1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
/*
* Copyright (c) 2006 The Regents of The University of Michigan
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Ali Saidi
*/
#ifndef __MEM_TPORT_HH__
#define __MEM_TPORT_HH__
/**
* @file
*
* Declaration of SimpleTimingPort.
*/
#include "mem/port.hh"
#include "sim/eventq.hh"
#include <list>
#include <string>
/**
* A simple port for interfacing objects that basically have only
* functional memory behavior (e.g. I/O devices) to the memory system.
* Both timing and functional accesses are implemented in terms of
* atomic accesses. A derived port class thus only needs to provide
* recvAtomic() to support all memory access modes.
*
* The tricky part is handling recvTiming(), where the response must
* be scheduled separately via a later call to sendTiming(). This
* feature is handled by scheduling an internal event that calls
* sendTiming() after a delay, and optionally rescheduling the
* response if it is nacked.
*/
class SimpleTimingPort : public Port
{
protected:
/** A deferred packet, buffered to transmit later. */
class DeferredPacket {
public:
Tick tick; ///< The tick when the packet is ready to transmit
PacketPtr pkt; ///< Pointer to the packet to transmit
DeferredPacket(Tick t, PacketPtr p)
: tick(t), pkt(p)
{}
};
typedef std::list<DeferredPacket> DeferredPacketList;
typedef std::list<DeferredPacket>::iterator DeferredPacketIterator;
/** A list of outgoing timing response packets that haven't been
* serviced yet. */
DeferredPacketList transmitList;
/** This function attempts to send deferred packets. Scheduled to
* be called in the future via SendEvent. */
void processSendEvent();
/**
* This class is used to implemented sendTiming() with a delay. When
* a delay is requested a the event is scheduled if it isn't already.
* When the event time expires it attempts to send the packet.
* If it cannot, the packet sent when recvRetry() is called.
**/
typedef EventWrapper<SimpleTimingPort, &SimpleTimingPort::processSendEvent>
SendEvent;
Event *sendEvent;
/** If we need to drain, keep the drain event around until we're done
* here.*/
Event *drainEvent;
/** Remember whether we're awaiting a retry from the bus. */
bool waitingOnRetry;
/** Check the list of buffered packets against the supplied
* functional request. */
void checkFunctional(PacketPtr funcPkt);
/** Check whether we have a packet ready to go on the transmit list. */
bool deferredPacketReady()
{ return !transmitList.empty() && transmitList.front().tick <= curTick; }
Tick deferredPacketReadyTick()
{ return transmitList.empty() ? MaxTick : transmitList.front().tick; }
void schedSendEvent(Tick when)
{
if (waitingOnRetry) {
assert(!sendEvent->scheduled());
return;
}
if (!sendEvent->scheduled()) {
sendEvent->schedule(when);
} else if (sendEvent->when() > when) {
sendEvent->reschedule(when);
}
}
/** Schedule a sendTiming() event to be called in the future.
* @param pkt packet to send
* @param absolute time (in ticks) to send packet
*/
void schedSendTiming(PacketPtr pkt, Tick when);
/** Attempt to send the packet at the head of the deferred packet
* list. Caller must guarantee that the deferred packet list is
* non-empty and that the head packet is scheduled for curTick (or
* earlier).
*/
void sendDeferredPacket();
/** This function is notification that the device should attempt to send a
* packet again. */
virtual void recvRetry();
/** Implemented using recvAtomic(). */
void recvFunctional(PacketPtr pkt);
/** Implemented using recvAtomic(). */
bool recvTiming(PacketPtr pkt);
/**
* Simple ports generally don't care about any status
* changes... can always override this in cases where that's not
* true. */
virtual void recvStatusChange(Status status) { }
public:
SimpleTimingPort(std::string pname, MemObject *_owner = NULL)
: Port(pname, _owner),
sendEvent(new SendEvent(this)),
drainEvent(NULL),
waitingOnRetry(false)
{}
~SimpleTimingPort() { delete sendEvent; }
/** Hook for draining timing accesses from the system. The
* associated SimObject's drain() functions should be implemented
* something like this when this class is used:
\code
PioDevice::drain(Event *de)
{
unsigned int count;
count = SimpleTimingPort->drain(de);
if (count)
changeState(Draining);
else
changeState(Drained);
return count;
}
\endcode
*/
unsigned int drain(Event *de);
};
#endif // __MEM_TPORT_HH__
|
