3 * Copyright (c) 2006 The Regents of The University of Michigan
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15 * this software without specific prior written permission.
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35 * Definition of a simple bus bridge without buffering.
40 #include "base/trace.hh"
41 #include "mem/bridge.hh"
42 #include "sim/builder.hh"
44 Bridge::BridgePort::BridgePort(const std::string
&_name
,
45 Bridge
*_bridge
, BridgePort
*_otherPort
,
46 int _delay
, int _nack_delay
, int _req_limit
,
47 int _resp_limit
, bool fix_partial_write
)
48 : Port(_name
), bridge(_bridge
), otherPort(_otherPort
),
49 delay(_delay
), nackDelay(_nack_delay
), fixPartialWrite(fix_partial_write
),
50 outstandingResponses(0), queuedRequests(0), inRetry(false),
51 reqQueueLimit(_req_limit
), respQueueLimit(_resp_limit
), sendEvent(this)
55 Bridge::Bridge(Params
*p
)
57 portA(p
->name
+ "-portA", this, &portB
, p
->delay
, p
->nack_delay
,
58 p
->req_size_a
, p
->resp_size_a
, p
->fix_partial_write_a
),
59 portB(p
->name
+ "-portB", this, &portA
, p
->delay
, p
->nack_delay
,
60 p
->req_size_b
, p
->resp_size_b
, p
->fix_partial_write_b
),
61 ackWrites(p
->write_ack
), _params(p
)
64 panic("No support for acknowledging writes\n");
68 Bridge::getPort(const std::string
&if_name
, int idx
)
72 if (if_name
== "side_a")
74 else if (if_name
== "side_b")
79 if (port
->getPeer() != NULL
)
80 panic("bridge side %s already connected to.", if_name
);
88 // Make sure that both sides are connected to.
89 if (portA
.getPeer() == NULL
|| portB
.getPeer() == NULL
)
90 fatal("Both ports of bus bridge are not connected to a bus.\n");
92 if (portA
.peerBlockSize() != portB
.peerBlockSize())
93 fatal("Busses don't have the same block size... Not supported.\n");
97 Bridge::BridgePort::respQueueFull()
99 assert(outstandingResponses
>= 0 && outstandingResponses
<= respQueueLimit
);
100 return outstandingResponses
>= respQueueLimit
;
104 Bridge::BridgePort::reqQueueFull()
106 assert(queuedRequests
>= 0 && queuedRequests
<= reqQueueLimit
);
107 return queuedRequests
>= reqQueueLimit
;
110 /** Function called by the port when the bus is receiving a Timing
113 Bridge::BridgePort::recvTiming(PacketPtr pkt
)
115 DPRINTF(BusBridge
, "recvTiming: src %d dest %d addr 0x%x\n",
116 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr());
118 DPRINTF(BusBridge
, "Local queue size: %d outreq: %d outresp: %d\n",
119 sendQueue
.size(), queuedRequests
, outstandingResponses
);
120 DPRINTF(BusBridge
, "Remove queue size: %d outreq: %d outresp: %d\n",
121 otherPort
->sendQueue
.size(), otherPort
->queuedRequests
,
122 otherPort
->outstandingResponses
);
124 if (pkt
->isRequest() && otherPort
->reqQueueFull() && !pkt
->wasNacked()) {
125 DPRINTF(BusBridge
, "Remote queue full, nacking\n");
130 if (pkt
->needsResponse() && !pkt
->wasNacked())
131 if (respQueueFull()) {
132 DPRINTF(BusBridge
, "Local queue full, no space for response, nacking\n");
133 DPRINTF(BusBridge
, "queue size: %d outreq: %d outstanding resp: %d\n",
134 sendQueue
.size(), queuedRequests
, outstandingResponses
);
138 DPRINTF(BusBridge
, "Request Needs response, reserving space\n");
139 ++outstandingResponses
;
142 otherPort
->queueForSendTiming(pkt
);
148 Bridge::BridgePort::nackRequest(PacketPtr pkt
)
152 pkt
->setDest(pkt
->getSrc());
154 //put it on the list to send
155 Tick readyTime
= curTick
+ nackDelay
;
156 PacketBuffer
*buf
= new PacketBuffer(pkt
, readyTime
, true);
158 // nothing on the list, add it and we're done
159 if (sendQueue
.empty()) {
160 assert(!sendEvent
.scheduled());
161 sendEvent
.schedule(readyTime
);
162 sendQueue
.push_back(buf
);
166 assert(sendEvent
.scheduled() || inRetry
);
168 // does it go at the end?
