gem5/src/dev/intel_8254_timer.cc

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/*
* Copyright (c) 2004, 2005
* The Regents of The University of Michigan
* All Rights Reserved
*
* This code is part of the M5 simulator.
*
* Permission is granted to use, copy, create derivative works and
* redistribute this software and such derivative works for any
* purpose, so long as the copyright notice above, this grant of
* permission, and the disclaimer below appear in all copies made; and
* so long as the name of The University of Michigan is not used in
* any advertising or publicity pertaining to the use or distribution
* of this software without specific, written prior authorization.
*
* THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION FROM THE
* UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY PURPOSE, AND
* WITHOUT WARRANTY BY THE UNIVERSITY OF MICHIGAN OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE. THE REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE
* LIABLE FOR ANY DAMAGES, INCLUDING DIRECT, SPECIAL, INDIRECT,
* INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM
* ARISING OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
* IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGES.
*
* Authors: Ali G. Saidi
* Andrew L. Schultz
* Miguel J. Serrano
*/
#include "base/misc.hh"
#include "dev/intel_8254_timer.hh"
using namespace std;
Intel8254Timer::Intel8254Timer(EventManager *em, const string &name,
Counter *counter0, Counter *counter1, Counter *counter2) :
EventManager(em), _name(name)
{
counter[0] = counter0;
counter[1] = counter1;
counter[2] = counter2;
}
Intel8254Timer::Intel8254Timer(EventManager *em, const string &name) :
EventManager(em), _name(name)
{
counter[0] = new Counter(this, name + ".counter0", 0);
counter[1] = new Counter(this, name + ".counter1", 1);
counter[2] = new Counter(this, name + ".counter2", 2);
}
void
Intel8254Timer::writeControl(const CtrlReg data)
{
int sel = data.sel;
if (sel == ReadBackCommand)
panic("PITimer Read-Back Command is not implemented.\n");
if (data.rw == LatchCommand)
counter[sel]->latchCount();
else {
counter[sel]->setRW(data.rw);
counter[sel]->setMode(data.mode);
counter[sel]->setBCD(data.bcd);
}
}
void
Intel8254Timer::serialize(const string &base, ostream &os)
{
// serialize the counters
counter[0]->serialize(base + ".counter0", os);
counter[1]->serialize(base + ".counter1", os);
counter[2]->serialize(base + ".counter2", os);
}
void
Intel8254Timer::unserialize(const string &base, Checkpoint *cp,
const string &section)
{
// unserialze the counters
counter[0]->unserialize(base + ".counter0", cp, section);
counter[1]->unserialize(base + ".counter1", cp, section);
counter[2]->unserialize(base + ".counter2", cp, section);
}
Intel8254Timer::Counter::Counter(Intel8254Timer *p,
const string &name, unsigned int _num)
: _name(name), num(_num), event(this), initial_count(0),
latched_count(0), period(0), mode(0), output_high(false),
latch_on(false), read_byte(LSB), write_byte(LSB), parent(p)
{
}
void
Intel8254Timer::Counter::latchCount()
{
// behave like a real latch
if(!latch_on) {
latch_on = true;
read_byte = LSB;
latched_count = currentCount();
}
}
int
Intel8254Timer::Counter::currentCount()
{
int clocks = event.clocksLeft();
if (clocks == -1) {
warn_once("Reading current count from inactive timer.\n");
return 0;
}
if (mode == RateGen || mode == SquareWave)
return clocks + 1;
else
return clocks;
}
uint8_t
Intel8254Timer::Counter::read()
{
if (latch_on) {
switch (read_byte) {
case LSB:
read_byte = MSB;
return (uint8_t)latched_count;
break;
case MSB:
read_byte = LSB;
latch_on = false;
return latched_count >> 8;
break;
default:
panic("Shouldn't be here");
}
} else {
uint16_t count = currentCount();
switch (read_byte) {
case LSB:
read_byte = MSB;
return (uint8_t)count;
break;
case MSB:
read_byte = LSB;
return count >> 8;
break;
default:
panic("Shouldn't be here");
}
}
}
void
Intel8254Timer::Counter::write(const uint8_t data)
{
switch (write_byte) {
case LSB:
initial_count = (initial_count & 0xFF00) | data;
if (event.scheduled())
parent->deschedule(event);
output_high = false;
write_byte = MSB;
break;
case MSB:
initial_count = (initial_count & 0x00FF) | (data << 8);
// In the RateGen or SquareWave modes, the timer wraps around and
// triggers on a value of 1, not 0.
