bridge.cc revision 3349:fec4a86fa212 
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    : Port(_name), bridge(_bridge), otherPort(_otherPort),
48      delay(_delay), outstandingResponses(0),
49      queueLimit(_queueLimit), sendEvent(this)
50{
51}
52
53Bridge::Bridge(const std::string &n, int qsa, int qsb,
54               Tick _delay, int write_ack)
55    : MemObject(n),
56      portA(n + "-portA", this, &portB, _delay, qsa),
57      portB(n + "-portB", this, &portA, _delay, qsa),
58      ackWrites(write_ack)
59{
60}
61
62Port *
63Bridge::getPort(const std::string &if_name, int idx)
64{
65    BridgePort *port;
66
67    if (if_name == "side_a")
68        port = &portA;
69    else if (if_name == "side_b")
70        port = &portB;
71    else
72        return NULL;
73
74    if (port->getPeer() != NULL)
75        panic("bridge side %s already connected to.", if_name);
76    return port;
77}
78
79
80void
81Bridge::init()
82{
83    // Make sure that both sides are connected to.
84    if (portA.getPeer() == NULL || portB.getPeer() == NULL)
85        panic("Both ports of bus bridge are not connected to a bus.\n");
86}
87
88
89/** Function called by the port when the bus is receiving a Timing
90 * transaction.*/
91bool
92Bridge::BridgePort::recvTiming(PacketPtr pkt)
93{
94    DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
95            pkt->getSrc(), pkt->getDest(), pkt->getAddr());
96
97    return otherPort->queueForSendTiming(pkt);
98}
99
100
101bool
102Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
103{
104    if (queueFull())
105        return false;
106
107   if (pkt->isResponse()) {
108        // This is a response for a request we forwarded earlier.  The
109        // corresponding PacketBuffer should be stored in the packet's
110        // senderState field.
111        PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
112        assert(buf != NULL);
113        // set up new packet dest & senderState based on values saved
114        // from original request
115        buf->fixResponse(pkt);
116        DPRINTF(BusBridge, "restoring  sender state: %#X, from packet buffer: %#X\n",
117                        pkt->senderState, buf);
118        DPRINTF(BusBridge, "  is response, new dest %d\n", pkt->getDest());
119        delete buf;
120    }
121
122    Tick readyTime = curTick + delay;
123    PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
124    DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
125            buf->origSenderState, buf);
126
127    // If we're about to put this packet at the head of the queue, we
128    // need to schedule an event to do the transmit.  Otherwise there
129    // should already be an event scheduled for sending the head
130    // packet.
131    if (sendQueue.empty()) {
132        sendEvent.schedule(readyTime);
133    }
134
135    sendQueue.push_back(buf);
136
137    return true;
138}
139
140void
141Bridge::BridgePort::trySend()
142{
143    assert(!sendQueue.empty());
144
145    bool was_full = queueFull();
146
147    PacketBuffer *buf = sendQueue.front();
148
149    assert(buf->ready <= curTick);
150
151    PacketPtr pkt = buf->pkt;
152
153    DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
154            buf->origSrc, pkt->getDest(), pkt->getAddr());
155
156    pkt->flags &= ~SNOOP_COMMIT; //CLear it if it was set
157    if (sendTiming(pkt)) {
158        // send successful
159        sendQueue.pop_front();
160        buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it
161
162        if (buf->expectResponse) {
163            // Must wait for response.  We just need to count outstanding
164            // responses (in case we want to cap them); PacketBuffer
165            // pointer will be recovered on response.
166            ++outstandingResponses;
167            DPRINTF(BusBridge, "  successful: awaiting response (%d)\n",
168                    outstandingResponses);
169        } else {
170            // no response expected... deallocate packet buffer now.
171            DPRINTF(BusBridge, "  successful: no response expected\n");
172            delete buf;
173        }
174
175        // If there are more packets to send, schedule event to try again.
176        if (!sendQueue.empty()) {
177            buf = sendQueue.front();
178            sendEvent.schedule(std::max(buf->ready, curTick + 1));
179        }
180        // Let things start sending again
181        if (was_full) {
182          DPRINTF(BusBridge, "Queue was full, sending retry\n");
183          otherPort->sendRetry();
184        }
185
186    } else {
187        DPRINTF(BusBridge, "  unsuccessful\n");
188    }
189}
190
191
192void
193Bridge::BridgePort::recvRetry()
194{
195    trySend();
196}
197
198/** Function called by the port when the bus is receiving a Atomic
199 * transaction.*/
200Tick
201Bridge::BridgePort::recvAtomic(PacketPtr pkt)
202{
203    return otherPort->sendAtomic(pkt) + delay;
204}
205
206/** Function called by the port when the bus is receiving a Functional
207 * transaction.*/
208void
209Bridge::BridgePort::recvFunctional(PacketPtr pkt)
210{
211    std::list<PacketBuffer*>::iterator i;
212    bool pktContinue = true;
213
214    for (i = sendQueue.begin();  i != sendQueue.end(); ++i) {
215        if (pkt->intersect((*i)->pkt)) {
216            pktContinue &= fixPacket(pkt, (*i)->pkt);
217        }
218    }
219
220    if (pktContinue) {
221        otherPort->sendFunctional(pkt);
222    }
223}
224
225/** Function called by the port when the bus is receiving a status change.*/
226void
227Bridge::BridgePort::recvStatusChange(Port::Status status)
228{
229    otherPort->sendStatusChange(status);
230}
231
232void
233Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
234                                           AddrRangeList &snoop)
235{
236    otherPort->getPeerAddressRanges(resp, snoop);
237}
238
239BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)
240
241   Param<int> queue_size_a;
242   Param<int> queue_size_b;
243   Param<Tick> delay;
244   Param<bool> write_ack;
245
246END_DECLARE_SIM_OBJECT_PARAMS(Bridge)
247
248BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)
249
250    INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"),
251    INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"),
252    INIT_PARAM(delay, "The miminum delay to cross this bridge"),
253    INIT_PARAM(write_ack, "Acknowledge any writes that are received.")
254
255END_INIT_SIM_OBJECT_PARAMS(Bridge)
256
257CREATE_SIM_OBJECT(Bridge)
258{
259    return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
260            write_ack);
261}
262
263REGISTER_SIM_OBJECT("Bridge", Bridge)
264