text: /*
   *  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 "ints.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 void hp300_tick(int irq, void *dev_id, struct pt_regs *regs)
  {
    unsigned long tmp;
    void (*vector)(int, void *, struct pt_regs *) = dev_id;
    readb(CLOCKBASE + CLKSR);
    asm volatile ("movpw %1@(5),%0" : "=r" (tmp) : "a" (CLOCKBASE));
    vector(irq, NULL, regs);
  }
  
  unsigned long hp300_gettimeoffset(void)
  {
    /* Read current timer 1 value */
    unsigned char lsb, msb1, msb2;
    unsigned short ticks;
  
    msb1 = readb(CLOCKBASE + 5);
    lsb = readb(CLOCKBASE + 7);
    msb2 = readb(CLOCKBASE + 5);
    if (msb1 != msb2)
      /* A carry happened while we were reading.  Read it again */
      lsb = readb(CLOCKBASE + 7);
    ticks = INTVAL - ((msb2 << 8) | lsb);
    return (USECS_PER_JIFFY * ticks) / INTVAL;
  }
  
  void __init hp300_sched_init(void (*vector)(int, void *, struct pt_regs *))
  {
    writeb(0x1, CLOCKBASE + CLKCR2);		/* select CR1 */
    writeb(0x1, CLOCKBASE + CLKCR1);		/* reset */
  
    asm volatile(" movpw %0,%1@(5)" : : "d" (INTVAL), "a" (CLOCKBASE));
  
    sys_request_irq(6, hp300_tick, IRQ_FLG_STD, "timer tick", vector);
  
    writeb(0x1, CLOCKBASE + CLKCR2);		/* select CR1 */
    writeb(0x40, CLOCKBASE + CLKCR1);		/* enable irq */
  }
  