arch/mips/baget/time.c

   1 /* $Id: time.c,v 1.3 1999/08/17 22:18:37 ralf Exp $
   2  * time.c: Baget/MIPS specific time handling details
   3  *
   4  * Copyright (C) 1998 Gleb Raiko & Vladimir Roganov
   5  */
   6
   7 #include <linux/errno.h>
   8 #include <linux/init.h>
   9 #include <linux/sched.h>
  10 #include <linux/kernel.h>
  11 #include <linux/param.h>
  12 #include <linux/string.h>
  13 #include <linux/mm.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/timex.h>
  16 #include <linux/kernel_stat.h>
  17
  18 #include <asm/bootinfo.h>
  19 #include <asm/io.h>
  20 #include <asm/irq.h>
  21 #include <asm/ptrace.h>
  22 #include <asm/system.h>
  23
  24 #include <asm/baget/baget.h>
  25
  26 /*
  27  *  To have precision clock, we need to fix available clock frequency
  28  */
  29 #define FREQ_NOM  79125  /* Baget frequency ratio */
  30 #define FREQ_DEN  10000
  31 static inline int timer_intr_valid(void)
  32 {
  33         static unsigned long long ticks, valid_ticks;
  34
  35         if (ticks++ * FREQ_DEN >= valid_ticks * FREQ_NOM) {
  36                 /*
  37                  *  We need no overflow checks,
  38                  *  due baget unable to work 3000 years...
  39                  *  At least without reboot...
  40                  */
  41                 valid_ticks++;
  42                 return 1;
  43         }
  44         return 0;
  45 }
  46
  47 void static timer_interrupt(int irq, void *dev_id, struct pt_regs * regs)
  48 {
  49         if (timer_intr_valid()) {
  50         sti();
  51         do_timer(regs);
  52         }
  53 }
  54
  55 static void __init timer_enable(void)
  56 {
  57         unsigned char ss0cr0 = vic_inb(VIC_SS0CR0);
  58         ss0cr0 &= ~VIC_SS0CR0_TIMER_FREQ_MASK;
  59         ss0cr0 |= VIC_SS0CR0_TIMER_FREQ_1000HZ;
  60         vic_outb(ss0cr0, VIC_SS0CR0);
  61
  62         vic_outb(VIC_INT_IPL(6)|VIC_INT_NOAUTO|VIC_INT_EDGE|
  63                  VIC_INT_LOW|VIC_INT_ENABLE, VIC_LINT2);
  64 }
  65
  66 static struct irqaction timer_irq  =
  67 { timer_interrupt, SA_INTERRUPT, 0, "timer", NULL, NULL};
  68
  69 void __init time_init(void)
  70 {
  71         if (setup_baget_irq(BAGET_VIC_TIMER_IRQ, &timer_irq) < 0)
  72                 printk("time_init: unable request irq for system timer\n");
  73         timer_enable();
  74         /* We don't call sti() here, because it is too early for baget */
  75 }
  76
  77 void do_gettimeofday(struct timeval *tv)
  78 {
  79         unsigned long flags;
  80
  81         save_and_cli(flags);
  82         *tv = xtime;
  83         restore_flags(flags);
  84 }
  85
  86 void do_settimeofday(struct timeval *tv)
  87 {
  88         unsigned long flags;
  89
  90         save_and_cli(flags);
  91         xtime = *tv;
  92         time_state = TIME_BAD;
  93         time_maxerror = MAXPHASE;
  94         time_esterror = MAXPHASE;
  95         restore_flags(flags);
  96 }