/*
* Copyright (c) 2001-2004 Jakub Jermar
* 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
/** @addtogroup kernel_ia32
* @{
*/
/**
* @file
* @brief i8254 chip driver.
*
* Low level time functions.
*/
#include <stdint.h>
#include <time/clock.h>
#include <time/delay.h>
#include <arch/cycle.h>
#include <arch/interrupt.h>
#include <genarch/drivers/i8259/i8259.h>
#include <arch/drivers/i8254.h>
#include <cpu.h>
#include <config.h>
#include <arch/pm.h>
#include <arch/asm.h>
#include <arch/cpuid.h>
#include <arch.h>
#include <ddi/irq.h>
#define CLK_PORT1 ((ioport8_t *) 0x40U)
#define CLK_PORT4 ((ioport8_t *) 0x43U)
#define CLK_CONST 1193180
#define MAGIC_NUMBER 1194
#define LOOPS 150000
#define SHIFT 11
static irq_t i8254_irq;
static irq_ownership_t i8254_claim(irq_t *irq)
{
return IRQ_ACCEPT;
}
static void i8254_irq_handler(irq_t *irq)
{
/*
* This IRQ is responsible for kernel preemption.
* Nevertheless, we are now holding a spinlock which prevents
* preemption. For this particular IRQ, we don't need the
* lock. We just release it, call clock() and then reacquire it again.
*/
irq_spinlock_unlock(&irq->lock, false);
clock();
irq_spinlock_lock(&irq->lock, false);
}
void i8254_init(void)
{
irq_initialize(&i8254_irq);
i8254_irq.preack = true;
i8254_irq.inr = IRQ_CLK;
i8254_irq.claim = i8254_claim;
i8254_irq.handler = i8254_irq_handler;
irq_register(&i8254_irq);
i8254_normal_operation();
}
void i8254_normal_operation(void)
{
pio_write_8(CLK_PORT4, 0x36);
i8259_disable_irqs(1 << IRQ_CLK);
pio_write_8(CLK_PORT1, (CLK_CONST / HZ) & 0xf);
pio_write_8(CLK_PORT1, (CLK_CONST / HZ) >> 8);
i8259_enable_irqs(1 << IRQ_CLK);
}
void i8254_calibrate_delay_loop(void)
{
/*
* One-shot timer. Count-down from 0xffff at 1193180Hz
* MAGIC_NUMBER is the magic value for 1ms.
*/
pio_write_8(CLK_PORT4, 0x30);
pio_write_8(CLK_PORT1, 0xff);
pio_write_8(CLK_PORT1, 0xff);
uint8_t not_ok;
uint32_t t1;
uint32_t t2;
do {
/* will read both status and count */
pio_write_8(CLK_PORT4, 0xc2);
not_ok = (uint8_t) ((pio_read_8(CLK_PORT1) >> 6) & 1);
t1 = pio_read_8(CLK_PORT1);
t1 |= pio_read_8(CLK_PORT1) << 8;
} while (not_ok);
asm_delay_loop(LOOPS);
pio_write_8(CLK_PORT4, 0xd2);
t2 = pio_read_8(CLK_PORT1);
t2 |= pio_read_8(CLK_PORT1) << 8;
/*
* We want to determine the overhead of the calibrating mechanism.
*/
pio_write_8(CLK_PORT4, 0xd2);
uint32_t o1 = pio_read_8(CLK_PORT1);
o1 |= pio_read_8(CLK_PORT1) << 8;
asm_fake_loop(LOOPS);
pio_write_8(CLK_PORT4, 0xd2);
uint32_t o2 = pio_read_8(CLK_PORT1);
o2 |= pio_read_8(CLK_PORT1) << 8;
uint32_t delta = (t1 - t2) - (o1 - o2);
if (!delta)
delta = 1;
CPU->delay_loop_const =
((MAGIC_NUMBER * LOOPS) / 1000) / delta +
(((MAGIC_NUMBER * LOOPS) / 1000) % delta ? 1 : 0);
uint64_t clk1 = get_cycle();
delay(1 << SHIFT);
uint64_t clk2 = get_cycle();
CPU->frequency_mhz = (clk2 - clk1) >> SHIFT;
return;
}
/** @}
*/