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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/BusBridge.hh"
53 #include "mem/bridge.hh"
54 #include "params/Bridge.hh"
56 Bridge::BridgeSlavePort::BridgeSlavePort(const std::string
&_name
,
58 BridgeMasterPort
& _masterPort
,
59 int _delay
, int _nack_delay
,
61 std::vector
<Range
<Addr
> > _ranges
)
62 : SlavePort(_name
, _bridge
), bridge(_bridge
), masterPort(_masterPort
),
63 delay(_delay
), nackDelay(_nack_delay
),
64 ranges(_ranges
.begin(), _ranges
.end()),
65 outstandingResponses(0), inRetry(false),
66 respQueueLimit(_resp_limit
), sendEvent(*this)
70 Bridge::BridgeMasterPort::BridgeMasterPort(const std::string
&_name
,
72 BridgeSlavePort
& _slavePort
,
73 int _delay
, int _req_limit
)
74 : MasterPort(_name
, _bridge
), bridge(_bridge
), slavePort(_slavePort
),
75 delay(_delay
), inRetry(false), reqQueueLimit(_req_limit
),
80 Bridge::Bridge(Params
*p
)
82 slavePort(p
->name
+ "-slave", this, masterPort
, p
->delay
,
83 p
->nack_delay
, p
->resp_size
, p
->ranges
),
84 masterPort(p
->name
+ "-master", this, slavePort
, p
->delay
, p
->req_size
),
85 ackWrites(p
->write_ack
), _params(p
)
88 panic("No support for acknowledging writes\n");
92 Bridge::getMasterPort(const std::string
&if_name
, int idx
)
94 if (if_name
== "master")
97 // pass it along to our super class
98 return MemObject::getMasterPort(if_name
, idx
);
102 Bridge::getSlavePort(const std::string
&if_name
, int idx
)
104 if (if_name
== "slave")
107 // pass it along to our super class
108 return MemObject::getSlavePort(if_name
, idx
);
114 // make sure both sides are connected and have the same block size
115 if (!slavePort
.isConnected() || !masterPort
.isConnected())
116 fatal("Both ports of bus bridge are not connected to a bus.\n");
118 if (slavePort
.peerBlockSize() != masterPort
.peerBlockSize())
119 fatal("Slave port size %d, master port size %d \n " \
120 "Busses don't have the same block size... Not supported.\n",
121 slavePort
.peerBlockSize(), masterPort
.peerBlockSize());
123 // notify the master side of our address ranges
124 slavePort
.sendRangeChange();
128 Bridge::BridgeSlavePort::respQueueFull()
130 return outstandingResponses
== respQueueLimit
;
134 Bridge::BridgeMasterPort::reqQueueFull()
136 return requestQueue
.size() == reqQueueLimit
;
140 Bridge::BridgeMasterPort::recvTiming(PacketPtr pkt
)
142 // should only see responses on the master side
143 assert(pkt
->isResponse());
145 // all checks are done when the request is accepted on the slave
146 // side, so we are guaranteed to have space for the response
148 DPRINTF(BusBridge
, "recvTiming: src %d dest %d addr 0x%x\n",
149 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr());
151 DPRINTF(BusBridge
, "Request queue size: %d\n", requestQueue
.size());
153 slavePort
.queueForSendTiming(pkt
);
159 Bridge::BridgeSlavePort::recvTiming(PacketPtr pkt
)
161 // should only see requests on the slave side
162 assert(pkt
->isRequest());
164 DPRINTF(BusBridge
, "recvTiming: src %d dest %d addr 0x%x\n",
165 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr());
167 DPRINTF(BusBridge
, "Response queue size: %d outresp: %d\n",
168 responseQueue
.size(), outstandingResponses
);
170 if (masterPort
.reqQueueFull()) {
171 DPRINTF(BusBridge
, "Request queue full, nacking\n");
176 if (pkt
->needsResponse()) {
177 if (respQueueFull()) {
179 "Response queue full, no space for response, nacking\n");
181 "queue size: %d outstanding resp: %d\n",
182 responseQueue
.size(), outstandingResponses
);
186 DPRINTF(BusBridge
, "Request Needs response, reserving space\n");
187 assert(outstandingResponses
!= respQueueLimit
);
188 ++outstandingResponses
;
192 masterPort
.queueForSendTiming(pkt
);
198 Bridge::BridgeSlavePort::nackRequest(PacketPtr pkt
)
201 pkt
->makeTimingResponse();
204 // The Nack packets are stored in the response queue just like any
205 // other response, but they do not occupy any space as this is
206 // tracked by the outstandingResponses, this guarantees space for
207 // the Nack packets, but implicitly means we have an (unrealistic)
208 // unbounded Nack queue.
