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 */
38void 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
70exit:
71	clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
72}
73
74/* ----------------- NCI TX Data ----------------- */
75
76static 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 = (struct nci_data_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
93int 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}
103EXPORT_SYMBOL(nci_conn_max_data_pkt_payload_size);
104
105static 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		memcpy(skb_put(skb_frag, frag_len), 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
170free_exit:
171	while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
172		kfree_skb(skb_frag);
173
174exit:
175	return rc;
176}
177
178/* Send NCI data */
179int 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
212free_exit:
213	kfree_skb(skb);
214
215exit:
216	return rc;
217}
218EXPORT_SYMBOL(nci_send_data);
219
220/* ----------------- NCI RX Data ----------------- */
221
222static 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
267exit:
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 */
279void 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