net/nfc/nci/data.c

   1 /*
   2  *  The NFC Controller Interface is the communication protocol between an
   3  *  NFC Controller (NFCC) and a Device Host (DH).
   4  *
   5  *  Copyright (C) 2011 Texas Instruments, Inc.
   6  *
   7  *  Written by Ilan Elias <ilane@ti.com>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2
  11  *  as published by the Free Software Foundation
  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 Free Software
  20  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  *
  22  */
  23
  24 #include <linux/types.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/wait.h>
  27 #include <linux/bitops.h>
  28 #include <linux/skbuff.h>
  29
  30 #include "../nfc.h"
  31 #include <net/nfc/nci.h>
  32 #include <net/nfc/nci_core.h>
  33 #include <linux/nfc.h>
  34
  35 /* Complete data exchange transaction and forward skb to nfc core */
  36 void nci_data_exchange_complete(struct nci_dev *ndev,
  37                                 struct sk_buff *skb,
  38                                 int err)
  39 {
  40         data_exchange_cb_t cb = ndev->data_exchange_cb;
  41         void *cb_context = ndev->data_exchange_cb_context;
  42
  43         nfc_dbg("entry, len %d, err %d", ((skb) ? (skb->len) : (0)), err);
  44
  45         if (cb) {
  46                 ndev->data_exchange_cb = NULL;
  47                 ndev->data_exchange_cb_context = 0;
  48
  49                 /* forward skb to nfc core */
  50                 cb(cb_context, skb, err);
  51         } else if (skb) {
  52                 nfc_err("no rx callback, dropping rx data...");
  53
  54                 /* no waiting callback, free skb */
  55                 kfree_skb(skb);
  56         }
  57
  58         clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
  59 }
  60
  61 /* ----------------- NCI TX Data ----------------- */
  62
  63 static inline void nci_push_data_hdr(struct nci_dev *ndev,
  64                                         __u8 conn_id,
  65                                         struct sk_buff *skb,
  66                                         __u8 pbf)
  67 {
  68         struct nci_data_hdr *hdr;
  69         int plen = skb->len;
  70
  71         hdr = (struct nci_data_hdr *) skb_push(skb, NCI_DATA_HDR_SIZE);
  72         hdr->conn_id = conn_id;
  73         hdr->rfu = 0;
  74         hdr->plen = plen;
  75
  76         nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
  77         nci_pbf_set((__u8 *)hdr, pbf);
  78
  79         skb->dev = (void *) ndev;
  80 }
  81
  82 static int nci_queue_tx_data_frags(struct nci_dev *ndev,
  83                                         __u8 conn_id,
  84                                         struct sk_buff *skb) {
  85         int total_len = skb->len;
  86         unsigned char *data = skb->data;
  87         unsigned long flags;
  88         struct sk_buff_head frags_q;
  89         struct sk_buff *skb_frag;
  90         int frag_len;
  91         int rc = 0;
  92
  93         nfc_dbg("entry, conn_id 0x%x, total_len %d", conn_id, total_len);
  94
  95         __skb_queue_head_init(&frags_q);
  96
  97         while (total_len) {
  98                 frag_len = min_t(int, total_len, ndev->max_pkt_payload_size);
  99
 100                 skb_frag = nci_skb_alloc(ndev,
 101                                         (NCI_DATA_HDR_SIZE + frag_len),
 102                                         GFP_KERNEL);
 103                 if (skb_frag == NULL) {
 104                         rc = -ENOMEM;
 105                         goto free_exit;
 106                 }
 107                 skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
 108
 109                 /* first, copy the data */
 110                 memcpy(skb_put(skb_frag, frag_len), data, frag_len);
 111
 112                 /* second, set the header */
 113                 nci_push_data_hdr(ndev, conn_id, skb_frag,
 114                 ((total_len == frag_len) ? (NCI_PBF_LAST) : (NCI_PBF_CONT)));
 115
 116                 __skb_queue_tail(&frags_q, skb_frag);
 117
 118                 data += frag_len;
 119                 total_len -= frag_len;
 120
 121                 nfc_dbg("frag_len %d, remaining total_len %d",
 122                         frag_len, total_len);
