/*
* 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
* benchmark_timer_initialize() and benchmark_timer_read(). benchmark_timer_read() usually returns
* the number of microseconds since benchmark_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).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#include <rtems.h>
#include <rtems/score/sh_io.h>
#include <rtems/score/iosh7045.h>
extern uint32_t bsp_clicks_per_second;
/*
* 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
extern rtems_isr timerisr(void);
static uint32_t Timer_interrupts;
bool benchmark_timer_find_average_overhead;
static uint32_t Timer_MHZ ;
void benchmark_timer_initialize( void )
{
uint8_t temp8;
uint16_t temp16;
rtems_interrupt_level level;
rtems_isr *ignored;
Timer_MHZ = bsp_clicks_per_second / 1000000 ;
/*
* Timer has never overflowed. This may not be necessary on some
* implemenations of timer but ....
*/
Timer_interrupts /* .i */ = 0;
rtems_interrupt_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 );
rtems_interrupt_enable( level );
/* start timer 1 */
temp8 = read8(MTU_TSTR) | ~MTU1_STARTMASK;
write8( temp8, MTU_TSTR );
}
/*
* The following controls the behavior of benchmark_timer_read().
*
* 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 benchmark_timer_read( void )
{
uint32_t clicks;
uint32_t 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 ( benchmark_timer_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) ;
}
}
void benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
{
benchmark_timer_find_average_overhead = find_flag;
}
/* Timer 1 is used */
#pragma interrupt
void timerisr( void )
{
uint8_t temp8;
/* reset the flags of the status register */
temp8 = read8(MTU_TSR1) & MTU1_STAT_MASK;
write8( temp8, MTU_TSR1 );
Timer_interrupts += 1;
}
