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clocksource: convert footbridge to generic i8253 clocksource

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Convert the footbridge isa-timer code to use generic i8253 clocksource.

Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2011-05-08 18:50:20 +01:00
parent 89c0b8e252
commit 8c414ff3f4
4 changed files with 23 additions and 41 deletions
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15
arch/arm/include/asm/i8253.h Normal file
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@ -0,0 +1,15 @@
#ifndef __ASMARM_I8253_H
#define __ASMARM_I8253_H
/* i8253A PIT registers */
#define PIT_MODE 0x43
#define PIT_CH0 0x40
#define PIT_LATCH ((PIT_TICK_RATE + HZ / 2) / HZ)
extern raw_spinlock_t i8253_lock;
#define outb_pit outb_p
#define inb_pit inb_p
#endif

2
arch/arm/mach-footbridge/Kconfig
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@ -4,6 +4,7 @@ menu "Footbridge Implementations"
config ARCH_CATS
bool "CATS"
select CLKSRC_I8253
select FOOTBRIDGE_HOST
select ISA
select ISA_DMA
@ -59,6 +60,7 @@ config ARCH_EBSA285_HOST
config ARCH_NETWINDER
bool "NetWinder"
select CLKSRC_I8253
select FOOTBRIDGE_HOST
select ISA
select ISA_DMA

45
arch/arm/mach-footbridge/isa-timer.c
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@ -10,53 +10,16 @@
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/timex.h>
#include <asm/irq.h>
#include <asm/i8253.h>
#include <asm/mach/time.h>
#include "common.h"
#define PIT_MODE 0x43
#define PIT_CH0 0x40
#define PIT_LATCH ((PIT_TICK_RATE + HZ / 2) / HZ)
static cycle_t pit_read(struct clocksource *cs)
{
unsigned long flags;
static int old_count;
static u32 old_jifs;
int count;
u32 jifs;
raw_local_irq_save(flags);
jifs = jiffies;
outb_p(0x00, PIT_MODE); /* latch the count */
count = inb_p(PIT_CH0); /* read the latched count */
count |= inb_p(PIT_CH0) << 8;
if (count > old_count && jifs == old_jifs)
count = old_count;
old_count = count;
old_jifs = jifs;
raw_local_irq_restore(flags);
count = (PIT_LATCH - 1) - count;
return (cycle_t)(jifs * PIT_LATCH) + count;
}
static struct clocksource pit_cs = {
.name = "pit",
.rating = 110,
.read = pit_read,
.mask = CLOCKSOURCE_MASK(32),
};
DEFINE_RAW_SPINLOCK(i8253_lock);
static void pit_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
@ -121,7 +84,7 @@ static void __init isa_timer_init(void)
pit_ce.max_delta_ns = clockevent_delta2ns(0x7fff, &pit_ce);
pit_ce.min_delta_ns = clockevent_delta2ns(0x000f, &pit_ce);
clocksource_register_hz(&pit_cs, PIT_TICK_RATE);
clocksource_i8253_init();
setup_irq(pit_ce.irq, &pit_timer_irq);
clockevents_register_device(&pit_ce);

2
include/linux/clocksource.h
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@ -341,4 +341,6 @@ static inline void update_vsyscall_tz(void)
extern void timekeeping_notify(struct clocksource *clock);
extern int clocksource_i8253_init(void);
#endif /* _LINUX_CLOCKSOURCE_H */