Embedded Linux Experts

 * llc_output.c - LLC minimal output path
 * Copyright (c) 1997 by Procom Technology, Inc.
 * 		 2001-2003 by Arnaldo Carvalho de Melo <>
 * This program can be redistributed or modified under the terms of the
 * GNU General Public License version 2 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 version 2 for more details.

#include <linux/if_arp.h>
#include <linux/if_tr.h>
#include <linux/netdevice.h>
#include <linux/trdevice.h>
#include <linux/skbuff.h>
#include <net/llc.h>
#include <net/llc_pdu.h>

 *	llc_mac_hdr_init - fills MAC header fields
 *	@skb: Address of the frame to initialize its MAC header
 *	@sa: The MAC source address
 *	@da: The MAC destination address
 *	Fills MAC header fields, depending on MAC type. Returns 0, If MAC type
 *	is a valid type and initialization completes correctly 1, otherwise.
int llc_mac_hdr_init(struct sk_buff *skb, unsigned char *sa, unsigned char *da)
	int rc = 0;

	switch (skb->dev->type) {
#ifdef CONFIG_TR
	case ARPHRD_IEEE802_TR: {
		struct net_device *dev = skb->dev;
		struct trh_hdr *trh;
		skb->mac.raw = skb_push(skb, sizeof(*trh));
		trh = tr_hdr(skb);
		trh->ac = AC;
		trh->fc = LLC_FRAME;
		if (sa)
			memcpy(trh->saddr, sa, dev->addr_len);
			memset(trh->saddr, 0, dev->addr_len);
		if (da) {
			memcpy(trh->daddr, da, dev->addr_len);
			tr_source_route(skb, trh, dev);
			skb->mac.raw = skb->data;
		unsigned short len = skb->len;
		struct ethhdr *eth;

		skb->mac.raw = skb_push(skb, sizeof(*eth));
		eth = eth_hdr(skb);
		eth->h_proto = htons(len);
		memcpy(eth->h_dest, da, ETH_ALEN);
		memcpy(eth->h_source, sa, ETH_ALEN);
		printk(KERN_WARNING "device type not supported: %d\n",
		rc = -EINVAL;
	return rc;

 *	llc_build_and_send_ui_pkt - unitdata request interface for upper layers
 *	@sap: sap to use
 *	@skb: packet to send
 *	@dmac: destination mac address
 *	@dsap: destination sap
 *	Upper layers calls this function when upper layer wants to send data
 *	using connection-less mode communication (UI pdu).
 *	Accept data frame from network layer to be sent using connection-
 *	less mode communication; timeout/retries handled by network layer;
 *	package primitive as an event and send to SAP event handler
int llc_build_and_send_ui_pkt(struct llc_sap *sap, struct sk_buff *skb,
			      unsigned char *dmac, unsigned char dsap)
	int rc;
	llc_pdu_header_init(skb, LLC_PDU_TYPE_U, sap->laddr.lsap,
			    dsap, LLC_PDU_CMD);
	rc = llc_mac_hdr_init(skb, skb->dev->dev_addr, dmac);
	if (likely(!rc))
		rc = dev_queue_xmit(skb);
	return rc;