210 // put it on the list to send
211 Tick readyTime
= curTick() + nackDelay
;
212 PacketBuffer
*buf
= new PacketBuffer(pkt
, readyTime
, true);
214 // nothing on the list, add it and we're done
215 if (responseQueue
.empty()) {
216 assert(!sendEvent
.scheduled());
217 bridge
->schedule(sendEvent
, readyTime
);
218 responseQueue
.push_back(buf
);
222 assert(sendEvent
.scheduled() || inRetry
);
224 // does it go at the end?
225 if (readyTime
>= responseQueue
.back()->ready
) {
226 responseQueue
.push_back(buf
);
230 // ok, somewhere in the middle, fun
231 std::list
<PacketBuffer
*>::iterator i
= responseQueue
.begin();
232 std::list
<PacketBuffer
*>::iterator end
= responseQueue
.end();
233 std::list
<PacketBuffer
*>::iterator begin
= responseQueue
.begin();
236 while (i
!= end
&& !done
) {
237 if (readyTime
< (*i
)->ready
) {
239 bridge
->reschedule(sendEvent
, readyTime
);
240 responseQueue
.insert(i
,buf
);
249 Bridge::BridgeMasterPort::queueForSendTiming(PacketPtr pkt
)
251 Tick readyTime
= curTick() + delay
;
252 PacketBuffer
*buf
= new PacketBuffer(pkt
, readyTime
);
254 // If we're about to put this packet at the head of the queue, we
255 // need to schedule an event to do the transmit. Otherwise there
256 // should already be an event scheduled for sending the head
258 if (requestQueue
.empty()) {
259 bridge
->schedule(sendEvent
, readyTime
);
262 assert(requestQueue
.size() != reqQueueLimit
);
264 requestQueue
.push_back(buf
);
269 Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt
)
271 // This is a response for a request we forwarded earlier. The
272 // corresponding PacketBuffer should be stored in the packet's
273 // senderState field.
274 PacketBuffer
*buf
= dynamic_cast<PacketBuffer
*>(pkt
->senderState
);
276 // set up new packet dest & senderState based on values saved
277 // from original request
278 buf
->fixResponse(pkt
);
280 DPRINTF(BusBridge
, "response, new dest %d\n", pkt
->getDest());
283 Tick readyTime
= curTick() + delay
;
284 buf
= new PacketBuffer(pkt
, readyTime
);
286 // If we're about to put this packet at the head of the queue, we
287 // need to schedule an event to do the transmit. Otherwise there
288 // should already be an event scheduled for sending the head
290 if (responseQueue
.empty()) {
291 bridge
->schedule(sendEvent
, readyTime
);
293 responseQueue
.push_back(buf
);
297 Bridge::BridgeMasterPort::trySend()
299 assert(!requestQueue
.empty());
301 PacketBuffer
*buf
= requestQueue
.front();
303 assert(buf
->ready
<= curTick());
305 PacketPtr pkt
= buf
->pkt
;
307 DPRINTF(BusBridge
, "trySend: origSrc %d dest %d addr 0x%x\n",
308 buf
->origSrc
, pkt
->getDest(), pkt
->getAddr());
310 // If the send was successful, make sure sender state was set to NULL
311 // otherwise we could get a NACK back of a packet that didn't expect a
312 // response and we would try to use freed memory.
