/* * 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/sched.h>#include <linux/time.h>#include <linux/clocksource.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> #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNTunsigned long ccount_per_jiffy;		/* per 1/HZ */unsigned long nsec_per_ccount;		/* nsec per ccount increment */#endif static cycle_t ccount_read(void){	return (cycle_t)get_ccount();} static struct clocksource ccount_clocksource = {	.name = "ccount",	.rating = 200,	.read = ccount_read,	.mask = CLOCKSOURCE_MASK(32),	/*	 * With a shift of 22 the lower limit of the cpu clock is	 * 1MHz, where NSEC_PER_CCOUNT is 1000 or a bit less than	 * 2^10: Since we have 32 bits and the multiplicator can	 * already take up as much as 10 bits, this leaves us with	 * remaining upper 22 bits.	 */	.shift = 22,}; 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){#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	ccount_clocksource.mult =		clocksource_hz2mult(CCOUNT_PER_JIFFY * HZ,				ccount_clocksource.shift);	clocksource_register(&ccount_clocksource); 	/* Initialize the linux timer interrupt. */ 	setup_irq(LINUX_TIMER_INT, &timer_irqaction);	set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);} /* * 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 		xtime_update(1); /* Linux handler in kernel/time/timekeeping */ 		/* Note that writing CCOMPARE clears the interrupt. */ 		next += CCOUNT_PER_JIFFY;		set_linux_timer(next);	} 	/* Allow platform to do something useful (Wdog). */ 	platform_heartbeat(); 	/* Make sure we didn't miss any tick... */ 	if ((signed long)(get_ccount() - next) > 0)		goto again; 	return IRQ_HANDLED;} #ifndef CONFIG_GENERIC_CALIBRATE_DELAYvoid __cpuinit 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