source: rtems/bsps/m68k/mvme162/clock/ckinit.c @ d7d66d7

/*
 *  This routine initializes the Tick Timer 2 on the MVME162 board.
 *  The tick frequency is 1 millisecond.
 */

/*
 *  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.org/license/LICENSE.
 *
 *  Modifications of respective RTEMS file: COPYRIGHT (c) 1994.
 *  EISCAT Scientific Association. M.Savitski
 *
 *  This material is a part of the MVME162 Board Support Package
 *  for the RTEMS executive. Its licensing policies are those of the
 *  RTEMS above.
 */

#include <stdlib.h>

#include <bsp.h>
#include <rtems/clockdrv.h>

#define MS_COUNT          1000            /* T2's countdown constant (1 ms) */
#define CLOCK_INT_LEVEL   6               /* T2's interrupt level */

uint32_t         Clock_isrs;                  /* ISRs until next tick */
volatile uint32_t         Clock_driver_ticks; /* ticks since initialization */
rtems_isr_entry  Old_ticker;

void Clock_exit( void );

#define CLOCK_VECTOR (VBR0 * 0x10 + 0x9)

/*
 *  ISR Handler
 */
static rtems_isr Clock_isr(rtems_vector_number vector)
{
  Clock_driver_ticks += 1;
  lcsr->timer_cnt_2 = 0;            /* clear counter */
  lcsr->intr_clear |= 0x02000000;

  if ( Clock_isrs == 1 ) {
    rtems_clock_tick();
    Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000;
  }
  else
    Clock_isrs -= 1;
}

static void Install_clock(rtems_isr_entry clock_isr )
{

  Clock_driver_ticks = 0;
  Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000;

  Old_ticker = (rtems_isr_entry) set_vector( clock_isr, CLOCK_VECTOR, 1 );
  lcsr->vector_base |= MASK_INT;   /* unmask VMEchip2 interrupts */
  lcsr->to_ctl = 0xE7;             /* prescaler to 1 MHz (see Appendix A1) */
  lcsr->timer_cmp_2 = MS_COUNT;
  lcsr->timer_cnt_2 = 0;           /* clear counter */
  lcsr->board_ctl |= 0x700;        /* increment, reset-on-compare, and */
                                   /*   clear-overflow-cnt */

  lcsr->intr_level[0] |= CLOCK_INT_LEVEL * 0x10;      /* set int level */
  lcsr->intr_ena |= 0x02000000;       /* enable tick timer 2 interrupt */

  atexit( Clock_exit );
}

void Clock_exit( void )
{
/* Dummy for now. See other m68k BSP's for code examples */
}

rtems_device_driver Clock_initialize(
  rtems_device_major_number major,
  rtems_device_minor_number minor,
  void *pargp
)
{
  Install_clock( Clock_isr );

  return RTEMS_SUCCESSFUL;
}