/*
 * Copyright (c) 2010-2016 Free Software Foundation.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <device/intr.h>
#include <device/ds_routines.h>
#include <ipc/ipc_space.h>
#include <kern/debug.h>
#include <kern/queue.h>
#include <kern/printf.h>
#include <mach/notify.h>

#include "interrupt.h"

#ifndef MACH_XEN
// TODO this is only for x86 system
#define sti() __asm__ __volatile__ ("sti": : :"memory")
#define cli() __asm__ __volatile__ ("cli": : :"memory")

/* The cache which holds our proxy memory objects.  */
static struct kmem_cache intr_entry_cache;

struct intr_entry
{
  ipc_port_t port;	/* We receive notifications on this port.  */
  queue_chain_t chain;
  ipc_port_t dest;
  int line;
  /* The number of interrupts occur since last run of intr_thread. */
  int interrupts;
};
typedef struct intr_entry *intr_entry_t;

static queue_head_t intr_queue;

/* This function can only be used in the interrupt handler. */
boolean_t
queue_intr (struct intr_entry *e)
{
  cli ();
  e->interrupts++;
  sti ();

  thread_wakeup ((event_t) &intr_thread);
  return TRUE;
}

/* insert an interrupt entry in the queue.
 * This entry exists in the queue until
 * the corresponding interrupt port is removed.*/
kern_return_t
insert_intr_entry (int line, ipc_port_t dest, struct intr_entry **entry)
{
  kern_return_t err = 0;
  struct intr_entry *e, *new;
  int free = 0;
  ipc_port_t dnnotify;
  ipc_port_request_index_t dnindex;

  new = (struct intr_entry *) kmem_cache_alloc (&intr_entry_cache);
  if (new == NULL)
    return D_NO_MEMORY;

  /* Allocate port, keeping a reference for it.  */
  new->port = ipc_port_alloc_kernel ();
  if (new->port == IP_NULL)
    {
      kmem_cache_free (&intr_entry_cache, (vm_offset_t) new);
      return KERN_RESOURCE_SHORTAGE;
    }

  /* Associate the port with the object.  */
  ipc_kobject_set (new->port, (ipc_kobject_t) new, IKOT_INTR_ENTRY);

  new->line = line;
  new->dest = dest;
  new->interrupts = 0;

  /* Register a dead-name notification so that we are notified if the
     userspace handler dies.  */
  dnnotify = ipc_port_make_sonce (new->port);
  ip_lock (dest);
  /* We use a bogus port name.  We don't need it to distinguish the
     notifications because we register just one per object.  */
 retry:
  err = ipc_port_dnrequest (dest, (mach_port_t) 1, dnnotify, &dnindex);
  if (err)
    {
      err = ipc_port_dngrow (dest);
      /* dest is unlocked */
      if (err != KERN_SUCCESS)
	{
	  ipc_port_release_sonce (dnnotify);
	  kmem_cache_free (&intr_entry_cache, (vm_offset_t) new);
	  return err;
	}
      ip_lock (dest);
      goto retry;
    }
  /* dest is locked.  dnindex is only valid until we unlock it and we
     might decide to cancel.  */

  /* check whether the intr entry has been in the queue. */
  cli ();
  queue_iterate (&intr_queue, e, struct intr_entry *, chain)
    if (e->dest == dest && e->line == line)
      {
	printf ("the interrupt entry for line %d and port %p "
		"has already been inserted before.\n",
		line, dest);
	free = 1;
	err = D_ALREADY_OPEN;
	goto out;
      }
  queue_enter (&intr_queue, new, struct intr_entry *, chain);
out:
  sti ();
  if (free)
    {
      ipc_port_dncancel (new->dest, (mach_port_t) 1, dnindex);
      ip_unlock (new->dest);
      ipc_port_release_sonce (dnnotify);
      ipc_port_dealloc_kernel (new->port);
      ipc_port_release_send (new->dest);
      kmem_cache_free (&intr_entry_cache, (vm_offset_t) new);
    }
  else
    ip_unlock (new->dest);
  *entry = new;
  return err;
}

