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Diffstat (limited to 'arch/arm26/kernel/time.c')
| -rw-r--r-- | arch/arm26/kernel/time.c | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/arch/arm26/kernel/time.c b/arch/arm26/kernel/time.c new file mode 100644 index 000000000000..549a6b2e177e --- /dev/null +++ b/arch/arm26/kernel/time.c @@ -0,0 +1,234 @@ +/* + * linux/arch/arm26/kernel/time.c + * + * Copyright (C) 1991, 1992, 1995 Linus Torvalds + * Modifications for ARM (C) 1994-2001 Russell King + * Mods for ARM26 (C) 2003 Ian Molton + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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 + * 1998-12-20 Updated NTP code according to technical memorandum Jan '96 + * "A Kernel Model for Precision Timekeeping" by Dave Mills + */ + +#include <linux/config.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/interrupt.h> +#include <linux/time.h> +#include <linux/init.h> +#include <linux/smp.h> +#include <linux/timex.h> +#include <linux/errno.h> +#include <linux/profile.h> + +#include <asm/hardware.h> +#include <asm/io.h> +#include <asm/irq.h> +#include <asm/ioc.h> + +u64 jiffies_64 = INITIAL_JIFFIES; + +EXPORT_SYMBOL(jiffies_64); + +extern unsigned long wall_jiffies; + +/* this needs a better home */ +DEFINE_SPINLOCK(rtc_lock); + +/* change this if you have some constant time drift */ +#define USECS_PER_JIFFY (1000000/HZ) + +static int dummy_set_rtc(void) +{ + return 0; +} + +/* + * hook for setting the RTC's idea of the current time. + */ +int (*set_rtc)(void) = dummy_set_rtc; + +/* + * Get time offset based on IOCs timer. + * FIXME - if this is called with interrutps off, why the shennanigans + * below ? + */ +static unsigned long gettimeoffset(void) +{ + unsigned int count1, count2, status; + long offset; + + ioc_writeb (0, IOC_T0LATCH); + barrier (); + count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8); + barrier (); + status = ioc_readb(IOC_IRQREQA); + barrier (); + ioc_writeb (0, IOC_T0LATCH); + barrier (); + count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8); + + offset = count2; + if (count2 < count1) { + /* + * We have not had an interrupt between reading count1 + * and count2. + */ + if (status & (1 << 5)) + offset -= LATCH; + } else if (count2 > count1) { + /* + * We have just had another interrupt between reading + * count1 and count2. + */ + offset -= LATCH; + } + + offset = (LATCH - offset) * (tick_nsec / 1000); + return (offset + LATCH/2) / LATCH; +} + +/* + * Scheduler clock - returns current time in nanosec units. + */ +unsigned long long sched_clock(void) +{ + return (unsigned long long)jiffies * (1000000000 / HZ); +} + +static unsigned long next_rtc_update; + +/* + * If we have an externally synchronized linux clock, then update + * CMOS clock accordingly every ~11 minutes. set_rtc() has to be + * called as close as possible to 500 ms before the new second + * starts. + */ +static inline void do_set_rtc(void) +{ + if (time_status & STA_UNSYNC || set_rtc == NULL) + return; + +//FIXME - timespec.tv_sec is a time_t not unsigned long + if (next_rtc_update && + time_before((unsigned long)xtime.tv_sec, next_rtc_update)) + return; + + if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) && + xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1)) + return; + + if (set_rtc()) + /* + * rtc update failed. Try again in 60s + */ + next_rtc_update = xtime.tv_sec + 60; + else + next_rtc_update = xtime.tv_sec + 660; +} + +#define do_leds() + +void do_gettimeofday(struct timeval *tv) +{ + unsigned long flags; + unsigned long seq; + unsigned long usec, sec, lost; + + do { + seq = read_seqbegin_irqsave(&xtime_lock, flags); + usec = gettimeoffset(); + + lost = jiffies - wall_jiffies; + if (lost) + usec += lost * USECS_PER_JIFFY; + + sec = xtime.tv_sec; + usec += xtime.tv_nsec / 1000; + } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); + + /* usec may have gone up a lot: be safe */ + while (usec >= 1000000) { + usec -= 1000000; + sec++; + } + + tv->tv_sec = sec; + tv->tv_usec = usec; +} + +EXPORT_SYMBOL(do_gettimeofday); + +int do_settimeofday(struct timespec *tv) +{ + 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 + * done, and then undo it! + */ + tv->tv_nsec -= 1000 * (gettimeoffset() + + (jiffies - wall_jiffies) * USECS_PER_JIFFY); + + while (tv->tv_nsec < 0) { + tv->tv_nsec += NSEC_PER_SEC; + tv->tv_sec--; + } + + xtime.tv_sec = tv->tv_sec; + xtime.tv_nsec = tv->tv_nsec; + time_adjust = 0; /* stop active adjtime() */ + time_status |= STA_UNSYNC; + time_maxerror = NTP_PHASE_LIMIT; + time_esterror = NTP_PHASE_LIMIT; + write_sequnlock_irq(&xtime_lock); + clock_was_set(); + return 0; +} + +EXPORT_SYMBOL(do_settimeofday); + +static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) +{ + do_timer(regs); +#ifndef CONFIG_SMP + update_process_times(user_mode(regs)); +#endif + do_set_rtc(); //FIME - EVERY timer IRQ? + profile_tick(CPU_PROFILING, regs); + return IRQ_HANDLED; //FIXME - is this right? +} + +static struct irqaction timer_irq = { + .name = "timer", + .flags = SA_INTERRUPT, + .handler = timer_interrupt, +}; + +extern void ioctime_init(void); + +/* + * Set up timer interrupt. + */ +void __init time_init(void) +{ + ioc_writeb(LATCH & 255, IOC_T0LTCHL); + ioc_writeb(LATCH >> 8, IOC_T0LTCHH); + ioc_writeb(0, IOC_T0GO); + + + setup_irq(IRQ_TIMER, &timer_irq); +} + |