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/*
* This routine initializes Timer 1 for an MC68302.
* The tick frequency is 1 millisecond.
*/
/*
* 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 <rtems/m68k/m68302.h>
#define CLOCK_VECTOR 137
#define TMR1_VAL ( RBIT_TMR_RST /* software reset the timer */\
| RBIT_TMR_ICLK_MASTER16 /* master clock divided by 16 */\
| RBIT_TMR_FRR /* restart timer after ref reached */\
| RBIT_TMR_ORI) /* enable interrupt when ref reached */
#define TRR1_VAL 1000 /* 1000 ticks @ 16MHz/16
* = 1 millisecond tick.
*/
/*
* 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;
/*
* Clock_isrs is the number of clock ISRs until the next invocation of
* the RTEMS clock tick routine. The clock tick device driver
* gets an interrupt once a millisecond and counts down until the
* length of time between the user configured microseconds per tick
* has passed.
*/
uint32_t Clock_isrs;
void Clock_exit( void );
/*
* ISR Handler
*/
static rtems_isr Clock_isr(
rtems_vector_number vector
)
{
Clock_driver_ticks += 1;
m302.reg.isr = RBIT_ISR_TIMER1; /* clear in-service bit */
m302.reg.ter1 = (RBIT_TER_REF | RBIT_TER_CAP); /* clear timer intr request */
if ( Clock_isrs == 1 ) {
rtems_clock_tick();
Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000;
}
else
Clock_isrs -= 1;
}
static void Install_clock(
rtems_isr_entry clock_isr
)
{
Clock_driver_ticks = 0;
Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000;
set_vector( clock_isr, CLOCK_VECTOR, 1 );
m302.reg.trr1 = TRR1_VAL; /* set timer reference register */
m302.reg.tmr1 = TMR1_VAL; /* set timer mode register & enable */
/*
* Enable TIMER1 interrupts only.
*/
m302.reg.imr |= RBIT_IMR_TIMER1; /* set 68302 int-mask to allow ints */
atexit( Clock_exit );
}
void Clock_exit( void )
{
/* TODO: figure out what to do here */
/* 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 );
return RTEMS_SUCCESSFUL;
}
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