Subversion Repositories openrisc_2011-10-31

/*  ckinit.c

 *

 *  Implementation of the Clock_control() and Clock_initialize() functions

 *  prototyped in rtems/c/src/lib/include/clockdrv.h.

 *

 *  This port does not allow the application to select which timer on the

 *  MVME167 to use for the clock, nor does it allow the application to

 *  configure the clock. The clock uses the VMEchip2 Tick Timer #2. This

 *  timer is set up to raise a MC680x0 level-6 interrupt every 1 ms. The

 *  interrupt vector is 0x69.

 *

 *  All page references are to the MVME166/MVME167/MVME187 Single Board

 *  Computer Programmer's Reference Guide (MVME187PG/D2) with the April

 *  1993 supplements/addenda (MVME187PG/D2A1).

 *

 *  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.

 *

 *  Modifications of respective RTEMS files:

 *  Copyright (c) 1998, National Research Council of Canada

 *

 *  $Id: ckinit.c,v 1.2 2001-09-27 12:00:19 chris Exp $

 */

#include <stdlib.h>

#include <bsp.h>

#include <rtems/libio.h>

#define MS_COUNT          1000              /* T2's countdown constant (1 ms) */

#define CLOCK_INT_LEVEL   6                 /* T2's interrupt level */

#define CLOCK_VECTOR (VBR0 * 0x10 + 0x9)    /* T2 is vector $X9 (p. 2-71)*/

/*

 *  These are declared in rtems/c/src/lib/include/clockdrv.h

 *  In other BSPs, rtems_clock_major is set to the largest possible value

 *  (which is almost certainly greater than the number of I/O devices) to

 *  indicate that this device has not been initialized yet. The actual

 *  device number is supplied during initialization. We do not do that.

 *

 *  Initialized data ends up the the .data section. This causes two problems:

 *  1) the .data section is no longer ROMable because we need to write into

 *  it. 2) The initial value is correct only after a download. On subsequent

 *  program restarts, the value is not re-initialized but left to whatever it

 *  was when the previous run terminated or aborted. If we depend on some

 *  global variable value, we must initialize that value explicitly in code

 *  at boot time.

 */

rtems_device_major_number rtems_clock_major;

rtems_device_minor_number rtems_clock_minor;

/*

 *  Clock_driver_ticks is a monotonically increasing counter of the number of

 *  VMEchip2 timer #2 ticks since the driver was initialized.

 */

volatile rtems_unsigned32 Clock_driver_ticks;

/*

 *  Clock_isrs is the number of clock ISRs until the next invocation of the

 *  RTEMS clock tick routine. This 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. This allows the clock

 *  device to "tick" faster than the kernel clock. Of course, the kernel clock

 *  cannot tick faster than the hardware clock. Therefore, the kernel clock

 *  ticks cannot occur more frequently than every 1 millisecond.

 */

rtems_unsigned32 Clock_isrs;

/*

 *  Records the previous clock ISR (should be NULL)

 */

rtems_isr_entry  Old_ticker;

/*

 *  Called when the kernel exits.

 */

void clock_exit( void );

/*

 *  VMEchip2_T2_isr

 *

 *  C ISR Handler. Increment the number of internal ticks. If it is time for a

 *  kernel clock tick (if Clock_isrs == 1), call rtems_clock_tick() to signal

 *  the event and reset the Clock_isrs counter; else, just decrement it.

 *

 *  Input parameters:

 *    vector number

 *

 *  Output parameters: NONE

 *

 *  Return values: NONE

 */

rtems_isr VMEchip2_T2_isr(

  rtems_vector_number vector

)

{

  char overflow;                /* Content of overflow counter */

  long i;

  long ct;                      /* Number of T2 ticks per RTEMS ticks */

  ct = BSP_Configuration.microseconds_per_tick / 1000;

  /*

   *  May have missed interrupts, so should look at the overflow counter.

