arch/mips/baget/time.c

   1 /*
   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/spinlock.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 extern rwlock_t xtime_lock;
  27
  28 /*
  29  *  To have precision clock, we need to fix available clock frequency
  30  */
  31 #define FREQ_NOM  79125  /* Baget frequency ratio */
  32 #define FREQ_DEN  10000
  33
  34 static inline int timer_intr_valid(void)
  35 {
  36         static unsigned long long ticks, valid_ticks;
  37
  38         if (ticks++ * FREQ_DEN >= valid_ticks * FREQ_NOM) {
  39                 /*
  40                  *  We need no overflow checks,
  41                  *  due baget unable to work 3000 years...
  42                  *  At least without reboot...
  43                  */
  44                 valid_ticks++;
  45                 return 1;
  46         }
  47         return 0;
  48 }
  49
  50 void static timer_interrupt(int irq, void *dev_id, struct pt_regs * regs)
  51 {
  52         if (timer_intr_valid()) {
  53                 sti();
  54                 do_timer(regs);
  55         }
  56 }
  57
  58 static void __init timer_enable(void)
  59 {
  60         unsigned char ss0cr0 = vic_inb(VIC_SS0CR0);
  61         ss0cr0 &= ~VIC_SS0CR0_TIMER_FREQ_MASK;
  62         ss0cr0 |= VIC_SS0CR0_TIMER_FREQ_1000HZ;
  63         vic_outb(ss0cr0, VIC_SS0CR0);
  64
  65         vic_outb(VIC_INT_IPL(6)|VIC_INT_NOAUTO|VIC_INT_EDGE|
  66                  VIC_INT_LOW|VIC_INT_ENABLE, VIC_LINT2);
  67 }
  68
  69 static struct irqaction timer_irq  =
  70 { timer_interrupt, SA_INTERRUPT, 0, "timer", NULL, NULL};
  71
  72 void __init time_init(void)
  73 {
  74         if (setup_baget_irq(BAGET_VIC_TIMER_IRQ, &timer_irq) < 0)
  75                 printk("time_init: unable request irq for system timer\n");
  76         timer_enable();
  77         /* We don't call sti() here, because it is too early for baget */
  78 }
  79
  80 void do_gettimeofday(struct timeval *tv)
  81 {
  82         unsigned long flags;
  83
  84         read_lock_irqsave (&xtime_lock, flags);
  85         *tv = xtime;
  86         read_unlock_irqrestore (&xtime_lock, flags);
  87 }
  88
  89 void do_settimeofday(struct timeval *tv)
  90 {
  91         write_lock_irq (&xtime_lock);
  92         xtime = *tv;
  93         time_adjust = 0;                /* stop active adjtime() */
  94         time_status |= STA_UNSYNC;
  95         time_maxerror = NTP_PHASE_LIMIT;
  96         time_esterror = NTP_PHASE_LIMIT;
  97         write_unlock_irq (&xtime_lock);
  98 }