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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/arch/arm/common/time-acorn.c
*
* Copyright (c) 1996-2000 Russell King.
*
* Changelog:
* 24-Sep-1996 RMK Created
* 10-Oct-1996 RMK Brought up to date with arch-sa110eval
* 04-Dec-1997 RMK Updated for new arch/arm/time.c
* 13=Jun-2004 DS Moved to arch/arm/common b/c shared w/CLPS7500
*/
#include <linux/clocksource.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <mach/hardware.h>
#include <asm/hardware/ioc.h>
#include <asm/mach/time.h>
#define RPC_CLOCK_FREQ 2000000
#define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ)
static u32 ioc_time;
static u64 ioc_timer_read(struct clocksource *cs)
{
unsigned int count1, count2, status;
unsigned long flags;
u32 ticks;
local_irq_save(flags);
ioc_writeb (0, IOC_T0LATCH);
barrier ();
count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
barrier ();
status = ioc_readb(IOC_IRQREQA);
barrier ();
ioc_writeb (0, IOC_T0LATCH);
barrier ();
count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
ticks = ioc_time + RPC_LATCH - count2;
local_irq_restore(flags);
if (count2 < count1) {
/*
* The timer has not reloaded between reading count1 and
* count2, check whether an interrupt was actually pending.
*/
if (status & (1 << 5))
ticks += RPC_LATCH;
} else if (count2 > count1) {
/*
* The timer has reloaded, so count2 indicates the new
* count since the wrap. The interrupt would not have
* been processed, so add the missed ticks.
*/
ticks += RPC_LATCH;
}
return ticks;
}
static struct clocksource ioctime_clocksource = {
.read = ioc_timer_read,
.mask = CLOCKSOURCE_MASK(32),
.rating = 100,
};
void __init ioctime_init(void)
{
ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL);
ioc_writeb(RPC_LATCH >> 8, IOC_T0LTCHH);
ioc_writeb(0, IOC_T0GO);
}
static irqreturn_t
ioc_timer_interrupt(int irq, void *dev_id)
{
ioc_time += RPC_LATCH;
timer_tick();
return IRQ_HANDLED;
}
/*
* Set up timer interrupt.
*/
void __init ioc_timer_init(void)
{
WARN_ON(clocksource_register_hz(&ioctime_clocksource, RPC_CLOCK_FREQ));
ioctime_init();
if (request_irq(IRQ_TIMER0, ioc_timer_interrupt, 0, "timer", NULL))
pr_err("Failed to request irq %d (timer)\n", IRQ_TIMER0);
}
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