Subversion Repositories openrisc_2011-10-31

/*  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: timer.c,v 1.2 2001-09-27 11:59:50 chris Exp $

 */

#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);

}