bridge.hh revision 8922:17f037ad8918
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 * Declaration of a memory-mapped bus bridge that connects a master 48 * and a slave through a request and response queue. 49 */ 50 51#ifndef __MEM_BRIDGE_HH__ 52#define __MEM_BRIDGE_HH__ 53 54#include <list> 55#include <queue> 56#include <string> 57 58#include "base/fast_alloc.hh" 59#include "base/types.hh" 60#include "mem/mem_object.hh" 61#include "mem/packet.hh" 62#include "mem/port.hh" 63#include "params/Bridge.hh" 64#include "sim/eventq.hh" 65 66/** 67 * A bridge is used to interface two different busses (or in general a 68 * memory-mapped master and slave), with buffering for requests and 69 * responses. The bridge has a fixed delay for packets passing through 70 * it and responds to a fixed set of address ranges. 71 * 72 * The bridge comprises a slave port and a master port, that buffer 73 * outgoing responses and requests respectively. Buffer space is 74 * reserved when a request arrives, also reserving response space 75 * before forwarding the request. An incoming request is always 76 * accepted (recvTiming returns true), but is potentially NACKed if 77 * there is no request space or response space. 78 */ 79class Bridge : public MemObject 80{ 81 protected: 82 83 /** 84 * A packet buffer stores packets along with their sender state 85 * and scheduled time for transmission. 86 */ 87 class PacketBuffer : public Packet::SenderState, public FastAlloc { 88 89 public: 90 Tick ready; 91 PacketPtr pkt; 92 bool nackedHere; 93 Packet::SenderState *origSenderState; 94 short origSrc; 95 bool expectResponse; 96 97 PacketBuffer(PacketPtr _pkt, Tick t, bool nack = false) 98 : ready(t), pkt(_pkt), nackedHere(nack), 99 origSenderState(_pkt->senderState), 100 origSrc(nack ? _pkt->getDest() : _pkt->getSrc() ), 101 expectResponse(_pkt->needsResponse() && !nack) 102 103 { 104 if (!pkt->isResponse() && !nack) 105 pkt->senderState = this; 106 } 107 108 void fixResponse(PacketPtr pkt) 109 { 110 assert(pkt->senderState == this); 111 pkt->setDest(origSrc); 112 pkt->senderState = origSenderState; 113 } 114 }; 115 116 // Forward declaration to allow the slave port to have a pointer 117 class BridgeMasterPort; 118 119 /** 120 * The port on the side that receives requests and sends 121 * responses. The slave port has a set of address ranges that it 122 * is responsible for. The slave port also has a buffer for the 123 * responses not yet sent. 124 */ 125 class BridgeSlavePort : public SlavePort 126 { 127 128 private: 129 130 /** A pointer to the bridge to which this port belongs. */ 131 Bridge *bridge; 132 133 /** 134 * Master port on the other side of the bridge 135 * (connected to the other bus). 136 */ 137 BridgeMasterPort& masterPort; 138 139 /** Minimum request delay though this bridge. */ 140 Tick delay; 141 142 /** Min delay to respond with a nack. */ 143 Tick nackDelay; 144 145 /** Address ranges to pass through the bridge */ 146 AddrRangeList ranges; 147 148 /** 149 * Response packet queue. Response packets are held in this 150 * queue for a specified delay to model the processing delay 151 * of the bridge. 152 */ 153 std::list<PacketBuffer*> responseQueue; 154 155 /** Counter to track the outstanding responses. */ 156 unsigned int outstandingResponses; 157 158 /** If we're waiting for a retry to happen. */ 159 bool inRetry; 160 161 /** Max queue size for reserved responses. */ 162 unsigned int respQueueLimit; 163 164 /** 165 * Is this side blocked from accepting new response packets. 166 * 167 * @return true if the reserved space has reached the set limit 168 */ 169 bool respQueueFull(); 170 171 /** 172 * Turn the request packet into a NACK response and put it in 173 * the response queue and schedule its transmission. 174 * 175 * @param pkt the request packet to NACK 176 */ 177 void nackRequest(PacketPtr pkt); 178 179 /** 180 * Handle send event, scheduled when the packet at the head of 181 * the response queue is ready to transmit (for timing 182 * accesses only). 183 */ 184 void trySend(); 185 186 /** 187 * Private class for scheduling sending of responses from the 188 * response queue. 189 */ 190 class SendEvent : public Event 191 { 192 BridgeSlavePort& port; 193 194 public: 195 SendEvent(BridgeSlavePort& p) : port(p) {} 196 virtual void process() { port.trySend(); } 197 virtual const char *description() const { return "bridge send"; } 198 }; 199 200 /** Send event for the response queue. */ 201 SendEvent sendEvent; 202 203 public: 204 205 /** 206 * Constructor for the BridgeSlavePort. 207 * 208 * @param _name the port name including the owner 209 * @param _bridge the structural owner 210 * @param _masterPort the master port on the other side of the bridge 211 * @param _delay the delay from seeing a response to sending it 212 * @param _nack_delay the delay from a NACK to sending the response 213 * @param _resp_limit the size of the response queue 214 * @param _ranges a number of address ranges to forward 215 */ 216 BridgeSlavePort(const std::string &_name, Bridge *_bridge, 217 BridgeMasterPort& _masterPort, int _delay, 218 int _nack_delay, int _resp_limit, 219 std::vector<Range<Addr> > _ranges); 220 221 /** 222 * Queue a response packet to be sent out later and also schedule 223 * a send if necessary. 