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47 * Definition of a bus object.
50 #include "base/misc.hh"
51 #include "base/trace.hh"
52 #include "debug/BusAddrRanges.hh"
53 #include "debug/CoherentBus.hh"
54 #include "mem/coherent_bus.hh"
56 CoherentBus::CoherentBus(const CoherentBusParams
*p
)
57 : BaseBus(p
), reqLayer(*this, ".reqLayer", p
->clock
),
58 respLayer(*this, ".respLayer", p
->clock
),
59 snoopRespLayer(*this, ".snoopRespLayer", p
->clock
)
61 // create the ports based on the size of the master and slave
62 // vector ports, and the presence of the default port, the ports
63 // are enumerated starting from zero
64 for (int i
= 0; i
< p
->port_master_connection_count
; ++i
) {
65 std::string portName
= csprintf("%s-p%d", name(), i
);
66 MasterPort
* bp
= new CoherentBusMasterPort(portName
, *this, i
);
67 masterPorts
.push_back(bp
);
70 // see if we have a default slave device connected and if so add
71 // our corresponding master port
72 if (p
->port_default_connection_count
) {
73 defaultPortID
= masterPorts
.size();
74 std::string portName
= csprintf("%s-default", name());
75 MasterPort
* bp
= new CoherentBusMasterPort(portName
, *this,
77 masterPorts
.push_back(bp
);
80 // create the slave ports, once again starting at zero
81 for (int i
= 0; i
< p
->port_slave_connection_count
; ++i
) {
82 std::string portName
= csprintf("%s-p%d", name(), i
);
83 SlavePort
* bp
= new CoherentBusSlavePort(portName
, *this, i
);
84 slavePorts
.push_back(bp
);
93 // iterate over our slave ports and determine which of our
94 // neighbouring master ports are snooping and add them as snoopers
95 for (SlavePortConstIter p
= slavePorts
.begin(); p
!= slavePorts
.end();
97 // check if the connected master port is snooping
98 if ((*p
)->isSnooping()) {
99 DPRINTF(BusAddrRanges
, "Adding snooping master %s\n",
100 (*p
)->getMasterPort().name());
101 snoopPorts
.push_back(*p
);
105 if (snoopPorts
.empty())
106 warn("CoherentBus %s has no snooping ports attached!\n", name());
110 CoherentBus::recvTimingReq(PacketPtr pkt
, PortID slave_port_id
)
112 // determine the source port based on the id
113 SlavePort
*src_port
= slavePorts
[slave_port_id
];
115 // remember if the packet is an express snoop
116 bool is_express_snoop
= pkt
->isExpressSnoop();
118 // test if the bus should be considered occupied for the current
119 // port, and exclude express snoops from the check
120 if (!is_express_snoop
&& !reqLayer
.tryTiming(src_port
)) {
121 DPRINTF(CoherentBus
, "recvTimingReq: src %s %s 0x%x BUSY\n",
122 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
126 DPRINTF(CoherentBus
, "recvTimingReq: src %s %s expr %d 0x%x\n",
127 src_port
->name(), pkt
->cmdString(), is_express_snoop
,
130 // set the source port for routing of the response
131 pkt
->setSrc(slave_port_id
);
133 Tick headerFinishTime
= is_express_snoop
? 0 : calcPacketTiming(pkt
);
134 Tick packetFinishTime
= is_express_snoop
? 0 : pkt
->finishTime
;
136 // uncacheable requests need never be snooped
137 if (!pkt
->req
->isUncacheable()) {
138 // the packet is a memory-mapped request and should be
139 // broadcasted to our snoopers but the source
140 forwardTiming(pkt
, slave_port_id
);
143 // remember if we add an outstanding req so we can undo it if
144 // necessary, if the packet needs a response, we should add it
145 // as outstanding and express snoops never fail so there is
146 // not need to worry about them
147 bool add_outstanding
= !is_express_snoop
&& pkt
->needsResponse();
149 // keep track that we have an outstanding request packet
150 // matching this request, this is used by the coherency
151 // mechanism in determining what to do with snoop responses
152 // (in recvTimingSnoop)
153 if (add_outstanding
) {
