time.c

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/* $Id: time.c,v 1.20 2000/02/28 12:42:51 gniibe Exp $
 *
 *  linux/arch/sh/kernel/time.c
 *
 *  Copyright (C) 1999  Tetsuya Okada & Niibe Yutaka
 *  Copyright (C) 2000  Philipp Rumpf <[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/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 <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 <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

#if defined(__sh3__)
#define TMU_TOCR	0xfffffe90	/* Byte access */
#define TMU_TSTR	0xfffffe92	/* Byte access */

#define TMU0_TCOR	0xfffffe94	/* Long access */
#define TMU0_TCNT	0xfffffe98	/* Long access */
#define TMU0_TCR	0xfffffe9c	/* Word access */

#define FRQCR		0xffffff80
#elif defined(__SH4__)
#define TMU_TOCR	0xffd80000	/* Byte access */
#define TMU_TSTR	0xffd80004	/* Byte access */

#define TMU0_TCOR	0xffd80008	/* Long access */
#define TMU0_TCNT	0xffd8000c	/* Long access */
#define TMU0_TCR	0xffd80010	/* Word access */

#define FRQCR		0xffc00000
#endif

extern rwlock_t xtime_lock;
extern unsigned long wall_jiffies;
#define TICK_SIZE tick

static unsigned long do_gettimeoffset(void)
{
	int count;

	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;

	/* 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;

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

	return count;
}

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

	read_lock_irqsave(&xtime_lock, flags);
	usec = do_gettimeoffset();
	{
		unsigned long lost = jiffies - wall_jiffies;
		if (lost)
			usec += lost * (1000000 / HZ);
	}
	sec = xtime.tv_sec;
	usec += xtime.tv_usec;
	read_unlock_irqrestore(&xtime_lock, flags);

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

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

void do_settimeofday(struct timeval *tv)
{
	write_lock_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!
	 */
	tv->tv_usec -= do_gettimeoffset();
	tv->tv_usec -= (jiffies - wall_jiffies) * (1000000 / HZ);

	while (tv->tv_usec < 0) {
		tv->tv_usec += 1000000;
		tv->tv_sec--;
	}

	xtime = *tv;
	time_adjust = 0;		/* stop active adjtime() */
	time_status |= STA_UNSYNC;
	time_maxerror = NTP_PHASE_LIMIT;
	time_esterror = NTP_PHASE_LIMIT;
	write_unlock_irq(&xtime_lock);
}

/* 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, void *dev_id, struct pt_regs *regs)
{
	do_timer(regs);
#if 0
	if (!user_mode(regs))
		sh_do_profile(regs->pc);
#endif

#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 ((time_status & STA_UNSYNC) == 0 &&
	    xtime.tv_sec > last_rtc_update + 660 &&
	    xtime.tv_usec >= 500000 - ((unsigned) tick) / 2 &&
	    xtime.tv_usec <= 500000 + ((unsigned) tick) / 2) {
		if (sh_mv.mv_rtc_settimeofday(&xtime) == 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 void 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_lock(&xtime_lock);
	do_timer_interrupt(irq, NULL, regs);
	write_unlock(&xtime_lock);
}

static unsigned int __init get_timer_frequency(void)
{
	u32 freq;
	struct timeval tv1, tv2;
	unsigned long diff_usec;
	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);
	ctrl_outb(TMU_TOCR_INIT, TMU_TOCR);
	ctrl_outw(TMU0_TCR_CALIB, TMU0_TCR);
	ctrl_outl(0xffffffff, TMU0_TCOR);
	ctrl_outl(0xffffffff, TMU0_TCNT);

	rtc_gettimeofday(&tv2);

	do {
		rtc_gettimeofday(&tv1);
	} while (tv1.tv_usec == tv2.tv_usec && tv1.tv_sec == tv2.tv_sec);

