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/*

 *  timer for the Hitachi SH 704X

 *

 *  This file manages the benchmark timer used by the RTEMS Timing Test

 *  Suite.  Each measured time period is demarcated by calls to

 *  Timer_initialize() and Read_timer().  Read_timer() usually returns

 *  the number of microseconds since Timer_initialize() exitted.

 *

 *  NOTE: It is important that the timer start/stop overhead be

 *        determined when porting or modifying this code.

 *

 *  Authors: Ralf Corsepius (corsepiu@faw.uni-ulm.de) and

 *           Bernd Becker (becker@faw.uni-ulm.de)

 *

 *  COPYRIGHT (c) 1997-1998, FAW Ulm, Germany

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 *

 *  COPYRIGHT (c) 1998.

 *  On-Line Applications Research Corporation (OAR).

 *  Copyright assigned to U.S. Government, 1994.

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  $Id: timer.c,v 1.2 2001-09-27 12:01:39 chris Exp $

 */

#include <rtems.h>

#include <rtems/score/sh_io.h>

#include <rtems/score/iosh7045.h>

/*

 *  We use a Phi/4 timer

 */

#define SCALE (Timer_MHZ/4)

#define MTU1_STARTMASK  0xfd

#define MTU1_SYNCMASK   0xfd

#define MTU1_MODEMASK   0xc0

#define MTU1_TCRMASK    0x01

#define MTU1_TIORMASK   0x88

#define MTU1_STAT_MASK  0xf8

#define MTU1_TIERMASK   0xfc

#define IPRC_MTU1_MASK  0xfff0

#ifndef MTU1_PRIO

#define MTU1_PRIO 15

#endif

#define MTU1_VECTOR 86

rtems_isr timerisr();

static rtems_unsigned32 Timer_interrupts;

rtems_boolean Timer_driver_Find_average_overhead;

static rtems_unsigned32 Timer_MHZ ;

void Timer_initialize( void )

{

  rtems_unsigned8  temp8;

  rtems_unsigned16 temp16;

  rtems_unsigned32 level;

  rtems_isr        *ignored;

  Timer_MHZ = rtems_cpu_configuration_get_clicks_per_second() / 1000000 ;

  /*

   *  Timer has never overflowed.  This may not be necessary on some

   *  implemenations of timer but ....

   */

  Timer_interrupts /* .i */ = 0;

  _CPU_ISR_Disable( level);

  /*

   *  Somehow start the timer

   */

  /* stop Timer 1  */

  temp8 = read8( MTU_TSTR) & MTU1_STARTMASK;

  write8( temp8, MTU_TSTR);

  /* initialize counter 1 */

  write16( 0, MTU_TCNT1);

  /* Timer 1 is independent of other timers */

  temp8 = read8( MTU_TSYR) & MTU1_SYNCMASK;

  write8( temp8, MTU_TSYR);

  /* Timer 1, normal mode */

  temp8 = read8( MTU_TMDR1) & MTU1_MODEMASK;

  write8( temp8, MTU_TMDR1);

  /* x0000000

   * |||||+++--- Internal Clock

   * |||++------ Count on rising edge

   * |++-------- disable TCNT clear

   * +---------- don`t care

   */

  write8( MTU1_TCRMASK, MTU_TCR1);

  /* gra and grb are not used */

  write8( MTU1_TIORMASK, MTU_TIOR1);

  /* reset all status flags */

  temp8 = read8( MTU_TSR1) & MTU1_STAT_MASK;

  write8( temp8, MTU_TSR1);

  /* enable overflow interrupt */

  write8( MTU1_TIERMASK, MTU_TIER1);

  /* set interrupt priority */

  temp16 = read16( INTC_IPRC) & IPRC_MTU1_MASK;

  temp16 |= MTU1_PRIO;

  write16( temp16, INTC_IPRC);

  /* initialize ISR */

  _CPU_ISR_install_raw_handler( MTU1_VECTOR, timerisr, &ignored );

  _CPU_ISR_Enable( level);

  /* start timer 1 */

  temp8 = read8( MTU_TSTR) | ~MTU1_STARTMASK;

  write8( temp8, MTU_TSTR);

}

/*

 *  The following controls the behavior of Read_timer().

 *

 *  AVG_OVERHEAD is the overhead for starting and stopping the timer.  It

 *  is usually deducted from the number returned.

 *

 *  LEAST_VALID is the lowest number this routine should trust.  Numbers

 *  below this are "noise" and zero is returned.

 */

#define AVG_OVERHEAD      1  /* It typically takes X.X microseconds */

                             /* (Y countdowns) to start/stop the timer. */

                             /* This value is in microseconds. */

#define LEAST_VALID       0 /* 20 */ /* Don't trust a clicks value lower than this */

int Read_timer( void )

{

  rtems_unsigned32 clicks;

  rtems_unsigned32 total ;

  /*

   *  Read the timer and see how many clicks it has been since we started.

   */

  clicks = read16( MTU_TCNT1);   /* XXX: read some HW here */

  /*

   *  Total is calculated by taking into account the number of timer overflow

   *  interrupts since the timer was initialized and clicks since the last

   *  interrupts.

   */

  total = clicks + Timer_interrupts * 65536 ;

  if ( Timer_driver_Find_average_overhead )

    return total / SCALE;          /* in XXX microsecond units */

  else

  {

    if ( total < LEAST_VALID )

      return 0;            /* below timer resolution */

  /*

   *  Somehow convert total into microseconds

   */

    return (total / SCALE - AVG_OVERHEAD) ;

  }

}

/*

 *  Empty function call used in loops to measure basic cost of looping

 *  in Timing Test Suite.

 */

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;

}

/* Timer 1 is used */

#pragma interrupt

void timerisr( void )

{

  unsigned8 temp8;

  /* reset the flags of the status register */

  temp8 = read8( MTU_TSR1) & MTU1_STAT_MASK;

  write8( temp8, MTU_TSR1);

  Timer_interrupts += 1;

}