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 */
nci_data_exchange_complete(struct nci_dev * ndev,struct sk_buff * skb,int err)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
nci_push_data_hdr(struct nci_dev * ndev,__u8 conn_id,struct sk_buff * skb,__u8 pbf)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 skb->dev = (void *) ndev;
85 }
86
nci_queue_tx_data_frags(struct nci_dev * ndev,__u8 conn_id,struct sk_buff * skb)87 static int nci_queue_tx_data_frags(struct nci_dev *ndev,
88 __u8 conn_id,
89 struct sk_buff *skb) {
90 int total_len = skb->len;
91 unsigned char *data = skb->data;
92 unsigned long flags;
93 struct sk_buff_head frags_q;
94 struct sk_buff *skb_frag;
95 int frag_len;
96 int rc = 0;
97
98 pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len);
99
100 __skb_queue_head_init(&frags_q);
101
102 while (total_len) {
103 frag_len =
104 min_t(int, total_len, ndev->max_data_pkt_payload_size);
105
106 skb_frag = nci_skb_alloc(ndev,
107 (NCI_DATA_HDR_SIZE + frag_len),
108 GFP_KERNEL);
109 if (skb_frag == NULL) {
110 rc = -ENOMEM;
111 goto free_exit;
112 }
113 skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
114
115 /* first, copy the data */
116 memcpy(skb_put(skb_frag, frag_len), data, frag_len);
117
118 /* second, set the header */
119 nci_push_data_hdr(ndev, conn_id, skb_frag,
120 ((total_len == frag_len) ?
121 (NCI_PBF_LAST) : (NCI_PBF_CONT)));
122
123 __skb_queue_tail(&frags_q, skb_frag);
124
125 data += frag_len;
126 total_len -= frag_len;
127
128 pr_debug("frag_len %d, remaining total_len %d\n",
129 frag_len, total_len);
130 }
131
132 /* queue all fragments atomically */
133 spin_lock_irqsave(&ndev->tx_q.lock, flags);
134
135 while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
136 __skb_queue_tail(&ndev->tx_q, skb_frag);
137
138 spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
139
140 /* free the original skb */
141 kfree_skb(skb);
142
143 goto exit;
144
145 free_exit:
146 while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
147 kfree_skb(skb_frag);
148
149 exit:
150 return rc;
151 }
152
153 /* Send NCI data */
nci_send_data(struct nci_dev * ndev,__u8 conn_id,struct sk_buff * skb)154 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
155 {
156 int rc = 0;
157
158 pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len);
159
160 /* check if the packet need to be fragmented */
161 if (skb->len <= ndev->max_data_pkt_payload_size) {
162 /* no need to fragment packet */
163 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
164
165 skb_queue_tail(&ndev->tx_q, skb);
166 } else {
167 /* fragment packet and queue the fragments */
168 rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
169 if (rc) {
170 pr_err("failed to fragment tx data packet\n");
171 goto free_exit;
172 }
173 }
174
175 queue_work(ndev->tx_wq, &ndev->tx_work);
176
177 goto exit;
178
179 free_exit:
180 kfree_skb(skb);
181
182 exit:
183 return rc;
184 }
185
186 /* ----------------- NCI RX Data ----------------- */
187
nci_add_rx_data_frag(struct nci_dev * ndev,struct sk_buff * skb,__u8 pbf)188 static void nci_add_rx_data_frag(struct nci_dev *ndev,
189 struct sk_buff *skb,
190 __u8 pbf)
191 {
192 int reassembly_len;
193 int err = 0;
194
195 if (ndev->rx_data_reassembly) {
196 reassembly_len = ndev->rx_data_reassembly->len;
197
198 /* first, make enough room for the already accumulated data */
199 if (skb_cow_head(skb, reassembly_len)) {
200 pr_err("error adding room for accumulated rx data\n");
201
202 kfree_skb(skb);
203 skb = NULL;
204
205 kfree_skb(ndev->rx_data_reassembly);
206 ndev->rx_data_reassembly = NULL;
207
208 err = -ENOMEM;
209 goto exit;
210 }
211
212 /* second, combine the two fragments */
213 memcpy(skb_push(skb, reassembly_len),
214 ndev->rx_data_reassembly->data,
215 reassembly_len);
216
217 /* third, free old reassembly */
218 kfree_skb(ndev->rx_data_reassembly);
219 ndev->rx_data_reassembly = NULL;
220 }
221
222 if (pbf == NCI_PBF_CONT) {
223 /* need to wait for next fragment, store skb and exit */
224 ndev->rx_data_reassembly = skb;
225 return;
226 }
227
228 exit:
229 nci_data_exchange_complete(ndev, skb, err);
230 }
231
232 /* Rx Data packet */
nci_rx_data_packet(struct nci_dev * ndev,struct sk_buff * skb)233 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
234 {
235 __u8 pbf = nci_pbf(skb->data);
236
237 pr_debug("len %d\n", skb->len);
238
239 pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
240 nci_pbf(skb->data),
241 nci_conn_id(skb->data),
242 nci_plen(skb->data));
243
244 /* strip the nci data header */
245 skb_pull(skb, NCI_DATA_HDR_SIZE);
246
247 if (ndev->target_active_prot == NFC_PROTO_MIFARE) {
248 /* frame I/F => remove the status byte */
249 pr_debug("NFC_PROTO_MIFARE => remove the status byte\n");
250 skb_trim(skb, (skb->len - 1));
251 }
252
253 nci_add_rx_data_frag(ndev, skb, pbf);
254 }
255