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, struct sk_buff *skb,
  39                                 int err)
  40 {
  41         data_exchange_cb_t cb = ndev->data_exchange_cb;
  42         void *cb_context = ndev->data_exchange_cb_context;
  43
  44         pr_debug("len %d, err %d\n", skb ? skb->len : 0, err);
  45
  46         /* data exchange is complete, stop the data timer */
  47         del_timer_sync(&ndev->data_timer);
  48         clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags);
  49
  50         if (cb) {
  51                 ndev->data_exchange_cb = NULL;
  52                 ndev->data_exchange_cb_context = NULL;
  53
  54                 /* forward skb to nfc core */
  55                 cb(cb_context, skb, err);
  56         } else if (skb) {
  57                 pr_err("no rx callback, dropping rx data...\n");
  58
  59                 /* no waiting callback, free skb */
  60                 kfree_skb(skb);
  61         }
  62
  63         clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
  64 }
  65
  66 /* ----------------- NCI TX Data ----------------- */
  67
  68 static inline void nci_push_data_hdr(struct nci_dev *ndev,
  69                                      __u8 conn_id,
  70                                      struct sk_buff *skb,
  71                                      __u8 pbf)
  72 {
  73         struct nci_data_hdr *hdr;
  74         int plen = skb->len;
  75
  76         hdr = (struct nci_data_hdr *) skb_push(skb, NCI_DATA_HDR_SIZE);
  77         hdr->conn_id = conn_id;
  78         hdr->rfu = 0;
  79         hdr->plen = plen;
  80
  81         nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
  82         nci_pbf_set((__u8 *)hdr, pbf);
  83 }
  84
  85 static int nci_queue_tx_data_frags(struct nci_dev *ndev,
  86                                    __u8 conn_id,
  87                                    struct sk_buff *skb) {
  88         int total_len = skb->len;
  89         unsigned char *data = skb->data;
  90         unsigned long flags;
  91         struct sk_buff_head frags_q;
  92         struct sk_buff *skb_frag;
  93         int frag_len;
  94         int rc = 0;
  95
  96         pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len);
  97
  98         __skb_queue_head_init(&frags_q);
  99
 100         while (total_len) {
 101                 frag_len =
 102                         min_t(int, total_len, ndev->max_data_pkt_payload_size);
 103
 104                 skb_frag = nci_skb_alloc(ndev,
 105                                          (NCI_DATA_HDR_SIZE + frag_len),
 106                                          GFP_KERNEL);
 107                 if (skb_frag == NULL) {
 108                         rc = -ENOMEM;
 109                         goto free_exit;
 110                 }
 111                 skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
 112
 113                 /* first, copy the data */
 114                 memcpy(skb_put(skb_frag, frag_len), data, frag_len);
 115
 116                 /* second, set the header */
 117                 nci_push_data_hdr(ndev, conn_id, skb_frag,
 118                                   ((total_len == frag_len) ?
 119                                    (NCI_PBF_LAST) : (NCI_PBF_CONT)));
 120
 121                 __skb_queue_tail(&frags_q, skb_frag);
 122
 123                 data += frag_len;
 124                 total_len -= frag_len;
 125
 126                 pr_debug("frag_len %d, remaining total_len %d\n",
 127                          frag_len, total_len);
 128         }
 129
 130         /* queue all fragments atomically */
 131         spin_lock_irqsave(&ndev->tx_q.lock, flags);
 132
 133         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
 134                 __skb_queue_tail(&ndev->tx_q, skb_frag);
 135
 136         spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
 137
 138         /* free the original skb */
 139         kfree_skb(skb);
 140
 141         goto exit;
 142
 143 free_exit:
 144         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
 145                 kfree_skb(skb_frag);
 146
 147 exit:
 148         return rc;
 149 }
 150
 151 /* Send NCI data */
 152 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
 153 {
 154         int rc = 0;
 155
 156         pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len);
 157
 158         /* check if the packet need to be fragmented */
 159         if (skb->len <= ndev->max_data_pkt_payload_size) {
 160                 /* no need to fragment packet */
 161                 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
 162
 163                 skb_queue_tail(&ndev->tx_q, skb);
 164         } else {
 165                 /* fragment packet and queue the fragments */
 166                 rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
 167                 if (rc) {
 168                         pr_err("failed to fragment tx data packet\n");
 169                         goto free_exit;
 170                 }
 171         }
 172
 173         queue_work(ndev->tx_wq, &ndev->tx_work);
 174
 175         goto exit;
 176
 177 free_exit:
 178         kfree_skb(skb);
 179
 180 exit:
 181         return rc;
 182 }
 183
 184 /* ----------------- NCI RX Data ----------------- */
 185
 186 static void nci_add_rx_data_frag(struct nci_dev *ndev,
 187                                  struct sk_buff *skb,
 188                                  __u8 pbf)
 189 {
 190         int reassembly_len;
 191         int err = 0;
 192
 193         if (ndev->rx_data_reassembly) {
 194                 reassembly_len = ndev->rx_data_reassembly->len;
 195
 196                 /* first, make enough room for the already accumulated data */
 197                 if (skb_cow_head(skb, reassembly_len)) {
 198                         pr_err("error adding room for accumulated rx data\n");
 199
 200                         kfree_skb(skb);
 201                         skb = NULL;
 202
 203                         kfree_skb(ndev->rx_data_reassembly);
 204                         ndev->rx_data_reassembly = NULL;
 205
 206                         err = -ENOMEM;
 207                         goto exit;
 208                 }
 209
 210                 /* second, combine the two fragments */
 211                 memcpy(skb_push(skb, reassembly_len),
 212                        ndev->rx_data_reassembly->data,
 213                        reassembly_len);
 214
 215                 /* third, free old reassembly */
 216                 kfree_skb(ndev->rx_data_reassembly);
 217                 ndev->rx_data_reassembly = NULL;
 218         }
 219
 220         if (pbf == NCI_PBF_CONT) {
 221                 /* need to wait for next fragment, store skb and exit */
 222                 ndev->rx_data_reassembly = skb;
 223                 return;
 224         }
 225
 226 exit:
 227         nci_data_exchange_complete(ndev, skb, err);
 228 }
 229
 230 /* Rx Data packet */
 231 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
 232 {
 233         __u8 pbf = nci_pbf(skb->data);
 234
 235         pr_debug("len %d\n", skb->len);
 236
 237         pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
 238                  nci_pbf(skb->data),
 239                  nci_conn_id(skb->data),
 240                  nci_plen(skb->data));
 241
 242         /* strip the nci data header */
 243         skb_pull(skb, NCI_DATA_HDR_SIZE);
 244
 245         if (ndev->target_active_prot == NFC_PROTO_MIFARE) {
 246                 /* frame I/F => remove the status byte */
 247                 pr_debug("NFC_PROTO_MIFARE => remove the status byte\n");
 248                 skb_trim(skb, (skb->len - 1));
 249         }
 250
 251         nci_add_rx_data_frag(ndev, skb, pbf);
 252 }