/*
* This is modified by Doug McBride to get it to work for the MC68EC040
* IDP board. The below comments are kept to show that some prior work
* was done in the area and the modifications performed was application
* specific for the IDP board to port it to.
*
* This routine initializes the mc68230 on the MC68EC040 board.
* The tick frequency is 40 milliseconds.
*/
/*
* 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.org/license/LICENSE.
*/
#include <stdlib.h>
#include <bsp.h>
uint32_t Clock_isrs; /* ISRs until next tick */
volatile uint32_t Clock_driver_ticks;
/* ticks since initialization */
rtems_isr_entry Old_ticker;
extern void led_putnum(void);
void Disable_clock(void);
#define CLOCK_VECTOR 0x4D
void Clock_exit( void );
/*
* ISR Handler
*
*
* ((1ms * 6.5 MHz) / 2^5) = 203.125) where 6.5 MHz is the clock rate of the
* MC68230, 2^5 is the prescaler factor, and 1ms is the common interrupt
* interval for the Clock_isr routine.
*
* Therefore, 203 (decimal) is the number to program into the CPRH-L registers
* of the MC68230 for countdown. However, I have found that 193 instead of
* 203 provides greater accuracy -- why? The crystal should be more accurate
* than that
*/
static rtems_isr Clock_isr(
rtems_vector_number vector
)
{
Clock_driver_ticks += 1;
/* acknowledge interrupt
MC68230_TSR = 1; */
MC68230_WRITE (MC68230_TSR, 1);
if ( Clock_isrs == 1 ) {
rtems_clock_tick();
/* Cast to an integer so that 68EC040 IDP which doesn't have an FPU doesn't
have a heart attack -- if you use newlib1.6 or greater and get
libgcc.a for gcc with software floating point support, this is not
a problem */
Clock_isrs =
(int)(rtems_configuration_get_microseconds_per_tick() / 1000);
}
else
Clock_isrs -= 1;
}
void Disable_clock(void)
{
/* Disable timer */
MC68230_WRITE (MC68230_TCR, 0x00);
}
static void Install_clock(
rtems_isr_entry clock_isr )
{
Clock_driver_ticks = 0;
Clock_isrs = (int)(rtems_configuration_get_microseconds_per_tick() / 1000);
/* led_putnum('c'); * for debugging purposes */
Old_ticker = (rtems_isr_entry) set_vector( clock_isr, CLOCK_VECTOR, 1 );
/* Disable timer for initialization */
MC68230_WRITE (MC68230_TCR, 0x00);
/* some PI/T initialization stuff here -- see comment in the ckisr.c
file in this directory to understand why I use the values that I do */
/* Set up the interrupt vector on the MC68230 chip:
MC68230_TIVR = CLOCK_VECTOR; */
MC68230_WRITE (MC68230_TIVR, CLOCK_VECTOR);
/* Set CPRH through CPRL to 193 (not 203) decimal for countdown--see ckisr.c
CPRH = 0x00;
CPRM = 0x00;
CPRL = 0xC1; */
MC68230_WRITE (MC68230_CPRH, 0x00);
MC68230_WRITE (MC68230_CPRM, 0x00);
MC68230_WRITE (MC68230_CPRL, 0xC1);
/* Enable timer and use it as an external periodic interrupt generator
MC68230_TCR = 0xA1; */
/* led_putnum('a'); * for debugging purposes */
MC68230_WRITE (MC68230_TCR, 0xA1);
/*
* Schedule the clock cleanup routine to execute if the application exits.
*/
atexit( Clock_exit );
}
/* The following was added for debugging purposes */
void Clock_exit( void )
{
uint8_t data;
/* disable timer
data = TCR;
TCR = (data & 0xFE); */
MC68230_READ (MC68230_TCR, data);
MC68230_WRITE (MC68230_TCR, (data & 0xFE));
/* 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;
}
