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/* Clock_init()
*
* This routine initailizes the periodic interrupt timer on
* the Motorola 68332.
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* COPYRIGHT (c) 1989-1999.
* 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 <stdlib.h>
#include <bsp.h>
#include <mrm332.h>
#define CLOCK_VECTOR MRM_PIV
uint32_t Clock_isrs; /* ISRs until next tick */
volatile uint32_t Clock_driver_ticks;
/* ticks since initialization */
rtems_isr_entry Old_ticker;
void Clock_exit( void );
/*
* These are set by clock driver during its init
*/
rtems_device_major_number rtems_clock_major = ~0;
rtems_device_minor_number rtems_clock_minor;
rtems_isr Clock_isr(rtems_vector_number vector)
{
Clock_driver_ticks += 1;
if ( Clock_isrs == 1 ) {
rtems_clock_tick();
Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000;
}
else
Clock_isrs -= 1;
}
void Install_clock(
rtems_isr_entry clock_isr
)
{
Clock_driver_ticks = 0;
Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000;
Old_ticker = (rtems_isr_entry) set_vector( clock_isr, CLOCK_VECTOR, 1 );
/* enable 1mS interrupts */
*PITR = (unsigned short int)( SAM(0x09,0,PITM) );/* load counter */
*PICR = (unsigned short int) /* enable interrupt */
( SAM(ISRL_PIT,8,PIRQL) | SAM(CLOCK_VECTOR,0,PIV) );
atexit( Clock_exit );
}
void Clock_exit( void )
{
/* shutdown the periodic interrupt */
*PICR = (unsigned short int)
( SAM(0,8,PIRQL) | SAM(CLOCK_VECTOR,0,PIV) );
/* ^^ zero disables interrupt */
/* do not restore old vector */
}
rtems_device_driver Clock_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *pargp
)
{
Install_clock( Clock_isr );
/*
* make major/minor avail to others such as shared memory driver
*/
rtems_clock_major = major;
rtems_clock_minor = minor;
return RTEMS_SUCCESSFUL;
}
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