text: /****************************************************************************
   * sched/irq/irq_attach.c
   *
   *   Copyright (C) 2007-2008, 2010, 2012, 2017-2018 Gregory Nutt. All rights
   *     reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * 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 <errno.h>
  
  #include <nuttx/irq.h>
  
  #include "irq/irq.h"
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: irq_attach
   *
   * Description:
   *   Configure the IRQ subsystem so that IRQ number 'irq' is dispatched to
   *   'isr'
   *
   ****************************************************************************/
  
  int irq_attach(int irq, xcpt_t isr, FAR void *arg)
  {
  #if NR_IRQS > 0
    int ret = -EINVAL;
  
    if ((unsigned)irq < NR_IRQS)
      {
        irqstate_t flags;
        int ndx;
  
  #ifdef CONFIG_ARCH_MINIMAL_VECTORTABLE
        /* Is there a mapping for this IRQ number? */
  
        ndx = g_irqmap[irq];
        if ((unsigned)ndx >= CONFIG_ARCH_NUSER_INTERRUPTS)
          {
            /* No.. then return failure. */
  
            return ret;
          }
  #else
        ndx = irq;
  #endif
  
        /* If the new ISR is NULL, then the ISR is being detached.
         * In this case, disable the ISR and direct any interrupts
         * to the unexpected interrupt handler.
         */
  
        flags = enter_critical_section();
        if (isr == NULL)
          {
            /* Disable the interrupt if we can before detaching it.  We might
             * not be able to do this if:  (1) the device does not have a
             * centralized interrupt controller (so up_disable_irq() is not
             * supported). Or (2) if the device has different number for vector
             * numbers and IRQ numbers (in that case, we don't know the correct
             * IRQ number to use to disable the interrupt). In those cases, the
             * code will just need to be careful that it disables all interrupt
             * sources before detaching from the interrupt vector.
             */
  
  #if !defined(CONFIG_ARCH_NOINTC) && !defined(CONFIG_ARCH_VECNOTIRQ)
            up_disable_irq(irq);
  #endif
            /* Detaching the ISR really means re-attaching it to the
             * unexpected exception handler.
             */
  
            isr = irq_unexpected_isr;
            arg = NULL;
          }
  
  #ifdef CONFIG_IRQCHAIN
        /* Save the new ISR and its argument in the table.
         * If there is only one ISR on this irq, then .handler point to the ISR
         * and .arg point to the ISR parameter; Otherwise, .handler point to
         * irqchain_dispatch and .arg point to irqchain_s.
         */
  
        if (is_irqchain(ndx, isr))
          {
            ret = irqchain_attach(ndx, isr, arg);
            leave_critical_section(flags);
            return ret;
          }
  #endif
  
        /* Save the new ISR and its argument in the table. */
  
        g_irqvector[ndx].handler = isr;
        g_irqvector[ndx].arg     = arg;
  #ifdef CONFIG_SCHED_IRQMONITOR
        g_irqvector[ndx].start   = clock_systime_ticks();
  #ifdef CONFIG_HAVE_LONG_LONG
        g_irqvector[ndx].count   = 0;
  #else
        g_irqvector[ndx].mscount = 0;
        g_irqvector[ndx].lscount = 0;
  #endif
  #endif
  
        leave_critical_section(flags);
        ret = OK;
      }
  
    return ret;
  #else
    return OK;
  #endif
  }
  