/* * Copyright 2001 MontaVista Software Inc. * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net * Copyright (c) 2003, 2004  Maciej W. Rozycki * * Common time service routines for MIPS machines. See * Documentation/mips/time.README. * * This program is free software; you can redistribute  it and/or modify it * under  the terms of  the GNU General  Public License as published by the * Free Software Foundation;  either version 2 of the  License, or (at your * option) any later version. */#include <linux/types.h>#include <linux/kernel.h>#include <linux/init.h>#include <linux/sched.h>#include <linux/param.h>#include <linux/time.h>#include <linux/timex.h>#include <linux/smp.h>#include <linux/kernel_stat.h>#include <linux/spinlock.h>#include <linux/interrupt.h>#include <linux/module.h> #include <asm/bootinfo.h>#include <asm/cache.h>#include <asm/compiler.h>#include <asm/cpu.h>#include <asm/cpu-features.h>#include <asm/div64.h>#include <asm/sections.h>#include <asm/time.h> /* * The integer part of the number of usecs per jiffy is taken from tick, * but the fractional part is not recorded, so we calculate it using the * initial value of HZ.  This aids systems where tick isn't really an * integer (e.g. for HZ = 128). */#define USECS_PER_JIFFY		TICK_SIZE#define USECS_PER_JIFFY_FRAC	((unsigned long)(u32)((1000000ULL << 32) / HZ)) #define TICK_SIZE	(tick_nsec / 1000) /* * forward reference */DEFINE_SPINLOCK(rtc_lock); /* * By default we provide the null RTC ops */static unsigned long null_rtc_get_time(void){	return mktime(2000, 1, 1, 0, 0, 0);} static int null_rtc_set_time(unsigned long sec){	return 0;} unsigned long (*rtc_mips_get_time)(void) = null_rtc_get_time;int (*rtc_mips_set_time)(unsigned long) = null_rtc_set_time;int (*rtc_mips_set_mmss)(unsigned long);  /* how many counter cycles in a jiffy */static unsigned long cycles_per_jiffy __read_mostly; /* expirelo is the count value for next CPU timer interrupt */static unsigned int expirelo;  /* * Null timer ack for systems not needing one (e.g. i8254). */static void null_timer_ack(void) { /* nothing */ } /* * Null high precision timer functions for systems lacking one. */static cycle_t null_hpt_read(void){	return 0;} /* * Timer ack for an R4k-compatible timer of a known frequency. */static void c0_timer_ack(void){	unsigned int count; 	/* Ack this timer interrupt and set the next one.  */	expirelo += cycles_per_jiffy;	write_c0_compare(expirelo); 	/* Check to see if we have missed any timer interrupts.  */	while (((count = read_c0_count()) - expirelo) < 0x7fffffff) {		/* missed_timer_count++; */		expirelo = count + cycles_per_jiffy;		write_c0_compare(expirelo);	}} /* * High precision timer functions for a R4k-compatible timer. */static cycle_t c0_hpt_read(void){	return read_c0_count();} /* For use both as a high precision timer and an interrupt source.  */static void __init c0_hpt_timer_init(void){	expirelo = read_c0_count() + cycles_per_jiffy;	write_c0_compare(expirelo);} int (*mips_timer_state)(void);void (*mips_timer_ack)(void); /* last time when xtime and rtc are sync'ed up */static long last_rtc_update; /* * local_timer_interrupt() does profiling and process accounting * on a per-CPU basis. * * In UP mode, it is invoked from the (global) timer_interrupt. * * In SMP mode, it might invoked by per-CPU timer interrupt, or * a broadcasted inter-processor interrupt which itself is triggered * by the global timer interrupt. */void local_timer_interrupt(int irq, void *dev_id){	profile_tick(CPU_PROFILING);	update_process_times(user_mode(get_irq_regs()));} /* * High-level timer interrupt service routines.  