/* * 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_CCOUNT unsigned 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; /* * Scheduler clock - returns current tim in nanosec units. */ unsigned long long sched_clock(void) { return (unsigned long long)jiffies * (1000000000 / HZ); } static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs); 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, struct pt_regs *regs) { unsigned long next; next = get_linux_timer(); again: while ((signed long)(get_ccount() - next) > 0) { profile_tick(CPU_PROFILING, regs); #ifndef CONFIG_SMP update_process_times(user_mode(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_DELAY void __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