154 // we should never have an exsiting request outstanding
155 assert(outstandingReq
.find(pkt
->req
) == outstandingReq
.end());
156 outstandingReq
.insert(pkt
->req
);
159 // since it is a normal request, determine the destination
160 // based on the address and attempt to send the packet
161 bool success
= masterPorts
[findPort(pkt
->getAddr())]->sendTimingReq(pkt
);
163 // if this is an express snoop, we are done at this point
164 if (is_express_snoop
) {
167 // for normal requests, check if successful
169 // inhibited packets should never be forced to retry
170 assert(!pkt
->memInhibitAsserted());
172 // if it was added as outstanding and the send failed, then
175 outstandingReq
.erase(pkt
->req
);
177 DPRINTF(CoherentBus
, "recvTimingReq: src %s %s 0x%x RETRY\n",
178 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
180 // update the bus state and schedule an idle event
181 reqLayer
.failedTiming(src_port
, headerFinishTime
);
183 // update the bus state and schedule an idle event
184 reqLayer
.succeededTiming(packetFinishTime
);
192 CoherentBus::recvTimingResp(PacketPtr pkt
, PortID master_port_id
)
194 // determine the source port based on the id
195 MasterPort
*src_port
= masterPorts
[master_port_id
];
197 // test if the bus should be considered occupied for the current
199 if (!respLayer
.tryTiming(src_port
)) {
200 DPRINTF(CoherentBus
, "recvTimingResp: src %s %s 0x%x BUSY\n",
201 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
205 DPRINTF(CoherentBus
, "recvTimingResp: src %s %s 0x%x\n",
206 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
208 calcPacketTiming(pkt
);
209 Tick packetFinishTime
= pkt
->finishTime
;
211 // the packet is a normal response to a request that we should
212 // have seen passing through the bus
213 assert(outstandingReq
.find(pkt
->req
) != outstandingReq
.end());
215 // remove it as outstanding
216 outstandingReq
.erase(pkt
->req
);
218 // send the packet to the destination through one of our slave
219 // ports, as determined by the destination field
220 bool success M5_VAR_USED
= slavePorts
[pkt
->getDest()]->sendTimingResp(pkt
);
222 // currently it is illegal to block responses... can lead to
226 respLayer
.succeededTiming(packetFinishTime
);
232 CoherentBus::recvTimingSnoopReq(PacketPtr pkt
, PortID master_port_id
)
234 DPRINTF(CoherentBus
, "recvTimingSnoopReq: src %s %s 0x%x\n",
235 masterPorts
[master_port_id
]->name(), pkt
->cmdString(),
238 // we should only see express snoops from caches
239 assert(pkt
->isExpressSnoop());
241 // set the source port for routing of the response
242 pkt
->setSrc(master_port_id
);
244 // forward to all snoopers
245 forwardTiming(pkt
, InvalidPortID
);
247 // a snoop request came from a connected slave device (one of
248 // our master ports), and if it is not coming from the slave
249 // device responsible for the address range something is
250 // wrong, hence there is nothing further to do as the packet
251 // would be going back to where it came from
252 assert(master_port_id
== findPort(pkt
->getAddr()));
256 CoherentBus::recvTimingSnoopResp(PacketPtr pkt
, PortID slave_port_id
)
258 // determine the source port based on the id
259 SlavePort
* src_port
= slavePorts
[slave_port_id
];
261 // test if the bus should be considered occupied for the current
263 if (!snoopRespLayer
.tryTiming(src_port
)) {
264 DPRINTF(CoherentBus
, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n",
265 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
269 DPRINTF(CoherentBus
, "recvTimingSnoop: src %s %s 0x%x\n",
270 src_port
->name(), pkt
->cmdString(), pkt
->getAddr());
272 // get the destination from the packet
273 PortID dest
= pkt
->getDest();
275 // responses are never express snoops
276 assert(!pkt
->isExpressSnoop());