if (mode == RateGen || mode == SquareWave)
period = initial_count - 1;
else
period = initial_count;
if (period > 0)
event.setTo(period);
write_byte = LSB;
break;
}
}
void
Intel8254Timer::Counter::setRW(int rw_val)
{
if (rw_val != TwoPhase)
panic("Only LSB/MSB read/write is implemented.\n");
}
void
Intel8254Timer::Counter::setMode(int mode_val)
{
if(mode_val != InitTc && mode_val != RateGen &&
mode_val != SquareWave)
panic("PIT mode %#x is not implemented: \n", mode_val);
mode = mode_val;
}
void
Intel8254Timer::Counter::setBCD(int bcd_val)
{
if (bcd_val)
panic("PITimer does not implement BCD counts.\n");
}
bool
Intel8254Timer::Counter::outputHigh()
{
return output_high;
}
void
Intel8254Timer::Counter::serialize(const string &base, ostream &os)
{
paramOut(os, base + ".initial_count", initial_count);
paramOut(os, base + ".latched_count", latched_count);
paramOut(os, base + ".period", period);
paramOut(os, base + ".mode", mode);
paramOut(os, base + ".output_high", output_high);
paramOut(os, base + ".latch_on", latch_on);
paramOut(os, base + ".read_byte", read_byte);
paramOut(os, base + ".write_byte", write_byte);
Tick event_tick = 0;
if (event.scheduled())
event_tick = event.when();
paramOut(os, base + ".event_tick", event_tick);
}
void
Intel8254Timer::Counter::unserialize(const string &base, Checkpoint *cp,
const string &section)
{
paramIn(cp, section, base + ".initial_count", initial_count);
paramIn(cp, section, base + ".latched_count", latched_count);
paramIn(cp, section, base + ".period", period);
paramIn(cp, section, base + ".mode", mode);
paramIn(cp, section, base + ".output_high", output_high);
paramIn(cp, section, base + ".latch_on", latch_on);
paramIn(cp, section, base + ".read_byte", read_byte);
paramIn(cp, section, base + ".write_byte", write_byte);
Tick event_tick;
paramIn(cp, section, base + ".event_tick", event_tick);
if (event_tick)
parent->schedule(event, event_tick);
}
Intel8254Timer::Counter::CounterEvent::CounterEvent(Counter* c_ptr)
{
interval = (Tick)(SimClock::Float::s / 1193180.0);
counter = c_ptr;
}
void
Intel8254Timer::Counter::CounterEvent::process()
{
switch (counter->mode) {
case InitTc:
counter->output_high = true;
break;
case RateGen:
case SquareWave:
setTo(counter->period);
break;
default:
panic("Unimplemented PITimer mode.\n");
}
counter->parent->counterInterrupt(counter->num);
}
void
Intel8254Timer::Counter::CounterEvent::setTo(int clocks)
{
if (clocks == 0)
panic("Timer can't be set to go off instantly.\n");
DPRINTF(Intel8254Timer, "Timer set to curTick + %d\n",
clocks * interval);
counter->parent->schedule(this, curTick + clocks * interval);
}
int
Intel8254Timer::Counter::CounterEvent::clocksLeft()
{
if (!scheduled())
return -1;
return (when() - curTick + interval - 1) / interval;
}
const char *
Intel8254Timer::Counter::CounterEvent::description() const
{
return "Intel 8254 Interval timer";
}