1/* 2 * Copyright (c) 2011-2012 ARM Limited 3 * All rights reserved 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2006 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Ali Saidi 41 * Steve Reinhardt 42 * Andreas Hansson 43 */ 44 45/** 46 * @file 47 * Implementation of a memory-mapped bus bridge that connects a master 48 * and a slave through a request and response queue. 49 */ 50 51#include "base/trace.hh"
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52#include "debug/BusBridge.hh"
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52#include "debug/Bridge.hh" |
53#include "mem/bridge.hh" 54#include "params/Bridge.hh" 55
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56Bridge::BridgeSlavePort::BridgeSlavePort(const std::string &_name,
57 Bridge* _bridge,
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56Bridge::BridgeSlavePort::BridgeSlavePort(const std::string& _name, 57 Bridge& _bridge, |
58 BridgeMasterPort& _masterPort,
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59 int _delay, int _nack_delay,
60 int _resp_limit,
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59 int _delay, int _resp_limit, |
60 std::vector<Range<Addr> > _ranges)
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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),
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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) 65{ 66} 67
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70Bridge::BridgeMasterPort::BridgeMasterPort(const std::string &_name,
71 Bridge* _bridge,
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68Bridge::BridgeMasterPort::BridgeMasterPort(const std::string& _name, 69 Bridge& _bridge, |
70 BridgeSlavePort& _slavePort, 71 int _delay, int _req_limit)
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74 : MasterPort(_name, _bridge), bridge(_bridge), slavePort(_slavePort),
75 delay(_delay), inRetry(false), reqQueueLimit(_req_limit),
76 sendEvent(*this)
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72 : MasterPort(_name, &_bridge), bridge(_bridge), slavePort(_slavePort), 73 delay(_delay), reqQueueLimit(_req_limit), sendEvent(*this) |
74{ 75} 76 77Bridge::Bridge(Params *p) 78 : MemObject(p),
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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)
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79 slavePort(p->name + ".slave", *this, masterPort, p->delay, p->resp_size, 80 p->ranges), 81 masterPort(p->name + ".master", *this, slavePort, p->delay, p->req_size) |
82{
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87 if (ackWrites)
88 panic("No support for acknowledging writes\n");
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83} 84 85MasterPort& 86Bridge::getMasterPort(const std::string &if_name, int idx) 87{ 88 if (if_name == "master") 89 return masterPort; 90 else 91 // pass it along to our super class 92 return MemObject::getMasterPort(if_name, idx); 93} 94 95SlavePort& 96Bridge::getSlavePort(const std::string &if_name, int idx) 97{ 98 if (if_name == "slave") 99 return slavePort; 100 else 101 // pass it along to our super class 102 return MemObject::getSlavePort(if_name, idx); 103} 104 105void 106Bridge::init() 107{ 108 // make sure both sides are connected and have the same block size 109 if (!slavePort.isConnected() || !masterPort.isConnected()) 110 fatal("Both ports of bus bridge are not connected to a bus.\n"); 111 112 if (slavePort.peerBlockSize() != masterPort.peerBlockSize()) 113 fatal("Slave port size %d, master port size %d \n " \ 114 "Busses don't have the same block size... Not supported.\n", 115 slavePort.peerBlockSize(), masterPort.peerBlockSize()); 116 117 // notify the master side of our address ranges 118 slavePort.sendRangeChange(); 119} 120 121bool 122Bridge::BridgeSlavePort::respQueueFull() 123{ 124 return outstandingResponses == respQueueLimit; 125} 126 127bool 128Bridge::BridgeMasterPort::reqQueueFull() 129{
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136 return requestQueue.size() == reqQueueLimit;
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130 return transmitList.size() == reqQueueLimit; |
131} 132 133bool 134Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) 135{ 136 // all checks are done when the request is accepted on the slave 137 // side, so we are guaranteed to have space for the response
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144 DPRINTF(BusBridge, "recvTiming: response %s addr 0x%x\n",
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138 DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n", |
139 pkt->cmdString(), pkt->getAddr()); 140
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147 DPRINTF(BusBridge, "Request queue size: %d\n", requestQueue.size());
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141 DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size()); |
142
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149 slavePort.queueForSendTiming(pkt);
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143 slavePort.schedTimingResp(pkt, curTick() + delay); |
144 145 return true; 146} 147 148bool 149Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) 150{
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157 DPRINTF(BusBridge, "recvTiming: request %s addr 0x%x\n",
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151 DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", |