This function * is set as irqaction->handler and is invoked through do_IRQ. */irqreturn_t timer_interrupt(int irq, void *dev_id){	write_seqlock(&xtime_lock); 	mips_timer_ack(); 	/*	 * call the generic timer interrupt handling	 */	do_timer(1); 	/*	 * If we have an externally synchronized Linux clock, then update	 * CMOS clock accordingly every ~11 minutes. rtc_mips_set_time() 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_mips_set_mmss(xtime.tv_sec) == 0) {			last_rtc_update = xtime.tv_sec;		} else {			/* do it again in 60 s */			last_rtc_update = xtime.tv_sec - 600;		}	} 	write_sequnlock(&xtime_lock); 	/*	 * In UP mode, we call local_timer_interrupt() to do profiling	 * and process accouting.	 *	 * In SMP mode, local_timer_interrupt() is invoked by appropriate	 * low-level local timer interrupt handler.	 */	local_timer_interrupt(irq, dev_id); 	return IRQ_HANDLED;} int null_perf_irq(void){	return 0;} int (*perf_irq)(void) = null_perf_irq; EXPORT_SYMBOL(null_perf_irq);EXPORT_SYMBOL(perf_irq); asmlinkage void ll_timer_interrupt(int irq){	int r2 = cpu_has_mips_r2; 	irq_enter();	kstat_this_cpu.irqs[irq]++; 	/*	 * Suckage alert:	 * Before R2 of the architecture there was no way to see if a	 * performance counter interrupt was pending, so we have to run the	 * performance counter interrupt handler anyway.	 */	if (!r2 || (read_c0_cause() & (1 << 26)))		if (perf_irq())			goto out; 	/* we keep interrupt disabled all the time */	if (!r2 || (read_c0_cause() & (1 << 30)))		timer_interrupt(irq, NULL); out:	irq_exit();} asmlinkage void ll_local_timer_interrupt(int irq){	irq_enter();	if (smp_processor_id() != 0)		kstat_this_cpu.irqs[irq]++; 	/* we keep interrupt disabled all the time */	local_timer_interrupt(irq, NULL); 	irq_exit();} /* * time_init() - it does the following things. * * 1) board_time_init() - * 	a) (optional) set up RTC routines, *      b) (optional) calibrate and set the mips_hpt_frequency *	    (only needed if you intended to use cpu counter as timer interrupt *	     source) * 2) setup xtime based on rtc_mips_get_time(). * 3) calculate a couple of cached variables for later usage * 4) plat_timer_setup() - *	a) (optional) over-write any choices made above by time_init(). *	b) machine specific code should setup the timer irqaction. *	c) enable the timer interrupt */ void (*board_time_init)(void); unsigned int mips_hpt_frequency; static struct irqaction timer_irqaction = {	.handler = timer_interrupt,	.flags = IRQF_DISABLED,	.name = "timer",}; static unsigned int __init calibrate_hpt(void){	cycle_t frequency, hpt_start, hpt_end, hpt_count, hz; 	const int loops = HZ / 10;	int log_2_loops = 0;	int i; 	/*	 * We want to calibrate for 0.1s, but to avoid a 64-bit	 * division we round the number of loops up to the nearest	 * power of 2.	 */	while (loops > 1 << log_2_loops)		log_2_loops++;	i = 1 << log_2_loops; 	/*	 * Wait for a rising edge of the timer interrupt.	 */	while (mips_timer_state());	while (!mips_timer_state()); 	/*	 * Now see how many high precision timer ticks happen	 * during the calculated number of periods between timer	 * interrupts.	 */	hpt_start = clocksource_mips.read();	do {		while (mips_timer_state());		while (!mips_timer_state());	} while (--i);	hpt_end = clocksource_mips.read(); 	hpt_count = (hpt_end - hpt_start) & clocksource_mips.mask;	hz = HZ;	frequency = hpt_count * hz; 	return frequency >> log_2_loops;} struct clocksource clocksource_mips = {	.name		= "MIPS",	.mask		= 0xffffffff,	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,}; static void __init init_mips_clocksource(void){	u64 temp;	u32 shift; 	if (!mips_hpt_frequency || clocksource_mips.read == null_hpt_read)		return; 	/* Calclate a somewhat reasonable rating value */	clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;	/* Find a shift value */	for (shift = 32; shift > 0; shift--) {		temp = (u64) NSEC_PER_SEC << shift;		do_div(temp, mips_hpt_frequency);		if ((temp >> 32) == 0)			break;	}	clocksource_mips.shift = shift;	clocksource_mips.mult = (u32)temp; 	clocksource_register(&clocksource_mips);} void __init time_init(void){	if (board_time_init)		board_time_init(); 	if (!rtc_mips_set_mmss)		rtc_mips_set_mmss = rtc_mips_set_time; 	xtime.tv_sec = rtc_mips_get_time();	xtime.tv_nsec = 0; 	set_normalized_timespec(&wall_to_monotonic,	                        -xtime.tv_sec, -xtime.tv_nsec); 	/* Choose appropriate high precision timer routines.  */	if (!cpu_has_counter && !clocksource_mips.read)		/* No high precision timer -- sorry.  */		clocksource_mips.read = null_hpt_read;	else if (!mips_hpt_frequency && !mips_timer_state) {		/* A high precision timer of unknown frequency.  */		if (!clocksource_mips.read)			/* No external high precision timer -- use R4k.  */			clocksource_mips.read = c0_hpt_read;	} else {		/* We know counter frequency.  Or we can get it.  */		if (!clocksource_mips.read) {			/* No external high precision timer -- use R4k.  */			clocksource_mips.read = c0_hpt_read; 			if (!mips_timer_state) {				/* No external timer interrupt -- use R4k.  */				mips_timer_ack = c0_timer_ack;				/* Calculate cache parameters.  */				cycles_per_jiffy =					(mips_hpt_frequency + HZ / 2) / HZ;				/*				 * This sets up the high precision				 * timer for the first interrupt.				 */				c0_hpt_timer_init();			}		}		if (!mips_hpt_frequency)			mips_hpt_frequency = calibrate_hpt(); 		/* Report the high precision timer rate for a reference.  */		printk("Using %u.%03u MHz high precision timer.\n",		       ((mips_hpt_frequency + 500) / 1000) / 1000,		       ((mips_hpt_frequency + 500) / 1000) % 1000);	} 	if (!mips_timer_ack)		/* No timer interrupt ack (e.g. i8254).  */		mips_timer_ack = null_timer_ack; 	/*	 * Call board specific timer interrupt setup.	 *	 * this pointer must be setup in machine setup routine.	 *	 * Even if a machine chooses to use a low-level timer interrupt,	 * it still needs to setup the timer_irqaction.	 * In that case, it might be better to set timer_irqaction.handler	 * to be NULL function so that we are sure the high-level code	 * is not invoked accidentally.	 */	plat_timer_setup(&timer_irqaction); 	init_mips_clocksource();} #define FEBRUARY		2#define STARTOFTIME		1970#define SECDAY			86400L#define SECYR			(SECDAY * 365)#define leapyear(y)		((!((y) % 4) && ((y) % 100)) || !((y) % 400))#define days_in_year(y)		(leapyear(y) ? 366 : 365)#define days_in_month(m)	(month_days[(m) - 1]) static int month_days[12] = {	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; void to_tm(unsigned long tim, struct rtc_time *tm){	long hms, day, gday;	int i; 	gday = day = tim / SECDAY;	hms = tim % SECDAY; 	/* Hours, minutes, seconds are easy */	tm->tm_hour = hms / 3600;	tm->tm_min = (hms % 3600) / 60;	tm->tm_sec = (hms % 3600) % 60; 	/* Number of years in days */	for (i = STARTOFTIME; day >= days_in_year(i); i++)		day -= days_in_year(i);	tm->tm_year = i; 	/* Number of months in days left */	if (leapyear(tm->tm_year))		days_in_month(FEBRUARY) = 29;	for (i = 1; day >= days_in_month(i); i++)		day -= days_in_month(i);	days_in_month(FEBRUARY) = 28;	tm->tm_mon = i - 1;		/* tm_mon starts from 0 to 11 */ 	/* Days are what is left over (+1) from all that. */	tm->tm_mday = day + 1; 	/*	 * Determine the day of week	 */	tm->tm_wday = (gday + 4) % 7;	/* 1970/1/1 was Thursday */} EXPORT_SYMBOL(rtc_lock);EXPORT_SYMBOL(to_tm);EXPORT_SYMBOL(rtc_mips_set_time);EXPORT_SYMBOL(rtc_mips_get_time);