/*
   * Copyright (C) 2007-2012 Siemens AG
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2
   * as published by the Free Software Foundation.
   *
   * 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, write to the Free Software Foundation, Inc.,
   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Written by:
   * Pavel Smolenskiy <pavel.smolenskiy@gmail.com>
   * Maxim Gorbachyov <maxim.gorbachev@siemens.com>
   * Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
   * Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/workqueue.h>
  #include <linux/netdevice.h>
  #include <linux/crc-ccitt.h>
  
  #include <net/mac802154.h>
  #include <net/ieee802154_netdev.h>
  
  #include "mac802154.h"
  
  /* The IEEE 802.15.4 standard defines 4 MAC packet types:
   * - beacon frame
   * - MAC command frame
   * - acknowledgement frame
   * - data frame
   *
   * and only the data frame should be pushed to the upper layers, other types
   * are just internal MAC layer management information. So only data packets
   * are going to be sent to the networking queue, all other will be processed
   * right here by using the device workqueue.
   */
  struct rx_work {
  	struct sk_buff *skb;
  	struct work_struct work;
  	struct ieee802154_dev *dev;
  	u8 lqi;
  };
  
  static void
  mac802154_subif_rx(struct ieee802154_dev *hw, struct sk_buff *skb, u8 lqi)
  {
  	struct mac802154_priv *priv = mac802154_to_priv(hw);
  
  	mac_cb(skb)->lqi = lqi;
  	skb->protocol = htons(ETH_P_IEEE802154);
  	skb_reset_mac_header(skb);
  
  	BUILD_BUG_ON(sizeof(struct ieee802154_mac_cb) > sizeof(skb->cb));
  
  	if (!(priv->hw.flags & IEEE802154_HW_OMIT_CKSUM)) {
  		u16 crc;
  
  		if (skb->len < 2) {
  			pr_debug("got invalid frame
  ");
  			goto out;
  		}
  		crc = crc_ccitt(0, skb->data, skb->len);
  		if (crc) {
  			pr_debug("CRC mismatch
  ");
  			goto out;
  		}
  		skb_trim(skb, skb->len - 2); /* CRC */
  	}
  
  	mac802154_monitors_rx(priv, skb);
  	mac802154_wpans_rx(priv, skb);
  out:
  	dev_kfree_skb(skb);
  	return;
  }
  
  static void mac802154_rx_worker(struct work_struct *work)
  {
  	struct rx_work *rw = container_of(work, struct rx_work, work);
  	struct sk_buff *skb = rw->skb;
  
  	mac802154_subif_rx(rw->dev, skb, rw->lqi);
  	kfree(rw);
  }
  
  void
  ieee802154_rx_irqsafe(struct ieee802154_dev *dev, struct sk_buff *skb, u8 lqi)
  {
  	struct mac802154_priv *priv = mac802154_to_priv(dev);
  	struct rx_work *work;
  
  	if (!skb)
  		return;
  
  	work = kzalloc(sizeof(struct rx_work), GFP_ATOMIC);
  	if (!work)
  		return;
  
  	INIT_WORK(&work->work, mac802154_rx_worker);
  	work->skb = skb;
  	work->dev = dev;
  	work->lqi = lqi;
  
  	queue_work(priv->dev_workqueue, &work->work);
  }
  EXPORT_SYMBOL(ieee802154_rx_irqsafe);