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Linux/net/nfc/nci/data.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  *  The NFC Controller Interface is the communication protocol between an
  4  *  NFC Controller (NFCC) and a Device Host (DH).
  5  *
  6  *  Copyright (C) 2011 Texas Instruments, Inc.
  7  *  Copyright (C) 2014 Marvell International Ltd.
  8  *
  9  *  Written by Ilan Elias <ilane@ti.com>
 10  */
 11 
 12 #define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
 13 
 14 #include <linux/types.h>
 15 #include <linux/interrupt.h>
 16 #include <linux/wait.h>
 17 #include <linux/bitops.h>
 18 #include <linux/skbuff.h>
 19 
 20 #include "../nfc.h"
 21 #include <net/nfc/nci.h>
 22 #include <net/nfc/nci_core.h>
 23 #include <linux/nfc.h>
 24 
 25 /* Complete data exchange transaction and forward skb to nfc core */
 26 void nci_data_exchange_complete(struct nci_dev *ndev, struct sk_buff *skb,
 27                                 __u8 conn_id, int err)
 28 {
 29         struct nci_conn_info    *conn_info;
 30         data_exchange_cb_t cb;
 31         void *cb_context;
 32 
 33         conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
 34         if (!conn_info) {
 35                 kfree_skb(skb);
 36                 goto exit;
 37         }
 38 
 39         cb = conn_info->data_exchange_cb;
 40         cb_context = conn_info->data_exchange_cb_context;
 41 
 42         pr_debug("len %d, err %d\n", skb ? skb->len : 0, err);
 43 
 44         /* data exchange is complete, stop the data timer */
 45         del_timer_sync(&ndev->data_timer);
 46         clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags);
 47 
 48         if (cb) {
 49                 /* forward skb to nfc core */
 50                 cb(cb_context, skb, err);
 51         } else if (skb) {
 52                 pr_err("no rx callback, dropping rx data...\n");
 53 
 54                 /* no waiting callback, free skb */
 55                 kfree_skb(skb);
 56         }
 57 
 58 exit:
 59         clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
 60 }
 61 
 62 /* ----------------- NCI TX Data ----------------- */
 63 
 64 static inline void nci_push_data_hdr(struct nci_dev *ndev,
 65                                      __u8 conn_id,
 66                                      struct sk_buff *skb,
 67                                      __u8 pbf)
 68 {
 69         struct nci_data_hdr *hdr;
 70         int plen = skb->len;
 71 
 72         hdr = skb_push(skb, NCI_DATA_HDR_SIZE);
 73         hdr->conn_id = conn_id;
 74         hdr->rfu = 0;
 75         hdr->plen = plen;
 76 
 77         nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
 78         nci_pbf_set((__u8 *)hdr, pbf);
 79 }
 80 
 81 int nci_conn_max_data_pkt_payload_size(struct nci_dev *ndev, __u8 conn_id)
 82 {
 83         struct nci_conn_info *conn_info;
 84 
 85         conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
 86         if (!conn_info)
 87                 return -EPROTO;
 88 
 89         return conn_info->max_pkt_payload_len;
 90 }
 91 EXPORT_SYMBOL(nci_conn_max_data_pkt_payload_size);
 92 
 93 static int nci_queue_tx_data_frags(struct nci_dev *ndev,
 94                                    __u8 conn_id,
 95                                    struct sk_buff *skb) {
 96         struct nci_conn_info    *conn_info;
 97         int total_len = skb->len;
 98         unsigned char *data = skb->data;
 99         unsigned long flags;
100         struct sk_buff_head frags_q;
101         struct sk_buff *skb_frag;
102         int frag_len;
103         int rc = 0;
104 
105         pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len);
106 
107         conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
108         if (!conn_info) {
109                 rc = -EPROTO;
110                 goto exit;
111         }
112 
113         __skb_queue_head_init(&frags_q);
114 
115         while (total_len) {
116                 frag_len =
117                         min_t(int, total_len, conn_info->max_pkt_payload_len);
118 
119                 skb_frag = nci_skb_alloc(ndev,
120                                          (NCI_DATA_HDR_SIZE + frag_len),
121                                          GFP_KERNEL);
122                 if (skb_frag == NULL) {
123                         rc = -ENOMEM;
124                         goto free_exit;
125                 }
126                 skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
127 
128                 /* first, copy the data */
129                 skb_put_data(skb_frag, data, frag_len);
130 
131                 /* second, set the header */
132                 nci_push_data_hdr(ndev, conn_id, skb_frag,
133                                   ((total_len == frag_len) ?
