source: rtems/c/src/lib/libbsp/i386/force386/clock/ckinit.c @ ac7d5ef0

/*  Clock_initialize
 *
 *  This routine initializes the Motorola MFP 68901 on the
 *  FORCE CPU386 board.  The tick frequency is 1 millisecond.
 *
 *  Input parameters:  NONE
 *
 *  Output parameters:  NONE
 *
 *  COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994.
 *  On-Line Applications Research Corporation (OAR).
 *  All rights assigned to U.S. Government, 1994.
 *
 *  This material may be reproduced by or for the U.S. Government pursuant
 *  to the copyright license under the clause at DFARS 252.227-7013.  This
 *  notice must appear in all copies of this file and its derivatives.
 *
 *  $Id$
 */

#include <bsp.h>
#include <clockdrv.h>
#include <stdlib.h>

volatile rtems_unsigned32 Clock_driver_ticks;
rtems_unsigned32 Clock_isrs;              /* ISRs until next tick */
rtems_isr_entry  Old_ticker;

rtems_device_driver Clock_initialize(
  rtems_device_major_number major,
  rtems_device_minor_number minor,
  void *pargp,
  rtems_id tid,
  rtems_unsigned32 *rval
)
{
  Install_clock( Clock_isr );
}

void ReInstall_clock(
  rtems_isr_entry clock_isr
)
{
  rtems_unsigned32 isrlevel = 0;

  rtems_interrupt_disable( isrlevel );
   (void) set_vector( clock_isr, 0x38, 1 );
  rtems_interrupt_enable( isrlevel );
}

void Install_clock(
  rtems_isr_entry clock_isr
)
{
  Clock_driver_ticks = 0;
  Clock_isrs = BSP_Configuration.microseconds_per_tick / 1000;

  if ( BSP_Configuration.ticks_per_timeslice ) {
    Old_ticker = ( rtems_isr_entry ) set_vector( clock_isr, 0x38, 1 );
    outport_byte( TBCR, 0x14 );  /* reset it, delay mode, 50X */
    outport_byte( TBDR, 0x50 );  /* 1 millisecond */
    outport_byte( IERA, 0x41 );  /* enable interrupt for B */
  }
  atexit( Clock_exit );
}

void Clock_exit( void )
{
  if ( BSP_Configuration.ticks_per_timeslice ) {
    outport_byte( TBCR, 0x00 );  /* initial value */
    outport_byte( IERA, 0x40 );  /* disable interrupt */
    /* ??? Is "do not restore old vector" causing problems? */
  }
}