1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
160 lines
3.7 KiB
C
160 lines
3.7 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/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 unsigned long __init sa1100_get_rtc_time(void)
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{
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/*
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* According to the manual we should be able to let RTTR be zero
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* and then a default diviser for a 32.768KHz clock is used.
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* Apparently this doesn't work, at least for my SA1110 rev 5.
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* If the clock divider is uninitialized then reset it to the
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* default value to get the 1Hz clock.
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*/
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if (RTTR == 0) {
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RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
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printk(KERN_WARNING "Warning: uninitialized Real Time Clock\n");
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/* The current RTC value probably doesn't make sense either */
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RCNR = 0;
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return 0;
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}
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return RCNR;
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}
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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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/*
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* We will be entered with IRQs enabled.
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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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* IRQs are disabled inside the loop to ensure coherence between
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* lost_ticks (updated in do_timer()) and the match reg value, so we
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* can use do_gettimeofday() from interrupt handlers.
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*/
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static irqreturn_t
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sa1100_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
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{
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unsigned int next_match;
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write_seqlock(&xtime_lock);
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do {
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timer_tick(regs);
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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 = SA_INTERRUPT,
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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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struct timespec tv;
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set_rtc = sa1100_set_rtc;
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tv.tv_nsec = 0;
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tv.tv_sec = sa1100_get_rtc_time();
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do_settimeofday(&tv);
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OSMR0 = 0; /* set initial match at 0 */
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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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OIER |= OIER_E0; /* enable match on timer 0 to cause interrupts */
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OSCR = 0; /* initialize free-running timer, force first match */
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}
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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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};
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