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47 * Definition of a bus object.
50 #include "base/misc.hh"
51 #include "base/trace.hh"
52 #include "debug/Bus.hh"
53 #include "debug/BusAddrRanges.hh"
54 #include "debug/Drain.hh"
57 BaseBus::BaseBus(const BaseBusParams
*p
)
59 headerCycles(p
->header_cycles
), width(p
->width
),
60 gotAddrRanges(p
->port_default_connection_count
+
61 p
->port_master_connection_count
, false),
62 gotAllAddrRanges(false), defaultPortID(InvalidPortID
),
63 useDefaultRange(p
->use_default_range
),
64 blockSize(p
->block_size
)
69 for (MasterPortIter m
= masterPorts
.begin(); m
!= masterPorts
.end();
74 for (SlavePortIter s
= slavePorts
.begin(); s
!= slavePorts
.end();
83 // determine the maximum peer block size, look at both the
84 // connected master and slave modules
85 uint32_t peer_block_size
= 0;
87 for (MasterPortConstIter m
= masterPorts
.begin(); m
!= masterPorts
.end();
89 peer_block_size
= std::max((*m
)->peerBlockSize(), peer_block_size
);
92 for (SlavePortConstIter s
= slavePorts
.begin(); s
!= slavePorts
.end();
94 peer_block_size
= std::max((*s
)->peerBlockSize(), peer_block_size
);
97 // if the peers do not have a block size, use the default value
98 // set through the bus parameters
99 if (peer_block_size
!= 0)
100 blockSize
= peer_block_size
;
102 // check if the block size is a value known to work
103 if (!(blockSize
== 16 || blockSize
== 32 || blockSize
== 64 ||
105 warn_once("Block size is neither 16, 32, 64 or 128 bytes.\n");
109 BaseBus::getMasterPort(const std::string
&if_name
, PortID idx
)
111 if (if_name
== "master" && idx
< masterPorts
.size()) {
112 // the master port index translates directly to the vector position
113 return *masterPorts
[idx
];
114 } else if (if_name
== "default") {
115 return *masterPorts
[defaultPortID
];
117 return MemObject::getMasterPort(if_name
, idx
);
122 BaseBus::getSlavePort(const std::string
&if_name
, PortID idx
)
124 if (if_name
== "slave" && idx
< slavePorts
.size()) {
125 // the slave port index translates directly to the vector position
126 return *slavePorts
[idx
];
128 return MemObject::getSlavePort(if_name
, idx
);
133 BaseBus::calcPacketTiming(PacketPtr pkt
)
135 // the bus will be called at a time that is not necessarily
136 // coinciding with its own clock, so start by determining how long
137 // until the next clock edge (could be zero)
138 Tick offset
= nextCycle() - curTick();
140 // determine how many cycles are needed to send the data
141 unsigned dataCycles
= pkt
->hasData() ? divCeil(pkt
->getSize(), width
) : 0;
143 // before setting the bus delay fields of the packet, ensure that
144 // the delay from any previous bus has been accounted for
145 if (pkt
->busFirstWordDelay
!= 0 || pkt
->busLastWordDelay
!= 0)
146 panic("Packet %s already has bus delay (%d, %d) that should be "
147 "accounted for.\n", pkt
->cmdString(), pkt
->busFirstWordDelay
,
148 pkt
->busLastWordDelay
);
150 // The first word will be delivered on the cycle after the header.
