/*
 *  linux/arch/arm/kernel/time.c
 *
 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
 *  Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King
 *
 * 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
 * 1997-09-10  Updated NTP code according to technical memorandum Jan '96
 *             "A Kernel Model for Precision Timekeeping" by Dave Mills
 */
#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 <linux/init.h>

#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/delay.h>

#include <linux/timex.h>
#include <asm/hardware.h>

extern int setup_arm_irq(int, struct irqaction *);
extern volatile unsigned long lost_ticks;

/* change this if you have some constant time drift */
#define USECS_PER_JIFFY	(1000000/HZ)

#ifndef BCD_TO_BIN
#define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)
#endif

#ifndef BIN_TO_BCD
#define BIN_TO_BCD(val) ((val)=(((val)/10)<<4) + (val)%10)
#endif

/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
 *
 * [For the Julian calendar (which was used in Russia before 1917,
 * Britain & colonies before 1752, anywhere else before 1582,
 * and is still in use by some communities) leave out the
 * -year/100+year/400 terms, and add 10.]
 *
 * This algorithm was first published by Gauss (I think).
 *
 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
 * machines were long is 32-bit! (However, as time_t is signed, we
 * will already get problems at other places on 2038-01-19 03:14:08)
 */
static inline unsigned long mktime(unsigned int year, unsigned int mon,
	unsigned int day, unsigned int hour,
	unsigned int min, unsigned int sec)
{
	if (0 >= (int) (mon -= 2)) {	/* 1..12 -> 11,12,1..10 */
		mon += 12;	/* Puts Feb last since it has leap day */
		year -= 1;
	}
	return (((
		    (unsigned long)(year/4 - year/100 + year/400 + 367*mon/12 + day) +
		      year*365 - 719499
		    )*24 + hour /* now have hours */
		   )*60 + min /* now have minutes */
		  )*60 + sec; /* finally seconds */
}

#include <asm/arch/time.h>

static unsigned long do_gettimeoffset(void)
{
	return gettimeoffset ();
}

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

	save_flags_cli (flags);
	*tv = xtime;
	tv->tv_usec += do_gettimeoffset();

	/*
	 * xtime is atomically updated in timer_bh. lost_ticks is
	 * nonzero if the tiemr bottom half hasnt executed yet.
	 */
	if (lost_ticks)
		tv->tv_usec += USECS_PER_JIFFY;

	restore_flags(flags);

	if (tv->tv_usec >= 1000000) {
		tv->tv_usec -= 1000000;
		tv->tv_sec++;
	}
}

void do_settimeofday(struct timeval *tv)
{
	cli ();
	/* This is revolting. We need to set the xtime.tv_usec
	 * correctly. However, the value in this location is
	 * is value at the last tick.
	 * Discover what correction gettimeofday
	 * would have done, and then undo it!
	 */
	tv->tv_usec -= do_gettimeoffset();

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

	xtime = *tv;
	time_state = TIME_BAD;
	time_maxerror = MAXPHASE;
	time_esterror = MAXPHASE;
	sti ();
}

/*
 * timer_interrupt() needs to keep up the real-time clock,
 * as well as call the "do_timer()" routine every clocktick.
 */
static void timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	if (reset_timer ())
		do_timer(regs);

	update_rtc ();
}

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

__initfunc(void time_init(void))
{
	xtime.tv_sec = setup_timer();
	xtime.tv_usec = 0;

	setup_arm_irq(IRQ_TIMER, &irqtimer);
}
