net/nfc/af_nfc.c

/*
 * Copyright (C) 2011 Instituto Nokia de Tecnologia
 *
 * Authors:
 *    Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
 *    Lauro Ramos Venancio <lauro.venancio@openbossa.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

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

#include "nfc.h"

static DEFINE_RWLOCK(proto_tab_lock);
static const struct nfc_protocol *proto_tab[NFC_SOCKPROTO_MAX];

static int nfc_sock_create(struct net *net, struct socket *sock, int proto,
			   int kern)
{
	int rc = -EPROTONOSUPPORT;

	if (net != &init_net)
		return -EAFNOSUPPORT;

	if (proto < 0 || proto >= NFC_SOCKPROTO_MAX)
		return -EINVAL;

	read_lock(&proto_tab_lock);
	if (proto_tab[proto] &&	try_module_get(proto_tab[proto]->owner)) {
		rc = proto_tab[proto]->create(net, sock, proto_tab[proto], kern);
		module_put(proto_tab[proto]->owner);
	}
	read_unlock(&proto_tab_lock);

	return rc;
}

static const struct net_proto_family nfc_sock_family_ops = {
	.owner  = THIS_MODULE,
	.family = PF_NFC,
	.create = nfc_sock_create,
};

int nfc_proto_register(const struct nfc_protocol *nfc_proto)
{
	int rc;

	if (nfc_proto->id < 0 || nfc_proto->id >= NFC_SOCKPROTO_MAX)
		return -EINVAL;

	rc = proto_register(nfc_proto->proto, 0);
	if (rc)
		return rc;

	write_lock(&proto_tab_lock);
	if (proto_tab[nfc_proto->id])
		rc = -EBUSY;
	else
		proto_tab[nfc_proto->id] = nfc_proto;
	write_unlock(&proto_tab_lock);

	if (rc)
		proto_unregister(nfc_proto->proto);

	return rc;
}
EXPORT_SYMBOL(nfc_proto_register);

void nfc_proto_unregister(const struct nfc_protocol *nfc_proto)
{
	write_lock(&proto_tab_lock);
	proto_tab[nfc_proto->id] = NULL;
	write_unlock(&proto_tab_lock);

	proto_unregister(nfc_proto->proto);
}
EXPORT_SYMBOL(nfc_proto_unregister);

int __init af_nfc_init(void)
{
	return sock_register(&nfc_sock_family_ops);
}

void af_nfc_exit(void)
{
	sock_unregister(PF_NFC);
}