169 if (readyTime
>= sendQueue
.back()->ready
) {
170 sendQueue
.push_back(buf
);
174 // ok, somewhere in the middle, fun
175 std::list
<PacketBuffer
*>::iterator i
= sendQueue
.begin();
176 std::list
<PacketBuffer
*>::iterator end
= sendQueue
.end();
177 std::list
<PacketBuffer
*>::iterator begin
= sendQueue
.begin();
180 while (i
!= end
&& !done
) {
181 if (readyTime
< (*i
)->ready
) {
183 sendEvent
.reschedule(readyTime
);
184 sendQueue
.insert(i
,buf
);
194 Bridge::BridgePort::queueForSendTiming(PacketPtr pkt
)
196 if (pkt
->isResponse() || pkt
->wasNacked()) {
197 // This is a response for a request we forwarded earlier. The
198 // corresponding PacketBuffer should be stored in the packet's
199 // senderState field.
200 PacketBuffer
*buf
= dynamic_cast<PacketBuffer
*>(pkt
->senderState
);
202 // set up new packet dest & senderState based on values saved
203 // from original request
204 buf
->fixResponse(pkt
);
206 // Check if this packet was expecting a response and it's a nacked
207 // packet, in which case we will never being seeing it
208 if (buf
->expectResponse
&& pkt
->wasNacked())
209 --outstandingResponses
;
211 DPRINTF(BusBridge
, "response, new dest %d\n", pkt
->getDest());
216 if (pkt
->isRequest() && !pkt
->wasNacked()) {
222 Tick readyTime
= curTick
+ delay
;
223 PacketBuffer
*buf
= new PacketBuffer(pkt
, readyTime
);
225 // If we're about to put this packet at the head of the queue, we
226 // need to schedule an event to do the transmit. Otherwise there
227 // should already be an event scheduled for sending the head
229 if (sendQueue
.empty()) {
230 sendEvent
.schedule(readyTime
);
232 sendQueue
.push_back(buf
);
236 Bridge::BridgePort::trySend()
238 assert(!sendQueue
.empty());
240 PacketBuffer
*buf
= sendQueue
.front();
242 assert(buf
->ready
<= curTick
);
244 PacketPtr pkt
= buf
->pkt
;
246 // Ugly! @todo When multilevel coherence works this will be removed
247 if (pkt
->cmd
== MemCmd::WriteInvalidateReq
&& fixPartialWrite
&&
249 PacketPtr funcPkt
= new Packet(pkt
->req
, MemCmd::WriteReq
,
251 funcPkt
->dataStatic(pkt
->getPtr
<uint8_t>());
252 sendFunctional(funcPkt
);
253 pkt
->cmd
= MemCmd::WriteReq
;
257 DPRINTF(BusBridge
, "trySend: origSrc %d dest %d addr 0x%x\n",
258 buf
->origSrc
, pkt
->getDest(), pkt
->getAddr());
260 bool wasReq
= pkt
->isRequest();
261 bool wasNacked
= pkt
->wasNacked();
263 if (sendTiming(pkt
)) {
265 sendQueue
.pop_front();
266 buf
->pkt
= NULL
; // we no longer own packet, so it's not safe to look at it
268 if (buf
->expectResponse
) {
269 // Must wait for response
270 DPRINTF(BusBridge
, " successful: awaiting response (%d)\n",
271 outstandingResponses
);
273 // no response expected... deallocate packet buffer now.
274 DPRINTF(BusBridge
, " successful: no response expected\n");
282 --outstandingResponses
;
285 // If there are more packets to send, schedule event to try again.
