/****************************************************************************
 * arch/misoc/src/minerva/minerva_doirq.c
 *
 *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *           Ramtin Amin <keytwo@gmail.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdint.h>
#include <assert.h>
#include <debug.h>

#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <nuttx/board.h>

#include <arch/irq.h>
#include <arch/board/board.h>

#include "group/group.h"
#include "minerva.h"

/****************************************************************************
 * Public Functions
 ****************************************************************************/

uint32_t *minerva_doirq(int irq, uint32_t * regs)
{
  board_autoled_on(LED_INIRQ);

  /* Current regs non-zero indicates that we are processing an interrupt;
   * g_current_regs is also used to manage interrupt level context switches.
   * Nested interrupts are not supported
   */

  DEBUGASSERT(g_current_regs == NULL);
  g_current_regs = regs;

  /* Disable further occurrences of this interrupt (until the interrupt
   * sources have been clear by the driver).
   */

  up_disable_irq(irq);

  /* Deliver the IRQ */

  irq_dispatch(irq, regs);

#if defined(CONFIG_ARCH_FPU) || defined(CONFIG_ARCH_ADDRENV)
  /* Check for a context switch.  If a context switch occurred, then
   * g_current_regs will have a different value than it did on entry.  If an
   * interrupt level context switch has occurred, then restore the floating
   * point state and the establish the correct address environment before
   * returning from the interrupt.
   */

  if (regs != g_current_regs)
    {
#  ifdef CONFIG_ARCH_FPU
      /* Restore floating point registers */

      up_restorefpu((uint32_t *) g_current_regs);
#  endif

#  ifdef CONFIG_ARCH_ADDRENV
      /* Make sure that the address environment for the previously running
       * task is closed down gracefully (data caches dump, MMU flushed) and
       * set up the address environment for the new thread at the head of
       * the ready-to-run list.
       */

      group_addrenv(NULL);
#  endif
    }
#endif

  /* If a context switch occurred while processing the interrupt then
   * g_current_regs may have change value.  If we return any value different
   * from the input regs, then the lower level will know that a context switch
   * occurred during interrupt processing.
   */

  regs = (uint32_t *) g_current_regs;

  /* Set g_current_regs to NULL to indicate that we are no longer in an
   * interrupt handler.
   */

  g_current_regs = NULL;

  /* Unmask the last interrupt (global interrupts are still disabled) */

  up_enable_irq(irq);
  board_autoled_off(LED_INIRQ);
  return regs;
}