bridge.cc revision 4432:5e55857abb01 
1
2/*
3 * Copyright (c) 2006 The Regents of The University of Michigan
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met: redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer;
10 * redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution;
13 * neither the name of the copyright holders nor the names of its
14 * contributors may be used to endorse or promote products derived from
15 * this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * Authors: Ali Saidi
30 *          Steve Reinhardt
31 */
32
33/**
34 * @file
35 * Definition of a simple bus bridge without buffering.
36 */
37
38#include <algorithm>
39
40#include "base/trace.hh"
41#include "mem/bridge.hh"
42#include "sim/builder.hh"
43
44Bridge::BridgePort::BridgePort(const std::string &_name,
45                               Bridge *_bridge, BridgePort *_otherPort,
46                               int _delay, int _queueLimit,
47                               bool fix_partial_write)
48    : Port(_name), bridge(_bridge), otherPort(_otherPort),
49      delay(_delay), fixPartialWrite(fix_partial_write),
50      outstandingResponses(0), queueLimit(_queueLimit), sendEvent(this)
51{
52}
53
54Bridge::Bridge(const std::string &n, int qsa, int qsb,
55               Tick _delay, int write_ack, bool fix_partial_write_a,
56               bool fix_partial_write_b)
57    : MemObject(n),
58      portA(n + "-portA", this, &portB, _delay, qsa, fix_partial_write_a),
59      portB(n + "-portB", this, &portA, _delay, qsa, fix_partial_write_b),
60      ackWrites(write_ack)
61{
62    if (ackWrites)
63        panic("No support for acknowledging writes\n");
64}
65
66Port *
67Bridge::getPort(const std::string &if_name, int idx)
68{
69    BridgePort *port;
70
71    if (if_name == "side_a")
72        port = &portA;
73    else if (if_name == "side_b")
74        port = &portB;
75    else
76        return NULL;
77
78    if (port->getPeer() != NULL)
79        panic("bridge side %s already connected to.", if_name);
80    return port;
81}
82
83
84void
85Bridge::init()
86{
87    // Make sure that both sides are connected to.
88    if (portA.getPeer() == NULL || portB.getPeer() == NULL)
89        fatal("Both ports of bus bridge are not connected to a bus.\n");
90
91    if (portA.peerBlockSize() != portB.peerBlockSize())
92        fatal("Busses don't have the same block size... Not supported.\n");
93}
94
95
96/** Function called by the port when the bus is receiving a Timing
97 * transaction.*/
98bool
99Bridge::BridgePort::recvTiming(PacketPtr pkt)
100{
101    if (pkt->flags & SNOOP_COMMIT) {
102        DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
103                pkt->getSrc(), pkt->getDest(), pkt->getAddr());
104
105        return otherPort->queueForSendTiming(pkt);
106    }
107    else {
108        // Else it's just a snoop, properly return if we are blocking
109        return !queueFull();
110    }
111}
112
113
114bool
115Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
116{
117    if (queueFull()) {
118        DPRINTF(BusBridge, "Queue full, returning false\n");
119        return false;
120    }
121
122   if (pkt->isResponse()) {
123        // This is a response for a request we forwarded earlier.  The
124        // corresponding PacketBuffer should be stored in the packet's
125        // senderState field.
126        PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
127        assert(buf != NULL);
128        // set up new packet dest & senderState based on values saved
129        // from original request
130        buf->fixResponse(pkt);
131        DPRINTF(BusBridge, "restoring  sender state: %#X, from packet buffer: %#X\n",
132                        pkt->senderState, buf);
133        DPRINTF(BusBridge, "  is response, new dest %d\n", pkt->getDest());
134        delete buf;
135    }
136
137    Tick readyTime = curTick + delay;
138    PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
139    DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
140            buf->origSenderState, buf);
141
142    // If we're about to put this packet at the head of the queue, we
143    // need to schedule an event to do the transmit.  Otherwise there
144    // should already be an event scheduled for sending the head
145    // packet.