286 if (!sendQueue
.empty()) {
287 buf
= sendQueue
.front();
288 DPRINTF(BusBridge
, "Scheduling next send\n");
289 sendEvent
.schedule(std::max(buf
->ready
, curTick
+ 1));
292 DPRINTF(BusBridge
, " unsuccessful\n");
295 DPRINTF(BusBridge
, "trySend: queue size: %d outreq: %d outstanding resp: %d\n",
296 sendQueue
.size(), queuedRequests
, outstandingResponses
);
301 Bridge::BridgePort::recvRetry()
304 Tick nextReady
= sendQueue
.front()->ready
;
305 if (nextReady
<= curTick
)
308 sendEvent
.schedule(nextReady
);
311 /** Function called by the port when the bus is receiving a Atomic
314 Bridge::BridgePort::recvAtomic(PacketPtr pkt
)
316 // fix partial atomic writes... similar to the timing code that does the
317 // same... will be removed once our code gets this right
318 if (pkt
->cmd
== MemCmd::WriteInvalidateReq
&& fixPartialWrite
) {
320 PacketPtr funcPkt
= new Packet(pkt
->req
, MemCmd::WriteReq
,
322 funcPkt
->dataStatic(pkt
->getPtr
<uint8_t>());
323 otherPort
->sendFunctional(funcPkt
);
325 pkt
->cmd
= MemCmd::WriteReq
;
327 return delay
+ otherPort
->sendAtomic(pkt
);
330 /** Function called by the port when the bus is receiving a Functional
333 Bridge::BridgePort::recvFunctional(PacketPtr pkt
)
335 std::list
<PacketBuffer
*>::iterator i
;
337 for (i
= sendQueue
.begin(); i
!= sendQueue
.end(); ++i
) {
338 if (pkt
->checkFunctional((*i
)->pkt
))
342 // fall through if pkt still not satisfied
343 otherPort
->sendFunctional(pkt
);
346 /** Function called by the port when the bus is receiving a status change.*/
348 Bridge::BridgePort::recvStatusChange(Port::Status status
)
350 otherPort
->sendStatusChange(status
);
354 Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList
&resp
,
357 otherPort
->getPeerAddressRanges(resp
, snoop
);
358 // we don't allow snooping across bridges
362 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge
)
364 Param
<int> req_size_a
;
365 Param
<int> req_size_b
;
366 Param
<int> resp_size_a
;
367 Param
<int> resp_size_b
;
369 Param
<Tick
> nack_delay
;
370 Param
<bool> write_ack
;
371 Param
<bool> fix_partial_write_a
;
372 Param
<bool> fix_partial_write_b
;
374 END_DECLARE_SIM_OBJECT_PARAMS(Bridge
)
376 BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge
)
378 INIT_PARAM(req_size_a
, "The size of the queue for requests coming into side a"),
379 INIT_PARAM(req_size_b
, "The size of the queue for requests coming into side b"),
380 INIT_PARAM(resp_size_a
, "The size of the queue for responses coming into side a"),
381 INIT_PARAM(resp_size_b
, "The size of the queue for responses coming into side b"),
382 INIT_PARAM(delay
, "The miminum delay to cross this bridge"),
383 INIT_PARAM(nack_delay
, "The minimum delay to nack a packet"),
384 INIT_PARAM(write_ack
, "Acknowledge any writes that are received."),
385 INIT_PARAM(fix_partial_write_a
, "Fixup any partial block writes that are received"),
386 INIT_PARAM(fix_partial_write_b
, "Fixup any partial block writes that are received")
388 END_INIT_SIM_OBJECT_PARAMS(Bridge
)
390 CREATE_SIM_OBJECT(Bridge
)
392 Bridge::Params
*p
= new Bridge::Params
;
393 p
->name
= getInstanceName();
394 p
->req_size_a
= req_size_a
;
395 p
->req_size_b
= req_size_b
;
396 p
->resp_size_a
= resp_size_a
;
397 p
->resp_size_b
= resp_size_b
;
399 p
->nack_delay
= nack_delay
;
400 p
->write_ack
= write_ack
;
401 p
->fix_partial_write_a
= fix_partial_write_a
;
402 p
->fix_partial_write_b
= fix_partial_write_b
;
403 return new Bridge(p
);
406 REGISTER_SIM_OBJECT("Bridge", Bridge
)