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/config.h> /* CONFIG_HEARTBEAT */
  14 #include <linux/module.h>
  15 #include <linux/errno.h>
  16 #include <linux/sched.h>
  17 #include <linux/kernel.h>
  18 #include <linux/param.h>
  19 #include <linux/string.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/profile.h>
  22 #include <linux/irq.h>
  23 #include <linux/mm.h>
  24
  25 #include <asm/io.h>
  26 #include <asm/timer-regs.h>
  27 #include <asm/mb-regs.h>
  28 #include <asm/mb86943a.h>
  29
  30 #include <linux/timex.h>
  31
  32 #define TICK_SIZE (tick_nsec / 1000)
  33
  34 unsigned long __nongprelbss __clkin_clock_speed_HZ;
  35 unsigned long __nongprelbss __ext_bus_clock_speed_HZ;
  36 unsigned long __nongprelbss __res_bus_clock_speed_HZ;
  37 unsigned long __nongprelbss __sdram_clock_speed_HZ;
  38 unsigned long __nongprelbss __core_bus_clock_speed_HZ;
  39 unsigned long __nongprelbss __core_clock_speed_HZ;
  40 unsigned long __nongprelbss __dsu_clock_speed_HZ;
  41 unsigned long __nongprelbss __serial_clock_speed_HZ;
  42 unsigned long __delay_loops_MHz;
  43
  44 static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs *regs);
  45
  46 static struct irqaction timer_irq  = {
  47         timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "timer", NULL, NULL
  48 };
  49
  50 static inline int set_rtc_mmss(unsigned long nowtime)
  51 {
  52         return -1;
  53 }
  54
  55 /*
  56  * timer_interrupt() needs to keep up the real-time clock,
  57  * as well as call the "do_timer()" routine every clocktick
  58  */
  59 static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
  60 {
  61         /* last time the cmos clock got updated */
  62         static long last_rtc_update = 0;
  63
  64         /*
  65          * Here we are in the timer irq handler. We just have irqs locally
  66          * disabled but we don't know if the timer_bh is running on the other
  67          * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
  68          * the irq version of write_lock because as just said we have irq
  69          * locally disabled. -arca
  70          */
  71         write_seqlock(&xtime_lock);
  72
  73         do_timer(1);
  74         update_process_times(user_mode(regs));
  75         profile_tick(CPU_PROFILING, regs);
  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         return IRQ_HANDLED;
 101 }
 102
 103 void time_divisor_init(void)
 104 {
 105         unsigned short base, pre, prediv;
 106
 107         /* set the scheduling timer going */
 108         pre = 1;
 109         prediv = 4;
 110         base = __res_bus_clock_speed_HZ / pre / HZ / (1 << prediv);
 111
 112         __set_TPRV(pre);
 113         __set_TxCKSL_DATA(0, prediv);
 114         __set_TCTR(TCTR_SC_CTR0 | TCTR_RL_RW_LH8 | TCTR_MODE_2);
 115         __set_TCSR_DATA(0, base & 0xff);
 116         __set_TCSR_DATA(0, base >> 8);
 117 }
 118
 119 void time_init(void)
 120 {
 121         unsigned int year, mon, day, hour, min, sec;
 122
 123         extern void arch_gettod(int *year, int *mon, int *day, int *hour, int *min, int *sec);
 124
 125         /* FIX by dqg : Set to zero for platforms that don't have tod */
 126         /* without this time is undefined and can overflow time_t, causing  */
 127         /* very stange errors */
 128         year = 1980;
 129         mon = day = 1;
 130         hour = min = sec = 0;
 131         arch_gettod (&year, &mon, &day, &hour, &min, &sec);
 132
 133         if ((year += 1900) < 1970)
 134                 year += 100;
 135         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
 136         xtime.tv_nsec = 0;
 137
 138         /* install scheduling interrupt handler */
 139         setup_irq(IRQ_CPU_TIMER0, &timer_irq);
 140
 141         time_divisor_init();
 142 }
 143
 144 /*
 145  * Scheduler clock - returns current time in nanosec units.
 146  */
 147 unsigned long long sched_clock(void)
 148 {
 149         return jiffies_64 * (1000000000 / HZ);
 150 }