278 calcPacketTiming(pkt
);
279 Tick packetFinishTime
= pkt
->finishTime
;
281 // determine if the response is from a snoop request we
282 // created as the result of a normal request (in which case it
283 // should be in the outstandingReq), or if we merely forwarded
284 // someone else's snoop request
285 if (outstandingReq
.find(pkt
->req
) == outstandingReq
.end()) {
286 // this is a snoop response to a snoop request we
287 // forwarded, e.g. coming from the L1 and going to the L2
288 // this should be forwarded as a snoop response
289 bool success M5_VAR_USED
= masterPorts
[dest
]->sendTimingSnoopResp(pkt
);
292 // we got a snoop response on one of our slave ports,
293 // i.e. from a coherent master connected to the bus, and
294 // since we created the snoop request as part of
295 // recvTiming, this should now be a normal response again
296 outstandingReq
.erase(pkt
->req
);
298 // this is a snoop response from a coherent master, with a
299 // destination field set on its way through the bus as
300 // request, hence it should never go back to where the
301 // snoop response came from, but instead to where the
302 // original request came from
303 assert(slave_port_id
!= dest
);
305 // as a normal response, it should go back to a master
306 // through one of our slave ports
307 bool success M5_VAR_USED
= slavePorts
[dest
]->sendTimingResp(pkt
);
309 // currently it is illegal to block responses... can lead
314 snoopRespLayer
.succeededTiming(packetFinishTime
);
321 CoherentBus::forwardTiming(PacketPtr pkt
, PortID exclude_slave_port_id
)
323 for (SlavePortIter s
= snoopPorts
.begin(); s
!= snoopPorts
.end(); ++s
) {
325 // we could have gotten this request from a snooping master
326 // (corresponding to our own slave port that is also in
327 // snoopPorts) and should not send it back to where it came
329 if (exclude_slave_port_id
== InvalidPortID
||
330 p
->getId() != exclude_slave_port_id
) {
331 // cache is not allowed to refuse snoop
332 p
->sendTimingSnoopReq(pkt
);
338 CoherentBus::recvRetry()
340 // responses and snoop responses never block on forwarding them,
341 // so the retry will always be coming from a port to which we
342 // tried to forward a request
343 reqLayer
.recvRetry();
347 CoherentBus::recvAtomic(PacketPtr pkt
, PortID slave_port_id
)
349 DPRINTF(CoherentBus
, "recvAtomic: packet src %s addr 0x%x cmd %s\n",
350 slavePorts
[slave_port_id
]->name(), pkt
->getAddr(),
353 MemCmd snoop_response_cmd
= MemCmd::InvalidCmd
;
354 Tick snoop_response_latency
= 0;
356 // uncacheable requests need never be snooped
357 if (!pkt
->req
->isUncacheable()) {
358 // forward to all snoopers but the source
359 std::pair
<MemCmd
, Tick
> snoop_result
=
360 forwardAtomic(pkt
, slave_port_id
);
361 snoop_response_cmd
= snoop_result
.first
;
362 snoop_response_latency
= snoop_result
.second
;
365 // even if we had a snoop response, we must continue and also
366 // perform the actual request at the destination
367 PortID dest_id
= findPort(pkt
->getAddr());
369 // forward the request to the appropriate destination
370 Tick response_latency
= masterPorts
[dest_id
]->sendAtomic(pkt
);
372 // if we got a response from a snooper, restore it here
373 if (snoop_response_cmd
!= MemCmd::InvalidCmd
) {
374 // no one else should have responded
375 assert(!pkt
->isResponse());
376 pkt
->cmd
= snoop_response_cmd
;
377 response_latency
= snoop_response_latency
;
380 pkt
->finishTime
= curTick() + response_latency
;
381 return response_latency
;
385 CoherentBus::recvAtomicSnoop(PacketPtr pkt
, PortID master_port_id
)
387 DPRINTF(CoherentBus
, "recvAtomicSnoop: packet src %s addr 0x%x cmd %s\n",
388 masterPorts
[master_port_id
]->name(), pkt
->getAddr(),
391 // forward to all snoopers
392 std::pair