224 * 225 * @param pkt a response to send out after a delay 226 */ 227 void queueForSendTiming(PacketPtr pkt); 228 229 protected: 230 231 /** When receiving a timing request from the peer port, 232 pass it to the bridge. */ 233 virtual bool recvTiming(PacketPtr pkt); 234 235 /** When receiving a retry request from the peer port, 236 pass it to the bridge. */ 237 virtual void recvRetry(); 238 239 /** When receiving a Atomic requestfrom the peer port, 240 pass it to the bridge. */ 241 virtual Tick recvAtomic(PacketPtr pkt); 242 243 /** When receiving a Functional request from the peer port, 244 pass it to the bridge. */ 245 virtual void recvFunctional(PacketPtr pkt); 246 247 /** When receiving a address range request the peer port, 248 pass it to the bridge. */ 249 virtual AddrRangeList getAddrRanges(); 250 }; 251 252 253 /** 254 * Port on the side that forwards requests and receives 255 * responses. The master port has a buffer for the requests not 256 * yet sent. 257 */ 258 class BridgeMasterPort : public MasterPort 259 { 260 261 private: 262 263 /** A pointer to the bridge to which this port belongs. */ 264 Bridge* bridge; 265 266 /** 267 * Pointer to the slave port on the other side of the bridge 268 * (connected to the other bus). 269 */ 270 BridgeSlavePort& slavePort; 271 272 /** Minimum delay though this bridge. */ 273 Tick delay; 274 275 /** 276 * Request packet queue. Request packets are held in this 277 * queue for a specified delay to model the processing delay 278 * of the bridge. 279 */ 280 std::list<PacketBuffer*> requestQueue; 281 282 /** If we're waiting for a retry to happen. */ 283 bool inRetry; 284 285 /** Max queue size for request packets */ 286 unsigned int reqQueueLimit; 287 288 /** 289 * Handle send event, scheduled when the packet at the head of 290 * the outbound queue is ready to transmit (for timing 291 * accesses only). 292 */ 293 void trySend(); 294 295 /** 296 * Private class for scheduling sending of requests from the 297 * request queue. 298 */ 299 class SendEvent : public Event 300 { 301 BridgeMasterPort& port; 302 303 public: 304 SendEvent(BridgeMasterPort& p) : port(p) {} 305 virtual void process() { port.trySend(); } 306 virtual const char *description() const { return "bridge send"; } 307 }; 308 309 /** Send event for the request queue. */ 310 SendEvent sendEvent; 311 312 public: 313 314 /** 315 * Constructor for the BridgeMasterPort. 316 * 317 * @param _name the port name including the owner 318 * @param _bridge the structural owner 319 * @param _slavePort the slave port on the other side of the bridge 320 * @param _delay the delay from seeing a request to sending it 321 * @param _req_limit the size of the request queue 322 */ 323 BridgeMasterPort(const std::string &_name, Bridge *_bridge, 324 BridgeSlavePort& _slavePort, int _delay, 325 int _req_limit); 326 327 /** 328 * Is this side blocked from accepting new request packets. 329 * 330 * @return true if the occupied space has reached the set limit 331 */ 332 bool reqQueueFull(); 333 334 /** 335 * Queue a request packet to be sent out later and also schedule 336 * a send if necessary. 337 * 338 * @param pkt a request to send out after a delay 339 */ 340 void queueForSendTiming(PacketPtr pkt); 341 342 /** 343 * Check a functional request against the packets in our 344 * request queue. 345 * 346 * @param pkt packet to check against 347 * 348 * @return true if we find a match 349 */ 350 bool checkFunctional(PacketPtr pkt); 351 352 protected: 353 354 /** When receiving a timing request from the peer port, 355 pass it to the bridge. */ 356 virtual bool recvTiming(PacketPtr pkt); 357 358 /** When receiving a retry request from the peer port, 359 pass it to the bridge. */ 360 virtual void recvRetry(); 361 362 /** When receiving a Atomic requestfrom the peer port, 363 pass it to the bridge. */ 364 virtual Tick recvAtomic(PacketPtr pkt); 365 366 /** When receiving a Functional request from the peer port, 367 pass it to the bridge. */ 368 virtual void recvFunctional(PacketPtr pkt); 369 }; 370 371 /** Slave port of the bridge. */ 372 BridgeSlavePort slavePort; 373 374 /** Master port of the bridge. */ 375 BridgeMasterPort masterPort; 376 377 /** If this bridge should acknowledge writes. */ 378 bool ackWrites; 379 380 public: 381 typedef BridgeParams Params; 382 383 protected: 384 Params *_params; 385 386 public: 387 const Params *params() const { return _params; } 388 389 virtual MasterPort& getMasterPort(const std::string& if_name, 390 int idx = -1); 391 virtual SlavePort& getSlavePort(const std::string& if_name, int idx = -1); 392 393 virtual void init(); 394 395 Bridge(Params *p); 396}; 397 398#endif //__MEM_BUS_HH__ 399