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, see <http://www.gnu.org/licenses/>.
  20  *
  21  */
  22
  23 #define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
  24
  25 #include <linux/types.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/wait.h>
  28 #include <linux/bitops.h>
  29 #include <linux/skbuff.h>
  30
  31 #include "../nfc.h"
  32 #include <net/nfc/nci.h>
  33 #include <net/nfc/nci_core.h>
  34 #include <linux/nfc.h>
  35
  36 /* Complete data exchange transaction and forward skb to nfc core */
  37 void nci_data_exchange_complete(struct nci_dev *ndev, 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         pr_debug("len %d, err %d\n", skb ? skb->len : 0, err);
  44
  45         /* data exchange is complete, stop the data timer */
  46         del_timer_sync(&ndev->data_timer);
  47         clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags);
  48
  49         if (cb) {
  50                 ndev->data_exchange_cb = NULL;
  51                 ndev->data_exchange_cb_context = NULL;
  52
  53                 /* forward skb to nfc core */
  54                 cb(cb_context, skb, err);
  55         } else if (skb) {
  56                 pr_err("no rx callback, dropping rx data...\n");
  57
  58                 /* no waiting callback, free skb */
  59                 kfree_skb(skb);
  60         }
  61
  62         clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
  63 }
  64
  65 /* ----------------- NCI TX Data ----------------- */
  66
  67 static inline void nci_push_data_hdr(struct nci_dev *ndev,
  68                                      __u8 conn_id,
  69                                      struct sk_buff *skb,
  70                                      __u8 pbf)
  71 {
  72         struct nci_data_hdr *hdr;
  73         int plen = skb->len;
  74
  75         hdr = (struct nci_data_hdr *) skb_push(skb, NCI_DATA_HDR_SIZE);
  76         hdr->conn_id = conn_id;
  77         hdr->rfu = 0;
  78         hdr->plen = plen;
  79
  80         nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
  81         nci_pbf_set((__u8 *)hdr, pbf);
  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) ?
 118                                    (NCI_PBF_LAST) : (NCI_PBF_CONT)));
 119
 120                 __skb_queue_tail(&frags_q, skb_frag);
 121
 122                 data += frag_len;
 123                 total_len -= frag_len;
 124
 125                 pr_debug("frag_len %d, remaining total_len %d\n",
 126                          frag_len, total_len);
 127         }
 128
 129         /* queue all fragments atomically */
 130         spin_lock_irqsave(&ndev->tx_q.lock, flags);
 131
 132         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
 133                 __skb_queue_tail(&ndev->tx_q, skb_frag);
 134
 135         spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
 136
 137         /* free the original skb */
 138         kfree_skb(skb);
 139
 140         goto exit;
 141
 142 free_exit:
 143         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
 144                 kfree_skb(skb_frag);
 145
 146 exit:
 147         return rc;
 148 }
 149
 150 /* Send NCI data */
 151 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
 152 {
 153         int rc = 0;
 154
 155         pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len);
 156
 157         /* check if the packet need to be fragmented */
 158         if (skb->len <= ndev->max_data_pkt_payload_size) {
 159                 /* no need to fragment packet */
 160                 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
 161
 162                 skb_queue_tail(&ndev->tx_q, skb);
 163         } else {
 164                 /* fragment packet and queue the fragments */
 165                 rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
 166                 if (rc) {
 167                         pr_err("failed to fragment tx data packet\n");
 168                         goto free_exit;
 169                 }
 170         }
 171
 172         queue_work(ndev->tx_wq, &ndev->tx_work);
 173
 174         goto exit;
 175
 176 free_exit:
 177         kfree_skb(skb);
 178
 179 exit:
 180         return rc;
 181 }
 182
 183 /* ----------------- NCI RX Data ----------------- */
 184
 185 static void nci_add_rx_data_frag(struct nci_dev *ndev,
 186                                  struct sk_buff *skb,
 187                                  __u8 pbf)
 188 {
 189         int reassembly_len;
 190         int err = 0;
 191
 192         if (ndev->rx_data_reassembly) {
 193                 reassembly_len = ndev->rx_data_reassembly->len;
 194
 195                 /* first, make enough room for the already accumulated data */
 196                 if (skb_cow_head(skb, reassembly_len)) {
 197                         pr_err("error adding room for accumulated rx data\n");
 198
 199                         kfree_skb(skb);
 200                         skb = NULL;
 201
 202                         kfree_skb(ndev->rx_data_reassembly);
 203                         ndev->rx_data_reassembly = NULL;
 204
 205                         err = -ENOMEM;
 206                         goto exit;
 207                 }
 208
 209                 /* second, combine the two fragments */
 210                 memcpy(skb_push(skb, reassembly_len),
 211                        ndev->rx_data_reassembly->data,
 212                        reassembly_len);
 213
 214                 /* third, free old reassembly */
 215                 kfree_skb(ndev->rx_data_reassembly);
 216                 ndev->rx_data_reassembly = NULL;
 217         }
 218
 219         if (pbf == NCI_PBF_CONT) {
 220                 /* need to wait for next fragment, store skb and exit */
 221                 ndev->rx_data_reassembly = skb;
 222                 return;
 223         }
 224
 225 exit:
 226         nci_data_exchange_complete(ndev, skb, err);
 227 }
 228
 229 /* Rx Data packet */
 230 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
 231 {
 232         __u8 pbf = nci_pbf(skb->data);
 233
 234         pr_debug("len %d\n", skb->len);
 235
 236         pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
 237                  nci_pbf(skb->data),
 238                  nci_conn_id(skb->data),
 239                  nci_plen(skb->data));
 240
 241         /* strip the nci data header */
 242         skb_pull(skb, NCI_DATA_HDR_SIZE);
 243
 244         if (ndev->target_active_prot == NFC_PROTO_MIFARE) {
 245                 /* frame I/F => remove the status byte */
 246                 pr_debug("NFC_PROTO_MIFARE => remove the status byte\n");
 247                 skb_trim(skb, (skb->len - 1));
 248         }
 249
 250         nci_add_rx_data_frag(ndev, skb, pbf);
 251 }