arch/frv/kernel/time.c

   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
  33 unsigned long __nongprelbss __clkin_clock_speed_HZ;
  34 unsigned long __nongprelbss __ext_bus_clock_speed_HZ;
  35 unsigned long __nongprelbss __res_bus_clock_speed_HZ;
  36 unsigned long __nongprelbss __sdram_clock_speed_HZ;
  37 unsigned long __nongprelbss __core_bus_clock_speed_HZ;
  38 unsigned long __nongprelbss __core_clock_speed_HZ;
  39 unsigned long __nongprelbss __dsu_clock_speed_HZ;
  40 unsigned long __nongprelbss __serial_clock_speed_HZ;
  41 unsigned long __delay_loops_MHz;
  42
  43 static irqreturn_t timer_interrupt(int irq, void *dummy);
  44
  45 static struct irqaction timer_irq  = {
  46         timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "timer", NULL, NULL
  47 };
  48
  49 static inline int set_rtc_mmss(unsigned long nowtime)
  50 {
  51         return -1;
  52 }
  53
  54 /*
  55  * timer_interrupt() needs to keep up the real-time clock,
  56  * as well as call the "do_timer()" routine every clocktick
  57  */
  58 static irqreturn_t timer_interrupt(int irq, void *dummy)
  59 {
  60         /* last time the cmos clock got updated */
  61         static long last_rtc_update = 0;
  62
  63         /*
  64          * Here we are in the timer irq handler. We just have irqs locally
  65          * disabled but we don't know if the timer_bh is running on the other
  66          * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
  67          * the irq version of write_lock because as just said we have irq
  68          * locally disabled. -arca
  69          */
  70         write_seqlock(&xtime_lock);
  71
  72         do_timer(1);
  73         update_process_times(user_mode(get_irq_regs()));
  74         profile_tick(CPU_PROFILING);
  75
  76         /*
  77          * If we have an externally synchronized Linux clock, then update
  78          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  79          * called as close as possible to 500 ms before the new second starts.
  80          */
  81         if (ntp_synced() &&
  82             xtime.tv_sec > last_rtc_update + 660 &&
  83             (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
  84             (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2
  85             ) {
  86                 if (set_rtc_mmss(xtime.tv_sec) == 0)
  87                         last_rtc_update = xtime.tv_sec;
  88                 else
  89                         last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  90         }
  91
  92 #ifdef CONFIG_HEARTBEAT
  93         static unsigned short n;
  94         n++;
  95         __set_LEDS(n);
  96 #endif /* CONFIG_HEARTBEAT */
  97
  98         write_sequnlock(&xtime_lock);
  99         return IRQ_HANDLED;
 100 }
 101
 102 void time_divisor_init(void)
 103 {
 104         unsigned short base, pre, prediv;
 105
 106         /* set the scheduling timer going */
 107         pre = 1;
 108         prediv = 4;
 109         base = __res_bus_clock_speed_HZ / pre / HZ / (1 << prediv);
 110
 111         __set_TPRV(pre);
 112         __set_TxCKSL_DATA(0, prediv);
 113         __set_TCTR(TCTR_SC_CTR0 | TCTR_RL_RW_LH8 | TCTR_MODE_2);
 114         __set_TCSR_DATA(0, base & 0xff);
 115         __set_TCSR_DATA(0, base >> 8);
 116 }
 117
 118 void time_init(void)
 119 {
 120         unsigned int year, mon, day, hour, min, sec;
 121
 122         extern void arch_gettod(int *year, int *mon, int *day, int *hour, int *min, int *sec);
 123
 124         /* FIX by dqg : Set to zero for platforms that don't have tod */
 125         /* without this time is undefined and can overflow time_t, causing  */
 126         /* very stange errors */
 127         year = 1980;
 128         mon = day = 1;
 129         hour = min = sec = 0;
 130         arch_gettod (&year, &mon, &day, &hour, &min, &sec);
 131
 132         if ((year += 1900) < 1970)
 133                 year += 100;
 134         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
 135         xtime.tv_nsec = 0;
 136
 137         /* install scheduling interrupt handler */
 138         setup_irq(IRQ_CPU_TIMER0, &timer_irq);
 139
 140         time_divisor_init();
 141 }
 142
 143 /*
 144  * Scheduler clock - returns current time in nanosec units.
 145  */
 146 unsigned long long sched_clock(void)
 147 {
 148         return jiffies_64 * (1000000000 / HZ);
 149 }