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" 52#include "debug/Bridge.hh" 53#include "mem/bridge.hh" 54#include "params/Bridge.hh" 55 56Bridge::BridgeSlavePort::BridgeSlavePort(const std::string& _name, 57 Bridge& _bridge, 58 BridgeMasterPort& _masterPort, 59 Cycles _delay, int _resp_limit,
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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 68Bridge::BridgeMasterPort::BridgeMasterPort(const std::string& _name, 69 Bridge& _bridge, 70 BridgeSlavePort& _slavePort, 71 Cycles _delay, int _req_limit) 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), 79 slavePort(p->name + ".slave", *this, masterPort, 80 ticksToCycles(p->delay), p->resp_size, p->ranges), 81 masterPort(p->name + ".master", *this, slavePort, 82 ticksToCycles(p->delay), p->req_size) 83{ 84} 85 86MasterPort& 87Bridge::getMasterPort(const std::string &if_name, int idx) 88{ 89 if (if_name == "master") 90 return masterPort; 91 else 92 // pass it along to our super class 93 return MemObject::getMasterPort(if_name, idx); 94} 95 96SlavePort& 97Bridge::getSlavePort(const std::string &if_name, int idx) 98{ 99 if (if_name == "slave") 100 return slavePort; 101 else 102 // pass it along to our super class 103 return MemObject::getSlavePort(if_name, idx); 104} 105 106void 107Bridge::init() 108{ 109 // make sure both sides are connected and have the same block size 110 if (!slavePort.isConnected() || !masterPort.isConnected()) 111 fatal("Both ports of bus bridge are not connected to a bus.\n"); 112 113 if (slavePort.peerBlockSize() != masterPort.peerBlockSize()) 114 fatal("Slave port size %d, master port size %d \n " \ 115 "Busses don't have the same block size... Not supported.\n", 116 slavePort.peerBlockSize(), masterPort.peerBlockSize()); 117 118 // notify the master side of our address ranges 119 slavePort.sendRangeChange(); 120} 121 122bool 123Bridge::BridgeSlavePort::respQueueFull() 124{ 125 return outstandingResponses == respQueueLimit; 126} 127 128bool 129Bridge::BridgeMasterPort::reqQueueFull() 130{ 131 return transmitList.size() == reqQueueLimit; 132} 133 134bool 135Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) 136{ 137 // all checks are done when the request is accepted on the slave 138 // side, so we are guaranteed to have space for the response 139 DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n", 140 pkt->cmdString(), pkt->getAddr()); 141 142 DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size()); 143 144 slavePort.schedTimingResp(pkt, bridge.clockEdge(delay)); 145 146 return true; 147} 148 149bool 150Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) 151{ 152 DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", 153 pkt->cmdString(), pkt->getAddr()); 154 155 // ensure we do not have something waiting to retry 156 if(retryReq) 157 return false; 158 159 DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", 160 transmitList.size(), outstandingResponses); 161 162 if (masterPort.reqQueueFull()) { 163 DPRINTF(Bridge, "Request queue full\n"); 164 retryReq = true; 165 } else if (pkt->needsResponse()) { 166 if (respQueueFull()) { 167 DPRINTF(Bridge, "Response queue full\n"); 168 retryReq = true; 169 } else { 170 DPRINTF(Bridge, "Reserving space for response\n"); 171 assert(outstandingResponses != respQueueLimit); 172 ++outstandingResponses; 173 retryReq = false; 174 masterPort.schedTimingReq(pkt, bridge.clockEdge(delay)); 175 } 176 } 177 178 // remember that we are now stalling a packet and that we have to 179 // tell the sending master to retry once space becomes available, 180 // we make no distinction whether the stalling is due to the 181 // request queue or response queue being full 182 return !retryReq; 183} 184 185void 186Bridge::BridgeSlavePort::retryStalledReq() 187{ 188 if (retryReq) { 189 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 190 retryReq = false; 191 sendRetry(); 192 } 193} 194 195void 196Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) 197{ 198 // If we expect to see a response, we need to restore the source 199 // and destination field that is potentially changed by a second 200 // bus 201 if (!pkt->memInhibitAsserted() && pkt->needsResponse()) { 202 // Update the sender state so we can deal with the response 203 // appropriately 204 RequestState *req_state = new RequestState(pkt); 205 pkt->senderState = req_state; 206 } 207 208 // If we're about to put this packet at the head of the queue, we 209 // need to schedule an event to do the transmit. Otherwise there 210 // should already be an event scheduled for sending the head 211 // packet. 212 if (transmitList.empty()) { 213 bridge.schedule(sendEvent, when); 214 } 215 216 assert(transmitList.size() != reqQueueLimit); 217 218 transmitList.push_back(DeferredPacket(pkt, when)); 219} 220 221 222void 223Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) 224{ 225 // This is a response for a request we forwarded earlier. The 226 // corresponding request state should be stored in the packet's 227 // senderState field. 