/*
   * Copyright 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:
   * Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
   * Sergey Lapin <slapin@ossfans.org>
   * Maxim Gorbachyov <maxim.gorbachev@siemens.com>
   * Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
   */
  
  #include <linux/netdevice.h>
  #include <linux/if_arp.h>
  #include <linux/crc-ccitt.h>
  
  #include <net/ieee802154_netdev.h>
  #include <net/mac802154.h>
  #include <net/wpan-phy.h>
  
  #include "mac802154.h"
  
  /* IEEE 802.15.4 transceivers can sleep during the xmit session, so process
   * packets through the workqueue.
   */
  struct xmit_work {
  	struct sk_buff *skb;
  	struct work_struct work;
  	struct mac802154_priv *priv;
  	u8 chan;
  	u8 page;
  };
  
  static void mac802154_xmit_worker(struct work_struct *work)
  {
  	struct xmit_work *xw = container_of(work, struct xmit_work, work);
  	struct mac802154_sub_if_data *sdata;
  	int res;
  
  	mutex_lock(&xw->priv->phy->pib_lock);
  	if (xw->priv->phy->current_channel != xw->chan ||
  	    xw->priv->phy->current_page != xw->page) {
  		res = xw->priv->ops->set_channel(&xw->priv->hw,
  						  xw->page,
  						  xw->chan);
  		if (res) {
  			pr_debug("set_channel failed
  ");
  			goto out;
  		}
  
  		xw->priv->phy->current_channel = xw->chan;
  		xw->priv->phy->current_page = xw->page;
  	}
  
  	res = xw->priv->ops->xmit(&xw->priv->hw, xw->skb);
  	if (res)
  		pr_debug("transmission failed
  ");
  
  out:
  	mutex_unlock(&xw->priv->phy->pib_lock);
  
  	/* Restart the netif queue on each sub_if_data object. */
  	rcu_read_lock();
  	list_for_each_entry_rcu(sdata, &xw->priv->slaves, list)
  		netif_wake_queue(sdata->dev);
  	rcu_read_unlock();
  
  	dev_kfree_skb(xw->skb);
  
  	kfree(xw);
  }
  
  netdev_tx_t mac802154_tx(struct mac802154_priv *priv, struct sk_buff *skb,
  			 u8 page, u8 chan)
  {
  	struct xmit_work *work;
  	struct mac802154_sub_if_data *sdata;
  
  	if (!(priv->phy->channels_supported[page] & (1 << chan))) {
  		WARN_ON(1);
  		kfree_skb(skb);
  		return NETDEV_TX_OK;
  	}
  
  	mac802154_monitors_rx(mac802154_to_priv(&priv->hw), skb);
  
  	if (!(priv->hw.flags & IEEE802154_HW_OMIT_CKSUM)) {
  		u16 crc = crc_ccitt(0, skb->data, skb->len);
  		u8 *data = skb_put(skb, 2);
  		data[0] = crc & 0xff;
  		data[1] = crc >> 8;
  	}
  
  	if (skb_cow_head(skb, priv->hw.extra_tx_headroom)) {
  		kfree_skb(skb);
  		return NETDEV_TX_OK;
  	}
  
  	work = kzalloc(sizeof(struct xmit_work), GFP_ATOMIC);
  	if (!work) {
  		kfree_skb(skb);
  		return NETDEV_TX_BUSY;
  	}
  
  	/* Stop the netif queue on each sub_if_data object. */
  	rcu_read_lock();
  	list_for_each_entry_rcu(sdata, &priv->slaves, list)
  		netif_stop_queue(sdata->dev);
  	rcu_read_unlock();
  
  	INIT_WORK(&work->work, mac802154_xmit_worker);
  	work->skb = skb;
  	work->priv = priv;
  	work->page = page;
  	work->chan = chan;
  
  	queue_work(priv->dev_workqueue, &work->work);
  
  	return NETDEV_TX_OK;
  }