![Russell King](/assets/img/avatar_default.png)
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>
190 lines
4.1 KiB
C
190 lines
4.1 KiB
C
/*
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* linux/arch/arm/mach-sa1100/time.c
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*
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* Copyright (C) 1998 Deborah Wallach.
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* Twiddles (C) 1999 Hugo Fiennes <hugo@empeg.com>
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*
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* 2000/03/29 (C) Nicolas Pitre <nico@cam.org>
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* Rewritten: big cleanup, much simpler, better HZ accuracy.
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*
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*/
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/timex.h>
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#include <linux/signal.h>
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#include <asm/mach/time.h>
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#include <asm/hardware.h>
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#define RTC_DEF_DIVIDER (32768 - 1)
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#define RTC_DEF_TRIM 0
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static int sa1100_set_rtc(void)
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{
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unsigned long current_time = xtime.tv_sec;
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if (RTSR & RTSR_ALE) {
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/* make sure not to forward the clock over an alarm */
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unsigned long alarm = RTAR;
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if (current_time >= alarm && alarm >= RCNR)
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return -ERESTARTSYS;
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}
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RCNR = current_time;
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return 0;
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}
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/* IRQs are disabled before entering here from do_gettimeofday() */
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static unsigned long sa1100_gettimeoffset (void)
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{
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unsigned long ticks_to_match, elapsed, usec;
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/* Get ticks before next timer match */
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ticks_to_match = OSMR0 - OSCR;
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/* We need elapsed ticks since last match */
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elapsed = LATCH - ticks_to_match;
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/* Now convert them to usec */
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usec = (unsigned long)(elapsed * (tick_nsec / 1000))/LATCH;
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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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sa1100_timer_interrupt(int irq, void *dev_id)
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{
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unsigned int next_match;
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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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/*
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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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* Since IRQs are disabled at this point, coherence between
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* lost_ticks(updated in do_timer()) and the match reg value is
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* ensured, hence we can use do_gettimeofday() from interrupt
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* handlers.
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*/
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do {
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timer_tick();
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OSSR = OSSR_M0; /* Clear match on timer 0 */
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next_match = (OSMR0 += LATCH);
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} while ((signed long)(next_match - OSCR) <= 0);
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write_sequnlock(&xtime_lock);
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return IRQ_HANDLED;
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}
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static struct irqaction sa1100_timer_irq = {
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.name = "SA11xx Timer Tick",
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.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
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.handler = sa1100_timer_interrupt,
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};
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static void __init sa1100_timer_init(void)
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{
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unsigned long flags;
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set_rtc = sa1100_set_rtc;
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OIER = 0; /* disable any timer interrupts */
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OSSR = 0xf; /* clear status on all timers */
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setup_irq(IRQ_OST0, &sa1100_timer_irq);
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local_irq_save(flags);
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OIER = OIER_E0; /* enable match on timer 0 to cause interrupts */
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OSMR0 = OSCR + LATCH; /* set initial match */
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local_irq_restore(flags);
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}
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#ifdef CONFIG_NO_IDLE_HZ
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static int sa1100_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 sa1100_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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sa1100_dyn_tick_handler(int irq, void *dev_id)
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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) <= 0)
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return sa1100_timer_interrupt(irq, dev_id);
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}
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return IRQ_NONE;
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}
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static struct dyn_tick_timer sa1100_dyn_tick = {
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.enable = sa1100_dyn_tick_enable_disable,
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.disable = sa1100_dyn_tick_enable_disable,
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.reprogram = sa1100_dyn_tick_reprogram,
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.handler = sa1100_dyn_tick_handler,
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};
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#endif
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#ifdef CONFIG_PM
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unsigned long osmr[4], oier;
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static void sa1100_timer_suspend(void)
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{
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osmr[0] = OSMR0;
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osmr[1] = OSMR1;
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osmr[2] = OSMR2;
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osmr[3] = OSMR3;
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oier = OIER;
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}
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static void sa1100_timer_resume(void)
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{
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OSSR = 0x0f;
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OSMR0 = osmr[0];
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OSMR1 = osmr[1];
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OSMR2 = osmr[2];
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OSMR3 = osmr[3];
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OIER = oier;
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/*
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* OSMR0 is the system timer: make sure OSCR is sufficiently behind
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*/
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OSCR = OSMR0 - LATCH;
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}
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#else
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#define sa1100_timer_suspend NULL
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#define sa1100_timer_resume NULL
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#endif
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struct sys_timer sa1100_timer = {
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.init = sa1100_timer_init,
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.suspend = sa1100_timer_suspend,
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.resume = sa1100_timer_resume,
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.offset = sa1100_gettimeoffset,
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#ifdef CONFIG_NO_IDLE_HZ
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.dyn_tick = &sa1100_dyn_tick,
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#endif
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};
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