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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/arm/mach-footbridge/isa-timer.c
10817 views
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/*

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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/spinlock.h>

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#include <linux/timex.h>

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#include <asm/irq.h>

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#include <asm/i8253.h>

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#include <asm/mach/time.h>

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#include "common.h"

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DEFINE_RAW_SPINLOCK(i8253_lock);

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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_i8253_init();

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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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