bridge.hh revision 8713:2f1a3e335255
1/* 2 * Copyright (c) 2011 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 Port 126 { 127 128 private: 129 130 /** A pointer to the bridge to which this port belongs. */ 131 Bridge *bridge; 132 133 /** 134 * Pointer to the 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 /** 248 * When receiving a range change on the slave side do nothing. 249 */ 250 virtual void recvRangeChange(); 251 252 /** When receiving a address range request the peer port, 253 pass it to the bridge. */ 254 virtual AddrRangeList getAddrRanges(); 255 }; 256 257 258 /** 259 * Port on the side that forwards requests and receives 260 * responses. The master port has a buffer for the requests not 261 * yet sent. 262 */ 263 class BridgeMasterPort : public Port 264 { 265 266 private: 267 268 /** A pointer to the bridge to which this port belongs. */ 269 Bridge* bridge; 270 271 /** 272 * Pointer to the slave port on the other side of the bridge 273 * (connected to the other bus). 274 */ 275 BridgeSlavePort* slavePort; 276 277 /** Minimum delay though this bridge. */ 278 Tick delay; 279 280 /** 281 * Request packet queue. Request packets are held in this 282 * queue for a specified delay to model the processing delay 283 * of the bridge. 284 */ 285 std::list<PacketBuffer*> requestQueue; 286 287 /** If we're waiting for a retry to happen. */ 288 bool inRetry; 289 290 /** Max queue size for request packets */ 291 unsigned int reqQueueLimit; 292 293 /** 294 * Handle send event, scheduled when the packet at the head of 295 * the outbound queue is ready to transmit (for timing 296 * accesses only). 297 */ 298 void trySend(); 299 300 /** 301 * Private class for scheduling sending of requests from the 302 * request queue. 303 */ 304 class SendEvent : public Event 305 { 306 BridgeMasterPort *port; 307 308 public: 309 SendEvent(BridgeMasterPort *p) : port(p) {} 310 virtual void process() { port->trySend(); } 311 virtual const char *description() const { return "bridge send"; } 312 }; 313 314 /** Send event for the request queue. */ 315 SendEvent sendEvent; 316 317 public: 318 319 /** 320 * Constructor for the BridgeMasterPort. 321 * 322 * @param _name the port name including the owner 323 * @param _bridge the structural owner 324 * @param _slavePort the slave port on the other side of the bridge 325 * @param _delay the delay from seeing a request to sending it 326 * @param _req_limit the size of the request queue 327 */ 328 BridgeMasterPort(const std::string &_name, Bridge *_bridge, 329 BridgeSlavePort* _slavePort, int _delay, 330 int _req_limit); 331 332 /** 333 * Is this side blocked from accepting new request packets. 334 * 335 * @return true if the occupied space has reached the set limit 336 */ 337 bool reqQueueFull(); 338 339 /** 340 * Queue a request packet to be sent out later and also schedule 341 * a send if necessary. 342 * 343 * @param pkt a request to send out after a delay 344 */ 345 void queueForSendTiming(PacketPtr pkt); 346 347 /** 348 * Check a functional request against the packets in our 349 * request queue. 350 * 351 * @param pkt packet to check against 352 * 353 * @return true if we find a match 354 */ 355 bool checkFunctional(PacketPtr pkt); 356 357 protected: 358 359 /** When receiving a timing request from the peer port, 360 pass it to the bridge. */ 361 virtual bool recvTiming(PacketPtr pkt); 362 363 /** When receiving a retry request from the peer port, 364 pass it to the bridge. */ 365 virtual void recvRetry(); 366 367 /** When receiving a Atomic requestfrom the peer port, 368 pass it to the bridge. */ 369 virtual Tick recvAtomic(PacketPtr pkt); 370 371 /** When receiving a Functional request from the peer port, 372 pass it to the bridge. */ 373 virtual void recvFunctional(PacketPtr pkt); 374 375 /** 376 * When receiving a range change, pass it through the bridge. 377 */ 378 virtual void recvRangeChange(); 379 }; 380 381 /** Slave port of the bridge. */ 382 BridgeSlavePort slavePort; 383 384 /** Master port of the bridge. */ 385 BridgeMasterPort masterPort; 386 387 /** If this bridge should acknowledge writes. */ 388 bool ackWrites; 389 390 public: 391 typedef BridgeParams Params; 392 393 protected: 394 Params *_params; 395 396 public: 397 const Params *params() const { return _params; } 398 399 /** A function used to return the port associated with this bus object. */ 400 virtual Port *getPort(const std::string &if_name, int idx = -1); 401 402 virtual void init(); 403 404 Bridge(Params *p); 405}; 406 407#endif //__MEM_BUS_HH__ 408