/* Lookup a intr_entry object by its port.  */
static intr_entry_t
intr_entry_port_lookup (ipc_port_t port)
{
  struct intr_entry *entry;

  if (!IP_VALID(port))
    return 0;

  ip_lock (port);
  if (ip_active (port) && (ip_kotype (port) == IKOT_INTR_ENTRY))
    entry = (struct intr_entry *) port->ip_kobject;
  else
    entry = 0;
  ip_unlock (port);
  return entry;
}

/* Process a dead-name notification for a userspace interrupt handler
   notification port.  */
boolean_t
intr_entry_notify (mach_msg_header_t *msg)
{
  if (msg->msgh_id == MACH_NOTIFY_DEAD_NAME)
    {
      struct intr_entry *entry;
      int line;
      mach_dead_name_notification_t *dn;

      dn = (mach_dead_name_notification_t *) msg;
      entry = intr_entry_port_lookup
	((ipc_port_t) dn->not_header.msgh_remote_port);
      assert (entry);

      cli ();
      line = entry->line;
      assert (!queue_empty (&intr_queue));
      queue_remove (&intr_queue, entry, struct intr_entry *, chain);
      sti ();

      ipc_port_dealloc_kernel (entry->port);
      ipc_port_release_send (entry->dest);
      kmem_cache_free (&intr_entry_cache, (vm_offset_t) entry);

      printf ("irq handler %d: userspace handler died\n", line);
      return TRUE;
    }

  printf ("intr_entry_notify: strange notification %d\n",
	  msg->msgh_id);
  return FALSE;
}


mach_intr_notification_t mach_intr_notification_template;

static void
init_mach_intr_notification (mach_intr_notification_t *n)
{
  mach_msg_header_t *m = &n->intr_header;
  mach_msg_type_t *t = &n->intr_type;

  m->msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_PORT_SEND, 0);
  m->msgh_size = sizeof *n;
  m->msgh_seqno = INTR_NOTIFY_MSGH_SEQNO;
  m->msgh_local_port = MACH_PORT_NULL;
  m->msgh_remote_port = MACH_PORT_NULL;
  m->msgh_id = MACH_INTR_NOTIFY;

  t->msgt_name = MACH_MSG_TYPE_INTEGER_32;
  t->msgt_size = 32;
  t->msgt_number = 1;
  t->msgt_inline = TRUE;
  t->msgt_longform = FALSE;
  t->msgt_deallocate = FALSE;
  t->msgt_unused = 0;
}

static boolean_t
deliver_intr (int line, ipc_port_t dest_port)
{
  ipc_kmsg_t kmsg;
  mach_intr_notification_t *n;
  mach_port_t dest = (mach_port_t) dest_port;

  if (dest == MACH_PORT_NULL)
    return FALSE;

  kmsg = ikm_alloc(sizeof *n);
  if (kmsg == IKM_NULL)
    return FALSE;

  ikm_init(kmsg, sizeof *n);
  n = (mach_intr_notification_t *) &kmsg->ikm_header;
  *n = mach_intr_notification_template;

  n->intr_header.msgh_remote_port = dest;
  n->line = line;

  ipc_port_copy_send (dest_port);
  ipc_mqueue_send_always(kmsg);

  return TRUE;
}

void
intr_thread ()
{
  struct intr_entry *e;
  int line;
  ipc_port_t dest;
  queue_init (&intr_queue);
  init_mach_intr_notification (&mach_intr_notification_template);

  kmem_cache_init (&intr_entry_cache, "intr_entry",
		   sizeof (struct intr_entry), 0, NULL, 0);

  for (;;)
    {
      assert_wait ((event_t) &intr_thread, FALSE);
      cli ();

    restart:
      queue_iterate (&intr_queue, e, struct intr_entry *, chain)
	if (e->interrupts)
	  {
	    line = e->line;
	    dest = e->dest;
	    e->interrupts--;

	    sti ();
	    deliver_intr (line, dest);
	    cli ();

	    /* We cannot assume that e still exists at this point
	       because we released the lock.  Hence we restart the
	       iteration.  */
	    goto restart;
	  }

      sti ();
      thread_block (thread_no_continuation);
    }
}

#else	/* MACH_XEN */

boolean_t
intr_entry_notify (mach_msg_header_t *msg)
{
  panic ("not reached");
}

#endif	/* MACH_XEN */