134                                    (NCI_PBF_LAST) : (NCI_PBF_CONT)));
135 
136                 __skb_queue_tail(&frags_q, skb_frag);
137 
138                 data += frag_len;
139                 total_len -= frag_len;
140 
141                 pr_debug("frag_len %d, remaining total_len %d\n",
142                          frag_len, total_len);
143         }
144 
145         /* queue all fragments atomically */
146         spin_lock_irqsave(&ndev->tx_q.lock, flags);
147 
148         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
149                 __skb_queue_tail(&ndev->tx_q, skb_frag);
150 
151         spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
152 
153         /* free the original skb */
154         kfree_skb(skb);
155 
156         goto exit;
157 
158 free_exit:
159         while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
160                 kfree_skb(skb_frag);
161 
162 exit:
163         return rc;
164 }
165 
166 /* Send NCI data */
167 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
168 {
169         struct nci_conn_info    *conn_info;
170         int rc = 0;
171 
172         pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len);
173 
174         conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
175         if (!conn_info) {
176                 rc = -EPROTO;
177                 goto free_exit;
178         }
179 
180         /* check if the packet need to be fragmented */
181         if (skb->len <= conn_info->max_pkt_payload_len) {
182                 /* no need to fragment packet */
183                 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
184 
185                 skb_queue_tail(&ndev->tx_q, skb);
186         } else {
187                 /* fragment packet and queue the fragments */
188                 rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
189                 if (rc) {
190                         pr_err("failed to fragment tx data packet\n");
191                         goto free_exit;
192                 }
193         }
194 
195         ndev->cur_conn_id = conn_id;
196         queue_work(ndev->tx_wq, &ndev->tx_work);
197 
198         goto exit;
199 
200 free_exit:
201         kfree_skb(skb);
202 
203 exit:
204         return rc;
205 }
206 EXPORT_SYMBOL(nci_send_data);
207 
208 /* ----------------- NCI RX Data ----------------- */
209 
210 static void nci_add_rx_data_frag(struct nci_dev *ndev,
211                                  struct sk_buff *skb,
212                                  __u8 pbf, __u8 conn_id, __u8 status)
213 {
214         int reassembly_len;
215         int err = 0;
216 
217         if (status) {
218                 err = status;
219                 goto exit;
220         }
221 
222         if (ndev->rx_data_reassembly) {
223                 reassembly_len = ndev->rx_data_reassembly->len;
224 
225                 /* first, make enough room for the already accumulated data */
226                 if (skb_cow_head(skb, reassembly_len)) {
227                         pr_err("error adding room for accumulated rx data\n");
228 
229                         kfree_skb(skb);
230                         skb = NULL;
231 
232                         kfree_skb(ndev->rx_data_reassembly);
233                         ndev->rx_data_reassembly = NULL;
234 
235                         err = -ENOMEM;
236                         goto exit;
237                 }
238 
239                 /* second, combine the two fragments */
240                 memcpy(skb_push(skb, reassembly_len),
241                        ndev->rx_data_reassembly->data,
242                        reassembly_len);
243 
244                 /* third, free old reassembly */
245                 kfree_skb(ndev->rx_data_reassembly);
246                 ndev->rx_data_reassembly = NULL;
247         }
248 
249         if (pbf == NCI_PBF_CONT) {
250                 /* need to wait for next fragment, store skb and exit */
251                 ndev->rx_data_reassembly = skb;
252                 return;
253         }
254 
255 exit:
256         if (ndev->nfc_dev->rf_mode == NFC_RF_TARGET) {
257                 /* Data received in Target mode, forward to nfc core */
258                 err = nfc_tm_data_received(ndev->nfc_dev, skb);
259                 if (err)
260                         pr_err("unable to handle received data\n");
261         } else {
262                 nci_data_exchange_complete(ndev, skb, conn_id, err);
263         }
264 }
265 
266 /* Rx Data packet */
267 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
268 {
269         __u8 pbf = nci_pbf(skb->data);
270         __u8 status = 0;
271         __u8 conn_id = nci_conn_id(skb->data);
272         struct nci_conn_info    *conn_info;
273 
274         pr_debug("len %d\n", skb->len);
275 
276         pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
277                  nci_pbf(skb->data),
278                  nci_conn_id(skb->data),
279                  nci_plen(skb->data));
280 
281         conn_info = nci_get_conn_info_by_conn_id(ndev, nci_conn_id(skb->data));
282         if (!conn_info)
283                 return;
284 
285         /* strip the nci data header */
286         skb_pull(skb, NCI_DATA_HDR_SIZE);
287 
288         if (ndev->target_active_prot == NFC_PROTO_MIFARE ||
289             ndev->target_active_prot == NFC_PROTO_JEWEL ||
290             ndev->target_active_prot == NFC_PROTO_FELICA ||
291             ndev->target_active_prot == NFC_PROTO_ISO15693) {
292                 /* frame I/F => remove the status byte */
293                 pr_debug("frame I/F => remove the status byte\n");
294                 status = skb->data[skb->len - 1];
295                 skb_trim(skb, (skb->len - 1));
296         }
297 
298         nci_add_rx_data_frag(ndev, skb, pbf, conn_id, nci_to_errno(status));
299 }
300 

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