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, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include <linux/nfc.h>
  23 #include <linux/module.h>
  24
  25 #include "nfc.h"
  26
  27 static DEFINE_RWLOCK(proto_tab_lock);
  28 static const struct nfc_protocol *proto_tab[NFC_SOCKPROTO_MAX];
  29
  30 static int nfc_sock_create(struct net *net, struct socket *sock, int proto,
  31                            int kern)
  32 {
  33         int rc = -EPROTONOSUPPORT;
  34
  35         if (net != &init_net)
  36                 return -EAFNOSUPPORT;
  37
  38         if (proto < 0 || proto >= NFC_SOCKPROTO_MAX)
  39                 return -EINVAL;
  40
  41         read_lock(&proto_tab_lock);
  42         if (proto_tab[proto] && try_module_get(proto_tab[proto]->owner)) {
  43                 rc = proto_tab[proto]->create(net, sock, proto_tab[proto]);
  44                 module_put(proto_tab[proto]->owner);
  45         }
  46         read_unlock(&proto_tab_lock);
  47
  48         return rc;
  49 }
  50
  51 static struct net_proto_family nfc_sock_family_ops = {
  52         .owner  = THIS_MODULE,
  53         .family = PF_NFC,
  54         .create = nfc_sock_create,
  55 };
  56
  57 int nfc_proto_register(const struct nfc_protocol *nfc_proto)
  58 {
  59         int rc;
  60
  61         if (nfc_proto->id < 0 || nfc_proto->id >= NFC_SOCKPROTO_MAX)
  62                 return -EINVAL;
  63
  64         rc = proto_register(nfc_proto->proto, 0);
  65         if (rc)
  66                 return rc;
  67
  68         write_lock(&proto_tab_lock);
  69         if (proto_tab[nfc_proto->id])
  70                 rc = -EBUSY;
  71         else
  72                 proto_tab[nfc_proto->id] = nfc_proto;
  73         write_unlock(&proto_tab_lock);
  74
  75         return rc;
  76 }
  77 EXPORT_SYMBOL(nfc_proto_register);
  78
  79 void nfc_proto_unregister(const struct nfc_protocol *nfc_proto)
  80 {
  81         write_lock(&proto_tab_lock);
  82         proto_tab[nfc_proto->id] = NULL;
  83         write_unlock(&proto_tab_lock);
  84
  85         proto_unregister(nfc_proto->proto);
  86 }
  87 EXPORT_SYMBOL(nfc_proto_unregister);
  88
  89 int __init af_nfc_init(void)
  90 {
  91         return sock_register(&nfc_sock_family_ops);
  92 }
  93
  94 void af_nfc_exit(void)
  95 {
  96         sock_unregister(PF_NFC);
  97 }