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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"
#include "debug.h"
 
DEFAULT_DEBUG_CHANNEL(tick);
 
/* 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;
  TRACE("tick_job param: %i, mode: %i at %lli (%lli)\n", (int)param, mode,
        runtime.sim.cycles, runtime.cpu.instructions);
  switch (mode) {
  case 1:
    if (!param) {
      sprs[SPR_TTCR] = ttcr = 0;
      cycles_start = runtime.sim.cycles - ttcr;
      TRACE("Scheduleing timer job for %li\n", (ttmr & SPR_TTMR_PERIOD) - 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;
  TRACE("set ttcr = %"PRIxREG"\n", value);
  ttcr = value;
  /* Remove previous if it exists */
  TRACE("Removeing scheduled jobs\n");
  SCHED_FIND_REMOVE(tick_job, (void *)0);
  SCHED_FIND_REMOVE(tick_job, (void *)1);
  if (mode == 1 || mode == 2) {
    TRACE("Scheduleing timer job for %li\n", (ttmr & SPR_TTMR_PERIOD) - ttcr);
    SCHED_ADD(tick_job, (void *)0, (ttmr & SPR_TTMR_PERIOD) - ttcr);
    cycles_start = runtime.sim.cycles - ttcr;
  }
}
 
void spr_write_ttmr (unsigned long value)
{
  TRACE("set ttmr = %"PRIxREG"\n", value);
  ttmr = value;
  /* Handle the modes properly. */
  switch((ttmr & SPR_TTMR_M) >> 30) {
    case 0:    /* Timer is disabled */
      TRACE("Removeing scheduled jobs\n");
      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;
      TRACE("Removeing scheduled jobs\n");
      SCHED_FIND_REMOVE(tick_job, (void *)0);
      SCHED_FIND_REMOVE(tick_job, (void *)1);
      TRACE("Scheduleing timer job for %li\n", (ttmr & SPR_TTMR_PERIOD) - ttcr);
      SCHED_ADD(tick_job, (void *)0, (ttmr & SPR_TTMR_PERIOD) - ttcr);
      break;
    case 2:    /* Stop the timer when match */
      TRACE("Removeing scheduled jobs\n");
      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 ()
{
  TRACE("read ttcr %lli\n", runtime.sim.cycles - cycles_start);
  return runtime.sim.cycles - cycles_start;
}