152 pkt->cmdString(), pkt->getAddr()); 153
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160 DPRINTF(BusBridge, "Response queue size: %d outresp: %d\n",
161 responseQueue.size(), outstandingResponses);
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154 // ensure we do not have something waiting to retry 155 if(retryReq) 156 return false; |
157
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163 if (masterPort.reqQueueFull()) {
164 DPRINTF(BusBridge, "Request queue full, nacking\n");
165 nackRequest(pkt);
166 return true;
167 }
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158 DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", 159 transmitList.size(), outstandingResponses); |
160
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169 if (pkt->needsResponse()) {
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161 if (masterPort.reqQueueFull()) { 162 DPRINTF(Bridge, "Request queue full\n"); 163 retryReq = true; 164 } else if (pkt->needsResponse()) { |
165 if (respQueueFull()) {
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171 DPRINTF(BusBridge,
172 "Response queue full, no space for response, nacking\n");
173 DPRINTF(BusBridge,
174 "queue size: %d outstanding resp: %d\n",
175 responseQueue.size(), outstandingResponses);
176 nackRequest(pkt);
177 return true;
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166 DPRINTF(Bridge, "Response queue full\n"); 167 retryReq = true; |
168 } else {
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179 DPRINTF(BusBridge, "Request Needs response, reserving space\n");
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169 DPRINTF(Bridge, "Reserving space for response\n"); |
170 assert(outstandingResponses != respQueueLimit); 171 ++outstandingResponses;
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172 retryReq = false; 173 masterPort.schedTimingReq(pkt, curTick() + delay); |
174 } 175 } 176
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185 masterPort.queueForSendTiming(pkt);
186
187 return true;
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177 // remember that we are now stalling a packet and that we have to 178 // tell the sending master to retry once space becomes available, 179 // we make no distinction whether the stalling is due to the 180 // request queue or response queue being full 181 return !retryReq; |
182} 183 184void
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191Bridge::BridgeSlavePort::nackRequest(PacketPtr pkt)
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185Bridge::BridgeSlavePort::retryStalledReq() |
186{
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193 // Nack the packet
194 pkt->makeTimingResponse();
195 pkt->setNacked();
196
197 // The Nack packets are stored in the response queue just like any
198 // other response, but they do not occupy any space as this is
199 // tracked by the outstandingResponses, this guarantees space for
200 // the Nack packets, but implicitly means we have an (unrealistic)
201 // unbounded Nack queue.
202
203 // put it on the list to send
204 Tick readyTime = curTick() + nackDelay;
205 DeferredResponse resp(pkt, readyTime, true);
206
207 // nothing on the list, add it and we're done
208 if (responseQueue.empty()) {
209 assert(!sendEvent.scheduled());
210 bridge->schedule(sendEvent, readyTime);
211 responseQueue.push_back(resp);
212 return;
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187 if (retryReq) { 188 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 189 retryReq = false; 190 sendRetry(); |
191 }
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214
215 assert(sendEvent.scheduled() || inRetry);
216
217 // does it go at the end?
218 if (readyTime >= responseQueue.back().ready) {
219 responseQueue.push_back(resp);
220 return;
221 }
222
223 // ok, somewhere in the middle, fun
224 std::list<DeferredResponse>::iterator i = responseQueue.begin();
225 std::list<DeferredResponse>::iterator end = responseQueue.end();
226 std::list<DeferredResponse>::iterator begin = responseQueue.begin();
227 bool done = false;
228
229 while (i != end && !done) {
230 if (readyTime < (*i).ready) {
231 if (i == begin)
232 bridge->reschedule(sendEvent, readyTime);
233 responseQueue.insert(i, resp);
234 done = true;
235 }
236 i++;
237 }
238 assert(done);
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192} 193 194void
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242Bridge::BridgeMasterPort::queueForSendTiming(PacketPtr pkt)
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195Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) |
196{
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244 Tick readyTime = curTick() + delay;
245
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197 // If we expect to see a response, we need to restore the source 198 // and destination field that is potentially changed by a second 199 // bus 200 if (!pkt->memInhibitAsserted() && pkt->needsResponse()) { 201 // Update the sender state so we can deal with the response 202 // appropriately 203 RequestState *req_state = new RequestState(pkt); 204 pkt->senderState = req_state; 205 } 206 207 // If we're about to put this packet at the head of the queue, we 208 // need to schedule an event to do the transmit. Otherwise there 209 // should already be an event scheduled for sending the head 210 // packet.
