tport.cc revision 3263 
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
33void
34SimpleTimingPort::recvFunctional(Packet *pkt)
35{
36    // just do an atomic access and throw away the returned latency
37    recvAtomic(pkt);
38}
39
40bool
41SimpleTimingPort::recvTiming(Packet *pkt)
42{
43    // If the device is only a slave, it should only be sending
44    // responses, which should never get nacked.  There used to be
45    // code to hanldle nacks here, but I'm pretty sure it didn't work
46    // correctly with the drain code, so that would need to be fixed
47    // if we ever added it back.
48    assert(pkt->result != Packet::Nacked);
49    Tick latency = recvAtomic(pkt);
50    // turn packet around to go back to requester if response expected
51    if (pkt->needsResponse()) {
52        pkt->makeTimingResponse();
53        sendTimingLater(pkt, latency);
54    }
55    return true;
56}
57
58void
59SimpleTimingPort::recvRetry()
60{
61    assert(outTiming > 0);
62    assert(!transmitList.empty());
63    if (sendTiming(transmitList.front())) {
64        transmitList.pop_front();
65        outTiming--;
66        DPRINTF(Bus, "No Longer waiting on retry\n");
67        if (!transmitList.empty())
68            sendTimingLater(transmitList.front(), 1);
69    }
70
71    if (transmitList.empty() && drainEvent) {
72        drainEvent->process();
73        drainEvent = NULL;
74    }
75}
76
77void
78SimpleTimingPort::SendEvent::process()
79{
80    assert(port->outTiming > 0);
81    if (!port->transmitList.empty() && port->transmitList.front() != packet) {
82        //We are not the head of the list
83        port->transmitList.push_back(packet);
84    } else if (port->sendTiming(packet)) {
85        // send successful
86        if (port->transmitList.size()) {
87            port->transmitList.pop_front();
88            port->outTiming--;
89           if (!port->transmitList.empty())
90                port->sendTimingLater(port->transmitList.front(), 1);
91        }
92        if (port->transmitList.empty() && port->drainEvent) {
93            port->drainEvent->process();
94            port->drainEvent = NULL;
95        }
96    } else {
97        // send unsuccessful (due to flow control).  Will get retry
98        // callback later; save for then if not already
99        DPRINTF(Bus, "Waiting on retry\n");
100        if (!(port->transmitList.front() == packet))
101            port->transmitList.push_back(packet);
102    }
103}
104
105
106unsigned int
107SimpleTimingPort::drain(Event *de)
108{
109    if (outTiming == 0 && transmitList.size() == 0)
110        return 0;
111    drainEvent = de;
112    return 1;
113}
114