source: rtems/bsps/no_cpu/no_bsp/clock/ckinit.c @ cc466a5

/*
 *  This file provides a template for the clock device driver initialization.
 *
 *  If possible, please use the dev/clock/clockimpl.h method for instantiating
 *  a clock driver.
 */

/*
 *  COPYRIGHT (c) 1989-2014.
 *  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.
 */

#include <stdlib.h>

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

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    4

/*
 *  Clock_driver_ticks is a monotonically increasing counter of the
 *  number of clock ticks since the driver was initialized.
 */
volatile uint32_t         Clock_driver_ticks;

/*
 *  Clock_isrs is the number of clock ISRs until the next invocation of
 *  the RTEMS clock tick routine.  The clock tick device driver
 *  gets an interrupt once a millisecond and counts down until the
 *  length of time between the user configured microseconds per tick
 *  has passed.
 */
uint32_t         Clock_isrs;              /* ISRs until next tick */

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

static void Clock_exit( void );

/*
 *  Isr Handler
 */
static 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
   */
}

/*
 *  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;
  Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000;

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

  /* XXX */

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

  atexit( Clock_exit );
}

/*
 *  Clean up before the application exits
 */

void Clock_exit( void )
{
  /* XXX: turn off the timer interrupts */

  /* XXX: If necessary, restore the old vector */
}

void _Clock_Initialize( void )
{
  Install_clock( Clock_isr );
}