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/* tick.c -- Simulation of OpenRISC 1000 tick timer

   Copyright (C) 1999 Damjan Lampret, lampret@opencores.org

This file is part of OpenRISC 1000 Architectural Simulator.

This program 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 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT 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 this program; if not, write to the Free Software

Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */

/* This is functional simulation of OpenRISC 1000 architectural

   tick timer.

*/

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include "config.h"

#ifdef HAVE_INTTYPES_H

#include <inttypes.h>

#endif

#include "port.h"

#include "arch.h"

#include "abstract.h"

#include "except.h"

#include "tick.h"

#include "spr_defs.h"

#include "pic.h"

#include "sprs.h"

#include "sim-config.h"

#include "sched.h"

/* When did the timer start to count */

int cycles_start = 0;

/* TT Count Register */

unsigned long ttcr;

/* TT Mode Register */

unsigned long ttmr;

/* Reset. It initializes TTCR register. */

void tick_reset()

{

  if (config.sim.verbose)

    PRINTF("Resetting Tick Timer.\n");

  mtspr(SPR_TTCR, 0);

  mtspr(SPR_TTMR, 0);

}

/* Job handler for tick timer */

void tick_job (void *param)

{

  int mode = (ttmr & SPR_TTMR_M) >> 30;

  /*debug (7, "tick_job%i, param %i\n", param, mode);*/

  switch (mode) {

  case 1:

    if (!param) {

      sprs[SPR_TTCR] = ttcr = 0;

      cycles_start = runtime.sim.cycles - ttcr;

      SCHED_ADD(tick_job, (void *)0, (ttmr & SPR_TTMR_PERIOD) - ttcr);

    }

  case 2:

    if (ttmr & SPR_TTMR_IE) {

      setsprbits(SPR_TTMR, SPR_TTMR_IP, 1);

      /* be sure not to issue timer exception if an exception occured before it */

      if ((mfspr(SPR_SR) & SPR_SR_TEE) == SPR_SR_TEE)

        except_handle(EXCEPT_TICK, mfspr(SPR_EEAR_BASE));

      else

        /* If TEE is currently not set we have to pend tick exception

           by rescheduling. */

        SCHED_ADD(tick_job, (void *)1, 1);

    }

    break;

  }

}

/* Starts the tick timer.  This function is called by a write to ttcr spr register */

void spr_write_ttcr (unsigned long value)

{

  unsigned mode = (ttmr & SPR_TTMR_M) >> 30;

  /*debug (7, "ttcr = %08x\n", value);*/

  ttcr = value;

  /* Remove previous if it exists */

  SCHED_FIND_REMOVE(tick_job, (void *)0);

  SCHED_FIND_REMOVE(tick_job, (void *)1);

  if (mode == 1 || mode == 2) {

    SCHED_ADD(tick_job, (void *)0, (ttmr & SPR_TTMR_PERIOD) - ttcr);

    cycles_start = runtime.sim.cycles - ttcr;

  }

}

void spr_write_ttmr (unsigned long value)

{

  /*debug (7, "ttmr = %08x\n", value);*/

  ttmr = value;

  /* Handle the modes properly. */

  switch((ttmr & SPR_TTMR_M) >> 30) {

    case 0:    /* Timer is disabled */

      SCHED_FIND_REMOVE(tick_job, (void *)0);

      SCHED_FIND_REMOVE(tick_job, (void *)1);

      break;

    case 1:    /* Timer should auto restart */

      sprs[SPR_TTCR] = ttcr = 0;

      cycles_start = runtime.sim.cycles;

      SCHED_FIND_REMOVE(tick_job, (void *)0);

      SCHED_FIND_REMOVE(tick_job, (void *)1);

      SCHED_ADD(tick_job, (void *)0, (ttmr & SPR_TTMR_PERIOD) - ttcr);

      break;

    case 2:    /* Stop the timer when match */

      SCHED_FIND_REMOVE(tick_job, (void *)0);

      SCHED_FIND_REMOVE(tick_job, (void *)1);

      break;

    case 3:    /* Timer keeps running -- do nothing*/

      break;

  }

}

unsigned long spr_read_ttcr ()

{

  /*debug (7, "ttcr ---- %08x\n", runtime.sim.cycles - cycles_start);*/

  return runtime.sim.cycles - cycles_start;

}