net/nfc/af_nfc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2011 Instituto Nokia de Tecnologia
   4  *
   5  * Authors:
   6  *    Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
   7  *    Lauro Ramos Venancio <lauro.venancio@openbossa.org>
   8  */
   9
  10 #include <linux/nfc.h>
  11 #include <linux/module.h>
  12
  13 #include "nfc.h"
  14
  15 static DEFINE_RWLOCK(proto_tab_lock);
  16 static const struct nfc_protocol *proto_tab[NFC_SOCKPROTO_MAX];
  17
  18 static int nfc_sock_create(struct net *net, struct socket *sock, int proto,
  19                            int kern)
  20 {
  21         int rc = -EPROTONOSUPPORT;
  22
  23         if (net != &init_net)
  24                 return -EAFNOSUPPORT;
  25
  26         if (proto < 0 || proto >= NFC_SOCKPROTO_MAX)
  27                 return -EINVAL;
  28
  29         read_lock(&proto_tab_lock);
  30         if (proto_tab[proto] && try_module_get(proto_tab[proto]->owner)) {
  31                 rc = proto_tab[proto]->create(net, sock, proto_tab[proto], kern);
  32                 module_put(proto_tab[proto]->owner);
  33         }
  34         read_unlock(&proto_tab_lock);
  35
  36         return rc;
  37 }
  38
  39 static const struct net_proto_family nfc_sock_family_ops = {
  40         .owner  = THIS_MODULE,
  41         .family = PF_NFC,
  42         .create = nfc_sock_create,
  43 };
  44
  45 int nfc_proto_register(const struct nfc_protocol *nfc_proto)
  46 {
  47         int rc;
  48
  49         if (nfc_proto->id < 0 || nfc_proto->id >= NFC_SOCKPROTO_MAX)
  50                 return -EINVAL;
  51
  52         rc = proto_register(nfc_proto->proto, 0);
  53         if (rc)
  54                 return rc;
  55
  56         write_lock(&proto_tab_lock);
  57         if (proto_tab[nfc_proto->id])
  58                 rc = -EBUSY;
  59         else
  60                 proto_tab[nfc_proto->id] = nfc_proto;
  61         write_unlock(&proto_tab_lock);
  62
  63         if (rc)
  64                 proto_unregister(nfc_proto->proto);
  65
  66         return rc;
  67 }
  68 EXPORT_SYMBOL(nfc_proto_register);
  69
  70 void nfc_proto_unregister(const struct nfc_protocol *nfc_proto)
  71 {
  72         write_lock(&proto_tab_lock);
  73         proto_tab[nfc_proto->id] = NULL;
  74         write_unlock(&proto_tab_lock);
  75
  76         proto_unregister(nfc_proto->proto);
  77 }
  78 EXPORT_SYMBOL(nfc_proto_unregister);
  79
  80 int __init af_nfc_init(void)
  81 {
  82         return sock_register(&nfc_sock_family_ops);
  83 }
  84
  85 void __exit af_nfc_exit(void)
  86 {
  87         sock_unregister(PF_NFC);
  88 }