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/* timer.c
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*
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* NOTE: These routines will not work if the optimizer is enabled
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* for some compilers. The multiple writes to the Z8036
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* may be optimized away.
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*
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* It is important that the timer start/stop overhead be
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* determined when porting or modifying this code.
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*
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* COPYRIGHT (c) 1989-1999.
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* On-Line Applications Research Corporation (OAR).
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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* http://www.OARcorp.com/rtems/license.html.
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*
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* $Id: timer.c,v 1.2 2001-09-27 12:00:01 chris Exp $
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*/
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#include <rtems.h>
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#include <bsp.h>
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int Ttimer_val;
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rtems_boolean Timer_driver_Find_average_overhead;
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rtems_isr timerisr();
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void Timer_initialize()
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{
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rtems_unsigned8 data;
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(void) set_vector( timerisr, TIMER_VECTOR, 0 ); /* install ISR */
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Ttimer_val = 0; /* clear timer ISR count */
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Z8x36_READ ( TIMER, MASTER_INTR, data );
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Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0x01) );
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Z8x36_WRITE( TIMER, MASTER_CFG, 0xd4 );
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Z8x36_READ ( TIMER, MASTER_INTR, data );
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Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0x7E) );
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Z8x36_WRITE( TIMER, CT1_TIME_CONST_MSB, 0x00 );
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Z8x36_WRITE( TIMER, CT1_TIME_CONST_LSB, 0x00 );
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Z8x36_WRITE( TIMER, CT1_MODE_SPEC, 0x87 );
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Z8x36_WRITE( TIMER, CNT_TMR_VECTOR, TIMER_VECTOR );
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Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0x20 );
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Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0x26 );
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Z8x36_READ ( TIMER, MASTER_INTR, data );
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Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0xDA) | 0x80 );
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Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0xC6 );
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/*
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* ACC_IC54 - interrupt 5 will be vectored and mapped to level 6
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*/
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data = (*(rtems_unsigned8 *)0x0D00000B);
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(*(rtems_unsigned8 *)0x0D00000B) = (data & 0x0F) | 0x60;
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}
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#define AVG_OVERHEAD 9 /* It typically takes 3.65 microseconds */
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/* (9 countdowns) to start/stop the timer. */
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#define LEAST_VALID 10 /* Don't trust a value lower than this */
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int Read_timer()
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{
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rtems_unsigned8 data;
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rtems_unsigned8 msb, lsb;
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rtems_unsigned32 remaining, total;
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Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0xce ); /* read the counter value */
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Z8x36_READ( TIMER, CT1_CUR_CNT_MSB, msb );
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Z8x36_READ( TIMER, CT1_CUR_CNT_LSB, lsb );
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remaining = 0x10000 - ((msb << 8) + lsb);
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total = (Ttimer_val * 0x10000) + remaining;
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Z8x36_READ ( TIMER, MASTER_INTR, data );
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Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0x01) );
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/* do not restore old vector */
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if ( Timer_driver_Find_average_overhead == 1 )
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return total; /* in countdown units */
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if ( total < LEAST_VALID )
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return 0; /* below timer resolution */
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/* Clocked at 2.4615 Mhz */
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return (int)(((float)(total-AVG_OVERHEAD)) / 2.4615 * 2.0);
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}
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rtems_status_code Empty_function( void )
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{
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return RTEMS_SUCCESSFUL;
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}
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void Set_find_average_overhead(
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rtems_boolean find_flag
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)
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{
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Timer_driver_Find_average_overhead = find_flag;
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}
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