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/*
* Timer Init
*
* This module initializes TIMER 2 for on the MCF5272 for benchmarks.
*
* Copyright (C) 2000 OKTET Ltd., St.-Petersburg, Russia
* Author: Victor V. Vengerov <vvv@oktet.ru>
*
* Based on work:
* Author:
* David Fiddes, D.J@fiddes.surfaid.org
* http://www.calm.hw.ac.uk/davidf/coldfire/
*
* COPYRIGHT (c) 1989-1998.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
#include <rtems.h>
#include <bsp.h>
#include <mcf5272/mcf5272.h>
#define TRR2_VAL 65530
uint32_t Timer_interrupts;
bool benchmark_timer_find_average_overhead;
/* External assembler interrupt handler routine */
extern rtems_isr timerisr(rtems_vector_number vector);
/* benchmark_timer_initialize --
* Initialize timer 2 for accurate time measurement.
*
* PARAMETERS:
* none
*
* RETURNS:
* none
*/
void
benchmark_timer_initialize(void)
{
uint32_t icr;
/* Catch timer2 interrupts */
set_vector(timerisr, BSP_INTVEC_TMR2, 0);
/* Reset Timer */
g_timer_regs->tmr2 = MCF5272_TMR_RST;
g_timer_regs->tmr2 = MCF5272_TMR_CLK_STOP;
g_timer_regs->tmr2 = MCF5272_TMR_RST;
g_timer_regs->tcn2 = 0; /* reset counter */
Timer_interrupts = 0; /* Clear timer ISR counter */
g_timer_regs->ter2 = MCF5272_TER_REF | MCF5272_TER_CAP;
g_timer_regs->trr2 = TRR2_VAL -1 ;
/* Set Timer 2 prescaler so that it counts in microseconds */
g_timer_regs->tmr2 = (
(((BSP_SYSTEM_FREQUENCY / 1000000) - 1) << MCF5272_TMR_PS_SHIFT) |
MCF5272_TMR_CE_DISABLE |
MCF5272_TMR_ORI |
MCF5272_TMR_FRR |
MCF5272_TMR_CLK_MSTR |
MCF5272_TMR_RST);
/* Initialize interrupts for timer2 */
icr = g_intctrl_regs->icr1;
icr = icr & ~(MCF5272_ICR1_TMR2_MASK | MCF5272_ICR1_TMR2_PI);
icr |= (MCF5272_ICR1_TMR2_IPL(BSP_INTLVL_TMR2) | MCF5272_ICR1_TMR2_PI);
g_intctrl_regs->icr1 = icr;
}
/*
* The following controls the behavior of benchmark_timer_read().
*
* FIND_AVG_OVERHEAD * instructs the routine to return the "raw" count.
*
* AVG_OVEREHAD 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 0 /* It typically takes 2.0 microseconds */
/* (Y countdowns) to start/stop the timer. */
/* This value is in microseconds. */
#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */
/* benchmark_timer_read --
* Read timer value in microsecond units since timer start.
*
* PARAMETERS:
* none
*
* RETURNS:
* number of microseconds since timer has been started
*/
int
benchmark_timer_read( void )
{
uint16_t clicks;
uint32_t total;
/*
* Read the timer and see how many clicks it has been since counter
* rolled over.
*/
clicks = g_timer_regs->tcn2;
/* Stop Timer... */
g_timer_regs->tmr2 = MCF5272_TMR_CLK_STOP | MCF5272_TMR_RST;
/*
* 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 = (Timer_interrupts * TRR2_VAL) + clicks;
if ( benchmark_timer_find_average_overhead == 1 )
return total; /* in XXX microsecond units */
if ( total < LEAST_VALID )
return 0; /* below timer resolution */
/*
* Return the count in microseconds
*/
return (total - AVG_OVERHEAD);
}
/* benchmark_timer_disable_subtracting_average_overhead --
* This routine is invoked by the "Check Timer" (tmck) test in the
* RTEMS Timing Test Suite. It makes the benchmark_timer_read routine not
* subtract the overhead required to initialize and read the benchmark
* timer.
*
* PARAMETERS:
* find_flag - bool flag, true if overhead must not be subtracted.
*
* RETURNS:
* none
*/
void
benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
{
benchmark_timer_find_average_overhead = find_flag;
}
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