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/*
* arch/arm/mach-ks8695/time.c
*
* Copyright (C) 2006 Ben Dooks <ben@simtec.co.uk>
* Copyright (C) 2006 Simtec Electronics
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <asm/io.h>
#include <asm/mach/time.h>
#include <asm/arch/regs-timer.h>
#include <asm/arch/regs-irq.h>
#include "generic.h"
/*
* Returns number of ms since last clock interrupt. Note that interrupts
* will have been disabled by do_gettimeoffset()
*/
static unsigned long ks8695_gettimeoffset (void)
{
unsigned long elapsed, tick2, intpending;
/*
* Get the current number of ticks. Note that there is a race
* condition between us reading the timer and checking for an
* interrupt. We solve this by ensuring that the counter has not
* reloaded between our two reads.
*/
elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD);
do {
tick2 = elapsed;
intpending = __raw_readl(KS8695_IRQ_VA + KS8695_INTST) & (1 << KS8695_IRQ_TIMER1);
elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD);
} while (elapsed > tick2);
/* Convert to number of ticks expired (not remaining) */
elapsed = (CLOCK_TICK_RATE / HZ) - elapsed;
/* Is interrupt pending? If so, then timer has been reloaded already. */
if (intpending)
elapsed += (CLOCK_TICK_RATE / HZ);
/* Convert ticks to usecs */
return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
}
/*
* IRQ handler for the timer.
*/
static irqreturn_t ks8695_timer_interrupt(int irq, void *dev_id)
{
write_seqlock(&xtime_lock);
timer_tick();
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction ks8695_timer_irq = {
.name = "ks8695_tick",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = ks8695_timer_interrupt,
};
static void ks8695_timer_setup(void)
{
unsigned long tmout = CLOCK_TICK_RATE / HZ;
unsigned long tmcon;
/* disable timer1 */
tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
__raw_writel(tmcon & ~TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON);
__raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1TC);
__raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1PD);
/* re-enable timer1 */
__raw_writel(tmcon | TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON);
}
static void __init ks8695_timer_init (void)
{
ks8695_timer_setup();
/* Enable timer interrupts */
setup_irq(KS8695_IRQ_TIMER1, &ks8695_timer_irq);
}
struct sys_timer ks8695_timer = {
.init = ks8695_timer_init,
.offset = ks8695_gettimeoffset,
.resume = ks8695_timer_setup,
};
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