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/* pic.c -- Simulation of OpenRISC 1000 programmable interrupt controller

   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

   programmable interrupt controller.

*/

#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 "pic.h"

#include "opcode/or32.h"

#include "spr_defs.h"

#include "execute.h"

#include "except.h"

#include "sprs.h"

#include "sim-config.h"

#include "sched.h"

#include "debug.h"

DEFAULT_DEBUG_CHANNEL(pic);

/* Reset. It initializes PIC registers. */

void pic_reset()

{

  PRINTF("Resetting PIC.\n");

  cpu_state.sprs[SPR_PICMR] = 0;

  cpu_state.sprs[SPR_PICPR] = 0;

  cpu_state.sprs[SPR_PICSR] = 0;

}

/* Handles the reporting of an interrupt if it had to be delayed */

void pic_clock(void *dat)

{

  /* Don't do anything if interrupts not currently enabled */

  if(cpu_state.sprs[SPR_SR] & SPR_SR_IEE) {

    TRACE("Delivering interrupt on cycle %lli\n", runtime.sim.cycles);

    except_handle(EXCEPT_INT, cpu_state.sprs[SPR_EEAR_BASE]);

  } else if(cpu_state.sprs[SPR_PICSR] & cpu_state.sprs[SPR_PICMR])

    /* Reschedule only if the interrupt hasn't been cleared */

    sched_next_insn(pic_clock, NULL);

}

/* WARNING: Don't eaven try and call this function *during* a simulated

 * instruction!! (as in during a read_mem or write_mem callback).  except_handle

 * assumes that this is the case, it breaks otherwise. */

/* WARNING2: Don't except report_interrupt to return!  However, it also _may_

 * return.  Make sure you handle this case aswell. */

/* Asserts interrupt to the PIC. */

void report_interrupt(int line)

{

  /* Disable doze and sleep mode */

  cpu_state.sprs[SPR_PMR] &= ~(SPR_PMR_DME | SPR_PMR_SME);

  TRACE("Asserting interrupt %d (%s).\n", line,

        (cpu_state.sprs[SPR_PICMR] & (1 << line)) ? "Unmasked" : "Masked");

  SCHED_FIND_REMOVE(pic_clock, NULL);

  if ((cpu_state.sprs[SPR_PICMR] & (1 << line)) || line < 2) {

    cpu_state.sprs[SPR_PICSR] |= 1 << line;

    /* Don't do anything if interrupts not currently enabled */

    if (cpu_state.sprs[SPR_SR] & SPR_SR_IEE) {

      TRACE("Delivering interrupt on cycle %lli\n", runtime.sim.cycles);

      except_handle(EXCEPT_INT, cpu_state.sprs[SPR_EEAR_BASE]);

      return;

    }

  }

  if(cpu_state.sprs[SPR_PICMR] & cpu_state.sprs[SPR_PICSR])

    /* Interrupts not currently enabled, retry next clock cycle */

    sched_next_insn(pic_clock, NULL);

}