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260 if (requestQueue.empty()) {
261 bridge->schedule(sendEvent, readyTime);
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211 if (transmitList.empty()) { 212 bridge.schedule(sendEvent, when); |
213 } 214
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264 assert(requestQueue.size() != reqQueueLimit);
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215 assert(transmitList.size() != reqQueueLimit); |
216
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266 requestQueue.push_back(DeferredRequest(pkt, readyTime));
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217 transmitList.push_back(DeferredPacket(pkt, when)); |
218} 219 220 221void
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271Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt)
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222Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) |
223{ 224 // This is a response for a request we forwarded earlier. The 225 // corresponding request state should be stored in the packet's 226 // senderState field. 227 RequestState *req_state = dynamic_cast<RequestState*>(pkt->senderState); 228 assert(req_state != NULL); 229 // set up new packet dest & senderState based on values saved 230 // from original request 231 req_state->fixResponse(pkt);
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232 delete req_state; |
233 234 // the bridge assumes that at least one bus has set the 235 // destination field of the packet 236 assert(pkt->isDestValid());
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285 DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest());
286 delete req_state;
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237 DPRINTF(Bridge, "response, new dest %d\n", pkt->getDest()); |
238
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288 Tick readyTime = curTick() + delay;
289
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239 // If we're about to put this packet at the head of the queue, we 240 // need to schedule an event to do the transmit. Otherwise there 241 // should already be an event scheduled for sending the head 242 // packet.
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294 if (responseQueue.empty()) {
295 bridge->schedule(sendEvent, readyTime);
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243 if (transmitList.empty()) { 244 bridge.schedule(sendEvent, when); |
245 }
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297 responseQueue.push_back(DeferredResponse(pkt, readyTime));
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246 247 transmitList.push_back(DeferredPacket(pkt, when)); |
248} 249 250void
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301Bridge::BridgeMasterPort::trySend()
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251Bridge::BridgeMasterPort::trySendTiming() |
252{
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303 assert(!requestQueue.empty());
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253 assert(!transmitList.empty()); |
254
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305 DeferredRequest req = requestQueue.front();
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255 DeferredPacket req = transmitList.front(); |
256
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307 assert(req.ready <= curTick());
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257 assert(req.tick <= curTick()); |
258 259 PacketPtr pkt = req.pkt; 260
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311 DPRINTF(BusBridge, "trySend request: addr 0x%x\n", pkt->getAddr());
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261 DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", 262 pkt->getAddr(), transmitList.size()); |
263 264 if (sendTimingReq(pkt)) { 265 // send successful
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315 requestQueue.pop_front();
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266 transmitList.pop_front(); 267 DPRINTF(Bridge, "trySend request successful\n"); |
268 269 // If there are more packets to send, schedule event to try again.
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318 if (!requestQueue.empty()) {
319 req = requestQueue.front();
320 DPRINTF(BusBridge, "Scheduling next send\n");
321 bridge->schedule(sendEvent,
322 std::max(req.ready, curTick() + 1));
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270 if (!transmitList.empty()) { 271 req = transmitList.front(); 272 DPRINTF(Bridge, "Scheduling next send\n"); 273 bridge.schedule(sendEvent, std::max(req.tick, 274 bridge.nextCycle())); |
275 }
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324 } else {
325 inRetry = true;
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276 277 // if we have stalled a request due to a full request queue, 278 // then send a retry at this point, also note that if the 279 // request we stalled was waiting for the response queue 280 // rather than the request queue we might stall it again 281 slavePort.retryStalledReq(); |
282 } 283
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328 DPRINTF(BusBridge, "trySend: request queue size: %d\n",
329 requestQueue.size());
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284 // if the send failed, then we try again once we receive a retry, 285 // and therefore there is no need to take any action |
286} 287 288void
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333Bridge::BridgeSlavePort::trySend()
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289Bridge::BridgeSlavePort::trySendTiming() |
290{
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335 assert(!responseQueue.empty());
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291 assert(!transmitList.empty()); |
292
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337 DeferredResponse resp = responseQueue.front();
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293 DeferredPacket resp = transmitList.front(); |
294
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339 assert(resp.ready <= curTick());
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295 assert(resp.tick <= curTick()); |
296 297 PacketPtr pkt = resp.pkt; 298
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343 DPRINTF(BusBridge, "trySend response: dest %d addr 0x%x\n",
344 pkt->getDest(), pkt->getAddr());
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299 DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", 300 pkt->getAddr(), outstandingResponses); |
301
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346 bool was_nacked_here = resp.nackedHere;
347
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302 if (sendTimingResp(pkt)) {
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349 DPRINTF(BusBridge, " successful\n");
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303 // send successful
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351 responseQueue.pop_front();
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304 transmitList.pop_front(); 305 DPRINTF(Bridge, "trySend response successful\n"); |
306
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353 if (!was_nacked_here) {
354 assert(outstandingResponses != 0);
355 --outstandingResponses;
356 }
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307 assert(outstandingResponses != 0); 308 --outstandingResponses; |
309 310 // If there are more packets to send, schedule event to try again.
