time.c

linux-2.6.15.6

/*
 *  arch/sh/kernel/time.c
 *
 *  Copyright (C) 1999  Tetsuya Okada & Niibe Yutaka
 *  Copyright (C) 2000  Philipp Rumpf <[e-mail]>
 *  Copyright (C) 2002, 2003, 2004  Paul Mundt
 *  Copyright (C) 2002  M. R. Brown  <[e-mail]>
 *
 *  Some code taken from i386 version.
 *    Copyright (C) 1991, 1992, 1995  Linus Torvalds
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/profile.h>

#include <asm/processor.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/delay.h>
#include <asm/machvec.h>
#include <asm/rtc.h>
#include <asm/freq.h>
#include <asm/cpu/timer.h>
#ifdef CONFIG_SH_KGDB
#include <asm/kgdb.h>
#endif

#include <linux/timex.h>
#include <linux/irq.h>

#define TMU_TOCR_INIT	0x00
#define TMU0_TCR_INIT	0x0020
#define TMU_TSTR_INIT	1

#define TMU0_TCR_CALIB	0x0000

#ifdef CONFIG_CPU_SUBTYPE_ST40STB1
#define CLOCKGEN_MEMCLKCR 0xbb040038
#define MEMCLKCR_RATIO_MASK 0x7
#endif /* CONFIG_CPU_SUBTYPE_ST40STB1 */

extern unsigned long wall_jiffies;
#define TICK_SIZE (tick_nsec / 1000)
DEFINE_SPINLOCK(tmu0_lock);

/* XXX: Can we initialize this in a routine somewhere?  Dreamcast doesn't want
 * these routines anywhere... */
#ifdef CONFIG_SH_RTC
void (*rtc_get_time)(struct timespec *) = sh_rtc_gettimeofday;
int (*rtc_set_time)(const time_t) = sh_rtc_settimeofday;
#else
void (*rtc_get_time)(struct timespec *);
int (*rtc_set_time)(const time_t);
#endif

#if defined(CONFIG_CPU_SUBTYPE_SH7300)
static int md_table[] = { 1, 2, 3, 4, 6, 8, 12 };
#endif
#if defined(CONFIG_CPU_SH3)
static int stc_multipliers[] = { 1, 2, 3, 4, 6, 1, 1, 1 };
static int stc_values[]      = { 0, 1, 4, 2, 5, 0, 0, 0 };
#define bfc_divisors stc_multipliers
#define bfc_values stc_values
static int ifc_divisors[]    = { 1, 2, 3, 4, 1, 1, 1, 1 };
static int ifc_values[]      = { 0, 1, 4, 2, 0, 0, 0, 0 };
static int pfc_divisors[]    = { 1, 2, 3, 4, 6, 1, 1, 1 };
static int pfc_values[]      = { 0, 1, 4, 2, 5, 0, 0, 0 };
#elif defined(CONFIG_CPU_SH4)
#if defined(CONFIG_CPU_SUBTYPE_SH73180)
static int ifc_divisors[] = { 1, 2, 3, 4, 6, 8, 12, 16 };
static int ifc_values[] = { 0, 1, 2, 3, 4, 5, 6, 7 };
#define bfc_divisors ifc_divisors	/* Same */
#define bfc_values ifc_values
#define pfc_divisors ifc_divisors	/* Same */
#define pfc_values ifc_values
#else
static int ifc_divisors[] = { 1, 2, 3, 4, 6, 8, 1, 1 };
static int ifc_values[]   = { 0, 1, 2, 3, 0, 4, 0, 5 };
#define bfc_divisors ifc_divisors	/* Same */
#define bfc_values ifc_values
static int pfc_divisors[] = { 2, 3, 4, 6, 8, 2, 2, 2 };
static int pfc_values[]   = { 0, 0, 1, 2, 0, 3, 0, 4 };
#endif
#else
#error "Unknown ifc/bfc/pfc/stc values for this processor"
#endif

/*
 * Scheduler clock - returns current time in nanosec units.
 */
unsigned long long sched_clock(void)
{
	return (unsigned long long)jiffies * (1000000000 / HZ);
}

static unsigned long do_gettimeoffset(void)
{
	int count;
	unsigned long flags;

	static int count_p = 0x7fffffff;    /* for the first call after boot */
	static unsigned long jiffies_p = 0;

	/*
	 * cache volatile jiffies temporarily; we have IRQs turned off.
	 */
	unsigned long jiffies_t;

	spin_lock_irqsave(&tmu0_lock, flags);
	/* timer count may underflow right here */
	count = ctrl_inl(TMU0_TCNT);	/* read the latched count */

	jiffies_t = jiffies;

