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/*

 *  Clock Tick Device Driver

 *

 *  This routine utilizes the Decrementer Register common to the PPC family.

 *

 *  The tick frequency is directly programmed to the configured number of

 *  microseconds per tick.

 *

 *  COPYRIGHT (c) 1989-1997.

 *  On-Line Applications Research Corporation (OAR).

 *  Copyright assigned to U.S. Government, 1994.

 *

 *  The license and distribution terms for this file may 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 12:01:03 chris Exp $

 */

#include <stdlib.h>

#include <bsp.h>

#include <rtems/libio.h>

#include <assert.h>

/*

 *  The Real Time Clock Counter Timer uses this trap type.

 */

#define CLOCK_VECTOR PPC_IRQ_DECREMENTER

/*

 *  Clock ticks since initialization

 */

volatile rtems_unsigned32 Clock_driver_ticks;

/*

 *  This is the value programmed into the count down timer.

 */

rtems_unsigned32 Clock_Decrementer_value;

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;

#define PPC_Set_decrementer( _clicks ) \

  do { \

    asm volatile( "mtdec %0" : "=r" ((_clicks)) : "r" ((_clicks)) ); \

  } while (0)

/*

 *  Clock_isr

 *

 *  This is the clock tick interrupt handler.

 *

 *  Input parameters:

 *    vector - vector number

 *

 *  Output parameters:  NONE

 *

 *  Return values:      NONE

 *

 */

rtems_isr Clock_isr(

  rtems_vector_number  vector,

  CPU_Interrupt_frame *frame

)

{

  /*

   *  Set the decrementer.

   */

  PPC_Set_decrementer( Clock_Decrementer_value );

  /*

   *  The driver has seen another tick.

   */

  Clock_driver_ticks += 1;

  /*

   *  Real Time Clock counter/timer is set to automatically reload.

   */

  rtems_clock_tick();

}

/*

 *  Install_clock

 *

 *  This routine actually performs the hardware initialization for the clock.

 *

 *  Input parameters:

 *    clock_isr - clock interrupt service routine entry point

 *

 *  Output parameters:  NONE

 *

 *  Return values:      NONE

 *

 */

extern int CLOCK_SPEED;

void Install_clock(

  rtems_isr_entry clock_isr

)

{

  Clock_driver_ticks = 0;

  Old_ticker = (rtems_isr_entry) set_vector( clock_isr, CLOCK_VECTOR, 1 );

  PPC_Set_decrementer( Clock_Decrementer_value );

  atexit( Clock_exit );

}

/*

 *  Clock_exit

 *

 *  This routine allows the clock driver to exit by masking the interrupt and

 *  disabling the clock's counter.

 *

 *  Input parameters:   NONE

 *

 *  Output parameters:  NONE

 *

 *  Return values:      NONE

 *

 */

void Clock_exit( void )

{

  /* nothing to do */;

  /* do not restore old vector */

}

/*

 *  Clock_initialize

 *

 *  This routine initializes the clock driver.

 *

 *  Input parameters:

 *    major - clock device major number

 *    minor - clock device minor number

 *    parg  - pointer to optional device driver arguments

 *

 *  Output parameters:  NONE

 *

 *  Return values:

 *    rtems_device_driver status code

 */

rtems_device_driver Clock_initialize(

  rtems_device_major_number major,

  rtems_device_minor_number minor,

  void *pargp

)

{

  Clock_Decrementer_value = (int) &CPU_PPC_CLICKS_PER_MS *

                       (BSP_Configuration.microseconds_per_tick / 1000);

  Install_clock( (rtems_isr_entry) Clock_isr );

  /*

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

   */

  rtems_clock_major = major;

  rtems_clock_minor = minor;

  return RTEMS_SUCCESSFUL;

}

/*

 *  Clock_control

 *

 *  This routine is the clock device driver control entry point.

 *

 *  Input parameters:

 *    major - clock device major number

 *    minor - clock device minor number

 *    parg  - pointer to optional device driver arguments

 *

 *  Output parameters:  NONE

 *

 *  Return values:

 *    rtems_device_driver status code

 */

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, pargp );

    }

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

    {

      rtems_interrupt_disable( isrlevel );

       (void) set_vector( args->buffer, CLOCK_VECTOR, 1 );

      rtems_interrupt_enable( isrlevel );

    }

done:

    return RTEMS_SUCCESSFUL;

}