/* Timer_init()
*
* This routine initializes the timer on the FORCE CPU-386 board.
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* NOTE: This routine will not work if the optimizer is enabled
* for some compilers. The multiple writes to the Z8036
* may be optimized away.
*
* It is important that the timer start/stop overhead be
* determined when porting or modifying this code.
*
* 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 <rtems.h>
#include <bsp.h>
#include <stdlib.h>
volatile rtems_unsigned32 Ttimer_val; /* Updated from ISR!!! */
rtems_boolean Timer_driver_Find_average_overhead;
extern void timerisr();
/*
* Number of us per timer interrupt. Note: 1 us == 1 tick.
*/
#define US_PER_ISR 250
void TimerOn(const rtems_raw_irq_connect_data* used)
{
Ttimer_val = 0; /* clear timer ISR count */
/* Select timer, stay in mode 0 */
outport_byte (TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN);
/* Set to 250 usec interval */
outport_byte (TIMER_CNTR0, US_PER_ISR & 0xFF );
outport_byte (TIMER_CNTR0, (US_PER_ISR >> 8) & 0xFF );
/* Enable all timers */
outport_byte (TIMER_CONFIG, 0x00);
/*
* enable interrrupt at i8259 level
*/
BSP_irq_enable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
}
static int TimerIsOn (const rtems_raw_irq_connect_data *used)
{
return BSP_irq_enabled_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
}
void TimerOff(const rtems_raw_irq_connect_data* used)
{
/* Disable all timers */
outport_byte (TIMER_CONFIG, 0x80);
/*
* disable interrrupt at i8259 level
*/
BSP_irq_disable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
/* reset timer mode to standard (DOS) value */
}
static rtems_raw_irq_connect_data timer_raw_irq_data = {
BSP_PERIODIC_TIMER + BSP_IRQ_VECTOR_BASE,
timerisr,
TimerOn,
TimerOff,
TimerIsOn
};
static rtems_raw_irq_connect_data old_raw_irq_data = {
BSP_PERIODIC_TIMER + BSP_IRQ_VECTOR_BASE,
};
void Timer_exit()
{
if (!i386_delete_idt_entry(&timer_raw_irq_data)) {
printk("Timer_exit:Timer raw handler removal failed\n");
rtems_fatal_error_occurred(1);
}
}
void Timer_initialize(void)
{
static rtems_boolean First = TRUE;
if (First)
{
First = FALSE;
if (!i386_get_current_idt_entry (&old_raw_irq_data)) {
printk("Timer_initialize: failed to get old raw irq entry.\n");
rtems_fatal_error_occurred(1);
}
if (!i386_delete_idt_entry (&old_raw_irq_data)) {
printk("Timer_initialize: failed to delete old raw irq entry.\n");
rtems_fatal_error_occurred(1);
}
atexit(Timer_exit); /* Try not to hose the system at exit. */
if (!i386_set_idt_entry (&timer_raw_irq_data)) {
printk("Timer_initialize: raw handler installation failed.\n");
rtems_fatal_error_occurred(1);
}
}
/* wait for ISR to be called at least once */
Ttimer_val = 0;
while (Ttimer_val == 0)
continue;
Ttimer_val = 0;
}
#define AVG_OVERHEAD 3 /* It typically takes 3.0 microseconds */
/* (3 ticks) to start/stop the timer. */
#define LEAST_VALID 4 /* Don't trust a value lower than this */
int Read_timer(void)
{
register rtems_unsigned32 clicks, total;
register rtems_unsigned8 lsb, msb;
/* latch the count */
outport_byte (TIMER_MODE, TIMER_SEL0|TIMER_LATCH );
/* read the count */
inport_byte (TIMER_CNTR0, lsb );
inport_byte (TIMER_CNTR0, msb );
/*
* Timer ISR increments Ttimer_val every US_PER_ISR clock ticks,
* where 1 tick == 1 us. Below, 'click' is in microseconds.
*
* This assumes the timer input clocks are sourced from the system's
* prescaled clock (PSCLK), which is set to be at 1MHz.
*/
clicks = (msb << 8) | lsb;
total = Ttimer_val * US_PER_ISR + (US_PER_ISR - clicks);
if ( Timer_driver_Find_average_overhead == 1 )
return total; /* in one microsecond units */
else if ( total < LEAST_VALID )
return 0; /* below timer resolution */
else
return (total - AVG_OVERHEAD);
}
rtems_status_code Empty_function( void )
{
return RTEMS_SUCCESSFUL;
}
void Set_find_average_overhead(
rtems_boolean find_flag
)
{
Timer_driver_Find_average_overhead = find_flag;
}
/*
* Wait_X_ms: a delay loop used by the network driver...
*/
#define SLOW_DOWN_IO 0x80 /* I/O port which does nothing */
#define LOOP1MS 320 /* Just a guess.... */
void Wait_X_ms (unsigned timeToWait)
{
unsigned i, j;
for (j=0; j<timeToWait; j++)
for (i=0; i<LOOP1MS; i++)
outport_byte (SLOW_DOWN_IO, 0);
}
