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/* Clock_initialize
*
* This routine initializes the 8254 timer under GO32.
* The tick frequency is 1 millisecond.
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* $Id$
*/
#include <bsp.h>
#include <clockdrv.h>
#include <stdlib.h>
volatile rtems_unsigned32 Clock_driver_ticks;
rtems_unsigned32 Clock_isrs_per_tick; /* ISRs per tick */
rtems_unsigned32 Clock_isrs; /* ISRs until next tick */
rtems_isr_entry Old_ticker;
rtems_device_driver Clock_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *pargp,
rtems_id tid,
rtems_unsigned32 *rval
)
{
Install_clock( Clock_isr );
}
void ReInstall_clock(
rtems_isr_entry clock_isr
)
{
rtems_unsigned32 isrlevel = 0;
rtems_interrupt_disable( isrlevel );
(void) set_vector( clock_isr, 0x8, 1 );
rtems_interrupt_enable( isrlevel );
}
void Install_clock(
rtems_isr_entry clock_isr
)
{
unsigned int microseconds_per_isr;
#if 0
/* Initialize clock from on-board real time clock. This breaks the */
/* test code which assumes which assumes the application will do it. */
{
rtems_time_of_day Now;
extern void init_rtc( void );
extern long rtc_read( rtems_time_of_day * tod );
init_rtc();
if ( rtc_read( &Now ) >= 0 )
clock_set( &Now );
}
#endif
/* Start by assuming hardware counter is large enough, then */
/* scale it until it actually fits. */
Clock_driver_ticks = 0;
Clock_isrs_per_tick = 1;
if ( BSP_Configuration.microseconds_per_tick == 0 )
microseconds_per_isr = 10000; /* default 10 ms */
else
microseconds_per_isr = BSP_Configuration.microseconds_per_tick;
while ( US_TO_TICK(microseconds_per_isr) > 65535 ) {
Clock_isrs_per_tick *= 10;
microseconds_per_isr /= 10;
}
/* Initialize count in ckisr.c */
Clock_isrs = Clock_isrs_per_tick;
#if 0
/* This was dropped in the last revision. Its a nice thing to know. */
TICKS_PER_SECOND = 1000000 / (Clock_isrs_per_tick * microseconds_per_isr);
#endif
if ( BSP_Configuration.ticks_per_timeslice ) {
/* 105/88 approximates TIMER_TICK*1e-6 */
unsigned int count = US_TO_TICK( microseconds_per_isr );
Old_ticker = (rtems_isr_entry) set_vector( clock_isr, 0x8, 1 );
outport_byte( TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN );
outport_byte( TIMER_CNTR0, count >> 0 & 0xff );
outport_byte( TIMER_CNTR0, count >> 8 & 0xff );
}
atexit( Clock_exit );
}
void Clock_exit( void )
{
if ( BSP_Configuration.ticks_per_timeslice ) {
extern void rtc_set_dos_date( void );
/* reset to DOS value: */
outport_byte( TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN );
outport_byte( TIMER_CNTR0, 0 );
outport_byte( TIMER_CNTR0, 0 );
/* reset time-of-day */
rtc_set_dos_date();
/* re-enable old handler: assume it was one of ours */
set_vector( (rtems_isr_entry)Old_ticker, 0x8, 1 );
}
}
#if 0 && defined(pentium)
/* This can be used to get extremely accurate timing on a pentium. */
/* It isn't supported. [bryce] */
#define HZ 90.0
volatile long long Last_RDTSC;
#define RDTSC()\
({ long long _now; __asm __volatile (".byte 0x0F,0x31":"=A"(_now)); _now; })
long long Kernel_Time_ns( void )
{
extern rtems_unsigned32 _TOD_Ticks_per_second;
unsigned isrs_per_second = Clock_isrs_per_tick * _TOD_Ticks_per_second;
long long now;
int flags;
disable_intr( flags );
now = 1e9 * Clock_driver_ticks / isrs_per_second
+ (RDTSC() - Last_RDTSC) * (1000.0/HZ);
enable_intr( flags );
return now;
}
#endif
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