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

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

   Copyright (C) 2008 Embecosm Limited

   Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>

   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 3 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, see <http://www.gnu.org/licenses/>. */

/* This program is commented throughout in a fashion suitable for processing

   with Doxygen. */

/* Autoconf and/or portability configuration */

#include "config.h"

#include "port.h"

/* System includes */

#include <stdlib.h>

#include <stdio.h>

/* Package includes */

#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"

/* -------------------------------------------------------------------------- */

/* Reset the PIC.

   Sets registers to consistent values.                                       */

/* -------------------------------------------------------------------------- */

void

pic_reset (void)

{

  PRINTFQ ("Resetting PIC.\n");

  cpu_state.sprs[SPR_PICMR] = config.pic.use_nmi ? 0x00000003 : 0x00000000;

  cpu_state.sprs[SPR_PICSR] = 0x00000000;

}       /* pic_reset () */

/* -------------------------------------------------------------------------- */

/* Handle the reporting of an interrupt

   PIC interrupts are scheduled to take place after the current instruction

   has completed execution.

   @param[in] dat  Data associated with the exception (not used)              */

/* -------------------------------------------------------------------------- */

static void

pic_rep_int (void *dat)

{

  /* printf ("Handling interrupt PICSR: 0x%08x\n", cpu_state.sprs[SPR_PICSR]);

   */

  if (cpu_state.sprs[SPR_PICSR])

    {

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

    }

}       /* pic_rep_int () */

/* -------------------------------------------------------------------------- */

/* Enable interrupts.

   Called whenever interrupts get enabled, or when PICMR is written.

   @todo Not sure if calling whenever PICMR is written is a good

         idea. However, so long as interrupts are properly cleared, it should

         not be a problem.                                                    */

/* -------------------------------------------------------------------------- */

void

pic_ints_en (void)

{

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

    {

      SCHED_ADD (pic_rep_int, NULL, 0);

    }

}       /* pic_ints_en () */

/* -------------------------------------------------------------------------- */

/*!Assert an interrupt to the PIC

   OpenRISC supports both edge and level triggered interrupt. The only

   difference is how the interrupt is cleared. For edge triggered, it is by

   clearing the corresponding bit in PICSR. For level triggered it is by

   deasserting the interrupt line.

   For integrated peripherals, these amount to the same thing (using

   clear_interrupt ()). For external peripherals, the library provides two

   distinct interfaces.

   An interrupt disables any power management activity.

   We warn if an interrupt is received on a line that already has an interrupt

   pending.

   @note If this is called during a simulated instruction (ie. from a read/

         write mem callback), the interrupt will be delivered after the

         instruction has finished executing.

   @param[in] line  The interrupt being asserted.                             */

/* -------------------------------------------------------------------------- */

void

report_interrupt (int line)

{

  uint32_t lmask = 1 << line;

  /* printf ("Interrupt reported on line %d\n", line); */

  /* Disable doze and sleep mode */

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

  /* If PIC is disabled, don't set any register, just raise EXCEPT_INT */

  if (!config.pic.enabled)

    {

      if (cpu_state.sprs[SPR_SR] & SPR_SR_IEE)

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

      return;

    }

  /* We can't take another interrupt if the previous one has not been

     cleared. */

  if (cpu_state.sprs[SPR_PICSR] & lmask)

    {

      /* Interrupt already signaled and pending */

      PRINTF ("Warning: Int on line %d pending: ignored\n", line);

      return;

    }

  cpu_state.sprs[SPR_PICSR] |= lmask;

  /* If we are enabled in the mask, and interrupts are globally enabled in the

     SR, schedule the interrupt to take place after the next instruction. */

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

      (cpu_state.sprs[SPR_SR] & SPR_SR_IEE))

    {

      SCHED_ADD (pic_rep_int, NULL, 0);

    }

}       /* report_interrupt () */

/* -------------------------------------------------------------------------- */

/* Clear an interrupt on a PIC line.

   Logically this is different for a level sensitive interrupt (it lowers the

   input line) and an edge sensitive interrupt (it clears the PICSR bit).

   However within Or1ksim, these are implemented through the same operation -

   clearing the bit in PICSR.

   @param[in] line  The interrupt being cleared.                              */

/* -------------------------------------------------------------------------- */

void

clear_interrupt (int line)

{

  cpu_state.sprs[SPR_PICSR] &= ~(1 << line);

}       /* clear_interrupt */

/*----------------------------------------------------[ PIC configuration ]---*/

/*---------------------------------------------------------------------------*/

/*!Enable or disable the programmable interrupt controller

   Set the corresponding field in the UPR

   @param[in] val  The value to use

   @param[in] dat  The config data structure (not used here)                 */

/*---------------------------------------------------------------------------*/

static void

pic_enabled (union param_val  val,

             void            *dat)

{

  if (val.int_val)

    {

      cpu_state.sprs[SPR_UPR] |= SPR_UPR_PICP;

    }

  else

    {

      cpu_state.sprs[SPR_UPR] &= ~SPR_UPR_PICP;

    }

  config.pic.enabled = val.int_val;

}       /* pic_enabled() */

/*---------------------------------------------------------------------------*/

/*!Enable or disable edge triggering of interrupts

   @param[in] val  The value to use

   @param[in] dat  The config data structure (not used here)                 */

/*---------------------------------------------------------------------------*/

static void

pic_edge_trigger (union param_val  val,

                  void            *dat)

{

  config.pic.edge_trigger = val.int_val;

}       /* pic_edge_trigger() */

/*---------------------------------------------------------------------------*/

/*!Enable or disable non-maskable interrupts

   @param[in] val  The value to use

   @param[in] dat  The config data structure (not used here)                 */

/*---------------------------------------------------------------------------*/

static void

pic_use_nmi (union param_val  val,

                  void            *dat)

{

  config.pic.use_nmi = val.int_val;

}       /* pic_use_nmi() */

/*---------------------------------------------------------------------------*/

/*!Initialize a new interrupt controller configuration

   ALL parameters are set explicitly to default values in init_defconfig()   */

/*---------------------------------------------------------------------------*/

void

reg_pic_sec ()

{

  struct config_section *sec = reg_config_sec ("pic", NULL, NULL);

  reg_config_param (sec, "enabled",      PARAMT_INT, pic_enabled);

  reg_config_param (sec, "edge_trigger", PARAMT_INT, pic_edge_trigger);

  reg_config_param (sec, "use_nmi",      PARAMT_INT, pic_use_nmi);

}       /* reg_pic_sec() */