151 pkt
->busFirstWordDelay
= (headerCycles
+ 1) * clockPeriod() + offset
;
153 // Note that currently busLastWordDelay can be smaller than
154 // busFirstWordDelay if the packet has no data
155 pkt
->busLastWordDelay
= (headerCycles
+ dataCycles
) * clockPeriod() +
159 template <typename PortClass
>
160 BaseBus::Layer
<PortClass
>::Layer(BaseBus
& _bus
, const std::string
& _name
) :
162 bus(_bus
), _name(_name
), state(IDLE
), drainManager(NULL
),
167 template <typename PortClass
>
168 void BaseBus::Layer
<PortClass
>::occupyLayer(Tick until
)
170 // ensure the state is busy or in retry and never idle at this
171 // point, as the bus should transition from idle as soon as it has
172 // decided to forward the packet to prevent any follow-on calls to
173 // sendTiming seeing an unoccupied bus
174 assert(state
!= IDLE
);
176 // note that we do not change the bus state here, if we are going
177 // from idle to busy it is handled by tryTiming, and if we
178 // are in retry we should remain in retry such that
179 // succeededTiming still sees the accurate state
181 // until should never be 0 as express snoops never occupy the bus
183 bus
.schedule(releaseEvent
, until
);
185 DPRINTF(BaseBus
, "The bus is now busy from tick %d to %d\n",
189 template <typename PortClass
>
191 BaseBus::Layer
<PortClass
>::tryTiming(PortClass
* port
)
193 // first we see if the bus is busy, next we check if we are in a
194 // retry with a port other than the current one
195 if (state
== BUSY
|| (state
== RETRY
&& port
!= retryList
.front())) {
196 // put the port at the end of the retry list
197 retryList
.push_back(port
);
201 // update the state which is shared for request, response and
202 // snoop responses, if we were idle we are now busy, if we are in
203 // a retry, then do not change
210 template <typename PortClass
>
212 BaseBus::Layer
<PortClass
>::succeededTiming(Tick busy_time
)
214 // if a retrying port succeeded, also take it off the retry list
215 if (state
== RETRY
) {
216 DPRINTF(BaseBus
, "Remove retry from list %s\n",
217 retryList
.front()->name());
218 retryList
.pop_front();
222 // we should either have gone from idle to busy in the
223 // tryTiming test, or just gone from a retry to busy
224 assert(state
== BUSY
);
226 // occupy the bus accordingly
227 occupyLayer(busy_time
);
230 template <typename PortClass
>
232 BaseBus::Layer
<PortClass
>::failedTiming(PortClass
* port
, Tick busy_time
)
234 // if we are not in a retry, i.e. busy (but never idle), or we are
235 // in a retry but not for the current port, then add the port at
236 // the end of the retry list
237 if (state
!= RETRY
|| port
!= retryList
.front()) {
238 retryList
.push_back(port
);
241 // even if we retried the current one and did not succeed,
242 // we are no longer retrying but instead busy
245 // occupy the bus accordingly
246 occupyLayer(busy_time
);
249 template <typename PortClass
>
251 BaseBus::Layer
<PortClass
>::releaseLayer()
253 // releasing the bus means we should now be idle
254 assert(state
== BUSY
);
255 assert(!releaseEvent
.scheduled());
260 // bus is now idle, so if someone is waiting we can retry
261 if (!retryList
.empty()) {
262 // note that we block (return false on recvTiming) both
263 // because the bus is busy and because the destination is
264 // busy, and in the latter case the bus may be released before
265 // we see a retry from the destination
267 } else if (drainManager
) {
268 DPRINTF(Drain
, "Bus done draining, signaling drain manager\n");
269 //If we weren't able to drain before, do it now.
270 drainManager
->signalDrainDone();
271 // Clear the drain event once we're done with it.
276 template <typename PortClass
>
278 BaseBus::Layer
<PortClass
>::retryWaiting()
280 // this should never be called with an empty retry list
281 assert(!retryList
.empty());
283 // we always go to retrying from idle
284 assert(state
== IDLE
);
286 // update the state which is shared for request, response and
290 // note that we might have blocked on the receiving port being
291 // busy (rather than the bus itself) and now call retry before the
292 // destination called retry on the bus
293 retryList
.front()->sendRetry();
295 // If the bus is still in the retry state, sendTiming wasn't
296 // called in zero time (e.g. the cache does this)
297 if (state
== RETRY
) {
298 retryList
.pop_front();
300 //Burn a cycle for the missed grant.
