/* * arch/xtensa/kernel/time.c * * Timer and clock support. * * This file is subject to the terms and conditions of the GNU General Public * License.  See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 2005 Tensilica Inc. * * Chris Zankel <chris@zankel.net> */ #include <linux/errno.h>#include <linux/time.h>#include <linux/timex.h>#include <linux/interrupt.h>#include <linux/module.h>#include <linux/init.h>#include <linux/irq.h>#include <linux/profile.h>#include <linux/delay.h> #include <asm/timex.h>#include <asm/platform.h>  DEFINE_SPINLOCK(rtc_lock);EXPORT_SYMBOL(rtc_lock);  #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNTunsigned long ccount_per_jiffy;		/* per 1/HZ */unsigned long ccount_nsec;		/* nsec per ccount increment */#endif unsigned int last_ccount_stamp;static long last_rtc_update = 0; static irqreturn_t timer_interrupt(int irq, void *dev_id);static struct irqaction timer_irqaction = {	.handler =	timer_interrupt,	.flags =	IRQF_DISABLED,	.name =		"timer",}; void __init time_init(void){	time_t sec_o, sec_n = 0; 	/* The platform must provide a function to calibrate the processor	 * speed for the CALIBRATE.	 */ #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT	printk("Calibrating CPU frequency ");	platform_calibrate_ccount();	printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),			(int)(ccount_per_jiffy/(10000/HZ))%100);#endif 	/* Set time from RTC (if provided) */ 	if (platform_get_rtc_time(&sec_o) == 0)		while (platform_get_rtc_time(&sec_n))			if (sec_o != sec_n)				break; 	xtime.tv_nsec = 0;	last_rtc_update = xtime.tv_sec = sec_n;	last_ccount_stamp = get_ccount(); 	set_normalized_timespec(&wall_to_monotonic,		-xtime.tv_sec, -xtime.tv_nsec); 	/* Initialize the linux timer interrupt. */ 	setup_irq(LINUX_TIMER_INT, &timer_irqaction);	set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);}  int do_settimeofday(struct timespec *tv){	time_t wtm_sec, sec = tv->tv_sec;	long wtm_nsec, nsec = tv->tv_nsec;	unsigned long ccount; 	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!	 */	ccount = get_ccount();	nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC; 	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);	return 0;} EXPORT_SYMBOL(do_settimeofday);  void do_gettimeofday(struct timeval *tv){	unsigned long flags;	unsigned long sec, usec, delta, seq; 	do {		seq = read_seqbegin_irqsave(&xtime_lock, flags); 		delta = get_ccount() - last_ccount_stamp;		sec = xtime.tv_sec;		usec = (xtime.tv_nsec / NSEC_PER_USEC);	} while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); 	usec += (delta * CCOUNT_NSEC) / NSEC_PER_USEC;	for (; usec >= 1000000; sec++, usec -= 1000000)		; 	tv->tv_sec = sec;	tv->tv_usec = usec;} EXPORT_SYMBOL(do_gettimeofday); /* * The timer interrupt is called HZ times per second. */ irqreturn_t timer_interrupt (int irq, void *dev_id){ 	unsigned long next; 	next = get_linux_timer(); again:	while ((signed long)(get_ccount() - next) > 0) { 		profile_tick(CPU_PROFILING);#ifndef CONFIG_SMP		update_process_times(user_mode(get_irq_regs()));#endif 		write_seqlock(&xtime_lock); 		last_ccount_stamp = next;		next += CCOUNT_PER_JIFFY;		do_timer (1); /* Linux handler in kernel/timer.c */ 		if (ntp_synced() &&		    xtime.tv_sec - last_rtc_update >= 659 &&		    abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ) { 			if (platform_set_rtc_time(xtime.tv_sec+1) == 0)				last_rtc_update = xtime.tv_sec+1;			else				/* Do it again in 60 s */				last_rtc_update += 60;		}		write_sequnlock(&xtime_lock);	} 	/* NOTE: writing CCOMPAREn clears the interrupt.  */ 	set_linux_timer (next); 	/* Make sure we didn't miss any tick... */ 	if ((signed long)(get_ccount() - next) > 0)		goto again; 	/* Allow platform to do something useful (Wdog). */ 	platform_heartbeat(); 	return IRQ_HANDLED;} #ifndef CONFIG_GENERIC_CALIBRATE_DELAYvoid __devinit calibrate_delay(void){	loops_per_jiffy = CCOUNT_PER_JIFFY;	printk("Calibrating delay loop (skipped)... "	       "%lu.%02lu BogoMIPS preset\n",	       loops_per_jiffy/(1000000/HZ),	       (loops_per_jiffy/(10000/HZ)) % 100);}#endif