x86_pit.c
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/*
* Copyright (C) 2014 René Kijewski <rene.kijewski@fu-berlin.de>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @ingroup x86-irq
* @{
*
* @file
* @brief Configuration and interrupt handling for the Programmable Interval Timer (PIT).
*
* @author René Kijewski <rene.kijewski@fu-berlin.de>
*
* @}
*/
#include "x86_interrupts.h"
#include "x86_pit.h"
#include "x86_ports.h"
#include "cpu.h"
#include "irq.h"
#include <stdio.h>
void x86_init_pit(void)
{
puts("PIT initialized");
}
uint16_t x86_pit_read(unsigned channel)
{
unsigned old_flags = irq_disable();
outb(PIT_COMMAND_PORT, (channel - 1) << 6 | PIT_ACCESS_MODE_LATCH_COUNT);
uint16_t lohi = inb(PIT_CHANNEL_0_PORT + channel - 1);
lohi += inb(PIT_CHANNEL_0_PORT + channel - 1) << 8;
irq_restore(old_flags);
return lohi;
}
void x86_pit_set2(unsigned channel, unsigned mode, uint16_t max)
{
unsigned old_flags = irq_disable();
outb(PIT_COMMAND_PORT, ((channel - 1) << 6) | mode | PIT_ACCESS_MODE_LO_HI);
outb(PIT_CHANNEL_0_PORT + channel - 1, max & 0xff);
outb(PIT_CHANNEL_0_PORT + channel - 1, max >> 8);
irq_restore(old_flags);
}
bool x86_pit_set(unsigned channel, unsigned mode, unsigned hz)
{
if (PIT_MIN_HZ > hz || hz > PIT_MAX_HZ) {
return false;
}
uint16_t max = PIT_MAX_HZ / hz;
x86_pit_set2(channel, mode, max);
return true;
}