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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libbsp/] [i386/] [ts_386ex/] [timer/] [timer.c] - Blame information for rev 593

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1 30 unneback
/*  Timer_init()
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 *
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 *  This routine initializes the timer on the FORCE CPU-386 board.
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 *
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 *  Input parameters:  NONE
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 *
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 *  Output parameters:  NONE
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 *
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 *  NOTE: This routine will not work if the optimizer is enabled
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 *        for some compilers.  The multiple writes to the Z8036
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 *        may be optimized away.
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 *
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 *        It is important that the timer start/stop overhead be
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 *        determined when porting or modifying this code.
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 *
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 *  COPYRIGHT (c) 1989-1999.
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 *  On-Line Applications Research Corporation (OAR).
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 *
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 *  The license and distribution terms for this file may be
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 *  found in the file LICENSE in this distribution or at
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 *  http://www.OARcorp.com/rtems/license.html.
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 *
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 *  $Id: timer.c,v 1.2 2001-09-27 11:59:50 chris Exp $
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 */
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#include <rtems.h>
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#include <bsp.h>
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#include <stdlib.h>
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volatile rtems_unsigned32  Ttimer_val;  /* Updated from ISR!!! */
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rtems_boolean Timer_driver_Find_average_overhead;
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extern void timerisr();
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/*
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 * Number of us per timer interrupt. Note: 1 us == 1 tick.
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 */
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#define  US_PER_ISR   250
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void TimerOn(const rtems_raw_irq_connect_data* used)
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{
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  Ttimer_val = 0;                           /* clear timer ISR count */
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  /* Select timer, stay in mode 0 */
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  outport_byte (TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN);
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  /* Set to 250 usec interval */
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  outport_byte (TIMER_CNTR0, US_PER_ISR & 0xFF );
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  outport_byte (TIMER_CNTR0, (US_PER_ISR >> 8) & 0xFF );
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  /* Enable all timers */
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  outport_byte (TIMER_CONFIG, 0x00);
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  /*
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   * enable interrrupt at i8259 level
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   */
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  BSP_irq_enable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
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}
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static int TimerIsOn (const rtems_raw_irq_connect_data *used)
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{
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  return BSP_irq_enabled_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
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}
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void TimerOff(const rtems_raw_irq_connect_data* used)
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{
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  /* Disable all timers */
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  outport_byte (TIMER_CONFIG, 0x80);
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  /*
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   * disable interrrupt at i8259 level
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   */
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  BSP_irq_disable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
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  /* reset timer mode to standard (DOS) value */
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}
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static rtems_raw_irq_connect_data timer_raw_irq_data = {
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  BSP_PERIODIC_TIMER + BSP_IRQ_VECTOR_BASE,
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  timerisr,
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  TimerOn,
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  TimerOff,
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  TimerIsOn
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};
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static rtems_raw_irq_connect_data old_raw_irq_data = {
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  BSP_PERIODIC_TIMER + BSP_IRQ_VECTOR_BASE,
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};
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void Timer_exit()
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{
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 if (!i386_delete_idt_entry(&timer_raw_irq_data)) {
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      printk("Timer_exit:Timer raw handler removal failed\n");
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      rtems_fatal_error_occurred(1);
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 }
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}
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void Timer_initialize(void)
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{
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  static rtems_boolean First = TRUE;
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  if (First)
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  {
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    First = FALSE;
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    if (!i386_get_current_idt_entry (&old_raw_irq_data)) {
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      printk("Timer_initialize: failed to get old raw irq entry.\n");
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      rtems_fatal_error_occurred(1);
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    }
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    if (!i386_delete_idt_entry (&old_raw_irq_data)) {
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      printk("Timer_initialize: failed to delete old raw irq entry.\n");
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      rtems_fatal_error_occurred(1);
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    }
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    atexit(Timer_exit); /* Try not to hose the system at exit. */
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    if (!i386_set_idt_entry (&timer_raw_irq_data)) {
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      printk("Timer_initialize: raw handler installation failed.\n");
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      rtems_fatal_error_occurred(1);
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    }
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  }
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  /* wait for ISR to be called at least once */
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  Ttimer_val = 0;
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  while (Ttimer_val == 0)
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    continue;
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  Ttimer_val = 0;
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}
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#define AVG_OVERHEAD      3  /* It typically takes 3.0 microseconds */
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                             /* (3 ticks) to start/stop the timer. */
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#define LEAST_VALID       4  /* Don't trust a value lower than this */
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int Read_timer(void)
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{
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  register rtems_unsigned32 clicks, total;
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  register rtems_unsigned8 lsb, msb;
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  /* latch the count */
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  outport_byte (TIMER_MODE, TIMER_SEL0|TIMER_LATCH );
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  /* read the count */
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  inport_byte (TIMER_CNTR0, lsb );
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  inport_byte (TIMER_CNTR0, msb );
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  /*
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   * Timer ISR increments Ttimer_val every US_PER_ISR clock ticks,
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   * where 1 tick == 1 us. Below, 'click' is in microseconds.
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   *
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   * This assumes the timer input clocks are sourced from the system's
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   * prescaled clock (PSCLK), which is set to be at 1MHz.
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   */
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  clicks = (msb << 8) | lsb;
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  total = Ttimer_val * US_PER_ISR + (US_PER_ISR - clicks);
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  if ( Timer_driver_Find_average_overhead == 1 )
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    return total;          /* in one microsecond units */
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  else if ( total < LEAST_VALID )
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    return 0;            /* below timer resolution */
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  else
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    return (total - AVG_OVERHEAD);
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}
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rtems_status_code Empty_function( void )
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{
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  return RTEMS_SUCCESSFUL;
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}
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void Set_find_average_overhead(
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  rtems_boolean find_flag
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)
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{
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  Timer_driver_Find_average_overhead = find_flag;
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}
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/*
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 *  Wait_X_ms: a delay loop used by the network driver...
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 */
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#define SLOW_DOWN_IO  0x80      /* I/O port which does nothing */
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#define LOOP1MS        320      /* Just a guess....  */
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void Wait_X_ms (unsigned timeToWait)
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{
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  unsigned i, j;
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  for (j=0; j<timeToWait; j++)
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    for (i=0; i<LOOP1MS; i++)
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      outport_byte (SLOW_DOWN_IO, 0);
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}

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