/*
   * llc_core.c - Minimum needed routines for sap handling and module init/exit
   *
   * Copyright (c) 1997 by Procom Technology, Inc.
   * 		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   *
   * This program can be redistributed or modified under the terms of the
   * GNU General Public License as published by the Free Software Foundation.
   * This program is distributed without any warranty or implied warranty
   * of merchantability or fitness for a particular purpose.
   *
   * See the GNU General Public License for more details.
   */
  
  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/if_ether.h>
  #include <linux/netdevice.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  #include <linux/init.h>

  #include <net/net_namespace.h>

  #include <net/llc.h>
  
  LIST_HEAD(llc_sap_list);

  static DEFINE_SPINLOCK(llc_sap_list_lock);

  /**
   *	llc_sap_alloc - allocates and initializes sap.
   *
   *	Allocates and initializes sap.
   */
  static struct llc_sap *llc_sap_alloc(void)
  {

  	struct llc_sap *sap = kzalloc(sizeof(*sap), GFP_ATOMIC);

  	int i;

  
  	if (sap) {

  		/* sap->laddr.mac - leave as a null, it's filled by bind */

  		sap->state = LLC_SAP_STATE_ACTIVE;

  		spin_lock_init(&sap->sk_lock);

  		for (i = 0; i < LLC_SK_LADDR_HASH_ENTRIES; i++)
  			INIT_HLIST_NULLS_HEAD(&sap->sk_laddr_hash[i], i);

  		atomic_set(&sap->refcnt, 1);

  	}
  	return sap;
  }

  static struct llc_sap *__llc_sap_find(unsigned char sap_value)

  {

  	struct llc_sap *sap;

  
  	list_for_each_entry(sap, &llc_sap_list, node)
  		if (sap->laddr.lsap == sap_value)
  			goto out;
  	sap = NULL;
  out:
  	return sap;
  }

  /**
   *	llc_sap_find - searchs a SAP in station
   *	@sap_value: sap to be found
   *
   *	Searchs for a sap in the sap list of the LLC's station upon the sap ID.

   *	If the sap is found it will be refcounted and the user will have to do
   *	a llc_sap_put after use.

   *	Returns the sap or %NULL if not found.
   */
  struct llc_sap *llc_sap_find(unsigned char sap_value)
  {

  	struct llc_sap *sap;

  	rcu_read_lock_bh();

  	sap = __llc_sap_find(sap_value);
  	if (sap)
  		llc_sap_hold(sap);

  	rcu_read_unlock_bh();

  	return sap;
  }
  
  /**
   *	llc_sap_open - open interface to the upper layers.
   *	@lsap: SAP number.
   *	@func: rcv func for datalink protos
   *
   *	Interface function to upper layer. Each one who wants to get a SAP
   *	(for example NetBEUI) should call this function. Returns the opened
   *	SAP for success, NULL for failure.
   */
  struct llc_sap *llc_sap_open(unsigned char lsap,
  			     int (*func)(struct sk_buff *skb,
  					 struct net_device *dev,

  					 struct packet_type *pt,
  					 struct net_device *orig_dev))

  {

  	struct llc_sap *sap = NULL;

  	spin_lock_bh(&llc_sap_list_lock);

  	if (__llc_sap_find(lsap)) /* SAP already exists */

  		goto out;

  	sap = llc_sap_alloc();
  	if (!sap)
  		goto out;
  	sap->laddr.lsap = lsap;
  	sap->rcv_func	= func;

  	list_add_tail_rcu(&sap->node, &llc_sap_list);

  out:

  	spin_unlock_bh(&llc_sap_list_lock);

  	return sap;
  }
  
  /**
   *	llc_sap_close - close interface for upper layers.
   *	@sap: SAP to be closed.
   *
   *	Close interface function to upper layer. Each one who wants to
   *	close an open SAP (for example NetBEUI) should call this function.
   * 	Removes this sap from the list of saps in the station and then
   * 	frees the memory for this sap.
   */
  void llc_sap_close(struct llc_sap *sap)
  {

  	WARN_ON(sap->sk_count);

  
  	spin_lock_bh(&llc_sap_list_lock);
  	list_del_rcu(&sap->node);
  	spin_unlock_bh(&llc_sap_list_lock);
  
  	synchronize_rcu();

  	kfree(sap);
  }

  static struct packet_type llc_packet_type __read_mostly = {

  	.type = cpu_to_be16(ETH_P_802_2),

  	.func = llc_rcv,
  };

  static struct packet_type llc_tr_packet_type __read_mostly = {

  	.type = cpu_to_be16(ETH_P_TR_802_2),

  	.func = llc_rcv,
  };
  
  static int __init llc_init(void)
  {

  	dev_add_pack(&llc_packet_type);
  	dev_add_pack(&llc_tr_packet_type);
  	return 0;
  }
  
  static void __exit llc_exit(void)
  {
  	dev_remove_pack(&llc_packet_type);
  	dev_remove_pack(&llc_tr_packet_type);
  }
  
  module_init(llc_init);
  module_exit(llc_exit);

  EXPORT_SYMBOL(llc_sap_list);

  EXPORT_SYMBOL(llc_sap_find);
  EXPORT_SYMBOL(llc_sap_open);
  EXPORT_SYMBOL(llc_sap_close);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Procom 1997, Jay Schullist 2001, Arnaldo C. Melo 2001-2003");
  MODULE_DESCRIPTION("LLC IEEE 802.2 core support");