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/* timer.c
*
* NOTE: These routines will not work if the optimizer is enabled
* for some compilers. The multiple writes to the Z8036
* may be optimized away.
*
* It is important that the timer start/stop overhead be
* determined when porting or modifying this code.
*
* COPYRIGHT (c) 1989-1997.
* On-Line Applications Research Corporation (OAR).
* Copyright assigned to U.S. Government, 1994.
*
* The license and distribution terms for this file may in
* the file LICENSE in this distribution or at
* http://www.OARcorp.com/rtems/license.html.
*
* $Id$
*/
#include <rtems.h>
#include <bsp.h>
int Ttimer_val;
rtems_boolean Timer_driver_Find_average_overhead;
rtems_isr timerisr();
void Timer_initialize()
{
rtems_unsigned8 data;
(void) set_vector( timerisr, TIMER_VECTOR, 0 ); /* install ISR */
Ttimer_val = 0; /* clear timer ISR count */
Z8x36_READ ( TIMER, MASTER_INTR, data );
Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0x01) );
Z8x36_WRITE( TIMER, MASTER_CFG, 0xd4 );
Z8x36_READ ( TIMER, MASTER_INTR, data );
Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0x7E) );
Z8x36_WRITE( TIMER, CT1_TIME_CONST_MSB, 0x00 );
Z8x36_WRITE( TIMER, CT1_TIME_CONST_LSB, 0x00 );
Z8x36_WRITE( TIMER, CT1_MODE_SPEC, 0x87 );
Z8x36_WRITE( TIMER, CNT_TMR_VECTOR, TIMER_VECTOR );
Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0x20 );
Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0x26 );
Z8x36_READ ( TIMER, MASTER_INTR, data );
Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0xDA) | 0x80 );
Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0xC6 );
/*
* ACC_IC54 - interrupt 5 will be vectored and mapped to level 6
*/
data = (*(rtems_unsigned8 *)0x0D00000B);
(*(rtems_unsigned8 *)0x0D00000B) = (data & 0x0F) | 0x60;
}
#define AVG_OVERHEAD 9 /* It typically takes 3.65 microseconds */
/* (9 countdowns) to start/stop the timer. */
#define LEAST_VALID 10 /* Don't trust a value lower than this */
int Read_timer()
{
rtems_unsigned8 data;
rtems_unsigned8 msb, lsb;
rtems_unsigned32 remaining, total;
Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0xce ); /* read the counter value */
Z8x36_READ( TIMER, CT1_CUR_CNT_MSB, msb );
Z8x36_READ( TIMER, CT1_CUR_CNT_LSB, lsb );
remaining = 0x10000 - ((msb << 8) + lsb);
total = (Ttimer_val * 0x10000) + remaining;
Z8x36_READ ( TIMER, MASTER_INTR, data );
Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0x01) );
/* do not restore old vector */
if ( Timer_driver_Find_average_overhead == 1 )
return total; /* in countdown units */
if ( total < LEAST_VALID )
return 0; /* below timer resolution */
/* Clocked at 2.4615 Mhz */
return (int)(((float)(total-AVG_OVERHEAD)) / 2.4615 * 2.0);
}
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;
}
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