linux/arch/frv/kernel/time.c
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   1/* time.c: FRV arch-specific time handling
   2 *
   3 * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 * - Derived from arch/m68k/kernel/time.c
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License
   9 * as published by the Free Software Foundation; either version
  10 * 2 of the License, or (at your option) any later version.
  11 */
  12
  13#include <linux/module.h>
  14#include <linux/errno.h>
  15#include <linux/sched.h>
  16#include <linux/kernel.h>
  17#include <linux/param.h>
  18#include <linux/string.h>
  19#include <linux/interrupt.h>
  20#include <linux/profile.h>
  21#include <linux/irq.h>
  22#include <linux/mm.h>
  23
  24#include <asm/io.h>
  25#include <asm/timer-regs.h>
  26#include <asm/mb-regs.h>
  27#include <asm/mb86943a.h>
  28
  29#include <linux/timex.h>
  30
  31#define TICK_SIZE (tick_nsec / 1000)
  32
  33unsigned long __nongprelbss __clkin_clock_speed_HZ;
  34unsigned long __nongprelbss __ext_bus_clock_speed_HZ;
  35unsigned long __nongprelbss __res_bus_clock_speed_HZ;
  36unsigned long __nongprelbss __sdram_clock_speed_HZ;
  37unsigned long __nongprelbss __core_bus_clock_speed_HZ;
  38unsigned long __nongprelbss __core_clock_speed_HZ;
  39unsigned long __nongprelbss __dsu_clock_speed_HZ;
  40unsigned long __nongprelbss __serial_clock_speed_HZ;
  41unsigned long __delay_loops_MHz;
  42
  43static irqreturn_t timer_interrupt(int irq, void *dummy);
  44
  45static struct irqaction timer_irq  = {
  46        .handler = timer_interrupt,
  47        .flags = IRQF_DISABLED,
  48        .name = "timer",
  49};
  50
  51static inline int set_rtc_mmss(unsigned long nowtime)
  52{
  53        return -1;
  54}
  55
  56/*
  57 * timer_interrupt() needs to keep up the real-time clock,
  58 * as well as call the "do_timer()" routine every clocktick
  59 */
  60static irqreturn_t timer_interrupt(int irq, void *dummy)
  61{
  62        /* last time the cmos clock got updated */
  63        static long last_rtc_update = 0;
  64
  65        profile_tick(CPU_PROFILING);
  66        /*
  67         * Here we are in the timer irq handler. We just have irqs locally
  68         * disabled but we don't know if the timer_bh is running on the other
  69         * CPU. We need to avoid to SMP race with it. NOTE: we don't need
  70         * the irq version of write_lock because as just said we have irq
  71         * locally disabled. -arca
  72         */
  73        write_seqlock(&xtime_lock);
  74
  75        do_timer(1);
  76
  77        /*
  78         * If we have an externally synchronized Linux clock, then update
  79         * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  80         * called as close as possible to 500 ms before the new second starts.
  81         */
  82        if (ntp_synced() &&
  83            xtime.tv_sec > last_rtc_update + 660 &&
  84            (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
  85            (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2
  86            ) {
  87                if (set_rtc_mmss(xtime.tv_sec) == 0)
  88                        last_rtc_update = xtime.tv_sec;
  89                else
  90                        last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  91        }
  92
  93#ifdef CONFIG_HEARTBEAT
  94        static unsigned short n;
  95        n++;
  96        __set_LEDS(n);
  97#endif /* CONFIG_HEARTBEAT */
  98
  99        write_sequnlock(&xtime_lock);
 100
 101        update_process_times(user_mode(get_irq_regs()));
 102
 103        return IRQ_HANDLED;
 104}
 105
 106void time_divisor_init(void)
 107{
 108        unsigned short base, pre, prediv;
 109
 110        /* set the scheduling timer going */
 111        pre = 1;
 112        prediv = 4;
 113        base = __res_bus_clock_speed_HZ / pre / HZ / (1 << prediv);
 114
 115        __set_TPRV(pre);
 116        __set_TxCKSL_DATA(0, prediv);
 117        __set_TCTR(TCTR_SC_CTR0 | TCTR_RL_RW_LH8 | TCTR_MODE_2);
 118        __set_TCSR_DATA(0, base & 0xff);
 119        __set_TCSR_DATA(0, base >> 8);
 120}
 121
 122void time_init(void)
 123{
 124        unsigned int year, mon, day, hour, min, sec;
 125
 126        extern void arch_gettod(int *year, int *mon, int *day, int *hour, int *min, int *sec);
 127
 128        /* FIX by dqg : Set to zero for platforms that don't have tod */
 129        /* without this time is undefined and can overflow time_t, causing  */
 130        /* very strange errors */
 131        year = 1980;
 132        mon = day = 1;
 133        hour = min = sec = 0;
 134        arch_gettod (&year, &mon, &day, &hour, &min, &sec);
 135
 136        if ((year += 1900) < 1970)
 137                year += 100;
 138        xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
 139        xtime.tv_nsec = 0;
 140
 141        /* install scheduling interrupt handler */
 142        setup_irq(IRQ_CPU_TIMER0, &timer_irq);
 143
 144        time_divisor_init();
 145}
 146
 147/*
 148 * Scheduler clock - returns current time in nanosec units.
 149 */
 150unsigned long long sched_clock(void)
 151{
 152        return jiffies_64 * (1000000000 / HZ);
 153}
 154