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/* 
 *  This file implements a benchmark timer using a MONGOOSE-V timer.
 *
 *  COPYRIGHT (c) 1989-2001.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in found in the file LICENSE in this distribution or at
 *  http://www.OARcorp.com/rtems/license.html.
 *
 *  timer.c,v 1.6 2002/02/01 19:30:54 joel Exp
 */
 
#include <assert.h>
 
#include <bsp.h>
 
rtems_boolean Timer_driver_Find_average_overhead;
 
#if defined(USE_TIMER2_FOR_CLOCK)
#define TIMER_BASE   MONGOOSEV_TIMER1_BASE
#define TIMER_VECTOR MONGOOSEV_IRQ_TIMER1
#else
#define TIMER_BASE   MONGOOSEV_TIMER2_BASE
#define TIMER_VECTOR MONGOOSEV_IRQ_TIMER2
#endif
 
void Timer_initialize()
{
  /*
   *  Programming the compare register as the maximum value should let
   *  it run long enough and accurate enough not to require an interrupt.
   *  but if it ever does generate an interrupt, we will simply fault.
   *
   *  NOTE:  This is similar to the clock driver initialization
   *         with the exception that the divider is disabled and
   *         the compare register is set to the maximum value.
   */
 
   MONGOOSEV_WRITE_REGISTER( TIMER_BASE, MONGOOSEV_TIMER_CONTROL_REGISTER, 0);
 
   MONGOOSEV_WRITE_REGISTER( TIMER_BASE,
			     MONGOOSEV_TIMER_INITIAL_COUNTER_REGISTER,
			     0xffffffff );
 
   MONGOOSEV_WRITE_REGISTER( TIMER_BASE,
			     MONGOOSEV_TIMER_CONTROL_REGISTER,
			     MONGOOSEV_TIMER_CONTROL_COUNTER_ENABLE );
 
}
 
#define AVG_OVERHEAD      0  /* It typically takes N instructions */
                             /*     to start/stop the timer. */
 
#define LEAST_VALID       1  /* Don't trust a value lower than this */
                             /* mongoose-v can count cycles. :) */
#include <rtems/bspIo.h>
 
int Read_timer()
{
  rtems_unsigned32  clicks;
  rtems_unsigned32  total;
  rtems_unsigned32  tcr;
 
  clicks = MONGOOSEV_READ_REGISTER( TIMER_BASE,
				    MONGOOSEV_TIMER_INITIAL_COUNTER_REGISTER );
  total = 0xffffffff - clicks;
 
  tcr = MONGOOSEV_READ_REGISTER( TIMER_BASE, MONGOOSEV_TIMER_CONTROL_REGISTER );
 
  MONGOOSEV_WRITE_REGISTER( TIMER_BASE, 
			    MONGOOSEV_TIMER_CONTROL_REGISTER, 
			    0 );
 
  if ( tcr & MONGOOSEV_TIMER_CONTROL_TIMEOUT )
    printk( "MG5 timer overran\n" );
 
  if ( Timer_driver_Find_average_overhead == 1 )
    return total;          /* in cycle units */
 
  if ( total < LEAST_VALID )
    return 0;            /* below timer resolution */
 
  return (total - AVG_OVERHEAD) / CPU_CLOCK_RATE_MHZ;
}
 
rtems_status_code Empty_function( void )
{
  return RTEMS_SUCCESSFUL;
}
 
void Set_find_average_overhead(
  rtems_boolean find_flag
)
{
  Timer_driver_Find_average_overhead = find_flag;
}
 
 
/* eof */