
= transmitList
.front();
273 DPRINTF(Bridge
, "Scheduling next send\n");
274 bridge
.schedule(sendEvent
, std::max(req
.tick
,
275 bridge
.nextCycle()));
278 // if we have stalled a request due to a full request queue,
279 // then send a retry at this point, also note that if the
280 // request we stalled was waiting for the response queue
281 // rather than the request queue we might stall it again
282 slavePort
.retryStalledReq();
285 // if the send failed, then we try again once we receive a retry,
286 // and therefore there is no need to take any action
290 Bridge::BridgeSlavePort::trySendTiming()
292 assert(!transmitList
.empty());
294 DeferredPacket resp
= transmitList
.front();
296 assert(resp
.tick
<= curTick());
298 PacketPtr pkt
= resp
.pkt
;
300 DPRINTF(Bridge
, "trySend response addr 0x%x, outstanding %d\n",
301 pkt
->getAddr(), outstandingResponses
);
303 if (sendTimingResp(pkt
)) {
305 transmitList
.pop_front();
306 DPRINTF(Bridge
, "trySend response successful\n");
308 assert(outstandingResponses
!= 0);
309 --outstandingResponses
;
311 // If there are more packets to send, schedule event to try again.
312 if (!transmitList
.empty()) {
313 resp
= transmitList
.front();
314 DPRINTF(Bridge
, "Scheduling next send\n");
315 bridge
.schedule(sendEvent
, std::max(resp
.tick
,
316 bridge
.nextCycle()));
319 // if there is space in the request queue and we were stalling
320 // a request, it will definitely be possible to accept it now
321 // since there is guaranteed space in the response queue
322 if (!masterPort
.reqQueueFull() && retryReq
) {
323 DPRINTF(Bridge
, "Request waiting for retry, now retrying\n");
329 // if the send failed, then we try again once we receive a retry,
330 // and therefore there is no need to take any action
334 Bridge::BridgeMasterPort::recvRetry()
336 Tick nextReady
= transmitList
.front().tick
;
337 if (nextReady
<= curTick())
340 bridge
.schedule(sendEvent
, nextReady
);
344 Bridge::BridgeSlavePort::recvRetry()
346 Tick nextReady
= transmitList
.front().tick
;
347 if (nextReady
<= curTick())
350 bridge
.schedule(sendEvent
, nextReady
);
354 Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt
)
356 return delay
* bridge
.clockPeriod() + masterPort
.sendAtomic(pkt
);
360 Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt
)
362 std::list
<DeferredPacket
>::iterator i
;
364 pkt
->pushLabel(name());
366 // check the response queue
367 for (i
= transmitList
.begin(); i
!= transmitList
.end(); ++i
) {
368 if (pkt
->checkFunctional((*i
).pkt
)) {
374 // also check the master port's request queue
375 if (masterPort
.checkFunctional(pkt
)) {
381 // fall through if pkt still not satisfied
382 masterPort
.sendFunctional(pkt
);
386 Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt
)
389 std::list
<DeferredPacket
>::iterator i
= transmitList
.begin();
391 while(i
!= transmitList
.end() && !found
) {
392 if (pkt
->checkFunctional((*i
).pkt
)) {
403 Bridge::BridgeSlavePort::getAddrRanges() const
409 BridgeParams::create()
411 return new Bridge(this);