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Linux/net/nfc/nci/data.c

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  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  *  Copyright (C) 2014 Marvell International Ltd.
  7  *
  8  *  Written by Ilan Elias <ilane@ti.com>
  9  *
 10  *  This program is free software; you can redistribute it and/or modify
 11  *  it under the terms of the GNU General Public License version 2
 12  *  as published by the Free Software Foundation
 13  *
 14  *  This program is distributed in the hope that it will be useful,
 15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 17  *  GNU General Public License for more details.
 18  *
 19  *  You should have received a copy of the GNU General Public License
 20  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 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                                 __u8 conn_id, int err)
 40 {
 41         struct nci_conn_info    *conn_info;
 42         data_exchange_cb_t cb;
 43         void *cb_context;
 44 
 45         conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
 46         if (!conn_info) {
 47                 kfree_skb(skb);
 48                 goto exit;
 49         }
 50 
 51         cb = conn_info->data_exchange_cb;
 52         cb_context = conn_info->data_exchange_cb_context;
 53 
 54         pr_debug("len %d, err %d\n", skb ? skb->len : 0, err);
 55 
 56         /* data exchange is complete, stop the data timer */
 57         del_timer_sync(&ndev->data_timer);
 58         clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags);
 59 
 60         if (cb) {
 61                 /* forward skb to nfc core */
 62                 cb(cb_context, skb, err);
 63         } else if (skb) {
 64                 pr_err("no rx callback, dropping rx data...\n");
 65 
 66                 /* no waiting callback, free skb */
 67                 kfree_skb(skb);
 68         }
 69 
 70 exit:
 71         clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
 72 }
 73 
 74 /* ----------------- NCI TX Data ----------------- */
 75 
 76 static inline void nci_push_data_hdr(struct nci_dev *ndev,
 77                                      __u8 conn_id,
 78                                      struct sk_buff *skb,
 79                                      __u8 pbf)
 80 {
 81         struct nci_data_hdr *hdr;
 82         int plen = skb->len;
 83 
 84         hdr = skb_push(skb, NCI_DATA_HDR_SIZE);
 85         hdr->conn_id = conn_id;
 86         hdr->rfu = 0;
 87         hdr->plen = plen;
 88 
 89         nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
 90         nci_pbf_set((__u8 *)hdr, pbf);
 91 }
 92 
 93 int nci_conn_max_data_pkt_payload_size(struct nci_dev *ndev, __u8 conn_id)
 94 {
 95         struct nci_conn_info *conn_info;
 96 
 97         conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
 98         if (!conn_info)
 99                 return -EPROTO;
100 
101         return conn_info->max_pkt_payload_len;
102 }
103 EXPORT_SYMBOL(nci_conn_max_data_pkt_payload_size);
104 
105 static int nci_queue_tx_data_frags(struct nci_dev *ndev,
106                                    __u8 conn_id,
107                                    struct sk_buff *skb) {
108         struct nci_conn_info    *conn_info;
109         int total_len = skb->len;
110         unsigned char *data = skb->data;
111         unsigned long flags;
112         struct sk_buff_head frags_q;
113         struct sk_buff *skb_frag;
114         int frag_len;
115         int rc = 0;
116 
117         pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len);
118 
119         conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
120         if (!conn_info) {
121                 rc = -EPROTO;
122                 goto free_exit;
123         }
124 
125         __skb_queue_head_init(&frags_q);
126 
127         while (total_len) {
128                 frag_len =
129                         min_t(int, total_len, conn_info->max_pkt_payload_len);
130 
131                 skb_frag = nci_skb_alloc(ndev,
132                                          (NCI_DATA_HDR_SIZE + frag_len),
133                                          GFP_KERNEL);
134                 if (skb_frag == NULL) {
135                         rc = -ENOMEM;
136                         goto free_exit;
137                 }
138                 skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
139 
140                 /* first, copy the data */
141                 skb_put_data(skb_frag, data, frag_len);
142 
143                 /* second, set the header */
144                 nci_push_data_hdr(ndev, conn_id, skb_frag,
145                                   ((total_len == frag_len) ?
