ckinit.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

/*  ckinit.c
 *
 *  This file provides a template for the clock device driver initialization.
 *
 *  COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  $Id: ckinit.c,v 1.4.6.1 2003/09/04 17:32:05 joel Exp $
 */

#ifndef lint
static char _sccsid[] = "@(#)ckinit.c 03/15/96     1.1\n";
#endif

#include <stdlib.h>

#include <rtems.h>
#include <rtems/libio.h>

#include "clock.h"

extern int CPU_CLOCK_RATE_MHZ; /* provided in bsp */

#define CLOCKS_PER_MICROSECOND ( CPU_CLOCK_RATE_MHZ ) /* equivalent to CPU clock speed in MHz */

void Clock_exit( void );
rtems_isr Clock_isr( rtems_vector_number vector );


/*
 *  The interrupt vector number associated with the clock tick device
 *  driver.
 */

#define CLOCK_VECTOR         14

/*
 *  Clock_driver_ticks is a monotonically increasing counter of the
 *  number of clock ticks since the driver was initialized.
 */

volatile rtems_unsigned32 Clock_driver_ticks;


/*
 * These are set by clock driver during its init
 */
 
rtems_device_major_number rtems_clock_major = ~0;
rtems_device_minor_number rtems_clock_minor;

/*
 *  The previous ISR on this clock tick interrupt vector.
 */

rtems_isr_entry  Old_ticker;

void Clock_exit( void );

static unsigned32 a29k_timer_rate = 0;

/*
 *  Isr Handler
 */

rtems_isr Clock_isr(
  rtems_vector_number vector
)
{
/*
 * bump the number of clock driver ticks since initialization
 *
 * determine if it is time to announce the passing of tick as configured
 * to RTEMS through the rtems_clock_tick directive
 *
 * perform any timer dependent tasks
 */

  a29k_clear_timer();

  Clock_driver_ticks += 1;

  rtems_clock_tick();
}

/* User callback shell (set from Clock_Control) */
static void (*user_callback)(void);

rtems_isr User_Clock_isr(
  rtems_vector_number vector
)
{
   /* refresh the internal CPU timer */
  a29k_clear_timer();

   if (user_callback)
      user_callback();
}

/*
 *  Install_clock
 *
 *  Install a clock tick handler and reprograms the chip.  This
 *  is used to initially establish the clock tick.
 */

void Install_clock(
  rtems_isr_entry clock_isr
)
{
  /*
   *  Initialize the clock tick device driver variables
   */

  Clock_driver_ticks = 0;

  /*
   *  If ticks_per_timeslice is configured as non-zero, then the user
   *  wants a clock tick.
   */

  if ( rtems_configuration_get_ticks_per_timeslice() ) {
    Old_ticker = (rtems_isr_entry) set_vector( clock_isr, CLOCK_VECTOR, 1 );
    /*
     *  Hardware specific initialize goes here
     */

    a29k_timer_rate = rtems_configuration_get_microseconds_per_tick() * CLOCKS_PER_MICROSECOND;
    a29k_init_timer( a29k_timer_rate );
  }

  /*
   *  Schedule the clock cleanup routine to execute if the application exits.
   */

  atexit( Clock_exit );
}

/*
 *  Clean up before the application exits
 */

void Clock_exit( void )
{
  if ( rtems_configuration_get_ticks_per_timeslice() ) {

    /* a29k: turn off the timer interrupts */
    a29k_disable_timer();

  }
}

/*
 *  Clock_initialize
 *
 *  Device driver entry point for clock tick driver initialization.
 */

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;
}

rtems_device_driver Clock_control(
  rtems_device_major_number major,
  rtems_device_minor_number minor,
  void *pargp
)
{
    rtems_unsigned32 isrlevel;
    rtems_libio_ioctl_args_t *args = pargp;
 
    if (args == 0)
        goto done;
 
    /*
     * This is hokey, but until we get a defined interface
     * to do this, it will just be this simple...
     */
 
    if (args->command == rtems_build_name('I', 'S', 'R', ' '))
    {
        Clock_isr(CLOCK_VECTOR);
    }
    else if (args->command == rtems_build_name('N', 'E', 'W', ' '))
    {
      rtems_interrupt_disable( isrlevel );
      user_callback = (void (*)(void))args->buffer;
      (void) set_vector( User_Clock_isr, CLOCK_VECTOR, 1 );
      rtems_interrupt_enable( isrlevel );
    }
 
done:
    return RTEMS_SUCCESSFUL;
}