302 // update the state which is shared for request, response and
306 // occupy the bus layer until the next cycle ends
307 occupyLayer(bus
.clockEdge(Cycles(1)));
311 template <typename PortClass
>
313 BaseBus::Layer
<PortClass
>::recvRetry()
315 // we got a retry from a peer that we tried to send something to
316 // and failed, but we sent it on the account of someone else, and
317 // that source port should be on our retry list, however if the
318 // bus layer is released before this happens and the retry (from
319 // the bus point of view) is successful then this no longer holds
320 // and we could in fact have an empty retry list
321 if (retryList
.empty())
324 // if the bus layer is idle
326 // note that we do not care who told us to retry at the moment, we
327 // merely let the first one on the retry list go
333 BaseBus::findPort(Addr addr
)
335 // we should never see any address lookups before we've got the
336 // ranges of all connected slave modules
337 assert(gotAllAddrRanges
);
340 PortID dest_id
= checkPortCache(addr
);
341 if (dest_id
!= InvalidPortID
)
344 // Check the address map interval tree
345 PortMapConstIter i
= portMap
.find(addr
);
346 if (i
!= portMap
.end()) {
348 updatePortCache(dest_id
, i
->first
);
352 // Check if this matches the default range
353 if (useDefaultRange
) {
354 if (defaultRange
.contains(addr
)) {
355 DPRINTF(BusAddrRanges
, " found addr %#llx on default\n",
357 return defaultPortID
;
359 } else if (defaultPortID
!= InvalidPortID
) {
360 DPRINTF(BusAddrRanges
, "Unable to find destination for addr %#llx, "
361 "will use default port\n", addr
);
362 return defaultPortID
;
365 // we should use the range for the default port and it did not
366 // match, or the default port is not set
367 fatal("Unable to find destination for addr %#llx on bus %s\n", addr
,
371 /** Function called by the port when the bus is receiving a range change.*/
373 BaseBus::recvRangeChange(PortID master_port_id
)
375 DPRINTF(BusAddrRanges
, "Received range change from slave port %s\n",
376 masterPorts
[master_port_id
]->getSlavePort().name());
378 // remember that we got a range from this master port and thus the
379 // connected slave module
380 gotAddrRanges
[master_port_id
] = true;
382 // update the global flag
383 if (!gotAllAddrRanges
) {
384 // take a logical AND of all the ports and see if we got
385 // ranges from everyone
386 gotAllAddrRanges
= true;
387 std::vector
<bool>::const_iterator r
= gotAddrRanges
.begin();
388 while (gotAllAddrRanges
&& r
!= gotAddrRanges
.end()) {
389 gotAllAddrRanges
&= *r
++;
391 if (gotAllAddrRanges
)
392 DPRINTF(BusAddrRanges
, "Got address ranges from all slaves\n");
395 // note that we could get the range from the default port at any
396 // point in time, and we cannot assume that the default range is
397 // set before the other ones are, so we do additional checks once
398 // all ranges are provided
399 if (master_port_id
== defaultPortID
) {
400 // only update if we are indeed checking ranges for the
401 // default port since the port might not have a valid range
403 if (useDefaultRange
) {
404 AddrRangeList ranges
= masterPorts
[master_port_id
]->getAddrRanges();
406 if (ranges
.size() != 1)
407 fatal("Bus %s may only have a single default range",
410 defaultRange
= ranges
.front();
413 // the ports are allowed to update their address ranges
414 // dynamically, so remove any existing entries
415 if (gotAddrRanges
[master_port_id
]) {
416 for (PortMapIter p
= portMap
.begin(); p
!= portMap
.end(); ) {
417 if (p
->second
== master_port_id
)
418 // erasing invalidates the iterator, so advance it
419 // before the deletion takes place
426 AddrRangeList ranges
= masterPorts