314 Packet::SenderState
*old_sender_state
= pkt
->senderState
;
315 if (!buf
->expectResponse
)
316 pkt
->senderState
= NULL
;
318 if (sendTiming(pkt
)) {
320 requestQueue
.pop_front();
321 // we no longer own packet, so it's not safe to look at it
324 if (!buf
->expectResponse
) {
325 // no response expected... deallocate packet buffer now.
326 DPRINTF(BusBridge
, " successful: no response expected\n");
330 // If there are more packets to send, schedule event to try again.
331 if (!requestQueue
.empty()) {
332 buf
= requestQueue
.front();
333 DPRINTF(BusBridge
, "Scheduling next send\n");
334 bridge
->schedule(sendEvent
, std::max(buf
->ready
, curTick() + 1));
337 DPRINTF(BusBridge
, " unsuccessful\n");
338 pkt
->senderState
= old_sender_state
;
342 DPRINTF(BusBridge
, "trySend: request queue size: %d\n",
343 requestQueue
.size());
347 Bridge::BridgeSlavePort::trySend()
349 assert(!responseQueue
.empty());
351 PacketBuffer
*buf
= responseQueue
.front();
353 assert(buf
->ready
<= curTick());
355 PacketPtr pkt
= buf
->pkt
;
357 DPRINTF(BusBridge
, "trySend: origSrc %d dest %d addr 0x%x\n",
358 buf
->origSrc
, pkt
->getDest(), pkt
->getAddr());
360 bool was_nacked_here
= buf
->nackedHere
;
362 // no need to worry about the sender state since we are not
365 if (sendTiming(pkt
)) {
366 DPRINTF(BusBridge
, " successful\n");
368 responseQueue
.pop_front();
369 // this is a response... deallocate packet buffer now.
372 if (!was_nacked_here
) {
373 assert(outstandingResponses
!= 0);
374 --outstandingResponses
;
377 // If there are more packets to send, schedule event to try again.
378 if (!responseQueue
.empty()) {
379 buf
= responseQueue
.front();
380 DPRINTF(BusBridge
, "Scheduling next send\n");
381 bridge
->schedule(sendEvent
, std::max(buf
->ready
, curTick() + 1));
384 DPRINTF(BusBridge
, " unsuccessful\n");
388 DPRINTF(BusBridge
, "trySend: queue size: %d outstanding resp: %d\n",
389 responseQueue
.size(), outstandingResponses
);
393 Bridge::BridgeMasterPort::recvRetry()
396 Tick nextReady
= requestQueue
.front()->ready
;
397 if (nextReady
<= curTick())
400 bridge
->schedule(sendEvent
, nextReady
);
404 Bridge::BridgeSlavePort::recvRetry()
407 Tick nextReady
= responseQueue
.front()->ready
;
408 if (nextReady
<= curTick())
411 bridge
->schedule(sendEvent
, nextReady
);
415 Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt
)
417 return delay
+ masterPort
.sendAtomic(pkt
);
421 Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt
)
423 std::list
<PacketBuffer
*>::iterator i
;
425 pkt
->pushLabel(name());
427 // check the response queue
428 for (i
= responseQueue
.begin(); i
!= responseQueue
.end(); ++i
) {
429 if (pkt
->checkFunctional((*i
)->pkt
)) {
435 // also check the master port's request queue
436 if (masterPort
.checkFunctional(pkt
)) {
442 // fall through if pkt still not satisfied
443 masterPort
.sendFunctional(pkt
);
447 Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt
)
450 std::list
<PacketBuffer
*>::iterator i
= requestQueue
.begin();
452 while(i
!= requestQueue
.end() && !found
) {
453 if (pkt
->checkFunctional((*i
)->pkt
)) {
464 Bridge::BridgeSlavePort::getAddrRanges()
470 BridgeParams::create()
472 return new Bridge(this);