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