146    if (sendQueue.empty()) {
147        sendEvent.schedule(readyTime);
148    }
149
150    sendQueue.push_back(buf);
151
152    return true;
153}
154
155void
156Bridge::BridgePort::trySend()
157{
158    assert(!sendQueue.empty());
159
160    bool was_full = queueFull();
161    int pbs = peerBlockSize();
162
163    PacketBuffer *buf = sendQueue.front();
164
165    assert(buf->ready <= curTick);
166
167    PacketPtr pkt = buf->pkt;
168
169    pkt->flags &= ~SNOOP_COMMIT; //CLear it if it was set
170
171    if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite &&
172            pkt->getOffset(pbs) && pkt->getSize() != pbs) {
173        buf->partialWriteFix(this);
174        pkt = buf->pkt;
175    }
176
177    DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
178            buf->origSrc, pkt->getDest(), pkt->getAddr());
179
180
181    if (sendTiming(pkt)) {
182        // send successful
183        sendQueue.pop_front();
184        buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it
185
186        if (buf->expectResponse) {
187            // Must wait for response.  We just need to count outstanding
188            // responses (in case we want to cap them); PacketBuffer
189            // pointer will be recovered on response.
190            ++outstandingResponses;
191            DPRINTF(BusBridge, "  successful: awaiting response (%d)\n",
192                    outstandingResponses);
193        } else {
194            // no response expected... deallocate packet buffer now.
195            DPRINTF(BusBridge, "  successful: no response expected\n");
196            delete buf;
197        }
198
199        // If there are more packets to send, schedule event to try again.
200        if (!sendQueue.empty()) {
201            buf = sendQueue.front();
202            sendEvent.schedule(std::max(buf->ready, curTick + 1));
203        }
204        // Let things start sending again
205        if (was_full) {
206          DPRINTF(BusBridge, "Queue was full, sending retry\n");
207          otherPort->sendRetry();
208        }
209
210    } else {
211        DPRINTF(BusBridge, "  unsuccessful\n");
212        buf->undoPartialWriteFix();
213    }
214}
215
216
217void
218Bridge::BridgePort::recvRetry()
219{
220    trySend();
221}
222
223/** Function called by the port when the bus is receiving a Atomic
224 * transaction.*/
225Tick
226Bridge::BridgePort::recvAtomic(PacketPtr pkt)
227{
228    return otherPort->sendAtomic(pkt) + delay;
229}
230
231/** Function called by the port when the bus is receiving a Functional
232 * transaction.*/
233void
234Bridge::BridgePort::recvFunctional(PacketPtr pkt)
235{
236    std::list<PacketBuffer*>::iterator i;
237    bool pktContinue = true;
238
239    for (i = sendQueue.begin();  i != sendQueue.end(); ++i) {
240        if (pkt->intersect((*i)->pkt)) {
241            pktContinue &= fixPacket(pkt, (*i)->pkt);
242        }
243    }
244
245    if (pktContinue) {
246        otherPort->sendFunctional(pkt);
247    }
248}
249
250/** Function called by the port when the bus is receiving a status change.*/
251void
252Bridge::BridgePort::recvStatusChange(Port::Status status)
253{
254    otherPort->sendStatusChange(status);
255}
256
257void
258Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
259                                           AddrRangeList &snoop)
260{
261    otherPort->getPeerAddressRanges(resp, snoop);
262}
263
264BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)
265
266   Param<int> queue_size_a;
267   Param<int> queue_size_b;
268   Param<Tick> delay;
269   Param<bool> write_ack;
270   Param<bool> fix_partial_write_a;
271   Param<bool> fix_partial_write_b;
272
273END_DECLARE_SIM_OBJECT_PARAMS(Bridge)
274
275BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)
276
277    INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"),
278    INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"),
279    INIT_PARAM(delay, "The miminum delay to cross this bridge"),
280    INIT_PARAM(write_ack, "Acknowledge any writes that are received."),
281    INIT_PARAM(fix_partial_write_a, "Fixup any partial block writes that are received"),
282    INIT_PARAM(fix_partial_write_b, "Fixup any partial block writes that are received")
283
284END_INIT_SIM_OBJECT_PARAMS(Bridge)
285
286CREATE_SIM_OBJECT(Bridge)
287{
288    return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
289            write_ack, fix_partial_write_a, fix_partial_write_b);
290}
291
292REGISTER_SIM_OBJECT("Bridge", Bridge)
293