/* Clock_init()
*
*
* 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.
*
* 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.OARcorp.com/rtems/license.html.
*
* $Id$
*/
#include <stdlib.h>
#include <bsp.h>
#include <rtems/libio.h>
rtems_unsigned32 Clock_isrs; /* ISRs until next tick */
volatile rtems_unsigned32 Clock_driver_ticks;
/* ticks since initialization */
rtems_isr_entry Old_ticker;
extern rtems_configuration_table Configuration;
extern void led_putnum();
void Disable_clock();
#define CLOCK_VECTOR 0x4D
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;
/*
* 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
*/
rtems_isr Clock_isr(
rtems_vector_number vector
)
{
Clock_driver_ticks += 1;
/* acknowledge interrupt
TSR = 1; */
MC68230_WRITE (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)(BSP_Configuration.microseconds_per_tick / 1000);
}
else
Clock_isrs -= 1;
}
void Disable_clock()
{
/* Disable timer */
MC68230_WRITE (TCR, 0x00);
}
void Install_clock( clock_isr )
rtems_isr_entry clock_isr;
{
Clock_driver_ticks = 0;
Clock_isrs = (int)(Configuration.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 (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:
TIVR = CLOCK_VECTOR; */
MC68230_WRITE (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 (CPRH, 0x00);
MC68230_WRITE (CPRM, 0x00);
MC68230_WRITE (CPRL, 0xC1);
/* Enable timer and use it as an external periodic interrupt generator
TCR = 0xA1; */
/* led_putnum('a'); * for debugging purposes */
MC68230_WRITE (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 )
{
rtems_unsigned8 data;
/* disable timer
data = TCR;
TCR = (data & 0xFE); */
MC68230_READ (TCR, data);
MC68230_WRITE (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 );
/*
* make major/minor avail to others such as shared memory driver
*/
rtems_clock_major = major;
rtems_clock_minor = minor;
return RTEMS_SUCCESSFUL;
}
rtems_device_driver Clock_control(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *pargp
)
{
rtems_unsigned32 isrlevel;
rtems_libio_ioctl_args_t *args = pargp;
if (args == 0)
goto done;
/*
* This is hokey, but until we get a defined interface
* to do this, it will just be this simple...
*/
if (args->command == rtems_build_name('I', 'S', 'R', ' '))
{
Clock_isr(CLOCK_VECTOR);
}
else if (args->command == rtems_build_name('N', 'E', 'W', ' '))
{
rtems_interrupt_disable( isrlevel );
(void) set_vector( args->buffer, CLOCK_VECTOR, 1 );
rtems_interrupt_enable( isrlevel );
}
done:
return RTEMS_SUCCESSFUL;
}