   */

  lcsr->intr_clear |= 0x02000000;   /* Clear the interrupt */

  overflow = (lcsr->board_ctl >> 12) & 0xF;

  lcsr->board_ctl |= 0x400;         /* Reset overflow counter */

  /* Attempt to protect against one more period */

  if ( overflow == 0 )

    overflow = 16;

  Clock_driver_ticks += overflow;   /* One or more internal ticks */

  if ( Clock_isrs <= overflow ) {

    /* If its time for kernel clock ticks, signal the events to RTEMS */

    for( i = overflow - Clock_isrs; i >= 0; i -= ct ) {

      rtems_clock_tick();

    }

    /* Reset the counter */

    Clock_isrs = (rtems_unsigned32)-i;

  }

  else

    Clock_isrs -= overflow;

}

/*

 *  VMEchip2_T2_initialize

 *

 *  Initialize the VMEchip2 Tick Timer #2.

 *

 *  THE VMECHIP2 PRESCALER REGISTER IS ASSUMED TO BE SET!

 *  The prescaler is used by all VMEchip2 timers, including the VMEbus grant

 *  timeout counter, the DMAC time off timer, the DMAC timer on timer, and the

 *  VMEbus global timeout timer. The prescaler value is normally set by the

 *  boot ROM to provide a 1 MHz clock to the timers. For a 25 MHz MVME167, the

 *  prescaler value should be 0xE7 (page 2-63).

 *

 *  Input parameters: NONE

 *

 *  Output paremeters: NONE

 *

 *  Return values: NONE

 */

void VMEchip2_T2_initialize( void )

{

  Clock_driver_ticks = 0;

  Clock_isrs = BSP_Configuration.microseconds_per_tick / 1000;

  lcsr->intr_ena &= 0xFDFFFFFF;   /* Disable tick timer 2 interrupt */

  lcsr->intr_clear = 0x02000000;  /* Clear tick timer 2 interrupt */

  lcsr->intr_level[0] =           /* Set tick timer 2 interrupt level */

      (lcsr->intr_level[0] & 0xFFFFFF0F ) | (CLOCK_INT_LEVEL << 4);

  lcsr->timer_cmp_2 = MS_COUNT;   /* Period in compare register */

  lcsr->timer_cnt_2 = 0;          /* Clear tick timer 2 counter */

  Old_ticker =                    /* Install C ISR */

      (rtems_isr_entry) set_vector( VMEchip2_T2_isr, CLOCK_VECTOR, 1 );

  lcsr->board_ctl |= 0x700;       /* Start tick timer 2, reset-on-compare, */

                                  /*  and clear tick timer 2 overflow counter */

  lcsr->intr_ena |= 0x02000000;   /* Enable tick timer 2 interrupt */

  lcsr->vector_base |= 0x00800000;/* Unmask VMEchip2 interrupts */

  atexit( clock_exit );           /* Turn off T2 interrupts when we exit */

}

/*

 *  clock_exit

 *

 *  This routine stops the VMEchip2 T2 timer, disables its interrupt, and

 *  re-install the old interrupt vectors.

 *

 *  Input parameters:   NONE

 *

 *  Output parameters:  NONE

 *

 *  Return values:      NONE

 *

 */

void clock_exit( void )

{

  lcsr->board_ctl &= 0xFFFFFEFF;  /* Stop tick timer 2 */

  lcsr->intr_ena &= 0xFDFFFFFF;   /* Disable tick timer 2 interrupt */

  lcsr->intr_clear = 0x02000000;  /* Clear tick timer 2 interrupt */

  set_vector( Old_ticker, CLOCK_VECTOR, 1 );

}

/*

 *  Clock_initialize()

 *  prototyped in rtems/c/src/lib/include/clockdrv.h.

 *

 *  Input parameters:

 *     major - console device major number

 *     minor - console device minor number

 *             ALWAYS 0 IN VERSION 3.6.0 OF RTEMS!

 *             Probably provided for symmetry with the other I/O calls.

 *     arg   - pointer to optional device driver arguments

 *             ALWAYS NULL IN VERSION 3.6.0 OF RTEMS!

 *

 *  Output paremeters: 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

)

{

  VMEchip2_T2_initialize();

  /*

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

   */

  rtems_clock_major = major;

  rtems_clock_minor = minor;

  return RTEMS_SUCCESSFUL;

}

/*

 *  Clock_control().

 *  Prototyped in rtems/c/src/lib/include/clockdrv.h

 *

 *  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', ' ') )

    {

      VMEchip2_T2_isr( CLOCK_VECTOR );

    }

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

    {

      rtems_interrupt_disable( isrlevel );

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

      rtems_interrupt_enable( isrlevel );

    }

done:

    return RTEMS_SUCCESSFUL;

}