[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>
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@ -365,8 +365,8 @@ config NO_IDLE_HZ
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Please note that dynamic tick may affect the accuracy of
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timekeeping on some platforms depending on the implementation.
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Currently at least OMAP platform is known to have accurate
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timekeeping with dynamic tick.
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Currently at least OMAP and PXA2xx platforms are known to have
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accurate timekeeping with dynamic tick.
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config ARCH_DISCONTIGMEM_ENABLE
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bool
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@ -70,6 +70,11 @@ static unsigned long pxa_gettimeoffset (void)
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return usec;
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}
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#ifdef CONFIG_NO_IDLE_HZ
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static unsigned long initial_match;
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static int match_posponed;
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#endif
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static irqreturn_t
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pxa_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
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{
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@ -77,6 +82,13 @@ pxa_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
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write_seqlock(&xtime_lock);
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#ifdef CONFIG_NO_IDLE_HZ
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if (match_posponed) {
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match_posponed = 0;
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OSMR0 = initial_match;
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}
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#endif
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/* Loop until we get ahead of the free running timer.
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* This ensures an exact clock tick count and time accuracy.
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* IRQs are disabled inside the loop to ensure coherence between
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@ -126,6 +138,42 @@ static void __init pxa_timer_init(void)
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OSCR = 0; /* initialize free-running timer, force first match */
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}
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#ifdef CONFIG_NO_IDLE_HZ
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static int pxa_dyn_tick_enable_disable(void)
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{
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/* nothing to do */
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return 0;
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}
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static void pxa_dyn_tick_reprogram(unsigned long ticks)
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{
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if (ticks > 1) {
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initial_match = OSMR0;
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OSMR0 = initial_match + ticks * LATCH;
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match_posponed = 1;
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}
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}
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static irqreturn_t
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pxa_dyn_tick_handler(int irq, void *dev_id, struct pt_regs *regs)
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{
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if (match_posponed) {
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match_posponed = 0;
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OSMR0 = initial_match;
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if ( (signed long)(initial_match - OSCR) <= 8 )
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return pxa_timer_interrupt(irq, dev_id, regs);
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}
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return IRQ_NONE;
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}
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static struct dyn_tick_timer pxa_dyn_tick = {
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.enable = pxa_dyn_tick_enable_disable,
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.disable = pxa_dyn_tick_enable_disable,
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.reprogram = pxa_dyn_tick_reprogram,
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.handler = pxa_dyn_tick_handler,
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};
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#endif
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#ifdef CONFIG_PM
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static unsigned long osmr[4], oier;
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@ -161,4 +209,7 @@ struct sys_timer pxa_timer = {
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.suspend = pxa_timer_suspend,
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.resume = pxa_timer_resume,
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.offset = pxa_gettimeoffset,
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#ifdef CONFIG_NO_IDLE_HZ
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.dyn_tick = &pxa_dyn_tick,
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#endif
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};
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