[master_port_id
]->getAddrRanges();
428 for (AddrRangeConstIter r
= ranges
.begin(); r
!= ranges
.end(); ++r
) {
429 DPRINTF(BusAddrRanges
, "Adding range %s for id %d\n",
430 r
->to_string(), master_port_id
);
431 if (portMap
.insert(*r
, master_port_id
) == portMap
.end()) {
432 PortID conflict_id
= portMap
.find(*r
)->second
;
433 fatal("%s has two ports with same range:\n\t%s\n\t%s\n",
435 masterPorts
[master_port_id
]->getSlavePort().name(),
436 masterPorts
[conflict_id
]->getSlavePort().name());
441 // if we have received ranges from all our neighbouring slave
442 // modules, go ahead and tell our connected master modules in
443 // turn, this effectively assumes a tree structure of the system
444 if (gotAllAddrRanges
) {
445 // also check that no range partially overlaps with the
446 // default range, this has to be done after all ranges are set
447 // as there are no guarantees for when the default range is
448 // update with respect to the other ones
449 if (useDefaultRange
) {
450 for (PortID port_id
= 0; port_id
< masterPorts
.size(); ++port_id
) {
451 if (port_id
== defaultPortID
) {
452 if (!gotAddrRanges
[port_id
])
453 fatal("Bus %s uses default range, but none provided",
456 AddrRangeList ranges
=
457 masterPorts
[port_id
]->getAddrRanges();
459 for (AddrRangeConstIter r
= ranges
.begin();
460 r
!= ranges
.end(); ++r
) {
461 // see if the new range is partially
462 // overlapping the default range
463 if (r
->intersects(defaultRange
) &&
464 !r
->isSubset(defaultRange
))
465 fatal("Range %s intersects the " \
466 "default range of %s but is not a " \
467 "subset\n", r
->to_string(), name());
473 // tell all our neighbouring master ports that our address
474 // ranges have changed
475 for (SlavePortConstIter s
= slavePorts
.begin(); s
!= slavePorts
.end();
477 (*s
)->sendRangeChange();
484 BaseBus::getAddrRanges() const
486 // we should never be asked without first having sent a range
487 // change, and the latter is only done once we have all the ranges
488 // of the connected devices
489 assert(gotAllAddrRanges
);
491 // at the moment, this never happens, as there are no cycles in
492 // the range queries and no devices on the master side of a bus
493 // (CPU, cache, bridge etc) actually care about the ranges of the
494 // ports they are connected to
496 DPRINTF(BusAddrRanges
, "Received address range request, returning:\n");
498 // start out with the default range
499 AddrRangeList ranges
;
500 if (useDefaultRange
) {
501 ranges
.push_back(defaultRange
);
502 DPRINTF(BusAddrRanges
, " -- Default %s\n", defaultRange
.to_string());
505 // add any range that is not a subset of the default range
506 for (PortMapConstIter p
= portMap
.begin(); p
!= portMap
.end(); ++p
) {
507 if (useDefaultRange
&& p
->first
.isSubset(defaultRange
)) {
508 DPRINTF(BusAddrRanges
, " -- %s is a subset of default\n",
509 p
->first
.to_string());
511 ranges
.push_back(p
->first
);
512 DPRINTF(BusAddrRanges
, " -- %s\n", p
->first
.to_string());
520 BaseBus::deviceBlockSize() const
525 template <typename PortClass
>
527 BaseBus::Layer
<PortClass
>::drain(DrainManager
*dm
)
529 //We should check that we're not "doing" anything, and that noone is
530 //waiting. We might be idle but have someone waiting if the device we
531 //contacted for a retry didn't actually retry.
532 if (!retryList
.empty() || state
!= IDLE
) {
533 DPRINTF(Drain
, "Bus not drained\n");
541 * Bus layer template instantiations. Could be removed with _impl.hh
542 * file, but since there are only two given options (MasterPort and
543 * SlavePort) it seems a bit excessive at this point.
545 template class BaseBus::Layer
<SlavePort
>;
546 template class BaseBus::Layer
<MasterPort
>;