 123         }
 124
 125         /* queue all fragments atomically */
 126         spin_lock_irqsave(&ndev->tx_q.lock, flags);
 127
 128         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
 129                 __skb_queue_tail(&ndev->tx_q, skb_frag);
 130
 131         spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
 132
 133         /* free the original skb */
 134         kfree_skb(skb);
 135
 136         goto exit;
 137
 138 free_exit:
 139         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
 140                 kfree_skb(skb_frag);
 141
 142 exit:
 143         return rc;
 144 }
 145
 146 /* Send NCI data */
 147 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
 148 {
 149         int rc = 0;
 150
 151         nfc_dbg("entry, conn_id 0x%x, plen %d", conn_id, skb->len);
 152
 153         /* check if the packet need to be fragmented */
 154         if (skb->len <= ndev->max_pkt_payload_size) {
 155                 /* no need to fragment packet */
 156                 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
 157
 158                 skb_queue_tail(&ndev->tx_q, skb);
 159         } else {
 160                 /* fragment packet and queue the fragments */
 161                 rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
 162                 if (rc) {
 163                         nfc_err("failed to fragment tx data packet");
 164                         goto free_exit;
 165                 }
 166         }
 167
 168         queue_work(ndev->tx_wq, &ndev->tx_work);
 169
 170         goto exit;
 171
 172 free_exit:
 173         kfree_skb(skb);
 174
 175 exit:
 176         return rc;
 177 }
 178
 179 /* ----------------- NCI RX Data ----------------- */
 180
 181 static void nci_add_rx_data_frag(struct nci_dev *ndev,
 182                                 struct sk_buff *skb,
 183                                 __u8 pbf)
 184 {
 185         int reassembly_len;
 186         int err = 0;
 187
 188         if (ndev->rx_data_reassembly) {
 189                 reassembly_len = ndev->rx_data_reassembly->len;
 190
 191                 /* first, make enough room for the already accumulated data */
 192                 if (skb_cow_head(skb, reassembly_len)) {
 193                         nfc_err("error adding room for accumulated rx data");
 194
 195                         kfree_skb(skb);
 196                         skb = 0;
 197
 198                         kfree_skb(ndev->rx_data_reassembly);
 199                         ndev->rx_data_reassembly = 0;
 200
 201                         err = -ENOMEM;
 202                         goto exit;
 203                 }
 204
 205                 /* second, combine the two fragments */
 206                 memcpy(skb_push(skb, reassembly_len),
 207                                 ndev->rx_data_reassembly->data,
 208                                 reassembly_len);
 209
 210                 /* third, free old reassembly */
 211                 kfree_skb(ndev->rx_data_reassembly);
 212                 ndev->rx_data_reassembly = 0;
 213         }
 214
 215         if (pbf == NCI_PBF_CONT) {
 216                 /* need to wait for next fragment, store skb and exit */
 217                 ndev->rx_data_reassembly = skb;
 218                 return;
 219         }
 220
 221 exit:
 222         nci_data_exchange_complete(ndev, skb, err);
 223 }
 224
 225 /* Rx Data packet */
 226 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
 227 {
 228         __u8 pbf = nci_pbf(skb->data);
 229
 230         nfc_dbg("entry, len %d", skb->len);
 231
 232         nfc_dbg("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d",
 233                         nci_pbf(skb->data),
 234                         nci_conn_id(skb->data),
 235                         nci_plen(skb->data));
 236
 237         /* strip the nci data header */
 238         skb_pull(skb, NCI_DATA_HDR_SIZE);
 239
 240         if (ndev->target_active_prot == NFC_PROTO_MIFARE) {
 241                 /* frame I/F => remove the status byte */
 242                 nfc_dbg("NFC_PROTO_MIFARE => remove the status byte");
 243                 skb_trim(skb, (skb->len - 1));
 244         }
 245
 246         nci_add_rx_data_frag(ndev, skb, pbf);
 247 }