linux/arch/arm/mach-pxa/time.c
Russell King 4adb70fc1b [ARM] pxa: remove boot time RTC initialisation
The RTC library code contains everything necessary to set the
system time from the RTC; for similar reasons as the previous
commit, it's far better to let the RTC library code sort this
out rather than implement something which might not be
appropriate for everyone.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2007-07-12 14:28:17 +01:00

211 lines
4.8 KiB
C

/*
* arch/arm/mach-pxa/time.c
*
* Author: Nicolas Pitre
* Created: Jun 15, 2001
* Copyright: MontaVista Software Inc.
*
* 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/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/clocksource.h>
#include <asm/system.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/leds.h>
#include <asm/irq.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
#include <asm/arch/pxa-regs.h>
static int pxa_set_rtc(void)
{
unsigned long current_time = xtime.tv_sec;
if (RTSR & RTSR_ALE) {
/* make sure not to forward the clock over an alarm */
unsigned long alarm = RTAR;
if (current_time >= alarm && alarm >= RCNR)
return -ERESTARTSYS;
}
RCNR = current_time;
return 0;
}
#ifdef CONFIG_NO_IDLE_HZ
static unsigned long initial_match;
static int match_posponed;
#endif
static irqreturn_t
pxa_timer_interrupt(int irq, void *dev_id)
{
int next_match;
write_seqlock(&xtime_lock);
#ifdef CONFIG_NO_IDLE_HZ
if (match_posponed) {
match_posponed = 0;
OSMR0 = initial_match;
}
#endif
/* Loop until we get ahead of the free running timer.
* This ensures an exact clock tick count and time accuracy.
* Since IRQs are disabled at this point, coherence between
* lost_ticks(updated in do_timer()) and the match reg value is
* ensured, hence we can use do_gettimeofday() from interrupt
* handlers.
*
* HACK ALERT: it seems that the PXA timer regs aren't updated right
* away in all cases when a write occurs. We therefore compare with
* 8 instead of 0 in the while() condition below to avoid missing a
* match if OSCR has already reached the next OSMR value.
* Experience has shown that up to 6 ticks are needed to work around
* this problem, but let's use 8 to be conservative. Note that this
* affect things only when the timer IRQ has been delayed by nearly
* exactly one tick period which should be a pretty rare event.
*/
do {
timer_tick();
OSSR = OSSR_M0; /* Clear match on timer 0 */
next_match = (OSMR0 += LATCH);
} while( (signed long)(next_match - OSCR) <= 8 );
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction pxa_timer_irq = {
.name = "PXA Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = pxa_timer_interrupt,
};
static cycle_t pxa_get_cycles(void)
{
return OSCR;
}
static struct clocksource clocksource_pxa = {
.name = "pxa_timer",
.rating = 200,
.read = pxa_get_cycles,
.mask = CLOCKSOURCE_MASK(32),
.shift = 20,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static void __init pxa_timer_init(void)
{
struct timespec tv;
unsigned long flags;
set_rtc = pxa_set_rtc;
OIER = 0; /* disable any timer interrupts */
OSSR = 0xf; /* clear status on all timers */
setup_irq(IRQ_OST0, &pxa_timer_irq);
local_irq_save(flags);
OIER = OIER_E0; /* enable match on timer 0 to cause interrupts */
OSMR0 = OSCR + LATCH; /* set initial match */
local_irq_restore(flags);
/*
* OSCR runs continuously on PXA and is not written to,
* so we can use it as clock source directly.
*/
clocksource_pxa.mult =
clocksource_hz2mult(CLOCK_TICK_RATE, clocksource_pxa.shift);
clocksource_register(&clocksource_pxa);
}
#ifdef CONFIG_NO_IDLE_HZ
static int pxa_dyn_tick_enable_disable(void)
{
/* nothing to do */
return 0;
}
static void pxa_dyn_tick_reprogram(unsigned long ticks)
{
if (ticks > 1) {
initial_match = OSMR0;
OSMR0 = initial_match + ticks * LATCH;
match_posponed = 1;
}
}
static irqreturn_t
pxa_dyn_tick_handler(int irq, void *dev_id)
{
if (match_posponed) {
match_posponed = 0;
OSMR0 = initial_match;
if ( (signed long)(initial_match - OSCR) <= 8 )
return pxa_timer_interrupt(irq, dev_id);
}
return IRQ_NONE;
}
static struct dyn_tick_timer pxa_dyn_tick = {
.enable = pxa_dyn_tick_enable_disable,
.disable = pxa_dyn_tick_enable_disable,
.reprogram = pxa_dyn_tick_reprogram,
.handler = pxa_dyn_tick_handler,
};
#endif
#ifdef CONFIG_PM
static unsigned long osmr[4], oier;
static void pxa_timer_suspend(void)
{
osmr[0] = OSMR0;
osmr[1] = OSMR1;
osmr[2] = OSMR2;
osmr[3] = OSMR3;
oier = OIER;
}
static void pxa_timer_resume(void)
{
OSMR0 = osmr[0];
OSMR1 = osmr[1];
OSMR2 = osmr[2];
OSMR3 = osmr[3];
OIER = oier;
/*
* OSMR0 is the system timer: make sure OSCR is sufficiently behind
*/
OSCR = OSMR0 - LATCH;
}
#else
#define pxa_timer_suspend NULL
#define pxa_timer_resume NULL
#endif
struct sys_timer pxa_timer = {
.init = pxa_timer_init,
.suspend = pxa_timer_suspend,
.resume = pxa_timer_resume,
#ifdef CONFIG_NO_IDLE_HZ
.dyn_tick = &pxa_dyn_tick,
#endif
};