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

	do {
		rtc_gettimeofday(&tv2);
	} while (tv1.tv_usec == tv2.tv_usec && tv1.tv_sec == tv2.tv_sec);

	freq = 0xffffffff - ctrl_inl(TMU0_TCNT);
	if (tv2.tv_usec < tv1.tv_usec) {
		tv2.tv_usec += 1000000;
		tv2.tv_sec--;
	}

	diff_usec = (tv2.tv_sec - tv1.tv_sec) * 1000000 + (tv2.tv_usec - tv1.tv_usec);

	/* this should work well if the RTC has a precision of n Hz, where
	 * n is an integer.  I don't think we have to worry about the other
	 * cases. */
	factor = (1000000 + diff_usec/2) / diff_usec;

	if (factor * diff_usec > 1100000 ||
	    factor * diff_usec <  900000)
		panic("weird RTC (diff_usec %ld)", diff_usec);

	return freq * factor;
}

static struct irqaction irq0  = { timer_interrupt, SA_INTERRUPT, 0, "timer", NULL, NULL};

void __init time_init(void)
{
	unsigned int cpu_clock, master_clock, bus_clock, module_clock;
	unsigned int timer_freq;
	unsigned short frqcr, ifc, pfc, bfc;
	unsigned long interval;
#if defined(__sh3__)
	static int ifc_table[] = { 1, 2, 4, 1, 3, 1, 1, 1 };
	static int pfc_table[] = { 1, 2, 4, 1, 3, 6, 1, 1 };
	static int stc_table[] = { 1, 2, 4, 8, 3, 6, 1, 1 };
#elif defined(__SH4__)
	static int ifc_table[] = { 1, 2, 3, 4, 6, 8, 1, 1 };
#define bfc_table ifc_table	/* Same */
	static int pfc_table[] = { 2, 3, 4, 6, 8, 2, 2, 2 };
#endif

	rtc_gettimeofday(&xtime);

	setup_irq(TIMER_IRQ, &irq0);

	timer_freq = get_timer_frequency();

	module_clock = timer_freq * 4;

#if defined(__sh3__)
	{
		unsigned short tmp;

		frqcr = ctrl_inw(FRQCR);
		tmp  = (frqcr & 0x8000) >> 13;
		tmp |= (frqcr & 0x0030) >>  4;
		bfc = stc_table[tmp];
		tmp  = (frqcr & 0x4000) >> 12;
		tmp |= (frqcr & 0x000c) >> 2;
		ifc  = ifc_table[tmp];
		tmp  = (frqcr & 0x2000) >> 11;
		tmp |= frqcr & 0x0003;
		pfc = pfc_table[tmp];
	}
#elif defined(__SH4__)
	{
		frqcr = ctrl_inw(FRQCR);
		ifc  = ifc_table[(frqcr>> 6) & 0x0007];
		bfc  = bfc_table[(frqcr>> 3) & 0x0007];
		pfc = pfc_table[frqcr & 0x0007];
	}
#endif
	master_clock = module_clock * pfc;
	bus_clock = master_clock / bfc;
	cpu_clock = master_clock / ifc;
	printk("CPU clock: %d.%02dMHz\n",
	       (cpu_clock / 1000000), (cpu_clock % 1000000)/10000);
	printk("Bus clock: %d.%02dMHz\n",
	       (bus_clock/1000000), (bus_clock % 1000000)/10000);
	printk("Module clock: %d.%02dMHz\n",
	       (module_clock/1000000), (module_clock % 1000000)/10000);
	interval = (module_clock/4 + HZ/2) / HZ;

	printk("Interval = %ld\n", interval);

	current_cpu_data.cpu_clock    = cpu_clock;
	current_cpu_data.master_clock = master_clock;
	current_cpu_data.bus_clock    = bus_clock;
	current_cpu_data.module_clock = module_clock;

	/* Start TMU0 */
	ctrl_outb(0, TMU_TSTR);
	ctrl_outb(TMU_TOCR_INIT, TMU_TOCR);
	ctrl_outw(TMU0_TCR_INIT, TMU0_TCR);
	ctrl_outl(interval, TMU0_TCOR);
	ctrl_outl(interval, TMU0_TCNT);
	ctrl_outb(TMU_TSTR_INIT, TMU_TSTR);
}