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/*
* linux/arch/arm/mach-footbridge/isa-timer.c
*
* Copyright (C) 1998 Russell King.
* Copyright (C) 1998 Phil Blundell
*/
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/timex.h>
#include <asm/irq.h>
#include <asm/mach/time.h>
#include "common.h"
#define PIT_MODE 0x43
#define PIT_CH0 0x40
#define PIT_LATCH ((PIT_TICK_RATE + HZ / 2) / HZ)
static cycle_t pit_read(struct clocksource *cs)
{
unsigned long flags;
static int old_count;
static u32 old_jifs;
int count;
u32 jifs;
raw_local_irq_save(flags);
jifs = jiffies;
outb_p(0x00, PIT_MODE); /* latch the count */
count = inb_p(PIT_CH0); /* read the latched count */
count |= inb_p(PIT_CH0) << 8;
if (count > old_count && jifs == old_jifs)
count = old_count;
old_count = count;
old_jifs = jifs;
raw_local_irq_restore(flags);
count = (PIT_LATCH - 1) - count;
return (cycle_t)(jifs * PIT_LATCH) + count;
}
static struct clocksource pit_cs = {
.name = "pit",
.rating = 110,
.read = pit_read,
.mask = CLOCKSOURCE_MASK(32),
};
static void pit_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
unsigned long flags;
raw_local_irq_save(flags);
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
outb_p(0x34, PIT_MODE);
outb_p(PIT_LATCH & 0xff, PIT_CH0);
outb_p(PIT_LATCH >> 8, PIT_CH0);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
outb_p(0x30, PIT_MODE);
outb_p(0, PIT_CH0);
outb_p(0, PIT_CH0);
break;
case CLOCK_EVT_MODE_ONESHOT:
case CLOCK_EVT_MODE_RESUME:
break;
}
local_irq_restore(flags);
}
static int pit_set_next_event(unsigned long delta,
struct clock_event_device *evt)
{
return 0;
}
static struct clock_event_device pit_ce = {
.name = "pit",
.features = CLOCK_EVT_FEAT_PERIODIC,
.set_mode = pit_set_mode,
.set_next_event = pit_set_next_event,
.shift = 32,
};
static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *ce = dev_id;
ce->event_handler(ce);
return IRQ_HANDLED;
}
static struct irqaction pit_timer_irq = {
.name = "pit",
.handler = pit_timer_interrupt,
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.dev_id = &pit_ce,
};
static void __init isa_timer_init(void)
{
pit_ce.cpumask = cpumask_of(smp_processor_id());
pit_ce.mult = div_sc(PIT_TICK_RATE, NSEC_PER_SEC, pit_ce.shift);
pit_ce.max_delta_ns = clockevent_delta2ns(0x7fff, &pit_ce);
pit_ce.min_delta_ns = clockevent_delta2ns(0x000f, &pit_ce);
clocksource_register_hz(&pit_cs, PIT_TICK_RATE);
setup_irq(pit_ce.irq, &pit_timer_irq);
clockevents_register_device(&pit_ce);
}
struct sys_timer isa_timer = {
.init = isa_timer_init,
};
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