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 #define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
  25
  26 #include <linux/types.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/wait.h>
  29 #include <linux/bitops.h>
  30 #include <linux/skbuff.h>
  31
  32 #include "../nfc.h"
  33 #include <net/nfc/nci.h>
  34 #include <net/nfc/nci_core.h>
  35 #include <linux/nfc.h>
  36
  37 /* Complete data exchange transaction and forward skb to nfc core */
  38 void nci_data_exchange_complete(struct nci_dev *ndev,
  39                                 struct sk_buff *skb,
  40                                 int err)
  41 {
  42         data_exchange_cb_t cb = ndev->data_exchange_cb;
  43         void *cb_context = ndev->data_exchange_cb_context;
  44
  45         pr_debug("len %d, err %d\n", skb ? skb->len : 0, err);
  46
  47         if (cb) {
  48                 ndev->data_exchange_cb = NULL;
  49                 ndev->data_exchange_cb_context = 0;
  50
  51                 /* forward skb to nfc core */
  52                 cb(cb_context, skb, err);
  53         } else if (skb) {
  54                 pr_err("no rx callback, dropping rx data...\n");
  55
  56                 /* no waiting callback, free skb */
  57                 kfree_skb(skb);
  58         }
  59
  60         clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
  61 }
  62
  63 /* ----------------- NCI TX Data ----------------- */
  64
  65 static inline void nci_push_data_hdr(struct nci_dev *ndev,
  66                                         __u8 conn_id,
  67                                         struct sk_buff *skb,
  68                                         __u8 pbf)
  69 {
  70         struct nci_data_hdr *hdr;
  71         int plen = skb->len;
  72
  73         hdr = (struct nci_data_hdr *) skb_push(skb, NCI_DATA_HDR_SIZE);
  74         hdr->conn_id = conn_id;
  75         hdr->rfu = 0;
  76         hdr->plen = plen;
  77
  78         nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
  79         nci_pbf_set((__u8 *)hdr, pbf);
  80
  81         skb->dev = (void *) ndev;
  82 }
  83
  84 static int nci_queue_tx_data_frags(struct nci_dev *ndev,
  85                                         __u8 conn_id,
  86                                         struct sk_buff *skb) {
  87         int total_len = skb->len;
  88         unsigned char *data = skb->data;
  89         unsigned long flags;
  90         struct sk_buff_head frags_q;
  91         struct sk_buff *skb_frag;
  92         int frag_len;
  93         int rc = 0;
  94
  95         pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len);
  96
  97         __skb_queue_head_init(&frags_q);
  98
  99         while (total_len) {
 100                 frag_len =
 101                         min_t(int, total_len, ndev->max_data_pkt_payload_size);
 102
 103                 skb_frag = nci_skb_alloc(ndev,
 104                                         (NCI_DATA_HDR_SIZE + frag_len),
 105                                         GFP_KERNEL);
 106                 if (skb_frag == NULL) {
 107                         rc = -ENOMEM;
 108                         goto free_exit;
 109                 }
 110                 skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
 111
 112                 /* first, copy the data */
 113                 memcpy(skb_put(skb_frag, frag_len), data, frag_len);
 114
 115                 /* second, set the header */
 116                 nci_push_data_hdr(ndev, conn_id, skb_frag,
 117                 ((total_len == frag_len) ? (NCI_PBF_LAST) : (NCI_PBF_CONT)));
 118
 119                 __skb_queue_tail(&frags_q, skb_frag);
 120
 121                 data += frag_len;
 122                 total_len -= frag_len;
 123
 124                 pr_debug("frag_len %d, remaining total_len %d\n",
 125                          frag_len, total_len);
 126         }
 127
 128         /* queue all fragments atomically */
 129         spin_lock_irqsave(&ndev->tx_q.lock, flags);
 130
 131         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
 132                 __skb_queue_tail(&ndev->tx_q, skb_frag);
 133
 134         spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
 135
 136         /* free the original skb */
 137         kfree_skb(skb);
 138
 139         goto exit;
 140
 141 free_exit:
 142         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
 143                 kfree_skb(skb_frag);
 144
 145 exit:
 146         return rc;
 147 }
 148
 149 /* Send NCI data */
 150 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
 151 {
 152         int rc = 0;
 153
 154         pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len);
 155
 156         /* check if the packet need to be fragmented */
 157         if (skb->len <= ndev->max_data_pkt_payload_size) {
 158                 /* no need to fragment packet */
 159                 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
 160
 161                 skb_queue_tail(&ndev->tx_q, skb);
 162         } else {
 163                 /* fragment packet and queue the fragments */
 164                 rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
 165                 if (rc) {
 166                         pr_err("failed to fragment tx data packet\n");
 167                         goto free_exit;
 168                 }
 169         }
 170
 171         queue_work(ndev->tx_wq, &ndev->tx_work);
 172
 173         goto exit;
 174
 175 free_exit:
 176         kfree_skb(skb);
 177
 178 exit:
 179         return rc;
 180 }
 181
 182 /* ----------------- NCI RX Data ----------------- */
 183
 184 static void nci_add_rx_data_frag(struct nci_dev *ndev,
 185                                 struct sk_buff *skb,
 186                                 __u8 pbf)
 187 {
 188         int reassembly_len;
 189         int err = 0;
 190
 191         if (ndev->rx_data_reassembly) {
 192                 reassembly_len = ndev->rx_data_reassembly->len;
 193
 194                 /* first, make enough room for the already accumulated data */
 195                 if (skb_cow_head(skb, reassembly_len)) {
 196                         pr_err("error adding room for accumulated rx data\n");
 197
 198                         kfree_skb(skb);
 199                         skb = 0;
 200
 201                         kfree_skb(ndev->rx_data_reassembly);
 202                         ndev->rx_data_reassembly = 0;
 203
 204                         err = -ENOMEM;
 205                         goto exit;
 206                 }
 207
 208                 /* second, combine the two fragments */
 209                 memcpy(skb_push(skb, reassembly_len),
 210                                 ndev->rx_data_reassembly->data,
 211                                 reassembly_len);
 212
 213                 /* third, free old reassembly */
 214                 kfree_skb(ndev->rx_data_reassembly);
 215                 ndev->rx_data_reassembly = 0;
 216         }
 217
 218         if (pbf == NCI_PBF_CONT) {
 219                 /* need to wait for next fragment, store skb and exit */
 220                 ndev->rx_data_reassembly = skb;
 221                 return;
 222         }
 223
 224 exit:
 225         nci_data_exchange_complete(ndev, skb, err);
 226 }
 227
 228 /* Rx Data packet */
 229 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
 230 {
 231         __u8 pbf = nci_pbf(skb->data);
 232
 233         pr_debug("len %d\n", skb->len);
 234
 235         pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
 236                  nci_pbf(skb->data),
 237                  nci_conn_id(skb->data),
 238                  nci_plen(skb->data));
 239
 240         /* strip the nci data header */
 241         skb_pull(skb, NCI_DATA_HDR_SIZE);
 242
 243         if (ndev->target_active_prot == NFC_PROTO_MIFARE) {
 244                 /* frame I/F => remove the status byte */
 245                 pr_debug("NFC_PROTO_MIFARE => remove the status byte\n");
 246                 skb_trim(skb, (skb->len - 1));
 247         }
 248
 249         nci_add_rx_data_frag(ndev, skb, pbf);
 250 }