228 RequestState *req_state = dynamic_cast<RequestState*>(pkt->senderState); 229 assert(req_state != NULL); 230 // set up new packet dest & senderState based on values saved 231 // from original request 232 req_state->fixResponse(pkt); 233 delete req_state; 234 235 // the bridge assumes that at least one bus has set the 236 // destination field of the packet 237 assert(pkt->isDestValid()); 238 DPRINTF(Bridge, "response, new dest %d\n", pkt->getDest()); 239 240 // If we're about to put this packet at the head of the queue, we 241 // need to schedule an event to do the transmit. Otherwise there 242 // should already be an event scheduled for sending the head 243 // packet. 244 if (transmitList.empty()) { 245 bridge.schedule(sendEvent, when); 246 } 247 248 transmitList.push_back(DeferredPacket(pkt, when)); 249} 250 251void 252Bridge::BridgeMasterPort::trySendTiming() 253{ 254 assert(!transmitList.empty()); 255 256 DeferredPacket req = transmitList.front(); 257 258 assert(req.tick <= curTick()); 259 260 PacketPtr pkt = req.pkt; 261 262 DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", 263 pkt->getAddr(), transmitList.size()); 264 265 if (sendTimingReq(pkt)) { 266 // send successful 267 transmitList.pop_front(); 268 DPRINTF(Bridge, "trySend request successful\n"); 269 270 // If there are more packets to send, schedule event to try again. 271 if (!transmitList.empty()) { 272 req = transmitList.front(); 273 DPRINTF(Bridge, "Scheduling next send\n"); 274 bridge.schedule(sendEvent, std::max(req.tick, 275 bridge.nextCycle())); 276 } 277 278 // if we have stalled a request due to a full request queue, 279 // then send a retry at this point, also note that if the 280 // request we stalled was waiting for the response queue 281 // rather than the request queue we might stall it again 282 slavePort.retryStalledReq(); 283 } 284 285 // if the send failed, then we try again once we receive a retry, 286 // and therefore there is no need to take any action 287} 288 289void 290Bridge::BridgeSlavePort::trySendTiming() 291{ 292 assert(!transmitList.empty()); 293 294 DeferredPacket resp = transmitList.front(); 295 296 assert(resp.tick <= curTick()); 297 298 PacketPtr pkt = resp.pkt; 299 300 DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", 301 pkt->getAddr(), outstandingResponses); 302 303 if (sendTimingResp(pkt)) { 304 // send successful 305 transmitList.pop_front(); 306 DPRINTF(Bridge, "trySend response successful\n"); 307 308 assert(outstandingResponses != 0); 309 --outstandingResponses; 310 311 // If there are more packets to send, schedule event to try again. 312 if (!transmitList.empty()) { 313 resp = transmitList.front(); 314 DPRINTF(Bridge, "Scheduling next send\n"); 315 bridge.schedule(sendEvent, std::max(resp.tick, 316 bridge.nextCycle())); 317 } 318 319 // if there is space in the request queue and we were stalling 320 // a request, it will definitely be possible to accept it now 321 // since there is guaranteed space in the response queue 322 if (!masterPort.reqQueueFull() && retryReq) { 323 DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); 324 retryReq = false; 325 sendRetry(); 326 } 327 } 328 329 // if the send failed, then we try again once we receive a retry, 330 // and therefore there is no need to take any action 331} 332 333void 334Bridge::BridgeMasterPort::recvRetry() 335{ 336 Tick nextReady = transmitList.front().tick; 337 if (nextReady <= curTick()) 338 trySendTiming(); 339 else 340 bridge.schedule(sendEvent, nextReady); 341} 342 343void 344Bridge::BridgeSlavePort::recvRetry() 345{ 346 Tick nextReady = transmitList.front().tick; 347 if (nextReady <= curTick()) 348 trySendTiming(); 349 else 350 bridge.schedule(sendEvent, nextReady); 351} 352 353Tick 354Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) 355{ 356 return delay * bridge.clockPeriod() + masterPort.sendAtomic(pkt); 357} 358 359void 360Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) 361{ 362 std::list<DeferredPacket>::iterator i; 363 364 pkt->pushLabel(name()); 365 366 // check the response queue 367 for (i = transmitList.begin(); i != transmitList.end(); ++i) { 368 if (pkt->checkFunctional((*i).pkt)) { 369 pkt->makeResponse(); 370 return; 371 } 372 } 373 374 // also check the master port's request queue 375 if (masterPort.checkFunctional(pkt)) { 376 return; 377 } 378 379 pkt->popLabel(); 380 381 // fall through if pkt still not satisfied 382 masterPort.sendFunctional(pkt); 383} 384 385bool 386Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) 387{ 388 bool found = false; 389 std::list<DeferredPacket>::iterator i = transmitList.begin(); 390 391 while(i != transmitList.end() && !found) { 392 if (pkt->checkFunctional((*i).pkt)) { 393 pkt->makeResponse(); 394 found = true; 395 } 396 ++i; 397 } 398 399 return found; 400} 401 402AddrRangeList 403Bridge::BridgeSlavePort::getAddrRanges() const 404{ 405 return ranges; 406} 407 408Bridge * 409BridgeParams::create() 410{ 411 return new Bridge(this); 412}
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