	/*
	 * avoiding timer inconsistencies (they are rare, but they happen)...
	 * there is one kind of problem that must be avoided here:
	 *  1. the timer counter underflows
	 */

	if( jiffies_t == jiffies_p ) {
		if( count > count_p ) {
			/* the nutcase */

			if(ctrl_inw(TMU0_TCR) & 0x100) { /* Check UNF bit */
				/*
				 * We cannot detect lost timer interrupts ...
				 * well, that's why we call them lost, don't we? :)
				 * [hmm, on the Pentium and Alpha we can ... sort of]
				 */
				count -= LATCH;
			} else {
				printk("do_slow_gettimeoffset(): hardware timer problem?\n");
			}
		}
	} else
		jiffies_p = jiffies_t;

	count_p = count;
	spin_unlock_irqrestore(&tmu0_lock, flags);

	count = ((LATCH-1) - count) * TICK_SIZE;
	count = (count + LATCH/2) / LATCH;

	return count;
}

void do_gettimeofday(struct timeval *tv)
{
	unsigned long seq;
	unsigned long usec, sec;
	unsigned long lost;

	do {
		seq = read_seqbegin(&xtime_lock);
		usec = do_gettimeoffset();

		lost = jiffies - wall_jiffies;
		if (lost)
			usec += lost * (1000000 / HZ);

		sec = xtime.tv_sec;
		usec += xtime.tv_nsec / 1000;
	} while (read_seqretry(&xtime_lock, seq));

	while (usec >= 1000000) {
		usec -= 1000000;
		sec++;
	}

	tv->tv_sec = sec;
	tv->tv_usec = usec;
}

EXPORT_SYMBOL(do_gettimeofday);

int do_settimeofday(struct timespec *tv)
{
	time_t wtm_sec, sec = tv->tv_sec;
	long wtm_nsec, nsec = tv->tv_nsec;

	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
	 * made, and then undo it!
	 */
	nsec -= 1000 * (do_gettimeoffset() +
				(jiffies - wall_jiffies) * (1000000 / HZ));

	wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
	wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);

	set_normalized_timespec(&xtime, sec, nsec);
	set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);

	ntp_clear();
	write_sequnlock_irq(&xtime_lock);
	clock_was_set();

	return 0;
}

EXPORT_SYMBOL(do_settimeofday);

/* last time the RTC clock got updated */
static long last_rtc_update;

/*
 * timer_interrupt() needs to keep up the real-time clock,
 * as well as call the "do_timer()" routine every clocktick
 */
static inline void do_timer_interrupt(int irq, struct pt_regs *regs)
{
	do_timer(regs);
#ifndef CONFIG_SMP
	update_process_times(user_mode(regs));
#endif
	profile_tick(CPU_PROFILING, regs);

#ifdef CONFIG_HEARTBEAT
	if (sh_mv.mv_heartbeat != NULL)
		sh_mv.mv_heartbeat();
#endif

	/*
	 * If we have an externally synchronized Linux clock, then update
	 * RTC clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	 * called as close as possible to 500 ms before the new second starts.
	 */
	if (ntp_synced() &&
	    xtime.tv_sec > last_rtc_update + 660 &&
	    (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
	    (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
		if (rtc_set_time(xtime.tv_sec) == 0)
			last_rtc_update = xtime.tv_sec;
		else
			last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
	}
}

/*
 * This is the same as the above, except we _also_ save the current
 * Time Stamp Counter value at the time of the timer interrupt, so that
 * we later on can estimate the time of day more exactly.
 */
static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	unsigned long timer_status;

	/* Clear UNF bit */
	timer_status = ctrl_inw(TMU0_TCR);
	timer_status &= ~0x100;
	ctrl_outw(timer_status, TMU0_TCR);

	/*
	 * Here we are in the timer irq handler. We just have irqs locally
	 * disabled but we don't know if the timer_bh is running on the other
	 * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
	 * the irq version of write_lock because as just said we have irq
	 * locally disabled. -arca
	 */
	write_seqlock(&xtime_lock);
	do_timer_interrupt(irq, regs);
	write_sequnlock(&xtime_lock);

	return IRQ_HANDLED;
}

/*
 * Hah!  We'll see if this works (switching from usecs to nsecs).
 */
static unsigned int __init get_timer_frequency(void)
{
	u32 freq;
	struct timespec ts1, ts2;
	unsigned long diff_nsec;
	unsigned long factor;

	/* Setup the timer:  We don't want to generate interrupts, just
	 * have it count down at its natural rate.
	 */
	ctrl_outb(0, TMU_TSTR);
#if !defined(CONFIG_CPU_SUBTYPE_SH7300)
	ctrl_outb(TMU_TOCR_INIT, TMU_TOCR);
#endif
	ctrl_outw(TMU0_TCR_CALIB, TMU0_TCR);
	ctrl_outl(0xffffffff, TMU0_TCOR);
	ctrl_outl(0xffffffff, TMU0_TCNT);

	rtc_get_time(&ts2);

	do {
		rtc_get_time(&ts1);
	} while (ts1.tv_nsec == ts2.tv_nsec && ts1.tv_sec == ts2.tv_sec);

	/* actually start the timer */
	ctrl_outb(TMU_TSTR_INIT, TMU_TSTR);

	do {
		rtc_get_time(&ts2);
	} while (ts1.tv_nsec == ts2.tv_nsec && ts1.tv_sec == ts2.tv_sec);

	freq = 0xffffffff - ctrl_inl(TMU0_TCNT);
	if (ts2.tv_nsec < ts1.tv_nsec) {
		ts2.tv_nsec += 1000000000;
		ts2.tv_sec--;
	}