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         .handler = timer_interrupt,
  47         .flags = IRQF_DISABLED,
  48         .mask = CPU_MASK_NONE,
  49         .name = "timer",
  50 };
  51
  52 static inline int set_rtc_mmss(unsigned long nowtime)
  53 {
  54         return -1;
  55 }
  56
  57 /*
  58  * timer_interrupt() needs to keep up the real-time clock,
  59  * as well as call the "do_timer()" routine every clocktick
  60  */
  61 static irqreturn_t timer_interrupt(int irq, void *dummy)
  62 {
  63         /* last time the cmos clock got updated */
  64         static long last_rtc_update = 0;
  65
  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         update_process_times(user_mode(get_irq_regs()));
  77         profile_tick(CPU_PROFILING);
  78
  79         /*
  80          * If we have an externally synchronized Linux clock, then update
  81          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  82          * called as close as possible to 500 ms before the new second starts.
  83          */
  84         if (ntp_synced() &&
  85             xtime.tv_sec > last_rtc_update + 660 &&
  86             (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
  87             (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2
  88             ) {
  89                 if (set_rtc_mmss(xtime.tv_sec) == 0)
  90                         last_rtc_update = xtime.tv_sec;
  91                 else
  92                         last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  93         }
  94
  95 #ifdef CONFIG_HEARTBEAT
  96         static unsigned short n;
  97         n++;
  98         __set_LEDS(n);
  99 #endif /* CONFIG_HEARTBEAT */
 100
 101         write_sequnlock(&xtime_lock);
 102         return IRQ_HANDLED;
 103 }
 104
 105 void time_divisor_init(void)
 106 {
 107         unsigned short base, pre, prediv;
 108
 109         /* set the scheduling timer going */
 110         pre = 1;
 111         prediv = 4;
 112         base = __res_bus_clock_speed_HZ / pre / HZ / (1 << prediv);
 113
 114         __set_TPRV(pre);
 115         __set_TxCKSL_DATA(0, prediv);
 116         __set_TCTR(TCTR_SC_CTR0 | TCTR_RL_RW_LH8 | TCTR_MODE_2);
 117         __set_TCSR_DATA(0, base & 0xff);
 118         __set_TCSR_DATA(0, base >> 8);
 119 }
 120
 121 void time_init(void)
 122 {
 123         unsigned int year, mon, day, hour, min, sec;
 124
 125         extern void arch_gettod(int *year, int *mon, int *day, int *hour, int *min, int *sec);
 126
 127         /* FIX by dqg : Set to zero for platforms that don't have tod */
 128         /* without this time is undefined and can overflow time_t, causing  */
 129         /* very strange errors */
 130         year = 1980;
 131         mon = day = 1;
 132         hour = min = sec = 0;
 133         arch_gettod (&year, &mon, &day, &hour, &min, &sec);
 134
 135         if ((year += 1900) < 1970)
 136                 year += 100;
 137         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
 138         xtime.tv_nsec = 0;
 139
 140         /* install scheduling interrupt handler */
 141         setup_irq(IRQ_CPU_TIMER0, &timer_irq);
 142
 143         time_divisor_init();
 144 }
 145
 146 /*
 147  * Scheduler clock - returns current time in nanosec units.
 148  */
 149 unsigned long long sched_clock(void)
 150 {
 151         return jiffies_64 * (1000000000 / HZ);
 152 }