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malta-time.c

/*
 * Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
 *
 *  This program is free software; you can distribute it and/or modify it
 *  under the terms of the GNU General Public License (Version 2) as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Setting up the clock on the MIPS boards.
 */

#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/time.h>
#include <linux/timex.h>
#include <linux/mc146818rtc.h>

#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/hardirq.h>
#include <asm/i8253.h>
#include <asm/irq.h>
#include <asm/div64.h>
#include <asm/cpu.h>
#include <asm/time.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/maltaint.h>

unsigned long cpu_khz;

static int mips_cpu_timer_irq;
static int mips_cpu_perf_irq;
extern int cp0_perfcount_irq;

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

static void mips_perf_dispatch(void)
{
      do_IRQ(mips_cpu_perf_irq);
}

/*
 * 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;

      unsigned long flags;
      unsigned int start;

      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. */
      start = read_c0_count();

      /* 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() - start;

      /* restore interrupts */
      local_irq_restore(flags);

      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;
}

unsigned long read_persistent_clock(void)
{
      return mc146818_get_cmos_time();
}

static void __init plat_perf_setup(void)
{
#ifdef MSC01E_INT_BASE
      if (cpu_has_veic) {
            set_vi_handler(MSC01E_INT_PERFCTR, mips_perf_dispatch);
            mips_cpu_perf_irq = MSC01E_INT_BASE + MSC01E_INT_PERFCTR;
      } else
#endif
      if (cp0_perfcount_irq >= 0) {
            if (cpu_has_vint)
                  set_vi_handler(cp0_perfcount_irq, mips_perf_dispatch);
            mips_cpu_perf_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
#ifdef CONFIG_SMP
            set_irq_handler(mips_cpu_perf_irq, handle_percpu_irq);
#endif
      }
}

unsigned int __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("CPU frequency %d.%02d MHz\n", est_freq/1000000,
             (est_freq%1000000)*100/1000000);

        cpu_khz = est_freq / 1000;

      mips_scroll_message();
#ifdef CONFIG_I8253           /* Only Malta has a PIT */
      setup_pit_timer();
#endif

      plat_perf_setup();
}

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