source: rtems/c/src/lib/libbsp/i386/i386ex/clock/ckinit.c @ 2d6932a

/*  Clock_initialize
 *
 *  This routine initializes the Timer/Counter on the Intel
 *  386ex evaluation board.
 *
 *  The tick frequency is 1 millisecond.
 *
 *  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.rtems.com/license/LICENSE.
 *
 *  $Id$
 */
#define TMR0      0xF040
#define TMR1      0xF041
#define TMR2      0xF042
#define TMRCON    0xF043
#define TMRCFG    0xF834

#include <bsp.h>
#include <bsp/irq.h>

#include <stdlib.h>

uint32_t         Clock_isrs;              /* ISRs until next tick */
static uint32_t         Clock_initial_isr_value;

volatile uint32_t         Clock_driver_ticks;

void Clock_exit( void );

/*
 * These are set by clock driver during its init
 */

rtems_device_major_number rtems_clock_major = ~0;
rtems_device_major_number rtems_clock_minor = 0;

/*
 *  This is the ISR handler.
 */

void Clock_isr()
{
  /* enable_tracing(); */
  Clock_driver_ticks += 1;
  if ( Clock_isrs == 1 ) {
    rtems_clock_tick();
    Clock_isrs = Clock_initial_isr_value; /* rtems_configuration_get_microseconds_per_tick() / 1000;*/
  }
  else
    Clock_isrs -= 1;
}

void ClockOff(const rtems_irq_connect_data* unused)
{
  outport_byte  ( TMRCFG , 0x80 ); /* disable the counter timer */
}

void ClockOn(const rtems_irq_connect_data* unused)
{
  outport_byte    ( TMRCFG , 0x00 ); /* enable the counter timer */
}

int ClockIsOn(const rtems_irq_connect_data* unused)
{
  return ((i8259s_cache & 0x1) == 0);
}

static rtems_irq_connect_data clockIrqData = {BSP_PERIODIC_TIMER,
                                              Clock_isr,
                                              0,
                                              ClockOn,
                                              ClockOff,
                                              ClockIsOn};

rtems_device_driver Clock_initialize(
  rtems_device_major_number major,
  rtems_device_minor_number minor,
  void *pargp
)
{
  unsigned timer_counter_init_value;
  unsigned char clock_lsb, clock_msb;

  Clock_driver_ticks = 0;

  Clock_isrs =
    Clock_initial_isr_value =
    rtems_configuration_get_microseconds_per_tick() / 1000; /* ticks per clock_isr */

  /*
   * configure the counter timer ( should be based on microsecs/tick )
   * NB. The divisor(Clock_isrs) resolves the  is the same number that appears in confdefs.h
   * when setting the microseconds_per_tick value.
   */
  ClockOff      ( &clockIrqData );

  timer_counter_init_value  =  rtems_configuration_get_microseconds_per_tick() / Clock_isrs;
  clock_lsb = (unsigned char)timer_counter_init_value;
  clock_msb = timer_counter_init_value >> 8;

  outport_byte  ( TMRCON , 0x34 );
  outport_byte  ( TMR0   , clock_lsb );       /* load LSB first */
  outport_byte  ( TMR0   , clock_msb );  /* then MSB       */

  if (!BSP_install_rtems_irq_handler (&clockIrqData)) {
    printk("Unable to initialize system clock\n");
    rtems_fatal_error_occurred(1);
  }

  /*
   * make major/minor avail to others such as shared memory driver
   */

  rtems_clock_major = major;
  rtems_clock_minor = minor;

  return RTEMS_SUCCESSFUL;
}

void Clock_exit()
{
  ClockOff(&clockIrqData);
  BSP_remove_rtems_irq_handler (&clockIrqData);
}