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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/arm/common/time-acorn.c
10817 views
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/*

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 *  linux/arch/arm/common/time-acorn.c

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 *

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 *  Copyright (c) 1996-2000 Russell King.

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 *

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 * This program is free software; you can redistribute it and/or modify

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 * it under the terms of the GNU General Public License version 2 as

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 * published by the Free Software Foundation.

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 *

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 *  Changelog:

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 *   24-Sep-1996	RMK	Created

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 *   10-Oct-1996	RMK	Brought up to date with arch-sa110eval

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 *   04-Dec-1997	RMK	Updated for new arch/arm/time.c

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 *   13=Jun-2004	DS	Moved to arch/arm/common b/c shared w/CLPS7500

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 */

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#include <linux/timex.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 <mach/hardware.h>

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#include <asm/hardware/ioc.h>

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#include <asm/mach/time.h>

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unsigned long ioc_timer_gettimeoffset(void)

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{

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	unsigned int count1, count2, status;

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	long offset;

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	ioc_writeb (0, IOC_T0LATCH);

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	barrier ();

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	count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);

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	barrier ();

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	status = ioc_readb(IOC_IRQREQA);

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	barrier ();

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	ioc_writeb (0, IOC_T0LATCH);

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	barrier ();

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	count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);

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	offset = count2;

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	if (count2 < count1) {

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		/*

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		 * We have not had an interrupt between reading count1

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		 * and count2.

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		 */

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		if (status & (1 << 5))

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			offset -= LATCH;

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	} else if (count2 > count1) {

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		/*

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		 * We have just had another interrupt between reading

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		 * count1 and count2.

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		 */

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		offset -= LATCH;

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	}

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	offset = (LATCH - offset) * (tick_nsec / 1000);

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	return (offset + LATCH/2) / LATCH;

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}

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void __init ioctime_init(void)

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{

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	ioc_writeb(LATCH & 255, IOC_T0LTCHL);

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	ioc_writeb(LATCH >> 8, IOC_T0LTCHH);

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	ioc_writeb(0, IOC_T0GO);

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}

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static irqreturn_t

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ioc_timer_interrupt(int irq, void *dev_id)

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{

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	timer_tick();

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	return IRQ_HANDLED;

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}

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static struct irqaction ioc_timer_irq = {

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	.name		= "timer",

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	.flags		= IRQF_DISABLED,

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	.handler	= ioc_timer_interrupt

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};

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/*

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 * Set up timer interrupt.

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 */

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static void __init ioc_timer_init(void)

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{

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	ioctime_init();

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	setup_irq(IRQ_TIMER, &ioc_timer_irq);

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}

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struct sys_timer ioc_timer = {

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	.init		= ioc_timer_init,

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	.offset		= ioc_timer_gettimeoffset,

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};

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