/*
   * Generic HDLC support routines for Linux
   * HDLC Ethernet emulation support
   *

   * Copyright (C) 2002-2006 Krzysztof Halasa <khc@pm.waw.pl>

   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of version 2 of the GNU General Public License
   * as published by the Free Software Foundation.
   */

  #include <linux/errno.h>

  #include <linux/etherdevice.h>

  #include <linux/gfp.h>

  #include <linux/hdlc.h>

  #include <linux/if_arp.h>

  #include <linux/inetdevice.h>

  #include <linux/init.h>

  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/pkt_sched.h>

  #include <linux/poll.h>

  #include <linux/rtnetlink.h>

  #include <linux/skbuff.h>

  static int raw_eth_ioctl(struct net_device *dev, struct ifreq *ifr);

  static netdev_tx_t eth_tx(struct sk_buff *skb, struct net_device *dev)

  {
  	int pad = ETH_ZLEN - skb->len;
  	if (pad > 0) {		/* Pad the frame with zeros */
  		int len = skb->len;
  		if (skb_tailroom(skb) < pad)
  			if (pskb_expand_head(skb, 0, pad, GFP_ATOMIC)) {

  				dev->stats.tx_dropped++;

  				dev_kfree_skb(skb);
  				return 0;
  			}
  		skb_put(skb, pad);
  		memset(skb->data + len, 0, pad);
  	}
  	return dev_to_hdlc(dev)->xmit(skb, dev);
  }

  static struct hdlc_proto proto = {
  	.type_trans	= eth_type_trans,

  	.xmit		= eth_tx,

  	.ioctl		= raw_eth_ioctl,
  	.module		= THIS_MODULE,
  };
  
  
  static int raw_eth_ioctl(struct net_device *dev, struct ifreq *ifr)

  {
  	raw_hdlc_proto __user *raw_s = ifr->ifr_settings.ifs_ifsu.raw_hdlc;
  	const size_t size = sizeof(raw_hdlc_proto);
  	raw_hdlc_proto new_settings;
  	hdlc_device *hdlc = dev_to_hdlc(dev);

  	int result, old_qlen;

  
  	switch (ifr->ifr_settings.type) {
  	case IF_GET_PROTO:

  		if (dev_to_hdlc(dev)->proto != &proto)
  			return -EINVAL;

  		ifr->ifr_settings.type = IF_PROTO_HDLC_ETH;
  		if (ifr->ifr_settings.size < size) {
  			ifr->ifr_settings.size = size; /* data size wanted */
  			return -ENOBUFS;
  		}

  		if (copy_to_user(raw_s, hdlc->state, size))

  			return -EFAULT;
  		return 0;
  
  	case IF_PROTO_HDLC_ETH:
  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;
  
  		if (dev->flags & IFF_UP)
  			return -EBUSY;
  
  		if (copy_from_user(&new_settings, raw_s, size))
  			return -EFAULT;
  
  		if (new_settings.encoding == ENCODING_DEFAULT)
  			new_settings.encoding = ENCODING_NRZ;
  
  		if (new_settings.parity == PARITY_DEFAULT)
  			new_settings.parity = PARITY_CRC16_PR1_CCITT;
  
  		result = hdlc->attach(dev, new_settings.encoding,
  				      new_settings.parity);
  		if (result)
  			return result;

  		result = attach_hdlc_protocol(dev, &proto,

  					      sizeof(raw_hdlc_proto));
  		if (result)
  			return result;
  		memcpy(hdlc->state, &new_settings, size);

  		old_qlen = dev->tx_queue_len;
  		ether_setup(dev);

  		dev->tx_queue_len = old_qlen;

  		eth_hw_addr_random(dev);

  		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);

  		netif_dormant_off(dev);

  		return 0;
  	}
  
  	return -EINVAL;
  }

  
  
  static int __init mod_init(void)
  {
  	register_hdlc_protocol(&proto);
  	return 0;
  }
  
  
  
  static void __exit mod_exit(void)
  {
  	unregister_hdlc_protocol(&proto);
  }
  
  
  module_init(mod_init);
  module_exit(mod_exit);
  
  MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
  MODULE_DESCRIPTION("Ethernet encapsulation support for generic HDLC");
  MODULE_LICENSE("GPL v2");