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time.c

/*
 *  linux/arch/m68k/hp300/time.c
 *
 *  Copyright (C) 1998 Philip Blundell <philb@gnu.org>
 *
 *  This file contains the HP300-specific time handling code.
 */

#include <asm/ptrace.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
#include <asm/machdep.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/traps.h>
#include <asm/blinken.h>

/* Clock hardware definitions */

#define CLOCKBASE 0xf05f8000

#define     CLKCR1            0x1
#define     CLKCR2            0x3
#define     CLKCR3            CLKCR1
#define     CLKSR       CLKCR2
#define     CLKMSB1           0x5
#define     CLKMSB2           0x9
#define     CLKMSB3           0xD

/* This is for machines which generate the exact clock. */
#define USECS_PER_JIFFY (1000000/HZ)

#define INTVAL ((10000 / 4) - 1)

static irqreturn_t hp300_tick(int irq, void *dev_id)
{
      unsigned long tmp;
      irq_handler_t vector = dev_id;
      in_8(CLOCKBASE + CLKSR);
      asm volatile ("movpw %1@(5),%0" : "=d" (tmp) : "a" (CLOCKBASE));
      /* Turn off the network and SCSI leds */
      blinken_leds(0, 0xe0);
      return vector(irq, NULL);
}

unsigned long hp300_gettimeoffset(void)
{
  /* Read current timer 1 value */
  unsigned char lsb, msb1, msb2;
  unsigned short ticks;

  msb1 = in_8(CLOCKBASE + 5);
  lsb = in_8(CLOCKBASE + 7);
  msb2 = in_8(CLOCKBASE + 5);
  if (msb1 != msb2)
    /* A carry happened while we were reading.  Read it again */
    lsb = in_8(CLOCKBASE + 7);
  ticks = INTVAL - ((msb2 << 8) | lsb);
  return (USECS_PER_JIFFY * ticks) / INTVAL;
}

void __init hp300_sched_init(irq_handler_t vector)
{
  out_8(CLOCKBASE + CLKCR2, 0x1);         /* select CR1 */
  out_8(CLOCKBASE + CLKCR1, 0x1);         /* reset */

  asm volatile(" movpw %0,%1@(5)" : : "d" (INTVAL), "a" (CLOCKBASE));

  request_irq(IRQ_AUTO_6, hp300_tick, IRQ_FLG_STD, "timer tick", vector);

  out_8(CLOCKBASE + CLKCR2, 0x1);         /* select CR1 */
  out_8(CLOCKBASE + CLKCR1, 0x40);        /* enable irq */
}

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