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359 if (!responseQueue.empty()) {
360 resp = responseQueue.front();
361 DPRINTF(BusBridge, "Scheduling next send\n");
362 bridge->schedule(sendEvent,
363 std::max(resp.ready, curTick() + 1));
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311 if (!transmitList.empty()) { 312 resp = transmitList.front(); 313 DPRINTF(Bridge, "Scheduling next send\n"); 314 bridge.schedule(sendEvent, std::max(resp.tick, 315 bridge.nextCycle())); |
316 }
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365 } else {
366 DPRINTF(BusBridge, " unsuccessful\n");
367 inRetry = true;
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317 318 // if there is space in the request queue and we were stalling 319 // a request, it will definitely be possible to accept it now 320 // since there is guaranteed space in the response queue 321 if (!masterPort.reqQueueFull() && retryReq) { 322 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 323 retryReq = false; 324 sendRetry(); 325 } |
326 } 327
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370 DPRINTF(BusBridge, "trySend: queue size: %d outstanding resp: %d\n",
371 responseQueue.size(), outstandingResponses);
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328 // if the send failed, then we try again once we receive a retry, 329 // and therefore there is no need to take any action |
330} 331 332void 333Bridge::BridgeMasterPort::recvRetry() 334{
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377 inRetry = false;
378 Tick nextReady = requestQueue.front().ready;
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335 Tick nextReady = transmitList.front().tick; |
336 if (nextReady <= curTick())
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380 trySend();
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337 trySendTiming(); |
338 else
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382 bridge->schedule(sendEvent, nextReady);
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339 bridge.schedule(sendEvent, nextReady); |
340} 341 342void 343Bridge::BridgeSlavePort::recvRetry() 344{
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388 inRetry = false;
389 Tick nextReady = responseQueue.front().ready;
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345 Tick nextReady = transmitList.front().tick; |
346 if (nextReady <= curTick())
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391 trySend();
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347 trySendTiming(); |
348 else
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393 bridge->schedule(sendEvent, nextReady);
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349 bridge.schedule(sendEvent, nextReady); |
350} 351 352Tick 353Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) 354{ 355 return delay + masterPort.sendAtomic(pkt); 356} 357 358void 359Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) 360{
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405 std::list<DeferredResponse>::iterator i;
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361 std::list<DeferredPacket>::iterator i; |
362 363 pkt->pushLabel(name()); 364 365 // check the response queue
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410 for (i = responseQueue.begin(); i != responseQueue.end(); ++i) {
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366 for (i = transmitList.begin(); i != transmitList.end(); ++i) { |
367 if (pkt->checkFunctional((*i).pkt)) { 368 pkt->makeResponse(); 369 return; 370 } 371 } 372 373 // also check the master port's request queue 374 if (masterPort.checkFunctional(pkt)) { 375 return; 376 } 377 378 pkt->popLabel(); 379 380 // fall through if pkt still not satisfied 381 masterPort.sendFunctional(pkt); 382} 383 384bool 385Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) 386{ 387 bool found = false;
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432 std::list<DeferredRequest>::iterator i = requestQueue.begin();
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388 std::list<DeferredPacket>::iterator i = transmitList.begin(); |
389
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434 while(i != requestQueue.end() && !found) {
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390 while(i != transmitList.end() && !found) { |
391 if (pkt->checkFunctional((*i).pkt)) { 392 pkt->makeResponse(); 393 found = true; 394 } 395 ++i; 396 } 397 398 return found; 399} 400 401AddrRangeList 402Bridge::BridgeSlavePort::getAddrRanges() const 403{ 404 return ranges; 405} 406 407Bridge * 408BridgeParams::create() 409{ 410 return new Bridge(this); 411}
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