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/*  clock.c

 *

 *  This routine initializes the PIT on the MPC821.

 *  The tick frequency is specified by the bsp.

 *

 *  Author: Jay Monkman (jmonkman@frasca.com)

 *  Copyright (C) 1998 by Frasca International, Inc.

 *

 *  Derived from c/src/lib/libcpu/ppc/ppc403/clock/clock.c:

 *

 *  Author: Andrew Bray <andy@i-cubed.co.uk>

 *

 *  COPYRIGHT (c) 1995 by i-cubed ltd.

 *

 *  To anyone who acknowledges that this file is provided "AS IS"

 *  without any express or implied warranty:

 *      permission to use, copy, modify, and distribute this file

 *      for any purpose is hereby granted without fee, provided that

 *      the above copyright notice and this notice appears in all

 *      copies, and that the name of i-cubed limited not be used in

 *      advertising or publicity pertaining to distribution of the

 *      software without specific, written prior permission.

 *      i-cubed limited makes no representations about the suitability

 *      of this software for any purpose.

 *

 *  Derived from c/src/lib/libcpu/hppa1_1/clock/clock.c:

 *

 *  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.OARcorp.com/rtems/license.html.

 *

 *  $Id: clock.c,v 1.2 2001-09-27 12:01:26 chris Exp $

 */

#include <clockdrv.h>

#include <rtems/libio.h>

#include <stdlib.h>                     /* for atexit() */

#include <mpc821.h>

volatile rtems_unsigned32 Clock_driver_ticks;

extern volatile m821_t m821;

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)

{

  m821.piscr |= M821_PISCR_PS;

  Clock_driver_ticks++;

  rtems_clock_tick();

}

void Install_clock(rtems_isr_entry clock_isr)

{

  rtems_isr_entry previous_isr;

  rtems_unsigned32 pit_value;

  Clock_driver_ticks = 0;

  pit_value = rtems_configuration_get_microseconds_per_tick() /

               rtems_cpu_configuration_get_clicks_per_usec();

  if (pit_value == 0) {

    pit_value = 0xffff;

  } else {

    pit_value--;

  }

  if (pit_value > 0xffff) {           /* pit is only 16 bits long */

    rtems_fatal_error_occurred(-1);

  }

  /*

   * initialize the interval here

   * First tick is set to right amount of time in the future

   * Future ticks will be incremented over last value set

   * in order to provide consistent clicks in the face of

   * interrupt overhead

   */

  rtems_interrupt_catch(clock_isr, PPC_IRQ_LVL0, &previous_isr);

  m821.sccr &= ~(1<<24);

  m821.pitc = pit_value;

  /* set PIT irq level, enable PIT, PIT interrupts */

  /*  and clear int. status */

  m821.piscr = M821_PISCR_PIRQ(0) |

    M821_PISCR_PTE | M821_PISCR_PS | M821_PISCR_PIE;

  m821.simask |= M821_SIMASK_LVM0;

  atexit(Clock_exit);

}

void

ReInstall_clock(rtems_isr_entry new_clock_isr)

{

  rtems_isr_entry previous_isr;

  rtems_unsigned32 isrlevel = 0;

  rtems_interrupt_disable(isrlevel);

  rtems_interrupt_catch(new_clock_isr, PPC_IRQ_LVL0, &previous_isr);

  rtems_interrupt_enable(isrlevel);

}

/*

 * Called via atexit()

 * Remove the clock interrupt handler by setting handler to NULL

 */

void

Clock_exit(void)

{

  /* disable PIT and PIT interrupts */

  m821.piscr &= ~(M821_PISCR_PTE | M821_PISCR_PIE);

  (void) set_vector(0, PPC_IRQ_LVL0, 1);

}

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_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(PPC_IRQ_LVL0);

  }

  else if (args->command == rtems_build_name('N', 'E', 'W', ' ')) {

    ReInstall_clock(args->buffer);

  }

 done:

  return RTEMS_SUCCESSFUL;

}