<MemCmd
, Tick
> snoop_result
=
393 forwardAtomic(pkt
, InvalidPortID
);
394 MemCmd snoop_response_cmd
= snoop_result
.first
;
395 Tick snoop_response_latency
= snoop_result
.second
;
397 if (snoop_response_cmd
!= MemCmd::InvalidCmd
)
398 pkt
->cmd
= snoop_response_cmd
;
400 pkt
->finishTime
= curTick() + snoop_response_latency
;
401 return snoop_response_latency
;
404 std::pair
<MemCmd
, Tick
>
405 CoherentBus::forwardAtomic(PacketPtr pkt
, PortID exclude_slave_port_id
)
407 // the packet may be changed on snoops, record the original
408 // command to enable us to restore it between snoops so that
409 // additional snoops can take place properly
410 MemCmd orig_cmd
= pkt
->cmd
;
411 MemCmd snoop_response_cmd
= MemCmd::InvalidCmd
;
412 Tick snoop_response_latency
= 0;
414 for (SlavePortIter s
= snoopPorts
.begin(); s
!= snoopPorts
.end(); ++s
) {
416 // we could have gotten this request from a snooping master
417 // (corresponding to our own slave port that is also in
418 // snoopPorts) and should not send it back to where it came
420 if (exclude_slave_port_id
== InvalidPortID
||
421 p
->getId() != exclude_slave_port_id
) {
422 Tick latency
= p
->sendAtomicSnoop(pkt
);
423 // in contrast to a functional access, we have to keep on
424 // going as all snoopers must be updated even if we get a
426 if (pkt
->isResponse()) {
427 // response from snoop agent
428 assert(pkt
->cmd
!= orig_cmd
);
429 assert(pkt
->memInhibitAsserted());
430 // should only happen once
431 assert(snoop_response_cmd
== MemCmd::InvalidCmd
);
432 // save response state
433 snoop_response_cmd
= pkt
->cmd
;
434 snoop_response_latency
= latency
;
435 // restore original packet state for remaining snoopers
441 // the packet is restored as part of the loop and any potential
442 // snoop response is part of the returned pair
443 return std::make_pair(snoop_response_cmd
, snoop_response_latency
);
447 CoherentBus::recvFunctional(PacketPtr pkt
, PortID slave_port_id
)
449 if (!pkt
->isPrint()) {
450 // don't do DPRINTFs on PrintReq as it clutters up the output
452 "recvFunctional: packet src %s addr 0x%x cmd %s\n",
453 slavePorts
[slave_port_id
]->name(), pkt
->getAddr(),
457 // uncacheable requests need never be snooped
458 if (!pkt
->req
->isUncacheable()) {
459 // forward to all snoopers but the source
460 forwardFunctional(pkt
, slave_port_id
);
463 // there is no need to continue if the snooping has found what we
464 // were looking for and the packet is already a response
465 if (!pkt
->isResponse()) {
466 PortID dest_id
= findPort(pkt
->getAddr());
468 masterPorts
[dest_id
]->sendFunctional(pkt
);
473 CoherentBus::recvFunctionalSnoop(PacketPtr pkt
, PortID master_port_id
)
475 if (!pkt
->isPrint()) {
476 // don't do DPRINTFs on PrintReq as it clutters up the output
478 "recvFunctionalSnoop: packet src %s addr 0x%x cmd %s\n",
479 masterPorts
[master_port_id
]->name(), pkt
->getAddr(),
483 // forward to all snoopers
484 forwardFunctional(pkt
, InvalidPortID
);
488 CoherentBus::forwardFunctional(PacketPtr pkt
, PortID exclude_slave_port_id
)
490 for (SlavePortIter s
= snoopPorts
.begin(); s
!= snoopPorts
.end(); ++s
) {
492 // we could have gotten this request from a snooping master
493 // (corresponding to our own slave port that is also in
494 // snoopPorts) and should not send it back to where it came
496 if (exclude_slave_port_id
== InvalidPortID
||
497 p
->getId() != exclude_slave_port_id
)
498 p
->sendFunctionalSnoop(pkt
);
500 // if we get a response we are done
501 if (pkt
->isResponse()) {
508 CoherentBus::drain(Event
*de
)
510 // sum up the individual layers
511 return reqLayer
.drain(de
) + respLayer
.drain(de
) + snoopRespLayer
.drain(de
);
515 CoherentBusParams::create()
517 return new CoherentBus(this);