tport.cc revision 5693:4bf6f614871b 
1/*
2 * Copyright (c) 2006 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Ali Saidi
29 */
30
31#include "mem/tport.hh"
32
33bool
34SimpleTimingPort::checkFunctional(PacketPtr pkt)
35{
36    DeferredPacketIterator i = transmitList.begin();
37    DeferredPacketIterator end = transmitList.end();
38
39    for (; i != end; ++i) {
40        PacketPtr target = i->pkt;
41        // If the target contains data, and it overlaps the
42        // probed request, need to update data
43        if (pkt->checkFunctional(target)) {
44            return true;
45        }
46    }
47
48    return false;
49}
50
51void
52SimpleTimingPort::recvFunctional(PacketPtr pkt)
53{
54    if (!checkFunctional(pkt)) {
55        // Just do an atomic access and throw away the returned latency
56        recvAtomic(pkt);
57    }
58}
59
60bool
61SimpleTimingPort::recvTiming(PacketPtr pkt)
62{
63    // If the device is only a slave, it should only be sending
64    // responses, which should never get nacked.  There used to be
65    // code to hanldle nacks here, but I'm pretty sure it didn't work
66    // correctly with the drain code, so that would need to be fixed
67    // if we ever added it back.
68
69    if (pkt->memInhibitAsserted()) {
70        // snooper will supply based on copy of packet
71        // still target's responsibility to delete packet
72        delete pkt;
73        return true;
74    }
75
76    bool needsResponse = pkt->needsResponse();
77    Tick latency = recvAtomic(pkt);
78    // turn packet around to go back to requester if response expected
79    if (needsResponse) {
80        // recvAtomic() should already have turned packet into
81        // atomic response
82        assert(pkt->isResponse());
83        schedSendTiming(pkt, curTick + latency);
84    } else {
85        delete pkt;
86    }
87
88    return true;
89}
90
91
92void
93SimpleTimingPort::schedSendTiming(PacketPtr pkt, Tick when)
94{
95    assert(when > curTick);
96    assert(when < curTick + Clock::Int::ms);
97
98    // Nothing is on the list: add it and schedule an event
99    if (transmitList.empty() || when < transmitList.front().tick) {
100        transmitList.push_front(DeferredPacket(when, pkt));
101        schedSendEvent(when);
102        return;
103    }
104
105    // list is non-empty & this belongs at the end
106    if (when >= transmitList.back().tick) {
107        transmitList.push_back(DeferredPacket(when, pkt));
108        return;
109    }
110
111    // this belongs in the middle somewhere
112    DeferredPacketIterator i = transmitList.begin();
113    i++; // already checked for insertion at front
114    DeferredPacketIterator end = transmitList.end();
115
116    for (; i != end; ++i) {
117        if (when < i->tick) {
118            transmitList.insert(i, DeferredPacket(when, pkt));
119            return;
120        }
121    }
122    assert(false); // should never get here
123}
124
125
126void
127SimpleTimingPort::sendDeferredPacket()
128{
129    assert(deferredPacketReady());
130    // take packet off list here; if recvTiming() on the other side
131    // calls sendTiming() back on us (like SimpleTimingCpu does), then
132    // we get confused by having a non-active packet on transmitList
133    DeferredPacket dp = transmitList.front();
134    transmitList.pop_front();
135    bool success = sendTiming(dp.pkt);
136
137    if (success) {
138        if (!transmitList.empty() && !sendEvent->scheduled()) {
139            Tick time = transmitList.front().tick;
140            schedule(sendEvent, time <= curTick ? curTick+1 : time);
141        }
142
143        if (transmitList.empty() && drainEvent) {
144            drainEvent->process();
145            drainEvent = NULL;
146        }
147    } else {
148        // Unsuccessful, need to put back on transmitList.  Callee
149        // should not have messed with it (since it didn't accept that
150        // packet), so we can just push it back on the front.
151        assert(!sendEvent->scheduled());
152        transmitList.push_front(dp);
153    }
154
155    waitingOnRetry = !success;
156
157    if (waitingOnRetry) {
158        DPRINTF(Bus, "Send failed, waiting on retry\n");
159    }
160}
161
162
163void
164SimpleTimingPort::recvRetry()
165{
166    DPRINTF(Bus, "Received retry\n");
167    assert(waitingOnRetry);
168    sendDeferredPacket();
169}
170
171
172void
173SimpleTimingPort::processSendEvent()
174{
175    assert(!waitingOnRetry);
176    sendDeferredPacket();
177}
178
179
180unsigned int
181SimpleTimingPort::drain(Event *de)
182{
183    if (transmitList.size() == 0)
184        return 0;
185    drainEvent = de;
186    return 1;
187}
188