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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm26/kernel/time.c
Linux-2.6.12-rc2v2.6.12-rc2
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!
Diffstat (limited to 'arch/arm26/kernel/time.c')
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diff --git a/arch/arm26/kernel/time.c b/arch/arm26/kernel/time.c
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+/*
+ * linux/arch/arm26/kernel/time.c
+ *
+ * Copyright (C) 1991, 1992, 1995 Linus Torvalds
+ * Modifications for ARM (C) 1994-2001 Russell King
+ * Mods for ARM26 (C) 2003 Ian Molton
+ *
+ * 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.
+ *
+ * This file contains the ARM-specific time handling details:
+ * reading the RTC at bootup, etc...
+ *
+ * 1994-07-02 Alan Modra
+ * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
+ * 1998-12-20 Updated NTP code according to technical memorandum Jan '96
+ * "A Kernel Model for Precision Timekeeping" by Dave Mills
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/timex.h>
+#include <linux/errno.h>
+#include <linux/profile.h>
+
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/ioc.h>
+
+u64 jiffies_64 = INITIAL_JIFFIES;
+
+EXPORT_SYMBOL(jiffies_64);
+
+extern unsigned long wall_jiffies;
+
+/* this needs a better home */
+DEFINE_SPINLOCK(rtc_lock);
+
+/* change this if you have some constant time drift */
+#define USECS_PER_JIFFY (1000000/HZ)
+
+static int dummy_set_rtc(void)
+{
+ return 0;
+}
+
+/*
+ * hook for setting the RTC's idea of the current time.
+ */
+int (*set_rtc)(void) = dummy_set_rtc;
+
+/*
+ * Get time offset based on IOCs timer.
+ * FIXME - if this is called with interrutps off, why the shennanigans
+ * below ?
+ */
+static unsigned long gettimeoffset(void)
+{
+ unsigned int count1, count2, status;
+ long offset;
+
+ ioc_writeb (0, IOC_T0LATCH);
+ barrier ();
+ count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
+ barrier ();
+ status = ioc_readb(IOC_IRQREQA);
+ barrier ();
+ ioc_writeb (0, IOC_T0LATCH);
+ barrier ();
+ count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
+
+ offset = count2;
+ if (count2 < count1) {
+ /*
+ * We have not had an interrupt between reading count1
+ * and count2.
+ */
+ if (status & (1 << 5))
+ offset -= LATCH;
+ } else if (count2 > count1) {
+ /*
+ * We have just had another interrupt between reading
+ * count1 and count2.
+ */
+ offset -= LATCH;
+ }
+
+ offset = (LATCH - offset) * (tick_nsec / 1000);
+ return (offset + LATCH/2) / LATCH;
+}
+
+/*
+ * Scheduler clock - returns current time in nanosec units.
+ */
+unsigned long long sched_clock(void)
+{
+ return (unsigned long long)jiffies * (1000000000 / HZ);
+}
+
+static unsigned long next_rtc_update;
+
+/*
+ * If we have an externally synchronized linux clock, then update
+ * CMOS clock accordingly every ~11 minutes. set_rtc() has to be
+ * called as close as possible to 500 ms before the new second
+ * starts.
+ */
+static inline void do_set_rtc(void)
+{
+ if (time_status & STA_UNSYNC || set_rtc == NULL)
+ return;
+
+//FIXME - timespec.tv_sec is a time_t not unsigned long
+ if (next_rtc_update &&
+ time_before((unsigned long)xtime.tv_sec, next_rtc_update))
+ return;
+
+ if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) &&
+ xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1))
+ return;
+
+ if (set_rtc())
+ /*
+ * rtc update failed. Try again in 60s
+ */
+ next_rtc_update = xtime.tv_sec + 60;
+ else
+ next_rtc_update = xtime.tv_sec + 660;
+}
+
+#define do_leds()
+
+void do_gettimeofday(struct timeval *tv)
+{
+ unsigned long flags;
+ unsigned long seq;
+ unsigned long usec, sec, lost;
+
+ do {
+ seq = read_seqbegin_irqsave(&xtime_lock, flags);
+ usec = gettimeoffset();
+
+ lost = jiffies - wall_jiffies;
+ if (lost)
+ usec += lost * USECS_PER_JIFFY;
+
+ sec = xtime.tv_sec;
+ usec += xtime.tv_nsec / 1000;
+ } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
+
+ /* usec may have gone up a lot: be safe */
+ while (usec >= 1000000) {
+ usec -= 1000000;
+ sec++;
+ }
+
+ tv->tv_sec = sec;
+ tv->tv_usec = usec;
+}
+
+EXPORT_SYMBOL(do_gettimeofday);
+
+int do_settimeofday(struct timespec *tv)
+{
+ if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
+ return -EINVAL;
+
+ write_seqlock_irq(&xtime_lock);
+ /*
+ * This is revolting. We need to set "xtime" correctly. However, the
+ * value in this location is the value at the most recent update of
+ * wall time. Discover what correction gettimeofday() would have
+ * done, and then undo it!
+ */
+ tv->tv_nsec -= 1000 * (gettimeoffset() +
+ (jiffies - wall_jiffies) * USECS_PER_JIFFY);
+
+ while (tv->tv_nsec < 0) {
+ tv->tv_nsec += NSEC_PER_SEC;
+ tv->tv_sec--;
+ }
+
+ xtime.tv_sec = tv->tv_sec;
+ xtime.tv_nsec = tv->tv_nsec;
+ time_adjust = 0; /* stop active adjtime() */
+ time_status |= STA_UNSYNC;
+ time_maxerror = NTP_PHASE_LIMIT;
+ time_esterror = NTP_PHASE_LIMIT;
+ write_sequnlock_irq(&xtime_lock);
+ clock_was_set();
+ return 0;
+}
+
+EXPORT_SYMBOL(do_settimeofday);
+
+static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ do_timer(regs);
+#ifndef CONFIG_SMP
+ update_process_times(user_mode(regs));
+#endif
+ do_set_rtc(); //FIME - EVERY timer IRQ?
+ profile_tick(CPU_PROFILING, regs);
+ return IRQ_HANDLED; //FIXME - is this right?
+}
+
+static struct irqaction timer_irq = {
+ .name = "timer",
+ .flags = SA_INTERRUPT,
+ .handler = timer_interrupt,
+};
+
+extern void ioctime_init(void);
+
+/*
+ * Set up timer interrupt.
+ */
+void __init time_init(void)
+{
+ ioc_writeb(LATCH & 255, IOC_T0LTCHL);
+ ioc_writeb(LATCH >> 8, IOC_T0LTCHH);
+ ioc_writeb(0, IOC_T0GO);
+
+
+ setup_irq(IRQ_TIMER, &timer_irq);
+}
+