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sim_time.c

#include <linux/types.h>
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/mc146818rtc.h>
#include <linux/smp.h>
#include <linux/timex.h>

#include <asm/hardirq.h>
#include <asm/div64.h>
#include <asm/cpu.h>
#include <asm/time.h>
#include <asm/irq.h>
#include <asm/mc146818-time.h>
#include <asm/msc01_ic.h>

#include <asm/mips-boards/generic.h>
#include <asm/mips-boards/prom.h>
#include <asm/mips-boards/simint.h>


unsigned long cpu_khz;

/*
 * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect
 */
static unsigned int __init estimate_cpu_frequency(void)
{
      unsigned int prid = read_c0_prid() & 0xffff00;
      unsigned int count;

#if 1
      /*
       * hardwire the board frequency to 12MHz.
       */

      if ((prid == (PRID_COMP_MIPS | PRID_IMP_20KC)) ||
          (prid == (PRID_COMP_MIPS | PRID_IMP_25KF)))
            count = 12000000;
      else
            count =  6000000;
#else
      unsigned int flags;

      local_irq_save(flags);

      /* Start counter exactly on falling edge of update flag */
      while (CMOS_READ(RTC_REG_A) & RTC_UIP);
      while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));

      /* Start r4k counter. */
      write_c0_count(0);

      /* Read counter exactly on falling edge of update flag */
      while (CMOS_READ(RTC_REG_A) & RTC_UIP);
      while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));

      count = read_c0_count();

      /* restore interrupts */
      local_irq_restore(flags);
#endif

      mips_hpt_frequency = count;

      if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
          (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
            count *= 2;

      count += 5000;    /* round */
      count -= count%10000;

      return count;
}

static int mips_cpu_timer_irq;

static void mips_timer_dispatch(void)
{
      do_IRQ(mips_cpu_timer_irq);
}


unsigned __cpuinit get_c0_compare_int(void)
{
#ifdef MSC01E_INT_BASE
      if (cpu_has_veic) {
            set_vi_handler(MSC01E_INT_CPUCTR, mips_timer_dispatch);
            mips_cpu_timer_irq = MSC01E_INT_BASE + MSC01E_INT_CPUCTR;
      } else {
#endif
            if (cpu_has_vint)
                  set_vi_handler(cp0_compare_irq, mips_timer_dispatch);
            mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
      }

      return mips_cpu_timer_irq;
}

void __init plat_time_init(void)
{
      unsigned int est_freq;

      /* Set Data mode - binary. */
      CMOS_WRITE(CMOS_READ(RTC_CONTROL) | RTC_DM_BINARY, RTC_CONTROL);

      est_freq = estimate_cpu_frequency();

      printk(KERN_INFO "CPU frequency %d.%02d MHz\n", est_freq / 1000000,
             (est_freq % 1000000) * 100 / 1000000);

      cpu_khz = est_freq / 1000;
}

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