source: rtems/c/src/lib/libbsp/m68k/mvme136/clock/ckinit.c @ 34ef6c7

/*  Clock_init()
 *
 *  This routine initializes the Z80386 1 on the MVME136 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.
 *
 *  $Id$
 */

#include <stdlib.h>

#include <bsp.h>
#include <rtems/libio.h>
#include <rtems/zilog/z8036.h>

#define MICRVAL     0xe2            /* disable lower chain, no vec */
                                    /*  set right justified addr */
                                    /*  and master int enable */
#define MCCRVAL     0xc4            /* enable T1 and port B */
                                    /*   timers independent */
#define MS_COUNT    0x07d0          /* T1's countdown constant (1 ms) */
#define T1MSRVAL    0x80            /* T1 cont. cycle/pulse output */
#define T1CSRVAL    0xc6            /* enable interrupt, allow and */
                                    /*   and trigger countdown */

#define TIMER        0xfffb0000
#define RELOAD       0x24            /* clr IP & IUS,allow countdown */

#define CLOCK_VECTOR 66

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 );

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

rtems_device_major_number rtems_clock_major = ~0;
rtems_device_minor_number rtems_clock_minor;

/*
 *  ISR Handler
 */

rtems_isr Clock_isr(
  rtems_vector_number vector
)
{
  Clock_driver_ticks += 1;
  ((volatile struct z8036_map *) TIMER)->CT1_CMD_STATUS = RELOAD;

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

void Install_clock(
  rtems_isr_entry clock_isr
)
{
  volatile struct z8036_map *timer;

  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 );
  timer = (struct z8036_map *) 0xfffb0000;
  timer->MASTER_INTR        = MICRVAL;
  timer->CT1_MODE_SPEC      = T1MSRVAL;

  *((uint16_t*)0xfffb0016) = MS_COUNT;  /* write countdown value */

  /*
   *  timer->CT1_TIME_CONST_MSB = (MS_COUNT >> 8);
   *  timer->CT1_TIME_CONST_LSB = (MS_COUNT &  0xff);
   */

  timer->MASTER_CFG         = MCCRVAL;
  timer->CT1_CMD_STATUS     = T1CSRVAL;

  /*
   * Enable interrupt via VME interrupt mask register
   */
  (*(uint8_t*)0xfffb0038) &= 0xfd;

  atexit( Clock_exit );
}

void Clock_exit( void )
{
  volatile struct z8036_map *timer;

  timer = (struct z8036_map *) 0xfffb0000;
  timer->MASTER_INTR        = 0x62;
  timer->CT1_MODE_SPEC      = 0x00;
  timer->MASTER_CFG         = 0xf4;
  timer->CT1_CMD_STATUS     = 0x00;
  /* do not restore old vector */
}

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

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

  rtems_clock_major = major;
  rtems_clock_minor = minor;

  return RTEMS_SUCCESSFUL;
}