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/*
* This routine initializes the MC68340/349 Periodic Interval Timer
*/
/*
* Based on the `gen68360' board support package, and covered by the
* original distribution terms.
*
* Geoffroy Montel
* France Telecom - CNET/DSM/TAM/CAT
* 4, rue du Clos Courtel
* 35512 CESSON-SEVIGNE
* FRANCE
*
* e-mail: g_montel@yahoo.com
*/
/*
* COPYRIGHT (c) 1989-2014.
* 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 <stdlib.h> /* for atexit() */
#include <bsp.h>
#include <m68340.h>
#include <rtems/clockdrv.h>
#define CLOCK_VECTOR 120 /* clock isr routine vector in the vbr */
#define CLOCK_IRQ_LEVEL 6 /* clock isr level */
/*
* Clock_driver_ticks is a monotonically increasing counter of the
* number of clock ticks since the driver was initialized.
*/
volatile uint32_t Clock_driver_ticks;
/*
* Periodic interval timer interrupt handler
*/
static rtems_isr
Clock_isr (rtems_vector_number vector)
{
/*
* Announce the clock tick
*/
Clock_driver_ticks++;
rtems_clock_tick();
}
static void
Clock_exit (void)
{
/*
* Turn off periodic interval timer
*/
SIMPITR = 0;
}
static void
Install_clock (rtems_isr_entry clock_isr)
{
uint32_t pitr_tmp;
uint32_t usecs_per_tick;
Clock_driver_ticks = 0;
set_vector (clock_isr, CLOCK_VECTOR, 1);
/* sets the Periodic Interrupt Control Register PICR */
SIMPICR = ( CLOCK_IRQ_LEVEL << 8 ) | ( CLOCK_VECTOR );
/* sets the PITR count value */
/* this assumes a 32.765 kHz crystal */
usecs_per_tick = rtems_configuration_get_microseconds_per_tick();
/* find out whether prescaler should be enabled or not */
if ( usecs_per_tick <= 31128 ) {
pitr_tmp = ( usecs_per_tick * 8192 ) / 1000000 ;
} else {
pitr_tmp = ( usecs_per_tick / 1000000 ) * 16;
/* enable it */
pitr_tmp |= 0x100;
}
SIMPITR = (unsigned char) pitr_tmp;
atexit (Clock_exit);
}
void _Clock_Initialize( void )
{
Install_clock (Clock_isr);
}
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