net/nfc/af_nfc.c

   1 /*
   2  * Copyright (C) 2011 Instituto Nokia de Tecnologia
   3  *
   4  * Authors:
   5  *    Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
   6  *    Lauro Ramos Venancio <lauro.venancio@openbossa.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the
  20  * Free Software Foundation, Inc.,
  21  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  22  */
  23
  24 #include <linux/nfc.h>
  25 #include <linux/module.h>
  26
  27 #include "nfc.h"
  28
  29 static DEFINE_RWLOCK(proto_tab_lock);
  30 static const struct nfc_protocol *proto_tab[NFC_SOCKPROTO_MAX];
  31
  32 static int nfc_sock_create(struct net *net, struct socket *sock, int proto,
  33                            int kern)
  34 {
  35         int rc = -EPROTONOSUPPORT;
  36
  37         if (net != &init_net)
  38                 return -EAFNOSUPPORT;
  39
  40         if (proto < 0 || proto >= NFC_SOCKPROTO_MAX)
  41                 return -EINVAL;
  42
  43         read_lock(&proto_tab_lock);
  44         if (proto_tab[proto] && try_module_get(proto_tab[proto]->owner)) {
  45                 rc = proto_tab[proto]->create(net, sock, proto_tab[proto]);
  46                 module_put(proto_tab[proto]->owner);
  47         }
  48         read_unlock(&proto_tab_lock);
  49
  50         return rc;
  51 }
  52
  53 static struct net_proto_family nfc_sock_family_ops = {
  54         .owner  = THIS_MODULE,
  55         .family = PF_NFC,
  56         .create = nfc_sock_create,
  57 };
  58
  59 int nfc_proto_register(const struct nfc_protocol *nfc_proto)
  60 {
  61         int rc;
  62
  63         if (nfc_proto->id < 0 || nfc_proto->id >= NFC_SOCKPROTO_MAX)
  64                 return -EINVAL;
  65
  66         rc = proto_register(nfc_proto->proto, 0);
  67         if (rc)
  68                 return rc;
  69
  70         write_lock(&proto_tab_lock);
  71         if (proto_tab[nfc_proto->id])
  72                 rc = -EBUSY;
  73         else
  74                 proto_tab[nfc_proto->id] = nfc_proto;
  75         write_unlock(&proto_tab_lock);
  76
  77         return rc;
  78 }
  79 EXPORT_SYMBOL(nfc_proto_register);
  80
  81 void nfc_proto_unregister(const struct nfc_protocol *nfc_proto)
  82 {
  83         write_lock(&proto_tab_lock);
  84         proto_tab[nfc_proto->id] = NULL;
  85         write_unlock(&proto_tab_lock);
  86
  87         proto_unregister(nfc_proto->proto);
  88 }
  89 EXPORT_SYMBOL(nfc_proto_unregister);
  90
  91 int __init af_nfc_init(void)
  92 {
  93         return sock_register(&nfc_sock_family_ops);
  94 }
  95
  96 void af_nfc_exit(void)
  97 {
  98         sock_unregister(PF_NFC);
  99 }