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/*==========================================================================

//

//      timer_pit.c

//

//      HAL timer code using the Periodic Interval Timer

//

//==========================================================================

// ####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 2006 Free Software Foundation, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under

// the terms of the GNU General Public License as published by the Free

// Software Foundation; either version 2 or (at your option) any later

// version.

//

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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License

// along with eCos; if not, write to the Free Software Foundation, Inc.,

// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

//

// As a special exception, if other files instantiate templates or use

// macros or inline functions from this file, or you compile this file

// and link it with other works to produce a work based on this file,

// this file does not by itself cause the resulting work to be covered by

// the GNU General Public License. However the source code for this file

// must still be made available in accordance with section (3) of the GNU

// General Public License v2.

//

// This exception does not invalidate any other reasons why a work based

// on this file might be covered by the GNU General Public License.

// -------------------------------------------

// ####ECOSGPLCOPYRIGHTEND####

//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):    asl, Oliver Munz

// Contributors: asl, Oliver Munz

// Date:         2009-06-03

// Purpose:      Clock support using the PIT

// Description:

//

//####DESCRIPTIONEND####

//

//========================================================================*/

#include <pkgconf/hal.h>

#include <cyg/infra/cyg_type.h>         // base types

#include <cyg/infra/cyg_ass.h>          // assertion macros

#include <cyg/hal/hal_io.h>             // IO macros

#include <cyg/hal/hal_platform_ints.h>

// -------------------------------------------------------------------------

// Use system clock

void

hal_clock_initialize(cyg_uint32 period){

  cyg_uint32 ir;

  cyg_uint32 pimr;

  CYG_ASSERT(CYGNUM_HAL_INTERRUPT_RTC == CYGNUM_HAL_INTERRUPT_PITC,

             "Invalid timer interrupt");

  CYG_ASSERT(period <= AT91_PITC_VALUE_MASK,

             "Invalid timer period");

  pimr = (period - 1); /* This is what we want */

  HAL_READ_UINT32(AT91_PITC + AT91_PITC_PIIR, ir); /* Counter */

  ir = ir & AT91_PITC_VALUE_MASK; /* The current count */

  do { /* Test if the new PITC-Modulus is overrun by the counter */

    if (ir > pimr){ /* If the counter is already too high */

      pimr = (ir + 100) & AT91_PITC_VALUE_MASK; /* Set the comparator ahead */

      HAL_WRITE_UINT32((AT91_PITC + AT91_PITC_PIMR),

                       pimr | AT91_PITC_PIMR_PITEN);

    }

    if (ir < (period - 1)){ /* If we can try it */

      pimr = (period - 1); /* This is what we want */

      /* Set the real Period Interval timer */

      HAL_WRITE_UINT32((AT91_PITC + AT91_PITC_PIMR),

                       pimr | AT91_PITC_PIMR_PITEN);

    }

    HAL_READ_UINT32(AT91_PITC + AT91_PITC_PIMR, pimr); /* The real value */

    pimr = pimr & AT91_PITC_VALUE_MASK; /* Value */

    HAL_READ_UINT32(AT91_PITC + AT91_PITC_PIIR, ir); /* Counter */

    ir = ir & AT91_PITC_VALUE_MASK; /* The current counts */

  } while (ir > (period - 1) || pimr != (period - 1)); // Is it correct?

  /* Enable interrupt */

  HAL_WRITE_UINT32((AT91_PITC + AT91_PITC_PIMR), (period - 1) |

                   AT91_PITC_PIMR_PITEN | AT91_PITC_PIMR_PITIEN);

  /* Read the status register to clear any pending interrupt */

  HAL_READ_UINT32(AT91_PITC + AT91_PITC_PISR, ir);

}

// This routine is called during a clock interrupt.

void

hal_clock_reset(cyg_uint32 vector, cyg_uint32 period)

{

  cyg_uint32 reg;

  cyg_uint32 pimr;

  CYG_ASSERT(period < AT91_PITC_VALUE_MASK, "Invalid HAL clock configuration");

  // Check that the PIT has the right period.

  HAL_READ_UINT32((AT91_PITC + AT91_PITC_PIMR), pimr);

  if ((pimr & AT91_PITC_VALUE_MASK) != (period - 1)) {

    HAL_WRITE_UINT32((AT91_PITC + AT91_PITC_PIMR),

                     (period - 1) |

                     AT91_PITC_PIMR_PITEN |

                     AT91_PITC_PIMR_PITIEN);

  }

  /* Read the value register so that we clear the interrupt */

  HAL_READ_UINT32(AT91_PITC + AT91_PITC_PIVR, reg);

}

// Read the current value of the clock, returning the number of hardware

// "ticks" that have occurred (i.e. how far away the current value is from

// the start)

void

hal_clock_read(cyg_uint32 *pvalue)

{

  cyg_uint32 ir;

  cyg_uint32 pimr;

  // Check that the PIT is running. If not start it.

  HAL_READ_UINT32((AT91_PITC + AT91_PITC_PIMR),pimr);

  if (!(pimr & AT91_PITC_PIMR_PITEN)) {

    HAL_WRITE_UINT32((AT91_PITC + AT91_PITC_PIMR),

                     AT91_PITC_VALUE_MASK | AT91_PITC_PIMR_PITEN);

  }

  HAL_READ_UINT32(AT91_PITC + AT91_PITC_PIIR, ir);

  *pvalue = ir & AT91_PITC_VALUE_MASK;

}

// -------------------------------------------------------------------------

//

// Delay for some number of micro-seconds

// PIT is clocked at MCLK / 16

//

void hal_delay_us(cyg_int32 usecs)

{

  cyg_int64 ticks;

  cyg_uint32 val1, val2;

  cyg_uint32 piv;

  // Calculate how many PIT ticks the required number of microseconds

  // equate to. We do this calculation in 64 bit arithmetic to avoid

  // overflow.

  ticks = (((cyg_uint64)usecs) *

           ((cyg_uint64)CYGNUM_HAL_ARM_AT91_CLOCK_SPEED))/16/1000000LL;

  // Calculate the wrap around period.

  HAL_READ_UINT32(AT91_PITC + AT91_PITC_PIMR, piv);

  piv = (piv & AT91_PITC_VALUE_MASK) - 1;

  hal_clock_read(&val1);

  while (ticks > 0) {

    hal_clock_read(&val2);

    if (val2 < val1)

      ticks -= ((piv + val2) - val1); //overflow occurred

    else

      ticks -= (val2 - val1);

    val1 = val2;

  }

}

// timer_pit.c