146                                    (NCI_PBF_LAST) : (NCI_PBF_CONT)));
147 
148                 __skb_queue_tail(&frags_q, skb_frag);
149 
150                 data += frag_len;
151                 total_len -= frag_len;
152 
153                 pr_debug("frag_len %d, remaining total_len %d\n",
154                          frag_len, total_len);
155         }
156 
157         /* queue all fragments atomically */
158         spin_lock_irqsave(&ndev->tx_q.lock, flags);
159 
160         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
161                 __skb_queue_tail(&ndev->tx_q, skb_frag);
162 
163         spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
164 
165         /* free the original skb */
166         kfree_skb(skb);
167 
168         goto exit;
169 
170 free_exit:
171         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
172                 kfree_skb(skb_frag);
173 
174 exit:
175         return rc;
176 }
177 
178 /* Send NCI data */
179 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
180 {
181         struct nci_conn_info    *conn_info;
182         int rc = 0;
183 
184         pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len);
185 
186         conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
187         if (!conn_info) {
188                 rc = -EPROTO;
189                 goto free_exit;
190         }
191 
192         /* check if the packet need to be fragmented */
193         if (skb->len <= conn_info->max_pkt_payload_len) {
194                 /* no need to fragment packet */
195                 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
196 
197                 skb_queue_tail(&ndev->tx_q, skb);
198         } else {
199                 /* fragment packet and queue the fragments */
200                 rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
201                 if (rc) {
202                         pr_err("failed to fragment tx data packet\n");
203                         goto free_exit;
204                 }
205         }
206 
207         ndev->cur_conn_id = conn_id;
208         queue_work(ndev->tx_wq, &ndev->tx_work);
209 
210         goto exit;
211 
212 free_exit:
213         kfree_skb(skb);
214 
215 exit:
216         return rc;
217 }
218 EXPORT_SYMBOL(nci_send_data);
219 
220 /* ----------------- NCI RX Data ----------------- */
221 
222 static void nci_add_rx_data_frag(struct nci_dev *ndev,
223                                  struct sk_buff *skb,
224                                  __u8 pbf, __u8 conn_id, __u8 status)
225 {
226         int reassembly_len;
227         int err = 0;
228 
229         if (status) {
230                 err = status;
231                 goto exit;
232         }
233 
234         if (ndev->rx_data_reassembly) {
235                 reassembly_len = ndev->rx_data_reassembly->len;
236 
237                 /* first, make enough room for the already accumulated data */
238                 if (skb_cow_head(skb, reassembly_len)) {
239                         pr_err("error adding room for accumulated rx data\n");
240 
241                         kfree_skb(skb);
242                         skb = NULL;
243 
244                         kfree_skb(ndev->rx_data_reassembly);
245                         ndev->rx_data_reassembly = NULL;
246 
247                         err = -ENOMEM;
248                         goto exit;
249                 }
250 
251                 /* second, combine the two fragments */
252                 memcpy(skb_push(skb, reassembly_len),
253                        ndev->rx_data_reassembly->data,
254                        reassembly_len);
255 
256                 /* third, free old reassembly */
257                 kfree_skb(ndev->rx_data_reassembly);
258                 ndev->rx_data_reassembly = NULL;
259         }
260 
261         if (pbf == NCI_PBF_CONT) {
262                 /* need to wait for next fragment, store skb and exit */
263                 ndev->rx_data_reassembly = skb;
264                 return;
265         }
266 
267 exit:
268         if (ndev->nfc_dev->rf_mode == NFC_RF_TARGET) {
269                 /* Data received in Target mode, forward to nfc core */
270                 err = nfc_tm_data_received(ndev->nfc_dev, skb);
271                 if (err)
272                         pr_err("unable to handle received data\n");
273         } else {
274                 nci_data_exchange_complete(ndev, skb, conn_id, err);
275         }
276 }
277 
278 /* Rx Data packet */
279 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
280 {
281         __u8 pbf = nci_pbf(skb->data);
282         __u8 status = 0;
283         __u8 conn_id = nci_conn_id(skb->data);
284         struct nci_conn_info    *conn_info;
285 
286         pr_debug("len %d\n", skb->len);
287 
288         pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
289                  nci_pbf(skb->data),
290                  nci_conn_id(skb->data),
291                  nci_plen(skb->data));
292 
293         conn_info = nci_get_conn_info_by_conn_id(ndev, nci_conn_id(skb->data));
294         if (!conn_info)
295                 return;
296 
297         /* strip the nci data header */
298         skb_pull(skb, NCI_DATA_HDR_SIZE);
299 
300         if (ndev->target_active_prot == NFC_PROTO_MIFARE ||
301             ndev->target_active_prot == NFC_PROTO_JEWEL ||
302             ndev->target_active_prot == NFC_PROTO_FELICA ||
303             ndev->target_active_prot == NFC_PROTO_ISO15693) {
304                 /* frame I/F => remove the status byte */
305                 pr_debug("frame I/F => remove the status byte\n");
306                 status = skb->data[skb->len - 1];
307                 skb_trim(skb, (skb->len - 1));
308         }
309 
310         nci_add_rx_data_frag(ndev, skb, pbf, conn_id, nci_to_errno(status));
311 }
312 

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