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/*
* arch/arm/mach-ns9xxx/time.c
*
* Copyright (C) 2006 by Digi International Inc.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*/
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <asm/arch-ns9xxx/regs-sys.h>
#include <asm/arch-ns9xxx/clock.h>
#include <asm/arch-ns9xxx/irqs.h>
#include <asm/arch/system.h>
#include "generic.h"
#define TIMERCLOCKSELECT 64
static u32 usecs_per_tick;
static irqreturn_t
ns9xxx_timer_interrupt(int irq, void *dev_id)
{
write_seqlock(&xtime_lock);
timer_tick();
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static unsigned long ns9xxx_timer_gettimeoffset(void)
{
/* return the microseconds which have passed since the last interrupt
* was _serviced_. That is, if an interrupt is pending or the counter
* reloads, return one period more. */
u32 counter1 = SYS_TR(0);
int pending = SYS_ISR & (1 << IRQ_TIMER0);
u32 counter2 = SYS_TR(0);
u32 elapsed;
if (pending || counter2 > counter1)
elapsed = 2 * SYS_TRC(0) - counter2;
else
elapsed = SYS_TRC(0) - counter1;
return (elapsed * usecs_per_tick) >> 16;
}
static struct irqaction ns9xxx_timer_irq = {
.name = "NS9xxx Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = ns9xxx_timer_interrupt,
};
static void __init ns9xxx_timer_init(void)
{
int tc;
usecs_per_tick =
SH_DIV(1000000 * TIMERCLOCKSELECT, ns9xxx_cpuclock(), 16);
/* disable timer */
if ((tc = SYS_TC(0)) & SYS_TCx_TEN)
SYS_TC(0) = tc & ~SYS_TCx_TEN;
SYS_TRC(0) = SH_DIV(ns9xxx_cpuclock(), (TIMERCLOCKSELECT * HZ), 0);
REGSET(tc, SYS_TCx, TEN, EN);
REGSET(tc, SYS_TCx, TLCS, DIV64); /* This must match TIMERCLOCKSELECT */
REGSET(tc, SYS_TCx, INTS, EN);
REGSET(tc, SYS_TCx, UDS, DOWN);
REGSET(tc, SYS_TCx, TDBG, STOP);
REGSET(tc, SYS_TCx, TSZ, 32);
REGSET(tc, SYS_TCx, REN, EN);
SYS_TC(0) = tc;
setup_irq(IRQ_TIMER0, &ns9xxx_timer_irq);
}
struct sys_timer ns9xxx_timer = {
.init = ns9xxx_timer_init,
.offset = ns9xxx_timer_gettimeoffset,
};
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