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Diffstat (limited to 'arch/parisc/kernel/time.c')
| -rw-r--r-- | arch/parisc/kernel/time.c | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c new file mode 100644 index 00000000000..6cf7407344b --- /dev/null +++ b/arch/parisc/kernel/time.c @@ -0,0 +1,243 @@ +/* + * linux/arch/parisc/kernel/time.c + * + * Copyright (C) 1991, 1992, 1995 Linus Torvalds + * Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King + * Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org) + * + * 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/errno.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/kernel.h> +#include <linux/param.h> +#include <linux/string.h> +#include <linux/mm.h> +#include <linux/interrupt.h> +#include <linux/time.h> +#include <linux/init.h> +#include <linux/smp.h> +#include <linux/profile.h> + +#include <asm/uaccess.h> +#include <asm/io.h> +#include <asm/irq.h> +#include <asm/param.h> +#include <asm/pdc.h> +#include <asm/led.h> + +#include <linux/timex.h> + +u64 jiffies_64 = INITIAL_JIFFIES; + +EXPORT_SYMBOL(jiffies_64); + +/* xtime and wall_jiffies keep wall-clock time */ +extern unsigned long wall_jiffies; + +static long clocktick; /* timer cycles per tick */ +static long halftick; + +#ifdef CONFIG_SMP +extern void smp_do_timer(struct pt_regs *regs); +#endif + +irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) +{ + long now; + long next_tick; + int nticks; + int cpu = smp_processor_id(); + + profile_tick(CPU_PROFILING, regs); + + now = mfctl(16); + /* initialize next_tick to time at last clocktick */ + next_tick = cpu_data[cpu].it_value; + + /* since time passes between the interrupt and the mfctl() + * above, it is never true that last_tick + clocktick == now. If we + * never miss a clocktick, we could set next_tick = last_tick + clocktick + * but maybe we'll miss ticks, hence the loop. + * + * Variables are *signed*. + */ + + nticks = 0; + while((next_tick - now) < halftick) { + next_tick += clocktick; + nticks++; + } + mtctl(next_tick, 16); + cpu_data[cpu].it_value = next_tick; + + while (nticks--) { +#ifdef CONFIG_SMP + smp_do_timer(regs); +#else + update_process_times(user_mode(regs)); +#endif + if (cpu == 0) { + write_seqlock(&xtime_lock); + do_timer(regs); + write_sequnlock(&xtime_lock); + } + } + +#ifdef CONFIG_CHASSIS_LCD_LED + /* Only schedule the led tasklet on cpu 0, and only if it + * is enabled. + */ + if (cpu == 0 && !atomic_read(&led_tasklet.count)) + tasklet_schedule(&led_tasklet); +#endif + + /* check soft power switch status */ + if (cpu == 0 && !atomic_read(&power_tasklet.count)) + tasklet_schedule(&power_tasklet); + + return IRQ_HANDLED; +} + +/*** converted from ia64 ***/ +/* + * Return the number of micro-seconds that elapsed since the last + * update to wall time (aka xtime aka wall_jiffies). The xtime_lock + * must be at least read-locked when calling this routine. + */ +static inline unsigned long +gettimeoffset (void) +{ +#ifndef CONFIG_SMP + /* + * FIXME: This won't work on smp because jiffies are updated by cpu 0. + * Once parisc-linux learns the cr16 difference between processors, + * this could be made to work. + */ + long last_tick; + long elapsed_cycles; + + /* it_value is the intended time of the next tick */ + last_tick = cpu_data[smp_processor_id()].it_value; + + /* Subtract one tick and account for possible difference between + * when we expected the tick and when it actually arrived. + * (aka wall vs real) + */ + last_tick -= clocktick * (jiffies - wall_jiffies + 1); + elapsed_cycles = mfctl(16) - last_tick; + + /* the precision of this math could be improved */ + return elapsed_cycles / (PAGE0->mem_10msec / 10000); +#else + return 0; +#endif +} + +void +do_gettimeofday (struct timeval *tv) +{ + unsigned long flags, seq, usec, sec; + + do { + seq = read_seqbegin_irqsave(&xtime_lock, flags); + usec = gettimeoffset(); + sec = xtime.tv_sec; + usec += (xtime.tv_nsec / 1000); + } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); + + while (usec >= 1000000) { + usec -= 1000000; + ++sec; + } + + tv->tv_sec = sec; + tv->tv_usec = usec; +} + +EXPORT_SYMBOL(do_gettimeofday); + +int +do_settimeofday (struct timespec *tv) +{ + time_t wtm_sec, sec = tv->tv_sec; + long wtm_nsec, nsec = tv->tv_nsec; + + 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! + */ + nsec -= gettimeoffset() * 1000; + + 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); + + 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); + +/* + * XXX: We can do better than this. + * Returns nanoseconds + */ + +unsigned long long sched_clock(void) +{ + return (unsigned long long)jiffies * (1000000000 / HZ); +} + + +void __init time_init(void) +{ + unsigned long next_tick; + static struct pdc_tod tod_data; + + clocktick = (100 * PAGE0->mem_10msec) / HZ; + halftick = clocktick / 2; + + /* Setup clock interrupt timing */ + + next_tick = mfctl(16); + next_tick += clocktick; + cpu_data[smp_processor_id()].it_value = next_tick; + + /* kick off Itimer (CR16) */ + mtctl(next_tick, 16); + + if(pdc_tod_read(&tod_data) == 0) { + write_seqlock_irq(&xtime_lock); + xtime.tv_sec = tod_data.tod_sec; + xtime.tv_nsec = tod_data.tod_usec * 1000; + set_normalized_timespec(&wall_to_monotonic, + -xtime.tv_sec, -xtime.tv_nsec); + write_sequnlock_irq(&xtime_lock); + } else { + printk(KERN_ERR "Error reading tod clock\n"); + xtime.tv_sec = 0; + xtime.tv_nsec = 0; + } +} + |