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[ARM] 2862/1: VST aka CONFIG_NO_IDLE_HZ support for PXA2xx 

Patch from Nicolas Pitre

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Nicolas Pitre 2005-09-01 12:48:40 +01:00 committed by Russell King
parent 68d9102f76
commit 5c53ff088c
2 changed files with 53 additions and 2 deletions
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4
arch/arm/Kconfig
View File

@ -365,8 +365,8 @@ config NO_IDLE_HZ
Please note that dynamic tick may affect the accuracy of
timekeeping on some platforms depending on the implementation.
Currently at least OMAP platform is known to have accurate
timekeeping with dynamic tick.
Currently at least OMAP and PXA2xx platforms are known to have
accurate timekeeping with dynamic tick.
config ARCH_DISCONTIGMEM_ENABLE
bool

51
arch/arm/mach-pxa/time.c
View File

@ -70,6 +70,11 @@ static unsigned long pxa_gettimeoffset (void)
return usec;
}
#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, struct pt_regs *regs)
{
@ -77,6 +82,13 @@ pxa_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
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.
* IRQs are disabled inside the loop to ensure coherence between
@ -126,6 +138,42 @@ static void __init pxa_timer_init(void)
OSCR = 0; /* initialize free-running timer, force first match */
}
#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, struct pt_regs *regs)
{
if (match_posponed) {
match_posponed = 0;
OSMR0 = initial_match;
if ( (signed long)(initial_match - OSCR) <= 8 )
return pxa_timer_interrupt(irq, dev_id, regs);
}
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;
@ -161,4 +209,7 @@ struct sys_timer pxa_timer = {
.suspend = pxa_timer_suspend,
.resume = pxa_timer_resume,
.offset = pxa_gettimeoffset,
#ifdef CONFIG_NO_IDLE_HZ
.dyn_tick = &pxa_dyn_tick,
#endif
};